Defensive secretion of the tenebrionid beetle,Blaps mucronata: Physical and chemical determinants of effectiveness

Summary The primary components of the defensive secretions ofBlaps mucronata (Tenebrionidae) are two quinones (methyl-p-benzoquinone and ethyl-p-benzoquinone) and the hydrocarbon 1p-n-tridecene. The hydrocarbon is shown, by comparison with longer- and shorter-chainn-alkanes and 1-n-alkenes, to be optimally suited as carrier of the quinones, and as a surfactant that promotes spread of secretion over the beetle's body following discharge from the gland openings at the abdominal tip. As shown from repellency tests with ants (Monomorium pharaonis) and topical irritancy tests with cockroaches (Periplaneta americana), the antiinsectan potency of the secretion derives as much from the hydrocarbon as from the quinones.Paper no. 82 of the seriesDefensive Mechanisms of Arthropods     

Do clones degenerate over time? Explaining the genetic variability of asexuals through population genetic models

Background  

Quest for understanding the nature of mechanisms governing the life span of clonal organisms lasts for several decades. Phylogenetic evidence for recent origins of most clones is usually interpreted as proof that clones suffer from gradual age-dependent fitness decay (e.g. Muller's ratchet). However, we have shown that a neutral drift can also qualitatively explain the observed distribution of clonal ages. This finding was followed by several attempts to distinguish the effects of neutral and non-neutral processes. Most recently, Neiman et al. 2009 (Ann N Y Acad Sci.:1168:185-200.) reviewed the distribution of asexual lineage ages estimated from a diverse array of taxa and concluded that neutral processes alone may not explain the observed data. Moreover, the authors inferred that similar types of mechanisms determine maximum asexual lineage ages in all asexual taxa. In this paper we review recent methods for distinguishing the effects of neutral and non-neutral processes and point at methodological problems related with them.     

Preparative and analytical separation of the zopiclone enantiomers and determination of their affinity to the benzodiazepine receptor binding site

We report the preparative separation of rac-zopiclone using malic acid as the resolving agent. Furthermore, two different methods for the analytical determination of zopiclone enantiomers by HPLC on chiral stationary phases are described. The benzodiazepine receptor binding of the isolated enantiomers was investigated. Half-maximal inhibitory concentrations of (+)- and (?)-zopiclone were 21 or 1,130 nmol/liter, respectively, indicating a more than 50 times higher affinity of the (+)-enantiomer toward the receptor. © 1993 Wiley-Liss, Inc.     

Kurze Mitteilungen

Ohne Zusammenfassung     

A 5, 6-dimethoxylated flavone in the leaf resin of Adenostoma sparsifolium

A new flavone 5,6-dimethoxy-3,7,4′-trihydroxyflavone was isolated from the external leaf resin of Adenostoma sparsifolium and identified by spect     

Parental Body Mass as a Determinant of Egg Size and Egg Output in an Arctiid Moth (Utetheisa ornatrix)

Females of the moth Utetheisa ornatrix (family Arctiidae) mate preferentially with larger males. As a consequence, females have larger sons and daughters, which have been shown to be more acceptable in courtship and more fecund, respectively. We demonstrate that mating with larger males results in accelerated oviposition by the female on the day after mating and that females are intrinsically prone to lay larger eggs in the first days after mating. Both these additional size-dependent effects have potential adaptive consequences.     

Characterization of the isolated calcium-binding vesicles from the green alga Mougeotia scalaris,and their relevance to chloroplast movement

The calcium-binding vesicles from the green alga Mougeotia scalaris were isolated and characterized after staining in vivo by neutral red or rhodamine B. They were found to possess, a protonated group with a pK_a-9.9, typifying phenolic hydroxyl groups; upon titration, both, phenolic compound(s) and vital dye were concomitantly released from the vesicular matrix. A shift in peak absorbance from 450 nm to 540 nm of the vitally stained vesicles indicated that the neutral form of neutral red was bound to the vesicular, matrix as an intermediate form, stabilized via intermolecular hydrogen bonds to the phenolic compound(s). Up to 8.5.10⁹ dye molecules were calculated to be adsorbed to a mean-size vesicle. Analysis of Langmuir adsorption isotherms, indicated that there were two binding sites each for both neutral red and rhodamine B. The isolated vesicles were devoid of calcium, probably because vesicular calcium, bound to the vesicle matrix, was displaced upon dye binding. Dye adsorption to the vesicles in vivo results in substantial inhibition of the reorientational movement of the Mougeotia chloroplast and is explained by dye-mediated disorder of the cellular calcium homoeostasis.Abbreviations NR neutral red - RB rhodamine B - SDS sodium dodecyl sulfate This paper is part of the Ph.D. thesis of F. Grolig at Justus-Liebig-Universität Giessen, FRG