木聚糖酶活力测定条件研究

用DNS法测木聚糖酶活力,分析测定条件对测定结果的影响。结果表明,在不同的条件下测定酶活力会得到不同的木聚糖酶活力测定值。其中,酶液用量、酶解反应的时间对测定结果的影响较大,酶液稀释度、DNS显色时间、DNS的用量,对测定结果也有一定的髟响。测定木聚糖酶活力的适宜条件为：酶液量/1％木聚糖液量1/9(V／V);酶解反应时间：10min;DNS用量2—2．5ml;DNS显色时间2—5min。     

饲养条件对黄粉虫幼虫生长及存活的影响

采用5因素2次正交旋转组合设计,以黄粉虫幼虫饲养过程中饲养温度(X1)、相对湿度(X2)、虫粪筛除频率(X3)、饲养密度(X4)以及饲料含水量(X5)5因素为参试因素,考查它们对黄粉虫高龄幼虫的生长及存活的影响,建立并进行了简化得到了以黄粉虫幼虫增重率及死亡率为目标函数的回归模型：Y增＝127．5079 18．6559x5 2．7894x3x4-2．3854x3x5-3．0594x1^2 1．824lx3^2-3．8559x5^2;y死＝1．7459 0．4l08x1 0．0975x2 0．9025x4 0．3442x5 0．0834x1^2 0．3060x4^2-0．2623x5^2。分析结果表明：影响黄粉虫幼虫生长后期增重及死亡的主要因素分别为饲料含水量和饲养密度;饲料含水量和温度对黄粉虫增重有着重要的影响,饲养密度、温度、饲料含水量对黄粉虫的死亡有着重要的影响,其影响均达1％或5％显著水平;推荐的饲养条件为：温度24—27℃、相对湿度64％一70％、筛粪频率2—4d／次、饲养密度0．42-0．49g／cm^2、饲料含水量l3．48％-l7．48％。     

青藤碱对人外周血CD4^＋T淋巴细胞增殖和细胞内Ca^2＋浓度影响的体外研究

目的探讨青藤碱（SIN）对人外周血CD4^＋T淋巴细胞增殖和细胞内Ca^2＋浓度的体外影响及其效应机制。方法建立体外人外周血CD4^＋T淋巴细胞模型,分别作以下处理：（1）空白对照组;（2）环孢素（CsA）组（50ng／m1）;（3）低浓度SIN组（10μmol／1）;（4）中浓度SIN组（200μmol／1）;（5）高浓度SIN组（1000μmol／1）。分别用MTT比色法和流式细胞术（FCM）检测CD4^＋细胞增殖和细胞内Ca^2＋荧光强度。采用方差分析比较各组间差异的统计学意义。结果（1）高浓度SIN组、中浓度SIN组与其他各组细胞增殖抑制率存在差异（F=1444．228,P=0．000）;（2）FCM检测细胞内Ca^2＋浓度结果：中浓度SIN组、高浓度SIN组与其他各组差异有统计学意义（F=479．055,P=0．000）;（3）经SIN处理后,人外周血CD4^＋T淋巴细胞增殖抑制率和细胞内Ca^2＋浓度之间存在负相关r=-0．836,P=0．005）。结论SIN能浓度依赖性地抑制人外周血CD4^＋T淋巴细胞增殖和细胞内Ca^2＋浓度升高,人外周血CD4^＋T淋巴细胞增殖抑制率和细胞内Ca^2＋浓度之间存在显著性负相关。     

构建羰基还原酶基因工程菌生物转化产l-麻黄碱

以筛选得到的Morganella morganii J-8细菌的基因组为模板,通过PCR扩增得到目的基因mdlh2。核苷酸序列测定结果表明,基因全长1046bp。以pET28a（＋）为表达载体,构建重组质粒pET28a（＋）-mldh2,并在E．coli BL21（DE3）中表达。利用表达产物进行生物转化,发现其具有催化底物1-苯基-2-甲氨基丙酮（简称MAK）产l-麻黄碱的活力。进一步考察了诱导时间和IPTG浓度对重组菌表达的羰基还原酶的影响,37℃下用0．5mmoL／L的IPTG诱导4h,重组羰基还原酶的酶活达到0．2U／mg蛋白,转化液中l-麻黄碱质量浓度达到45mg／L。     

