Neuromuscular action of venom from the South American colubrid snake Philodryas patagoniensis

Snakes of the opisthoglyphous genus Philodryas are widespread in South America and cause most bites by colubrids in this region. In this study, we examined the neurotoxic and myotoxic effects of venom from Philodryas patagoniensis in biventer cervicis and phrenic nerve-diaphragm preparations and we compared the biochemical activities of venoms from P. patagoniensis and Philodryas olfersii. Philodryas patagoniensis venom (40 microg/mL) had no effect on mouse phrenic nerve-diaphragm preparations but caused time-dependent neuromuscular blockade of chick biventer cervicis preparations. This blockade was not reversed by washing. The highest concentration of venom tested (40 microg/mL) significantly reduced (p<0.05) the contractures to exogenous acetylcholine (55 microM and 110 microM) and K(+) (13.4 mM) after 120 min; lower concentrations of venom had no consistent or significant effect on these responses. Venom caused a concentration- and time-dependent release of creatine kinase (CK) from biventer cervicis preparations. Histological analysis showed contracted muscle fibers at low venom concentrations and myonecrosis at high concentrations. Philodryas venoms had low esterase and phospholipase A(2) but high proteolytic activities compared to the pitviper Bothrops jararaca. SDS-PAGE showed that the Philodryas venoms had similar electrophoretic profiles, with most proteins having a molecular mass of 25-80 kDa. Both of the Philodryas venoms cross-reacted with bothropic antivenom in ELISA, indicating the presence of proteins immunologically related to Bothrops venoms. RP-HPLC of P. patagoniensis venom yielded four major peaks, each of which contained several proteins, as shown by SDS-PAGE. These results indicate that P. patagoniensis venom has neurotoxic and myotoxic components that may contribute to the effects of envenoming by this species.     

Phosphate starvation affects the synthesis of outer membrane proteins in Thiobacillus ferrooxidans

The outer membrane protein (omp40) component from the chemolithoautotrophic acidophilic Thiobacillus ferrooxidans is apparently regulated by the external pH and the concentration of phosphorus. Its amino-terminal sequence showed little identity with the Escherichia coli OmpC, OmpF or PhoE porins, but was 38.5% identical to the outer membrane channel-forming protein NosA from Pseudomonas stutzeri, whose expression is also regulated environmentally. In addition, the partial amino acid sequence of T. ferrooxidans omp40 showed between 34 and 38% identity with the amino-terminal end of the small outer membrane proteins Rck and PagC from Salmonella typhimurium and OmpX from Enterobacter cloacae.     

Resistance of the AF-28 sorghum variety to Contarinia sorghicola

The variety AF-28 of Sorghum bicolor Pers and the hybrid R-1090 were compared in relation to the sorghum midge, Contarinia sorghicola (Coquillet), (Diptera: Cecidomyidae) in two counties of the State of São Paulo. They were compared in seven successive monthly trials beginning in September 1972. Averages of 252 and 137 adult flies emerged per head of the hybrid R-1090 in Campinas and Jaboticabal respectively, while 2.9 and 0.8 emerged from AF-28. The damage was graded with a visual scale from 0 to 4. Average damage grades of 3.5 and 3.3 were attributed to the hybrid R-1090 in Campinas and Jaboticabal respectively, while the variety AF-28 had averages of 0.5 and 0.3, respectively.

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Résumé La variété AF-28 et l'hybride R-1090 de Sorghum bicolor Pers. ont été comparés à différentes époques de l'année et en deux localités différentes de l'Etat de Sâo Paulo, Brésil.On n'a pas constaté d'interaction variété x époque ou variété x lieu.AF-28 a prouvé sa résistance à toutes les époques, aussi bien dans un lieu que dans l'autre; l'hybride par contre s'est montré grandement susceptible.Des moyennes de 252,2 et 136,7 mouches par panicule ont été observées pour l'hybride R-1090 à Campinas et à Jaboticabal contre 2,9 et 0,8 seulement par panicule de AF-28. Le préjudice a été estimé visuellement selon une échelle de 0 à 4. Des préjudices d'une valeur moyenne de 3,5 et 3,3 ont été attribués à l'hybride R-1090 à Campinas et à Jaboticabal respectivement, alors que simultanément la variété AF-28 ne subissait que des préjudices évalués à 0,5 et 0,3 respectivement.Quatre espèces de microhyménoptères parasites de Contarinia sorghicola ont été récoltées au cours de ce travail: Eupelmus popa et trois espèces différentes du genre Tetrastichus.

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Part of a thesis presented to the School of Sciences of Bauru for fulfilment of the requirement for the degree of Doctor of Science. This research was financed by the Project 72/1471 of the agreement UNIÃO-ESTADO-FAPESP and by CNPq Project 12910/73.     

Ultrastructural changes in naturally aged Pinus pinea seeds

The decline of germination observed after storage of Pinus pinea L. seeds up to 35 years at room temperature was accompanied by an increase in their ability to leak reducing sugars, probably as a consequence of membrane alterations due to senescence. Results of studies of the cell ultrastructure of viable and non-viable seeds before and after imbibition indicate that such is the case. Noticeable changes occurred in the ultrastructure of endosperm and embryo cells with germinability loss, even in the unimbibed condition. The main alterations were spherosome coalescence, plasmalemma separation from the cell wall and chromatin aggregation.     

Acknowledging uncertainty in evolutionary reconstructions of ecological niches

Reconstructing ecological niche evolution can provide insight into the biogeography and diversification of evolving lineages. However, comparative phylogenetic methods may infer the history of ecological niche evolution inaccurately because (a) species' niches are often poorly characterized; and (b) phylogenetic comparative methods rely on niche summary statistics rather than full estimates of species' environmental tolerances. Here, we propose a new framework for coding ecological niches and reconstructing their evolution that explicitly acknowledges and incorporates the uncertainty introduced by incomplete niche characterization. Then, we modify existing ancestral state inference methods to leverage full estimates of environmental tolerances. We provide a worked empirical example of our method, investigating ecological niche evolution in the New World orioles (Aves: Passeriformes: Icterus spp.). Temperature and precipitation tolerances were generally broad and conserved among orioles, with niche reduction and specialization limited to a few terminal branches. Tools for performing these reconstructions are available in a new R package called nichevol.