Computational studies on polynitropurines as potential high energy density materials

As part of a search for high energy density materials (HEDMs), a series of purine derivatives with nitro groups were designed computationally. The relationship between the structures and the performances of these polynitropurines was studied. Density functional theory (DFT) at the B3LYP/6-311G** level was employed to evaluate the heats of formation (HOFs) of the polynitropurines by designing an isodesmic reaction method. Results indicated that the HOFs were influenced by the number and positions of substituent groups. Detonation properties were evaluated using the Kamlet–Jacobs equations, based on the theoretical densities and heats of formation of the polynitropurines. The relative stabilities of the polynitropurines were studied via the pyrolysis mechanism and the UB3LYP/6-311G** method. Homolysis of the ring–NO₂ bond is predicted to be the initial step in the thermal decomposition of these purine derivatives. Considering their detonation properties and relative stabilities, the tetranitropurine (D1) derivatives may be regarded as potential candidates for practical HEDCs. These results may provide useful information for further investigations.     

稀土元素对甜菜种子萌发,幼苗生长及块根产量的影响

本文研究了稀土元素对甜菜的生物效应。结果表明,稀土元素可显著地提高种子萌发率,促进幼苗生长,增加幼苗根系活力、叶片净光合速率与块根产量,并明显地降低了甜菜叶片细胞膜在低温下的透性,即提高了叶片的抗寒力。     

Human placenta-derived mesenchymal stem cells loaded on linear ordered collagen scaffold improves functional recovery after completely transected spinal cord injury in canine

Traumatic spinal cord injury(SCI) is a major challenge in the clinic. In this study, we sought to examine the synergistic effects of linear ordered collagen scaffold(LOCS) and human placenta-derived mesenchymal stem cells(hPMSCs) when transplanted into completely transected beagle dogs. After 36 weeks observation, we found that LOCS+hPMSCs implants promoted better hindlimb locomotor recovery than was observed in the non-treatment(control) group and LOCS group. Histological analysis showed that the regenerated tissue after treatment was well integrated with the host tissue, and dramatically reduced the volume of cystic and chondroitin sulfate proteoglycans(CSPGs) expression. Furthermore, the LOCS+hPMSCs group also showed more neuron-specific βIII-tubulin(Tuj-1)-and NeuN-positive neurons in the lesion area, as well as axonal regeneration, remyelination and synapse formation in the lesion site. Additionally, dogs in the LOCS+hPMSCs group experienced enhanced sprouting of both ascending(CGRP-positive) sensory fibers and descending(5-HT-and TH-positive) motor fibers at the lesion area. All these data together suggested that the combined treatment had beneficial effects on neuronal regeneration and functional improvement in a canine complete transection model. Therefore, LOCS+hPMSCs implantation holds a great promise for bridging the nerve defect and may be clinically useful in the near future.     

Targeting P2 receptors in purinergic signaling: a new strategy of active ingredients in traditional Chinese herbals for diseases treatment

Adenosine triphosphate (ATP) and its metabolites adenosine diphosphate, adenosine monophosphate, and adenosine in purinergic signaling pathway play important roles in many diseases. Activation of P2 receptors (P2R) channels and subsequent membrane depolarization can induce accumulation of extracellular ATP, and furtherly cause kinds of diseases, such as pain- and immune-related diseases, cardiac dysfunction, and tumorigenesis. Active ingredients of traditional Chinese herbals which exhibit superior pharmacological activities on diversified P2R channels have been considered as an alternative strategy of disease treatment. Experimental evidence of potential ingredients in Chinese herbs targeting P2R and their pharmacological activities were outlined in the study.

     

Valsartan ameliorates ageing‐induced aorta degeneration via angiotensin II type 1 receptor‐mediated ERK activity

Angiotensin II (Ang II) plays important roles in ageing‐related disorders through its type 1 receptor (AT₁R). However, the role and underlying mechanisms of AT1R in ageing‐related vascular degeneration are not well understood. In this study, 40 ageing rats were randomly divided into two groups: ageing group which received no treatment (ageing control), and valsartan group which took valsartan (selective AT1R blocker) daily for 6 months. 20 young rats were used as adult control. The aorta structure were analysed by histological staining and electron microscopy. Bcl‐2/Bax expression in aorta was analysed by immunohistochemical staining, RT‐PCR and Western blotting. The expressions of AT₁R, AT₂R and mitogen‐activated protein kinases (MAPKs) were detected. Significant structural degeneration of aorta in the ageing rats was observed, and the degeneration was remarkably ameliorated by long‐term administration of valsartan. With ageing, the expression of AT1R was elevated, the ratio of Bcl‐2/Bax was decreased and meanwhile, an important subgroup of MAPKs, extracellular signal‐regulated kinase (ERK) activity was elevated. However, these changes in ageing rats could be reversed to some extent by valsartan. In vitro experiments observed consistent results as in vivo study. Furthermore, ERK inhibitor could also acquire partial effects as valsartan without affecting AT1R expression. The results indicated that AT1R involved in the ageing‐related degeneration of aorta and AT1R‐mediated ERK activity was an important mechanism underlying the process.     

