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Achlya

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Thomas J Mullins – 1st expert on this subject based on the ideXlab platform

  • sexual morphogenesis in Achlya ultrastri induction of antheridial hyphae water molds steroid hormones vesicles freeze etching
    , 2016
    Co-Authors: Thomas J Mullins, Ann E Ellis

    Abstract:

    Male strains of the water mold Achlya ambisexualis produce antheridial hyphae in response to the steroid hormone antheridiol. The antheridial hypha is postulated to be initiated through a localized wall softening with the enzyme cellulase. Freeze-etch studies of hormone-treated hyphae were conducted to determine if aggregates of vesicles are induced at the location of new antheridial hyphae. Localized aggregates of vesicles were found in conjunction with areas of wall thinning. These data suggest that the processes of vesiculation and secre- tion provide a mechanism for concentration of cellulase at the site of initiation of antheridial hyphae. A distinctive pattern of sexuality characterizes heterothallic members of the biflagellate water molds, such as Achlya ambisexualis Raper. In this species, sexual morphogenesis is initiated and sequentially controlled by a series of diffusible

  • glucan 1 3 beta glucosidase activities of Achlya bisexualis synthesis and properties
    Mycologia, 1999
    Co-Authors: Xin Du, Thomas J Mullins

    Abstract:

    Glucan 1,3-13-glucosidase activity in Achlya bisexualis increases dramatically during carbon star- vation, in agreement with results from other micro- organisms. This response in Achlya, however, is elim- inated when phosphate limitation is imposed. Under this condition even higher enzyme activities are pro- duced in the presence of glucose. A series of chro- matography procedures has purified a 1,3-f3-glucosi- dase activity with a 30 kDa protein, as judged by SDS- PAGE electrophoresis, which has a Km of 0.67 mg mL-1 for laminarin. The substrate specificity is nar- row, with the best activity against laminarin and the neutral 1,3-p3-glucan reserve of Achlya. The pattern of hydrolysis is that of an exocleavage, the initial product was mainly glucose and with additional in- cubation time only glucose. This is a key enzyme ac- tivity for the release of glucose from the neutral 1,3- 13-glucan reserve during Ca2+-induced sporulation.

  • ca2 induced sporulation in Achlya bisexualis reserve 1 3 beta glucans provide both carbon and phosphorus
    Mycologia, 1998
    Co-Authors: Xin Du, Thomas J Mullins

    Abstract:

    Reserve water-soluble 1,3-3-glucans represent some 13% (wt/wt) of the mycelial dry weight of Achlya, and consist of a small neutral form and a very large phosphorylated one. The phosphoglucan appears to be formed via aggregation of neutral molecules by phosphodiester linkages. Asexual sporulation in Achlya bisexualis, induced by 0.5 mM Ca2+, was accompanied by a 43% reduction in total glucan after 4 h, and the ratio of neutral glucan to phosphoglucan changed between 4 and 12 h. Phosphate content of the phosphoglucan declined by 50%, but the molecular size remained large and the ratio of monoand diester linkages changed only slightly. Appropriate enzyme activities of {3-glucanase and phosphoesterases capable of releasing both glucose and phosphate were found, and are described.

Alexandra Shapiro – 2nd expert on this subject based on the ideXlab platform

  • Localization of cytoplasmic water-soluble reserve (1→3)-β-glucans in Achlya with immunostaining
    Mycologia, 2018
    Co-Authors: Alexandra Shapiro, J. Thomas Mullins

    Abstract:

    AbstractThe cytoplasmic water-soluble reserve (1→3)-β-glucans of Achlya are of two types: a small neutral and a large phosphorylated. These glucans have been localized using indirect immunolabellin…

  • localization of cytoplasmic water soluble reserve 1 3 β glucans in Achlya with immunostaining
    Mycologia, 1997
    Co-Authors: Alexandra Shapiro, Thomas J Mullins

    Abstract:

    AbstractThe cytoplasmic water-soluble reserve (1→3)-β-glucans of Achlya are of two types: a small neutral and a large phosphorylated. These glucans have been localized using indirect immunolabellin…

