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ILAR Journal V39(2/3) 1998
Comparative Gene Mapping

The Linkage Map of Xiphophorus Fishes
Donald C. Morizot, Rodney S. Nairn, Ronald B. Walter, and Steven Kazianis
Donald C. Morizot, Ph.D., and Rodney S. Nairn, Ph.D., are Associate Professors of Carcinogenesis at the University of Texas M. D. Anderson Cancer Center, Science Park, Research Division, Smithville, Texas. Steven Kazianis, Ph.D., is a Research Associate al the same institution. Ronald B. Walter, Ph.D., is Associate Professor of Genetics in the Department of Biology, Southwest Texas State University, San Marcos, Texas.

INTRODUCTION

Advances in molecular biological techniques, particularly the advent of polymerase chain reaction (PCR1)-based methods, have resulted in an explosion of gene mapping studies in a variety of organisms. Assignments of known genes to linkage groups in fishes particularly have provided illuminating insights regarding the rates and kinds of chromosomal rearrangement that have occurred during vertebrate evolution. As the earliest classes of vertebrates, fishes might be suspected to have retained gene arrangements similar to those of the vertebrate ancestor, especially given the extraordinary karyotypic conservatism of teleosts (bony fishes), such that more than half the species assessed exhibit the presumed primitive diploid complement of 48 chromosomes (Chiarelli and Capanna 1973).

At the time of this writing, linkage maps with markers for most or all chromosome pairs have been assembled for only 3 teleosts: zebrafish Danio rerio, Cypriniformes (Johnson and others 1996; Postlethwait and others 1994); platyfishes and swordtails of the genus Xiphophorus, Cyprinodontiformes (Kazianis and others 1996; Morizot and others 1991, 1993; Morizot 1994 and unpublished); and medaka Oryzias latipes, Cyprinodontiformes (Wada and others 1995). The zebrafish map comprises ~650 markers, including ~100 genes; the Xiphophorus map, ~300 markers and 103 genes; and the medaka map, 170 markers and 9 genes. Less complete gene maps with multiple linkage groups have been assembled for several other fishes, including trout and salmon, order Salmoniformes (Allendorf and others 1986; May and Johnson 1993); Ictalurus catfishes, Siluriformes (Liu and others 1992, 1996; Morizot and others 1994); centrarchid sunfishes, Perciformes (Pasdar and others 1984); Poeciliopsis, Cyprinodontiformes (Morizot and others 1990); and puffers such as fugu, Tetraodontiformes (Brenner and others 1993; Crnogorac-Jurcevic and others 1997; Elgar and others 1996). In this paper, we summarize 1 of the largest fish gene maps, that of Xiphophorus species.

REASONS FOR MAPPING THIS GENUS

Gene mapping in Xiphophorus fishes wax initiated in the 1970s, first to identify the number of genes regulating a spontaneous malignant melanoma in interspecific hybrids that had been discovered more than 6 decades ago, arguably the oldest genetic model of cancer (Gordon 1931; Kosswig 1931; Siciliano and others 1976). The interest in identifying oncogenes and tumor suppressor genes has continued, with identification of a sex-linked oncogene Xmrk, related to EGFR (Schartl 1995), a candidate CDKN2 tumor suppressor gene in spontaneous and ultraviolet radiation-induced melanomas (Nairn and others 1996), and identification of new tumor regulatory genes by genomic localization (Kazianis and others 1996). Almost complete interfertility among the >20 species of the genus either by natural matings or artificial insemination makes production of extraordinarily informative genetic crosses a relatively easy matter.

A second reason for development of the Xiphophorus gene map was the early identification of gene arrangements apparently conserved between fishes and mammals through more than 400 million yr of evolutionary divergence, an heretical conclusion at its first presentation (Morizot 1983). At the same time, linkage of duplicated genes in different linkage groups such as glucosephosphate isomerases, pyruvate kinases, and isocitrate dehydrogenases in linkage groups (LGs1) II and IV in Poeciliopsis and Xiphophorus suggested derivation from chromosome duplications (Leslie 1982; Morizot 1983, 1994), perhaps resulting from the ancestral tetraploidizations postulated by Ohno (1970). Confirmation of these hypotheses will require mapping of many more members of gene families in a variety of vertebrates, and hopefully in stem vertebrate and chordate taxa.

