Fine structure of diffused pseudobranchial neurosecretory cells associated with carotid labyrinth in an air‐breathing catfish Clarias batrachus

Fish are known to have branchial chemoreceptors and even extrabranchial chemoreceptors to meet the challenges of aquatic environment. The pseudobranchial neurosecretory system associated with carotid labyrinth (CL) is one such example. CL – a chemosensory organ is well known in amphibians. The homologous structure also exists in fish. Clusters of neurosecretory cells, close to the CL and the first two efferent branchial arteries occur in catfish and a few other groups of teleosts. These cells belong to the pseudobranchial neurosecretory system (PNS). To reveal the ultrastructure of CL and the pseudobranchial neurosecretory cells (PNSCs), environmental scanning electron microscope (ESEM) and transmission electron microscope (TEM) investigations were made in an Asian air‐breathing catfish Clarias batrachus. Under ESEM, the PNS appeared as a mass of cells innervated by nerves and supplied by blood capillaries. The CL appeared to have a network of blood capillaries. The transmission electron microscopic investigations showed pear shaped PNSCs having different sizes of dense cored vesicles (DCVs), numerous mitochondria, nerve varicosities, indicating a secretory function of the cells. The CL shows a close association with PNSCs and smooth muscles. Although the exact function of the CL and associated PNSCs in the biology of fish is far from clear, their morphology suggests they are involved in a stress response such as to hypoxia.     

Purification and characterization of streptolysin O from Streptococcus pyogenes.

1. Streptolysin O, an exotoxin produced by group A beta-hemolytic streptococci, has been purified from Streptococcus pyogenes culture supernatants. 2. The isolation and purification procedure involved ammonium sulphate and polyethylene glycol precipitations, and ion-exchange chromatographies on CM-Sepharose and Mono Q. 3. The proposed procedure introduces two ion-exchange chromatography steps making the purification process simpler and, especially, more reproducible than other described protocols. 4. The purified streptolysin O was hemolytically active, had a specific activity of 415,000 HU/mg, an optimum pH of 7.0, a relative molecular mass of 60,100 and an isoelectric pH of 7.5.     

Strategies to Improve Child Immunization via Antenatal Care Visits in India: A Propensity Score Matching Analysis

Numerous studies have examined the empirical evidence concerning the influence of demographic and socio-economic factors influencing child immunization, but no documentation is available which shows the actual impact of antenatal care (ANC) visits on subsequent child immunization. Therefore, this paper aims to examine the net impact of ANC visits on subsequent utilization of child immunization after removing the presence of selection bias. Nationwide data from India’s latest National Family Health Survey conducted during 2005–06 is used for the present study. The analysis has been carried out in the two separate models, in the first model 1–2 ANC visit and in the second model three or more ANC visits has been compared with no visit. We have used propensity score matching method with a counterfactual model that assesses the actual ANC visits effect on treated (ANC visits) and untreated groups (no ANC visit), and have employed Mantel-Haenszel bounds to examine whether result would be free from hidden bias or not. Using matched sample analysis result shows that child immunization among the groups of women who have completed 1–2 ANC visits and those who had more than two visits was about 13 percent and 19 percent respectively, higher than the group of women who have not made any ANC visit. Findings of nearest neighbor matching with replacement method, which completely eliminated the bias, indicate that selection bias present in data set leads to overestimates the positive effects of ANC visits on child immunization. Result based on Mantel-Haenszel bounds method suggest that if around 19 percent bias would be involved in the result then also we could observe the true positive effect of 1–2 ANC visits on child immunization. This also indicates that antenatal clinics are the conventional platforms for educating pregnant women on the benefits of child immunization.     

