Improved embryoid induction and green shoot regeneration from wheat anthers cultured in medium with maltose

Summary Anthers from spring wheat (Triticum aestivum L.) genotypes, including six F₁ hybrids, were cultured in a modified liquid N6 medium containing either sucrose or maltose. In every case, use of maltose resulted in greater microspore callus induction and green shoot regeneration than culture in sucrose-containing medium. Induction in maltose medium also allowed green shoots to be recovered from crosses that showed only a poor response in other media and from two genotypes that did not respond to modified N6 medium with sucrose. Replacement of sucrose with maltose generally resulted in microspores having a more embryogenic mode of development in which distinct embryoids often formed. The most responsive genotype produced over 200 green shoots/100 anthers when cultured in medium with maltose.NRCC publication no. 31494     

Regeneration of plantlets from in vitro cultured cotyledons of white spruce (Picea glauca (Moench) Voss)

Adventitious shoot production from seedling cotyledons was investigated for white spruce [Picea glauca (Moench) Voss]. The age of the seedling was found to be important for shoot induction response, the optimum seedling age being 7 to 8 days old. Prior to that age, although response was seen, the multiplication rate was lower. After 7 to 8 days, the capacity to produce shoots declined considerably. The optimum cytokinin (BA) concentration for bud induction was 2 M BA. The response to specific BA concentrations was independent of seedling age. The shoot regeneration presented here was highly reproducible and provided primary multiplication rates of approximately 100 to 150 shoots per seedling which had an average of 6 cotyledons. Approximately 30% of 40 regenerated shoots were induced to differentiate roots and all the rooted plantlets were successfully transplanted to soil.Abbreviations BA Benzyladenine - IBA indole-3-butyric acid. NRCC No. 29142     

The JmjN Domain of Jhd2 Is Important for Its Protein Stability,and the Plant Homeodomain (PHD) Finger Mediates Its Chromatin Association Independent of H3K4 Methylation

Histone lysine methylation is a dynamic process that plays an important role in regulating chromatin structure and gene expression. Recent studies have identified Jhd2, a JmjC domain-containing protein, as an H3K4-specific demethylase in budding yeast. However, important questions regarding the regulation and functions of Jhd2 remain unanswered. In this study, we show that Jhd2 has intrinsic activity to remove all three states of H3K4 methylation in vivo and can dynamically associate with chromatin to modulate H3K4 methylation levels on both active and repressed genes and at the telomeric regions. We found that the plant homeodomain (PHD) finger of Jhd2 is important for its chromatin association in vivo. However, this association is not dependent on H3K4 methylation and the H3 N-terminal tail, suggesting the presence of an alternative mechanism by which Jhd2 binds nucleosomes. We also provide evidence that the JmjN domain and its interaction with the JmjC catalytic domain are important for Jhd2 function and that Not4 (an E3 ligase) monitors the structural integrity of this interdomain interaction to maintain the overall protein levels of Jhd2. We show that the S451R mutation in human SMCX (a homolog of Jhd2), which has been linked to mental retardation, and the homologous T359R mutation in Jhd2 affect the protein stability of both of these proteins. Therefore, our findings provide a mechanistic explanation for the observed defects in patients harboring this SMCX mutant and suggest the presence of a conserved pathway involving Not4 that modulates the protein stability of both yeast Jhd2 and human SMCX.     

Seizure induces activation of multiple subtypes of neural progenitors and growth factors in hippocampus with neuronal maturation confined to dentate gyrus

