Ribonucleotide reductase activity in green algae

A ribonucleoside diphosphate reductase is demonstrated in the algae, $\text{Scenedesmus}\text{obliquus}$ and $\text{Chlorella}\text{pyrenoidosa}$. In synchronized cultures an activity maximum at the 12th hour of the cell cycle coincides with maximum DNA production. Induction of reductase activity is prevented by cycloheximide. The enzyme requires dithiols for reduction of CDP $\text{in}\text{vitro}$; it is not significantly stimulated by iron or magnesium ions nor dependent upon deoxyadenosylcobalamin. ATP stimulates the reaction but dATP or dTTP act as inhibitors. The ribonucleotide reductase of green algae differs from the B₁₂-requiring enzyme characterized in $\text{Euglena}\text{gracilis}$.     

Radioimmunological and biological measurement of prostaglandins in rabbit urine : Decrease of PGE2 excretion at high NaCl intake

The estimation of prostaglandin (PG) E₂ and of PGF_2α by radioimmunoassay is described in detail. PGE₂ was measured after conversion to either PGB₂ or PGF_2α and the results compared to bioassay. The methods were used to follow the excretion of PGE₂ and PGF_2α after salt loading in rabbits. A marked reduction of PGE₂ levels was observed at high NaCl intake, while PGF_2α excretion remained unchanged.     

Methanogenesis in a saltern in the Bretagne (France)

Abstract Salterns in the Bretagne (France), exhibiting different stages of salinity of 5% to 33% evolved up to 0.7 mmol methane per m² per day. Methane concentrations of up to 0.4 mM were found. High methane evolution rates and increased methane concetration were restricted to basins of up to 7% and more than 15% salinity, and to the upper 10 cm of the sediments, where high sulfate concentrations (50 to 100 mM) occurred as well. Basins of 10–15% salinity exhibited only low methane evolution rates (less than 0.05 mmol methane per m² per day) and low methane concentrations (less than 0.02 mM). Gas bubbles arising during times of increased photosynthetic activity from the microbial mats covering the sediments of the saltern basins contained up to 2% methane. Addition of methylated amines and methanol, but not of H₂/CO₂, formate or acetate, to sediments slurries from basins of up to 12% salinity resulted in a rapid enrichment of methanogenic populations. Enriched methanogenic bacteria did not grow at salinities exceeding 15% or temperatures exceeding 45°C, and showed characteristics similar to those documented for Methanococcus halophilus and strain SF1 (DSM 3243). No enrichments were obtained from basins of more than 20% salinity in spite of methane being produced and evolved from those basins.     

Der mikrobielle Abbau von Kohlenwasserstoffen

Ohne Zusammenfassung     

Studies on the cell cycle of Myxobacter AL-1

Myxobacter AL-1 was synchronized by size fractionation of asynchronous cultures on a 5–20% equivolumetric sucrose gradient in a Ti—15 zonal rotor. The degree of synchronization obtained by this method was determined 1. by a comparison of the size distribution of an asynchronous culture to the distribution of cell numbers in the fractions of the zonal run, 2. by studying the size distributions in the different fractions obtained with the zonal rotor and 3. by following the growth and size distribution of a fraction from a zonal run during one division cycle. The results indicate that this method is suitable for the study of the cell cycle of Myxobacter AL-1.     

Versuche über die Chemorezeption der Brachyuren

Ohne Zusammenfassung     

Ornithologische Notizen aus dem Ebrodelta

Zusammenfassung Im Ebrodelta ist, abgesehen von einigen Seen und Sümpfen, nur noch ein schmaler Küstenstreifen landwirtschaftlich ungenutzt. Hier hat sich ein Teil ursprünglichen Vogelreichtums erhalten, und hier wurde seit einigen Jahren eine Reihe faunistischer Erhebungen durchgeführt.Diese erbrachten mehrere erste Brutnachweise für Spanien oder die spanische Mittelmeerküste:Larus ridibundus, Sterna dougallii, St. sandvicensis, Haematopus ostralegus, Limosa limosa, Asio flammeus, Acrocephalus palustris. Als Rast- und Überwinterungsgebiet ist das Delta von großer Bedeutung, z. B. fürEgretta garzetta undPhoenicopterus ruber. Enge Beziehungen zur Camargue sind vielfach erkennbar, vielleicht sogar hinsichtlich der Ausbreitung vonLarus ridibundus undHaematopus ostralegus. Regelmäßige Wintervorkommen vonMarmaronetta angustirostris sind erwähnenswert.Es wird mit einigen bisher unbekannten Brutplätzen von Laro-Limicolen bekanntgemacht, von denen eine Kolonie vonSterna albifrons mit 300–400 Paaren besonders vermerkt sei. Für weitere Arten können Bestandsangaben gemacht werden.Dieses einzige, bedeutende Brut- und Rastgebiet zwischen Camargue und Coto Doñana ist in höchster Gefahr, durch intensivere landwirtschaftliche Nutzung und touristische Erschließung vernichtet zu werden.

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Resumen Datos ornitologicos sobre el Delta del Ebro. — Sin contar con charcas y marismas, el Delta del Ebro es una franja costera aun no explotada por la agricultura. Gracias a esto una numerosa variedad de aves ha podido mantenerse aprovechando las todavia persistentes condiciones orginarias del medio ambiente. Sobre estas aves se han venido acumulando en los ultimos años un buen acopio de observaciones.Se pudo constatar como nidificantes por primera vez en España o costas mediterranes a las siguientes especies:Larus ridibundus, Sterna dougalli, St. sandvicensis, Haematopus ostralegus, Limosa limosa, Asio flammeus, Acrocephalus palustris. Como lugar de invernada o refugio durante el paso el Delta del Ebro tiene un especial interes, por ejemplo paraEgretta garzetta yPhoenicopterus ruber. Se establecen algunas relaciones con la Camarga principalmente en cuanto a la expansión deLarus ridibundus yHaematopus ostralegus. Se mencionan invernadas regulares deMarmaronetta angustirostris. Se señalan algunos nuevos lugares de cria para Laro-Limicolas, merece destacarse el hallazgo de una colonia deSterna albifrons compuesta por unos 300–400 pares. Para otras especies se dan datos numerieos estimativos.El Delta del Ebro es un lugar unico y de gran importancia, situado entre la Camarga y el Coto de Doñana, que está hoy en peligro de desaparición debido a la colonización intensiva de la agricultura y a la creciente afluencia turistica.