Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 38
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
J Hered ; 115(2): 166-172, 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-37952226

RESUMO

The illegal poaching of lions for their body parts poses a severe threat to lion populations across Africa. Poaching accounts for 35% of all human-caused lion deaths, with 51% attributed to retaliatory killings following livestock predation. In nearly half of the retaliatory killings, lion body parts are removed, suggesting that high demand for lion body parts may fuel killings attributed to human-lion conflict. Trafficked items are often confiscated in transit or destination countries far from their country of origin. DNA from lion parts may in some cases be the only available means for examining their geographic origins. In this paper, we present the Lion Localizer, a full-stack software tool that houses a comprehensive database of lion mitochondrial DNA (mtDNA) sequences sourced from previously published studies. The database covers 146 localities from across the African continent and India, providing information on the potential provenance of seized lion body parts. Lion mtDNA sequences of 350 or 1,140 bp corresponding to the cytochrome b region can be generated from lion products and queried against the Lion Localizer database. Using the query sequence, the Lion Localizer generates a listing of exact or partial matches, which are displayed on an interactive map of Africa. This allows for the rapid identification of potential regions and localities where lions have been or are presently being targeted by poachers. By examining the potential provenance of lion samples, the Lion Localizer serves as a valuable resource in the fight against lion poaching. The software is available at https://lionlocalizer.org.


Assuntos
DNA Mitocondrial , Leões , Animais , Humanos , DNA Mitocondrial/genética , Leões/genética , África , Software
2.
Proc Natl Acad Sci U S A ; 115(34): 8609-8614, 2018 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-30082403

RESUMO

Endogenous retroviruses (ERVs) are proviral sequences that result from colonization of the host germ line by exogenous retroviruses. The majority of ERVs represent defective retroviral copies. However, for most ERVs, endogenization occurred millions of years ago, obscuring the stages by which ERVs become defective and the changes in both virus and host important to the process. The koala retrovirus, KoRV, only recently began invading the germ line of the koala (Phascolarctos cinereus), permitting analysis of retroviral endogenization on a prospective basis. Here, we report that recombination with host genomic elements disrupts retroviruses during the earliest stages of germ-line invasion. One type of recombinant, designated recKoRV1, was formed by recombination of KoRV with an older degraded retroelement. Many genomic copies of recKoRV1 were detected across koalas. The prevalence of recKoRV1 was higher in northern than in southern Australian koalas, as is the case for KoRV, with differences in recKoRV1 prevalence, but not KoRV prevalence, between inland and coastal New South Wales. At least 15 additional different recombination events between KoRV and the older endogenous retroelement generated distinct recKoRVs with different geographic distributions. All of the identified recombinant viruses appear to have arisen independently and have highly disrupted ORFs, which suggests that recombination with existing degraded endogenous retroelements may be a means by which replication-competent ERVs that enter the germ line are degraded.


Assuntos
Retrovirus Endógenos/genética , Phascolarctidae/genética , Recombinação Genética , Animais , Feminino , Masculino , New South Wales
3.
Gan To Kagaku Ryoho ; 48(7): 963-965, 2021 Jul.
Artigo em Japonês | MEDLINE | ID: mdl-34267037

RESUMO

The prognosis of patients with brain metastasis is very poor. Very few cases of combined treatment with nivolumab(240 mg/body, day 1, q2w, a programmed cell death-1[PD-1]inhibitor)and gamma knife radiosurgery(GKR)(27 Gy/3 Fr) for gastric cancer patients with brain metastasis have been reported. Here, we discuss the case of a 55-year-old man with HER2-positive poorly differentiated gastric adenocarcinoma with multiple bone and intra-abdominal lymph node metastases. After 25 courses of SOX(oxaliplatin 100 mg/m2, day 1, q3w plus S-1 120 mg/day, day 1-14, po, q3w)plus trastuzumab( 6 mg/kg, q3w)treatment, brain metastasis was detected. Subsequently, combined treatment with GKR and nivolumab(8 courses, anti-PD-1 monotherapy)was initiated. Both intra-abdominal and brain lesions decreased in response to this treatment, showing that combined therapy with nivolumab and GKR could be effective for treating gastric cancer patients with brain metastasis.


