糖皮质激素非基因组效应的研究

在过去的几十年间,人们认为糖皮质激素（glucocorticoid,GC）仅仅是通过改变基因的表达来发挥其生理作用,这个过程需要几个小时来完成。然而,近年来越来越多的证据表明GC对激素分泌、神经元兴奋性、机体行为及细胞形态、糖类代谢等具备快速效应,这些过程往往在数秒钟或者分种内完成,这种作用机制被称为GC的非基因组作用机制。GC的非基因组作用主要可能通过两种不同的机制起作用：（1）通过细胞膜上或者细胞质内结构未知的糖皮质激素受体（glucocorticoid Recptor,GR）来发挥非基因组作用,即为特异性非基因组效应,（2）GC主要通过改变细胞膜理化作用来发挥效应。也称为非特异性非基因组效应（non-specific nongenomic effects,NSNE）。本文通过阐述近年来GC的非基因组的作用的最新研究进展并且讨论了这些非基因组作用临床治疗过程中的联系。对糖皮质激素基因组和非基因组作用机制的深入了解有助于指导我们在临床合理用药并减少其副作用。     

普通玉米籽粒性状的遗传效应分析

采用二倍体种子遗传模型及其分析方法,研究了５个玉米籽粒性状的直接效应、母体效应和细胞质效应．分析结果表明,各性状的遗传同时受种子直接效应和母体效应的影响,细胞质基因对百粒重和粒宽具有极显著影响．除粒长、粒厚的直接显性效应与母体显性效应间的协方差外,直接效应与母体效应间的协方差均不显著．因此,通过母体植株的表现可对这些性状进行有效的选择．Ｓ_２２和 ８７－１是改良粒重的优良亲本．选择粒较宽的自交系作母本有利于提高后代选系及Ｆ_１的百粒重．     

Across species‐pool aggregation alters grassland productivity and diversity

Plant performance is determined by the balance of intra‐ and interspecific neighbors within an individual's zone of influence. If individuals interact over smaller scales than the scales at which communities are measured, then altering neighborhood interactions may fundamentally affect community responses. These interactions can be altered by changing the number (species richness), abundances (species evenness), and positions (species pattern) of the resident plant species, and we aimed to test whether aggregating species at planting would alter effects of species richness and evenness on biomass production at a common scale of observation in grasslands. We varied plant species richness (2, 4, or 8 species and monocultures), evenness (0.64, 0.8, or 1.0), and pattern (planted randomly or aggregated in groups of four individuals) within 1 × 1 m plots established with transplants from a pool of 16 tallgrass prairie species and assessed plot‐scale biomass production and diversity over the first three growing seasons. As expected, more species‐rich plots produced more biomass by the end of the third growing season, an effect associated with a shift from selection to complementarity effects over time. Aggregating conspecifics at a 0.25‐m scale marginally reduced biomass production across all treatments and increased diversity in the most even plots, but did not alter biodiversity effects or richness–productivity relationships. Results support the hypothesis that fine‐scale species aggregation affects diversity by promoting species coexistence in this system. However, results indicate that inherent changes in species neighborhood relationships along grassland diversity gradients may only minimally affect community (meter) – scale responses among similarly designed biodiversity–ecosystem function studies. Given that species varied in their responses to local aggregation, it may be possible to use such species‐specific results to spatially design larger‐scale grassland communities to achieve desired diversity and productivity responses.     

Bacterial survival in evaporating deposited droplets on a teflon-coated surface

Understanding of bacterial survival in aerosols is crucial for controlling infection transmission via airborne aerosols and/or large droplets routes. The cell viability changes of four bacteria species (Escherichia coli K12 JM109; Acinetobacter sp. 5A5; Pseudomonas oleovorans X5; and Staphylococcus aureus X8), three Gram-negative and one Gram-positive, in a large evaporating droplet of size 1,800 μm in diameter on teflon-coated slides were measured using the LIVE/DEAD BacLight solution and a microscope. Droplets of three levels of salinity (0, 0.9, and 36% w/v) were tested. All four species survived well during the droplet evaporation process, but died mostly at the time when droplets were dried out at 40–45 min. The final bacteria survival rate after droplets were completely dried was dependent on bacteria species and the salinity of the suspension solution. Droplet evaporation over the first 35–40 min had no adverse effect on bacterial survival for the droplets tested. The lethal effect of desiccation was found to be the most important death mechanism.     

