Metal complexation by histidine-rich peptides confers protective roles against cadmium stress in Escherichia coli as revealed by proteomics analysis

The underlying mechanism and cellular responses of bacteria against toxic cadmium ions is still not fully understood. Herein, Escherichia coli TG1 expressing hexahistidine-green fluorescent protein (His6GFP) and cells expressing polyhistidine-fused to the outer membrane protein A (His-OmpA) were applied as models to investigate roles of cytoplasmic metal complexation and metal chelation at the surface membrane, respectively, upon exposure to cadmium stress. Two-dimensional gel electrophoresis (2-DE) and two-dimensional difference in gel electrophoresis (2D-DIGE) in conjunction with mass spectrometry-based protein identification had successfully revealed the low level expression of antioxidative enzymes and stress-responsive proteins such as manganese-superoxide dismutase (MnSOD; +1.65 fold), alkyl hydroperoxide reductase subunit C (AhpC; +1.03 fold) and DNA starvation/stationary phase protection protein (Dps; −1.02 fold) in cells expressing His6GFP in the presence of 0.2 mM cadmium ions. By contrarily, cadmium exposure led to the up-regulation of MnSOD of up to +7.20 and +3.08 fold in TG1-carrying pUC19 control plasmid and TG1 expressing native GFP, respectively, for defensive purposes against Cd-induced oxidative cell damage. Our findings strongly support the idea that complex formation between cadmium ions and His6GFP could prevent reactive oxygen species (ROS) caused by interaction between Cd2+ and electron transport chain. This coincided with the evidence that cells expressing His6GFP could maintain their growth pattern in a similar fashion as that of the control cells even in the presence of harmful cadmium. Interestingly, overexpression of either OmpA or His-OmpA in E. coli cells has also been proven to confer protection against cadmium toxicity as comparable to that observed in cells expressing His6GFP. Blockage of metal uptake as a consequence of anchored polyhistidine residues on surface membrane limited certain amount of cadmium ions in which some portion could pass through and exert their toxic effects to cells as observed by the increased expression of MnSOD of up to +9.91 and +3.31 fold in case of TG1 expressing only OmpA and His-OmpA, respectively. Plausible mechanisms of cellular responses and protein mapping in the presence of cadmium ions were discussed. Taken together, we propose that the intracellular complexation of cadmium ions by metal-binding regions provides more efficiency to cope with cadmium stress than the blockage of metal uptake at the surface membrane. Such findings provide insights into the molecular mechanism and cellular adaptation against cadmium toxicity in bacteria

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Effects of different finishing feeding strategies for culled cows on lipid and organoleptic characteristics of the meat

Culled dairy cows (n=32) were either slaughtered immediately after culling-off (control) or subjected to a finishing period of 12 weeks. For finishing, three different diets were tested. A forage-only group was fed with ad libitum with corn silage. Two other groups either received a high-fiber concentrate feed (crude rice bran) or a concentrate feed with lower fiber content (cassava pulp). Cows were slaughtered on four days with two cows per treatment each. Samples of the Longissimus dorsi were individually excised 24 hrs post-mortem. Feeds were analyzed for proximate contents and fatty acid profile. In the LD, apart from fatty acid analysis, thiobarbituric acid reactive substances (TBARS), color and sensory grading was determined in LD aged for 0, 1, 3, 5, and 7 days in vaccuumized form. Treatment effects were determined by analysis of variance. Finishing on corn silage only increased the proportions of conjugated linoleic acids, docosahexaenoic acid and total polyunsaturated fatty acids (PUFA) and led to rather dark meat. The other traits remained widely unaffected. Adding crude rice bran to the finishing diet did not cause a lot of differences to control. The lipids in the LD of the rice-bran fed cows had higher PUFA proportions and a lower shelf life. Finishing with a diet lower in fiber increased intramuscular fat to 6.7% vs. 3.4-4.2% in the other groups. Concomitantly, sensory scoring in terms of tenderness, juiciness, flavor intensity and overall acceptability was mostly highest. Concerning fatty acid profile (except palmitic acid), TBARS and color the meat of the group receiving cassava pulp resembled that of the control. In conclusion, it seems advantageous in terms of lipid- and sensoryrelated sense to finish culled cows either with high-quality forage alone or this forage supplemented with cassava pulp

Current situation and future prospects for beef production in Thailand — A review

Thailand is a country of native beef cattle resource farming. It has undergone rapid social and economic change in the past decade. Agricultural growth has been maintained by increasing the production of rice and cassava. Changing economic status also provides opportunities for beef cattle producers to meet increasing consumer demand for beef. Finishing beef cattle numbers in Thailand were about 1.0 M head in 2015. Beef produced in Thailand has exclusively been for domestic consumption. Only 1% of Thailand’s beef cattle are for the premium market which is based on marbling score, 40% are sold into modern markets that consider muscling of cattle, and the remainder enter traditional markets. Cross-bred cattle for the premium market are raised within intensive systems. Most producers of premium beef are members of beef cooperatives, or have invested in their enterprises at high levels. Culled cow (native or cross-bred cattle) are mainly for small holder farm production. Malaysia, Indonesia, and other members of the Asian Economic Community (AEC) are set to become the largest beef market, which has been confirmed by 2015 through 2020 forecasts for consumption of beef that must increasingly be halal. These circumstances are likely to be challenging for beef producers in Thailand to gain a share of this market. Integration across all sectors involved in beef production in Thailand will be required

