Phenanthrene degradation by estuarine surface microlayer and bulk water microbial populations

Paired surface microlayer and bulk water samples from five sites in the Great Bay Estuary, New Hampshire, were examined with regard to numbers of bacteria,¹⁴C-phenanthrene biodegradation potentials, and organic and inorganic chemical characteristics. Microlayer samples were generally enriched in nutrients (N and P), dissolved organic matter, and culturable heterotrophic bacteria compared with their corresponding bulk waters. Microlayer samples from marina environments were also enriched in aromatic hydrocarbons, as determined by UV spectrophotometric and fluorometric analyses, and demonstrated substantial phenanthrene biodegradation activity in the assay employed. Biodegradation activity of marina bulk water samples ranged from nil to levels exceeding those exhibited by microlayer samples. No diminution of biodegradation activity was observed after filtration (1.2 m effective retention) of microlayer water, indicating that the responsible organisms were not particle-associated. Phenanthrene-degrading bacteria, enumerated by counting clearing zones in a crystalline phenanthrene overlay after colony development on a phenanthrene/toluene agar (PTA) medium, were superior to epifluorescence direct counts or standard plate counts on PTA or estuarine nutrient agar in predicting¹⁴C-phenanthrene biodegradative activity.     

A new method for thawing frozen ram semen

The purpose of this work was to facilitate the on-farm use of frozen semen by initially thawing the straws in laboratory treated sperm (TS) rather than on-farm control sperm (CS), as is usually done. After thawing, TS was diluted, centrifuged, and extended in skim milk for storage at +15° C until utilized 3 to 6 hours later. $\text{In}$$\text{vitro}$: immediately after preparation and addition of skim milk for TS and thawing for CS, the percentage of stained cells and abnormal cells was higher (P < 0.01) in TS than in CS. In contrast, following a 3 hour incubation, TS and CS had the same proportion of motile cells. $\text{In}$$\text{vivo}$: fertility and prolificacy of FGA + PMSG-treated ewes were slightly higher following AI (1 AI/female) with TS than with CS: 52.4% $\text{vs}$ 44.2% and 155.0% $\text{vs}$ 148.0%, respectively. Fertility was also higher (P < 0.01) with fresh semen than with TS, but the difference was only 9.2 points (70.3% $\text{vs}$ 61.1% for the respective 798 and 242 ewes inseminated once). Prolificacy rates were similar (164.3% $\text{vs}$ 167.6%).     

Differential bioavailability of soil-sorbed naphthalene to two bacterial species.

Prediction of the fate of hydrophobic organic contaminants in soils is complicated by the competing processes of sorption and biodegradation. To test the hypothesis that sorbed naphthalene is unavailable to degradative microorganisms, we developed a simple kinetic method to examine the rates and extents of naphthalene degradation in soil-free and soil-containing systems in a comparison of two bacterial species. The method is predicated on the first-order dependence of the initial mineralization rate on the naphthalene concentration when the latter is below the Michaelis-Menten half-saturation constant (Km) for naphthalene for the organism under study. Rates and extents of mineralization were estimated by nonlinear regression analysis of data by using both a simple first-order model and a three-parameter, coupled degradation-desorption model described for the first time here. Bioavailability assays with two bacterial species (Pseudomonas putida ATCC 17484 and a gram-negative soil isolate, designated NP-Alk) gave dramatically different results. For NP-Alk, sorption limited both the rate and extent of naphthalene mineralization, in accordance with values predicted on the basis of the equilibrium aqueous-phase naphthalene concentrations. For strain 17484, both the rates and extents of naphthalene mineralization exceeded the predicted values and resulted in enhanced rates of naphthalene desorption from the soils. We conclude that there are important organism-specific properties which make generalizations regarding the bioavailability of sorbed substrates inappropriate.     

Amino acid sequence of a new mitochondrially synthesized proteolipid of the ATP synthase of Saccharomyces cerevisiae.

