K、Na、Ca、Mg 4种元素在疏叶骆驼刺体内含量分布特点的研究

 此项工作在新疆平原荒漠区盐化草甸带进行。研究结果显示出K、Na、Ca、Mg 4种元素在植物体内不同器官的含量分布特点和各个器官中不同元素间的含量关系。同时表明这4种元素在植物体不同器官中具有不同的作用。对于K、Na元素,地上部器官尤其叶片中含量水平反映出器官具有较强的留K排Ns的选择性元素的分配机制。     

艾滋病合并隐球菌感染17例尸检材料的临床病理学研究

在１５１例艾滋病尸检材料中发现１７例合并隐球菌感染,均经病理学确诊,患者男１５名,女２名,平均４３．６岁。１２例发生脑膜炎、肺炎和淋巴结炎各７例,尚见脾（６例）、肾（５例）等器官受累。９例为播散性感染。病变为慢性肉牙肿性,其中见有隐球菌。本文描述隐球菌性脑膜炎、肺炎等临床病理学表现,并讨论其病变特征与病理诊断问题。     

LDL受体基因cDNA的RT－PCR分离、克隆及其在RFLP中的应用

利用ＲＴ－ＰＣＲ技术分离低密度脂蛋白受体基因ｃＤＮＡ,将长为２６０５ｂｐ的ｃＤＮＡ插入质粒ｐＪＮ６,并经全序列测定证实,该序列与已报道序列相比,存在两个变异碱基,即第７５４位Ｃ→Ｔ,和１６５４位的Ｇ→Ａ,这两个变异碱基并不改变编码的氨基酸,利用ＬＤＬ受体基因ｃＤＮＡ中的ＣｌａⅠ片段作为探针,检测到ＬＤＬ受体基因上外显子８的ＳｔｕⅠ位点是个限制性片段长度多态性位点。所克隆的ｃＤＮＡ含有可译框架的全部密码,因此可作为基因表达材料。     

乳链菌肽的分离纯化和部分生物学性质

用乳酸链球菌ＳＭ５２６进行乳链菌肽的发酵生产,产量为４０～５０ｍｇ／ｌ．经中空纤维超滤器超滤,非极性大孔吸附树脂ＸＡＤ－２层析,ＣＭ－ＳｅｐｈａｄｅｘＣ－２５层析和ＳｅｐｈａｄｅｘＧ－５０层析纯化了该肽。ＳＤＳ－ＰＡＧＥ表明达均一,ＲＰ－ＨＰＬＣ表明其纯度不低于９５％。ＳＤＳ－ＰＡＧＥ测其Ｍｒ约为３６００,用ＩＥＦ测其等电点为９．５．酸性条件下稳定且抗热;对胰蛋白酶、胃蛋白酶和木瓜蛋白酶不敏感,但对α－胰凝乳酶和蛋白酶Ｋ敏感。乳链菌肽对多种革兰氏阳性菌有强烈的抑制作用;以枯草杆菌和金黄色葡萄球菌为指示菌,其作用方式是杀菌。     

白细胞介素－2的PEG化

用自制的氨基ＰＥＧ化试剂ｒＩＬ－２进行化学修饰,研究了试剂浓度,溶液ｐＨ,反应时间等与ＰＥｃａ－ｒＩＬ－２产率及ＩＬ－２活性保持之间的关系,建立了一套获得稳定修饰度的ＰＥＧ－ｒＩＬ－２的方法。研究发现,反应时间跟修饰度关系不大;溶液ｐＨ对修饰度有一定的影响,中性ｐＨ以上反应都可进行;而试剂浓度直接决定修饰度的高低,过量越多,修饰度越高,而生物活性保留也越低;但低度修饰,对活性几乎没有影响,可保留活性在９５％左右。     

Development of Media and Automated Liquid Fermentation Methods to Produce Desiccation-Tolerant Propagules ofTrichoderma harzianum

