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PubMed1975

Spores of microorganisms. XXVI. Synthetic activities of germinating spores of Bacillus cereus prevented from outgrowth.

Spores of Bacillus cereus were germinated in a germination limited medium (GL-medium) which facilitates only germination but not the postgerminative development of spores. Under these conditions a limited protein synthesis occurs. However, this protein synthesis is stopped after a short time interval. The rate of synthesis of new proteins, as well as their total amount, is influenced by the length of the activation heat shock. Synthesis of the wall material continues for several hours and thick-walled cells with a changed ultrastructure are formed. Synthesis of the diaminopimelic acid (dap) containing material of the cell wall is sensitive to actinomycin D and relatively resistant to chloramphenicol. Similarly, protein synthesis is relatively chlorapmhenicol-resistant but is fully inhibited by azauracil or spiramycin. Whereas RNA formed in the control culture is partially decomposed after 30 min of incubation, chloramphenicol accelerates its synthesis and prevents its decay. Exudate components apparently stimulate synthesis of ribonucleic acid, proteins and the wall material. The 14-C-dap containing material released by prelabelled spores in the form of the exudate during the germination is not re-utilized by the spores germinated in the GL-medium. The results are discussed with respect to the atypical primary synthetic activities of spores under conditions when the postgerminative development is prevented and from the point of view of participation of the germination exudate during these syntheses.

Bacillus cereus↗
PubMed2002

Spore germination.

Despite being relatively insensitive to environmental insult, the spore is responsive to low concentrations of chemical germinants, which induce germination. The process of bacterial spore germination involves membrane permeability changes, ion fluxes and the activation of enzymes that degrade the outer layers of the spore. A number of components in the spore that are required for the germination response have been identified, including a spore-specific family of receptor proteins (the GerA family), an ion transporter and cortex lytic enzymes. The germinant traverses the outer layers of the spore and interacts with its receptor in the inner membrane to initiate the cascade of germination events, but the molecular details of this signal transduction process remain to be identified.

Bacterial Proteins↗
PubMed1997

Abscisic acid inhibits germination of mature Arabidopsis seeds by limiting the availability of energy and nutrients.

The addition of abscisic acid (ABA) to mature non-dormant seeds inhibits their germination. This effect of ABA might be related to its natural function as an endogenous inhibitor of precocious germination during seed formation. In this work, we studied how ABA affects the germination of mature seeds and the growth of nascent seedlings of Arabidopsis thaliana (L.) Heynh. Our findings were as follows: (i) inhibition by ABA was gradual, dose-dependent, and did not disappear after germination; (ii) inhibition of germination was relieved by the addition of metabolizable sugars or amino acids to the plating media; (iii) the effect of sugars and amino acids was cooperative, indicating that these two groups of metabolites relieve different deficiencies; (iv) ABA caused appreciable alterations in energy and nitrogen metabolism; and (v) ABA prevented the degradation of the seed storage proteins. In summary, ABA appears to inhibit seed germination by restricting the availability of energy and metabolites. This mechanism seems consistent with other known effects of ABA.

Abscisic Acid↗
PubMed2005

Differential gene expression during teliospore germination in Ustilago maydis.

Ustilago maydis is a model fungal pathogen that induces the formation of tumors in maize. The tumor provides an environment for hyphal differentiation, leading to the formation of thick-walled, diploid teliospores. Such spores serve as a dispersal agent for smut and rust fungi, and their germination leads to new rounds of infection. The morphological changes that occur during teliospore germination in U. maydis have been described in detail. However, the specific molecular events that facilitate this process have not been identified. Through the construction and hybridization of microarrays containing a set of 3918 non-redundant cDNAs, we have identified genes that are differentially regulated during teliospore germination. Teliospores induced to germinate for 4 and 11 h were selected for comparison with dormant teliospores. Genes identified as differentially expressed included many that are presumably involved in as yet undescribed molecular events during teliospore germination, as well as characterized genes previously shown to be required for the process. This study represents the first large-scale investigation of changes in gene expression during teliospore germination.

