~（14）C－涕灭威在旱田土壤中的降解

研究了１４Ｃ－涕灭威在５种土壤中（４ｐｐｍ,互．２２μＣｉ·５０ｇ－１土壤干重）的生物降解．模拟试验为密闭系统,土壤中水分含量为２２％,气温２０—３０Ｃ℃在供试的５种土壤中,北京肖家河的土壤降解最快,为施人放射剂量的５１．３％,以“ＣＯ：形式从土壤进出;２６．０％与土壤结合,只有２１．６％可以被抽出．取自浙江义乌的土壤降解较慢,收集到的１４ＣＯ２为施入量的２３．３％．土壤中加入杀菌剂红霉素或敌茵丹降解作用明显减慢．土壤提取物中涕灭威亚砜、涕灭威亚砜肟被确认是主要的代谢产物,还发现了少量的涕灭威砜,涕灭威亚砜腈涕灭威砜腈和涕灭威砜肟等降解物．     

14C-菲在营养液-火山石-小麦有控系统中的迁移和转化

利用放射性同位素示踪技术研究了¹⁴C标记菲在有控系统中的迁移转化。结果表明,¹⁴C-菲在有控系统中降解较快,施入药品24d后仅有0.32%的¹⁴C-菲存留在植物、营养液和火山石中。植物吸收的¹⁴C放射性大部分被结合到植物组织中,其它¹⁴C主要以菲的极性代谢物形态存在。     

阿维菌素在土壤中的微生物降解研究

运用恒温培养法研究了阿维菌素在土壤中的降解动力学．结果表明,非生物+微生物降解、非生物降解及微生物降解的半衰期分别为34．8、277．3和49．9d,说明阿维菌素在土壤中的降解主要由微生物引起．从试验土壤中分离到1株高效降解阿维菌素的菌株,经16S rDNA鉴定为嗜麦芽寡养单胞菌(Stenotrophomonas maltrophilia)．从该降解菌中提取的粗酶液米氏常数(Km)为6．78nmol·ml^-1,最大降解速率为81．5nmol·min^-1·mg^-1。     

甲基叔丁基醚微生物降解研究进展*

汽油添加剂甲基叔丁基醚(Methyl tert-Butyl Ether,MTBE)的水体污染问题近年引起广泛关注,因而微生物降解MTBE的研究也渐成热点。对MTBE的微生物降解研究现状进行简要综述,总结好氧条件下降解菌对MTBE的降解情况,以关键中间代谢物-叔丁基醇(tert-butyl alcohol,TBA)为分界点探讨微生物降解MTBE的两步可能途径,浅论MTBE微生物降解的影响因素。     

氰化物在土壤中的自然降解模拟实验

通过对3种含不同氰化物浓度的粘黄土泥样的测定,探索氰化物在粘土中的降解规律。结果表明：粘黄土对氰化物（CN^-）有较强的吸附与净化作用;CN^-浓度随时间的变化符合一级动力学模式;制备土样中CN^-的初始浓度高降解慢,初始浓度低降解快。     

13C-标记秸秆添加对DNA稳定性同位素探针试验结果的影响

【目的】稳定性同位素探针技术(stable isotope probing,SIP)是采用稳定性同位素示踪复杂环境中具有代谢活性微生物的有力工具。然而,在近期利用SIP技术的研究当中,我们发现~(13)C-标记物对试验本身有一定程度影响。例如研究土壤秸秆降解微生物,需将~(13)C-标记作物秸秆添加到土壤,利用微域培养实验和DNA-SIP技术解析主导降解微生物物种。但是~(13)C秸秆的添加以及不同土壤肥力水平是否会影响土壤微生物群落有待商榷。【方法】本研究采集江西鹰潭红壤试验站3种施肥处理(Control、NPK、OM)水稻土壤,分别添加自然丰度(12C)和~(13)C-标记的高丰度水稻秸秆,进行微域培养试验,研究两种秸秆添加下的响应物种以及不同丰度C对生物质气体的累积排放、细菌a-多样性以及群落结构的影响。【结果】研究发现,3种施肥土壤下,2种丰度秸秆处理间C累计排放无差异。但是,寡营养条件(Control)下,~(13)C-标记秸秆处理的细菌a-多样性高,12C秸秆处理群落异质性高,稳定性较差,无差异性物种;与~(12)C秸秆处理相比,富营养条件(NPK和OM)下,~(13)C-标记秸秆处理的细菌a-多样性和群落结构无差异,但存在差异物种,主要集中于变形菌门和稀有物种。【结论】本研究的结果表明~(13)C标记秸秆对微生物群落有一定影响,因此在后续的SIP试验中,高丰度秸秆虽可被用来作为标记底物,但需慎用。     

FGF14在神经退行疾病中的研究进展 *

成纤维细胞生长因子14(FGF14)是成纤维细胞生长因子家族中一员,主要在发育中及成熟的神经系统中表达。研究发现,FGF14在退行性神经系统中的脊髓小脑共济失调27型中发挥着重要的作用,FGF14的功能与各种离子通道关系密切,以钠离子通道为主,活性被神经元的兴奋性调节。根据FGF14的特点,归纳总结了FGF14目前的研究进展,为FGF14的基础和工程化研究提供理论依据。     

春小麦对土壤中14C-辛硫磷残留物的转移规律和途径的研究

经拌土处理施入盆钵土壤中的~(14)C-辛硫磷经土壤微生物和光的作用会降解。土壤中的这些辛硫磷残留物能被春小麦根系吸收,经茎转运到植株地上部分。茎只起输导作用,滞留的残留物较少;而叶子,特别是旗叶中能保持较高的残留水平。不同层次叶片累积的~(14)C-辛硫磷残留物再通过蒸腾、代谢和光解等途径不断转移消解,或以~(14)CO_2,或以其他含~(14)C化合物的形式向周围环境中逸出。春小麦叶片中的~(14)C-辛硫磷总残留提取物中约有50％的非光敏性物质。农药在土壤—植物—空气三者之间具有连续性,是农药生态毒理研究中一个必须注意的问题。     

