白洋淀菹草对富营养化水体总磷的净化

利用白洋淀区域鲥鯸淀、王家寨和小淀3个淀区的水体、底泥和菹草组成室内静态的模拟生长体系,研究白洋淀菹草在不同水体及底泥环境下的生长状况,以及不同菹草生长体系对水体总磷的净化效果.结果表明:鲥鯸淀菹草生长体系对水体总磷的净化效果最佳,最大去除率为87.9%,单位生物量对水体总磷的最大去除率为2.2%;王家寨和小淀菹草生长体系对水体总磷的最大去除率分别为47.4%和76.9%,单位生物量对水体总磷的最大去除率分别为0.9%和1.4%.3个菹草生长体系的底泥对水体总磷吸附的最大百分比分别为9.1%、7.4%和7.7%.菹草生长体系的TP-t和v-t拟合方程表明,水体中总磷浓度及其去除速率随时间的延长以负指数形式衰减.     

沉水植物菹草对富营养化水体中TN 生态效应及模型研究

通过室内模拟构建水体营养盐和菹草生物量正交试验, 研究菹草从石芽萌发至菹草植株衰亡腐烂整个生命周期中, 对水体中TN 的生态效应, 并以此为依据建立菹草对富营养化水体生态效应模型。研究表明: 在不同生物量菹草作用下, 富营养化水体中TN 含量是先下降后上升的一个周期式过程; 在相同营养水平条件下, 菹草对TN 的吸收量随菹草生物量的增大而依次递增, 而在相同生物量的前提下, 菹草对TN 的修复力存在一个最佳营养水平范围, 即13.95-20.56 mg·L–1 之间; 菹草对富营养化水体生态效应模型分两部分: 菹草对富营养化水体中TN 与时间关系模型以及菹草生态修复水体TN 限度理论模型, 通过这两个模型的构建可以为生产实践中菹草在生态修复富营养化水体的投放量和菹草的最佳收割时间提供有力依据, 为工程实践提供有效保障。     

衰亡期黑藻与生长期菹草交替生长对水体磷迁移的影响

为利用冷暖种交替控制水体磷污染、抑制水体富营养化,揭示湖泊演化规律和机理。研究设置单季植物组(黑藻组、菹草组)和交替生长组(黑藻组+菹草组)进行实验。交替生长组在黑藻衰亡期种植菹草,监测各组上覆水和底泥中各形态磷含量的变化,计算黑藻衰亡释放磷及菹草生长吸收磷的总量,同时测定环境因子指标。分析沉水植物交替生长(黑藻+菹草)过程对衰亡期沉水植物(黑藻组)释放磷所带来的二次污染的消减作用,并分析环境因子变化与磷含量之间的关系。实验结果表明:黑藻+菹草组显著(P<0.05)降低了上覆水中总磷(TP)、溶解性总磷(DTP)和溶解性活性磷(SRP)的浓度;显著(P<0.05)降低了间隙水中DTP和SRP的浓度。底泥TP含量黑藻组呈上升趋势,黑藻+菹草和菹草组呈下降趋势。在采用菹草生物量期望2倍于衰亡植物黑藻生物量的模拟实验条件下,每实验组沉水植物黑藻衰亡分解所释放的磷为1.51 g,沉水植物菹草生长所富集吸收的磷为1.83 g。因此,菹草具备消减黑藻所释放磷的能力,可作为冷暖种交替控制水体富营养化的备选物种。实验组磷的迁移方向分别为:黑藻组磷迁移最终方向为底泥,黑藻+菹草组和菹草组磷的迁移方向为植物。黑藻+菹草组通过提高环境中DO和ORP,使得水相中磷向沉积物相中迁移,从而使得水相中各形态磷浓度保持在相对较低的水平。     