片断森林植物多样性及其保护和恢复价值

森林片断化是导致生物多样性丧失最严重的单一因素。在片断森林中植物多样性除与片断面积有关外,还受边缘效应、瞬时取样效应、驰豫效应、远距离扩散的挽救效应以及背景生态系统的性质等影响。本文阐述了在这些综合因素影响下,片断森林中植物种类、丰富、性质的变化。由于这些综合因素的影响,不少片断森林尚有较高的保护价值,但需建立合适的评价体系和标准。片断森林在确定生态恢复目标、为恢复实践提供种源等方面也有重要价值。提出了对片断森林的保护措施。     

大坝的生态效应:概念、研究热点及展望

大坝产生的生态效应涉及范围广、周期长,在对社会经济发展起到积极作用的同时,也对生态、环境造成了一定的影响。在评述国内外对大坝生态效应概念和内涵理解的基础上,提出了大坝生态效应链和生态效应网的概念。依据大坝建设和运行的特点,结合流域生态系统的特征分别论述了大坝对水文、局地生态的调节效应以及屏障效应和岛屿化、截留效应、边缘效应、水温效应等国内外研究的热点。最后,提出了今后大坝生态效应的研究方向:1)生态正效应、生态效应链和生态效应网;2)生态系统过程和状态生态效应;3)不同时空尺度下生态效应及其尺度推绎方法等3个方面的研究。     

压力波对听觉器官的致伤作用——Ⅱ.压力波参数与伤情的关系

压力峰值 P、脉宽 T 和发数 N 是决定压力波致伤作用的基本参量,它们之一的增大一般都导致伤情的加重,但中耳损伤和内耳损伤各有不同的变化规律。当 N 为1、T 在几毫秒之内时,170dB 左右的 P 可以开始对豚鼠的中耳致伤,P 增至185dB 左右时中耳损伤便达到最大。T 和 N 的增大虽也可稍降低中耳的致伤阈或使损伤稍加重,但其主要作用则是加重内耳的伤情。若将听觉器官的损伤从最轻到最重分成5级,则每当 P 增高3—4dB,或 T 或 N 增3—5倍,伤情大体上加重一级。因此若 T 和 N 不变,压力峰值超出安全界线15dB 便可能引起严重的听觉损伤。在数秒到数十分钟的范围内,发射的间隔时间对伤情的影响不大。但当发射的间隔时间缩短到<1s(如100ms)时,对一定发数的总伤情便可稍减轻,此结果可用中耳反射的保护作用来解释。     

Stomach cancer incidence trends in selected Latin America countries: Age,period, and birth-cohort effects

