Cadmium causes the oxidative modification of proteins in pea plants

In pea (Pisum sativum L.) leaves from plants grown in the presence of 50 µm CdCl₂ the oxidative production of carbonyl groups in proteins, the rate of protein degradation and the proteolytic activity were investigated. In leaf extracts the content of carbonyl groups measured by derivatization with 2,4‐dinitrophenylhydrazine (DNPH), was two‐fold higher in plants treated with Cd than in control plants. The identification of oxidized proteins was carried out by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis of proteins derivatized with DNPH and immunochemical detection with an antibody against DNPH. The intensity of the reactive bands was higher in plants exposed to Cd than in controls. By using different antibodies some of the oxidized proteins were identified as Rubisco, glutathione reductase, manganese superoxide dismutase, and catalase. The incubation of leaf crude extracts with increasing H₂O₂ concentrations showed a progressive enhancement in carbonyl content and the pattern of oxidized proteins was similar to that found in Cd‐treated plants. Oxidized proteins were more efficiently degraded, and the proteolytic activity increased 20% due to the metal treatment. In peroxisomes purified from pea leaves a rise in the carbonyl content similar to that obtained in crude extracts from Cd‐treated plants was observed, but the functionality of the peroxisomal membrane was not apparently affected by Cd. Results obtained demonstrate the participation of both oxidative stress, probably mediated by H₂O₂, and proteolytic degradation in the mechanism of Cd toxicity in leaves of pea plants, and they appear to be involved in the Cd‐induced senescence previously reported in these plants.     

Plasma lipid peroxidation and erythrocyte antioxidants status in workers exposed to nickel

The objectives were to investigate the plasma lipid peroxidation and erythrocyte antioxidants status in workers exposed to nickel. The study groups comprised 69 nickel plating workers and 50 office workers residing in the same city, but away from the place of work of the study group subjects, considered as control group. Urinary nickel concentration was determined by graphite furnace atomic absorption spectrophotometry. The plasma lipid peroxidation and erythrocyte antioxidants were measured by spectrophotmetric methods. The plasma lipid peroxidation level was significantly increased in nickel-platers and their helpers as compared with controls. Erythrocyte antioxidants were significantly decreased in the nickel-platers compared with the controls. The level of plasma lipid peroxidation was positively and erythrocyte antioxidants were negatively and significantly correlated with the urine nickel levels. Multiple regression analysis assessed the oxidative stress associated with nickel and other potential confounding factors such as body mass index, the consumption of green vegetables, coffee, tea, smoking and alcohol consumption. Analysis showed that the lifestyle confounding factors: the consumption of green vegetables, smoking and alcohol, were not significantly associated with oxidative stress. The exposure to nickel, body mass index and coffee consumption were significantly associated with oxidative stress. The results show that the increased plasma lipid peroxidation and decreased erythrocyte antioxidants levels observed in nickel-exposed workers could be used as biomarkers of oxidative stress.     

Carcass and meat quality traits of chickens fed diets concurrently supplemented with vitamins C and E under constant heat stress

The objective of this study was to determine if a diet supplemented simultaneously with vitamins C and E would alleviate the negative effects of heat stress, applied between 28 and 42 days of age, on performance, carcass and meat quality traits of broiler chickens. A total of 384 male broiler chickens were assigned to a completely randomized design, with a 2×3 factorial arrangement (diet with or without vitamin supplementation and two ambient temperatures plus a pair-feeding group) and 16 replicates. Chickens were kept in thermoneutral conditions up to 28 days of age. They were then housed in groups of four per cage, in three environmentally controlled chambers: two thermoneutral (22.5 and 22.6°C) and one for heat stress (32°C). Half the chickens were fed a diet supplemented with vitamins C (257 to 288 mg/kg) and E (93 to 109 mg/kg). In the thermoneutral chambers, half of the chickens were pair-fed to heat stressed chickens, receiving each day the average feed intake recorded in the heat stress chamber in the previous day. Meat physical quality analyses were performed on the pectoralis major muscle. No ambient temperature×diet supplementation interaction effects were detected on performance, carcass, or meat quality traits. The supplemented diet resulted in lower growth performance, attributed either to a carry-over effect of the lower initial BW, or to a possible catabolic effect of vitamins C and E when supplemented simultaneously at high levels. Heat stress reduced slaughter and carcass weights, average daily gain and feed intake, and increased feed conversion. Growth performance of pair-fed chickens was similar to that of heat stressed chickens. Exposure to heat stress increased carcass and abdominal fat percentages, but reduced breast, liver and heart percentages. Pair-fed chickens showed the lowest fat percentage and their breast percentage was similar to controls. Heat stress increased meat pH and negatively affected meat color and cooking loss. In pair-fed chickens, meat color was similar to the heat stressed group. Shear force was not influenced by heat stress, but pair-fed chickens showed the tenderest meat. In conclusion, reduction in growth performance and negative changes in meat color in heat stressed chickens were attributed to depression in feed intake, whereas negative changes in body composition, higher meat pH and cooking loss were credited to high ambient temperature per se. Diet supplementation with vitamins C and E as antioxidants did not mitigate any of these negative effects.     

