The search for the gene mutations underlying enterotoxigenic Escherichia coli F4ab/ac susceptibility in pigs: a review

Diarrhoea due to enterotoxigenic Escherichia coli with fimbriae F4 (ETEC-F4) is an important problem in neonatal and just weaned piglets and hence for the pig farming industry. There is substantial evidence for a genetic basis for susceptibility to ETEC-F4 since not all piglets suffer from diarrhoea after an ETEC-F4 infection. It is assumed that the wild boar was originally ETEC-F4 resistant and that susceptibility towards ETEC arose after domestication. There are different phenotypes in the pig determined by which of the three existing F4 variants (F4ab, F4ac or F4ad) they are susceptible or resistant for. This suggests that several F4 receptors exist, expressed individually or in combination with each other on the brush border of the piglet’s small intestine. As such, the mucin-type glycoproteins (IMTGP) are described as F4ab/ac receptors, while the intestinal neutral glycospingolipid (IGLad) is proposed as an F4ad receptor. GP74 is a putative F4ab receptor. However, the specific genes that encode for the susceptibility are not yet known. In the past decades, linkage analyses revealed that the loci encoding for the receptor(s) for the two most frequent variants F4ab and F4ac were mapped to the 13^th chromosome of the pig (Sus scrofa 13, SSC13). After fine mapping, the region of interest was mapped between two microsatellite markers, Sw207 and S0075, and interesting candidate genes surfaced. Numerous SNP analyses and a few expression studies on the three MUC-genes (MUC4, MUC13 and MUC20) and the transferrin receptor gene (TFRC) as well as on some other positional candidate genes have been performed in order to find the causative mutation for the ETEC-F4ab/ac receptor(s). However, until today, the exact mutation causing susceptibility to ETEC-F4 remains unknown.     

Prevalence and risk factors for Campylobacter spp. in chicken broiler flocks in Reunion Island (Indian Ocean)

Our objectives were to determine Campylobacter prevalence in broiler chicken flocks in Reunion Island and to define specific practices associated with the presence of Campylobacter spp. Infection in Reunionese broiler flocks. Fifty broiler flocks were studied in Reunion Island from May 2007 to February 2009. A questionnaire was submitted to the farmers and samples of fresh droppings were collected to assess the flock's Campylobacter status. Fifty four percent of the flocks were infected by Campylobacter spp.: 30% (95% CI: 28.71-31.29) were infected with Campylobacter coli and 17% (95% CI: 15.95-18.05) with Campylobacter jejuni; only 7% (95% CI: 6.28-7.72) were infected by both species at the same time. Several poultry houses in the farm (OR=11.2; [1.05-92]) and cleaning without any detergent (OR=13.1; [2.1-78.3]) increased the risk of Campylobacter infection. A distance higher than 500 m between broiler farms (OR=0.27; [0.1-0.8]) and use of disinfectant during the rearing period decreased this risk of infection (OR=0.15; [0.1-0.75]).     

Seasonal Changes in Water Quality in Commercial Channel Catfish Ponds in Mississippi

Selected water quality variables were measured at monthly intervals for 1 yr in 10 commercial channel catfish ponds in northwest Mississippi. Temporal changes in most variables appeared to be related to seasonal periodicity of phytoplankton abundance. Phytoplankton standing crops and total organic matter were highest in summer months when primary production was favored by warm water temperatures, high solar irradiance, and large inputs of nutrients resulting from high summer fish feed allowances. As day length, water temperature, and feed inputs decreased in autumn and winter, phytoplankton abundance and organic matter concentrations decreased. Seasonal changes in total nitrogen and total phosphorus concentrations were similar to phytoplankton abundance because much of the total nitrogen and phosphorus was contained within phytoplankton cells. Contrasting to the seasonal trend for total nitrogen, concentrations of dissolved inorganic nitrogen were lowest in the summer and highest in the cooler months. Rapid assimilation by phytoplankton served to maintain relatively low concentrations of dissolved inorganic nitrogen during the summer despite highest nitrogen loading rates during that period. Low water temperatures and generally less favorable conditions for phytoplankton growth decreased rates of nitrogen assimilation in the winter and ammonia, nitrite, and nitrate accumulated. Soluble reactive phosphorus concentrations were low throughout the year because physico-chemical processes, such as precipitation and adsorption to bottom muds acted to continually remove inorganic phosphorus from the water column.     

Criteria for selecting productive and stable pea cultivars

The beginning and duration of the seed set in the growth cycle determine the level and stability of the yield of a pea (Pisum sativum L.) genotype. The objective of the present study was to identify criteria for selecting genotypes, both in terms of timing of seed set and productivity. Genotypes were initially compared in field experiments for two different levels of inter-plant competition, but using the same photo-thermal conditions. These experiments showed that the initiation and, particularly, the duration of seed set were affected by plant growth rates, indicating that selection on these variables must be done by comparing genotypes under regular cropping conditions. When measuring seed production of the whole plant, we found that mean dry seed weight per podded node all over the plant and the number of podded nodes on any fertile stem were similar to those on the main stem. These results confirmed that branches and main stems have a similar reproductive pattern, and thus that any podded stem of the canopy is representative of every stem of the plant. Lastly, we showed that, when associated, the number of podded nodes, the mean dry seed weight per podded node on the main stem (or on any reproductive stem of the canopy), and the number of basal branches per plant are suitable criteria for selecting for productivity among genotypes with a similar duration of seed set. This revised version was published online in August 2006 with corrections to the Cover Date.     

