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PubMed1985

Germinability of coat-lacking spores of Bacillus megaterium.

Upon treatment with acid, the germinability of both intact and coat-lacking spores of Bacillus megaterium ATCC 19213 exhibited similar features. Namely, when the spores previously germinated by alanine in the presence of phosphate buffer were converted to H-spores by treatment with nitric acid, germination proceeded at a very low speed in a same germination medium. When H-spores converted to Ca-spores by treatment with calcium acetate and subsequently germinated, germination proceeded at a speed higher than that of native spores and occurred even in the absence of buffer. These results suggest that the site of exchangeable cations concerned with germinability must not exist in the coat.

Alanine↗
PubMed1987

Acid rain and pollen germination in corn.

The properties of an acid rain episode that could influence the germination of pollen in corn, Zea mays L., were evaluated by treating silks with a simulated acid rain and measuring the subsequent germination of pollen on the silks. The data indicated that acid rain creates an inhospitable environment for pollen germination on the silk surface. Reduced germination appeared directly related to the acidity of the rain, but not the sulphate concentration. Rinsing silks with a pH 5.6 rain after treatment with a pH 2.6 rain did not increase pollen germination above that on silks treated only with a pH 2.6 rain, suggesting the reduced germination was due to physical and/or chemical modifications of the silk surface and not to residual acid on the tissue. Pollen germination on silks was inhibited even when silk tissue was exposed to a simulated rain of pH 2.6 for <1.5min.

Journal Article↗
PubMed1981

Influence of cations on lysozyme-induced germination of coatless spores of Clostridium perfringens 8-6.

Bacterial endospore germination is powerfully influenced by inorganic salts, cations having especially important effects. Spores of Clostridium perfringens 8-6 are unusual in lacking a spore coat; these spores germinate only in the presence of lysozyme, which readily digests the exposed cortex. Lysozyme-induced germination showed the same response to ionic strength and valence of cations as does lysozyme hydrolysis of peptidoglycan, and close parallels are evident in the influence of inorganic cations on germination of normal spores. La3+ and transition element cations inhibited lysozyme-induced germination at low concentration, again demonstrating parallels with their action on lysozyme digestion of peptidoglycan and on the germination of normal spores. The poly-cations poly(L-lysine) and Ruthenium Red inhibited at extremely low concentrations. Mn2+ and Co2+, at appropriately low concentrations, stimulated lysozyme germination of 8-6 spores and also lysis of Micrococcus lysodeikticus.

Cations↗
PubMed2006

Germination polarity of Beauveria bassiana conidia and its possible correlation with virulence.

Three different germination types of conidia; unidirectional, bidirectional and multidirectional, were revealed through microscopic observations for eight Beauveria bassiana isolates germinated on Sabouraud dextrose agar. Canonical correlation analysis indicated that there is a positive correlation between unidirectional germination and virulence against diamondback moth, Plutella xylostella and the Colorado potato beetle, Leptinotarsa decemlineata. Scanning electron microscopy revealed different in vivo behaviors for unipolar- and bipolar-germinated conidia. Unipolar-germinated conidia produced a strong germ tube with mostly appressorium-like structures while bipolar-germinated conidia continued to invasive hyphal growth without any penetration, indicating that germination polarity in one way or another may be an indicator of pathogenic ability.

Animals↗
PubMed2003

Attachment and germination of Entomophaga maimaiga conidia on host and non-host larval cuticle.

The lepidopteran-specific fungal pathogen Entomophaga maimaiga is highly virulent against Lymantria dispar (gypsy moth) larvae, and other members of the family Lymantriidae. Numerous species in the subfamily Cuculliinae (Family Noctuidae) are not susceptible to E. maimaiga due to the inability of this fungus to penetrate the larval cuticle. Conidial attachment and germination were compared among five cuculliine species and L. dispar using bioassays and scanning electron microscopy. Although conidia were showered evenly across larvae during bioassays, on L. dispar conidia were most abundant on segments, where they adhered well to the cuticle and germinated at high percentages. Conidia on cuculliine cuticles were predominantly found in large, loose aggregations in intersegmental areas. Few conidia on cuculliine cuticle germinated and scanning electron microscopy revealed a thick film of mucous enveloping conidia. We hypothesize that the conidia on cuculliines become coated by this film and were only loosely attached to the larval cuticle. No such film was seen on L. dispar larvae where individual conidia appeared well attached. On L. dispar larvae many conidia also adhered to setae. To determine if hydrophobicity affected the ability of E. maimaiga conidia to attach and germinate on a substrate, a goniometer was used to determine relative hydrophobicity of larval cuticles. L. dispar cuticle was more hydrophobic than cuculliine cuticle, suggesting that a high level of hydrophobicity could be a required characteristic for hosts. Cuticles from four cuculliine species and L. dispar were sequentially extracted using hexane, chloroform, and methanol. Conidia were showered onto glass slides coated with the different extracts and germination was quantified. Methanol extracts of cuculliine cuticle consistently decreased germination, compared to all extracts of L. dispar cuticle. For all L. dispar extracts, the majority of conidia produced germ tubes, which is a normal prerequisite for cuticular penetration. For the cuculliines, conidia exposed to hexane and chloroform extracts produced secondary conidia as did all controls, but the conidia exposed to cuculliine methanol extracts that germinated produced germ tubes. These studies demonstrated that a range of factors act in concert to prevent E. maimaiga infection of the cuculliine species investigated.

