Effect of antiserum to luteinizing hormone (LHAS) on the physiology of the epididymis and accessory glands in the albino rat

Rabbit antiserum specific to ovine luteinizing hormone free of contaminating antibodies to nonspecific proteins and FSH was administered to adult, intact rats at a dose of 0.1 and 0.2 ml/day for five days. LHAS had no effect on the weights of the epididymis but decreased their secretory activity to castrate level. Administration of 0.2 ml of LHAS or castration resulted in a marked and comparable reduction in the weights and secretory activity of the accessory glands. LHAS, even at a lower dose (0.1 ml/day), caused a significant reduction in the content of sialic acid in the vas deferons and Cowper's glands. These results are discussed in relation to the factors that regulate the functions of the epididymis and accessory glands.

Selective attention in a synchronising bushcricket: physiology

Synchronising bushcricket males achieve synchrony by delaying their chirps in response to calling neighbours. In multi-male choruses, males that delay chirps in response to all their neighbours would remain silent most of the time and be unable to attract mates. This problem could be overcome if the afferent auditory system exhibited selective attention, and thus a male interacted only with a subset of neighbours. We investigated whether individuals of the bushcricket genus Mecopoda restricted their attention to louder chirps neurophysiologically, behaviourally and through spacing. We found that louder leading chirps were preferentially represented in the omega neuron but the representation of softer following chirps was not completely abolished. Following chirps that were 20 dB louder than leading chirps were better represented than leading chirps. During acoustic interactions, males synchronised with leading chirps even when the following chirps were 20 dB louder. Males did not restrict their attention to louder chirps during interactions but were affected by all chirps above a particular threshold. In the field, we found that males on average had only one or two neighbours whose calls were above this threshold. Selective attention is thus achieved in this bushcricket through spacing rather than neurophysiological filtering of softer signals.

Selective attention in a synchronising bushcricket: physiology, behaviour and ecology

Synchronising bushcricket males achieve synchrony by delaying their chirps in response to calling neighbours. In multi-male choruses, males that delay chirps in response to all their neighbours would remain silent most of the time and be unable to attract mates. This problem could be overcome if the afferent auditory system exhibited selective attention, and thus a male interacted only with a subset of neighbours. We investigated whether individuals of the bushcricket genus Mecopoda restricted their attention to louder chirps neurophysiologically, behaviourally and through spacing. We found that louder leading chirps were preferentially represented in the omega neuron but the representation of softer following chirps was not completely abolished. Following chirps that were 20 dB louder than leading chirps were better represented than leading chirps. During acoustic interactions, males synchronised with leading chirps even when the following chirps were 20 dB louder. Males did not restrict their attention to louder chirps during interactions but were affected by all chirps above a particular threshold. In the field, we found that males on average had only one or two neighbours whose calls were above this threshold. Selective attention is thus achieved in this bushcricket through spacing rather than neurophysiological filtering of softer signals.

Selective attention in a synchronising bushcricket: physiology, behaviour and ecology

Synchronising bushcricket males achieve synchrony by delaying their chirps in response to calling neighbours. In multi-male choruses, males that delay chirps in response to all their neighbours would remain silent most of the time and be unable to attract mates. This problem could be overcome if the afferent auditory system exhibited selective attention, and thus a male interacted only with a subset of neighbours. We investigated whether individuals of the bushcricket genus Mecopoda restricted their attention to louder chirps neurophysiologically, behaviourally and through spacing. We found that louder leading chirps were preferentially represented in the omega neuron but the representation of softer following chirps was not completely abolished. Following chirps that were 20 dB louder than leading chirps were better represented than leading chirps. During acoustic interactions, males synchronised with leading chirps even when the following chirps were 20 dB louder. Males did not restrict their attention to louder chirps during interactions but were affected by all chirps above a particular threshold. In the field, we found that males on average had only one or two neighbours whose calls were above this threshold. Selective attention is thus achieved in this bushcricket through spacing rather than neurophysiological filtering of softer signals.

