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911.
Diego Marcel Parreira de Castro Débora Reis de Carvalho Paulo dos Santos Pompeu Marcelo Zacharias Moreira Gabriela Bielefeld Nardoto Marcos Callisto 《PloS one》2016,11(3)
It is well recognized that assemblage structure of stream macroinvertebrates changes with alterations in catchment or local land use. Our objective was to understand how the trophic ecology of benthic macroinvertebrate assemblages responds to land use changes in tropical streams. We used the isotope methodology to assess how energy flow and trophic relations among macroinvertebrates were affected in environments affected by different land uses (natural cover, pasture, sugar cane plantation). Macroinvertebrates were sampled and categorized into functional feeding groups, and available trophic resources were sampled and evaluated for the isotopic composition of 13C and 15N along streams located in the Cerrado (neotropical savanna). Streams altered by pasture or sugar cane had wider and more overlapped trophic niches, which corresponded to more generalist feeding habits. In contrast, trophic groups in streams with native vegetation had narrower trophic niches with smaller overlaps, suggesting greater specialization. Pasture sites had greater ranges of resources exploited, indicating higher trophic diversity than sites with natural cover and sugar cane plantation. We conclude that agricultural land uses appears to alter the food base and shift macroinvertebrate assemblages towards more generalist feeding behaviors and greater overlap of the trophic niches. 相似文献
912.
Denise Silva Nogueira Pedro Henrique Gazzinelli-Guimar?es Fernando Sérgio Barbosa Nathália Maria Resende Caroline Cavalcanti Silva Luciana Maria de Oliveira Chiara Cássia Oliveira Amorim Fabrício Marcus Silva Oliveira Matheus Silvério Mattos Lucas Rocha Kraemer Marcelo Vidigal Caliari Soraya Gaze Lilian Lacerda Bueno Remo Castro Russo Ricardo Toshio Fujiwara 《PLoS neglected tropical diseases》2016,10(1)
Ascaris spp. infection affects 800 million people worldwide, and half of the world population is currently at risk of infection. Recurrent reinfection in humans is mostly due to the simplicity of the parasite life cycle, but the impact of multiple exposures to the biology of the infection and the consequences to the host’s homeostasis are poorly understood. In this context, single and multiple exposures in mice were performed in order to characterize the parasitological, histopathological, tissue functional and immunological aspects of experimental larval ascariasis. The most important findings revealed that reinfected mice presented a significant reduction of parasite burden in the lung and an increase in the cellularity in the bronchoalveolar lavage (BAL) associated with a robust granulocytic pulmonary inflammation, leading to a severe impairment of respiratory function. Moreover, the multiple exposures to Ascaris elicited an increased number of circulating inflammatory cells as well as production of higher levels of systemic cytokines, mainly IL-4, IL-5, IL-6, IL-10, IL-17A and TNF-α when compared to single-infected animals. Taken together, our results suggest the intense pulmonary inflammation associated with a polarized systemic Th2/Th17 immune response are crucial to control larval migration after multiple exposures to Ascaris. 相似文献
913.
Trunk wood of Iryanthera laevis Markgr. (Myristicaceae) contains 2′,4′-dihydroxy- 4,6′dimethoxydihydrochalcone, three 2′-hydroxy-4′,5′-methylenedioxyflavans with differently substituted A-rings (7-OH-6,8-diMe; 7-OH-5,8-diMe; 5-OH-7-OMe-6,8-diMe) and 1-(2′-hydroxy-4′-methoxy-5′-methylphenyl)-3(2″-hydroxy-4″,5″-methylenedioxphenyl)- propane, as well as three additional known diarylpropanes. 相似文献
914.
915.