Animals↗
PubMed2001

Overexpression of DnaK from a halotolerant cyanobacterium Aphanothece halophytica enhances the high-temperatue tolerance of tobacco during germination and early growth.

DnaK1 from a halotolerant cyanobacterium Aphanothece halophytica, was overexpressed in the cytosol of tobacco. When the control and transgenic tobacco seeds were incubated at 27 degrees C, more than 95% of the control and transgenic tobacco seeds germinated. However, at a high incubation temperature, 40 degrees C, only 27% of the control seeds germinated whereas 82% of the transgenic seeds germinated. High temperature treatment during the imbibition of seeds delayed germination more in the control plants than in the transformants although the maximum percentage of germination was similar in both plants. The quantum yields of electron transport and plant elongation were higher in the transformant during high temperature treatment in young seedlings, but similar in older leaves. DnaK1 was detected in small amounts in seeds and its levels increased during germination. These data indicate that the expression of DnaK1 from a halotolerant cyanobacterium A. halophytica improved the tolerance to high temperature during germination and early growth.

Journal Article↗
PubMed2001

Differential induction of Orobanche seed germination by Arabidopsis thaliana.

Parasitic plants, including the root holoparasites Orobanche spp., cause devastating damage to crops worldwide. Arabidopsis thaliana (L.) is widely used an amenable model for the study of plant biology, including plant-pathogen interactions. Bringing the two plants together in a controlled system will enable the study of the molecular and genetic basis involved in host-parasitic plant interactions and should provide tools for the detection of genes responsible for incompatibility and resistance responses. The objective of this study was to screen Arabidopsis lines for reduced germination of Orobanche seeds. A 96-cell well bioassay was developed to test the potential of lines, ecotypes and mutants of Arabidopsis to induce germination of Orobanche. Screening of 50 A. thaliana ecotypes did not reveal non-inducing ecotypes. Screening of 13000 A. thaliana fast neutron mutated M2 plants detected 94 non-inducing mutant plants of which 34 were rescued, self pollinated, and M3 seeds collected. M3 seedlings from five lines were reduced in their ability to induce germination. In a separate assay, we determined that the reduced germination rates corresponded with reduced distance from the roots at which germination occurred. While further studies are necessary to determine the segregation of low germination phenotypes, these lines might prove useful for studying the genetic basis of variation in germination stimulant production in A. thaliana.

Journal Article↗
PubMed1999

Singlet oxygen is part of a hyperoxidant state generated during spore germination.

We show that singlet oxygen is generated in asexual spores (conidia) from Neurospora crassa at the onset of germination. Oxidation of N. crassa catalase-1 (Cat-1) was previously shown to be caused by singlet oxygen (Lledías et al. J. Biol. Chem. 273, 1998). In germinating conidia, increased protein oxidation, decrease of total protein, Cat-1 oxidation and accumulation of cat-1 mRNA was detected. These changes were modulated in vivo by light intensity, an external clean source of singlet oxygen, and by carotene amount and content of coordinated double bonds. Conditions that stimulated singlet oxygen formation increased Cat-1 oxidation and accumulation of cat-1 mRNA. Germinating conidia from mutant strains altered in carotene synthesis showed increased levels of protein degradation, Cat-1 oxidation and accumulation of cat-1 mRNA. During germination Cat-1a was oxidized, oxidized Cat-1c-Cat-1e conformers disappeared and Cat-1a was synthesized de novo. Furthermore, spontaneous oxygen-dependent chemiluminescence increased as soon as conidia absorbed dissolved oxygen. Low-level chemiluminescence is due to photon emission from excited electrons in carbonyls and singlet oxygen as they return to their ground state. H2O2 added to conidia under Ar caused a peak of chemiluminescence and germination of 20% of conidia, suggesting that a hyperoxidant state suffices to start germination under anaerobic conditions. Taken together, these results show that singlet oxygen is part of a hyperoxidant state that develops at the start of germination of conidia, in consonance with our proposal that morphogenetic transitions occur as a response to a hyperoxidant state.

