Microsatellite marker-based assessment of the biodiversity of native bioethanol yeast strains.

Although many Brazilian sugar mills initiate the fermentation process by inoculating selected commercial Saccharomyces cerevisiae strains, the unsterile conditions of the industrial sugar cane ethanol fermentation process permit the constant entry of native yeast strains. Certain of those native strains are better adapted and tend to predominate over the initial strain, which may cause problems during fermentation. In the industrial fermentation process, yeast cells are often exposed to stressful environmental conditions, including prolonged cell recycling, ethanol toxicity and osmotic, oxidative or temperature stress. Little is known about these S. cerevisiae strains, although recent studies have demonstrated that heterogeneous genome architecture is exhibited by some selected well-adapted Brazilian indigenous yeast strains that display high performance in bioethanol fermentation. In this study, 11 microsatellite markers were used to assess the genetic diversity and population structure of the native autochthonous S. cerevisiae strains in various Brazilian sugar mills. The resulting multilocus data were used to build a similarity-based phenetic tree and to perform a Bayesian population structure analysis. The tree revealed the presence of great genetic diversity among the strains, which were arranged according to the place of origin and the collection year. The population structure analysis revealed genotypic differences among populations; in certain populations, these genotypic differences are combined to yield notably genotypically diverse individuals. The high yeast diversity observed among native S. cerevisiae strains provides new insights on the use of autochthonous high-fitness strains with industrial characteristics as starter cultures at bioethanol plants.

Detection and quantification of Duffy antigen on bovine red blood cell membranes using a polyclonal antibody / Detecção e quantificação do antigeno Duffy nos eritrócitos de bovinos empregando um anticorpo policlonal

Babesiosis is one of the most important diseases affecting livestock agriculture worldwide. Animals from the subspecies Bos taurus indicus are more resistant to babesiosis than those from Bos taurus taurus. The genera Babesia and Plasmodium are Apicomplexa hemoparasites and share features such as invasion of red blood cells (RBC). The glycoprotein Duffy is the only human erythrocyte receptor for Pasmodium vivax and a mutation which abolishes expression of this glycoprotein on erythrocyte surfaces is responsible for making the majority of people originating from the indigenous populations of West Africa resistant to P. vivax. The current work detected and quantified the Duffy antigen on Bos taurus indicus and Bos taurus taurus erythrocyte surfaces using a polyclonal antibody in order to investigate if differences in susceptibility to Babesia are due to different levels of Duffy antigen expression on the RBCs of these animals, as is known to be the case in human beings for interactions of Plasmodium vivax-Duffy antigen. ELISA tests showed that the antibody that was raised against Duffy antigens detected the presence of Duffy antigen in both subspecies and that the amount of this antigen on those erythrocyte membranes was similar. These results indicate that the greater resistance of B. taurus indicus to babesiosis cannot be explained by the absence or lower expression of Duffy antigen on RBC surfaces.

As doenças infecciosas e parasitárias causam perdas importantes em vários setores da produção da pecuária mundial. Estima-se que mais de 600 milhões de bovinos de países tropicais e subtropicais estejam expostos à infecção por Babesia sp. gerando grande prejuízo econômico. Os gêneros Babesia e Plasmodium são hemoparasitas pertencentes ao filo Apicomplexa e apresentam características comuns no processo de invasão eritrocitária. A babesiose bovina causada por Babesia bigemina e Babesia bovis apresenta sinais clínicos similares a malária humana causada por Plasmodium vivax e Plasmodium falciparum. A glicoproteína Duffy é a única receptora para o P. vivax em humanos. A maioria dos indivíduos negros africanos é resistente a este parasita devido a uma mutação que provoca a ausência de expressão desta glicoproteína na superfície das hemácias. Tendo em vista este fato, e que animais da subespécie Bos taurus taurus são mais susceptíveis à babesiose quando comparados à animais Bos taurus indicus, objetivou-se neste trabalho a detecção e quantificação do antígeno Duffy na superfície dos eritrócitos de bovinos empregando para tal, anticorpo policlonal que permitisse investigar se as diferenças na susceptibilidade são devido a diferentes níveis de expressão do antígeno Duffy nas hemácias. Ensaios de ELISA mostraram que o anticorpo produzido foi capaz de reconhecer o antígeno Duffy presente nas hemácias bovinas e a análise quantitativa não demonstrou diferença significativa na presença do mesmo. Estes resultados sugerem que a resistência maior dos zebuínos à babesiose não se deve à ausência de expressão, ou à presença em menor quantidade do antígeno Duffy na superfície de suas hemácias.