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PubMed1998

Regulation and characterization of a newly deduced cell wall hydrolase gene (cwlJ) which affects germination of Bacillus subtilis spores.

The predicted amino acid sequence of Bacillus subtilis ycbQ (renamed cwlJ) exhibits high similarity to those of the deduced C-terminal catalytic domain of SleBs, the specific cortex-hydrolyzing enzyme of B. cereus and the deduced one of B. subtilis. We constructed a cwlJ::lacZ fusion in the B. subtilis chromosome. The beta-galactosidase activity and results of Northern hybridization and primer extension analyses of the cwlJ gene indicated that it is transcribed by EsigmaE RNA polymerase. cwlJ-deficient spores responded to both L-alanine and AGFK, the A580 values of spore suspensions decreased more slowly than in the case of the wild-type strain, and the mutant spores released less dipicolinic acid than did those of the wild-type strain during germination. However, the mutant spores released only slightly less hexosamine than did the wild-type spores. In contrast, B. subtilis sleB spores did not release hexosamine at a significant level. While cwlJ and sleB spores were able to germinate, CJSB (cwlJ sleB) spores could not germinate but exhibited initial germination reactions, e.g., partial decrease in A580 and slow release of dipicolinic acid. CJSB spores became slightly gray after 6 h in the germinant, but their refractility was much greater than that of sleB mutant spores. The roles of the sleB and cwlJ mutations in germination and spore maturation are also discussed.

Alanine↗
PubMed1961

L-Alanine dehydrogenase: a mechanism controlling the specificity of amino acid-induced germination of Bacillus cereus spores.

O'Connor, R. J. (University of Wisconsin, Madison), and Harlyn O. Halvorson. L-Alanine dehydrogenase: A mechanism controlling the specificity of amino acid-induced germination of Bacillus cereus spores. J. Bacteriol. 82:706-713. 1961.-A study has been undertaken of the properties and specificity of germination of spores of Bacillus cereus strain T. In the absence of additional carbon sources, only l-alanine, l-alpha-NH(2)-n-butyric acid, and l-cysteine were effective germinating agents. The physical properties of germination, induced by l-alanine and l-alpha-NH(2)-n-butyric acid following extended heat shock, were in close agreement with those of l-alanine dehydrogenase. The specificity of the germination system, as well as amino acid deamination in vivo, support the view that l-alanine dehydrogenase activity is essential for germination and that the enzyme serves as the initial binding site for l-alanine in heat-shocked spores.

Alanine↗
PubMed1962

Permeability of bacterial spores. III. Permeation relative to germination.

Black, S. H. (The University of Michigan, Ann Arbor) and Philipp Gerhardt. Permeability of bacterial spores. III. Permeation relative to germination. J. Bacteriol. 83:301-308. 1962.-The passive diffusion of solutes into dormant spores, characterized previously with the test organism Bacillus cereus strain terminalis, has now been examined in relation to germination. Dormant spores did not take up specific germinants differently than they did other compounds, under conditions optimal for germination. Germinated spores, viable but prevented from growing out, displayed some changes in permeability, evidenced by increased total uptake of glucose and water and by observable penetration of a fluorescigenic dye. Heat-killed spores were as permeable to glucose and the dye as germinated ones.

Bacillus cereus↗
PubMed1962

Germination properties of spores with low dipicolinic acid content.

Keynan, A. (University of Wisconsin, Madison), W. G. Murrell, and H. O. Halvorson. Germination properties of spores with low dipicolinic acid content. J. Bacteriol. 83:395-399. 1962.-When the dipicolinic acid content of spores of Bacillus cereus strain T is reduced from 7.5 to 2 or 3%, the spores germinate spontaneously after heat activation and are sluggish in their response to l-alanine and other germination agents. Only germination initiated by calcium dipicolinic acid is unaffected. l-Alanine-induced germination is stimulated by exogenous dipicolinic acid. These results support the hypothesis that endogenous dipicolinic acid regulates the l-alanine-triggered germination.

Alanine↗
PubMed1962

Enzymes of glucose and pyruvate catabolism in cells, spores, and germinated spores of Clostridium botulinum.

