高温胁迫下外源褪黑素对黄瓜幼苗活性氧代谢的影响

以黄瓜品种‘津春4号’为试材,用叶面喷施的方法,研究了高温胁迫条件下外源褪黑素(melatonin,MT)对黄瓜幼苗活性氧（ROS）代谢的影响.结果表明：外源MT能显著降低高温胁迫下黄瓜叶片超氧阴离子自由基（O₂^-.）产生速率、过氧化氢（H₂O₂）含量、电解质漏渗率（relative electric conductivity, REC）及丙二醛(MDA)含量,增强黄瓜幼苗叶片中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性,提高抗坏血酸（AsA）、谷胱甘肽（GSH）及可溶性蛋白质含量.说明MT预处理能抑制高温胁迫条件下黄瓜幼苗体内ROS的产生,提高抗氧化酶系的活性及抗氧化物质的含量,降低膜质过氧化水平,保护脂膜的完整性,减少电解质的外渗,减轻高温胁迫对幼苗造成的伤害,提高幼苗抗高温胁迫的能力.     

A robust two-way semi-linear model for normalization of cDNA microarray data

Background  

Normalization is a basic step in microarray data analysis. A proper normalization procedure ensures that the intensity ratios provide meaningful measures of relative expression values.     

Architecture and function of the lophophore in the problematic brachiopod Heliomedusa orienta (Early Cambrian, South China)

The detailed structure of the lophophore is a key diagnostic character in the definition of higher brachiopod taxa. The problematic Heliomedusa orienta Sun and Hou, from the Lower Cambrian Chengjiang Lagerstätte of Yunnan, southwestern China, has a well-preserved lophophore, which is unlike that of any known extant or extinct brachiopods. Based on a comparative study of lophophore disposition in H. orienta and the extant discinid Pelagodiscus atlanticus, the in- and excurrent pattern and shell orientation of H. orienta are described and discussed. Reconstructions of lophophore shape and function are based on numerous specimens and comparison with P. atlanticus. The lophophore is composed of a pair of lophophoral arms that freely arch posteriorly rather than coiling anteriorly as commonly seen in fossil and recent lingulids. The lophophore is attached to the dorsal lobe of the mantle; it has neither calcareous nor chitinous supporting structures, and is disposed symmetrically on either side of the valve midline. The mouth can be inferred to be located at the base of the two brachial tubes, slightly posterior to the anterodorsal projection of the body wall. The lophophoral arms bear laterofrontal tentacles with a double row of cilia along their lateral edge, as in extant lingulid brachiopods. The main brachial axes are also ciliated, which presumably facilitated transport of mucous-bound nutrient particles to the mouth. The unique organization of the lophophore in Heliomedusa is not like any known fossil and living brachiopods. This clearly demonstrates that H. orienta is not a member of any crown group. It is here considered as a member of the brachiopod stem group, which challenges recent interpretations of a close discinid affinity.     

种植条件下海滨盐土理化性状与生物学特征

以苏北海滨盐土种植实验区7个不同特征的地块为对象,研究了海滨盐土基本理化性状及其生物学特征的季节变化,以及其与植物种植和植被条件的关系.结果表明:海滨盐土的土壤性状随种莓年限和植被状况的不同有较大的变异性,种植耐盐植物地块平均土壤电导率(0.95 dS·m-1)低于自然植被地块(2.77 dS·m-1),但部分地块电导率水平较种植前有所升高;土壤肥力普遍较低,水解性氮含量平均低于50 mg·kg-1,有效磷含量(除施肥地块)平均低于3 mg·kg-1,有机质含量低于1%,种植耐盐植物地块因施肥而有所改善.土壤电导率和养分水平是影响盐土植被生长与分布的主要因素,前者尤为关键;土壤氮磷含量与微生物数量密切相关.不同植被和干扰状况下土壤性状的季节变化差异明显,植被盖度高、人为干扰少的土壤环境相对稳定,反之则波动剧烈.     

Lactose Induction Increases Production of Recombinant Keratinocyte Growth Factor-2 in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Recombinant human keratinocyte growth factor-2 (rhKGF-2) has previously been expressed in Escherichia coli using isopropyl-β-d-thiogalactopyranoside (IPTG), a non-metabolizable and expensive compound, as the inducer. In order to determine whether IPTG could be replaced with the cheap and natural lactose to induce rhKGF-2 expression, we examined the expression of rhKGF-2 in flask culture and 30-l fermentation using lactose as the inducer. The optimized fermentation induced with lactose resulted in 1,382 g of cell mass, corresponding to a 84% enhancement in cell mass compared with IPTG induction. While the expression level of rhKGF-2 induced with lactose was comparable to that induced with IPTG, the solubility of target protein was increased by lactose induction than by IPTG induction. The recombinant protein was further purified by cation exchange and heparin-affinity chromatography. 255 milligrams of pure rhKGF-2 was achieved per liter culture by lactose induction, 52% higher than that obtained by IPTG induction. A preliminary biochemical characterization of purified rhKGF-2 was performed by Western blotting and mitogenic activity analysis, and the results demonstrated that the purified lactose-induced rhKGF-2 could react with anti-human KGF-2 antibody and stimulate the proliferation of FGFR2-IIIb-transfected mouse BaF3 cells as IPTG-induced rhKGF-2 could do.     