Marcelo A. Fernandez-Viña Xiaojiang Gao M. Elisa Moraes J. Roberto Moraes Iracema Salatiel Sharon Miller Jeanette Tsai Yiping Sun Jiabin An Zulay Layrisse Ephraim Gazit Chaim Brautbar Peter Stastny 《Immunogenetics》1991,34(5):299-312
The use of polymerase chain reaction (PCR) and oligonucleotide hybridization offers a new approach for the definition of HLA class II alleles. It has been possible to determine 43 alleles of DRB1, four of DRB3, two of DRB4, four of DRB5, eight of DQA1, and 14 of DQB1. These alleles are inherited together in members of families and form closely associated groups which are found repeatedly and in characteristics patterns in different populations. We have determined the HLA class II alleles and analyzed their association in 431 healthy unrelated subjects including 161 North American Caucasians, 53 Latin Americans, 61 Blacks, 88 Chinese, and 68 Israeli Jews. For-locus haplotypes (DRB1; DRB3/4/5; DQA1; DQB1) were derived from 79 B cell lines and the analysis of segregation in 34 nuclear families. The B-cell lines yielded 37 and the families showed the same, and 20 other, haplotypic combinations. In addition to these 57 haplotypes, associated alleles were assigned in the unrelated panels following certain rules. The resulting haplotypes were assigned to groups known to share associated alleles. The groups were: (1) DR1, DR2, and DRw10 (13 haplotypes); (2) DR3 and DRw6 (26 haplotypes); (3) DR5 and DRw8 (24 haplotypes); (4) DR4, DR7, and DR9 (24 haplotypes). Their distribution in populations with different ethnic backgrounds was analyzed. The expressed DRB4 allele and its null mutant were determined by PCR and oligonucleotide hybridization. The different DR7 haplotypes resulting from these determinations were analyzed in a panel of 130 North American Caucasoids. This comprehensive analysis of class II HLA haplotypes in human populations should be useful in understanding the role of these genes and in various applications including anthropolgy, disease susceptibility, and transplantation of allogeneic organs and tissues.
Address correspondence and offprint requests to: P. Stastny 相似文献
916.
Marcelo dos Santos Guerra 《Plant Systematics and Evolution》1988,158(2-4):107-115
The chromatin structure of six diploids species ofCostus was analysed using conventional Giemsa staining, C-banding and DAPI/CMA fluorochromes. The interphase nuclei in all the species show an areticulate structure and the prophase chromosomes show large blocks of proximal condensed chromatin. After banding procedures, each chromosome exhibits only centromeric dot-like DAPI+/CMA– C-bands whereas the satellites (one pair at each karyotype) are weakly stained after C-banding and show a DAPI–/CMA+ fluorescence. Two chromocentres show bright fluorescence with CMA and weak staining after C-banding whereas the others chromocentres show only a small fraction of DAPI+ heterochromatin. These results were interpreted to mean that the greater part of the condensed chromatin has an euchromatic nature whereas two types of well localized heterochromatin occur in a small proportion. The Z-stage analysis suggests that heterochromatin and condensed euchromatin decondense at different times. The chromosome number and morphology of all species are given and the implications of the condensed euchromatin are discussed.Dedicated to Prof.Elisabeth Tschermak-Woess on the occasion of her 70th birthday. 相似文献
917.
Marcelo dos Santos Guerra 《Chromosoma》1988,97(1):80-87
The mitotic and meiotic chromosomes of five populations of Eleutherine bulbosa were analysed after C-banding and fluorochrome (DAPI/CMA) staining. All individuals showed heterozygosity in pair number I for a pericentric inversion and a tandem duplication in the inverted region of one of the homologues. The duplication comprised the secondary constriction and ca. 40% of its associated CMA+ heterochromatin. All the secondary constrictions were nucleolar organizers, but the repeated one seemed to be the most active. The inverted segment constituted ca. 70% of the chromosome length and included, in addition to the duplication and the centromere, two DAPI+ C-bands. These markers, especially the CMA+ blocks which were unique in the complement, permitted a detailed analysis of meiotic pairing. In practically all examples of late zygotene the CMA blocks were paired, which seems to mean that non-homologous pairing never occurred. At this stage the duplicated CMA+ block was clearly unpaired. At pachytene-diplotene the inverted region formed a typical loop without chiasmata. Although male meiosis was normal, no indication of sexual reproduction was found. A causal relationship between duplication, inversion and asexual reproduction is proposed to explain the maintenance of the heterozygosity. 相似文献
918.
