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PubMed2001

Primate origins: evolutionary change in digital ray patterning and segmentation.

This study presents evidence that the first primates share with extant lemurs, tarsiers, and anthropoids hand proportions unlike those of their close relatives, the tree shrews (Scandentia), colugos (Dermoptera), and plesiadapiforms. Specifically, early primates as well as modern strepsirhines and haplorhines have relatively short metacarpals and long proximal phalanges giving them a grasping, prehensile hand. Limb development was studied in the primate Microcebus murinus and a comparative sample of rodents, artiodactyls, and marsupials to investigate the role of embryonic patterning in the morphogenesis and evolution of primate hand proportions. Comparative analysis shows that the derived finger proportions of primates are generated during the early phases of digital ray patterning and segmentation, when the interzone cells marking the presumptive metacarpo- and interphalangeal joints first appear. Interspecific variation in relative digit and metapodial proportions therefore has high developmental penetrance; that is, adult differences are observed at early ontogenetic stages. The paleontological, comparative, and developmental data are therefore consistent with the hypothesis that the early Cenozoic origin of primates involved an evolutionary change in digital ray pattern formation ultimately yielding a grasping, prehensile hand.

Animals↗
PubMed2002

Leopard predation and primate evolution.

Although predation is an important driving force of natural selection its effects on primate evolution are still not well understood, mainly because little is known about the hunting behaviour of the primates' various predators. Here, we present data on the hunting behaviour of the leopard (Panthera pardus), a major primate predator in the Tai; forest of Ivory Coast and elsewhere. Radio-tracking data showed that forest leopards primarily hunt for monkeys on the ground during the day. Faecal analyses confirmed that primates accounted for a large proportion of the leopards' diet and revealed in detail the predation pressure exerted on the eight different monkey and one chimpanzee species. We related the species-specific predation rates to various morphological, behavioural and demographic traits that are usually considered adaptations to predation (body size, group size, group composition, reproductive behaviour, and use of forest strata). Leopard predation was most reliably associated with density, suggesting that leopards hunt primates according to abundance. Contrary to predictions, leopard predation rates were not negatively, but positively, related to body size, group size and the number of males per group, suggesting that predation by leopards did not drive the evolution of these traits in the predicted way. We discuss these findings in light of some recent experimental data and suggest that the principal effect of leopard predation has been on primates' cognitive evolution.

Adaptation, Physiological↗
PubMed1996

Primate phylogeny: morphological vs. molecular results.

Our comparative study of morphological (our data on selected living primates) and molecular characters (from the literature) confirms that, overall, phylogenetic reconstructions of Primates, and consequently their classifications, are more similar than dissimilar. When data from fossil Primates are incorporated, there may be several possible relationships among living Primates; the difference between most of them hinges mainly on the position of Tarsius. In one hypothesis, tarsiers are closely related to lemurs and lorises, and thus Primates is divided into Prosimii [lorises, lemurs, and tarsiers] and Anthropoidea [Platyrrhini and Catarrhini, i.e., monkeys, apes, and humans]. Two additional alternatives are that Tarsius is a sister group to the clade embracing lorises + lemurs and Anthropoidea and that in which all three lineages (Tarsius, lorises + lemurs, and Anthropoidea) form a polychotomy. In another hypothesis, tarsiers are closely related to anthropoids, giving these two branches: Strepsirhini [lemurs, lorises] and Haplorhini [tarsiers and Anthropoidea (Platyrrhini, the New World monkeys, and Catarrhini, Old World monkeys and Hominoidea)]. The first three alternatives gain some support from the fossil record, and the fourth from morphology of the living Tarsius and molecular data. It is emphasized that the morphological characters employed in this study for Tarsius are based on the only surviving genus of once-diverse tarsiiform primates known from the Eocene, and, although considered a "living fossil," it cannot represent all of them. Furthermore, Tarsius embodies derived features of its own which may affect its systematic position, but not necessarily the position of Tarsiiformes. Although the early Tertiary adapoids might have more nearly resembled anthropoids in their biochemistry and placental developments, this hypothesis is not testable from fossils, and any inferred relationships here must be based on characters of skeletal anatomy. Alternatively, anthropoids may be derived from certain omomyids or from some as yet undiscovered Eocene African taxon. Close relationships among Homo, Pan, and Gorilla have been confirmed during recent decades; Pongo is the sister group to this trichotomy. With increasing molecular data, Homo and Pan appear to be closer to each other than to any other living hominid taxon. Gorilla is a sister group to the Homo-Pan clade and Pongo is a sister group to all of them. Morphologists have given limited evidence for such a dichotomous grouping. In this study, we support the Homo-Pan clade, although with characters not as strong as for other clades.