Simmons, R. J. (Michigan State University, East Lansing), and R. N. Costilow. Enzymes of glucose and pyruvate catabolism in cells, spores, and germinated spores of Clostridium botulinum. J. Bacteriol. 84:1274-1281. 1962.-An investigation was made of the enzymes of vegetative cells, spores, and germinated spores of Clostridium botulinum 62-A to elucidate a pathway of glucose metabolism. Manometric studies were conducted with intact cells, and various enzymes and enzyme systems were assayed in cell-free and spore-free extracts by use of spectrophotometric and colorimetric procedures. Glucose fermentation was found to be inducible; glucokinase was the controlling enzyme. All other enzymes of the Embden-Meyerhof-Parnas (EMP) pathway were found in both induced and non-induced cells, but they were in relatively low concentrations in the latter. This, plus the fact that no glucose-6-phosphate dehydrogenase was detected, led to the conclusion that glucose is catabolized primarily by the EMP system. A number of glycolytic enzymes were also found in extracts of spores and germinated spores of this organism, but the activities were extremely low as compared with activities in cell extracts. A phosphoroclastic-type reaction was readily demonstrated in both glucose-adapted and non-adapted cells, but not in spores and germinated spores. However, both acetokinase and phosphotransacetylase, as well as coenzyme A transphorase, were detected in spores and germinated-spore extracts, although at very low activity levels as compared with cell extracts. The specific activity of diaphorase in spore extracts was about one-half that of corresponding cell extracts, and the activity of reduced diphosphopyridine nucleotide (DPNH) oxidase was actually higher in the spore extracts. In addition, the DPNH oxidase in spore extracts was considerably more heat-stable than that in extracts of cells or germinated spores.

Carbohydrate Metabolism↗
PubMed1968

Spore germination in strains of Dictyostelium discoideum and other members of the Dictyosteliaceae.

Spores of all strains of Dictyostelium discoideum tested in this study germinated after a heat shock of 45 C for 30 min. Whereas the strains differed in their rates of germination, the rate for each strain was constant. A correlation existed between the rate of germination and the rate of vegetative growth when spores were inoculated into bacterial streaks. Heat shock clearly increased spore germination in D. purpureum, but the response was less dramatic than in D. discoideum. Enhancement also occurred in D. rosarium, but only in media containing peptone. Strains of D. mucoroides gave varied responses, and these could be divided into those which required mutrients for spore germination and those which did not. The spores of Polysphondylium pallidum were resistant to mild heat (45 C), but were not activated; peptone was required for germination. In contrast, the microcysts of this species were heat-labile and required no added nutrients for excystment.

Culture Media↗
PubMed1979

Low temperature induces decreased germinability of Cylindrocladium microsclerotia.

Numbers of germinable Cylindrocladium crotalariae microsclerotia (assayed at 26 degrees C) decreased progressively over 4 weeks when naturally infested soils were incubated at 6 degrees C. Lower numbers of germinable microsclerotia were obtained from a soil incubated at--3 than at 5 degrees C, while no germinable microsclerotia were found for soils incubated at--10 degrees C. Significantly, when soils incubated at--10 or at 6 degrees C for 4 weeks were transferred to 26 degrees C for 4 weeks, the low-temperature effect was partially reversed. Incubation of naturally infested soils under field conditions from October to February indicated that a similar low-temperature induced phenomenon exists in nature. Germinability of axenic laboratory-grown microsclerotia of C. crotalariae, C. floridanum, and C. scoparium incubated 4 weeks at 6 degrees C ranged from 0 to 91% (mean = 38%) of the initial germinability. Partial recovery of laboratory-grown microsclerotia from the low-temperature effect, by incubation at 26 degrees C, was demonstrated. Conductivity measurements of solutions bathing microsclerotia incubated at 6 degrees C were higher than those incubated at 26 degrees C for 4 weeks and indicated that chilling injury may account, in part, for decreased germinability of microsclerotia.

Cold Temperature↗
PubMed1994

Germinal centers.

Germinal centers develop in the B cell follicles of secondary lymphoid tissues during T cell-dependent (TD) antibody responses. The B cells that give rise to germinal centers initially have to be activated outside follicles, in the T cell-rich zones in association with interdigitating cells and T cell help. After immunization with a single dose of protein-based antigen, the germinal centers formed are oligoclonal; on average three B blasts colonize each follicle. These blasts undergo massive clonal expansion and activate a site-directed hypermutation mechanism that acts on their immunoglobulin-variable (Ig-v)-region genes. Mature germinal centers are divided into dark and light zones. The proliferating blasts, centroblasts, occupy the dark zone and give rise to centrocytes that are not in cell cycle and fill the light zone. The light zone contains a rich network of follicular dendritic cells (FDC) that have the capacity to take up antigen and hold this on their surface for periods of more than a year. The antigen is held as an immune complex in a native unprocessed form; but the antigen may be taken up from FDC by B cells, which can process this and present it to T cells. Centrocytes appear to be selected by their ability to interact with antigen held on FDC. There is a high death rate among centrocytes in vivo, and when these cells are isolated in vitro, they undergo apoptosis within hours on culture. The onset of apoptosis can be delayed by cross-linking centrocytes' surface Ig, and long-term survival is achieved by signalling through their surface CD40. After activation through CD40 the centrocytes increase their surface Ig and acquire characteristics of memory and processing of antigen held on FDC and its presentation to T cells that can be induced to express CD40 ligand at the point of cognate interaction. Other signals that induce a proportion of germinal center cells to become plasma cells have also been described. Germinal centers persist for about 3 weeks following immunization, but after this, memory B blasts continue to proliferate in follicles throughout the months of T cell-dependent antibody responses. These cells are probably the source of plasma cells and memory cells required to maintain long-term antibody production and memory after the first 3 weeks of T cell-dependent antibody responses.

