极端耐盐碱菌株的筛选及其菌肥对盐碱条件下小麦生长和土壤环境的影响

为获得具有盐碱地改良应用潜力的耐盐碱菌株,将采集于东营盐碱地的土样稀释涂布于pH 9、盐浓度100 g·L-1的Gibbson改良培养基上,共获得18株细菌.通过提高盐浓度、pH值,最终获得在pH 12、盐浓度20%的条件下仍然可以生长的极端耐盐碱菌株N14.对N14进行形态学、生理生化特征和16S rDNA序列分析鉴定,结果表明:菌株N14为马氏芽孢杆菌.盆栽试验结果表明,与盐碱土(CK)相比,N14菌肥可以显著提高小麦的生物量,株高、鲜重、干重分别提高了21.8%、57.9%、41.7%;显著增加小麦叶绿素a、叶绿素b、叶绿素总量,增长率分别为36.4%、20.0%、31.7%;显著提高盐碱土壤中的蔗糖酶、脲酶和碱性磷酸酶的活性,增长率分别为23.2%、68.8%、106.5%;显著提高小麦根系的超氧化物歧化酶、过氧化物酶和过氧化氢酶的活性,增长率分别为109.6%、17.8%、50%;显著减少小麦根系丙二醛的含量,减少率为39.8%.本研究为极端耐盐碱菌的应用提供了一条新思路,为盐碱地的改良提供了一条新途径.     

不同光周期条件下棉花粉蚧的生长发育和种群增长能力

【目的】 研究阐明不同光周期条件下棉花粉蚧Phenacoccus solenopsis Tinsley实验种群的发育历期、繁殖和数量动态规律,为制定该虫防治对策、研究治理措施等提供科学依据。【方法】 以扶桑为寄主,在温度27±1℃、相对湿度70%±5%、光照强度4 000 lx及不同光周期（8L∶16D, 10L∶14D, 12L∶12D, 14L∶10D和16L∶8D）条件下,观察了棉花粉蚧实验种群的生长发育特性和繁殖能力,组建了实验种群生命表。【结果】 不同光周期处理下棉花粉蚧1龄若虫和3龄若虫的发育历期及雌成虫产仔量均发生了变化,但不同龄期若虫存活率之间差异不大。随着光照时间增加,棉花粉蚧1龄若虫、3龄若虫发育速率加快,8 h光照时发育历期分别为5.43 d和6.35 d,而16 h光照时发育历期分别缩短至4.16 d和4.75 d;整个若虫发育历期也由8 h光照时的15.54 d缩短至16 h光照时的12.74 d,世代历期由27.75 d缩短至23.45 d。长光照时雌虫更早进入产仔期,也有利于雌虫繁殖后代,16 h光照时进入产仔期是18日龄,8 和10 h光照时均推迟至22日龄;16 h光照时单雌产仔量为417.06头,明显高于12 ,10 和8 h光照时的353.59,347.61和336.00头。长光照条件下实验种群趋势指数(I)明显较大,增长潜能更大,16,10 和8 h光照时种群趋势指数分别为 175.37,133.94和141.99。该虫生命表参数表明,随着光照时间加长净增值率（R₀）呈逐渐增大趋势,8, 10,12,14和16 h光照时分别为88.57,86.85,100.77,124.16和126.86;内禀增长率、周限增长率表现类似的规律,8～16 h光照时内禀增长率（r_m）为0.1616～0.2066,周限增长率（λ）为1.1754～1.2294;而种群倍增时间（t）则随着光照时加长而缩短,8～16 h光照时为4.29～3.36 d。【结论】 长光照有利于棉花粉蚧生长发育和繁殖,世代历期缩短,种群增长潜能变强。     

Neonatal imprinting and hepatic cytochrome P-450 II. Partial purification of a sex-dependent and neonatally imprinted form(s) of cytochrome P-450

A new form of cytochrome P-450 was partially purified from hepatic microsomes of neonatally imprinted rats (adult male and adult male castrated at four weeks of age). This new form of cytochrome P-450 appears to have an apparent molecular weight of approximately 50,000 daltons as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis. It appears that this form of cytochrome P-450 is either absent or present in low concentrations in cytochrome P-450 preparations isolated from neonatally nonimprinted rats (adult female and adult male castrated at birth). Reconstitution of testosterone hydroxylase and benzphetamine N-demethylase activities of this partially purified cytochrome P-450 revealed that the presence of testosterone 16α-hydroxylase activity, an imprintable microsomal enzyme, was in parallel with the imprinting status of the animals; a significantly higher activity was detected in the neonatally imprinted than that of the nonimprinted animals. This was in contrast to the nonimprintable benzphetamine N-demethylase, testosterone 7α-and 6β-hydroxylase activities which exhibited no correlation with the imprinting status of the animals. We have prepared antisera from rabbits using the partially purified cytochrome P-450 preparations from adult male rats as antigens. These antisera inhibited microsomal testosterone 16α- and 7α-hydroxylase activities in a concentration-dependent manner, without impairing 6β-hydroxylase activity. These data suggest that the partially purified cytochrome P-450 from adult male rats consists of both imprintable (16α-) and nonimprintable (7α-) testosterone hydroxylase activities. The antisera formed immunoprecipitant lines in the Ouchterlony double diffusion plates with partially purified cytochrome P-450 from both neonatally imprinted and nonimprinted adult rats. The immunoprecipitant lines, as stained by coomassie blue, suggest the homology of the cytochrome P-450 preparations from neonatally imprinted and nonimprinted rats. Immunoabsorption of the antisera against neonatally nonimprinted, partially purified cytochrome P-450 completely removed the immunoprecipitant lines without appreciably impairing the inhibitory effects of antisera on the microsomal testosterone 16α-and 7α-hydroxylase activities. In contrast, immunoabsorption of the antisera against partially purified cytochrome P-450 from adult male rats (imprinted) abolished completely both the immunoprecipitant lines and the inhibition on microsomal testosterone hydroxylation reaction (16α and 7α). The inhibitory actin of antisera on testosterone hydroxyulation was also abolished upon boiling the antisera at 100°C for 5 minutes. The biochemical and immunochemical data in this study suggest that the neonatally imprintable form or forms of hepatic microsomal cytochrome P-450 accounts for a small fraction of the bulk of total cytochrome P-450. However, the existence of this form of cytochrome P-450 is regulated by gonadal hormones during the neonatal period and accounts for the major imprintable sex difference in drug and steroid metabolism in adulthood.     

