Single chain antibody displays glutathione S-transferase activity

Substrate binding and the subsequent reaction are the two principal phenomena that underlie the activity of enzymes, and many enzyme-like catalysts were generated based on the phenomena. The single chain variable region fragment of antibody 2F3 (scFv2F3) was elicited against hapten GSH-S-DN2phBu, a conjugate of glutathione (GSH), butyl alcohol, and 1-chloro-2,4-dinitrobenzene (CDNB); it can therefore bind both GSH and CDNB, the substrates of native glutathione S-transferases (GSTs). It was shown previously that there is a serine residue that is the catalytic group of GST in the CDR regions of scFv2F3 close to the sulfhydryl of GSH. Thus, we anticipated that scFv2F3 will display GST activity. The experimental results showed that scFv2F3 indeed displayed GST activity that is equivalent to the rat-class GST T-2-2 and exhibited pH- and temperature-dependent catalytic activity. Steady-state kinetic studies showed that the Km values for the substrates are close to those of native GSTs, indicating that scFv2F3 has strong affinities for the substrates. Compared with some other GSTs, its kcat value was found to be low, which could be caused by the similarity between the GSH-S-DN2phBu and the reaction product of GSH and CDNB. These results showed that our approach to imitating enzymes is correct, which is that an active site may catalyze a chemical reaction when a catalytic group locates beside a substrate-binding site of a receptor. It is important to consider product inhibition in hapten design in order to obtain a mimic with a high catalytic efficiency.     

Bioinformatic analysis of BBTV satellite DNA in Hainan

Banana bunchy top virus (BBTV),family Nanaviridae,genus Babuvirus,is a single stranded DNA virus (ssDNA) that causes banana bunchy top disease (BBTD) in banana plants.It is the most common and most destructive of all viruses in these plants and is widespread throughout the Asia-Pacific region.In this study we isolated,cloned and sequenced a BBTV sample from Hainan Island,China.The results from sequencing and bioinformatics analysis indicate this isolate represents a satellite DNA component with 12 DNA sequences motifs.We also predicted the physical and chemical properties,structure,signal peptide,phosphorylation,secondary structure,tertiary structure and functional domains of its encoding protein,and compare them with the corresponding quantities in the replication initiation protein of BBTV DNA1.     

Influences of Environmental Factors on Leaf Morphology of Chinese Jujubes

Rainfall and temperature are the primary limiting factors for optimum quality and yield of cultivated jujube (Ziziphus jujuba Mill.). Adaptation to arid and cool environments has been and remains an important goal of many jujube improvement programs. This study summarized the survey results of 116 Chinese jujube varieties grown at 33 sites in China. The objective was to identify the environmental factors that influence leaf morphology, and the implications for breeding and introduction of new jujube varieties. Jujube leaf morphological traits were evaluated for their potential relationships with mean annual temperature (MAT) and mean annual precipitation (MAP). The results showed that many leaf morphological traits had a strong linear relationship with local precipitation and temperature. Longer veins per unit area (VLA) and reduced leaf area and leaf perimeter were typical of arid areas. VLA was inversely related to MAT and MAP at the centers of origin of jujube. There was a positive relationship between leaf shape (perimeter²/area) and both MAT and MAP. These results indicated that leaf vein traits of Chinese jujubes might have resulted from their adaptation to environmental factors in the course of long-term evolution. Principal component analysis allocated the 116 jujube varieties to three different groups, differentiated on the basis of morphological and physiological leaf characteristics. Jujube varieties from the Hebei, Shandong, Henan, southern Shanxi and central Shaanxi provinces were closely related, as were varieties from northwest Shanxi and northeast Shaanxi provinces, and varieties from the Gansu and Ningxia provinces. These close relationships were partially attributed to the frequent exchanges of varieties within each group. Leaf venation characteristics might be used as reference indices for jujube variety introduction between different locations.Influences of Environmental Factors on Leaf Morphology of Chinese Jujubes     

Comparison of the effects of symmetric and asymmetric temperature elevation and CO2 enrichment on yield and evapotranspiration of winter wheat (Triticum aestivum L.)

Under the changing climate, asymmetric warming pattern would be more likely during day and night time, instead of symmetric one. Concurrently, the growth responses and water use of plants may be different compared with those estimated based on symmetric warming. In this work, it was compared with the effects of symmetric (ETs) and asymmetric (ETa) elevation of temperature alone, and in interaction with elevated carbon dioxide concentration (EC), on the grain yield (GY) and evapotranspiration in winter wheat (Triticum aestivum L.) based on pot experiment in the North China Plain (NCP). The experiment was carried out in six enclosed‐top chambers with following climate treatments: (1) ambient temperature and ambient CO₂ (CON), (2) ambient temperature and elevated CO₂ (EC), (3) elevated temperature and ambient CO₂ (ETs; ETa), and (4) elevated temperature and elevated CO₂ (ECETs, ECETa). In symmetric warming, temperature was increased by 3°C and in asymmetric one by 3.5°C during night and 2.5°C during daytime, respectively. As a result, GY was in ETa and ETs 15.6 (P < 0.05) and 10.3% (P < 0.05) lower than that in CON. In ECETs and ECETa treatments, GY was 14.9 (P < 0.05) and 9.1% (P < 0.05) higher than that in CON. Opposite to GY, evapotranspiration was 7.8 (P < 0.05) and 17.9% (P < 0.05) higher in ETa and ETs treatments and 7.2 (P < 0.05) and 2.1% (P > 0.05) lower in ECETs and ECETa treatments compared with CON. Thus, GY of wheat could be expected to increase under the changing climate with concurrent elevation of CO₂ and temperature as a result of increased WUE under the elevated CO₂. However, the gain would be lower under ETa than that estimated based on ETs due to higher evapotranspiration.     

