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Sporulation
Kinds of Sporulation Terms modified by Sporulation Selected AbstractsInfection of Arceuthobium americanum by Colletotrichum gloeosporioides and its potential for inundative biological controlFOREST PATHOLOGY, Issue 5 2005T. D. Ramsfield Summary Inundative biological control of Arceuthobium americanum occurring on Pinus contorta var. latifolia with the fungus Colletotrichum gloeosporioides was investigated. Isolates of C. gloeosporioides were collected throughout British Columbia, Canada, and one isolate was selected for assessment based on its growth and sporulation in culture. The fungus was formulated using the ,Stabileze' method and inoculated onto A. americanum under field conditions. It became established on some replicates and there was a higher incidence of C. gloeosporioides on treated replicates than controls. In some replicates, the treatment reduced fruit production, leading to a decrease in the reproductive capacity of the dwarf mistletoe plant; however, the efficacy was highly variable and not significant. Résumé Une méthode de lutte biologique utilisant le champignon Colletotrichum gloeosporioides contre Arceuthobium americanum sur Pinus contorta var. latifolia a étéétudiée. Des isolats de C. gloeosporioides ont été collectés dans toute la Colombie Britannique, au Canada, et un isolat a été sélectionné pour les essais, sur la base de sa croissance et de sa sporulation en culture. La préparation fongique a été formulée en utilisant la méthode 'Stabileze' et inoculée sur A. americanum sur le terrain. Le champignon s'est établi dans quelques cas et l'incidence de C. gloeosporioides a été plus forte dans les cas traités par rapport aux témoins. Dans quelques cas, le traitement a réduit la production de fruits, conduisant à une diminution de la capacité reproductive du faux-gui, toutefois l'efficacité s'est montrée très variable et globalement non significative. Zusammenfassung Es wurde die Eignung des Pilzes Colletotrichum gloeosporioides zur biologischen Bekämpfung von Arceuthobium americanum auf Pinus contorta var. latifolia untersucht. Verschiedene Isolate von C. gloeosporioides wurden in British Columbia (Kanada) gesammelt und ein Isolat wurde aufgrund seines guten Wachstums und der Sporulation in vitro für die Inokulationsexperimente ausgewählt. Die Konidien des Pilzes wurden nach der ,,Stabileze'' Methode formuliert und im Freiland auf A. americanum inokuliert. Der Pilz etablierte sich in einigen Fällen und C. gloeosporioides kam auf den behandelten Pflanzen häufiger vor als auf den Kontrollen. Bei einigen Wiederholungen war die Fruktifikation der Mistel reduziert; allerdings war dieser Effekt sehr variabel und die Unterschied war nicht signifikant. [source] A medium to enhance identification of Septoria musiva from poplar cankersFOREST PATHOLOGY, Issue 3 2002J. C. STANOSZ A series of experiments was conducted to determine the relative tolerance in vitro of an isolate of Septoria musiva (a fungus that causes a severely damaging stem canker disease of poplars) for selected chemicals. Inhibition of diameter growth of this fungus on a V-8 vegetable juice-based medium with captan, chlorothalonil, iprodione, mancozeb and streptomycin sulphate at concentrations, respectively, of 50, 1, 10, 10, and 100 mg l,1 was relatively low compared to inhibition of eight other fungi cultured from cankers on poplars. In addition, the presence of captan stimulated profuse sporulation of the fungus. These properties assisted in the identification of S. musiva from cankers resulting from artificial inoculation of poplar branches in the field. Un milieu de culture pour aider à l'identification de Septoria musiva isolé de chancres sur peuplier Un isolat de Septoria musiva, champignon responsable de chancres de tronc sur peupliers, àété testéin vitro pour sa tolérance à un certain nombre de substances. L'inhibition de la croissance en diamètre a été déterminée sur milieu V8 additionné de captan, chlorothalonil, iprodione, mancozèbe et sulfate de streptomycine aux concentrations respectives de 50, 1, 10, 10, et 100 mg par litre; l'inhibition était relativement faible comparée à celle de huit autres champignons isolés de chancres de peuplier. La présence de captan stimulait la sporulation du champignon. Ces propriétés ont aidéà l'identification du S. musiva réisoléà partir de chancres obtenus au champ par inoculation artificielle de branches de peuplier. Ein Medium zur Verbesserung der Identifikation von Septoria musiva aus Pappelkrebsen Es wurde eine Serie von Experimenten zur Bestimmung der relativen Toleranz eines Septoria musiva Isolats (ein Erreger ausserordentlich schädlicher Stammkrebse an Pappeln) gegenüber ausgewählten Chemikalien durchgeführt. Das Wachstums des Pilzes auf einem auf V-8 Gemüsesaft basierenden Medium mit 50 mg l,1 Captan, 1 mg l,1 Chlorothalonil, 10 mg l,1 Iprodion, 10 mg l,1 Mancozeb und 100 mg l,1 Streptomycinsulfat wurde im Vergleich zum Wachstum von acht anderen Pilzarten, die ebenfalls aus Pappelkrebsen isoliert wurden, nur schwach gehemmt. Zudem regte Captan den Pilz zu intensiver Sporulation an. Als hilfreich erwiesen sich diese Eigenschaften in Feldversuchen bei der Identifikation von S. musiva aus Krebsen, die sich nach künstlicher Inokulation von Pappelzweigen entwickelten. [source] Sporulation and Germination Gene Expression Analysis of Bacillus anthracis Sterne Spores in Skim Milk under Heat and Different Intervention TechniquesJOURNAL OF FOOD SCIENCE, Issue 3 2009Y. Liu ABSTRACT:, To investigate how B. anthracis Sterne spores survive in milk under heat (80 °C, 10 min), pasteurization (72 °C, 15 s), microfiltration, and pasteurization and microfiltration, the expression levels of genes related to sporulation and germination were tested using real-time PCR assays. Twenty-seven sporulation- and germination-related genes were selected for the target genes. Our results demonstrated that gene expression levels were altered by heat and microfiltration whereas the pasteurization and pasteurization and microfiltration resulted in less alteration of gene expression. Heat activated and inhibited both sporulation- and germination-related genes, suggesting that bacterial spores underwent different molecular mechanism for heat treatments. Our results may provide some insight into the molecular mechanisms of spore survival in response to heat treatment and different intervention strategies used to treat fluid skim milk. [source] From fundamental studies of sporulation to applied spore researchMOLECULAR MICROBIOLOGY, Issue 2 2005Imrich Barák Summary Sporulation in the Gram-positive bacterium, Bacillus subtilis, has been used as an excellent model system to study cell differentiation for almost half a century. This research has given