Showing papers by "Stephen J. O'Brien published in 2001"

Molecular phylogenetics and the origins of placental mammals

Abstract: The precise hierarchy of ancient divergence events that led to the present assemblage of modern placental mammals has been an area of controversy among morphologists, palaeontologists and molecular evolutionists. Here we address the potential weaknesses of limited character and taxon sampling in a comprehensive molecular phylogenetic analysis of 64 species sampled across all extant orders of placental mammals. We examined sequence variation in 18 homologous gene segments (including nearly 10,000 base pairs) that were selected for maximal phylogenetic informativeness in resolving the hierarchy of early mammalian divergence. Phylogenetic analyses identify four primary superordinal clades: (I) Afrotheria (elephants, manatees, hyraxes, tenrecs, aardvark and elephant shrews); (II) Xenarthra (sloths, anteaters and armadillos); (III) Glires (rodents and lagomorphs), as a sister taxon to primates, flying lemurs and tree shrews; and (IV) the remaining orders of placental mammals (cetaceans, artiodactyls, perissodactyls, carnivores, pangolins, bats and core insectivores). Our results provide new insight into the pattern of the early placental mammal radiation.

Resolution of the early placental mammal radiation using Bayesian phylogenetics

Abstract: Molecular phylogenetic studies have resolved placental mammals into four major groups, but have not established the full hierarchy of interordinal relationships, including the position of the root. The latter is critical for understanding the early biogeographic history of placentals. We investigated placental phylogeny using Bayesian and maximum-likelihood methods and a 16.4-kilobase molecular data set. Interordinal relationships are almost entirely resolved. The basal split is between Afrotheria and other placentals, at about 103 million years, and may be accounted for by the separation of South America and Africa in the Cretaceous. Crown-group Eutheria may have their most recent common ancestry in the Southern Hemisphere (Gondwana).

Effect of a single amino acid change in MHC class I molecules on the rate of progression to AIDS.

Abstract: Background From studies of genetic polymorphisms and the rate of progression from human immunodeficiency virus type 1 (HIV-1) infection to the acquired immunodeficiency syndrome (AIDS), it appears that the strongest susceptibility is conferred by the major-histocompatibility-complex (MHC) class I type HLA-B*35,Cw*04 allele. However, cytotoxic T-lymphocyte responses have been observed against HIV-1 epitopes presented by HLA-B*3501, the most common HLA-B*35 subtype. We examined subtypes of HLA-B*35 in five cohorts and analyzed the relation of structural differences between HLA-B*35 subtypes to the risk of progression to AIDS. Methods Genotyping of HLA class I loci was performed for 850 patients who seroconverted and had known dates of HIV-1 infection. Survival analyses with respect to the rate of progression to AIDS were performed to identify the effects of closely related HLA-B*35 subtypes with different peptide-binding specificities. Results HLA-B*35 subtypes were divided into two groups according to peptide-binding specificity: the HLA-B*35-PY group, which consists primarily of HLA-B*3501 and binds epitopes with proline in position 2 and tyrosine in position 9; and the more broadly reactive HLA-B*35-Px group, which also binds epitopes with proline in position 2 but can bind several different amino acids (not including tyrosine) in position 9. The influence of HLA-B*35 in accelerating progression to AIDS was completely attributable to HLA-B*35-Px alleles, some of which differ from HLA-B*35-PY alleles by only one amino acid residue. Conclusions This analysis shows that, in patients with HIV-1 infection, a single amino acid change in HLA molecules has a substantial effect on the rate of progression to AIDS. The different consequences of HLA-B*35-PY and HLA-B*35-Px in terms of disease progression highlight the importance of the epitope specificities of closely related class I molecules in the immune defense against HIV-1.

Reliability, validity, and responsiveness of four knee outcome scales for athletic patients.