Backgroundto explore the age, period, and birth-cohort effects on stomach cancer incidence trends during 3 decades in selected Latin American countries.Methodsa time-trend study was performed using Cancer Incidence in Five Continents data from high-quality population-based cancer registries(PBCRs) in Latin American countries. Crude and age-standardized incidence rates(ASRIs) were calculated. Time trends in ASRIs were assessed using the average annual percentage change(AAPC). Age-period-cohort effects were estimated by Poisson regression for individuals aged between 20 and 79 years with stomach cancer informed by PBCRs from 1983 to 2012 in Cali(Colombia); from 1982 to 2011 in Costa Rica; and from 1988 to 2012 for Goiania(Brazil) and Quito(Ecuador). The goodness-of-fit model was tested using the deviance of the models.Resultsa decrease in age-standardized incidence rates was observed for both genders in all populations covered by PBCRs, except for young men from Cali(AAPC 3.89 95 %IC: 1.32–7.29). The age effect was statistically significant in all areas, and the curve slope reached peaks in the older age groups. The cohort effect was observed in all PBCRs. Regarding the period effect, an increased ratio rate was observed for both genders in Costa Rica(1997–2001 women RR 1.11 95 %CI: 1.05–1.17; men RR 1.12 95 %CI: 1.08–1.17) and Goiânia(2003–2007 women RR 1.21 95 %CI: 1.08–1.35; men RR 1.09 95 %CI: 1.01–1.20), while Quito(1998–2002 women RR 0.89 95 %CI: 0.81–0.98; men RR 0.86 95 %CI: 0.79–0.93) presented a decrease.Conclusionthe present study showed a decreasing gastric cancer trend for over the past 30 years with gender and geographic variations. Such a decrease seems to be mainly a result of cohort effects, suggesting that the economic market opening process led to changes in the risk factor exposures over successive generations. These geographic and gender variations may reflect cultural/ethnic/gender differences and differences in dietary and smoking rate patterns. However, an increased incidence was observed for young men in Cali, and additional studies are needed to determine the cause of the increasing incidence in this group.     

Anti-inflammatory,anti-oxidant effect and cytotoxicity of ocimum sanctum intra oral gel for combating periodontal diseases

It is of interest to evaluate the anti-inflammatory, anti-oxidant effect and cytotoxicity of Ocimum sanctum (an Indian herb, Thulsi) intra oral gel in combating periodontal diseases. Hence, 2% of O. sanctum gel was prepared with Carbopol940 soaked in purified water containing 0.2% w/v sodium benzoate overnight. Hydroxy proplyl methyl cellulose (HPMC) solution was mixed with propylene glycol using using tissue homogenizer. Anti-oxidant effect was analyzed using DPPH radical assay and anti-inflammatory effect was assessed using the inhibition of albumin denaturation assay. Ocimum sanctum gel with various dilutions from10 micro litres to 50 micro litres showed exponential increase in percentage of inhibition from 60.9 to 72.2 exhibiting antioxidant activity. The anti-inflammatory effect of Ocimum sanctum gel showed comparatively equivalent effect with standard diclofenac gel with values ranging from 76.6 for 50 micro liters of Ocimum sanctum gel and 89.6 for standard gel at 50 micro liters. Ocimum sanctum showed less toxicity towards brine shrimp nauplii. Thus we show that Ocimum sanctum gel showed potent anti-oxidant and anti-inflammatory effect and less toxic to brine shrimp nauplii as a promising agent for the treatment of periodontal diseases.     

栖息地破碎化与鸟类生存

栖息地破碎化给野生动物带来的不良后果是全球生态学家和保护生物学家共同关心的问题.自从提出栖息地破碎化是导致生物多样性丧失的关键因素之一的论点后,近20年来,栖息地破碎化研究一直是生态学和保护生物学最活跃的前沿研究领域之一.栖息地破碎化是一动态过程,可在多尺度上发生并蕴涵着复杂的空间模式变化.栖息地破碎化对鸟类的生态学效应主要体现在面积效应、隔离效应和边缘效应等.这些效应影响着鸟类的分布、基因交流、种群动态、扩散行为、种间关系和生活史特征等,最终影响着鸟类的生存.介绍和总结了栖息地破碎化过程、研究的理论依据及栖息地破碎化对鸟类生存产生的诸多影响.     

