Dormancy cycles in buried seeds of three perennial Xyris (Xyridaceae) species from the Brazilian campo rupestre.

Dormancy cycles are an important mechanism for avoiding seed germination under unfavourable periods for seedling establishment. This mechanism has been scarcely studied in tropical species. Here, we studied three tropical and perennial species of Xyris, X. asperula, X. subsetigera and X. trachyphylla, to investigate in situ longevity and the existence of seasonal seed dormancy cycles. Seeds of three species of Xyris were buried in their natural habitat, with samples exhumed bimonthly for 18 months. Germination of exhumed seeds was assessed under a 12-h photoperiod over a broad range of temperatures. Seeds of X. trachyphylla were also subjected to treatments to overcome secondary dormancy. Seeds of all species are able to form a persistent seed bank and exhibit seasonal changes in germinability. Secondary dormancy was acquired during the rainy summer and was overcome during the subsequent dry season (autumn/winter). Desiccation partially overcomes secondary dormancy in X. trachyphylla seeds. Soil seed bank persistence and synchronisation of seed germination under favourable conditions for seedling establishment contribute to the persistence and regeneration of X. asperula, X. subsetigera and X. trachyphylla in their natural environment.

Genetic diversity analysis of Croton antisyphiliticus Mart. using AFLP molecular markers.

Croton antisyphiliticus Mart. is a medicinal plant native to Cerrado vegetation in Brazil, and it is popularly used to treat urogenital tract infections. The objective of the present study was to assess the genetic variability of natural C. antisyphiliticus populations using AFLP molecular markers. Accessions were collected in the states of Minas Gerais, São Paulo, and Goiás. The genotyping of individuals was performed using a LI-COR® DNA Analyzer 4300. The variability within populations was found to be greater than the variability between them. The F(ST) value was 0.3830, which indicated that the populations were highly structured. A higher percentage of polymorphic loci (92.16%) and greater genetic diversity were found in the population accessions from Pratinha-MG. Gene flow was considered restricted (N(m) = 1.18), and there was no correlation between genetic and geographic distances. The populations of C. antisyphiliticus exhibited an island-model structure, which demonstrates the vulnerability of the species.

Home range and density of three sympatric felids in the Southern Atlantic Forest, Brazil.

Home range and minimal population densities of Southern tiger cat (Leopardus guttulus), margay (Lepardus wiedii) and jaguarundi (Puma yagouaroundi) were estimated between 2005 and 2006 in Taquari Valley, near the southern edge of the Atlantic Rainforest in Brazil. Home range data were collected by conventional radio telemetry (VHF) locations in a highly fragmented landscape. The average home range size, calculated using 95% kernel density estimates, was 16.01 km2 for Southern tiger cat, 21.85 km2 for margay and 51.45 km2 for jaguarundi. Telemetry data were used to obtain minimal density estimates of 0.08 Southern tiger cats / km2, and 0.04 jaguarundi / km2. The density estimates arise from areas where ocelot (Leopardus pardalis) and other larger-bodied carnivores were locally extinct, and they suggest a specific type of mesopredator release known as the ocelot effect, which is likely enabling the increase in smaller felid populations in this area.

Home range and density of three sympatric felids in the Southern Atlantic Forest, Brazil / Área de vida e densidade de três felídeos simpátricos na Mata Atlântica do Brasil

Abstract Home range and minimal population densities of Southern tiger cat (Leopardus guttulus), margay (Lepardus wiedii) and jaguarundi (Puma yagouaroundi) were estimated between 2005 and 2006 in Taquari Valley, near the southern edge of the Atlantic Rainforest in Brazil. Home range data were collected by conventional radio telemetry (VHF) locations in a highly fragmented landscape. The average home range size, calculated using 95% kernel density estimates, was 16.01 km2 for Southern tiger cat, 21.85 km2 for margay and 51.45 km2 for jaguarundi. Telemetry data were used to obtain minimal density estimates of 0.08 Southern tiger cats / km2, and 0.04 jaguarundi / km2. The density estimates arise from areas where ocelot (Leopardus pardalis) and other larger-bodied carnivores were locally extinct, and they suggest a specific type of mesopredator release known as the ocelot effect, which is likely enabling the increase in smaller felid populations in this area.(AU)