us a detailed picture of the genetic, physiological and biochemical mechanisms that allow bacteria to survive harsh environmental conditions by forming highly robust spores. Although many basic aspects of this process are now understood in great detail, including the crystal and NMR structures of some of the key proteins and their complexes, bacterial sporulation still continues to be a highly attractive model for studying various cell processes at a molecular level. There are several reasons for such scientific interest. First, some of the complex steps in sporulation are not fully understood and/or are only described by ,controversial' models. Second, intensive research on unicellular development of a single microorganism, B. subtilis, left us largely unaware of the multitude of diverse sporulation mechanisms in many other Gram-positive endospore and exospore formers. This diversity would likely be increased if we were to include sporulation processes in the Gram-negative spore formers. Spore formers have great potential in applied research. They have been used for many years as biodosimeters and as natural insecticides, exploited in the industrial production of enzymes, antibiotics, used as probiotics and, more, exploited as possible vectors for drug delivery, vaccine antigens and other immunomodulating molecules. This report describes these and other aspects of current fundamental and applied spore research that were presented at European Spores Conference held in Smolenice Castle, Slovakia, June 2004. [source] Roles of the two ClpC ATP binding sites in the regulation of competence and the stress responseMOLECULAR MICROBIOLOGY, Issue 3 2001Kürsad Turgay MecA targets the competence transcription factor ComK to ClpC. As a consequence, this factor is degraded by the ClpC/ClpP protease. ClpC is a member of the Clp/HSP100 family of ATPases and possesses two ATP binding sites. We have individually modified the Walker A motifs of these two sites and have also deleted a putative substrate recognition domain of ClpC at the C-terminus. The effects of these mutations were studied in vitro and in vivo. Deletion of the C-terminal domain resulted in a decreased binding affinity for MecA, a decreased ATPase activity in response to MecA addition and decreased degradative activity in vitro. In vivo, this deletion resulted in a failure to degrade ComK and in a decrease in thermal resistance for growth. Mutation of the N-terminal Walker A box (K214Q) caused a drastically decreased ATPase activity in vitro, but did not interfere with MecA binding. In vivo, this mutation had no effect on thermal resistance, but had a clpC null phenotype with respect to competence. Mutation of the C-terminal Walker A motif (K551Q) caused essentially the reverse phenotype both in vivo and in vitro. Although binding to MecA was only moderately impaired with 2 mM ATP, this mutant protein displayed no response to 0.2 mM ATP, unlike the wild-type ClpC and the K214Q mutant protein. The ATPase activity of the K551Q mutant protein, induced by the addition of MecA plus ComS, was decreased about 10-fold but was not eliminated. In vivo, the K551Q mutation showed a partial defect with respect to competence and a profound loss of thermal resistance. Sporulation was reduced drastically by the K551Q and less so by the K214Q mutation, but remained unaffected by deletion of the C-terminal domain. Although the evidence suggests that the functions of the two ATP-binding domains overlap, it appears that the N-terminal nucleotide-binding domain of ClpC is particularly concerned with MecA-related functions, whereas the C-terminal domain plays a more general role in the activities of ClpC. [source] Sporulation of Plasmopara viticola: Differentiation and Light RegulationPLANT BIOLOGY, Issue 3 2002J. Rumbolz Abstract: The development of grape downy mildew (Plasmopara viticola) was followed histologically during the entire latent period until the appearance of mature sporangia. Production of sporangiophores and sporangia was assessed using low-temperature scanning electron (LTSEM) and fluorescent light microscopy. Time-course studies using attached leaves of Vitis vinifera cv. Müller-Thurgau revealed that the production of sporangiophores and sporangia is a highly coordinated process and is completed within 7 h. As this differentiation is assumed to occur only in darkness, the influence of light was investigated. For this purpose, different light regimes were applied to infected leaf discs of V. viniferacv. Müller-Thurgau. White light irradiation prevented formation of sporangia, although the growth of the mycelium was not affected. Many sporangiophores were observed that were abnormally shaped, i.e., short hyphae in clusters or thin, extremely elongated hyphae. For the formation of mature sporangia, a prolonged dark period was necessary. Light experiments suggest photosensitivity at the end of the latent period. A terminal white light irradiation caused an inhibitory effect, whereas a final phase of darkness promoted sporangium development. Different light qualities were tested, revealing an inhibition of sporangium development by blue light whereas neither red nor far-red light were effective. [source] Use of monoclonal antibodies to quantify the dynamics of ,-galactosidase and endo-1,4-,-glucanase production by Trichoderma hamatum during saprotrophic growth and sporulation in peatENVIRONMENTAL MICROBIOLOGY, Issue 5 2005Christopher R. Thornton Summary Trichoderma species are ubiquitous soil and peat-borne saprotrophs that have received enormous scientific interest as biocontrol agents of plant diseases caused by destructive root pathogens. Mechanisms of biocontrol such as antibiosis and hyperparasitism are well documented and the biochemistry and molecular genetics of these processes defined. An aspect of biocontrol that has received little attention is the ability of Trichoderma species to compete for nutrients in their natural environments. Trichoderma species are efficient producers of polysaccharide-degrading enzymes that enable them to colonize organic matter thereby preventing the saprotrophic spread of plant pathogens. This study details the use of monoclonal antibodies (mAbs) to quantify the production of two enzymes implicated in the saprotrophic growth of Trichoderma species in peat. Using mAbs specific to the hemicellulase enzyme ,-galactosidase (AGL) and the cellulase enzyme endo-1,4-,-glucanase (EG), the relationship between the saprotrophic growth dynamics of a biocontrol strain of Trichoderma hamatum and the concomitant production of these enzymes in peat-based microcosms was studied. Enzyme activity assays and enzyme protein concentrations derived by enzyme-linked immunosorbent assay (ELISA) established the precision and sensitivity of mAb-based