Samuel H. Hori

Induction of vitellogenin synthesis in goldfish by massive doses of androgens.

Abstract Oral administration of massive doses of methyltestosterone into goldfish caused an extensive proliferation of the rough endoplasmic reticulum, hypertrophy of the Golgi apparatus, and the production of numerous secretory granules in the liver, suggesting the induced synthesis of some secretory proteins. The electrophoretic pattern of serum proteins was prominently altered, showing three bands which were absent in normal, immature fish. All of these changes were similarly observed in estradiol-treated fish. In order to identify the hormone-induced serum proteins, they were purified from estradiol- and methyltestosterone-treated fish and were subjected to chemical and immunological analyses. The results indicated that the serum proteins induced by methyltestosterone and by estradiol are identical in the contents of lipids, phospholipids, calcium, and protein-bound phosphorus and the reactivity to antiserum elicited to the estradiol-induced serum proteins. Furthermore, it was found that the antibody forms a single, connecting precipitin line with the hormone-induced proteins, sera of vitellogenic fish, and ovary extracts of matured fish, but not with sera of normal males. In view of the above findings, it was concluded that the serum proteins induced by methyltestosterone are vitellogenin. Ethynyltestosterone and methylandrostenediol were also effective, but testosterone, dihydrotestosterone, and methyldihydrotestosterone were much less effective in inducing vitellogenin synthesis.

Intramembraneous localization of rat liver microsomal hexose-6-phosphate dehydrogenase and membrane permeability to its substrates

A method for purifying hexose-6-phosphate dehydrogenase (beta-D-glucose: NAD(P) -oxidoreductase, EC 1.1.1.47) from rat liver microsomes is described. The purified enzyme was shown to be homogeneous by sodium dodecyl sulfate (SDS)-polyacrylamide electrophoresis. It is shown that the enzyme is bound to the inner surface of microsomal membranes, and that glucose 6-phosphate, but not NADP, penetrates almost freely into the membranes at 37 degrees C.

Energy storage during reproductive diapause in the Drosophila melanogaster species group

SummaryTemperate species of the Drosophila melanogaster group enter reproductive diapause for overwintering in response to short daylength. During the prediapause period they accumulate triacylglycerols, but not glycogen, as energy resources. The capacity for storing triacylglycerols differs between species, and appears to be closely correlated with diapause and cold-hardiness; cool-temperate species, such as those of the auraria species complex, which enter a deep diapause and are highly cold-hardy, accumulate larger quantities of triacylglycerols than warm-temperate species, such as D. rufa and D. lutescens, which enter a weak diapause and are less cold-hardy. Among the cool-temperate spcies, D. subauraria occurs at a higher latitude and has the greatest capacity for accumulating triacylglycerols. A subtropical species, D. takahashii, which has no diapause in nature and is not cold-hardy, is unable to store the same quantities of triacylglycerols as temperate species.

EFFECTS OF HORMONES ON HEPATIC GLUCOSE 6-PHOSPHATE DEHYDROGENASE OF RAT

The effects of hormones on the total activity and the isozyme pattern of glucose 6-phosphate dehydrogenase of livers of normal, castrated and adrenalectomized rats were studied. Sex difference in total enzyme activity and in the activity of one of the seven isozymes separated electrophoretically (band D enzyme) has been confirmed. Orchidectomy did not affect appreciably the enzyme activity; ovariectomy of young rats reduced the enzyme activity and abolished the sex difference. Adrenalectomy slightly reduced the enzyme activity in male and female rats, but did not eliminate the sex difference in isozyme pattern. Injection of dehydroepiandrosterone into normal and castrated female rats lowered the enzyme activity, whereas administration of estradiol benzoate to normal and castrated male rats strikingly increased the enzyme activity. In estradiol-treated males the isozyme pattern become female type. The effect of estradiol was inhibited by puromycin. Estradiol stimulated but dehydroepiandrosterone had little effect on hepatic 6-phosphogluconate dehydrogenase activity.

Immunohistochemical localization of hexose 6-phosphate dehydrogenase in various organs of the rat.

Distribution of hexose 6-phosphate dehydrogenase in various organs of the rat has been studied by a peroxidase-labeled antibody method in order to find some clue to elucidating the, as yet unclear, function of this enzyme. As a result, the following cells were found to contain this enzyme in relative abundance: hepatic parenchymal cells, ovarian lutein and theca interna cells, testicular interstitial cells, striated ducts and serous tubular portions of the submandibular gland, plasma cells and the P3 segment of proximal convolutions, and collecting tubules of the cortex and inner medulla of the kidney. Although the role of this enzyme in salivary glands and in plasma cells is unclear at present, the results obtained with steroidogenic cells, liver cells, and renal tubules appear to suggest the possibility that this enzyme might be involved in drug and steroid metabolism.

