930 resultados para Russian wheat aphid, population genetics, native range, invasive pathways, genetic isolation, demography, salivary gland genes, selection


Relevância:

100.00% 100.00%

Publicador:

Resumo:

A fauna de mamíferos do estado de São Paulo consta de 231 táxons, sendo este número uma estimativa da real diversidade presente na região, dado a falta de amostragem em grandes extensões do estado, e também de revisões taxonômicas para determinados grupos. Ainda assim, nosso conhecimento aumentou em 20% desde a última estimativa em 1998, principalmente em relação aos quirópteros e roedores. Estes dados são provenientes de inventários faunísticos, e também do estudo de espécimes depositados em coleções científicas oriundos de revisões taxonômicas. Também temos um maior volume de dados a respeito da distribuição dos mamíferos em relação às diferentes paisagens presentes no estado, o que nos permite dividir a mastofauna em três componentes distintos: o mais importante desses é o das espécies generalistas, que ocorrem em todas as principais paisagens do estado; o segundo grupo concentra espécies das formações abertas, e o terceiro grupo inclui as espécies essencialmente florestais. Além disso, o número de estudos que tem se preocupado com o efeito da fragmentação de hábitats sobre as comunidades de mamíferos, bem como a respeito da permeabilidade das espécies em áreas alteradas, também aumentaram. Dados a respeito da ocorrência, abundância e vulnerabilidade das espécies foram essenciais para traçar estratégias em relação à escolha de áreas e à indicação de ações prioritárias para a conservação dos mamíferos no estado, assim como classificar as espécies nas diferentes categorias de ameaças propostas, culminando na Lista das Espécies Ameaçadas do Estado de São Paulo. Entretanto, ainda existem inúmeras lacunas de conhecimento, que vão desde o número limitado de amostras zoológicas, até a falta de informações acerca da ecologia e história natural de várias espécies. É imprescindível que aumentemos as amostras de mamíferos em coleções zoológicas, principalmente em áreas de Floresta Ombrófila Densa, nos fragmentos de Cerrado, bem como em áreas do centro e oeste do Estado, que permanecem ainda pouco estudadas, com o objetivo de produzir um maior número de revisões taxonômicas em diversos grupos de mamíferos, e de estudos com abordagens filogeográficas e de genética de populações, para diagnosticarmos de forma efetiva a riqueza de mamíferos no estado, bem como os mecanismos evolutivos responsáveis por esta diversificação. Aliados a esses estudos serão necessárias abordagens ecológicas para gerarmos conhecimento, que em conjunto, nos permitirá avaliarmos o estado de conservação dos mamíferos de São Paulo e tomarmos decisões sobre as melhores estratégias para manejarmos e preservarmos estas espécies.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Salivary gland polytene chromosomes of 4th instar Anopheles darlingi Root were examined from multiple locations in the Brazilian Amazon. Minor modifications were made to existing polytene photomaps. These included changes to the breakpoint positions of several previously described paracentric inversions and descriptions of four new paracentric inversions, two on the right arm of chromosome 3 and two on the left arm of chromosome 3 that were found in multiple locations. A total of 18 inversions on the X (n = 1) chromosome, chromosome 2 (n = 7) and 3 (n = 11) were scored for 83 individuals from Manaus, Macapá and Porto Velho municipalities. The frequency of 2Ra inversion karyotypes in Manaus shows significant deficiency of heterozygotes (p < 0.0009). No significant linkage disequilibrium was found between inversions on chromosome 2 and 3. We hypothesize that at least two sympatric subpopulations exist within the An. darlingi population at Manaus based on inversion frequencies.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Elysia timida (Risso, 1818) three decades of research.— During the last 30 years, studies on Elysia timida (Risso, 1818) have addressed various aspects related to food sources, photosynthetic efficiency of kleptoplasts, population genetics, chemical ecology and reproductive biology, both in the Mediterranean Sea and in the Mar Menor coastal lagoon. E. timida shows a strong specific interaction with Acetabularia acetabulum, retaining functional chloroplasts for at least 45 days and obtaining extra energy in periods when food resources are scarce. It shows control of parapodia, avoiding pigment photodestruction under oversaturated light conditions. The chemical ecological relationships established between E. timida and its potential predator fish, Thalassoma pavo, have also been evaluated, and it has been found that that the extracts of the mollusc contain repellent and unpalatable polypropionate compounds. Population genetics has demonstrated the genetic divergence between populations showing high and significant values of FST and genetic distances, and at least six privative alleles that are not shared with Mediterranean populations have been detected in lagoon populations. This sacoglossan is a poecilogonic species, and its lagoon populations show a greater reproductive output than Mediterranean populations; they produce a greater number of egg masses and embyros per individual, and the capsules have a wider diameter.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Bubo bubo is the largest owl in the world, showing a wide geographical distribution throughout the Palaearctic region. It underwent a demographic decline in many European countries during the last century and was considered “vulnerable” (Annex II of the CITES). Nowadays, it is classified as “Least Concern” according to IUCN. Despite its ecological importance and conservation status, few polymorphic molecular markers are available to study its diversity and population genetics. We report on the isolation and development of 10 new microsatellites for the Eagle owl, B. bubo. All loci (10 tetra-nucleotide) are characterized by high polymorphism levels. Number of alleles ranged from 5 to 13 and expected heterozygosity varied from 0.733 to 0.840. These microsatellites would be very useful to assess the genetic diversity, connectivity patterns and parentage of B. bubo. This information will allow to establish new conservation strategies and improve the management of the species.