The “happy puppet” syndrome in two siblings

Summary Disomic and trisomic cells of a patient with Down syndrome mosaic were used to study the effect of the additional chromosome 21 against an identical genetic background. The frequency of Ag staining and the participation in satellite associations were determined for each pair of acrocentric chromosomes. The additional chromosome 21 of the trisomic cells and its homologues proved to be regularly Ag positive. Therefore the trisomic cells showed more Ag positive chromosomes and more satellite associations per cell than the diploid cells. Thus, no compensation for the additional rRNA-gene dose could be found in the cells of the trisomic line.     

Effect of inhibitors of protein synthesis on rat liver spermidine N-acetyltransferase

The increase in spermidine N-acetyltransferase activity in rat liver produced by carbon tetrachloride was completely prevented by simultaneous treatment with inhibitors of protein and nucleic acid synthesis suggesting that the increase results from the synthesis of new protein rather than the release of the enzyme from a cryptic inactive form. Treatment with cycloheximide 2 h after carbon tetrachloride also completely blocked the rise in spermidine N-acetyltransferase seen 4 h later. Such treatment completely prevented the fall in spermidine and rise in putrescine in the liver 6 h after carbon tetrachloride confirming the importance of the induction of spermidine N-acetyltransferase in the conversion of spermidine into putrescine. When cycloheximide was administered to rats in which spermidine N-acetyltransferase activity had been stimulated by prior treatment with carbon tetrachloride or thioacetamide, the activity was lost rapidly showing that the enzyme protein has a rapid rate of turnover. The half-life for the enzyme in thioacetamide-treated rats was 40 min, whereas the half-life for ornithine decarboxylase (which is well known to turn over very rapidly) was 27 min. In carbon tetrachloride-treated rats the rate or protein degradation was reduced and the half-life of spermidine N-acetyltransferase was 155 min and that for ornithine decarboxylase was 65 min. It appears that three of the enzymes involved in the synthesis and interconversion of putrescine and spermidine namely, ornithine decarboxylase, S-adenosylmethionine decarboxylase and spermidine N-acetyltransferase have rapid rates of turnover and that polyamine levels are regulated by changes in the amount of these enzymes.     

Highly sensitive assay for tyrosine hydroxylase activity by high-performance liquid chromatography

A highly sensitive assay for tyrosine hydroxylase (TH) activity by high-performance liquid chromatography (HPLC) with amperometric detection was devised based on the rapid isolation of enzymatically formed DOPA by a double-column procedure, the columns fitted together sequentially (the top column of Amberlite CG-50 and the bottom column of aluminium oxide). DOPA was adsorbed on the second aluminium oxide column, then eluted with 0.5 M hydrochloric acid, and assayed by HPLC with amperometric detection. d-Tyrosine was used for the control. α-Methyldopa was added to the incubation mixture as an internal standard after incubation. This assay was more sensitive than radioassays and 5 pmol of DOPA formed enzymatically could be measured in the presence of saturating concentrations of tyrosine and 6-methyltetrahydropterin. The TH activity in 2 mg of human putamen could be easily measured, and this method was found to be particularly suitable for the assay of TH activity in a small number of nuclei from animal and human brain.     

Plant growth-promoting activities of alkoxycarbonylisoureas in relation to their chemical structures

A number of alkoxycarbonylisourea derivatives were synthesized and their plant growth-promoting activities examined by the rice (Oryza sativa) seedling test. Isourea compounds with an appropriate substituent such as a halogen atom or a methyl, ethyl or methoxy group at the para-position on a benzene ring in 1-alkoxycarbonyl-2-alkyl-3-phenylcarbamoylisoureas promoted the growth of rice seedlings and acted as a highly active gibberellic acid-synergist when used in combination with gibberellic acid. The common structural requirements of isourea derivatives applied well for a growth promoter and a gibberellic acid-synergist.     

Effects of lipolytic enzymes on the photochemical activities of spinach chloroplasts.

1. Spinach class II chloroplasts were treated with purified potato lipolytic acyl-hydrolase and venom phospholipase A2, and their lipid degradations and the effects on the photochemical activities were followed. 2. Potato lipolytic enzyme hydrolyzed monogalactosyldiacylglycerol at a faster rate than phospholipids such as phosphatidylglycerol and phosphatidylcholine. The treatment caused a rapid decrease of Photosystem I activity, and a less change of Photosystem II activity. 3. Venom phospholipase A2 which preferentially hydrolyzed phosphatidylglycerol, caused a rapid decrease of Photosystem II activity and only a slight decrease of photosystem I activity. 4. Potato enzyme and phospholipase A2 degraded the membrane lipids of glutaraldehyde-fixed chloroplasts at a rather slightly higher rate than those of non-treated chloroplasts. 5. The results suggested a possible correlation between monogalactosyldiacylglycerol degradation and decay of Photosystem I activity and between phosphatidylglycerol degradation and decay of Photosystem II activity. A possible mechanism is discussed.     

EFFECT OF STIMULATION OF EXCITATORY NERVE TRACT ON RELEASE OF GLUTAMIC ACID FROM OLFACTORY CORTEX SLICES IN VITRO

Abstract— Thin sections prepared from the olfactory cortex of the guinea pig were incubated in a medium containing [¹⁴C]glutamate, and release of radioactive compounds and electrical activity were subsequently examined in the presence of l -cysteate. The postsynaptic potential was almost completely suppressed in the medium containing l -cysteate, whereas the presynaptic potential was unaffected. Repetitive stimulation of the excitatory input of the lateral olfactory tract enhanced release of radioactive glutamate. The facilitatory effect of lateral olfactory tract stimulation increased with increase in stimulus frequency and was dependent on calcium. Release of radioactive gluiamine was not enhanced by lateral olfactory tract stimulation. Phenobarbitone sodium markedly depressed both the postsynaptic potential and the effect of lateral olfactory tract stimulation on glutamate release. These results indicate that stimulation to the lateral olfactory tract enhances liberation of glutamate from the tract nerve terminals.     

Metabolism of testosterone sulfate in the rat: analysis of biliary metabolites.

Following intraperitoneal injection of a mixture of testosterone-7-3-H-17-sulfate and testosterone-4-14-C into male and female rats with bile fistulas, biliary metabolites were separated and purified by a combination of column chromatography, enzymic hydrolysis or solvolysis of the conjugate fractions and identification of the liberated aglycones. The injected steroids were extensively metabolized and excreted predominantly in the bile. The major portion of the 3H was excreted in the disulfate fraction in both sexes. Solvolysis of the disulfate revealed the sex-specific aglycone pattern: 5alpha-Androstane-3beta,17beta-diol was the major metabolite in the male rat, whereas 5alpha-androstane-3alpha,17beta-diol and polar steroids were found in the female. In marked contrast, testosterone was metabolized in a different way than testosterone sulfate. 14-C radioactivity was distributed in monoglucosiduronate, monosulfate, and diconjugate fractions. Analysis of the aglycones showed that polar steroids were the main metabolites in the male. In the female, testosterone was metabolized to polar steroids, androsterone, and 5alpha-androstane-3alpha,17beta-diol.     

Pummerer Rearrangement of Selenium-Containing Uracil Nucleosides

Abstract

Pummerer-type rearrangement of uracil nucleosides having a phenylseleno group in the 2′-, 3′-, and 5′-positions took place upon oxidation with MCPBA in CH₂Cl₂ followed by treatment with acid anhydrides to yield α-acyloxyselenides.