A naturally occurring amino acid substitution in the voltage-dependent sodium channel selectivity filter affects channel gating

The pore of sodium channels contains a selectivity filter made of 4 amino acids, D/E/K/A. In voltage sensitive sodium channel (Nav) channels from jellyfish to human the fourth amino acid is Ala. This Ala, when mutated to Asp, promotes slow inactivation. In some Nav channels of pufferfishes, the Ala is replaced with Gly. We studied the biophysical properties of an Ala-to-Gly substitution (A1529G) in rat Nav1.4 channel expressed in Xenopus oocytes alone or with a beta 1 subunit. The Ala-to-Gly substitution does not affect monovalent cation selectivity and positively shifts the voltage-dependent inactivation curve, although co-expression with a beta 1 subunit eliminates the difference between A1529G and WT. There is almost no difference in channel fast inactivation, but the beta 1 subunit accelerates WT current inactivation significantly more than it does the A1529G channels. The Ala-to-Gly substitution mainly influences the rate of recovery from slow inactivation. Again, the beta 1 subunit is less effective on speeding recovery of A1529G than the WT. We searched Nav channels in numerous databases and noted at least four other independent Ala-to-Gly substitutions in Nav channels in teleost fishes. Thus, the Ala-to-Gly substitution occurs more frequently than previously realized, possibly under selection for alterations of channel gating.

Modulation of redox regulatory molecules and electron transport chain activity in muscle of air breathing fish Heteropneustes fossilis under air exposure stress

Responses of redox regulatory system to long-term survival (> 18 h) of the catfish Heteropneustes fossilis in air are not yet understood. Lipid and protein oxidation level, oxidant (H2O2) generation, antioxidative status (levels of superoxide dismutase, catalase, glutathione peroxidase and reductase, ascorbic acid and non-protein sulfhydryl) and activities of respiratory complexes (I, II, III and IV) in mitochondria were investigated in muscle of H. fossilis under air exposure condition (0, 3, 6, 12 and 18 h at 25 A degrees C). The increased levels of both H2O2 and tissue oxidation were observed due to the decreased activities of antioxidant enzymes in muscle under water deprivation condition. However, ascorbic acid and non-protein thiol groups were the highest at 18 h air exposure time. A linear increase in complex II activity with air exposure time and an increase up to 12 h followed by a decrease in activity of complex I at 18 h were observed. Negative correlation was observed for complex III and V activity with exposure time. Critical time to modulate the above parameters was found to be 3 h air exposure. Dehydration induced oxidative stress due to modulation of electron transport chain and redox metabolizing enzymes in muscle of H. fossilis was clearly observed. Possible contribution of redox regulatory system in muscle tissue of the fish for long-term survival in air is elucidated. Results of the present study may be useful to understand the redox metabolism in muscle of fishes those are exposed to air in general and air breathing fishes in particular.

A Kunitz-type serine protease inhibitor from Butea monosperma seed and its influence on developmental physiology of Helicoverpa armigera

A protease inhibitor from the seeds of Butea monosperma (BmPI) was purified, characterized and studied for its influence on developmental physiology of Helicover-pa armigera. BmPI on two-dimensional separations indicated the presence of a 14 kDa protein with an isoelectric point in the acidic region (pl 5.6). Multiple Sequence Analysis data suggested that the BmPI contains a sequence motif which is conserved in various trypsin and chymotrypsin inhibitors of Kunitz-type. The inhibitor exhibited trypsin inhibitory activity in a broad range of pH (4-10) and temperature (10-80 degrees C). The enzyme kinetic studies revealed BmPI as a competitive inhibitor with a K-i value of 1.2 x 10(-9) M. In vitro studies with BmPI indicated measurable inhibitory activity on total gut proteolytic enzymes of H. armigera (IC(50)2.0 mu g/ml) and bovine trypsin. BmPI supplemented artificial diet caused dose dependent mortality and reduction in growth and weight. The fertility and fecundity of H. armigera, declined whereas the larval-pupal duration of the insect life cycle extended. These detrimental effects on H. armigera suggest the usefulness of BmPl in insect pest management of food crops. (C) 2014 Elsevier Ltd. All rights reserved.

