Some aspects of the natural history and food selection ofAvahi laniger

Two groups ofAvahi laniger were studied in the Forêt de Analamozoatra near Perinet in the eastern rainforest of Madagascar from August to October 1984. Overlap between the home ranges of neighbouring groups ofA. laniger was minimal. Group size ranged from one to four individuals with a median group size of two. In four out of ten groups a baby was born between August and September.A. laniger were most active after dusk and before dawn. They had an extended resting period around midnight. Their diet consisted mostly of leaves from at least 17 different plant species. They also ate flowers. Fruit eating was recorded twice. Leaves eaten had high contents of protein and sugar but did not contain alkaloids. The concentration of condensed tannins did not differ between food items and non-food items. There was no indication of competition with other prosimians that might explain their nocturnality.     

Horseradish peroxidase based bienzyme elctrode for isocitrate

Coimmobilized horseradish peroxidase and D-isocitrate dehydrogenase were fixed to an oxygen electrode to assemble a bienzyme electrode for isocitrate determination. The linear measuring range for isocitrate of the sensor is between 0.1 and 2.0 mmol. I^?1, the coefficient of variation (20 measurements) is 3.6%. 8 samples per hour can be assayed. With one sensor preparation 140 measurements can be carried out.     

Effects of histamine on bronchial artery blood flow and bronchomotor tone

The effects of aerosolized 5% histamine (10 breaths) on bronchial artery blood flow (Qbr), airflow resistance (RL), and pulmonary and systemic hemodynamics were studied in mechanically ventilated sheep anesthetized with pentobarbital sodium. Histamine increased mean Qbr and RL to 252 +/- 45 and 337 +/- 53% of base line, respectively. This effect was significantly different from base line for 30 min after challenge. The histamine-induced increase in RL was blocked by pretreatment with the histamine H1 receptor antagonist, chlorpheniramine, whereas the histamine-induced elevation in Qbr was prevented by the H2 antagonist, metiamide. Both responses were blocked only when both antagonists were present. Changes in Qbr were not directly associated with alterations in systemic and pulmonary hemodynamics or arterial blood gas composition. In vitro histamine caused a dose-dependent contraction of ovine bronchial artery strips that was prevented by H1 antagonist. The H2 agonist, impromidine, caused relaxation of precontracted arterial strips and was more potent and efficacious than histamine, whereas H1 agonists failed to elicit a relaxant response. Thus these findings indicate that histamine aerosol induces a vasodilation in the bronchial vascular bed; histamine has a direct effect on Qbr that is independent of alterations in RL, systemic and pulmonary hemodynamics, or arterial blood gas composition; and, histamine-induced bronchoconstriction is mediated predominantly by H1-receptors, whereas increased Qbr is controlled predominantly by H2-receptors, probably located in resistance vessels. This local effect of histamine on Qbr may have important implications in the pathophysiology of bronchial asthma and pulmonary edema.     

Dual effect of light on flowering and sprouting of rose shoots

Shade, caused by a dense leaf canopy in the light conditions of a normal greenhouse, reduced sprouting of the third axillary bud (from the top) on decapitated rose branches ( Rosa hybrida cv. Marimba) in comparison to less shaded buds on branches protruding above the canopy and sparsely spaced. Flowering of the third young shoot on shaded branches bearing 3 lateral shoots was totally inhibited. Mixed fluorescent and incandescent light in a growth chamber reduced sprouting of the third bud on decapitated rose branches in comparison to decapitated branches on rose plants held in fluorescent light of similar photon flux density. This was attributed to the higher R:FR ratio in fluorescent vs mixed light that reached the third bud, and in exposed vs shaded branches. Flowering of the third shoot was promoted by several factors: high photon flux density, 0.5 m M gibberellic acid (GA) or 0.2 m M benzyladenine (BA). BA was the most effective treatment. Treatments promoting flowering of the third shoot did not reduce growth or flowering of the upper shoots. However, spraying the uppermost shoot with BA suppressed the growth of the shoots below. It is concluded that light affects flowering in two ways. The effect on bud sprouting is related mainly to R:FR ratios, while the effect on flower development is related mainly to photon flux density. Cytokinins may substitute for the light effect on flower development.     

Many rhinovirus serotypes share the same cellular receptor.