Abstract: Background: Many patient-based knee-rating scales are available for the evaluation of athletic patients. However, there is little information on the measurement properties of these instruments and therefore no evidence to support the use of one questionnaire rather than another. The goal of the present study was to determine the reliability, validity, and responsiveness of four knee-rating scales commonly used for the evaluation of athletic patients: the Lysholm scale, the subjective components of the Cincinnati knee-rating system, the American Academy of Orthopaedic Surgeons sports knee-rating scale, and the Activities of Daily Living scale of the Knee Outcome Survey. Methods: All patients in the study had a disorder of the knee and were active in sports (a Tegner score of 4 points). Forty-one patients who had a knee disorder that had stabilized and who were not receiving treatment were administered all four questionnaires at baseline and again at a mean of 5.2 days (range, two to fourteen days) later to test reliability. Forty-two patients were administered the scales at baseline and at a minimum of three months after treatment to test responsiveness. The responses of 133 patients at baseline were studied to test construct validity. Results: The reliability was high for all scales, with the intraclass correlation coefficient ranging from 0.88 to 0.95. As for construct validity, the correlations among the knee scales ranged from 0.70 to 0.85 and those between the knee scales and the physical component scale of the Short Form-36 (SF-36) and the patient and clinician severity ratings ranged from 0.59 to 0.77. Responsiveness, measured with the standardized response mean, ranged from 0.8 for the Cincinnati knee-rating system to 1.1 for the Activities of Daily Living scale. Conclusions: All four scales satisfied our criteria for reliability, validity, and responsiveness, and all are acceptable for use in clinical research.

Genetic Evidence for Two Species of Elephant in Africa

Abstract: Elephants from the tropical forests of Africa are morphologically distinct from savannah or bush elephants. Dart-biopsy samples from 195 free-ranging African elephants in 21 populations were examined for DNA sequence variation in four nuclear genes (1732 base pairs). Phylogenetic distinctions between African forest elephant and savannah elephant populations corresponded to 58% of the difference in the same genes between elephant genera Loxodonta (African) and Elephas (Asian). Large genetic distance, multiple genetically fixed nucleotide site differences, morphological and habitat distinctions, and extremely limited hybridization of gene flow between forest and savannah elephants support the recognition and conservation management of two African species: Loxodonta africana and Loxodonta cyclotis.

Phylogeography, population history and conservation genetics of jaguars (Panthera onca, Mammalia, Felidae).

Abstract: The jaguar ( Panthera onca ), the largest felid in the American Continent, is currently threatened by habitat loss, fragmentation and human persecution. We have investigated the genetic diversity, population structure and demographic history of jaguars across their geographical range by analysing 715 base pairs of the mitochondrial DNA (mtDNA) control region and 29 microsatellite loci in ∪ ∪ ∪ 40 individuals sampled from Mexico to southern Brazil. Jaguars display low to moderate levels of mtDNA diversity and medium to high levels of microsatellite size variation, and show evidence of a recent demographic expansion. We estimate that extant jaguar mtDNA lineages arose 280 000‐510 000 years ago (95% CI 137 000‐830 000 years ago), a younger date than suggested by available fossil data. No strong geographical structure was observed, in contrast to previously proposed subspecific partitions. However, major geographical barriers such as the Amazon river and the Darien straits between northern South America and Central America appear to have restricted historical gene flow in this species, producing measurable genetic differentiation. Jaguars could be divided into four incompletely isolated phylogeographic groups, and further sampling may reveal a finer pattern of subdivision or isolation by distance on a regional level. Operational conservation units for this species can be defined on a biome or ecosystem scale, but should take into account the historical barriers to dispersal identified here. Conservation strategies for jaguars should aim to maintain high levels of gene flow over broad geographical areas, possibly through active management of disconnected populations on a regional scale.

Canine and Feline Parvoviruses Can Use Human or Feline Transferrin Receptors To Bind, Enter, and Infect Cells

Abstract: Canine parvovirus (CPV) enters and infects cells by a dynamin-dependent, clathrin-mediated endocytic pathway, and viral capsids colocalize with transferrin in perinuclear vesicles of cells shortly after entry (J S L Parker and C R Parrish, J Virol 74:1919–1930, 2000) Here we report that CPV and feline panleukopenia virus (FPV), a closely related parvovirus, bind to the human and feline transferrin receptors (TfRs) and use these receptors to enter and infect cells Capsids did not detectably bind or enter quail QT35 cells or a Chinese hamster ovary (CHO) cell-derived cell line that lacks any TfR (TRVb cells) However, capsids bound and were endocytosed into QT35 cells and CHO-derived TRVb-1 cells that expressed the human TfR TRVb-1 cells or TRVb cells transiently expressing the feline TfR were susceptible to infection by CPV and FPV, but the parental TRVb cells were not We screened a panel of feline-mouse hybrid cells for susceptibility to FPV infection and found that only those cells that possessed feline chromosome C2 were susceptible The feline TfR gene (TRFC) also mapped to feline chromosome C2 These data indicate that cell susceptibility for these viruses is determined by the TfR

