Recovery of methanotrophs from disturbance: population dynamics,evenness and functioning

Biodiversity is claimed to be essential for ecosystem functioning, but is threatened by anthropogenic disturbances. Prokaryotes have been assumed to be functionally redundant and virtually inextinguishable. However, recent work indicates that microbes may well be sensitive to environmental disturbance. Focusing on methane-oxidizing bacteria as model organisms, we simulated disturbance-induced mortality by mixing native with sterilized paddy soil in two ratios, 1:4 and 1:40, representing moderate and severe die-offs. Disturbed microcosms were compared with an untreated control. Recovery of activity and populations was followed over 4 months by methane uptake measurements, pmoA-qPCR, pmoA-based terminal restriction fragment length polymorphism and a pmoA-based diagnostic microarray. Diversity and evenness of methanotrophs decreased in disturbed microcosms, but functioning was not compromised. We consistently observed distinctive temporal shifts between type I and type II methanotrophs, and a rapid population growth leading to even higher cell numbers comparing disturbed microcosms with the control. Overcompensating mortality suggested that population size in the control was limited by competition with other bacteria. Overall, methanotrophs showed a remarkable ability to compensate for die-offs.     

Mass Culturing of Ditylenchus dipsaci to Yield Large Quantities of Inoculum

Methods are described for rearing large quantities of Ditylenchus dipsaci on alfalfa tissues. Nematodes and alfalfa seed were disinfected and nematodes were reared in quantities sufficient to provide a continuous supply of inoculum for our alfalfa-breeding program. Nematodes reproduced best in darkness at 20-25 C. Cultures reached maximum numbers in 3-6 wk.     

Indol-3yl-acetic acid in roots of Zea mays

Indol-3yl-acetic acid was identified in extracts of sterile roots of Zeamays seedlings by means of TLC, chromogenic reactions, GLC and GC-MS.     

Letter: Crystallization and preliminary x-ray investigation of bovine erythrocyte carbonic anhydrase

The major form of bovine erythrocyte carbonic anhydrase has been prepared by a new method in which the conventional chloroform-ethanol treatment is replaced by chromatography on DEAE-Sephadex. Single crystals, suitable for high resolution X-ray diffraction studies, have been obtained from enzyme prepared by this method. The space group is P6₁22. The unit cell contains 12 enzyme molecules and has the dimensions $\text{a = b = 68}\text{A}\text{?}$, $\text{c = 244}\text{A}\text{?}$.     

Le Système Nerveux des Cténaires

Summary A subectodermal nerve-net is demonstrated in ten species of Ctenophores by means of either Methylene Blue vital staining or silver impregnation. There is no evidence of subendodermal nerve-net. The ectodermal nerve-net displays a characteristic polygonal pattern which is thought to result from morphogenetic events. Both bipolar and tripolar neurones occur.Three types of concentrations of nervous tissue are described: a) a high accumulation of nervous perikarya at the aboral sensory pole; b) a noticeable densification of the net along the eight meridional ciliary strands of every species, and around the lips of Beroidea; c) in the Cydippids Pleurobrachia and Hormiphora two thick strands of fibers and neurones interconnecting the aboral organ and the tentacles: the tentacular nerves.Ultrastructural evidence is given for the presence of nervous elements under and amidst ectodermal epithelial cells. Three features allow the recognition and characterization of neurites and neurones: a) numerous clear and/or granulated vesicles; b) microtubules in variable amounts; c) frequent and highly differentiated synaptic contacts.The very peculiar arrangement of the presynaptic elements is observed in all the species of Ctenophores so far studied. These synaptic contacts suggest chemical transmission in the nerve-net.On the basis of ultrastructural evidence the author refutes the nervous nature previously attributed to the ciliated cells of the meridional grooves.A parallel is drawn between nervous systems of Cnidaria and Ctenophora.