Animals↗
PubMed1999

Defining the ancestral karyotype of all primates by multidirectional chromosome painting between tree shrews, lemurs and humans.

We used multidirectional chromosome painting with probes derived by bivariate fluorescence-activated flow sorting of chromosomes from human, black lemur (Eulemur macaco macaco) and tree shrew (Tupaia belangeri, order Scandentia) to better define the karyological relationship of tree shrews and primates. An assumed close relationship between tree shrews and primates also assists in the reconstruction of the ancestral primate karyotype taking the tree shrew as an "outgroup" species. The results indicate that T. belangeri has a highly derived karyotype. Tandem fusions or fissions of chromosomal segments seem to be the predominant mechanism in the evolution of this tree shrew karyotype. The 22 human autosomal painting probes delineated 40 different segments, which is in the range found in most mammals analyzed by chromosome painting up to now. There were no reciprocal translocations that would distinguish the karyotype of the tree shrew from an assumed primitive primate karyotype. This karyotype would have included the chromosomal forms 1a, 1b, 2a, 2b, 3/21, 4-11, 12a/22a, 12b/22b, 13, 14/15, 16a, 16b, 17, 18, 19a, 19b, 20 and X and Y and had a diploid chromosome number of 2n=50. Of these forms, chromosomes 1a, 1b, 4, 8, 12a/22a, and 12b/22b may be common derived characters that would link the tree shrew with primates. To define the exact phylogenetic relationships of the tree shrews and the genomic rearrangements that gave rise to the primates and eventually to humans further chromosome painting in Rodentia, Lagomorpha, Dermoptera and Chiroptera is needed, but many of the landmarks of genomic evolution are now known.

Animals↗
PubMed1984

Plasma testosterone transport in primates.

All primate species, including Old and New World primates and prosimians have a plasma testosterone-estradiol binding globulin (TeBG), which is a glycoprotein and has a similar mobility in polyacrylamide gel electrophoresis. In New World primates the TeBG binding capacity for [3H]testosterone was higher and its affinity lower than in Old World primates. These changes were associated with high unbound plasma testosterone concentrations in these species. Binding parameters of TeBG in prosimian species varied markedly. Thus, in primate evolution TeBG was conserved despite marked differences in binding characteristics. In New World primates changes are associated with high total and unbound testosterone, a finding concordant with alterations of other steroid hormones concentration in these species with "generalized steroid hormone resistance".

Animals↗
PubMed1994

The molecular genetics and evolution of primate colour vision.

Until recently, the genetic basis of colour vision could only be inferred from measuring the colour vision of family groups. However, in the past few years the sites of the genes for visual pigments have been located and sequenced. The genes that specify the opsins for the rod and short-wavelength cone pigments are located on the third and seventh chromosomes, respectively. In Old World primates the genes for the middle- and long-wavelength pigments are located on the q arm of the X chromosome in a head-to-tail array. The close sequence similarity of the two genes on the X chromosome leads to a high frequency of unequal inter- and intragenic recombination leading to gene deletion or the creation of hybrid genes. In New World primates there is only a single locus on the X chromosome for a middle- to long-wavelength cone pigment. However, three alleles can occur at this locus and each codes for a slightly different cone pigment. As a result there are three types of male dichromat and three types of female dichromat and trichromat in each species. Colour vision in New World primates might be an intermediate stage between the uniform dichromacy of non-primate mammals and the uniform trichromacy of Old World primates. Alternatively, colour vision in New World primates might be an adaptation to allow a wide variety of colour-vision types within a single family group.

