Genetic exchange across a paracentric inversion of the mouse t complex.

(1)

Copyright 0 199 1 by the Genetics Society of America

Genetic Exchange Across

a Paracentric Inversion of the Mouse t Complex

M. F.

Hammer,’ S. Bliss and L. M. Silver

Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544 Manuscript received January 15, 199 1

Accepted April 27, 199 1

ABSTRACT

Mouse t haplotypes are distinguished from wild-type forms of chromosome 17 by four non-

overlapping paracentric inversions which span a genetic distance of 20 cM. These inversion polymorphisms are responsible for a 100-200-fold suppression of recombination which maintains the integrity of complete t haplotypes and has led to their divergence from the wild-type chromosomes of four species of house mice within which t haplotypes reside. As evidence for the long period of recombinational isolation, alleles that distinguish all t haplotypes from all wild-type chromosomes have been established at a number of loci spread across the 20-cM variant region. However, a more complex picture emerges upon analysis of other t-associated loci. In particular, “mosaic haplotypes” have been identified that carry a mixture of wild-type and t-specific alleles. T o investigate the genetic basis for

mosaic chromosomes, we conducted a comprehensive analysis of eight t complex loci within 76 animals

representing 10 taxa in the genus Mus, and including 23 previously characterized t haplotypes. Higher resolution restriction mapping and sequence analysis was also performed for alleles at the Hba-ps4 locus. The results indicate that a short tract of D N A was transferred relatively recently across an inversion from a t haplotype allele of Hba-ps4 to the corresponding locus on a wild-type homolog leading to the creation of a new hybrid allele. Several classes of wild-type Hba-ps4 alleles, including

the most common form in inbred strains, appear to be derived from this hybrid allele. The accumulated

data suggest that a common form of genetic exchange across one of the four t-associated inversions is

gene conversion at isolated loci that do not play a role in the transmission ratio distortion phenotype required for t haplotype propagation. The implications of the results pose questions concerning the evolutionary stability of gene complexes within large paracentric inversions and suggest that recombinational isolation may be best established for loci residing within a short distance from inversion breakpoints.

V

ARIANT forms of the proximal portion of chro-

mosome 17 known as t haplotypes are polymor-

phic in natural populations of house mice (SILVER

1985; KLEIN 1986). These chromosomal segments

carry mutations that result in the violation of Mendel’s first law. I n a process known as transmission ratio

distortion (TRD), males heterozygous for a t haplo-

type and a wild-type chromosome can transmit the t

haplotype to over 95% of their offspring, whereas

transmission in females is n o r m a l . T R D is a special

case of meiotic drive because both sperm types are

produced in Mendelian proportions, but those carrying the t haplotype have a relative advantage at fertil- ization (OLDS-CLARKE 1986).

t haplotypes share a number of properties with

o t h e r systems of meiotic drive, such as SD a n d SR in

Drosophila (CROW 1988; WU a n d HAMMER 1991),

and represent informative examples of coadapted

gene complexes (DOBZHANSKY 1 9 5 1). In particular,

every meiotic drive system that has been analyzed in

detail involves interactions among closely linked

genes, and chromosomal rearrangements that sup-

’

Present address: Division of Biotechnology, Biosciences West, University of Arizona, Tucson, Arizona 85721.

Genetics 128: 799-8 12 (August, 199 1)

press recombination between these loci. In fact, the- oretical studies predict that recombination suppres-

sors such as inversions will be favored by selection

(THOMSON a n d FELDMAN 1974; CHARLESWORTH a n d

HARTL 1978). In the case of t haplotypes, five loci

that are required for the expression of T R D have

been mapped across the 20-cM t region of chromo-

some I7 (LYON 1984; SILVER and REMIS 198’7). Re-

combination between t haplotype and wild-type alleles

of these loci is suppressed by a series of four non- overlapping paracentric inversions (ARTZT, SHIN and

BENNETT 1982; HERRMANN et al. 1986; SARVETNICK

et al. 1986; HAMMER, SCHIMENTI a n d SILVER 1989).

These inversions have probably been selected for

because only t haplotypes with a complete set of T R D alleles are transmitted at high ratios, and only high

ratio t haplotypes survive for significant periods of

time in natural populations (LEWONTIN and DUNN 1960).

TRD and recombination suppression should lead to

the rapid fixation of t haplotypes in mouse popula-

tions. However, they have been found only at fre-

quencies between 5 and 15% in most populations of

(2)

800 M. F. Hammer, S. Bliss and L. M. Silver

ern European house mouse M u s musculus, and the Far

Eastern species M u s castaneus a n d Mus molossinus

(KLEIN, SIPOS, a n d FICUEROA 1984; KANEDA et al.

1989). Two factors appear to play a role in the pre-

vention of fixation. First, most t haplotypes carry

recessive lethal mutations, with at least 16 different

complementation groups identified in wild mice

(KLEIN, SIPOS, a n d FIGUEROA 1984; KLEIN 1986).

Second, all t haplotypes cause male sterility in animals

with two complementing lethal forms or homozygous for a nonlethal t haplotype.

There is evidence that the origin of t haplotypes predates the divergence of t h e species in which they are found, and that they have existed for at least 2-4

million years (DELARBRE et al. 1988; HAMMER, SCHI-

MENTI and SILVER 1989). Along with the preservation

of allelic combinations at T R D loci, the presence of

the inversions also preserves combinations of variant

alleles of other loci within the region of recombination

suppression. T h e long-term recombinational isolation

has led to DNA sequence divergence and the estab- lishment of alleles that distinguish wild-type chromo-

somes and t haplotypes. For example, DNA sequences

from the noncoding regions of t complex protein-1

( T c p - I ) , DNA segment Lehrach 122 (DI7Leh122),

and a-globin pseudogene-4 (Hba-fd) demonstrate a

wild-typelt haplotype divergence of 1-2% (FRISCHAUF

1985; WILLISON, DUDLEY a n d POTTER 1986; M. F.

HAMMER and L. M. SILVER, unpublished results). In

addition, a number of protein-coding and anonymous DNA loci have alleles that are associated exclusively with t haplotypes (SILVER et al. 1983, 1987; Fox et al.

1985). However, there are a number of exceptions to

the patterns just described. At certain loci, alleles have

been found that are shared between t haplotypes and

wild-type chromosomes (DEMBIC, SINGER a n d KLEIN

1984; SKOW et al. 1987; NADEAU a n d PHILLIPS 1987).

These exceptions present interesting evolutionary

problems. Some authors have interpreted the exist-

ence of mosaic chromosomes (those carrying a mixture of wild-type alleles a n d t-like alleles) as evidence

for the persistence of ancestral polymorphism that was

present in the population that gave rise to t haplotypes

(FIGUEROA et al. 1988; ERHART et al. 1989). Alterna-

tively, mosaic chromosomes may be the result of rare

recombination between contemporary t haplotypes

a n d wild-type chromosomes (ERHART et al. 1989).

This would imply that t haplotypes could be disassem- bled and would raise questions concerning the stability

of coadapted gene complexes in evolution.

H e r e we present an investigation of mosaicism a t t h e Hba-ps4 locus mapping to the most distal inversion o f t haplotypes. The data provide evidence for a recent genetic exchange between t haplotypes and wild-type

chromosomes as the cause of mosaicism at this locus.

MATERIALS A N D METHODS

Mice: Table 1 lists the geographic origins and sources of

76 animals representing 10 taxa from 29 localities. The survey includes 11 laboratory strains (see Table 1 legend), 1 1 mice trapped in the wild, and 3 1 laboratory descendants

of separate lines of wild-caught mice. In addition, 23 lines

of mice carrying independent t haplotypes were examined.