Antioxidant and iron-chelating activities of cyanobacterial exopolymers with potential for wound healing

Progress of wound healing is critically dependent on the balance between oxidants and antioxidants at the wound site, and transition metals such as iron can exacerbate ROS generation. In the present study, cyanobacterial exopolymers from three strains of Anabaena and Tolypothrix tenuis have been characterized for their antiradical and Fe²⁺-chelating activity. All the four exopolymers exhibited antioxidant activities against O₂·, H₂O₂, OH·, and NO·, with the exopolymer from Anabaena oryzae showing strong inhibition of NO· and ·OH radicals followed by that from Anabaena anomala. Correlation analysis of antioxidant activities and sulphate, uronic and phenolic content of the exopolymers showed a strong correlation of sulphate content to superoxide scavenging and activity against nitric oxide radicals. H₂O₂ scavenging was related to the presence of phenolics in the preparation which also contributed to the reducing power. Iron chelation had a strong bearing upon the overall reducing power and superoxide control.     

Effect of potassium chloride and calcium chloride induced stress on in vitro cultures of Bacopa monnieri (L.) Pennell and accumulation of medicinally important bacoside A

Growth, osmotic adjustment, antioxidant enzyme defense and principle medicinal component bacoside A was studied in in vitro raised shoots of Bacopa monnieri under different concentrations of KCl and CaCl₂ (0, 50, 100, 150 or 200 mM). Significant reduction was observed in shoot number per culture; shoot length, fresh weight, dry weight and tissue water content (TWC) when shoots were exposed to increasing KCl and CaCl₂ concentrations (50–200 mM) as compared to control. Minimum damage to the membrane as assessed by malondialdehyde (MDA) content was noticed in control in contrast to sharp increase in KCl and CaCl₂ stressed shoots. Higher amounts of free proline, glycine betaine and total soluble sugars (TSS) accumulated in KCl and CaCl₂ exposed shoots compared to the controls. Among different concentrations of KCl and CaCl₂, increasing concentration of CaCl₂ showed more increase in osmolyte accumulation. Na⁺ content decreased with increasing concentrations of KCl and CaCl₂. Accumulation of K⁺ increased significantly in KCl (50–100 mM) stressed shoots as compared to control, while it decreased in CaCl₂ treated shoots indicating that it prevents the uptake of K⁺ ions. Ca²⁺ accumulation significantly increased with increasing concentrations of CaCl₂ up to 150 mM but decreased at higher concentrations. Shoots treated with KCl and CaCl₂ (0–100 mM) showed higher antioxidant enzyme (SOD, CAT, APX and GPX) activities but KCl suppressed the activities at higher concentrations. Accumulation of bacoside A was enhanced with an increase in KCl and CaCl₂ concentration up to 100 mM. It appears from the data that accumulation of osmolytes, and elevated activities of antioxidant enzymes play an important role in osmotic adjustment in shoot cultures of Bacopa and the two salts tested have a positive effect on bacoside accumulation.     

Co-fermentation of carbon sources by Enterobacter aerogenes ATCC 29007 to enhance the production of bioethanol

We investigated the enhancement of bioethanol production in Enterobacter aerogenes ATCC 29007 by co-fermentation of carbon sources such as glycerol, glucose, galactose, sucrose, fructose, xylose, starch, mannitol and citric acid. Biofuel production increases with increasing growth rate of microorganisms; that is why we investigated the optimal growth rate of E. aerogenes ATCC 29007, using mixtures of different carbon sources with glycerol. E. aerogenes ATCC 29007 was incubated in media containing each carbon source and glycerol; growth rate and bioethanol production improved in all cases compared to those in medium containing glycerol alone. The growth rate and bioethanol production were highest with mannitol. Fermentation was carried out at 37 °C for 18 h, pH 7, using 50 mL defined production medium in 100 mL serum bottles at 200 rpm. Bioethanol production under optimized conditions in medium containing 16 g/L mannitol and 20 g/L glycerol increased sixfold (32.10 g/L) than that containing glycerol alone (5.23 g/L) as the carbon source in anaerobic conditions. Similarly, bioethanol production using free cells in continuous co-fermentation also improved (27.28 g/L) when 90.37 % of 16 g/L mannitol and 67.15 % of 20 g/L glycerol were used. Although naturally existing or engineered microorganisms can ferment mixed sugars sequentially, the preferential utilization of glucose to non-glucose sugars often results in lower overall yield and productivity of ethanol. Here, we present new findings in E. aerogenes ATCC 29007 that can be used to improve bioethanol production by simultaneous co-fermentation of glycerol and mannitol.