黄河三角洲菹草生长模型及其对水质的影响

通过连续对菹草生长过程的观测 ,用指数方程拟合了菹草从 10月中旬至第 2年 5月底的整个生长过程 (p<0 .0 0 2 ) ,设K=2 .5 kg/ m2时 ,用 L ogistic方程拟合了从 3月到 5月底的生长过程 (p<0 .0 0 0 )。通过 7月底至 8月初、10月、翌年 3月和 5月份对一个菹草型水库和无或有不同规模水草的 5座水库水生生物的周年调查发现 :(1)菹草型水库 TP最高峰的月份比其它水库的推迟 ,其它水库 10月份 TP最高 ,而菹草型水库 3月份最高 ;(2 )菹草型水库浮游植物最高峰的月份比无水草水库的推迟 ,无水草水库出现在夏季 (7～ 8月份 ) ,草型水库的出现在秋季 (10月份 ) ;(3)菹草型水库 3月份浮游植物生物量明显高于其它水库的 ,其硅藻占据更高的优势度 ;(4 )菹草型水库和其它水库之间的总磷和浮游植物数量的年平均值无明显差别 ;(5 )不同水库藻类数量年平均值与 TP年平均值相关极显著 (p<0 .0 0 5 ) ,而 TP又与氯化物 (Cl)相关极显著 (p<0 .0 0 5 ) ;(6 )水草的存在使p H略有提高 ,并使其在不同时间的波动幅度减小     

水深梯度对菹草生长的影响

用盆栽试验方法,将菹草石芽种植在水下30、60、90、120、150、180 cm的花盆内,研究了水深梯度对菹草生长的影响。结果表明：菹草株高与水深显著相关（P<0.01）,菹草生长的适宜水深范围为90～150 cm;5月7日前后,除水深180 cm组外,其他实验组虽然株高有所增加,但叶片数量反而减少,植株开始衰老腐烂;水深差异对菹草叶片光合色素含量影响不明显;水深30、60 cm组菹草的F_v/F_m、ETR值低于深水处其他处理组,表明在菹草生长的中后期,水面光照对水深浅于60 cm的菹草叶片光合电子传递效率有一定的阻碍作用;从快速光响应曲线可以看出,在菹草生长的中后期,水深<60 cm、>150 cm对菹草生长不利。     

鄱阳湖湿地景观恢复的物种选择及其对环境因子的响应

湿地是重要的生态系统,对人类和野生生物都具有极其重要的价值。由于自然因素的变化和人类活动的干扰,湿地退化严重。近年来,湿地恢复已成为世界环境问题改善的重要工具之一。选择适用的湿地植物是退化湿地恢复的关键途径。本文以鄱阳湖湿地为研究对象,通过专家赋值、野外调查、定位观测等方法,筛选了苦草、野菱、芦苇、苔草等25种鄱阳湖常见植物作为湿地景观恢复的优先物种。对苦草、黑藻、菹草、菖蒲、芦苇等5种植物对环境因子的响应进行观测。结果表明,苦草在清水环境130-140cm处的生长最好;黑藻在清水环境中100-110cm处的生长最好;菹草在不同水深(50-160cm)下都能够生长,菹草高度随水深增加而增加;菖蒲具有一定的耐淹能力(< 80cm),但完全淹水(水深100-120cm)明显影响到菖蒲根状茎萌发、幼苗生长和生物量的积累;芦苇根状茎萌发对水深要求严格,土壤要湿润且透气性良好才是芦苇萌发的最好条件,芦苇根状茎萌发前淹水超过20 cm其萌发将会受到明显抑制,淹水超过30 cm则无法萌发。通过对沉水植物的透明度研究表明,植物对水质的透明度都有一定的要求,透明度较好更利于湿地植物的生长发育。     

光和基质对菹草石芽萌发、幼苗生长及叶片光合效率的影响

通过室内模拟试验,研究了基质和光照对菹草石芽萌发、幼苗生长以及不同光照对菹草生长后期叶片光合效率的影响.结果表明,在光照和缺乏基质的条件下,菹草石芽的萌发率和出苗率提高.基质的存在促进了根的生长,而光对根的生长并未起到促进作用.在无光条件下, 菹草幼苗节间长度明显大于有光处理.在暗处理中, 菹草叶片的质膜透性显著增加.在有光照条件下,有无基质对菹草幼苗叶片叶绿素a(Chla)、叶绿素b(Chlb)以及Chla/Chlb比值的影响为Chla、Chlb的含量增高,Chla/Chlb比值在3.5上下波动;Chla/Chlb最大值和最小值在有基质时分别为4.4和2.8,无基质时为4.2和2.7.但对幼苗处理40 d时,暗处理的叶片质膜透性与有光有基质、有光无基质之间差异极显著(P＜0.01).不同光照处理(自然光、50%自然光、20%自然光和10%自然光)的光合特性差异比较结果表明,在菹草生长后期,在自然光下菹草叶片的F_v/F_m和F_v/F_o的比值与其它3个遮光处理相比存在显著差异(P＜0.05),而在3个遮光处理之间差异不显著.进一步比较F_v/F_m、F_v/F_o、ETR、qP、qN和ΦPSⅡ等荧光参数值的结果显示,在生长的后期,一定程度的弱光会起到促进菹草的光合效率、延缓菹草衰老的作用.     

