Number Of Microsatellite Markers Research Articles

Whole genome survey of big cats (Genus: Panthera) identifies novel microsatellites of utility in conservation genetic study

Big cats (Genus: Panthera) are among the most threatened mammal groups of the world, owing to hunting, habitat loss, and illegal transnational trade. Conservation genetic studies and effective curbs on poaching are important for the conservation of these charismatic apex predators. A limited number of microsatellite markers exists for Panthera species and researchers often cross-amplify domestic cat microsatellites to study these species. We conducted data mining of seven Panthera genome sequences to discover microsatellites for conservation genetic studies of four threatened big cat species. A total of 32 polymorphic microsatellite loci were identified in silico and tested with 152 big cats, and were found polymorphic in most of the tested species. We propose a set of 12 novel microsatellite markers for use in conservation genetics and wildlife forensic investigations of big cat species. Cumulatively, these markers have a high discriminatory power of one in a million for unrelated individuals and one in a thousand for siblings. Similar PCR conditions of these markers increase the prospects of achieving efficient multiplex PCR assays. This study is a pioneering attempt to synthesise genome wide microsatellite markers for big cats.

Development and characterization of 14 microsatellites for the eastern chipmunk, Tamias striatus.

The number of microsatellite markers currently available for the eastern chipmunk Tamias striatus provides limited capacity to achieve sufficient pedigree building for the study of their genetic structure and relatedness patterns. We developed microsatellite loci for the eastern chipmunk, a small rodent commonly found in eastern North America. More specifically, we report data for 14 loci and 50 individuals genotyped from a population in southern Québec, Canada. We found a number of alleles ranging from 5 to 21 and there was no linkage disequilibrium among locus. One locus deviated from Hardy-Weinberg equilibrium and had a high proportion of null alleles. Those loci will be used in addition to previously developed loci to improve the precision of parentage assignment and population genetics studies on this species.

Sequence data characterization and development of DNA markers for sesame (Sesamum indicum L.)

New DNA sequencing techniques enable researchers obtain large quantity of sequence information, which are deposited in digital storage or could be further mined for other purposes. Sesame (Sesamum indicum L.) is one of very important oilseed crops, its seed oil contains many antioxidant properties making sesame the queen of oil crops. Today, molecular plant breeding technology is indispensable for plant breeders and seed producers. Compared to other seed oil crops the available number of microsatellite markers in sesame is still not sufficient enough for the development of polymorphic markers for breeding and genetic studies. Thus, new approaches or resources are needed for development of microsatellite markers for sesame. In the present study, we utilized a total of 45099 transcribed genomic DNA sequences/expressed sequence tags and mined these sequences for studying frequency of microsatellite motifs, ranging from di- to hexa-nucleotides with four to ten tandem repeats, and repeat numbers greater than 10. Using mined transcribed data, 42 putative microsatellite markers were developed and characterized at the sequence level. However, we did not confirm these markers and have no information about the level of their polymorphisms in sesame in vitro. We discussed the biological meaning of the motif lengths and repeat numbers in the sesame genome.

Abstract 421: Improved detection and identification of microsatellite instability features in colorectal cancer: Implications for immunotherapy

