Osmoconditioning prevents the onset of microtubular cytoskeleton and activation of cell cycle and is detrimental for germination of Jatropha curcas L. seeds.

Jatropha curcas is an oilseed crop renowned for its tolerance to a diverse range of environmental stresses. In Brazil, this species is grown in semiarid regions where crop establishment requires a better understanding of the mechanisms underlying appropriate seed, seedling and plant behaviour under water restriction conditions. In this context, the objective of this study was to investigate the physiological and cytological profiles of J. curcas seeds in response to imbibition in water (control) and in polyethylene glycol solution (osmoticum). Seed germinability and reactivation of cell cycle events were assessed by means of different germination parameters and immunohistochemical detection of tubulin and microtubules, i.e. tubulin accumulation and microtubular cytoskeleton configurations in water imbibed seeds (control) and in seeds imbibed in the osmoticum. Immunohistochemical analysis revealed increasing accumulation of tubulin and appearance of microtubular cytoskeleton in seed embryo radicles imbibed in water from 48 h onwards. Mitotic microtubules were only visible in seeds imbibed in water, after radicle protrusion, as an indication of cell cycle reactivation and cell proliferation, with subsequent root development. Imbibition in osmoticum prevented accumulation of microtubules, i.e. activation of cell cycle, therefore germination could not be resumed. Osmoconditioned seeds were able to survive re-drying and could resume germination after re-imbibition in water, however, with lower germination performance, possibly due to acquisition of secondary dormancy. This study provides important insights into understanding of the physiological aspects of J. curcas seed germination in response to water restriction conditions.

The association between the HLA-G 14-bp insertion/deletion polymorphism and type 1 diabetes.

Type 1 diabetes (T1D) is a multifactorial disease that has a strong genetic component. The HLA-G is a nonclassical HLA class I locus that is associated with immunomodulatory functions, including downregulation of innate and adaptive immune responses and induction of immune tolerance. However, there is currently limited information about the involvement of HLA-G in T1D susceptibility. This case-control study aims to investigate the T1D susceptibility association of alleles and genotypes of a widely investigated 14-bp insertion/deletion polymorphism in the HLA-G and to provide further evidence of the frequency distribution of class II HLA-DR-DQ-risk genotypes in T1D children and adolescents in the Brazilian population. The deletion allele and the homozygous deletion genotype are associated with susceptibility to T1D and the insertion allele and the heterozygous deletion/insertion genotype are associated with protection from T1D. We also confirm that genetic susceptibility to T1D is associated with the DRB1*03:01-DQA1*05:01-DQB1*02:01 and DRB1*04-DQA1*03:01-DQB1*03:02 haplotypes in Brazilian northeast region. The DR3-DQ2/DR4-DQ8 genotype conferred the highest detected risk for T1D. Our results identify a novel association of the 14-bp deletion allele and the homozygous deletion genotype with T1D development and provide additional evidence of the importance of HLA class II heterozygous DR3-DQ2/DR4-DQ8 genotype in T1D susceptibility.