Resumo Neste estudo são apresentadas áreas de vida e estimativas mínimas de densidade populacional do gato-do-mato-pequeno (Leopardus guttulus), gato-maracajá (Leopardus wiedii) e gato-mourisco (Puma yagouaroundi) obtidas entre 2005 e 2006, no Vale do Taquari, próximo ao limite sul da Mata Atlântica no Brasil. Os dados sobre área de vida foram coletados com a utilização de telemetria convencional (VHF) em uma paisagem altamente fragmentada. A área de vida média, calculada por Kernel 95%, foi de 16,01 km2 para o gato- do-mato-pequeno, 21,85 km2 para o gato-maracajá e 51,45 km2 para o gato-mourisco. Os dados de telemetria foram utilizados para obter uma estimativa de densidade mínima de 0,08 gatos-do-mato-pequenos por km2, e 0,04 gatos-mourisco por km2. As estimativas de densidade são oriundas de áreas sem a presença de jaguatiricas (Leopardus pardalis) ou outros predadores de maior porte, todos localmente extintos, com possíveis efeitos de um tipo específico de relaxamento de mesopredadores, conhecido como Efeito Pardalis que podem permitir o aumento do tamanho das populações de gatos menores.(AU)

Home range and density of three sympatric felids in the Southern Atlantic Forest, Brazil / Área de vida e densidade de três felídeos simpátricos na Mata Atlântica do Brasil

Abstract Home range and minimal population densities of Southern tiger cat (Leopardus guttulus), margay (Lepardus wiedii) and jaguarundi (Puma yagouaroundi) were estimated between 2005 and 2006 in Taquari Valley, near the southern edge of the Atlantic Rainforest in Brazil. Home range data were collected by conventional radio telemetry (VHF) locations in a highly fragmented landscape. The average home range size, calculated using 95% kernel density estimates, was 16.01 km2 for Southern tiger cat, 21.85 km2 for margay and 51.45 km2 for jaguarundi. Telemetry data were used to obtain minimal density estimates of 0.08 Southern tiger cats / km2, and 0.04 jaguarundi / km2. The density estimates arise from areas where ocelot (Leopardus pardalis) and other larger-bodied carnivores were locally extinct, and they suggest a specific type of mesopredator release known as the ocelot effect, which is likely enabling the increase in smaller felid populations in this area.

Resumo Neste estudo são apresentadas áreas de vida e estimativas mínimas de densidade populacional do gato-do-mato-pequeno (Leopardus guttulus), gato-maracajá (Leopardus wiedii) e gato-mourisco (Puma yagouaroundi) obtidas entre 2005 e 2006, no Vale do Taquari, próximo ao limite sul da Mata Atlântica no Brasil. Os dados sobre área de vida foram coletados com a utilização de telemetria convencional (VHF) em uma paisagem altamente fragmentada. A área de vida média, calculada por Kernel 95%, foi de 16,01 km2 para o gato- do-mato-pequeno, 21,85 km2 para o gato-maracajá e 51,45 km2 para o gato-mourisco. Os dados de telemetria foram utilizados para obter uma estimativa de densidade mínima de 0,08 gatos-do-mato-pequenos por km2, e 0,04 gatos-mourisco por km2. As estimativas de densidade são oriundas de áreas sem a presença de jaguatiricas (Leopardus pardalis) ou outros predadores de maior porte, todos localmente extintos, com possíveis efeitos de um tipo específico de relaxamento de mesopredadores, conhecido como “Efeito Pardalis” que podem permitir o aumento do tamanho das populações de gatos menores.

Home range and density of three sympatric felids in the Southern Atlantic Forest, Brazil

Abstract Home range and minimal population densities of Southern tiger cat (Leopardus guttulus), margay (Lepardus wiedii) and jaguarundi (Puma yagouaroundi) were estimated between 2005 and 2006 in Taquari Valley, near the southern edge of the Atlantic Rainforest in Brazil. Home range data were collected by conventional radio telemetry (VHF) locations in a highly fragmented landscape. The average home range size, calculated using 95% kernel density estimates, was 16.01 km2 for Southern tiger cat, 21.85 km2 for margay and 51.45 km2 for jaguarundi. Telemetry data were used to obtain minimal density estimates of 0.08 Southern tiger cats / km2, and 0.04 jaguarundi / km2. The density estimates arise from areas where ocelot (Leopardus pardalis) and other larger-bodied carnivores were locally extinct, and they suggest a specific type of mesopredator release known as the ocelot effect, which is likely enabling the increase in smaller felid populations in this area.

