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531.
Extracellular enzyme production in solid culture media was analyzed in order to determine the variability among different Metarhizium anisopliae isolates. Using specific substrates, amylase, lipase, chitinase, and protease production was tested in 11 isolates from different regions of Brazil. Enzyme production was determined by the formation of a halo around the colony, and the diameters of both halo and colony were measured. The enzymatic index was expressed by the colony diameter/halo diameter ratio. In general, the isolates from the same region had similar enzymatic indexes, although similar indexes were also found for isolates from geographically distinct regions. The different isolates were tentatively grouped according to index similarity. 相似文献
532.
J Weissmann I J Taborda de Messias O Pribilla 《Anthropologischer Anzeiger; Bericht über die biologisch-anthropologische Literatur》1983,41(4):301-307
Three different population samples have been tested for properdin factor B markers: 395 individuals from Schleswig-Holstein (Germany), 343 individuals (Europids) from Southern Brazil, and 309 individuals (Negroids) from Guinea-Bissau (Western Africa). These samples are showing marked differences in the distribution of Bf gene frequencies. As for the sample from Southern Brazil the Bf data are confirming the assumption that the Caucasoid population in Southern Brazil is somewhat mixed with Negroids. 相似文献
533.
Ceres Maria Andrade da Mata Rezende Otto Richard Gottlieb 《Biochemical Systematics and Ecology》1973,1(2):111-118
An evolutionary scheme for shikimate-acetate derived xanthones is deduced from their substitution pattern. Increasing distance of a particular xanthone from the primitive precursor is symbolized by increasing numbers. Each xanthone containing plant species is characterized by the average of the numbers attributed to its constituents. Each genus is characterized by the average of the numbers calculated for its species. The method is useful in comparing phyletic order of genera within the Guttiferae. 相似文献
534.
Syomara Hakiko Matusita Soares de Rezende Maria Elita B. Castro Marlinda L. Souza 《Journal of invertebrate pathology》2009,(3):153-159
Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) has been widely used to control the velvetbean caterpillar, Anticarsia gemmatalis, in Brazil. To date, AgMNPV has been produced by larval infection and, due to in vivo production limitations and the continuing high demand for the biopesticide, attempts should be made to develop in vitro production of this virus. In order to investigate the effects caused by serial passage of AgMNPV in cell culture, we carried out a total of ten passages and analyzed the morphological and the genomic changes of the virus. After six passages, the many-polyhedra (MP) phenotype started to switch to the few-polyhedra (FP) phenotype which rapidly accumulated in the virus population. Ultrastructural analysis showed typical signs of FP mutant formation such as decrease in the number of polyhedra per cell, polyhedra aberrant morphology and low numbers of virions occluded in the protein matrix. Also enhanced BV production was observed from the fifth passage indicating that FP mutants were becoming predominant in comparison to the wild type virus. Restriction endonuclease analysis of the viral DNA revealed that lower and higher passages had similar profiles indicating that there were no large insertions or deletions or rearrangements in their genomes and indicating the generation of FP mutants instead of defective interfering viruses. 相似文献
535.
Ana C. Messias António P. Aguiar Lorraine Brennan Lígia M. Saraiva David L. Turner 《BBA》2006,1757(2):143-153
The NMR structure of the oxidised wild-type cytochrome c3 from Desulfovibrio vulgaris Hildenborough was determined in solution. Using a newly developed methodology, NMR data from the K45Q mutant was then grafted onto data from the wild-type protein to determine the structure in the region of the mutation. The structural origins of the redox-Bohr effect and haem-haem cooperativities are discussed with respect to the redox-related conformational changes observed in solution. 相似文献
536.
Effects of phenotypic complementarity and phylogeny on the nested structure of mutualistic networks 总被引:2,自引:1,他引:1
Recent studies have started to unravel the structure of mutualistic networks, although few functional explanations underlying such structure have been explored. We used computer simulations to test whether complementarity between phenotypic traits of plants and animals can explain the pervasive tendency of specialists to interact with proper subsets of species that generalists interact with (nested interactions), and how phylogeny affects such interaction patterns. Simultaneously, we assessed whether complementarity and phylogenetic structure were associated with patterns of interaction in a real mutualistic community. Simulation results support that highly nested networks can emerge from phenotypic complementarity, particularly when several traits are involved. The hierarchical structure of phylogenetic relations can also contribute to increased nestedness because traits determining complementarity are then inherited in a correlated fashion. Phylogenetic effects on resulting generalization levels are often low, but can be detected. Results from the empirical network support a relevant role of complementarity and phylogenetic history on interaction patterns. Our results demonstrate that these factors can contribute to nestedness, which emphasize the necessity of considering evolutionary mechanisms in studies of community structure. 相似文献
537.
