Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness

Infection induced defence responses in sorghum, with special emphasis on accumulation of reactive oxygen species and cell wall modifications

Hemibiotrophic plant pathogens pass both biotrophic and necrotrophic phases during their infection cycle. Colletotrichum spp. exhibits two types of hemibiotrophy, i.e. intracellular and subcuticular intramural. Colletotrichum sublineolum infecting sorghum exhibits a typical intracellular type of hemibiotrophy. During the biotrophic stage of C. sublineolum infection in sorghum, several cell wall-associated defence reactions are activated and efficiently participate in stopping pathogen development. Among these defence reactions, generation and accumulation of reactive oxygen species (ROS) and cell wall barrier formation are key factors in resistance. This review focuses on the infection processes of C. sublineolum in sorghum and the defence responses activated, with special emphasis on accumulation of ROS and hydroxy-rich glyco-proteins (HRGPs)

A sesquiterpene synthase from the endophytic fungus <i>Serendipita indica</i> catalyzes formation of viridiflorol

Interactions between plant-associated fungi and their hosts are characterized by a continuous crosstalk of chemical molecules. Specialized metabolites are often produced during these associations and play important roles in the symbiosis between the plant and the fungus, as well as in the establishment of additional interactions between the symbionts and other organisms present in the niche. Serendipita indica, a root endophytic fungus from the phylum Basidiomycota, is able to colonize a wide range of plant species, conferring many benefits to its hosts. The genome of S. indica possesses only few genes predicted to be involved in specialized metabolite biosynthesis, including a putative terpenoid synthase gene (SiTPS). In our experimental setup, SiTPS expression was upregulated when the fungus colonized tomato roots compared to its expression in fungal biomass growing on synthetic medium. Heterologous expression of SiTPS in Escherichia coli showed that the produced protein catalyzes the synthesis of a few sesquiterpenoids, with the alcohol viridiflorol being the main product. To investigate the role of SiTPS in the plant-endophyte interaction, an SiTPS-over-expressing mutant line was created and assessed for its ability to colonize tomato roots. Although overexpression of SiTPS did not lead to improved fungal colonization ability, an in vitro growth-inhibition assay showed that viridiflorol has antifungal properties. Addition of viridiflorol to the culture medium inhibited the germination of spores from a phytopathogenic fungus, indicating that SiTPS and its products could provide S. indica with a competitive advantage over other plant-associated fungi during root colonization

Infection induced oxidative cross-linking of hydroxyproline-rich glycoproteins (HRGPs) is associated with restriction of <i>Colletotrichum sublineolum</i> in sorghum

Hydroxyproline-rich glycoproteins (HRGPs) accumulation and oxidative cross-linking is one of the earliest defense responses in plants against pathogen infection. In the present study HRGP accumulation in three sorghum genotypes i.e. SC146 (resistant), cv. SC326 (intermediately resistant) and BTx623 (susceptible) as a response to Colletotrichum sublineolum isolate CP2126 infection is elucidated. HRGPs were monitored by hydroxyproline (Hyp) estimation. In genotypes SC146 and genotypes SC326 there was a significantly higher amounts of Hyp at 2 days after inoculation (dai) compared to genotype BTx623, indicating an infection induced accumulation of HRGPs. Western blot analysis of acid-ethanol extracted proteins with polyclonal antibody raised against pearl millet purified HRGPs identified four bands with molecular masses of ~65, 45, 17 and 14 kDa as HRGPs. Insolubilization of the 45 kDa protein in genotypes SC146 and SC326 upon infection with C. sublineolum indicates a role of this protein in cell wall cross-linking, coinciding with heavier accumulation of hydrogen peroxide. In addition, tissue print analysis using polyclonal antibody of pearl millet HRGPs recognized these cross-linked proteins to be HRGPs. These findings indicated that HRGPs in sorghum is a component of defense reaction against C. sublineolum infection

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness