Kisspeptin and the seasonal control of reproduction in hamsters

Reproduction is a complex and energy demanding function. When internal and external conditions might impair reproductive success (negative energy balance, stress, harsh season) reproductive activity has to be repressed. Recent evidence suggests that these inhibitory mechanisms operate on Kiss1-expressing neurons, which were recently shown to be implicated in the regulation of GnRH release. Hamsters are seasonal rodents which are sexually active in long photoperiod and quiescent in short photoperiod. The photoperiodic information is transmitted to the reproductive system by melatonin, a pineal hormone whose secretion is adjusted to night length. The photoperiodic variation in circulating melatonin has been shown to synchronize reproductive activity with seasons, but the mechanisms involved in this effect of melatonin were so far unknown. Recently we have observed that Kiss1 mRNA level in the arcuate nucleus of the Syrian hamster is lower in short photoperiod, when animals are sexually quiescent. Notably, intracerebroventricular infusion of Kiss1 gene product, kisspeptin, in hamsters kept in short photoperiod is able to override the inhibitory photoperiod and to reactivate sexual activity. The inhibition of Kiss1 expression in short photoperiod is driven by melatonin because pinealectomy prevents decrease in Kiss1 mRNA level in short photoperiod and melatonin injection in long photoperiod down regulates Kiss1 expression. Whether melatonin acts directly on arcuate Kiss1 expressing neurons or mediates its action via interneurons is the subject of the current investigations.     

Recent advances in the cryopreservation of shoot-derived germplasm of economically important fruit trees of Actinidia, Diospyros, Malus, Olea, Prunus, Pyrus and Vitis

This paper presents the advances made over the last decade in cryopreservation of economically important vegetatively propagated fruit trees. Cryopreservation protocols have been established using both dormant buds sampled on field-grown plants and shoot tips sampled on in vitro plantlets. In the case of dormant buds, scions are partially dehydrated by storage at − 5 °C, and then cooled slowly to − 30 °C using low cooling rates (c.a. 1 °C/h) before immersion in liquid nitrogen. After slow rewarming and rehydration of samples, regrowth takes place either through grafting of buds on rootstocks or excision of apices and inoculation in vitro. In the case of shoot tips of in vitro plantlets, the cryopreservation techniques employed are the following: controlled rate cooling procedures involving slow prefreezing followed by immersion in liquid nitrogen or vitrification-based procedures including encapsulation–dehydration, vitrification, encapsulation–vitrification and droplet-vitrification. The current status of cryopreservation for a series of fruit tree species including Actinidia, Diospyros, Malus, Olea, Prunus, Pyrus and Vitis is presented. Routine application of cryopreservation for long-term germplasm storage in genebanks is currently limited to apple and pear, for which large cryopreserved collections have been established at NCGRP, Fort Collins (USA), using dormant buds and in vitro shoot tips, respectively. However, there are a growing number of examples of pilot scale testing experiments under way for different species in various countries. Progress in the further development and application of cryopreservation techniques will be made through a better understanding of the mechanisms involved in the induction of tolerance to dehydration and cryopreservation in frozen explants.     

Presence of Hemitragus aff. cedrensis (Mammalia, Bovidae) in the Iberian Peninsula: Biochronological and biogeographical implications of its discovery at Bolomor Cave (Valencia, Spain)

The discovery of new material in Late Pleistocene levels at Bolomor Cave (Valencia, Spain) raises some questions about the presence of the most ancient record of Hemitragus cedrensis in the peninsula, and its dispersal out of Provence. The morphology and dimensions of some lower teeth confirm the identification of H. aff. cedrensis. Moreover, it presents strong similarities, both morphological and metrical, with the specimens from Caune de l’Arago and bau de l’Aubesier (end of OIS 7 to OIS 5e) rather than with the population from the eponymous locality. The data suggest a dispersal event out of Provence towards the Iberian Peninsula during the Eemian. This dispersal was not stopped by natural barriers such as large rivers, or mountains. The results presented here confirm the biochronological interest of the genus Hemitragus for the Late Pleistocene in Mediterranean Europe.     

