RESUMEN

Cadmium (Cd) toxicity is a worldwide problem for crop production. The present work used hydroponic experiments to investigate the ameliorating effects and physiological mechanisms of glutathione (GSH) mitigation of Cd toxicity in cucumber seedlings. The results revealed that Cd was mainly accumulated in roots of cucumber, 100 µM GSH pretreatment in 50 µM Cd solution significantly recovered Cd-induced growth inhibition, improved photosynthetic and chlorophyll fluorescence performance. Moreover, external GSH obviously depressed hydroxyl free radical (·OH) and malondialdehyde accumulation, increased the total antioxidant capacity in cucumber exposed to Cd. Results indicated that pre-treatment of GSH can alleviate Cd toxicity by reducing Cd uptake and ROS accumulation, reduce the negative consequences of oxidative stress caused by Cd toxicity, moreover protect photosynthetic machinery from damaging, balance nutrients and antioxidants in cucumber.

A toxicidade do Cádmio (Cd) é um problema mundial para a produção de plantas olerícolas. O presente trabalho com o uso experimentos hidropônicos objetivou investigar a atenuação dos efeitos do cádmio por meio de mecanismos envolvendo a glutationa (GSH) e redução da toxicidade em plântulas de pepino submetidas ao Cd. OS resultados revelaram que o Cd acumulou principalmente nas raízes do pepino, Na dose de 100 µM GSH-50 esta reduziu a concentração em µM Cd na solução ea mesma melhora a ou reduz a inibição do crescimento ,bem como melhora o desempenho e a fluorescência clorofílica. Além disso, obviamente, radical Livre hidroxila GSH externa ·OH) aumenta a acumulação do malondialdeído e aumento da capacidade antioxidante total no pepino expostos ao Cd. OS resultados indicaram que o pré -tratamento de GSH pode reduzir a toxicidade, reduzindo a captação Cd e acumulação ROS , reduzir os efeitos negativos do stress oxidativo reduzindo a sua toxicidade, além de proteger o equilíbrio da disponibilidade de nutrientes e antioxidantes.

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RESUMEN

Chromosomal organization is sufficiently evolutionarily stable that large syntenic blocks of genes can be recognized even between species as distantly related as mammals and puffer fish (450 million years (Myr) of divergence). In Diptera, the gene content of the X chromosome and the autosomes is well conserved: in Drosophila more than 95% of the genes have remained on the same chromosome arm in the 12 sequenced species (63 Myr of divergence, traversing 400 Myr of evolution), and the same linkage groups are clearly recognizable in mosquito genomes (260 Myr of divergence). Here we investigate the conservation of Y-linked gene content among the 12 sequenced Drosophila species. We found that only a quarter of the Drosophila melanogaster Y-linked genes (3 out of 12) are Y-linked in all sequenced species, and that most of them (7 out of 12) were acquired less than 63 Myr ago. Hence, whereas the organization of other Drosophila chromosomes traces back to the common ancestor with mosquitoes, the gene content of the D. melanogaster Y chromosome is much younger. Gene losses are known to have an important role in the evolution of Y chromosomes, and we indeed found two such cases. However, the rate of gene gain in the Drosophila Y chromosomes investigated is 10.9 times higher than the rate of gene loss (95% confidence interval: 2.3-52.5), indicating a clear tendency of the Y chromosomes to increase in gene content. In contrast with the mammalian Y chromosome, gene gains have a prominent role in the evolution of the Drosophila Y chromosome.

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