CURRENT MAP STATUS

A summary of the Xiphophorus linkage map is presented in Tables 1 and 2 and Figure 2. The map is a composite of multiple cross types among 15 species of the genus, assembled from analysis of ~5000 backcross and intercross hybrid individuals. Most likely gene orders and maximum likelihood recombination estimates were calculated using MAPMAKER software (Lander and others 1987), minimizing linkage group length where equally likely orders existed. Approximately 334 markers including 103 genes have been assigned to 34 multipoint linkage groups, 10 more than the 24 pairs of acrocentric and telocentric chromosomes. Focusing on linkage groups identified in crosses between the platyfish Xiphophorus maculatus and the southern swordtail Xiphophorus helleri, which are the most completely marked and most often utilized melanoma model genetic crosses, the markers are distributed on only 25 linkage groups, 1 of which (U26) includes only 2 markers with no observed recombinants. The 9 other unassigned linkage groups were discovered in other interspecific cross types and are as yet incompletely tested with markers from LGs i through XVII and the sex chromosome linkage group, LG XXIV.

The 103 genes mapped include 67 isozyme genes, 23 cloned genes, 16 restriction fragment length markers not yet cloned and sequenced, 7 pigment pattern genes, and 4 miscellaneous loci including a sex-linked lethal trait (SLLI), the sex-determining locus, and a pituitary gonadotropin releasing gene (PIT) governing size and age at sexual maturity (Kallman and Borkoski 1978). The linkage map thus provides for comparative gene mapping approximately 90 genes for which homology with genes of other vertebrates can be established. Equally important in genetic models of cancer is the fact that markers are likely to be located on all 24 chromosomes in many genetic crosses, virtually assuring detection of tumor regulatory genes by linkage analysis. Although Morizot and others (1991) estimated the length of the Xiphophorus map at about 1800 cM, additive estimates from X. helleri x X. maculatus-derived backcrosses span a length of-2860 cM, somewhat larger than estimates of 2720 cM in zebrafish (Postlethwait and others 1994). Both the map and map length estimates must be considered crude first approximations to the actual map for several reasons: (1) Many gene orders are as yet very poorly supported by meager data; (2) recombination estimates represent averages over many diverse interspecific cross types and of recombination in both male and female hybrids; and (3) there still is a significant probability of either lengthening or shortening of the map by coalescence of linkage groups with additional linkage data.

APPROACHES USED TO DEVELOP THE MAP

Gene mapping in Xiphophorus has proceeded in the old-fashioned way of making genetic crosses, particularly reciprocal first backcrosses, and assessing joint segregation of every pair of markers to detect deviations from independent assortment expectations due to genetic linkage. Because Xiphophorus fishes are livebearers, manipulation of eggs is difficult, and no chromosome set alterations have been successful. However, the great power of making a variety of hybrids among highly diverged species potentially yields thousands of polymorphic markers in each genetic cross. In Xiphophorus mapping, most of the emphasis has been on mapping markers of several different types. When most polymorphic isozyme loci had been mapped, attention turned to mapping genes cloned in other vertebrates, particularly other fish species. Although detection of restriction fragment length marker polymorphisms on Southern blots has added a number of genes to the linkage map, PCR-based approaches are usually much easier and faster. We will utilize the >100 cloned and sequenced fish genes to design primers for PCR-based genotyping that will provide the bulk of new gene assignments to the linkage map in the near future. For localizing a large number of markers, arbitrarily primed PCR (AP-PCR or RAPD) polymorphisms have proved to be fast, easy, and repeatable (Kazianis and others 1996). Combinations of these approaches will produce reasonable marker saturation in the near future. Unfortunately, Xiphophorus chromosomes are small and difficult to stain for individual recognition (containing only ~20% of the DNA content of humans), so assignment of linkage groups to chromosomes remains a task for the future.

