The Site Specificity of Two Species of Gregarina in Tenebrio molitor Larvae

The site specificity of the apicomplexans Gregarina cuneata and Gregarina sleini , in larval Tenebrio molitor was investigated. Gregarina cuneata was found to inhabit the anteriormost region of the larval midgut, while G. steini was restricted to the posterior portion of the intestine. The site specificity of the pair was conserved in single and concurrent infections. Interspecific interactions do not seem to be presently responsible for the resource partitioning by the 2 gregarine species. Key words. Gregarina, site specificity, Tenebrio molitor.     

Effects of muscle glycogen and plasma FFA availability on human metabolic responses in cold water.

The purpose of this study was to investigate whether simultaneous alterations in the availability of plasma free fatty acids and muscle glycogen would impair the maintenance of thermal balance during cold water immersion in humans. Eight seminude subjects were immersed on two occasions in 18 degrees C water for 90 min or until rectal temperature (Tre) decreased to 35.5 degrees C. Each immersion followed 2.5 days of a specific dietary and exercise regimen designed to elicit low (LOW) or high glycogen levels (HIGH) in large skeletal muscle groups. Nicotinic acid (1.6 mg/kg) was administered for 2 h before and during immersion to inhibit white adipose tissue lipolysis. Biopsies from the vastus lateralis showed that the glycogen concentration before the immersion was significantly lower in LOW than in HIGH (223 +/- 19 vs. 473 +/- 24 mmol glucose units/kg dry muscle). However, the mean rates of glycogen utilization were not significantly different between trials (LOW 0.62 +/- 0.14 vs. HIGH 0.88 +/- 0.15 mmol glucose units.kg-1.min-1). Nicotinic acid dramatically reduced plasma free fatty acid levels in both trials, averaging 127 +/- 21 mumol/l immediately before the immersion. Cold water immersion did not significantly alter those levels. Plasma glucose levels were significantly reduced after cold water immersion to a similar extent in both trials (18 +/- 4%). Mean respiratory exchange ratio at rest and during immersion was greater in HIGH than LOW, whereas there were no intertrial differences in O2 uptake. The calculated average metabolic heat production during immersion tended to be lower (P = 0.054) in LOW than in HIGH (15.3 +/- 1.9 vs. 17.5 +/- 1.9 kJ/min).(ABSTRACT TRUNCATED AT 250 WORDS)     

Behavioral adaptations for raiding in the slave-making ant,Polyergus breviceps

We studied recruitment behavior of the slavemaking ant Polyergus breviceps,which typically raids colonies of Formica gnava.The first test series demonstrated the importance of social context, by showing that recruitment was high during raiding, but virtually absent during preraid circling and during the return trip after a slave raid. The second test series showed that Formicapupae (alone or together with adults) must be present for workers of Polyegrusto recruit nestmates. The third test series demonstrated that panic alarm by raided Formicais caused by a pheromone, and we suggest that adults of Formicamay be the source of this secretion. Finally, the fourth test series showed that formic acid is lethal to adults of Formicabut has almost no adverse effect on Polyergus.This relative immunity by Polyergusmay enable them to remain organized while entering nests of Formicaduring slave raids.     

Lineage, migration, and morphogenesis of longitudinal glia in the Drosophila CNS as revealed by a molecular lineage marker

Previous studies described three different classes of glial cells in the developing CNS of the early Drosophila embryo that prefigure and ensheath the major CNS axon tracts. Among these are 6 longitudinal glial cells on each side of each segment that overlie the longitudinal axon tracts. Here we use transformant lines carrying a P element containing a 130 bp sequence from the fushi tarazu gene in front of the lacZ reporter gene to direct beta-galactosidase expression in the longitudinal glia. Using this molecular lineage marker, we show that 1 of the "neuroblasts" in each hemisegment is actually a glioblast, which divides once symmetrically, in contrast to the typical asymmetric neuroblast divisions, producing 2 glial cells, which migrate medially and divide to generate the 6 longitudinal glial cells. As with neuroblasts, mutations in Notch and other neurogenic genes lead to supernumerary glioblasts. The results indicate that the glioblast is similar to other neuroblasts; however, the positionally specified fate of this blast cell is to generate a specific lineage of glia rather than a specific family of neurons.