Genomic DNA purification and analysis: DNA was prepared from tissues that were kept at -20" until used.

High molecular weight DNA was isolated according to

standard procedures. Two micrograms of genomic DNA

was digested to completion with Tag1 restriction endonucle-

ase (New England Biolabs), the fragments were size fraction- ated by 0.8% agarose gel electrophoresis and transferred to nylon membranes (GeneScreen, New England Nuclear) and baked according to the manufacturer's specifications. The DNA was covalently bound to the nylon by exposure to 254 nm light.

DNA probes and hybridization: The following recombinant plasmids were used as molecular probes to study selected chromosome I 7 loci. Three obtained by microdis-

section-Tu48, Tu1 19, Tu89-define the loci Dl 7Leh48,

Dl7Lehll9, DI7Leh89, respectively (ROHME et al. 1984). A

cosmid subclone (Bb-40) is used to define Dl 7Leh66b (SCHI-

MENTI et al. 1987). A genomic fragment 0.7 kilobase (kb) upstream to Tcp-I gene (probe 29X) was kindly provided by K. WILLISON (WILLISON, DUDLEY and POTTER 1986). A

0.92-kb BamHI fragment containing portions of exon 5 and

6 and the intervening intron of the Pim-1 gene was provided by A. BERNS (CUYPERS et al. 1984).

T h e a-globin pseudogene-4 (Hba-ps4) and the a-A crystallin

(Crya-I) genes were isolated from a homozygous genomic

library derived from cell line DNA and kindly provided by

JOHN SCHIMENTI. Lambda clones containing these sequences

were isolated, digested with EcoRI and BamHI for subclon-

ing into pBR322. Four Hba-ps4 region subclones of 1.6, 1.3, 1 and 0.6 kb are shown in Figure 3 and referred to as Hba-6, -7, -9 and -1 1, respectively. Hba-6 and Hba-9 span a

2.6-kb region within and immediately surrounding the Hba-

ps4 pseudogene. Hba-7 and Hba-1 1 define a region of DNA

that lies 3-6 kb downstream from the pseudogene. This

entire region will be considered as a single locus. A Crya-2

Barn HI-Bam HI subclone of 0.6 kb was used in this study and is referred to as Cry-1 0.

Radioactive probes were produced by polymerization

from a mixture of random oligonucleotide primers on tem-

plates of denatured DNA (FEINBERG and VOGELSTEIN

1983). Hybridization to nylon membranes was performed

according to the procedure of CHURCH and GILBERT (1 984).

DNA sequencing: The 2.6-kb insert of the BALB/cJ Hba- ps4-containing plasmid (LEDER et al. 1981) and the sub-

cloned fragments Hba-9 and -6 were annealed to gene

specific oligonucleotide primers spaced at 200-400-bp in- tervals and sequenced using the double stranded sequencing method of BARTLETT, GAILLARD, andJoKLIK (1 986). A 1.4- kb region of PCR-amplified D N A from the DEAl allele of Hba-ps4 was also sequenced using this method. Y . NISHIOKA

initially provided 1.3 kb of the unpublished BALB/cJ Hba-

ps4 sequence.

High resolution restriction analysis: Three micrograms of genomic DNA were digested to completion with 1 of 1 1

(3)

Genetic Exchange in the t Complex

TABLE 1

Sources of mice subjected to restriction enzyme analysis

80 1

Mouse number and kind Geographic origin Source"

M. domesticus 1 2 :3 4 5 6-8 9-1 0

1 1 12-13 14-16 17 18 19 20-2 1

22-23 24-29 :30-3 1 32

M . musculus

3 3

3 4

3 5

36 37 38 39 M. castaneus 40 41 42 43 44

M . molossinu.!

M. bactrianw M. abbotta 45 46 BALB/cJ CSH/HeJ 1 29/sv C57BllO/J

S M/J DME DMA I)I H I CJ

D1J D I T WMP/PAS DPL DEA DEA DES DEG DEW PWK/PAS MCB MCS MYB MA1 MPW MDS CASA/RK C T T

MOLC/RK BI0.BACI BlO.BAC2 XBS AYG Laboratory Laboratory Laboratory Laboratory Laboratory Morocco, Erfoud Morocco, Azrou Israel, Haifa Israel, Jerusalem Israel, Jerusalem Italy, Tirano Tunisia, Monastir Peru, Lima Egypt, Abu Rawash Egypt, Abu Rawash Egypt, Saqqara

Egypt, Giza, near Bashtil Egypt, Wadi El Naturn

C7echoslavakia, Prague Czechoslavakia,

Bratislava Czechoslavakia,

Studenec. Yugoslavia, Belgrade Austria, Illmitz Poland, Warsaw Denmark, Skive

Thailand, Thon Buri Thailand, Thon Buri

Japan, Kyushu

Pakistan, Lahore Pakistan, Lahore

Bulgaria, Slantchev Briag Yugoslavia, Gradsko

1 1 1 1 1 2 2, 3 4 4 2, 4 2 5 3 2 7 7 7 7 5 2 2 4 2 2 2 1 3 1 12 12 4 3

-

" Inbred laboratory strains were provided by T h e Jackson Laboratory, Bar Harbor Maine (1) and J. L. GUENET ( 5 ) ; laboratory raised

descendents of wild-caught individuals were provided by MICHAEL POTTER (2), R. D. SAGE ( 3 ) , V . CHAPMAN (4). U . RITTE ( 6 ) ; and wild- caught mice were provided by I,. D'HOOSTELAERE (7). t haplotypes were from Princeton (8) o r provided by J. KLEIN (9). H. WINKING ( I O ) , J. FOREIJT (1 1). T h e congenic inbred strains from M . bactrianus were provided by K. FISCHER-LINDAHL (1 2). All t haplotypes were maintained a s congenic strains except tTU"" a n d t"' which were t l t . For further details on the original collection of mice see FERRIS et al. (1983) and

POTTER, NADEAU and CANCRO (1986).

M . hortulanus

47 HAH

48 HYP

49 SSC

5 0 SSG

51 SMA

52 C v T

5 ?l COT

54 t "

55 56 57

58 t ( I

59 t" 2 60 t" 5 61 y l ?

6 2 t"'3? M. spretus

M . cervicolor

M. caroli

t haplotypes t l . h l

lu6 J

I lrr<,X

6 3

64

t ~ r l , , c ' 7 ( ~

I !,X 27

65

66 to4

67 68 69 70

71 tl>,h4 72

73

74 tl""U

75 t'l""'l I 76

l-aW2Y

ru,m

t"7'

l - u l l z h

I,," 20

l u h 5 t l t < h h

I i w 2 4

Austria, Halbturn Yugoslavia, Pancevo

Spain, Cadiz Spain, Granada Morocco, Azrou

Thailand, Chon Buri

Thailand, Loei

Laboratory Italy, Alpic Drobic Italy, Ardenno Egypt, Giza France, Paris USA, Philadelphia USA, New York USA, California USA, Montana USA, Michigan Federal Republic of Ger- many, Dudelhof Federal Republic of Ger- many, Erpenhausen Czechoslavakia, Lhotka Czechoslavakia, Brno

Denmark, S. Jutland

Poland, Bialowieza USSR, Ryazan,

Astrachan Italy, Cremona Italy, Caneto, Pavese Italy, Luino Italy, Calcinato Chile, Buin

Federal Republic of Ger- many, Langenargen

2 3 3 4 2 2 2 8

I 0 10 9 8 8 8 8 8 9 9 9 11 9 8 9 9 10 10 10 10 9 9

analyzed by polyacrylamide gel electrophoresis (KREITMAN

and ACUADE 1986). Each fragment pattern produced by a given enz me was assigned a capital letter, with A being reserved

?

or the pattern appearing in the known BALB/cJ Hba-ps4 sequence. Cleavage maps for each enz me were constructed by the sequence comparison m e t h o J i n which one maps the sites needed to account for each fragment pattern by comparison with the known sequence (FERRIS et al. 1983).

