Sex-specific patterns in body condition and testosterone level changes in a territorial migratory bird: the Bluethroat Luscinia svecica

The Bluethroat Luscinia svecica is a migratory passerine that exhibits a socially monogamous pair bond and a high level of parental care. Males are territorial both when wintering and breeding whereas females are territorial only in winter. We investigated changes in body condition and testosterone levels during successive life-history stages and determined their relationships. Sex-specific patterns were observed in the variation in body condition and testosterone level. Male body condition varied mainly during the winter. It peaked at the onset of the prenuptial moult and then decreased, whereas it remained stable throughout breeding. In contrast, female body condition varied mainly during the breeding season. It increased during the prelaying stage and then abruptly decreased until fledgling provisioning. As in other monogamous and territorial passerines, testosterone levels in Bluethroat males were low during winter, increased in late winter, peaked during the prelaying stage and then decreased when provisioning young. In wintering females, territorial competition caused testosterone levels to rise. These females were able to produce territorial vocalizations and exhibit aggressive postures. Females showed higher mean testosterone levels than males when wintering whereas the opposite was observed when breeding. Our data from wintering female Bluethroats support the 'challenge hypothesis' under which high testosterone levels are associated with periods of social instability, and testosterone can regulate female territorial behaviour during this period.     

Intermediate filament proteins in mouse brain cells cultured in the presence or absence of fetal calf serum

Mesencephalic cells from 13-day-old mouse embryos were cultured either in the presence of serum or in a conditioned chemically defined medium. The types of intermediate filaments present in the cells in these two conditions were analysed by immunocytochemical means. It was found that in the absence of serum more than 95% of the cells contained neurofilaments and were therefore neuronal in nature. The remaining 5% were all stained with an antibody against vimentin. In the presence of serum the proportion of vimentin-positive cells increased very much. Double labelling experiments were performed in order to further characterize the vimentin-containing cells. It was found that 30–50% of these cells also contained the glial fibrillary acidic protein and were therefore likely to be astrocytes. No cell ever reacted with antigalactocerebrosides or antibodies against fibronectin excluding the presence or fibroblasts or mature oligodendrocytes in these cultures.     

Characterization of endozepine-related peptides in the central nervous system and in peripheral tissues of the rat

Endozepines represent a novel family of regulatory peptides that have been isolated by their ability to displace benzodiazepines from their binding sites. All endozepines derive from an 86 amino acid precursor polypeptide called diazepam binding inhibitor (DBI), which generates, through proteolytic cleavage, several biologically active endozepines. The aim of the present study was to compare the molecular forms of endozepines present in different regions of the rat brain and in various peripheral organs using an antiserum raised against the central (biologically active) region of DBI. Combination of HPLC analysis and RIA detection revealed the existence of two major forms (peaks I and II) of endozepine-immunoreactive peptides. The retention times of the two peaks (36 and 39 min, respectively) were identical in all tissues or organs tested. Western blotting analysis of cerebral cortex extracts confirmed the existence of two immunoreactive species with apparent molecular weights 4000 and 6000 Da, which respectively correspond to peaks I and II. Tryptic digestion of peaks I and II generated a single immunoreactive peptide that coeluted with the synthetic octadecaneuropeptide ODN [DBI(33–50)]. These results show that, in different parts of the brain and in various peripheral organs, DBI is rapidly processed to generate two peptides of apparent molecular weight of 4000 and 6000 Da, which both possess the biologically active determinant of endozepines.     

An Assessment of Genetic Diversity Within a Collection of Cassava (Manihot esculenta Crantz) Germplasm Using Molecular Markers

Cassava (Manihot esculenta Crantz) cDNA clones were used todetect restriction fragment length polymorphisms in a collectionof Manihot germplasm maintained as in vitro plants at ORSTOM,Montpellier. The collection consisted of mostly African cultivarsof M. esculenta, together with a few M. glaziovii Mueller vonArgau and M. caerulescens Pohl, and some interspecific hybridsbetween M. esculenta and M. glaziovii. The clones revealed significantlevels of polymorphism both within and between the species;sufficient to construct dendrograms indicating the genetic diversitywithin the collection.Copyright 1993, 1999 Academic Press Cassava, Manihot esculenta (Crantz), restriction fragment length polymorphisms, RFLPs, genetic diversity     

Extraction and characterisation of very highly methylated pectins from lemon cell walls

Pectins were extracted either by water from extruded lemon fibre or by hot acid from the raw lemon fibre. The amount of water-soluble polysaccharides from lemon plant cell walls was greatly increased after extrusion-cooking. The pectins obtained by extraction with water from the extruded fibre and the pectins extracted from the raw material by hot acid were studied. The water-soluble pectins obtained after extrusion-cooking had the distinctive feature of being very highly (92%) methylated; they were also particularly rich in arabinose side-chains. High molecular weight material coming from the “hairy” regions was isolated after digestion by an endo-polygalacturonase. Methylation analysis revealed the presence in both pectins of fairly branched (1 → 5)-linked arabinans and arabinogalactans of type I and II side-chains.     

Chemical structure of a prebiotic analog of adenosine

Upon heating a dry mixture of ribose and adenine, condensation products are formed. They were identified as isomers of N6-ribosyl-adenine (Fuller, Sanchez and Orgel, 1972). Due to the current interest in nucleotide analogs as potential constituents of primitive RNA catalysts, the products were further characterized by mass spectroscopy and proton NMR. Our results fully substantiate the previous proposals.