A mechanism coordinating root elongation,endodermal differentiation,redox homeostasis and stress response

Root growth relies on both cell division and cell elongation, which occur in the meristem and elongation zones, respectively. SCARECROW (SCR) and SHORT-ROOT (SHR) are GRAS family genes essential for root growth and radial patterning in the Arabidopsis root. Previous studies showed that SCR and SHR promote root growth by suppressing cytokinin response in the meristem, but there is evidence that SCR expressed beyond the meristem is also required for root growth. Here we report a previously unknown role for SCR in promoting cell elongation. Consistent with this, we found that the scr mutant accumulated a higher level of reactive oxygen species (ROS) in the elongation zone, which is probably due to decreased expression of peroxidase gene 3, which consumes hydrogen peroxide in a reaction leading to Casparian strip formation. When the oxidative stress response was blocked in the scr mutant by mutation in ABSCISIC ACID 2 (ABA2) or when the redox status was ameliorated by the upbeat 1 (upb1) mutant, the root became significantly longer, with longer cells and a larger and more mitotically active meristem. Remarkably, however, the stem cell and radial patterning defects in the double mutants still persisted. Since ROS and peroxidases are essential for endodermal differentiation, these results suggest that SCR plays a role in coordinating cell elongation, endodermal differentiation, redox homeostasis and oxidative stress response in the root. We also provide evidence that this role of SCR is independent of SHR, even though they function similarly in other aspects of root growth and development.     

A taxonomic study of Ooctonus (Hymenoptera,Mymaridae) from Heilongjiang,China

Five species of Ooctonus Haliday (Hymenoptera, Mymaridae) from Heilongjiang Province, China, are reviewed. One species, Ooctonus huberi sp. n., is described as new, and four species, Ooctonus orientalis Doutt, Ooctonus saturn Triapitsyn, Ooctonus sublaevis Förster and Ooctonus vulgatus Haliday are reported as new to China. A key to the females of the 10 described Chinese species is given. All the specimens are deposited in the insect collections of Northeast Forestry University, China.     

Secretion expression of SOD1 and its overlapping function with GSH in brewing yeast strain for better flavor and anti-aging ability

Superoxide dismutase (SOD) is a significant antioxidant, but unlike glutathione (GSH), SOD cannot be secreted into beer by yeast cells during fermentation, this directly leads to the limited application of SOD in beer anti-aging. In this investigation, we constructed the SOD1 secretion cassette in which strong promoter PGK1p and the sequence of secreting signal factor from Saccharomyces cerevisiae were both harbored to the upstream of coding sequence of SOD1 gene, as a result, the obtained strains carrying this cassette successfully realized the secretion of SOD1. In order to overcome the limitation of previous genetic modification on yeast strains, one new comprehensive strategy was adopted targeting the suitable homologous sites by gene deletion and SOD1 + GSH1 co-overexpression, and the new strain ST31 (Δadh2::SOD1 + Δilv2::GSH1) was constructed. The results of the pilot-scale fermentation showed that the diacetyl content of ST31 was lower by 42 % than that of the host, and the acetaldehyde content decreased by 29 %, the GSH content in the fermenting liquor of ST31 increased by 29 % compared with the host. Both SOD activity test and the positive and negative staining assay after native PAGE indicated that the secreted active SOD in the fermenting liquor of ST31 was mainly a dimer with the size of 32,500 Da. The anti-aging indexes such as the thiobarbituric acid and the resistance staling value further proved that the flavor stability of the beer brewed with strain ST31 was not only better than that of the original strain, but also better than that of the previous engineering strains. The multi-modification and comprehensive improvement of the beer yeast strain would greatly enhance beer quality than ever, and the self-cloning strain would be attractive to the public due to its bio-safety.     

中国多孔菌科一新记录属——棘刚毛菌属(Echinochaete)

笔者1987年9月8日在吉林省张广才岭老爷岭山采到一份标本,生于阔叶树腐木上,经鉴定为短孔棘刚毛菌(Echinochaete brachyporus)隶属于多孔菌科(Polyporaceae),棘刚毛菌属(Echinochaete)。棘刚毛菌属为多孔菌科中一个较小的属,现已见报道的共有6种1变种,分布于世界许多地区。对于本属及其种类在我国未曾有记载。本文对该属的概况及新记录种的特征、分布作了报导。