广西植物研究所科技开发的十年

近十年来,广西植物研究所的科技开发工作得到了迅速的发展,科技开发的实力不断增强,形式多元化、多渠道,水平也不断得到提高。本文概括地叙述了广西植物研究所科技开发工作的历史、现状以及今后发展的建议。     

Transformation of maize embryogenic calli mediated by ultrasonication and regeneration of fertile transgenic plants

An insecticidal protein gene isolated fromBacillus thuringiensis was transferred into maize by using ultrasonication. The fertile transgenic plants and their progeny were obtained. The Southern hybridization results indicated that the foreign gene had integrated into the maize genome. It has been found that the acoustic intensity and the duration of treatment are the important parameters influencing transformation efficiency by ultrasonication. The maximum relative transformation frequency of 34.1 % was achieved after 30 min of sonication at 0. 5 W/cm² acoustic intensity. With appropriate parameters the ultrasonication can make a number of micropores formed on the cell surface and minimize the treatment damage to the foreign DNA molecules, thus facilitating the DNA molecules to enter the cells. Project supported by “863” State High Technology Development Program.     

大肠杆菌原核增强子样M片段的进一步研究

阐明基因转录调控机理一直是分子生物学的研究热点。增强子是广泛存在于真核、病毒及原核生物中的重要的调控元件之一,它通过与各种调控蛋白因子相互作用而发挥其转录增强调节功能。 原核转录增强子的发现是近几年的事,有关研究报道远少于真核和病毒增强子。1989年,潘卫、吴     

正中神经体感诱发电位P_（22）波的来源及其对偏瘫患者手功能恢复的预测价值

使用耳垂参考电极,在顶、额颅表同步描记正中神经体感诱发电位（Ｍ－ＳＥＰ）,可记录到Ｐ＿(１４)、Ｐ＿(２２)、Ｎ＿(３０)和Ｐ＿(１４)、Ｎ＿(２０)、Ｐ＿(２２)两组波。动物实验观察发现,局部麻醉家兔中央前回后,Ｐ＿(２２)波消失;麻醉顶叶对Ｐ＿(２２)波幅无明显影响,证明Ｐ＿(２２)是与手运动相关联的波。分析经ＣＴ证实的３９名偏瘫患者,观察经物理治疗前后Ｐ＿(２２)、Ｎ＿(２０)与手肌力的对应关系,发现Ｐ＿(２２)对判断手功能的预后是个很敏感的指标,若患者Ｐ＿(２２)波分化不清或消失,是手功能预后不好的信号,因此,Ｐ＿(２２)波可考虑作为临床判断手功能预后的电生理指标之一。     

Disuccinimidyl suberate cross-linked hemoglobin as a novel red blood cell substitute

Disuccinimidyl suberate (DSS) intramolecularly cross-linked hemoglobin (Hb) was developed as a novel red blood cell substitute. A multi-angle laser light scattering detector coupled with size exclusion HPLC was applied to determine the molecular weight of the modified Hb. SDS-PAGE was also used as a complement. It was proved that 83.8% of the product was intramolecularly cross-linked Hb with weight-average molecular weights (Mw) of 67.5 kD, 12% was dimeric Hb with Mw of 146.6 kD, and 4.2% was trimeric Hb with Mw of 306.4 kD. The tetramer structure of the cross-linked Hb was stable as shown in size-exclusion chromatography using a mobile phase containing 1 mol/L MgCl2. Analysis by LC-MS demonstrated that the reaction of DSS with Hb mainly took place between the twoα subunits within a Hb molecule, resulting in stabilization of the tetramer structure. However, the cross-linking was not site-specific. The P50 of the cross-linked Hb decreased from 21.8 mmHg to 14.3 mmHg, and the Hill coefficient decreased from 2.22 to 1.41. Result of isoelectric focusing showed that the pI of DSS cross-linked Hb was in the range of 4.6-5.2, similar to that of serum albumin. The safety of DSS cross-linked Hb was favored by animal tests on rats and guinea pigs. Exchange transfusion experiment with DSS cross-linked Hb using rats as a model indicated no pressor effect or other significant side effects. The characteristics and properties of DSS cross-linked Hb were also compared with that of diaspirin cross-linked Hb reported in the literature.     