Molecular Dating and Biogeography of the Early Placental Mammal Radiation

Abstract: The timing and phylogenetic hierarchy of early placental mammal divergences was determined based on combined DNA sequence analysis of 18 gene segments (9779 bp) from 64 species. Using rooted and unrooted phylogenies derived from distinct theoretical approaches, strong support for the divergence of four principal clades of eutherian mammals was achieved. Minimum divergence dates of the earliest nodes in the placental mammal phylogeny were estimated with a quartet-based maximum-likelihood method that accommodates rate variation among lineages using conservative fossil calibrations from nine different nodes in the eutherian tree. These minimum estimates resolve the earliest placental mammal divergence nodes at periods between 64 and 104 million years ago, in essentially every case predating the Cretaceous-Tertiary (K-T) boundary. The pattern and timing of these divergences allow a geographic interpretation of the primary branching events in eutherian history, likely originating in the southern supercontinent Gondwanaland coincident with its breakup into Africa and South America 95-105 million years ago. We propose an integrated genomic, paleontological, and biogeographic hypothesis to account for these earliest splits on the placental mammal family tree and address current discrepancies between fossil and molecular evidence.

Evolution of mammalian genome organization inferred from comparative gene mapping

Abstract: Comparative genome analyses, including chromosome painting in over 40 diverse mammalian species, ordered gene maps from several representatives of different mammalian and vertebrate orders, and large-scale sequencing of the human and mouse genomes are beginning to provide insight into the rates and patterns of chromosomal evolution on a whole-genome scale, as well as into the forces that have sculpted the genomes of extant mammalian species.

Phylogenetics, genome diversity and origin of modern leopard, Panthera pardus

Abstract: Leopards, Panthera pardus, are widely distributed across southern Asia and sub-Saharan Africa. The extent and phylogeographic patterns of molecular genetic diversity were addressed in a survey of 77 leopards from known geographical locales representing 13 of the 27 classical trinomial subspecies. Phylogenetic analysis of mitochondrial DNA sequences (727 bp of NADH5 and control region) and 25 polymorphic microsatellite loci revealed abundant diversity that could be partitioned into a minimum of nine discrete populations, tentatively named here as revised subspecies: P. pardus pardus, P. p. nimr, P. p. saxicolor, P. p. fusca, P. p. kotiya, P. p. delacouri, P. p. japonensis, P. p. orientalis and P. p. melas. However, because of limited sampling of African populations, this may be an underestimate of modern phylogeographic population structure. Combined phylogeographic and population diversity estimates support an origin for modern leopard lineages 470,000-825,000 years ago in Africa followed by their migration into and across Asia more recently (170,000-300,000 years ago). Recent demographic reductions likely have led to genetic impoverishment in P. p. orientalis and in the island subspecies P. p. kotiya.

Racial Differences in HLA Class II Associations with Hepatitis C Virus Outcomes

Abstract: A broad, vigorous CD4 T cell response, mediated by class II human leukocyte antigens (HLAs), favors hepatitis C virus (HCV) clearance. HLA-DQB1*0301 has been associated with viral clearance in an ethnically homogeneous cohort. To validate this association and to identify other class II associations in an ethnically varied cohort, molecular class II HLA typing was performed on 200 HCV clearance and 374 matched persistently infected subjects. HLA-DQB1*0301 was weakly associated with viral clearance in combined ethnic groups (odds ratio [OR], 0.72; 95% confidence interval [CI], 0.53-0.97) but was stronger in black subjects. In white subjects, viral clearance was associated with DRB1*0101 (OR, 0.32; 95% CI, 0.17-0.60) and its DQB1*0501 haplotype, whereas viral persistence was associated with DRB1*0301 (OR, 2.36; 95% CI, 1.23-4.52) and its DQB1*0201 haplotype. These results support a role for class II alleles in the immune response to HCV and underscore the importance of studying genetic associations in an ethnically diverse cohort.

