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Insects Sep 2021Arthropods, including insects, convert sterols into cholesterol due to the inability to synthesise cholesterol de novo. 24-dehydrocholesterol reductase (DHCR24) plays an...
Arthropods, including insects, convert sterols into cholesterol due to the inability to synthesise cholesterol de novo. 24-dehydrocholesterol reductase (DHCR24) plays an important role in the conversion. Not only involving the cholesterol biosynthesis in vertebrates, DHCR24 is required for the conversion of desmosterol into cholesterol in phytophagous insects. The current study extensively examined DHCR24 in omnivorous insects, which feed on both plants and animals, using as the experimental model. We identified cDNAs encoding two homologues of DHCR24 from , which were designated as GbDHCR24-1 and GbDHCR24-2. Both homologues contained the flavin adenine dinucleotide binding domain, which is a feature of DHCR24. Quantitative polymerase chain reaction revealed that among tissues of adult crickets, fat body and anterior midgut expressed high levels of GbDHCR24s. Both fat body and anterior midgut demonstrated DHCR24 activities in which one of the functions is the conversion of desmosterol into cholesterol in vitro. Knockdown of GbDHCR24-1 significantly reduced the conversion activity in the anterior midgut while knockdown of the GbDHCR24-2 did not. Additionally, the accumulation of desmosterol was detected in a feeding experiment with a specific DHCR24 inhibitor, azacosterol. We finally concluded that GbDHCR24-1 is the major enzyme that facilitates the desmosterol-to-cholesterol-conversion in crickets.
PubMed: 34564222
DOI: 10.3390/insects12090782 -
Journal of Bacteriology Nov 1978The interconversion of free and esterified sterols was followed radioisotopically with [U-14C]acetate and [methyl-14C]methionine. In pulse-chase experiments,...
The interconversion of free and esterified sterols was followed radioisotopically with [U-14C]acetate and [methyl-14C]methionine. In pulse-chase experiments, radioactivity first appeared mainly in unesterified sterols in exponential-phase cells. Within one generation time, the label equilibrated between the free and esterified sterol pools and subsequently accumulated in steryl esters in stationary-phase cells. When the sterol pools were prelabeled by growing cells aerobically to the stationary phase and the cells were diluted into unlabeled medium, the prelabeled steryl esters returned to the free sterol form under several conditions. (i) During aerobic growth, the prelabeled sterols decreased from 80% to 45% esters in the early exponential phase and then returned to 80% esters as the culture reached the stationary phase. (ii) Under anaerobic conditions, the percentage of prelabeled steryl esters declined continuously. When growth stopped, only 15% of the sterols remained esterified. (iii) In the presence of an inhibitor of sterol biosynthesis, which causes accumulation of a precursor to ergosterol, prelabeled sterols decreased to 40% steryl esters while the precursor was found preferentially in the esterified form. These results indicate that the bulk of the free sterol and steryl ester pools are freely interconvertible, with the steryl esters serving as a supply of free sterols. Furthermore, there is an active cellular control over what types of sterol are found in the free and esterified sterol pools.
Topics: Aerobiosis; Anaerobiosis; Azacosterol; Ergosterol; Esters; Saccharomyces cerevisiae; Sterols
PubMed: 361713
DOI: 10.1128/jb.136.2.531-537.1978 -
Journal of Neurochemistry Apr 1984In this report, we examine the requirement of cholesterol biosynthesis and its axonal transport for goldfish optic nerve regeneration. Cholesterol, labeled by...
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-diazacholesterol. The inhibition of growth could be overcome by addition of mevalonolactone, but not cholesterol, to the medium. Intraperitoneal administration of 200 nmol of diazacholesterol resulted in 92-98% inhibition of retinal cholesterol synthesis and accumulation of labeled desmosterol 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.
Topics: Animals; Axons; Azacosterol; Cholesterol; Desmosterol; Goldfish; Mevalonic Acid; Nerve Regeneration; Optic Nerve; Retina
PubMed: 6699648
DOI: 10.1111/j.1471-4159.1984.tb12701.x -
Poultry Science Feb 2004Contraception may provide a useful nonlethal management tool when it is desirable to reduce populations of birds. We tested the efficacy of 20,25 diazacholesterol, and...
