科尔沁沙质草地生物量积累过程对降水变化的响应模拟

科尔沁沙地是中国北方严重的沙漠化区域之一,理解其沙质草地生物量积累对降水变化的响应有利于该区域的生态恢复和后续经营管理。在植被-土壤水分耦合模型的基础上结合植被阈值-迟滞响应模式(T-D),在点尺度上模拟科尔沁沙质草地生长季植被生物量积累过程对降水变化的响应。结果表明(1)植被生物量积累对降水量变化表现出明显的非线性响应。降水量增加,促进植被生物量积累,反之则抑制生物量积累,但在同等程度的降水量变化下生物量积累对降水增加的响应远大于对降水量减少的响应。(2)生物量积累对降水频率变化的响应与单次有效降水量变化在干旱年和湿润年都显著正相关,但与累计有效降水量相关性微弱,而与有效降水间隔变化只在干旱年显著相关,表明在不同年份间降水频率变化实际上通过改变单次有效降水量和有效降水间隔来影响生物量的积累。(3)生物量积累过程对降水频率变化存在明显的响应阈值,但该阈值在不同的降水量和降水特征下并不相同。科尔沁沙质草地植被生物量积累过程对降水变化有明显的响应,植被-土壤水分耦合模拟与T-D模型的结合能有效地在日尺度上识别这种响应,这为探究植被和降水关系提供了新工具。     

温度对黄喉拟水龟性别决定的影响

研究了不同孵育温度对黄喉拟水龟(MauremysmuticaCantor)性别决定的影响,同时分析了孵育温度对胚胎发育及成活率的影响。实验设置的3个孵化温度为(25±0.5)℃,(29±0.5)℃和(33±0.5)℃。每一温度指标下设置40枚受精卵。在实验温度内,胚胎的发育速度随着孵化温度的升高而加快,所用的孵育时间也越来越短。孵化累积温度CTUs在25℃时最高,在29℃时最低,而33℃时则居中,在25℃和29℃时,孵化成活率较高,均达到97.5%。在33℃时孵化成活率只有67.5%,而在孵出的稚龟中亦有一定数量的畸形龟,累积孵化温度也高于29℃时的CTUs,说明33℃的孵育温度对胚胎发育有不利影响,预示33℃已临近其胚胎发育的存活阈(Survivalthreshold)。在25℃时,雄性子代占优势,雌性率为23.7%;在33℃时,雌性子代占绝对优势,雌性率为94.7%;在29℃时,性比达到平衡,雌性率为50%。经X2检验,在25℃及33℃时的性比与依赖概率估计的性比(1∶1)有极显著的差异(p<0.005),这种显著的偏离说明黄喉拟水龟的性别决定属于TSD机制,而且可能属于其中的TSDⅠ型,即高温产生雌性子代,低温产生雄性子代。而29℃可能是黄喉拟水龟性别决定的临界温度。     

The complete mitochondrial genome of the butterfly <Emphasis Type="Italic">Apatura metis</Emphasis> (Lepidoptera: Nymphalidae)

As an important pest in the Slender Leaved Willow (Salix alba), Apatura metis is called Freyer’s purple emperor, and its mitochondrial genome is 15,236 bp long. The encoded genes for 22 tRNA genes, two ribosomal RNA (rrnL and rrnS) genes, and 13 protein-coding genes (PCGs), and a control region in the A. metis mitochondria are highly homologous to other lepidopteran species. The mitochondrial genome of A. metis is biased toward a high A + T content (A + T = 80.5%). All protein-coding genes, except for COI begins with the CGA codon as observed in other lepidopterans, start with a typical ATN initiation codon. All tRNAs show the classic clover-leaf structure, except that the dihydrouridine (DHU) arm of tRNA ^Ser(AGN) forms a simple loop. The A. metis A + T-rich region contains some conserved structures including a structure combining the motif ‘ATAGA’ and 19 bp poly (T) stretch, which is similar to those found in other lepidopteran mitogenomes. The phylogenetic analyses of lepidopterans based on mitogenomes sequences demonstrate that each of the six superfamilies is monophyletic, and the relationship among them is (((Noctuoidea + (Geometroidea + Bombycoidea)) + Pyraloidea) + Papilionoidea) + Tortricoidea. In Papilionoidea group, our conclusion argues that ((Lycaenidae + Pieridae) + Nymphalidae) + Papilionidae.     

The Compound Chinese Medicine “Kang Fu Ling” Protects against High Power Microwave-Induced Myocardial Injury

Background

The prevention and treatment of Microwave-caused cardiovascular injury remains elusive. This study investigated the cardiovascular protective effects of compound Chinese medicine “Kang Fu Ling” (KFL) against high power microwave (HPM)-induced myocardial injury and the role of the mitochondrial permeability transition pore (mPTP) opening in KFL protection.

Methods

Male Wistar rats (100) were divided into 5 equal groups: no treatment, radiation only, or radiation followed by treatment with KFL at 0.75, 1.5, or 3 g/kg/day. Electrocardiography was used to Electrophysiological examination. Histological and ultrastructural changes in heart tissue and isolated mitochondria were observed by light microscope and electron microscopy. mPTP opening and mitochondrial membrane potential were detected by confocal laser scanning microscopy and fluorescence analysis. Connexin-43 (Cx-43) and endothelial nitric oxide synthase (eNOS) were detected by immunohistochemistry. The expression of voltage-dependent anion channel (VDAC) was detected by western blotting.

