An efficient, practical synthesis of 2-methoxyestradiol

An efficient and practical scheme to synthesize 2-methoxyestradiol has been developed. The key step was the copper-mediated methoxylation using ethyl acetate as a co-catalyst to introduce a methoxyl group. These synthetic procedures of four steps from 17β-estradiol as starting material gave 2-methoxyestradiol with a 61% overall yield.     

Effect of ACTH, dexamethasone, and adrenalectomy on the secretion of testosterone in the rat

The effect of ACTH (100 micrograms/animal/day, i.p.), dexamethasone (75 micrograms/animal/day, s.c.), both for three consecutive days, and adrenalectomy, with or without dexamethasone, maintained according to the group, one, two or three days, on the plasmatic testosterone and corticosterone levels, has been studied in adult male Wistar rats. ACTH and adrenalectomy produced a high decrease in testosterone levels (p less than 0.001 for the three days studied). Dexamethasone produced lower testosterone levels in the first day followed by partial recuperation between the second and the third days of its administration. Dexamethasone produced the effects mentioned for intact animals. The changes in corticosterone levels were according to an adequate response of the hypothalamus-pituitary-adrenal system under these experimental circumstances. ACTH exerts an inhibitory effect on testosterone secretion in the rat, so that such an effect from the data obtained after adrenalectomy and simultaneous dexamethasone injections, does not seems to be mediated either by the presence of adrenals or high corticosterone levels.     

Inorganic-carbon uptake by a small-celled strain of Stichococcus bacillaris

Air-grown cells of a marine, small-celled (2 m diameter) strain of Stichococcus bacillaris contained appreciable carbonic-anhydrase activity but this was repressed when cells were grown on air enriched with 5% (v/v) CO₂. Assay of carbonic-anhydrase activity using intact cells and cell extracts showed all activity was intracellular in this Stichococcus strain. Measurement of inorganic-carbon-dependent photosynthetic O₂ evolution at pH 5.0, where CO₂ is the predominant form of inorganic carbon, showed that the concentration of inorganic carbon required for half-maximal rate of photosynthetic O₂ evolution [K_0.5(CO₂)] was 4.0 M for both air- and CO₂-grown cells. At pH 8.3 the K_0.5(CO₂) was 0.3 mM for air-grown and 0.6 mM for CO₂-grown cells. Sodium ions did not enhance bicarbonate utilization. Measurement of the internal inorganic-carbon pool (HCO ₃ ^– +CO₂) by the silicone-oil-layer centrifugal filtering technique showed that air- and CO₂-grown cells were able to concentrate inorganic carbon up to 20-fold in relation to the external medium at pH 5.0 but not at pH 8.3. In this alga the high affinity for CO₂ and inorganic-carbon accumulation in CO₂- and air-grown cells results from active CO₂ transport that is not dependent on carbonic-anhydrase activity.Abbreviation Hepes 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid     

Infraciliature, morphogenesis and life cycle of Endosphaera terebrans (Suctoria, Tokophridae)

The morphology, infraciliature, and life cycle of Endosphaera terebrans, a suctorian endocommensal of peritrichs, have been studied with the aid of silver impregnation. The life cycle of Endosphaera terebrans begins with infection of the host cell by a small larva. The swarmer has a pointed needle-like cellular projection and two rings of cilia. The swarmer penetrates the the peritrich, loses the cilia, and then matures into an adult. The infraciliature of the adult form has four rows of barren kinetosomes that lack kinetodesmal fibers. By endogenous budding, a migratory larva is produced that leaves the host cell through the peristomial disc and that can infect other peritrichs.     