Immunologic and virologic response to highly active antiretroviral therapy in the Multicenter AIDS Cohort Study

Abstract: Objectives To evaluate prior antiretroviral therapy experience and host characteristics as determinants of immunologic and virologic response to highly active antiretroviral therapy (HAART). Methods We studied 397 men from the Multicenter AIDS Cohort Study (MACS) who initiated HAART between October 1995 and March 1999. CD4 cell count and HIV-1 RNA responses to HAART were measured at the first visit following HAART (short-term) and extending from the first visit to approximately 33 months after HAART (long-term). Prior antiretroviral experience was classified into three groups based on antiretroviral therapy use during the 5 years prior to HAART. Age, race and host genetic characteristics also were assessed for their effects on treatment response. Results Better short- and long-term CD4 cell and HIV-1 RNA responses were observed in the treatment-naive users. Intermittently and consistently experienced users did not significantly differ in response. Whereas race did not independently affect response, among those initiating HAART with > 400 x 10(6) CD4 cells/l, younger age and the Delta32 CCR5 genotype were associated with a better short-term CD4 cell response. There was a suggestion that having the protective CCR5 genotype also was associated with a better long-term CD4 cell response. Conclusion Immunologic and virologic response to HAART was stronger in individuals who had no prior experience with the antiretroviral therapy agents subsequently included in their initial HAART regimen. Age, level of immune competence and immunogenetics appeared to play a role in the subsequent immune reconstitution following use of highly effective HIV therapy.

Markers for mapping by admixture linkage disequilibrium in African American and Hispanic populations.

Abstract: Population linkage disequilibrium occurs as a consequence of mutation, selection, genetic drift, and population substructure produced by admixture of genetically distinct ethnic populations. African American and Hispanic ethnic groups have a history of significant gene flow among parent groups, which can be of value in affecting genome scans for disease-gene discovery in the case-control and transmission/disequilibrium test designs. Disease-gene discovery using mapping by admixture linkage disequilibrium (MALD) requires a map of polymorphic markers that differentiate between the founding populations, along with differences in disease-gene allele frequencies. We describe markers appropriate for MALD mapping by assessing allele frequencies of 744 short tandem repeats (STRs) in African Americans, Hispanics, European Americans, and Asians, by choosing STR markers that have large differences in composite δ, log-likelihood ratios, and/or I*(2) for MALD. Additional markers can be added to this MALD map by utilization of the rapidly growing single-nucleotide–polymorphism databases and the literature, to achieve a 3–10-cM scanning scale. The map will be useful for studies of diseases, including prostate and breast cancer, diabetes, hypertension, and end-stage renal disease, that have large differences in incidence between the founding populations of either Hispanics or African Americans.

Hepatitis C Virus Load Is Associated with Human Immunodeficiency Virus Type 1 Disease Progression in Hemophiliacs

Abstract: Hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) coinfection is common in hemophiliacs and injection drug users. To assess the interaction between HCV load and HIV-1 disease progression, we examined 207 HIV-1/HCV-coinfected patients. Patients were followed prospectively for approximately 7 years, and annual measurements of CD4(+) cell counts and HCV and HIV-1 loads were obtained. Survival analysis was used to define the independent effects of HCV load on HIV-1 progression. After controlling for CD4(+) cell count and HIV-1 RNA level, every 10-fold increase in baseline HCV RNA was associated with a relative risk (RR) for clinical progression to acquired immunodeficiency syndrome (AIDS) of 1.66 (95% confidence interval [CI], 1.10-2.51; P=.016) and an RR for AIDS-related mortality of 1.54 (95% CI, 1.03-2.30; P=.036). These findings emphasize the need for further research regarding the use of HIV-1- and HCV-specific therapy in coinfected individuals.