Abstract Colorectal cancers with loss of DNA mismatch repair display microsatellite instability (MSI). These tumors have a better prognosis and an improved response rate to immune check point therapies compared to non-MSI tumors. MSI-positive tumors demonstrate a surprising range of somatic alterations in repetitive sequence tracts. For example, elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) that may be related to functional loss of MSH3. Current MSI tests are based on PCR and capillary electrophoresis. This conventional approach is suboptimal because i) only a small number of microsatellite markers are interrogated per assay, and ii) sensitivity is insufficient for low allelic fraction alleles in heterogeneous tumors. Next generation sequencing permits the inclusion of more microsatellite markers, but these NGS method still rely on PCR methods, which is the major source of artifacts that obscure the true somatic alterations. In this study, we analyzed a series of colorectal cancers using a new sequencing technology that sequences in parallel more than 200 microsatellite regions - we evaluate mono-, di- , tri- and tetranucleotide repeats to provide a broader spectrum of MSI events. This deep sequencing technology provides greater than 2,000X coverage, uses in vitro CRISPR-Cas9 segmentation, and eliminates the need for PCR amplification. Because every read corresponded to a single DNA molecule, we eliminated the artifacts introduced by PCR that obscured true MSI events. Moreover, we improved the sensitivity of detecting minor allele fractions to as low as 0.1% by measuring microsatellite haplotypes. Included in our analysis was new method for somatic copy number changes in 82 cancer genes, by which we can infer chromosomal instability (CIN) status. Among our cases, 10 cancers had MSI when considering both mononucleotide and tetranucleotide repeats. Interestingly, diagnostic testing of two of these tumors were false negatives and were demonstrated to be MSI-high. There were three major types among the 10 MSI cancers: MSI-high, EMAST, and the cancers having both. However, such types were distinguishable only by microsatellites with intermediate length (10 - 20 bp). MSI-high tumors (n = 3) showed no sign of CIN while all the EMAST tumors (n = 4) also showed CIN phenotype. Our results suggest that the current gold standard MSI diagnostic test may have issues with both false negatives and false positives, indicating that NGS approaches are better suited for evaluating MSI status of tumors and consideration of immunotherapy. Citation Format: Giwon Shin, HoJoon Lee, Susan M. Grimes, Matthew A. Kubit, Hanlee P. Ji. Improved detection and identification of microsatellite instability features in colorectal cancer: Implications for immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 421.

On the origin and systematic position of the Azorean goldenrod, Solidago azorica (Asteraceae)

Goldenrods were first collected in the Azores by the German botanist Karl Hochstetter in 1838 and described as an endemic species Solidago azorica. In 1882, Asa Gray placed the name into synonymy of the American seaside goldenrod, S. sempervirens. The taxonomic position and status of the plants in the Azores remained unclear ever since but recent human-mediated introduction from the American coast seemed to be the most likely explanation. Here, I analyze molecular and morphological data and the historical record to test this hypothesis. While morphological differences are not clear and an overall similarity to some specimens from New Foundland is striking, I find that all analyzed Solidago plants from the Azores archipelago differ in their nuclear ITS and ETS sequences plus a number of microsatellite markers from American goldenrods. Furthermore, the historical record suggests existence of goldenrods in the Azores at the time of the arrival of the first settlers and well before Columbus’ first journey. Moreover, large populations were reported from several islands in the 16th century. I conclude that the Azorean plants are native to the Azores and represent a distinct endemic species sharing a common ancestor with S. sempervirens. The Azorean plants represent a geographically isolated, genetically distinct population that is most likely the result of a natural colonization event from the North American coast perhaps via vagrant birds. I reinstate the name S. azorica and describe the morphological differences between S. azorica and S. sempervirens.

Fingerprinting Based on Microsatellite Markers for the Identification of Rice Varieties in Chhattisgarh

Molecular markers are useful tools for determining cultivar identity. The purpose of this study to establish fingerprints of four rice varieties in Chhattisgarh. Microsatellite combines several features of an ultimate molecular marker and they are being used increasingly in various plant genetic studies and applications. The varieties were evaluated utilizing 115 microsatellite markers distributed over the whole rice genome. A total of 160 alleles were detected using 24 microsatellite primer-pairs, and the number of alleles/marker ranged from 2 to 4 with an average of 2.95 alleles/locus. The result suggested that a relatively rapid and small number of microsatellite markers could be used for the identification of rice varieties.

A microsatellite genetic linkage map of black rockfish (Sebastes schlegeli)

Ovoviviparous black rockfish (Sebastes schlegeli) is an important marine fish species for aquaculture and fisheries in China. Genetic information of this species is scarce because of the lack of microsatellite markers. In this study, a large number of microsatellite markers of black rockfish were isolated by constructing microsatellite-enriched libraries. Female- and male-specific genetic linkage maps were constructed using 435 microsatellite markers genotyped in a full-sib family of the fish species. The female linkage map contained 140 microsatellite markers, in which 23 linkage groups had a total genetic length of 1334.1 cM and average inter-marker space of 13.3 cM. The male linkage map contained 156 microsatellite markers, in which 25 linkage groups had a total genetic length of 1359.6 cM and average inter-marker distance of 12.4 cM. The genome coverage of the female and male linkage maps was 68.6% and 69.3%, respectively. The female-to-male ratio of the recombination rate was approximately 1.07:1 in adjacent microsatellite markers. This paper presents the first genetic linkage map of microsatellites in black rockfish. The collection of polymorphic markers and sex-specific linkage maps of black rockfish could be useful for further investigations on parental assignment, population genetics, quantitative trait loci mapping, and marker-assisted selection in related breeding programs.

