Atlantic salmon eggs favour sperm in competition that have similar major histocompatibility alleles

Polyandry and post-copulatory sexual selection provide opportunities for the evolution of female differential sperm selection. Here, we examined the influence of variation in major histocompatibility (MH) class I allelic composition upon sperm competition dynamics in Atlantic salmon. We ran in vitro fertilization competitions that mimicked the gametic microenvironment, and replicated a paired-male experimental design that allowed us to compare differences in sperm competition success among males when their sperm compete for eggs from females that were genetically either similar or dissimilar at the MH class I locus. Concurrently, we measured variation in spermatozoal traits that are known to influence relative fertilization success under these conditions. Contrary to the findings demonstrating mechanisms that promote MH complex heterozygosity, our results showed that males won significantly greater relative fertilization success when competing for eggs from genetically similar females at the MH class I. This result also showed covariation with the known influences of sperm velocity on relative fertilization success. We discuss these unexpected findings in relation to sperm-egg recognition and hybridization avoidance mechanisms based upon immunogenetic variation.     

Abscisic Acid Deficiency Causes Changes in Cuticle Permeability and Pectin Composition That Influence Tomato Resistance to Botrytis cinerea

A mutant of tomato (Solanum lycopersicum) with reduced abscisic acid (ABA) production (sitiens) exhibits increased resistance to the necrotrophic fungus Botrytis cinerea. This resistance is correlated with a rapid and strong hydrogen peroxide-driven cell wall fortification response in epidermis cells that is absent in tomato with normal ABA production. Moreover, basal expression of defense genes is higher in the mutant compared with the wild-type tomato. Given the importance of this fast response in sitiens resistance, we investigated cell wall and cuticle properties of the mutant at the chemical, histological, and ultrastructural levels. We demonstrate that ABA deficiency in the mutant leads to increased cuticle permeability, which is positively correlated with disease resistance. Furthermore, perturbation of ABA levels affects pectin composition. sitiens plants have a relatively higher degree of pectin methylesterification and release different oligosaccharides upon inoculation with B. cinerea. These results show that endogenous plant ABA levels affect the composition of the tomato cuticle and cell wall and demonstrate the importance of cuticle and cell wall chemistry in shaping the outcome of this plant-fungus interaction.Plant defense against pathogens often involves the induction of mechanisms after pathogen recognition, including defense signaling, cell wall strengthening, and localized cell death, but plants also have preformed chemical and structural defense barriers. Fungal pathogens that penetrate the plant tissue directly through the outer surface, rather than via natural plant openings or wounds, must pass through the plant cuticle and epidermal cell wall. Penetration of the host surface happens either by physical means (i.e. by a highly localized pressure in the appressorium) or by chemical means (i.e. by the release of hydrolyzing enzymes). Necrotrophic plant pathogens like Botrytis cinerea typically use the latter strategy. During penetration, they produce cutinases and pectinolytic enzymes such as pectin methylesterases, endopolygalacturonases, and exopolygalacturonases (van Kan, 2006).The cuticle is a hydrophobic barrier that covers the aerial surfaces of the plant. It is mainly composed of cutin, a polyester matrix, and soluble waxes, a complex mixture of hydrophobic material containing very-long-chain fatty acids and their derivatives, embedded into and deposited onto the cutin matrix. It plays an important role in organ development and protection against water loss (Yephremov et al., 1999; Sieber et al., 2000; Kurata et al., 2003; Jung et al., 2006). The cuticle is generally considered as a mere passive physical barrier against pathogen invasion, but it has also been recognized as a potential source of signaling and elicitor molecules (Jenks et al., 1994; Reina-Pinto and Yephremov, 2009). Plant cutin monomers trigger cutinase secretion in pathogenic fungi (Woloshuk and Kolattukudy, 1986), and cutin and wax components initiate appressorium formation and penetration in appressorium-forming pathogens (Kolattukudy et al., 1995; Francis et al., 1996; Gilbert et al., 1996; Fauth et al., 1998; Dickman et al., 2003). In plants, cutin monomers induce pathogenesis-related gene expression and elicit hydrogen peroxide (H₂O₂) synthesis (Fauth et al., 1998; Kim et al., 2008; Park et al., 2008). Transgenic tomato (Solanum lycopersicum) plants expressing the yeast Δ-9 desaturase gene had high levels of cutin monomers that inhibited powdery mildew (Erysiphe polygoni) spore germination, leading to enhanced resistance (Wang et al., 2000). Arabidopsis (Arabidopsis thaliana) plants expressing a fungal cutinase or mutants with a defective cuticle, such as long-chain acyl-CoA synthetase2 and bodyguard, are generally more susceptible to bacteria and equally susceptible to biotrophic fungi but are surprisingly resistant to B. cinerea (Bessire et al., 2007; Chassot et al., 2007; Tang et al., 2007). It has been postulated that a defective or thin cuticle encourages these plants to constitutively express defense-related mechanisms and to secrete antifungal compounds to the plant surface, thereby inhibiting B. cinerea growth (Bessire et al., 2007; Chassot et al., 2007). In addition, cuticle metabolic pathways might directly modulate plant-pathogen interactions by interacting with hormonally regulated defense pathways (Fiebig et al., 2000; Garbay et al., 2007; Mang et al., 2009) or with complex lipid signaling pathways leading to hypersensitive cell death (Raffaele et al., 2008).Once plant pathogens have penetrated the cuticle, they secrete hydrolases that target the plant cell wall (ten Have et al., 1998; Oeser et al., 2002; Vogel et al., 2002; Jakob et al., 2007) that is mainly composed of cellulose, hemicellulose, and pectin (35% of total dry weight). Pectin consists mainly of the polysaccharides homogalacturonan and rhamnogalacturonan I and II. Homogalacturonans are linear chains of α-(1–4)-linked d-GalA residues that can be methylesterified at C-6. Rhamnogalacturonan I and II are more complex, branched polysaccharides. B. cinerea is typically regarded as a pectinolytic pathogen because it possesses an efficient pectinolytic machinery, including a variety of polygalacturonases and pectin methylesterases (PMEs), some of which are important virulence factors (ten Have et al., 1998, 2001; Valette-Collet et al., 2003; Kars et al., 2005). Pectins are a rich source of oligogalacturonides (OGAs), biologically active signaling molecules that can activate plant defense mechanisms (Hahn et al., 1981; Côté and Hahn, 1994; Messiaen and Van Cutsem, 1994; Ridley et al., 2001). The eliciting capacity of the OGAs was shown to depend on their size, which in turn is influenced by the methylesterification pattern of the homogalacturonan fraction (Mathieu et al., 1991; Messiaen and Van Cutsem, 1994). To counteract the activity of fungal pectinases, many plants express polygalacturonase-inhibiting proteins and PME inhibitors, which are localized in the cell wall. The role of these proteins in plant defense against B. cinerea has been extensively demonstrated (Powell et al., 2000; Ferrari et al., 2003; Sicilia et al., 2005; Joubert et al., 2006, 2007; Lionetti et al., 2007). The interaction with the inhibitors not only limits the destructive potential of polygalacturonases but also leads to the accumulation of elicitor-active OGAs (De Lorenzo and Ferrari, 2002). How OGAs are perceived by the plant is still unclear, but in view of the diversity of biological activities and structure requirements, they are thought to be recognized through different proteins, including receptor-like kinases, wall-associated kinases, arabinogalactan proteins, and Pro-rich proteins (Côté and Hahn, 1994; Showalter, 2001; Humphrey et al., 2007).Over the past years, the role of abscisic acid (ABA) in plant-pathogen interactions has gained increased attention. ABA is mostly negatively correlated with resistance against phytopathogens through down-regulation of defense responses orchestrated by salicylic acid, jasmonic acid, and ethylene (Mohr and Cahill, 2001; Audenaert et al., 2002; Mauch-Mani and Mauch, 2005; Asselbergh et al., 2008). In tomato, the ABA-deficient mutant sitiens has an enhanced resistance to B. cinerea (Audenaert et al., 2002) that depends on a timely, localized oxidative burst leading to rapid epidermal cell wall fortification and a faster and higher induction of defense-related gene expression upon infection compared with the wild type (Asselbergh et al., 2007). Moreover, basal defense gene expression is higher in this mutant than in the wild type. As this early response is of vital importance for the resistant reaction of tomato against B. cinerea, we investigated whether alterations in cuticle and/or cell wall, which form the first barrier to the invading pathogen, affect resistance. We demonstrate that the sitiens cuticle is more permeable and that permeability is positively correlated with resistance to B. cinerea. Furthermore, differences in pectin composition and rate of methylesterification occur. Together, these data hint at an unanticipated role for extracellular matrix components in the resistance of tomato against B. cinerea and thus shed new light on the largely unexplored interrelationship between the extracellular matrix and plant-pathogen interactions.     

Obtaining valid laboratory data in clinical trials conducted in resource diverse settings: lessons learned from a microbicide phase III clinical trial

Background

Over the last decade several phase III microbicides trials have been conducted in developing countries. However, laboratories in resource constrained settings do not always have the experience, infrastructure, and the capacity to deliver laboratory data meeting the high standards of clinical trials. This paper describes the design and outcomes of a laboratory quality assurance program which was implemented during a phase III clinical trial evaluating the efficacy of the candidate microbicide Cellulose Sulfate 6% (CS) [1].

Methodology

In order to assess the effectiveness of CS for HIV and STI prevention, a phase III clinical trial was conducted in 5 sites: 3 in Africa and 2 in India. The trial sponsor identified an International Central Reference Laboratory (ICRL), responsible for the design and management of a quality assurance program, which would guarantee the reliability of laboratory data. The ICRL provided advice on the tests, assessed local laboratories, organized trainings, conducted supervision visits, performed re-tests, and prepared control panels. Local laboratories were provided with control panels for HIV rapid tests and Chlamydia trachomatis/Neisseria gonorrhoeae (CT/NG) amplification technique. Aliquots from respective control panels were tested by local laboratories and were compared with results obtained at the ICRL.

