Sterol Requirement for Zoospore Formation in the Mosquito-Parasitizing Fungus<i>Lagenidium Giganteum</i>

Domnas, A.; Srebro, J. P.; Hicks, B. F.

doi:10.1080/00275514.1977.12020142

Cited by 29 publications

(12 citation statements)

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“…Requirements for sterols have also been documented for asexual (11) and sexual (30) reproduction by the facultative mosquito parasite Lagenidiim ,ngiganteuim (Oomycetes:Lagenidiales), which cannot synthesize these compounds (60).…”

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confidence: 99%

Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Kerwin

Duddles

1989

J Bacteriol

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Several genera of oomycete fungi which are incapable of de novo sterol synthesis do not require these compounds for vegetative growth. The requirement for an exogenous source of sterols for sexual reproduction by several members of the Pythiaceae has been questioned by reports of apparent induction and maturation of oospores on defined media supplemented with phospholipids in the absence of sterols. A more detailed examination of this phenomenon suggested that trace levels of sterols in the inoculum of some pythiaceous fungi act synergistically with phospholipid medium supplements containing unsaturated fatty acid moieties to induce oosporogenesis. Phospholipid analysis of one species, Pythium ultimum, suggested that only the fatty acid portion of the exogenous phospholipid is taken up by the fungus. Enrichment of the phospholipid fraction of total cell lipid of P. ultimum with unsaturated fatty acids promoted oospore induction, and enhanced levels of unsaturated fatty acids in the neutral lipid fraction increased oospore viability. For some pythiaceous fungi, the levels of sterols required for the maturation of oospores with appropriate phospholipid medium supplementation suggest that these compounds are necessary only for the sparking and critical domain roles previously described in other fungi.

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confidence: 99%

Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Kerwin

Duddles

1989

J Bacteriol

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“…Lagenidium giganteum is another Oomycete, but of the Lagenidiales, that requires exogenous sterols to produce zoospores (9). Warner and Domnas (10) have shown that this organism converts cycloartenol, but not lanosterol, to cholesterol.…”

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confidence: 99%

Cycloartenol-derived sterol biosynthesis in the Peronosporales

Warner¹,

Eierman²,

Sovocool³

et al. 1982

Proc. Natl. Acad. Sci. U.S.A.

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Selected species of the order Peronosporales, which are unable to epoxidize squalene and thus synthesize sterols, are able to metabolize exogenous cycloartenol to lanosterol and in some organisms to fucosterol, ergosterol, and cholesterol. Lanosterol was less effectively utilized but some ergosterol and cholesterol were yielded. Fucosterol was very efficiently metabolized by most species to ergosterol, A7-ergostenol, A5-ergostenol, cholestanol, and cholesterol. Several unknown sterols were observed in most trials. These data suggest a vestigial sterol synthetic pathway derived from cycloartenol, followed by possible isomerization to lanosterol and then to other sterols.It has been established that species of Pythium and Phytophthora require exogenous sterols for sexual reproduction (1, 2). These organisms are unable to synthesize sterols because of a missing squalene epoxidase (3). Metabolism of exogenous sterols has been observed in Phytophthora cactorum by Langeake (4), who reported possible conversion of lanosterol to cholesterol. Nes and Patterson (5) reported that Phyt. cactorum was unable to transform cycloartenol or lanosterol to other sterols. Conversion ofA7 and A5'7 sterols to A5 sterols has been reported by Elliott and Knights (6) in Phyt. cactorum, which additionally synthesizes cholesteryl esters, cholesteryl glucosides, and acyl sterol glycosides (7,8). Other than the above, sterol conversions in Phytophthora or Pythium have, in general, not been demonstrated in detail.Lagenidium giganteum is another Oomycete, but of the Lagenidiales, that requires exogenous sterols to produce zoospores (9). Warner and Domnas (10) have shown that this organism converts cycloartenol, but not lanosterol, to cholesterol. Because Lagenidium species are able to metabolize cycloartenol, it was ofconsiderable interest to observe ifthis compound could be metabolized by selected species ofthe Peronosporales. This article reports our observations. Inoculation and growth were as described (10) (10) and the unsaponifiable lipid fraction was obtained. The sterols were separated on HPLC with a Waters instrument by using a 10-,um C18 column (4.6 x 250 mm). Fractions were eluted with methanol/H20 (96:4) at 2 ml/min flow with UV detection at 210 nm. MATERIALS AND METHODS MicroorganismsSterols were identified by gas/liquid chromatography on 3% SE-30 and 1% QF-1 with a Packard 417 FID chromatograph as described (10). Confirmation ofidentification was obtained with gas chromatography/electron impact mass spectroscopy (70 eV) with a Finnegan 4023 instrument. A 15-m flexible fused silica capillary coated with OV-101 was programmed from 160 to 2600C at 10°C/min with an initial hold of 3 min. RESULTSNo sterols were found in control organisms to the limit of detection (0.0001%). Uninoculated control cultures yielded a stoichiometric recovery of the administered sterols.Sterols Isolated After Administration ofCycloartenol. Table 1 illustrates the substances identified in the organisms examined. Clear evidence was obtained for the ...