Extrinsic effects, estimating opponents' RHP, and the structure of dominance hierarchies

We examined the impact of winner and loser effects on dominance hierarchy formation when individuals are capable of estimating their opponent's resource holding power (RHP). The accuracy of such estimates was a variable in our simulations, and we considered cases in which all individuals err within the same bounds, as well as cases in which some individuals consistently overestimate, while others consistently underestimate their opponent's fighting RHP. In all cases, we found a clearly defined linear hierarchy. In most simulations, the vast majority of interactions were 'attack-retreats', and the remainder of interactions were almost all 'fights'. Error rates had no effect on the linearity of the hierarchy or the basic attack-retreat nature of interactions, and consistent over and underestimation did not affect the ultimate position of an individual in a hierarchy.     

Effects of heavy water on mitochondrial respiration and oxidative phosphorylation

Studies on the influence of heavy water on mitochondrial respiration and oxidative phosphorylation revealed that both isotope and solvent effects, may be responsible for the observed changes. Although the two types of effects could not be totally delineated from each other by the experimental approaches employed, the isotope effect appeared to be primarily responsible for the uncoupling of oxidative phosphorylation, while the inhibition of respiration in the presence of ADP (State 3 respiration) could be a manifestation of the solvent effect.     

Group fusion: the impact of winner, loser, and bystander effects on hierarchy formation in large groups

We present the results of a series of computer simulations thatexamined the impact of winner, loser, and bystander effectson hierarchy formation in fused groups. These effects and theirimplications for hierarchy structure and aggressive interactionswere first examined in small four-member groups. Subsequentto this, the two small groups were fused into a single largergroup. Further interactions took place in this fused group,generating a new hierarchy. Our models demonstrate clearly thatwinner, loser, and bystander effects strongly influence boththe structure and types of interactions that emerge from thefusion of smaller groups. Four conditions produced results inwhich the same general patterns were uncovered in pre- and postfusiongroups: (1) winner effects alone, (2) bystander loser effectsalone, (3) winner and bystander winner effects operating simultaneously,and (4) all four effects in play simultaneously. Outside thisparameter space, hierarchy structure and the nature of aggressiveinteractions differed in pre- and postfusion groups. When onlyloser effects were in play, one of the two clear alphas fromthe prefused groups dropped in rank in the eight-member fusedgroup. When bystander winner effects were in play, it was difficultto rank any of the eight individuals in the fused group, andplayers interacted almost exclusively with those that were notin their original four-member group. When loser and bystanderloser effects operated simultaneously, two top-ranking individualsemerged in the fused groups, but the relative rank of the otherplayers was difficult to assign.     

Quantifying effects of biodiversity on ecosystem functioning across times and places

Biodiversity loss decreases ecosystem functioning at the local scales at which species interact, but it remains unclear how biodiversity loss affects ecosystem functioning at the larger scales of space and time that are most relevant to biodiversity conservation and policy. Theory predicts that additional insurance effects of biodiversity on ecosystem functioning could emerge across time and space if species respond asynchronously to environmental variation and if species become increasingly dominant when and where they are most productive. Even if only a few dominant species maintain ecosystem functioning within a particular time and place, ecosystem functioning may be enhanced by many different species across many times and places (β‐diversity). Here, we develop and apply a new approach to estimate these previously unquantified insurance effects of biodiversity on ecosystem functioning that arise due to species turnover across times and places. In a long‐term (18‐year) grassland plant diversity experiment, we find that total insurance effects are positive in sign and substantial in magnitude, amounting to 19% of the net biodiversity effect, mostly due to temporal insurance effects. Species loss can therefore reduce ecosystem functioning both locally and by eliminating species that would otherwise enhance ecosystem functioning across temporally fluctuating and spatially heterogeneous environments.     

Potential artefacts in morphometric analyses of fish: effects of formalin preservation on 0+ grayling

In 0+ grayling, 2 months of preservation in a 4% formalin solution usually caused decreases in various body lengths and fin areas and increases in various body widths. These effects of formalin were variable between two grayling populations and among three length classes of one population.     

