Properties of liver mitochondria from iron-loaded rats.

The increased iron content in livers from iron-loaded rats is almost exclusively confined to the mitochondria. The ten- to twenty-fold higher level of nonheme iron in such mitochondria decreases the respiratory control with pyruvate-malate, but not with 3-hydroxybutyrate or succinate as substrates, and has no effect on the capacity for phosphorylation and substrate oxidation. Iron-loaded mitochondria have a malondialdehyde level which is about three times higher than that of control mitochondria, even after repeated washings with bovine serum albumin and EDTA. This is suggestive of an on-going process of lipid oxidation presumably catalyzed by the accumulated iron. Differences between the present in vivo data and in vitro results obtained by others are discussed.     

Plankton secondary productivity and biomass: Their relation to lake trophic state

The biomass and production of the most important zooplankton species were followed for two years in three lakes of varying trophic status in the Lake Washington watershed. Cladocerans and copepods were of equal importance in the biomass of lakes Findley and Chester Morse (both oligotrophic), whereas, copepods were the main biomass component in Lake Sammamish (mesotrophic). Cladocerans dominated production in lakes Sammamish and Chester Morse, while in Findley Lake their productive role, like that of biomass, was equal to that of the copepods. Rotifers contributed a relatively small biomass and production.Data from this study supported Hillbricht-Ilkowska's postulate that the energy transfer efficiency between the primary and secondary trophic levels decreases with increasing trophic state. Energy transfer efficiencies for the lakes of this study expressed as a two year mean of the ratio-secondary: primary production, were as follows: Findley Lake-0.13; Chester Morse Lake-0.08; and Lake Sammanish-0.04.On the other hand, the hypothesis of Patalas that the secondary productivity: biomass ratio (P/B) tended to increase in proportion to the productivity of a lake, could not be supported. Lake Sammamish, the most productive of the lakes studied, had a P/B ratio of 0.03 while lakes Findley and Chester Morse had P/B ratios of 0.04.     

Effects of different feeding levels on moulting,growth and conversion efficiency of Palaemon lamarrei

Pigment analyses by TLC were carried out during and after the peak of a Peridinium bloom in Lake Kinneret (Israel). During the experimental period considerable changes occurred in the absolute and relative amounts of the various pigments, especially carotene, diadinoxanthine, peridinin, chlorophyll a and chlorophyl c. The ratio between total Carotenoid to total chlorophyll content is also followed. Our findings show that considerable changes in pigment composition in natural phytoplankton can occur while the species composition remains constant.     

设施菜田不同碳氮管理对反硝化菌结构和功能的影响

【目的】通过6年长期定位试验,比较设施菜田不同碳氮管理下反硝化菌结构和功能的差异。【方法】采用末端限制性片段多态性(T-RFLP)和变性梯度凝胶电泳(DGGE)方法分别分析nir K/nir S和nos Z型反硝化菌群结构特征,利用自动连续在线培养监测体系(Robot系统)测定分析NO/(NO3-+NO2-)和N2O/(N2O+N2)产物比,并通过乙炔抑制法测定反硝化酶活性。【结果】传统施肥处理(CN)显著改变了nir K和nos Z型反硝化菌的结构,增加了NO/(NO3-+NO2-)和N2O/(N2O+N2)产物比。nir S型菌受碳氮管理影响较小。减氮(RN)和添加秸秆处理(RN+S)的nir K和nos Z型反硝化菌结构与CN处理的差异性显著,且会显著降低NO/(NO3-+NO2-)和N2O/(N2O+N2)产物比;与CN和RN相比,RN+S显著增加反硝化酶活性。【结论】设施菜田长期传统施肥措施改变了反硝化菌的结构和功能,增加土壤自身的NO产生能力并减弱了N2O还原N2的能力。减氮和添加秸秆管理能形成自身的反硝化菌群结构,并降低NO和N2O排放风险;秸秆的添加会促进反硝化潜在速率,降低菜田NO3-淋洗风险。     

基于城市微气候模拟软件的城市道路绿化带对PM2.5消减作用的研究

随着经济的快速发展及机动车保有量的持续增长,车辆造成的道路污染问题日益严重。广州作为中国重要的经济发展城市,交通源排放问题高度集中,机动车排放是城市PM2.5的主要来源之一,开展减缓城市道路污染危害的研究具有重要意义。本研究为调查绿化带对广州城市道路PM2.5的影响,运用实测与城市微气候模拟软件（ENVI-met）模拟结合的研究方法,实测并分析城市道路空间PM2.5的浓度分布及其影响因素,使用实测数据对模拟软件进行验证分析,模拟研究理想道路模型下不同高宽比、风向等因素及绿化带植配类型对PM2.5的消减作用。研究表明：（1）城市道路空间PM2.5浓度分布受污染源、街道高宽比、风速风向、绿化带等综合影响,自然消减情况下,其主要受风速风向和高宽比双因素影响;（2）通常街道高宽比越大,越有利于道路空间PM2.5的扩散;（3）城市道路空间PM2.5自然沉降最小距离为12 m,0-12 m范围内应保持无障碍物的开敞环境,PM2.5消减的关键范围是12-24 m,此范围内可以利用生态手段沉降颗粒物;（4） PM2.5消减率受绿化带和风向的双控制,应根据主导风向选择绿化带植配方式。在主导风平行面和垂直迎风面绿化带对PM2.5有正消减效应,建议植配类型为"乔-乔+灌+草";在主导风垂直背风面绿化带对PM2.5呈负消减效应,植配类型为"乔-灌"绿化带消减率接近于自然消减率,而植配类型为"乔-灌+草"和"乔-乔+灌+草"的绿化带加重了颗粒物在该区域的积聚。     

