Photosynthetic generation of O2 and H2 by photosystem I-deficient chlamydomonas mutants

A comparative study of aerobic generation of O2 and anaerobic photoproduction of H2 in whole cells of a wild-type strain of Chlamydomonas reinhardtii and its photosystem I-deficient mutants B4 and F8 found no contribution of photosystem II to ferredoxin photoreduction, which is not consistent with data of recent studies by Greenbaum et al. (Nature, 1995, 376, 438-441; and Science, 1996, 273, 364-367) who reported that they had discovered such a capacity in these mutant strains. In the wild-type and mutant strains, action spectra showed that O2 was evolved by photosystem II, whereas photoinhibition of chlororespiration and evolution of H2 depended on the activity of photosystem I. Single-turnover flash measurements of H2 evolution showed that the contents of photosystem I in mutant strains amounted to 3-35% of that in the wild-type strain. This fraction of photosystem I in "leaky" mutants displayed abnormal kinetic features and was highly sensitive to photoinhibition.     

Application of beneficial rhizospheric microbes for the mitigation of seed-borne mycotoxigenic fungal infection and mycotoxins in maize

In the present investigation, seven rhizobacteria and nine Trichoderma spp. were evaluated to suppress seed-borne mycotoxigenic fungi (Aspergillus flavus and Fusarium verticillioides) and mycotoxin (aflatoxin and fumonisin) and to improve planting value of maize. Under in vitro conditions, these beneficial microorganisms suppressed the growth of A. flavus and F. verticillioides to various extents. Bacillus sp. (Bsp 3/aM), Pseudomonas putida (Has 1/c), Trichoderma asperellum (M5) and T. asperellum (T2) exhibited the greatest antagonistic effect on seed-borne mycotoxigenic fungi, and subsequently reduced mycotoxin concentrations in seeds. Under greenhouse conditions, these four biocontrol strains were also found to increase root length, shoot length, % germination, vigour index, fresh weight and dry weight of seedlings. Considering their overall performances, strains Bsp 3/aM, Has 1/c, M5 and T2 were selected for field studies as microbial talcum formulations. Among the tested microbial formulations, strain Bsp 3/aM significantly increased yield by 9.4% and 6.2% over the control in two maize cultivars Hema and Pearl, respectively. Increased plant growth and yield was also correlated with nutrient uptake in both the tested cultivars. All microbial formulation recorded significantly (p ≤ 0.05) reduced A. flavus infection and aflatoxin contamination in harvested seeds. But, none of the microbial formulations were found significant (p ≤ 0.05) in reducing F. verticilliodes incidence and fumonisin contamination. Our findings indicate that these microbial antagonists indirectly improve host health by suppressing seed-borne incidence of mycotoxigenic fungi and directly by facilitating nutrient uptake, thereby revealing their potential as both biofertilisers and biopesticides for maize production.     

Detection of two loci involved in (1-->3)-beta-glucan (curdlan) biosynthesis by Agrobacterium sp. ATCC31749, and comparative sequence analysis of the putative curdlan synthase gene

Genes essential for the production of a linear, bacterial (1-->3)-beta- glucan, curdlan, have been cloned for the first time from Agrobacterium sp. ATCC31749. The genes occurred in two, nonoverlapping, genomic fragments that complemented different sets of curdlan( crd )-deficient transposon-insertion mutations. These were detected as colonies that failed to stain with aniline blue, a (1-->3)-beta-glucan specific dye. One fragment carried a biosynthetic gene cluster (locus I) containing the putative curdlan synthase gene, crdS, and at least two other crd genes. The second fragment may contain only a single crd gene (locus II). Determination of the DNA sequence adjacent to several locus I mutations revealed homology to known sequences only in the cases of crdS mutations. Complete sequencing of the 1623 bp crdS gene revealed highest similarities between the predicted CrdS protein (540 amino acids) and glycosyl transferases with repetitive action patterns. These include bacterial cellulose synthases (and their homologs), which form (1-->4)-beta-glucans. No similarity was detected with putative (1-->3)- beta-glucan synthases from yeasts and filamentous fungi. Whatever the determinants of the linkage specificity of these beta-glucan synthases might be, these results raise the possibility that (1-->3)-beta-glucans and (1-->4)-beta-glucans are formed by related catalytic polypeptides.      

A state and transition model for the eastern Monte Phytogeographycal Province in Rio Negro

We developed a functional model for a shrub steppe vegetation of the eastern Monte Phytogeographical Province in Río Negro (Argentina) with six stable states and 12 transitions, based on the woody encroachment degree, characteristics of the herbaceous layer and the soil surface, and biological crust cover. Information was obtained from letters of naturalists and travelers along the region since the late eighteenth century, reports of old settlers, and our own research work. On the Monte, different functional groups can be distinguished. Our work focused on the three most conspicuous to analyze the dynamics of the system: shrubs, grasses and biological crust. The shrub layer is only affected by large-scale disturbances (fire, mechanical clearing) which maintain the balance between grasses and shrubs in the system. Mechanical clearing with soil removal also causes a decrease in grass cover and vegetation diversity. This layer, however, is most frequently affected by intensive and continuous grazing, which reduces the occurrence of fires and shifts the equilibrium toward the shrubs. All disturbances in general deteriorate the biological crust that covers the soil, which offers situations of facilitation for the regeneration of the herbaceous layer. Grazing and mechanical clearing reduce soil cover and promote the development of soil compaction, which reduce water infiltration and germination and/or seedling establishment, and this creates deteriorated states difficult to reverse. Those states can also be produced by tillage for agriculture and stubble grazing. Some of the transitions that we describe can be favored through grassland management strategies, in order to reach higher states of pastoral value and reverse deteriorating situations.     