NBPT在土壤中的降解及其影响因子

采用实验室培养方法研究了NBPT在土壤中的降解动态。结果表明,在未灭菌的土壤中,NBPT的半衰期为7.2~7.6 d,远远小于在灭菌土壤中22.4 d的半衰期;随着环境温度增高(20℃上升至30℃),NBPT降解速度略有提升(半衰期由7.6 d缩短至6.5 d);NBPT在黑暗条件下降解半衰期为4.5 d,而在光照条件下的半衰期为5.9 d。可见,几种试验因子对土壤中NBPT的降解均有不同程度的影响。其中土壤微生物是影响NBPT降解的主要因素,有利于土壤中微生物生长的环境因素,如偏酸的土壤,对土壤中NBPT的降解有促进作用。而葡萄糖则可能因为增加了土壤颗粒的团聚性及其还原性能,增加了土壤对NBPT的吸附而抑制了NBPT的降解。     

The abundance of nahAc genes correlates with the 14C-naphthalene mineralization potential in petroleum hydrocarbon-contaminated oxic soil layers

In this study, we evaluated whether the abundance of the functional gene nahAc reflects aerobic naphthalene degradation potential in subsurface and surface samples taken from three petroleum hydrocarbon contaminated sites in southern Finland. The type of the contamination at the sites varied from lightweight diesel oil to high molecular weight residuals of crude oil. Samples were collected from both oxic and anoxic soil layers. The naphthalene dioxygenase gene nahAc was quantified using a replicate limiting dilution-polymerase chain reaction (RLD-PCR) method with a degenerate primer pair. In the non-contaminated samples nahAc genes were not detected. In the petroleum hydrocarbon-contaminated oxic soil samples nahAc gene abundance [range 3 x 10(1)-9 x 10(4) copies (g dry wt soil)(-1)] was correlated (Kendall non-parametric correlation r2=0.459, p<0.01) with the aerobic 14C-naphthalene mineralization potential (range 1 x 10(-5)-0.1 d(-1)) measured in microcosms at in situ temperatures (8 degrees C for subsurface and 20 degrees C for surface soil samples). In these samples nahAc gene abundance was also correlated with total microbial cell counts (r2=0.471, p<0.01), respiration rate (r2=0.401, p<0.01) and organic matter content (r2=0.341, p<0.05). NahAc genes were amplified from anoxic soil layers indicating that, although involved in aerobic biodegradation of naphthalene, these genes or related sequences were also present in the anoxic subsurface. In the samples taken from the anoxic layers, the aerobic 14C-naphthalene mineralization rates were not correlated with nahAc gene abundance. In conclusion, current sequence information provides the basis for a robust tool to estimate the naphthalene degradation potential at oxic zones of different petroleum hydrocarbon-contaminated sites undergoing in situ bioremediation.     

The moss fauna 1: Tardigrades

The Tardigrada is described as a group of animals suitable for close study in project work. Reasons for their suitability are given and an illustrated key is included.     

Hongos queratinofílicos en suelos de parques de la ciudad de Corrientes,Argentina

BackgroundThe soil is a natural reservoir of keratinophilic fungi, which are a small but important group of filamentous fungi, some of which typically develop on keratinized tissues of living animals. There are numerous species of saprophytic fungi with recognized keratinophilic abilities, and several studies have been undertaken in order to link their presence to possible human disease.AimsTo know the biota of geophilic fungi in general and of keratinophilic fungi particularly in soils from two public parks.MethodsSoil samples from two public parks of Corrientes city, Argentina, were studied during two seasons, using the hook technique and serial dilutions for fungal isolation.ResultsUsing the hook technique, 170 isolates were classified into 17 genera and 21 species, among which it is worth mentioning the presence of Microsporum canis. Shannon index for keratinophilic fungi in autumn was 2.27, and 1.92 in spring. By means of the serial dilutions technique, 278 fungi isolated were identified into 33 genera and 71 species. Shannon index in autumn was 3.9, and 3.5 in spring.ConclusionsThe soils studied have particularly favorable conditions for the survival of pathogens and opportunistic geophilic fungi for humans and animals.     

A small ribosomal subunit (SSU) processome component, the human U3 protein 14A (hUTP14A) binds p53 and promotes p53 degradation

Ribosome biogenesis is required for normal cell function, and aberrant ribosome biogenesis can lead to p53 activation. However, how p53 is activated by defects of ribosome biogenesis remains to be determined. Here, we identified human UTP14a as an SSU processome component by showing that hUTP14a is nucleolar, associated with U3 snoRNA and involved in 18 S rRNA processing. Interestingly, ectopic expression of hUTP14a resulted in a decrease and knockdown of hUTP14a led to an increase of p53 protein levels. We showed that hUTP14a physically interacts with p53 and functionally promotes p53 turn-over, and that hUTP14a promotion of p53 destabilization is sensitive to a proteasome inhibitor but independent of ubiquitination. Significantly, knockdown of hUTP14a led to cell cycle arrest and apoptosis. Our data identified a novel pathway for p53 activation through a defect in rRNA processing and suggest that a ribosome biogenesis factor itself could act as a sensor for nucleolar stress to regulate p53.     

真核细胞蛋白酶体降解血红蛋白分子机理

从真核细胞蛋白酶体分子结构及血红蛋白分子结构出发,阐述真核细胞蛋白酶体降解血红蛋白的分子机理,以探索出调控降解血红蛋白的有效途径,为畜禽血液的综合利用提供理论依据。