自然越冬期软枣猕猴桃枝条组织结构及内源激素的变化特征

该试验以抗寒性不同的5年生软枣猕猴桃品种‘魁绿’、‘丰绿’和‘96-6’为试验材料,测定分析自然越冬期间枝条组织解剖结构、细胞膜透性和内源激素GA3、ABA、IAA含量水平的变化,以明确不同品种软枣猕猴桃越冬期间对低温的适应能力及其内在生理机制,为软枣猕猴桃抗寒品种的选育及鉴别提供理论依据。结果表明:(1)软枣猕猴桃枝条木质部比率大小依次为‘魁绿’>‘96-6’>‘丰绿’,皮层比率依次为‘丰绿’>96-6’>魁绿’,二者表现趋势相反,且‘魁绿’枝条的解剖结构与其他两品种差异显著。(2)在自然越冬期间,各品种软枣猕猴桃枝条相对电导率和MDA含量随温度变化均呈先升后降的趋势,在温度最低的1月份达到最高,其中‘魁绿’枝条的相对电导率和MDA含量变化幅度最小,而‘丰绿’受低温影响较大。(3)在11月份至2月份,随自然温度的变化,各品种软枣猕猴桃枝条的GA3和IAA含量均呈先降低后升高的变化趋势,ABA含量则呈先升后降的趋势,且都在1月份分别达到最低或最高值。研究发现,在自然越冬期间,低温对3个软枣猕猴桃品种的组织解剖结构、膜透性及内源激素含量均都造成较大的影响,品种‘魁绿’枝条的木质部比率最大、皮层比率最小,相对电导率和MDA含量变化幅度最小,内源激素含量GA3和ABA/GA3变化趋势较小,故其抗寒性比‘丰绿’和‘96-6’更强。     

太子参内生细菌RPB-32的分类鉴定及其代谢物对小鼠肠道微生物群落的影响

【背景】肠道微生物在宿主肠道微环境稳态中起着至关重要的作用。众多因子,如抗生素、饮食和年龄等会干扰这种微平衡,引起菌群平衡发生改变,进而影响到机体健康状况。太子参具有心肌保护、增加免疫、抗氧化、抗糖尿病、抗应激、抗疲劳等药理活性,而太子参内生菌代谢物对肠道微生物的调控作用以及可能对机体健康的影响目前还未见报道。【目的】研究太子参内生菌RPB-32分类地位及其代谢提取物对小鼠肠道微生物的调节作用,以探讨其对机体健康的影响。【方法】对RPB-32进行传统方法和分子鉴定。将120只KM小鼠随机分为溶剂对照组(3%乙醇)及石油醚提取物、正丁醇提取物和乙酸乙酯提取物低、中、高剂量组(n=12)。小鼠灌胃处理14 d后采集粪便,通过选择性培养基培养及宏基因组测序[溶剂对照(S.F.1为3%乙醇溶液)、乙酸乙酯提取物高剂量组(S.F.2)]检测灌胃前后小鼠肠道微生物的变化。【结果】常规传统方法与分子鉴定结果表明RPB-32为芽孢杆菌(Bacillus sp.)。与空白对照组相比,给予内生菌代谢提取物的乙酸乙酯中剂量组、乙酸乙酯高剂量组、正丁醇低剂量组、正丁醇中剂量组及正丁醇高剂量组乳酸菌数量明显增加,正丁醇中剂量组的肠球菌和正丁醇高剂量组的肠杆菌数量明显减少。S.F.2与S.F.1基于门、属和种水平上的微生物群落结构相比表明:S.F.2的拟杆菌门(Bacteroidetes)数量明显增加,而厚壁菌门(Firmicutes)数量明显减少;S.F.2的Bacteroides、Prevotella、Parabacteroides、Akkermansia、Helicobacter、Butyricimonas、Alistipes、Ruminococcus、Muribaculum、Barnesiella、Odoribacter、Azospirillum、Mucispirillum和Lactobacillus数量明显增多,Rikenella、Angelakisella、Clostridium、Oscillibacter、Pseudoflavonifractor、Flavonifractor、Mailhella、Desulfovibrio、Faecalibacterium、Eubacterium、Lachnoclostridium、Hungatella、Butyrivibrio、Blautia、Dorea、Ruminiclostridium、Roseburia、Anaerotruncus和Butyricicoccus等数量减少;S.F.2的Bacteroides sartorii、Bacteroides caecimuris、Bacteroides uniformis、Parabacteroides chinchillae、Parabacteroides glodsteinii、Helicobacter bilis、Bacteroides fragilis、Bacteroides vulgatus、Bacteroides thetaiotaomicron和Butyricimonas virosa等数量明显增多,Faecalibacterium prausnitzii、Rikenella microfusus、Flavonifractor plautii、Mailhella massiliensis和Clostridium clostridioforme等数量减少。【结论】初步判断太子参内生芽孢杆菌RPB-32代谢物(BM)对肠道微生物组成有明显影响,可能对机体糖脂降解、抗感染和抗炎等方面有改善作用。     