The AXB and BXA set of recombinant inbred mouse strains

The recombinant inbred (RI) set of strains, AXB and BXA, derived from C57BL/6J and A/J, originally constructed and maintained at the University of California/San Diego, have been imported into The Jackson Laboratory and are now in the 29th to 59th generation of brother-sister matings. Genetic quality control testing with 45 proviral and 11 biochemical markers previously typed in this RI set indicated that five strains had been genetically contaminated sometime in the past, so these strains have been discarded. The correct and complete strain distribution patterns for 56 genetic markers are reported for the remaining RI strain set, which consists of 31 living strains and 8 extinct strains for which DNA is available. Two additional strains, AXB 12 and BXA 17, are living and may be added to the set pending further tests of genetic purity. The progenitors of this RI set differ in susceptibility to 27 infectious diseases as well as atherosclerosis, obesity, diabetes, cancer, cleft palate, and hydrocephalus. Thus, the AXB and BXA set of RI strains will be useful in the genetic analysis of several complex diseases.     

Enhanced detection of glycoproteins in polyacrylamide gels

A highly sensitive and simple method to enhance detection of glycoproteins resolved by either one- or two-dimensional polyacrylamide gel electrophoresis is described. The method is a modification of the procedure described by D. Fargeaud et al. (D. Fargeaud, J. C. Benoit, F. Kato, and G. Chappuis (1984) Arch. Virol. 80, 69-82) that uses concanavalin A conjugated with fluorescein isothyocyanate to detect the carbohydrate moiety of glycoproteins. Briefly, the electrophoresed gel is exposed to the fluorescent lectin, thoroughly washed, and sequentially transferred to 50% methanol in deionized water and to absolute methanol. The result is an abrupt dehydration of the gel which turns evenly white and stiff. At least a twofold enhancement of fluorescence is obtained as detected by exposing the treated gel to an appropriate uv source. The sensitivity of the procedure allows us to detect purified immunoglobulin molecules by their carbohydrate content in the range of 0.2 microgram of total protein. The specificity of the detection is demonstrated by a comparison with the corresponding polypeptide profile obtained by silver nitrate staining of the gel.     

Phenolsulphonphthalein conjugation and biliary excretion in the rat: influence of phenobarbital and 3-methylcholanthrene

The effect of phenobarbital and 3-methylcholanthrene pretreatment on the biliary excretion of phenolsulphonphthalein (PSP) was investigated in male Wistar rats. The dye was injected at a single dose of 200 mumol/kg body wt. About 20% of the compound was excreted as a glucuronide in the controls, the liver UDP-glucuronyltransferase activity toward PSP being 0.064 +/- 0.005 nmol.min-1.mg protein-1. Treatment for two weeks with phenobarbital (354 mumol.kg body wt-1.day-1) caused a transient increase in conjugated and unconjugated PSP excretion, but glucuronyltransferase activity was not modified. 3-Methylcholanthrene pretreatment for 4 days (75 mumol.kg body wt-1.day-1) also enhanced biliary excretion of the dye, but the increase corresponded only to the glucuronide and glucuronyltransferase activity was significantly enhanced by 20%. Our data indicate that not only the rate of biotransformation but also other factors could be responsible for increased PSP biliary excretion following administration of microsomal enzyme inducers.     

白头翁的受精及组织化学研究

成熟花粉为二细胞,生殖细胞的蛋白质染色较营养细胞的深,淀粉粒充满营养细胞。花粉管常见穿人正在退化中的助细胞,并释放出两个精子,大量稠浓的蛋白质和淀粉,个别的释放在助细胞与胚囊壁之间。在一些卵细胞核,次生核(或极核)中,受精前后有1—3个小核仁(约1微米);助细胞具丝状器;反足细胞宿存,具多核和多核仁。胚囊中各个细胞的原生质稠浓程度和蛋白质染色深浅不同,其中以反足细胞和助细胞的原生质最稠浓,蛋白质染色最深。淀粉十分贫乏,绝大多数卵细胞,中央细胞和几乎全部助细胞和反足细胞均不含淀粉。双受精属于有丝分裂前类型,两性核融合步骤为:精子核接近和贴附在卵核和次生核上(或极核上),两性核的核膜溶解,其染色质沉入融合核,并随之松解,同时出现雄性核仁,最终,雄性核仁和雌性核仁合并,形成具单核和单核仁的合子和初生胚乳细胞。另外,雄性核仁同卵核仁合并较雄性核仁和次生核的晚,所以卵细胞完成受精较次生核晚。