光强和硝态氮水平对铜藻(Sargassum horneri)生长和光合生理特性的影响

以金潮种铜藻(Sargassum horneri)为对象,探讨了不同硝态氮水平下光照强度对其生长和光合生理特性的影响,以期为金潮暴发机制的研究提供一定的参考。实验设置了高(100μmol·L-1)、低(自然海水,50μmol·L-1) 2个硝态氮浓度和高(150μmol photons·m-2·s-1)、中(60μmol photons·m-2·s-1)、低(10μmol photons·m-2·s-1)三个光照水平,检测了藻体在不同硝态氮浓度和光照条件下适应培养7 d后生长、色素含量、可溶性糖含量、可溶性蛋白含量、氮吸收速率及最大光合放氧速率(Pmax)等生理指标的变化。结果表明:氮浓度相同时,铜藻的生长速率、可溶性糖含量、可溶性蛋白含量、氮吸收速率、Pmax均随光照强度的增加而增加,而色素含量随着光照强度的增加而降低;低氮条件下,除类胡萝卜素外,以上指标在高光处理下均显著高于低光处理(P0.05);高氮条件下,除可溶性糖外,以上指标在高光条件下也均显著高于低光处理(P0.05);同一光照强度下,色素及可溶性蛋白含量、氮吸收速率及Pmax随氮浓度的增加而增加;可溶性糖含量随着硝态氮浓度的增加而减少;且在3个光照条件下,高氮处理下藻体的Pmax均显著高于低氮处理。总之,不同光照和氮浓度处理7 d后,高光、高氮适应后的藻体表现出较高的生长和光合作用潜能。铜藻断裂后漂浮于海面极易获得较高光强条件,而富营养海水中的高氮条件会刺激铜藻的光合潜能而使其加速生长,进而加剧铜藻金潮的暴发。     

CO2对转基因聚球藻7942生长、表达等的影响

研究了不同浓度CO2 对转基因聚球藻 794 2生长、胸腺素α1表达和光合作用的影响 ,结果表明 :不同浓度的CO2 对藻细胞指数生长期的比生长速率没有明显的影响 ,通入空气与 5 %CO2 空气对藻细胞线性生长速率和最终藻细胞浓度影响也不显著 ;高浓度CO2 会减少NO-3 的吸收 ,提高硝酸还原酶的活性 ,这表明NO-3 的吸收与还原是不偶联的。低浓度CO2 对藻细胞的生化组成和胸腺素α1表达没有影响。而高浓度的CO2 明显降低可溶性蛋白及光合色素叶绿素a、类胡萝卜素和藻蓝蛋白的含量 ,胸腺素α1含量也显著降低。不同CO2 浓度培养的藻细胞P I曲线表明 ,不同浓度的CO2 对藻细胞的光合作用效率没有明显的影响 ,但生长在高浓度CO2 中藻细胞的最大光合速率明显增加。     

大气CO2升高和紫外辐射相互作用对羊栖菜生理特性的影响

为了研究经济海藻羊栖菜对大气CO2浓度增加与紫外辐射(UVR)相互作用的响应,设置两个CO2浓度(380μL/L和800μL/L)以及两种辐射处理,即PAR处理(滤除UV-A、UV-B,藻体仅接受可见光,400—700nm)和PAB处理(全波长辐射280—700nm)培养海藻,探讨了羊栖菜生长、光合作用、呼吸作用、光合色素含量、可溶性糖和蛋白以及硝酸还原酶活性的变化情况。结果表明高浓度CO2显著提高羊栖菜藻体的相对生长速率,并且紫外辐射的负面效应在高CO2处理下表现不显著。高CO2降低了藻体的光合作用速率,而UVR的负面效应和生长体现为一致性,但是羊栖菜的呼吸作用没有受到环境变化的明显影响。羊栖菜的光合色素叶绿素a和类胡萝卜素在高浓度CO2处理下明显降低,而UVR没有明显影响。环境因子对羊栖菜的可溶性糖没有影响,但是在高CO2和全波长辐射处理下,藻体可溶性蛋白的含量显著增加。同时高CO2明显提高了硝酸还原酶的活性,并且仅在高浓度CO2处理下藻体中UVR对其活性有抑制作用。CO2和UVR对羊栖菜的大多数生理特性存在明显的交互作用,在未来CO2浓度进一步增加的情况下,UVR的负面效应将会得到一定程度的缓解,这样有利于羊栖菜在养殖海区获得更高的产量。     

