排序方式: 共有124条查询结果,搜索用时 15 毫秒
81.
Sousa-Santos C Collares-Pereira MJ Almada V 《Journal of experimental zoology. Part A, Ecological genetics and physiology》2007,307(4):220-225
The endemic Iberian minnow Squalius alburnoides is a complex of fishes of hybrid origin including both males and females with distinct ploidy levels and varying proportions of the parental genomes. In this paper we demonstrated that in contrast to many vertebrate hybrid lineages the sperm of triploid hybrid males of S. alburnoides is viable and fully functional. Flow cytometry and analysis of sequences of a fragment of the beta-actin nuclear gene applied to progenitors and offspring evidenced that these males produced their sperm clonally, as already described for diploid hybrids. The presence of different types of fertile males (nonhybrid diploids with normal meiosis and both diploid and triploid hybrids) coupled with hybridogenetic meiosis in females endows this vertebrate complex with a high level of independence from other species and contributes to maintain its genetic variability. 相似文献
82.
In this paper, we analysed the phylogeography of the Critically Endangered fish Chondrostoma lusitanicum (Cyprinidae) endemic to Portugal. A fragment of the mitochondrial cyt b gene and one from the nuclear beta-actin gene were sequenced. The results support recognition of 3 ESU's distributed as follows:
1) Sado River, 2) the Tagus River basin and 3 independent nearby coastal rivers (collectively named "West") and 3) Lagoa de
Albufeira, a small coastal lagoon between Tagus and Sado basins. 相似文献
83.
S Stefanni R Castilho M Sala-Bozano J I Robalo S M Francisco R S Santos N Marques A Brito V C Almada S Mariani 《Heredity》2015,115(6):527-537
The processes and timescales associated with ocean-wide changes in the distribution
of marine species have intrigued biologists since Darwin''s earliest insights
into biogeography. The Azores, a mid-Atlantic volcanic archipelago located
>1000 km off the European continental shelf, offers ideal opportunities to
investigate phylogeographic colonisation scenarios. The benthopelagic sparid fish
known as the common two-banded seabream (Diplodus vulgaris) is now
relatively common along the coastline of the Azores archipelago, but was virtually
absent before the 1990s. We employed a multiple genetic marker approach to test
whether the successful establishment of the Azorean population derives from a recent
colonisation from western continental/island populations or from the demographic
explosion of an ancient relict population. Results from nuclear and mtDNA sequences
show that all Atlantic and Mediterranean populations belong to the same phylogroup,
though microsatellite data indicate significant genetic divergence between the
Azorean sample and all other locations, as well as among Macaronesian, western
Iberian and Mediterranean regions. The results from Approximate Bayesian Computation
indicate that D. vulgaris has likely inhabited the Azores for ∼40
(95% confidence interval (CI): 5.5–83.6) to 52 (95% CI:
6.32–89.0) generations, corresponding to roughly 80–150 years, suggesting
near-contemporary colonisation, followed by a more recent demographic expansion that
could have been facilitated by changing climate conditions. Moreover, the lack of
previous records of this species over the past century, together with the absence of
lineage separation and the presence of relatively few private alleles, do not exclude
the possibility of an even more recent colonisation event. 相似文献
84.
Winter segregation of migrant European robins Erithacus rubecula in relation to sex, age and size 总被引:2,自引:0,他引:2
Birds often show some form of social segregation during winter, both at large geographical scales (a consequence of differential migration) and at the regional or local level, when comparing different habitats or micro-habitats. However, our understanding of the mechanisms underlying such patterns is still poor. These issues have been rarely investigated in migratory Old-World passerines, particularly with respect to differences between the sexes. In this study, we show that female European robins Erithacus rubecula (sexed by molecular techniques) greatly outnumber males in southern Iberia, which confirms that this species is a differential migrant with a strong latitudinal segregation of the sexes. Furthermore, sex, age and body size influence the habitat distribution of robins in winter. Subordinate birds (females, juveniles and small individuals) were generally more common in habitats with a greater shrub development, and comparatively scarce in woodlands with relatively little undergrowth. Birds wintering in woodlands were in better condition (assessed by breast-muscle scoring) than birds wintering in shrubland. These results are consistent with the hypothesis that proposes that social dominance, mediated by differences in size and experience, is important in determining the habitat segregation of sex and age classes. The alternative hypothesis (habitat specialization), although not specifically supported by our findings, cannot be ruled out on the basis of the available evidence. 相似文献
85.
