Mapping quantitative trait loci affecting fatness and breast muscle weight in meat-type chicken lines divergently selected on abdominal fatness

Quantitative trait loci (QTL) for abdominal fatness and breast muscle weight were investigated in a three-generation design performed by inter-crossing two experimental meat-type chicken lines that were divergently selected on abdominal fatness. A total of 585 F₂ male offspring from 5 F₁ sires and 38 F₁ dams were recorded at 8 weeks of age for live body, abdominal fat and breast muscle weights. One hundred-twenty nine microsatellite markers, evenly located throughout the genome and heterozygous for most of the F₁ sires, were used for genotyping the F₂ birds. In each sire family, those offspring exhibiting the most extreme values for each trait were genotyped. Multipoint QTL analyses using maximum likelihood methods were performed for abdominal fat and breast muscle weights, which were corrected for the effects of 8-week body weight, dam and hatching group. Isolated markers were assessed by analyses of variance. Two significant QTL were identified on chromosomes 1 and 5 with effects of about one within-family residual standard deviation. One breast muscle QTL was identified on GGA1 with an effect of 2.0 within-family residual standard deviation.     

Confirmation and elimination of xylose metabolism bottlenecks in glucose phosphoenolpyruvate-dependent phosphotransferase system-deficient Clostridium acetobutylicum for simultaneous utilization of glucose, xylose, and arabinose

Efficient cofermentation of D-glucose, D-xylose, and L-arabinose, three major sugars present in lignocellulose, is a fundamental requirement for cost-effective utilization of lignocellulosic biomass. The Gram-positive anaerobic bacterium Clostridium acetobutylicum, known for its excellent capability of producing ABE (acetone, butanol, and ethanol) solvent, is limited in using lignocellulose because of inefficient pentose consumption when fermenting sugar mixtures. To overcome this substrate utilization defect, a predicted glcG gene, encoding enzyme II of the D-glucose phosphoenolpyruvate-dependent phosphotransferase system (PTS), was first disrupted in the ABE-producing model strain Clostridium acetobutylicum ATCC 824, resulting in greatly improved D-xylose and L-arabinose consumption in the presence of D-glucose. Interestingly, despite the loss of GlcG, the resulting mutant strain 824glcG fermented D-glucose as efficiently as did the parent strain. This could be attributed to residual glucose PTS activity, although an increased activity of glucose kinase suggested that non-PTS glucose uptake might also be elevated as a result of glcG disruption. Furthermore, the inherent rate-limiting steps of the D-xylose metabolic pathway were observed prior to the pentose phosphate pathway (PPP) in strain ATCC 824 and then overcome by co-overexpression of the D-xylose proton-symporter (cac1345), D-xylose isomerase (cac2610), and xylulokinase (cac2612). As a result, an engineered strain (824glcG-TBA), obtained by integrating glcG disruption and genetic overexpression of the xylose pathway, was able to efficiently coferment mixtures of D-glucose, D-xylose, and L-arabinose, reaching a 24% higher ABE solvent titer (16.06 g/liter) and a 5% higher yield (0.28 g/g) compared to those of the wild-type strain. This strain will be a promising platform host toward commercial exploitation of lignocellulose to produce solvents and biofuels.     

Neuropilin-2 expression promotes TGF-β1-mediated epithelial to mesenchymal transition in colorectal cancer cells

