Achlya Americana Research Articles

Achlya americana

This datasheet on Achlya americana covers Identity, Distribution.

Characterization of Achlya americana and A. bisexualis (Saprolegniales, Oomycota) Isolated from Freshwater Environments in Korea

Many members of the Saprolegniales (Oomycete) cause mycoses and disorders of fishes, of which Achlya and Saprolegnia are most ubiquitous genera worldwide. During a survey of the diversity of freshwater oomycetes in Korea, we collected seven isolates of Achlya, for which morphological and molecular phylogenetic analyses enabled them to identify as Achlya americana and Achlya bisexualis. In Korea, only a species of Achlya, A. prolifera, has been previously found to cause seedling rot on rice (Oryza sativa), but none of the two species have been reported yet. Importantly, A. bisexualis was isolated from a live fish, namely rice fish (Oryzias sinensis), as well as freshwater, and this is the first report of Achlya-causing mycoses on freshwater fishes in Korea. The presence of A. americana and A. bisexualis on live fish in Korea should be closely monitored, as considering the well-known broad infectivity of these species it has the potential to cause an important emerging disease on aquaculture industry.

Studies on toxicity of selected Oomycetes

The MTT test is used to determine the cytotoxicity of species: <em>Achlya americana, A. caroliniana, Leptomitus lacteus, Saprolegnia ferax</em> and <em>S. lapponica</em>, which occurred in Lake Sitno in the Drawieński National Park (W Poland). It was stated that among five examined species of zoosporic fungi only one of them <em>A. caroliniana</em>, does not show cytotoxic effect. Low and mean toxicity of other tested water FLO, however, combined with the large-scale character of their appearance shows, that they can create serious threat for the spawn, fry, fish as well as the other organisms (including invertebrates) existing in water.

Aquatic fungi and straminipilous organisms in lakes of the Augustowska Primeval Forest, Poland

Abstract We analyzed species composition of aquatic fungi and straminipilous organisms in six lakes located within the Augustowska Primeval Forest, Poland. Mycological observations conducted in the spring and autumn seasons together with hydrochemical analysis in the 2010–2012 revealed the presence of 44 species (10 aquatic fungi and 34 straminipilous organisms). Among the taxa detected, there were some potential pathogens of economically valuable fish species and spawn, including Achlya americana, Ac. polyandra, Saprolegnia ferax and S. parasitica. Some of the species were crustacean pathogens, such as Lagenidium giganteum, Myzocytium microsporum and M. zoophthorum. There were also some common human pathogens Aspergillus niger and Candida tropicalis. Some species, such as Achlya klebsiana, Ac. prolifera, Nowakowskiella elegans, N. macrospora, Pythium debaryanum, Py. inflatum, Rhizophlyctis rosea and Saprolegnia litoralis were common phytosaprobionts. The largest number of species of fungi and straminipilous organisms was identified in Lake Sajenek (22), the fewest in Lake Białe (12). The quantitative composition and qualitative differentiation of mycobiota were influenced by the content of biogenic compounds and the amount of organic substance. The elevated levels of these parameters (Lake Sajenek) stimulated the growth of fungi and straminipilous organisms, whereas very low concentrations of biogenic compounds and a small amount of organic matter (Lake Białe) had an inhibitory effect. Statistical analysis of the results was conducted to determine the correlations between the number of fungal and straminipilous species and the hydrochemical parameters, i.e. water temperature, the level of nitrogen compounds (nitrate nitrogen, ammonium nitrogen), calcium carbohydrate, magnesium carbohydrate, water oxidizability and the content of dry residue, dissolved substances and suspension.

