Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Tribes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources
PubMed2005

A phylogeny of the schoenoid sedges (Cyperaceae: Schoeneae) based on plastid DNA sequences, with special reference to the genera found in Africa.

Despite its large size (about 700 species), the australy-centred sedge tribe Schoeneae has received little explicit phylogenetic study, especially using molecular data. As a result, generic relationships are poorly understood, and even the monophyly of the tribe is open to question. In this study, plastid DNA sequences (rbcL, trnL-trnF, and rps16) drawn from a broad array of Schoeneae are analysed using Bayesian and parsimony-based approaches to infer a framework phylogeny for the tribe. Both analytical methods broadly support the monophyly of Schoeneae, Bayesian methods doing so with good support. Within the schoenoid clade, there is strong support for a series of monophyletic generic groupings whose interrelationships are unclear. These lineages form a large polytomy at the base of Schoeneae that may be indicative of past radiation, probably following the fragmentation of Gondwana. Most of these lineages contain both African and non-African members, suggesting a history of intercontinental dispersal. The results of this study clearly identify the relationships of the African-endemic schoenoid genera and demonstrate that the African-Australasian genus Tetraria, like Costularia, is polyphyletic. This pattern is morphologically consistent and suggests that these genera require realignment.

Africa↗
PubMed2006

Neotomine-peromyscine rodent systematics based on combined analyses of nuclear and mitochondrial DNA sequences.

Recently, sequences from two nuclear genes (exon 6 of the dentin matrix protein 1 gene and intron 7 of the beta-fibrinogen gene) and one mitochondrial gene (cytochrome b gene) were used independently in an attempt to resolve phylogenetic relationships within the neotomine-peromyscine complex. Although these studies provided testable hypotheses regarding this group of rodents, the affinities of certain tribes and genera remain uncertain. To elucidate these relationships, the three data partitions were tested for heterogeneity and then concatenated according to conditional data combination and total evidence approaches. Support was found for five clades, four of which correspond to well recognized tribes (the Neotomini, Peromyscini=Reithrodontomyini, Baiomyini, and Tylomyini). Recommendations are made regarding the recognition of Ochrotomys as a tribe of its own, the Ochrotomyini, paralleling other recent findings. The Peromyscini, Baiomyini, and Ochrotomyini are unresolved in relation to each other, but as a whole are sister to the Neotomini. The Tylomyini is basal to all clades. It appears that combined data from the nuclear and mitochondrial genes (analyzing all three partitions simultaneously) resulted in the best phylogenetic hypothesis regarding the complex.

Animals↗
PubMed2006

Evolutionary relationships among the Scarabaeini (Coleoptera: Scarabaeidae) based on combined molecular and morphological data.

The Scarabaeini is an old world tribe of ball-rolling dung beetles that have origins dating back to at least the mid-upper Miocene (19-8 million years ago). The tribe has received little to no attention in morphological or molecular phylogenetics. We obtained sequence data from the mitochondrial cytochrome oxidase subunit I (1,197 bp) and 16S ribosomal RNA (461 bp) genes for 25 species of the Scarabaeini in an attempt to further resolve broad phylogenetic relationships within this tribe. Sequence data from both markers along with 216 morphological and 3 biological characters were analysed separately and combined. Independent analyses showed poorly resolved trees with many of the intermediate and basal nodes collapsed by low bootstrap values. Many sites in both genes exhibited strong A+T nucleotide bias and high interlineage divergences. The combined analysis revealed a number of well supported relationships such as the monophyly of the nocturnal species Scarabaeus satyrus, S. [Neateuchus] proboscideus, and S. zambesianus. Furthermore, the total evidence tree suggested to elevate S. (Pachysoma) to the status of an independent genus, Pachysoma, as a sister taxon to a clade containing Pachylomerus femoralis and Scarabaeus sensu lato. Within the latter, the following subgenera were maintained by the combination of data sets: S. (Scarabaeolus), S. (Sceliages), and S. (Kheper). Both, feeding specialisation and food relocation behaviour, were inferred to be polyphyletic in the Scarabaeini. Total evidence analysis found no support for common ancestry of Scarabaeini and Eucraniini.