光强对菹草生长及抗氧化酶活性的影响

试验以菹草(Potamogeton crispus)为试验材料, 在7种不同光强(自然光的100%、60%、40%、20%、10%、5%和1%)条件下, 测定并分析菹草的形态指标(株高、叶片数)和生理指标(叶绿素、根系活力、抗氧化酶活性及丙二醛)对光强条件的响应, 为富营养化水体植物群落的构建提供理论依据。结果表明: (1)随着光照强度的增大, 菹草的株高、叶片数、生物量增长率显著上升, 而光强过高(CK组)和过低(1%组)菹草生长受到抑制; (2)菹草叶绿素含量随光照强度的增大, 呈先上升后下降趋势。1%组和CK组Chl. a、Chl. b、Chl. a+b和Car含量低, 其余各组含量较高; (3)随着试验时间的延长, 菹草根系活力呈先上升后下降趋势, 20%组、40%组和60%组的根系活力较大; (4)菹草SOD、POD和CAT活性整体表现为先升后降趋势, 试验后期1%和CK组SOD含量较高, POD、CAT含量较低。菹草叶片MDA含量在试验过程中不断上升, 抑制菹草的正常生长。自然光照的20%—60%, 菹草生长状况较好; 持续的弱光胁迫将导致植物活性氧代谢失调, 细胞受到伤害, 最终导致植物死亡。     

富营养水体中总氮与总磷比对苦草生长的影响

在室外受控实验条件下,研究了富营养水体中不同氮磷比(TN/TP)(12.5∶1、25∶1、50∶1)对苦草(Vallisneria spiralis)生长的影响.结果表明:当TN/TP为25∶1时,苦草的生长状态最好,苦草生物量的增长率最大,分别高于TN/TP为12.5∶1和50∶1时的54%和31%;当TN/TP为25∶1时,附着生物尤其是附着藻类的生长状态最差,对苦草生长的不利影响最小;可见,富营养水体中适宜于苦草生长的TN/TP为25∶1;TN/TP为25∶1这一比例的应用具有相对性,当水体营养浓度低于限制水平时,该比例适用,如果水体中营养盐浓度超过限制水平时,该比例则不适用.     

水体无机碳条件对常见沉水植物生长和生理的影响

为了解水华引起的水体无机碳变化对沉水植物生长的影响,对8种沉水植物:金鱼藻、穗花狐尾藻、篦齿眼子菜、光叶眼子菜、微齿眼子菜、伊乐藻、菹草和黑藻在不同无机碳浓度下的生物量、株高、叶绿素以及光合和呼吸速率进行了比较研究.结果表明8种沉水植物均能利用HCO3-作为光合无机碳源,在1.5 mmoL/L外源HCO3-浓度下能促进金鱼藻、菹草和伊乐藻的生长,提高其光合速率;在2.5 mmol/L外源HCO3-浓度下能促进狐尾藻、光叶眼子菜、黑藻、微齿眼子菜和蓖齿眼子菜的生长,提高其光合速率.在CO32-为优势碳源时,8种沉水植物表现出不同的适应性,发现微齿眼子菜、篦齿眼子菜和黑藻在整个实验范围内生长未受抑制,且在不同浓度下表现生长和光合速率的促进,说明这三种沉水植物对[HCO3-]/[CO32-]比值和pH具有较广适应范围.而当CO32-成为优势碳源时,金鱼藻和伊乐藻的生长受到抑制,狐尾藻、菹草和光叶眼子菜均死亡,表明[HCO3-]/[CO32-]比值和pH是这5种沉水植物生长的重要限制因子.     

Sex-specific somatic–otolith growth relationship in two Gadidae

Otolith and somatic mass of two Gadidae ( Merlangius merlangus and Trisopterus minutus ) were compared in order to analyse the sex-specific relationship between otolith and somatic growth at age. In the present study, otolith mass appeared a reliable indicator of age in both species. Otolith growth reflected somatic growth, but the relationship between these characters varied and differed between species and sexes.     

Control of animal cell proliferation

Present understanding of the control of animal cell proliferation is summarized briefly. Major gaps in present knowledge are listed. Models of growth control are discussed.     

