Ecotoxicity of soils contaminated with industrial and domestic wastewater in western Shenyang, China

Soil samples were collected from 7 sites in the up-, mid- and down-reach along and nearby the wastewater irrigation channel, western Shenyang of China. The concentrations of selected pollutants (mineral oil, PAHs - polycycle aromatic hydrocarbons and Cd) were determined by UV spectrometer, HPLC and AAS (atomic adsorption spectrometer) spectrometer, respectively. Toxicity effects of soils were evaluated by seedling emergence test with root length of wheat as the end-point and by earthworms test with the mortality rate and inhibition rates of body weight as endpoints. Results showed accumulation of pollutants for most soils with concentration of 200.2 mg·kg-1-1600 mg·kg-1 for mineral oil, 0.33 mg·kg-1-1.81 mg·kg-1 for Cd and 900.16 mg·kg-1 -2737.91 mg·kg-1 for PAHs. The inhibition rates of root elongation were from -20% up to 40 %, and mortality rates of earthworms ranged from 0%-40% from the exposure period of two weeks to eight weeks by sampling interval of two weeks, the inhibition rates of earthw     

SUMO E3 Ligase AtMMS21 Regulates Drought Tolerance in Arabidopsis thaliana

Post-translational modifications of proteins by small ubiquitin-like modifiers (SUMOs) play crucial roles in plant growth and development, and in stress responses. The MMS21 is a newly-identified Arabidopsis thaliana L. SUMO E3 ligase gene aside from the SIZ1, and its function requires further elucidation. Here, we show that MMS21 deficient plants display improved drought tolerance, and constitutive expression of MMS21 reduces drought tolerance. The expression of MMS21 was reduced by abscisic acid (ABA), polyethylene glycol (PEG) or drought stress. Under drought conditions, mms21 mutants showed the highest survival rate and the slowest water loss, and accumulated a higher level of free proline compared to wild-type (WT) and MMS21 over-expression plants. Stomatal aperture, seed germination and cotyledon greening analysis indicated that mms21 was hypersensitive to ABA. Molecular genetic analysis revealed that MMS21 deficiency led to elevated expression of a series of ABA-mediated stress-responsive genes, including COR15A, RD22, and P5CS1 The ABA and drought-induced stress-responsive genes, including RAB18, RD29A and RD29B, were inhibited by constitutive expression of MMS21. Moreover, ABA-induced accumulation of SUMO-protein conjugates was blocked in the mms21 mutant. We thus conclude that MMS21 plays a role in the drought stress response, likely through regulation of gene expression in an ABA-dependent pathway.     

低温对植物叶片中超氧物歧化酶、过氧化氢酶和过氧化氢水平的影响

番茄和鸡蛋果叶片中可提取的SOD活性不受低温的影响。在电泳谱带上SOD主同工酶带被氰化物而不被低温抑制,次同工酶带在低温下不稳定,且活性很低,它的变化不影响总的SOD活性。一些冷敏感植物叶片中CAT活性被低温抑制,而H_2O_3水平在低温下稳定或有增加,这可能使毒性更强的羟基离子(OH·)易于形成。     

NAD~+对小麦叶片线粒体甘氨酸氧化和三羧酸代谢的调节

外源NAD~+对小麦叶片线粒体内甘氨酸、苹果酸及α—酮戊二酸氧化都有促进作用。当几种呼吸底物同时存在时,其中甘氨酸的氧化抑制了其他底物的同时氧化,因为催化这两类废物氧化的酶对NAD~+的亲和力和对NADH/NAD~+比值的敏感程度有差异,催化甘氨酸氧化的甘氨酸脱羧酶对线粒体基质内可利用的NAD~+的亲和力分别比苹果酸脱氢酶和α—酮戊二酸脱氢酶的亲和力大约1或2倍。另外,甘氨酸亦可通过保持线粒体基质内高NADH/NAD~+比值来影响三羧酸环的正常代谢。     

多效唑调节水稻植株生长的作用机理

多效唑处理水稻植株后使株高降低和分蘖增加,植株体内的GA类物质和IAA含量相应下降,乙烯释放率显著增加;用外源GA_3和氮肥能逆转多效唑的抑制作用而使株高增加,同时GA类物质含量也明显增加。因此,多效唑不仅调节体内的GA类物质含量,还能通过调节IAA含量和乙烯释放率而影响植物生长。     

植物鲜嫩组织电阻的构成

用高渗溶液处理植物鲜嫩组织,R_t增至对照的3～4倍,用电导率不同的营养液浸泡被测组织,发现R_t值并不依赖于环境溶液的电导率。在利用胞外电极和直流电测量R_t时,施加于组织的电流约有75～90％是流经共质体的。R_t主要是反映了共质体的电导状况,即反映了膜透性的大小和细胞间电偶联的程度。     

粟长孺孢菌的异核现象

本文报道了粟长孺孢的菌(Hetminthosporium setariae)的异核现象。用γ-射线和甲基磺酸乙酯诱变获得的颜色、形态和营养突变株(H8、Hw)可在基本培养基上形成异核体(8W)。其以上各种特性不同于亲本。 8W分离之后的突变株可稳定地传代,混合后仍能形成异核体。从而证实了该菌的异核性。观察并测定了亲本株和异核体的生长率、致病性及产孢能力。粟长孺孢菌(H8)和玉蜀黍长孺孢菌(866·R-8)可形成种间异核体。