SCIENTIFIC CONTRIBUTIONS OF THE MAP

The most significant contribution of gene mapping in Xiphophorus to the area of comparative gene mapping in vertebrates undoubtedly is strong support for hypotheses that the vertebrate genome derived from 2 or more ancestral duplications of chromosome sets in chordate ancestors (Lundin 1993; Morizot 1994; Ohno 1970). Diploid teleost fishes usually have many more expressed gene duplicates than mammals in gene families. Differences have been identified for glyceraldehyde-3-phosphate dehyrogenase coding loci (at least 4 for fish versus 2 for mammals), glucosephosphate isomerase loci (2 versus 1), triosephosphate isomerase loci (2 versus 1 ), cytosolic creatine kinase loci (4 versus 2), cytosolic malate dehyrogenase loci (2 versus 1), cytosolic glutamate-oxaloacetate transaminase loci (2 versus 1), and so on for many other examples. If these duplicated genes arose through chromosome duplication and if chromosomal rearrangements were relatively uncommon, linkage of duplicated genes in fishes would suggest retention of patterns produced by ancestral chromosome and/or chromosome set duplications. Many such examples have been adduced by gene mapping in poeciliid fishes, including Xiphophorus. Glucosephosphate isomerase, pyruvate kinase, and isocitrate dehydrogenase duplicates are linked in 2 poeciliid linkage groups; glutamate-oxaloacetate transaminase and malate dehydrogenase genes are linked in at least 2 poeciliid linkage groups; and glyceraldehyde-3-phosphate dehydrogenase and dimeric peptidase gene duplicates are linked in at least 2 Xiphophorus linkage groups. Morizot (1994) compared Xiphophorus gene arrangements with those in other vertebrates and suggested that 3 sets of paralogous chromosomes could be identified and that genes in each paralogous set were much more likely to be rearranged within a set of paralogous chromosomes in vertebrate gene maps than translocated into chromosomes of a nonhomologous set.

Contributions of Xiphophorus genetic studies to elucidation of genetic mechanisms of cancer initiation and progression likewise have been very significant. The hybrid melanoma models of Xiphophorus helped to maintain interest in genetic components of tumorigenesis during the bandwagon times when viruses, environmental carcinogens, and "lifestyle" were touted to be causative of >90% of human cancers. Current research in Xiphophorus focuses on identification of new oncogenes and tumor suppressor genes and elucidation of mechanisms by which oncogenes and tumor suppressor genes common to fish and human cancers produce susceptibility to neoplasia. For example, spontaneous and ultraviolet radiation-induced melanomas in Xiphophorus hybrids are strikingly similar to human malignant melanomas. Based on this similarity, an epidermal growth factor receptor-related oncogenic duplicate in Xiphophorus and a cyclin-dependent kinase inhibitor closely related to p l6 (likely to be involved in development of human familial malignant melanoma) are under intense study (Dracopoli and Fountain 1996; Nairn and others 1996; Schartl 1995). Other potential oncogenes and/or tumor suppressor genes for melanomas and other tumors have been identified in Xiphophorus hybrids by genomic localization; these genes, when cloned and identified, may facilitate identification of homologues in humans that are as yet unidentified as important regulatory genes in tumorigenesis.

ANTICIPATED FUTURE CONTRIBUTIONS OF THE MAP

A much larger gene map of Xiphophorus should yield the comparative gene mapping database necessary to reconstruct the gene map of the ancestor of all vertebrates. Although such a prediction may seem rash, several lines of evidence suggest its verity. First, the much greater similarity of fish gene maps compared with mammalian maps (Andersson and others 1996; Wakefield and Graves 1996), despite an equal time of evolutionary divergence from the vertebrate ancestor as mammals, suggests that gene rearrangements in fishes have occurred relatively infrequently and that fish gene maps thus retain greater similarity to arrangements in the vertebrate ancestor than do maps of representatives of other vertebrate classes. Second, many syntenic associations in fish gene maps apparently are conserved in amphibian, avian, and mammalian gene maps (Andersson and others 1996; Morizot 1994; Wakefield and Graves 1996), suggesting plesiomorphic retention of ancestral gene arrangements. Third, nonrandomness of chromosomal rearrangements during vertebrate evolution with preferential translocations among homologous chromosomes or chromosome segments may facilitate probable localization of genes in the vertebrate ancestor.