RESULTS

Variation at t complex loci: DNA probes for eight loci mapping to the t complex were used in a survey

of TaqI restriction sites in 23 previously described,

independently obtained t haplotypes, 9 inbred laboratory strains (listed in the legend to Table l ) ,

2

congenic lines containing a segment of chromosome

17 derived from Mus bactrianus, 3 2 wild-derived and wild-caught M. domesticus and M. musculus, as well as individuals representing

7

other species in the genus Mus (Table 1). T h e positions occupied by these loci within the t complex are shown in Figure 1. The results of the survey are shown in the APPENDIX (Table

(4)

802 M. F. Hammer, S. Bliss and L. M. Silver

Wild-type

t haplotype

T R D b c i : D l D4 R D3 D2

CM: 2 4 6 8 10 12 14 16 18

FIGURE 1 .-Positions occupied by eight loci and four inversions within the mouse t complex. The centromere is depicted by the solid circle and the four chromosomal inversions by the shaded boxes (relative orientation on wild-type and t haplotypes indicated by slanted lines). The eight loci examined in this survey and their positions within the t complex are shown. The symbols 48, 119,66, Hba, Pim, Cry and 89 represent D l 7 L e h 4 8 , D I 7 L e h l l 9 , D 1 7 L e h 6 6 ,

Hba-ps4, Pim-1, Crya-1 and Dl 7Leh89, respectively. Also shown are

the five loci involved in transmission ratio distortion and the scale in centiMorgans.

characterized by at least one restriction fragment variant between wild-type and t haplotypes (APPENDIX, Table 4), and these variants define separate restriction fragment length polymorphism (RFLP) alleles. Alleles found in previously characterized t haplotypes and absent from all wild-type chromosomes are called t- specific.

Five patterns of variation are detected among the 8 loci: (1) at D17Leh48, D17Leh119, D17Leh89, and

Hba-ps4 (detected with probes Hba-7 and Hba-1 l ) , a

single t-specific allele is shared by all t haplotypes; (2) at the D17Leh66 locus (detected with the Bb40 probe), two t-specific alleles are carried by different t haplotypes; (3) at Pim-1, a single t-specific allele is present in a subset o f t haplotypes, and all others have an allele shared by some wild-type chromosomes; (4) at Tcp-1

(and at Hba-ps4 as detected with probes Hba-6 and Hba-9), an allele shared by all t haplotypes is present on some wild-type chromosomes; and (5) at Cry-1, three alleles present in t haplotypes are all found in wild-type chromosomes.

Six DNA probes, Tu48, Tu1 19, Tu89, Hba-7, Hba- 11 and Bb-40, identify RFLP alleles that distinguish all t haplotypes from all wild-type chromosomes of the house mice examined in this survey. Only these probes are “informative” in detecting t-specific alleles and determining whether chromosomes collected from wild-mice are complete (with all four inversions) or partial t haplotypes (missing one or more inversions).

The probes used to detect Tcp-I and Crya-I alleles failed to identify t-specific variants (Figure 2). All t

haplotypes examined carry the Tcp-I allele producing pattern 1 which was found in 80% of M . domesticus mice. T h e Tcp-I allele producing pattern 2 was identified in 20% of M . domesticus and 100% of M . musculus mice. This contrasts with the results of two- dimensional protein electrophoresis (SILVER et al.

1983) and restriction fragment patterns analyzed with Tcp-1 cDNA (WILLISON, DUDLEY and POTTER 1986) where all t haplotypes were found to be associated

40 119 Tcpl 66 Hbae Hba7 Plm Cry 89

I 1 1

*’

1 I 1 2 4 5 7 I

I 1 I 2 1234 1 2 3 I 2 2 4 7 I 2

1 1 1 1 1 1 2 4 1

1 1 2 2 1 2 2 4 1

1 1 2 5 3 2 1 4 5 3 4 5 %

1 h l p l o t w 3

M. d o m l i c u s

D U l

x

S M l J

M. musculus

M. castamus

-

’

M. m/ossiflur

1 1 1 6 7 2 2 1 3 7

1 1 2 . 5 3 2 1 5 4

Ourgroups

2 I 2 2 3 4 8910 3 2 1 3 1258 9101112

FIGURE 2.--Summary of the Tag1 restriction patterns for eight t-complex loci. Abbreviations are the same as used in Figure 1 . Each box represents the pattern obtained with a separate probe hybrid- izing in the vicinity of a particular locus. The type of filling repre- sents restriction fragment patterns which are assigned numbers

(APPENDIX, Table 3). The results for t w o non-overlapping portions of the Hba-ps4 region are shown separately. Solid boxes indicate a restriction pattern uniquely associated with t haplotypes whereas other types of filled boxes represent restriction patterns associated with wild-type chromosomes.

with one variant, and all wild-type chromosomes were associated with another. t haplotypes carry three alleles of Crya-I producing fragments 4 (46%),

7

(42%) and 5 (1

2%).

The majority of M . domesticus animals have the allele producing fragment 4 (94%), whereas 6% have the allele producing fragment 7. For M .

musculus, equal numbers of mice were found with alleles producing fragments 4 and 5.

T h e conclusions of SKOW et al. (1987) regarding the Crya-1 locus differ in some regards from this report. Using a cDNA probe and several restriction enzymes, they found the majority of t haploptypes surveyed to be associated with an allele they considered to be t-specific (Crya-1‘). We have reexamined three t haplotypes with the “Crya-1‘” allele (t“’, tm3’,

and t”’7’) and have found that all three carry the allele

producing fragment 7 which is also present in 6% of wild-type M . domesticus chromosomes. Thus the Crya- I‘ allele can no longer be considered t-specific. T h e Crya-I” allele corresponds to the class of chromosomes that carry the allele producing fragment 4 in our survey.

(5)

Genetic Exchange in the t Complex 803

TABLE 2

Tag1 alleles and restriction patterns for the Hba-ps4 region and

four informative loci

Hba-ps4 region

Informative

Mouse number” and kind loci* Hba9 Hba6 Hba7/1 1‘ alleled

M . domesticus

Wild-type

2 5 , 24, 25

1 , 2, 3, 6-8, 12-16, 19, 24, 26, 27, 30, 3 1 , 32 4 , 1 1 , 17-18, 28, 29 9, 10

20, 25, 31 (DEA1) 5 , 22 (SWJ) Mosaic

t haplotypes

8, 10,21-23, 27-29,32

33-39 M . musculus

M . castaneus

40 41

M . molossinus

42

43 (BlO.BAC2) M . bactrianus

t haplotypes‘

M . abbotti

56-63,68-72

45-46

47-48

M . spretus

49-51

M . cervicolor

52 M . hortulanus

M . caroli

53

+

3 1 2 d l

+

1 1 2 a

+

2 2 2 b

+

3 1 1 d2

+

t t 1 c l

+

t t 2 c 2

t t t t t

+

3 12 d l

+

1 1 2 a

+

2 2 2 b

+

3 21 d l

t t t t t

+

3 1 2 d l

+

3 1 2 d l

+

3 1 2 d l

+

4 1 3 e

+

5 1 2 f

4).

