Juvenile hormone titre and regulation in the cockroachDiploptera punctata

Summary Titres of juvenile hormone (JH) have been determined in both hemolymph and whole body extracts of femaleDiploptera punctata during the first gonotrophic cycle using a method employing gas chromatography/mass spectrometry for qualitative and quantitative analysis. JH III is the sole JH found in both adult and last instarD. punctata. Maximum values of 1500 ng/ml (6M) were observed at the middle of the gonotrophic cycle, when basal oocyte growth rate was greatest. Changes in rates of JH release in vitro by corpora allata paralleled closely the changes in JH titre, suggesting that biosynthesis is a major regulator of titre. JH levels per animal were calculated from observed JH titres, and at certain time points in the gonotrophic cycle JH levels obtained from analysis of whole bodies were significantly greater than those predicted from hemolymph titres. These results suggest the existence of a nonhemolymph JH pool inD. punctata. Decay in JH titre after allatectomy of 5 day females has also been studied. Following a rapid initial decline, the rate of decay slowed appreciably 4 h post-operation. Thus, use of a first-order rate constant to estimate half-life of JH significantly underestimated the longevity of the hormone. The apparent persistence of JH following allatectomy may be due to the existence of a nonhemolymph JH pool.     

The susceptibility to exercise-induced muscle damage increases as rats grow larger

Summary Glucose-6-phosphate dehydrogenase and N-acetyl--glucosaminidase activities were both elevated after eccentric exercise indicating that this type of exercise causes muscle damage. Muscle damage as measured by glucose-6-phosphate dehydrogenase activity in the vastus intermedius was greater and occurred later in larger rats indicating that the susceptibility to muscle damage is increased and the repair process delayed in older and larger animals.     

A new semisynthetic ergot peptide alkaloid: DCN 203-922

Summary We report the synthesis, stereochemistry and preliminary pharmacological evaluation of DCN 203-922, a novel ergot alkaloid of the cyclol type, which contains in its peptide moiety the uncommon amino acid L-allo-isoleucine.Part of this paper was reported by this author at the Herbstversammlung der Schweizerischen Chemischen Gesellschaft, Bern, in October 1986.     

Inner ear of the coelacanth fish Latimeria has tetrapod affinities

Auditory reception in elasmobranchs, teleosts and amphibians may be mediated by various inner-ear sensory epithelia 1–3, including the basilar papilla, which seems to be the precursor of the cochlea in mammals. The origin of the basilar papilla remains a major unsolved problem for understanding the evolution of hearing in terrestrial vertebrates4–6. Study of living species indicates that the basilar papilla is a unique feature of tetrapods 6,7, but palaeonto-logical data indicate that this epithelium as well as a middle ear, is already present in crossopterygian fish 8–10. However, no basilar papilla has been found in the only living crossopterygian species, the coelacanth Latimeria chalumnae 11. I have re-examined the inner ear of adult and embryonic Latimeria and find a membranous specialization which resembles in structure, position and innerva-tion pattern the basilar papilla of tetrapods, in particular amniotes. No epithelium comparable to the basilar papilla was found in lungfish. I suggest that the basilar papillae of Latimeria and tetrapods are homologous and evolved only once in their common ancestor.     

Regulation of cellulose synthesis in Acetobacter xylinum by cyclic diguanylic acid

Cellulose is the most abundant renewable carbon resource on earth and is an indispensable raw material for the wood, paper, and textile industries. A model system to study the mechanism of cellulose biogenesis is the bacterium Acetobacter xylinum which produces pure cellulose as an extracellular product. It was from this organism that in vitro preparations which possessed high levels of cellulose synthase activity were first obtained in both membranous and soluble forms. We recently demonstrated that this activity is subject to a complex multi-component regulatory system, in which the synthase is directly affected by an unusual cyclic nucleotide activator enzymatically formed from GTP, and indirectly by a Ca (2+) -sensitive phosphodiesterase which degrades the activator. The cellulose synthase activator (CSA) has now been identified as bis-(3' 5')-cyclic diguanylic acid (5'G3'p5'G3'p) on the basis of mass spectroscopic data, nuclear magnetic resonance analysis and comparison with chemically synthesized material. We also report here on intermediary steps in the synthesis and degradation of this novel circular dinucleotide, which have been integrated into a model for the regulation of cellulose synthesis.     

Protective effect of vitamins against trichothecene toxicity towardsSaccharomyces cerevisiae

Summary Several trichothecene mycotoxins were shown to inhibit the growth ofSaccharomyces cerevisiae. This effect was most pronounced with the macrocyclic trichothecenes, especially verrucarin A. Much less growth inhibition was observed with T-2 toxin. Verrucarol, diacetoxyscirpenol, acetyl T-2 toxin, HT-2 toxin, T-2 tetraol and neosolaniol were inactive at a concentration of 75 g of toxin per disc. Incubation ofS. cerevisiae with verrucarin A together with vitamins resulted in a decrease in toxicity. Pyridoxine-HCl, Ca-pantothenate, thiamine-HCl and -tocopheryl acetate were amongst the most potent of the vitamins tested which reversed growth inhibition, overcoming the inhibitory potential of the toxins.9 December 1986The authors thank Dr J. Behrend, Makor Company, Israel, for a generous gift of verrucarin A and roridin A.