胰高血糖素样肽-2对仔猪肠粘膜免疫影响及作用机制研究进展

此文就胰高血糖素样肽-2（glucagon-like peptide 2，GLP-2）对仔猪肠粘膜免疫功能的影响及其作用机制研究进展作一综述。     

新型绿色饲料添加剂—γ-氨基丁酸

γ-氨基丁酸(γ-aminobutyric acid,GABA)是中枢主要的抑制性神经递质,具有镇静、降血压、抗惊厥等生理作用。此外,GABA在外周神经及非神经的组织中还能发挥激素或营养因子的功能,对动物机体正常的生理功能起着重要的调节作用。     

浅谈绿化草坪的更新复壮

云南铝业股份有限公司所在地海拔约2100m,属北亚热带、低纬度、高原山地季风气候,常年气候干湿分明,年均降水量约1600mm。公司共有绿化草坪约12万m2。我们经过多年的摸索实践,找到了适合公司种植的草坪草种主要有:早熟禾、黑麦草、羊茅、剪股颖、三叶草等。由于草坪使用时间长,     

养菊的教训

其一、“一劳永逸”酿苦酒有一年6月底,我正在喷多效唑控制菊花高度时,一位花友来访。他见后说:“这样喷药麻烦,把多效唑拌到土里最省事。”他的话应和了我贪图省事的心理。于是,在未经亲自试验的情况下,次年我就全面地将多效唑拌土施用,每盆     

Preparation of anti-tetracycline antibodies and development of an indirect heterologous competitive enzyme-linked immunosorbent assay to detect residues of tetracycline in milk

Tetracycline (TC) is a broad-spectrum antibiotic used increasingly in animal husbandry to treat diseases or to promote growth as feed additives. To avoid using labor-intensive instrumental methods to detect residues of TC in food and food products, a simple and convenient indirect heterologous competitive enzyme-linked immunosorbent assay (ELISA) method for TC was developed using polyclonal antibody prepared in this study. Three new immunogens, TC-o-tolidine-bovine serum albumin (BSA), TC- 4-aminobenzoic acid-cationized BSA (cBSA), and TC-1,1'-carbonyldiimidazole-cBSA, were synthesized in this research to develop anti-TC antibodies. All antibodies raised in rabbits and coating antigens synthesized were screened and characterized using homologous and heterologous ELISA formats to select the best combination. An optimized ELISA gave an IC50 value of 3.92 mug/mL toward TC in PBS buffer. The specificity of the assay was studied by measuring cross-reactivity of the antibody with the structurally closely related compounds of chlortetracycline (112%) and oxytetracycline (<2%). The recovery rates from the TC-fortified raw milk samples were in the range of 74-116%, while the intra- and interassay coefficients of variation were <14.5 and <25.0, respectively.     

Molecular cloning and characterization of the gene encoding cold-active beta-galactosidase from a psychrotrophic and halotolerant Planococcus sp. L4

The gene bgaP encoding cold-active beta-galactosidase from a psychrotrophic and halotolerant Planococcus sp. L4 was cloned into Escherichia coli and sequenced. A sequence analysis of the DNA responsible for the BgaP gene revealed an open reading frame of 2031 bp encoding for a protein of 677 amino acid residues. The BgaP was heterologously expressed in E. coli and purified followed by Ni2+ affinity chromatography. The molecular mass of the native enzyme was approximately 156 kDa as determined by gel filtration. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the deduced amino acid sequence of the BgaP indicated molecular masses of 78 and 77.311 kDa, respectively, suggesting that the BgaP is a dimer. The purified BgaP had an isoelectric point of 4.8 and exhibited maximal activity at 20 degrees C and pH 6.8 under the assay conditions used. The enzyme is particularly thermolabile, losing all activity in only 10 min at 45 degrees C. It was able to hydrolyze lactose as a substrate, as well as o-nitrophenyl-beta-D-galactopyranoside (ONPG); the Km values with ONPG and lactose were calculated to be 5.4 and 20.4 mM at 5 degrees C, respectively. The catalytic efficiencies of BagP for lactose at 5 and 20 degrees C had 14 and 47 times more than that of E. coli beta-galactosidase at 20 degrees C, respectively. Therefore, cold-active beta-galactosidase from the psychrotrophic and halotolerant Planococcus sp. L4 could conceivably be developed to fulfill the practical requirements to enable its use for lactose removal in milk and dairy products at low temperature or a reporter enzyme for psychrophilic genetic systems.     