Paepalanthus sect. Diphyomene has inflorescences arranged in umbels. The underlying bauplan seems however to be more complex and composed of several distinct subunits. Despite appearing superficially very similar, the morphology and anatomy of the inflorescences can supply useful information for the understanding of the phylogeny and taxonomy of the group. Inflorescences of Paepalanthus erectifolius, Paepalanthus flaccidus, Paepalanthus giganteus, and Paepalanthus polycladus were analyzed in regard to branching pattern and anatomy. In P. erectifolius, P. giganteus and P. polycladus the structure is a tribotryum, with terminal dibotryum, and with pherophylls bearing lateral dibotrya. In P. flaccidus, the inflorescence is a pleiobotryum, with terminal subunit, and without pherophylls. Secondary inflorescences may occur in all species without regular pattern. Especially when grown in sites without a pronounced seasonality, the distinction between enrichment zone (part of the same inflorescence) and new inflorescences may be obscured. The main anatomical features supplying diagnostic and phylogenetic information are as follows: (a) in the elongated axis, the thickness of the epidermal cell walls and the cortex size; (b) in the bracts, the quantity of parenchyma cells (c) in the scapes, the shape and the presence of a pith tissue. Therefore, P. sect. Diphyomene can be divided in two groups; group A is represented by P. erectifolius, P. giganteus and P. polycladus, and group B is represented by P. flaccidus. The differentiation is based in both, inflorescence structure and anatomy. Group A presents a life cycle and anatomical features similar to species of Actinocephalus. Molecular trees also point that these two groups are closely related. However, inflorescence morphology and blooming sequence are different. Species of group B present an inflorescence structure and anatomical features shared with many genera and species in Eriocaulaceae. The available molecular and morphology based phylogenies still do not allow a precise allocation of the group in the bulk of basal species of Paepalanthus collocated in P. sect. Variabiles. The characters described and used here supply however important information towards this goal. 相似文献
919.
Rogério Loesch Zacariotti Kathleen Fernandes Grego Wilson Fernandes Sávio Stefanini Sant'Anna Marcelo Alcindo de Barros Vaz Guimarães 《Zoo biology》2007,26(2):155-160
Two hundred‐ninety species of reptiles are estimated to need urgent action for conservation, with at least 113 threatened species worldwide. The International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species includes 80 species of snakes, with six native Brazilian species, a number likely to be an underestimation. Some authors believe that assisted reproduction would be an important tool to improve reproduction in captivity of some reptiles. An efficient technique for semen collection and evaluation is an important step in development of protocols for cryopreservation of semen or artificial insemination in snakes, contributing to the conservation of endangered species. Although these techniques are important, some basic semen parameters are described for four of the ~2,900 snake species in the world. The Brazilian rattlesnake (Crotalus durissus terrificus) was chosen as a model for semen collection in snakes because it is found quite often in Sao Paulo State. Semen was collected once from each animal by the same investigator during the mating season of this species in Brazil. After antiseptic cleansing of the skin around the cloaca, the snakes were injected subcutaneously with a dose of 15 mg/kg of 1% solution of lidocaine around the cloaca. Semen was collected with ventral massages after cloacal relaxation and directly from genital papilla inside the cloaca. A total of 28 ejaculates from 39 animals were obtained, representing collection efficiency of 71.80%. Semen volume and concentration in Brazilian rattlesnakes ranged from 3–70 µl and from 0.94–2.23 × 109 spermatozoa/ml, respectively. Zoo Biol 0:1–6, 2007. © 2007 Wiley‐Liss, Inc. 相似文献
920.