Animals↗
PubMed2006

Phylogeny and biogeography of 91 species of heroine cichlids (Teleostei: Cichlidae) based on sequences of the cytochrome b gene.

Heroini constitute the second largest tribe of Neotropical cichlids and show their greatest diversity in Mesoamerica. Although heroine species are morphologically and ecologically very diverse, they were all historically assigned to one single genus, Cichlasoma that was never formally revised from a phylogenetic point of view. Here, we present the most comprehensive molecular phylogeny of the tribe Heroini to date, based on the complete DNA sequence of the mitochondrial gene cytochrome b, and the analysis of 204 individuals representing 91 species. Phylogenetic analyses did not support the monophyly of heroines because the genus Pterophyllum was placed as the sister group of all remaining heroines plus cichlasomatines. However, the recovered relative position of Pterophyllum was without strong statistical support. Within the remaining heroines, Hyspelecara and Hoplarchus are recovered with low support in a basal position with respect to a clade that includes Heros, Uaru, Mesonauta, and Symphysodon, and the circumamazonian (CAM) heroines. The first clade is restricted to South America. The largest clade of heroines, the CAM heroines, include more than 85% of the species within the tribe. This clade is mostly Mesoamerican, but also contains four species found in the Greater Antilles (Nandopsis), and three genera found in South America (the 'Heros' festae group, Australoheros, and Caquetaia). Up to eight major lineages can be recovered within the CAM heroines, but the phylogenetic relationships among them remain unresolved. Two large suprageneric groups can be distinguished, the amphilophines and the herichthyines. The amphilophines include Amphilophus, Archocentrus, Hypsophrys, Neetroplus, Parachromis, Petenia, and five additional unnamed genera (the 'Heros' istlanus group, the 'Amphilophus' calobrensis group, the 'Heros' urophthalmus group, the 'Heros' wesseli group, and the 'Heros' sieboldii group). The herichthyines include the crown-group herichthyines (Herichthys, Theraps, Vieja, and Paratheraps) and the genera Tomocichla, Herotilapia, and Thorichthys, together with three unnamed genera (the 'Heros' umbriferus group, the 'Heros' grammodes group, and the 'Heros' salvini group). Amphilophines are prevalent in southern Mesomerica south of the Motagua fault. Herichthyines have basal linages in Central America, whereas crown-group herichthyines and three related genera are found north from the Motagua fault. At least two independent origins are required to explain current Mesoamerican heroine distribution. Dispersal of heroines from South America into Mesoamerica was dated between 24 and 16 million years ago (MYA) based on geological calibrations and on standard fish mitochondrial cytochrome b rates, respectively. These datings cannot be reconciled with currently known geological evidence, and the existence of a connection between Central America and South America in the Miocene needs to be postulated in order to explain the origins of Mesoamerican heroine lineages. However, our datings agree with those estimated for the dispersal of other secondary freshwater fishes (Rivulidae, Synbranchus) into Mesoamerica, and predate the invasion of primary freshwater fishes by at least 10 myr.

Animals↗
PubMed2001

Extended HLA haplotypes in a Carib Amerindian population: the Yucpa of the Perija Range.

