Size-hierarchy in a year-class and "condition" of common minnow Esomus danricus (Ham.) in relation to various ecological factors operating in the pond environment

Investigations were made on the existence of size-hierarchy in specimens of Esomus danricus (Ham.) belonging to the same year-class, and the variations in condition factor of the different size-groups. Divergence in the growth rates of individual fish resulted in the development of size-hierarchy in the population. Marked changes seemed to occur in condition factor of the different size-groups. A multitude of factors operating simultaneously in the pond environment appeared to govern the condition factor of fish.     

CURRICULUM GUIDE FOR RESEARCH ETHICS WORKSHOPS FOR COUNTRIES IN THE MIDDLE EAST

To help ensure the ethical conduct of research, many have recommended educational efforts in research ethics to investigators and members of research ethics committees (RECs). One type of education activity involves multi‐day workshops in research ethics. To be effective, such workshops should contain the appropriate content and teaching techniques geared towards the learning styles of the targeted audiences. To ensure consistency in content and quality, we describe the development of a curriculum guide, core competencies and associated learning objectives and activities to help educators organize research ethics workshops in their respective institutions. The curriculum guide is divided into modular units to enable planners to develop workshops of different lengths and choose content materials that match the needs, abilities, and prior experiences of the target audiences. The content material in the curriculum guide is relevant for audiences in the Middle East, because individuals from the Middle East who participated in a Certificate Program in research ethics selected and developed the training materials (e.g., articles, powerpoint slides, case studies, protocols). Also, many of the activities incorporate active‐learning methods, consisting of group work activities analyzing case studies and reviewing protocols. The development of such a workshop training curriculum guide represents a sustainable educational resource to enhance research ethics capacity in the Middle East.     

Differential application of lambda-cyhalothrin to control the sandfly Lutzomyia longipalpis

Abstract. To study the impact of residual pyrethroid insecticide on the abundance and distribution of peridomestic Lutzomyia longipalpis , the sandfly vector of visceral leishmaniasis in Brazil, lambda-cyhalothrin was applied at 20 mg a.i.m^-2 in the following interventions: (i) spraying of all animal pens in a village (blanket coverage); (ii) treatment of a subset of animal pens, either by spraying, or by installation of insecticide-impregnated 1 m² cotton sheets as 'targets' (focal coverage).
By sampling with CDC light traps, and using a novel analytical approach, we detected a 90% reduction in Lu. longipalpis abundance in sprayed sheds of the focal intervention. However, there was no discernible effect on the abundance of other phlebotomines trapped in sheds, or on the abundance of Lu. longipalpis in untreated dining-huts and houses. This differential impact on Ludongipalpis abundance is explained in terms of the disruption of male pheromone production. Treated targets were approximately half as effective as residual spraying in reducing the abundance of Lu.longipalpis in sheds.
Following blanket intervention, the abundance of Lu.longipalpis in traps fell by only 45% (not significant): catches at untreated dining-huts actually increased, possibly because the blanket coverage diverted Lu. longipalpis away from major aggregation sites at animal pens. It is recommended that care be taken during vector control programmes to ensure that all potential aggregation sites are treated. The possible consequences of leaving some sites untreated include poor control of peridomestic sandfly abundance and an increase in the biting rate on dogs and humans.     

The Adaptation of Enzymes to Pressure II. A Comparison of Muscle Pyruvate Kinases from Surface and Midwater Fishes with the Homologous Enzyme from an Off-Shore Benthic Species

SYNOPSIS. Pyruvate kinase (PK) maximum catalytic rate is dramaticallydecelerated by increasing hydrostatic pressure. In four differentspecies inhabiting different portions of the water column, musclepyruvate kinase displays (1) a reduction in the volume changeof activation, V*. a t higher temperatures, (2) a pH independenceof V*, and (3) a general increase in the activation energy atincreased pressures. Although shared by the four different pyruvatekinases examined, none of these characteristics is criticallyinvolved in the regulation of PK catalysis. In contrast, pressureeffects on another set of characteristics, all vitally importantto control of PK catalytic function, depend upon the speciesorigin of the enzyme. In the case of the rainbow trout, Salmogairdneri, high pressure dramatically reduces pyruvate kinaseaffinities for the two substrates (PEP and ADP), the cationiccofactor (Mg²⁺), and the negative modulator (ATP). The homologousmuscle enzyme from Oligoplites mundus, another surface dwellingspecies, displays similar responses to pressure. On the otherhand, muscle PK affinities for the same key regulatory ligandsare much less pressure sensitive in the abyssal rattail fishes(Coryphaenoides sp.) and are essentially pressure independentin a vertically migrating midwater sea bass, Ectreposebastesimus. In these latter two species, PK catalytic rates underprobable physiological conditions are determined largely bythese kinetic properties rather than by energy-volume parameters.     