Adult hippocampal neurogenesis is altered in response to different physiological and pathological stimuli. GFAP^+ve/nestin^+ve radial glial like Type-1 progenitors are considered to be the resident stem cell population in adult hippocampus. During neurogenesis these Type-1 progenitors matures to GFAP^−ve/nestin^+ve Type-2 progenitors and then to Type-3 neuroblasts and finally differentiates into granule cell neurons. In our study, using pilocarpine-induced seizure model, we showed that seizure initiated activation of multiple progenitors in the entire hippocampal area such as DG, CA1 and CA3. Seizure induction resulted in activation of two subtypes of Type-1 progenitors, Type-1a (GFAP^+ve/nestin^+ve/BrdU^+ve) and Type-1b (GFAP^+ve/nestin^+ve/BrdU^−ve). We showed that majority of Type-1b progenitors were undergoing only a transition from a state of dormancy to activated form immediately after seizures rather than proliferating, whereas Type-1a showed maximum proliferation by 3 days post-seizure induction. Type-2 (GFAP^−ve/nestin^+ve/BrdU^+ve) progenitors were few compared to Type-1. Type-3 (DCX^+ve) progenitors showed increased expression of immature neurons only in DG region by 3 days after seizure induction indicating maturation of progenitors happens only in microenvironment of DG even though progenitors are activated in CA1 and CA3 regions of hippocampus. Also parallel increase in growth factors expression after seizure induction suggests that microenvironmental niche has a profound effect on stimulation of adult neural progenitors.     

Contrasting reactivity of thioglucoside and selenoglucoside donors towards promoters: implications for glycosylation stereocontrol

The stereochemical outcome of glycosylation reactions with model thioglycosides and selenoglycosides proved to be dependent on the source of promoter iodonium ion, with iodine giving different results to N-iodosuccinimide (NIS) alone or N-iodosuccinimide/trimethylsilyltrifluoromethanesulfonate (NIS/TMSOTf). In contrast to armed thioglycosides, which anomerise, and disarmed thioglycosides, which do not react, both armed and disarmed selenoglycosides give rise to the corresponding glycosyl iodides when reacted with iodine. Further, whilst the single electron transfer agent DDQ alone is an ineffective promoter, in combination with iodine it produces better acetonitrile-assisted beta-stereoselectivity with both thioglycosides and selenoglycosides than does tris(4-bromophenyl)aminium hexachloroantimonate (BAHA).     

Quercetin improves oxidative stress-induced pancreatic beta cell alterations via mTOR-signaling

Molecular and Cellular Biochemistry - Citrus flavonoids particularly quercetin which is abundant in grapefruit, onion, green tea, berries etc. are known to have a protective effect on oxidative...     

DNA Methyl Transferase (DNMT) Gene Polymorphisms Could Be a Primary Event in Epigenetic Susceptibility to Schizophrenia

DNA methylation has been implicated in the etiopathology of various complex disorders. DNA methyltransferases are involved in maintaining and establishing new methylation patterns. The aim of the present study was to investigate the inherent genetic variations within DNA methyltransferase genes in predisposing to susceptibility to schizophrenia. We screened for polymorphisms in DNA methyltransferases, DNMT1, DNMT3A, DNMT3B and DNMT3L in 330 schizophrenia patients and 302 healthy controls for association with Schizophrenia in south Indian population. These polymorphisms were also tested for subgroup analysis with patient''s gender, age of onset and family history. DNMT1 rs2114724 (genotype P = .004, allele P = 0.022) and rs2228611 (genotype P = 0.004, allele P = 0.022) were found to be significantly associated at genotypic and allelic level with Schizophrenia in South Indian population. DNMT3B rs2424932 genotype (P = 0.023) and allele (P = 0.0063) increased the risk of developing schizophrenia in males but not in females. DNMT3B rs1569686 (genotype P = 0.027, allele P = 0.033) was found to be associated with early onset of schizophrenia and also with family history and early onset (genotype P = 0.009). DNMT3L rs2070565 (genotype P = 0.007, allele P = 0.0026) confers an increased risk of developing schizophrenia at an early age in individuals with family history. In-silico prediction indicated functional relevance of these SNPs in regulating the gene. These observations might be crucial in addressing and understanding the genetic control of methylation level differences from ethnic viewpoint. Functional significance of genotype variations within the DNMTs indeed suggest that the genetic nature of methyltransferases should be considered while addressing epigenetic events mediated by methylation in Schizophrenia.