The pace of research in genetic mechanisms of tumorigenesis is so fast that it is difficult to predict the future impact of Xiphophorus mapping studies. Some new oncogenes and tumor suppressor genes will likely be identified first in Xiphophorus and then found to have associations with development of particular tumors in humans. It is quite possible that new mechanisms of regulation of gene expression, cellular growth and differentiation, programmed cell death, or other events in tumor cell progression may be identified first in mechanistic studies of tumor development in Xiphophorus models. Whatever new discoveries are made, it appears likely that as in the past, the first identification of genetic [actors will come through localization to particular genomic regions in genetic crosses.

USES OF THE MAP AND ACCESSIBILITY

Scientists with interests in particular genes or gene families in vertebrates often can benefit from results of comparative gene mapping studies. The locations of many genes in vertebrates can now or in the near future be predicted with considerable confidence if they reside in a highly conserved syntenic segment. Furthermore, if a sufficient number of cloned sequences from vertebrate species have been mapped to a region, probing of genomic or cDNA library clones may permit facile cloning of nearby genes of interest. Positional cloning by reverse genetic approaches undoubtedly will become easier as extensive gene maps of a variety of vertebrate species are assembled.

Geneticists working on almost any type of problem, from improvement by selective breeding to attempts to identify modes of inheritance of particular traits, can find gene maps to be useful in designing experiments. For example, if catfish geneticists interested in identifying major genes for disease resistance have identified markers in their genetic crosses, the map positions of homologous genes in Xiphophorus can provide a good preliminary estimate of genomic coverage of their markers for quantitative trait linkage analysis. It should be noted that the utility of such analyses provides a major impetus to inclusion of genes for which homology among vertebrates can be confidently determined in gene mapping studies in any species.

Xiphophorus linkage databases can be accessed by interested researchers in a variety of ways, beginning with reference to publications with original linkage group assignments and direct queries to major Xiphophorus mapping research groups for access to updated marker information and linkage map summaries on the Internet (http://sprd1.mdacc.tmc.edu/skazianis/mainpage.html).

CONCLUSION

Gene maps of fishes have expanded dramatically during the 1990s. The remarkable conservatism of gene arrangements in teleosts and unexpected homology with those of many mammals has permitted identification of chromosome segments little changed since divergence of the fish and mammal common ancestor approximately 450 million yr ago. Expansion and refinement of fish gene maps thus promise to allow reconstruction of genomic arrangements of the vertebrate ancestor. An even more exciting prospect is the beginning of research designed to answer some of the most perplexing problems in biology:

Comparative gene mapping among vertebrates and eventually among other animal groups will undoubtedly provide the first insights into these critical questions and certainly will provide the framework on which meaningful experiments can be devised.

1Abbreviations used in this paper: LG, linkage group; PCR, polymerase chain reaction.


ACKNOWLEDGMENTS

The research resulting in the current Xiphophorus linkage map was supported by National Institutes of Health grants CA55245, CA09480, CA76693, ES07784, and RR12253 and Texas Advanced Technology Program 3615-030. We are grateful for the excellent technical assistance of Luis Della Coletta and Barbara Santi, the Center for Research on Environmental Disease Molecular Biology Service Core personnel Elizabeth Osterndorff and Dr. Michael LaBate, and Dr. Dennis Johnston.

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TABLE 1 Alphabetical listing of mapped polymorphisms in Xiphophorus

SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
ACO1XIVIsozymic
ACO2XIsozymic
ACTBXVIRFLP
ADAIIsozymic
AMYVIIsozymic
AMYL1U18PCR
ASD1XIIPhenotypic
ATPAIIIIsozymic
CA1XXIVIsozymic
CA2L1IPCR
CBIIPhenotypic
CDKN2XVRFLP/PCR
CKMXIIsozymic
DXXIVRFLP
DNMTXVIRFLP

