Ecological Transitions in Grouping Benefits Explain the Paradox of Environmental Quality and Sociality.

Both benign and harsh environments promote the evolution of sociality. This paradox-societies occur in environments of such contrasting quality-may be explained by the different types of benefits that individuals receive from grouping: resource defense benefits that derive from group-defended critical resources versus collective action benefits that result from social cooperation among group members. Here, we investigate cooperative behavior in the burying beetle Nicrophorus nepalensis along an elevational gradient where environmental quality (climate and competition) varies with altitude. We show that climate (temperature) and competition (both intra- and interspecific) independently and synergistically influence sociality via different grouping benefits that vary along the gradient. At low elevations where interspecific competition for resources is intense, groups gain from the collective action benefit of increased interspecific competitive ability. In contrast, pairs have higher fitness at intermediate elevations where intraspecific competition for resources is greatest because resource defense is the key grouping benefit. However, groups and pairs have similar fitness at high elevations, suggesting that there is no grouping benefit in such physiologically challenging environments. Our results demonstrate that sociality is favored for different reasons under a range of environmental conditions, perhaps explaining why animal societies occur in environments of such contrasting quality.

Osmotic stress alters the intracellular distribution of non-erythroidal spectrin (fodrin) in bovine aortic endothelial cells.

Cell swelling is known to result in unfolding of membrane invaginations and restructuring of F-actin. The effect of cell swelling on the intracellular distributions of other cytoskeletal proteins that constitute the submembrane cortical cytoskeleton is virtually unknown. This study focuses on the effects of cell swelling on non-erythroidal spectrin (fodrin, also known as spectrin II), a predominant component of the membrane cytoskeleton. The intracellular distribution of spectrin in vascular endothelial cells was studied by optical sectioning using a 3-D deconvolution microscopy system. Our results show that once bovine aortic endothelial cells (BAECs) reach confluency, the non-erythroidal spectrin is localized in the submembrane regions of the cells. Analysis of the intensity profiles of the non-erythroidal spectrin under isotonic and hypotonic conditions show that: (a) the width of the submembrane spectrin staining increases gradually with time within the first 5 minutes after the osmotic shock; (b) significant recovery is observed after 10 minutes even if the cells are maintained in hypotonic medium, and (c) spectrin distribution is altered by disrupting F-actin with latrunculin A but not by stabilizing F-actin with jasplakinolide. We suggest that cell swelling results in partial translocation of the submembrane spectrin to the cytosol and that it may play a major role in initiation of swelling-induced cellular events.

[Effects of fungal elicitor on cell status and taxol production in cells suspension cultures of Taxus chinesis var. mairei].

Effects of fungal elicitor on cell redox status and taxol production were studied in suspension cultures of Taxus chinesis var. mairei in the late exponential stage. The results show that fungal elicitor induced oxygen burst, changes of the cell redox status, alkalinization of medium and the fluctuation of the activity of redox enzymes with a sequence. The content of protein representing the quantity of enzymes increased. The activity of SOD increased quickly after treatment by fungal elicitor and that of POD could be kept at a higher level in contrast to the control. The activity of CAT was inhibited at first and followed by an obvious increase, while the activity of PAL was promoted. The taxol yield was 5 folds of the control, reaching to 67 mg/L.