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At least 19 recordsLinked to original sources
PubMed1976

The in vitro effects of farnesol and derivatives on Hymenolepis diminuta.

Employing an in vitro maintenance system, in which 8-day-old Hymenolepis diminuta survives for 24 hr (Fioravanti and MacInnis, 1976), it was found that farnesol or farnesal supplementation of the medium had no beneficial effects on maintenance and these substances induced necrosis at higher concentrations. Similar experiments utilizing Schiller's (1965) culture system demonstrated that neither farnesol, farnesal, nor farnesyl methyl ether exhibited growth promoting effects and were toxic to the worms at higher concentrations. In addition, neither the 2-cis, 6-trans nor the 2-trans, 6-trans-isomers of farnesol promoted growth in the Schiller system and at higher concentrations resulted in severe necrosis within 24 hr.

Animals↗
PubMed1992

Growth inhibition of leukemia cell line CEM-C1 by farnesol: effects of phosphatidylcholine and diacylglycerol.

Acute leukemia cells of the established line CEM-C1 were treated during growth in serum-free medium with various concentrations of trans-trans farnesol. At concentrations ranging from 9.0 to 31.5 microM, farnesol inhibited growth of these cells without causing cell lysis. This effect was preceded by very rapid inhibition of choline incorporation in cellular lipid fraction. The growth inhibitory effect was prevented to a large extent by incubation with phosphatidylcholine or diacylglycerol.

Acyclic Monoterpenes↗
PubMedDate not supplied

[Activity of the octanol dehydrogenase, of the alcool dehydrogenase and aldehyde dehydrogenase on the farnesol metabolism. Photoperiodic and neurhormonale regulation, controlling the metabolism of the juvenile hormone, in Pieris brassicae (author's transl)].

The antagonistic photoperiodic behaviour of the farnesol dehydrogenases indicates that the photonic control mechanism of the brain acts on the farnesol derivates. This cerebral control is double. The first system, linked at the allatotrope function is proportionnal at the photoperiod and acts on the octanol dehydrogenase 0,32. The second system controle the deshydrogenases ADH bands 0,50--0,58, is linked at the darkness. It is linked also at the neurocerebral activity then it stops its activity at the 4th day of the 5th stage. This last seems to be the determinating control for the establishment of the diapause since in short photoperiod, when the inhibition by this system ends, the alcool dehydrogenases 0,50-0,58 series is suractivated in rate with the lasting of the scotophase. In darkness, the 1st system functionnes cyclically and has a maximum synchron with the single maximum of the 2nd system. Inversally, in continuous light, the 2nd system is synchronisated with the 1st which has a prolongated action, maybe linked with a prolongated activity of the neurosecretory cells of the pars intercerebralis and corpora allata.

Animals↗
PubMed1977

[Study on deshydrogenases implicated in control of farnesol and juvenile hormone metabolisms in Pieris brassicae (author's transl)].

Activity of ODH is high during larval development on pars intercerebralis which is releasing its allatotropic neurosecretion towards 4 th day of 5 th instar under photophase 16 h. ADH is inhibited during the same period and then activated at the time of spinning when the level of JH I and II is falling; by oxidization of JH I and JH II, possibly JH III is produced.

Animals↗
PubMed1977

Hydrolysis and isomerization of trans,trans-farnesyl diphosphate by Andrographis tissue-culture enzymes.

Incubation of (3R,5S)-[5-3H1]mevalonate + (3RS)-[2-14C]mevalonate with Andrographis cell-free extract leads to trans,trans-farnesol and cis,trans-farnesol which both totally retain tritium. 2. This conflicts with our previous results which predict one third tritium loss in the cis,trans-farnesol. Inversion at C-1 during hydrolysis of trans,trans-farnesyl diphosphate to trans,trans-farnesol could explain this anomaly. 3. (1s)-trans,trans-[1-3H1]Farnesyl diphosphate and phosphate and (1R)-trans,trans-[1-3H1]-farnesyl diphosphate and phosphate, all prepared chemically, were hydrolysed with Andrographis phosphatase, and alkaline phosphatase and hydrogenolysed with lithium aluminium hydride and the product alcohols exchanged with liver alcohol hydrogenase. 4. Both Andrographis phosphatase and alkaline phosphatase hydrolyse trans,trans-farnesyl diphosphate and trans,trans-farnesyl phosphate with retention. 5. Hydrolysis of trans,trans-[1-18O]farnesyl diphosphate in H2(18O with both phosphatases supports P-O fission. 6. The C-1 configuration in (1S)-TRANS,TRANS-[1-3H1]farnesyl diphosphate and phosphate and (1R)-trans,trans-[1-3H1]farnesyl diphosphate and phosphate is progressively racemised in 0.01 M NH4OH/MeOH (1/9) AT - 20 degrees C.

