The effect of different hyperglucagonemic states on monooxygenase activities and isozymic pattern of cytochrome P-450 in mouse

The continuous infusion of a low dose of glucagon (35 g/kg/d, for 5 d) constitutes, in view of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase activities , a reliable experimental model of hyperglucagonemia. By conjunction of monooxygenase assays and immunoquantitation of specific isozymes of cytochrome P-450, the actual inducing ability of glucagon has been shown and it might explain some of the modifications of the drug metabolizing system in diabetic mice. The isozymic pattern of cytochrome P-430 of liver microsomes from diabetic mice appears very different from that produced by classical inducers.     

Use of purified antipeptide sera of selected specificity for the detection of the simian virus 40 large T antigen by western blotting

Western blotting was used as a powerful alternative to immunoprecipitation for the detection of the simian virus 40 (SV40) large tumor (T) antigen. After resolution by electrophoresis on a SDS-polyacrylamide gel of a [¹⁵S]methionine labeled crude extract from SV40 infected monkey kidney cells, the separated proteins were transferred electrophoretically on nitrocellulose paper. T antigen was detected on nitrocellulose strips by using for the first time, specific, purified antipeptide monoclonal antibodies directed against the N- and C-terminal portions of the molecule, and¹²⁵I-labeled Protein A.     

Differentiation of keratinocytesin vitro: a new culture vessel mimicking thein vivo situation

A culture vessel consisting of two independent chambers separated only by the growth substrate is described. Cells may be cultured on both sides of the growth substrate. Culture medium and gas exposure can independently be controlled in both compartments. Human hair follicles have been used as source of keratinocytes and the bovine eye lens capsule has been explored as growth substrate. The presence of 5% CO₂ in air in the lower compartment appears to have a significant effect on the morphology of the cultures. When the cultures are being exposed to air with 5% CO₂, the culture medium being applied in the lower compartment, formation of corneocytes characteristic for adult stratum corneum is induced, as evidenced by light and electron microscopy. To the knowledge of the authors, this stage of differentiationin vitro has not been obtained with previously described systems. Differentiation of the lower cell layers has been characterised with specific antibodies. The possible use of the system for applied and pure scientific research is discussed.     

Inhibition of polyphosphoinositide phosphodiesterase by aminoglycoside antibiotics

The calcium-activated phosphodiesteratic hydrolysis of³²P-labeled phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 4-phosphate in prelabeled nerve ending membranes is inhibited by the aminoglycosides neomycin and gentamicin, and to a lesser extent, by streptomycin. The inhibition is overcome by increasing concentrations of Ca²⁺, indicating that the aminoglycosides exert their effect by displacing Ca²⁺ from lipid.Dedicated to Professor Yasuzo Tsukada.     

Aquatic fungi of Algeria: Achlya radiosa Maurizio

Achlya radiosa Maurizio is reported from Algeria. This is the first record for the African continent. Culture methods and morphological and reproductive characters of the fungus are given.     

Cholesterol Synthesis and Nerve Regeneration

Abstract: In this report, we examine the requirement of cholesterol biosynthesis and its axonal transport for goldfish optic nerve regeneration. Cholesterol, labeled by intraocular injection of [³H]mevalonolactone. exhibited a delayed appearance in the optic tectum. Squalene and other minor components were labeled but not transported. Following optic nerve crush, the amount of labeled cholesterol transport was elevated, while retinal labeling was not altered relative to control fish. A requirement for cholesterol biosynthesis is inferred from the inhibition of neurite outgrowth in retinal explants caused by the cholesterol synthesis inhibitor, 20, 25-diazacholes-terol. The inhibition of growth could be overcome by addition of mevalonolactone, but not cholesterol, to the medium. Intraperitoneal administration of 200 nmol of dia-zacholesterol resulted in 92-98% inhibition of retinal cholesterol synthesis and accumulation of labeled des-mosterol and other lipids in fish retina and brain which persisted for 2 weeks. Diazacholesterol-treated fish showed no reduction in the amount of lipid-soluble radioactivity transported following intraocular injection of [³H]mevalonolactone, but there were alterations in the chromatographic pattern of the transported labeled lipids. In contrast to its effects on neurite outgrowth in vitro , diazacholesterol did not inhibit optic nerve regeneration in vivo , as measured both by arrival of labeled rapidly transported protein at the tectum and by time required for the return of visual function.     

Hoplolaimoidea (Nematoda: Tylenchida) from the Aleutian Islands with Descriptions of Four New Species

Four new species of hoplolaimoid nematodes (Merlinius adakensis, Pratylenchoides megalobatus, Pratylenchus pratensisobrinus, and Pratylenchus ventroprojectus) are described from Adak Island in the Aleutian chain. M. adakensis n. sp. is separated from other species by body length (0.96-1.3 mm), stylet length (32-36 μm), number of tail annules (49-68), and c'' (3.1-4.1). P. megalobatus n. sp. differs from all known Pratylenchoides spp. by having a very long esophageal gland lobe (b'' = 2.4-3.3, overlap 3-6 times the body width). P. pratensisobrinus n. sp. closely resembles P. pratensis (de Man) Filipjev, but has a longer stylet (15-17 μm), a longer tail (c = 12-15; c'' = 2.8-3.7), and more tail annules (23-37). P. ventroprojectus n. sp. is distinguished by body length (392-475 μm), three lip annules, low and flattened cephalic capsule, and presence of terminal subventral projection. Pratylenchoides variabilis Sher, Helicotylenchus amplius Anderson &Eveleigh, and H. spitsbergensis Loof are also reported from Adak and Amchitka Islands.     

Effect of Folate Deficiency on Local Cerebral Glucose Utilization in the Rat

There is considerable debate on the role of folate in CNS function. Recent work indicates that folate deficiency may affect CNS serotonin metabolism, and clinical studies describe many consequences of such a deficiency. On the other hand some workers maintain that folate deficiency alone causes CNS abnormalities. We maintained rats, through dietary deprivation, at folate levels below 4 ng/ml for more than 6 weeks and showed that at that time both their liver and brain folate levels were significantly reduced. We then studied their local cerebral glucose utilization (LCGU) using the [14C]deoxyglucose technique. This method assesses cerebral function by measuring regional metabolic activity. We also determined LCGU in rats given the same diet but replenished with folate (folate control) and in others given free access to commercially available food (normal controls). Our results show that this degree of folate deficiency has no effect on cerebral function. This contrasts with the focal suppression of LCGU we previously reported in a model of vitamin B12 deficiency.     

A proton-deuterium exchange study of three types ofDesulfovibrio hydrogenases

Summary Hydrogenases are among the main enzymes involved in bacterial anaerobic corrosion of metals. The study of their mode of action is important for a full comprehension of this phenomenon. The three types ofDesulfovibrio hydrogenases [(Fe), (NiFe), (NiFeSe)] present different patterns in the pH dependence of their activity. The periplasmic enzyme fromDesulfovibrio salexigens and the cytoplasmic enzyme fromDesulfovibrio baculatus both have pH optima at 7.5 for H₂ uptake and 4.0 for H₂ evolution and H⁺–D₂ exchange reaction (measured by membrane-inlet mass-spectrometry). The H₂ to HD ratio at pH above 5.0 is higher than 1.0. The periplasmic hydrogenase fromD. gigas presents the same pH optimum (8.0) for the H⁺–D₂ exchange as for H₂ consumption. In contrast, the enzyme fromD. vulgaris has the highest activity in H₂ production and in the exchange at pH 5.0. Both hydrogenases have a H₂-to-HD ratio below 1.0.