Different response of photosystem II to short and long‐term drought stress in Arabidopsis thaliana

Short‐ and long‐term drought stress on photosystem II (PSII) and oxidative stress were studied in Arabidopsis thaliana. Under drought stress, chlorophyll (Chl) content, Chl fluorescence, relative water content and oxygen evolution capacity gradually decreased, and the thylakoid structure was gradually damaged. Short‐term drought stress caused a rapid disassembly of the light‐harvesting complex II (LHCII). However, PSII dimers kept stable under the short‐term drought stress and significantly decreased only after 15 days of drought stress. Immunoblotting analysis of the thylakoid membrane proteins showed that most of the photosystem proteins decreased after the stress, especially for Lhcb5, Lhcb6 and PsbQ proteins. However, surprisingly, PsbS significantly increased after the long‐term drought stress, which is consistent with the substantially increased non‐photochemical quenching (NPQ) after the stress. Our results suggest that the PSII–LHCII supercomplexes and LHCII assemblies play an important role in preventing photo‐damages to PSII under drought stress.     

Actaea muliensis sp. nov. (Ranunculaceae), an unusual species with dark purple staminodes from western Sichuan,China

Actaea muliensis (Ranunculaceae), a new species from Muli County, Sichuan Province, China, is described and illustrated. Morphologically, it is somewhat similar to A. mairei, but is most readily distinguishable from that species and others within A. sect. Cimicifuga by, among other characters, the dark purple (vs yellow) staminodes. Actaea muliensis is revealed to be a diploid (2n = 16) species with 3‐colpate pollen.     

Taxonomic notes on Cimicifuga nanchuanensis (Ranunculaceae), a hitherto imperfectly known species from China

Cimicifuga nanchuanensis P. K. Hsiao (Ranunculaceae) has been regarded as an imperfectly known species. Based on critical examination of herbarium specimens and living plants we have determined that it is a morphologically distinctive species and that its geographical range is much wider than believed before, far from locally endemic to its type locality. Our cytological examination reveals the species to be a diploid (2n = 16). Our molecular phylogenetic analyses using nrDNA and cpDNA datasets confirm our morphological observations. As the generic concept and delimitation of Actaea L., in which Cimicifuga Wernisch. and Souliea Franch. are included, have also been strongly corroborated by our molecular phylogenetic analyses, here we adopt a broad Actaea and make a new combination for the species in question, i.e. Actaea nanchuanensis (P. K. Hsiao) J. P. Luo, Q. Yuan & Q. E. Yang.     

Serum metabolomic markers for traumatic brain injury: a mouse model

Introduction

Traumatic brain injury (TBI) is physical injury to brain tissue that temporarily or permanently impairs brain function.

Objectives

Evaluate the use of metabolomics for the development of biomarkers of TBI for the diagnosis and timing of injury onset.

Methods

A validated model of closed injury TBI was employed using 10 TBI mice and 8 sham operated controls. Quantitative LC–MS/MS metabolomic analysis was performed on the serum.

Results

Thirty-six (24.0 %) of 150 metabolites were altered with TBI. Principal component analysis (PCA) and Partial least squares discriminant analysis (PLS-DA) analyses revealed clear segregation between TBI versus control sera. The combination of methionine sulfoxide and the lipid PC aa C34:4 accurately diagnosed TBI, AUC (95 % CI) 0.85 (0.644–1.0). A combination of metabolite markers were highly accurate in distinguishing early (4 h post TBI) from late (24 h) TBI: AUC (95 % CI) 1.0 (1.0–1.0). Spermidine, which is known to have an antioxidant effect and which is known to be metabolically disrupted in TBI, was the most discriminating biomarker based on the variable importance ranking in projection (VIP) plot. Several important metabolic pathways were found to be disrupted including: pathways for arginine, proline, glutathione, cysteine, and sphingolipid metabolism.

Conclusion

Using serum metabolomic analysis we were able to identify novel putative serum biomarkers of TBI. They were accurate for detecting and determining the timing of TBI. In addition, pathway analysis provided important insights into the biochemical mechanisms of brain injury. Potential clinical implications for diagnosis, timing, and monitoring brain injury are discussed.