气候变化对海藻龙须菜生长与光合作用耐热特性的影响

为探讨大气CO2升高和温室效应对龙须菜生长及生理生化特性的影响,在4种条件下培养龙须菜:1)对照组(390μL/L CO2+20℃),2)CO2升高组(700μL/L CO2+20℃),3)温度升高组(390μL/L CO2+24℃),4)温室效应组(700μL/L CO2+24℃),测定藻体生长和生化组分以及高温胁迫下的最大光化学量子产量(Fv/Fm)和光能利用效率(α)、光合速率(Pn)和呼吸速率(Rd)。结果表明,CO2升高、温度升高以及温室效应均促进龙须菜的生长,温室效应下的促进作用更明显。温室效应使龙须菜具较高的Pn和Rd以及较低的可溶性蛋白(SP)和可溶性碳水化合物(SC)含量。高浓度CO2对叶绿素(Chl a)和类胡萝卜素(Car)含量没有显著影响,而高温使其上升;藻红蛋白(PE)和藻蓝蛋白(PC)含量不受CO2浓度和温度的影响。龙须菜Fv/Fm、α、Pn和Rd值,在32℃处理3 h后略有上升,在36℃处理3 h后下降,而在40℃处理20 min后降到极低水平。正常温度(20℃)生长的龙须菜最高耐受温度在32—36℃之间,而较高温(24℃)生长的龙须菜在36—40℃之间;生长温度对光合作用和呼吸作用耐热性能的影响比CO2浓度的影响更大;而温室效应生长条件下的龙须菜光合作用表现出更突出的耐热性能。     

大气CO_2增加对不同生长光强下龙须菜光合生理特性的影响

为了探讨未来大气CO2升高对不同生长光强下大型海藻的影响,选取经济红藻龙须菜为实验材料,研究了其生长速率、光合作用、呼吸作用、叶绿素荧光参数以及光合色素对CO2和光强的响应。实验设置两个CO2浓度,正常空气水平CO2浓度(390μL/L)和高CO2浓度(1000μL/L);两个光强梯度,高光(300μmol m-2s-1)和低光(100μmol m-2s-1)。结果表明,CO2和光强对龙须菜的生长和光合作用有明显的交互作用。大气CO2升高并没有显著影响龙须菜的生长速率,但在不同CO2处理下,龙须菜对光强的响应不同。在空气水平下,光强的变化对其生长速率影响不显著。而在高CO2作用下,高光处理下的藻体有更高的生长速率。CO2显著促进高光生长下龙须菜的呼吸作用速率,但是在低光下作用不明显。而对于光合作用速率来说,低光培养下的藻体CO2表现为负面效应,但对高光下生长的藻体作用不明显。CO2增加没有改变龙须菜生长状态下的电子传递速率,但在高光下,CO2表现为一定的抑制作用。CO2显著降低了龙须菜天线色素藻红蛋白和叶绿素a的含量。这些CO2与光强的结合效应表明,大气CO2的升高对龙须菜光合生理特性的影响随着光强的变化而呈现不同的效应,在未来评估CO2的增加对大型海藻的影响时,要充分考虑其他环境因子的耦合效应。     