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
EGFRVIRFLP
ERCC2XIRFLP
ES1VIsozymic
ES2IIIsozymic
ES3IIIsozymic
ES4VIsozymic
ES5IIIsozymic
ES7IIIIsozymic
FBPXIIIsozymic
FEM1XXIVRFLP
FEM2XXIVPCR-based
FHIXIsozymic

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
G6PDIIsozymic
GALT1VIIIIsozymic
GAPD1IIIIsozymic
GAPD2IIIIsozymic/PCR
GAPD3XIIIIsozymic
GDAXOOIsozymic
GDH1U2Isozymic
GDH2IVIsozymic
GLAXVIsozymic
GLNSVIIsozymic
GLOIVIsozymic
GLYDHVIsozymic
GNRHU22RFLP
GOT1VIsozymic
GOT2IVIsozymic
GOT3U1Isozymic
GPD1U2Isozymic
GPI1IVIsozymic
GPI2IIIsozymic
GUK1IXIsozymic
GUK2IIIIsozymic
GUK3VIIsozymic

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
HEXAVIIIIsozymic
IDH1IVIsozymic
IDH2VIIIsozymic
ITPIXIsozymic
JUNA1VIRFLP
JUNA2U4RFLP

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
LDH1IIIsozymic
LIG1VIRFLP
MACRXXIVPhenotypic
MANAIIIsozymic
MDH1U1Isozymic
MDH2VIsozymic
MEIIIIsozymic
MHCDABU24RFLP
MHCDXBIIIRFLP
MP5U15Isozymic
MPIIIIsozymic
MYH1U20RFLP
NP2VIIsozymic
onesarIIIPhenotypic

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
PXVIIPhenotypic
PEPAXIIIIsozymic
PEPBXVIIIsozymic
PEPCIIIIsozymic
PEPDIVIsozymic
PEPSXIIIsozymic
PEPXU2Isozymic
PGAM1XIIsozymic
PGAM2VIIIIsozymic
PGDIIsozymic
PGKXIIsozymic
PGMIXIsozymic
PITXXIVPhenotypic
PK1IVIsozymic
PK2IIIsozymic
PPIAXIsozymic
PPIBU22Isozymic
PVALB1U15Isozymic
PVALB2XIsozymic
PVALB3U4Isozymic

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
RPS15VIRFLP
SEXXXIVPhenotypic
SLL1XXIVPhenotypic
SORDIVIsozymic
SS1XXIVPhenotypic
SS2IIPhenotypic
SWCOLXXIVPhenotypic
TC1L1IIIPCR
TFVIIsozymic
TP53XIVRFLP
TPI1XIIIIsozymic
UMPKVIIsozymic
UNGXIIIsozymic
XANTXXIVPhenotypic

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0001U2RFLP
XD0002XIIIRFLP
XD0003VIRFLP
XD0004VIIIRFLP
XD0006U4RFLP
XD0007XIIIRFLP
XD0008U14AP-PCR/RAPDCP1243
XD0009U14AP-PCR/RAPD31381123
XD0011U8AP-PCR/RAPDCP1282
XD0012XIIAP-PCR/RAPD31381151
XD0014U9AP-PCR/RAPDCP1304
XD0015IIIAP-PCR/RAPDCP1409
XD0019U8AP-PCR/RAPD3139587

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0022XVIIAP-PCR/RAPDCP1512
XD0023XIVAP-PCR/RAPDD11111
XD0024IIAP-PCR/RAPD3906355
XD0025XVIIAP-PCR/RAPDD11134
XD0027U12AP-PCR/RAPDVARXM1443
XD0028XAP-PCR/RAPD3906420
XD0029VAP-PCR/RAPD3139673
XD0030U11AP-PCR/RAPD3906603
XD0031IIIAP-PCR/RAPDCP2278
XD0033U9AP-PCR/RAPD3906678
XD0034IXAP-PCR/RAPDCP2301
XD0035U9AP-PCR/RAPDCP1546
XD0036U12AP-PCR/RAPD3906745
XD0039IIIAP-PCR/RAPDCP2397