Assuntos
Adenocarcinoma , Neoplasias Encefálicas , Radiocirurgia , Neoplasias Gástricas , Adenocarcinoma/cirurgia , Protocolos de Quimioterapia Combinada Antineoplásica , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Nivolumabe/uso terapêutico , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/cirurgia
4.
J Hered ; 111(6): 564-572, 2020 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-32945850

RESUMO

Chronic wasting disease (CWD) is a fatal, highly transmissible spongiform encephalopathy caused by an infectious prion protein. CWD is spreading across North American cervids. Studies of the prion protein gene (PRNP) in white-tailed deer (WTD; Odocoileus virginianus) have identified non-synonymous substitutions associated with reduced CWD frequency. Because CWD is spreading rapidly geographically, it may impact cervids of conservation concern. Here, we examined the genetic vulnerability to CWD of 2 subspecies of WTD: the endangered Florida Key deer (O. v. clavium) and the threatened Columbian WTD (O. v. leucurus). In Key deer (n = 48), we identified 3 haplotypes formed by 5 polymorphisms, of which 2 were non-synonymous. The polymorphism c.574G>A, unique to Key deer (29 of 96 chromosomes), encodes a non-synonymous substitution from valine to isoleucine at codon 192. In 91 of 96 chromosomes, Key deer carried c.286G>A (G96S), previously associated with substantially reduced susceptibility to CWD. Key deer may be less genetically susceptible to CWD than many mainland WTD populations. In Columbian WTD (n = 13), 2 haplotypes separated by one synonymous substitution (c.438C>T) were identified. All of the Columbian WTD carried alleles that in other mainland populations are associated with relatively high susceptibility to CWD. While larger sampling is needed, future management plans should consider that Columbian WTD are likely to be genetically more vulnerable to CWD than many other WTD populations. Finally, we suggest that genetic vulnerability to CWD be assessed by sequencing PRNP across other endangered cervids, both wild and in captive breeding facilities.


Assuntos
Cervos/genética , Polimorfismo Genético , Proteínas Priônicas/genética , Doença de Emaciação Crônica/genética , Alelos , Animais , Espécies em Perigo de Extinção , Florida , Predisposição Genética para Doença , Haplótipos
5.
J Hered ; 110(7): 761-768, 2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31674643

RESUMO

Illegal hunting is a major threat to the elephants of Africa, with more elephants killed by poachers than die from natural causes. DNA from tusks has been used to infer the source populations for confiscated ivory, relying on nuclear genetic markers. However, mitochondrial DNA (mtDNA) sequences can also provide information on the geographic origins of elephants due to female elephant philopatry. Here, we introduce the Loxodonta Localizer (LL; www.loxodontalocalizer.org), an interactive software tool that uses a database of mtDNA sequences compiled from previously published studies to provide information on the potential provenance of confiscated ivory. A 316 bp control region sequence, which can be readily generated from DNA extracted from ivory, is used as a query. The software generates a listing of haplotypes reported among 1917 African elephants in 24 range countries, sorted in order of similarity to the query sequence. The African locations from which haplotype sequences have been previously reported are shown on a map. We demonstrate examples of haplotypes reported from only a single locality or country, examine the utility of the program in identifying elephants from countries with varying degrees of sampling, and analyze batches of confiscated ivory. The LL allows for the source of confiscated ivory to be assessed within days, using widely available molecular methods that do not depend on a particular platform or laboratory. The program enables identification of potential regions or localities from which elephants are being poached, with capacity for rapid identification of populations newly or consistently targeted by poachers.


Assuntos
DNA Mitocondrial , Elefantes/genética , Software , Navegador , África , Animais , Animais Selvagens , Biologia Computacional/métodos , Conservação dos Recursos Naturais , Elefantes/classificação , Genética Forense , Marcadores Genéticos , Haplótipos , Dinâmica Populacional
6.
J Virol ; 90(18): 8169-80, 2016 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-27384662

