Cultivable cellulolytic fungi isolated from the gut of Amazonian aquatic insects

Fungos filamentosos tem sido alvo de estudos de bioprospecção devido à sua grande eficiencia em produzir enzimas extracelulares, as quais tem grande potencial para uso em bioindústrias. Neste estudo, fungos filamentosos foram isolados do intestino de larvas de insetos aquáticos da Amazônia, para avaliar sua atividade celulolítica. Foram coletadas 69 larvas de insetos aquáticos fragmentadores de três gêneros: Phylloicus (Trichoptera: Calamoceratidae), Triplectides (Trichoptera:Leptoceridae) e Stenochironomus (Diptera: Chironomidae) em dez igarapés de uma área protegida na Amazônia central brasileira. O crescimento dos fungos isolados foi feito em meio de cultura Ágar Batata Dextrose (BDA). Os isolados fúngicos foram transferidos para o meio sintético com Carboximetil celulose e utilizou-se vermelho Congo para determinar o índice enzimático. O halo de hidrólise, indicando a produção de celulases, foi observado em 175 isolados fúngicos (70% do total), dos quais 25 tiveram um índice enzimático ≥ 2,0 e pertencem a sete gêneros fúngicos. Os táxons fúngicos Cladosporium, Gliocephalotrichum, Penicillium, Pestalotiopsis, Talaromyces, Trichoderma e Umbelopsis foram isolados dos intestinos das larvas de Phylloicus, Triplectides e Stenochironomus e são tradicionalmente utilizados em aplicações biotecnológicas. Os resultados indicam um potencial celulolítco destes fungos associados ao intestino de insetos aquáticos amazônicos. (AU)

Antimicrobial activity of honeys from two stingless honeybee species and Apis mellifera (Hymenoptera: Apidae) against pathogenic microorganisms / Atividade antimicrobiana de méis de duas espécies de abelhas sem ferrão e Apis mellifera (Hymenoptera, Apidae) contra micro-organismos patogênicos

Honeys are described possessing different properties including antimicrobial. Many studies have presented this activity of honeys produced by Apis mellifera bees, however studies including activities of stingless bees honeys are scarce. The aim of this study was to compare the antimicrobial activity of honeys collected in the Amazonas State from Melipona compressipes, Melipona seminigra and Apis mellifera against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Chromobacterium violaceum, and Candida albicans. Minimum inhibitory concentrations were determined using the agar dilution method with Müller-Hinton agar (for bacteria) or Saboraud agar (for yeast). Staphylococcus aureus and E. faecalis were inhibited by all honeys at concentrations below 12%, while E. coli and C. violaceum were inhibited by stingless bee honeys at concentrations between 10 and 20%. A. mellifera honey inhibited E. coli at a concentration of 7% and Candida violaceum at 0.7%. C. albicans were inhibited only with honey concentrations between 30 and 40%. All examined honey had antimicrobial activity against the tested pathogens, thus serving as potential antimicrobial agents for several therapeutic approaches.

Méis são descritos possuindo diferentes propriedades, incluindo a antimicrobiana. Muitos estudos têm apresentado essa atividade de méis produzidos por abelhas Apis mellifera, no entanto estudos incluindo atividades de méis de abelhas sem ferrão são escassos. O objetivo deste estudo foi comparar a atividade antimicrobiana de méis de Melipona compressipes, Melipona seminigra e A. mellifera, coletados no Estado do Amazonas, contra Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Chromobacterium violaceum, e Candida albicans. As concentrações inibitórias mínimas foram determinadas usando o método de diluição em ágar, com ágar Muller-Hinton (para bactérias) ou ágar Sabouraud (para a levedura). S. aureus e E. faecalis foram inibidos por todos os méis em concentrações inferiores a 12%, enquanto E. coli e C. violaceum foram inibidos por méis de abelhas sem ferrão em altas concentrações entre 10 e 20%. A. mellifera inibiu E. coli na concentração de 7% e C. violaceum em baixa concentração (0,7%). C. albicans foi inibida apenas em concentrações entre 30 e 40% dos méis. Assim, todas as variedades de mel testadas apresentaram atividade antimicrobiana sobre os patógenos testados, servindo assim como agente antimicrobiano potencial para diversas abordagens terapêuticas.

The genome of Anopheles darlingi, the main neotropical malaria vector.

Anopheles darlingi is the principal neotropical malaria vector, responsible for more than a million cases of malaria per year on the American continent. Anopheles darlingi diverged from the African and Asian malaria vectors ∼100 million years ago (mya) and successfully adapted to the New World environment. Here we present an annotated reference A. darlingi genome, sequenced from a wild population of males and females collected in the Brazilian Amazon. A total of 10 481 predicted protein-coding genes were annotated, 72% of which have their closest counterpart in Anopheles gambiae and 21% have highest similarity with other mosquito species. In spite of a long period of divergent evolution, conserved gene synteny was observed between A. darlingi and A. gambiae. More than 10 million single nucleotide polymorphisms and short indels with potential use as genetic markers were identified. Transposable elements correspond to 2.3% of the A. darlingi genome. Genes associated with hematophagy, immunity and insecticide resistance, directly involved in vector-human and vector-parasite interactions, were identified and discussed. This study represents the first effort to sequence the genome of a neotropical malaria vector, and opens a new window through which we can contemplate the evolutionary history of anopheline mosquitoes. It also provides valuable information that may lead to novel strategies to reduce malaria transmission on the South American continent. The A. darlingi genome is accessible at www.labinfo.lncc.br/index.php/anopheles-darlingi.

Evidence for the evolutionary nascence of a novel sex determination pathway in honeybees.

Sex determination in honeybees (Apis mellifera) is governed by heterozygosity at a single locus harbouring the complementary sex determiner (csd) gene, in contrast to the well-studied sex chromosome system of Drosophila melanogaster. Bees heterozygous at csd are females, whereas homozygotes and hemizygotes (haploid individuals) are males. Although at least 15 different csd alleles are known among natural bee populations, the mechanisms linking allelic interactions to switching of the sexual development programme are still obscure. Here we report a new component of the sex-determining pathway in honeybees, encoded 12 kilobases upstream of csd. The gene feminizer (fem) is the ancestrally conserved progenitor gene from which csd arose and encodes an SR-type protein, harbouring an Arg/Ser-rich domain. Fem shares the same arrangement of Arg/Ser- and proline-rich-domain with the Drosophila principal sex-determining gene transformer (tra), but lacks conserved motifs except for a 30-amino-acid motif that Fem shares only with Tra of another fly, Ceratitis capitata. Like tra, the fem transcript is alternatively spliced. The male-specific splice variant contains a premature stop codon and yields no functional product, whereas the female-specific splice variant encodes the functional protein. We show that RNA interference (RNAi)-induced knockdowns of the female-specific fem splice variant result in male bees, indicating that the fem product is required for entire female development. Furthermore, RNAi-induced knockdowns of female allelic csd transcripts result in the male-specific fem splice variant, suggesting that the fem gene implements the switch of developmental pathways controlled by heterozygosity at csd. Comparative analysis of fem and csd coding sequences from five bee species indicates a recent origin of csd in the honeybee lineage from the fem progenitor and provides evidence for positive selection at csd accompanied by purifying selection at fem. The fem locus in bees uncovers gene duplication and positive selection as evolutionary mechanisms underlying the origin of a novel sex determination pathway.