Julie C Silver – 3rd expert on this subject based on the ideXlab platform

  • molecular cloning and characterization of two different cdnas encoding the molecular chaperone hsp90 in the oomycete Achlya ambisexualis
    Fungal Genetics and Biology, 2004
    Co-Authors: Shelley A Brunt, Julie C Silver

    Abstract:

    Abstract The chaperone Hsp90 plays a key role in the maturation and activation of many ‘client’ proteins in eukaryotic cells. In the oomycete Achlya ambisexualis two populations of hsp90 transcripts that differ slightly in size (2.8 and 2.9 kb) are present in heat-shocked mycelia. Only the 2.8 kb transcripts are seen in vegetative mycelia and in mycelia undergoing antheridiol-induced differentiation. Two different hsp90 cDNAs were isolated and characterized. Although nearly identical, an additional eight nucleotide sequence was present at the end of the 3′UTR of one of the two cDNAs. RT-PCR analyses indicated that hsp90 transcripts containing the eight nucleotide extension, were present only in heat-shocked mycelia. Hsp90 transcripts lacking this sequence were present in vegetative mycelia and the levels of these transcripts increased in both heat-shocked and hormone-treated mycelia. Each hsp90 cDNA encoded a nearly identical Hsp90 protein. However, two Hsp90 proteins (86 and 84 kDa) were observed on immunoblots of mycelial proteins. Only one of these, i.e., the 86 kDa protein was detected by an anti-phosphoserine antibody, suggesting that the difference in mass of the two Hsp90 isoforms, was due at least in part, to different levels of phosphoserine residues. Index descriptors: Hsp90; Chaperones; Steroid hormone; Antheridiol; Heat shock protein; Achlya; Oomycete

  • hsp90 containing multiprotein complexes in the eukaryotic microbe Achlya
    Cell Stress & Chaperones, 1998
    Co-Authors: Shelley A Brunt, David O. Toft, Gary H Perdew, Julie C Silver

    Abstract:

    In the oomycete fungus Achlya ambisexualis, hyphae of the male strain undergo sexual differentiation in the presence of the steroid hormone antheridiol. Earlier studies demonstrated that antheridiol binds with high affinity to a 9S multiprotein complex from A. ambisexualis cytosols. Although these complexes were found to contain the heat shock protein Hsp90, the other components were not known. It was of interest to determine if any of the other protein components in the Achlya Hsp90-heterocomplexes would be homologous to those found in the steroid receptor-Hsp90-heterocomplexes of vertebrates. Cytosolic proteins of 110 kDa, 74 kDa, 64 kDa, 61 kDa, 56 kDa, 47 kDa, 27 kDa and 23 kDa, were found in repeated trials, to co-immunoprecipitate with Achlya Hsp90. The 74 kDa protein was identified as the heat shock protein Hsp70, the 23 kDa protein was found to be related to the vertebrate protein p23 and the 56 kDa protein was found to be related to immunophilin FKBP51. All three of these proteins are components of the vertebrate receptor heterocomplexes. The 110 kDa, 61 kDa and 27 kDa proteins appeared to be unique to the Achlya complexes. Unlike the seven other proteins co-immunoprecipitating with Hsp90, the 61 kDa protein was observed only in the co-immunoprecipitates produced from in vitro translates of RNA isolated from antheridiol-treated mycelia.

  • molecular cloning and characterization of two distinct hsp 85 sequences from the steroid responsive fungus Achlya ambisexualis
    Current Genetics, 1991
    Co-Authors: Shelley A Brunt, Julie C Silver

    Abstract:

    In Achlya ambisexualis, hsp85 is one of the characteristic mycelial heat shock proteins induced in response to a rapid elevation in temperature (Silver et al. 1983). This heat shock protein has the same electrophoretic mobility on two-dimensional gels and is antigenically related to an 85 kDa steroid hormone-regulated protein which constites a component of the putative Achlya steroid hormone-receptor complex. We report here the isolation of two distinct, yet highly related, hsp85 gene sequences from Achlya genomic libraries. Northern analyses, using these two Achlya genomic sequences as probes, suggest that there are two hsp85 message population in Achlya and that at least one of these is regulated by the steroid hormone antheridiol.