WOLBACHIA INFECTION IN DROSOPHILA SIMULANS: DOES THE FEMALE HOST BEAR A PHYSIOLOGICAL COST?

Fitness traits of three Drosophila simulans strains infected by endocellular bacteria belonging to the genus Wolbachia have been compared with those of replicate stocks previously cured from the infection by an antibiotic treatment. The traits measured were development time, egg-to-adult viability, egg hatch, productivity, fecundity, and the number of functional ovarioles. Individuals of the first strain were bi-infected by two Wolbachia variants, wHa and wNo. The second strain was infected by wHa, the third one by wNo. The Wolbachia studied here cause cytoplasmic incompatibility (CI), a high embryonic mortality (70% to > 90%) when an infected male is crossed with an uninfected female. Three generations after antibiotic treatment, we observed in all strains a significant drop in productivity in the cured stocks. This drop was not due to antibiotic toxicity and was associated with the loss of the Wolbachia. However the effect had disappeared in two of the three strains five generations after treatment, and could not be found in the third strain in a third measurement carried out 14 generations after treatment. The temporary nature of the productivity difference indicates that Wolbachia do not enhance productivity in infected strains. On the other hand, in all traits measured, our results show the absence of any negative effects of the Wolbachia on their host. This could be explained when considering Wolbachia evolution, as maternally transmitted parasites bear a strong selective pressure not to harm their female host. However, CI would allow the bacteria to be maintained even when harming the female. The apparent absence of deleterious effects caused by these Wolbachia might result from a trade-off, where a relatively low bacteria density would advantage the Wolbachia by suppressing any deleterious effects on the female host, at the cost of a weaker maternal transmission rate of the infection.     

Wheat germ agglutinin (WGA) reduces ADH-induced water flow and induces cell surface changes in epithelial cells of frog urinary bladder

The functional and structural changes induced by apical wheat germ agglutinin (WGA) 100 micrograms/ml exposure on frog urinary bladder have been investigated and the possible correlations between these effects discussed. Bladders, apically exposed to WGA for 30 min to 3 hr exhibit a marked reduction of their response to antidiuretic hormone (ADH) challenge and of their hydrosmotic reactivity. Structural changes triggered by WGA treatment are: 1. apical invaginations of the plasma membrane, interpreted as endocytotic in nature, taking into account the results of carbohydrate cytochemical detection and horseradish peroxidase (HRP) exposure: 2. cytoskeleton disorganization and microvilli collapse. These phenomena do not interfere with cortical granule traffic and are independent of ADH challenge: they occur in ADH-stimulated bladders as well as in bladders at rest. These findings could be interpreted as follows: binding of the divalent lectin WGA to its coat specific receptors would induce changes in the apical membrane structure which in turn could provoke disorganization and disruption of apical cytoskeletal elements associated with plasma membrane. Reduction of bladder response to ADH challenge could result from a reduced recycling of aggrephores, as they are associated with cytoskeletal elements in the subapical cytoplasm. Collapse of microvilli and endocytotic events also could result from apical cytoskeleton disruption, as microvilli are sustained by bundles of actin filaments interconnected with apical cytoskeletal filaments and as plasma membrane is associated with apical cytoskeleton. However, these two last events evidently occur in ADH-challenged or non-challenged bladders.     

Plant natural fragments,an innovative approach for drug discovery

Plant natural products (PNP) (e.g., secondary vegetal metabolites and their derivatives) have been a productive source of active ingredients for the pharmaceutical industry. The High Throughput Screening of Plant Natural Products (PNP-HTS) with extracts or isolated compounds has shown to be time consuming, expensive, and not as successful as expected. Recently building upon the innovative fragment-based drug discovery (FBDD) a disruptive approach was developed based on PNP. The fragment approach involves elaboration and/or isolation of weakly binding small molecules with molecular weights between 150 and 250 Da. This method is fundamentally different from HTS in almost every aspect (i.e., size of the compound library, screening methods, and optimization steps from hit to lead). Due to their nature, vegetal natural fragments have unique three-dimensional (3D) properties, high Fsp³, low aromaticity, and large chemo-diversities which represent potential opportunities for developing novel drugs. Preliminary results using vegetal natural fragments appear to be a promising and emerging field which offers valuable prospects for developing new drugs.

     

How to measure,report and verify soil carbon change to realize the potential of soil carbon sequestration for atmospheric greenhouse gas removal

There is growing international interest in better managing soils to increase soil organic carbon (SOC) content to contribute to climate change mitigation, to enhance resilience to climate change and to underpin food security, through initiatives such as international ‘4p1000’ initiative and the FAO's Global assessment of SOC sequestration potential (GSOCseq) programme. Since SOC content of soils cannot be easily measured, a key barrier to implementing programmes to increase SOC at large scale, is the need for credible and reliable measurement/monitoring, reporting and verification (MRV) platforms, both for national reporting and for emissions trading. Without such platforms, investments could be considered risky. In this paper, we review methods and challenges of measuring SOC change directly in soils, before examining some recent novel developments that show promise for quantifying SOC. We describe how repeat soil surveys are used to estimate changes in SOC over time, and how long‐term experiments and space‐for‐time substitution sites can serve as sources of knowledge and can be used to test models, and as potential benchmark sites in global frameworks to estimate SOC change. We briefly consider models that can be used to simulate and project change in SOC and examine the MRV platforms for SOC change already in use in various countries/regions. In the final section, we bring together the various components described in this review, to describe a new vision for a global framework for MRV of SOC change, to support national and international initiatives seeking to effect change in the way we manage our soils.     

Assessing land use and land cover change in coastal urban wetlands of international importance in Ghana using Intensity Analysis

Wetlands Ecology and Management - In the era of global environmental change, land transformation is acknowledged as a critical subject that needs to be addressed. Even though some studies have been...     

Field monitoring of onion maggot (Delia antiqua) fly through improved trapping

Onion maggot (Delia antiqua) is an economically important pest of Allium crops in temperate regions throughout the world. Management of this pest is necessary to achieve economic returns and depends on insecticide regimes and cultural management. Current cultural management especially altering planting date, field location and crop rotation depend on monitoring. We evaluated the effect of shape, size, colour and chemical attractants on trap catch of field populations of adult D. antiqua flies in upstate New York. White, large diameter, spherical traps in conjunction with Delia Lure attractant performed the best in attracting and catching D. antiqua adults. These results suggest an improved means of attracting and capturing D. antiqua populations which could be useful in monitoring efforts and development of attract and kill strategies for pest control.