Enantioselective hydrolysis of oxazepam 3-acetate by esterases in human and rat liver microsomes and rat brain S9 fraction

Rates of hydrolysis of racemic and enantiomeric oxazepam 3-acetates (OXA) by esterases in human and rat liver microsomes and rat brain S9 fraction were compared. When rac-OXA was the substrate, esterases in human and rat liver microsomes were highly enantioselective toward (R)-OXA. In contrast, esterases in rat brain S9 fraction were highly enantioselective toward (S)-OXA. Hydrolysis rates of rac-OXA were highly dependent on the amount of esterases used. At 0.05 mg protein equivalent of esterases and 150 nmol of rac-OXA per ml of incubation mixture, the (R)-OXA was hydrolyzed 3.6-fold and 18.5-fold faster than (S)-OXA by rat and human liver microsomes, respectively. The specific activities (nmol of OXA hydrolyzed/mg microsomal protein/min) of liver microsomes in the hydrolysis of enantiomerically pure (R)-OXA were approximately 120 (rat) and 1,980 (human), and in the hydrolysis of enantiomerically pure (S)-OXA were 4 (rat) and 7 (human), respectively. In the incubation of rac-OXA with rat brain S9 fraction, (S)-OXA was hydrolyzed approximately 6-fold faster than (R)-OXA. Results also indicated an enantiomeric interaction in the hydrolysis of rac-OXA by esterases in rat and human liver microsomes; the presence of (R)-OXA stimulated the hydrolysis of (S)-OXA, whereas the presence of (S)-OXA inhibited the hydrolysis of (R)-OXA. In rat brain S9 fraction, the presence of (R)-OXA inhibited the hydrolysis of (S)-OXA, whereas the presence of (S)-OXA appeared to have stimulated the hydrolysis of (R)-OXA.     

Callus culture ofPterocladia capillacea (Rhodophyta) and analysis of cell wall polysaccharides

Calluses induced fromPterocladia capillacea have been kept in culture for more than three years. They exhibit a fast growth rate, owing to the release of single cells, which in turn develop into new callus. The effect of various media and culture conditions upon growth was investigated. In order to confirm the identity of the callus cells, a 0,45 mg incoculum was grown that yielded 15 g dried callus within six weeks. Polysaccharides from this material (5.5 g) were analysed by¹³C NMR spectroscopy. This produced a spectrum typical of agar and very similar to the one obtained for agar extracted fromP. capillacea plants. However, the callus agar displayed no gel-forming properties, even after alkali modification.author for correspondence     

Basal prostaglandin synthesis by the isolated perfused rat kidney

In order to assess the main characteristics of the prostaglandin (PG) biosynthesis by the isolated perfused rat kidney, the urinary and venous outputs of PGE2, PGF2alpha, 6-keto-PGF1alpha and of thromboxane (Tx)B2 were followed during 120 min after an equilibration period of 30 min. Single pass kidneys were perfused with a Krebs-Henseleit solution added with Polygeline at a constant flow rate providing a perfusion pressure about 90 mm Hg. From the beginning of the study, major differences could be observed in the renal biosynthetic rate of the 4 PG studied which were mainly excreted into the venous effluent. During the perfusion, urinary and venous outputs of PGE2, PGF2alpha and of TxB2 remained stable whereas those of 6-keto-PGF1alpha sharply increased and were found inversely related to the glomerular filtration rate (r = -0.95; p n 0.001). Finally, the urinary and venous outputs of each of the four PGs studied were found positively related. It is concluded that the isolated perfused rat kidney is a valuable preparation for studying the biosynthesis of PGs and that, at least in thi model, the urinary excretion of PGs is a good index of their renal synthesis.     