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Large wild herbivores are crucial to ecosystems and human societies. We highlight the 74 largest terrestrial herbivore species on Earth (body mass≥100 kg), the threats they face, their important and often overlooked ecosystem effects, and the conservation efforts needed to save them and their predators from extinction. Large herbivores aregenerally facing dramatic population declines and range contractions, such that ~60% are threatened with extinction. Nearly all threatened species are in developing countries, where major threats include hunting, land-use change, and resource depression by livestock. Loss of large herbivores can have cascading effects on other species including large carnivores, scavengers, mesoherbivores, small mammals, and ecological processes involving vegetation, hydrology, nutrient cycling, and fire regimes. The rate of large herbivore decline suggests that ever-largerswaths of the world will soon lack many of the vital ecological services these animals provide, resulting in enormous ecological and social costs.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Polymorphism describes two or more distinct, genetically determined, phenotypes that co-occur in the same population, where the rarest morph is maintained at a frequency above the mutation rate (Ford 1945; Huxley 1955). In a recent opinion piece, we explored a new idea regarding the role of genetic architectures and morph interactions in colour polymorphisms and how this can negatively affect population performance (Bolton et al. 2015). In this issue of Molecular Ecology, Forsman (2016) thoroughly discusses the current evidence for polymorphisms enhancing population performance and critiques the validity of the definitions of polymorphism we use in our original paper. We respond by clarifying that the negative consequences of polymorphisms that we discussed are likely to be most pertinent in species that have a particular set of characteristics, such as strong sexual or social interactions between morphs and discrete genetic architectures. Although it was not our intention to redefine polymorphism, we do believe that there should be further discussion about refining or characterizing balanced polymorphisms with respect to the degree of morph sympatry, discreteness of traits and their underlying genetic architecture, and the types of selection that drive and maintain the variation. The latter describes whether polymorphism is primarily maintained by external factors such as predation pressure or internal factors such as interactions with members of the same species. The contribution of Forsman (2016) is useful to this discussion, and we hope that our exchange of opinions will inspire new empirical and theoretical ideas on the origin and maintenance of colour polymorphisms.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background: Intensified selection of polled individuals has recently gained importance in predominantly horned dairy cattle breeds as an alternative to routine dehorning. The status quo of the current polled breeding pool of genetically-closely related artificial insemination sires with lower breeding values for performance traits raises questions regarding the effects of intensified selection based on this founder pool. Methods: We developed a stochastic simulation framework that combines the stochastic simulation software QMSim and a self-designed R program named QUALsim that acts as an external extension. Two traits were simulated in a dairy cattle population for 25 generations: one quantitative (QMSim) and one qualitative trait with Mendelian inheritance (i.e. polledness, QUALsim). The assignment scheme for qualitative trait genotypes initiated realistic initial breeding situations regarding allele frequencies, true breeding values for the quantitative trait and genetic relatedness. Intensified selection for polled cattle was achieved using an approach that weights estimated breeding values in the animal best linear unbiased prediction model for the quantitative trait depending on genotypes or phenotypes for the polled trait with a user-defined weighting factor. Results: Selection response for the polled trait was highest in the selection scheme based on genotypes. Selection based on phenotypes led to significantly lower allele frequencies for polled. The male selection path played a significantly greater role for a fast dissemination of polled alleles compared to female selection strategies. Fixation of the polled allele implies selection based on polled genotypes among males. In comparison to a base breeding scenario that does not take polledness into account, intensive selection for polled substantially reduced genetic gain for this quantitative trait after 25 generations. Reducing selection intensity for polled males while maintaining strong selection intensity among females, simultaneously decreased losses in genetic gain and achieved a final allele frequency of 0.93 for polled. Conclusions: A fast transition to a completely polled population through intensified selection for polled was in contradiction to the preservation of high genetic gain for the quantitative trait. Selection on male polled genotypes with moderate weighting, and selection on female polled phenotypes with high weighting, could be a suitable compromise regarding all important breeding aspects.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Blast is a major disease of rice in Brazil, the largest rice-producing country outside Asia. This study aimed to assess the genetic structure and mating-type frequency in a contemporary Pyricularia oryzae population, which caused widespread epidemics during the 2012/13 season in the Brazilian lowland subtropical region. Symptomatic leaves and panicles were sampled at flooded rice fields in the states of Rio Grande do Sul (RS, 34 fields) and Santa Catarina (SC, 21 fields). The polymorphism at ten simple sequence repeats (SSR or microsatellite) loci and the presence of MAT1-1 or MAT1-2 idiomorphs were assessed in a population comprised of 187 isolates. Only the MAT1-2 idiomorph was found and 162 genotypes were identified by the SSR analysis. A discriminant analysis of principal components (DAPC) of SSR data resolved four genetic groups, which were strongly associated with the cultivar of origin of the isolates. There was high level of genotypic diversity and moderate level of gene diversity regardless whether isolates were grouped in subpopulations based on geographic region, cultivar host or cultivar within region. While regional subpopulations were weakly differentiated, high genetic differentiation was found among subpopulations comprised of isolates from different cultivars. The data suggest that the rice blast pathogen population in southern Brazil is comprised of clonal lineages that are adapting to specific cultivar hosts. Farmers should avoid the use of susceptible cultivars over large areas and breeders should focus at enlarging the genetic basis of new cultivars.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