Results

Overall, good results were observed. However, discordances between the ICRL and site laboratories were identified for HIV and CT/NG results. One particular site experienced difficulties with HIV rapid testing shortly after study initiation. At all sites, DNA contamination was identified as a cause of invalid CT/NG results. Both problems were timely detected and solved. Through immediate feedback, guidance and repeated training of laboratory staff, additional inaccuracies were prevented.

Conclusions

Quality control guidelines when applied in field laboratories ensured the reliability and validity of final study data. It is essential that sponsors provide adequate resources for implementation of such comprehensive technical assessment and monitoring systems.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00153777","term_id":"NCT00153777"}}NCT00153777 and Current Controlled Trials ISRCTN95638385     

Glutamate levels and transport in cat (Felis catus) area 17 during cortical reorganization following binocular retinal lesions

Glutamate is known to play a crucial role in the topographic reorganization of visual cortex after the induction of binocular central retinal lesions. In this study we investigated the possible involvement of the glial high-affinity Na+/K+-dependent glutamate transporters in cortical plasticity using western blotting and intracortical microdialysis. Basal extracellular glutamate levels and the re-uptake activity for glutamate have been determined by comparing the extracellular glutamate concentration before and during the blockage of glutamate removal from the synaptic cleft with the potent transporter inhibitor l-trans-pyrrolidine-3,4-dicarboxylic acid. In cats with central retinal lesions we observed increased basal extracellular glutamate concentrations together with a decreased re-uptake activity in non-deprived, peripheral area 17, compared with the sensory-deprived, central cortex of the same animal as well as the topographically matching regions of area 17 in normal subjects. Western blotting experiments revealed a parallel decrease in the expression level of the glial glutamate transporter proteins GLT-1 and GLAST in non-deprived cortex compared with sensory-deprived cortex of lesion cats and the corresponding regions of area 17 of normal subjects. This study shows that partial sensory deprivation of the visual cortex affects the removal of glutamate from the synaptic cleft and implicates a role for glial-neuronal interactions in adult brain plasticity.     

The cell cycle: a review of regulation,deregulation and therapeutic targets in cancer

The cell cycle is controlled by numerous mechanisms ensuring correct cell division. This review will focus on these mechanisms, i.e. regulation of cyclin-dependent kinases (CDK) by cyclins, CDK inhibitors and phosphorylating events. The quality checkpoints activated after DNA damage are also discussed. The complexity of the regulation of the cell cycle is also reflected in the different alterations leading to aberrant cell proliferation and development of cancer. Consequently, targeting the cell cycle in general and CDK in particular presents unique opportunities for drug discovery. This review provides an overview of deregulation of the cell cycle in cancer. Different families of known CDK inhibitors acting by ATP competition are also discussed. Currently, at least three compounds with CDK inhibitory activity (flavopiridol, UCN-01, roscovitine) have entered clinical trials.     

Vitamin D(3): synthesis of seco C-9,11,21-trisnor-17-methyl-1 alpha, 25-dihydroxyvitamin D(3) analogues

The synthesis and biological activities of seco C-9,11,21-trisnor-17-methyl-1 alpha,25-dihydroxyvitamin D(3) analogues (D-ring analogues) are described.     

Trends in comparative genetics and their potential impacts on wheat and barley research

We review some general points about comparative mapping, the evolution of gene families and recent advances in the understanding of angiosperm phylogeny. These are considered in relation to studies of large-genome cereals, particularly barley (Hordeum vulgare) and wheat (Triticum aestivum), with reference to methods of gene isolation. The relative merits of direct map-based cloning in barley and wheat, utilization of the smaller genome of rice (Oryza sativa) and gene homology methods that utilize information from model species such as Arabidopsis thaliana are briefly discussed.     

Comparison of two methods for serotyping Ureaplasma urealyticum clinical isolates

A newly developed enzyme linked immunosorbent assay (ELISA) method using monoclonal antibodies (MAbs) to the 14 serotypes of Ureaplasma urealyticum was compared to immunofluorescence assay (IFA) for serotyping U. urealyticum clinical isolates. Of the 102 vaginal isolates of U. urealyticum, five strains were lost and were excluded from analysis. Of the 97 strains analysed, a total of 86 (89%) strains were typeable by ELISA and a total of 89 (92%) strains were typeable by IFA. Eighty-six strains were typeable by both methods, three by IFA only and eight strains were not typeable neither by ELISA nor by IFA. Of the 86 strains typeable by both methods, complete concordance in serotyping results was found. The three strains not typeable by ELISA were typeable as serotype 4 by IFA. These three strains were reanalysed by ELISA after major modifications of the antigen preparation and were typeable as serotype 4. In conclusion, the ELISA was found suitable for serotyping clinical isolates. However, since the ELISA had a somewhat lower performance than IFA, strains not typeable by ELISA, should be retested by another technique such as IFA.