Catalase↗
PubMed2002

Differential expression of desaturases and changes in fatty acid composition during sporangiospore germination and development in Mucor rouxii.

Polyunsaturated fatty acids (PUFAs), namely, oleic (C18:1), linoleic (C18:2), and gamma-linolenic acid (C18:3), constituted the majority in the total fatty acid content (44%) of sporangiospores of Mucor rouxii. At 30 degrees C, the germination begins within 1h at which time spore swelling occurs, followed by germ tube emergence within 3-4h. Throughout germination, an increase in gamma-linolenic acid (GLA) was observed and its content was highest at germ tube emergence. It took longer for sporangiospores of M. rouxii to germinate at sub-optimal temperatures (15 and 35 degrees C). However, the content of GLA was higher at the germ tube initiation than at the mycelial stage at all temperatures, suggesting the association of GLA and germination of sporangiospores. This finding was substantially confirmed by differential expression of delta9-, delta12-, and delta6-desaturase genes measured during spore germination. The expression of three desaturase genes parallels the pattern of GLA synthesis. By using RT-PCR techniques to follow gene expression, we found that mRNA of delta12- and delta6-desaturase genes were translated as soon as the spores were introduced into a fresh medium while the mRNA of delta9-desaturase gene could not be detected until 2h after introduction. A sharp increase in mRNA of delta6-desaturase genes correlated well with an increase in GLA content at germ tube emergence (4h). These results demonstrated that changes in fatty acid composition of sporangiospore of M. rouxii and differential expression of desaturase genes occurred during germination, and that extensive changes in GLA synthesis associated with some events in germination process.

Fatty Acid Desaturases↗
PubMed1999

The role of peptidoglycan structure and structural dynamics during endospore dormancy and germination.

Dormant, bacterial endospores are the most resistant living structures known. The spore cell wall (cortex) maintains dormancy, core dehydration, and heat resistance. The cortex peptidoglycan has a unique, spore specific structure that enables it to fulfill its role. The cross-linking index of spore cortex peptidoglycan is very low, occurring at only 2.9% of the muramic acid residues compared to 33% in vegetative cells. The level of cross-linking of the cortex may be important in maintaining spore dormancy and heat resistance. Approximately 50% of the muramic acid residues in spore cortex are substituted with muramic delta-lactam. This modification is spore specific and is the major characteristic feature of the cortex. The muramic delta-lactam has no apparent role in establishing core dehydration, maintaining dormancy or heat resistance. However, the muramic delta-lactam residues are necessary for spore cortex hydrolysis during germination. They constitute part of the substrate recognition profile of the germination specific lytic enzymes (GSLEs) which are responsible for cortex hydrolysis. Germination results in loss of dormant spore properties and hydrolysis of the cortex is essential for later germination events and outgrowth. Application of muropeptide analysis to determine peptidoglycan structural dynamics during germination has revealed an unexpected degree of complexity in peptidoglycan hydrolysis. At least three hydrolytic activities, an N-acetyl glucosaminidase, a lytic transglycosylase and a possible amidase, are involved. A non-hydrolytic activity, likely to be an epimerase of muramic acid also occurs early during germination. The lytic transglycosylase generates anhydro-muropeptides which are released during germination and may be recycled during outgrowth to form part of the new vegetative cell wall.

Bacillus subtilis↗
PubMed2001

Characterization of vibrissa germinative cells: transition of cell types.