Patterns of Genetic Diversity in Remaining Giant Panda Populations

Abstract: The giant panda ( Ailuropoda melanoleuca ) is among the more familiar symbols of species conser- vation. The protection of giant panda populations has been aided recently by the establishment of more and better-managed reserves in existing panda habitat located in six mountain ranges in western China. These re- maining populations are becoming increasingly isolated from one another, however, leading to the concern that historic patterns of gene flow will be disrupted and that reduced population sizes will lead to diminished genetic variability. We analyzed four categories of molecular genetic markers (mtDNA restriction-fragment- length polymorphisms (RFLP), mtDNA control region sequences, nuclear multilocus DNA fingerprints, and mi- crosatellite size variation) in giant pandas from three mountain populations (Qionglai, Minshan, and Qin- ling) to assess current levels of genetic diversity and to detect evidence of historic population subdivisions. The three populations had moderate levels of genetic diversity compared with similarly studied carnivores for all four gene measures, with a slight but consistent reduction in variability apparent in the smaller Qinling population. That population also showed significant differentiation consistent with its isolation since historic times. From a strictly genetic perspective, the giant panda species and the three populations look promising insofar as they have retained a large amount of genetic diversity in each population, although evidence of re- cent population reduction—likely from habitat loss—is apparent. Ecological management to increase habi- tat, population expansion, and gene flow would seem an effective strategy to stabilize the decline of this en- dangered species.

Tara, a novel F-actin binding protein, associates with the Trio guanine nucleotide exchange factor and regulates actin cytoskeletal organization

Abstract: Reorganization of the actin cytoskeleton is essential to numerous cellular processes including cell locomotion and cytokinesis. This actin remodeling is regulated in part by Rho family GTPases. Previous studies implicated Trio, a Dbl-homology guanine nucleotide exchange factor with two exchange factor domains, in regulating actin cytoskeleton reorganization, cell motility and cell growth via activation of Rho GTPases. Trio is essential for mouse embryonic development and Trio-deficiency is associated with abnormal skeletal muscle and neural tissue development. Furthermore, genetic analyses in Caenorhabditis elegans and Drosophila demonstrate a role for trio-like genes in cell migration and axon guidance. Herein we characterize a novel Trio-binding protein, Tara, that is comprised of an N-terminal pleckstrin homology domain and a C-terminal coiled-coil region. Trio and Tara associate as assessed by the yeast interaction-trap assays and mammalian co-immunoprecipitation studies. Ectopically expressed Tara localizes to F-actin in a periodic pattern that is highly similar to the pattern of myosin II. Furthermore, a direct interaction between Tara and F-actin is indicated by in vitro binding studies. Cells that transiently or stably overexpress Tara display an extensively flattened cell morphology with enhanced stress fibers and cortical F-actin. Tara expression does not alter the ability of the cell to attach or to initially spread, but rather increases cell spreading following these initial events. Tara stabilizes F-actin structures as indicated by the relative resistance of Tara-expressing cells to the F-actin destabilizer Latrunculin B. We propose that Tara regulates actin cytoskeletal organization by directly binding and stabilizing F-actin, and that the localized formation of Tara and Trio complexes functions to coordinate actin remodeling.

The anatomy and histology of the rotator interval capsule of the shoulder

Abstract: Forty-seven rotator interval regions from fetuses and 10 fresh-frozen rotator interval regions from adult cadavers were evaluated by gross dissection and light microscopy Specimens from adults also were evaluated with ultrasound and magnetic resonance imaging An analysis of 37 fetal specimens (> 14 weeks gestation) revealed two rotator interval types: Type I (9 of 37) was defined by a contiguous bridge of capsule consisting of poorly organized collagen fibers A Type II rotator interval (28 of 37) had a complete defect covered by only a thin layer of synovium Similar to the Type II rotator interval in the fetus, a rotator interval defect was present in six of eight specimens from adults Histologically, the capsular tissue within the rotator interval consisted of poorly organized collagen fibers in specimens from the fetus and adult Maximal opening of the rotator interval was seen by ultrasound with internal rotation and downward traction of the hyperextended arm in the coronal, oblique, and sagittal planes Magnetic resonance imaging of the rotator interval region permitted anatomic evaluation The complete absence of tissue in 28 of 37 fetuses suggests that the rotator interval defect is congenital The authors recommend that surgeons carefully evaluate the integrity of the tissue within the rotator interval When rotator interval closure is desired such as in patients with a persistent sulcus sign after arthroscopic stabilization, suturing the edges of more substantial tissue immediately adjacent to the boundaries of the rotator interval region would seem prudent