538.
Granuloma reaction around Schistosoma mansoni eggs is the prominent lesion in human schistosomiasis. Studies have suggested the involvement of a series of suppressive mechanisms in the control of this reaction. Using an in vitro model of granuloma formation, we have shown that immune complexes (IC) isolated from sera of chronic intestinal schistosomiasis patients were able to reduce granulomatous reaction developed against soluble egg antigen-conjugated polyacrylamide beads. In this system, the role of the l-arginine-nitric oxide (NO) pathway in the formation of prostaglandin E(2) (PGE(2)) by human peripheral blood mononuclear cells (PBMC) of patients infected with schistosomiasis was investigated using IC. Preincubation of PBMC with IC produced a significant increase of both nitrite and PGE(2) levels in the cell supernatant. This effect was inhibited by coincubation of cells with Nomega-nitro-l-arginine methyl ester (L-NAME), a NO synthase inhibitor, showing that the release of PGE(2) subsequent to IC stimulation was driven by NO. The inhibitory effect of L-NAME on PGE(2) release by IC-treated PBMC was reversed by sodium nitroprusside, a known NO donor. Our results indicate that NO could be an important second signal for the stimulation of PGE(2) production induced by IC in PBMC from human schistosomiasis patients. 相似文献
539.
Antonio Galina Carlos Logullo Edmilson Fernandes de Souza Gustavo Lazzaro Rezende Wagner Seixas da Silva 《Physiologia plantarum》1999,105(1):17-23
The preference of maize ( Zea mays L.) mitochondrial hexokinase (EC 2.7.1.1.) for glucose and fructose and the ADP regulation were evaluated. The Michaelis-Menten constants (Km ) varied between 0.02 and 0.09 m M for glucose and from 2 to 6 m M for fructose as substrates. The value of Vmax was five times higher in the presence of glucose as compared with fructose in membrane-bound enzyme preparations. It was shown that ADP produced from the reaction inhibits the hexokinase activity (Ki =20–50 μ M ). However, the inhibition was very specific for adenine nucleotide. Only a small inhibition was observed when 1 m M of UDP, CDP or GDP was included in the assay medium. Nevertheless, the ADP inhibition was observed only when glucose was phosphorylated. In assay conditions where fructose serves as substrate, the affinity for ADP decreased by 10-fold (Ki varied between 500 and 1 000 μ M ). These kinetics properties were also observed in partially purified soluble enzyme preparations. These data suggest that the type of hexose bound to the catalytic site modulates the ADP control of maize mitochondrial hexokinase. 相似文献
540.
Thaís Rezende e Silva Figueira Guilherme Coutinho de Mello Serrano Paulo Arruda 《Tropical plant biology》2008,1(2):108-119
Prolamins, the seed storage proteins of maize, sorghum and coix were also found in sugarcane. Prolamins are grouped into structurally distinct classes termed the α-, β-, γ- and δ-prolamins. Orthologues for almost all of the α-, β-, γ- and δ-prolamins classes were identified in sugarcane. In maize, there are two molecular weight classes of α-prolamins, the 22 and 19 kD α-zeins. Sugarcane also possesses both the 22 kD and the 19 kD α-prolamins, which we denote as caneins, whereas sorghum and coix contain only the 22 kD α-prolamin (α-kafirin and α-coixin, respectively). Amino acid sequence alignments of the 22 and 19 kD α-prolamins from these plants revealed that both the 19 kD α-zein and the 19 kD α-canein lack around 20 amino acids at the sixth α-helix domain. We postulate that the 19 kD α-prolamins originated from a deletion of the sixth α-helix of a 22 kD counterpart in the saccharum lineage. Saccharum and sorghum diverged around five to nine million years ago (Mya), when only the 22 kD α-prolamins existed. The 19 kD α-canein must therefore have emerged after this time. Sorghum possesses a 19 kD α-prolamin similar to that of sugarcane and maize, but it contains the sixth α-helix domain lacking in the 19 kD α-zein and the 19 kD α-canein. This sorghum α-prolamin that we called 19 kD-like α-kafirin must be the ancestor of the 19 kD α-canein. The 19 kD-like α-kafirin could also be the ancestor of the 19 kD α-zein but it is also possible that the genes encoding the 19 kD α-zein and the 19 kD α-canein have evolved separately in these close groups. 相似文献