RESUMO

UNLABELLED: Gibbon ape leukemia virus (GALV) and koala retrovirus (KoRV) most likely originated from a cross-species transmission of an ancestral retrovirus into koalas and gibbons via one or more intermediate as-yet-unknown hosts. A virus highly similar to GALV has been identified in an Australian native rodent (Melomys burtoni) after extensive screening of Australian wildlife. GALV-like viruses have also been discovered in several Southeast Asian species, although screening has not been extensive and viruses discovered to date are only distantly related to GALV. We therefore screened 26 Southeast Asian rodent species for KoRV- and GALV-like sequences, using hybridization capture and high-throughput sequencing, in the attempt to identify potential GALV and KoRV hosts. Only the individuals belonging to a newly discovered subspecies of Melomys burtoni from Indonesia were positive, yielding an endogenous provirus very closely related to a strain of GALV. The sequence of the critical receptor domain for GALV infection in the Indonesian M. burtoni subsp. was consistent with the susceptibility of the species to GALV infection. The second record of a GALV in M. burtoni provides further evidence that M. burtoni, and potentially other lineages within the widespread subfamily Murinae, may play a role in the spread of GALV-like viruses. The discovery of a GALV in the most western part of the Australo-Papuan distribution of M. burtoni, specifically in a transitional zone between Asia and Australia (Wallacea), may be relevant to the cross-species transmission to gibbons in Southeast Asia and broadens the known distribution of GALVs in wild rodents. IMPORTANCE: Gibbon ape leukemia virus (GALV) and the koala retrovirus (KoRV) are very closely related, yet their hosts neither are closely related nor overlap geographically. Direct cross-species infection between koalas and gibbons is unlikely. Therefore, GALV and KoRV may have arisen via a cross-species transfer from an intermediate host whose range overlaps those of both gibbons and koalas. Using hybridization capture and high-throughput sequencing, we have screened a wide range of rodent candidate hosts from Southeast Asia for KoRV- and GALV-like sequences. Only a Melomys burtoni subspecies from Wallacea (Indonesia) was positive for GALV. We report the genome sequence of this newly identified GALV, the critical domain for infection of its potential cellular receptor, and its phylogenetic relationships with the other previously characterized GALVs. We hypothesize that Melomys burtoni, and potentially related lineages with an Australo-Papuan distribution, may have played a key role in cross-species transmission to other taxa.


Assuntos
Vírus da Leucemia do Macaco Gibão/isolamento & purificação , Murinae/virologia , Infecções por Retroviridae/veterinária , Doenças dos Roedores/virologia , Animais , Sequenciamento de Nucleotídeos em Larga Escala , Indonésia , Vírus da Leucemia do Macaco Gibão/genética , Hibridização de Ácido Nucleico , Provírus/genética , Provírus/isolamento & purificação , Infecções por Retroviridae/virologia , Análise de Sequência de DNA
7.
Anim Biotechnol ; 28(2): 112-119, 2017 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-27791476

RESUMO

Toll-like receptor 2 (TLR2) plays an important role in recognition by the innate immune system of Gram-positive bacteria. As Gram-positive bacteria cause mastitis, we examined variations in the region of the TLR2 gene that codes for the extracellular domain. Samples of forty goats from a single dairy herd were collected, half with low SCC (≤200,000 cells/mL), and half with higher SCC. Two synonymous single nucleotide polymorphisms (SNPs) were identified: 840G > A and 1083A > G. One nonsynonymous SNP 739G > A was identified. This coded for valine or isoleucine, which have similar physiochemical properties, and was not in a region coding for a known functional domain. Surprisingly, the least square mean SCC of the heterozygous goats (146,220) was significantly lower than the SCC of homozygous GG goats (537,700; p = 0.004), although these two groups were similar in days in milk (p = 0.984), and there was no significant difference by breed (p = 0.941). Because factors other than mastitis can affect SCC and our sample sizes were limited, additional studies are needed to corroborate an association between TLR2 genotype and SCC or mastitis in goats.


Assuntos
Contagem de Células/veterinária , Cabras/genética , Cabras/metabolismo , Leite/citologia , Leite/fisiologia , Polimorfismo de Nucleotídeo Único/genética , Receptor 2 Toll-Like/genética , Animais , Feminino , Estudos de Associação Genética , Predisposição Genética para Doença/genética
8.
Mol Biol Evol ; 32(1): 109-20, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25261407

