Extension of life duration by dietary ethanol in Drosophila melanogaster: response to selection in two strains of different origins

Lines homozygous for the Adh ^S and Adh ^F alleles were extracted from a French and an African natural population of D. melanogaster. The lines from each geographic region were then crossed and the Mendelian F₂ constituted the first generation subjected to selection for an increase in adult survival in the presence of 2% ethanol.The responses to selection were similar in the two strains, in spite of their different ethanol tolerance. In less than 10 generations, life span with ethanol increased from about 7 to more than 12 days, with realized heritabilities of 0.14 and 0.18. This extension of longevity was also observed with other concentrations of ethanol but not with water alone. The increase in life span in presence of alcohol appears to result from unknown metabolic processes, which are not obligatorily related to the capacity of the flies to tolerate starvation, nor to their size, their lipid content of their ethanol tolerance. In the two lines, however, the Adh ^S allele was quickly eliminated, suggesting a selective advantage for the F allele.     

cDNA sequence and predicted primary structure of the gamma subunit from the ATP synthase from Chlamydomonas reinhardtii

The 1701-base nucleotide sequence (not including the poly(A) tail) of a cDNA for the gamma subunit of the ATP synthase from Chlamydomonas reinhardtii was determined. A start translation sequence, 23 bases in from the 5' end, initiates an 1074-base-long open reading frame. The sequence of the first 21 amino acids at the amino-terminal end of the mature gamma subunit from C. reinhardtii was determined and compared to the deduced amino acid sequence of the open reading frame. From this it was determined that the mature protein contains 323 amino acids, with the first 35 amino acids probably being part of the transit peptide. The length of the mature protein is the same as that for the mature gamma subunit from spinach, for which only a few of the amino acids of the transit peptide are known. The similarity of the two mature proteins at the nucleotide level is 56% while at the amino acid level it is 77%. In addition, the 3 cysteines, which in spinach are involved in the energy-linked catalytic functions of the ATP synthase, are conserved in the predicted amino acid sequence for the gamma subunit from C. reinhardtii. In contrast, the mature C. reinhardtii gamma subunit contains 3 additional cysteine residues not found in the spinach gamma subunit.     

5''-Nucleotidases in rat heart. Evidence for the occurrence of two soluble enzymes with different substrate specificities.

Chromatography of soluble proteins from rat heart on phosphocellulose columns separates two 5'-nucleotidases. The first to emerge from the column shows a preference for AMP over IMP as substrate, whereas the second shows a preference for IMP over AMP. The properties of the IMP-preferring enzyme, including the conditions under which it is eluted from phosphocellulose columns, show it to be the enzyme studied by Itoh, Oka & Ozasa [Biochem. J. (1986) 235, 847-851]. The kinetic properties of the AMP-preferring enzyme indicate that it is likely to be the enzyme responsible for the production of adenosine under conditions of hypoxia and increased work load, and with metabolic stresses such as a high load of acetate.     

Serum alpha-tocopherol, all-trans retinol, total lipids and cholesterol in the black rhinoceros (Diceros bicornis)

1. Mean concentration of serum alpha-tocopherol (Vitamin E) in 28 free-living black rhinoceroses sedated during translocation in Zimbabwe was 1.92 (SD, 0.43) mg/l. 2. Alpha-tocopherol was not detectable (less than 0.15 mg/l) in five captive black rhinoceroses held at London Zoo. 3. Circulating levels of all-trans retinol (Vitamin A) were not different between the two groups. 4. The low level of alpha-tocopherol in captive rhinoceroses suggests a risk of acute haemolytic anaemia.     

Calorimetric and Fourier transform infrared spectroscopic studies on the interaction of glycophorin with phosphatidylserine/dipalmitoylphosphatidylcholine-d62 mixtures