Farmers’ management of peanut (Arachis hypogaea L.) diversity,their varietal preference traits and uses in Southern and Central Benin

Journal of Crop Science and Biotechnology - Peanut (Arachis hypogaea L.) is one of the major oilseed legumes contributing to food security in Benin. Unfortunately, several constraints hamper its...     

Can a problem-solving approach strengthen landscape ecology’s contribution to sustainable landscape planning?

The need to avert unacceptable and irreversible environmental change is the most urgent challenge facing society. Landscape ecology has the capacity to help address these challenges by providing spatially-explicit solutions to landscape sustainability problems. However, despite a large body of research, the real impact of landscape ecology on sustainable landscape management and planning is still limited. In this paper, we first outline a typology of landscape sustainability problems which serves to guide landscape ecologists in the problem-solving process. We then outline a formal problem-solving approach, whereby landscape ecologists can better bring about disciplinary integration, a consideration of multiple landscape functions over long time scales, and a focus on decision making. This framework explicitly considers multiple ecological objectives and socio-economic constraints, the spatial allocation of scarce resources to address these objectives, and the timing of the implementation of management actions. It aims to make explicit the problem-solving objectives, management options and the system understanding required to make sustainable landscape planning decisions. We propose that by adopting a more problem-solving approach, landscape ecologists can make a significant contribution towards realising sustainable future landscapes.     

Vulnerability of low temperature induced needle retention in balsam fir (Abies balsamea L.) to vapor pressure deficits

Low temperature (LT) exposure has been shown to delay postharvest needle abscission and senescence (NAS) in balsam fir and changes in vapor pressure deficit (VPD) are expected to alter these processes. Two and half year-old seedlings were exposed to a LT of 5°C for 15 days while the control (CT) group was maintained at 22°C. Seedlings were then exposed to four different VPD (0.22, 0.87, 1.3 and 1.86?kPa) and observed for relative water content (RWC), xylem pressure potential (XPP), membrane injury index (MII), stem capacitance (SC) and NAS. An interactive effect of LT and VPD was observed in RWC, XPP, MII and NAS. Low VPD (0.22 and 0.87?kPa) resulted in less negative XPP, lower electrolyte leakage, higher SC and ultimately higher NAS than those at high VPD. Maximum NAS was recorded at 0.22?kPa. At 1.86?kPa, LT had 5× lower RWC (13%), 3× more negative XPP (?1.1?MPa), 1.8× higher membrane damage and 35% lower NAS (47 days) than CT. The SC declined with an increase in VPD with no effect of LT. The XPP and RWC of LT seedlings showed a positive relationship with NAS with R² values of 0.54 and 0.59, respectively. LT offered no benefits to NAS at high VPD environments.     

Use of a commercial protease and yeasts to obtain CGRP-like molecules from saithe protein

Different bioactive molecules, such as CGRP-like peptides, can be found in fish protein hydrolysates. Calcitonin gene-related peptide (CGRP) is a neuropeptide known to act as a potent arterial and venous vasodilator in humans. This study focuses on the industrial obtaining of CGRP-like molecules from saithe (Pollachius virens) byproduct, derived from the filleting process. Protein from P. virens was primarily hydrolyzed with Alcalase and later treated with Saccharomyces cerevisiae live cells. Treatment with Saccharomyces doubled the quantity of bioactive molecules obtained. The CGRP-like molecules were partially purified by chromatography, and the immunoreactive material was further analyzed for its CGRP-like bioactivity, using a specific radioreceptor assay. The concentration of CGRP-like molecules increased over 100-fold after purification. The bioactive molecules were able to induce cyclic AMP stimulation in rat liver membranes. Finally, partial sequencing of the bioactive peptide was performed, showing some homology with alpha-actin and myosin of several fish species.     

Framework for intake simulation of functional ingredients

OBJECTIVE: To create a general framework for the simulation of intakes from mandatory or voluntary fortification, which will make outcomes of simulation studies more comparable and give insight on uncertainties. DESIGN: A general framework was developed based on methods used in already published case studies of mandatory fortification. The framework was extended to be suitable for the simulation of voluntary fortification. Case studies of folic acid fortification were used to illustrate the general framework. RESULTS: The developed framework consists of six steps. First, the definition of the fortification strategy (step 1), followed by the identification of potential carrier products (step 2), and the definition of fortification levels or ranges (step 3). Thereafter, virtual food/supplement composition data are created (step 4) and food/supplement consumption data are required (step 5). Finally, the intake of the functional ingredient from functional foods, other foods and dietary supplements is calculated during the simulation resulting in total habitual intake distributions (step 6). CONCLUSIONS: Simulation of both mandatory and voluntary folic acid fortification in The Netherlands showed that the general framework is applicable. Also with incomplete data or data from different sources, the (habitual) intake distributions can be estimated using assumptions, statistical procedures or probabilistic modelling approaches. It is important that the simulation procedure is described well, so that an insight on uncertainties and knowledge gaps to be filled is given.