Germinative cells, small cell masses attached to the stalks of dermal papillae that are able to differentiate into the hair shaft and inner root sheath, form follicular bulb-like structures when co-cultured with dermal papilla cells. We studied the growth characteristics of germinative cells to determine the cell types in the vibrissa germinative tissue. Germinative tissues, attaching to dermal papillae, were cultured on 3T3 feeder layers. The cultured keratinocytes were harvested and transferred, equally and for two passages, onto lined dermal papilla cells (LDPC) and/or 3T3 feeder layers. The resulting germinative cells were classified into three types in the present experimental condition. Type 1 cells grow very well on either feeder layer, whereas Type 3 cells scarcely grow on either feeder layer. Type 2 cells are very conspicuous and are reversible. They grow well on 3T3 but growth is suppressed on LDPC feeder layers. The Type 2 cells that grow well on 3T3 feeder layers, however, are suppressed when transferred onto LDPC and the Type 2 cells that are suppressed on LDPC begin to grow again on 3T3. The transition of one cell type to another in vitro and the cell types that these germinative cell types correspond to in vivo is discussed. It was concluded that stem cells or their close progenitors reside in the germinative tissues of the vibrissa bulb except at late anagen-early catagen.

3T3 Cells↗
PubMed1982

Zinc release and the sequence of biochemical events during triggering of Bacillus megaterium KM spore germination.

Zinc release is the first quantitatively significant event detected during the triggering of Bacillus megaterium KM spore germination. Of the total spore Zn2+ pool 25% is released from non-heat-activated spores within 4 min of triggering germination. During this period only 10% of the spore population becomes irreversibly committed to germinate. The investigation of a putative role for Zn2+ in the germination trigger mechanism has established a relationship between the rate and extent of Zn2+ release and the stimulation of spore germination by heat activation. Furthermore, a correlation can be demonstrated between the extent of zinc release from spore populations and the time required to obtain 50% commitment of these populations to germinate over a wide temperature range. These findings have been used to expand a recently published model for the triggering of bacterial spore germination.

Bacillus megaterium↗
PubMed1985

Role of uricase in the triggering of germination of Bacillus fastidiosus spores.

The likelihood that uric acid was the only compound capable of triggering germination of Bacillus fastidiosus spores was reinforced by the finding that ureidoglycollic acid, urea, NH4Cl, 2,8-dihydroxypurine and a combination of L-alanine and O-carbamoyl-D-serine were ineffective as germinants. Uric acid-triggered germination of B. fastidiosus was prevented by a range of inhibitors that also inhibited uricase activity in dormant spore extracts. O2 uptake during germination started immediately after addition of uric acid, possibly as a consequence of the oxidation of uric acid by the enzyme uricase. Germination showed a dependence on uric acid concentration, with a relatively high Km (4-5 mM). During the first 10 min of germination of heat-activated spores there was no detectable change in the number of spore-cortex reducing groups, indicating that selective cortex hydrolysis is not involved in the trigger mechanism of germination of B. fastidiosus. On the basis of the results, a model is proposed in which re-initiation of uricase activity is the mechanism by which B. fastidiosus spores are triggered to emerge from the dormant state.

Adenosine Triphosphate↗
PubMed1998

Mode of phytochrome B action in the photoregulation of seed germination in Arabidopsis thaliana.

Arabidopsis thaliana seeds imbibed for a short duration show phytochrome B (PhyB)-specific photo-induction of germination. Using this system, the relationship was determined between the amount of PhyB in seeds and photon energy required for PhyB-specific germination in two transgenic Arabidopsis lines transformed with either the Arabidopsis PhyB cDNA (ABO) or the rice PhyB cDNA (RBO). Immunochemical detection of PhyB apoprotein (PHYB) showed that the expression level of PHYB in ABO seeds was at least two times higher than that in the wild-type seeds, but in RBO seeds the PHYB level was indistinguishable from that in wild-type seeds. The photon fluence required for induction and photoreversible inhibition of germination was examined using the Okazaki large spectrograph. At the wavelengths of 400-710 nm, the ABO seeds required significantly less photon fluence than wild-type seeds for induction of germination, whereas the RBO seeds required similar fluence to wild-type seeds. A critical threshold wavelength for either induction or inhibition of germination of ABO seeds shifted towards the longer wavelengths relative to wild-type seeds. By assuming that PhyA and PhyB are similar in their photochemical parameters, amounts of Pfr at each wavelength were calculated. The photon fluence required for 50% germination was equivalent to the fluence generating a Pfr/Ptot ratio of 0.21-0.43 in wild-type seeds, and of 0.035-0.056 in ABO seeds. These results indicate that PhyB-specific seed germination is not strictly a function of the Pfr/Ptot ratio, but is probably a function of the absolute Pfr concentration.

Arabidopsis↗
PubMed2003

Inducible beta-glucosidase synthesis during germination and outgrowth of Bacillus subtilis ATCC 9372 spores.