RESUMO

Endogenous retroviruses (ERVs) comprise 8% of the human genome and are common in all vertebrate genomes. The only retrovirus known to be currently transitioning from exogenous to endogenous form is the koala retrovirus (KoRV), making koalas (Phascolarctos cinereus) ideal for examining the early stages of retroviral endogenization. To distinguish endogenous from exogenous KoRV proviruses, we isolated koala genomic regions flanking KoRV integration sites. In three wild southern Australian koalas, there were fewer KoRV loci than in three captive Queensland koalas, consistent with reports that southern Australian koalas carry fewer KoRVs. Of 39 distinct KoRV proviral loci examined in a sire-dam-progeny triad, all proved to be vertically transmitted and endogenous; none was exogenous. Of the 39 endogenous KoRVs (enKoRVs), only one was present in the genomes of both the sire and the dam, suggesting that, at this early stage in the retroviral invasion of a host germ line, very large numbers of ERVs have proliferated at very low frequencies in the koala population. Sequence divergence between the 5'- and 3'-long terminal repeats (LTRs) of a provirus can be used as a molecular clock. Within each of ten enKoRVs, the 5'-LTR sequence was identical to the 3'-LTR sequence, suggesting a maximum age for enKoRV invasion of the koala germ line of approximately 22,200-49,900 years ago, although a much younger age is possible. Across the ten proviruses, seven LTR haplotypes were detected, indicating that at least seven different retroviral sequences had entered the koala germ line.


Assuntos
Retrovirus Endógenos/genética , Células Germinativas/virologia , Phascolarctidae/virologia , Provírus/genética , Integração Viral , Animais , Austrália , Retrovirus Endógenos/fisiologia , Evolução Molecular , Genoma , Genoma Viral , Haplótipos , Humanos , Phascolarctidae/classificação , Phascolarctidae/genética , Filogenia , Provírus/fisiologia , Sequências Repetidas Terminais
9.
J Hered ; 107(7): 573-580, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27515769

RESUMO

The koala (Phascolarctos cinereus) suffered population declines and local extirpation due to hunting in the early 20th century, especially in southern Australia. Koalas were subsequently reintroduced to the Brisbane Ranges (BR) and Stony Rises (SR) by translocating individuals from a population on French Island descended from a small number of founders. To examine genetic diversity and north-south differentiation, we genotyped 13 microsatellite markers in 46 wild koalas from the BR and SR, and 27 Queensland koalas kept at the US zoos. The Queensland koalas displayed much higher heterozygosity (H O = 0.73) than the 2 southern Australian koala populations examined: H O = 0.49 in the BR, whereas H O = 0.41 in the SR. This is consistent with the historical accounts of bottlenecks and founder events affecting the southern populations and contrasts with reports of high genetic diversity in some southern populations. The 2 southern Australian koala populations were genetically similar (F ST = 0.018, P = 0.052). By contrast, northern and southern Australian koalas were highly differentiated (F ST = 0.27, P < 0.001), thereby suggesting that geographic structuring should be considered in the conservation management of koalas. Sequencing of 648bp of the mtDNA control region in Queensland koalas found 8 distinct haplotypes, one of which had not been previously detected among koalas. Queensland koalas displayed high mitochondrial haplotype diversity (H = 0.753) and nucleotide diversity (π = 0.0072), indicating along with the microsatellite data that North American zoos have maintained high levels of genetic diversity among their Queensland koalas.


Assuntos
Variação Genética , Genética Populacional , Phascolarctidae/classificação , Phascolarctidae/genética , Animais , DNA Mitocondrial , Genótipo , Haplótipos , Repetições de Microssatélites , Filogenia , Queensland , Análise de Sequência de DNA , Vitória
10.
Mol Biol Evol ; 30(2): 299-304, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22983950

RESUMO

Although endogenous retroviruses are common across vertebrate genomes, the koala retrovirus (KoRV) is the only retrovirus known to be currently invading the germ line of its host. KoRV is believed to have first infected koalas in northern Australia less than two centuries ago. We examined KoRV in 28 koala museum skins collected in the late 19th and 20th centuries and deep sequenced the complete proviral envelope region from five northern Australian specimens. Strikingly, KoRV env sequences were conserved among koalas collected over the span of a century, and two functional motifs that affect viral infectivity were fixed across the museum koala specimens. We detected only 20 env polymorphisms among the koalas, likely representing derived mutations subject to purifying selection. Among northern Australian koalas, KoRV was already ubiquitous by the late 19th century, suggesting that KoRV evolved and spread among koala populations more slowly than previously believed. Given that museum and modern koalas share nearly identical KoRV sequences, it is likely that koala populations, for more than a century, have experienced increased susceptibility to diseases caused by viral pathogenesis.


