Song and immunological condition in male barn swallows (Hirundo rustica)

Male secondary sexual characters may have evolved as intra-or intersexual signals of male phenotypic or genetic quality.In birds, singing performance may have the function to honestlyreveal health and vigor of individual males. Infectious diseasesand poor body conditions would therefore be expected to negativelyinfluence singing performance. Since bird pathogens are knownto elicit both a humoral and a cell-mediated immune response,it can be predicted that a negative relationship exists betweensinging performance and activity of the immune system. Thisprediction was tested for the first time in this correlationalstudy. The relationships between song rate and features andhematological variables (concentration of leukocytes in peripheralblood, ratio of gamma-globulins to total plasma proteins, bloodcell sedimentation rate, hematocrit) and body condition wereanalyzed in a population of bam swallows (Hirundo rustica).Song rate was negatively correlated with lymphocyte concentrationand with the ratio of gamma-globulins to plasma proteins. Spectrographicanalysis showed that features of song were not significantlycorrelated with hematological variables or body condition. Thelevel of circulating testosterone was not correlated with songrate nor hematological variables. This study is the first toshow a correlation between a bird's singing performance andhematological profile and suggests that song rate of male barnswallows may reflect their health status. Song in this speciesmight thus have evolved because it allows prospecting femalesto assess aspects of phenotypic and/or genetic quality of potentialmates     

Benzodiazepine-induced voraciousness in cats and inhibition of amphetamine-anorexia

The effect of different benzodiazepines on food intake was studied in cats which had been trained to eat their daily food within 3 hours, under conditions in which emotional factors were not present. When benzodiazepines were administered (at a dose ranging from 0.1 to 3 mg/Kg) before feeding, they increased both the total amount of food eaten and also the rate at which food was injested. When they were administered at the end of the feeding period, these compounds made the animals resume eating voraciously. The order of decreasing potency of the benzodiazepines tested was: oxazepam, N-methyl-lorazepam, diazepam, chlordiazepoxide, pinazepam, medazepam. Oxazepam (3 mg/Kg) stimulated maximally the food intake, even when administered up to 12 hours before feeding. Finally, oxazepam antagonized the anorexigenic effect of d-amphetamine, but did not influence amphetamine-induced hyperactivity and stereotyped behavior.     

Platelet glycohydrolase activities: Characterization and release

Granules containing acid hydrolases have been detected in human platelets but have not been thoroughly characterized. We have studied the activity and characteristics of glycohydrolases present in normal human platelets, evaluated their release upon stimulation with thrombin, and assessed the contribution of platelet - released lysosomal contents to the glycohydrolase activity present in normal serum. Platelets contained a remarkable glycohydrolase activity with a prevalence of β - N-acetylhexosaminidase. All glycohydrolases were released to some extent upon stimulation with thrombin and contributed to the glycohydrolase activity found in human serum. α-Mannosidase and α-galactosidase were partially inactivated after release by a mechanism as yet undefined. In addition, thrombin stimulation affects the intraplatelet isoenzyme pattern of β-N-acetylhexosaminidase by producing the appearance of a new form.     

Binding of [3H]-2-isobutyl-3-methoxypyrazine to cow olfactory mucosa

The odorant 2-isobutyl-3-methoxypyrazine binds to cow olfactorymucosa homogenate. The complex, which can be separated by gelfiltration on Sephadex G-100, appears to be made up of fourmacromolecular species. No significant binding has been measuredwith respiratory epithelium. The binding disappears after treatmentwith proteolytic enzymes, or in a SDS containing buffer, thusindicating that the receptors are proteins. Complete loss ofbinding capacity has been also observed as a consequence ofdialysis: this suggests the involvement of a low molecular weightcomponent.     

Phenotypic Changes Across a Geographic Gradient: The Case of Three Sympatric Dolphin Species

Phenotypic changes in the mammalian mandible can occur at different spatial and temporal scales. We investigated mandibular size and shape variation in three extant closely related dolphins (Cetacea, Odontoceti): Tursiops truncatus, Stenella coeruleoalba and Delphinus delphis in order to test the hypothesis that similar phenotypic changes occur across the same geographical gradient. Our data included 219 specimens representative of the following geographic locations: the Mediterranean Sea, the eastern north Atlantic and the North Sea. Each mandibula was photographed laterally and spatial positioning of eight homologous 2D landmarks was recorded. After applying generalised Procrustes analysis (GPA), intraspecific variation was first investigated between sexes and among populations to allow further pooling of samples. Size and shape differences among populations and species were investigated through multivariate ordination techniques (PCA), Procrustes ANOVA and allometric analyses. In all three species, Mediterranean populations clearly differed in mandible shape from the extra-Mediterranean ones. Among the three, the direction of geographic phenotypic changes was significantly similar in the striped and common dolphin, while the bottlenose dolphin was the most divergent species, differing both in size and allometric trajectory. Shape variation of the two former species highlighted a morphological convergence in the Atlantic, and a phenotypic divergence in the Mediterranean. Shape differences among the three dolphin species were interpreted in the light of different prey preferences, feeding strategies and habitat partitioning to avoid direct competition.