Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Effect of Alpha and Beta blockers on the hydrosmotic response of the isolated skin of the toad Bufo arenarum to adrenaline, vasopressin and angiostensin II?. The hydrosmotiec effect of epinephrine (E), vasopressin (VP) and angiotensin II (AT) were measured gravimetrically in untreated and phentolamine ?or propranolol? treated toad skin. The existence of autoinhibition for high doses of E, previously reported to exist in frog skin, was confirmed in toad skin in the present series of experiments. Beta-adrenergic blocking agents significantly inhibit the hydrosmotic effect of submaximal doses of E, but it was found that, in contrast to previous reports, phentolamine also blocks such effects. No explanation exists as yet for this observation. Neither alpha-nor beta-blockers affect the response to VP or AT, showing that different receptors exist in toad skin for catecholamine and peptide hormones.

Valid morphological characters in the systematics of the genus Sicarius (Walckenaer 1847) (Aranae: Sicariidae)?. The genus Sicarius has 23 species: 6 from south Africa, 1 from San Salvador and Costa Rica, 1 from Galapagos Islands, 1 from Brazil, 8 from Chile, and 3 from Peru. One of them S. terrosus (Nicolet 1849) is the Type-Species, it is also found in Peru and Argentina. In Argentina besides S. terrosus were collected S. rupestris (Holmberg 1881); S. patagonicus (Simon in Mello-Leitao 1919) and S. irregularis (Mello-Leitao 1940). Here is stablished the following synonymy: Sicarius irregularis (Mello-Leitao 1940) = Sicarius patagonicus (Simon in Mello-Leitao 1919). The characters mentioned up to now are discussed and the new ones are given: proportional length and breadth of the cephalotorax; distance of the medium eyes and lateral ones; prominence of the eye tubercle; form and position of the stridulating organ in the femur of the palpus; form of the tibia of the male palpus; form of the spermathecae. All these are illustrated with photographs made with the electronic microscope (scanning), the drawing of the spermathecae and tho map with the distribution of the species collected in Argentina.

Review of the Argentine species of the genus Bosmina Baird grouped in the subgenus Neobosmina Lieder (Crustacea: Cladocera)?. Morphological and biometrical characters of a lot of Neobosmina specimens from several localities of Argentina are studied. The importance and variability of such characters are also discussed. Three species are identified: Bosmina (N.) hagmanni Stingelin. The new combination B. huaronensis from B. lonfispina var. huaronensis Delachaux and a list of synonyms for each species is proposed. These species can be differentiated by the combination of at least 14 characters of different values for females and males. The males of these three species hitherto unknown are described; so the similarity of the shape of the male postabdomen in the subgenus Neobosmina is confirmed. It is also discussed the geographical distribution based on the author?s original records and on those of the literature.

Biological notes about a new Conchostraca (Crustacea, Branchiopoda) of high altitude?. Leptestheria tucumanensis, a new species related to L. titicacae Harding, is described from high altitude lakes and ?bogs? of the Cumbres Calehaquíes, in Tucumán province, Argentina. General ecological factors are noted. Physical factors are mainly related to high altitude (+ 4,250 m). Chemical and biotic factors are extremely variable within short distances. Two main types of sites exist: 1) highly alkaline lakes, and 2) acid pools within phanerogamic bogs. Distribution from lake to lake in the area during a 3 year period is quite variable, as it is from year to year within the same lake, possibly due to the interaction of biotic and abiotie factors. The ambiguous systematic position of both related species, L. titicacae and L. tucumanensis, is discussed, mainly as they share characters of Leptestheriidae and Cyzicicac.

?Aditional data about vital cycle of Polybetes pythagoricus (Holmberg, 1874) (Aranae, Eusparassidae)?. Two offsprings (called series 1 and 2) of the same female of P. pythagoricus are studied under laboratory conditions.

Some considerations about Oligochaeta reproduction current studies?. The present state of the problem of the reproduction among the Oligochaeta is outlined here, with special reference to the uniparental mode. The methods of exploration in this sphere are abriged and an eventual classification of the distinet ways of sexual reproduction among the Oligochaeta is tentatively sketched. André?s assumption about a tendenecy toward a parthenogenesis genetically predetermined among the Oligochaeta and the data given by Gates concerning the parthenogenetic polymorphism of the genitalia are particularly cmphasized.

Preliminary results of the study of fat body lipids and hemolymph in insects?. Knowledge of lipids metabolism in insects, might give a better base to understand nutritional studies. Fat body and haemolimph lipids of Diatraea saccharalis (F.), were studied, and some preliminary results are presented here.

?Chilean Asteroidea of the family Odontasteridae? This work deals with the study of Chilean Asteroidea belonging to the family Odontasteridae Verrill, 1899. Diagnosis of the family, genera and species are indicated. In Chile there are the following genera: Asterodon and Odontaster; species: Asterodon granulosus Perrier; Asterodon singularis (Müller & Troschel) and Odontaster penicillatus (Philippi). Data on distribution, occurrence and ecological notes are provided.

Effects of oxytocin inhibitors on the natripheral and hydrosmotic responses of toad skin to oxytocin and angiotensin II?. Previous reports from this laboratory demonstrated that 8-Leu-angiotensin Il, an analog of angiotensin 11 (AT), significantly blocked the natriferic and hydrosmotic responses of toad skin to AT, without affecting the responses to neurohypophyseal hormones. The present work was undertaken in order to characterize the effects of oxytocin (0) analog on these responses to both 0 and AT. 4-Leu-oxytocin was found to be ineffective in inhibiting the response to 0, whereas 1-6 alpha deaminocystathionine-2-0-methyltyrosine-oxytocin (MeDCOT-1), although devoid of effects per se, proved to have a dual behavior: while inhibiting the natriferic effects of peptide hormones (0 and AT) without affecting that of catecholamines (norepinephrine), it seems to unspecifically potentiate the hydrosmotic response to all of these agents. These results dramatically contrast those previously reported by other authors for the same compound, and provide additional evidence for the existence of separate receptors for peptide hormones and catecholamines in toad skin.

Annotated list of material collected on Uruguayan coasts, transported by camalotes from the Paraná River?. Large accumulation of ?camalotes? (water hyacinths), Eichhornia crassipes stranded on the Uruguayan shore of the Río de la Plata estuary as a consequence of floodings at the Paraná river. Animals transported by the floating plants have been collected on the Uruguayan strands, particulary at Juan Lacaze, and identified. One colubrid, Helicops leopardinus, and three amphibians, Lysapsus limellus, Pseudis paradoxa and a Leptodactilidae recorded have not previously been mentioned for the Uruguayan fauna. Similar strandings of masses of floating vegetals recorded by various authors in the past, are commented.