Numbers refer to fragments listed in APPENDIX (Tables 3 and

a Individuals listed twice are heterozygous.

The loci D l 7Leh48, Dl 7Lehl19, D17Leh66 and D l 7Leh89 have alleles that distinguish all characterized t haplotypes from wild-type chromosomes. t represents t-specific alleles at all four loci and

+

represents wild-type alleles at all four loci (see APPENDIX, Table 3, and text).

‘ Hba-7 and Hba-1 1 results are shown in a single column because they span adjacent regions and hybridize the same restriction frag- ments.

Alleles named on basis of RFLPs with probes Hba6, Hba9, Hba7/11 (see Figure 3).

Previously characterized t haplotypes.

al. (1988) speculated that they had recovered a t haplotype from this subspecies based on the presence of the 5.2-kb TaqI allele of Hba-ps4.

Mosaic chromosomes: Chromosomes associated with both t-specific and wild-type alleles have been referred to as mosaic (ERHART et al. 1989). A subset of these chromosomes may be equivalent to partial t

haplotypes, which are generated by rare crossing over between complete t haplotypes and wild-type chromosomes. However, it is difficult to explain the origin

of some mosaic chromosomes by simple recombination events alone when wild-type and t-specific alleles are found to be intermingled. Mosaic chromosomes of the latter type were identified with the use of DNA probes hybridizing to two loci, Pim-1 and Hba-ps4

(Figure 2). Seven of 23 t haplotypes were found to carry a Pim-I restriction fragment pattern indistin- guishable from that associated with all wild-type M .

domesticus chromosomes. These results agree with the

findings of NADEAU and PHILLIPS (1 987).

Previous studies on Hba-ps4 identified a series of

TaqI alleles associated with wild-type chromosomes

and showed that a 5.2-kb TaqI fragment was shared by all t haplotypes (FOX, SILVER and MARTIN 1984; SILVER et al. 1987). Three distinct wild-type Hba-ps4

alleles have been identified with the use of the restriction enzyme TaqI (D’EUSTACHIO et al. 1984; FOX, SILVER and MARTIN 1984; DELARBRE et al. 1988);

Hba-ps4“ is associated with 3.8- and 1.4-kb TaqI frag-

ments, Hba-ps4‘ is associated with a 3.4-kb TaqI fragment, and a third allele is associated with 2.0- and 1.4-

kb Tag1 fragments (defined as H b ~ - p s 4 ~ ; Table

2).

In the present study, the 5.2-kb Hba-ps4‘ was found in association with all 23 t haplotypes examined. How- ever, this allele was also found in the inbred wild-type strain SM/J (mouse number 5) as well as four wild- derived mice that carried no other t-specific alleles (mice numbers 20, 22, 25 and 31: DEA1, DEA3, DES2 and DEG2; see Table 2 and Figure

2).

By the definition of ERHART et al. (1989), all five of these mice carry mosaic chromosomes. These results may be interpreted in two ways. First, it is possible that a single point mutation(s) occurred recently in one or more wild-type chromosomes to give rise to a 5.2-kb

TaqI fragment independent o f t haplotypes. This iden-

tity by “coincidence” can easily be accounted for by any mutation which eliminates the TaqI site located between the 3.8- and 1.4-kb fragments characteristic of the wild-type Hba-ps4” allele (Figure 3). Alterna- tively, the DNA sequences surrounding this site could be identical by descent and indicative of the presence of t-like regions within otherwise wild-type chromosomes. It is possible to distinguish between these two interpretations through an analysis of additional restriction site polymorphisms in the vicinity of the TaqI

sites responsible for the 5.2-kb fragment. In a previous study, we used such an analysis to demonstrate a single point mutation as the likely explanation for the presence of the 5.2 kb Tag1 fragment in loose linkage with the partial t haplotype tTUw3* (SILVER et al. 1987).

Tag1 site variation in the vicinity of Hba-ps4: The

(6)

804 M. F. Hammer, S. Bliss and L. M. Silver

2 1 I 1 1 1 . I

,

a

3 1 I c I 1 . I I b

4 1 1 I

I .

. I I d2

Mosaic

5 1

. .

1 . I , 1 c1

6 1

.

1 1 .I 1 c2

I haplotype

7 1

.

I , 1 1 I 1

1 1 1 1 1 1 1 1 1 I I 1 1

0 2 4 6 8 10 12

kilnbases

FIGURE 3.-DNA probes and restriction sites in the vicinity of

the Hbu-ps4 locus. (A) Restriction map of the tu' genomic clone. All

Eco RI (R), BamHI (B) and TuqI (T) sites within a 12-kb region

surrounding the Hbu-ps4 locus are shown. The small open boxes

represent the three open reading frames of Hbu-ps4. The solid

black bars, numbered 9, 6, 7 and 11, represent four genomic

subclones-Hba9, Hba6, Hba7 and Hba 1 1-that were used as probes.

(B) TaqI map of the Hbu-ps4 region derived from Southern analysis

of genomic DNA. TuqI sites are numbered T1-T8 and indicated

by vertical lines; an asterisk indicates the absence of a TuqI site.

The seven Tag1 haplotypes are referred to as alleles with the

designated letters and numbers (shown on right). The relationships between allele names shown here and specific restriction fragment sizes listed in APPENDIX (Table 4) are indicated in Table 2.

3). Haplotype #1 represents a subset of the H b q "

class and is found in all taxa including the more distantly related species Mus abbotti, Mus hortulanus and Mus spretus. This haplotype is considered to be ancestral and will be referred to as Hba-ps#'. Haplo- type #2 (Hba-psC), #3 (Hba-ps4') and #4 (named Hba-

p ~ 4 ~ ' here) could all be derived from H b ~ - p s 4 ~ ' by a

single site loss ( T 2 , T 3 and T 5 , respectively; Figure 3). Haplotype

#7

(Hba-ps4') was found uniquely in association with all previously characterized t haplotypes, and differs from all other haplotypes by a site gain at T6. The mosaic chromosomes, defined above on the basis of the 5.2-kb "t-fragment," are divided into two groups-haplotypes #5 (Hba-ps4"') and #6 (Hba-ps4")-based on polymorphisms in TaqI sites detected by probes Hba7 and Hbal l.

High resolution restriction maps: Eleven restriction enzymes were used to obtain high resolution maps (HRM) of a 2.6-kb EcoRI fragment of DNA (spanning probes Hba-9 and Hba-6) within and immediately surrounding the Hba-ps4 locus from 14 mice (APPEN- DIX, Table 5). A total of 8 different cleavage patterns were identified and analyzed in conjunction with the nucleotide sequence for BALB/cJ. Restriction maps were inferred for over 100 sites within each genomic DNA sample (data not shown). A comparison of Hba- ps4 restriction maps obtained with a wild-type BALB/

CJ chromosome (Hba-ps4"), a complete tw5 haplotype

(Hba-ps4')), and the five mosaic chromosomes (Hba-

Ps4" and Hba-ps4") is shown in Figure 4A. There are

a total of 15 variable sites (1 1 restriction enzyme differences and 4 length polymorphisms) among the maps obtained. Fourteen of these sites differ between t"' and BALB/cJ. There are two classes of HRM for

Hba-ps4 alleles on mosaic chromosomes that are con-

sistent with the allelic designation on the basis of TaqI

sites: the two mosaic chromosomes with an Hbu-ps4"

allele (SM/J and DEA3) share the same HRM, as do the three chromosomes with the Hba-psC' allele (DEA1, DES2 and DEG2). These two HRMs are distinguished from one another at 4 sites. In addition, these maps are distinguishable from that of Hba-ps4'

by

7

sites (Hba-ps4") and 5 sites (Hba-ps4").