灵芝EIM-40漆酶的分离纯化及酶学性质

采用冻干浓缩、（NH4）2S04盐析、HiTrapphenyl（FF）疏水层析和QSepharose FastFlow离子交换层析对灵芝EIM-40发酵液进行分离纯化,获得纯化漆酶,纯化倍数为14．6,回收率为5．3％。SDS-PAGE银染的结果为单一条带,相对分子质量约为6．53×104。以愈创木酚和2,2-联氮-二（3-乙基-苯并噻唑-6-磺酸）二铵盐（ABTS）为催化底物进行酶学性质研究,最适pH分别为4．8和4．5,最适温度分别为55和50℃,2种底物在pH4．0。5．0范围内,温度低于50℃时,酶的稳定性都很好。以愈创木酚为底物,Km=645．0umol／L;以ABTS为底物,Km=22．2txmol／L。Cu2＋对该酶起激活作用,Fe2＋、Ca2＋、Ba2＋则完全抑制酶的活性。     

PS1沼泽红假单胞菌对集约化对虾养殖废水的净化作用

应用光合细菌PS1——沼泽红假单胞菌（Rhodopseudomonas palustris）净化集约化对虾养殖废水,探讨不同温度、不同菌浓度下PS1对养殖废水的净化效果。研究结果表明：PS1可有效降低对虾养殖废水中的COD、NH4^＋-N、NO3^-N、PO4^3--P,但对NO2^--N无降解效果,反而使之持续升高;PS1对养殖废水96h的降解率受温度和添加菌浓度的影响显著（P〈0．05）。当温度为26℃时,PS1对废水的降解活性较好;不同菌浓度组间的净化效果差异明显（P〈0．05）,综合净化效果,以12．5×10^5 CFU／ml的菌浓度为宜。     

生物催化法合成6-氰基-（3R，5R）-二羟基己酸叔丁酯

利用E.coli BL21／pCDFDuet-gdh—cr-X共表达全细胞催化6-氰基-（5R）-羟基-3-羰基己酸叔丁酯不对称还原合成6-氰基-（3R,5R）-二羟基已酸叔丁酯。结果表明：在菌体用量4．85g/L、葡萄糖与底物质量浓度比为1：1、温度28℃、pH7．0条件下,80．0g／L6-氰基-（5R）-羟基-3-羰基己酸叔丁酯生物还原2h后,底物转化率可达99．0％,产物d.e．值大于99．5％。在考察范围内,NADP^＋用量对催化效率无显著作用。     

黑曲霉An-76木聚糖酶系的酶学研究

用分子筛和离子交换等色谱分离技术,由黑曲霉An-76的木聚糖酶系中分离纯化到一种β-木糖苷酶(βx)和三种内切-β-木聚糖酶组分(EX1,EX 2,EX 3)。这几种酶均达到凝胶电泳纯和聚焦电泳纯。用凝胶过滤方法测得3X的分子量为147000,用凝胶电泳法测得EX1、EX2和EX3的分子量分别为2 3000、22000和41 000;βX、EX1、EX2和EX 3的等电点分别为4．6、5．9、4．1和3．9。本文还研究了各种酶的最适反应温度和PH、酶的热稳定性和pH稳定性;研究了金属离子和巯基试剂对酶活力的影响、动力学参数、氨基酸组成、底物持异性和反应产物等。各酶组份不具有分解纤维素的交叉活力。巯基试剂能完全抑制卢βX活力,其活力丧失可被半胱氨酸恢复。     