assays in quantifying enzyme production during active growth of the fungus. Trends in enzyme activities and protein concentrations were similar for both enzymes, during a 21-day sampling period in which active growth and sporulation of the fungus in peat was quantified using an independent mAb-based assay. There was a sharp increase in active biomass of T. hamatum 3 days after inoculation of microcosms with phialoconidia. After 3 days there was a rapid decline in active biomass which coincided with sporulation of the fungus. A similar trend was witnessed with EG activities and concentrations. This showed that EG production related directly to active growth of the fungus. The trend was not found, however, with AGL. There was a rapid increase in enzyme activities and protein concentrations on day 3, after which they remained static. The reason for the maintenance of elevated AGL probably resulted from secretion of the enzyme from conidia and chlamydospores. ELISA, immunofluoresence and immunogold electron microscopy studies of these cells showed that the enzyme is localized within the cytoplasm and is secreted extracellularly into the surrounding environment. It is postulated that release of oligosaccharides from polymeric hemicellulose by the constitutive spore-bound enzyme leads to AGL induction and could act as an environmental cue for spore germination. [source] SIMPEROTA 1/3 , a decision support system for blue mould disease of tobacco,EPPO BULLETIN, Issue 2 2007P. Racca Blue mould (Peronospora tabacina) is the most serious threat to German tobacco crops. In order to efficiently control the disease whilst minimizing the risk of nontolerable fungicide residue levels on tobacco leaves, a decision support system has been developed which optimizes the timing of fungicide treatments. The DSS consists of two models, SIMPEROTA 1, which forecasts the dates of blue mould first appearance and SIMPEROTA 3 which forecasts the dates of fungicide applications. Crucial biological processes are included in the models (infection, mycelium growth, sporulation and spore release). Input parameters are temperature, relative humidity and leaf wetness recorded on an hourly basis. Validation with data from 2003 and 2006 showed that SIMPEROTA 1 gave satisfying results. The model is suitable for practical use and can be employed for steering monitoring efforts of extension services and for the timing of the first fungicide treatment. SIMPEROTA 3 gives advice on follow-up treatments and the length of spraying intervals, but this model needs to be validated before being introduced into practice. [source] Promoters of crystal protein genes do not control crystal formation inside exosporium of Bacillus thuringiensis ssp. finitimus strain YBT-020FEMS MICROBIOLOGY LETTERS, Issue 1 2009Fang Ji Abstract Most Bacillus thuringiensis parasporal crystals separate from spores after sporulation. A special phenomenon called spore-crystal association (SCA) occurs in a few subspecies (e.g. ssp. finitimus) where enclosed crystals are associated with spores. In this study, the involvement of crystal protein gene promoters in SCA was investigated. Two crystal protein genes, cry26Aa and cry28Aa, were isolated from subspecies finitimus strain YBT-020, and each or both were then transferred to acrystalliferous B. thuringiensis strain BMB171 and the plasmid-cured derivative of strain YBT-020. SCA was not observed with any recombinant strain, implying that the crystal protein genes are not sufficient to cause SCA. When the typical crystal protein gene cry1Ca was introduced into strain YBT-020, free bipyramidal crystals formed in addition to SCA. Recombinant genes containing the promoter of cry26Aa or cry28Aa fused with the coding sequence (CDS) of cry1Ca were introduced into strain YBT-020, and the typical cry1Ca phenotype was observed. Another two fusion genes consisting of the promoter of cry1Ca and the CDS of cry26Aa or cry28Aa were also transferred to strain YBT-020. Only enclosed crystals formed. These results indicate that the promoters of the crystal protein genes are not the key factor determining the crystal location in strain YBT-020. [source] Nutrition influences growth and virulence of the insect-pathogenic fungus Metarhizium anisopliaeFEMS MICROBIOLOGY LETTERS, Issue 2 2005Farooq A. Shah Abstract Nutrition influenced growth, sporulation and virulence of the insect pathogenic fungus, Metarhizium anisopliae. Virulent conidia were produced on susceptible insect hosts, 1% yeast extract, 2% peptone, osmotic stress medium (OSM) and CN 10:1 medium. Several strain independent markers were identified that could be used to predict the virulence of M. anisopliae conidia. Virulent conidia typically had high levels of spore bound Pr1, an important cuticle degrading protease, and high germination rates. We also show for the first time that virulent conidia have an endogenous CN ratio below 5.2:1. Real Time PCR revealed that virulent conidia from insects contained significantly higher levels of transcripts of pr1 A and other pathogenicity-related genes than inoculum from artificial media. Of the artificial media studied, 1% yeast extract medium yielded the most virulent conidia, these had higher levels of transcripts of these pathogenicity-related genes than the least virulent conidia from the high conidia yielding CN 35:1 medium (= SDA), however, the levels were significantly lower than those in insect-derived conidia. Our study shows for the first time that the passaged inoculum is virulent irrespective of the original culture medium or insect host. Virulent conidia were consistently produced on OSM even though growth and sporulation were poor. We postulate that starvation conditions, whether in vivo or in vitro, results in de-repression of Pr1 and that elevated levels of this enzyme enhance fungal virulence. [source] Analysis of the germination of spores of Bacillus subtilis with temperature sensitive spo mutations in the spoVA operonFEMS MICROBIOLOGY LETTERS, Issue 1 2004Venkata Ramana Vepachedu Abstract A Bacillus subtilis strain with a base substitution in the ribosome-binding site of spoVAC was temperature sensitive (ts) in sporulation and spores prepared at the permissive temperature were ts in l -alanine-triggered germination, but not in germination with Ca2+ -dipicolinic acid (DPA) or dodecylamine. Spores of a ts spo mutant with a missense mutation in the spoVAC coding region were not ts for germination with l -alanine, dodecylamine or Ca2+ -DPA. These findings are discussed in light of the proposal that SpoVA proteins are involved not only in DPA uptake during sporulation, but also in DPA release during nutrient-mediated spore germination. [source] Deprogrammed sporulation in StreptomycesFEMS MICROBIOLOGY LETTERS, Issue 1 2002Yasuo Ohnishi Abstract