     

Effect of pH on the activity of nervous cholinesterases of the rat towards different biochemical and histochemical substrates and inhibitors

Summary Cholinesterase activities of homogenates of rat brain and superior cervical ganglion were determined by automatic titration using several biochemical and histochemical substrates. High hydrolysis rates were observed when acetylcholine, acetylthiocholine, propionylcholine or propionylthiocholine was used as substrate; -naphthyl acetate and acetyl--methylcholine were hydrolyzed at a moderate rate, and activities were low towards butyrylcholine, butyrylthiocholine and benzoylcholine. With most substrates, the enzyme activity increased from pH 5 to pH 10 and decreased at pH 11. Acetylcholine and acetyl--methylcholine showed an activity maximum at pH 7 or 8. Inhibition by the selective inhibitor of specific cholinesterase 284 C 51 was not markedly affected by pH. On the other hand, the inhibiting power of the selective inhibitor of non-specific cholinesterase iso-OMPA markedly decreased when the pH was lowered. The inhibitor data at different pHs and with different concentrations of eserine, 284 C 51 or iso-OMPA at pH 6 indicated that acetylcholine, propionylcholine and propionylthiocholine are readily hydrolyzed by both specific and non-specific cholinesterase, while acetyl--methylcholine is mainly split by specific cholinesterase and butyrylcholine mainly by non-specific cholinesterase. The significance of propionylcholine and propionylthiocholine as substrates of specific cholinesterase is emphasized.     

Taxonomic status and distributional range of Aconitum angustius (Ranunculaceae) based on cytological evidence

Aconitum sinomontanum Nakai var. angustius W. T. Wang (Ranunculaceae) has been recorded to occur only in the Anhui, Jiangxi and Hunan provinces, China. However, it is here revealed to be a much more widespread tetraploid (2n = 32) entity almost allopatric with the diploid (2n = 16) A. sinomontanum s.s. The former entity has a southern distribution in China, occurring in Anhui, Chongqing, northern Guangxi, Guizhou, southern Henan, northwestern Hubei, Hunan, and Jiangxi, while the latter has a relatively northern distribution, occurring in northeastern Chongqing, southern Gansu, Hebei, western Henan, western Hubei, eastern Qinghai, Shaanxi, Shanxi, and Sichuan. There is only minor overlap of the geographical distributions of the diploid and tetraploid populations, with both entities documented as co‐occurring in northeastern Chongqing and northwestern Hubei. The two entities also are very different from each other in karyotypic constitution. As A. sinomontanum var. angustius is fairly well differentiated from A. sinomontanun in external morphology, ploidy level, karyotypic constitution and geographical distribution, it seems justified to recognize A. sinomontanum var. angustius, an entity possibly of allopolyploid origin, as the independent species A. angustius (W. T. Wang) W. T. Wang.     

Electron microscopic demonstration of cholinesterases in nervous tissue

Summary Acetylcholinesterase was demonstrated at ultrastructural level in the motor nerve cells of rat's spinal cord using the Karnovsky-Roots modification of Koelle's thiocholine method. Selective inhibitors were employed to check the validity of the reaction.Prolonged formaldehyde fixation improved the poor penetration of the reactive agents and diminished the relatively large crystal size of the end product, which were the two main difficulties of the method. The preservation of ultrastructure was highly improved, when thin sections were made without freezing using a tissue chopper.Acetylcholinesterase was localized in the nuclear envelope, in the rough-surfaced endoplasmic reticulum, in medium-sized vesicles of the Golgi apparatus, and around synaptic terminals. Synaptic vesicles were found negative.     

生物样本库是生物医学研究的重要基础

在生物医学研究飞速发展的今天,随着对健康和疾病认识的不断深入,传统的单病因、单基因研究模式已难以胜任复杂疾病的研究.医学科学的发展需要一种能提供疾病相关的、具有普遍意义的、全局式的分子信息数据库.生物样本库在其中所能发挥的关键作用得到了越来越多的重视.它从最初的小作坊模式经过100多年,尤其是近30年的快速发展已经演化成为科研院所和政府支持的生物样本库、商业化生物样本库及以人口为基础的生物银行等多种模式.伴随存储样本数据信息的复杂度不断快速增加,生物样本库除了收集样本相关的基本数据和诊断信息外,还延伸到配套信息,包括参加人和病人的多种表型,到目前已经迅速扩展到基因组学、蛋白质组学及其他的组学信息.如何科学地建设和管理这种大型复杂模式的生物样本库成为医学科学领域亟待规范、解决的问题.本文将从生物样本库的发展入手重点讨论其建设、管理和应用.