Neuropilins, initially characterized as neuronal receptors, act as co-receptors for cancer related growth factors and were recently involved in several signaling pathways leading to cytoskeletal organization, angiogenesis and cancer progression. Then, we sought to investigate the ability of neuropilin-2 to orchestrate epithelial-mesenchymal transition in colorectal cancer cells. Using specific siRNA to target neuropilin-2 expression, or gene transfer, we first observed that neuropilin-2 expression endows HT29 and Colo320 for xenograft formation. Moreover, neuropilin-2 conferred a fibroblastic-like shape to cancer cells, suggesting an involvement of neuropilin-2 in epithelial-mesenchymal transition. Indeed, the presence of neuropilin-2 in colorectal carcinoma cell lines was correlated with loss of epithelial markers such as cytokeratin-20 and E-cadherin and with acquisition of mesenchymal molecules such as vimentin. Furthermore, we showed by surface plasmon resonance experiments that neuropilin-2 is a receptor for transforming-growth factor-β1. The expression of neuropilin-2 on colon cancer cell lines was indeed shown to promote transforming-growth factor-β1 signaling, leading to a constitutive phosphorylation of the Smad2/3 complex. Treatment with specific TGFβ-type1 receptor kinase inhibitors restored E-cadherin levels and inhibited in part neuropilin-2-induced vimentin expression, suggesting that neuropilin-2 cooperates with TGFβ-type1 receptor to promote epithelial-mesenchymal transition in colorectal cancer cells. Our results suggest a direct role of NRP2 in epithelial-mesenchymal transition and highlight a cross-talk between neuropilin-2 and TGF-β1 signaling to promote cancer progression. These results suggest that neuropilin-2 fulfills all the criteria of a therapeutic target to disrupt multiple oncogenic functions in solid tumors.     

Risk factors for campylobacteriosis of chicken, ruminant, and environmental origin: a combined case-control and source attribution analysis

Background

Campylobacteriosis contributes strongly to the disease burden of food-borne pathogens. Case-control studies are limited in attributing human infections to the different reservoirs because they can only trace back to the points of exposure, which may not point to the original reservoirs because of cross-contamination. Human Campylobacter infections can be attributed to specific reservoirs by estimating the extent of subtype sharing between strains from humans and reservoirs using multilocus sequence typing (MLST).

Methodology/Principal Findings

We investigated risk factors for human campylobacteriosis caused by Campylobacter strains attributed to different reservoirs. Sequence types (STs) were determined for 696 C. jejuni and 41 C. coli strains from endemic human cases included in a case-control study. The asymmetric island model, a population genetics approach for modeling Campylobacter evolution and transmission, attributed these cases to four putative animal reservoirs (chicken, cattle, sheep, pig) and to the environment (water, sand, wild birds) considered as a proxy for other unidentified reservoirs. Most cases were attributed to chicken (66%) and cattle (21%), identified as the main reservoirs in The Netherlands. Consuming chicken was a risk factor for campylobacteriosis caused by chicken-associated STs, whereas consuming beef and pork were protective. Risk factors for campylobacteriosis caused by ruminant-associated STs were contact with animals, barbecuing in non-urban areas, consumption of tripe, and never/seldom chicken consumption. Consuming game and swimming in a domestic swimming pool during springtime were risk factors for campylobacteriosis caused by environment-associated STs. Infections with chicken- and ruminant-associated STs were only partially explained by food-borne transmission; direct contact and environmental pathways were also important.

Conclusion/Significance

This is the first case-control study in which risk factors for campylobacteriosis are investigated in relation to the attributed reservoirs based on MLST profiles. Combining epidemiological and source attribution data improved campylobacteriosis risk factor identification and characterization, generated hypotheses, and showed that genotype-based source attribution is epidemiologically sensible.     

Rapid suppression of extension growth in dark-grown wheat seedlings by red light

Continuous recordings were made using a linear displacement transducer to investigate short-term growth responses of intact dark-grown wheat (Triticum aestivum L. cv Maris Huntsman) seedlings to red light. To eliminate any effect of light prior to the experimental treatments, the seedlings were grown and mounted on the transducer apparatus in total darkness. The growth kinetics after irradiation were complex and appeared to consist of three successive phases of growth deceleration. When the tip of the intact coleoptile was irradiated with red light from two opposite fiber bundles (fluence rate: 2 × 64 micromoles per square meter per second) for varying periods of time (10 seconds, 1 minute, 5 minutes, continuous), a decrease in extension rate was detectable after a latent period of 8 to 10 minutes. Up to 30 minutes after the start of the irradiation treatment, there was no difference in the kinetics of inhibition (about 20 to 25% inhibition) between the different lengths of irradiation. Extension rate reached a minimum (65% inhibition) at about 85 minutes, after which growth acceleration toward the dark control rate was observed. Far-red reversibility of the rapid effect of red light on growth was not observed, even when far-red light was given only 4 seconds after the end of 10 seconds red light. Short (15 seconds) far-red light did not induce a response.     

