Genomic characterization of Puccinia triticina using molecular marker technology / Caracterização genômica de Puccinia triticina usando tecnologia de marcadores moleculares

Leaf rust, caused by Puccinia triticina, is the most common rust disease of wheat. The fungus is an obligate parasite capable of producing infectious urediniospores. To study the genetic structure of the leaf rust population 20 RAPD primers were evaluated on 15 isolates samples collected in Pakistan. A total of 105 RAPD fragments were amplified with an average of 7 fragments per primer. The number of amplified fragments varied from 1 to 12. GL Decamer L-07 and GL Decamer L-01 amplified the highest number of bands (twelve) and primer GL Decamer A-03 amplified the lowest number of bands i.e one. Results showed that almost all investigated isolates were genetically different that confirms high genetic diversity within the leaf rust population. Rust spores can follow the migration pattern in short and long distances to neighbor areas. Results indicated that the greatest variability was revealed by 74.9% of genetic differentiation within leaf rust populations. These results suggested that each population was not completely identical and high gene flow has occurred among the leaf rust population of different areas. The highest differentiation and genetic distance among the Pakistani leaf rust populations were detected between the leaf rust population in NARC isolate (NARC-4) and AARI-11and the highest similarity was observed between NARC isolates (NARC-4) and (NARC-5). The present study showed the leaf rust population in Pakistan is highly dynamic and variable.

A ferrugem da folha, causada por Puccinia triticina, é a ferrugem mais comum do trigo. O fungo é um parasita obrigatório, capaz de produzir urediniósporos infecciosos. Para estudar a estrutura genética da população de ferrugem da folha, 20 primers RAPD foram avaliados em 15 amostras de isolados coletadas no Paquistão. Um total de 105 fragmentos RAPD foram amplificados com uma média de 7 fragmentos por primer. O número de fragmentos amplificados variou de 1 a 12. GL Decamer L-07 e GL Decamer L-01 amplificaram o maior número de bandas (doze), e o primer GL Decamer A-03 amplificou o menor número de bandas, ou seja, um. Os resultados mostraram que quase todos os isolados investigados eram geneticamente diferentes, o que confirma a alta diversidade genética na população de ferrugem da folha. Os esporos de ferrugem podem seguir o padrão de migração em distâncias curtas e longas para áreas vizinhas. Os resultados indicaram que a maior variabilidade foi revelada por 74,9% da diferenciação genética nas populações de ferrugem. Esses resultados sugeriram que cada população não era completamente idêntica e um alto fluxo gênico ocorreu entre a população de ferrugem da folha de diferentes áreas. A maior diferenciação e distância genética entre as populações de ferrugem da folha do Paquistão foram detectadas entre a população de ferrugem da folha no isolado NARC (NARC-4) e AARI-11 e a maior similaridade foi observada entre os isolados NARC (NARC-4) e (NARC-5). O presente estudo mostrou que a população de ferrugem da folha no Paquistão é altamente dinâmica e variável.

Presence of neutral fat in stool and its association with aetiology and presenting features of diarrhoea in children.

Enteric infections, impaired digestion, loss of villous cells, and poor absorption of fat may lead to presence of neutral fat in stool, particularly in children with diarrhoea. We aimed to examine the association between presence of neutral fat in stool and aetiology of diarrhoea and nutritional status of the patients at different age groups. A total of 13,171 patients aged 5 days-106 years enrolled in the Diarrhoeal Disease Surveillance System of the Dhaka Hospital of ICDDR,B during 1996-2001 were studied. Presence of neutral fat in faecal specimens, aetiology of diarrhoea, and nutritional status in children below 5 years of age were determined and analysed. Of the total study individuals, 7,671 (58%) had neutral fat in their faecal specimens. Neutral fat was more frequently present in faeces of individuals infected with rotavirus in all age groups or in enterotoxigenic E. coli (ETEC) infection in children 0-23 months old while compared with those who did not have these infections (p=0.005, p=0.014, respectively). Neutral fat was less frequently (p<0.001) present in malnourished 0-23 months old children. Presence of neutral fat in the stool in diarrhoea due to rotavirus and in young childhood ETEC diarrhoea signifies compromised gastrointestinal function due to these infections. The mechanism of persistence of neutral fat in the stool of such patients, and its nutritional and clinical implications require further studies.