The bacterial genus Streptomyces forms chains of spores by septation at intervals in aerial hyphae and subsequent maturation on solid medium. Substrate hyphae undergo extensive lysis, liberating nutrients on which aerial hyphae develop. Some mutant strains, however, ectopically form spores by septation in substrate hyphae on solid medium or in vegetative hyphae in liquid medium, which suggests that all hyphae have the potential to differentiate into spores. A Streptomyces griseus mutant strain NP4, which has a mutation in the regulatory system for an ATP-binding cassette (ABC) transporter gene, forms ectopic spores in substrate hyphae only on glucose-containing medium. In addition, overexpression of a substrate-binding protein of the ABC transporter in the wild-type strain causes ectopic septation in very young substrate hyphae and subsequent sporulation in response to glucose. These ectopic spores germinate normally. The ectopic sporulation is independent of A-factor, a microbial hormone that determines the timing of aerial mycelium formation during normal development. Thus, substrate hyphae of Streptomyces have a potential to develop into spores without formation of aerial hyphae. For programmed development, therefore, the strict repression of septum formation in substrate mycelium should be necessary, as well as the positive signal relay leading to aerial mycelium formation followed by septation and sporulation. [source] Green fluorescent protein , a bright idea for the study of bacterial protein localizationFEMS MICROBIOLOGY LETTERS, Issue 1 2001Gregory J Phillips Abstract Use of the green fluorescent protein (GFP) of Aequorea victoria as a reporter for protein and DNA localization has provided sensitive, new approaches for studying the organization of the bacterial cell, leading to new insights into diverse cellular processes. GFP has many characteristics that make it useful for localization studies in bacteria, primarily its ability to fluoresce when fused to target polypeptides without the addition of exogenously added substrates. As an alternative to immunofluorescence microscopy, the expression of gfp gene fusions has been used to probe the function of cellular components fundamental for DNA replication, translation, protein export, and signal transduction, that heretofore have been difficult to study in living cells. Moreover, protein and DNA localization can now be monitored in real time, revealing that several proteins important for cell division, development and sporulation are dynamically localized throughout the cell cycle. The use of additional GFP variants that permit the labeling of multiple components within the same cell, and the use of GFP for genetic screens, should continue to make this a valuable tool for addressing complex questions about the bacterial cell. [source] The immunosuppressive drug leflunomide affects mating-pheromone response and sporulation by different mechanisms in Saccharomyces cerevisiaeFEMS MICROBIOLOGY LETTERS, Issue 1 2000Hiro-aki Fujimura Abstract Leflunomide (LFM) is a novel anti-inflammatory and immunosuppressive drug, and inhibits the growth of cytokine-stimulated lymphoid cells in vitro. The effect of LFM on haploid and diploid cells of Saccharomyces cerevisiae was investigated to elucidate the molecular mechanism of action of the drug. Using a halo assay, LFM was shown to enhance the cell cycle arrest of haploid cells induced by mating pheromone ,-factor. LFM also inhibited sporulation of diploid cells completely. S. cerevisiae genes which were cloned to suppress the anti-proliferative effect when present in increased copy number were introduced and examined for their activity to suppress the effect of LFM. Out of them, MLF4/SSH4, was found to suppress the sporulation-inhibitory effect of LFM. However, MLF4 failed to suppress the enhancing effect of LFM on pheromone response. Thus, LFM is suggested to act on haploid and diploid cells by different mechanisms. [source] Members of the IclR family of bacterial transcriptional regulators function as activators and/or repressorsFEMS MICROBIOLOGY REVIEWS, Issue 2 2006Antonio J. Molina-Henares Abstract Members of the IclR family of regulators are proteins with around 250 residues. The IclR family is best defined by a profile covering the effector binding domain. This is supported by structural data and by a number of mutants showing that effector specificity lies within a pocket in the C-terminal domain. These regulators have a helix-turn-helix DNA binding motif in the N-terminal domain and bind target promoters as dimers or as a dimer of dimers. This family comprises regulators acting as repressors, activators and proteins with a dual role. Members of the IclR family control genes whose products are involved in the glyoxylate shunt in Enterobacteriaceae, multidrug resistance, degradation of aromatics, inactivation of quorum-sensing signals, determinants of plant pathogenicity and sporulation. No clear consensus exists on the architecture of DNA binding sites for IclR activators: the MhpR binding site is formed by a 15-bp palindrome, but the binding sites of PcaU and PobR are three perfect 10-bp sequence repetitions forming an inverted and a direct repeat. IclR-type positive regulators bind their promoter DNA in the absence of effector. The mechanism of repression differs among IclR-type regulators. In most of them the binding sites of RNA polymerase and the repressor overlap, so that the repressor occludes RNA polymerase binding. In other cases the repressor binding site is distal to the RNA polymerase, so that the repressor destabilizes the open complex. [source] Glucose induction pathway regulates meiosis in Saccharomyces cerevisiae in part by controlling turnover of Ime2p meiotic kinaseFEMS YEAST RESEARCH, Issue 5 2008Misa Gray Abstract Several components of the glucose induction pathway, namely the Snf3p glucose sensor and the Rgt1p and Mth1p transcription factors, were shown to be involved in inhibition of sporulation by glucose. The glucose sensors had only a minor role in regulating transcript levels of the two key regulators of meiotic initiation, the Ime1p transcription factor and the Ime2p kinase, but a major role in regulating Ime2p stability. Interestingly, Rgt1p was involved in glucose inhibition of spore formation but not inhibition of Ime2p stability. Thus, the glucose induction pathway may regulate meiosis through both RGT1- dependent and RGT1- independent pathways. [source] The importance of a functional trehalose biosynthetic pathway for the life of yeasts and fungiFEMS YEAST RESEARCH, Issue 4-5 2004Carlos Gancedo Abstract The view of the role of trehalose in yeast has changed in the last few years. For a long time considered a reserve carbohydrate, it gained new importance when its function