* and

Mycological and ecological studies have been carried out at four stations of Sarchnar water spring: (Sarchnar spring pools, Sarchnar district waste water, Chaq Chaq stream (industrial water) and confluence of these three stations, Selected within Sulaimani Governorate during April to August 2008.Certain physico-chemical parameters of water were perforormed using standard methods. The first investigation of total of twelve aquatic fungus species from 163 isolates was reported.Eleven species were identified in which 8 of them belonging to the family Saproleginaceae including, Achlya americana, A. apiculata, A. racemosa, Saprolegnia ferax, S. parasitica and S. litoralis and 2 species of Aphanomycese laevis and Aphanomycese stellates, three an identified species belonging to each of the familes Leptomitaceae, Pythiaceae and Blastocladiaceae which including Leptomitus sp, Pythium s p and Allomyces sp respectively, and one species of Chytrid which belongs to the class Chytridiomycota were recorded. Sarchnar spring pool was the richest station with aquatic fungus species, while Sarchnar district sewage water was the poorest station. Some physico-chemical parameters showing a significant relationship to the fungal occurrence and distributions.

Diversity and dynamics of the fungal community in Lake Ohrid

Fungi are universally present in freshwater systems and are of great significance in the structural and functional organization of these ecosystems. The aim of this study was to assess the diversity of fungal communities in the ancient, oligotrophic Lake Ohrid and to investigate their spa- tial and temporal dynamics. The fungal community in Lake Ohrid consists of 36 species identified from 213 isolates. The autochthonous community is made up of 10 species belonging to the orders Saprolegniales and Peronosporales: Achlya americana, A. racemosa, Aphanomyces leavis, Dic- tyuchus monosporus, D. sterile, Pythium ultimum, Saprolegnia ferax, S. hypogina, S. monoica, and Saprolegnia sp. The allochthonous community is composed of 26 species from 15 genera of fungi. The dominant genera are Aspergillus (5 species, 13.86% of determined species), Penicillium (6 species, 16.66%), and Cladosporium and Fusarium (3 species, 8.33%). The species Kloeckera apiculata, Didiostible sp., Gliocladium roseum, and Varicosporium delicatum are identified here for the first time in freshwater ecosystems of the Balkans. Quantitative analysis of the fungal community showed that the number of propagules varied in the range of 0 to 19.5 × 10 3 l -1 . The diversity and abundance of both the autochthonous and the allochthonous fungal communities are greater in the littoral than in the pelagial zone. Our results represent the first hydromycological data for Lake Ohrid the region of Macedonia.

Studies on parasitic watermolds of Kumaun Himalaya; host range of Achlya americana Humphrey, on certain temperate fish.

Summary: Achlya americana Humphrey was found as a naturally occuring parasite of Carassius auratus L. for the first time. The pathogen extended its host range on six other cold water fish of Kumaun viz., Cyprinus carpio var. communis L., Puntius conchonius Ham., P. ticto Ham., Schizothorax plagiostomus Heckel, S. richardsoni Gray & Hard. and Tor tor Ham., by artificial inoculation experiments under the controlled laboratory conditions whereas Nemacheilus rupicola Mc Cle. was found immune to this fungus. Zusammenfassung: Achlya americana Humphrey wurde als natürlich vorkommender Parasit zum ersten Mal bei Carassius auratus L. gefunden. Der pathogene Pilz erwies sich jedoch auch als Parasit bei 6 weiteren Kaltwasserfischen in Kumaun, nämlich Cyprinus carpio var. communis L., Puntius conchonius Ham., P. ticto Ham., Schizothorax plagiostomus Heckel, S. richardsoni Gray & Hard. und Tor tor Ham., wenn eine künstliche experimentelle Beimpfung unter kontrollierten Laboratoriumsbedingungen vorgenommen wurde. Im Gegensatz dazu war Nemacheilus rupicola Mc Cle. immun gegen den Pilz.