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0040XVIIAP-PCR/RAPD3140610
XD0041VAP-PCR/RAPD3139544
XD0042VAP-PCR/RAPDCP2424
XD0044IIAP-PCR/RAPD3140768
XD0045U9AP-PCR/RAPD3139709
XD0046IIAP-PCR/RAPD3140813
XD0048XVIIAP-PCR/RAPDCP2667
XD0049VAP-PCR/RAPDPROM3334
XD0050XVIIAP-PCR/RAPDCP2323
XD0052XAP-PCR/RAPDCP2435
XD0053XVAP-PCR/RAPDCP2852
XD0054VAP-PCR/RAPDPROM3507
XD0055U11AP-PCR/RAPDCP2456
XD0057U8AP-PCR/RAPDPROM3563
XD0059XIVAP-PCR/RAPDPROM3583

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0060IIIAP-PCR/RAPDCP2772
XD0062IIIAP-PCR/RAPDCP2470
XD0065U11AP-PCR/RAPDCP2459
XD0068VAP-PCR/RAPDCP1206
XD0069VAP-PCR/RAPDP53RP303
XD0070VAP-PCR/RAPDOp-10560
XD0071VAP-PCR/RAPDOp-10500
XD0072VAP-PCR/RAPDOp-12700
XD0073VAP-PCR/RAPDOp-13440
XD0074VAP-PCR/RAPDOp-18420
XD0075VAP-PCR/RAPDOp-19380
XD0076VRFLP
XD0077IVRFLP
xd0078U16AP-PCR/RAPDCP11030
XD0079U18AP-PCR/RAPDCP1800

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0081IIAP-PCR/RAPDCP1372
XD0082XIVAP-PCR/RAPDCP1739
XD0083XIAP-PCR/RAPDCP1583
XD0084U18AP-PCR/RAPDCP1488
XD0085XVIIAP-PCR/RAPDCP1433
XD0086XIAP-PCR/RAPDCP1401
XD0087U22AP-PCR/RAPDCP1339
XD0088U20AP-PCR/RAPDCP1309
XD0089U22AP-PCR/RAPDCP1243
XD0090U16AP-PCR/RAPDCP1232
XD0091U19AP-PCR/RAPDCP1184
XD0092U20AP-PCR/RAPDCP1183
XD0093IIAP-PCR/RAPDCP1146
XD0094IAP-PCR/RAPDCP2305
XD0095IXAP-PCR/RAPDCP2312
XD0097U16AP-PCR/RAPDCP2374
XD0098U20AP-PCR/RAPDP53FP668
XD0099XIIAP-PCR/RAPDP53FP616

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0100IIAP-PCR/RAPDP53FP601
XD0101IIIAP-PCR/RAPDP53FP557
XD0102U19AP-PCR/RAPDP53FP370
XD0103U16AP-PCR/RAPDP53FP290
XD0104XIIIAP-PCR/RAPDP53FP262
XD0105IIIAP-PCR/RAPDP53FP238
XD0106U18AP-PCR/RAPDP53FP206
XD0107IVAP-PCR/RAPDP53FP170
XD0108VIAP-PCR/RAPDP53FP161
XD0109XIIIRFLP
XD0110U19AP-PCR/RAPDOp-10
XD0111U18AP-PCR/RAPDOp-10
XD0112U16AP-PCR/RAPDOp-10
XD0113XIIAP-PCR/RAPDOp-18
XD0014IVAP-PCR/RAPDOp-18
XD0115XIIIRFLP
XD0116VAP-PCR/RAPDP53LinF11120
XD0117IIAP-PCR/RAPDP53LinF1616
XD0118U18AP-PCR/RAPDP53LinF1532
XD0119VIAP-PCR/RAPDP53LinF1507