高效液相色谱法在脱氧核糖核酸酶解动力学研究中的应用

为了更好地对脱氧核糖核酸酶解动力学过程进行研究,建立脱氧核糖核酸（DNA）酶解液中4种脱氧核苷酸（腺嘌呤脱氧核苷酸（dAMP）、鸟嘌呤脱氧核苷酸（dGMP）、胞嘧啶脱氧核苷酸（dCMP）、胸腺嘧啶脱氧核苷酸（dTMP））的高效液相测定方法,能将酶解液中4种脱氧核苷酸完全分离并准确定量。在此基础上,对DNA酶解的动力学进行初步研究,其反应机理为不存在底物和产物抑制的双底物顺序反应,动力学方程为x=1／bin（1＋abt）（其中a=0．3723p0—0．974;b=-0．0493p0^2＋1．1150p0-1．1103）,该方程可以很好地描述DNA酶解过程,误差仅为3．31％.     

链霉菌Strz-2胞外木聚糖酶的纯化和固定化研究

为探讨木聚糖酶被固定化后的酶活力变化 ,采用盐析、离子交换和分子筛层析方法对链霉菌胞外木聚糖酶进行了纯化 ,并采用DNS方法对固定化酶的性质进行了研究。结果如下 :粗酶液被纯化了 30 .5倍 ,比活力达 4 5 7.5 ,活力回收 4 2 .6 %。纯化后的酶固定在戊二醛交联的壳聚糖上 ,残活力为 4 1.8%。固定化酶的最适pH为 6 .0 ,最适温度为 5 5℃ ,且固定化酶在 6 5 -75℃活力都较高。该酶的耐热性比较强 ,固定化酶热稳定性优于原酶 ;以木聚糖为底物 ,固定化酶的表观米氏常数为 0 .83× 10 -2g/L。因此 ,固定化的木聚糖酶优于原酶     

Characteristics of the membranes of the pellicle of the ciliatePseudomicrothorax dubius

Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.     

The early development of the tail and the transformation of the shape of the nucleus of the spermatid of the domestic fowl,Gallus gallus

Summary The differentiation of the spermatid, especially in reference to the formation of the flagellum, and transformation of the shape of the nucleus was investigated in the domestic fowl.In the early stage of the spermatid, a prominent Golgi apparatus appears around the centrioles. The Golgi vesicles then surround the axial-filament complex which develops from the distal centriole. These vesicles fuse to form continuous membrane at the earliest stage of flagellar formation, and in the succeeding stage Golgi lamellae are attached to the plasma membrane of the developing flagellum. From these observations, it is assumed that Golgi apparatus may be a source of the membrane system of the flagellum.The microtubules distributed around the nucleus form the circular manchette. The anterior region of the nucleus with the manchette is cylindrical in shape and the posterior region without it remains irregular in shape. When the circular manchette has been completed, the whole nucleus acquires a slender cylindrical shape. The circular manchette then changes into the longitudinal manchette. The nuclei of spermatids without a longitudinal manchette are abnormal in shape. In view of these observations it is assumed that the nuclear shaping of the spermatid may be accomplished by circular manchette and the maintenance of shape of the elongated nucleus by longitudinal manchette.The authors wish to thank Mr. Takayuki Mori for his helpful suggestions and technical advices     

Characterization of the composition of the aqueous humor and the vitreous body of the eye of the frog Rana temporaria L

This study aimed to analyze the aqueous humor (AH) and the vitreous body (VB) of the eye of the adult frog Rana temporaria L. as a representative species of amphibians, which lead a semi-terrestrial life. The presence of collagen, albumin, uric acid and electron donors was shown in both media; however, there are slight differences in their concentrations. To determine collagen, a spectral-fluorescent probe, cyanine dye, was used. The presence of collagen in AH of the frog was found at the first time. The total content of electron donors (ascorbic and uric acids, tryptophan, and tyrosine) in VB and HA was roughly estimated at ~ 1.5 × 10^− 4 mol/L. Both VB and AH absorb light in similar UV regions. The total protein and albumin contents in AH were found to be somewhat higher than those in VB. The uric acid content was at an equally low level in both intraocular media. It is supposed that the similarity of VB and AH compositions shown in this work is due to some exchange between VB and AH contents in the course of accommodation. The role of intraocular fluids in physiological functions of the eye and in protecting the retina against UV light is discussed.     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418