Mycobiota associated with larval mines of Thrypticus truncatus and T. sagittatus (Diptera, Dolichopodidae) on waterhyacinth, Eichhornia crassipes, in Argentina

Abstract Thrypticus truncatus is a candidate agent for biocontrol of waterhyacinth; the larvae of this diptera mine in the petioles and feed on the phloem in the vascular bundles. The mycobiota associated with T. truncatus and T. sagittatus mines was investigated during two surveys undertaken in the spring and autumn in the Delta of the Parana River, Argentina. Isolations were made from the mines and larval feeding points, as well as from the larvae, following dissection of the petioles, and plated onto agar. Young and upper parts of the petioles without Thrypticus mines were used as controls. Twenty eight fungal species were isolated from the mines. Pestalotiopsis guepinii , Mucor attenuatus, Phoma tropica, Achlya americana, Fusarium avenaceum, Cladosporium cladosporioides , Clonostachys rosea, Epicoccum purpurascens, Plectosporium tabacinum, Alternaria alternata, and Acremonium sp. were the most common fungi associated with mines and feeding points. Cladosporium cladosporioides , Cytospora sp., Mucor attenuatus, and Phoma tropica were associated with the larval body. The list of fungi in mines was compared with bibliographic information to determine if the species are known pathogens on waterhyacinth or other plant species. This is the first study on mycobiota associated with T. truncatus and T. sagittatus mines in waterhyacinth petioles in Argentina.

Effect of Benomyl Treated Garlic on Growth and Sporulation of Pythium aphanidermatum and Achlya americana

Effect of Benomyl Treated Garlic on Growth and Sporulation of Pythium aphanidermatum and Achlya americana

Five Serbian reservoirs contain different fungal propagules

This paper presents results of a mycological survey conducted in five large reservoirs in Serbia (Sjenica, Barje, Garaši, Meðuvršje and Ovčar-Kablar) that have different hydrobiological and production characteristics. The sampling was conducted in March, June, August and October 2002. Quantitative analysis of fungal communities showed that the average number of colony-forming units in these reservoirs was 1966–5682/L of water. The highest number of CFUs was found in the α-mesosaprobic (Class III) Ovčar-Kablar Reservoir and the lowest was in the oligosaprobic (Class I) Sjenica Reservoir. CFUs were higher in samples taken near lake bottoms and in littoral zones rich with macrovegetation than in the middle depths. In these reservoirs 48 species were identified from 720 isolates. The dominant genera were Penicillium, Aspergillus, Cladosporium, Fusarium, Rhizopus, Mucor, Phoma and Verticillium. The autochthonous aquatic fungal community comprised these species: Achlya americana, A. diffusa, A. racemosa, Dictyuchus sterile, Isoachlya toruloides, Leptomitus lacteus, Pythium ultimum, Saprolegnia ferax, S. hypogyna and S. monica. My results indicate that aquatic fungi on the whole are better represented in lakes with a higher trophic status.

Zoosporic aquatic fungi growing on avian excrements in various types of water bodies

Coprophilic fungi in the water from six different water bodies were studied between 1995–1997. For hydrochemical analysis samples of water were collected every three months while for estimation of fungus content every month. Excrements of 3 phytophagous (greylag goose, roman-nosed goose, mute swan), 4 carnivorous (grey heron, white stork, marsh harrier, cormorant) and 3 omnivorous bird species (musk-duck, mallard, black-headed gull) were used as bait. Thirty-six fungus species growing on avian excrements in the water of all examined water bodies were found, 6 of these species belonged to Chytridiomycetes and 30 to Oomycetes. The largest number of fungus species was detected on excrements of musk duck, mallard and mute swan, the smallest one on excrements of roman-nosed goose, marsh harrier and cormorant. Such fungus species as Achlya americana, Aphanomyces laevis, Dictyuchus monosporus, Pythium debaryanum, Pythium rostratum, Saprolegnia asterophora, Saprolegnia ferax and Saprolegnia parasitica were detected on excrements of all birds examined. Out of these 36 species, 11 are known as parasites or necrotrophs of fish. Rhizophydium ampullaceum and Diasporangium jonesianum are reported for the first time from Poland.