Twenty-four human rhinovirus serotypes were grown and purified by centrifugation in metrizamide density gradients. These preparations had a lower buoyant density (1.24 g/cm3) and higher specific infectivities (1:24 to 1:240) than did rhinoviruses described previously (E. J. Stott and R. J. Killington, Annu. Rev. Microbiol. 26:503-524, 1972). Binding conditions in which the unique cellular receptors for virus attachment were saturated were determined for each serotype. Competition binding assays between pairs of serotypes allowed 20 of the 24 serotypes to be assigned to the same cellular receptor. The remaining four serotypes appeared to attach to a different cellular receptor. Since most serotypes were chosen for study at random, it seems likely that many of the yet unstudied rhinoviruses will share this common cellular receptor.     

The Fc portion of intact IgG blocks stimulation of human PBMC by anti-T3

The means by which normal human serum inhibits the activation of PBMC by OKT3 has been investigated. The Fc portion of intact IgG is shown to be the major inhibitor in human serum of this OKT3-induced stimulation. Furthermore, inhibition by IgG subclasses correlated with their ability to bind to the monocyte Fc receptor, i.e., IgG1 and IgG3 produced greater inhibition than IgG2 and IgG4, and this inhibition was competitive. In contrast, hypogammaglobulinemic serum, IgA, IgM, and F(ab')2 of IgG were not inhibitory relative to intact IgG or Fc of IgG. Because of the similarities between T3 and the idiotype-defined T cell receptor for antigen, these investigations suggest that IgG might modulate the interactions between the T cell recognition complex and anti-idiotype antibody, thus regulating the idiotype network.     

Selection on the male hemizygous genotype in arrhenotokous insects and mites

Arrhenotokously reproducing Hymenoptera and Acarina include many important natural enemies. This reproductive system offers the opportunity of selection on hemizygous (♂ ♂), with the attendant advantages of an unmasked genotype fully exposed to selection, in creased frequency of genotypes expressing rare genes, and enhanced discrimination of characters, in all-♂ populations produced by virgin (♀ ♀). Increased selection intensity and reduced genetic drift may offer additional advantages. The method is limited to characters displayed by (♂ ♂), and may require labor-intensive techniques and species-specific research. The method has been shown to be practicable withAphytis holoxanthus DeBach (Hymenoptera: Aphelinidae), an important parasite of the Florida red scale,Chrysomphalus aonidum (L.) (Homoptera: Diaspididae).      

Microbial transformations of galanthamin-precursors

Summary Galanthamin is a medical important alkaloid. Its chemical synthesis gives a racemic product in low yields. Starting with a belladinderivative an enzymatic ring closure should lead exclusively to a chiral product possibly with the native structure. Although this reactions type is unknown in preparative biotransformations a large number of microorganisms were tested, unfortunately without success. On the other hand in the screen transformation products were found resulting from specific dealkylations of the subtrate. The type of metabolite formed was dependent on the fungi utilized for the transformation. Additionally two N-oxides were formed by Septomyxa affinis, one in good yield. It is possible that the chirality of this compound can direct the ring closure preferentially or exclusively to the desired stereoisomer of narwedine.     

Transfer and amplification of a mutant beta-tubulin gene results in colcemid dependence: use of the transformant to demonstrate regulation of beta-tubulin subunit levels by protein degradation.

Total genomic DNA from a temperature-sensitive, colcemid-resistant Chinese hamster ovary (CHO) cell mutant expressing an electrophoretic variant beta-tubulin was used to transform wild-type CHO cells to colcemid-resistant cells at 37 degrees C. Southern blot analysis of the transformant demonstrated the three- to fivefold amplification of one of many beta-tubulin sequences compared with that of the wild type or mutant, thereby identifying a functional tubulin gene in CHO cells. This amplification of one tubulin-coding sequence resulted in a threefold increase in two beta-tubulin mRNA species, suggesting that both species may be encoded by a single gene. Pulse-chase experiments showed that in the transformant, total beta-tubulin was synthesized and degraded faster than in the revertant or wild-type cells, so that the steady-state levels of beta-tubulin and alpha-tubulin were unchanged in the transformant compared with those of wild-type, mutant, or revertant cells. Increased ratios of mutant to wild-type beta-tubulin made the transformant dependent on microtubule-depolymerizing drugs for growth at 37 but not 34 degrees C and supersensitive to the microtubule-stabilizing drug taxol at 34 degrees C.