The Pattern of Phylogenomic Evolution of the Canidae

Abstract: Canidae species fall into two categories with respect to their chromosome composition: those with high numbered largely acrocentric karyotypes and others with a low numbered principally metacentric karyotype. Those species with low numbered metacentric karyotypes are derived from multiple independent fusions of chromosome segments found as acrocentric chromosomes in the high numbered species. Extensive chromosome homology is apparent among acrocentric chromosome arms within Canidae species; however, little chromosome arm homology exists between Canidae species and those from other Carnivore families. Here we use Zoo-FISH (fluorescent in situ hybridization, also called chromosomal painting) probes from flow-sorted chromosomes of the Japanese raccoon dog (Nyctereutes procyonoides) to examine two phylogenetically divergent canids, the arctic fox (Alopex lagopus) and the crab-eating fox (Cerdocyon thous). The results affirm intra-canid chromosome homologies, also implicated by G-banding. In addition, painting probes from domestic cat (Felis catus), representative of the ancestral carnivore karyotype (ACK), and giant panda (Ailuropoda melanoleuca) were used to define primitive homologous segments apparent between canids and other carnivore families. Canid chromosomes seem unique among carnivores in that many canid chromosome arms are mosaics of two to four homology segments of the ACK chromosome arms. The mosaic pattern apparently preceded the divergence of modern canid species since conserved homology segments among different canid species are common, even though those segments are rearranged relative to the ancestral carnivore genome arrangement. The results indicate an ancestral episode of extensive centric fission leading to an ancestral canid genome organization that was subsequently reorganized by multiple chromosome fusion events in some but not all Canidae lineages.

On Choosing Mammalian Genomes for Sequencing

Abstract: With the human genome sequenced and the genome of the mouse almost complete, which mammalian species are next in line to have their genomes sequenced? In their Perspective, O9Brien and colleagues debate the many criteria that could be used to select the next lucky mammal to have the secrets of its genome decoded.

Patterns of Size Homoplasy at 10 Microsatellite Loci in Pumas (Puma concolor)

Abstract: Microsatellites, repetitive simple sequences of 1–6 nt in length, are abundant in eukaryotic genomes (Weber 1990a). Because of extensive variability in the number of repeat units for any one locus among members of a population, microsatellite loci exhibit high polymorphism. Microsatellite variation has become a useful class of genetic markers in population assessment for numerous species for questions of genetic identification, parentage, kinship, and population variability assessment (Jarne and Lagoda 1996; Goldstein and Pollock 1997). The high level of polymorphism at microsatellite loci is believed to result from slipped-strand mispairing during DNA replication (Levinson and Gutman 1987; Weber 1990b; Weber and Wong 1993; Krugylak et al. 1998), most commonly causing the gain or loss of one or more repeat units. This mutation mechanism would be expected to generate allelic homoplasy, i.e., comigrating allele size fragments which are not identical by descent or in DNA sequence among different individuals. Because mutational slippage does not conform to the infinite-alleles model (Kimura and Crow 1964), a stepwise mutation model (SMM) (Ohta and Kimura 1973; Chakraborty and Nei 1982) has been invoked to explain allele frequency distributions and population variability at microsatellite loci (Valdez, Slatkin, and Freimer 1993; Kimmel et al. 1996). A distinguishing feature of the two models is that homoplasy is not considered under the infinite-alleles model, while it is an expectation of the stepwise mutation model (Viard et al. 1998). The SMM (but not the infinite-alleles model) makes the assumption that differences in allelic length are due to variation in the number of repeat units and not to insertions and deletions in the flanking sequences. Allelic size homoplasy, a condition under which comigrating alleles represent different sequence motifs, has been demonstrated through sequence analysis of electromorphs of compound or imperfect repeats of primates (Blanquer-Maumont and Crouau-Roy 1995), several fish species (Angers and Bernatchez 1997), invertebrates (Viard et al. 1998), and the fungus Candida albicans (Metzgar et al. 1998). Insertion and deletion events in genomic regions flanking microsatellites confer allelic size homoplasy in several marine turtle species (FitzSimmons et al. 1995) and humans (Homo sa-

Cell culture forensics.