The purification and the amino acid sequence of a proteolipid translated on ribosomes in yeast mitochondria is reported. This protein, which is a subunit of the ATP synthase, was purified by extraction with chloroform/methanol (2/1) and subsequent chromatography on phosphocellulose and reverse phase h.p.l.c. A mol. wt. of 5500 was estimated by chromatography on Bio-Gel P-30 in 80% formic acid. The complete amino acid sequence of this protein was determined by automated solid phase Edman degradation of the whole protein and of fragments obtained after cleavage with cyanogen bromide. The sequence analysis indicates a length of 48 amino acid residues. The calculated mol. wt. of 5870 corresponds to the value found by gel chromatography. This polypeptide contains three basic residues and no negatively charged side chain. The three basic residues are clustered at the C terminus. The primary structure of this protein is in full agreement with the predicted amino acid sequence of the putative polypeptide encoded by the mitochondrial aap1 gene recently discovered in Saccharomyces cerevisiae. Moreover, this protein shows 50% homology with the amino acid sequence of a putative polypeptide encoded by an unidentified reading frame also discovered near the mitochondrial ATPase subunit 6 gene in Aspergillus nidulans.     

Phosphate transport in yeast mitochondria: purification and characterization of a mitoribosomal synthesis dependent proteolipid showing a high affinity for phosphate.

It is possible to obtain from yeast mitochondria a proteolipid able to bind phosphate, by two different procedures. One of them, generally used for lipid extraction, leads to the preparation of a more active crude proteolipid. This crude proteolipid has been purified by various chromatographic procedures and the active fraction, in phosphate binding, is always associated with cardiolipin. Its molecular weight seems to be close to 10000. The phosphate binding shows ligand saturation behavior and is inhibited by arsenate and N-ethylmaleimide; succinate is noninhibitory. This protein seems to be dependent on the mitoribosomal synthesis since it is not present in mitochrondria of mutant "petite colonie" and its amount largely decreases in mitochondria from yeast grown in the presence of chloramphenicol. It is possible to extract a proteolipid from the oligomycin sensitive ATPase, showing the same activity and properties. The hypothesis that this proteolipid acts as a part of the Pi carrier and constitutes the oligomycin-sensitive ATPase complex is discussed.     

Le prétendu rhinocéros de Nouvelle Calédonie est un marsupial (Zygomaturus diahotensis nov. sp.): Solution d'une énigmeet conséquences paléogéographiques

The first mammalian remain ever found in NewCaledonia is an upper tooth found by golddiggers in the Plio-Pleistocene terrace from the Diahot river. This tooth, given to the Muséum national d'Histoire naturelle (Paris) in 1876, was determined as a rhinoceros tooth and then completely forgotten. Its detailed study shows that it belongs to Zygomaturus, a large marsupial diprotodontid genus whose story is rather complicated. The Diahot tooth represents a new species of Zygomaturus, Z. diahotensis nov. sp., close to Z. trilobus from the Australian Pleistocene. That kinship suggests a Plio-Pleistocene land connection between Australia and New Caledonia, whereas till now New Caledonia was supposed to be separated from Australia since the end of the Cretaceous, because of the total absence of indigenous mammals, fossil or recent, in New Caledonia. The latest geological studies in the East Pacific do not contradict our hypothesis.     

Influence of soil quality in the larval habitat on development of Anopheles gambiae Giles.

Larval ecology is an important aspect of the population dynamics of anopheline mosquitoes (Diptera: Culicidae), the vectors of malaria. Anopheles larvae live in pools of stagnant water and adult fitness may be correlated with the nutritional conditions under which larvae develop. A study was conducted in Mbita, Western Kenya, to investigate how properties of the soil substrate of Anopheles gambiae breeding pools can influence development of this mosquito species. An. gambiae eggs from an established colony were dispensed into experimental plastic troughs containing soil samples from a range of natural Anopheles larval habitats and filtered Lake Victoria water. The duration of larval development (8-15 days), pupation rate (0-79%), and adult body size (20.28-26.91 mm3) varied among different soil types. The total organic matter (3.61-21.25%), organic carbon (0.63-7.18%), and total nitrogen (0.06-0.58%) levels of the soils were positively correlated with pupation rate and negatively correlated with development time and adult body size.     