Eleven MHC loci haplotypes have been defined among a Carib speaking Amerindian population; the Yucpa, inhabiting the northern section of the Perija Range, on the limits between Colombia and Venezuela. This tribe has been known with the name of "Motilones mansos" and is located close to the Chibcha-Paeze speaking Bari or "Motilones bravos." Seventy-three full blooded Yucpa living at the villages of Aroy, Marewa, and Peraya, were selected using a genealogy previously collected by an anthropologist and tested for Bf-C4AB complement allotypes and by serology, high resolution PCR-SSO and SBT typing for HLA class 1 and class 2 alleles. Combinations of 6 HLA-A, 6 HLA-B, 5 HLA-C, 1 Bf, 3 C4AB, 3 DQA1, 3DQB1 and 2 DPA1 and 2 DPB1 alleles present in this population originate 17 different haplotypes, 3 of which represent 63% of the haplotypic constitution of the tribe. The presence of 13 individuals homozygous for 11-loci haplotypes corroborates the existence of the following allelic combinations: DRB1*0411 DQA1*03011 DQB1*0302 DPA1*01 DPB1*0402 with HLA-A*6801 C*0702 B*3909 BfS C4 32 (f = 0.3372) or with A*0204 C*0702 B*3905 (f = 0.1977) and a third haplotype which differs only in DRB1*0403 and A*2402 (f = 0.0930). The results demonstrate the isolation of the tribe and the existence of high frequencies of a reduced number of "Amerindian" ancestral and novel class 1 and class 2 alleles (B*1522, DRB1*0807) with significant linkage disequilibria. These results will be useful to test the hypothesis that differentiation of Amerindian tribal groups will have to rely on haplotypes and micropolymorphism rather than allelic lineage frequencies due to the uniformity shown thus far by the putative descendants of the original Paleo-Indians.

Colombia↗
PubMed2000

Fertility, mortality and gender bias among tribal population: an Indian perspective.

The present paper critically reviews the existing literature on fertility, mortality and its gender bias among India's tribal population in the post-Independence period. Despite difficulties and limitations of available literature on tribal demography--most of which has been produced by anthropologists--our review extracts several interesting and important points. First, although fertility and mortality levels for some tribes and for some regions are either lower or higher or even the same as those for nontribal groups, India's aggregate tribal population evinces both lower fertility and mortality than the levels for their closest comparable nontribal group, namely low caste people. Several sociocultural and lifestyle features of tribals are historically favourable to maintaining a relatively low fertility and mortality. Despite baseline aggregative patterns of demographic differential being favourable to tribes, there is rather strong indication that of late and in the near future Indian tribals might be lagging behind the nontribal population in demographic transition (e.g. in terms of slower pace of tribal fertility and mortality declines). Also, while gender relations among Indian tribes have historically been more balanced and egalitarian, an unfortunate trend of tribal gender bias conforming to the mainstream anti-female pattern (along with acculturation, assimilation and similar 'modernizing' processes) is increasingly discernable under current circumstances.

Cultural Characteristics↗
PubMed2000

Evolutionary strategies of human T-cell lymphotropic virus type II.

Human T-cell lymphotropic virus type II (HTLV-II) primarily infects two different populations in which the virus is transmitted in very diverse ways. In endemically infected populations, the virus is propagated through sexual contact, and by mother to child transmission via breast-feeding, among intravenous drug users (IDUs), spread is mainly due to blood-borne transmission via needle sharing. The phylogeny of HTLV-II strains isolated from American Indian and Pygmy tribes and strains from IDUs, reveal that the virus originated on the African continent as a result of a simian to human transmission at least 400,000 years ago. HTLV-II was very likely introduced into the American continent during one or more migrations of HTLV-II infected Asian populations over the Bering land bridge, some 15,000-35,000 years ago. During the last few decades, HTLV-II has been transmitted from native American Indians to IDUs at least twice, followed by a rapid spread of the virus in the drug users population world-wide due to the practice of needle sharing. Molecular clock analysis showed that HTLV-II has two different evolutionary rates, with the molecular clock for the virus in IDUs ticking 150-350 times faster than the one in endemically infected tribes: 2.7x10(-4) compared to 1.7/7.3x10(-7) nucleotide substitutions per site per year in the LTR region. Although many of the HTLV-II infected drug users are co-infected with HIV, the dramatic acceleration of the evolutionary rate seems to be mainly related to the different modes of transmission in the two populations. These contrasting evolutionary rates correlate with an endemic spread of HTLV-II in infected tribes compared to an epidemic spread in IDUs.

