Campylobacter jejuni induces an anti-inflammatory response in human intestinal epithelial cells through activation of phosphatidylinositol 3-kinase/Akt pathway

Campylobacter jejuni (C. jejuni) is the most common cause of human acute bacterial gastroenteritis. Poultry is a major reservoir of C. jejuni and considered an important source of human infections, thus, it is important to understand the host response to C. jejuni from chicken origin. In this study, we demonstrated firstly that a chicken isolate SC11 colonized chicks faster than clinical isolate NCTC11168. Using the SC11, we further studied the host responds to C. jejuni in terms of inflammatory response and involvement of cellular signaling pathways. Infection of C. jejuni SC11 was able to activate phosphatidylinositol 3-kinase (PI3K)/Akt pathway and induce pro-inflammatory interleukin-8 (IL-8) as well as anti-inflammatory cytokine IL-10 in human intestinal epithelial cell line Colo 205. The signalling pathways PI3K/Akt and mitogen-activated protein (MAP) kinases ERK and p38 were involved in C. jejuni-induced IL-8 and IL-10 expression. Inhibition of PI3K resulted in augmentation of C. jejuni-induced IL-8 production, concomitant with down-regulation of IL-10 mRNA, indicating an anti-inflammatory response was activated and associated with the activation of P13K/Akt. Similar effect was observed for cytolethal distending toxin (CDT) deficient mutants. Moreover, we demonstrated that heat-killed bacteria were able to induce IL-8 and IL-10 expression to a lower level than live bacteria. We therefore conclude that C. jejuni activate a PI3K/Akt-dependent anti-inflammatory pathway in human intestinal epithelial cells which may benefit the intracellular survival of C. jejuni during infection.     

Comparative analysis of local and improved practices used by farmer seed production schools in Vietnam

Farmer seed production schools in combination with participatory field experimentation might be effective instruments to enhance the skills of farmers to produce high-quality seed in the informal seed system in Vietnam. Four hundred twenty nine, unreplicated on-farm experiments were carried out in four different provinces and analyzed by the farmer seed production schools. These experiments consisted of two adjacent seed production plots: one with common local practice and one with improved practice. Differences between the two plots in yield and profit were assessed. Averaged across provinces, yields of the “improved practice plots” were 0.43 Mg ha⁻¹ higher in the wet season and 0.78 Mg ha⁻¹ higher in the dry season than the “local practice plots”. In the Nam Dinh and Nghe An provinces more hills per m², more input of potassium and muck, and fewer seedlings per hill at transplanting contributed to the higher yields in the “improved practice plots”. In the provinces Binh Dinh and Dong Thap, using a drum seeder for sowing, reduced seed rate, less input of nitrogen fertilizer and more potassium contributed to the yield advantage of the “improved practice plots”. The profit of the improved practice plots was 212 US$ ha⁻¹ higher than the profit in the local practice plots. Rice growers can benefit from lower seed rates, better yields and higher prices when grains are sold as seeds. These findings may direct the seed policies and extension approaches in Vietnam.     

Misspecification in stock assessments: Common uncertainties and asymmetric risks

Common uncertainties in stock assessment relate to parameters or assumptions that strongly determine both the estimates of quantities of management interest (e.g. stock depletion) and related reference points (e.g. biomass at maximum sustainable yield). The risks associated with these uncertainties are often presented to managers in the form of decision tables. However, a formal evaluation of the risks from misspecifying an assessment model over time‐horizons spanning multiple assessment cycles requires closed‐loop simulation. There were two aims of this study: (a) develop an approach to identify and evaluate asymmetries in risk to yields and spawning biomass due to biases in key parameters and data sources in a stock assessment model, (b) quantify the relative importance of correctly specifying the various assessment attributes. A computationally efficient stock reduction analysis was evaluated using closed‐loop simulation to identify risks associated with a stock assessment with persistent positive and negative biases in the key parameters and inaccurate assumptions regarding data sources. Six types of assessment misspecification were examined, namely the assumed natural mortality rate, the assumed recruitment compensation ratio, the assumed age of maturity, a hyper‐stable or hyper‐deplete index of abundance, over‐ or under‐reporting of historical catch, and misspecification of the assumed shape of the selectivity curve. This study reveals large asymmetries in risk associated with common uncertainties in stock assessment processes. We highlight the value of reproducible and computationally efficient stock assessment models that can be investigated by closed‐loop simulation before being used for fisheries management.     

Concurrent rice‐shrimp‐crab farming systems in the Mekong Delta: Are conditions (sub) optimal for crop production and survival?