Development of microsatellite markers in sesame (Sesamum indicum L.)

Sesame (Sesamum indicum L.) is an important oilseed crop with high-quality seed oil and many antioxidant properties. Owing to its commercial and medicinal values, there is a renewed interest among agricultural scientists in this ancient crop. Efforts to strengthen the sesame-specific marker base have been initiated in the recent past; however, the available number of microsatellite markers is still not sufficient for the development of high-resolution genetic linkage maps for important agronomic traits and there is a need to increase the number of informative DNA markers in sesame. In the present study, we developed 25 microsatellite markers by employing the selective hybridization strategy and 95 mining expressed sequence tags of the NCBI database. This new set of microsatellite markers was characterized and screened for genetic diversity in an array of 16 sesame germplasms. Of the 120 SSRs, 92 were polymorphic, consisting of 18 SSRs from selective hybridization and 74 from the EST data set. The number of alleles per microsatellite locus ranged from 2 to 5, with an average of 3.11 alleles. The allele size ranged widely (100-510 bp) among the primer pairs. Polymorphic information content estimates ranged from 0.2982 to 0.912. Jaccard's similarity coefficient ranged from 0.21 to 0.82. The potential of the markers was assessed by diversity analysis using the sequential hierarchical agglomerative nonoverlapping clustering technique of the unweighted pair group method of arithmetic means on a set of 16 genotypes of sesame, including 2 wild species. Results supported the hypothesis that S. malabaricum could be the immediate progenitor of the cultivar species and that S. mulayanum is distinct from S. malabaricum and S. indicum, while suggesting hardly any diversity among the cultivars.

Extension of a set of microsatellite markers for more precise identification of chum salmon Oncorhynchus keta walbaum

A set often microsatellite loci enabling fairly accurate identification of the chum salmon individuals from geographically distant groups was designed at the Laboratory of Genetic Identification, Vavilov Institute of General Genetics, Russian Academy of Sciences. However, identification of the individuals from closely located basins performed using these loci was not sufficiently precise. The present study was focused on the improvement of the resolution of the method through increasing the number microsatellite loci used. In this study, typing of additional microsatellite loci of chum salmon and evaluation of the change of the degree of identification with the increase of the number ofmicrosatellite loci used is described. It was shown that the identification accuracy permanently increased with the increase of the number of microsatellite markers used.

Short communication: Parentage verification of South African Angora goats, using microsatellite markers

South African Angora goats are farmed under extensive production systems in relatively large herds. As a result, breeders make use of group and flock-mating systems that limit accurate parentage recording and selection efficiency. In this study the aim was to refine a panel of microsatellite markers suitable for parentage verification in South African Angora goats. The markers were first evaluated based on the number of alleles, allele frequency, PIC, HE, HO and individual exclusion probability, and secondly as part of a panel. Eighteen markers were tested in 192 South African Angora goats representing different family structures with known and unknown parent information. The final set of microsatellite markers, with the strongest exclusion and the least number of microsatellite markers, consisted of 14 microsatellite markers namely BM1258, BM1329, BM1818, BM7160, CSRD247, HSC, INRA63, INRABERN192, MCM527, OarFCB48, SRCRSP5, SRCRSP8, SRCRSP9 and SRCRSP24. This panel had a combined first-parent exclusion probability of 99.7% and it was possible to perform parental identification in a test family.

Agronomic and molecular traits of the 'Italia Muscat' clone in Sao Francisco River Valley

The objective of this study was to evaluate agronomic and molecular traits of the 'Italia Muscat' clone and compare it with the cv. 'Italia', providing information to support the cultivation of 'Italia Muscat' this cultivar in the São Francisco River Valley. Agronomic characteristics of both clones were evaluated for two seasons in 2004. The characteristics were phenology, bud break (%), bud fertility (%), yield (kg) mass of bunches (g), length and width of bunches (cm), mass of berries (g), length and diameter of berries (mm), TSS (ºBrix), ATT (% titratable acidity) and TSS/TTA. Molecular analysis of seven SSR markers were carried out. The clone 'Italia Muscat' showed larger berries, mass of bunches and better TSS/TA ratio than 'Italia'. The molecular analysis resulted in the same allelic profile in both clones, highlighting the need to use a larger number of microsatellite markers or other molecular technique to allow their discrimination. Based on their morpho-agronomic characteristics, 'Italia Muscat' seems to be a good table grape cultivar alternative for grape growers of São Francisco River Valley.