Animals↗
PubMed1999

Prevalence of herpes simplex virus types 1 and 2, cytomegalovirus, and varicella-zoster virus infections in Eritrea.

BACKGROUND: Herpesviruses establish latent infections in their hosts for life. The scarcity of data that exists in regard to herpesvirus infections in many African regions, could partly be due to the mild nature of their primary infections and the lack of means for their proper diagnosis. However, in recent decades the alarming spread of HIV infection in Africa and associated frequent reactivation of herpesvirus infections is leaving less room for neglect. This seroprevalence study is intended to help in the evaluation of the prevalence of herpesvirus infections in Eritrea. OBJECTIVE: To evaluate the spread of herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), cytomegalovirus (CMV), and varicella-zoster virus (VZV) infections. STUDY DESIGN: The study population groups comprise female sex workers (FSW), former guerrilla fighters, truck drivers, port workers, a tribe called Rashaida, pregnant women, children under 5 years of age, and children over 5 years of age. The groups of pregnant women and children under and over 5 years of age were included to form a background for the evaluation of groups considered at risk for sexually transmitted or blood borne infections. RESULTS: All study groups had a high seroprevalence of HSV-1 infections ( > 80%), except for the children under 5 years of age. The FSW had the highest prevalence of HSV-2 infections, 80%, followed by guerrilla fighters, truck drivers, port workers, pregnant women, children, and the Rashaidas. Positivity for antibodies against CMV was > 90% in all studied populations. The prevalence of VZV infections was surprisingly low in the tribe of Rashaida, 44% compared to more than 90% in the other adult groups tested for VZV (P = 0.0001). CONCLUSION: The study shows that the prevalence of HSV-2 in the risk group of FSW was high, which could partly be explained by their sexual behaviours. HSV-2 was particularly low in the Rashaida group and, as expected, in the children. The low prevalence of VZV observed in the Rashaida is of importance since it makes them vulnerable to infection with varicella during their inevitable integration with the other tribes in their society.

Adult↗
PubMed2001

A comparative study of the proventricular structure in corbiculate apinae (Hymenoptera, Apidae).

The present study compares the proventricular structure, analyzed under scanning electronic microscope (SEM), among tribes of corbiculate Apinae. Fifty-one species of stingless bees (Meliponini), one species of honeybee (Apini), three species of bumblebees (Bombini) and seven species of orchid bees (Euglossini), were analyzed as in-group, and one species of sphecid wasp (Sphecidae) and two species of Halictidae bees, as out-groups. The proventricular bulb presents a basic morphology pattern similar to that of other Hymenoptera such as ants and wasps, being a symplesiomorphy for bees. The shape of proventricular folds constitutes a synapomorphy for Meliponini and an autapomorphy for Apini. The shape of hair-like projections of the cuticle that lines the proventriculus is a synapomorphy for Meliponini and Apini. These proventricular data corroborate the monophyly of the tribe Meliponini and the hypothesis that recognizes only one tribe for stingless bees. In addition, Meliponini+Apini constitutes a monophyletic group and Bombini+Euglossini another monophyletic group. The results confirm that internal morphology is a character that can be used in studies of the phylogeny in insects and the use of SEM as a powerful tool in these analyses.

Animals↗
PubMed2002

Phylogenetic relationships of the carabid subfamily Harpalinae (Coleoptera) based on molecular sequence data.

The carabid subfamily Harpalinae contains most of the species of carabid beetles. This subfamily, with over 19,000 species, radiated in the Cretaceous to yield a large clade that is diverse in morphological form and ecological habit. While there are several morphological, cytological, and chemical characters that unite most harpalines, the placement of some tribes within the subfamily remains controversial, as does the sister group relationships to this large group. In this study, DNA sequences from the 28S rDNA gene and the wingless nuclear protein-coding gene were collected from 52 carabid genera representing 31 harpaline tribes in addition to more than 21 carabid outgroup taxa to reconstruct the phylogeny of this group. Molecular sequence data from these genes, along with additional data from the 18S rDNA gene, were analyzed with a variety of phylogenetic analysis methods, separately for each gene and in a combined data approach. Results indicated that the subfamily Harpalinae is monophyletic with the enigmatic tribes of Morionini, Peleciini, and Pseudomorphini included within it. Brachinine bombardier beetles are closely related to Harpalinae as they form the sister group to harpalines or, in some analyses, are included within it or with austral psydrines. The austral psydrines are the sister group to Harpalinae+Brachinini clade in most analyses and austral psydrines+Brachinini+Harpalinae clade is strongly supported.

