Transcription analysis of genes involved in lipid metabolism reveals the role of chromium in reducing body fat in animal models

Chromium was proposed to be an essential trace element over 50 years ago and has been accepted as an essential element for over 30 years. The recent studies indicated that the addition of supra nutritional amounts of chromium to the diet can only be considered as having pharmacological effects. However, the precise mechanism through which chromium acts on lipid, carbohydrate, protein and nucleic acid metabolism are relatively poor studied. To uncover, at least partially, the role of chromium in lipid metabolism, in this study, we evaluated the expression status of eight important genes, involved in fat biosynthesis and lipid metabolism, in four different tissue types (liver, subcutaneous fat, visceral fat, and longissimus muscle) in domestic goat kids feeding on three different chromium levels. The quantitative real-time PCR (RT-PCR) was established for expression analyses with HSP90 gene was used as reference gene. The results showed that supplementation of goats with 1.5 mg/day chromium significantly decreases the expression of the ACC1, DGAT1, FABP4, FAS, HSL, LEP genes, but does not affect the expression of the LPL and SCD1 genes in all studied tissues. This study highlights, for the first time, the role of supra nutritional levels of chromium in lipid biosynthesis and metabolism. These findings are of especial importance for improving meat quality in domestic animals.     

肉鸭养殖过程中发酵床垫料菌群结构变化的研究

【目的】探究发酵床使用时间和肉鸭粪便微生物对发酵床垫料菌群结构、总菌和大肠杆菌数量的影响。【方法】采集江苏某肉鸭发酵床养殖场内刚制作完成的发酵床垫料样品,及其饲养4批次、8批次后的垫料样品,同时采集各批次34日龄肉鸭粪便样品,采用变性梯度凝胶电泳技术(Denaturing gradient gel electrophoresis,DGGE)、16S rRNA基因序列分析和实时荧光定量PCR (Quantitative real-time PCR)技术对发酵床使用过程中垫料菌群结构进行定性和定量研究。【结果】0批次(D0)与4批次(D4)、8批次(D8)垫料菌群相似性分别为68.81%、70.82%,而4批次与8批次间垫料菌群的相似性则达81.93%,显著高于D4、D8与D0间相似性(P<0.05)。条带6、8 (最相似菌分别为Leqionella tunisiensis、Pedobacte bauzanensis)在3个时间点垫料菌群中均表现优势,且含量较为稳定;条带10 (最相似菌为Rummeliibacillus suwonesis)仅在2个重复使用垫料菌群中表现优势;条带12、13 (最相似菌分别是Psychrobacter sp. PRwf-1、Iamia majanohamensis)共同存在于垫料样和粪便样。肉鸭粪便中大肠杆菌的数量显著高于4批次、8批次垫料中的数量(P<0.05),与0批次垫料间差异不显著(P>0.05)。【结论】使用时间和肉鸭粪便微生物共同影响了发酵床垫料菌群结构和数量,菌群结构随使用时间的延长而趋于稳定。     

Engineering carotenoid production in mammalian cells for nutritionally enhanced cell-cultured foods

Metabolic engineering of mammalian cells has to-date focused primarily on biopharmaceutical protein production or the manipulation of native metabolic processes towards therapeutic aims. However, significant potential exists for expanding these techniques to diverse applications by looking across the taxonomic tree to bioactive metabolites not synthesized in animals. Namely, cross-taxa metabolic engineering of mammalian cells could offer value in applications ranging fromfood and nutrition to regenerative medicine and gene therapy. Towards the former, recent advances in meat production through cell culture suggest the potential to produce meat with fine cellular control, where tuning composition through cross-taxa metabolic engineering could enhance nutrition and food-functionality. Here we demonstrate this possibility by engineering primary bovine and immortalized murine muscle cells with prokaryotic enzymes to endogenously produce the antioxidant carotenoids phytoene, lycopene and β-carotene. These phytonutrients offer general nutritive value and protective effects against diseases associated with red and processed meat consumption, and so offer a promising proof-of-concept for nutritional engineering in cultured meat. We demonstrate the phenotypic integrity of engineered cells, the ability to tune carotenoid yields, and the antioxidant functionality of these compounds in vitro towards both nutrition and food-quality objectives. Our results demonstrate the potential for tailoring the nutritional profile of cultured meats. They further lay a foundation for heterologous metabolic engineering of mammalian cells for applications outside of the clinical realm.     