Cell Differentiation↗
PubMed2006

Identification and characterization of a germination operon from Bacillus thuringiensis.

Spore cortex-lytic enzymes are essential for germination in Bacillus. A homologue of the cwlJ gene involved in spore germination was isolated from Bacillus thuringiensis. The deduced product of this gene exhibits striking sequence similarity to CwlJ of Bacillus subtilis. Another open reading frame (ORF) was found 27 bp downstream of cwlJ and its deduced product shows high similarity to YwdL of B. subtilis. Reverse transcription polymerase chain reaction analysis indicated that cwlJ and ywdL formed a bicistronic operon in B. thuringiensis. Disruption of this operon did not affect sporulation and the spores of corresponding mutant showed the same refractility as the wild-type strain. In contrast, the fall of optical density at 600 nm in the mutant culture was slower than that of the wild-type strain during the spore germination response to different germinants such as L: -alanine, inosine or CaDPA. The spore germination of the cwlJ mutant was restored by introducing this operon into the disruption mutant. These results suggest this operon is essential for normal spore germination in B. thuringiensis. The expression of cwlJ was observed in the sporulating cells through Western blot experiments.

Bacillus thuringiensis↗
PubMed1984

The stage specific inhibition of Dictyostelium discoideum spore germination by the mutagen 4-nitroquinoline 1-oxide.

The drug 4-nitroquinoline 1-oxide (4NQO) is a potent inhibitor of Dictyostelium discoideum spore germination. This inexpensive, water soluble drug is active at a concentration of 5 micrograms/ml (26 microM) and permeates the spore at all stages in germination. Spores subjected to 4NQO treatment exhibit an irreversible blockage of myxamoebae emergence, but spore activation, post-activation lag, and swelling are not affected. Swollen 4NQO-treated spores lose the outer two spore walls but lack the ability to degrade the innermost wall. The drug does not affect oxygen uptake during post-activation lag or swelling, and only a stage specific depression in O2 uptake is observed when control spores begin to release myxamoebae. When added early in germination, 4NQO blocks the incorporation of [3H] uracil into a cold trichloroacetic acid (TCA) insoluble fraction by 98%. However, when the drug is added midway through germination and followed by a pulse labelling period of 1 h, only 65% inhibition of RNA synthesis is observed. This lack of complete inhibition may occur because the drug requires metabolic activation; thus, new rounds of RNA synthesis may have initiated before the drug became fully activated. 4NQO also blocks the de novo expression of beta-glucosidase activity when added early in germination. Additionally, we observe that vegetative cellular slime mold cells are 100 times more resistant than spores to 4NQO-induced damage. Taken together, our results support the observation that RNA synthesis is only required for the emergence stage of germination and that dormant D. discoideum spores may lack efficient excision repair mechanisms.

4-Nitroquinoline-1-oxide↗
PubMed1995

Antenatal risk factors for germinal matrix hemorrhage and intraventricular hemorrhage in preterm infants.

OBJECTIVES: This study was designed to evaluate the effect of antenatal risk factors on the occurrence of germinal matrix hemorrhage or intraventricular hemorrhage in preterm infants. STUDY DESIGN: Antenatal factors were evaluated in 302 infants delivered between 24 and 33 completed weeks gestation. Ultrasonographic screening of intracranial hemorrhage was carried out in all the infants. The association between risk factors and neonatal intracranial hemorrhage was evaluated with both univariate and multivariate models. RESULTS: In stepwise logistic regression analysis, birthweight was a better predictor of neonatal germinal matrix hemorrhage than gestational age. Conversely, gestational age better predicted intraventricular hemorrhage than did birthweight. Risk factors for neonatal germinal matrix hemorrhage and intraventricular hemorrhage were dissimilar. A history of heavy (> 10 cigarettes/day) maternal smoking on admission increased the risk of germinal matrix hemorrhage three-fold (odds ratio = 3.35; 95% C.I. 1.24-9.07). Antenatal corticosteroid use reduced the risk of intraventricular hemorrhage by 76% (odds ratio = 0.24; 95% C.I. 0.09-0.61). Among patients with spontaneous preterm delivery or premature rupture of fetal membranes, the presence of labor was a significant effect modifier of the gestational-age associated risk of germinal matrix hemorrhage-intraventricular hemorrhage. CONCLUSIONS: Risk factors for neonatal germinal matrix hemorrhage are different from those for intraventricular hemorrhage. Most antenatal factors, especially those affecting fetal maturity, could influence the progression rather than the onset of intracranial hemorrhage.