Decreased methylation of the major mouse long interspersed repeated DNA during aging and in myeloma cells

Sequences of DNA that hybridize on Southern blots with cloned EcoR1 1.3 kb (ER1) of long interspersed repeated sequence (L1Md) of mouse have been examined in genomic DNA of neonatal mice, livers and brains of adult mice (3, 10, 27, and 30 mo old), and the solid myeloma tumor MOPC-315. The isoschizomers Hpa II (CCGG or mCCGG) and Msp I (CCGG or CmCGG) were used to assess methylation. We found that the L1Md sequence is fully methylated in young animals but demethylated in myeloma. Demethylation of L1Md sequence also occurred in aged animals. By scanning the autoradiogram, we found that approximately 8% of the 10(4)-10(5) copies have been demethylated in 27-mo-old liver.     

源自大黄鱼肠道柠檬酸杆菌的外切几丁质酶的特性分析（英文）北大核心CSCD

【目的】从饲喂富含几丁质饲料的大黄鱼肠道分离具有几丁质分解功能的菌株并分离鉴定新的几丁质酶。【方法】利用胶体几丁质平板分离饲喂杂鱼的大黄鱼肠道中的几丁质分解菌。对几丁质酶基因chi-X进行了克隆并在大肠杆菌中表达。对CHI-X的酶学性质进行了分析。【结果】从饲喂杂鱼的大黄鱼肠道内容物中分离出1株具有几丁质分解功能的费氏柠檬酸杆菌,其中的几丁质酶基因编码1个含493个氨基酸残基的蛋白,其中包含一个糖苷水解酶18家族催化域。CHI-X对胶体几丁质具有分解功能。最适p H和温度分别是4.0和60°C。CHI-X具有很强的pH稳定性,在pH 3.0–11.0的范围培育1 h仍保留90%左右的活性。Mn^(2+),Li^+和K^+可促进CHI-X酶活,Ag^+对CHI-X有抑制作用。CHI-X对蛋白酶和石斑鱼肠道内容物有较强的抗逆性。CHI-X可分解胶体几丁质为N-乙酰葡萄糖胺和N-乙酰葡萄糖胺二聚体,表明它是一个几丁质外切酶。最后,CHI-X和另一个几丁质酶Chi565表现出酶活性的加和效应。【结论】分离自肠道菌的CHI-X能很好适应海水鱼类的肠道环境,可以作为温水海水养殖鱼类的饲料添加剂使用。     

黄腐酸和甜菜碱预处理对干旱胁迫下平邑甜茶生理特性及光合的影响

该研究以平邑甜茶[Malus hupehensis(Pamp.)Rehd.]2年生实生苗为材料,通过盆栽试验于干旱处理前3d分别连续喷施黄腐酸(FA)、甜菜碱(GB)和复配(FA+GB),并以清水为对照(CK)进行预处理,比较分析不同预处理对干旱胁迫下平邑甜茶的生理及光合特性变化,探讨FA和GB对平邑甜茶的抗旱生理机制。结果显示:(1)与对照相比,FA、GB和FA+GB预处理均能够显著提高平邑甜茶叶片相对含水量,且FA的保水性效果最佳。(2)3种预处理均可显著促进干旱胁迫下叶片可溶性蛋白、可溶性糖和脯氨酸含量增加,且FA+GB预处理后在干旱胁迫下叶片可溶性糖和脯氨酸累积量显著高于单施FA或GB。(3)3种预处理均可显著提高干旱胁迫下平邑甜茶幼苗的SOD、POD、CAT活性,并显著降低MDA的积累速度及其累积量,且以FA+GB预处理的MDA含量最低、抗氧化酶活性最高。(4)GB和FA+GB预处理下平邑甜茶的净光合速率、瞬时水分利用率显著高于CK和FA,且FA+GB处理下改善光合特性的效果最佳,GB次之。研究表明,单独喷施黄腐酸和甜菜碱及两者配施预处理均能够增加干旱胁迫下平邑甜茶的渗透调节物质和相对含水量,提高叶片的保水性,调节抗氧化物酶活性,降低丙二醛含量,增加细胞膜稳定性,改善光合性能,进而提高平邑甜茶的抗旱能力,且以复配喷施(FA+GB)预处理的效果最好。     

探讨肠道菌群对膝骨关节炎治疗的影响

膝骨关节炎是一种中老年人常见的慢性疾病,因其发病率及致残率高,严重影响患者的生存质量。膝骨关节炎不仅增加了患者及其家庭乃至社会的经济压力,而且还加重了心理负担。治疗方案虽然多,但目前尚无根治方法,而且疗效也参差不齐。肠道菌群作为人体巨大的微生物宝库,拥有着很大的潜力,这使之成为了科研领域一个新的研究热点,其对膝骨关节炎的影响也成为了人们关注的焦点。本文通过查阅相关文献,从慢性炎症、代谢性疾病、成骨细胞以及破骨细胞这四个方面来阐述和总结肠道菌群与膝骨关节炎的关系,以期为临床上治疗膝骨关节炎提供新的方法与思路。