A review of nutritional effects on fat composition of animal products with special emphasis on n-3 polyunsaturated fatty acids

The fatty acid composition of animal products (eggs, milk and meat) is the reflect of both the tissue fatty acid biosynthesis and the fatty acid composition of ingested lipids. This relationship is stronger in monogastrics (pigs, poultry and rabbits) than in ruminants, where dietary fatty acids are hydrogenated in the rumen. There is an increasing recognition of the health benefits of polyunsaturated fatty acids (PUFA), because these fatty acids are essential for humans. In addition, the ratio n-6/n-3 fatty acids in the human diet is important. This ratio by far exceeds the recommended value of 5. Therefore, inclusion of fish meals, or n-3 PUFA rich oils, or linseed in animal diets is a valid means of meeting consumer demand for animal products that are nutritionally beneficial.The studies that are undertaken on animals mainly use diets supplemented with linseed, as a source of n-3 fatty acids. The use of linseed diets generally leads to an increased n-3 fatty acid content in animal products (egg, meat, milk) in ruminants and monogastrics. Recent studies have also demonstrated that neither the processing nor the cooking affects the PUFA content of pork meat or meat products.The ability of unsaturated fatty acids, especially those with more than two double bonds, to rapidly oxidise, is important in regulating the shelf life of animal products (rancidity and colour deterioration); however, a good way to avoid such problems is to use antioxidant products (such as vitamin E) in the diet.Some studies also show that it is not necessary to feed animals with linseed-supplemented diets for a long time to have the highest increase in PUFA content of the products. So, short-term diet manipulation can be a practical reality for industry.As the market for n-3 PUFA enriched products is today limited in most countries, other studies must be undertaken to develop this kind of production.     

Predation on giant flying squirrels (Petaurista philippensis) by black crested gibbons (Nomascus concolor jingdongensis) at Mt. Wuliang, Yunnan, China

Predation on vertebrates is infrequent in gibbons. In a 14-month field study of the central Yunnan black crested gibbon (Nomascus concolor jingdongensis) at Mt. Wuliang, Yunnan, China, we observed gibbons attacking, killing and eating giant flying squirrels (Petaurista philippensis). During 845 h of observation on one study group, the gibbons attacked giant flying squirrels 11 times, and succeeded in 4 cases. Although all members of the group attempted to attack the squirrels, all four successful attacks were made by the same adult female. The victims were infants in three cases and a juvenile or sub-adult in one case. Black crested gibbons also attacked adult giant flying squirrels by grabbing their long tails and throwing them from the canopy, but they failed to catch or kill the prey in three cases observed. Passive meat sharing occurred in three out of four successful cases. Besides hunting giant flying squirrels, the black crested gibbons also ate eggs or chicks in two birds’ nests and one lizard.     