Time course of phytochrome-mediated changes in growth gradients on coleoptiles of Triticum aestivum L.

The length of parenchyma cells along the axis of dark-grown coleoptiles of Triticum aestivum L. and the pattern of competence for red-light-(R-) induced stimulation or inhibition of cell elongation in the course of coleoptile development were determined by microscopic measurements in a file of 240 cells from the tip to the base. On the basis of these measurements distinct zones (responding in different ways to R) were selected for studying the early time course of phytochrome-mediated growth-rate changes in intact coleoptiles by use of a sensitive transducer system. Between 2 d and 4 d after sowing dark-grown coleoptiles showed a graded incline in cell growth activity from the apex to the base (growth gradient). Whereas cell elongation in the coleoptile base ceased 4 d after sowing, cell elongation speeded up in the tip and middle region at that time. Those cells that grew slowly in darkness (tip and middle region between 2d and 3 d after sowing) were stimulated in growth by R-pulse irradiation (1 min R, 660 nm, 1000 J · m^–2). In contrast, the growth of fast-growing cells (base between 2 d and 4 d after sowing, tip and middle region between 4 d and 5 d after sowing) was inhibited by R. However, the starting time for R-induced growth changes was different for different coleoptile zones. The respective data point to the storage of a phytochrome-mediated signal in the cells of the middle region, until these cells become competent to respond to it; alternatively, Pfr, the far-red-light-absorbing form of phytochrome, may be stored in a stable form. Continuous recordings on the effect of R, far-red (FR) and R/FR on the zonal growth responses were made on intact coleoptiles, selected 3 d after sowing. During a 5-h investigation period the R-induced changes in growth rate could be divided into two phases: (i) A transient growth inhibition which started approx. 15 min after R. This response was qualitatively the same in all coleoptile zones investigated (tip, middle region, base). (ii) Zonal-specific growth responses which became measurable approx. 2.5 h after R, i.e. growth promotion in the tip, growth inhibition in the base and an adaptation of growth rate to the dark control level in the middle region. The R-induced growth rate changes were reversible by FR for both phases. Additional growth experiments on excised coleoptile segments under R and auxin application indicated that the zonal-specific growth promotion or inhibition may be not mediated by an influence of R on the auxin level.Abbreviations FR far-red light - Pfr far-red-light-absorbing form of phytochrome - R red light The technical assistance of Mrs. B. Liebe is gratefully acknowledged.     

Effects of different vertebrate growth factors on primary cultures of hemocytes from the gastropod mollusc,Haliotis tuberculata

Summary— A useful experimental system from primary cultures of hemocytes from Haliotis tuberculata has been established. Six days after initiation of the culture, the viability of hemocytes remained constant as measured by the MTT assay. In addition, hemocytes showed physiological responses as judged by protein and DNA syntheses in response to treatment with vertebrate growth factors. Porcine insulin and human epidermal growth factor (EGF) stimulated [³H]-leucine and [³H]-thymidine incorporation in hemocytes in a dose-dependent manner. No additive effect of insulin and EGF is observed either for [³H]-leucine or for [³H]-thymidine incorporation. The response of primary cultures of abalone hemocytes to vertebrate growth factors confirms their growth potential in vitro and provides a suitable model for further studies on regulation of the control of cellular processes such as cell growth, differentiation and migration in invertebrate cells.