Molecular identification of yeast,lactic and acetic acid bacteria species during spoilage of tchapalo,a traditional sorghum beer from Côte d’Ivoire

Yeasts, lactic and acetic acid bacteria are responsible of microbial spoilage of alcoholic beverages. However species involved in deterioration of sorghum beer produced in Côte d’Ivoire has not been investigated. This study was carried out to identify species of yeast, LAB and AAB during spoilage of tchapalo in order to define the best strategy for beer preservative. Thus, a total of 210 yeasts, LAB and AAB were isolated from samples of tchapalo stored at ambient temperature and at 4 °C for 3 days. Based on PCR–RFLP of the ITS region and the sequencing of D1/D2 domain, yeast isolates were assigned to seven species (Saccharomyces cerevisiae, Candida tropicalis, Rhodotorula mucilaginosa, Trichosporon asahii, Kluyveromyces marxianus, Meyerozyma guilliermondii and Trichosporon coremiiforme). During the storage at ambient temperature and at 4 °C, S. cerevisiae was the predominant species (>?76%). Excepted R. mucilaginosa, occurrence of non-Saccharomyces species was sporadic. LAB species detected in fresh samples using molecular methods were Pediococcus acidilactici, Lactobacillus paracasei, Lb. curvatus, Lb. fermentum and Weisssella paramesenteroides. P. acidilactici was the dominant species (47.8%) followed by Lb. paracasei (17.5%). W. paramesenteroides and Lb. fermentum were not detected during the spoilage at ambient temperature while at 4 °C W. paramesenteroides and Lb. paracasei have not been detected. For AAB, the species found were Acetobacter pasteurianus sub paradoxus and Acetobacter cerevisiae. These species were common to all samples during spoilage and A. pasteurianus sub paradoxus was the most frequently detected.     

Mitochondria-targeted cationic porphyrin-triphenylamine hybrids for enhanced two-photon photodynamic therapy

The proof of concept for two-photon activated photodynamic therapy has already been achieved for cancer treatment but the efficiency of this approach still heavily relies on the availability of photosensitizers combining high two-photon absorption and biocompatibility. In this line we recently reported on a series of porphyrin-triphenylamine hybrids which exhibit high singlet oxygen production quantum yield as well as high two-photon absorption cross-sections but with a very poor cellular internalization. We present herein new photosensitizers of the same porphyrin-triphenylamine hybrid series but bearing cationic charges which led to strongly enhanced water solubility and thus cellular penetration. In addition the new compounds have been found localized in mitochondria that are preferential target organelles for photodynamic therapy. Altogether the strongly improved properties of the new series combined with their specific mitochondrial localization lead to a significantly enhanced two-photon activated photodynamic therapy efficiency.     

Variability in storage response within a coffee (Coffea spp.) core collection under slow growth conditions

Anin vitro core collection of African coffee germplasm, structured in 32 diploid diversity groups, was established and conserved under slow growth for 3 years (6 subcultures). The initial objective was to store twenty accessions per group, with four replicates per accession. A statistical model was developed to analyse observations of survival rates within each diversity group. The goodness of fit of the model was shown. Survival analysis indicated a broad variability of the accessions in their response to the storage conditions and confirmed the importance of structuring the coffee complex down to the intraspecific level. Intra- and inter-group differences had consequences on the genetic representativity of thein vitro core collection. For practical purposes, conservation was carried on when the intra-group genetic drift was less than 50%.Abbreviations BA 6-benzyladenine - CAR Central African Republic - CIRAD Centre de Coopération Internationale en Recherche Agronomique pour le Développement - FAO Food and Agriculture Organization - IBPGR International Board for Plant Genetic Resources - IDEFOR-DCC Institut Des Fôrets - Département Café Cacao - ORSTOM Institut français de recherche scientifique pour le développement en coopération     

The trypanosome VSG expression site encodes adenylate cyclase and a leucine-rich putative regulatory gene.

African trypanosomes are protozoan parasites that evade the host immune system by varying their dense antigenic coat. The Variant Surface Glycoprotein (VSG) is expressed exclusively from telomere-linked expression sites that contain in addition to the VSG gene, a number of open reading frames termed Expression Site Associated Genes (ESAGs). Here we demonstrate by complementation of a yeast mutant deleted for adenylate cyclase (cyr-1), that an ESAG from Trypanosoma equiperdum encodes an adenylate cyclase. Furthermore, we report that adjacent to adenylate cyclase in the expression site, is a separate open reading frame that encodes a protein sequence motif similar to the leucine-rich repeat regulatory domain of Saccharomyces cerevisiae and Schizosaccharomyces pombe adenylate cyclases. The finding of two adjacent open reading frames homologous to a single enzyme in yeast suggests that the two expression site encoded proteins may interact to regulate adenylate cyclase activity during the course of an infection.     

PHACCS,an online tool for estimating the structure and diversity of uncultured viral communities using metagenomic information

Background  

Phages, viruses that infect prokaryotes, are the most abundant microbes in the world. A major limitation to studying these viruses is the difficulty of cultivating the appropriate prokaryotic hosts. One way around this limitation is to directly clone and sequence shotgun libraries of uncultured viral communities (i.e., metagenomic analyses). PHACCS, Phage Communities from Contig Spectrum, is an online bioinformatic tool to assess the biodiversity of uncultured viral communities. PHACCS uses the contig spectrum from shotgun DNA sequence assemblies to mathematically model the structure of viral communities and make predictions about diversity.