Effect of consanguinity on Argentinean Angus beef DNA traceability

Since the 1990s several authors have envisaged the use of DNA to certify meat origin. Two major parameters must be assessed before a DNA based traceability protocol can be implemented in the food chain: (i) the information content of a DNA marker set in a specific livestock breed or group of breeds; (ii) the minimum number of DNA markers needed to obtain a statistically acceptable match probability. The objective of the present work was to establish the effect of different levels of inbreeding in the matching efficiency, and the minimum number of microsatellite markers needed, in a DNA based meat traceability program, starting from an 11-microsatellite marker panel. Samples were obtained from beef production farms in South America, where animals are typically bred under pasture-based extensive conditions. Three groups of animals with different consanguinity rates were sampled. Exclusion power (Q) was higher than 0.999998 and match probability lower than 3.01E-08, for the whole set of markers within each group. Both values were affected by consanguinity. To reach a two mismatch criteria exclusion power (Q(2)) of 99.99, six markers were needed in unrelated animals whereas seven markers were needed in related animals. To reach Q(2)=99.9999, 8 and 10 microsatellite markers, respectively, were needed. In general, one or two more microsatellite markers were needed to identify consanguineous animals. This study proved the DNA marker set used to be suitable for the identification of the meat from all slaughtered animals in Argentina, per week, month, and year.

Microsatellite markers of water buffalo, Bubalus bubalis - development, characterisation and linkage disequilibrium studies

BackgroundMicrosatellite markers are highly polymorphic and widely used in genome mapping and population genetic studies in livestock species. River buffalo, Bubalus bubalis is an economically important livestock species, though only a limited number of microsatellite markers have been reported thus far in this species.ResultsIn the present study, using two different approaches 571 microsatellite markers have been characterized for water buffalo. Of the 571 microsatellite markers, 498 were polymorphic with average heterozygosity of 0.51 on a panel of 24 unrelated buffalo. Fisher exact test was used to detect LD between the marker pairs. Among the 137550 pairs of marker combination, 14.58% pairs showed significant LD (P < 0.05). Further to check the suitability of these microsatellite markers to map these on a radiation hybrid map of buffalo genome, the markers were tested on Chinese hamster genomic DNA for amplification. Only seven of these markers showed amplification in Chinese hamster, and thus 564, of these can be added to the radiation hybrid map of this species.ConclusionThe high conservation of cattle microsatellite loci in water buffalo promises the usefulness of the cattle microsatellites markers on buffalo. The polymorphic markers characterised in this study will contribute to genetic linkage and radiation hybrid mapping of water buffalo and population genetic studies.

Methods comparison for microsatellite marker development: Different isolation methods, different yield efficiency

Microsatellite markers have become one kind of the most important molecular tools used in various researches. A large number of microsatellite markers are required for the whole genome survey in the fields of molecular ecology, quantitative genetics and genomics. Therefore, it is extremely necessary to select several versatile, low-cost, efficient and time- and labor-saving methods to develop a large panel of microsatellite markers. In this study, we used Zhikong scallop (Chlamys farreri) as the target species to compare the efficiency of the five methods derived from three strategies for microsatellite marker development. The results showed that the strategy of constructing small insert genomic DNA library resulted in poor efficiency, while the microsatellite-enriched strategy highly improved the isolation efficiency. Although the mining public database strategy is time- and cost-saving, it is difficult to obtain a large number of microsatellite markers, mainly due to the limited sequence data of non-model species deposited in public databases. Based on the results in this study, we recommend two methods, microsatellite-enriched library construction method and FIASCO-colony hybridization method, for large-scale microsatellite marker development. Both methods were derived from the microsatellite-enriched strategy. The experimental results obtained from Zhikong scallop also provide the reference for microsatellite marker development in other species with large genomes.

Notes on the origin of 4BL-5RL rye translocations in common wheat (Triticum aestivumL.)