Adult↗
PubMed1982

Developmental regulation of protein synthesis during Polysphondylium pallidum cyst germination: a two-dimensional gel electrophoresis study.

Microcyst germination in Polysphondylium pallidum can be used as a model for studying gene expression because temporally regulated modulations in protein synthesis occur in this developmental pathway. Germinating cysts were labeled with [35S]methionine for half-hourly periods during the synchronous germination sequence, and the proteins labeled in each period were resolved by two-dimensional polyacrylamide gel electrophoresis. Three major classes of proteins observed were distinguished by the time of onset and duration of their synthesis: (a) proteins made throughout germination; (b) proteins synthesized only during a portion of the germination pathway; and (c) polypeptides whose synthesis started at 1 or 1.5 h and then continued throughout germination.

Cell Cycle↗
PubMedDate not supplied

Morphometry of blood vessels in the cortex and germinal plate of premature neonates.

Germinal plate hemorrhage with intraventricular rupture has been a leading cause of morbidity and mortality among premature neonates. Because germinal plate hemorrhage decreases with increasing gestational age, germinal plate vessel size and/or structure may be an important etiologic factor. Electron micrographs of the cortical and germinal plate blood vessels from 13 premature infants ranging in age from 19-37 weeks gestation were studied; vessel, lumena, and endothelial areas were measured using a digitizing tablet. In infants between 25-32 weeks gestation, the germinal plate vessel and lumenal areas were significantly greater than the areas of cortical vessel and lumena. This finding suggests that one of the factors involved in germinal plate hemorrhage is described by LaPlace's law which states that the larger the vessel diameter, the greater the pressure on the vessel wall.

Basement Membrane↗
PubMed2005

1-Octen-3-ol inhibits conidia germination of Penicillium paneum despite of mild effects on membrane permeability, respiration, intracellular pH, and changes the protein composition.

1-Octen-3-ol is a volatile germination self-inhibitor produced by Penicillium paneum that blocks the germination process. The size of conidia treated with 1-octen-3-ol was similar to that of freshly harvested conidia. Exposure to 1-octen-3-ol resulted in staining of 10-20% of the conidia with PI and TOTO, fluorescent DNA probes that cannot enter cells with an intact membrane, whereas only 3-5% of non-treated conidia were stained. Addition of 1-octen-3-ol to germinating conidia resulted in transient dissipation of the pH gradient. From this, we conclude that slight permeabilisation of the fungal membrane occurs in the presence of the inhibitor. Two-dimensional gel electrophoresis analysis of protein patterns revealed striking differences between non-germinated conidia, germinated conidia and 1-octen-3-ol-treated conidia. In conclusion, 1-octen-3-ol has mild effects on the plasma membrane, but interferes with essential metabolic processes, such as swelling and germination of the conidia, but in a reversible manner.

Cell Membrane Permeability↗
PubMed2005

Nitric oxide has a regulatory effect in the germination of conidia of Colletotrichum coccodes.

Nitric oxide (NO) was first detected in mammals and has since been found in plants and in micro-organisms such as bacteria. NO is an important signalling molecule involved in a number of critical signal transduction pathways. To date, NO has not been directly detected in fungi, and little research on NO and fungi has been completed. Here, the role of NO in the germination of Colletotrichum coccodes conidia was investigated. Conidia were germinated on microscope slides, treated with chemicals to block NO, to add NO, and/or to detect NO, and assessed for their stage of development over 24 h. NO was detected in germinating conidia at all stages of development. Exogenous NO delayed germination, while treatment with NO inhibitors accelerated germination, suggesting NO may have a regulatory effect in germination. The differential effect of the various inhibitors suggests the fungal isoform of nitric oxide synthase (NOS) may be biochemically similar to mammalian constitutive NOS.