Novel Functions of (p)ppGpp and Cyclic di-GMP in Mycobacterial Physiology Revealed by Phenotype Microarray Analysis of Wild-Type and Isogenic Strains of Mycobacterium smegmatis

The bacterial second messengers (p)ppGpp and bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) regulate important functions, such as transcription, virulence, biofilm formation, and quorum sensing. In mycobacteria, they regulate long-term survival during starvation, pathogenicity, and dormancy. Recently, a Pseudomonas aeruginosa strain lacking (p) ppGpp was shown to be sensitive to multiple classes of antibiotics and defective in biofilm formation. We were interested to find out whether Mycobacterium smegmatis strains lacking the gene for either (p)ppGpp synthesis (Delta rel(Msm)) or c-di-GMP synthesis (Delta dcpA) would display similar phenotypes. We used phenotype microarray technology to compare the growth of the wild-type and the knockout strains in the presence of several antibiotics. Surprisingly, the Delta rel(Msm) and Delta dcpA strains showed enhanced survival in the presence of many antibiotics, but they were defective in biofilm formation. These strains also displayed altered surface properties, like impaired sliding motility, rough colony morphology, and increased aggregation in liquid cultures. Biofilm formation and surface properties are associated with the presence of glycopeptidolipids (GPLs) in the cell walls of M. smegmatis. Thin-layer chromatography analysis of various cell wall fractions revealed that the levels of GPLs and polar lipids were reduced in the knockout strains. As a result, the cell walls of the knockout strains were significantly more hydrophobic than those of the wild type and the complemented strains. We hypothesize that reduced levels of GPLs and polar lipids may contribute to the antibiotic resistance shown by the knockout strains. Altogether, our data suggest that (p)ppGpp and c-di-GMP may be involved in the metabolism of glycopeptidolipids and polar lipids in M. smegmatis.

Isotopic and geochemical characterization of invader tilapia fishes from water bodies of West Bengal and Karnataka, India

The otoliths (N = 12) of freshwater invasive species tilapia (Tilapia mossambicus) collected from two water bodies located at Kolkata and Bangalore, India, were analyzed for stable isotopes (delta 18O, delta 14C) and major and trace elements in order to assess the suitability of using otoliths as a tracer of aquatic environmental changes. The stable isotope analysis was done using the dual inlet system of a Finnigan-MAT 253 isotope ratio mass spectrometer (Thermo-Fisher, Bremen, Germany). Concentrations of major and trace elements were determined using a Thermo X-Series II quadrupole mass spectrometer. The stable isotope composition in tilapia otolith samples from Bangalore and Kolkata water bodies are quite good agreeing with that of the respective lake/pond and rain water. Elemental composition revealed in a pattern of Ca > Fe > Na > Sr > K > Ba > Cr > Mg > As > Mn > Zn > Co > Cu > Cd > Pb. The otoliths from Kolkata pond water are more enriched in Ba, Zn, Pb, Mn, Se, Cu, Zn, Cd, and Ni whereas Cr and As were found to be higher in otolith samples from Bangalore lake. The enrichment factor (EF) values of Cr were higher for both the sampling location in comparison with other metals, although all the studied metals exhibited EF values >1. The PCA shows clustering of metals in the otolith which are related either with the metabolic and physiological attributes or waterborne source. The study demonstrated the potential of stable isotope techniques to distinguish otolith specimens from varied climatic zone, while elemental composition recorded the quality of water at both the locations. The role of climate driving the quality of water can be understood by detailed and continuous monitoring of otolith specimens in the future. Future method allows reconstruction of climate and water quality from old specimens from field exposures or museum collection.