Results

At 7 days after radiation, rats without KFL treatment showed a significantly lower heart rate (P<0.01) than untreated controls and a J point shift. Myocyte swelling and rearrangement were evident. Mitochondria exhibited rupture, and decreased fluorescence intensity, suggesting opening of mPTP and a consequent reduction in mitochondrial membrane potential. After treatment with 1.5 g/kg/day KFL for 7 d, the heart rate increased significantly (P<0.01), and the J point shift was reduced flavorfully (P<0.05) compared to untreated, irradiated rats; myocytes and mitochondria were of normal morphology. The fluorescence intensities of dye-treated mitochondria were also increased, suggesting inhibition of mPTP opening and preservation of the mitochondrial membrane potential. The microwave-induced decrease of Cx-43 and VDAC protein expression was significantly reversed.

Conclusion

Microwave radiation can cause electrophysiological, histological and ultrastructural changes in the heart. KFL at 1.5 g/kg/day had the greatest protective effect on these cardiovascular events. mPTP plays an important role in the protective effects of KFL against microwave-radiation-induced myocardial injury.     

Characterization of the mitochondrial NAD+ -dependent isocitrate dehydrogenase of the oleaginous yeast Rhodosporidium toruloides

Early biochemical studies have demonstrated that lipid accumulation by oleaginous yeasts is linked to the activity of the NAD⁺-dependent isocitrate dehydrogenase (Idh). However, molecular study of Idh of oleaginous microorganisms remains limited. Here, we present the cloning of a mitochondrial NAD⁺-specific Idh from Rhodosporidium toruloides (RtIdh), an excellent microbial lipid producer that uses carbohydrates as the carbon source. The evolutionary relationship analyses among RtIdhs and other yeast Idhs revealed that RtIdh had a closer relationship with the Idhs of Ustilago maydis and Schizophyllum commune. We expressed the RtIDH gene in the yeast Saccharomyces cerevisiae idhΔ mutant. Under the nitrogen-limited condition, the intracellular lipid content and extracellular citrate concentration of the culture of the S. cerevisiae idhΔ carrying the RtIDH gene increased as the carbon/nitrogen molar ratio of the media increased, while the wild-type S. cerevisiae strain showed no correlation. Our data provided valuable information for elucidating the molecular mechanism of microbial oleaginicity and for engineering microorganisms to produce metabolites of fatty acid pathway.     

天山中部天然云杉林森林生态系统降水过程中的水质变化

通过对天山中部天山云杉(Picea schrenkiana var.tianschanica (Rupr.)Chen et Fu)不同郁闭度、林龄天然林区内,降水在转化过程中各环节(包括大气降水、穿透水、地表径流、地下渗水)的水质变化规律,以及森林生态系统不同层次对水质的影响对比分析。结果表明:(1)天山云杉林生态系统对降雨的水质影响,随郁闭度和林龄的增加而增强。在林龄相同的条件下,表现为:0.20.40.60.8;在郁闭度为0.8的条件下,表现为:幼龄林中龄林成熟林近熟林;(2)大气降水透过林冠层后,水中的养分含量显著增高,表现为溶解氧含量减小,氨氮、COD、BOD、总磷、钾含量增加;(3)穿透水转化为地表径流,水中的溶解氧浓度进一步降低,COD、BOD、总磷、钾的含量升高,氨氮浓度降低;(4)总地下渗水的各项水质指标均明显优于大气降水,土壤层是森林生态系统净化水质的关键层。(5)通过对各集水区域水质指标定量化综合评价,天山云杉林生态系统内的水质质量表现为:7月份9月份8月份;(6)利用主成分分析方法(PAC)构建的水质综合评价多元线性模型,具有很强代表性,能很好地用于水质的等级评价。     

Ammonium enhances the uptake, bioaccumulation, and tolerance of phenanthrene in cucumber seedlings

Aims

Phenanthrene is one of the ubiquitous, persistent organic pollutants commonly found in soil and sediments. The study will provide insight regarding the feasibility of nitrogen-assisted phytoremediation.

Methods

To study the effects of various nitrogen forms on cucumber seedling phenanthrene tolerance, hydroponic experiments were conducted in a greenhouse.

Results

Under phenanthrene stress, decreases in plant growth and biomass were more pronounced with a nitrate supply than with ammonium. In addition, phenanthrene concentrations in plants fed with ammonium were higher than those fed with nitrate. The reduction in plant protein and sugar, increases in nitrogen and phosphate concentrations, and increased activity of antioxidative enzymes may contribute to the phenanthrene stress response and adaptation. Higher peroxidase, superoxide dismutase, and catalase activities were found in ammonium-fed plants as compared to nitrate-fed plants under phenanthrene stress. Moreover, the reduction in soluble protein content and increases in phenanthrene transport and accumulation in non-photosynthetic organs may enable ammonium-fed plants to adapt more effectively to adverse conditions.

Conclusions

Overall, these results suggest that ammonium nutrition could provide a useful tool to improve the growth and adaption of plants under phenanthrene stress.