Morpho-biometrical characterisation of Portuguese Bursaphelenchus xylophilus isolates with mucronate, digitate or round tailed females

Morpho-biometrical studies were conducted on 12 Bursaphelenchus xylophilus isolates collected from maritime pine, Pinus pinaster, in Portugal. The studies were carried out on 20 females and 20 males from each isolate. A wide variation in the female tails, from round, digitate to mucronate was detected in all isolates, confirming the occurrence of mucronate tails in some females of B. xylophilus. The presence of mucronate tailed females in the Portuguese isolates of B. xylophilus clearly makes the identification of B. xylophilus by this morphological character difficult since other non-pathogenic Bursaphelenchus species also have mucronate tailed females. Amplification of satellite DNA of single specimens using species-specific primers confirmed the identity of the mucronate tailed females in the Portuguese isolates as B. xylophilus. The satellite DNA technique was also useful in the identification of juveniles of B. xylophilus from P. pinaster wood samples

Biochemical and Molecular Characterization of Plant-Parasitic Nematodes

Nematologists need correct species identification to carry out research, teaching, extension and other activities. Therefore, nematode taxonomy must be pursued diligently at all levels. The identification of plant-parasitic nematodes is not always easy and that of some species is especially difficult. Most of the information that nematologists use when characterizing and identifying specimens is based on morphological and morphometrical characters. Although these characters are of primary importance, in the last three decades they have been supplemented by biochemical/ molecular characters. Biochemical approaches include the separation of proteins (general proteins and isozymes) by one-dimensional gel electrophoresis, isoelectric focusing, two-dimensional gel electrophoresis, and sodium dodecyl sulphate-capillary gel electrophoresis. Serology has also been found effective in the identification and quantification of nematodes, monoclonal antibodies being a more useful immunological tool than polyclonal antibodies. Identification based on the direct examination of DNA is potentially a more powerful method to characterize inter- and intra-specific variability. The development of techniques such as the polymerase chain reaction, restriction fragment length polymorphism, randomly amplified polymorphic DNA, and amplified fragment length polymorphism has increased the accuracy and speed of nematode characterization/identification. Progress continues to be made and more and more nematologists are using molecular techniques for diagnostic purposes and to assess genetic variation

Efeito do tamanho da presa e do acréscimo de ração na larvicultura de pacamã Effect of prey size selection and feeding on the larviculture of pacamã

Objetivou-se estudar o efeito do tamanho da presa, com ou sem adição de ração na larvicultura do pacamã (Lophiosilurus alexandri), espécie nativa da bacia do Rio São Francisco ameaçada de extinção. As larvas foram cultivadas em aquários por 16 dias e alimentadas com zooplâncton natural, selecionado em malhas de 650 e 1.300 µm, com ou sem ração. A oferta de zooplâncton de maior tamanho resultou em melhor desenvolvimento das larvas de pacamã, comprovando a vantagem do fornecimento de partículas alimentares maiores para o potencial de crescimento da espécie. O aumento na quantidade de ração não influenciou o desempenho das larvas, evidenciando a baixa ou falta de capacidade das larvas em digerir a ração ofertada. O fornecimento de ração diminuiu o pH e aumentou a condutividade elétrica, prejudicando a qualidade da água, o que não afetou o desempenho das larvas.<br>The effect of prey size selection and feeding on pacamã Lophiosilurus alexandri larvae culture (native specie of San Francisco basin classified as threatened of extinction) was evaluated. The larvae were cultivated in aquariums during 16 days and fed with natural zooplankton, screened in 650 and 1300 µm sieve, with and without ration. The offer of zooplankton of largest size provided a better development of the pacamã larvae, demonstrating the need of alimentary particles larger for the growth potential of the species. The increase of the amount of ration did not affect the performance of the larvae, evidencing low or lack of capacity in digesting the offered ration. The ration fed reduced the pH and increased the electric conductivity, worsening water quality, which did not affect the performance of the larvae