Effectiveness of twenty, twenty-five diazacholesterol, avian gonadotropin-releasing hormone, and chicken riboflavin carrier protein for inhibiting reproduction in Coturnix quail.
Contraception may provide a useful nonlethal management tool when it is desirable to reduce populations of birds. We tested the efficacy of 20,25 diazacholesterol, and immunization with avian gonadotropin-releasing hormone (AGnRH-I) and chicken riboflavin carrier protein (cRCP) as contraceptives and investigated their modes of action in Coturnix quail (Coturnix coturnix japonica). Females that were paired with males treated with 20,25 diazacholesterol produced lower percentages of eggs that were fertile and hatched. Females treated with 20,25 diazacholesterol and paired with control males laid fewer eggs, and lower percentages of their eggs were fertile and hatched. Treatment with 20,25 diazacholesterol reduced testosterone levels in males and progesterone levels in females. Nonesterified cholesterol levels were reduced, whereas desmosterol levels increased in birds treated with 20,25 diazacholesterol. Treatment with AGnRH-I and cRCP immunocontraceptive vaccines did not decrease average egg production and hatchability or hormone levels, but this failure might have been due to the vaccination protocol. If registered, wildlife managers may be able to use 20,25 diazacholesterol when other methods, such as lethal control, are undesirable for reducing damage caused by specific breeding behaviors such as the building of nests.
Topics: Animals; Anticholesteremic Agents; Azacosterol; Carrier Proteins; Cholesterol; Contraceptive Agents; Coturnix; Desmosterol; Female; Fertility; Gonadotropin-Releasing Hormone; Male; Membrane Transport Proteins; Oviposition; Progesterone; Riboflavin; Testosterone; Treatment Outcome
PubMed: 14979575
DOI: 10.1093/ps/83.2.234 -
Effects of diazacholesterol dihydrochloride (SC-12937), an avian antifertility agent, on rat testis.Journal of Andrology 1986The present study was undertaken to evaluate the effectiveness of an avian chemosterilant, 20, 25-diazacholesterol dihydrochloride (SC-12937), on the rat testis. Adult...
The present study was undertaken to evaluate the effectiveness of an avian chemosterilant, 20, 25-diazacholesterol dihydrochloride (SC-12937), on the rat testis. Adult male rats were injected intraperitoneally with 10 mg (Group 1) or 30 mg (Group 2) of SC-12937/kg/d or with vehicle alone (Group 3) for 10 days, and were killed 24 hours after the last injection. A wide range of variation in the appearance of affected seminiferous tubules was observed in the testis of SC-12937-treated rats at both dose levels. This ranged from apparently normal-looking seminiferous tubules to almost completely atrophied tubules with no cells. Affected tubules exhibited intraepithelial vacuoles of varying size, multinucleated giant cells, germ cell exfoliation, and tubular atrophy. The presence of severely damaged and entirely normal seminiferous tubules adjacent to one another in the same section was noteworthy. The changes appeared to be dose-related. A greater number (34.6%) of affected tubules were observed in rats receiving 30 mg of SC-12937 compared with the ones receiving 10 mg of this compound (19.6%). The Sertoli cells also were affected by this drug and exhibited cytoplasmic vacuolation, a marked increase in the accumulation of lipid droplets and myeloid bodies. Necrotic Sertoli cells also were observed in the severely affected tubules. The possible mechanism of antispermatogenic action of SC-12937 in rats has been discussed briefly.
Topics: Animals; Anticholesteremic Agents; Azacosterol; Body Weight; Cholesterol; Contraceptive Agents, Male; Male; Microscopy, Electron; Organ Size; Rats; Seminiferous Tubules; Sertoli Cells; Spermatogenesis; Testis
PubMed: 3771367
DOI: 10.1002/j.1939-4640.1986.tb00930.x