Sucrose synthase in rice plants : growth-associated changes in tissue specific distributions

Different parts of the rice (Oryza sativa L.) plant at different growth stages were analyzed for sucrose synthase (SS) by enzyme activity assay and enzyme-linked immunosorbent assay directly on the extracts or on the eluates from a gel filtration column. On a dry matter basis, the amount of soluble protein and SS activity decreased significantly, but the amount of enzyme protein changed little in growing leaves. In the grain, the SS activity was the highest at the early ripening stage and decreased later, but the amount of SS protein increased with the increase in maturity. In the root, a low activity of SS was detectable only in the tillering but not in other stages. Immunoblotting of SS protein extracted from different parts of rice showed two bands. Elution patterns of crude extracts from a gel filtration column showed the presence of several types of SS protein. Among them, two to three types with larger elution volumes had the SS activity but others with smaller elution volumes (considered as the aggregated forms) had no activity. The SS purified from different parts of the plant showed similar but distinctly different electrophoretic mobilities in a native gel. It has been concluded that different isozymes are expressed in different tissues at different growth stages.     

Drugs of abuse--opiates.

Treating opiate-dependent patients can be difficult for many physicians because the patients'' life-styles, values, and beliefs differ from those of the physicians. Primary care physicians, however, are often involved in the treatment of the medical complications of opiate abuse, and physicians must often manage a patient''s opiate dependence until appropriate referral to a drug abuse treatment program can be arranged. Treatment is guided by an understanding of the patient''s addictive disease, for which there are specific diagnostic criteria, and an understanding of the pharmacology of opiates of abuse and the medications used in treating opiate dependence. The opiate agonist, methadone, is useful for both detoxification and maintenance. The opiate antagonist, naloxone, is the treatment of choice for opiate overdose, and naltrexone, also an opiate antagonist, is a useful adjunct in subgroups of opiate-dependent patients for preventing relapse. New medications for the treatment of opiate dependence are being developed.     

Purification and characterization of a novel nucleoside phosphorylase from a Klebsiella sp. and its use in the enzymatic production of adenine arabinoside

An adenosine-assimilating bacterium, Klebsiella sp. strain LF1202, inducibly formed a novel nucleoside phosphorylase which acted on both purine and pyrimidine nucleosides when the cells were cultured in medium containing adenosine as a sole source of carbon and nitrogen. The enzyme was purified (approximately 83-fold, with a 17% activity yield) to the homogeneous state by polyacrylamide gel electrophoresis. The molecular weight of the purified enzyme was calculated to be 125,000 by gel filtration of Sephadex G-200 column chromatography, although the enzyme migrated as a single protein band with a molecular weight of 25,000 on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis; thus, it was thought to consist of five identical subunits. Besides purine nucleosides (adenosine, inosine, and guanosine), the purified enzyme also acted on pyrimidine nucleosides such as uridine, 2'-deoxyuridine, and thymidine. The purified enzyme catalyzed the synthesis of adenine arabinoside, a selective antiviral pharmaceutic agent, from uridine arabinoside and adenine.     

海枣曲霉β—D—岩藻糖苷酶的研究

Although beta-D-fucosidase (beta-D-fucoside fucohydrolase, EC 3.2.1.38) has been isolated from various sources, the identity of this enzyme is still not settled. We have purified a specific beta-D-fucosidase in electrophoretically homogeneous form crude extracts of Aspergillus phoenicis by polyethyleneglycol 6000-phosphate buffer aqueous two-phase separation, and successive chromatography on DEAE-Sephadex A-50, hydroxyapatite and Sephadex G-100 columns. The molecular weight of the enzyme was estimated to be 57000 by SDS-polyacrylamide gel electrophoresis and 50000 to 60000 by gel filtration on Sephadex G-100. The enzyme showed optimum coside were 2.4mmol/L, and 1.28 mumol min-1 the pH range 5.5-6.5 and below 35 degrees C. The Km and the Vmax values for pNP-beta-D-fucoside were 2.4mmol/L, and 1.28 mumol.min-1.mg-1 respectively. The enzyme was strongly inhibited by sulfhydryl group reagents, PCMB-NEM and iodoacetate. It was also inhibited by EDC, DEP and NBS. Thus, -SH, -COOH groups, histidyl and tryptophyl residues were essential for enzyme activity. The purified beta-D-fucosidase showed high specificity toward p-nitrophenyl beta-D-fucoside. The enzyme was inhibited by D-fucose and D-fucono-gamma-lactone, but not by D-galactose, D-galactono-gamma-lactone, D-glucose or D-glucono-gamma-lactone; the latter compounds are specific inhibitors of beta-D-galactosidase and beta-D-glucosidase respectively. Thus, this enzyme is the most strictly specific beta-D-fucosidase when compared with those previously reported.     

