Bacterial Virulence Factors: Secreted for Survival

Virulence is described as an ability of an organism to infect the host and cause a disease. Virulence factors are the molecules that assist the bacterium colonize the host at the cellular level. These factors are either secretory, membrane associated or cytosolic in nature. The cytosolic factors facilitate the bacterium to undergo quick adaptive—metabolic, physiological and morphological shifts. The membrane associated virulence factors aid the bacterium in adhesion and evasion of the host cell. The secretory factors are important components of bacterial armoury which help the bacterium wade through the innate and adaptive immune response mounted within the host. In extracellular pathogens, the secretory virulence factors act synergistically to kill the host cells. In this review, we revisit the role of some of the secreted virulence factors of two human pathogens: Mycobacterium tuberculosis—an intracellular pathogen and Bacillus anthracis—an extracellular pathogen. The advances in research on the role of secretory factors of these pathogens during infection are discussed.     

Statistical optimization of growth media for Paecilomyces lilacinus 6029 using non-edible oil cakes

The development of biofriendly and economical alternatives to chemical pesticides is a globally important scientific challenge. In this work, Karanja-based media conditions were optimized for obtaining high production of biomass and spores of a biocontrol agent, the entomopathogenic fungus Paecilomyces lilacinus 6029, using a two-step statistical approach coupled with rigorous experimentation. In the first step, non-edible Karanja cake was screened out as a major substrate from other oil cakes. In the second step, biomass production was maximized by applying response surface methodology to experimental variations in key physico-chemical factors: carbon/nitrogen (C/N) ratio and pH. This approach eventually predicted a maximum biomass production of 10.559 g/l with a medium having a C/N ratio of 35.88 and pH 5.9. An experimental production of 10.529 g/l biomass was obtained. The remarkable agreement between the predicted and the experimentally obtained biomass confirm the validity of the approach utilized to maximize production of P. lilacinus.     

No Correlation between TIMP2 -418 G>C Polymorphism and Increased Risk of Cancer: Evidence from a Meta-Analysis

Aim

Tissue inhibitor of metalloproteinase (TIMP2) is involved in the regulation of matrix metalloproteinase 2 (MMP2) and shown to implicate in cancer development and progression. The results from the published studies based on the association between TIMP2 -418 G>C polymorphism and cancer risk are inconsistent. In this meta-analysis, we aimed to evaluate the potential association between TIMP2 -418 G>C polymorphism and cancer risk.

Methodology

We searched PubMed (Medline) and EMBASE web databases to cover all studies based on relationship of TIMP2 -418 G>C polymorphism and risk of cancer until October 2013. The meta-analysis was performed for selected case-control studies and pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for all genetic models.

Results

A total of 2225 cancer cases and 2532 controls were included from ten eligible case-control studies. Results from overall pooled analysis suggested no evidence of significant risk between TIMP2 -418 G>C polymorphism and cancer risk in any of the genetic models, such as, allele (C vs. G: OR = 1.293, 95% CI = 0.882 to 1.894, p = 0.188), homozygous (CC vs. GG: OR = 0.940, 95% CI = 0.434 to 2.039, p = 0.876), heterozygous (GC vs. GG: OR = 1.397, 95% CI = 0.888 to 2.198, p = 0.148), dominant (CC+GC vs. GG: OR = 1.387, 95% CI = 0.880 to 2.187, p = 0.159) and recessive (CC vs. GG+GC: OR = 0.901, 95% CI = 0.442 to 1.838, p = 0.774) models. No evidence of publication bias was detected during the analysis.

Conclusions

The present meta-analysis suggests that the TIMP2 -418 G>C polymorphism may not be involved in predisposing risk factor for cancer in overall population. However, future larger studies with group of populations are needed to analyze the possible correlation.     

Improved Heterojunction Quality in Cu2O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited Zn1-xMgxO

Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn_1-xMg_xO thin films onto p-type thermally oxidized Cu₂O substrates outside vacuum at low temperature. The performance of photovoltaic devices featuring atmospherically fabricated ZnO/Cu₂O heterojunction was dependent on the conditions of AP-SALD film deposition, namely, the substrate temperature and deposition time, as well as on the Cu₂O substrate exposure to oxidizing agents prior to and during the ZnO deposition. Superficial Cu₂O to CuO oxidation was identified as a limiting factor to heterojunction quality due to recombination at the ZnO/Cu₂O interface. Optimization of AP-SALD conditions as well as keeping Cu₂O away from air and moisture in order to minimize Cu₂O surface oxidation led to improved device performance. A three-fold increase in the open-circuit voltage (up to 0.65 V) and a two-fold increase in the short-circuit current density produced solar cells with a record 2.2% power conversion efficiency (PCE). This PCE is the highest reported for a Zn_1-xMg_xO/Cu₂O heterojunction formed outside vacuum, which highlights atmospheric pressure spatial ALD as a promising technique for inexpensive and scalable fabrication of Cu₂O-based photovoltaics.     