生长激素分泌促进剂及构效关系研究进展

生长激素分泌促进剂是一类作用于垂体和下丘脑的具有专一性促生长激素释放作用的寡肽及其类似物.由于其分子质量小、活性高、可口服、作用专一而有可能成为新的生长激素治疗药物.目前已经发展了很多具有此类活性的多种结构的化合物,如肽、环肽、肽醇及非肽类似物等.尽管这类化合物的作用机制尚未完全明确,但已有证据表明存在新的调节生长激素分泌的途径和新的调节因子.     

Light-, nitrogen-, and phosphorus-limited growth of Phaeodactylum tricornutum Bohlin strain TFX-1: Chemical composition,carbon partitioning,and the diel periodicity of physiological processes

Phaeodactylum tricomutum Bohlin (strain TFX-1) was grown under light-, nitrogen-, and phosphorus-limited conditions in continuous or semicontinuous cultures under a 12L-12D light regime. The C, N, and P contents were determined at each steady state, as was the partitioning of cellular organic carbon into protein, lipids, polysaccharides, and metabolic intermediates. All determinations were made at the beginning and again at the end of the light period. The rates of nutrient assimilation and of synthesis of biochemical constituents during the light and dark periods were calculated from the above data, and the periodicities of these processes characterized. The elemental composition of the cells was different under each limitation. In particular, phosphorus limitation severely restricted the ability of the cell to store nitrogen in non-protein forms. Biochemical composition and the diel periodicity of cellular processes also differed between limitations. Nutrient uptake was most strongly periodic under light limitation. Protein synthesis showed increased periodicity under nitrogen limitation, relative to the other limitations, while the periodicity of lipid synthesis was reduced under phosphate limitation. Polysaccharide was synthesized at high rates during the light period and consumed in the dark under all limitations.     

The strain energy function in axial plant growth

A model for axial plant growth is formulated based on conservation of energy. The model derivation assumes that a strain energy function exists to describe the dissipation of potential energy associated with water uptake, mechanical deformation, and biosynthesis during growth. The derivation does not, however, make any further assumption on the mathematical form of this constitutive relation. The model is employed to investigate possible forms of the strain energy function as applied to steady root growth. Solutions of the nonlinear partial differential equations governing growth are given for cases when the third derivative of the strain energy function is >, <, or =0. These three cases encompass a multitude of mathematical forms of the strain energy function. The resulting solutions are compared with the realization of steady axial root growth. The results of this analysis indicate that a quadratic form of the strain energy function best described steady growth. This conclusion is consistent with previous assumptions on the form of constitutive relations for growth, and allows further interpretation on the water relations, mechanical, and biosynthetic energies associated with plant growth.Research support provided by state and federal funds appropriated to the OSU/OARDC. Journal article no. 12–88     

The growth ring concept: seeking a broader and unambiguous approach covering tropical species

The concept of growth rings is little discussed in the literature and their treatment remains somewhat confusing in terms of the diversity of structures described. This situation has a major impact on the study of growth rings in tropical species, in which variations and complexity are greater and accuracy of identification less good. The rigid conceptual delimitations used by dendrochronologists and wood anatomists of temperate regions cannot be applied to the study of growth rings in most tropical species, which has led to neglect of this subject. With the objective of discussing the concept of growth rings, the present study consists of a survey of anatomical, periodicity, causal and evolutionary aspects of the treatment of these structures as evidenced in previous studies, and the evaluation of their application and limitations to the development of this concept. Anatomical aspects arise through radial integrity, or the presence of early and late wood; the degree of distinction of the rings, which may vary from well to poorly defined; and tangential continuity, meaning that rings may form a complete circle in the transverse section of the trunk, or instead be tangentially discontinuous, lens‐shaped or in wedges. In addition there are a diversity of anatomical markers which enable us to recognize growth rings. Regarding periodicity, the rings may be annual, infra‐annual or supra‐annual. Causal aspects include genetic, endogenous and environmental components. Evolutionary aspects continue to be insufficiently investigated, and although most comparative studies treat growth rings recognized by different markers as though they were a single character, it remains questionable whether they can be regarded as homologous or the result of homoplasy. We conclude that the elaboration of a robust but broad definition which can include all the variation observed in growth rings of tropical species is a complex task, which is only possible by overcoming the restrictions adopted by dendrochronologists and wood anatomists of temperate regions for whom growth rings are essentially annual, strongly demarcated, tangentially continuous and restricted to the most pronounced markers.     