Beyond facial width-to-height ratios: bizygomatic width is highly sexually dimorphic when adjusting for allometry

A large and ever-growing literature implicates male facial width-to-height ratio (bizygomatic width divided by facial height) as a secondary sexual trait linked to numerous physical and psychological perceptions. However, this research is based entirely on the premise that bizygomatic width is sexually dimorphic, which recent research has called into question. Unfortunately, statisticians for the last 125 years have noted that morphological ratio measurements may engender spurious correlations and biased effect-size estimates. In the current study, we find that bizygomatic width is highly sexually dimorphic (equivalent d = 1.39), even after adjusting for 92 allometric measurements, including multiple facial height and other craniofacial measurements (equivalent d = 1.07) in a sample of 6068 men and women. By contrast, facial width-to-height ratio (fWHR) measurements demonstrated a statistical pattern consistent with the age-old argument that morphological ratio measurements may engender spurious correlations and biased effect-size estimates. Thus, when avoiding facial ratio measurements and adjusting for allometry in craniofacial measures, we found strong support for a key premise in the human evolutionary and behavioural sciences that bizygomatic width exhibits male-biased sexual dimorphism.     

Endotoxemia,vitamin D and premature biological ageing in Arab adults with different metabolic states

There are limited studies on the association of endotoxin, a potent mediator of gut-derived inflammation and telomere length (TL). We investigated (1) the influence of adiposity on endotoxin and TL amongst Saudi adults according to type 2 diabetes mellitus (T2DM) status and (2) the influence vitamin D may have on TL attrition. Anthropometric data and fasting blood samples were taken from 775 Saudi adults visiting different primary care centers in Riyadh [387 T2DM and 388 non-T2DM]. TL, derived from peripheral blood mononuclear cells, was analyzed by Quantitative real-time polymerase chain reaction and circulating endotoxin levels by Limulus Amebocyte Lysate assay. Subjects were stratified based on obesity and T2DM status. A significant lower TL was observed in the non-obese T2DM group as compared with their non-obese, non-T2DM counterparts (p = 0.002). Significant inverse associations between TL, endotoxin and endotoxin activity were observed in the cohort with obesity. Regression analysis showed that endotoxin was a significant predictor for TL in all subjects and even after stratification according to subgroups; with variances perceived in circulating TL stronger among non-T2DM obese (10%; p = 0.003) than non-T2DM non-obese (12%; p = 0.007). Also, in the non-T2DM group, TL and HDL-cholesterol predicted 29% of the variances perceived in 25(OH)D (p < 0.001). Taken together these findings show that circulating endotoxin and 25(OH)D are associated with premature biological ageing influenced by adiposity and metabolic state; suggesting future intervention studies to manipulate gut microbiome and or vitamin D levels may offer ways to mitigate premature TL attrition.     

生长光强对亚热带自然林两种木本植物稳定碳同位素比、细胞间CO2浓度和水分利用效率的影响

生长于１００％、４０％和１６％自然光下的荷木和黧蒴幼苗叶片稳定碳同位素比（δ１３Ｃ,－‰）,细胞间ＣＯ２浓度（Ｃｉ）和水分利用效率（ＷＵＥ）有一定的差别。１６％和４０％弱光下,δ１３Ｃ的负值增加－０．５４Ｊ‰到－０．８９‰。Ｃｉ增大８．１－１３．２μｉＬ－１,ＷＵＥ则下降６－２４％。结果表明,叶片的水分和气体交换特性受生长光强的调节,叶片的δ１３Ｃ值可反映其生长过程中受光的强弱状况。     

胰酶对皮肤角质细胞分离和传代的影响

考察不同的胰酶浓度及其作用时间对角质细胞分离和传代的影响。实验发现在胰酶浓度 0.25%时作用5min可获得的总活细胞量和有克隆形成能力的细胞量均优于其它培养条件 ;而在胰酶浓度0.05%时作用 5min可获得最大的原代角质细胞贴壁率。随着胰酶浓度的提高 ,传代角质细胞的贴壁率和贴壁速率常数以及克隆形成率均随之增加 ,因此在传代培养时使用 0.25%胰酶浓度进行消化较为适宜.