Animals↗
PubMed2003

Can the current molecular arsenal adequately track rapid divergence events within Simuliidae (Diptera)?

Ancient rapid divergence events, such as those that took place during the Mesozoic, are pervasive in evolution and represent a major challenge to phylogenetic biologists. The number of molecular phylogenetic studies in which rapid divergence has been invoked to account for poor phylogenetic resolution has steadily increased over the past few years. In this study, rapid divergence events are again hypothesized to have taken place, this time within the two major tribes of Simuliidae, Prosimuliini and Simuliini. This inference is based upon the failure of portions of 28S rDNA, EF-1alpha, DDC, PEPCK, and 12S rDNA to adequately reconstruct relationships among their constituent genera and the presence of short internal and long terminal nodes within both tribes for all character partitions of these genes. Sequence divergence, other than synonymous variation within coding genes, was low among genera and node support weak, except largely for those joining morphologically similar taxa previously recognized as closely related. Strong attraction between a long terminal node (Austrosimulium Tonnoir) and a long internal node (Simuliini), is hypothesized to be the reason for strong support for the placement of Austrosimulium as the basal-most lineage in this tribe. In spite of these problems, a preferred tree intended to be a reasonable estimate of simuliid phylogeny is tentatively presented. Based upon the considerable genomic sampling conducted in this and previous studies, it is clear that new types of genes are needed to more adequately resolve rapid divergence phenomena. The CAD and GART loci, currently under development as phylogenetic markers by the author, show greater promise for resolving simuliid relationships than do any of the genes examined herein.

Animals↗
PubMed2004

Phylogenetic analysis of the mitochondrial genes LSU rRNA and COI suggests early adaptive differentiation of anal teeth in chrysidine cuckoo wasps (Hymenoptera: Chrysididae).

Cuckoo wasps are a morphologically diverse group of Hymenoptera with parasitoid or cleptoparasitic life histories. In the present paper, we explore the phylogenetic signal in fragments of the mitochondrial genes LSU rRNA and COI to resolve the group's phylogeny. We analyzed sequence data of 33 species representing the taxa Cleptinae, Elampini, Parnopini, and Chrysidini. Most of the currently recognized relationships of major cuckoo wasp lineages are supported by the molecular data. A key difference concerns the phylogenetic position of the Euchroeus (=Brugmoia) group within the tribe Chrysidini. It seems likely that an erroneous interpretation of morphological characters has led to inappropriate rooting of that tribe. We suggest that species of the Euchroeus group be interpreted as forming the stem group of the Chrysidini and that the remaining genera of that tribe be united in a subordinated taxon. Our results imply that the evolution of anal dentition, of significance for breaking into sealed host nests otherwise not accessible to cuckoo wasps, already happened at the base of the Chrysidini and that an even number of anal teeth arose prior to an odd number.

Anal Canal↗
PubMed2002

Prevalence of hepatitis B and C virus infection in rural ethnic populations of Northern Thailand.