子宫内膜癌中的lncRNA-miRNA-mRNA ceRNA网络的整合分析

子宫内膜癌(uterine corpus endometrial carcinoma, UCEC)是危害女性健康的癌症之一,但其发生发展机制尚不完全清楚。基因的异常表达在细胞癌变过程中发挥着重要的作用。本研究利用生物信息学方法对UCEC中异常表达的基因进行网络调控分析,为UCEC的机制研究及预后治疗提供理论依据。首先,利用"limma"包筛选得到差异表达的RNA分子;接着,利用R软件中的"GDCRNATools"包构建lncRNA-miRNA-mRNAceRNA网络;最后,利用DAVID(TheDatabasefor Annotation,Visualization and Integrated Discovery)、R软件中的"survival"包、MCODE(Molecular COmplex Detection)插件、StarBase数据库等对ceRNA网络中的RNA分子进行综合分析。结果显示,在UCEC中,我们鉴定了1 319个mRNA、68个lncRNA及100个miRNA为差异表达的RNA分子。同时,利用这些UCEC中的差异表达RNA分子,成功构建了ceRNA网络,结果表明,HCG11、LINC00958、LINC00667、MAGI2-AS3和AC093010.3可能具有ceRNA的功能。通过进一步对该网络成员的分析,结果发现,该网络中的mRNA分子聚集于内皮细胞增殖、细胞骨架和锌离子结合负调控等生物学过程中。生存分析显示,hsa-miR-449a、LINC00958、PKIA和DPYSL2等19个差异表达的RNA分子与UCEC患者预后显著相关。最后,利用MCODE插件对ceRNA网络进行筛选,共获得一个子网络,其成员分别是LINC00667、hsa-miR-449a、hsa-miR-34a-5p和RECK。该研究结果提示,在UCEC的发生发展中存在lncRNA、miRNA和mRNA的差异表达,并且这些RNA分子之间存在ceRNA网络模式的调控,其中一些关键分子与患者的预后相关,这将为进一步研究与理解UCEC的发病机制及预后提供理论依据。     

Banana defence responses to Cosmopolites sordidus feeding and methyl jasmonate application

Each year 25–75% of banana and plantain yields are lost because of rhizome damages caused by banana weevil (Cosmopolites sordidus) in growing regions of sub‐Saharan Africa. However, the specific plant defence response of the rhizome tissue in relation to the C. sordidus attack is unknown. Consequently, in this study, we evaluated whether plant defence substances in the rhizome are correlated with the degree of larval damage and whether applications of methyl jasmonate (MJ) elicit a greater induction of the plant defence potential against C. sordidus. Moreover, we attempted to reveal cellular modifications in response to the root feeding herbivore through histochemical staining. The banana cultivars “Km5” and “Mbwazirume” with tolerance and susceptibility to C. sordidus, respectively, were used in a pot experiment to evaluate percent rhizome damage, leaf chlorophyll content, total phenolic content (TPC), antioxidant capacity and cell morphology in response to C. sordidus attack and/or MJ applications compared to untreated control plants. We found that C. sordidus‐induced rhizome damage was 30% in the susceptible cultivar but less than 5% in the tolerant cultivar. The percent rhizome damage was not related to leaf chlorophyll content but showed a significant negative linear relationship to both TPC and antioxidant capacity. Larvae feeding induced a considerably greater increase of polyphenolic defence compounds in Km5 than in Mbwazirume; however, this response was opposite in the MJ treatment, suggesting that the phytohormone induced the susceptible plant to invest more into the synthesis of defence chemicals that in turn lead to reduced C. sordidus damage. Tissue staining demonstrated a greater deposition of lignin and suberin in C. sordidus challenged rhizome, presumably to seal off healthy tissue with a physical barrier from continued pest attack. It is concluded that MJ induces polyphenolics in susceptible Mbwazirume banana that reduced C. sordidus damage.