Imagerie et bilan d'une infertilité masculine

A male cause is responsible in near 50% of infertilities. The radiologist takes place in a multidisciplinary management, after clinical and biological screening, which distinguishes:

- excretory infertilities, of which some causes are curable. Transrectal sonography (TRUS) and scrotal sonography are the first tests. In case of epididymal obstacle, scrotal abnormalities may correspond to constitutional or acquired causes; TRUS is normal. TRUS usually identifies congenital bilateral absence of vas deferens; without renal agenesia, a genital form of cystic fibrosis must be evocated. In case of distal obstacles, TRUS may be completed with MRI, especially in case of voluminous cystic tumors. Vasography, which directly shows was deferens patency, is required to accurately diagnose obstruction when ultrasound is not conclusive; vasography must be integrated in a surgical strategy.

- secretory azoospermies, from gonadic or hypothalamo-hypophyseal causes. Scrotal sonography may complete clinical examination. When hypothalamo-hypophyseal axis must be explored, MRI is the reference test.

- oligo-astheno-teratospermies, where infertilities are often mixed, with various male factors.

Three groups must be explored: hyperprolactinemies (MRI); chronic genital infection (ultrasound); varicoceles; Doppler color ultrasound may help to the detection; spermatic phlebography produce a pretherapeutic cartography, and may be the first step of a percutaneous sclerotherapy.     

Characterization of the <Emphasis Type="Italic">Trichomonas vaginalis</Emphasis> surface-associated AP65 and binding domain interacting with trichomonads and host cells

Background  

AP65 is a prominent adhesin of Trichomonas vaginalis that mediates binding of parasites to host vaginal epithelial cells (VECs). AP65 with no secretion signal sequence, membrane targeting peptide, and anchoring motif was recently found to be secreted.     

Impacts of inbreeding on bumblebee colony fitness under field conditions

Background  

Inbreeding and the loss of genetic diversity are known to be significant threats to small, isolated populations. Hymenoptera represent a special case regarding the impact of inbreeding. Haplodiploidy may permit purging of deleterious recessive alleles in haploid males, meaning inbreeding depression is reduced relative to diploid species. In contrast, the impact of inbreeding may be exacerbated in Hymenopteran species that have a single-locus complementary sex determination system, due to the production of sterile or inviable diploid males. We investigated the costs of brother-sister mating in the bumblebee Bombus terrestris. We compared inbred colonies that produced diploid males and inbred colonies that did not produce diploid males with outbred colonies. Mating, hibernation and colony founding took place in the laboratory. Once colonies had produced 15 offspring they were placed in the field and left to forage under natural conditions.     

Molecular mechanism of ligand recognition by membrane transport protein,Mhp1

The hydantoin transporter Mhp1 is a sodium‐coupled secondary active transport protein of the nucleobase‐cation‐symport family and a member of the widespread 5‐helix inverted repeat superfamily of transporters. The structure of Mhp1 was previously solved in three different conformations providing insight into the molecular basis of the alternating access mechanism. Here, we elucidate detailed events of substrate binding, through a combination of crystallography, molecular dynamics, site‐directed mutagenesis, biochemical/biophysical assays, and the design and synthesis of novel ligands. We show precisely where 5‐substituted hydantoin substrates bind in an extended configuration at the interface of the bundle and hash domains. They are recognised through hydrogen bonds to the hydantoin moiety and the complementarity of the 5‐substituent for a hydrophobic pocket in the protein. Furthermore, we describe a novel structure of an intermediate state of the protein with the external thin gate locked open by an inhibitor, 5‐(2‐naphthylmethyl)‐L‐hydantoin, which becomes a substrate when leucine 363 is changed to an alanine. We deduce the molecular events that underlie acquisition and transport of a ligand by Mhp1.     

Expression of N-linked sialyl Le(x) determinants and O-glycans in the carbohydrate moiety of human amniotic fluid transferrin during pregnancy

Transferrin, a glycoprotein involved in iron transport in body fluids, was isolated from amniotic fluid of a hydramniospatient by sequential anion-exchange chromatography and gel filtration. The N-glycans of human amniotic fluid transferrin (hAFT) were enzymatically liberated by PNGase-F digestion, isolated by gel filtration and fractionated by (high-pH) anion-exchange chromatography. After alkaline borohydride treatment of native hAFT, the released O-glycans were isolated by gel filtration and fractionated by anion-exchange chroma-tography. Structure elucidation of 14 N- and 2 O-glycans was performed by 500 or 600 MHz1H-NMR spectroscopy. Besides conventional N-glycans established earlier for human serum transferrin (hST), new (alpha1-3)-fucosylated N- glycans were found, representing sialyl Le(x) elements. Furthermore, as compared to hST, a higher degree of (alpha1-6)-fucosylation and an increase in branching from di- to triantennary compounds has been detected. The presence of O-glycans is demonstrated for the first time in transferrin.      