Alleles↗
PubMed1998

Some gastro-intestinal parasites of zoonotic (public health) importance commonly observed in old world non-human primates in Kenya.

A study was undertaken to categorise some gastro-intestinal (GIT) parasites commonly observed in Kenyan non-human primates (NHPs) on the basis of their health implications for humans. Six species of locally available non-human primates, namely olive baboons (Papio cyanocephalus anubis), Vervet monkey (Cercopithecus aethiops), Sykes monkey (Cercopithecus mitis), Black and white colobus (Colobus abyssinicus), Debrazzas monkey (Cercopithecus neglectus) and Grey and Black mangabeys (Cercocebus torquatus and Cercocebus albigena) which were imported from Zaire (Democratic Republic of Congo) were sampled. Simple laboratory methods involving microscopic examination of stained faecal smears were used. Wet faecal smears stained with iodine and unstained controls were used for conventional parasites while acid fast staining was employed to detect Cryptosporidium oocysts. Both helminths and protozoan parasites were detected in varying rates in all primate species. Trichuris sp. was the most frequent helminth followed by Strongyloides fulleborni, Strongyles sp. and Schistosoma mansoni in that order. Entamoeba coli was the most common protozoan followed, respectively, by Balantidiun coli and Entamoeba histolytica. All primate species examined were infected with all the parasites listed except the black and white colobus. Cryptosporidium was found in both clinically normal and diarrhoeic baboons and vervets. Most taxa of parasites observed could prejudice human welfare directly through infection and causation of illness and indirectly through increased cost of livestock production and decreased availability of animal proteins. The potential of some of the agents to cause opportunistic infections in immuno-compromised persons was suggested as a likely threat to man's well-being. This would warrant such person's exemption from high risk operations at primate and other animal facilities in developing countries. Further, specific studies are needed to provide data on the epidemiology, socio-economic impact and pathogenicity of the primate parasites to other species of animals and man.

Animals↗
PubMed2003

The energetic cost of locomotion: humans and primates compared to generalized endotherms.

A wide range of selective pressures have been advanced as possible causes for the adoption of bipedalism in the hominin lineage. One suggestion has been that because modern human walking is relatively efficient compared to that of a typical quadruped, the ancestral quadruped may have reaped an energetic advantage when it walked on two legs. While it has become clear that human walking is relatively efficient and human running inefficient compared to "generalized endotherms", workers differ in their opinion of how the cost of human bipedal locomotion compares to that of a generalized primate walking quadrupedally. One view is that human walking is particularly efficient in comparison to other primates. The present study addresses this by comparing the cost of human walking and running to that of the eight primate species for which data are available and by comparing cost in primates to that of a "generalized endotherm". There is no evidence that primate locomotion is more costly than that of a generalized endotherm, although more data on adult Old World monkeys and apes would be useful. Further, human locomotion does not appear to be particularly efficient relative to that of other primates.

Animals↗
PubMed2002

Nonhuman primate transgenesis: progress and prospects.

The nonhuman primate is used extensively in biomedical research owing to its close similarities to human physiology and human disease pathophysiology. Recently, several groups have initiated efforts to genetically manipulate nonhuman primates to address complex questions concerning primate-specific development and physiological adaptation. Primates pose unique challenges to transgenesis and, although this field is still in its infancy, the potential for obtaining new insights into primate physiology and gene function is unprecedented. This review focuses on the methods and potential applications of genetically altered nonhuman primates in biomedical research.

Adaptation, Physiological↗
PubMed2000

Progressive inactivation of the haploid expressed gene for the sperm-specific endozepine-like peptide (ELP) through primate evolution.