Further examination of the HRMs reveals the existence of nested sets of shared sites among the maps

of Hba-ps4", H ~ u - P s ~ ' ~ and tw5 in the 3' region (indi-

cated by the open lines in Figure 4A), and a similar sharing of sites occurs among the maps of Hba-ps4",

H ~ U - P S ~ ' ~ and BALB/cJ in the 5' region (indicated by

shaded lines in Figure 4A).

M. domesticus chromosomes previously classified with the most common wild-type allele ( b ) can be subdivided into three closely related groups based on HRMs (Figure 4B). All three maps share a 3' cluster of restriction sites with each other, with the maps of the mosaic chromosomes, and with that of tW5. In fact, the HRM of the wild-type inbred strain B10 is indis- tinguishable from the HRM of the mosaic chromosome SM/J. T h e sharing of clusters of sites is sugges- tive of one or more recent genetic exchange events between progenitors to the various chromosomes analyzed here.

DNA sequence comparisons between wild-type, t haplotype and mosaic chromosomes: T o further investigate the possibility of genetic exchange events, DNA sequences were determined for the Hba-ps4

locus present in BALB/cJ, tw5, and the mosaic chromosome DEAl (data not shown). T h e wild-type (BALB/cJ) and t haplotype sequences differ at 18 positions in a 1072 bp region (Figure 5A). When the DEAl Hba-ps4 sequence is compared to the others, a boundary is observed between nucleotides 5 10 and 675. In the region 5' to this boundary, DEAl is identical to BALB/cJ at 5 of the 6 sites that distinguish BALB/cJ from tw5; in the region 3' to this boundary, DEAl is identical to tW' at 11 of the 12 sites that distinguish wild-type and t chromosomes (see boxed- in regions in Figure 5A). This boundary contains the putative 5' breakpoint of a genetic exchange between wild-type sequences and t haplotypes.

(7)

Genetic Exchange in the t Complex 805

~ I I I I I I ~ I I I I I I I I I I ”

1 2 3 4 5 6 7 8 9 1011 12 13 14 15 FIGURE 4.-High resolution re-

A striction maps of the Hba-ps4 locus

n for BALB/cJ, and mosaic chro-

mosomes. T h e locations of polymor- phic restriction sites detected in ge-

nomic DNAs with eleven enzymes

are shown with a vertical line and a letter or number designating the enzyme Hue111 (H), Sau3AI (3). Hphl

(P). Tag1 (T), S c r f f (S), Ddel (D), RsaI

(R). HinfI (F), Ah1 (A). Length variation is indicated with inverted tri- angles. FAch variable site is given a number (1-15; site 8 is equivalent to T 3 in Figure 3B). Regions with ho-

mology to BALB/cJ are indicated

with shaded lines, and regions with homology to 1”” are indicated with open lines. (A) Restriction maps for

BALB/cJ. tu” and mosaic chromo-

somes with a 5.2-kb Tag1 fragment. T h e allelic designation is shown in parentheses. (B) Restriction maps for alleles with the 3.4-kb TaqI fragment

(Hba-ps4’). ( C ) Restriction maps for

two alleles of M . castaneus.

tended in the 3’ direction through analysis with the probes Hba7 and Hbal 1 (APPENDIX, Table 4A). Ho-

mology between DEAl and t”” continues through two informative sites to the 5-kb position in Figure 5B. At position 10 kb in Figure 5B, the situation reverses with identity between DEAl and BALB/cJ at all four informative sites. Therefore, the length of the region of homology between DEA 1 and tu’’ measures between 2 and 6 kb.

DISCUSSION

Wild-type M . domesticus chromosomes can carry a t-like form of Hba-ps4: Wild-type chromosomes recovered from the inbred strain SM/J and mice living in several Egyptian localities carry the 5.2-kb TaqI

allele of Hba-ps4 that is characteristic of all well- defined complete t haplotypes (Hba-ps4‘). All of the other loci examined on these Egyptian chromosomes have non-t haplotype alleles (Figure 2). Previous studies demonstrated that the 5.2-kb Tag1 fragment could arise independently of t haplotypes (SILVER et al. 1987). T o determine the relative relationship of an Egyptian Hba-ps4 allele (from the DEAl strain; the allele is named Hba-ps4’) to wild-type and t-alleles at this locus, these three sequences were compared by high resolution restriction mapping and DNA sequencing. T h e results demonstrate a strong homology between Hba-ps4“ and Hba-ps4‘ that is restricted to a region of DNA of 2-6 kb in length (Figure 5). Se- quences flanking both sides of this t-homologous region are much more homologous to that of the standard wild-type chromosome from the inbred strain

BALB/cJ. Two other Egyptian mice recovered from

nearby localities (DES2 and DEG2, Table 1) carry the same Hba-ps4” allele by the criteria of HRM. A number of other wild-derived and inbred mice carry Hba- ps4 alleles that are very similar to Hba-ps4“ with homology to Hba-ps4‘ over a somewhat shorter (by 400-500 bp) length of DNA. T h e true mosaic nature of all of these otherwise wild-type chromosomes is demonstrated by the existence of short DNA segments with multiple informative sites showing strong homology to t haplotypes. These chromosomes-the only class of “wild-type” mosaic chromosome identified in our survey-represent 14% of the 22 chromosomes sampled directly from wild mice. This differs from the study of ERHART et al. (1989) in which several classes of mosaic chromosome were found and repre- sented 45% of all chromosomes recovered from wild mice.

Genetic exchange between t haplotypes and their wild-type homologs: There are two explanations for the presence of mosaic chromosomes in populations of wild mice. t-like alleles on wild-type chromosomes could represent persisting polymorphisms that existed in the common population that gave rise to t haplotypes and present-day wild-type chromosomes. Assum- ing that barriers to recombination did not preexist in this ancestral population, such alleles would be expected to be shared by the progenitors to both wild- type chromosomes and t haplotypes. An alternative explanation is that recombination between complete t

haplotypes and their wild-type homologues has occurred relatively recently, well after the appearance of the inversion polymorphism.

(8)

M. F. Hammer, S. Bliss and L. M. Silver

806

A

BALB/cJ

DEAl

t w 5

B

C G G C T T A GA A T GGTAA

G$G G C C C G -2 AG T C A A C G

I I _I _I

A A C G T T C G -2 AG T CAACGC

5' exchange poinl 3' exchange point

C

I

BALB/cJ DEAl

L_.___._..._....__._ m U I

R A: R

R A T

1 w 5 _... : T A

DEAl

S M / J p

DES5

-

1 ~ 1 1 1 ~ 1 1 1 1 1

2 4 6 8 10

kilobases

FIGURE 5.-DNA sequence and restriction site comparisons of the Hba-ps4 region among BALB/cJ, tW5 and the mosaic chromosome from DEAl. (A) Variable nucleotide positions are shown for 1072 bp (scale in base pairs shown at top) including the 5' flanking region and open reading frames 1 and 2 of Hba-ps4. T h e first box

shows a region where DEAl and BALB/cJ are identical at five out

of six nucleotide positions and the second box shows a region where

DEAl and tU5 are identical at ten out of eleven nucleotide positions. (B) Variable restriction sites in the 3' flanking region. T h e sequenced region and the two boxes from (A) are shown under the bracketed line. T h e region of homology between DEAl and t W 5 is extended by the sharing of RsaI (R) and AluI (A) sites. A region of undetermined homology is indicated with dotted lines and includes a Taql site (T) that is absent in DEAl and shared between BALBc/ J and tW5. A region of shared restriction sites between DEAl and

BALB/cJ is indicated with a box on the far right of the diagram.