in the acquisition of thermotolerance was demonstrated. More recently the cellular processes in which the trehalose biosynthetic pathway has been implicated range from the control of glycolysis to sporulation and infectivity by certain fungal pathogens. There is now enough experimental evidence to conclude that trehalose 6-phosphate, an intermediate of trehalose biosynthesis, is an important metabolic regulator in such different organisms as yeasts or plants. Its inhibition of hexokinase plays a key role in the control of the glycolytic flux in Saccharomyces cerevisiae but other, likely important, sites of action are still unknown. We present examples of the phenotypes produced by mutations in the two steps of the trehalose biosynthetic pathway in different yeasts and fungi, and whenever possible examine the molecular explanations advanced to interpret them. [source] Survival and vitality of Gremmeniella abietina on Pinus sylvestris slash in northern SwedenFOREST PATHOLOGY, Issue 6 2006J. Witzell Summary Survival and vitality of Gremmeniella abietina on Pinus sylvestris slash was studied in northern Sweden during 2003 and 2004. Once a month between September 2003 and April 2004, two to three trees were cut down and debranched. Shoots with pycnidia were sampled at the felling date and then at every consecutive month. The percentage of germinated conidia from each shoot was calculated after 24, 48 and 72 h incubation. The vitality of G. abietina pycnidia in the slash remained high the whole period. Intact pycnidia were found on slash several months after the time of conidial sporulation, which indicates that new pycnidia may be produced on dead pine branches. Sampling of shoots from slash on 13- to 18-month-old clear-cuts showed conidial germination capacity as high as in pycnidia collected in fresh slash. Due to survival of G. abietina in slash it is recommended to postpone planting of P. sylvestris seedlings in northern boreal areas to the third vegetation period after sanitary clear-cuts. Résumé La survie et la vitalité de Gremmeniella abietina dans des rémanents de Pinus sylvestris ont étéétudiées dans le nord de la Suède pendant les années 2003 et 2004. Une fois par mois entre septembre 2003 et avril 2004, 2 ou 3 arbres ont été abattus et ébranchés. Des pousses avec pycnides ont étééchantillonnées à la date d'abattage et les mois suivants. Le pourcentage de conidies germées a été calculé pour chaque pousse après 24, 48 et 72 heures d'incubation. La vitalité des pycnides de G. abietina dans les rémanents est restée élevée tout au long de la période. Des pycnides intactes ont été trouvées dans les rémanents plusieurs mois après la période de sporulation conidienne, ce qui suggère que de nouvelles pycnides peuvent être produites sur des branches mortes de pin. Des échantillonnages de pousses dans des rémanents de coupes rases réalisées 13,18 mois plus tôt ont montré une capacité de germination des conidies aussi élevée que dans les pycnides collectées dans des rémanents fraîchement coupés. Du fait de la survie de G. abietina dans les rémanents, il est conseillé de reporter la plantation des semis de P. sylvestris dans les zones septentrionales boréales à la troisième saison de végétation après les coupes sanitaires. Zusammenfassung Das Überleben und die Vitalität von Gremmeniella abietina auf Schlagabraum von Pinus sylvestris wurde in den Jahren 2003 und 2004 untersucht. Zwischen September 2003 und April 2004 wurden in jedem Monat einmal 2,3 Bäume gefällt und entastet. Zum Zeitpunkt des Fällens und in jedem folgenden Monat wurden Triebe mit Pyknidien gesammelt. Von jedem Trieb wurde die Keimrate der Konidien nach 24, 48 und 72 Stunden Inkubation bestimmt. Während der gesamten Beobachtungsdauer blieb die Vitalität der Pyknidien im Schlagabraum hoch. Mehrere Monate nach der Sporulation wurden intakte Pyknidien gefunden, ein Hinweis darauf, dass möglicherweise neue Pyknidien auf den toten Kiefernzweigen gebildet wurden. Auf dem Schlagabraum von 13,18 Monate alten Kahlschlägen war die Keimfähigkeit der Konidien ähnlich hoch wie bei Pyknidien von frischem Schlagabraum. Aufgrund des langen Überlebens von G. abietina in Schlagabraum wird für die nördlichen borealen Gebiete empfohlen, nach phytosanitären Kahlschlägen P. sylvestris -Sämlinge erst in der dritten Vegetationsperiode zu pflanzen. [source] Infection of Arceuthobium americanum by Colletotrichum gloeosporioides and its potential for inundative biological controlFOREST PATHOLOGY, Issue 5 2005T. D. Ramsfield Summary Inundative biological control of Arceuthobium americanum occurring on Pinus contorta var. latifolia with the fungus Colletotrichum gloeosporioides was investigated. Isolates of C. gloeosporioides were collected throughout British Columbia, Canada, and one isolate was selected for assessment based on its growth and sporulation in culture. The fungus was formulated using the ,Stabileze' method and inoculated onto A. americanum under field conditions. It became established on some replicates and there was a higher incidence of C. gloeosporioides on treated replicates than controls. In some replicates, the treatment reduced fruit production, leading to a decrease in the reproductive capacity of the dwarf mistletoe plant; however, the efficacy was highly variable and not significant. Résumé Une méthode de lutte biologique utilisant le champignon Colletotrichum gloeosporioides contre Arceuthobium americanum sur Pinus contorta var. latifolia a étéétudiée. Des isolats de C. gloeosporioides ont été collectés dans toute la Colombie Britannique, au Canada, et un isolat a été sélectionné pour les essais, sur la base de sa croissance et de sa sporulation en culture. La préparation fongique a été formulée en utilisant la méthode 'Stabileze' et inoculée sur A. americanum sur le terrain. Le champignon s'est établi dans quelques cas et l'incidence de C. gloeosporioides a été plus forte dans les cas traités par rapport aux témoins. Dans quelques cas, le traitement a réduit la production de fruits, conduisant à une diminution de la capacité reproductive du faux-gui, toutefois l'efficacité s'est montrée très variable et globalement non significative. Zusammenfassung Es wurde die Eignung des Pilzes Colletotrichum gloeosporioides zur biologischen Bekämpfung von Arceuthobium americanum auf Pinus contorta var. latifolia untersucht. Verschiedene Isolate von C. gloeosporioides wurden in British Columbia (Kanada) gesammelt und ein Isolat wurde aufgrund seines guten Wachstums und der Sporulation in vitro für die Inokulationsexperimente ausgewählt. Die Konidien des Pilzes wurden nach der ,,Stabileze'' Methode formuliert und im Freiland auf A. americanum inokuliert. Der Pilz etablierte sich in einigen Fällen und C. gloeosporioides kam auf den behandelten Pflanzen häufiger