Long-term and transgenerational effects of cryopreservation on rabbit embryos

The short-term effects of cryopreservation and embryo transfer are well documented (reduced embryo viability, changes in pattern expression), but little is known about their long-term effects. We examined the possibility that embryo vitrification and transfer in rabbit could have an impact on the long-term reproductive physiology of the offspring and whether these phenotypes could be transferred to the progeny. Vitrified rabbit embryos were warmed and transferred to recipient females (F0). The offspring of the F0 generation were the F1 generation (cryopreserved animals). Females from F1 generation offspring were bred to F1 males to generate an F2 generation. In addition, two counterpart groups of noncryopreserved animals were bred and housed simultaneously to F1 and F2 generations (CF1 and CF2, respectively). The reproductive traits studied in all studied groups were litter size (LS), number born alive at birth (BA), and postnatal survival at Day 28 (number of weaned/number born alive expressed as percentage). The reproductive traits were analyzed using Bayesian methodology. Features of the estimated marginal posterior distributions of the differences between F1 and their counterparts (F1 − CF1) and between F2 and their counterparts (F2 − CF2) in reproductive characters found that vitrification and transfer procedures cause a consistent increase in LS and BA between F1 and CF1 females (more than 1.4 kits in LS and more than 1.3 BA) and also between F2 and CF2 females (0.96 kits in LS and 0.94 BA). We concluded that embryo cryopreservation and transfer procedures have long-term effects on derived female reproduction (F1 females) and transgenerational effects on female F1 offspring (F2 females).     

新型光敏化剂——竹红菌甲素的抑瘤作用

 利用竹红菌甲素并结合其光敏特性进行了动物体内的抑瘤试验。发现患瘤局部表皮涂布竹红菌甲素软膏或局部皮下注射或腹腔注射甲素花生油溶液、并经光照致敏后能使小鼠S-180实体肉瘤生长减缓,甚至有个别消退。同时利用细胞培养法和~3H标记化合物参入法进行了甲素抑瘤作用的定量分析。发现作用时间固定时(光照40分钟后继续培养3小时),大于12.5ng/ml浓度的甲素能明显抑制~3H-TdR、~3H-UR和~3H-Leu对S-180肉瘤细胞的参入速率;剂量与抑制率呈正相关。据此结果求出甲素对S-180肉瘤细胞的有效抑制浓度(LD(50))为40ng/ml。光照组与无光照组差异有显著性。用Ebrlich腹水癌细胞为研究体系也得到了类似的试验结果。实验结果提示竹红菌甲素具有明显的抑瘤作用,这种作用与其光敏特性有关。     

农田林网地区风速减弱规律的探讨

根据能量平衡原理,利用风洞实验资料和野外观测资料分析了林网地区动量通量(或动力速度)的变化规律,得到了林网地区与旷野的动力速度之比关系式:并据此分析了林网地区的风速减弱规律。     

A meta-analysis of the interactive effects of UV and drought on plants

Interactions between climate change and UV penetration in the biosphere are resulting in the exposure of plants to new combinations of UV radiation and drought. In theory, the impacts of combinations of UV and drought may be additive, synergistic or antagonistic. Lack of understanding of the impacts of combined treatments creates substantial uncertainties that hamper predictions of future ecological change. Here, we compiled information from 52 publications and analysed the relative impacts of UV and/or drought. Both UV and drought have substantial negative effects on biomass accumulation, plant height, photosynthesis, leaf area and stomatal conductance and transpiration, while increasing stress-associated symptoms such as MDA accumulation and reactive-oxygen-species content. Contents of proline, flavonoids, antioxidants and anthocyanins, associated with plant acclimation, are upregulated both under enhanced UV and drought. In plants exposed to both UV and drought, increases in plant defense responses are less-than-additive, and so are the damage and growth retardation. Less-than-additive effects were observed across field, glasshouse and growth-chamber studies, indicating similar physiological response mechanisms. Induction of a degree of cross-resistance seems the most likely interpretation of the observed less-than-additive responses. The data show that in future climates, the impacts of increases in drought exposure may be lessened by naturally high UV regimes.