The Effects of Dietary Selenium and Vitamin E and their Combination on the Fatty Acids of Erythrocytes,Bone Marrow and Spleen Tissue Lipids of Lambs

The object was to determine the influence of dietary vitamin E, selenium and their combination on the fatty acid con-tent of erythrocytes, bone marrow and spleen lipids of Akkaraman lambs. After supplementation for 15 days, the amount of all fatty acids was slightly higher (p < 0·05) in the vitamin E as compared to the control group, whereas the amount of longer fatty acids was significantly higher (p < 0·01, p < 0·001) in the selenium and combination groups. On the thirtieth day, the amount of all fatty acids was slightly high (p < 0·5) in all the supplemented groups in comparison with the control group. In the bone marrow lipids, the amount of longer fatty acids was decreased (p < 0·05, p < 0·01, p < 0·001) in the vitamin E and combination groups as compared to the control. Although the amount of some fatty acids was high (p < 0·05, p < 0·01) in the selenium group compared to the control, linoleic (18:2), linolenic (18:3) and the polyunsaturated fatty acids (PUFA) were lower (p < 0·05, p < 0·001). In the spleen lipids, the amount of longer fatty acids was slightly decreased (p < 0·05) in the vitamin E group as compared with the control; however the amount of longer fatty acids was significantly higher (p < 0·05, p < 0·01) in the selenium and combination groups in comparison to the control group. Thus dietary supplementation with selenium was more effective than dietary vitamin E supplementation in altering the fatty acid content of the erythrocyte, bone marrow and spleen lipids. © 1997 John Wiley & Sons, Ltd.     

Effects of Hydrostatic Pressure on Catalysis by Different Lactate Dehydrogenase Isozymes from Tissues of an Abyssal Fish

SYNOPSIS. The predominant lactate dehydrogenases (LDH's) occurringin liver, heart, and muscle of a benthic Coryphaenoides speciesare electrophoretically distinguishable from each other. Maximumrates of pyruvate reduction catalyzed by heart and muscle LDH'sshow an optimum pH near neutrality, while liver LDH activitydisplays an unusual alkaline pH optimum. Pyruvate saturationcurves are Michaelis-Menten in form for all three preparations.Maximum catalytic rates and the apparent K_m (pyruvate) are pressureindependent for liver and heart LDH's. In the case of muscleLDH's, the maximum catalytic rate is also pressure insensitive,but the K_m is dramatically increased by pressure. These experimentsdearly indicate that, at low substrate concentrations, the preciseeffects of pressure on enzyme-catalyzed reactions depend uponthe nature and origin of the catalyst.     

Effects of Pressure and Temperature on the Catalytic and Regulatory Properties of Muscle Pyruvate Kinase from an Off-Shore Benthic Fish

SYNOPSIS. Muscle pyruvate kinase from an abyssal Coryphaenoidesspecies occurs as a single electrophoretic form with an isoelectricpoint of about pH 6.0. Maximum catalytic rates are dramaticallyreduced by pressure. For catalysis at 3°C, the volume changeof activation, V*, is about 44 cm³/mole (calculated between14.7 and 8000 psi). The value ot V* decreases at higher temperaturesbut is pH independent. The activation energy for rattail musclepyruvate kinase at 14.7 psi is about 13 Kcal/mole and doublesat 12,000 psi. Mg²⁺ saturation kinetics involve positive site-siteinteractions. Hill plots yield n values of about 2.4 and K_avalues of about 2 mM (at 3°C), and these constants are pressureindependent. The K_m values for ADP increase slightly with pressure.PEP saturation curves are complex: at high PEP concentrations,the n values are about 2–2.5, while at low PEP levels,values for the Hill constant are about 1.0. The Hill constantlor PEP is not affected by pressure, but the apparent K_m increasessomewhat with pressure. FDP dramatically activates rattail musclepyruvate kinase (500% activation with 0.1 mM FDP) by (1) reducingthe K_mPEP, (2) increasing the maximum velocity, and (3) overridingnegative ATP modulation of the enzyme. The latter control featureis strictly dependent upon pressure and is not observed at lowpressure. In the presence of FDP, the K_m for PEP decreases athigh pressures, in this way counteracting the inhibitory effectsof pressure. Under low concentrations of substrates, pyruvatekinase activity is probably determined by its kinetic propertiesand not by energy-volume relationships.