The energetic significance of cooking

While cooking has long been argued to improve the diet, the nature of the improvement has not been well defined. As a result, the evolutionary significance of cooking has variously been proposed as being substantial or relatively trivial. In this paper, we evaluate the hypothesis that an important and consistent effect of cooking food is a rise in its net energy value. The pathways by which cooking influences net energy value differ for starch, protein, and lipid, and we therefore consider plant and animal foods separately. Evidence of compromised physiological performance among individuals on raw diets supports the hypothesis that cooked diets tend to provide energy. Mechanisms contributing to energy being gained from cooking include increased digestibility of starch and protein, reduced costs of digestion for cooked versus raw meat, and reduced energetic costs of detoxification and defence against pathogens. If cooking consistently improves the energetic value of foods through such mechanisms, its evolutionary impact depends partly on the relative energetic benefits of non-thermal processing methods used prior to cooking. We suggest that if non-thermal processing methods such as pounding were used by Lower Palaeolithic Homo, they likely provided an important increase in energy gain over unprocessed raw diets. However, cooking has critical effects not easily achievable by non-thermal processing, including the relatively complete gelatinisation of starch, efficient denaturing of proteins, and killing of food borne pathogens. This means that however sophisticated the non-thermal processing methods were, cooking would have conferred incremental energetic benefits. While much remains to be discovered, we conclude that the adoption of cooking would have led to an important rise in energy availability. For this reason, we predict that cooking had substantial evolutionary significance.     

PRNP gene variation in Pakistani cattle and buffaloes

Bovine spongiform encephalopathy (BSE) is a neurodegenerative prion protein misfolding disorder of cattle. BSE is of two types, classical BSE and atypical BSE which in turn is of two types, H-type BSE and L-type BSE. Both H-type BSE and L-type BSE are primarily sporadic prion disorders. However, one case of H-type BSE has recently been associated with E211K polymorphism in the prion protein gene (PRNP). Two polymorphisms in the bovine PRNP are also associated with susceptibility to classical BSE: a 23 bp insertion/deletion (indel) in the PRNP promoter region and a 12 bp indel in the first intron. No information regarding BSE susceptibility in Pakistani cattle is available. The present study aimed at achieving this information. A total of 236 cattle from 7 breeds and 281 buffaloes from 5 breeds were screened for E211K polymorphism and 23 bp and 12 bp indels employing triplex PCR. The E211K polymorphism was not detected in any of the animals studied. The 23 bp insertion allele was underrepresented in studied cattle breeds while the 12 bp insertion allele was overrepresented. Both 23 bp and 12 bp insertion alleles were overrepresented in studied buffalo breeds. Almost 90% of alleles were insertion alleles across all studied buffalo breeds. The average frequency of 23 bp and 12 bp insertion alleles across all studied cattle breeds was found to be 0.1822 and 0.9407, respectively. There were significant differences between Pakistani and worldwide cattle in terms of allele, genotype and haplotype frequencies of 23 bp and 12 bp indels. The higher observed frequency of 12 bp insertion allele suggests that Pakistani cattle are relatively more resistant to classical BSE than European cattle. However, the key risk factor for classical BSE is the dietary exposure of cattle to contaminated feedstuffs.     

Myosin light chain isoforms retain their species-specific electrophoretic mobility after processing, which enables differentiation between six species: 2DE analysis of minced meat and meat products made from beef, pork and poultry

Investigation of protein changes as well as authentication of meat is particularly difficult in processed meat products due to their different composition, complexity and very often inhomogeneity. The aim of this study was to check if the inter-species differences in the expression of myosin light chain (MLC) isoforms observed in raw meat were retained in meat products. MLCs from mixtures of minced meat (16 variants), frankfurters and sausages (15 products) made from cattle, pig, chicken, turkey, duck and goose were analysed by 2DE. Species-specific patterns of MLC isoforms were observed in all the mixtures and processed meat products. Relatively small degradation was observed in the MLCs after processing. Image analysis enabled species identification of the meat in all samples when the content of meat of one species was not lower than 10%. However, it was impossible to differentiate between all the six species under investigation on the basis of individual isoform. It was possible when the combination of all the three isoforms (myosin light chain 1 fast, myosin light chain 2 fast and myosin light chain 3 fast) was analysed. The results evidenced that MLCs have potential to be used as markers in authentication of meat products made from the analysed six species.     

