Seasonal changes in cold tolerance,water relations and accumulation of cations and compatible solutes in Atriplex halimus L.

We determined the cold (freezing) tolerance for field-grown plants of Atriplex halimus L. (Chenopodiaceae) in relation to plant ploidy level, leaf water relations and accumulation of osmolytes. Plants were grown at two sites in Murcia (Spain), having average minimum temperatures in the coldest month of 0.6 and 12.1 °C, respectively. LT₅₀ values derived from laboratory freezing tests, using leaves taken from the plants in early winter and in spring, showed greater tolerance for winter-harvested leaves; the acclimation was more pronounced at the cold-winter site. Cold tolerance was related positively with leaf K and/or Na accumulation. Analysis of compatible organic solutes (soluble sugars, total amino acids and quaternary ammonium compounds) showed that cold tolerance (measured both as LT₅₀ and as winter freezing damage in situ) was related most closely with leaf concentrations of soluble sugars. The leaf percentage dry matter content was related to both in vitro and in vivo tolerance, while tolerance in vitro was correlated also with the osmotic (potential ψ_s) and the relative water content. The two diploid (2n = 2x = 18) populations, from Spain, showed greater cold tolerance than the three tetraploid (2n = 4x = 36) populations, from North Africa and Syria, which may be related to the latter's greater cell size and consequent dilution of osmolytes. In this halophytic species, cold tolerance, like salinity and drought tolerance, seems to depend on osmotic adjustment, driven by vacuolar accumulation of K and Na and cytoplasmic accumulation of compatible solutes.     

Interleukin-1 stimulates prostaglandin biosynthesis by human amnion

The purpose of these studies was to determine if Interleukin-1 (IL-1) alters the rate of prostaglandin biosynthesis by human amnion. Primary monolayer cultures of amnion cells were established from women undergoing elective cesarean section before the onset of labor. Natural purified and recombinant human IL-1 alpha and IL-1 beta were incubated with amnion cells in culture, and prostaglandin E2 (PGE2) biosynthesis was measured by radioimmunoassay in cell-free media. A concentration-dependent increase in PGE2 production by amnion cells occurred in response to natural purified and recombinant IL-1 preparations. No differences in the parameters of the dose-response curves between the two IL-1 gene products could be determined (p greater than 0.05). Indomethacin blocked the effect of IL-1 in prostaglandin biosynthesis by human amnion. Interleukin-1, a fever mediator, could serve as a signal for the initiation of labor in cases of intrauterine or systemic infection.     

Abscisic acid-triggered guard cell l-cysteine desulfhydrase function and in situ hydrogen sulfide production contributes to heme oxygenase-modulated stomatal closure

Recent studies have demonstrated that hydrogen sulfide (H₂S) produced through the activity of l -cysteine desulfhydrase (DES1) is an important gaseous signaling molecule in plants that could participate in abscisic acid (ABA)-induced stomatal closure. However, the coupling of the DES1/H₂S signaling pathways to guard cell movement has not been thoroughly elucidated. The results presented here provide genetic evidence for a physiologically relevant signaling pathway that governs guard cell in situ DES1/H₂S function in stomatal closure. We discovered that ABA-activated DES1 produces H₂S in guard cells. The impaired guard cell ABA phenotype of the des1 mutant can be fully complemented when DES1/H₂S function has been specifically rescued in guard cells and epidermal cells, but not mesophyll cells. This research further characterized DES1/H₂S function in the regulation of LONG HYPOCOTYL1 (HY1, a member of the heme oxygenase family) signaling. ABA-induced DES1 expression and H₂S production are hyper-activated in the hy1 mutant, both of which can be fully abolished by the addition of H₂S scavenger. Impaired guard cell ABA phenotype of des1/hy1 can be restored by H₂S donors. Taken together, this research indicated that guard cell in situ DES1 function is involved in ABA-induced stomatal closure, which also acts as a pivotal hub in regulating HY1 signaling.     

海洋耐高温酸性α-淀粉酶水解玉米淀粉的研究

为开发适用于工业生产的新型酶制剂,以实验室自主构建的基因工程菌所产的新型海洋耐高温酸性α-淀粉酶为液化酶,以玉米淀粉液化后的DE值为指标,研究影响玉米淀粉的液化的因素,确定该酶水解玉米淀粉的最佳工艺条件。新型海洋耐高温酸性α-淀粉酶最佳的工艺条件为温度85℃、时间90 min、粉浆浓度250 g/L、酶用量32 U/g淀粉。     

Regulated nitrate transport in the cyanobacterium Anacystis nidulans.