Alkaline Phosphatase↗
PubMed1978

Evidence from cell-free systems for differences in the sterol biosynthetic pathway of Rhizoctonia solani and Phytophthora cinnamomi.

Cell-free preparations of both Rhizoctonia solani, a sterol-synthesizing fungus, and Phytophthora cinnamomi, a non-sterol-synthesizing fungus, incubated in the presence of [2(-14)C]mevalonate and iodacetamide, converted the mevalonate into labelled mevalonate 5-phosphate, mevalonate 5-pyrophosphate and isopentenyl pyrophosphate. In the absence of iodoacetamide, but under anaerobic conditions, the same preparations converted the mevalonate into labelled geraniol, farnesol and squalene, the first two compounds presumably as their pyrophosphates. When cell-free preparations of both organisms were incubated aerobically in the presence of [1(-14)C]isopentenyl pyrophosphate, only labelled geraniol, farnesol and squalene were recovered from the P. cinnamomi reaction mixture, whereas labelled geraniol, farnesol, squalene, squalene epoxide, lanosterol and ergosterol were present in the R. solani reaction mixture. When these same preparations were incubated in the presence of 14C-labelled squalene, labelled squalene epoxide, lanosterol and ergosterol were recovered from the R. solani reaction mixture. In contrast, the P. cinnamomi preparation was unable to convert the squalene into products further along the sterol pathway; instead, a portion of the labelled squalene was converted into water-soluble products, indicating the possible existence of a squalene-degradation process in this organism. It appears that the block in the sterol biosynthetic pathway of P. cinnamomi occurs at the level of squalene epoxidation.

Alkenes↗
PubMed1978

Evidence from mycelial studies for differences in the sterol biosynthetic pathway of Rhizoctonia solani and Phytophthora cinnamomi.

Phytophthora cinnamomi, a member of the Pythiacease, does not synthesize sterols. Small amounts of squalene, but no squalene epoxide or sterol, were isolated from the dried mycelium of this fungus after growth in sterol-free medium. The dried mycelium of Rhizoctonia solani, a sterol-synthesizing fungus grown under the same conditions, contained small amounts of squalene and squalene epoxide and large amounts of ergosterol. When the two organisms were grown in the presence of [14C]acetate, only labelled geraniol, farnesol and squalene were recovered from the P. cinnamomi mycelium, whereas labelled geraniol, farnesol, squalene, squalene epoxide and ergosterol were recovered from the R. solani mycelium. Similar results were obtained when the organisms were incubated in the presence of [2(-14)C]mevalonate; in this case, labelled lanosterol was also detected in the R. solani mycelium. Both organisms, when incubated in the presence of unlabelled squalene, squalene epoxide or lanosterol, incorporated these compounds into their mycelia; however, only the R. solani mycelium was able to convert these substrates into products further along the sterol pathway. It appears that squalene is the terminal compound in the sterol biosynthetic pathway of P. cinnamomi.

Acetates↗
PubMed1992

The ras/cholesterol connection: implications for ras oncogenicity.

The frequent detection of mutated ras genes in a variety of cancers (reviewed in Bos, 1988, 1989; Der, 1988) suggests that ras makes a significant contribution to human malignancies (reviewed in Barbacid, 1987; Lacal and Tronick, 1988; Der, 1989). While the role of ras in malignancy is unclear, it is well-established that the association of ras protein with the inner surface of the plasma membrane is critical for triggering ras oncogenicity. The trafficking of ras proteins to the plasma membrane requires a series of three closely linked posttranslational modifications (farnesylation, proteolysis, and carboxymethylation) that are signaled by the consensus C-terminal CAAX motif present on all ras proteins (reviewed in Rine and Kim, 1990; Gibbs, 1991; Der and Cox, 1991). THe recent discovery that an essential intermediate in cholesterol biosynthesis, the isoprenoid farnesol, is attached covalently to ras proteins has stimulated considerable interest and has identified important new directions for studies of ras function. First, understanding the role of farnesol-linked interactions with the plasma membrane may identify the biochemical basis for the oncogenic actions of ras proteins. Second, the enzymes that catalyze the processing steps that trigger membrane association of ras proteins are promising targets for pharmacologic intervention in ras-associated disease. In this review, we summarize our current knowledge of the role of posttranslational processing in ras-membrane interaction and transforming activity. We also provide an update of recent studies addressing the role of isoprenoid modification in the function of ras and of other isoprenoid-modified proteins (reviewed in James and Olson, 1990; Glomset et al., 1990; Maltese, 1990). While this role is likely to be specific for each protein, ras proteins can provide an excellent prototype for understanding the role of isoprenoid modification in protein function.