Biotransformation of Acetamide to Acetohydroxamic Acid at Bench Scale Using Acyl Transferase Activity of Amidase of <Emphasis Type="Italic">Geobacillus pallidus</Emphasis> BTP-5x MTCC 9225

The bioprocess employing acyl transferase activity of intracellular amidase of Geobacillus pallidus BTP-5x MTCC 9225 was harnessed for the synthesis of pharmaceutically important acetohydroxamic acid. G. pallidus BTP-5x exhibited highest acyl transferase activity with acetamide: hydroxylamine in ratio of 1:5 in 0.1 M NaH₂PO₄/Na₂HPO₄ buffer (pH 7.5) at 65°C. In one liter fed-batch reaction containing 1:5 ratio of two substrates total of eight feedings of 0.05 M/20 min of acetamide were made and it was found that maximum acetohydroxamic production was achieved at 3:5 ratios of substrate and cosubstrate. In 1 l bench scale batch reaction containing 0.3 M acetamide, 0.5 M hydroxylamine in 0.1 M NaH₂PO₄/Na₂HPO₄ buffer (pH 7.5, 50°C, 400 rpm) and 0.5 mg/ml (dry cell weight) of whole cells of G. pallidus BTP-5x (as biocatalyst) resulted in an yield of 0.28 M of acetohydroxamic acid after 20 min reaction time at 50°C. The acetamide bioconversion rate was 90–95% (mol mol⁻¹) and 51 g powder containing 40% (w/w) acetohydroxamic acid was recovered after lyophilization.     

Extracting Curvature Preferences of Lipids Assembled in Flat Bilayers Shows Possible Kinetic Windows for Genesis of Bilayer Asymmetry and Domain Formation in Biological Membranes

Studies on the assembly of pure lipid components allow mechanistic insights toward understanding the structural and functional aspects of biological membranes. Molecular dynamic (MD) simulations on membrane systems provide molecular details on membrane dynamics that are difficult to obtain experimentally. A large number of MD studies have remained somewhat disconnected from a key concept of amphipathic assembly resulting in membrane structures—shape parameters of lipid molecules in those structures in aqueous environments. This is because most of the MD studies have been done on flat lipid membranes. With the above in view, we analyzed MD simulations of 26 pure lipid patches as a function of (1) lipid type(s) and (2) time of MD simulations along with 35–40 ns trajectories of five pure lipids. We report, for the first time, extraction of curvature preferences of lipids from MD simulations done on flat bilayers. Our results may lead to mechanistic insights into the possible origins of bilayer asymmetries and domain formation in biological membranes.     

Occipital hair whorl as a racial criterion: a critical assessment

Reports on the incidence of single clockwise occipital whorls as opposed to double and counterclockwise whorls reveal no consistent geographical pattern. Earlier workers arrived at different conclusions. While Bernstein ('25b) and Schwartzburg ('27) suggested a dominant inheritance of counter-clockwise whorls, others like Winchester ('58) and Montagu ('63) believed the clockwise condition to be dominant. In the light of these and some other studies, Scheinfeld's ('56) remarks that chance factor in prenatal development may influence dominance, seem appropriate. The results of present study indicate that clockwise and anti-clockwise conditions show inconsistent variation which may be the result of change element rather than any specific mode of distribution. Two groups from India: 164 Pandits of Kashmir, pre-dominantly Caucasian and 95 Tibetan refugees, predominantly Mongoloid are contrasted. The incidence of a single clockwise whorl among Pandits is 67%, whereas among Tibetans it is 78%. A review of other populations studied shows greater variance within than between the so-called major racial stocks.     

Mechanism of action of aflatoxin B1 in Bacillus megaterium

Bacillus megaterium cells from various growth phases were equally susceptible to the lethal effects of aflatoxin B1. Known surfactants (EDTA and Tween-80) accentuated the effects of aflatoxin B1. Viability and inulin uptake in aflatoxin B1-exposed cells decreased considerably. The effect was concentration dependent. A straight-line relationship observed in the death curve indicated a single target for aflatoxin B1 action in B. megaterium. Leakage of intracellular constituents in B. megaterium was also concentration dependent, and this can be related to the extent of cell membrane damage.     

Responses of <Emphasis Type="Italic">Zea mays</Emphasis> L. cultivars ‘Buland’ and ‘Prakash’ to an antiozonant ethylene diurea grown under ambient and elevated levels of ozone

Increase in surface level of ozone (O₃) in last 30 years is one of the major problems for global agriculture. Field experiment was conducted using open top chambers on two Indian maize cultivars (Buland and Prakash) grown under ambient (AO) and elevated (EO) O₃ concentrations to evaluate the effect of an antiozonant ethylene diurea (EDU) given as soil drench. EDU application reduced the ROS production with concomitant decrease in lipid peroxidation. Inductions in activities of enzymatic antioxidants along with increased content of non-enzymatic antioxidants were observed in EDU-treated plants, though the response varied between the cultivars. Photosynthetic proteins (PEP carboxylase and RuBisCO large and small subunits) detected through SDS–PAGE analysis increased with EDU treatment. EDU also led to an increase in jasmonic acid and a decline in salicylic acid contents. The protective effect of EDU was further accompanied by increased pigments (chlorophyll and carotenoids), foliar carbohydrates (starch and total soluble sugars), enhanced biomass, and economic yield. Effectiveness of EDU was more evident at higher O₃ concentration and cultivar Prakash exhibited a more positive response with EDU as compared to Buland.