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“…To what extent they really need these molecules is an open question. For several decades it has been considered that the pythiaceous Pythium and Phytophthora spp as well as the mosquito parasitizing Lagenidium giganteum require sterols for an efficient growth and for sexual or asexual reproduction [63][64][65]. This is partially true.…”

Section: Sterols In Oomycete Physiologymentioning

confidence: 84%

Involvement of lipid-protein complexes in plant-microorganism interactions

Blein¹

2002

OCL

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Summary : Increasing concerns about the environmental impact of modern agricultural have prompted research for alternate practices to pesticide treatments, notably using plant defense mechanisms. Thus, isolation and characterization of plant defense elicitors have been the main step of studies in many groups. Moreover, in the global concept of interactions between organisms and their environment, a major concern is to discriminate recognition between exogenous and endogenous signals, notably during pathogenic or allergenic interactions involving small proteins, such as elicitins or lipid transfer proteins (LTPs). Elicitins and lipid transfer proteins (LTP) are both able to load and transfer lipidic molecules and share some structural and functional properties. While elicitins are known as elicitors of plant defense mechanisms, the biological function of LTPs is still an enigma. They are ubiquitous plant proteins able to load and transfer hydrophobic molecules such as fatty acids or phospholipids. Among them, LTPs1 (type 1 lipid transfer proteins) constitute a multigenic family of secreted plant lipid binding proteins that are constitutively expressed in specific tissues and/or induced in response to biotic and abiotic stress (for reviews [1][2][3][4]). Their biological function is still unknown, even if some data provide arguments for a role of these proteins in the assembly of extracellular hydrophobic polymers (i.e., cutin and suberin) [2,4] and/or in plant defense against fungal pathogens [1,3]. Beside their involvement in plant defense, LTPs1 are also known to be pan-allergens of plant-derived foods [5]. Finally, the discovery of the sterol carrier-properties of elicitins has opened new perspectives dealing with the relationship between this function and the elicitor activity of these small cystein-rich proteins. Nevertheless, this elicitor activity is restrained to few plant species, and thus does not appear in accordance with a universal lipid transfer function. These considerations required a reassessment of the precise role of elicitins for both fungi and plants [6].Résumé : La stimulation des mécanismes naturels de défense des plantes représente une stratégie alternative à l'utilisation de la lutte chimique en phytoprotection. Dans ce contexte, les élicitines, qui sont de petites protéines sécrétées par des Phytophthora et des Pythium, induisent une réaction de type hypersensible chez des plantes comme le tabac. Ces plantes deviennent résistantes à l'agression de leurs agents pathogènes. La récente découverte que les élicitines sont des protéines de transfert de stérols a apporté une vue nouvelle sur l'activité moléculaire des élicitines. Élicitines et protéines de transfert de lipides (LTP) sont capables de charger et de transporter des molécules lipidiques et partagent des caractères communs tant au plan structural que fonctionnel mais, tandis que les élicitines sont connues pour leur activité élicitrice de réaction de défense chez les plantes, l'activité biologique des LTP reste inconnue. Cependant, ...

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Sterol Requirement for Zoospore Formation in the Mosquito-Parasitizing FungusLagenidium Giganteum

Cited by 29 publications

References 15 publications

Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Cycloartenol-derived sterol biosynthesis in the Peronosporales

Involvement of lipid-protein complexes in plant-microorganism interactions

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