For quite some time, debate has raged about what the human race can and should do with its knowledge of genetics. We are now nearly 60 years removed from the work of Watson and Crick who determined the structure of deoxyribonucleic acid (DNA), yet our opinions as how best to employ scientific knowledge of the human genome, remain as diverse and polarised as ever. Human judgment is often shaped and coloured by popular media and culture, so it should come as no surprise that box office movies such as Gattaca (1997) continue to play a role in informing public opinion on genetics. In order to perform well at the box office, movies such as Gattaca take great liberty in sensationalising (and even distorting) the implications that may result from genetic screening and testing. If the public’s opinion on human genetics is strongly derived from the box office and popular media, then it is no wonder that the discourse on human genetics is couched in the polar parlances of future utopias or future dystopias. When legislating in an area like genetic discrimination in the workforce, we must be mindful of not overplaying the causal link between genetic predisposition towards a disability and an employee’s ability to perform the inherent requirements of their job. Genetic information is ultimately about people, it is not about genes. Genetic discrimination is ultimately about actions, it is not about the intrinsic value of genetic information.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A novel Glass Fibre Reinforced Polymer (GFRP) sandwich panel was developed by an Australian manufacturer for civil engineering applications. This research is motivated by the new applications of GFRP sandwich structures in civil engineering such as slab, beam, girder and sleeper. An optimisation methodology is developed in this work to enhance the design of GFRP sandwich beams. The design of single and glue laminated GFRP sandwich beam were conducted by using numerical optimisation. The numerical multi-objective optimisation considered a design two objectives simultaneously. These objectives are cost and mass. The numerical optimisation uses the Adaptive Range Multi-objective Genetic Algorithm (ARMOGA) and Finite Element (FE) method. Trade-offs between objectives was found during the optimisation process. Multi-objective optimisation shows a core to skin mass ratio equal to 3.68 for the single sandwich beam cross section optimisation and it showed that the optimum core to skin thickness ratio is 11.0.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