The endozepine-like peptide (ELP) is a novel intracellular molecule which is expressed in high amounts at both mRNA and protein levels very specifically in late haploid male germ cells. It is closely related to the ubiquitous acyl-CoA binding protein, is highly conserved, shares a similar ability to bind mid-long chain acyl-CoA, and is thus likely to be involved in mature sperm metabolism. While it has been characterized from diverse mammals, it has so far not been possible to identify an equivalent molecule in the primate testis. Using a PCR approach, combined with cDNA cloning and Northern hybridization, testicular transcripts and/or genomic DNA were analysed for different primate species, including human. In the marmoset and cynomolgus macaque normally structured transcripts appear to be expressed, though at a low level. In the human testis, two rare transcripts were characterized, hELP1 and hELP2, the products of independent duplicated genes. Both transcripts were longer than in non-mammalian species, included frame-shift mutations and substantial sequence insertions, preventing the translation of a sensible protein. Genomic PCR analysis of three anthropoid species, chimpanzee, gorilla and orangutan, showed the presence of a similarly mutated hELP1 gene. Only in the gorilla was a hELP2 gene identified, apparently lacking the frame-shift mutation, and thus potentially able to give rise to a functional ELP protein. Taken together, these results show that during primate evolution there has been a progressive inactivation of the ELP gene, initially with a down-regulation in lower primates, and subsequently with inactivating mutations in the open reading frame. At some time during simian evolution prior to these mutations there has been a gene duplication, though this second gene has also become inactivated in humans. In its pattern of evolution the ELP gene shows similarities with the MDC/fertilin family, whose members are also considered essential components of haploid sperm in non-primates, but which are progressively inactivated in anthropoids and humans. We should like to speculate that the established subfertility of the human male may not be a recent event, but the consequence of a longer evolutionary process whereby primates have traded off absolute fertility against social or sexual advantages.

Amino Acid Sequence↗
PubMed2001

Primate postcrania from the late middle Eocene of Myanmar.

Fossil primates have been known from the late middle to late Eocene Pondaung Formation of Myanmar since the description of Pondaungia cotteri in 1927. Three additional primate taxa, Amphipithecus mogaungensis, Bahinia pondaungensis and Myanmarpithecus yarshensis, were subsequently described. These primates are represented mostly by fragmentary dental and cranial remains. Here we describe the first primate postcrania from Myanmar, including a complete left humerus, a fragmentary right humerus, parts of left and right ulnae, and the distal half of a left calcaneum, all representing one individual. We assign this specimen to a large species of Pondaungia based on body size and the known geographic distribution and diversity of Myanmar primates. Body weight estimates of Pondaungia range from 4,000 to 9,000 g, based on humeral length, humeral midshaft diameter, and tooth area by using extant primate regressions. The humerus and ulna indicate that Pondaungia was capable of a wide variety of forelimb movements, with great mobility at the shoulder joint. Morphology of the distal calcaneus indicates that the hind feet were mobile at the transverse tarsal joint. Postcrania of Pondaungia present a mosaic of features, some shared in common with notharctine and adapine adapiforms, some shared with extant lorises and cebids, some shared with fossil anthropoids, and some unique. Overall, Pondaungia humeral and calcaneal morphology is most consistent with that of other known adapiforms. It does not support the inclusion of Pondaungia in Anthropoidea.

Animals↗
PubMed2000

Evolution of human and non-human primate CC chemokine receptor 5 gene and mRNA. Potential roles for haplotype and mRNA diversity, differential haplotype-specific transcriptional activity, and altered transcription factor binding to polymorphic nucleotides in the pathogenesis of HIV-1 and simian immunodeficiency virus.