Amino Acid Sequence↗
PubMed1976

Hormonal studies of uridine utilization in an insect cell line CP-1268 derived from the codling moth Laspeyresia pomonella.

Ecdysterone decreased cellular growth and the incorporation of uridine into RNA following 4 days of hormone exposure. This hormone did not affect uridine incorporation following short-term exposure up to 25 hours. Juvenile hormone and farnesol both significantly decreased uridine uptake and incorporation into RNA; however, uridine uptake was inhibited to a greater extent than uridine incorporation. Cyclic AMP increased the incorporation of uridine into RNA but had no demonstrable effect on the uptake process. This stimulation was not the result of cAMP degradation products. Cyclic AMP and ecdysterone together produced a significant increase in uridine incorporation into RNA. These studies demonstrate the potential utilization of insect cell lines for studying the mode of action of insect developmental hormones.

Cell Line↗
PubMed1992

Inhibition and activation of porcine squalene epoxidase.

Pig liver squalene epoxidase (SE) has been partially purified from solubilized microsomes by DEAE-Sephacel and Blue Sepharose 4B chromatography. This stable and reproducible preparation was used to investigate the mechanism of several substrate-like inhibitors of SE and to study the effects of pH, metals, detergents, and cofactors on enzyme activity. Most divalent (1 mM) and trivalent (0.1 mM) metal cations had little effect on SE at pH 7.4; only ferrous and cupric ions showed ca. 50% reduction in SE activity. Interestingly, at pH 8.8, EDTA (10 mM) shows 1.8-fold enhancement of enzyme activity. Among the detergents, Triton X-100 was clearly superior for solubilization and purification of porcine SE; Tween 80, Lubrol-PX, 3-[(3-cholamidopropyl)dimethylammonio]propanesulfonic acid, octyl beta-glucoside, and three different Zwittergents were much less effective for SE solubilization. Partially purified pig liver SE showed maximal activity at pH 8.8-9.0. Trisnorsqualene alcohol and trisnorsqualene cyclopropylamine were noncompetitive inhibitors at pH 8.8, with Ki values of 4 microM and 180 nM, respectively; these two inhibitors were not substrates for SE. In contrast, 26-hydroxysqualene was both a competitive inhibitor with a Ki value of 4 microM at pH 8.8 and a substrate for SE. An unexpected enhancement (up to 350%) of SE activity was observed at pH 7.4 following preincubation with selected nonpolar derivatives of farnesol and farnesoic acid. At pH 8.8, this effect was less dramatic but still evident.

Animals↗
PubMed1992

Isopentenoid synthesis in isolated embryonic Drosophila cells: absolute, basal mevalonate synthesis rate determination.

Embryonic Drosophila cells (Kc cells) and [5-3H]mevalonate (less than or equal to 10 microM) were used to determine the absolute basal in vivo rate of total mevalonic acid synthesis/utilization. An absolute in vivo mevalonic acid synthesis rate of 0.69 nmol/h/mg total cell protein was measured. Absolute mevalonate utilization was obtained by correcting for the extent of endogenous dilution of exogenous [3H]mevalonate at isotopic equilibrium. Cellular [3H]farnesol specific radioactivity was used as representative of a rapidly turning over isopentenoid pool. Although our previous Kc cell study (Havel, C. M., Rector, E. R. II, Watson, J. A., 1986, J. Biol. Chem. 261, 10,150-10,156) demonstrated that greater than or equal to 40% of the metabolized [3H]mevalonate appeared as 3H-labeled media water, this report established that t,t-3,7,11-[3H]trimethyl-2,6,10-dodecatriene-1,12 dioic acid was also secreted. Media accumulation of the C15-alpha,omega-prenyl dioic acid and 3H2O was related directly to [3H]mevalonic acid availability. This is the first mevalonate carbon balance study reported for a eukaryotic organism. It was concluded that (i) Kc cells synthesized more mevalonate than needed for normal growth and essential isopentenoids and (ii) excess mevalonate carbon accumulated intra- and extracellularly as isopentenoid compounds distal to C5 products. Finally, this study emphasized the need to measure total mevalonate utilization and not mevalonate conversion to a single isopentenoid end product in carbon balance investigations.

Animals↗