DNA based classification of food associated Enterobacteriaceae previously identified by Biolog GN Microplates

Enterobacteriaceae are frequently isolated from food products and it is essential to have methods for correct identification for both food hygiene and epidemiology reasons. Phenotypic methods are not always sufficient and have to be supplemented by DNA based methods. In the present study, 70 strains of Enterobacteriaceae derived from milk, fish and meat that had previously been identified by Biolog GN Microplates were genomically classified together with 15 representative type strains of species of Enterobacteriaceae. The field strains were dominated by Hafnia alvei, Serratia liquefaciens and Rahnella aquatilis. All strains were subjected to temporal temperature gel electrophoresis (TTGE) analysis using amplicons encompassing the V3, V4 and V9 variable regions of the 16S rRNA gene. Selected strains were analysed by ribotyping and partial 16S rDNA sequencing. The type strains were differentiated into 10 different TTGE groups. Two of the groups contained two type strains. Enterobacter aerogenes and Klebsiella planticola were not distinguished due to their identical sequences and Yersinia ruckeri and Citrobacter freundii showed the same migration pattern. The 70 food strains could be differentiated into 14 TTGE groups where 33 strains (47.1%) could be assigned to TTGE groups including type or reference strains. Rahnella strains were dispersed into three TTGE groups of which one group corresponded to Rahnella genomospecies 1 and one to genomospecies 3. The grouping of Rahnella strains was supported by ribotyping and phylogenetic analysis. TTGE can be a useful additional tool for identification on the species level of food related Enterobacteriaceae.     

Toxoplasma gondii infections in chickens – performance of various antibody detection techniques in serum and meat juice relative to bioassay and DNA detection methods

Chickens, especially if free-range, are frequently exposed to Toxoplasma gondii, and may represent an important reservoir for T. gondii. Poultry products may pose a risk to humans, when consumed undercooked. In addition, chickens are regarded as sensitive indicators for environmental contamination with T. gondii oocysts and have been used as sentinels. The aim of the present study was to determine the suitability of commonly used antibody detection methods, i.e. the modified agglutination test (MAT), IFAT and ELISA to detect T. gondii-infected chickens. Samples of experimentally and naturally infected chickens were used. The infection state of all chickens was determined by Magnetic-Capture (MC-) real-time PCR (RT PCR). Naturally exposed chickens were additionally examined by mouse bioassay and conventional RT PCR on acidic pepsin digests (PD-RT PCR). Blood serum and meat juice of various sources were tested for antibodies to T. gondii. In naturally infected chickens, there was substantial agreement between the mouse bioassay and MC-RT PCR or the mouse bioassay and conventional PD-RT PCR. PD-RT PCR was slightly more sensitive than MC-RT PCR, as all (26/26) bioassay-positive chickens also tested positive in at least one of the tissues tested (heart, drumstick). By MC-RT PCR, 92.3% (24/26) of the naturally infected bioassay-positive chickens were positive. The diagnostic sensitivity of MC-RT PCR was clearly related to the organ examined. Based on a quantitative assessment of the MC-RT PCR results in experimentally infected chickens, brain and heart tissues harbored an at least 100?times higher parasite concentration than breast, thigh or drumstick musculature. In naturally infected chickens, only three out of 24 birds, which were MC-RT PCR-positive in heart samples, also tested positive in drumstick musculature. Under experimental conditions, the agreement between MC-RT PCR and the serological techniques revealed 100% diagnostic sensitivity and specificity. Under field conditions, examinations of sera by ELISA, IFAT and MAT showed good performance in identifying chickens that were positive in either a mouse bioassay, MC-RT PCR, or PD-RT PCR as illustrated by diagnostic sensitivities of 87.5%, 87.5% and 65.2%, respectively, and diagnostic specificities of 86.2%, 82.8% and 100%, respectively. The examination of meat juice samples from breast, drumstick or heart musculature revealed similar or even better results in the ELISA. The results in the MAT with meat juice from breast musculature were less consistent than those of ELISA and IFAT because a number of negative chickens tested false-positive in the MAT. The MAT performed similar to ELISA and IFAT when applied to test meat juice samples collected from heart, thigh or drumstick musculature.