大气CO_2浓度升高对不同氮生长条件下的两种大型海藻光合作用的影响

以龙须菜和蛎菜两种大型海藻为试验材料,在室外自然条件下培养,设置常规CO2浓度(390μL·L-1)和高CO2浓度(800μL·L-1)空气两种通气条件、以及10和150μmol·L-1两种氮营养盐供应水平,以探讨大气CO2浓度升高对不同氮营养盐生长条件下海藻生长与光合特性的影响。结果表明:不管是高氮还是低氮的培养条件,大气CO2浓度升高都能促进这两种海藻的生长;在龙须菜中,这种生长促进作用在低氮培养条件下更高,而在蛎菜中这种生长促进作用在高氮培养条件下较高;短期海水中高CO2浓度能促进蛎菜和龙须菜的光合作用;长期高CO2浓度生长环境依然能维持龙须菜高的光合作用,但抑制蛎菜的光合作用。另外,不管培养液中CO2供应条件如何,氮加富均促进了龙须菜和蛎菜这两种海藻的光全和呼吸作用。     

两种抗生素对龙须菜的光合生理效应

探讨了不同浓度的两种抗生素(氯霉素和青霉素G钠)对龙须菜(Gracilaria lemaneiformis)生长、光合作用、呼吸作用、色素含量以及可溶性蛋白含量等生理特性的影响。结果表明:龙须菜的生长受到两种抗生素的影响,但是氯霉素的影响要比青霉素G钠的影响大的多。在氯霉素处理的过程中,光合作用、有效光化学效率(Yield)、藻红藻蓝蛋白以及可溶性蛋白含量都随着氯霉素浓度的升高而显著下降,但是呼吸作用速率由于氯霉素的处理而升高;此外光合色素含量不受氯霉素的影响。在青霉素G钠的处理中,光合作用、有效光化学效率随着青霉素G钠的升高而下降,龙须菜叶绿素a与类胡萝卜素含量随着青霉素G钠浓度的升高而具有升高的趋势,但藻红蛋白、藻蓝蛋白以及可溶性蛋白在各处理组之间均没有表现出一定趋势。这些结果说明,氯霉素对生长的影响主要是光合作用速率的下降,以及有关蛋白合成下降引起,而青霉素G钠对生长的影响可能原因是呼吸作用速率的增加引起。由于龙须菜对氯霉素的敏感性比对青霉素G钠的敏感性更强,氯霉素在基因工程的育种中可能更适合作为选择压力。     

硝态氮对海水胁迫下长春花幼苗光合特性及离子含量的影响

采用砂培试验研究了硝态氮对海水处理下长春花幼苗光合特性和离子分布的影响.结果表明：（1）高浓度海水显著抑制长春花幼苗的生长,提高硝态氮浓度能显著缓解海水胁迫对长春花幼苗生长发育的抑制作用,促进地上、地下部生物量积累.（2）随着海水浓度的增加,长春花幼苗叶片净光合速率、蒸腾速率、气孔导度和水分利用效率较对照均显著降低,细胞间隙CO2浓度显著增加;增加硝态氮浓度可显著提高长春花幼苗的净光合速率、蒸腾速率、气孔导度和水分利用效率,显著降低细胞间隙CO2浓度.（3）随着海水浓度的增加,长春花幼苗体内K＋含量较对照显著降低,而Na^＋、Cl^-含量显著增加,提高硝态氮浓度有利于长春花幼苗对K＋的吸收和向上运输,维持地上部较高的K^＋/Na^＋.研究发现,增加硝态氮能维持高浓度海水胁迫下长春花幼苗体内养分平衡,缓解盐胁迫对其光合生理和生长造成的伤害.     