In order to investigate the origin of two 4B-5R wheat-rye translocations a number of microsatellite markers were considered, (a) which were specific for the rye chromosome arm 5RL and (b) which should enable precise characterisation for the gene pool of a ‘Cornell’ wheat derivative. Seven out of eight markers revealed amplification fragments with the rye control, while the marker WMS0186 amplified only a PCR product with the appropriate chromosome arm of the wheat control. The heterogeneity of the DNA fragment patterns among five wheat-rye translocation lines confirms different wheat backgrounds of the American, Danish/UK, Hungarian, and Swedish sources of the 4B-5R translocations. The homogeneous DNA marker patterns of ‘Viking-hairy neck’ and ‘Cornell Sel. 82a1-2-4-7’ are particularly clear. The corresponding molecular markers together with the cytological data, genomic in situ hybridisation, the physiological investigations, and the historical review support the hypothesis of a common origin of ‘Viking-hairy neck’ and ‘Cornell Sel. 82a1-2-4-7’. The importance of the results for practical breeding and for introgression experiments is discussed.

GENETIC MAPPING OF WHEAT 2BL CHROMOSOME USING SSR MARKERS

The formation of albino plants is among the major h urdles against using the anther culture and isolated microspore culture to produce homozygous plants for new valuable cultivars. Regeneration of albino plants is a phenomenon associated with cereal in vitro culture. The ability to form a high percentage of green plant has been foun d to show a considerable genetic component. Researches with anther culture response from recipr ocal crosses between high and low responsive lines established that the genes for embryo and gre en plant formation in wheat and barley are mainly chromosomally inherited. Molecular markers, were used to locate the genes responsible for green plant formation. There were identified three QTLs o n wheat chromosomes 2AL ( QGpp.kvl-2A ), 2BL (QGpp.kvl-2B.1 ) and 5BL ( QGpp.kvl-5B ) that affects the capacity of regeneration of gree n plants from anther culture in a double haploids population of w heat (Ciano x Walter). Subsequently, two double haploid lines, CW204 and CW219 from the original mapping population Ciano x Walter were used as parents to establish a mapping population segregati ng for the QTL region on chromosome 2BL affecting green plant formation to confirm location of the QTL on 2BL. The approximately 30 cM chromosomal region on the long arm of 2BL, associated with the green plant formation, was mapped before, with a number of microsatellite markers. In this study there are mapped some other microsatellite markers on the long arm of the chrom osome 2B, to generate a more dense map of the region of interest, in order to locate more exactly the gene responsible for the green plant formation in wheat.

Genome-wide amplification and allelotyping of sporadic pituitary adenomas identify novel regions of genetic loss.

Through the use of a candidate gene approach, several previous studies have identified loss of heterozygosity (LOH) at putative tumor-suppressor gene (TSG) loci in sporadic pituitary tumors. This study reports a genome-wide allelotyping by use of 122 microsatellite markers in a large cohort of tumors, consisting of somatotrophinomas and non-functioning adenomas. Samples were first subject to prior whole genome amplification by primer extension pre-amplification (PEP) to circumvent limitations imposed by insufficient DNA for whole-genome analysis with this number of microsatellite markers. The overall mean frequency of loss in invasive tumors was significantly higher than that in their non-invasive counterparts (7 vs. 3% somatotrophinomas; 6 vs. 3% non-functioning adenomas, respectively). Analysis of the mean frequency of LOH, across all markers to individual chromosomal arms, identified 13 chromosomal arms in somatotrophinomas and 10 in non-functioning tumors, with LOH greater than the 99% upper confidence interval calculated for the rate of overall random allelic loss. In the majority of cases, these losses were more frequent in invasive tumors than in their non-invasive counterparts, suggesting these to be markers of tumor progression. Other regions showed similar frequencies of LOH in both invasive and non-invasive tumors, implying these to be early changes in pituitary tumorigenesis. This genome-wide study also revealed chromosomal regions where losses were frequently associated with an individual marker, for example, chromosome arm 1q (LOH > 30%). In some cases, these losses were subtype-specific and were found at a higher frequency in invasive tumors than in their non-invasive counterparts. Identification of these regions of loss provides the first preliminary evidence for the location of novel putative TSGs involved in pituitary tumorigenesis that are, in some cases, subtype-specific. This investigation provides an unbiased estimate of global aberrations in sporadic pituitary tumors as assessed by LOH analysis. The identification of multiple "hotspots" throughout the genome may be a reflection of an unstable chromatin structure that is susceptible to a deletion or epigenetic-mediated gene-silencing events.

