Extracao de DNA Spiroplasma kunkelii Whitcomb cultivado in vitro.

2003

Interrelationship between two variants of the Circulifer tenellus complex and Spiroplasma citri: the causal agent of stubborn disease

Tese de Doutoramento, Ciências Naturais, Unidade de Ciências e Tecnologias Agrárias, Universidade do Algarve, 1992

Spiroplasma in Drosophila melanogaster Populations: Prevalence, Male-Killing, Molecular Identification, and No Association with Wolbachia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Spiroplasma in Drosophila melanogaster Populations: Prevalence, Male-Killing, Molecular Identification, and No Association with Wolbachia

Spiroplasma endosymbionts are maternally transmitted bacteria that may kill infected sons resulting in the production of female-biased broods. The prevalence of male killers varies considerably both between and within species. Here, we evaluate the spatial and temporal status of male-killing and non-male-killing Spiroplasma infection in three Brazilian populations of Drosophila melanogaster, nearly a decade after the first occurrence report for this species. The incidence of the male-killing Spiroplasma ranged from close to 0 to 17.7 % (so far the highest estimate for a Drosophila species) with a suggestion of temporal decline in a population. We also found non-male-killing Spiroplasma coexisting in one population at lower prevalence (3-5 %), and we did not detect it in the other two. This may be taken as a suggestion of a spreading advantage conferred by the male-killing strategy. Sequencing two loci, we identified the phylogenetic position of Spiroplasma strains from the three localities, showing that all strains group closely in the poulsonii clade. Due to intensive sampling effort, we were able to test the association between Spiroplasma infections and another widespread endosymbiont, Wolbachia, whose prevalence ranged from 81.8 to 100 %. The prevalence of Wolbachia did not differ between Spiroplasma-infected and uninfected strains in our largest sample nor were the prevalences of the two endosymbionts associated across localities.

Herança da resistência ao enfezamento em milho

Os objetivos deste trabalho foram determinar a herança da resistência ao complexo de enfezamento em milho e determinar as melhores fontes de resistência entre as linhagens estudadas. Foram realizadas as análises dialélica e médias de gerações em linhagens de milho. Para a análise dialélica, foram cruzadas 12 linhagens de milho, em dialélico parcial. Para análises de médias de gerações, foram cruzadas três linhagens resistentes e quatro suscetíveis, para a obtenção das gerações F1, F2, RCP R e RCP S. Os trabalhos foram conduzidos em Jaboticabal, SP. A incidência de enfezamento foi avaliada no estádio fenológico R3. Efeitos significativos quanto à capacidade geral de combinação e capacidade específica de combinação foram obtidos, o que indicou que, no controle do caráter enfezamentos, estão envolvidos tanto os efeitos aditivos quanto os de dominância. Análises de médias de gerações mostraram a presença de poucos genes envolvidos com o controle da resistência, com predominância de efeitos aditivos, o que permite a seleção de genótipos resistentes. As linhagens L02, L03 e L05 poderão ser utilizadas como fontes de resistência, em futuras combinações híbridas.

Herança da resistência ao complexo enfezamento em milho (Zea mays L.)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Diversidade e evolução na simbiose entre bactérias e formigas Attini

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Endosymbiotic bacteria in honey bees: Arsenophonus spp. are not transmitted transovarially

Intracellular endosymbiotic bacteria are common and can play a crucial role for insect pathology. Therefore, such bacteria could be a potential key to our understanding of major losses of Western honey bees (Apis mellifera) colonies. However, the transmission and potential effects of endosymbiotic bacteria in A. mellifera and other Apis spp. are poorly understood. Here, we explore the prevalence and transmission of the genera Arsenophonus, Wolbachia, Spiroplasma and Rickettsia in Apis spp. Colonies of A. mellifera (N = 33, with 20 eggs from worker brood cells and 100 adult workers each) as well as mated honey bee queens of A. cerana, A. dorsata and A. florea (N = 12 each) were screened using PCR. While Wolbachia, Spiroplasma and Rickettsia were not detected, Arsenophonus spp. were found in 24.2% of A. mellifera colonies and respective queens as well as in queens of A. dorsata (8.3%) and A. florea (8.3%), but not in A. cerana. The absence of Arsenophonus spp. from reproductive organs of A. mellifera queens and surface-sterilized eggs does not support transovarial vertical transmission. Instead, horizontal transmission is most likely.