Neotypification of the genusTrichosporon

The currently accepted type species of the genusTrichosporon Behrend isT. beigelii. This species has formerly been regarded as identical toT. cutaneum. However, these fungi are now known to represent separate species with different ecology. The first species described inTrichosporon wasT. ovoides, an agent of human white piedra. A neotype strain is designated for this species, while a lectotype strain is indicated forT. cutaneum. The nameT. beigelii is considered as doubtful and consequently cannot be maintained.     

Transcobalamin II--cobalamin binding sites are present on rabbit germ cells.

Specific binding sites for rabbit transcobalamin II have been found on isolated adult rabbit germ cells. Scatchard analysis revealed a single class of binding sites for [57Co]cyanocobalamin-transcobalamin II with an association constant (Ka) of 1.3 x 10(10) M-1 and 700 sites per cell. Binding was reversible, saturable and calcium dependent. Electron microscope radioautography following incubation with iodinated transcobalamin II at 4 degrees C led to a detectable labeling mainly restricted to the plasma membrane.     

Common denominators in the etiology and pathology of visceral lesions of cystic fibrosis and Keshan disease

The common denominator of a unique disseminated multi-focal milliary myocardial hyaline necrosis and fibrosis in Keshan disease (KSD) and cystic fibrosis (CF) and a commonality of the affected age groups of fetuses and preschool children led to the review of existing KSD autopsy material to search for pancreatic and hepatic lesions considered pathognomonic for CF. Pancreatic lesions considered pathognomonic for CF were found in 595, or 35% of 1700 documented cases of KSD. The pancreatic lesions were limited to tissues of fetuses and preschool children. Adults dying of KSD had diagnostic lesions limited to the cardiovascular system, liver, and skeletal muscle. Varying degrees of focal biliary cirrhosis were identified in 850, or 50% of the KSD autopsies, and 85, or 5% developed severe lobular cirrhosis. The common denominator in CF and KSD appears to be a primary or induced secondary selenium deficiency in age-susceptable humans, prenatally at or around 22 wk of fetal life, during early postnatal life, or during the rapid-growth preschool years. The basic difference between the natural history of CF and KSD is that the selenium deficiency is totally environmental in KSD and appears to be the result of a maternal malabsorptive syndrome or an abnormality of selenium transfer in CF.     

背联体贻贝棘尾虫的形态,形态发生及其调节现象

背联体贻贝棘尾虫的每一虫腹面含有相当于正常棘尾虫的腹面纤毛系统,背联两虫任意一侧属于一虫的背面有4列背触毛,它们的排列分布相似于正常棘昆虫的第1—4列背触毛,另一虫背面打2列背触毛,它们相似于正常棘尾虫的第5、6列背触毛。结果表明,背联体棘尾虫是其中两虫各以背面第4列和第5列背触毛之间的皮层区相联接形成的。也有的背联体中背部皮层联接区有变化。无性分裂中背联两虫皮层纤毛结构的形态发生相似于正常棘尾虫,并且两者其皮层纤毛器如口围带、额腹横棘毛、左、右缘棘毛和背触毛等相应结构的发育是同步进行的,推测背联两虫的皮层发育既是相对独立的,又有某种机制控制着相互间的协调。背联体棘昆虫在无性生殖周期中总是经历着一个调节成单体的过程,认为这于背联两虫都具有一套结构功能正常的运动胞器(特别是口围带),而产生向不同方向运动的“不协调”的力有关。     

西双版纳热带季节雨林植物种类多样性的一种研究方法

一、方法1.样地的选择样地分别选取热带干性季节雨林的典型代表——以箭毒木(Antiaris toxicaria)、龙果(Pouteria grandifolia)为标志的群落,以千果榄仁(Terminalia myriocarpa)、番龙眼     

The effect of insecticides on the distribution of foracing parasitoids,Diaeretiella rapae [Hym.: Braconidae] on plants

Foraging aphid parasitoids,Diaeretiella rapae M'Intosh, were exposed to sublethal doses of the insecticides pirimicarb, permethrin and malathion on brusslls sprouts plants. Observations on wasp distribution over time revealed that wasps spent less time on sprayed plants, relative to controls and, while on these plants, tended to concentrate activity on unsprayed surfaces. For permethrin and malathion, pesticide residues reversed the stereotypic upward foraging pattern of the wasp. Negative consequences of sublethal pesticide doses for parasitoid foraging efficiency are discussed.