BACKGROUND: Genetic susceptibility to multiple sclerosis (MS) has been recognised for many years. Considerable data exist from the northern hemisphere regarding the familial recurrence risks for MS, but there are few data for the southern hemisphere and regions at lower latitude such as Australia. To investigate the interaction between environmental and genetic causative factors in MS, the authors undertook a familial recurrence risk study in three latitudinally distinct regions of Australia. METHODS: Immediate and extended family pedigrees have been collected for three cohorts of people with MS in Queensland, Victoria and Tasmania spanning 15° of latitude. Age of onset data from Queensland were utilised to estimate age-adjusted recurrence rates. RESULTS: Recurrence risks in Australia were significantly lower than in studies from northern hemisphere populations. The age-adjusted risk for siblings across Australia was 2.13% compared with 3.5% for the northern hemisphere. A similar pattern was seen for other relatives. The risks to relatives were proportional to the population risks for each site, and hence the sibling recurrence-risk ratio (λ(s)) was similar across all sites. DISCUSSION: The familial recurrence risk of MS in Australia is lower than in previously reported studies. This is directly related to the lower population prevalence of MS. The overall genetic susceptibility in Australia as measured by the λ(s) is similar to the northern hemisphere, suggesting that the difference in population risk is explained largely by environmental factors rather than by genetic admixture.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In Australian criminal justice systems, a wide range of pathways to sentencing and punishment exist alongside traditional court processes. In particular, therapeutic jurisprudence ('TJ') processes have emerged during the last quarter of a century and now occupy a key position in the criminal justice landscape. This article provides an introduction to TJ, highlighting in particular the emphasis it places on the active participation of offenders, before critically discussing offenders' capacity to engage with TJ processes. The article then summarises the research on the oral competence of offenders, and argues that offenders who lack oral competence may be disadvantaged in TJ processes. Finally, we provide an overview of the limited guidance that has been provided to TJ practitioners on how to maximise the participation of offenders with limited oral competence.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Human polybrominated diphenyl ether (PBDE) exposure occurs through a range of pathways including: ingestion of dust including hand-to-mouth contact; inhalation (air/particulate matter); and ingestion via food including the unique nutrition sources of human milk and placental transfer. While inhalation has been deemed a minor source of exposure, ingestion of food and dust make greater contributions to overall PBDE body burden with intake via dust reported to be much higher in infants than in adults. PBDEs have been detected in samples of human milk, blood serum, cord blood, and adipose tissue worldwide. Concentrations have been found to be highest in populations from North America, followed by Australia, Europe, and Asia. While factors such as gender and parity may not affect concentrations, occupational exposure and age (infants and children) are associated with higher PBDE concentrations. In contrast to “traditional” persistent organic pollutants, there is an inverse relationship between PBDE body burden and age. Predicted body burden calculated using available information on intake and elimination rates of BFRs appears to underestimate measured human body burden data obtained through analysis of BFRs in blood or human milk. This may be due to unknown exposure or inaccurate elimination data. Further exposure studies should focus on younger age groups and an investigation of human PBDE half-lives.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Fibroblast growth factors (FGFs) are potent mitogens, morphogens, and inducers of angiogenesis, and FGF signaling governs the genesis of diverse tissues and organs from the earliest stages. With such fundamental embryonic and homeostatic roles, it follows that aberrant FGF signaling underlies a variety of diseases. Pathological modifications to FGF expression are known to cause salivary gland aplasia and autosomal dominant hypophosphatemic rickets, while mutations in FGF receptors (FGFRs) result in a range of skeletal dysplasias. Anomalous FGF signaling is also associated with cancer development and progression. Examples include the overexpression of FGF2 and FGF6 in prostate cancer, and FGF8 overexpression in breast and prostate cancers. Alterations in FGF signaling regulators also impact tumorigenesis, which is exemplified by the down-regulation of Sprouty 1, a negative regulator of FGF signaling, in prostate cancer. In addition, several FGFRs are mutated in human cancers (including FGFR2 in gastric cancer and FGFR3 in bladder cancer). We recently identified intriguing alterations in the FGF pathway in a novel model of bladder carcinoma that consists of a parental cell line (TSU-Pr1/T24) and two sublines with increasing metastatic potential (TSU-Pr1-B1 and TSU-Pr1-B2), which were derived successively through in vivo cycling. It was found that the increasingly metastatic sublines (TSU-Pr1-B1 and TSU-Pr1-B2) had undergone a mesenchymal to epithelial transition. FGFR2IIIc expression, which is normally expressed in mesenchymal cells, was increased in the epithelial-like TSU-Pr1-B1 and TSU-Pr1-B2 sublines and FGFR2 knock-down was associated with the reversion of cells from an epithelial to a mesenchymal phenotype. These observations suggest that modified FGF pathway signaling should be considered when studying other cancer types.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Carcinoma ex pleomorphic adenoma (Ca ex PA) is a carcinoma arising from a primary or recurrent benign pleomorphic adenoma. It often poses a diagnostic challenge to clinicians and pathologists. This study intends to review the literature and highlight the current clinical and molecular perspectives about this entity. The most common clinical presentation of CA ex PA is of a firm mass in the parotid gland. The proportion of adenoma and carcinoma components determines the macroscopic features of this neoplasm. The entity is difficult to diagnose pre-operatively. Pathologic assessment is the gold standard for making the diagnosis. Treatment for Ca ex PA often involves an ablative surgical procedure which may be followed by radiotherapy. Overall, patients with Ca ex PA have a poor prognosis. Accurate diagnosis and aggressive surgical management of patients presenting with Ca ex PA can increase their survival rates. Molecular studies have revealed that the development of Ca ex PA follows a multi-step model of carcinogenesis, with the progressive loss of heterozygosity at chromosomal arms 8q, then 12q and finally 17p. There are specific candidate genes in these regions that are associated with particular stages in the progression of Ca ex PA. In addition, many genes which regulate tumour suppression, cell cycle control, growth factors and cell-cell adhesion play a role in the development and progression of Ca ex PA. It is hopeful that these molecular data can give clues for the diagnosis and management of the disease.