Assuntos
Retrovirus Endógenos/genética , Evolução Molecular , Animais , Proteínas de Fusão gag-pol/química , Proteínas de Fusão gag-pol/genética , Produtos do Gene env/química , Produtos do Gene env/genética , Humanos , Modelos Moleculares , Phascolarctidae/genética , Phascolarctidae/virologia , Conformação Proteica
11.
Genes (Basel) ; 14(2)2023 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-36833353

RESUMO

Epizootic hemorrhagic disease (EHD) leads to high mortality in white-tailed deer (Odocoileus virginianus) and is caused by a double-stranded RNA (dsRNA) virus. Toll-like receptor 3 (TLR3) plays a role in host immune detection and response to dsRNA viruses. We, therefore, examined the role of genetic variation within the TLR3 gene in EHD among 84 Illinois wild white-tailed deer (26 EHD-positive deer and 58 EHD-negative controls). The entire coding region of the TLR3 gene was sequenced: 2715 base pairs encoding 904 amino acids. We identified 85 haplotypes with 77 single nucleotide polymorphisms (SNPs), of which 45 were synonymous mutations and 32 were non-synonymous. Two non-synonymous SNPs differed significantly in frequency between EHD-positive and EHD-negative deer. In the EHD-positive deer, phenylalanine was relatively less likely to be encoded at codon positions 59 and 116, whereas leucine and serine (respectively) were detected less frequently in EHD-negative deer. Both amino acid substitutions were predicted to impact protein structure or function. Understanding associations between TLR3 polymorphisms and EHD provides insights into the role of host genetics in outbreaks of EHD in deer, which may allow wildlife agencies to better understand the severity of outbreaks.


Assuntos
Cervos , Vírus da Doença Hemorrágica Epizoótica , Infecções por Reoviridae , Animais , Receptor 3 Toll-Like , Vírus da Doença Hemorrágica Epizoótica/genética
12.
BMC Evol Biol ; 12: 237, 2012 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-23217182

RESUMO

BACKGROUND: HIV-1 derives from multiple independent transfers of simian immunodeficiency virus (SIV) strains from chimpanzees to human populations. We hypothesized that human populations in west central Africa may have been exposed to SIV prior to the pandemic, and that previous outbreaks may have selected for genetic resistance to immunodeficiency viruses. To test this hypothesis, we examined the genomes of Biaka Western Pygmies, who historically resided in communities within the geographic range of the central African chimpanzee subspecies (Pan troglodytes troglodytes) that carries strains of SIV ancestral to HIV-1. RESULTS: SNP genotypes of the Biaka were compared to those of African human populations who historically resided outside the range of P. t. troglodytes, including the Mbuti Eastern Pygmies. Genomic regions showing signatures of selection were compared to the genomic locations of genes reported to be associated with HIV infection or pathogenesis. In the Biaka, a strong signal of selection was detected at CUL5, which codes for a component of the vif-mediated APOBEC3 degradation pathway. A CUL5 allele protective against AIDS progression was fixed in the Biaka. A signal of selection was detected at TRIM5, which codes for an HIV post-entry restriction factor. A protective mis-sense mutation in TRIM5 had the highest frequency in Biaka compared to other African populations, as did a protective allele for APOBEC3G, which codes for an anti-HIV-1 restriction factor. Alleles protective against HIV-1 for APOBEC3H, CXCR6 and HLA-C were at higher frequencies in the Biaka than in the Mbuti. Biaka genomes showed a strong signal of selection at TSG101, an inhibitor of HIV-1 viral budding. CONCLUSIONS: We found protective alleles or evidence for selection in the Biaka at a number of genes associated with HIV-1 infection or progression. Pygmies have also been reported to carry genotypes protective against HIV-1 for the genes CCR5 and CCL3L1. Our hypothesis that HIV-1 may have shaped the genomes of some human populations in West Central Africa appears to merit further investigation.