New mutants resistant to glucose repression affected in the regulation of the NADH reoxidation

Spontaneous mutants resistant to vanadate, arsenate or thiophosphate were isolated from a haploid strain of Saccharomyces cerevisiae. These three anions have an inhibitory effect on some mitochondrial functions and at the level of glyceraldehyde 3-phosphate dehydrogenase, a glycolysis enzyme. All the selected mutants had the same phenotype: they were deficient in alcohol dehydrogenase I, the terminal enzyme of the glycolysis, and possessed a high content of cytochrome c oxidase, the terminal enzyme of the respiratory chain. Moreover, cytochrome c oxidase biosynthesis had become insensitive to the catabolite repression, while the biosynthesis of the other enzymes sensitive to this phenomenon were always inhibited by glucose. Metabolic effects of this pleiotropic mutation manifested themselves in the following ways. 1. Growth rate and final cell mass were enhanced, compared to the wild type, when cells were grown on glucose or on glycerol, but not on lactate or ethanol. 2. Growth under anaerobiosis was nil and mutants did not ferment. 3. Mitochondrial respiration of the mutant strains was identical to the wild type with succinate or 2-oxo-glutarate as substrate, and weak with ethanol. But with added NADH, respiration rate of the mutants was higher than that of the wild type and partially insensitive to antimycin, even when cells were grown in repression conditions. It is postulated that in mutants strains, NADH produced at the level of glyceraldehyde 3-phosphate dehydrogenase, failing to be reoxidized via alcohol dehydrogenase, could be reoxidized with a high turnover owing to the enhancement of the amount of cytochrome c oxidase. Since NADH reoxidation is partially insensitive to antimycin, a secondary pathway going from external NADH dehydrogenase to cytochrome c oxidase is suggested.     

Neurophysiological and behavioural evidence for an olfactory function for the dorsal organ and a gustatory one for the terminal organ in Drosophila melanogaster larvae

Multicellular electrophysiological responses from the dorsal organ on the cephalic lobes of third instar Drosophila melanogaster larvae (wild-type Canton S) stimulated with a cold-trapped banana volatile extract showed that this structure has an olfactory function in the fruit fly. Responses of the dorsal organ were also recorded to constituents of the banana volatile extract as they eluted from a gas chromatographic column (GC-coupled dorsal organ electrophysiology). The active chemostimulants were identified as 2-heptanone, isoamyl alcohol, hexyl acetate, hexanol and hexyl butyrate by gas chromatography-coupled mass spectrometry. Applying the same recording system to the terminal organ sensilla, no responses were obtained to either the banana volatile bouquet or its constituents. By contrast, high frequency multicellular responses were recorded in response to touching the terminal organ with the gustatory stimuli KCl and grapefruit juice; responses were absent on similar stimulation of the dorsal organ with either NaCl or KCl. This suggests a role for olfaction by the dorsal organ and for gustation by the terminal organ in Drosophila larvae.In a 7-mm high wind tunnel with a thin 1.2% agar floor, the Drosophila larvae showed odour-conditioned upwind responses in an air stream of 0.1 m/s bearing banana volatiles. Drosophila larvae responded best to the odour of cut bananas. A 1:1 mixture of the banana odour constituents 2-heptanone and hexanol (at either 50 or 100 &mgr;g source dose each) proved as attractive as the known larval attractants propionic acid and isoamyl acetate on their own at 100 &mgr;g, whereas hexanol and 2-heptanone on their own at a 100 &mgr;g source dose were less attractive. The stronger behavioural response to the banana volatile bouquet and to the binary mixture serves to underline the multireceptor nature of the dorsal organ response to food odour in Drosophila.