寡毛类纤毛虫变游虫新属的建立及基尔变游虫(新属,新组合)的形态学重描述与系统地位分析(英文)

利用蛋白银染色技术对采自青岛沿海砂隙的寡毛类纤毛虫Strombidium kielum进行了形态学重描述,发现该种在寡毛类纤毛虫中具有独一无二的纤毛下器模式,因此为其建立了1新属Varistrombidium,特征为具有5条斜穿虫体的体动基列,其中体动基列1和2延伸到虫体背部,终止于虫体尾端。对Varistrombidium kielum(Maeda&Carey,1985)nov.comb.的小亚基RNA序列分析表明,该种位于Strombidiidae科内,与其形态学相近种Omegastrombidium elegans聚在一起。同时对其小亚基RNA序列可变区2的二级结构进行了预测并与其形态学相似种进行了比较。还对Apostrombidium pseudokielum Xuet al.,2009进行了补充性描述。     

黄河上游灌区稻田N2O排放特征

黄河上游灌区稻田高产区过量施肥现象十分突出,氮肥过量施用引起土壤氮素盈余,导致N₂O排放量增大,由此引起的温室效应引起广泛关注。采用静态箱-气相色谱法研究黄河上游灌区稻田不同施肥处理下N₂O排放特征。试验设置5个施肥处理,包括常规氮肥300 kg/hm²下单施尿素和有机肥配施2个处理,分别用N300和N300-OM代表;优化氮肥240 kg/hm²下单施尿素和有机肥配施2个处理,分别用N240和N240-OM代表;对照不施氮肥用N0代表。试验结果得出,灌区水稻生长季稻田土壤N₂O排放主要集中在水稻分蘖前及水稻生长的中后期,稻田氮肥施用、灌水及土壤温度的变化对N₂O排放通量影响较大,不同处理水稻各生育阶段N₂O累积排放量与稻田土壤耕层NO^-₃-N含量动态变化显著相关。稻田N₂O排放不是黄河上游灌区稻田氮素损失的主要途径,但灌区稻田N₂O排放的增温潜势较大;稻田氮肥过量施用会显著增加N₂O排放量,在相同氮素水平下,有机肥配施会显著增加稻田土壤N₂O的排放量(P＜0.01)。优化施氮能有效减少灌区稻田水稻生长季N₂O排放量。稻田不同处理的水稻整个生长季土壤N₂O排放总量为2.69-3.87 kg/hm²,肥料氮通过N₂O排放损失的百分率仅为0.43%-0.64%。在灌区习惯灌水和高氮肥300 kg/hm²时,N300-OM处理的稻田N₂O排放量达3.87 kg/hm²,在100 a时间尺度上的全球增温潜势(GWPs)为20.76×10⁷ kg CO₂/hm²;优化施氮240 kg/hm²水平下,N240和N240-OM处理的N₂O累计排放量较N300-OM处理,分别降低了1.18 kg/hm²和0.57 kg/hm²,在100 a尺度上每年由稻田N₂O排放引起的GWPs分别降低了6.33×10⁷ kg CO₂/hm²和3.06×10⁷ kg CO₂/hm²。     

高温对两种卡帕藻的酶活性、色素含量与叶绿素荧光的影响

在室内采用静置培养法,以25℃为对照,研究高温(32℃、35℃和40℃)对长心卡帕藻Kappaphycus alvarezii与异枝卡帕藻K.striatum的硝酸还原酶(NR)和过氧化物酶(POD)活性、叶绿素a和藻红蛋白含量的影响,并采用调制叶绿素荧光技术,测定高温处理后2种藻的叶绿素荧光参数变化趋势.结果表明:高温对2种卡帕藻的NR和POD活性有显著影响.二者的NR活性均在35℃时最低,32℃时最高;异枝卡帕藻的POD活性在35℃时最高,而长心卡帕藻的在35℃时最低.在25-40℃之间,随着温度升高,异枝卡帕藻的叶绿素a含量逐渐减少,藻红蛋白含量先降后升,35℃时最高,而长心卡帕藻的两种色素含量皆在25℃时最高.在32-40℃条件下,随着温度升高,2种藻的实际光合效率(Y)和相对光合电子传递速率(ETR)明显下降,温度越高,下降程度越大;短期高温可刺激2种卡帕藻的光合活性增强,随着处理时间延长,异枝卡帕藻的光合活性下降,但差异不显著,而长心卡帕藻的光合活性显著下降.综合上述指标,显示32℃以上高温对2种卡帕藻产生胁迫,异枝卡帕藻对热胁迫的耐受力明显强于长心卡帕藻.     