Assuntos
Etnicidade/genética , Predisposição Genética para Doença/genética , Infecções por HIV/genética , Seleção Genética , África Central , África Ocidental , Aminoidrolases/genética , Animais , Fatores de Restrição Antivirais , População Negra/etnologia , População Negra/genética , Proteínas de Transporte/genética , Proteínas Culina/genética , Proteínas de Ligação a DNA/genética , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Genótipo , Infecções por HIV/virologia , HIV-1/fisiologia , Antígenos HLA-C/genética , Interações Hospedeiro-Patógeno , Humanos , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Pan troglodytes/virologia , Polimorfismo de Nucleotídeo Único , Receptores CXCR6 , Receptores de Quimiocinas/genética , Receptores Virais/genética , Análise de Sequência de DNA , Síndrome de Imunodeficiência Adquirida dos Símios/transmissão , Síndrome de Imunodeficiência Adquirida dos Símios/virologia , Vírus da Imunodeficiência Símia/fisiologia , Fatores de Transcrição/genética , Proteínas com Motivo Tripartido , Ubiquitina-Proteína Ligases
13.
Mol Ecol ; 21(5): 1175-89, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22260276

RESUMO

Among elephants, the phylogeographic patterns of mitochondrial (mt) and nuclear markers are often incongruent. One hypothesis attributes this to sex differences in dispersal and in the variance of reproductive success. We tested this hypothesis by examining the coalescent dates of genetic markers within elephantid lineages, predicting that lower dispersal and lower variance in reproductive success among females would have increased mtDNA relative to nuclear coalescent dates. We sequenced the mitochondrial genomes of two forest elephants, aligning them to mitogenomes of African savanna and Asian elephants, and of woolly mammoths, including the most divergent mitogenomes within each lineage. Using fossil calibrations, the divergence between African elephant F and S clade mitochondrial genomes (originating in forest and savanna elephant lineages, respectively) was estimated as 5.5 Ma. We estimated that the (African) ancestor of the mammoth and Asian elephant lineages diverged 6.0 Ma, indicating that four elephantid lineages had differentiated in Africa by the Miocene-Pliocene transition, concurrent with drier climates. The coalescent date for forest elephant mtDNAs was c. 2.4 Ma, suggesting that the decrease in tropical forest cover during the Pleistocene isolated distinct African forest elephant lineages. For all elephantid lineages, the ratio of mtDNA to nuclear coalescent dates was much greater than 0.25. This is consistent with the expectation that sex differences in dispersal and in variance of reproductive success would have increased the effective population size of mtDNA relative to nuclear markers in elephantids, contributing to the persistence of incongruent mtDNA phylogeographic patterns.


Assuntos
Clima , Elefantes/genética , Evolução Molecular , Genoma Mitocondrial , África , Animais , Núcleo Celular/genética , DNA Mitocondrial/genética , Elefantes/classificação , Feminino , Fósseis , Masculino , Mamutes , Dados de Sequência Molecular , Filogenia , Filogeografia , Alinhamento de Sequência , Análise de Sequência de DNA
14.
BMC Genet ; 13: 92, 2012 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-23095716

RESUMO

BACKGROUND: The koala (Phascolarctos cinereus) is an arboreal marsupial that was historically widespread across eastern Australia until the end of the 19th century when it suffered a steep population decline. Hunting for the fur trade, habitat conversion, and disease contributed to a precipitous reduction in koala population size during the late 1800s and early 1900s. To examine the effects of these reductions in population size on koala genetic diversity, we sequenced part of the hypervariable region of mitochondrial DNA (mtDNA) in koala museum specimens collected in the 19th and 20th centuries, hypothesizing that the historical samples would exhibit greater genetic diversity. RESULTS: The mtDNA haplotypes present in historical museum samples were identical to haplotypes found in modern koala populations, and no novel haplotypes were detected. Rarefaction analyses suggested that the mtDNA genetic diversity present in the museum samples was similar to that of modern koalas. CONCLUSIONS: Low mtDNA diversity may have been present in koala populations prior to recent population declines. When considering management strategies, low genetic diversity of the mtDNA hypervariable region may not indicate recent inbreeding or founder events but may reflect an older historical pattern for koalas.


Assuntos
DNA Mitocondrial/genética , Variação Genética , Phascolarctidae/genética , Animais , Dano ao DNA , Haplótipos
15.
J Hered ; 103(3): 459-64, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22235141

RESUMO

Genetic analyses using ancient DNA from Pleistocene and early Holocene fossils have largely relied on mitochondrial DNA (mtDNA) sequences. Among woolly mammoths, Mammuthus primigenius, mtDNA analyses have identified 2 distinct clades (I and II) that diverged 1-2 Ma. Here, we establish that microsatellite markers can be effective on Pleistocene samples, successfully genotyping woolly mammoth specimens at 2 loci. Although significant differentiation at the 2 microsatellite loci was not detected between 16 clade I and 4 clade II woolly mammoths, our results demonstrate that the nuclear population structure of Pleistocene species can be examined using fast-evolving nuclear microsatellite markers.