Intracellular accumulation of nitrate, indicative of the operation of an active nitrate transport system, has been measured in intact cells of the cyanobacterium Anacystis nidulans. The ability of the cells to accumulate nitrate was effectively hindered by either ammonium addition or selective inhibition of CO2 fixation by DL-glyceraldehyde, with the effect of either compound being prevented by previously blocking ammonium assimilation. The results support the contention that nitrate utilization in cyanobacteria is regulated at the level of nitrate transport through the concerted action of ammonium assimilation and CO2 fixation.     

Effect of detection heterogeneity in occupancy‐detection models: an experimental test of time‐to‐first‐detection methods

Imperfect detection can bias estimates of site occupancy in ecological surveys but can be corrected by estimating detection probability. Time‐to‐first‐detection (TTD) occupancy models have been proposed as a cost–effective survey method that allows detection probability to be estimated from single site visits. Nevertheless, few studies have validated the performance of occupancy‐detection models by creating a situation where occupancy is known, and model outputs can be compared with the truth. We tested the performance of TTD occupancy models in the face of detection heterogeneity using an experiment based on standard survey methods to monitor koala Phascolarctos cinereus populations in Australia. Known numbers of koala faecal pellets were placed under trees, and observers, uninformed as to which trees had pellets under them, carried out a TTD survey. We fitted five TTD occupancy models to the survey data, each making different assumptions about detectability, to evaluate how well each estimated the true occupancy status. Relative to the truth, all five models produced strongly biased estimates, overestimating detection probability and underestimating the number of occupied trees. Despite this, goodness‐of‐fit tests indicated that some models fitted the data well, with no evidence of model misfit. Hence, TTD occupancy models that appear to perform well with respect to the available data may be performing poorly. The reason for poor model performance was unaccounted for heterogeneity in detection probability, which is known to bias occupancy‐detection models. This poses a problem because unaccounted for heterogeneity could not be detected using goodness‐of‐fit tests and was only revealed because we knew the experimentally determined outcome. A challenge for occupancy‐detection models is to find ways to identify and mitigate the impacts of unobserved heterogeneity, which could unknowingly bias many models.     

Discovery of 5-(arenethynyl) hetero-monocyclic derivatives as potent inhibitors of BCR-ABL including the T315I gatekeeper mutant

Ponatinib (AP24534) was previously identified as a pan-BCR-ABL inhibitor that potently inhibits the T315I gatekeeper mutant, and has advanced into clinical development for the treatment of refractory or resistant CML. In this study, we explored a novel series of five and six membered monocycles as alternate hinge-binding templates to replace the 6,5-fused imidazopyridazine core of ponatinib. Like ponatinib, these monocycles are tethered to pendant toluanilides via an ethynyl linker. Several compounds in this series displayed excellent in vitro potency against both native BCR-ABL and the T315I mutant. Notably, a subset of inhibitors exhibited desirable PK and were orally active in a mouse model of T315I-driven CML.     

5-脂氧合酶（5-LOX）及代谢产物在异氟醚预处理脑保护作用中的研究进展

缺血性脑血管疾病（Ischemia Cerebral Vascular Disease,ICVD）可造成不同程度的神经功能障碍,以其高发病率、高致残率、高复发率、高死亡率严重威胁着人们的身体健康。而脑组织缺血后再灌注损伤即脑缺血再灌注损伤（ischemia-reperfusion injury）是脑缺血性疾病的最主要的损伤原因之一,因此阐明脑缺血再灌注损伤发生发展的病理生理机制、探寻有效的预防保护措施成为当今研究的重点问题。本文回顾、归纳脑缺血再灌注损伤的相关分子机制及异氟醚预处理对脑缺血再灌注损伤的保护作用,分析5-脂氧合酶及其代谢产物在脑缺血再灌注损伤中的作用及其与其他分子的相互关系,旨在探讨5-脂氧合酶及其代谢产物在异氟醚预处理保护脑缺血再灌注损伤中可能起到的作用。为脑缺血再灌注损伤的防治提供更多的理论依据。     

二阶运动条件下闪现滞后现象的研究

闪现滞后现象(flash—lag effect)是指运动物体旁闪现的物体在知觉中物体落后于运动物体的现象。对这个现象,有一种解释认为视网膜上对运动刺激的外推机制对闪现滞后现象有相当的贡献．用视网膜外推机制不再有效的二阶运动刺激取代前人实验中的一阶运动刺激来研究闪现滞后现象,发现在视网膜推断机制失效的情况下,闪现滞后现象并没有减小,而是和一阶运动刺激条件下的量相当。结果表明,视网膜上的加工机制并不是闪现滞后现象的主要原因,并提示闪现滞后现象的机制可能位于一、二阶运动加工通道的汇合阶段以上。