The Mekong Delta is the most important rice‐ and shrimp‐producing region for food and economic security in Vietnam. Rice‐shrimp farming is practised where salinity fluctuates substantially between wet and dry seasons. Research points to several potential risk factors for rotational systems, but how these link directly to both rice and shrimp production remains poorly quantified for systems that stock and harvest animals year‐round. We examined water and soil quality of 18 rice‐shrimp‐crab ponds, in which shrimp and crab are grown in both wet and dry seasons, in the Cà Mau Province of Vietnam. Multiple lines of evidence indicated that environmental conditions experienced by both rice and shrimp were suboptimal and contributed to low yields and survival. Year‐round cropping of shrimp and crab was associated with sustained suboptimal salinity, intensified by drought, for the wet‐season cultivation of rice. Although rice seedlings were sown in all 18 ponds, only three had a harvestable crop. Low shrimp production and survival was associated with sustained suboptimal water temperatures (too high), salinity (too high in the dry season and too low in the wet season) and dissolved oxygen concentrations (too low). Food availability and quality may also have affected shrimp production. Improving productivity of rice‐shrimp‐crab ponds in the study region may require (1) separation of rice and shrimp crops and improving efficiency of soil washing practices such that salinity conditions are more suitable for each when grown, and (2) management intervention to increase oxygenation of water, and the availability and quality of food for shrimp.     

Impact of Cuscuta australis infection on the photosynthesis of the invasive host,Mikania micrantha,under drought condition

Cuscuta species (dodders) are widespread stem holoparasites that depend on host plants for their entire mineral and water and most carbohydrate requirements. Dodders negatively affect host photosynthesis but precise information on their impact on hosts in the presence of environmental stress factors (i.e. drought) is little known. In a pot experiment, the leaf traits, gas exchange and chlorophyll a fluorescence of the invasive climber, Mikania micrantha, parasitized by Cuscuta australis, were investigated in order to study variations of host photosynthesis in response to parasitism and drought. The results showed that the concomitant presence of C. australis infection and drought significantly impacted the leaf traits (i.e. increased leaf dry mass content), gas exchange (i.e. decreased stomatal conductance and transpiration rates and increased water‐use efficiency) and quantum yield of chlorophyll a fluorescence of M. micrantha. The presence of a single stress factor (C. australis infection or drought), however, only significantly affected the leaf traits and gas exchange of M. micrantha. These results suggested that the combined additive effects of C. australis parasitism and drought significantly suppressed the photosynthesis of M. micrantha in relation to both stomatal and non‐stomatal limitation of host photosynthesis. This study provides insights into Cuscuta–host interactions under drought conditions in the tropics.     

Stabilization of toxic metals in three contaminated soils by residual impact of lime integrated with biochar and clays

Journal of Soils and Sediments - Mine and smelter soil contaminations with Pb, Cu, Cd, and Zn have become serious problems in China, because of anthropogenic activities. Little is known about the...     

Acute changes in the concentrations of prostaglandin F2α (PGF) and cortisol in uterine and ovarian venous blood during PGF-induced luteolysis in cows

Prostaglandin F2α (PGF) is considered to be the main luteolysin in cattle. We have previously demonstrated that cortisol (Cr) suppresses PGF production in non-pregnant bovine endometrium. This study was carried out to test whether exogenous PGF increases ovarian and/or uterine PGF production and to determine the temporal relationship between PGF and Cr in ovarian and uterine circulations during PGF-induced luteolysis in cows. Catheters were inserted into the ovarian vein (OV), uterine vein (UV) and jugular vein (JV) of 10 cows on Day 9 of the oestrous cycle (Ovulation = Day 0) for frequent blood collection. On Day 10, the cows were divided randomly into two groups and treated with a luteolytic dose of a PGF analogue (cloprostenol) or saline solution. Blood samples were collected at -0.25, 0, 0.25, 0.5, 1 and 2 h and then at 2-h intervals until 12 h after treatment (0 h). The basal concentrations of PGF and Cr in OV and UV plasma were not significantly different. Injection of a PGF analogue induced more than twofold increases in the levels of PGF between 0.25 and 1 h in UV plasma, but not in OV plasma. PGF increased (p < 0.05) the concentrations of Cr in OV, UV and JV plasma between 0.5 and 1 h. The Cr levels in OV, UV and JV plasma were similar. The PGF levels in UV plasma decreased after Cr reached its highest levels. The overall results suggest that the uterus rather than the ovary increases PGF production in response to PGF injection. Based on the temporal changes of PGF and Cr in the ovarian and uterine circulations, Cr may act to reduce uterine PGF production in non-pregnant cows in vivo.     

Campylobacter jejuni strains of human and chicken origin are invasive in chickens after oral challenge

The aim of the study was to evaluate the colonizing ability and the invasive capacity of selected Campylobacter jejuni strains of importance for the epidemiology of C jejuni in Danish broiler chickens. Four C. jejuni strains were selected for experimental colonization studies in day-old and 14-day-old chickens hatched from specific pathogen free (SPF) eggs. Of the four C. jejuni strains tested, three were Penner heat-stable serotype 2, flaA type 1/1, the most common type found among broilers and human cases in Denmark. The fourth strain was Penner heat-stable serotype 19, which has been shown to be associated with the Guillain Barré Syndrome (GBS) in humans. The minimum dose for establishing colonization in the day-old chickens was approximately 2 cfu, whereas two- to threefold higher doses were required for establishing colonization in the 14-day-old chickens. Two of the C. jejuni strains were shown to be invasive in orally challenged chickens as well as in three different human epithelial cell lines.