植物叶片衰老机理的几种假说

关于植物叶片衰老已有很多工作,对于衰老的机理提出了许多假说。本文汇总、介绍了其中几种主要假说。     

藻类批量培养中的比增长率最大值

批量培养谷皮菱形藻、莱茵衣藻、粉核小球藻、斜生栅藻、羊角月牙藻和铜绿微囊藻等六种藻类,在对数生长期,逐日计数而确定比增长率最大值（μｍａｒ）,发现（μｍａｒ）值出现的时间在各种藻类中不同。同时讨论了每种藻类的（μｍａｒ）与营养物质、光强、温度和起始浓度之间的关系。铜绿微囊藻的（μｍａｒ）在一定的总磷（ＴＰ）浓度范围内随ＴＰ浓度呈上升趋势。根据获得增大率最大值的条件,对它们在浮游植物群落中的生态位作     

稀有鮈鲫胚后发育和幼鱼生长的初步研究

本文介绍了室养条件下稀有　鲫胚后发育与幼鱼生长的特点。稀有　鲫的胚后发育过程可分为3个阶段共11个时期,在水温24．7—31．8℃的条件下,初孵仔鱼经25—30d即可完成胚后发育。在胚后发育期间,仔鱼、稚鱼及幼鱼呈线性生长,每日增长0．52mm左右。饲养条件对生长和发育均有很大影响。在相同的饲养条件下,采于四川省汉源县、灌县及彭县的亲鱼,其后代在生长上无显著性差异。     

皱纹盘鲍的个体能量收支

对皱纹盘鲍的呼吸、摄食、生长及能量收支等实验研究表明, 鲍的耗氧率与壳长、体重、温度及昼夜变化有关, 耗氧率与壳长、体重均呈幂函数关系, 一天中16~4时(夜间)耗氧率高于4~16时(白天)且在18~20时达峰值.同温度下鲍日摄食率与体重呈幂指数关系, 日(相对)摄食率随温度升高而增加, 而日相对摄食率、日相对生长率均随壳长、体重增加呈下降趋势.鲍在14~20℃内对海带的总转化效率为53%.鲍软体部、海带及鲍粪便干品的比能值分别为19.2、8.57和7.23kJ·g^-1.14~20℃皱纹盘鲍摄入能量的34.6~48.6%为粪能, 22.0~38.2%的能量用于自身代谢, 5.6~28.2%用于贝体软体部的生长.     

鱼腥藻提取液对水稻生长发育和产量的促进作用

以田间小区试验和大区产量直接对比的方法研究了鱼腥藻提取认对水稻幼苗生长和产量以及产量构成要素的影响,并探讨了方便有效且适宜于大田使用的方法。用藻液处理后水稻幼苗增高,根数、根长增加,分蘖能力增强,秧龄提前,叶面积明显加大。水稻成熟后除株高比对照略有下降外,各项产量构成要素如粒数、粒重、有效分蘖数、植株干重、千粒重、穗长等都优于对照组,但增产幅度随水稻品种和处理方式不同而异。大田使用时以１％鱼腥藻提     

Amphibian metamorphosis as a model for studying the developmental actions of thyroid hormone

The thyroid hormones L-thyroxine and triiodo-Lthyronine have profound effects on postenbryonic development of most vertebrates.Analysis of their action in mammals is vitiated by the exposure of the developing foetus to a number of maternal factors which do not allow one to specifically define the role of thyroid hormone (TH) or that of other hormones and factors that modulate its action.Amphibian metamorphosis is obligatorily dependent on TH which can initiate all the diverse physiological manifestations of this postembryonic developmental process(morphogenesis,cell death,re-structuring,etc.) in free-living embryos and larvas of most anurans.This article will first describe the salient features of metamorphosis and its control by TH and other hormones.Emphasis will be laid on the key role played by TH receptor (TR),in particular the phenomenon of TR gene autoinduction,in initiating the developmental action of TH.Finally,it will be argued that the findings on the control of amphibian metamorphosis enhance our understanding of the regulation of postembryonic development by TH in other vertebrate species.     

火炬松胚性细胞悬浮培养物的生长参数变化

以火炬松（PinustaedaL.）成熟合子胚来源的胚性愈伤组织为材料建立了胚性细胞悬浮系,测定了其培养物的鲜重、干重、细胞体积和胚数及培养液中的pH值、电导率和蔗糖浓度等生长参数在培养过程中的变化动态。结果表明,在培养周期内,培养液中的pH值、电导率和蔗糖浓度的逐步降低与培养物的鲜重、干重、细胞体积和胚胎数的逐步增加保持一致性。在培养至18—21d,pH值、电导率和蔗糖浓度均接近或降到最低点,而胚数及细胞体积的增长都达到最高点。     

Retroviral transfer of antisense sequences results in reduction of c-Abl and induction of apoptosis in hemopoietic cells

The c-abl proto-oncogene is ubiquitously expressed during mammalian development. Activated forms of c-Abl proteins are oncogenic and have been shown to suppress apoptosis. The biological role of normal c-Abl protein is unknown. In this study, we have introduced c-abl antisense sequences into various hemopoietic cells by retroviral gene transfer. Introduction and expression of the antisense sequence effectively reduced the amount of c-Abl protein in a number of transduced hemopoietic cells, that consequently underwent apoptosis. When factor-dependent cell lines were examined, we observed that the addition of sufficient amounts of growth factors could suppress apoptosis in myeloid but not in lymphoid lines. The ability of myeloid cells to be rescued by growth factors correlated with upregulation of mRNA level of IL-3 receptor subunits. Our data suggest that c-Abl provides an anti-apoptotic signal during mammalian cell growth, and that myeloid and lymphoid cells are different in their resistance to apoptosis.     

Contamination of a dredged material disposal site La Rochelle Bay,France .The use of the acetylcholinesterase activity of Mytilus edulis L. as a biomarker of pesticides: the need for a critical approach

A single aspect of the toxic impact of a dredged material disposal site located near a mussel-farming zone was followed for eight months. Acetylcholinesterase activity (AChE) of Mytilus edulis was investigated as a biomarker for possible contamination by neurotoxic compounds (carbamates and/or organophosphorous pesticides). Our observations showed that the enzymatic activities (including AChE) of these harbour mussels were decreased in sites directly and indirectly influenced (according to hydrodynamic conditions) by the dumping of dredged sediments, suggesting possible contamination by pesticides. The strong correlations observed between AChE activity and growth parameters (length and weight) seems to show, however, that the enzyme activity is also indirectly controlled through growth restriction, which may imply limitation of the development of the nervous system in juveniles. The concentration of total proteins, as well as the spawning process also seem to disturb the assessment of AChE activity. These field observations clearly indicate that the use of this enzyme activity as a biomarker should proceed with caution. For example, the seasonal variability of such activity should be taken into account in a biomonitoring programme.