Electrophoretic studies on the phosphorylase isozymes.

The electrophoretic method of Davis, Schliselfeld, Wolf, Leavitt and Krebs (1967) for phosphorylase isozymes has been modified. By this method, five isozymes were separated in various organs of rat and pig and were disignated as phosphorylase L, LI, I, II and III. The L and III enzymes were the only forms found in liver and skeletal muscle, respectively, while the I enzyme was dominant in brain, uterus, lung and small intestine, which also contained some fractions of the II and III enzymes. The I enzyme was also dominant in adrenal, ovary and kidney, but these organs contained the L+II or L+LI as minor components. The L and LI were richly found in spleen and leukocytes of adult rats and pigs and in liver of newborn rats. Such organ-specific heterogeneity of phosphorylase was confirmed by the immunological tests with the antibodies prepared against phosphorylases I, III and L. The II and LI enzymes were found to be the hybrid molecules between the I and III enzymes, and between the I and L enzymes which have been previously reported as unhybridizable, respectively. In view of the above findings, it was concluded that the rat and pig possessed at least five molecular forms of phosphorylase.

Hexose 6-phosphate dehydrogenase in starfishes

1. 1. Tissue extracts from 18 species of starfishes contain hexose 6-phosphate dehydrogenase (H6PD) which closely resembled vertebrate H6PD in the following respects: dependence on NADP and NAD, high activities on galactose 6-phosphate and 2-deoxyglucose 6-phosphate, formation of enzymatically active smaller molecules by tryptic digestion, resistance to SH inhibitors and inhibition by Mg and Ca ions. 2. 2. Kms of partially purified H6PD of Asterias amurensis for glucose 6-phosphate, galactose 6-phosphate, 2-deoxyglucose 6-phosphate and glucose are 8 × 10−6, 7.1 × 10−5, 9.4 × 10−4 and 1.4 M, respectively, being comparable with those of vertebrate H6PD. 3. 3. The present finding on starfish H6PD suggests that the progenitor of vertebrate H6PD might arise near the beginning of or before echinoderm evolution.

Latency of microsomal hexose-6-phosphate dehydrogenase

Abstract Intact microsomes isolated from rat liver showed no hexose-6-phosphate dehydrogenase activity, but the enzyme was activated by Triton X-100, deoxycholate, NH4OH, glycine/NaOH, lysophosphatidycholine, phospholipases A and C, pancreatic lipase and cholesterol esterase, and also by sonic treatment. The enzyme activation by deoxycholate, NH4OH and sonic treatments was solely due to solubilization, while that by phospholipase A appeared to be due to the detergent action of the hydrolysis products. On the other hand, the primary effects of phospholipase C, cholesterol esterase and pancreatic lipase might be accounted for by partial removal of membrane lipids. The results of washing and trypsin digestion experiments suggested that hexose-6-phosphate dehydrogenase is one of the most firmly bound enzymes among the microsomal proteins. The catalytic properties were the same in the solubized and the membrane-bound, activated enzymes. Feeding the rats on a high carbohydrate diet altered the extent of enzyme activation by sonication and phospholipase C treatment, suggesting that the microsomal membrane would actually undergo changes in the conformation and/or chemical composition under certain circumstances.

Phenobarbital-induced increase of the hexose 6-phosphate dehydrogenase activity

Abstract The intracellular and intramicrosomal distributions of hexose 6-phosphate dehydrogenase were examined in the livers of normal and starved rats before and after phenobarbital treatment. The results have revealed that the administration of phenobarbital (75 mg/kg body weight, 4 days) causes a significant increase of the hexose 6-phosphate dehydrogenase activity only in smooth-surfaced, but not in rough-surfaced endoplasmic reticulum, with concomitant increases of the activities of NADPH-cytochrome c reductase and aminopyrine demethylase. Starvation prior to the phenobarbital treatment enhanced the effect of phenobarbital on the microsomal enzymes.

Cytological Phosphorylase Locations in Rat Liver and Muscle as Shown by a Lead Precipitation Method

The method of Goldberg et al. (J. Nat. Cancer Inst., 13, 543, 1952) for phosphorylase was so modified as to yield reproducible and reliable results. Tissues were frozen in liquid nitrogen, sectioned in a cryostat at —22 C, immersed overnight in acetone at dry-ice temperature, coated with celloidin, incubated in a medium containing glucose-1-phosphate, NaF, acetate buffer pH 5.8, and lead nitrate with or without addition of adenosine 5′-phosphate, washed in water, and the stain developed with either dilute ammonium sulfide solution or an aqueous solution of I2-KI, 1:2:300. The technique demonstrates phosphorylase activity in sarcoplasm and in cytoplasm of hepatic cells.