海洋酸化与磷浓度变化对龙须菜光合作用和ATPase活性的影响

以大型海藻龙须菜(Gracilaria lemanensis)为实验材料, 设置不同CO2浓度(400 μL·L–1和1000 μL·L–1)和磷浓度(0.5和30 μmol·L-1)实验, 探讨大气CO2浓度升高对不同磷浓度培养下龙须菜生长、光合作用及ATPase活性的影响。结果显示大气CO2下, 磷加富导致龙须菜的相对生长速率和最大光合速率增加, 暗呼吸速率降低; 但高CO2浓度下, 磷浓度变化对三者的影响不明显。不论是在大气CO2浓度还是高浓度CO2下, 磷加富对叶绿素a、类胡萝卜素含量和实际光化学效率均没有明显影响, 但导致ATPase活性均明显增加。以上结果表明在高浓度CO2诱导海洋酸化环境中, 磷加富可以通过调节光合速率、暗呼吸速率和ATPase活性, 改变能量的利用效率调控其生长。     

CO2加富对两种海洋微绿藻的生长、光合作用和抗氧化酶活性的影响

研究了 CO2 加富对两种海洋微绿藻小球藻和亚心形扁藻的生长、光合作用和抗氧化酶活性的影响。实验结果表明 ,CO2加富 (含 5 0 0 0 μl/ L CO2 的空气 )促进小球藻和亚心形扁藻的生长。但两种藻对 CO2 加富的敏感性不同。CO2 加富对小球藻生物量影响的敏感性小于亚心形扁藻。CO2 加富使两种藻的干重和光合速率显著增加 ;可溶性蛋白含量显著下降 ;但两种藻的 Chla含量和 Car含量与对照相比变化不明显。高浓度 CO2 生长的小球藻和亚心形扁藻的 MDA含量比对照低 ,表明 CO2 升高可以减轻微藻的膜脂过氧化损伤 ,有利于膜脂稳定性的保持 ;在正常浓度 CO2 (36 0μl/ L )条件下 ,抗氧化酶 SOD、POD、CAT、GR的活性因藻种不同而存在很大差异 ,高浓度 CO2 (5 0 0 0μl/ L )培养条件使得这些抗氧化酶中的 SOD、CAT、GR的活性显著降低 ,而POD活性变化则不明显。 CO2 浓度升高可能导致抗氧化酶活性需求的减少 ,从而对藻的氧化损伤具有一定的保护能力。另外 ,光合速率、Chla含量和 Car含量以及抗氧化酶活性因藻种不同而存在很大的差异     

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

Molecular characterisation of species and genotypes of Cryptosporidium and Giardia and assessment of zoonotic transmission

The molecular characterisation of species and genotypes of Cryptosporidium and Giardia is essential for accurately identifying organisms and assessing zoonotic transmission. Results of recent molecular epidemiological studies strongly suggest that zoonotic transmission plays an important role in cryptosporidiosis epidemiology. In such cases the most prevalent zoonotic species is Cryptosporidium parvum. Genotyping and subtyping data suggest that zoonotic transmission is not as prevalent in the epidemiology of giardiasis. Molecular characterisation of Cryptosporidium and Giardia is a relatively recent application that is evolving as new genes are found that increase the accuracy of identification while discovering a greater diversity of species and yet unnamed taxa within these two important genera. As molecular data accumulate, our understanding of the role of zoonotic transmission in epidemiology and clinical manifestations is becoming clearer.     

Comparison of BMI and percentage of body fat of Indian and German children and adolescents

Today, serious health problems as overweight and obesity are not just constricted to the developed world, but also increase in the developing countries (Prentice 2006, Ramachandram et al. 2002). Focusing on this issue, BMI and percentage of body fat were compared in 2094 schoolchildren from two cross-sectional studies from India and Germany investigated in 2008 and 2009. The German children are in all age groups significantly taller, whereas the Indian children show higher values in BMI (e.g. 12 years: Indian: around 22 kg/m2; German: around 19 kg/m2) and in the percentage of body fat (e.g. 12 years: Indian: around 27%; German: around 18-20%) in most of the investigated age groups. The Indian children have significantly higher BMI between 10 and 13 (boys) respectively 14 years (girls). Indian children showed significant higher percentage of body fat between 10 and 15 years (boys) and between 8 and 16 years (girls). The difference in overweight between Indian and German children was strongest at 11 (boys) and 12 (girls) years: 70% of the Indian but 20% of the German children were classified as overweight. In countries such as India that undergo nutritional transition, a rapid increase in obesity and overweight is observed. In contrast to the industrialized countries, the risk of overweight in developing countries is associated with high socioeconomic status. Other reasons of the rapid increase of overweight in the developing countries caused by different environmental or genetic factors are discussed.     