6-shogaol (alkanone from ginger) induces apoptotic cell death of human hepatoma p53 mutant Mahlavu subline via an oxidative stress-mediated caspase-dependent mechanism

Mahlavu cells, poorly differentiated and p53 mutants of a human hepatoma subline, are known to be highly refractory to a number of chemotherapeutic agents and radiotherapy due to their high expressions of multidrug resistance gene-1 (MDR-1) and Bcl-2 proteins. Thus, it is desirable to search for an alternative strategy for effective eradication of this type of cancer cells. We present evidence here for the first time that 6-shogaol (6-SG), an alkanone isolated from the rhizomes of ginger, can effectively induce apoptotic cell death of Mahlavu cells via an oxidative stress-mediated caspase-dependent mechanism. The cascade of events in 6-SG-induced apoptosis of these cells involved an initial overproduction of reactive oxygen species (ROS) followed by a severe depletion of intracellular glutathione (GSH) contents. Both events consequently entailed a significant drop in mitochondrial transmembrane potential (DeltaPsim), which ultimately activated the activities of caspases 3/7 resulting in the DNA fragmentation. Interestingly, we also found that N-acetylcysteine (NAC), an antioxidant and a precursor of GSH biosynthesis, could offer a near complete protection of apoptotic cell death exerted by 6-SG. Similarly, exogenously added GSH could also provide protection with an equal efficacy. However, it was paradoxical that both Boc-Asp(OMe)-fmk (a broad caspases inhibitor) and cyclosporin A (an mitochondrial permeability transition opening inhibitor) could only partially protect these cells from 6-SG-induced apoptosis. Taking these data into consideration, it is obvious that GSH depletion is the major contributing factor in arbitrating 6-SG-induced apoptosis of Mahlavu cells. In conclusion, we provide here a novel modality that can help to eradicate a p53 mutant of human hepatoma cells by using a natural consistent isolated form of ginger. These data also provide evidence to reaffirm the notion that consumption of certain foodstuffs can be beneficial to health because some of the constituents contained in them may be anticarcinogenic.     

Absorption and excretion of luteolin and apigenin in rats after oral administration of Chrysanthemum morifolium extract

Chrysanthemum morifolium extract (CME) has the protective effect on cardiovascular diseases. Luteolin and apigenin are two major bioactive components in vivo when CME is orally administrated to experimental animal. The present paper shows the study of the absorption and excretion of luteolin and apigenin in rats after a single oral dose of CME (200 mg/kg). The levels of luteolin and apigenin in plasma, urine, feces, and bile were measured by HPLC after deconjugation with hydrochloric acid or beta-glucuronidase/sulfatase. The results showed that the plasma concentrations of luteolin and apigenin reached the highest peak level at 1.1 and 3.9 h after dosing, respectively. The area under the concentration-time curves (AUC) for luteolin and apigenin were 23.03 and 237.6 microg h mL-1, respectively. The total recovery of the dose was 37.9% (6.6% in urine; 31.3% in feces) for luteolin and 45.2% (16.6% in urine; 28.6% in feces) for apigenin. The cumulative luteolin and apigenin excreted in the bile was 2.05% and 6.34% of the dose, respectively. All of the results suggest apigenin may be absorbed more efficiently than luteolin in CME in rats, and both luteolin and apigenin have a slow elimination phase, with a quick absorption, so a possible accumulation of the two flavonoids in the body can be hypothesized.     

Evolution of phenolic compounds and antioxidant activity during malting

Two barley varieties, Gan4 and Hamelin, were malted to investigate the evolution of phenolic compounds and antioxidant activity during malting. The antioxidant activity was evaluated with DPPH radical scavenging activity, ABTS radical cation scavenging activity, reducing power, and metal chelating activity. Results showed that malting had significant influences on individual and total phenolic contents as well as antioxidant activities of two barley varieties. The contents of some phenolic compounds and the antioxidant activities decreased significantly during steeping and the early stages of germination and then increased remarkably during the later stages of germination and subsequent kilning. The most phenolic compounds identified in barley were (+)-catechin and ferulic acid, which both changed significantly during malting. Moreover, results from the Pearson correlation analysis showed that there were good correlations among DPPH radical scavenging activity, ABTS radical cation scavenging activity, reducing power, total phenolic content and sum of individual phenolic contents during malting.     

柑橘愈伤组织内源激素代谢与体细胞胚胎发育能力关系的研究Ⅰ．柑橘不同愈伤组织体细胞胚胎发生能力的比较

为了探明柑橘愈伤组织内源激素代谢与体细胞胚胎发生能力的关系，研究了长期继代保存的纽荷尔脐橙和伏令夏橙不同愈伤组织的体细胞胚胎发生。结果表明，无论是在加吸3％蔗糖的MT增殖培养基上，还是在加有30mL/L甘油的MT分化培养基上，纽荷尔脐橙的胚性愈伤组织和二倍体伏令夏橙愈伤组织的体细胞胚胎发生能力均较强，而纽荷尔脐橙的非胚性愈伤组织，四倍体和六倍体伏令夏橙愈伤组织的体细胞胚胎发生能力较弱。