BACKGROUND: In Thailand, the population is composed of multiethnic stocks. However, many epidemiological studies on HBV and HCV have focused on blood donors with Thai and/or Chinese ethnic background. Available information on HBV and HCV infections among ethnic minorities in Thailand is limited. OBJECTIVE: So as to contribute to the local public health planning, we have conducted an ethno-epidemiological survey for the HBV and HCV infections among several minorities in a multiethnic center, Northern Thailand. STUDY DESIGN: A total of 658 individuals from seven ethnic groups, Lahu, Lisu, Shan, Red Karen, White Karen, Hmong and Akha, living in northern Thailand were studied for the prevalence of HBV and HCV infections by the use of particle agglutination tests. RESULTS: An overall prevalence of HBs-Ag, anti-HBs and anti-HCV in the seven groups was 10.3, 33.0 and 3.8%, respectively. The positivity rate of HBV and HCV infection in each tribe ranged 4.7% (Akha)-22.6% (Lahu) and 2.0% (Hmong and Akha)-8.1% (Shan), respectively. Sexual difference in the prevalence of HBV was not observed, whereas the prevalence of HCV was significantly higher in the males (P<0.05). The prevalence of HBV was significantly different (P<0.005) by the groups but that of HCV was not. CONCLUSIONS: The prevalence of HBV and HCV infection in Thai ethnic minorities was investigated. We demonstrated that HBV was a more common infectious agent found in this populations than HCV. The prevalence of HBV infection was different by tribe but not by sex. In contrast, the prevalence of HCV infection was not different by tribe but by sex (males were infected more than females). The present study showed that HBV and HCV infection are widely spread in rural ethnic populations of northern Thailand. Thus, a nation wide but community-base epidemiological survey is required for the public health planning to control their related serious diseases.

Adolescent↗
PubMed2001

Risk factors for and relationship between bacterial vaginosis and cervicitis in a high risk population for cervicitis in Southern Iran.

In 1990, a study of the reproductive habits and cervical pathology in women of the Qashgha'i nomadic tribe, resulted in a high prevalence of cervicitis. This led us to explore the likely infectious agents responsible for a such high prevalence; to assess the difference in cervicitis rates between nomadic and non-nomadic populations in the same area; and to determine the risk factors for and the relationship between cervicitis and bacterial vaginosis (BV). In 1996-1997 a study was carried out of 839 married women of the Qashgha'i, 274 of the Lor nomadic tribes, and 388 non-nomadic urban women. A gynaecological examination, Pap smear and vaginal secretion for assessing BV by gram staining were performed. Data was analysed by logistic regression. Backward stepwise regression was used to assess multivariable effects on risk of cervicitis. The prevalence of cervicitis was 88% in the Qashgha'i, 85% in the Lor and 71% in the urban population. In the multivariate backward stepwise regression analysis for predictors of cervicitis in the Qashgha'i, significant factors were decreased association with those over 40 (p < 0.004) and postpartum bleeding. In the Lor tribe the predictors were an increased risk after more than four pregnancies (p < 0.01) and the use of contraception. Among the urban population, the risk of cervicitis was increased with the use of oral contraceptive previously (p < 0.03) or currently (p < 0.01). BV was strongly associated with cervicitis, with a relatively high attributable risk. Both sexual and childbirth exposures may be associated with cervicitis in these populations.

Adult↗
PubMed1999

Subtribe-specific monoclonal antibodies to Lolium perenne.

BACKGROUND AND OBJECTIVES: The ability to measure personal exposure to airborne grass pollen is important in the understanding of allergic diseases. Visual identification is time consuming and it is difficult to distinguish between many grass pollens morphologically. Although grass pollens share common allergenic determinants, we attempted to produce monoclonal antibodies that would distinguish between species, tribes and subfamilies of grasses which would allow immunodetection of pollens. METHODS: Monoclonal antibodies raised against Lolium perenne were screened for specificity against an extended panel of grass pollen extracts using standard ELISA techniques and a novel particle blotting assay using whole pollen grains. RESULTS: Antibodies showing specificity ranging from subfamily to part-tribe specificity were raised. The most specific monoclonal antibodies (numbers 4, 13 and 17) had reactivity to Lolium perenne and Festuca elatior but displayed little cross-reactivity to Phalaris arundinaceae and the rest of the Poeae tribe when tested by ELISA and no detectable cross-reaction when tested with particle blotting. CONCLUSION: Monoclonal antibodies that are functionally specific to only two grasses can be produced and used to discriminate between related grass species.