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0120IAP-PCR/RAPDP53LinF1494
XD0121VIIAP-PCR/RAPDP53inF1421
XD0122XIVAP-PCR/RAPDP53LinF1335
XD0123VIAP-PCR/RAPDP53LinF1278
XD0124IAP-PCR/RAPDP53LinF1241
XD0125XIIAP-PCR/RAPDP53LinF1193
XD0126IIAP-PCR/RAPD3906340
XD0127IXAP-PCR/RAPD3906410
XD0128IAP-PCR/RAPD3906315
XD0129U22AP-PCR/RAPDP16F2672
XD0130IIAP-PCR/RAPDP16F2441
XD0131IIAP-PCR/RAPDP16F2411
XD0132U20AP-PCR/RAPDP16F2380
XD0133XIIIAP-PCR/RAPDP16F2363
XD0134VAP-PCR/RAPDP16F2353
XD0135IXAP-PCR/RAPDP16F2253
XD0136U18AP-PCR/RAPDP16F2241
XD0137U20AP-PCR/RAPDP16F2162
XD0139XAP-PCR/RAPDP16F5818

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0140IIAP-PCR/RAPDP16F5455
XD0141IIAP-PCR/RAPDP16F5431
XD0142XVIIAP-PCR/RAPDP16F5421
XD0143XIAP-PCR/RAPDP53P5520
XD0144XVAP-PCR/RAPDP53P8429
XD0145IXAP-PCR/RAPDP53P8392
XD0146IVAP-PCR/RAPDP53P8331
XD0147XVAP-PCR/RAPDP53P8282
XD0148XVIAP-PCR/RAPDP53P8271
XD0149XAP-PCR/RAPDP53P8254
XD0150VIIIAP-PCR/RAPDP53P8242
XD0151VIIIAP-PCR/RAPDP53P8183
XD0152IIIAP-PCR/RAPDP53P8172
XD0153U20AP-PCR/RAPDP53P71039
XD0154U24AP-PCR/RAPDP53P7651
XD0155IIAP-PCR/RAPDP53P7619
XD0156XIIIAP-PCR/RAPDP53P7563
XD0157IXAP-PCR/RAPDP53P7507
XD0158IXAP-PCR/RAPDP53P7405
XD0159VIAP-PCR/RAPDP53P7373

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0160U18AP-PCR/RAPDP53P7223
XD0162IIIAP-PCR/RAPDP53P7165
XD0163XXIVAP-PCR/RAPDPROM3260
XD0164U18AP-PCR/RAPDPROM3323
XD0165U18AP-PCR/RAPDPROM3417
XD0168IIIAP-PCR/RAPDPROM3576
XD0169IIIAP-PCR/RAPDP16R1994
XD0170XIIAP-PCR/RAPDP16R1968
XD0171U20AP-PCR/RAPDP16R1877
XD0172XAP-PCR/RAPDP16R1782
XD0173XAP-PCR/RAPDP16R1744
XD0174VIIAP-PCR/RAPDP16R1604
XD0175XAP-PCR/RAPDP16R1486
XD0176IIIAP-PCR/RAPDP16R1450
XD0178XIIIAP-PCR/RAPDP16R1278

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0180U19AP-PCR/RAPDP16R1260
XD0181VAP-PCR/RAPDP16R1241
XD0182XAP-PCR/RAPDP16R1212
XD0183U19AP-PCR/RAPDP16R22776
XD0184IIAP-PCR/RAPDP16R22760
XD0185XIAP-PCR/RAPDP16R22734
XD0186IXAP-PCR/RAPDP16R22590
XD0187XIAP-PCR/RAPDP16R22413
XD0188VIIAP-PCR/RAPDP16R22365
XD0189IIAP-PCR/RAPDP16R22331
XD0190IIIAP-PCR/RAPDP16R22235
XD0191IVAP-PCR/RAPDP16R22212
XD0192XIAP-PCR/RAPDP53RP777
XD0195XIAP-PCR/RAPDP53RP277
XD0196XIIAP-PCR/RAPDP53RP283
XD0197IAP-PCR/RAPDP53RP405
XD0198IIAP-PCR/RAPDP53RP377
XD0199U18AP-PCR/RAPDP53RP305

