Androgen influence on male mouse ultrasounds during courtship

Ultrasonic vocalizations are emitted by adult male mice (Mus musculus) shortly after an adult female or her odor are encountered, possibly as an early part of courtship behavior. Consistent with this hypothesis, it was found that castration of adult male mice increased the latency to first ultrasonic vocalization in response to an adult female. In addition, castrated males, subsequently injected once with 200 μg of testosterone propionate, reduced their latency, whereas oil-injected castrates did not.     

Pectinases and cellulases from plum curculio larvae: Possible causes of apple and plum fruit abscission

Plum curculio larvae, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), were assayed for pectic and cellulolytic enzymes. Larvae produce at least five pectic enzymes:pectin methyl-esterase, endo-polymethylgalacturonase, endo-polygalacturonase, pectin methyl-trans-eliminase, and polygalacturonate-trans-eliminase. Larvae also produce cellulase. Enzymes are released as larvae feed and are capable of causing fruit tissue maceration. One or more of these enzymes may be responsible for the premature abscission of plums and apples infested with plum curculio larvae.

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Résumé Les larves de Conotrachelus nenuphar, le Plum curculio ont été testées par la recherche des enzymes pectinolytiques et cellulolytiques. Ces larves produisent au moins cinq enzymes pectinases: pectine methyl-esterase, endo-polymethylgalacturonase, endo-polygalacturonase, pectine methyl trans-eliminase, et polygalacturonate-trans-eliminase. Elles produisent aussi de la cellulase. Les enzymes sont libérées alors que les larves se nourrissent et sont capables de provoquer une macération du tissu des fruits. Une ou plusieurs de ces enzymes peuvent être responsables de la chute prématurée des prunes et des pommes infestées par des larves de Plum curculio.

     

Regulation of the degradative pathway enzymes coded for by the TOL plasmid (pWWO) from Pseudomonas putida mt-2

Pseudomonas putida mt-2 carries a plasmid (TOL, pWWO) which codes for a single set of enzymes responsible for the catabolism of toluene and m- and p-xylene to central metabolites by way of benzoate and m- and p-toluate, respectively, and subsequently by a meta cleavage pathway. Characterization of strains with mutations in structural genes of this pathway demonstrates that the inducers of the enzymes responsible for further degradation of m-toluate include m-xylene, m-methylbenzyl alcohol, and m-toluate, whereas the inducers of the enzymes responsible for oxidation of m-xylene to m-toluate include m-xylene and m-methylbenzyl alcohol but not m-toluate. A regulatory mutant is described in which m-xylene and m-methylbenzyl alcohol no longer induce any of the pathway enzymes, but m-toluate is still able to induce the enzymes responsible for its own degradation. Among revertants of this mutant are some strains in which all the enzymes are expressed constitutively and are not further induced by m-xylene. A model is proposed for the regulation of the pathway in which the enzymes are in two regulatory blocks, which are under the control of two regulator gene products. The model is essentially the same as proposed earlier for the regulation of the isofunctional pathway on the TOL20 plasmid from P. putida MT20.     

Changes in native alcohol dehydrogenase activity ofDrosophila upon treatment with guanidine hydrochloride,urea and heat

Fifty-two isochromosomal lines ofDrosophila melanogaster were examined for the existence of additional genetic variations in ADH activity subsequent to treatment With guanidine hydrochloride, urea and heat. A wealth of hidden variation was discovered among and within the Mexican populations of the insect after treatment with the denaturants. Dedicated to the late Dr. Sarah B. Pipkin of Howard University.     

Particulate carbonic anhydrase in homogenates of human kidney.

About 2% of human kidney carbonic anhydrase (carbonate hydro-lyase, EC 4.2.1.1) has been found in particulate fractions. Its distribution in the particulate fractions obtained by differential centrifugation suggests that it may be concentrated in the brush border. The particulate enzyme is like red cell carbonic anhydrace C in its susceptibility to inhibition by anions. Particulate carbonic anhydrase is firmly bound to the membrane and is not released by incubation at pH 10.6 and 37 degrees C or by addition of Triton X-100 or deoxycholate. In 10% Triton X-100 at pH 11.3 and 37 degrees C, the particulate enzyme is inactivated with a half time of about 20 min, and this is at least an order of magnitude slower than the inactivation of soluble enzymes in the presence or absence of membranes. The soluble enzymes are inactivated within a few minutes at 25 degrees C in 3-4% sodium dodecyl sulfate, but the particulate enzyme is relatively stable under those conditions, and its half-time of inactivation at 14 degrees C with a detergent-protein ratio of 25 was about 24 h. Gel filtration with Ultragel AcA-44 in sodium dodecyl sulfate indicates that the membrane carbonic anhydrase has a molecular weight of less than 66 000, so its stability is not due to association with large membrane fragments or vesicles. These results suggest that the membrane enzyme may be a different isozyme than the soluble carbonic anhydrases. Although present in relatively small amounts, its localization on the membrane could give it functional significance.     

15-Azasteroid blockage of cell permeability and mitochondrial respiration

The 15-azasteroid, 1,10,11,11a-tetrahydro-11a-methyl-2$\text{H}$ naphth (1,2-$\text{g}$)indol-7-ol, inhibits the growth of the cell culture lines KB and L-M as well as several strains of bacteria. The inhibition of growth is reversed following removal of the steroid from the growth medium. Using in vitro grown L-M cells, the compound inhibited the transport of amino acids and uracil. The action was non-detergent like and at least 100 times more effective in terminating metabolite transport than sodium azide. The azasteroid inhibited the oxidation of glutamate in isolated rat liver mitochondria. The oxidation of succinate was not affected by the azasteroid alone but in the presence of glutamate, the azasteroid uncoupled the oxidation of succinate from the ADP-ATP control. It is suggested that the azasteroid may be acting directly on the electron transport system and/or acting indirectly through membrane perturbations which disrupts the electron transport process.     

Structure and assembly of lipid-containing viruses, with special reference to bacteriophage PM2 as one type of model system.

The simpler lipid-containing viruses (influenza, Semliki Forest, PM2) may have a phospholipid bilayer sandwiched between an outer shell of protein and an internal nucleocapsid possessing helical or icosahedral symmetry. Extensive physical and chemical studies have enabled us to form a more detailed picture of the structure of bacteriophage PM2 and controlled stepwise degradation of the virion has helped us to localize the four viral proteins. The surface protein (II) of PM2 is basic and interacts with the acidic phosphatidylglycerol of the bilayer to stabilize the membrane. The nucleocapsid protein (III) has proteolipid characteristics and may interact with the phospholipids in a hydrophobic fashion. The spikes are formed from protein I and the fourth protein (IV) is closely associated with the DNA. It is possible to reassemble the virus by reversing the degradation steps. Assembly has been especially useful in revealing the processes whereby the proteins and lipids interact to form the bilayer. Furthermore, results of in vivo studies of phospholipid synthesis and both in vivo and in vitro studies of viral protein synthesis have enabled us to form a reasonably complete picture of the biosynthesis of PM2.     

THE EFFECT OF DIABETES, INSULIN AND WALLERIAN DEGENERATION ON LEUCINE METABOLISM OF ISOLATED RAT SCIATIC NERVES

Abstract– ¹⁴CO₂ production and ¹⁴C incorporation into proteins was studied in isolated rat sciatic nerves during incubation with 0.1 mM-[1-¹⁴C]leucine. Rats were made diabetic with streptozotocin. Nerves from diabetic rats incubated with glucose oxidized more [¹⁴C]leucine than controls. This difference was abolished in the presence of insulin (1 mU/ml). The effects of diabetes and insulin on leucine oxidation could not be demonstrated in the absence of glucose. Insulin stimulated the incorporation of [¹⁴C] from leucine into proteins by nerves from controls and diabetic rats.
Nerves undergoing Wallerian degeneration showed a marked increase in DNA content and stimulated incorporation of [¹⁴C]leucine into proteins. ¹⁴CO₂ production from leucine proceeded at 75% of the rate observed in intact nerves. Neither insulin nor diabetes affected leucine metabolism in degenerating nerves.
Neither the extracellular space nor the concentration of free amino acids were significantly different in nerves obtained from control and diabetic rats, except for lower glutamine content in the latter.
In vitro leucine metabolism of nerves is affected by diabetes, insulin and the integrity of the axon. The Schwann cell is suggested as a possible site of the observed changes in leucine metabolism.