vor als auf den Kontrollen. Bei einigen Wiederholungen war die Fruktifikation der Mistel reduziert; allerdings war dieser Effekt sehr variabel und die Unterschied war nicht signifikant. [source] A medium to enhance identification of Septoria musiva from poplar cankersFOREST PATHOLOGY, Issue 3 2002J. C. STANOSZ A series of experiments was conducted to determine the relative tolerance in vitro of an isolate of Septoria musiva (a fungus that causes a severely damaging stem canker disease of poplars) for selected chemicals. Inhibition of diameter growth of this fungus on a V-8 vegetable juice-based medium with captan, chlorothalonil, iprodione, mancozeb and streptomycin sulphate at concentrations, respectively, of 50, 1, 10, 10, and 100 mg l,1 was relatively low compared to inhibition of eight other fungi cultured from cankers on poplars. In addition, the presence of captan stimulated profuse sporulation of the fungus. These properties assisted in the identification of S. musiva from cankers resulting from artificial inoculation of poplar branches in the field. Un milieu de culture pour aider à l'identification de Septoria musiva isolé de chancres sur peuplier Un isolat de Septoria musiva, champignon responsable de chancres de tronc sur peupliers, àété testéin vitro pour sa tolérance à un certain nombre de substances. L'inhibition de la croissance en diamètre a été déterminée sur milieu V8 additionné de captan, chlorothalonil, iprodione, mancozèbe et sulfate de streptomycine aux concentrations respectives de 50, 1, 10, 10, et 100 mg par litre; l'inhibition était relativement faible comparée à celle de huit autres champignons isolés de chancres de peuplier. La présence de captan stimulait la sporulation du champignon. Ces propriétés ont aidéà l'identification du S. musiva réisoléà partir de chancres obtenus au champ par inoculation artificielle de branches de peuplier. Ein Medium zur Verbesserung der Identifikation von Septoria musiva aus Pappelkrebsen Es wurde eine Serie von Experimenten zur Bestimmung der relativen Toleranz eines Septoria musiva Isolats (ein Erreger ausserordentlich schädlicher Stammkrebse an Pappeln) gegenüber ausgewählten Chemikalien durchgeführt. Das Wachstums des Pilzes auf einem auf V-8 Gemüsesaft basierenden Medium mit 50 mg l,1 Captan, 1 mg l,1 Chlorothalonil, 10 mg l,1 Iprodion, 10 mg l,1 Mancozeb und 100 mg l,1 Streptomycinsulfat wurde im Vergleich zum Wachstum von acht anderen Pilzarten, die ebenfalls aus Pappelkrebsen isoliert wurden, nur schwach gehemmt. Zudem regte Captan den Pilz zu intensiver Sporulation an. Als hilfreich erwiesen sich diese Eigenschaften in Feldversuchen bei der Identifikation von S. musiva aus Krebsen, die sich nach künstlicher Inokulation von Pappelzweigen entwickelten. [source] Respiration and annual fungal production associated with decomposing leaf litter in two streamsFRESHWATER BIOLOGY, Issue 9 2004M. D. Carter Summary 1. We compared fungal biomass, production and microbial respiration associated with decomposing leaves in one softwater stream (Payne Creek) and one hardwater stream (Lindsey Spring Branch). 2. Both streams received similar annual leaf litter fall (478,492 g m,2), but Lindsey Spring Branch had higher average monthly standing crop of leaf litter (69 ± 24 g m,2; mean ± SE) than Payne Creek (39 ± 9 g m,2). 3. Leaves sampled from Lindsey Spring Branch contained a higher mean concentration of fungal biomass (71 ± 11 mg g,1) than those from Payne Creek (54 ± 8 mg g,1). Maximum spore concentrations in the water of Lindsay Spring Branch were also higher than those in Payne Creek. These results agreed with litterbag studies of red maple (Acer rubrum) leaves, which decomposed faster (decay rate of 0.014 versus 0.004 day,1), exhibited higher maximum fungal biomass and had higher rates of fungal sporulation in Lindsey Spring Branch than in Payne Creek. 4. Rates of fungal production and respiration per g leaf were similar in the two streams, although rates of fungal production and respiration per square metre were higher in Lindsey Spring Branch than in Payne Creek because of the differences in leaf litter standing crop. 5. Annual fungal production was 16 ± 6 g m,2 (mean ± 95% CI) in Payne Creek and 46 ± 25 g m,2 in Lindsey Spring Branch. Measurements were taken through the autumn of 2 years to obtain an indication of inter-year variability. Fungal production during October to January of the 2 years varied between 3 and 6 g m,2 in Payne Creek and 7,27 g m,2 in Lindsey Spring Branch. 6. Partial organic matter budgets constructed for both streams indicated that 3 ± 1% of leaf litter fall went into fungal production and 7 ± 2% was lost as respiration in Payne Creek. In Lindsey Spring Branch, fungal production accounted for 10 ± 5% of leaf litter fall and microbial respiration for 13 ± 9%. [source] Meu10 is required for spore wall maturation in Schizosaccharomyces pombeGENES TO CELLS, Issue 2 2002Takahiro Tougan Background: Many genes are meiosis and/or sporulation-specifically transcribed during this process. Isolation and analysis of these genes might help us to understand how meiosis and sporulation are regulated. For this purpose, we have isolated a large number of cDNA clones from Schizosaccharomyces pombe whose expression is up-regulated during meiosis. Results: We have isolated meu10+ gene, which encodes 416 amino acids and bears homology to SPS2 of Saccharomyces cerevisiae. A strain whose meu10+ gene has been deleted forms no viable spores. Thin-section electron micrographs showed that the meu10, strain has abnormally formed spore walls, and then they disrupt, allowing cytoplasmic material to escape. The Meu10-GFP fusion protein is localized to the spore periphery, thereafter returned to the cytoplasm after sporulation. Meu10-GFP localization to the spore wall was almost normal in the bgs2, or chs1, mutants that lack 1,3-,-glucan or chitin, respectively. In contrast, 1,3-,-glucan is abnormally localized in meu10, cells. Meu10 has an N-terminal domain with homology to the mammalian insulin receptor and a C-terminal domain with a transmembrane motif. Mutants whose N-terminal or C-terminal domain was truncated were severely defective for sporulation. Conclusions: Meu10 is a spore wall component and plays a pivotal role in the formation of the mature spore wall structure. [source] Temporal and selective association of multiple sigma factors with RNA polymerase during sporulation in Bacillus subtilisGENES TO CELLS, Issue 2 2000Masaya Fujita Background During sporulation in Bacillus subtilis, an asymmetric division produces two cells, a forespore and mother cell, with which follow different developmental paths. The highly ordered programme of temporal and spatial gene activation during sporulation is governed by the principal RNA polymerase holoenzyme (E,A) and alternative holoenzyme forms containing the developmental sigma factors ,H, ,F, ,E, ,G and ,K, which appear successively during development. The control mechanism(s) of temporal and selective association of multiple sigma factors with core RNA polymerase is unclear. As a first step to addressing these issues, this report quantifies the amount of each subunit of RNA polymerase that is present in the sporangium during sporulation, and analyses in vitro the relative affinities of each sigma subunit for core RNA polymerase. Results Using quantitative immunoblot analysis, the amounts of E,A, E,H, E,E and E,K in relation to the total amount of RNA polymerase at appropriate time-points were found to be 15%, 1%, 6% and 2%, respectively. Therefore, the core RNA polymerase is predicted to be in excess. The level of core RNA polymerase and ,A remained constant during the transition from vegetative growth to sporulation, whereas the sporulation-specific sigma factors appeared successively, in the order ,H, ,E and ,K. Competition experiments between sigma factors in an in vitro transcription system revealed the dominance of ,A over ,H and ,E for open promoter complex formation. These results are inconsistent with the idea that late appearing sigma factors can displace earlier appearing sigmas from the core enzyme. Conclusions As the core RNA polymerase is in excess, the results suggest that successive sigma factors can bind to core RNA polymerase without having to displace earlier appearing sigma factors. Thus, the programme of gene expression during sporulation might not require mechanisms for the substitution of one sigma factor by another on the core RNA polymerase. [source] Psychrophilic and psychrotrophic clostridia: sporulation and germination processes and their role in the spoilage of chilled, vacuum-packaged beef, lamb and venisonINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2010Katharine H. Adam Summary Spoilage of beef, lamb and venison by psychrophilic and psychrotrophic clostridial species renders meat unacceptable resulting in financial losses and reduced consumer confidence. A number of clostridial strains, including Clostridium algidicarnis, Clostridium algidixylanolyticum, Clostridium estertheticum, Clostridium frigidicarnis and Clostridium gasigenes, have been implicated in red meat spoilage. Unlike other spoilers, these clostridia are able to grow in anaerobic conditions and at chilled temperatures (some at ,1.5 °C the optimal storage temperature for chilled red meat). The spoilage they cause is characterised by softening of the meat, production of large amounts of drip (exudates), offensive odours and in the case of C. estertheticum and C. gasigenes production of gas. Spoilage occurs following the introduction of clostridial spores into vacuum packages during processing. Germination of spores is necessary for the growth of vegetative cells, which cause spoilage. Current mitigation strategies focus on good management practice within meat processing plants. However, this is not always sufficient to prevent spoilage. This review summarises the issues associated with meat spoilage because of psychrotolerant clostridia and discusses areas that require further study. [source] Effects of modification of membrane lipid composition on Bacillus subtilis sporulation and spore propertiesJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009K.K. Griffiths Abstract Aims:, To determine effects of inner membrane lipid composition on Bacillus subtilis sporulation and spore properties. Methods and Results:, The absence of genes encoding lipid biosynthetic enzymes had no effect on B. subtilis sporulation, although the expected lipids were absent from spores' inner membrane. The rate of spore germination with nutrients was decreased c. 50% with mutants that lacked the major cardiolipin (CL) synthase and another enzyme for synthesis of a major phospholipid. Spores lacking the minor CL synthase or an enzyme essential for glycolipid synthesis exhibited 50,150% increases in rates of dodecylamine germination, while spores lacking enzymes for phosphatidylethanolamine (PE), phosphatidylserine (PS) and lysylphosphatidylglycerol (l-PG) synthesis exhibited a 30,50% decrease. Spore sensitivity to H2O2 and tert-butylhydroperoxide was increased 30,60% in the absence of the major CL synthase, but these spores' sensitivity to NaOCl or OxoneÔ was unaffected. Spores of lipid synthesis mutants were less resistant to wet heat, with spores lacking enzymes for PE, PS or l-PG synthesis exhibiting a two to threefold decrease and spores of other strains exhibiting a four to 10-fold decrease. The decrease in spore wet heat resistance correlated with an increase in core water content. Conclusions:, Changing the lipid composition of the B. subtilis inner membrane did not affect sporulation, although modest effects on spore germination and wet heat and oxidizing agent sensitivity were observed, especially when multiple lipids were absent. The increases in rates of dodecylamine germination were likely due to increased ability of this compound to interact with the spore's inner membrane in the absence of some CL and glycolipids. The effects on spore wet heat sensitivity are likely indirect, because they were correlated with changes in core water content. Significance and Impact of the Study:, The results of this study provide insight into roles of inner membrane lipids in spore properties. [source] Activity and mode of action against fungal phytopathogens of bovine lactoferricin-derived peptidesJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2006A. Muñoz Abstract Aim:, To evaluate the activity against fungal phytopathogens of two synthetic peptides derived from the protein bovine lactoferricin: the antibacterial active core of six amino acid residues (LfcinB20,25) and an extension of 15 amino acids (LfcinB17,31). Methods and Results:,In vitro activity against fungal pathogens was determined and compared with that against model micro-organisms. Activity was demonstrated against fungi of agronomic relevance. Distinct antimicrobial properties in vitro were found for the two peptides. LfcinB17,31 had growth inhibitory activity higher than LfcinB20,25. However, LfcinB17,31 was not fungicidal to quiescent conidia of Penicillium digitatum at the concentrations assayed, while LfcinB20,25 killed conidia more efficiently. Microscopical observations showed that the mycelium of P. digitatum treated with LfcinB17,31 developed alterations of growth, sporulation and chitin deposition, and permeation of hyphal cells. In experimental inoculations of mandarins, both peptides showed limited protective effect against the disease caused by P. digitatum. Conclusions:, LfcinB20,25 and LfcinB17,31 peptides were shown to have antimicrobial activity