Production of somatic and germline chimeras in the chicken by transfer of early blastodermal cells

Cells were isolated from stage X embryos of a line of Barred Plymouth Rock chickens (that have black pigment in their feathers due to the recessive allele at the I locus) and injected into the subgerminal cavity of embryos from an inbred line of Dwarf White Leghorns (that have white feathers due to the dominant allele at the I locus). Of 53 Dwarf White Leghorn embryos that were injected with Barred Plymouth Rock blastodermal cells, 6 (11.3%) were phenotypically chimeric with respect to feather colour and one (a male) survived to hatching. The distribution of black feathers in the recipients was variable and not limited to a particular region although, in all but one case, the donor cell lineage was evident in the head. The male somatic chimera was mated to several Barred Plymouth Rock hens to determine the extent to which donor cells had been incorporated into his testes. Of 719 chicks hatched from these matings, 2 were phenotypically Barred Plymouth Rocks demonstrating that cells capable of incorporation into the germline had been transferred. Fingerprints of the blood and sperm DNA from the germline chimera indicated that both of these tissues were different from those of the inbred line of Dwarf White Leghorns. Bands that were present in fingerprints of blood DNA from the chimera and not present in those of the Dwarf White Leghorns were observed in those of the Barred Plymouth Rocks.(ABSTRACT TRUNCATED AT 250 WORDS)     

桔皮果胶提取条件的选择

用酸浸提、酒精沉淀法,从桔皮中提取果胶,通过正交设计分析,获得最佳得率的工艺条件。即果胶浸提液的酸度为pH2,反应时间2小时。沉淀果胶的酒精浓度为50％,其得率是12.6％。     

喜马拉雅土拨鼠非冬眠期乳酸脱氢酶同工酶基因表达特征

用聚丙烯酰胺凝胶电泳和紫外光谱法分析非冬眠期喜马拉雅土拨鼠4种组织的乳酸脱氢酶(LDH)同工酶的酶谱及其活力,该鼠骨骼肌酶带的多态分布,可能是潜在的调节基因调控所致。另外,本文还对构象异构体产生的亚带进行了研讨。     

甘蓝型油菜芥酸和二十碳烯酸含量的基因效应

以甘蓝型油菜的4种纯合芥酸基因型之间所有可能的6个杂交组合的P_1、P_2、F_1、P_2、B_1和B_2世代为材料,用生统遗传学方法研究了芥酸和二十碳烯酸的基因作用形式及效应。发现无论亲本是单基因差异还是二基因差异,F_1和F_2代的芥酸含量都接近中亲值,F_1略大于中亲值和F_(20)世代均值分析表明,芥酸含量的遗传符合加性显性模型,加性效应占绝对优势,显性效应不显著。用数量遗传学方法估计的芥酸基因数与已知的结果相近。     

异育淇鲫及其双亲同工酶的比较研究

用4.5％聚丙烯酰胺凝胶平板电泳研究了异育淇鲫及其母本淇鲫和父本兴国红鲤的肌可溶性蛋白以及肾、肝、眼、背白肌和心等五种组织的乳酸脱氢酶(LDH)、苹果酸脱氢酶(MDH)和酯酶(EST)。结果发现:异育淇鲫的肌可溶性蛋白以及同工酶的电泳图谱与母本淇鲫相同而与父本兴国红鲤显著不同,因而认为异育淇鲫是淇鲫雌核发育的产物,父本基因对子代基本无影响。在此基础上,本文对异源精子在雌核发育中所起的生物学作用进行了初步探讨。     

鹅观草与大麦属间杂种的形态和细胞遗传学研究

用活体/离体幼胚培养法成功地获得了鹅观草(Roegneria kamooji,2n=12,SSHHYY)与大麦(Hordeum vulgare,2n=14,11)间的属间杂种。杂交结实率为31.4％,胚培成苗率60.9％。杂种表现一年生,具有很强的生活力,形态上偏向鹅观草。F_1自交不孕,用大麦回交亦不结实。杂种具有预期的2n=28(SHYI)条染色体,花粉母细胞减数分裂中期Ⅰ平均形成26.38个单价体,0.67个棒状二价体,0.12个环状二价体和0.02个三价体。本文对双亲染色体组间的同源性以及在大麦育种中利用鹅观草种质的可能性进行了讨论。