大孔树脂——溶剂萃取法精制高色价栀子黄色素的集成技术研究

以栀子为原料提取栀子黄色素,采用大孔吸附树脂--有机溶剂萃取相结合的集成技术,从栀子中分离纯化得到高色价的栀子黄色素.先采用大孔吸附树脂对栀子黄色素进行初步精制,以306型大孔吸附树脂为研究对象,探讨了大孔树脂对栀子黄色素的静态吸附率、吸附流速和洗脱剂浓度对吸附的影响,从而得到较为合适的工艺:吸附流速2.O mT/mi...     

响应曲面法优化菌丝体中红曲色素的提取条件

以红曲菌丝体为原料,通过单因素实验及Box-Behnken设计响应曲面分析优化了红曲色素的提取工艺条件。通过实验,得到了提取率的回归方程Y=0.923-0.011X1-0.011X2-0.017X12-0.027X22-0.026X32-0.028X1X2-0.019X1X3,通过对模型解逆矩阵得优化方案:乙醇浓度X1=66%、超声功率X2=200 w、提取温度X3=52℃,模型预测结果为92.5%。在该工艺条件下进行验证实验,提取率达到92.1±0.6%(n=3)。     

Effect of ultraviolet radiation on chlorophyll,carotenoid, protein and proline contents of some annual desert plants

Investigation was carried out to find whether enhanced ultraviolet radiation influences the Malva parviflora L., Plantago major L., Rumex vesicarius L. and Sismbrium erysimoids Desf. of some annual desert plants. The seeds were grown in plastic pots equally filled with a pre-sieved normal sandy soil for 1 month. The planted pots from each species were randomly divided into equal groups (three groups). Plants of the first group exposed to white-light tubes (400–700 nm) 60 w and UV (365 nm) 8 w tubes. The second group was exposed to white-light tubes (400–700 nm) 60 w and UV (302 nm) 8 w tubes. The third group was exposed to white-light tubes (400–700 nm) 60 w and UV (254 nm) 8 w tubes, respectively, for six days. The results indicated that the chlorophyll contents were affected by enhanced UV radiation. The chlorophyll a, b, and total contents were decreased compared with the control values and reduced with the enhanced UV radiation, but the carotenoid was increased compared with the control and also reduced with the enhanced UV radiation. So, the contents of chlorophylls varied considerably. M. parviflora showed the highest constitutive levels of accumulated chlorophyll a, b, and total chlorophyll (0.463, 0.307 and 0.774 mg g⁻¹ f w) among the investigated plant species. P. major showed the lowest constitutive levels of the chloroplast pigments, 0.0036, 0.0038 and 0.0075 mg g⁻¹ f w for chlorophyll a, b, and total chlorophyll at UV-365 nm, respectively. The protein content was decreased significantly in both root and shoot systems compared with the control values but, it was increased with increasing wave lengths of UV-radiation of all tested plants. R. vesicarius showed the highest protein contents among the investigated plants; its content was 3.8 mg g⁻¹ f w at UV-365 nm in shoot system. On the other hand, decreasing ultraviolet wave length induced a highly significant increase in the level of proline in both root and shoot of all tested plants. From the results obtained, it is suggested that proline can protect cells against damage induced by ultraviolet radiation. Statistically, the variations of the studied metabolic activities were significant due to UV radiation treatment in shoot and root system of all investigated plant species.     