Colletotrichum↗
PubMed2005

Differentiation inside multicelled macroconidia of Fusarium culmorum during early germination.

Multicelled conidia are formed by many fungal species, but germination of these spores is scarcely studied. Here, the germination and the effects of antimicrobials on multicompartment macroconidia of Fusarium culmorum were investigated. Germ-tube formation was mostly from apical compartments. The intracellular pH (pH(in)) of the different individual cells of the macroconidia was monitored during germination. The pH(in) varied among different compartments and during different stages of germination. The internal pH was lowest in ungerminated cells and rose during germ-tube formation and was highest in new germ tubes. Antifungal compounds affect the pH(in) and differentiation of the conidia. The pH(in) inside the macroconidial compartments was lowered very fast in the presence of nystatin (1 and 4 microg/ml). At sublethal doses (0.3 microg/ml), the apical compartments were preferentially targeted showing lower pH(in) values. The reduced germination capacity of apical compartments under these conditions was compensated by an increased germination capacity of middle compartments.

Fusarium↗
PubMed2004

Unequal cell division regulated by the contents of germinal vesicles.

Fertilization occurs during meiosis in many animals, when maternal centrosomes participate in the formation of spindles at the animal pole, which results in polar body formation. Paternal centrosomes do not participate in cell division during oocyte maturation. After meiosis, they form the spindles while the maternal centrosomes are discarded. It is unknown why paternal centrosomes do not form spindles during meiosis. Here, we show that the artificial incorporation of sperm at the animal pole of immature starfish oocytes causes unequal cell division and the formation of polar body-like fragments. The removal of germinal vesicles from the animal pole blocks the formation of polar body-like fragments. Furthermore, translocation of germinal vesicles to the vegetal pole by centrifugation induces the extrusion of polar body-like fragments from the vegetal pole, where sperm penetration is prerequisite. After germinal vesicle breakdown, cyclin B is localized in the maternal and paternal asters and spindles near the germinal vesicle. These results suggest that germinal vesicle components such as the cdc2-cyclin B complex interact with asters and spindles and can induce unequal cell division. During normal fertilization, paternal centrosomes are likely kept away from the germinal vesicle components, resulting in the inhibition of unequal paternal centrosome-dependent cell division.

Animals↗
PubMed2004

Effect of high pressure gaseous carbon dioxide on the germination of bacterial spores.

Effect of high pressure gaseous carbon dioxide treatment (HGCT) at 6.5 MPa, 35 degrees C on the germination of bacterial spores was investigated. Germination of bacterial spores was estimated by the decrease of heat tolerance. Approximately, 40% of Bacillus coagulans and 70% of Bacillus licheniformis were germinated by HGCT for 120 min at 35 degrees C, respectively. Germination was confirmed by phase contrast microscopy. The effect of hydrostatic pressure treatment (HPT) at 6.5 MPa, 35 degrees C on the germination of B. coagulans and B. licheniformis spores were also investigated. Spores did not germinate by HPT alone at 6.5 MPa for 120 min.

Bacillus↗
PubMed2001

Mitochondrial small ribosomal RNA is a component of germinal granules in Xenopus embryos.

Mitochondrial large rRNA (mtlrRNA) and small rRNA (mtsrRNA) have been identified as components of germinal granules in Drosophila. We have previously reported that mtlrRNA is present on the germinal granules in Xenopus embryos. Here we report that mtsrRNA is also a common component of the germinal granules. Extra-mitochondrial mtsrRNA is localized on the surface of germinal granules in germ plasm from four-cell to blastula stage, then disappears until the completion of gastrulation. This temporal and spatial distribution pattern is identical to that of mtlrRNA. During the stages when both mitochondrial rRNAs are present around the germinal granules, mitochondrial-type ribosomes, typified by their smaller size, were also present on the surface of the germinal granules.

Animals↗
PubMed2004

Impact of water-stress and washing treatments on production, synthesis and retention of endogenous sugar alcohols and germinability of Metarhizium anisopliae blastospores.