Glycophorin has been isolated in pure form from human erythrocyte membranes and reconstituted into lipid vesicles composed of binary mixtures of bovine brain phosphatidylserine (PS) and acyl-chain perdeuterated dipalmitoylphosphatidylcholine (DPPC-d62). The effect of protein on lipid melting behavior and order has been monitored with differential scanning calorimetry and Fourier transform infrared spectroscopy (FT-IR). The phase diagram for PS/DPPC-d62 is consistent with that previously reported for PS/DPPC (Stewart et al. (1979) Biochim. Biophys. Acta 556, 1-16) and indicates that acyl chain perdeuteration does not greatly alter the lipid mixing characteristics. The use of deuterated lipid allows the examination of lipid order by FT-IR of each lipid component in the binary mixtures as well as in the ternary (lipid/lipid/protein) systems. Addition of glycophorin to a 30:70 PS/DPPC-d62 binary lipid mixture results in a preferential glycophorin/PS interaction leading to bulk lipid enriched in DPPC-d62. This is revealed in two ways: first, through cooperative calorimetric transitions increased in temperature from the binary lipid system and second, through FT-IR melting curves of the DPPC-d62 component which shows transitions increased in both onset and completion temperatures in the presence of protein. In addition, non-cooperative melting events are observed at temperatures below the onset of phase separation. The FT-IR data are used to assign these non-cooperative events to the melting of the PS component. For the 50:50 lipid mixture with protein, two transitions are observed in the DSC experiments. The IR results indicate that both lipid components are involved with the lower temperature event.     

Antibody-directed liposomes. Determination of affinity constants for soluble and liposome-bound antifluorescein

We have used the binding of liposomes conjugated with antifluorescein antibody specific for fluorescein isothiocyanate-modified erythrocytes as a model for multivalent antigen-antibody interactions. We examined a series of liposome preparations which were conjugated to between 0 and 332 active antibodies per liposome. The antigen binding capacity and mean intrinsic affinity of the soluble and conjugated antibody were determined by fluorescence quenching of carboxyfluorescein. Liposome-cell interaction data were fitted with a Scatchard-type equation. Functional affinity of liposomes for cells was up to 1000-fold greater than the intrinsic affinity of the antibody for soluble ligand. Analysis for binding at high cell concentrations revealed that liposome-induced cell agglutination reduces the number of available binding sites per cell.     

Studies of Fe3+ transport across isolated intestinal brush-border membrane of the mouse

Mouse intestinal brush-border membrane vesicles take up iron from media containing 59Fe3 +-nitrilotriacetic acid. The iron uptake by the vesicles represents accumulation of iron which relates to an osmotically active space. Uptake is linearly related to vesicle protein concentration and is inhibited by low incubation temperature and low medium free Fe3+ concentrations. Experiments with the lipid soluble iron ligand 8-hydroxyquinoline and with Triton X-100 imply that the uptake is rate limited by membrane transport.     

Role of membranes and energy-producing reactions in cellular processing of insulin in primary cultures of rat hepatocytes

Incubation of primary cultures of rat hepatocytes with the local anesthetics, procaine or lidocaine, had little or no effect on insulin uptake or degradation but caused an inhibition of insulin-stimulated glycogenesis. While exposure of cultures to the amines, monodansylcadaverine or CH3NH2, resulted in significant dose-dependent decreases in glycogenesis, only monodansylcadaverine (an inhibitor of receptor clustering) decreased uptake whereas CH3NH2 (a lysosomotropic agent) caused increases in both insulin uptake and degradation. When cells were treated with agents which inhibit glycolysis (NaF, 2-deoxy-D-glucose) or oxidative metabolism (2,4-dinitrophenol, carbonyl cyanide m-chlorophenyl hydrazone, NaN3, antimycin A), pronounced inhibitions of each of the bioactivities studied (syntheses of glycogen, protein, lipid) were observed, but only the glycolytic inhibitors decreased insulin uptake. These results suggest that insulin is internalized by an endocytotic process involving receptor clustering and requiring metabolic energy derived from glycolysis. The post-receptor biosynthetic processes involved in the expression of the biological activities of insulin (syntheses of glycogen, protein, lipid) require energy produced by oxidative metabolism while the degradation of insulin is carried out by nonlysosomal mechanisms which are not energy-requiring.     

Determination of ethanol partition coefficients to the interior and the surface of dipalmityl-phosphatidylcholine liposomes using deuterium nuclear magnetic resonance spectroscopy

The binding of ethanol-d6 to dipalmityl-phosphatidylcholine liposomes (DPPC) can be separated into two processes, namely, ethanol in the bilayer and on the surface of the bilayer. For the deuterons of the methylene group, the T2 of both bound states is shorter than the respective preexchange lifetime (tau beta) and therefore the amount of ethanol bound to both sites can be determined from the decrease in the methylene intensity resonance in the presence of DPPC. For the methyl resonance, however, only the T2 of deuterons on ethanol bound to the surface is less than its tau beta and the amount of surface bound ethanol-d6 can be determined. Subtraction yields the amount of ethanol bound within the bilayer. The partition coefficient for internally bound ethanol remains constant from 0 to 3.5 m ethanol. Surface binding is, however, highly cooperative.