Allergens↗
PubMed2003

The spectrum of kidney disease in American Indians.

American Indians and Alaska Natives (AI/AN) experience high rates of chronic kidney disease. Several studies have demonstrated increased rates of early kidney disease among AI/AN, both in diabetics and non-diabetics. Among some tribes of the American Southwest, high rates of mesangiopathic glomerulonephritis have been documented. The epidemic of diabetes among AI/AN, which began in the middle of the 20th century, appears to be driving the increase in end-stage renal disease (ESRD). At the end of 1999, AI/AN had a national prevalence rate of treated ESRD that was 3.5 times greater than that of white Americans. There is significant regional variation as well as differences among the approximately 550 tribes that make up the American Indian community, with some tribes experiencing ESRD rates over twenty times the rate of whites. Although graft survival is excellent, AI/AN ESRD patients are less likely than whites to be placed on the transplant waiting list, and those listed wait longer for a transplant. Despite socioeconomic barriers and high rates of co-morbid illness, survival among AI/AN ESRD patients is better than among whites. The burden of kidney disease, particularly the multigenerational occurrence in some families, is perceived as a major threat to the well-being of native communities. There is a sense of urgency among tribal leaders to address this epidemic, and research that may decrease its burden is likely to be welcomed.

Humans↗
PubMed2002

Epidemiology of the American Indians' burden and its likely genetic origins.

It was not known until recently whether the endemic of cholesterol gallstones among certain southwestern American Indian tribes was unique among this ethnic group. With use of ultrasonography of the gallbladder and standard diagnostic criteria, gallstones are now found in epidemic proportions in 13 diverse American Indian tribes and communities living in Arizona, Oklahoma, and the Dakotas. We speculate that this predisposition is polygenic involving "thrifty" genes that conferred survival advantages when Paleo-Indians migrated from present-day Siberia to the Americas during the last Great Ice Age approximately 50,000 to 10,000 years ago. A reasonable hypothesis is that functioning of these genes promoted more efficient calorie utilization and storage in the form of adipose tissue. Beneficial results would have been operative during the isolation of Paleo-Indians in the Bering Strait land bridge (Beringia) when thrifty genes would have ensured sufficient fat reserves for survival of prolonged winters, successful pregnancy outcomes, and extended lactation periods. The authors' conjoint work on genetics of experimental cholesterol cholelithiasis in inbred mice promises help in pinpointing orthologous genetic loci (LITH genes) in the human genome. Moreover, the shared environments and homogeneity of American Indian tribes and communities should facilitate discovery of the ensembles of their common and rarer cholesterol gallstone genes. It is anticipated that knowledge of expression, polymorphisms, and functionality of LITH genes will help resolve the molecular mechanisms of this complex heterogeneous trait and thereby provide targets for novel therapies to prevent cholesterol cholelithiasis worldwide.

Cholelithiasis↗
PubMed1989

Description and validation of a method for simultaneous estimation of effective population size and mutation rate from human population data.

A method is presented for utilizing population data on electrophoretic variants of proteins to estimate simultaneously the effective sizes (Ne values) of the populations in question and the rate of mutation resulting in electromorphs at the loci whose products were surveyed. The method is applied to data from 12 relatively unacculturated Amerindian tribes for whom census data and independent estimates of the number of different electrophoretic variants at 27 loci are available. Because of tribal demographic structure, Ne should be less than the current number of reproductive-aged adults. In fact, it is substantially greater for 7 tribes, most likely due to intertribal migration and a recent decrease in tribal size. Estimates of locus mutation rates for the 27 loci vary by more than a factor of 20, with an average of 1.1 x 10(-5) per locus per generation. This latter estimate is in satisfactory agreement with the results of other indirect approaches to the estimation of mutation rates in these tribes but about two times higher than the results of direct estimates based on these same loci in studies on civilized populations. This discrepancy could be due to the above-hypothesized migration and to decreases in tribal size.

Adult↗