Sex pheromone perception in male pine sawflies,Neodiprion sertifer (Hymenoptera; Diprionidae)

Summary Electroantennographic and single sensillum recordings were performed on male pine sawfly, Neodiprion sertifer, antennae. Responses to the sex pheromone component (2S, 3S, 7S)- 3,7-dimethyl-2-pentadecenyl (diprionyl) acetate (SSS:OAc), to the behavioral inhibitor (2S, 3R, 7R)-diprionyl acetate (SRR:OAc), to the six other enantiomers of diprionyl acetate, and to the biosynthetic precursor diprionol were recorded. Responses to trans-perillenal, a monoterpene identified in female gland extracts and to (2S, 3S, 7S)-diprionyl propionate (SSS:OPr), a field attractant for N. sertifer and some related sawfly species were also recorded.EAG recordings demonstrated a high antennal sensitivity to SSS:OAc and to SSS:OPr. A somewhat lower response was elicited by SRR:OAc.Single sensillum recordings revealed 8–12 different cells firing in each sensillum, corresponding to the number of cells observed in earlier morphological investigations. Out of these cells all, except one, responded to SSS:OAc and to SSS:OPr. No differences in the response to the two components could be observed. The largest amplitude cell in each sensillum was specifically tuned to the behavioral antagonist, SRR:OAc. The pheromone perception system encountered in male pine sawflies thus differs clearly from that observed in moths.Abbreviation EAG electroantennogram - OAc acetate - OPr propionate     

An endogenous ligand for the central sulfonylurea receptor

An endogenous ligand for the rat central sulfonylurea receptor has been evidenced in the rat central nervous system. The characteristics of this ligand (extractibility, non-dialysability, chromatographic behaviour on different media, sensitivity to proteases) indicate that it is a neutral to slightly basic peptide.     

NADPH-specific and NADH-specific xylose reduction is catalyzed by two separate enzymes in Pachysolen tannophilus

Summary Pachysolen tannophilus contains — in addition to an NADPH-linked xylose reductase — a separate NADH-linked one, in this respect differing from the yeast Pichia stipitis. Both enzyme proteins can conveniently be separated from each other by either ion exchange chromatography or chromatofocusing.     

Implementation of periodic acid-thiosemicarbazide-silver proteinate staining for ultrastructural assessment of muscle glycogen utilization during exercise

Summary Distribution of glycogen particles in semithin and ultrathin sections of biopsy samples from human muscles subjected to either short- or long-term running were investigated using PAS and Periodic Acid-ThioSemiCarbazide-Silver Proteinate (PA-TSC-SP) staining methods. Glycogen particles were predominantly found immediately under the sarcolemma or aligned along the myofibrillar Iband. After long-term exhaustive exercise type-1 fibers with a few or no glycogen particles in the core of the fibers were frequently observed. The subsarcolemmal glycogen stores of these depleted type-1 fibers were about three times as large as after exhaustive short-time exercise. Another indication of utilization of subsarcolemmal glycogen stores during anaerobic exercise was that many particles displayed a pale, rudimentary shape. This observation suggests fragmental metabolization of glycogen. Thus, depending on type of exercise and type of fiber differential and sequential glycogen utilization patterns can be observed.     

Moments and order statistics of extinction times in multitype branching processes and their relation to random selection models

We investigate the circumstances under which the moments of the order statistics of the extinction times of a set of independent branching processes exist. This extends a result of Schuster and Sigmund,Bull. math. Biol. 46, 11–17, 1984, which was found in a special random selection model. Furthermore we discussed existence of the expectation of extinction times of multitype branching processes and extend well known results for irreducible processes to the reducible case.     

Late enzymes of vindoline biosynthesis

From differentiated plants of Catharanthus roseus (L.) G. Don we have isolated a specific enzyme of the vindoline biosynthetic pathway catalysing the S-adenosylmethionine-dependent methylation of 11-O-demethyl-17-O-deacetyl-vindoline. The enzyme we named S-adenosyl-L-methionine : 11-O-demethyl-17-O-deacetylvindoline 11-O-methyltransferase. This transferase exhibits a high substrate specificity. Obviously the O-methylation at C-11 precedes the O-acetylation at the C-17 position during the biosynthesis of vindoline.A second enzyme was detected which hydrolyses the acetyl function of vindoline. The distribution of this acetylesterase in C. roseus plants demonstrates that the enzyme is not specifically associated with the vindoline distribution in the plant material. Most probably this enzyme plays no essential role in the biosynthesis of vindoline.     

Late enzymes of vindoline biosynthesis. Acetyl-CoA: 17-O-deacetylvindoline 17-O-acetyl-transferase

From differentiated plants of Catharanthus roseus (L.) G. Don, a specific enzyme was isolated and named acetyl-CoA : 17-O-deacetylvindoline 17-O-acetyltransferase, acting on the biosynthetic formation of the Aspidosperma type alkaloid vindoline.The enzyme shows a high selectivity towards different substrates. The acetyl-CoA-dependent transferase also catalyses the reverse reaction by hydrolysis of the 17-O-acetyl group of vindoline in the presence of free CoA. This enzyme is localized only in vindoline-containing plant parts, but was so far not detectable in cell suspension cultures of C. roseus. The enzyme allows the synthesis of labelled vindoline with high specific activity, applicable for instance as tracer for radioimmunoassays of vindoline.