PTOV1 is associated with UCH-L1 and in response to estrogen stimuli during the mouse oocyte development

To investigate the biological significance of ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) involvement in oocyte maturation, we screened for proteins that bound to UCH-L1 in mouse ovaries, and we found that the prostate tumor overexpressed-1 (PTOV1) protein was able to bind to UCH-L1. PTOV1 is highly expressed in prostate cancers and considered as a potential marker for carcinogenesis and the progress of prostate cancer. It was reported that PTOV1 plays an important role in cell cycle regulation, but its role in mammalian oocyte development and meiosis is still unclear. In this paper, it was found that the expression levels of PTOV1 in mouse ovaries progressively increased from prepubescence to adulthood. And we found by immunohistochemistry that PTOV1 spreaded in both the cytoplasm and nuclei of oocytes during prepuberty, but in normal adult mouse oocytes, it concentrated not only in nuclei but also on the plasma membrane, though in some oocytes with abnormal shapes, PTOV1 did not display the typical distribution patterns. In granulosa cells, however, it was found to locate in the cytoplasm at all the selected ages. In postnatal mouse ovaries (28 days), estradiol treatment induced the adult-specific distribution pattern of PTOV1 in oocytes. In addition, UCH-L1 was shown to be associated with CDK1, which participated in the regulation of cell cycle and oocyte maturation. Therefore, we propose that the distribution changes of PTOV1 are age-dependent, and significant for mouse oocyte development and maturation. Moreover, the discovery that PTOV1 is associated with UCH-L1 in mouse oocytes supports the explanations for that UCH-L1 is involved in oocyte development and maturation, especially under the regulation of estrogen.     

乳腺生物反应器表达的重组人乳清白蛋白的高效分离纯化

利用乳腺生物反应器高效地表达重组人乳清白蛋白,但是目标产物分离纯化的难度较大。通过分子模拟计算比较待分离原料中主要蛋白组分的物化性质,包括表面电势和表面疏水性,在此基础上设计了高分辨率、快速的分离纯化工艺。通过硫酸铵沉淀的正交试验条件优化,有效地去除了干扰层析精制过程的IgG杂质,提高了后续疏水层析的稳定性,从而成功地分离开目标蛋白及与其同源的牛乳清白蛋白杂质,得到纯度>95%的rHLA纯品,工艺回收率48.6%。乳糖合成活性和圆二色谱检测结果表明,纯化rHLA具有调节β-1,4-半乳糖苷转移酶活性和天然的空间结构。     

MicroRNA与胶质瘤的分子病理特征研究进展

MicroRNAs（miRNAs）是一类非编码的内源性小RNA分子,通过调节mRNA的稳定性及蛋白翻译过程控制基因表达,从而发挥促癌或抑癌作用;研究表明,在胶质瘤的发生、进展、侵袭过程中,伴随发生了许多分子病理特征的改变,这一过程中miRNAs发挥着重要作用,本文就此方面研究进展进行综述。     

Aluminium resistance requires resistance to acid stress: a case study with spinach that exudes oxalate rapidly when exposed to Al stress

Spinach is a vegetable with a high oxalate concentration in its tissues. Oxalate efflux from spinach (Spinacia oleracea L. cv. Quanneng) roots was rapidly stimulated (within 30 min) by aluminium (Al) treatment. The efflux was constant within 6 h, but increased with increasing Al concentration. The efflux was confined to the root tip (0-5 mm), which showed a 5-fold greater efflux than the root zone distal to the tip (5-10 mm). Oxalate efflux could not be triggered by treatment with the trivalent cation lanthanum or by phosphorus deficiency, indicating that the efflux was specific to the Al treatment. All this evidence suggested that spinach possesses Al-resistance mechanisms. However, spinach was found to be as sensitive to Al toxicity as the Al-sensitive wheat line ES8, which had no Al-dependent organic acids efflux. The Al accumulated in the apical 5 mm of the roots of spinach which was also similar to that in the Al-sensitive wheat after 24 h treatment with 50 microM AlCl(3), indicating a non-exclusion mechanism. In addition, root elongation in spinach was significantly inhibited at pH 4.5, compared with that at pH 6.5. Based on this evidence, it is concluded that the sensitivity to acid stress in spinach could mask the potential role for oxalate to protect the plant roots from Al toxicity.