( C ) t-homologous regions carried by DEA 1, SM/J and DES5 chro-

mosomes. T h e line indicates wild-type regions and the solid box indicates homology with t haplotypes. T h e open portion of the box indicates regions of undetermined homology. T h e scale for (B) and (C) is shown at the bottom in kilobases.

predictions of the former model. First, the mosaic chromosomes do not carry a mixture of wild-type and t-specific alleles at several loci as might be expected if they were descended directly from the population giving rise to t haplotypes. Second, shared ancestral alleles would be expected to diverge such that base substitutions would occur randomly throughout the Hba-ps4 region. In contrast, the results demonstrate a clustering of shared enzyme sites between tw5 and the mosaic chromosomes. This clustering is highly significant at the level of DNA sequence as shown in Figure 5A, and provides strong support for the model of a recent genetic exchange as an explanation for the mosaic chromosomes reported here. T h e low level of

sequence divergence between DEAl and within the region of shared sites (0.02%) compared to the

1.8% sequence divergence between tw5 and BALB/cJ gives further evidence that the genetic exchange event occurred recently relative to the event giving rise to the inversion.

Gene conversion: T h e position of Hba-ps4 within the distal inversion (Figure 1) makes the possibility of recovering the products of single crossover events in the vicinity of the pseudogene extremely unlikely. Single crossovers within paracentric inversions lead to inviable zygotes through the production of acentric and dicentric chromosomes. Exchanges of genetic ma- terial across inverted regions of t haplotypes are more likely due to double recombination or gene conversion.

Two lines of evidence suggest that the Hba-ps4" allele was created by gene conversion rather than by double crossing over. First, the length of the DNA exchanged between a t haplotype and the progenitor of the DEAl chromosome is between 2 and 6 kb. The probability of two crossover events occurring within this length of DNA is practically zero because strong positive interference will act over such short distances (KING et al. 1989). On the other hand, gene conversion events typically involve short tracts of DNA. T h e average length of conversion tracts at the rosy locus of D. melanogaster were shown to be 1208 f 790 bp (CURTIS et al. 1989). This is similar to measurements of the average meiotic conversion tract lengths in yeast which range from 0.7 kb to over 2 kb (BORTS and HABER 1989).

Second, there is evidence from experiments with D. melanogaster that the majority of recombinants from inversion heterozygotes are the products of gene con- versions rather than the classical double crossovers. Using a selective system to examine about 5 x IO6 zygotes, CHOVNICK (1 973) examined recombination between rosy mutant alleles in the center of a paracentric inversion heterozygote, and compared the results with experiments carried out in standard chromosome homozygotes. He found gene conversion frequencies were of the same order of magnitude in the inversion heterozygotes as in the standard arrangement homozygotes.

Origin of Hba-ps4 alleles: A single gene conversion between a t haplotype and a wild-type chromosome may explain the presence of mosaic chromosomes like DEAl in Egyptian mouse populations. All three mice bearing chromosomes with Hba-ps4" come from the geographical region close to Giza (and the pyramids). Therefore, it is very likely that these chromosomes are identical by descent. The other mosaic chromosomes identified in this study ( i e . , Figure 4, restriction maps 2, 5-7) may have resulted from separate conversion events or secondary recombination events in-

(9)

Genetic Exchange in the t Conlplex

T 2 1 3 5 7T39 11 13 15 T5 T6 T7 T 2 1 3 5 7 T 3 9 11 13 15 T5 T6

A " A

807

FIGURE 6.-Hypothetical scenario for the origin of mosaic haplotypes from known wild-type and f haplotype alleles. The positions of Tag1

(T2, T5-7) and other enzyme sites (1-15: site 8 is equivalent to T 3 ) are shown on the top of the diagram. Informative sites are indicated with vertical lines (presence) and asterisks (absence). (A) Two-step process in the formation of the DEA 1 Hba-ps4" allele. (Left) An ancestral

1 haplotype converts a wild-type chromosome with an allele similar to that carried by BALB/cJ (Hba-ps4""). creating an intermediate (Hba-

ps4"") with t-like sites 4-15, and BALB/cJ-like sites T5-T7. (Right) Recombination between sites 15 and T 5 w i t h Hba-ps4". (B) Formation

of Hba-ps4" (SM/J) and Hba-ps4'alIeles (haplotypes 5-7, Figure 48). The alleles carried by SM/J, BI 0 and DIT are formed by recombination

between sites 7 and 8 (T3) of Hba-ps4"" and three different wild-type alleles, Hba-psP', Hba-pdd2, and Hba-ps4". respectively.

the rosy locus between inverted regions of

D.

mela-

nogaster was 1 O-4events per meiosis (CHOVNICK 1973),

it seems likely that Hba-psC'-related alleles are the result of intra-allelic recombination with a wild-type allele.

A hypothetical scenario for the origin of all mosaic haplotypes from known wild-type chromosomes and a hypothetical ancestral t haplotype is shown in Figure 6. This scenario, only one of many that are possible, is appealing because it involves the least number of total steps and emphasizes the greater probability of intra-allelic recombination over multiple inter-chromosomal conversion events. T h e origin of the Hba-

ps4" allele is envisioned as a two-step process where an ancestral t haplotype converts a wild-type chromosome similar to BALB/cJ (Hba-ps4".') thereby creating an intermediate allele (which we call Hba-ps4"")

with t-sites 4 through 15, and BALB/cJ sites T 2 , 1-3 and T5-T7 (Figure 6A). This allele is now carried on a wild-type chromosome and can freely recombine with other wild-type alleles. Recombination with a wild-type H b ~ - p s 4 ~ ' allele, between sites 15 and T5, would create the arrangement of enzyme sites observed in Hba-ps4*'.

T h e origin of all other mosaic chromosomes can be explained by recombination between sites 7 and 8 of the Hba-ps4""interrnediate and one of three different closely related wild-type chromosomes (Figure 6B). This scenario implies that there is a recombination hotspot in which 3 intra-allelic recombination events have occurred within a 219-bp segment of the pseudogene (Figure 4, bases 91 1-1 130).

A separate conversion in

M.

castaneus? A similar region of t homology is also observed in one of two Hba-ps4 alleles of a wild-type chromosome from M .

castaneus (Figure 4C). This may suggest that an inde-

pendent recombination event occurred between a M .

castaneus wild-type allele and one similar to Hba-ps4"'

'.

However, in the upstream region of both C T T and CASA alleles, there is a mixture of t-specific and wild- type sites. Two explanations can be offered. First, it is possible that these alleles are the product of a transfer of genetic information from a M . castaneus t

haplotype (that differs from the t haplotypes examined from M . domesticus and M . musculus) to a M . castaneus wild-type chromosome. Recombination with wild-type alleles could then scatter t-specific sites onto different chromosomes.

A second explanation is that the alleles present in M . castaneus did not arise by recombination with a t haplotype, but are closely related to the alleles present in the ancestral population where t haplotypes originated. For example, it is possible that the distal inversion that is now carried by all t haplotypes, originated in the range of M . castaneus. T h e recombination suppression that resulted from the fixation of the inversion chromosome would preserve the similarity of the t form of the Hba-ps4 allele with those present in M . castaneus.