Heterologous expression of bacteriocin E-760 in Chlamydomonas reinhardtii and functional analysis

The use of antimicrobial peptides (AMPs) synthesized by bacteria (bacteriocins) is an alternative for combating multidrug resistant bacterial strains and their production by recombinant route is a viable option for their mass production. The bacteriocin E-760 isolated from the genus Enterococcus sp. has been shown to possess inhibitory activity against Gram-negative and Gram-positive bacteria. In this study, the expression of a chimeric protein coding for E-760 in the nucleus of C. reinhardtii was evaluated, as well as, its antibacterial activity. The synthetic gene E-760S was inserted into the genome of C. reinhardtii using Agrobacterium tumefaciens. A transgenic line was identified in TAP medium with hygromycin and also by PCR. The increment in the culture medium temperature of the transgenic strain at 35 °C for 10 minutes, increased the production level of the recombinant protein from 0.14 (Noninduced culture, NIC) to 0.36% (Induced culture, IC) of total soluble proteins (TSP); this was quantified by an ELISA assay. Recombinant E-760 possesses activity against Staphylococcus aureus in 0.34 U log, Streptococcus agalactiae in 0.48 U log, Enterococcus faecium in 0.36 U log, Pseudomonas aeruginosa in 2 U log and for Klebsiella pneumoniae, the activity was 0.07 U log. These results demonstrate that the nucleus transformation of C. reinhardtii can function as a stable expression platform for the production of the synthetic gene E-760 and it can potentially be used as an antibacterial agent.     

Early origin of foraminifera suggested by SSU rRNA gene sequences

Foraminifera are one of the largest groups of unicellular eukaryotes with probably the best known fossil record. However, the origin of foraminifera and their phylogenetic relationships with other eukaryotes are not well established. In particular, two recent reports, based on ribosomal RNA gene sequences, have reached strikingly different conclusions about foraminifera's evolutionary position within eukaryotes. Here, we present the complete small subunit (SSU) rRNA gene sequences of three species of foraminifera. Phylogenetic analysis of these sequences indicates that they branch very deeply in the eukaryotic evolutionary tree: later than those of the amitochondrial Archezoa, but earlier than those of the Euglenozoa and other mitochondria-bearing phyla. Foraminifera are clearly among the earliest eukaryotes with mitochondria, but because of the peculiar nature of their SSU genes we cannot be certain that they diverged first, as our data suggest.      

Implications of scale for patterns and processes in stream ecology

Abstract Although the scale-dependence of ecological patterns and processes is recognized by freshwater ecologists, current knowledge of scale effects is rudimentary and non-quantitative. We review issues of spatial and temporal scale in this paper to highlight conceptual problems relating to scale and some potential solutions. We present examples of how the spatial scale of a study influences observed patterns and their interpretation, and discuss how the size of an experimental arena influences the degree to which the dynamics of studied populations are influenced by exchange processes (immigration and emigration). The results of small-scale field experiments in streams will often be strongly influenced by the per capita exchange rates of organisms and differences in exchange rates may explain differences in the perceived effects of stream manipulations across scales. Spatial extent also influences the amount of spatial heterogeneity within a study site or arena, with important consequences for the outcome of predator-prey interactions. We suggest that changes in the availability of prey refuges may help explain why predator manipulations in streams appear to weaken as arena size increases. We also recommend that new techniques for decomposing and quantifying spatial heterogeneity be applied to characterize scale-dependent variation in freshwater systems. Lastly, we discuss the pitfalls of mismatching the temporal scale of experiments and models. Models incorporating spatial heterogeneity and the behaviour of organisms are needed to predict the short-term outcome of perturbations in streams, whereas models predicting long-term dynamics will need to integrate the impacts of episodic disturbance and all life history stages of organisms. In general, we recommend that freshwater ecologists undertake more multi-scale sampling and experimentation to examine patterns and processes at multiple scales, and make greater attempts to match the scales of their observations and experiments to the characteristic scales of the phenomena that they investigate.     

Feeding electrogram studies on the African cattle brown ear tick Rhipicephalus appendiculatus: evidence for an antifeeding effect of tick resistant serum

Abstract. Feeding behaviour of partially engorged Rhipicephalus appendiculatus (Neumann) (Acari: Ixodidae) on rabbit serum held in capillary tubes and placed over the tick mouthparts was studied using the feeding electrogram technique with simultaneous macro video photography. Correlation of electrical events with fluid movement in the vicinity of the tick's mouthparts and the capillary meniscus, permitted the characterization of an orderly sequence of signals, termed the 'Feeding Complex', associated with highest weight gains. This complex consisted of a 3–8 Hz fast-sucking waveform typically lasting 4–5 min, a sharp drop in potential at salivation, and rest lasting 1 or 2 min where no waveform or fluid movements occur. Very high impedence recordings from within the tick capitulum indicate that the fast-sucking waveform coincides with bursts of potentials corresponding to contraction of the pharyngeal dilator muscles, whereas during rest a tonic series of spikes signifies that the floor of the salivarium is actively lowered. Feeding electrograms of ticks fed on serum from tick-resistant rabbits showed significantly fewer feeding complexes. The weight gains achieved by these ticks were reduced correspondingly. This suggests that some of the humoral effectors of immunity have an antifeedant effect on this unusual parasite of rabbits.