Validation and implications of a growth model for brown trout, Salmo trutta, using long-term data from a small stream in north-west England

Summary 1. The objectives were: (i) to check the validity of a new growth model; (ii) to examine the relationship between population density and both mean mass and mean growth rate and (iii) to discover if compensatory growth occurred. First (0+) and second (1+) year‐old juvenile sea‐trout were sampled by electrofishing at the beginning and end of the summer from 1967 to 2000. Additional samples were taken in some years in winter and in the critical period for survival when the fry first emerge from the gravel. The trout left the stream as pre‐smolts in May, soon after their second birthday. 2. A growth model ( Elliott, Hurley & Fryer, 1995 ) estimated the mean mass of the trout over the 2 years spent in fresh water. The date and mean mass at the start of the growth period were defined as the median date for fry emerging from the gravel and their mean mass at emergence, both being estimated from individual‐based models ( Elliott & Hurley, 1998a, b ). 3. The variation in mean mass among year‐classes was small for newly‐emerged fry (CV = 6.2%), maximum at the start of the first summer of the life cycle (CV = 38.1%), and then decreased gradually for successive life‐stages to a low value for pre‐smolts (CV = 10.8%). Mean mass was not related to population density and, therefore, mean growth rate was density‐independent. Growth in the first, but not the second, winter of the life cycle was lower than model prediction, but when it was assumed in the model that there was no first‐winter growth, there was good agreement in most year‐classes between model estimated values and observed mean mass. Exceptions were that mean masses and growth rates for 0+ trout after four summer droughts were lower than expected, but compensatory growth followed, so that observed and expected masses were similar for 1+ trout. 4. Pre‐smolt mean mass on 30 April measured total growth achieved in the freshwater phase of the life cycle. This was significantly related to mean mass at the end of the first and second summers of the life cycle, but not to the emergence date and mean mass of emerging fry. 5. These juvenile sea‐trout were growing at their maximum potential in most year‐classes but when this was not achieved, compensatory growth soon restored their mass to values expected from the model. This ensured a low variation in the mean mass of pre‐smolts just before they migrated to the sea. However, the latter mass was higher in more recent year‐classes (1987–98) than in previous ones (1967–86), demonstrating the effect of slightly higher stream temperature. This study has shown the importance of developing realistic growth models in order to detect departure from maximum potential growth, and the more subtle effects of temperature change, possibly due to the effects of climate change.     

Growth of the Brown Alga <Emphasis Type="Italic">Laminaria japonica</Emphasis> in a Laboratory Environment

The growth of an individual thallus of the brown alga Laminaria japonica was studied in a laboratory environment. It was found that daily accretion of the Laminaria thallus can remain constant for a long time. The blade grew in length at a distance from 0 to 15–25 cm from the stipe-blade border, which makes up 60% of the blade length. In width, the blade grew both in the central and in the lateral parts of the blade, 0 to 7–10 cm from the stipe-blade border, which makes up 30% of the frond length. The transposition of a perforation hole mark from the stipe-blade border toward the blade tip evidenced the formation of new tissue in the growth zone even when the thallus diminished in size due to destruction of the blade tip. Based on the results of this observation, it was concluded that both restraint of accumulation and even reduction of the algal thallus in biomass and size cannot be taken as an indication of algal growth cessation.Original Russian Text Copyright ¢ 2005 by Biologiya Morya, Skriptsova, Leletkin.     

Production of a biologically active novel goldfish growth hormone in Escherichia coli

Goldfish pituitary contains two types of growth hormones. One with five cysteine residues (type-I) similar to other Cyprinid GHs, and the other with four Cys residues (type-II) similar to those of other fish and tertapod species. Recombinant goldfish type II GH (gfGH-II) was produced in Escherichia coli using the pRSETB expression vector. The gfGH-II was produced fused to a leader sequence, which sequestered into inclusion bodies after expression. The inclusion bodies were solubilized using sodium hydroxide and the fusion protein purified by chelating affinity chromatography. Subsequently, gfGH-II was cleaved and analyzed by Western blotting, using a specific antiserum. For comparison we also produced recombinant common carp GH (cGH) which has 95% similarity to gfGH-II, and tested their growth promoting activity in goldfish. Both forms of GH significantly increased the growth rate of goldfish (P<0.05), although cGH was found to have a somewhat higher potency than gfGH-II.