Carnitine and creatine content of tissues of normal and alloxan-diabetic sheep and rats

The concentration of carnitine in liver increased 28-fold and urinary carnitine excretion 5-fold in alloxan-diabetic sheep. In contrast there were no similar increases in alloxan-diabetic rats. The creatine content of liver decreased 3-fold and creatine excretion decreased 2-fold in diabetic sheep. In contrast the creatine content of liver increased nearly 4-fold in diabetic rats with no change in creatine excretion. The marked increased in production of carnitine by the liver of the diabetic sheep appears possible because of decreased production and excretion of creatine.     

Coiled-coil nanomechanics and uncoiling and unfolding of the superhelix and alpha-helices of myosin

The nanomechanical properties of the coiled-coils of myosin are fundamentally important in understanding muscle assembly and contraction. Force spectra of single molecules of double-headed myosin, single-headed myosin, and coiled-coil tail fragments were acquired with an atomic force microscope and displayed characteristic triphasic force-distance responses to stretch: a rise phase (R) and a plateau phase (P) and an exponential phase (E). The R and P phases arise mainly from the stretching of the coiled-coils, with the hinge region being the main contributor to the rise phase at low force. Only the E phase was analyzable by the worm-like chain model of polymer elasticity. Restrained molecular mechanics simulations on an existing x-ray structure of scallop S2 yielded force spectra with either two or three phases, depending on the mode of stretch. It revealed that coiled-coil chains separate completely near the end of the P phase and the stretching of the unfolded chains gives rise to the E phase. Extensive conformational searching yielded a P phase force near 40 pN that agreed well with the experimental value. We suggest that the flexible and elastic S2 region, particularly the hinge region, may undergo force-induced unfolding and extend reversibly during actomyosin powerstroke.     

Synthesis and turnover of cerebrosides and phosphatidylserine of myelin and microsomal fractions of adult and developing rat brain.

The synthesis and turnover of cerebrosides and phospholipids was followed in microsomal and myelin fractions of developing and adult rat brains after an intracerebral injection of [U-14C]serine. The kinetics of incorporation of radioactivity into microsomal and myelin cerebrosides indicate the possibility of a precursor-product relationship between cerebrosides of these membranes. The specific radioactivity of myelin cerebrosides was corrected for the deposition of newly formed cerebrosides in myelin. Multiphasic curves were obtained for the decline in specific radioactivity of myelin and microsomal cerebrosides, suggesting different cerebroside pools in these membranes. The half-life of the fast turning-over pool of cerebrosides of myelin was 7 and 22 days for the developing and adult rat brain respectively. The half-life of the slowly turning-over pool of myelin cerebrosides was about 145 days for both groups of animals. The half-life of the rapidly turning-over microsomal cerebrosides was calculated to be 20 and 40 h for the developing and adult animals respectively. The half-life of the intermediate and slowly turning-over microsomal cerebrosides was 11 and 60 days respectively, for both groups of animals. The amount of incorporation of radioactivity into microsomal cerebrosides from L-serine was greatly decreased in the adult animals, and greater amounts of the precursor were directed towards the synthesis of phosphatidylserine. In the developing animals, considerable amounts of cerebrosides were synthesized from L-serine, besides phosphatidylserine. The time-course of incorporation indicated that a precursor-product relationship exists between microsomal and myelin phosphatidylserine. The half-life of microsomal phosphatidylserine was calculated to be about 8 h for the fast turning-over pool in both groups of animals.