Ce travail correspond à la première partie d'une thèse de Doctorat d'Etat, intitulée: «Système nerveux et intégration chez les Cténaires». Il a été effectué au sein de l'Equipe de Recherches Associée au C.N.R.S. n^o 183 (Directeur: Dr. Max Pavans de Ceccatty) et avec le concours du Centre de Microscopie Electronique Appliquée à la Biologie, de l'Université Claude Bernard.Ce travail a bénéficié de la collaboration technique de Madame J. Amsellem que nous remercions vivement.     

The Legal Regulation of Floats and Gliders—In Quest of a New Regime?

This article analyzes the legal status of unmanned instruments (particularly, floats and gliders) for observation purposes in the ocean environment. These new kinds of instruments are being deployed by the thousands into the oceans, not the least as part of the Argo Project of the International Oceanographic Commission. Their uncontrolled drifting has raised legal questions, especially when such instruments enter waters subject to the jurisdiction of foreign states. The authors argue that the current international legal framework is insufficient to address the pertinent issues, and that a new legal regime is needed.     

Time course of pump inhibition by ouabain in amphibian epithelia

Inhibition by ouabain of rheogenic Na⁺ transport across the basolateral membranes of frog skin is found to be manifest within 3–4 min. This rate of pump inhibition is not different from the rate of diffusion through extracellular tissue layers between the serosal bath and the actual site of action, i.e., the epithelial cell layers. It is concluded that the well-known slow time course of decrease in transepithelial current flow is due ionic redistribution and conductance changes of the epithelial membranes secondary to pump inhibition.     

Quelques données ultrastructurales sur un myoépithélium: le pharynx d'un Bryozoaire

Résumé L'épithélium pharyngien d'Alcyonidium polyoum possède des cellules pourvues d'une très grande vacuole. L'incompressibilité du liquide vacuolaire permet un élargissement brusque de l'organe lors de la contraction du manchon musculaire strié qui enserre cette vacuole. Les fibres musculaires sont insérées sur le plasmalemme apical par des filaments unitifs. Le point d'attache est relié à la lame amorphe du cell-coat qui entoure les microvillosités par des fibrilles, réalisant probablement une liaison mécamique plus efficace. Le reticulum sarcoplasmique porte des ribosomes. Le cytoplasme apical renferme des vésicules de diverses catégories.

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Some ultrastructural data about a myoepithelium: The pharynx of a bryozoan

Summary Pharyngeal cells of Alcyonidium polyoum (Bryozoa) are provided with very large vacuoles. Each vacuole is enveloped by a thin layer of striated muscle, whose contraction enlarges the organ. Filaments join the muscular elements to the apical plasmalemma. This point of muscular insertion is connected by fibrils with the amorphic lamina of cell-coat which surrounds the microvilli. Ribosomes are often found on dyads. Various vesicles are located in the apical cytoplasm.

     

Synthesis,anti-diabetic evaluation and molecular docking studies of 4-(1-aryl-1H-1, 2, 3-triazol-4-yl)-1,4-dihydropyridine derivatives as novel 11-β hydroxysteroid dehydrogenase-1 (11β-HSD1) inhibitors

11-Beta-Hydroxysteroid dehydrogenase-1(11β-HSD1) inhibitors are one of the emerging classes of molecules to fight against diabetic complications. A novel series of 4-(1-substituted-1H-1,2,3-triazol-4-yl)-1,4-dihydropyridine derivatives were synthesized and evaluated for their anti-diabetic activity. Two compounds showed anti-diabetic activity very effectively. To clarify the mechanism of action of these compounds, the most potent compounds (5g and 5h) of the synthesized analogs were further studied by testing its 11-Beta Hydroxysteroid dehydrogenase-1 inhibitory activity through in vitro enzymatic experiments. The results showed that the 11β-HSD1 inhibitory activity of compounds 5g and 5h was stable and efficient. Molecular docking studies revealed compounds 5g (−9.758) and 5h (−8.495) to have a stable binding patterns to the human 11-Beta-Hydroxysteroid dehydrogenase-1.