Growth parameters and photosynthetic pigments in leaf segments of Zea mays exposed to cadmium, as related to protection mechanisms

The influence of cadmium on growth parameters and photosynthetic pigment content was studied in maize leaf segments differing in tissue maturity. Experiments were carried out with maize seedlings Zea mays L. cv. Hidosil treated with 25, 50, 100, 150 and 200 microM Cd for 14 days under low light conditions. Tissue age-dependent decrease of fresh mass, dry mass and area of the leaf segments was correlated with Cd concentration in the growth medium. Cd induced changes in chlorophyll and carotenoid contents, and the specific areas and densities of the leaf segments were dependent on age and metal concentration. Results are discussed with respect to the protection mechanisms in the leaf segments.     

Testing for endocytosis in plants

Summary. For many years endocytosis has been regarded with great scepsis by plant physiologists. Although now generally accepted, care must still be taken with experiments designed to demonstrate endocytic uptake at the plasma membrane. We have taken a critical look at the various agents which are in use as markers for plant endocytosis, pointing out pitfalls and precautions which should be taken. We also take this opportunity to introduce the tyrphostins – tyrosine kinase inhibitors –, which also seem to prevent endocytosis in plants. Correspondence and reprints: Heidelberg Institute for Plant Sciences, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Federal Republic of Germany.     

Reconstitution of ancestral green visual pigments of zebrafish and molecular mechanism of their spectral differentiation

We previously reported that zebrafish have four tandemly duplicated green (RH2) opsin genes (RH2-1, RH2-2, RH2-3, and RH2-4). Absorption spectra vary widely among the four photopigments reconstituted with 11-cis retinal, with their peak absorption spectra (lambda(max)) being 467, 476, 488, and 505 nm, respectively. In this study, we inferred the ancestral amino acid (aa) sequences of the zebrafish RH2 opsins by likelihood-based Bayesian statistics and reconstituted the ancestral opsins by site-directed mutagenesis. The ancestral pigment (A1) to the four zebrafish RH2 pigments and that (A3) to RH2-3 and RH2-4 showed lambda(max) at 506 nm, while that (A2) to RH2-1 and RH2-2 showed a lambda(max) at 474 nm, indicating that a spectral shift had occurred toward the shorter wavelength on the evolutionary lineages A1 to A2 by 32 nm, A2 to RH2-1 by 7 nm, and A3 to RH2-3 by 18 nm. Pigment chimeras and site-directed mutagenesis revealed a large contribution (approximately 15 nm) of glutamic acid to glutamine substitution at residue 122 (E122Q) to the A1 to A2 and A3 to RH2-3 spectral shifts. However, the remaining spectral differences appeared to result from complex interactive effects of a number of aa replacements, each of which has only a minor spectral contribution (1-3 nm). The four zebrafish RH2 pigments cover nearly an entire range of lambda(max) distribution among vertebrate RH2 pigments and provide an excellent model to study spectral tuning mechanisms of RH2 in vertebrates.     

Lethal effects of experimental warming approximating a future climate scenario on southern African quartz-field succulents: a pilot study

Here we examine the response of succulents in a global biodiversity hot spot to experimental warming consistent with a future African climate scenario. Passive daytime warming (averaging 5.5 degrees C above ambient) of the natural vegetation was achieved with 18 transparent hexagonal open-top chamber arrays randomized in three different quartz-field communities. After 4-months summer treatment, the specialized-dwarf and shrubby succulents displayed between 2.1 and 4.9 times greater plant and canopy mortalities in the open-top chambers than in the control plots. Those surviving in cooler ventilated areas and shaded refuges in the chambers had lower starch concentrations and water contents; the shrubby succulents also exhibited diminished chlorophyll concentrations. It is concluded that current thermal regimes are likely to be closely proximate to tolerable extremes for many endemic succulents in the region, and that anthropogenic warming could significantly exceed their thermal thresholds. Further investigation is required to elucidate the importance of associated moisture deficits in these warming experiments, a potential consequence of supplementary (fog and dew) precipitation interception by open-top chambers and higher evaporation therein, on plant mortalities.