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0200U19AP-PCR/RAPDP53RP294
XD0201XVIAP-PCR/RAPDP53RP184
XD0202U20AP-PCR/RAPDP53RP392
XD0203IIAP-PCR/RAPDP53RP434
XD0205IVAP-PCR/RAPDP53RP610
XD0207XIIAP-PCR/RAPDP53RTF1968
XD0208XIVAP-PCR/RAPDP53RTF1719
XD0209U22AP-PCR/RAPDP53RTF1812
XD0210U19AP-PCR/RAPDP53RTF1651
XD0211VIIAP-PCR/RAPDP53RTF1580
XD0212VIAP-PCR/RAPDP53RTF1515
XD0213IAP-PCR/RAPDP53RTF1398
XD0214XIIIAP-PCR/RAPDP53RTF1309
XD0215VIIAP-PCR/RAPDP53RTF1288
XD0216XVIIAP-PCR/RAPDP53RTF1256
XD0217XIAP-PCR/RAPDP53RTF1246
XD0218U19AP-PCR/RAPDP53RTF1220
XD0219XVIIAP-PCR/RAPDP53RTF1193

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0220U20AP-PCR/RAPDP53RTF1125
XD0221XVIIAP-PCR/RAPDP53RTF1198
XD0222IIAP-PCR/RAPDP53RTF2181
XD0223XVAP-PCR/RAPDP53RTF2154
XD0224IIIAP-PCR/RAPDP53RTF2138
XD0225U18AP-PCR/RAPDP53RTR11120
XD0226U24AP-PCR/RAPDP53RTR1776
XD0227VIIAP-PCR/RAPDP53RTR1755
XD0228XIIIAP-PCR/RAPDP53RTR1739
XD0229XVIIAP-PCR/RAPDP53RTR1612
XD0230IIIAP-PCR/RAPDP53RTR1573
XD0231VIIIAP-PCR/RAPDP53RTR1478
XD0232XIVAP-PCR/RAPDP53RTR1401
XD0233U16AP-PCR/RAPDP53RTR1295
XD0234VAP-PCR/RAPDP53RTR1402
XD0235XIAP-PCR/RAPDP53RTR1197
XD0236U18AP-PCR/RAPDP53RTR1181
XD0237XIAP-PCR/RAPDP53RTR2459
XD0238U18AP-PCR/RAPDP53RTR2367
XD0239XVIAP-PCR/RAPDP53RTR2362

TABLE 1 continued
SymbolaMap LocationMarker TypePrimer UsedbApp Sizec
XD0240VIIIAP-PCR/RAPDP53RTR2344
XD0241XVIAP-PCR/RAPDP53RTR2192
XD0242XIIAP-PCR/RAPDP53RTR2146
XD0243VIIAP-PCR/RAPDP53RTR2246
XD0244IIAP-PCR/RAPDP53RTR3368
XD0245U18AP-PCR/RAPDP53RTR3315
XD0246U22AP-PCR/RAPDP53RTR3267
XD0247XIIIAP-PCR/RAPDP53RTR3255
XD0248U20AP-PCR/RAPDP53RTR3216
XD0249XIAP-PCR/RAPDP53RTR3157
XD0250U16AP-PCR/RAPDP53RTR3152
XD0252VIIAP-PCR/RAPD3139378
XD0253U19AP-PCR/RAPD3139421
XD0254U20AP-PCR/RAPD3139443
XD0255VIIIAP-PCR/RAPD3139481
XD0256VIAP-PCR/RAPD3139710
XD0257U16RFLP
XD0258U16RFLP
XD0259IIIRFLP
XD0260U26AP-PCR/RAPDP16F5650
XD0261U26AP-PCR/RAPDP53RP324
XFYNXVRFLP
XMRK1XXIVRFLP
XMRK2XXIVRFLP/PCR
XSRCIRFLP
XYESVIRFLP

aMost gene symbols are defined in Morizot and others (1990, 1991, 1993) and follow human gene nomenclature conventions. XD denotes Xiphophorus anonymous DNA sequence.
bSee Table 2 for primer sequences.
cApproximate sizes of AP-PCR/RAPD markers are determined using methodology described in Kazianis and others 1996.


TABLE 2 Oligonucleotide primer names and sequences

PrimerSequence
CP1GATGAGTTCGTGTCCGTACAACTGG
CP2GGTTATCGAAATCAGCCACAGCGCC
D1CCCCAGACCTGTTTGTGTTGG