Animals↗
PubMed1977

Lymph macrophages enter the germinal center of lymph nodes of guinea pigs.

To determine the fate of macrophages within the afferent lymph stream, the popliteal lymph nodes at various times (3 h to 6 months) after subcutaneous injection of india ink into the footpads of guinea pigs were examined. Two types of cells which had phagocytized india ink were observed in the germinal centers. A small number of type I phagocytes (engulfing india ink as small particles which were often found together with tingible bodies in their cytoplasm) were scattered through the germinal center. A large number of type II phagocytes (packed full of india ink) presented preferentially in the medullary portion of the germinal center, together with many pyroninophil lymphoblastoid cells. In the second experiment, the afferent lymphatics of the popliteal lymph node were ligated 15-20 min after india ink injection. Although the type I phagocytes were distributed as in the first experiment, the type II phagocytes were scanty. In the third experiment, the afferent lymphatics of the popliteal lymph node were ligated 7 days after india ink injection. The type II phagocytes disappeared rapidly from the germinal center, whereas the type I phagocytes remained and were not affected by ligature. These results suggest that the type I phagocytes are the fixed macrophages or tingible body macrophages in the germinal center, and that the type II phagocytes are the macrophages migrating from the peripheral tissues. It was also shown that many macrophages reaching the regional node via afferent lymphatics entered the germinal center through the medullary pole where the cap of small lymphocytes became thinner or disappeared.

Animals↗
PubMed2006

Animal models of germinal matrix hemorrhage.

Germinal matrix hemorrhage refers to bleeding that arises from the subependymal (or periventricular) germinal region of the immature brain. Clinical studies have shown that infants who experience germinal matrix hemorrhage can develop hydrocephalus or suffer from long-term neurologic dysfunction, including cerebral palsy, seizures, and learning disabilities. Understanding the causative factors and the pathogenesis of subsequent brain damage is important if germinal matrix hemorrhage is to be prevented or treated. Appropriate animal models are necessary to achieve this understanding. A number of animal species, including mice, rats, rabbits, sheep, pigs, dogs, cats, and primates, have been used to model germinal matrix hemorrhage. This literature review critically evaluates the animal models of germinal matrix hemorrhage. Each model has its own advantages and disadvantages; no single model is suitable for the study of all aspects of brain damage.

Animals↗
PubMed1985

Gestational changes in the germinal matrix of the normal rhesus monkey fetus.

To explain the reported predisposition to germinal matrix hemorrhage in premature infants, pathogenetically important morphological features of the germinal matrix should be present in the 3rd trimester and rapidly change near term. Such features were sought in this study of the germinal matrix and its vasculature in normal rhesus monkey fetuses. The matrix cells, glia, ependyma, and capillaries showed no important structural changes during the 3rd trimester. The terminal vein tributaries were greatly enlarged by 148 days, but cellular and collagen support in their walls was minimal at this time. The latter features developed by the final days of gestation. These findings do not support a structural immaturity or specialization of the germinal matrix predisposing to germinal matrix hemorrhage. Our results, therefore, support the recent emphasis on physiological parameters in the pathogenesis and prevention of germinal matrix hemorrhage.

Animals↗
PubMed1994

Histone H1 kinase activity, germinal vesicle breakdown and M phase entry in mouse oocytes.