Cyclic nucleotides modulate lipoxygenase activity and reproduction in oomycetes

Previous studies in our laboratory demonstrated that epoxy alcohols produced from C 20 fatty acids by lipoxygenase activity are associated with maintaining vegetative growth. We have also shown the specific down-regulation of lipoxygenase activity in reproductively competent oomycetes in response to cues which trigger reproduction. Other workers have suggested that cyclic nucleotides may also play a role in the switch between vegetative and reproductive growth of fungi. Reproductive activity was assayed in Achlya americana. Oogonium production was eliminated or reduced in the presence of cAMP, dibutyryl cAMP (0.5 m M), or the phosphodiesterase inhibitors caffeine (0.1, 1 m M) and theophylline (1 m M) and increased by 0.5 m M cGMP. Levels of cAMP were significantly higher in vegetative mycelium and were increased fourfold by exposure to 0.1 m M caffeine. These data suggest that an accumulation of cAMP inhibits reproductive activity while cGMP promotes it. Lipoxygenase activity was determined in the presence of cAMP, cAMP phosphodiesterase inhibitors, and cGMP to determine the interaction between cyclic nucleotides and lipoxygenase activity. Lipoxygenase activity in reproductive mycelium of A. americana or Saprolegnia ferax was reduced compared to vegetative mycelium. Lipoxygenase activity of cultures grown and starved in the presence of cAMP (0.5 m M) or caffeine (0.1 m M) showed significant increases over the comparably treated reproductive controls. Exposure to cGMP had no affect on lipoxygenase activity in A. americana. These data suggest that cAMP may maintain vegetative growth by maintaining relatively high lipoxygenase activity levels while the reproduction promoting effect of cGMP is not via lipoxygenase activity down-regulation. Adenylate cyclase activity was significantly higher in vegetative, compared to reproductive, mycelium of both A. americana and S. ferax. Elevated adenylate cyclase activity in vegetative mycelium supports the hypothesis that cAMP maintains vegetative growth by maintaining high lipoxygenase activity.

The effect of heavy metals on Achlya Americana var. cambrica trow

Abstract The effect of Copper, Cadmium and Nickel on Mycelial growth, time for sporogenesis, sporangial density, time for oogenesis and oogonial density of Achlya americana var. Cambrica Trow was studied. The concentrations used of each metal are 0.25 , 0.5 , 0.75 , 1.0 , 1.25 , 1.5 ppm. Cd delayed the appearance of sporangia but increased the sporangial density, Cu has similar effect, Ni delayed the appearance of sporangia and decreased the density of the sporangia at the same time, both of Cd and Cu shortened the time needed for oogenesis and increased the density of oogonia while Hi delayed the appearance of oogonia but poaativly effected the density of oogonia. Colony diameter dropped significantly at the presence of Cd, Hi but was not effected by the presence of Cu, the percentage of abnormal sporangia increased in the presence of Cd,Ni, & Cu.

Phylogenetic implications of sterol biosynthesis in the oomycetes

The effects of two fungicides, triarimol and tridemorph, on sterol biosynthesis were examined in Achlya americana, Dictyuchus monosporous, Apodachlyella completa, and Lagenidium callinectes. Cultures grown in the presence of triarimol accumulated lanosterol, with the exception of Lagenidium which had inconclusive results. All tridemorph-treated cultures accumulated Δ 8-sterols, including zymosterol, fecosterol, and stigmasta-8, E-24(28)-dienol. Results point to the intermediacy of lanosterol but not cycloartenol in sterol biosynthesis in the Oomycetes. These data suggest that the evolution of the Oomycetes from photosynthetic algal ancestors is unkikely.

Lipid composition and metabolism in oospores and oospheres of Achlya americana

Oospores and oospheres of Achlya americana Humphrey were isolated by sonication and filtration through nylon-mesh cloth of progressively diminishing porosity, and their lipid composition was investigated. The average dry weight of an oospore was 3.2 ng. Approximately 37% of the dry weight was composed of lipid. Triacylglycerols represented 88.7% of the total lipid, unesterified fatty acids made up 9.7%, and sterols, sterol esters, phospholipids, and mono- and diacylglycerols each constituted less than 1% of the total. Palmitic, oleic, and linoleic acids were the predominant fatty acids, along with smaller amounts of myristic, palmitoleic, stearic, arachidonic, and eicosapentaenoic acids. The fatty acid composition of the triacylglycerol fraction was similar to that of the total lipid, while that of the phospholipid fraction was higher in oleic acid. The unesterified fatty acid fraction was higher in saturated components than the total lipid, while the sterol ester fraction was higher in unsaturated fatty acids. In both the total lipid and the various lipid classes, unsaturated fatty acids increased during spore development. The sterol fraction consisted of 72% fucosterol, 22% cholesterol, and 7% 24-methylenecholesterol. In both oospheres and oospores, 1-[ 14C] acetate was assimilated most readily into phospholipids, triacylglycerols, and unesterified fatty acids, and was incorporated preferentially into palmitic, palmitoleic, and oleic acids. 1-[ 14C]-Arachidonic acid was incorporated by isolated oospheres into eicosapentaenoic acid, indicating that arachidonic acid is the immediate precursor of eicosapentaenoic acid.