The entomopathogenic fungus Metarhizium anisopliae was physiologically manipulated by culturing in liquid culture under a range of water-stress conditions (0.98, 0.97 and 0.96 water activity, a(w)) imposed by either PEG 200, KCl or NaCl at 25 degrees C to optimise blastospore production and quality in terms of accumulation of endogenous compatible solutes and germinability. Optimum spore yield occurred at 0.98a(w), when PEG 200 was the solute. Blastospores produced under different water-stress levels were subjected to hypo-osmotic and iso-osmotic washing treatments before quantification of endogenous sugar alcohols (polyols) and germinability studies. Endogenous amounts of the low molecular weight polyol erythritol were greatly affected by culture age, water-stress and hypotonic or isotonic washing treatment. Endogenous erythritol in blastospores produced under 0.98 and 0.97a(w) increased with culture age. Osmoprotection (washing with isotonic PEG 200 solution) of blastospores produced under all water-stress conditions resulted in retention of higher amounts of erythritol. Increased endogenous retention of the high molecular weight polyol mannitol was also observed with an isotonic washing treatment but only in blastospores produced under intermediate water-stress (0.98 and 0.97a(w)). Germination of all treatments was > 90 % on a medium with freely available water. Under water-stress conditions (0.96a(w)) only 10 % of unmodified blastospores washed with water germinated. However, those grown under modified water availability conditions (0.98a(w)) and washed with isotonic solutions had significantly improved germination (38-90 %). Blastospores produced at < or = 0.97a(w) washed with isotonic solutions had decreased germination. These results could have significant implications for conserving ecophysiological quality of fungal biocontrol propagules during harvesting and have an impact on storage and formulation.

Ascomycota↗
PubMed2006

Real-time detection of kinetic germination and heterogeneity of single Bacillus spores by laser tweezers Raman spectroscopy.

Germination is the process by which a dormant spore returns to its vegetative state when exposed to suitable conditions. We report on the real-time detection of kinetic germination and heterogeneity of single Bacillus thuringiensis spores in an aqueous solution by monitoring the calcium dipicolinate (CaDPA) biomarker with laser tweezers Raman spectroscopy (LTRS). A single B. thuringiensis spore was optically trapped in a focused laser beam, and its Raman spectra were recorded sequentially in time after exposure to a nutrient-rich medium, so that the CaDPA amount inside the trapped spore was monitored during the dynamic germination process. The CaDPA content in an individual spore was observed to remain almost constant in the first period and then decrease very rapidly due to its release into the medium (within approximately 2 min). The time-to-germination (t(germ)), defined as the time required for the CaDPA band intensity to decrease to the midpoint from its initial value, was found to be stochastic for individual spores with a typical value of approximately 30 min under the experimental conditions. The distribution of the time-to-germination was measured from a time lapse measurement of a population of spores. The results demonstrated that LTRS can be used to noninvasively detect the kinetic germination process at the single-cell level and explore cellular heterogeneity.

Bacillus thuringiensis↗
PubMed2003

Defective zoospore encystment and suppressed cyst germination of Phytophthora palmivora caused by transient leaching treatments.

The behaviour of encysting zoospores of Phytophthora palmivora during leaching conditions was studied. Zoospores encysted and germinated successfully on polycarbonate membranes after mechanical agitation. Transient (10 min) leaching treatments with nutrient-free buffer underneath the membranes resulted in abnormal encystment and poor germination. The disruption was greatest when leaching was applied during the first minutes after start of encystment and not observed after 20 min. The early sensitivity of cells to leaching coincided with the period when alkali-resistant cell walls were formed (2-6 min after mechanical agitation). Effects of calcium and organic nutrients on encystment during leaching and germination after these treatments were studied. The disruption of encystment by early leaching treatments, but not the suppression of cyst germination, was overcome by adding calcium chloride during mechanical agitation of zoospores. Leaching with calcium containing buffer resulted in suppressed cyst germination as was the case with buffer alone. Leaching with 0.1% peptone containing buffer promoted consistently high encystment and germination.

Buffers↗