Showing papers by "Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto published in 1992"

Systematics, phylogeny and biogeography of the Meliponinae (Hymenoptera, Apidae): a mini-review

Abstract: Dans cet article de synthese sont discutees les principales propositions concernant la systematique, la phylogenese et la biogeographie des Meliponinae, ainsi que la polarite et l'importance de quelques caracteres morphologiques. Bien que tout un ensemble de synapomorphies (par ex les corbicules, le rastellum, l'articulation du basitarse posterieur pres de l'extremite anterieure de l'apex du tibia) suggerent que les Meliponinae constituent un groupe cophyletique des Apinae, des Bombinae et des Euglossinae, leurs relations avec ces sous-familles restent floues

Effects of blockade of 5-HT2 receptors and activation of 5-HT1A receptors on the exploratory activity of rats in the elevated plus-maze.

Abstract: Acute administration of gepirone, a 5-HT1A agonist, caused a dose dependent (1–10 mg/kg, IP) reduction in the locomotor activity (open and closed arms) of rats tested in the elevated plus-maze. However, rats housed in individual cages and submitted to chronic treatment with gepirone (10 mg/kg PO) showed a marked increase in the percentages of number and time spent in the open arms as compared to controls. These results are compatible with the idea that the antiaversive effect due to long-term treatment with 5-HT1A agonists is the result of a progressive desensitization of the somatodendritic 5-HT autoreceptor with the consequent recovery of firing rate of 5-HT neurons along with an activation of normosensitive postsynaptic 5-HT neurons. Ketanserin caused a biphasic effects on the exploratory behavior of rats in the plus-maze. The lower dose (0.5 mg/kg) decreased the aversion to the open arms and the higher dose (1.0 mg/kg) caused an unspecific decrease in the overall activity of the animals. Ketanserin is supposed to have antagonistic action on 5-HT2 and on α-adrenergic receptors. As prazosin (0.5–1.0 mg/kg), an α-adrenergic receptor blocker, did not present any significant effect in the present work it is suggested that the effects of the lower dose of ketanserin was due to its high antagonistic action on 5-HT2 receptors.

An AC biosusceptometer to study gastric emptying.

Abstract: A simple AC susceptometer was developed to study the gastric emptying when test meals labeled with 10% of a harmless magnetic tracer were ingested. The instrument allows the determination of T 1/2 of the stomach emptying with good precision compared to measurements with gamma camera and 99m Tc in the test meal.

Influence of calcium on the blood pressure and renal effects of stevioside.

Abstract: 1. The effects of verapamil (V, 0.015 mg/min, i.v.) or CaCl2 (800 mEq/l, 0.025 ml kg-1 min-1, i.v.) on renal function and mean arterial pressure (MAP) were evaluated in male Wistar rats weighing 280-320 g during treatment with stevioside (S, 16 mg kg-1 h-1, i.v.). 2. Verapamil administered to 10 rats significantly increased the hypotensive effect of stevioside on MAP (control, 124 +/- 0.77; S, 96 +/- 1.50; S+V, 67 +/- 0.70 mmHg) and on fractional sodium excretion (control, 0.76 +/- 0.05; S, 1.56 +/- 0.10; S+V, 2.72 +/- 0.25%). Urinary flow, reported as percent glomerular filtration rate (V/GFR), and renal plasma flow (RPF) increased slightly but not significantly during stevioside plus verapamil administration. 3. In contrast, infusion of CaCl2 in 10 rats pretreated with stevioside induced a marked attenuation of MAP (control, 119 +/- 1.83; S, 70 +/- 1.12; S+CaCl2, 109 +/- 1.60 mmHg) and RPF (control, 16.73 +/- 3.76; S, 34.33 +/- 2.55; S+CaCl2, 17.20 +/- 2.87 ml min-1 kg-1). The diuresis and natriuresis induced by stevioside were also inhibited by simultaneous administration of CaCl2. 4. These data are consistent with the view that stevioside acts on arterial pressure and renal function as a calcium antagonist, as is the case for verapamil.

Nest re-use and communal nesting in Microthurge corumbae (Hymenoptera, Megachilidae), with special reference to nest defense

Abstract: Observations on the nesting activities ofMicrothurge corumbae, carried out at the University Campus of Ribeirao Preto, Sao Paulo, Brazil, from 1977 to 1981, indicated that 61.9 % of nests were re-used by succeeding generations. Re-use by one generation was more frequent than by two generations, and re-use by a third was observed only once. Nests were re-used by one or several females. Single females were more frequently in the first re-use. In these cases nest re-use did not differ essentially from the solitary foundation of a new nest, except for the adoption of a pre-existing nest without excavation. In multifemale nests, analysis of relative age (wing wear), ovarian and spermathecal conditions of associated females and the content of nests at excavation indicated that the social pattern in such colonies is communal. There is some evidence that the associated females are relatives. The chalcidoid waspLeucospis was the principal nest parasite, and ants of the genusCrematogaster were nest predators. In multifemale nests, the rate of parasitism was significantly lower than in solitary nests, indicating that nest-sharing resulted in improved nest defense. On the other hand, the absence of predation on immatures of the first generation of M.commbae in multifemale nests suggests that such nests are also more resistant to attack by predators.

Anodontites trapesialis : a biological monitor of organochlorine pesticides

Abstract: The mussel Anodontites trapesialis (Lam, 1819) was used as an indicator of organochlorine pollutants in the Pardo River, located in the municipality of Ribeirao Preto (21° 07′S and 47° 45′W), State of Sao Paulo, Brazil.

Notas prévias sobre a bionomia de Ptilotrigona lurida (Hymenoptera, Apidae, Meliponinae): associação de leveduras em polen estocado.

Abstract: Polen estocado nos ninhos da abelha Ptilotrigona lurida foi encontrado em associacao com a levedura Candida sp., que parece promover a desidratacao do polen e conferir outras vantagens. De acordo com os resultados dos experimentos, pode-se dizer que: Candida sp. nao e contaminante casual do polen estocado por P. lurida, em todos os ninhos, em varias localidades da Amazonia, essa associacao estava presente; os testes indicaram que Candida sp. promove a dissecacao do polen e, possivelmente, confere vantagens na ensilagem do alimento, considerando-se a grande quantidade de polen estocada nos ninhos e que Candida sp. confere vantagens contra a invasao de moscas da familia Phoridae, importante predador de polen estocado nos ninhos de Meliponinae.