(10)

808 M . F. Hammer, S. Bliss and L. M . Silver

populations of M . domesticus, one of which (Hba-ps4') is the most common allele among inbred laboratory strains (D'EUSTACHIO et al. 1984; FOX, SILVER and MARTIN 1984; DELARBRE et al. 1988). If this process has been recurrent, the same pattern of variation should occur for other loci. In fact, evidence for such patterns has been observed in surveys of other t complex loci. Nearly one third of the complete t haplotypes examined in this survey carry an allele of Pim-1 with TaqI sites identical to those of an allele carried by all M . domesticus chromosomes examined; a similar result was obtained by NADEAU and PHILLIPS (1 987). Other examples of putative genetic exchange between wild-type and t haplotypes have been reported at the Crya-1 locus (SKOW et al. 1987) and the H-2Ea locus (DEMBIC, SINGER and KLEIN 1984). All of these loci reside within the largest of the four inversion polymorphisms-In( 17)2-that distinguish t haplotypes from wild-type chromosomes. It is possible that this inverted region is more likely to undergo the pairing necessary for exchange events to occur.

Conversion at t distorter loci would create mosaic t haplotypes with reduced transmission ratios and would be selected against. This means that Pim-1 and Crya-1 cannot be involved in TRD. Interestingly, there is the possibility that all TRD loci reside near the eight inversion breakpoints (Committee for Chro- mosome 17 et al. 199 l ) , whose adjacent regions might be less likely to undergo exchange events (CHOVNICK 1973), although this appears not to be the case for regions adjacent to insertion breakpoints in the Dro- sophila rosy locus (CLARK, HILLIKER and CHOVNICK

1988).

We thank Y. NISHIOKA for providing the unpublished BALB/cJ

Hba-ps4 sequence. This research was supported by a grant from the

National Institutes of Health to L. M. S. (HD20275) and by a

postdoctoral fellowship from the National Institutes of Health to M. F. H.

L I T E R A T U R E C I T E D

ARTZT, K., H-S. SHIN and D. BENNETT, 1982 Gene mapping

within the T/t-complex of the mouse. 11. Anomalous position of the H - 2 complex in t- haplotypes. Cell 28: 471-476.

BARTLETT, J. A,, R. K. GAILLARD and W. K. JOKLIK,

1986 Sequencing of supercoiled plasmid DNA. Biotechniques

BORTS, R. H., and J. E. HABER, 1989 Length and distribution of

meiotic gene conversion tracts and crossovers in Saccharomyces

cereuisiae. Genetics 123: 69-80.

CHARLESWORTH, B., and D. HARTL, 1978 Population dynamics

of the segregation distorter polymorphism of Drosophila mel-

anogaster. Genetics 89: 17 1- 192.

CHOVNICK, A. , 1973 Gene conversion and transfer of genetic

information within the inverted region of inversion heterozygotes. Genetics 75: 123-1 3 1.

CHURCH, G. M., and W. GILBERT, 1984 Genomic sequencing.

Proc. Natl. Acad. Sci. USA 81: 1991-1995.

CLARK, S . H., A. J. HILLIKER and A. CHOVNICK,

1988 Recombination can initiate and terminate at a large

4: 209-2 10.

number of sites within the rosy locus of Drosophila melanogaster. Genetics 118: 261-266.

Committee for Chromosome 17, K. ARTZT, D. BARLOW, W. F.

DOVE, K. FISCHER-LINDAHL, J. KLEIN, M. LYON and L. M.

SILVER, 1991 Maps of mouse chromosome 17: first report.

Mamm. Genome 1: 5-29.

CROW, J. F. , 1988 The ultraselfish gene. Genetics 118: 389-391.

CURTIS, D., S. H. CLARK, A. CHOVNICK and W. BENDER,

1989 Molecular analysis of recombination events in Drosoph- ila. Genetics 122: 653-66 1 .

CUYPERS, H. T., G. SELTEN, W . QUINT, M. ZIJLSTRA, E. R. MAAN-

DAG, w . BOELENS, P. VAN WEZENBECK, C. MELIEF and A.

BERNS, 1984 Murine leukemia virus-induced T-cell lym-

phomagenesis: integration of proviruses in a distinct chromosomal region. Cell 37: 14 1 - 150.

D'EUSTACHIO, P., B. FEIN, J. MICHAELSON and B. TAYLOR,,

1984 The alpha-globin pseudogene on mouse chromosome

17 is closely linked to H - 2 . J. Exp. Med. 1 5 9 958-963.

DELARBRE, C., Y. KASHI, P. BOURSOT, J. S. BECKMAN, P. KOURLISKY,

F. BONHOMME and G . GACHELIN, 1988 Phylogenetic distri-

bution in the genusMus of t-complex-specific DNA and protein

markers: inferences on the origin of t-haplotypes. Mol. Biol. Evol. 5: 120-133.

DEMBIC, Z., A. SINGER and J. KLEIN, 1984 Eo : a history of a

mutation. EMBO J. 3: 1647-1654.

DOBZHANSKY, T. , 195 1 Genetics and the Origin ofSpecies. Columbia University, New York.

ERHART, M. A,, S. J. PHILLIPS, F. BONHOMME, P. BOURSOT, E. M.

WAKELAND and J. H . NADEAU, 1989 Haplotypes that are

mosaic for wild-type and t complex-specific alleles in wild mice.

Genetics 123: 405-415.

FEINBERG, A. P., and B. VOGELSTEIN, 1983 A technique for

radiolabeling DNA restriction endonuclease fragments to high

specific activity. Anal. Biochem. 132: 6-1 3.

FERRIS, S. D., R. D. SAGE, E. M. PRAGER, U. RITTE and A. C.

WILSON, 1983 Mitochondrial DNA evolution in mice. Ge-

netics 105: 681-721.

FIGUEROA, F., E. NEUFIELD, U. RITTE and J. KLEIN, 1988 t-

Specific DNA polymorphisms among wild mice from Israel and

Spain. Genetics 119: 157-160.

FOX, H., L. M. SILVER and G. R. MARTIN, 1984 An a-globin

pseudogene is located within the mouse t complex. Immuno-

genetics 19: 125-130.

Fox, H. S., G . R. MARTIN, M. F. LYON, B. HERRMANN, A,".

FRISCHAUF, H . LEHRACH and L. M. SILVER, 1985 Molecular

probes define different regions of the mouse t complex. Cell

4 0 63-69.

FRISCHAUF, A,"., 1985 T h e T / t complex of the mouse. Trends

HAMMER, M. F., J. SCHIMENTI and L. M. SILVER, 1989 The

evolution of mouse chromosome 17 and the origin o f t complex inversions. Proc. Natl. Acad. Sci. USA 86: 3261-3265.

HERRMANN, B., M. BUCAN, P. E. MAINS, A.-M. FRISCHAUF, L. M.

SILVER and H. LEHRACH, 1986 Genetic analysis of the prox-

imal portion of the mouse t complex: evidence for a second inversion within t haplotypes. Cell 44: 469-476.

KANEDA, H., Y . Y. MAEDA, K. MORIWAKI, M. SAKAIZUMI, C. TAYA,

S . WATENABE and H. YONEKAWA, 1989 t chromosome found in East Asiatic wild mice, M. m. molossinus , M . m. castaneus.

Mouse News Lett. 84: 119.

KING, T . R., W. F. DOVE, B. HERRMANN, A. R. MOSER and A.

SHEDLOVSKY, 1989 Mapping to molecular resolution in the

T to H-2 region of the mouse genome with a nested set of

meiotic recombinants. Proc. Natl. Acad. Sci. USA 86: 222-

226.

KLEIN, J. , 1986 Natural History of the Major Histocompatibility Complex. John Wiley & Sons, New York.