Abstract: Genomics, proteomics, vaccinology, transgenics, stem cell—advances in all these areas critically stack on the shoulders of tissue culture, our ability to cultivate an organism's living cells in plastic dishes. Nutritional trial and error for decades of painstaking cell gardening laid the groundwork for the several thousand human primary cell explants and immortal tumor lines available to modern biotechnology. Now, the 50-year-old problem of cell line misidentification from cell contamination, mislabeling, or, in some cases, conscious deceit, has a brand-new tool for cell and individual validation, a composite short tandem repeat (STR, also called genomic microsatellite) genotype signature (1). The new advances, the latest in cell identification technologies, represent the most advanced and powerful forensic approach to dispense with the embarrassing, expensive, and maddening cell contamination that occurs in biomedical laboratories.

rPatterns of mtDNA and microsatellite variation in an island and mainland population of guanacos in southern Chile

Abstract: The archaeological record indicates that guanacos inhabited the Patagonia of Chile and Argentina about 13,600 years ago, but were unable to migrate further south owing to the presence of glacial and water barriers that covered much of southern South America including the island of Tierra del Fuego. As environmental and ecological conditions improved, guanacos, along with other large mammals including horses, colonized the area. As a result of continued world-wide glacial melting, ocean levels rose and Tierra del Fuego became isolated from the mainland approximately 8000 years ago. Although island populations generally exhibit lower levels of genetic variation than their counterpart mainland populations, it is difficult to predict how much less variation island populations will exhibit. An analysis of mitochondrial cytochrome b and ATPase-8 sequences and 15 nuclear microsatellite loci revealed that both populations retained appreciable genetic diversity. The island population, however, exhibited much less variation than the mainland population. Measures of genetic variation revealed modest, but significant genetic differentiation, consistent with separation of the two populations approximately 8000 years ago. The assessment of levels of genetic diversity and population differentiation among populations of the wild South American camelids is becoming increasingly important as interest mounts in their utilization as a renewable resource.

Integration of the feline radiation hybrid and linkage maps.

Abstract: The recent development of genome mapping resources for the domestic cat provides a unique opportunity to study comparative medicine in this companion animal which can inform and benefit both veterinary and human biomedical concerns. We describe here the integration and order comparison of the feline radiation hybrid (RH) map with the feline interspecies backcross (ISB) genetic linkage map, constructed by a backcross of F1 hybrids between domestic cat (Felis catus) and the Asian leopard cat (Prionailurus bengalensis). Of 253 microsatellite loci mapped in the ISB, 176 equivalently spaced markers were ordered among a framework of 424 Type I coding markers in the RH map. The integration of the RH and ISB maps resolves the orientation of multiple linkage groups and singleton loci from the ISB genetic map. This integrated map provides the foundation for gene mapping assessments in the domestic cat and in related species of the Felidae family.

A Radiation Hybrid Mapping Panel for the Rhesus Macaque

Abstract: The genomes of nonhuman primates have recently become highly visible candidates for full genome analysis, as they provide powerful models of human disease and a better understanding of the evolution of the human genome. We describe the creation of a 5000 rad radiation hybrid (RH) mapping panel for the rhesus macaque. Duplicate genotypes of 84 microsatellite and coding gene sequence tagged sites from six macaque chromosomes produced an estimated whole genome retention frequency of 0.33. To test the mapping ability of the panel, we constructed RH maps for macaque chromosomes 7 and 9 and compared them to orthologous locus orders in existing human and baboon maps derived from different methodologies. Concordant marker order between all three species maps suggests that the current panel represents a powerful mapping resource for generating high-density comparative maps of the rhesus macaque and other species genomes.

Fractures About the Orbit in Professional American Football Players

Abstract: A retrospective review was performed of records for players who suffered fractures about the orbit during participation in officially sponsored activities of the National Football League from 1980 to 1997. Clinical information was obtained on 19 of 29 players who sustained orbital fractures. The most common signs and symptoms included decreased visual acuity (74%, 14), decreased eye movement (42%, 8), hyphema (37%, 7), and infraorbital numbness (21%, 4). The mechanisms of injury were a digital poke (74%, 14) and blunt facial trauma (26%, 5). There were significantly more orbital fractures than zygomatic fractures suffered by offensive linemen as compared with all other positions. Fifteen of 19 players were managed with surgical reconstruction; 4 players were treated nonoperatively. The mean time from injury to surgical procedure was 7.7 days (range, 0 to 42). The mean interval to follow-up was 45.6 months (range, 3 to 146). At follow-up examination, eight (53%) of the patients treated surgically still reported diplopia with upper field gaze. Three of the four patients treated nonoperatively were asymptomatic. The mean time lost from games or practice was 25 days (range, 5 to 56). Ultimately, 17 (89%) players with orbital fractures were able to return to full football activities. Two patients were unable to resume their careers because of residual visual impairment.