Meiotic reinitiation of the mouse oocyte is characterized by a slow entry into metaphase I, beginning with germinal vesicle breakdown and ending with spindle formation. It is accompanied by a cascade of protein kinases and phosphatases increasing protein phosphorylation. The activation of histone H1 kinase and that of the mitogen-activated protein kinase p42 have been compared during spontaneous or okadaic acid-induced meiotic reinitiation. In spontaneously maturing oocytes, histone H1 kinase activity increases before germinal vesicle breakdown (2-fold), in a protein synthesis-independent manner. It is associated with the disappearance of the upper migrating form of p34cdc2, which, in our system, seems to represent the tyrosine phosphorylated form. Following germinal vesicle breakdown, histone H1 kinase activity culminates (8-fold) in metaphase I and requires protein synthesis. Activation by phosphorylation of p42MAPK is observed as a permanent shift upward-migrating form and by its myelin basic protein kinase activity. It occurs after germinal vesicle breakdown and depends on protein synthesis. In contrast, no increase of histone H1 kinase is detectable in oocytes induced to reinitiate meiosis by a transient inhibition of okadaic acid-sensitive phosphatase(s), either before germinal vesicle breakdown or during the following 7 hours of culture. A slight increase is nevertheless evident after 17 hours, when oocytes are arrested with an abnormal metaphase I spindle. The upper migrating form of p34cdc2 is present for 8 hours. The activation of p42MAPK begins before germinal vesicle breakdown.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Redistribution of cytoplasmic components during germinal vesicle breakdown in starfish oocytes.

The starfish oocyte is relatively clear optically, and its nucleus, termed the germinal vesicle, is large. These characteristics allowed studies by confocal microscopy of germinal vesicle breakdown during maturation in living oocytes. Three fluorescent probes for cytoplasmic components were used: fluorescein 70 kDa dextran, which does not cross the nuclear pore of immature oocytes and probably behaves in the same way as soluble cytosolic proteins, YOYO-1, which was used to localize ribosomes, and DiI which labels the nuclear envelope and endoplasmic reticulum. The first change observable by transmitted light microscopy during maturation is a wrinkling of the germinal vesicle envelope. Several minutes before the wrinkling, the 70 kDa dextran began to enter the germinal vesicle; the ribosomes did not enter during this period. The dextran is likely to be passing through nuclear pores whose size limit has increased but which still exclude ribosomes. At the time of the wrinkling of the germinal vesicle envelope, both 70 kDa dextran and ribosomes entered as a massive wave. The characteristics of this entry indicate that the permeability barrier of the nuclear envelope bilayer has been disrupted. The disruption of the permeability barrier occurred in a local region rather than around the entire periphery. Also, the disruption was observed more often on the animal pole side of the germinal vesicle (26/34 oocytes). The endoplasmic reticulum entered the nuclear region more slowly. Cytochalasin B inhibited this movement and also inhibited characteristic endoplasmic reticulum movements seen at high magnification. The effects of cytochalasin indicate that mixing of endoplasmic reticulum with nuclear space is an active process involving actin filaments.

Animals↗
PubMed1979

Ultrastructural cytochemistry of the nucleus in Zea mays embryos during germination.

The ultrastructure of embryonic root cells of Zea mays was studied from the quiescent stage (dry seed) to 72 h of germination. Semithin and ultrathin sections of tissues fixed with only glutaraldehyde and embedded in Epon were observed after usual section staining and after cytochemical reactions specific for DNA or preferential for ribonucleoproteiNS. In quiescent cells, dense chromatin forms a network which fills a great part of the nucleoplasm. Following germination, gradual dispersion of chromatin occurs: total dispersion is reached at 24 h. After 48 h the chromatin appears moderately condensed again. The nucleolus is compact and predominately fibrillar in dry cells. At 48 h a typical pars granulosa is differentiated. At 8 h a pronounced vacuolation of the nucleolus is observed; nucleolar vacuoles persist until 72 h but become less numerous. During the first 8 h of germination a nucleolus organizer region (NOR) in an eccentric position is associated with the nucleolus; by 24 h and later this NOR has disappeared. No DNA can be visualized in the nucleolar matrix between 0 and 8 h of germination, whereas later, when the nucleolus is reactivated. DNA is always detected in the nucleolar matrix and vacuoles. During the first 72 h of germination, heavily contrasted areas, rich in ribonucleoproteins and appearing to be fibrillar texture, are found in the nucleoplasm, often in closed contact with the dense chromatin. In quiescent cells dense ribonucleoprotein granules, approximately 40 nm in diameter are found dispersed or clustered in the nucleoplasm; after 8 h larger (50 nm), dense ribonucleoprotein granules are found frequently clustered in granular areas in the extranucleolar space. At 8 h of germination, when the nucleolus is temporarily highly vacuolated, unusual 35-nm ribonucleoprotein granules are found both in the smallest vacuoles and on the periphery of the nucleolus.

Cell Nucleolus↗
PubMed1985

Germination of stress-tolerant Eucalyptus pollen.