KLEIN, J., P. SIPOS and F. FIGUEROA, 1984 Polymorphism of t-

(11)

Genetic t h e E x c h a n g e i n t C o m p l e x 809

complex genes in European wild mice. Genet. Res. 3 0 93-

106.

KREITMAN, M., and M. AGUADE, 1986 Genetic uniformity in two

populations of Drosofhila melanogaster as revealed by filter hybridization of four-nucleotide-recognizing restriction en-

zyme digests. Proc. Natl. Acad. Sci. USA 83: 3562-3566.

LEDER, A,, D. SWAN, F. RUDDLE, D'EUSTACHIO and P. LEDER, 1981 Dispersion of alpha-like genes of the mouse to three

different chromosomes. Nature 293: 196-200.

LEWONTIN, R. C., and L. C. DUNN, 1960 T h e evolutionary dy-

namics of a polymorphism in the house mouse. Genetics 45:

LYON, M. F. , 1984 Transmission ratio distortion in mouse t- haplotypes is due to multiple distorter genes acting on a re-

sponder locus. Cell 37: 621-628.

NADEAU, J. H., and S. J. PHILLIPS, 1987 T h e putative oncogene

Pim-I in the mouse: its linkage and variation among t haplo-

types. Genetics 117: 533- 541.

OLDS-CLARKE, P., 1986 Motility characteristics of sperm from the

uterus and oviducts of female mice after mating to congenic males differing in sperm transport and fertility. Biol. Reprod.

POTTER, M.,J. H. NADEAuand M. P. CANCRo(Editors), 1986 T h e

wild mouse in immunology. Curr. Top. Microbiol. Immunol.

ROHME, D., H. Fox, B. HERRMANN, A,". FRISCHAUF, J.-E. ED-

STROM, P. MAINS, L. M. SILVER and H. LEHRACH,

1984 Molecular clones of the mouse t complex derived from

microdissected metaphase chromosomes. Cell 36: 783-788.

SARVETNICK, N., H. Fox, E. MANN, P. MAINS, R. ELLIOT and L. M.

SILVER, 1986 Nonhomologous pairing in mice heterozygous

for a t haplotype can produce recombinant chromosomes with

duplications and deletions. Genetics 113: 723-734.

SCHIMENTI, J., L. VOLD, D. SOCOLOW and L. M. SILVER, 1987 An

unstable family of large DNA elements in the center of the mouse t complex. J. Mol. Biol. 194: 583-594.

SILVER, L. M. , 1985 Mouse t haplotypes. Annu. Rev. Genet. 19:

705-722.

34: 453-467.

127: 373-395.

179-208.

SILVER, L. M., and D. REMIS, 1987 Five of the nine genetically defined regions of mouse t haplotypes are involved in transmission ratio distortion. Genet. Res. 49: 51-56.

SILVER, L. M., J. UMAN, J. DANSKA and J. 1. CARRELS, 1983 A

diversified set of testicular cell proteins specified by genes within the mouse t complex. Cell 35: 35-45.

SILVER, L. M., M . HAMMER, H. Fox, J. CARRELS, M. BUCAN, B.

HERRMANN, A.- M. FRISCHAUF, H. LEHRACH, H. WINKING, F.

FIGUEROA and J. KLEIN, 1987 Molecular evidence for the

rapid propagation of mouse t haplotypes from a single, recent,

ancestral chromosome. Mol. Biol. Evol. 4: 473-482.

SKOW, L. C., J. N. NADEAU, J. C. AHN, H.3. SHIN, K. ARTZT and

D. BENNETT, 1987 Polymorphism and linkage of the alpha-A

crystallin gene in t haplotypes of the mouse. Genetics 116: 107- 1 1 1 .

THOMSON, G. J., and M. W. FELDMAN, 1974 Population genetics

of modifiers of meiotic drive 11. Linkage modification in the

segregation distortion system. Theor. Popul. Biol. 5: 155-162.

WILLISON, K. R., K. DUDLEY and J. POTTER, 1986 Molecular

cloning and sequence analysis of a haploid expressed gene

encoding t complex polypeptide 1 . Cell 44: 727-738.

WU, C.-I., and M. F. HAMMER, 1991 Molecular evolution of

ultraselfish genes of meiotic drive systems, pp. 177-203 in

Evolution at the Molecular Level, edited by R. K. SELANDER, A.

G. CLARK and T. S. WHITTAM. Sinaur Associates, Sunderland,

Mass.

Communicating editor: A. CHOVNICK

APPENDIX

TuqI restriction fragment patterns for 8 loci and

fragment sizes for 11 t complex probes are given in Tables 3 and 4, respectively. Fragment patterns for

(12)

810 M . F. Hammer, S. Bliss and L. M. Silver

TABLE 3

TaqI restriction fragment patterns for 8 loci in the t complex

Tcp- 1 66 Hba

Mouse number and kind 4 8 119 29X Bb40 9 6 7 11 la 1 0 89

Pim Crya

M . domesticus 1 BALB/cJ 2 C3H/HeJ 3 129/sv 4 C57B11 O/J 5 SM/J 6 DMEl 7 DME2

8 DME3

9 DMAl

10 DMA2

11 DIH 12 lCJl 13 1CJ2 14 DIJl 15 DIJ2 16 DIJ3 17 D I T 18 WMP/PAS 19 DPL 20 DEAl 21 2

22 3 23 4

24 DES1

25 2

26 3

27 4

28 5

29 6

30 DEGl 31 DEG2 32 DEW M . musculus

33 PWK/PAS 34 MCB 35 MCS 36 MYB 37 MA1 38 MPW 39 MDS M . castaneus

40 CASA/RK 41 C T T

M . molossinus

42 MOLC/RK

43 BIO.BACI 44 BlO.BAC2

12.I. bactrianus

M. abbotti

45 XBS 46 AYG

M . hortulanus

47 HAH

48 HYP

M . spretus

49 ssc

50 SSG

51 SMA

M. cervicolorlcaroli

52 CVT 53 C K T

2 3 2 2 2 2 2 t*/2 t*/1 1 1 1 1 1 1 1 3 2 2 1 t t*/2 t*/2 1 1 4 t/ 1

t’/l t’/l 4 2 t‘/l

1 1

2 2

t t

1 1

t / l t / l

3 1

t/3 t/l

2 2

1 1

1 I

1 1

2 2 2 2

1 1

t t

t/t t/t

t / 3 t / l

t/3 t/l

t / l t / l

t/2 t/2 t/2 t/2

t / l t / l

t / l t / l 113 1

1 1

2 2 2 2

2 2

2 2 2

2

t/2 -

1 2

t / l -

2 2

2 2 2

2 2 2 2

2 2

2 1 2

-

- -

-

- -

t t

t/2 t/2

2 2

112 2

2 2

t/2 t/2

t/2

-

112 -

2 2

112

-

t/2 -

t/2 2

2 1

2 1 2 1 2 1 2 1 2 1

4 5

5 5

4 4

5 3

4 4 5 5

5 4

3 1

2

1

6 7

1 1

2 2

2

2 1

- ₃

3 7

-

1 1

2 1 5 4

1 1 2 5 3 1 2

314 118

5 t

1 t 1 1 2 t*

2 2

t t

2

t

2 2

t t

1 t

3 1

2 2

2 1

5 9

5 9 2 2 1 1 2 2 8 8

2 1

8 10

2 2 1 1 3 3 9 8

3 1

2 2

2 3 2 3

2 3

2 11 2 11

1 1 1

2 2 2 2 2 2 3 3 3 I4

10 10 10

3 1

2 2 2

11 12

4 1

5 1

3 2

6 12

6 13

3 4

5 5

3 1

2 1