A suitable medium was developed from modified Richard's medium plus V8 juice (RM8) to produce high levels of desiccation-tolerant conidia ofTrichoderma harzianumstrain 1295-22. The addition of 9% (v/v) glycerol to RM8 improved both biomass production and desiccation tolerance of the conidia ofT. harzianum.This medium was then used in a laboratory scale fermenter (1.5 liter) to determine optimal operating conditions. The optimal temperature for conidial production and desiccation tolerance improvement in the fermenter was 32°C when dissolved oxygen was maintained at 50% saturation of air, and the stirring rate was 1000 revolutions per minute. The initial water potential of the medium (with 9% glycerol) was −3.7 MPa, the pH was 6, and neither was controlled during fermentation. Changes in medium pH and dissolved oxygen were associated with the stages of morphological development and conidiation. The pH of the medium decreased concurrently with germ-tube elongation and mycelium development and then increased to 6.0–6.2 at phialide formation. Intensive conidiation occurred at pH 6.3–6.5 and reached its maximal level at 6.9–7.1. Changes in pH values could be used as indicators to monitor the morphological development and conidiation ofT. harzianumduring fermentation. The use of a 48-h-old culture inoculum, rather than conidial inoculum, to start fermentation reduced the time required to complete the shift from vegetative growth to phialide formation. Intensive conidiation occurred immediately after the addition of culture inoculum and reached maximum levels within 68 h of fermentation. Dry weight of biomass increased with the duration of fermentation and was greatest at 96 h. However, no improvements in conidia/gram and CFU/gram were achieved after 72 h of fermentation. The desiccation tolerance of conidia harvested at 72 or 96 h was significantly (P = 0.05) greater than that of conidia harvested at 48 h of fermentation. Results obtained from this study could be used for further scale-up of the fermentation process.     

Nitrate Nonutilizing Mutants and Vegetative Compatibility Groups in Fusarium poae

Nitrate nonutilizing (nit) mutants were recovered from 24 isolates of Fusarium poae and used to force heterokaryons between these isolates and to determine vegetative compatibility. Between 30 and 90% of the mycelial blocks, cultured on medium containing chlorate, produced nit mutants. The amount of chlorate in the medium altered the frequency and spectrum of nit mutants recovered. Most of the mutants (63%) had lesions at a nitrate reductase structural locus (nit1). Another 30% were mutants at one or more loci that control the production of a molybdenum-containing cofactor necessary for nitrate reductase activity (NitM). A few (6%) of the mutations occurred in a regulatory gene specific for the nitrate reduction pathway (nit3). Pairings between nit1 and NitM mutants were made on minimal medium containing nitrate as the sole nitrogen source. A mutant grows thinly unless it forms a complementary heterokaryon upon contact with another mutant. Heterokaryon formation was indicated by dense growth where the two mutant colonies touched. The 24 isolates could be divided into 13 nonoverlapping vegetative compatibility groups, suggesting that asexual exchange of genetic information within F. poae is subject to significant limitations.     

PLD activation in Chinese hamster ovary (CHO) cells transfected with PGF2α receptor cDNA

Pertussis toxin-insensitive GTP-binding protein was observed to be involved in prostaglandin F2α(PGF2α)-induced phosphoinositide metabolism in Chinese hamster ovary (CHO) cells transfected with PGF2α receptor cDNA (CHO-PGF2α·R cells) (Ito, S. et al. Biochem. Biophys. Res. Commun. 200: 756, 1994). In the present study, we investigated PGF2α-induced PLD activation in CHO-PGF2α·R cells. PLD activation was examined by measuring the production of [³H]phosphatidylbutanol ([³H]PBut), a specific product of the PLD-catalyzed transphosphatidylation reaction. PGF2α-induced [³H]PBut formation was concentration-dependent with the maximal level obtained at 1 μM PGF2α. The maximal [³H]PBut formation was observed at 2 min after addition of PGF2α. Depletion of extracellular Ca²⁺ with EGTA suppressed PGF2α-induced PLD activation by 50%. PKC inhibitors Ro31–8425 and calphostin C inhibited PGF2α-induced [³H]PBut formation by 50%. PTK inhibitors genistein and herbimycin A failed to inhibit PGF2α-induced PLD activation. A combination of maximal effective concentrations of PGF2α (1 μM) and PMA (100 nM) enhanced PLD activation in an additive manner. Pretreatment of the cells with PMA for 2 h down-regulated PKCα and decreased PGF2α-induced PLD activation. These results suggest that PLD activation by PGF2α is mediated by both PKC-dependent and -independent pathways and that PKCα is involved in the former pathway.     

Use of moving aeration membrane bioreactor for the efficient production of tissue type plasminogen activator in serum free medium

A moving aeration-membrane (MAM) bioreactor was employed for the production of 2 μg/mL of tissue type Plasminogen Activator (tPA) in serum free medium from normal human fibroblast cells. This system could maintain high cell density for long periods of steady state conditions in perfusion cultivation. Under normal operating conditions, shear stress was as low as 0.65 dynes/cm² at the agitation speed of 80 rpm. Even though cell density gradually decreased with increasing agitation speed, tPA production increased linearly with increasing shear stress within a moderate range. This culture system allowed production of 2 μg tPA/mL while maintaining a high cell density of 1.0×10⁷ viable cells/mL.