Effects of sodium nitroprusside and growth regulators on callus,multiple shoot induction and tissue browning in commercially important Valeriana jatamansi Jones

Plant Cell, Tissue and Organ Culture (PCTOC) - The effects of nitric oxide (NO) donor sodium nitroprusside (SNP) and various growth regulators on callus induction and shoot organogenesis in the...     

Deciphering sulfoglycolipids of Mycobacterium tuberculosis

For 4 decades, in vivo and in vitro studies have suggested that sulfoglycolipids (SGLs) play a role in the virulence or pathogenesis of the tubercle bacilli. However, the SGL structure and biosynthesis pathway remain only partially elucidated. Using the modern tools of structural analysis, including MALDI-time-of-flight MS, MS/MS, and two-dimensional NMR, we reevaluated the structure of the different SGL acyl (di-, tri-, and tetra-acylated) forms of the reference strain Mycobacterium tuberculosis H37Rv, as well as those produced by the mmpL8 knockout strains previously described to intracellularly accumulate di-acylated SGL. We report here the identification of new acyl forms: di-acylated SGL esterified by simple fatty acids only, as well as mono-acylated SGL bearing a hydroxyphthioceranoic acid, which were characterized in the wild-type strain. In a clinical strain, a complete family of mono-acylated SGLs was characterized in high abundance for the first time. For the mmpL8 mutant, SGLs were found to be esterified i) by an oxophthioceranoic acid, never observed so far, and ii) at nonconventional positions in the case of the unexpected tri-acylated forms. Our results further confirm the requirement of MmpL8 for the complete assembly of the tetra-acylated forms of SGL and also provide, by the discovery of new intermediates, insights in terms of the possible SGL biosynthetic pathways.     

Epidemiology of sudden cardiac death in rural South India - insights from the andhra pradesh rural health initiative

Background

Sudden cardiac death (SCD) is a common initial presentation of coronary artery disease (CAD). Despite the growing epidemic of CAD in India, the epidemiology of SCD is largely unknown.

Objective

The objective of the study was to define the prevalence and determinants of sudden cardiac deaths in rural South India.

Methods

Prospective mortality surveillance was conducted in 45 villages (180,162 subjects) in rural South India between January 2006 and October 2007. Trained multipurpose health workers sought to do verbal autopsies within 4 weeks of any death. Detailed questionnaires including comorbidities and circumstances surrounding death were recorded. SCD was adjudicated using the modified Hinkle-Thaler classification.

Results

A total of 1916 deaths occurred in the study population over the 22 month time period and verbal autopsy was obtained in 1827 (95%) subjects. Overall mean age of the deceased was 62 ± 20 years and 1007 (55%) were men. Cardiovascular and cerebrovascular diseases together accounted for 559 deaths (31%), followed by infectious disease (163 deaths, 9%), cancer (126 deaths, 7%) and suicide (93 deaths, 5%).Of the 1827 deaths, after excluding accidental deaths (89 deaths), 309 deaths (17%) met criteria for SCD. Cardiovascular disease was the underlying causes in the majority of the SCD events (231/309 (75%)). On multivariate analyses, previous MI/CAD (p < 0.001, OR 14.25), hypertension (p < 0.001, OR 1.84), and age groups between 40-60 yrs (p=0.029) were significantly associated with SCD.

Conclusion

Sudden cardiac death accounted for up to half of the cardiovascular deaths in rural Southern India. Traditional cardiovascular risk factors were strongly associated with SCD.     

In vitro antioxidant studies in leaves of Annona species

Antioxidant potential of leaves of three different species of Annona was studied by using different in vitro models eg., 1,1-diphenyl-2-picryl hydrazyl (DPPH), 2,2-azinobis-(3-ethylbenzothizoline-6-sulphonate) (ABTS), nitric oxide, superoxide, hydroxy radical and lipid peroxidation. The ethanolic extract of A. muricata at 500 microg/ml showed maximum scavenging activity (90.05%) of ABTS radical cation followed by the scavenging of hydroxyl radical (85.88%) and nitric oxide (72.60%) at the same concentration. However, the extract showed only moderate lipid peroxidation inhibition activity. In contrast, the extract of A. reticulata showed better activity in quenching DPPH (89.37%) and superoxide radical (80.88%) respectively. A.squamosa extract exhibited least inhibition in all in vitro antioxidant models excepting hydroxyl radical (79.79%). These findings suggest that the extracts of A. muricata possess potent in vitro antioxidant activity as compared to leaves of A. squamosa and A. reticulata suggesting its role as an effective free radical scavenger, augmenting its therapeutic     

Identification of nascent chain interaction sites on trigger factor

The role of ribosome-binding molecular chaperones in protein folding is not yet well understood. Trigger factor (TF) is the first chaperone to interact with nascent polypeptides as they emerge from the bacterial ribosome. It binds to the ribosome as a monomer but forms dimers in free solution. Based on recent crystal structures, TF has an elongated shape, with the peptidyl-prolyl-cis/trans-isomerase (PPIase) domain and the N-terminal ribosome binding domain positioned at opposite ends of the molecule and the C-terminal domain, which forms two arms, positioned in between. By using site specifically labeled TF proteins, we have demonstrated that all three domains of TF interact with nascent chains during translation. Interactions with the PPIase domain were length-dependent but independent of PPIase activity. Interestingly, with free TF, these same sites were found to be involved in forming the dimer interface, suggesting that dimerization partially occludes TF-nascent chain binding sites. Our data indicate the existence of two regions on TF along which nascent chains can interact, the NC-domains as the main site and the PPIase domain as an auxiliary site.     

A LuxP-FRET-based reporter for the detection and quantification of AI-2 bacterial quorum-sensing signal compounds

Various bacterial species produce and monitor low-molecular weight signaling molecules that regulate specific sets of genes in a population density-dependent manner. This process is known as quorum sensing (QS). To date, the detection of QS signaling molecules from Gram-negative bacteria has relied primarily on bacterial reporter strains. These bioassays are subject to substantial interference by compounds that affect the growth and metabolism of the reporter strains. In addition, the sensitivity of reporter strains to QS signaling molecules is population density-dependent. Here, we describe the development of an in vitro assay system for the rapid detection and quantification of the furanosyl borate diester (BAI-2) subclass of autoinducer 2 (AI-2), QS molecules. The sensor is based on ligand binding-induced changes in fluorescence resonance energy transfer (FRET) between a cyan and yellow variant of GFP fused to the termini of the BAI-2 receptor, LuxP. Unexpectedly, the addition of synthetic BAI-2 to the purified biosensor induces a decrease in the level of FRET between the terminal fluorophores. Several lines of evidence, including mutation of the ligand binding sites, indicate that the observed FRET changes are BAI-2-dependent. The FRET-based BAI-2 biosensor responded to the addition of culture filtrates from wild-type Vibrio harveyi but exhibited no response to culture filtrates from V. harveyi mutants defective in BAI-2 synthesis. The sensitivity of the biosensor to BAI-2 (apparent Kd = 270 nM) was similar to that of BAI-2 bioassay systems. The limitations of microbial bioassay systems and the advantages and potential applications for the FRET-based BAI-2 biosensor are discussed.