Too “sexy” for the field? Paired measures of laboratory and semi-field performance highlight variability in the apparent mating fitness of Aedes aegypti transgenic strains

Background Evaluating and improving mating success and competitive ability of laboratory-reared transgenic mosquito strains will enhance the effectiveness of proposed disease-control strategies that involve deployment of transgenic strains. Two components of the mosquito rearing process, larval diet quantity and aquatic environment - which are linked to physiological and behavioural differences in adults - are both relatively easy to manipulate. In mosquitoes, as for many other arthropod species, the quality of the juvenile habitat is strongly associated with adult fitness characteristics, such as longevity and fecundity. However, the influence of larval conditioning on mating performance is poorly understood. Here, we investigated the combined effects of larval diet amount and environmental water source on adult male mating success in a genetically modified strain of Aedes aegypti mosquitoes in competition with wild-type conspecifics. Importantly, this research was conducted in a field setting using low generation laboratory and wild-type lines. Results By controlling larval diet (high and low) and rearing water source (field-collected and laboratory water), we generated four treatment lines of a genetically modified strain of Ae. aegypti tagged with fluorescent sperm. Laboratory reared mosquitoes were then competed against a low generation wild-type colony in a series of laboratory and semi-field mating experiments. While neither food quantity nor larval aquatic environment were found to affect male mating fitness, the transgenic lines consistently outperformed wild-types in laboratory competition assays, an advantage that was not conferred to semi-field tests. Conclusions Using a model transgenic system, our results indicate that differences in the experimental conditions of laboratory- and field-based measures of mating success can lead to variation in the perceived performance ability of modified strains if they are only tested in certain environments. While there are many potential sources of variation between laboratory and field lines, laboratory adaptation - which may occur over relatively few generations in this species - may directly impact mating ability depending on the context in which it is measured. We suggest that colony-hybridization with field material can potentially be used to mitigate these effects in a field setting. Release programs utilising mass-produced modified laboratory strains should incorporate comparative assessments of quality in candidate lines

Effect of deep bedding floor and fermented feed supplement on productive performance, carcase, meat quality and fatty acid profile of crossbred pigs

This study determined the effects of deep bedding floor and fermented feed supplement on the growth performance, carcase, meat quality, and fatty acid profile of crossbred pigs. Thirty-two ((Thai native × Meishan) × Duroc) crossbreds were organised in a 2 × 2 factorial arrangement in a completely randomised design. Factor A was a deep bedding floor (DB) or solid bedding of concrete floor (SB). Factor B was a feed type of concentrate feed supplemented with a fresh banana stem (BF + CON) or fermented banana stem (FF + CON). Growth performance, carcase traits, chemical composition, meat quality, and fatty acid profile were determined. The final weight, average daily gain, and feed conversion ratio of pigs reared on SB were significantly higher than those of pigs raised on DB. The backfat thickness and loin eye area of SB pork were also higher than those of DB pork (p < .05). Feed type had an effect on the percentage of rib, fat content, and TBARS on days 0, 1, and 3. FF + CON feed were lower, but shear force value and a grilling loss percentage of FF + CON were higher than those of BF + CON. The effect of the interaction between floor and feed types was found in the belly of four lean cut and rib percentage, fat content, and pH value in the longissimus dorsi muscle at 24 h and TBARS on Days 0, 1, 3, and 7 (p < .05). Pigs on the DB floor showed inferior carcase composition but slightly better meat quality than pigs raised on SB.HIGHLIGHTS Pigs on the concrete floor performed better than pigs on the deep bedding floor regarding final weight, average daily gain, and feed conversion ratio. The pork of pigs fed fermented banana stem showed lower lipid peroxidation that that of pigs fed fresh banana stem. Floor-type and feed type had no effect on the fatty acid profile of pork

Population genetic structure of the malaria vector Anopheles minimus in Thailand based on mitochondrial DNA markers.

BACKGROUND: The malaria vector Anopheles minimus has been influenced by external stresses affecting the survival rate and vectorial capacity of the population. Since An. minimus habitats have continuously undergone ecological changes, this study aimed to determine the population genetic structure and the potential gene flow among the An. minimus populations in Thailand. METHODS: Anopheles minimus was collected from five malaria transmission areas in Thailand using Centers for Disease Control and Prevention (CDC) light traps. Seventy-nine females from those populations were used as representative samples. The partial mitochondrial cytochrome c oxidase subunit I (COI), cytochrome c oxidase subunit II (COII) and cytochrome b (Cytb) gene sequences were amplified and analyzed to identify species and determine the current population genetic structure. For the past population, we determined the population genetic structure from the 60 deposited COII sequences in GenBank of An. minimus collected from Thailand 20&nbsp;years ago. RESULTS: The current populations of An. minimus were genetically divided into two lineages, A and B. Lineage A has high haplotype diversity under gene flow similar to the population in the past. Neutrality tests suggested population expansion of An. minimus, with the detection of abundant rare mutations in all populations, which tend to arise from negative selection. CONCLUSIONS: This study revealed that the population genetic structure of An. minimus lineage A was similar between the past and present populations, indicating high adaptability of the species. There was substantial gene flow between the eastern and western An. minimus populations without detection of significant gene flow barriers