Polymorphisms in CC chemokine receptor 5 (CCR5), the major coreceptor of human immunodeficiency virus 1 (HIV-1) and simian immunodeficiency virus (SIV), have a major influence on HIV-1 transmission and disease progression. The effects of these polymorphisms may, in part, account for the differential pathogenesis of HIV-1 (immunosuppression) and SIV (natural resistance) in humans and non-human primates, respectively. Thus, understanding the genetic basis underlying species-specific responses to HIV-1 and SIV could reveal new anti-HIV-1 therapeutic strategies for humans. To this end, we compared CCR5 structure/evolution and regulation among humans, apes, Old World Monkeys, and New World Monkeys. The evolution of the CCR5 cis-regulatory region versus the open reading frame as well as among different domains of the open reading frame differed from one another. CCR5 cis-regulatory region sequence variation in humans was substantially higher than anticipated. Based on this variation, CCR5 haplotypes could be organized into seven evolutionarily distinct human haplogroups (HH) that we designated HHA, -B, -C, -D, -E, -F, and -G. HHA haplotypes were defined as ancestral to all other haplotypes by comparison to the CCR5 haplotypes of non-human primates. Different human and non-human primate CCR5 haplotypes were associated with differential transcriptional regulation, and various polymorphisms resulted in modified DNA-nuclear protein interactions, including altered binding of members of the NF-kappaB family of transcription factors. We identified novel CCR5 untranslated mRNA sequences that were conserved in human and non-human primates. In some primates, mutations at exon-intron boundaries caused loss of expression of selected CCR5 mRNA isoforms or production of novel mRNA isoforms. Collectively, these findings suggest that the response to HIV-1 and SIV infection in primates may have been driven, in part, by evolution of the elements controlling CCR5 transcription and translation.

Animals↗
PubMed1999

The prevalence of antibodies to simian T-cell leukaemia/lymphotropic virus (STLV-I) in non-human primate colonies in Kenya.

Retroviruses closely related to the human T-cell leukaemia/lymphotrophic virus type I (HTLV-I) have been detected in several, non-human, primate species. These retroviruses are called simian T-lymphotrophic virus type I (STLV-I). Infection with STLV-I has been associated with lymphoma and leukaemia in macaques, baboons, African green monkeys and gorillas. However, no STLV-I infection has been detected in New World primates, although STLV-II has been detected in spider monkeys. When sera from 10 species of non-human primates maintained at the Institute of Primate Research were screened for STLV-I infection, anti-STLV-I antibodies were detected in 12%, 12%, 23% and 38% of the olive baboons, yellow baboons, African green monkeys and lowland Sykes' monkeys, respectively. Western-blot studies confirmed these results. To date, no clinical disease has been linked with STLV-I infection in these colonies. The relatively high prevalence of anti-STLV-I antibodies in these non-human primates offers an opportunity for studies on the transmission, phylogenetic relationships and natural history of STLV-I in primate colonies.

Animals↗
PubMed2001

Synthetic peptide strategy for the detection of and discrimination among highly divergent primate lentiviruses.

