In vitro inhibition of the actions of basic FGF by a novel 16 amino acid peptide

We have examined the temperature-dependent effects of several organic compounds on the activity of the purified Ca²⁺-ATPase of erythrocytes. The monomeric enzyme was activated either by interaction with calmodulin or by oligomerization in the absence of calmodulin. Of the four homologous solute series studied including polyols, alkanols, aprotic solvents, and N-methyl derivatives of formamide and acetamide only polyols stabilized the enzyme over a broad range of concentration and temperature. Similarity of Ca²⁺-ATPase activity patterns at 25 and 37°C and in the presence of glycerol is in agreement with indirect, stabilizing interactions. Glycerol also protected the Ca²⁺-ATPase from thermal denaturation at 45°C. Within each homologous series, inhibitory effects increased with increasing solute concentration and with increasing structural similarity to detergents, indicating that direct destabilizing interactions are responsible for the observed inhibition. These were comparable to the destabilizing effect of urea. Oligomers were more resistant to all inhibitory solutes as compared to calmodulin-activated monomers suggesting that the nonpolar patches of the oligomerized enzyme are less accessible to solutes.     

Winter foraging patterns and voluntary hypothermia in the social caterpillar Eucheira socialis

1. Analysis of 28 years of weather data for the Sierra Madre Occidentals of Mexico showed that while flight, mating, and oviposition of the social caterpillar Eucheira socialis (Lepidoptera: Pieridae) occurred in the warmest and wettest months, much of the caterpillar’s feeding and growth occurred in the winter when nocturnal temperatures often fell below 0 °C. 2. Although daytime temperatures at the study site in midwinter were markedly warmer than overnight temperatures, colonies remained sequestered in their bolsas by day. Caterpillars initiated activity shortly after the onset of darkness and foraged overnight at temperatures as low as ? 2 °C. The remarkably low chill‐coma temperature recorded for this species has been reported previously only for a sub‐Antarctic caterpillar. 3. Temperature measurements on sunny days showed the interiors of bolsas to be thermally heterogeneous, with an average differential of 12 °C between the warmest and coolest regions of the structure. Although caterpillars clustered within the bolsas had body temperatures significantly greater than ambient, they exhibited voluntary hypothermia by day, seeking out and resting in the coolest pockets of the bolsas. 4. Voluntary hypothermia may influence growth rate adaptively and prevent acclimatisation to daytime temperatures that would have a negative effect on the caterpillar’s ability to locomote at low overnight temperatures.