Resumo Neste estudo são apresentadas áreas de vida e estimativas mínimas de densidade populacional do gato-do-mato-pequeno (Leopardus guttulus), gato-maracajá (Leopardus wiedii) e gato-mourisco (Puma yagouaroundi) obtidas entre 2005 e 2006, no Vale do Taquari, próximo ao limite sul da Mata Atlântica no Brasil. Os dados sobre área de vida foram coletados com a utilização de telemetria convencional (VHF) em uma paisagem altamente fragmentada. A área de vida média, calculada por Kernel 95%, foi de 16,01 km2 para o gato- do-mato-pequeno, 21,85 km2 para o gato-maracajá e 51,45 km2 para o gato-mourisco. Os dados de telemetria foram utilizados para obter uma estimativa de densidade mínima de 0,08 gatos-do-mato-pequenos por km2, e 0,04 gatos-mourisco por km2. As estimativas de densidade são oriundas de áreas sem a presença de jaguatiricas (Leopardus pardalis) ou outros predadores de maior porte, todos localmente extintos, com possíveis efeitos de um tipo específico de relaxamento de mesopredadores, conhecido como Efeito Pardalis que podem permitir o aumento do tamanho das populações de gatos menores.

Polyclonal B-cell activation by Neisseria meningitidis capsular polysaccharides elicit antibodies protective against Trypanosoma cruzi infection in vitro.

A hyperimmune rabbit antiserum against group C Neisseria meningitidis agglutinated and lysed Trypanosoma cruzi metacyclic trypomastigotes in a complement-mediated reaction. Immunization of rabbits with the purified polysaccharide C from N. meningitidis and of human volunteers with the AC-polysaccharide vaccine against meningitis also resulted in antibody production cross-reactive with T. cruzi infective forms. The rabbit antibodies bound to parasites, lysed metacyclic forms, and recognized several components from lysates of cell-derived trypomastigotes. The sera from six human volunteers reacted with cell-cultured trypomastigotes in vitro, lysed these forms, and recognized glycoconjugates migrating diffusely on the top of immunoblots. One serum also reacted with the isolated mucin-like glycoconjugate carrying the Ssp-3 epitope from cell-derived trypomastigotes, but treatment with sialidase did not abolish this reactivity. The anti-AC human antiserum also protected against HeLa cell infection and markedly decreased the number of parasites liberated after cell burst. The polyclonal response that resulted from human immunization with N. meningitidis polysaccharides A and C comprised trypanolytic antibodies that recognized nonsialylated epitopes expressed on infective forms of the parasite. It is suggested that human AC vaccination could be potentially helpful as an adjuvant to a specific immunotherapy of Chagas disease, developed with native or recombinant antigens of the parasite.

Reactivity of chagasic sera with crude and highly purified glycosphingolipid fractions from Trypanosoma cruzi epimastigotes.

The reactivities of sera from patients with Chagas disease or from T. cruzi-immunized rabbits with two different lipid preparations of T. cruzi were assessed using epimastigote antigens. Serum reactivities were determined using a quantitative enzyme-linked immunosorbent assay (ELISA). Antigen 1 represents the lower phase obtained from crude lipid extract after Folch partition (LCL). Antigen 2 is a highly purified glycosphingolipid fraction (GSL). The LCL antigen discriminated quite well the reactivities of Chagasic patients' sera and sera from healthy individuals, as well as between the serum from a T. cruzi-immunized rabbit (TIRS) and normal rabbit serum (NRS). A strong reactivity with GSL was obtained with TIRS. Reactivity with GSL was also obtained with human Chagasic sera. Compared to a group of normal individuals, the reactions of antibodies directed against lipid antigens were considerably increased in sera of patients with Chagas disease. Chagasic sera did not differentiate between glycolipids with terminal beta-glucosyl or beta-galactosyl non-reducing units. They discriminated, however, glucosylceramides with differences in the ceramide structure. To determine the specificity of Chagasic sera, antibodies isolated on LCL-immunosorbent (LCL-Ch Abs) as well as on laminin-immunosorbent (Lam-Ch Abs) were tested against laminin and LCL antigens. We found that Lam-Ch Abs reacted with murine laminin, whereas the reaction was negative with LCL. In contrast, the LCL-Ch Abs reacted either with LCL antigens or with laminin. The reactivity with laminin was strong in comparison with LCL.(ABSTRACT TRUNCATED AT 250 WORDS)