AIMS: To investigate the role of germination processes in the expression of the beta-glucosidase enzyme in Bacillus subtilis ATCC 9372 spores. METHODS AND RESULTS: Enzyme activity was monitored in germinating and non-germinating spores of B. subtilis ATCC 9372. The expression of beta-glucosidase by spores of B. subtilis was further investigated in the presence of a germination inhibitor, d-alanine, and a transcription inhibitor, novobiocin. Detection of enzyme activity required the presence of the germinant, l-alanine, as well as the inducer, 4-methylumbelliferryl-beta-d-glucoside. Furthermore, beta-glucosidase synthesis was abolished in the presence of d-alanine or novobiocin. CONCLUSIONS: The data obtained in this study indicated that beta-glucosidase was not pre-existing, or merely attached to the spore, but was synthesized de novo during spore germination. SIGNIFICANCE AND IMPACT OF THE STUDY: The requirement of functional germination processes for the detection of beta-glucosidase activity makes this enzyme a good candidate for detection of spore viability.

Alanine↗
PubMed1987

Cell patterning in pigment-chimeric eyes of Xenopus: local cues control the decision to become germinal cells.

Between 2.5 and 4 days of development, cell proliferation in the Xenopus eye becomes confined to a narrow ring of germinal cells at the front rim of the eye cup. Continued growth of the eye (which lasts until well beyond metamorphosis) is by the continued proliferation of cells in this germinal zone. To determine what factor(s) promotes cell division in this region of the eye long after it ceases at the back of the eye (near the optic nerve), we have transplanted small groups of eye cells from pigmented donor embryos into the eyes of albino hosts, transposing cells from the mitotically quiescent back of the eye to the germinal zone and vice versa. Regardless of their position of origin in the donor eye, only implants into the host germinal zone behaved like germinal cells--as assayed in the living growing eye by the addition of black tissue to the pigment retinal epithelium. Conversely when donor germinal cells were implanted into the back of the host eye, they ceased dividing once they became integrated into the eye and remained as a tiny black spot on the back of the host eye. This suggests that local environmental cues, rather than intrinsic cellular determinants, specify the fates of eye cells ensuring that cells on the eye rim will continue to function as germinal cells while others will withdraw from the cell cycle.

Animals↗
PubMed2002

mRNA decay is rapidly induced after spore germination of Saccharomyces cerevisiae.

Spores from the yeast Saccharomyces cerevisiae can germinate and resume their vegetative growth when placed in favorable conditions. Biochemical studies on germination have been limited by the difficulty of obtaining a pure population of spores germinating synchronously. Here, we report that spores can be purified and sorted according to their size by centrifugal elutriation and that these spores are able to germinate synchronously. Synchronizing their development has allowed reevaluating certain parameters of germination, and we demonstrate that both transcription and translation are induced very rapidly after germination induction. Spores contain mRNAs that are stable for several months in spores kept at 4 degrees C. Germination induction leads to very rapid degradation of these mRNAs, thus providing a simple model to study induction of mRNA decay in eukaryotes. mRNAs from the spore are polyadenylated, capped, and cosediment on sucrose gradients with ribosomes and polysomes and with components of the mRNA degradation machinery. The presence of polysomes in the spores led us to evaluate the activity of the translation apparatus in these cells. We present evidence that there is ongoing transcription and translation in nongerminating yeast spores incubated in water at 30 degrees C, suggesting that these activities could play a role in spore long term survival.

Base Sequence↗
PubMed1994

Biochemical and pharmacological factors causing induction and suppression of germination of Trichosporon beigelii.

Trichosporon beigelii is an emerging fungal pathogen, which is morphologically characterized by blastoconidia, arthroconidia and hyphae. The non-hyphal forms of T. beigelii germinate to form hyphae in plasma in vitro and in tissues in vivo, suggesting possible pathophysiological significance of this process. Little is known, however, about the mechanisms of germination of T. beigelii. We therefore studied relevant biochemical and pharmacological factors that may regulate germination of T. beigelii. Germination was significantly enhanced by temperature at 37 degrees C, chemically defined cell culture media such as RPMI-1640, plasma, physiological pH, N-acetylglucosamine and proline. N-acetylglucosamine was equivalent to proline in inducing germination. Germination was suppressed by high concentrations of glucose, increasing inocula, low pH, and amphotericin B at achievable serum concentrations. Thus, many of the factors regulating germination of T. beigelii appear to be similar to those for Candida albicans.

Amino Acids↗