Reproductive behaviour of the black-striped pipefish Syngnathus abaster (Pisces; Syngnathidae) 总被引:1,自引:0,他引:1
K. Silva †‡ N. M. Monteiro †§ M. N. Vieira † V. C. Almada 《Journal of fish biology》2006,69(6):1860-1869
The reproductive behaviour of Syngnathus abaster is described and compared with those of other syngnathids. The need for standardized behavioural data is discussed in light of the actual theories of evolution of mating patterns and sex-role reversal within this family. 相似文献
86.
87.
Christophe Vieira Filipe Henriques Sofie D'hondt Ana Neto Carmen H. Almada Manfred Kaufmann Marta Sansón Carlos Sangil Olivier De Clerck 《Journal of phycology》2020,56(2):346-357
The brown alga Lobophora (Dictyotales, Phaeophyceae) is an important macroalga in the North-eastern Atlantic archipelagos (i.e., Macaronesia). Notably in the Canaries it can dominate benthic assemblages. While the genus has been the subject of several ecological studies in the Canaries, no study has yet been conducted to assess species-level diversity of Lobophora in Macaronesia. We reassessed the diversity of Lobophora in Macaronesia, reporting the presence of seven species (L. caboverdeana sp. nov., L. canariensis, L. dagamae sp. nov., L. delicata, L. dispersa, L. littlerorum, and L. schneideri). Lobophora spp. from Macaronesia are morphologically and ecologically distinguishable. In the Canaries, L. schneideri dominates the photophilic assemblages from the intertidal to 20-30 m depth. Lobophora dagamae sp. nov. grows in less illuminated shallow habitats, and replaces L. schneideri from 30 to ~80 m. Lobophora canariensis also has a wide vertical distribution, from the intertidal to deep waters, while L. delicata, L. dispersa and L. littlerorum grow in shallow waters. The dominance of species with an upright habit versus prostrate or crustose species may be mediated by the pressure of herbivores. Four species have an amphi-Atlantic distribution: L. littlerorum, L. canariensis, L. delicata, and L. schneideri. Lobophora schneideri and L. delicata are furthermore distributed in the Mediterranean Sea. By sampling a pivotal region in the Atlantic, this study significantly improves our knowledge of Lobophora biogeography in the Atlantic Ocean. Macaronesia constitutes a species–poor region for Lobophora where no diversification events occurred, and a region of overlap between the Greater Caribbean and the Indo-Pacific. 相似文献
88.
A case of paracoccidioidomycosis with ocular involvement is studied. Brazilian literature is reviewed. The scarcity of human ocular mycosis is commented on. The most frequent clinic aspects of ocular lesions in natural mycosis are described.
Resumo Um caso de paracoccidioidomicose pulmonar e linfática seguido de comprometimento conjuntivo-palpebral é estudado, em São Paulo.A literatura nacional é revista. As lesões oculares, mais frequentemente verificadas, na paracoccidioidomicose natural são descritas, minuciosamente. O pequeno número de casos humanos com comprometimento ocular é discutido.A severidade e a frequencia das lesões oculares em animais inoculados intracardiacamente, com cultivos de P. brasiliensis sugerem disseminação hematogênica ocular da paracoccidioidomicose humana.相似文献
89.
90.
Alessandra Castiglioni Gianfranca Corna Elena Rigamonti Veronica Basso Michela Vezzoli Antonella Monno Albert E. Almada Anna Mondino Amy J. Wagers Angelo A. Manfredi Patrizia Rovere-Querini 《PloS one》2015,10(6)
Muscle injury induces a classical inflammatory response in which cells of the innate immune system rapidly invade the tissue. Macrophages are prominently involved in this response and required for proper healing, as they are known to be important for clearing cellular debris and supporting satellite cell differentiation. Here, we sought to assess the role of the adaptive immune system in muscle regeneration after acute damage. We show that T lymphocytes are transiently recruited into the muscle after damage and appear to exert a pro-myogenic effect on muscle repair. We observed a decrease in the cross-sectional area of regenerating myofibers after injury in Rag2-/- γ-chain-/- mice, as compared to WT controls, suggesting that T cell recruitment promotes muscle regeneration. Skeletal muscle infiltrating T lymphocytes were enriched in CD4+CD25+FOXP3+ cells. Direct exposure of muscle satellite cells to in vitro induced Treg cells effectively enhanced their expansion, and concurrently inhibited their myogenic differentiation. In vivo, the recruitment of Tregs to acutely injured muscle was limited to the time period of satellite expansion, with possibly important implications for situations in which inflammatory conditions persist, such as muscular dystrophies and inflammatory myopathies. We conclude that the adaptive immune system, in particular T regulatory cells, is critically involved in effective skeletal muscle regeneration. Thus, in addition to their well-established role as regulators of the immune/inflammatory response, T regulatory cells also regulate the activity of skeletal muscle precursor cells, and are instrumental for the proper regeneration of this tissue. 相似文献