The distribution of Achlya americana (Saprolegniales) in different aquatic habitat at Jabalpur, India

Distribution of the watermould Achlya americana in Jabalpur, India, was investigated. The influence of temperature, pH, BOD, CO2 and pollution is discussed.

The Cellulolytic Activity of Six Oomycetes

A review of the literature has shown a need for further investigation of the physiology of aquatic Phycomycetes and in particular the Oomycetes. Most investigations have dealt primarily with their morphology, taxonomy, and geographical distribution (1, 5, 6). However, their importance in decomposition and simplification of organic matter, especially when compared with bacteria and protozoa, is still an unanswered question (6). One of the most important structural polysaccharides of the plant kingdom is cellulose. The degradation of cellulose is often discussed in connection with the action of fungal parasites. The ability of Oomycetes to produce cellulolytic enzymes has been infrequently investigated (1, 5, 6). In addition, most studies that are reported lack quantitative data. Unestam (7), in his quantitative study, reported no cellulolytic activity of a Pythium sp. and Saprolegnia sp. incubated in shake and stationary media containing cellulose. Preliminary investigations, of growth on a semichemically defined medium, indicated that Pythium mamnmillatum Meur, P. dissoticum Drechsler, Pythium sp., Achlya americana Humphrey, Saprolegnia parasitica Coker, and Thraustotheca clavata (de Bary) Humphrey could be utilized for a quantitative investigation of the cellulolytic activity of Oomycetes. Dr. C. L. Fergus supplied isolates Pythium mammillatum, England 1962; Pythium sp., Vaartaja; P. dissoticum, W. A. Campbell 919-2; Thraustotheca clavata, ATCC 14555. Isolates of Achlya americana and Saprolegnia parasitica were obtained from the American Type Culture Collection as ATCC 14565 and ATCC 22284 respectively. The cellulolytic activity of the fungi was determined by modifying the method described by Fergus (3). First, the ability of these six Oomycetes to utilize an insoluble form of cellulose was investigated. Filter paper (Whatman No. 3, 5.5 cm in diam) was folded, oven-dried, and weighed. Two pieces were placed in each of a number of 250-ml Erlenmeyer flasks containing 50 ml of a medium of the following composition: K2HPO4,

THE FLAGELLATION, MOVEMENT, AND ENCYSTMENT OF SOME PHYCOMYCETOUS ZOOSPORES

The anterior flagellum of the zoospores of Phytophthora fragariae, P. megasperma, P. cambivora, Saprolegnia parasitica, Achlya americana, and Pythium aphanidermatum projects straight in front of the zoospore and never moves except during encystment whereas the posterior flagellum is active during the swimming period. In the secondary zoospore the anterior and posterior flagella are attached a short distance apart in the center of the depression on the concave side and respectively pass forward and backward through a groove and form a central axis about which the zoospore rotates. Hyaline vesicles which also have been called beads or paddles form at the base of the flagella at the beginning of encystment and glide part or all the way down the flagella. Movement of flagella after they are released from the zoospore is reported for the first time. Encystment may result from contact stimulus except in the case of Allomyces anomalus. A filament on which vesicles may occur may be secreted or retracted by the Allomyces zoospore.