against plant pathogenic filamentous fungi, with distinct properties and mode of action. Significance and Impact of the Study:, LfcinB20,25 and LfcinB17,31 peptides offer novel alternatives to develop resistant plants by molecular breeding. [source] History of science , sporesJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2006Lewis B Perry Memorial Lecture 200 Abstract Bacterial endospores were first studied 130 years ago by Cohn in 1876 and independently by Koch in the same year. Although spore dormancy and resistance have been much studied since then, questions still remain concerning the basic mechanisms and the kinetics of heat inactivation in particular. Likewise, the extreme dormancy and longevity of spores was recognized early on and later greatly extended but still evade complete understanding. Evidence has accumulated for the involvement of specific spore components such as calcium, dipicolinic acid, small acid soluble proteins in the core and peptidoglycan in the cortex. Involvement of physical factors too, such as the relative dehydration of the core, maybe in a high-viscosity state or even in a glassy state, has added to appreciation of the multicomponent nature of dormancy and resistance. Spore-former morphology formed the basis for early classification systems of sporeformers from about 1880 and consolidated in the mid-1900s, well prior to the use of modern genetic procedures. With respect to sporulation, groundbreaking sequence studies in the 1950s provided the basis for later elucidation of the genetic control widely relevant to many cell differentiation mechanisms. With respect to the breaking of dormancy (activation and germination), the elucidation of mechanisms began in the 1940s following the observations of Hills at Porton who identified specific amino acid and riboside ,germinants', and laid the basis for the later genetic analyses, the identification of germinant receptor genes and the elucidation of key germination reactions. The nonexponential nature of germination kinetics has thwarted the development of practical Tyndallization-like processing. So inactivation by heat remains the premier method of spore control, the basis of a huge worldwide industry, and still relying on the basic kinetics of inactivation of Clostridium botulinum spores, and the reasoning regarding safety first evolved by Bigelow et al. in 1920 and Esty and Meyer in 1922. ,Newer' processes such as treatment with ionizing radiation (first proposed in 1905) and high hydrostatic pressure (first proposed in 1899) may be introduced if consumer resistance and some remaining technical barriers could be overcome. [source] Inactivation of Bacillus spores in reconstituted skim milk by combined high pressure and heat treatmentJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2006K.J. Scurrah Abstract Aims:, To determine the resistance of a variety of Bacillus species spores to a combined high pressure and heat treatment; and to determine the affect of varying sporulation and treatment conditions on the level of inactivation achieved. Methods and Results:, Spores from eight Bacillus species (40 isolates) were high pressure,heat treated at 600 MPa, 1 min, initial temperature 72°C. The level of inactivation was broad (no inactivation to 6 log10 spores ml,1 reduction) and it varied within species. Different sporulation agar, high pressure equipment and pressure-transmitting fluid significantly affected the response of some isolates. Varying the initial treatment temperature (75, 85 or 95°C) shifted the relative order of isolate high pressure,heat resistance. Conclusions:, The response of Bacillus spores to combined high pressure,heat treatment is variable and can be attributed to both intrinsic and extrinsic factors. The combined process resulted in a high level of spore inactivation for several Bacillus species and is a potential alternative treatment to traditional heat-only processes. Significance and Impact of the Study:, Sporulation conditions, processing conditions and treatment temperature all affect the response of Bacillus spores to the combined treatment of high pressure and heat. High levels of spore inactivation can be achieved but the response is variable both within and between species. [source] Effect of sporulation and recovery medium on the heat resistance and amount of injury of spores from spoilage bacilliJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2001A.E. Cazemier Aims:,To assess the influence of sporulation media on heat resistance, and the use of stress recovery media to measure preservation injury of spores of five representative spoilage bacilli. Methods and Results:,Bacillus spores prepared on nutrient agar supplemented with Ca2+, Mg2+, Mn2+, Fe2+ and K+ were more heat-resistant than spores obtained from nutrient agar with Mn2+. This increased heat resistance correlated with a decrease in the protoplast water content as determined by buoyant density sedimentation. The degree of preservation injury severity could be assessed on media containing NaCl at moderate pH and organic acids at acid pH. Ca-DPA, K+ or proline were added to the recovery media to demonstrate that heat probably caused injury to both spore germination and the outgrowth system. Significance and Impact of the Study:,The metal content of sporulation media can strongly effect the validity of preservation resistance studies. The distinctive recovery media developed here can be relevant for assessing and comparing new preservation technologies. [source] Evidences of high carbon catabolic enzyme activities during sporulation of Pleurotus ostreatus (Florida)JOURNAL OF BASIC MICROBIOLOGY, Issue 6 2003Tapas K. Chakraborty Measurements of the specific activities of the representative enzymes of different pathways linked to carbohydrate metabolism indicate that glycolysis and TCA cycles are the major route of carbohydrate catabolism in the sporulating phase of fruiting body development in Pleurotus ostreatus. Enzymes of the pentose phosphate pathway always showed lower specific activities as compared to those of the enzymes of the glycolytic pathway. The activity of NADP linked glutamate dehydrogenase which is known to be an anabolic enzyme decreased drastically in sporulating fruiting bodies and in spore containing gill tissue (spore bearing structure). Mannitol dehydrogenase activity declined significantly in the sporulating phase of P. ostreatus. The high rate of metabolism during sporulation was further supported by a lower rate of gluconeogenesis at this stage. Concentrations of all the major sugars of the fruiting body (mannitol, glucose and trehalose) decreased in the mature fruiting body and gill tissue. This indicated high catabolic activities at this stage of development. [source] | |||||||||||||||||||||||||||||||