Earlier reports have indicated that the pollen of Eucalyptus is mechanically robust and unusually resistant to the osmotic stress imposed by immersion in water. We have investigated some of the features of the germination mechanism in the pollen of E. rhodantha with a view to clarifying the role of pollen-wall specializations in determining this resistance. Cultured in vitro, the pollen showed erratic germination, with a scatter of germination times up to 24 h. This was associated with variation between individual grains in the rate of hydration and dispersal of the pectins of the oncus, the thickened outer component of the intine present at each aperture. The oncus is itself differentiated, with a refractive outer layer lying within a sporopollenin operculum and itself overlying the protein-bearing layer of the intine. The outer layer, interpreted as a compacted pectin, undergoes only slow dissolution in aqueous media after the lifting of the operculum, and it is this that apparently protects the grain from the effects of short-term osmotic stress. The rate of dissolution varies between grains, possibly as a consequence of minor differences in developmental rate in the final stages of differentiation in the anther, and this contributes to the wider scatter of germination times. The dehydrated pollen gave one-third of the potential germination after 24 h exposure to 60 degrees C, and a small proportion survived 24 h at 70 degrees C. This degree of heat tolerance must primarily reflect properties of the protoplast of the vegetative cell, not examined in the present study; but the wall specializations may well provide a guard against extreme desiccation, and it is noteworthy that the function of the germination mechanism is not prejudiced by exposure to high temperatures.

Cell Membrane↗
PubMed1981

Impatiens pollen germination and tube growth as a bioassay for toxic substances.

Pollen of Impatiens sultanii Hook F. germinates and forms tubes rapidly at 25 degrees C in a simple medium containing 111.0 ppm CaCl2, 13.6 ppm KH2PO4, and 1000 ppm boric acid. Calcium, potassium, and boron are essential for germination and tube growth, but sucrose is not required. Pollen tubes grow with equal rapidity in liquid medium or on a medium solidified with 1% agar. Tube growth rates are linear for 1 hr. When different pollen sources or clonal sources are utilized, no variation in pollen tube growth is observed, and pollen from individual flowers remain viable for 26 hr. Formaldehyde inhibits pollen germination, tube production, and tube lengths at 7.5-10 ppm. With 2,4-dichlorophenol, pollen germination and tube production is inhibited at 0.5-20 ppm, while tube growth is inhibited significantly at 25 ppm. A biphasic inhibition of germination and tube formation occurs with p-cresol with a low level of inhibition occurring at 40-60 ppm and a higher one at 100-125 ppm. Tube lengths were inhibited at 150 ppm p-cresol. Acrylamide and dioctyl phthalate have no measurable effect upon pollen germination and tube growth.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1984

Formation of lymph follicles and germinal centers in draining lymph nodes after local injection of phytohemagglutinin and lipopolysaccharide in mice.

Changes in the number of lymph follicles and germinal centers in draining popliteal lymph nodes were investigated in 8-week-old mice injected with either phytohemagglutinin (PHA) or lipopolysaccharide (LPS) into the footpad of the left hind leg. The dose of PHA injected ranged from 10 micrograms to 1 mg, and that of LPS, from 2 to 200 micrograms. In unstimulated animals, the popliteal lymph nodes contained only a small number of germinal centers, and many of the lymph follicles in the nodes were in the form of primary follicles. In the draining lymph nodes, regardless of the dose injected, PHA induced germinal center development in existing primary follicles, but eventually failed to stimulate the formation of new lymph follicles and germinal centers. On the other hand, LPS not only induced germinal centers in the existing follicles, but also stimulated the formation of new primary follicles, many of which then developed germinal centers. The occurrence of new follicles in the LPS-treated lymph nodes was dose-dependent, and LPS appeared to cause de novo formation of follicles.

Animals↗
PubMed2004

[Effect of gamma-aminobutyric acid-rich germinated brown rice on indexes of life-style related diseases].

We examined the effects of gamma-aminobutyric acid-rich germinated brown rice (germinated brown rice) on principal indexes of life-style related diseases in 67 volunteers aged 71 +/- 8. They were divided into two groups; germinated brown rice group, which had an equal amount of the germinated brown rice to polished rice for 11 to 13 months, and control group, which had polished rice alone for the same period. Differences of indexes before and after the examination between the two groups were compared. Significant increases in body fat ratio, hemoglobin A1c and mean red cell volume and a significant decrease in mean red cell hemoglobin concentration were observed in the germinated brown rice group. However, there was no difference of changes in body mass index, blood pressure, serum lipid, hepatic and renal functions, bone metabolic markers, bone density, depression score, red blood cell counts, hemoglobin, hematocrit, and homeostasis model assessment of insulin resistance between the two groups. These findings suggested that germinated brown rice might not improve glucose metabolism.

Aged↗