MicroRNA-30 inhibits antiapoptotic factor Mcl-1 in mouse and human hematopoietic cells after radiation exposure

We previously reported that microRNA-30 (miR-30) expression was initiated by radiation-induced proinflammatory factor IL-1β and NFkB activation in mouse and human hematopoietic cells. However, the downstream effectors of miR-30 and its specific role in radiation-induced cell death are not well understood. In the present study, we evaluated effects of radiation on miR-30 expression and activation of intrinsic apoptotic pathway Bcl-2 family factors in in vivo mouse and in vitro human hematopoietic cells. CD2F1 mice and human CD34+ cells were exposed to different doses of gamma-radiation. In addition to survival studies, mouse blood, bone marrow (BM) and spleen cells and human CD34+ cells were collected at 4 h, and 1, 3 and 4 days after irradiation to determine apoptotic and stress response signals. Our results showed that mouse serum miR-30, DNA damage marker γ-H2AX in BM, and Bim, Bax and Bak expression, cytochrome c release, and caspase-3 and -7 activation in BM and/or spleen cells were upregulated in a radiation dose-dependent manner. Antiapoptotic factor Mcl-1 was significantly downregulated, whereas Bcl-2 was less changed or unaltered in the irradiated mouse cells and human CD34+ cells. Furthermore, a putative miR-30 binding site was found in the 3′ UTR of Mcl-1 mRNA. miR-30 directly inhibits the expression of Mcl-1 through binding to its target sequence, which was demonstrated by a luciferase reporter assay, and the finding that Mcl-1 was uninhibited by irradiation in miR-30 knockdown CD34+ cells. Bcl-2 expression was not affected by miR-30. Our data suggest miR-30 plays a key role in radiation-induced apoptosis through directly targeting Mcl-1in hematopoietic cells.     

Evaluation of N-acetyl-S-(p-chlorophenylcarbamoyl)cysteine as an irreversible inhibitor of mammalian thioredoxin reductase1

Context: Thioredoxin reductase (TrxR) is up-regulated in a number of human malignant cells and becomes a promising target for anticancer drug development.

Objective: To evaluate N-acetyl-S-(p-chlorophenylcarbamoyl)cysteine (NACC), a potent anticancer agent against melanoma, as an inhibitor of mammalian TrxR1.

Material and methods: The mechanism of inhibition against TrxR1 was investigated using substrate protection, dialysis and liquid chromatography–tandem mass spectrometry.

Results: NACC inhibits TrxR1 in a time and concentration dependent manner. The K_i and k_inact of NACC against TrxR1 were determined to be 80?μM and 0.178?min^?1, respectively. The inhibition occurred only in the presence of NADPH and persisted after extensive dialysis. The tandem mass spectrometric analysis demonstrated that the selenocysteine rather than cysteine residue at the active site was p-chlorophenyl carbamoylated by NACC. Inhibition of intracellular TrxR by NACC in cultured melanoma cells was observed.

Discussion and conclusion: NACC which irreversibly inhibits TrxR1 by forming a covalent bond with selenocysteine can be an effective tool in the study of TrxR1.     

The Effect of an Acute Bout of Moderate-Intensity Aerobic Exercise on Motor Learning of a Continuous Tracking Task

Introduction

There is evidence for beneficial effects of acute and long-term exercise interventions on several forms of memory, including procedural motor learning. In the present study we examined how performing a single bout of continuous moderate intensity aerobic exercise would impact motor skill acquisition and retention in young healthy adults, compared to a period of rest. We hypothesized that exercise would improve motor skill acquisition and retention, compared to motor practice alone.

Materials and Methods

Sixteen healthy adults completed sessions of aerobic exercise or seated rest that were immediately followed by practice of a novel motor task (practice). Exercise consisted of 30 minutes of continuous cycling at 60% peak O₂ uptake. Twenty-four hours after practice, we assessed motor learning with a no-exercise retention test (retention). We also quantified changes in offline motor memory consolidation, which occurred between practice and retention (offline). Tracking error was separated into indices of temporal precision and spatial accuracy.

Results

There were no differences between conditions in the timing of movements during practice (p = 0.066), at retention (p = 0.761), or offline (p = 0.966). However, the exercise condition enabled participants to maintain spatial accuracy during practice (p = 0.477); whereas, following rest performance diminished (p = 0.050). There were no significant differences between conditions at retention (p = 0.532) or offline (p = 0.246).

Discussion

An acute bout of moderate-intensity aerobic exercise facilitated the maintenance of motor performance during skill acquisition, but did not influence motor learning. Given past work showing that pairing high intensity exercise with skilled motor practice benefits learning, it seems plausible that intensity is a key modulator of the effects of acute aerobic exercise on changes in complex motor behavior. Further work is necessary to establish a dose-response relationship between aerobic exercise and motor learning.