We developed a simple, rapid, inexpensive, and highly sensitive and specific strategy for the detection and lineage differentiation of primate lentiviruses (PIV-ELISA). It is based on the use of two indirect ELISA methods using synthetic peptides mapping the gp41/36 region (detection component) and the V3 region (differentiation component) of four lentivirus lineages, namely SIVcpz/HIV-1 (groups M, O, N, and SIVcpz-gab), SIVmnd, SIVagm, and SIVsm/SIVmac/HIV-2. This strategy was evaluated with panels of sera originating from both humans and nonhuman primates. The human reference panel consisted of 144 HIV Western blot (WB)-positive sera in which the corresponding virus had been genotyped (HIV-1: 72 group M, 28 group O, and 6 group N; HIV-2: 21 subtype A and 10 subtype B; and 7 HIV-1+2) and 105 HIV WB-negative samples. The nonhuman primate reference panel consisted of 24 sera from monkeys infected by viruses belonging to the four lineages included in the PIV-ELISA strategy (5 chimpanzees, 5 macaques, 8 mandrills, and 6 vervets) and 42 samples from seronegative animals. Additional field evaluation panels consisted of 815 human sera from Gabon, Cameroon, and France and 537 samples from 25 nonhuman primate species. All the samples from the two reference panels were correctly detected and discriminated by PIV-ELISA. In the human field evaluation panel, the gp41/36 component correctly identified all the test samples, with 98% specificity. The V3 component discriminated 206 HIV-1 group M, 98 group O, 12 group M+O, and 128 HIV-2 sera. In the primate field evaluation panel, both gp41/36 and V3 detected and discriminated all the WB-positive samples originating from monkeys infected with SIVcpz, SIVagm-ver, SIVmnd-1, SIVmnd-2, SIVdrl, or SIVsun. These results were confirmed by genotyping in every case. Four SIV-infected red-capped mangabeys (confirmed by PCR) were correctly identified by gp41/36, but only two reacted with the V3 peptides in the absence of a specific SIVrcm V3 peptide. Addition of a V3 SIVrcm peptide discriminated all the SIVrcm-positive samples. Fourteen Papio papio samples were positive for SIVsm gp 36 and by WB, but negative by PCR, whereas three Papio cynocephalus samples were positive by gp41/36 but indeterminate by WB and negative by PCR. This combined ELISA system is thus highly sensitive and specific for antibodies directed against HIV and SIV. In addition, the V3-based serotyping results always agreed with genotyping results. This method should prove useful for studies of lentivirus prevalence and diversity in human and nonhuman primates, and may also have the potential to detect previously undescribed SIVs.

Amino Acid Sequence↗
PubMed1995

The SRP9/14 subunit of the signal recognition particle (SRP) is present in more than 20-fold excess over SRP in primate cells and exists primarily free but also in complex with small cytoplasmic Alu RNAs.

The heterodimeric protein SRP9/14 bound to the Alu sequences of SRP RNA is essential for the translational control function of the signal recognition particle (SRP). The Alu RNAs of primate cells are believed to be derived from SRP RNA and have been shown to bind to an SRP14-related protein in vitro. We have used antibodies to characterize SRP9/14 and examine its association with small RNAs in vivo. Although SRP9 proteins are the same size in both rodent and primate cells, SRP14 subunits are generally larger in primate cells. An additional alanine-rich domain at the C-terminus accounts for the larger size of one human isoform. Although the other four SRP proteins are largely assembled into SRP in both rodent and primate cells, we found that the heterodimer SRP9/14 is present in 20-fold excess over SRP in primate cells. An increased synthesis rate of both proteins may contribute to their accumulation. The majority of the excess SRP9/14 is cytoplasmic and does not appear to be bound to any small RNAs; however, a significant fraction of a small cytoplasmic Alu RNA is complexed with SRP9/14 in a 8.5 S particle. Our findings that there is a large excess of SRP9/14 in primate cells and that Alu RNAs are bound to SRP9/14 in vivo suggest that this heterodimeric protein may play additional roles in the translational control of gene expression and/or Alu transcript metabolism.

Amino Acid Sequence↗
PubMed2001

Episodic evolution of growth hormone in primates and emergence of the species specificity of human growth hormone receptor.

Growth hormone (GH) evolution is very conservative among mammals, except for primates and ruminant artiodactyls. In fact, most known mammalian GH sequences differ from the inferred ancestral mammalian sequence by only a few amino acids. In contrast, the human GH sequence differs from the inferred ancestral sequence by 59 amino acids. However, it is not known when this rapid evolution of GH occurred during primate evolution or whether it was due to positive selection. Also, human growth hormone receptor (GHR) displays species specificity; i.e., it can interact only with human (or rhesus monkey) GH, not with nonprimate GHS: The species specificity of human GHR is largely due to the Leu-->Arg change at position 43, and it has been hypothesized that this change must have been preceded by the His-->Asp change at position 171 of GH. Is this hypothesis true? And when did these changes occur? To address the above issues, we sequenced GH and GHR genes in prosimians and simians. Our data supported the above hypothesis and revealed that the species specificity of human GHR actually emerged in the common ancestor of Old World primates, but the transitional phase still persists in New World monkeys. Our data showed that the rapid evolution of primate GH occurred during a relatively short period (in the common ancestor of higher primates) and that the rate of change was especially high at functionally important sites, suggesting positive selection. However, the nonsynonymous rate/synonymous rate ratio at these sites was <1, so relaxation of purifying selection might have played a role in the rapid evolution of the GH gene in simians, possibly as a result of multiple gene duplications. Similar to GH, GHR displayed an accelerated rate of evolution in primates. Our data revealed proportionally more amino acid replacements at the functionally important sites in both GH and GHR in simians but, surprisingly, showed few coincidental replacements of amino acids forming the same intermolecular contacts between the two proteins.

Amino Acids↗
PubMed2003

Organization of seminiferous epithelium in primates: relationship to spermatogenic efficiency, phylogeny, and mating system.

The succession in time and space of specific germ cell associations, denoted as spermatogenic stages, is a typical feature of mammalian spermatogenesis. The arrangement of these stages is either single stage (one spermatogenic stage per tubular cross-section) or multistage (more than one spermatogenic stage per tubular cross-section). It has been proposed that the single-stage versus multistage arrangement is related to spermatogenic efficiency and that the multistage arrangement is typical for hominids. In the present work, the arrangement of spermatogenic stages and the spermatogenic efficiency of 17 primate species, comprising Strepsirrhini (Prosimians: Lemuriformes, Lorisiformes), Platyrrhini (New World primates), Catarrhini (Old World primates), and Hominoidea (great apes and humans), were analyzed comparatively by quantitative histological and flow cytometric means. We found a predominant single-stage tubular organization in the Strepsirrhini, indicating that the single-stage form represents the ancestral state. The highest degree of multistage complexity was found in Hominoidea (except orangutan) and in Platyrrhini, but not in Catarrhini. Hence, no direct relationship between single-stage/multistage tubular topography and phylogeny could be established across primates. In fact, the tubule arrangement seen in Platyrrhini and Catarrhini primates is the reverse of what might be expected from phylogeny. Interestingly, spermatogenic efficiency was similar in all species. We found no correlation between single-stage/multistage arrangement and spermatogenic efficiency or mating system. We speculate that the presence of a single-stage/multistage organization might simply reflect germ cell clonal size. Our findings further indicate that sperm competition in primates is not reflected at the level of testicular function.

Animals↗
PubMed1999

Isolation and phylogeny of endogenous retrovirus sequences belonging to the HERV-W family in primates.

An investigation was undertaken of primate pol gene sequences from a novel endogenous retrovirus family, ERV-W, related to a new human endogenous retrovirus family (HERV-W) that includes multiple sclerosis-associated retrovirus (MSRV) sequences identified in particles recovered from monocyte cultures from patients with multiple sclerosis. The pol gene sequences of the ERV-W family were detected in hominoids and Old World monkeys, but not in New World monkeys, whereas ERV-W long terminal repeat-like elements were detected in all primates (hominoids, Old World monkeys and New World monkeys). Thirty-two pol gene sequences from hominoids and Old World monkeys showed a high degree of sequence identity to MSRV and other HERV-W sequences. Phylogenetic analysis indicated close relationships of pol gene sequences across primate species. The analysis suggests that the ERV-W family has evolved independently but in constrained patterns ('parallel evolution') in different primate species, including man. The ratio of synonymous to non-synonymous substitutions indicated that negative selective pressure is acting on CHW1-1 from chimpanzee, HBW6-6 from baboon and HWX5 from man, sequences that have no disruption by point mutation or insertions/deletions. Therefore, these pol gene sequences could be associated with an active provirus in primates. The findings indicate that the ERV-W family has continued to evolve in the course of the primate radiation and may include members with a capacity to influence gene function and possibly cause disease.

Amino Acid Sequence↗