缺氧环境下白细胞介素8通过Akt-STAT3通路提高骨髓间充质干细胞自噬和增殖能力

探讨缺氧环境下,白细胞介素8(Interleukin-8,IL-8)对人骨髓间充质干细胞(Human bone marrow mesenchymal stem cells,hBMSC)增殖和自噬能力的影响以及机制。在缺氧模型下,未进行刺激的hBMSC为缺氧对照组;以100μmol/L人IL-8蛋白刺激的MSC为IL-8组;若先添加50μmol/L MK2206(Akt蛋白抑制剂)培养30 min,然后再添加100μmol/L IL-8则为Akt抑制剂组,在正常条件下培养的MSC为正常对照组。利用Ed U细胞增殖实验、TUNEL细胞凋亡实验、Western blotting或ELISA等实验分别检测各组MSC细胞Ed U标记阳性细胞的数目、细胞凋亡、自噬蛋白(LC-3)和Akt/STAT3等蛋白的表达。相对于缺氧对照组和Akt抑制剂组,IL-8明显提高hBMSC增殖和细胞自噬,并降低hBMSC的凋亡率,IL-8组hBMSC的Akt、STAT3和VEGF等蛋白表达增高。结果表明,缺氧环境下,IL-8通过Akt-STAT3通路发挥对MSC的保护作用,对保护MSC抗缺血缺氧性损伤,促进MSC在再生医学中应用具有重要意义。     

水稻OsMS2基因在花药发育中的功能分析

拟南芥MS2(MALE STERILITY 2)是一个调控花药花粉发育的关键基因。水稻OsMS2(Os03g07140)基因与拟南芥MS2的序列具有高度同源性。利用RNA干扰技术研究OsMS2基因在水稻花药发育过程中的功能。与野生型水稻相比, 转基因 植株营养生长阶段正常, 但雄性育性降低。转基因植株雄性育性降低与RNA干扰引起的OsMS2基因表达水平降低有关。进一步对转基因植株花药进行细胞学观察, 结果表明OsMS2基因表达水平的降低导致绒毡层细胞退化延迟, 小孢子壁的形成出现异常。扫描电镜观察结果显示, 小孢子壁光滑, 不能形成正常的外壁。以上结果表明OsMS2基因在水稻花药发育过程中起重要作用。     

侧脑室注射心房钠尿肽对大鼠室旁核单位放电...

We have applied microelectrode technique to record 118 spontaneously firing units from the hypothalamus in rats. Detection of the recording sites showed that 84 were in the paraventricular nucleus (PVN) and 34 were near the PVN (near-PVN). After intracerebroventricular (i.c.v.) administration of atrial natriuretic polypeptide (ANP), 91% (P less than 0.005) of the PVN neurones and 71% (P greater than 0.05) of near-PVN neurones sensitive to ANP showed a significant decrease in spontaneously firing rate. After i.c.v. administration of hypertonic NaCl solution, 64.7% (P less than 0.005) of the PVN neurones and 61.1% (P greater than 0.05) of near-PVN neurones showed a significant increase in firing rate. The results indicate that i.c.v. administration of ANP profoundly inhibits the electrical activity of the PVN neurones, but hypertonic NaCl solution markedly stimulates the PVN neurones.     

OsGRF4 controls grain shape,panicle length and seed shattering in rice

Traits such as grain shape, panicle length and seed shattering, play important roles in grain yield and harvest. In this study, the cloning and functional analysis of PANICLE TRAITS 2 (PT2), a novel gene from the Indica rice Chuandali (CDL), is reported. PT2 is synonymous with Growth‐Regulating Factor 4 (OsGRF4), which encodes a growth‐regulating factor that positively regulates grain shape and panicle length and negatively regulates seed shattering. Higher expression of OsGRF4 is correlated with larger grain, longer panicle and lower seed shattering. A unique OsGRF4 mutation, which occurs at the OsmiRNA396 target site of OsGRF4, seems to be associated with high levels of OsGRF4 expression, and results in phenotypic difference. Further research showed that OsGRF4 regulated two cytokinin dehydrogenase precursor genes (CKX5 and CKX1) resulting in increased cytokinin levels, which might affect the panicle traits. High storage capacity and moderate seed shattering of OsGRF4 may be useful in high‐yield breeding and mechanized harvesting of rice. Our findings provide additional insight into the molecular basis of panicle growth.