Sexual Hormones in Achlya. VII. The Hormonal Mechanism in Homothallic Species

1. A simple membrane technique is described for the study of diffusible sexual hormones in matings on a semisolid medium. 2. Sexual reactions have been shown to occur regularly between mated homothallic species and [male] and [female] strains of heterothallic species. All possible matings between two homothallic species, Achlya americana and Thraustotheca clavata, and [male] and [female] strains of two heterothallic species, A. bisexualis and A. ambisexualis, reveal relationships ranging from no reaction to complete compatibility, and presumably hybridization, between the two mated plants. 3. Matings between the homothallic and heterothallic species listed above, in a semisolid medium in which interposed membranes physically separate the mated plants, prove that the initiation and coordination of the sexual interactions result from diffusible hormones. 4. Assuming similar and interactive sexual hormonal mechanisms in homothallic and heterothallic species, the results of membrane matings confirm exactly the expectations based on the reactions observed in water and agar matings. 5. The effects of hormone-containing filtrates from homothallic and heterothallic species have been reciprocally determined on species showing both types of sexuality. 6. Homothallic plants react to hormone A in a quantitative pattern similar to the response of heterothallic [male]'s to hormone A plus hormone A1. Antheridial hyphal production is but little affected by hormones A1 and A2. 7. Degeneration and/or redifferentiation of oogonial initials results from high concentrations of hormone A in nine of twelve homothallic species investigated. Oogonial development, however, is normal if delimitation of the oogonium had occurred prior to the addition of the hormone. 8. Complete inhibition of oogonial initial production results from the addition of hormone A1 in three homothallic species. 9. Three homothallic species, A. americana, T. clavata, and T. primoachlya, were each shown to secrete both acetone-soluble and water-soluble (acetone-insoluble) substances capable of inducing antheridial hyphal production on [male] heterothallic plants. Each fraction, however, induces the reaction in quantitative patterns which preclude the identities of these hormones with the hormones of the A-complex from heterothallic species. 10. The conclusion is reached that homothallic species possess a hormonal mechanism similar in broad pattern to that previously demonstrated in heterothallic species, but that striking differences in detail, possibly only as regards hormonal specificities, obtain between the mechanisms characteristic of the two types of sexuality. 11. Each homothallic species possesses, in addition to the sexual capabilities requisite to its own hermaphroditism, affinities for extra-mycelial reactions, the kind and degree of which depend upon the sexual affinities of the immediate mate. Limited evidence is presented which indicates that the homothallic species studied range, as regards extra-mycelial potentialities, from strong-[male] to weak-[male]. These correspond to the predominant-[male] intergrades of heterothallic species in that they also possess weak [female] as well as [male] potentialities. 12. The possible significance of interspecific and intergeneric reactions involving homothallic species in nature is briefly discussed.

Achlya Debaryana Humphrey and the Prolifera Group

Achlya DeBaryana Humphrey is the Achlya polyandra of DeBary, not of Hildebrand, as Humphrey has shown;1 and as Hildebrand's name is the older and applies to another plant, Humphrey's name should be used. Recent writers on the morphology of this species have ignored this and still call the plant Achlya polyandra DeBary. There are now recognized three very closely related species, forming what was called by Humphrey the prolifera group, which from the work of recent writers are becoming more and more difficult to separate. They are Achlya prolifera (Nees) DeBary, A. DeBaryana Humphrey, and A. anmericana Humphrey. Humphrey was himself aware of the very close resemblances of these species and remarked upon it; but on account of DeBary's assurance of the autonomy of the first two, felt called on to continue the distinction. According to DeBary,2 A. DeBaryana (his A. polyandra) has antheridial branches that arise from the same main hyphae that bear the oogonia, and then branch and extend out to the o6gonia on the branches from which they arose (which is most common) or to o6gonia on other threads. In A. prolifera, on the other hand, he says that the antheridial branches are diclinous, always arising from other hyphae than the ones that bear the o6gonia and that all o6gonia are furnished with antheridia. He also says that while A. prolifera has o6gonia with abundant pits, the oogonia of A. DeBaryana is without them. Achlya americana has antheridial branches that arise from the same hyphae as the o6gonia, and it also has