Microsatellite instability is not a common feature in medullary breast cancer

Microsatellite instability (MSI) is a form of genomic instability associated with defective DNA mismatch repair in tumors. MSI is found in 85–90% of hereditary nonpolyposis colorectal cancer cases; however, its occurrence in breast carcinogenesis still remains to be clarified. In addition, data are limited on the incidence of MSI in the medullary subtype. The purpose of this study was to investigate the occurrence of MSI in medullary breast cancer (MBC). The study included a total of 16 patients with MBC, nine with typical and seven with atypical histology. The incidence of MSI in five microsatellite loci (D2S123, D3S1611, D17S807, D17S796 and Xq11-12) was determined by comparing paired normal and tumor tissue DNA after PCR amplification from paraffin-embedded tissues. All 16 tumors showed stability at five loci. Although the number of microsatellite markers and DNA samples may limit the value of our results, we conclude that the MSI phenotype is uncommon in human MBC.

Development and characterisation of 140 new microsatellites in apple (Malus x domestica Borkh.)

The availability of suitable genetic markers is essential to efficiently select and breed apple varieties of high quality and with multiple disease resistances. Microsatellites (simple sequence repeats, SSR) are very useful in this respect since they are codominant, highly polymorphic, abundant and reliably reproducible. Over 140 new SSR markers have been developed in apple and tested on a panel of 7 cultivars and 1 breeding selection. Their high level of polymorphism is expressed with an average of 6.1 alleles per locus and an average heterozygosity (H) of 0.74. Of all SSR markers, 115 have been positioned on a genetic linkage map of the cross ‘Fiesta’ × ‘Discovery’. As a result, all 17 linkage groups, corresponding to the 17 chromosomes of apple, were identified. Each chromosome carries at least two SSR markers, allowing the alignment of any apple molecular marker map both with regard to identification as well as to orientation of the linkage groups. To test the degree of conservation of the SSR flanking regions and the transferability of the SSR markers to other Rosaceae species, 15 primer pairs were tested on a series of Maloideae and Amygdaloideae species. The usefulness of the newly developed microsatellites in genetic mapping is demonstrated by means of the genetic linkage map. The possibility of constructing a global apple linkage map and the impact of such a number of microsatellite markers on gene and QTL mapping is discussed.

Suppression of tumorigenicity of rat liver epithelial tumor cell lines by a putative human 11p11.2-p12 liver tumor suppressor locus.

We have previously identified and mapped a locus within human chromosome 11p11.2-p12 that suppresses the tumorigenic potential of a rat liver tumor cell line (termed GN6TF) which contains well defined chromosomal aberrations involving rat chromosomes 1, 4, 7, and 10. In the present study, we investigated the potential of this human 11p11.2-p12 liver tumor suppressor locus to suppress the tumorigenic potential of two other rat liver tumor cell lines (GN3TG and GP10TA) following microcell-mediated introduction of human chromosome 11. These tumor cell lines are aneuploid and contain chromosomal abnormalities that are similar to the GN6TF tumor line. The tumorigenic potential and other phenotypic characteristics of GN3TG-11neo and GP10TA-11neo microcell hybrid (MCH) cell lines were variable, and dependent upon the status of the introduced human chromosome 11. MCH cell lines that retained the region of 11p11. 2-p12 delineated by microsatellite markers D11S1385 and D11S903 exhibited suppression of tumorigenicity in vivo (decrease in tumorigenicity and/or elongation of latency), whereas, the tumorigenic potential of one MCH line that lacked markers in this region of human 11p11.2-p12, but retained flanking markers, was not changed from that of the parental tumor cell line. The chromosomal interval between microsatellite markers D11S1385 and D11S903 encompasses the previously localized minimal liver tumor suppressor region, suggesting that a common locus is responsible for tumor suppression among the rat liver tumor cell lines examined. The results of the present study have verified the presence of a liver tumor suppressor locus within human 11p11.2-p12, and have identified a substantial number of microsatellite markers that are closely linked to this tumor suppressor region. These chromosomal markers will facilitate positional cloning of candidate genes from this region, and may prove useful for determining the involvement of this locus in the pathogenesis of human liver cancer.