Assuntos
Mamutes/genética , Repetições de Microssatélites/genética , Animais , DNA Mitocondrial/genética , Evolução Molecular , Especiação Genética , Técnicas de Genotipagem , Heterozigoto , Funções Verossimilhança , Filogenia , Marcas Tipográficas , Análise de Sequência de DNA , Sequências de Repetição em Tandem/genética
16.
PLoS One ; 17(11): e0274640, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36449540

RESUMO

Chronic wasting disease (CWD) is a fatal, highly infectious prion disease that affects captive and wild cervids. Chronic wasting disease is the only known transmissible spongiform encephalopathy affecting free-ranging wildlife. In CWD-positive deer, some haplotypes of the prion protein gene PRNP are detected at lower frequencies as compared to CWD-negative deer, as are some variants of the prion protein PrP. Here, we examined wild, hunter-harvested CWD-negative white-tailed deer (Odocoileus virginianus) to determine whether there were geographical or temporal differences in the PRNP haplotypes, PRNP diplotypes, PrP proteoforms, and in the proportion of deer with at least one protective haplotype. We sampled 96-100 hunter-harvested deer per county at two time points in the Illinois counties of Jo Daviess, LaSalle, and Winnebago, chosen based on their geographic locations and known occurrence of CWD. The entire coding region of PRNP was sequenced, with haplotypes, diplotypes, and PrP proteoforms inferred. Across time, in Winnebago there was a significant increase in PrP proteoform F (p = 0.034), which is associated with a lower vulnerability to CWD. In every county, there was an increase over time in the frequency of deer carrying at least one protective haplotype to CWD, with a significant increase (p = 0.02) in the Jo Daviess County CWD infected region. We also found that primer combination was important as there was an 18.7% difference in the number of the deer identified as homozygous depending on primer usage. Current Illinois state management practices continue to remove CWD infected deer from locally infected areas helping to keep CWD prevalence low. Nonetheless, continued research on spatial and temporal changes in PRNP haplotypes, PrP proteoforms, and levels of deer vulnerability among Illinois deer will be important for the management of CWD within the state of Illinois and beyond.


Assuntos
Cervos , Príons , Doença de Emaciação Crônica , Animais , Doença de Emaciação Crônica/genética , Proteínas Priônicas/genética , Cervos/genética , Príons/genética , Illinois
17.
Front Genet ; 13: 1021004, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36712847

RESUMO

Non-invasive biological samples benefit studies that investigate rare, elusive, endangered, or dangerous species. Integrating genomic techniques that use non-invasive biological sampling with advances in computational approaches can benefit and inform wildlife conservation and management. Here, we used non-invasive fecal DNA samples to generate low- to medium-coverage genomes (e.g., >90% of the complete nuclear genome at six X-fold coverage) and metagenomic sequences, combining widely available and accessible DNA collection cards with commonly used DNA extraction and library building approaches. DNA preservation cards are easy to transport and can be stored non-refrigerated, avoiding cumbersome or costly sample methods. The genomic library construction and shotgun sequencing approach did not require enrichment or targeted DNA amplification. The utility and potential of the data generated was demonstrated through genome scale and metagenomic analyses of zoo and free-ranging African savanna elephants (Loxodonta africana). Fecal samples collected from free-ranging individuals contained an average of 12.41% (5.54-21.65%) endogenous elephant DNA. Clustering of these elephants with others from the same geographic region was demonstrated by a principal component analysis of genetic variation using nuclear genome-wide SNPs. Metagenomic analyses identified taxa that included Loxodonta, green plants, fungi, arthropods, bacteria, viruses and archaea, showcasing the utility of this approach for addressing complementary questions based on host-associated DNA, e.g., pathogen and parasite identification. The molecular and bioinformatic analyses presented here contributes towards the expansion and application of genomic techniques to conservation science and practice.