A multi-population phenome-wide association study of genetically-predicted height in the Million Veteran Program

BackgroundHeight has been associated with many clinical traits but whether such associations are causal versus secondary to confounding remains unclear in many cases. To systematically examine this question, we performed a Mendelian Randomization-Phenome-wide association study (MR-PheWAS) using clinical and genetic data from a national healthcare system biobank.Methods and findingsAnalyses were performed using data from the US Veterans Affairs (VA) Million Veteran Program in non-Hispanic White (EA, n = 222,300) and non-Hispanic Black (AA, n = 58,151) adults in the US. We estimated height genetic risk based on 3290 height-associated variants from a recent European-ancestry genome-wide meta-analysis. We compared associations of measured and genetically-predicted height with phenome-wide traits derived from the VA electronic health record, adjusting for age, sex, and genetic principal components. We found 345 clinical traits associated with measured height in EA and an additional 17 in AA. Of these, 127 were associated with genetically-predicted height at phenome-wide significance in EA and 2 in AA. These associations were largely independent from body mass index. We confirmed several previously described MR associations between height and cardiovascular disease traits such as hypertension, hyperlipidemia, coronary heart disease (CHD), and atrial fibrillation, and further uncovered MR associations with venous circulatory disorders and peripheral neuropathy in the presence and absence of diabetes. As a number of traits associated with genetically-predicted height frequently co-occur with CHD, we evaluated effect modification by CHD status of genetically-predicted height associations with risk factors for and complications of CHD. We found modification of effects of MR associations by CHD status for atrial fibrillation/flutter but not for hypertension, hyperlipidemia, or venous circulatory disorders.ConclusionsWe conclude that height may be an unrecognized but biologically plausible risk factor for several common conditions in adults. However, more studies are needed to reliably exclude horizontal pleiotropy as a driving force behind at least some of the MR associations observed in this study.     

Neuronal protection by sirtuins in Alzheimer's disease

Silent information regulator 2, a member of NAD+-dependent histone deacetylase in yeast, and its homologs in mice and humans, participate in numerous important cell functions, including cell protection and cell cycle regulation. The sirtuin family members are highly conserved evolutionarily, and are predicted to have a role in cell survival. The science of sirtuins is an emerging field and is expected to contribute significantly to the role of sirtuins in healthy aging in humans. The role of sirtuins in neuronal protection has been studied in lower organisms, such as yeast, worms, flies and rodents. Both yeast Sir2 and mammalian sirtuin proteins are up-regulated under calorie-restricted and resveratrol treatments. Increased sirtuin expression protects cells from various insults. Caloric restriction and antioxidant treatments have shown useful effects in mouse models of aging and Alzheimer's disease (AD) and in limited human AD clinical trials. The role sirtuins may play in modifying and protecting neurons in patients with neurodegenerative diseases is still unknown. However, a recent report of Huntington's disease revealed that Sirtuin protects neurons in a Huntington's disease mouse model, suggesting that sirtuins may protect neurons in patients with neurodegenerative diseases, such as AD. In this review, we discuss the possible mechanisms of sirtuins involved in neuronal protection and the potential therapeutic value of sirtuins in healthy aging and AD.     

Methyl eugenol effects on Bactrocera dorsalis male total body protein,reproductive organs and ejaculate

Methyl eugenol (ME) and inclusion of protein into the adult diet increase the mating competitiveness of the Oriental fruit fly, Bactrocera dorsalis (Hendel). Exposing males to ME or protein is a promising post‐teneral treatment for males being released in the sterile insect technique (SIT). However, the effect of this post‐teneral treatment on male reproductive organs or the male ejaculate is unknown. During mating, males transfer sperm and accessory gland products (AGPs) to females and these compounds are reported to modulate female sexual inhibition. We studied the impact of male exposure to ME and a yeast hydrolysate (YH) diet on the protein reserves of males, male reproductive organ size, and the male ejaculate through sperm and AGPs. We show that males exposed to ME regardless of access to YH accumulated a greater amount of whole body protein. Males fed on YH also had increased total body protein and had bigger reproductive organs than YH‐deprived males, but no apparent effect of ME exposure was observed on reproductive organ size. Females stored less sperm when mated with males fed on YH and ME compared to males not fed on ME. YH and ME had no effect on male AGPs. Females injected with AGPs of males fed on YH and exposed to ME were just as likely to mate as females injected with AGPs of non‐treated males. However, females injected with AGPs of males exposed to ME mated faster than females injected with AGPs of non‐exposed males. We conclude that while exposure to ME increases male copulatory success and protein reserves in the male body, there seem to be some potential trade‐offs such as lower sperm stored by females. We discuss our results in terms of pre‐release protocols that may be used for B. dorsalis in SIT application.     

Novel acridinedione derivatives: design, synthesis, SIRT1 enzyme and tumor cell growth inhibition studies

A new scaffold N-(9-(ortho/meta/para-(benzyloxy)phenyl)-3,3,6,6-tetramethyl-1,8-dioxo-1,2,3,4,5,6,7,8-octahydroacridin-10(9H)-yl) isonicotinamide (H1-3) was discovered as a hSIRT1 inhibitor through virtual screening of in-house database. Based on these hits, a library of compounds were designed, synthesized and tested for in vitro hSIRT1 activity. The most potent compound 4d in the series showed a significant inhibition of SIRT1 activity. Further antitumor studies of compound 4d, showed a dose dependent increase in acetylation of p53K382 and decrease in SIRT1 with an IC₅₀ of 0.25 μM in MDA-MB231 breast cancer cell lines. Individual 3D-QSAR analysis using Schrödinger showed distribution of hydrophobic and non polar positive co-efficient at ortho position essential for bioactivity based on 4d.