Maintenance of sexual immaturity in male mice and bucks by immunization against N-terminal peptides of the follicle-stimulating hormone receptor

The follicle-stimulating hormone is one of the two pituitary hormones that control fertility in both sexes. In the male, receptors for FSH (FSHR) are only expressed on testicular Sertoli cells. FSH plays different roles during the male life; it functions as a growth factor during development and sustains spermatogenesis in adults. However, the exact role of this hormone as an initiator of male fertility is not fully understood and few data are available concerning its involvement during the peripubertal period. We recently produced filamentous phages displaying FSHR fragments overlapping residues 18-38, which, if injected in animals, induced anti-FSH receptor immunity capable of inhibiting hormone binding. We employed this strategy to transiently inhibit FSH activity in male mice and male goats of the Saanen and the Mongolian Alpas Cashmere breeds at the prepubertal stage. Anti-FSHR peptide immunization from the age of 3 wk delayed the acquisition of fecundity in male mice by up to 1 wk. Once fertile, progeny sizes produced by mating immunized males and untreated females were found to be reduced by up to 60%. In two different breeds of goats, FSHR peptide vaccines were able to maintain circulating testosterone at low prepubertal levels for several months despite no alteration in LH levels, reflecting their ability to delay the onset of puberty. These results support the conclusion that FSH may play a central role in the male at puberty through the control of testosterone production.     

Crystal structure of Pterocarpus angolensis lectin in complex with glucose,sucrose, and turanose

The crystal structure of the Man/Glc-specific seed lectin from Pterocarpus angolensis was determined in complex with methyl-alpha-d-glucose, sucrose, and turanose. The carbohydrate binding site contains a classic Man/Glc type specificity loop. Its metal binding loop on the other hand is of the long type, different from what is observed in other Man/Glc-specific legume lectins. Glucose binding in the primary binding site is reminiscent of the glucose complexes of concanavalin A and lentil lectin. Sucrose is found to be bound in a conformation similar as seen in the binding site of lentil lectin. A direct hydrogen bond between Ser-137(OG) to Fru(O2) in Pterocarpus angolensis lectin replaces a water-mediated interaction in the equivalent complex of lentil lectin. In the turanose complex, the binding site of the first molecule in the asymmetric unit contains the alphaGlc1-3betaFruf form of furanose while the second molecule contains the alphaGlc1-3betaFrup form in its binding site.     

A description of dynamical graphs associated to elementary regulatory circuits

The biological and dynamical importance of feedback circuits in regulatory graphs has often been emphasized. The work presented here aims at completely describing the dynamics of isolated elementary regulatory circuits. Our analytical approach is based on a discrete formal framework, built upon the logical approach of R. Thomas. Given a regulatory circuit, we show that the structure of synchronous and asynchronous dynamical graphs depends only on the length of the circuit (number of genes) and on its sign (which depends on the parity of the number of negative interactions). This work constitutes a first step towards the analytical characterisation of discrete dynamical graphs for more complex regulatory networks in terms of contributions corresponding to their embedded elementary circuits.     

The monosaccharide binding site of lentil lectin: an X-ray and molecular modelling study

The X-ray crystal structure of lentil lectin in complex with -d-glucopyranose has been determined by molecular replacement and refined to anR-value of 0.20 at 3.0 Å resolution. The glucose interacts with the protein in a manner similar to that found in the mannose complexes of concanavalin A, pea lectin and isolectin I fromLathyrus ochrus. The complex is stabilized by a network of hydrogen bonds involving the carbohydrate oxygens O6, O4, O3 and O5. In addition, the -d-glucopyranose residue makes van der Waals contacts with the protein, involving the phenyl ring of Phe123. The overall structure of lentil lectin, at this resolution, does not differ significantly from the highly refined structures of the uncomplexed lectin.Molecular docking studies were performed with mannose and its 2-O and 3-O-m-nitro-benzyl derivatives to explain their high affinity binding. The interactions of the modelled mannose with lentil lectin agree well with those observed experimentally for the protein-carbohydrate complex. The highly flexible Me-2-O-(m-nitro-benzyl)--d-mannopyranoside and Me-3-O-(m-nitro-benzyl)--d-mannopyranoside become conformationally restricted upon binding to lentil lectin. For best orientations of the two substrates in the combining site, the loss of entropy is accompanied by the formation of a strong hydrogen bond between the nitro group and one amino acid, Gly97 and Asn125, respectively, along with the establishment of van der Waals interactions between the benzyl group and the aromatic amino acids Tyr100 and Trp128.RL and FC are joint first authors.     

Early Devonian fungi: a blastocladalean fungus with sexual reproduction

In this paper we describe a fossil fungus–Paleoblastocladia milleri gen. et sp. nov.–from the 400 million-year-old Early Devonian Rhynie chert that shares numerous features with modern zoosporic fungi placed in the order Blastocladiales. The fungus occurs in tufts that arise from stomata or between the cuticle and epidermis of Aglaophyton major axes. Thallus development begins from an irregular bipolar basal cell that produces a system of intramatrical rhizoids and clavate-shaped extramatrical, nonseptate hyphae. These hyphae develop into two types of mature thalli. Sporothalli are characterized by several orders of dichotomous branching and the production of terminal, globose zoosporangia, as well as thick-walled, pitted resting sporangia. On separate dichotomously branched thalli (gametothalli) are terminal chains of two or three gametangia, in which the terminal one is slightly larger. Despite the fact that all of the reproductive organs contain either zoospores or gametes, none show evidence of discharge papillae. The fossil fungus is compared with extant members of the Blastocladiales, and the presence of sexual reproduction is discussed.     

Transient gene expression in electroporated banana (Musa spp., cv. ‘Bluggoe’, ABB group) protoplasts isolated from regenerable embryogenetic cell suspensions

Summary Electroporation conditions were established for transient expression of introduced DNA in banana (Musa spp., cv. Bluggoe) protoplasts isolated from regenerable embryogenic cell suspensions. The following parameters were found to be highly influential: electroporation buffer, polyethylene glycol treatment and its duration before electroporation, use of a heat shock, and chimaeric gene constructs. The maximum frequency of DNA introduction as detected by an in situ assay for transient expression of the uidA gene, amounted to 1.8% of total protoplasts. Since plants have recently been regenerated from banana protoplasts at a high frequency, the present results may contribute to the production of transgenic banana.Abbreviations AMV alfalfa mosaic virus - CaMV cauliflower mosaic virus - 2,4-D 2,4-dichlorophenoxyacetic acid - EGTA ethylene glycol-O-O'-bis(2-aminoethyl)-N,N,N',N'-tetraacetic acid - GUS glucuronidase - HEPES 4-(2-nydroxyethyl)piperazine-1-etnanesulfonic acid - MES 2-morpholinoethanesulfonic acid - MS Murashige-Skoog - NOS nopaline synthase - NFTII neomycin phosphotransferase - PEG polyethylene glycol - TGE transient GUS expression - X-Gluc 5-bromo-4-chloro-3-indolyl -D-glucuronic acid