18.
J Hered ; 102(5): 610-6, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21775678

RESUMO

A more complete description of African elephant phylogeography would require a method that distinguishes forest and savanna elephants using DNA from low-quality samples. Although mitochondrial DNA is often the marker of choice for species identification, the unusual cytonuclear patterns in African elephants make nuclear markers more reliable. We therefore designed and utilized genetic markers for short nuclear DNA regions that contain fixed nucleotide differences between forest and savanna elephants. We used M13 forward and reverse sequences to increase the total length of PCR amplicons and to improve the quality of sequences for the target DNA. We successfully sequenced fragments of nuclear genes from dung samples of known savanna and forest elephants in the Democratic Republic of Congo, Ethiopia, and Namibia. Elephants at previously unexamined locations were found to have nucleotide character states consistent with their status as savanna or forest elephants. Using these and results from previous studies, we estimated that the short-amplicon nuclear markers could distinguish forest from savanna African elephants with more than 99% accuracy. Nuclear genotyping of museum, dung, or ivory samples will provide better-informed conservation management of Africa's elephants.


Assuntos
Núcleo Celular/genética , DNA/química , Elefantes/genética , Animais , Sequência de Bases , Congo , Elefantes/classificação , Etiópia , Genes Ligados ao Cromossomo X , Variação Genética , Genótipo , Masculino , Namíbia , Especificidade da Espécie
19.
BMC Res Notes ; 14(1): 119, 2021 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-33771210

RESUMO

OBJECTIVE: The Sumatran rhinoceros is critically endangered, with fewer than 100 individuals surviving across its current range. Accurate census estimates of the remaining populations are essential for development and implementation of conservation plans. In order to enable molecular censusing, we here develop microsatellite markers with amplicon sizes of short length, appropriate for non-invasive fecal sampling. RESULTS: Due to limited sample quantity and potential lack of genome-wide diversity, Illumina sequence reads were generated from two Sumatran rhinoceros samples. Genomic screening identified reads with short tandem repeats and loci that were polymorphic within the dataset. Twenty-nine novel polymorphic microsatellite markers were characterized (A = 2.4; HO = 0.30). These were sufficient to distinguish among individuals (PID < 0.0001), and to distinguish among siblings (PID(sib) < 0.0001). Among rhinos in Indonesia, almost all markers were established as polymorphic and effective for genotyping DNA from fecal samples. Notably, the markers amplified and displayed microsatellite polymorphisms using DNA extracted from 11 fecal samples collected non-invasively from wild Sumatran rhinoceros. These microsatellite markers provide an important resource for a census and genetic studies of wild Sumatran rhinos.


Assuntos
Repetições de Microssatélites , Perissodáctilos , Animais , Genoma , Genômica , Indonésia , Repetições de Microssatélites/genética , Perissodáctilos/genética
20.
Prion ; 14(1): 214-225, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32835598

RESUMO

Chronic wasting disease (CWD) is caused by prions, infectious proteinaceous particles, PrPCWD. We sequenced the PRNP gene of 2,899 white-tailed deer (WTD) from Illinois and southern Wisconsin, finding 38 haplotypes. Haplotypes A, B, D, E, G and 9 others encoded Q95G96S100N103A123Q226, designated 'PrP variant A.' Haplotype C and 4 other haplotypes encoded PrP 'variant C' (Q95S96S100N103A123Q226). Haplotype F and two other haplotypes encoded PrP 'variant F' (H95G96S100N103A123Q226). The association of CWD with encoded PrP variants was examined in 2,537 tested WTD from counties with CWD. Relative to PrP variant A, CWD susceptibility was lower in deer with PrP variant C (OR = 0.26, p < 0.001), and even lower in deer with PrP variant F (OR = 0.10, p < 0.0001). Susceptibility to CWD was highest in deer with both chromosomes encoding PrP variant A, lower with one copy encoding PrP variant A (OR = 0.25, p < 0.0001) and lowest in deer without PrP variant A (OR = 0.07, p < 0.0001). There appeared to be incomplete dominance for haplotypes encoding PrP variant C in reducing CWD susceptibility. Deer with both chromosomes encoding PrP variant F (FF) or one encoding PrP variant C and the other F (CF) were all CWD negative. Our results suggest that an increased population frequency of PrP variants C or F and a reduced frequency of PrP variant A may reduce the risk of CWD infection. Understanding the population and geographic distribution of PRNP polymorphisms may be a useful tool in CWD management.


Assuntos
Cervos/genética , Estudos de Associação Genética , Predisposição Genética para Doença , Variação Genética , Proteínas Priônicas/genética , Doença de Emaciação Crônica/genética , Sequência de Aminoácidos , Animais , Proteínas Priônicas/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA