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831.
The nucleoids in Mycoplasma capricolum cells were visualized by phase-combined fluorescence microscopy of DAPI (4', 6-diamidino-2-phenylindole)-stained cells. Most growing cells in a rich medium had one or two nucleoids in a cell, and no anucleate cells were found. The nucleoids were positioned in the center in mononucleoid cells and at one-quarter and three-quarters of the cell length in binucleoid cells. These formations may have the purpose of ensuring delivery of replicated DNA to daughter cells. Internucleoid distances in binucleoid cells correlated with the cell lengths, and the relationship of DNA content to cell length showed that cell length depended on DNA content in binucleoid cells but not in mononucleoid cells. These observations suggest that cell elongation takes place in combination with nucleoid movement. Lipid synthesis was inhibited by transfer of cells to a medium lacking supplementation for lipid synthesis. The transferred cells immediately stopped dividing and elongated while regular spaces were maintained between the nucleoids for 1 h. After 1 h, the cells changed their shapes from rod-like to round, but the proportion of multinucleoid cells increased. Inhibition of protein synthesis by chloramphenicol induced nucleoid condensation and abnormal positioning, although partitioning was not inhibited. These results suggest that nucleoid partitioning does not require lipid or protein synthesis, while regular positioning requires both. When DNA replication was inhibited, the cells formed branches, and the nucleoids were positioned at the branching points. A model for the reproduction process of M. capricolum, including nucleoid migration and cell division, is discussed. 相似文献
832.
Abstract 1. Females of the monophagous shield bug Parastrachia japonensis Scott provision their nymph-containing nests with high-quality drupes of the single host tree, Schoepfia jasminodora , a resource that is poor and unstable, under an array of variable environmental constraints.
2. Although the number of drupes provisioned is correlated positively with enhanced nymphal development and survival, there is great variability in the number of drupes that females provide.
3. The ability to adjust behaviour and/or physiology, i.e. make risk-sensitive decisions, should be adaptive for organisms such as P. japonensis that are confronted with extreme variability in food availability and in the conditions under which they must forage. To assess whether females of this species use risk-sensitivity to improve their provisioning success, data on the parameters of provisioning activity obtained during a long-term field study were analysed. The relationships between variation in three female-controlled factors during nesting (nest site, active stage during the provisioning season, duration of provisioning activity) and the conditions of three environmental factors (drupe availability, intraspecific competition, weather) were examined. The relationships between all of these factors and provisioning capacity of females were investigated.
5. Nest site, intraspecific competition, and timing of provisioning activity only affected provisioning capacity when drupe availability was extremely good or bad or weather was particularly bad.
6. The findings suggest that females use risk-sensitive decisions to increase provisioning capacity under extreme conditions of low and high drupe availability and inclement weather. 相似文献
2. Although the number of drupes provisioned is correlated positively with enhanced nymphal development and survival, there is great variability in the number of drupes that females provide.
3. The ability to adjust behaviour and/or physiology, i.e. make risk-sensitive decisions, should be adaptive for organisms such as P. japonensis that are confronted with extreme variability in food availability and in the conditions under which they must forage. To assess whether females of this species use risk-sensitivity to improve their provisioning success, data on the parameters of provisioning activity obtained during a long-term field study were analysed. The relationships between variation in three female-controlled factors during nesting (nest site, active stage during the provisioning season, duration of provisioning activity) and the conditions of three environmental factors (drupe availability, intraspecific competition, weather) were examined. The relationships between all of these factors and provisioning capacity of females were investigated.
5. Nest site, intraspecific competition, and timing of provisioning activity only affected provisioning capacity when drupe availability was extremely good or bad or weather was particularly bad.
6. The findings suggest that females use risk-sensitive decisions to increase provisioning capacity under extreme conditions of low and high drupe availability and inclement weather. 相似文献
833.
Ishizuka Shintaro Toda Kazuya Furuichi Takeshi 《International journal of primatology》2020,41(2):401-414
International Journal of Primatology - Relationships between females of different groups in female philopatric species are typically antagonistic, whereas those in female dispersing species can be... 相似文献
834.
Suzuki T Semba S Sunden Y Orba Y Kobayashi S Nagashima K Kimura T Hasegawa H Sawa H 《Microbiology and immunology》2012,56(9):639-646
JC virus (JCV) belongs to the polyomavirus family of double-stranded DNA viruses and causes progressive multifocal leukoencephalopathy in humans. JCV encodes early proteins (large T antigen, small T antigen, and T' antigen) and four late proteins (agnoprotein, and three viral capsid proteins, VP1, VP2, and VP3). In the current study, a novel function for JCV agnoprotein in the morphogenesis of JC virion particles was identified. It was found that mature virions of agnoprotein-negative JCV are irregularly shaped. Sucrose gradient sedimentation and cesium chloride gradient ultracentrifugation analyses revealed that the particles of virus lacking agnoprotein assemble into irregularly sized virions, and that agnoprotein alters the efficiency of formation of VP1 virus-like particles. An in vitro binding assay and immunocytochemistry revealed that agnoprotein binds to glutathione S-transferase fusion proteins of VP1 and that some fractions of agnoprotein colocalize with VP1 in the nucleus. In addition, gel filtration analysis of formation of VP1-pentamers revealed that agnoprotein enhances formation of these pentamers by interacting with VP1. The present findings suggest that JCV agnoprotein plays a role, similar to that of SV40 agnoprotein, in facilitating virion assembly. 相似文献
835.
Hirotaka Toh Takashi Nozawa Atsuko Minowa-Nozawa Miyako Hikichi Shintaro Nakajima Chihiro Aikawa 《Autophagy》2020,16(2):334-346
ABSTRACTAutophagy selectively targets invading bacteria to defend cells, whereas bacterial pathogens counteract autophagy to survive in cells. The initiation of canonical autophagy involves the PIK3C3 complex, but autophagy targeting Group A Streptococcus (GAS) is PIK3C3-independent. We report that GAS infection elicits both PIK3C3-dependent and -independent autophagy, and that the GAS effector NAD-glycohydrolase (Nga) selectively modulates PIK3C3-dependent autophagy. GAS regulates starvation-induced (canonical) PIK3C3-dependent autophagy by secreting streptolysin O and Nga, and Nga also suppresses PIK3C3-dependent GAS-targeting-autophagosome formation during early infection and facilitates intracellular proliferation. This Nga-sensitive autophagosome formation involves the ATG14-containing PIK3C3 complex and RAB1 GTPase, which are both dispensable for Nga-insensitive RAB9A/RAB17-positive autophagosome formation. Furthermore, although MTOR inhibition and subsequent activation of ULK1, BECN1, and ATG14 occur during GAS infection, ATG14 recruitment to GAS is impaired, suggesting that Nga inhibits the recruitment of ATG14-containing PIK3C3 complexes to autophagosome-formation sites. Our findings reveal not only a previously unrecognized GAS-host interaction that modulates canonical autophagy, but also the existence of multiple autophagy pathways, using distinct regulators, targeting bacterial infection.Abbreviations: ATG5: autophagy related 5; ATG14: autophagy related 14; ATG16L1: autophagy related 16 like 1; BECN1: beclin 1; CALCOCO2: calcium binding and coiled-coil domain 2; GAS: group A streptococcus; GcAV: GAS-containing autophagosome-like vacuole; LAMP1: lysosomal associated membrane protein 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTORC1: mechanistic target of rapamycin kinase complex 1; Nga: NAD-glycohydrolase; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; PtdIns3P: phosphatidylinositol-3-phosphate; PtdIns4P: phosphatidylinositol-4-phosphate; RAB: RAB, member RAS oncogene GTPases; RAB1A: RAB1A, member RAS oncogene family; RAB11A: RAB11A, member RAS oncogene family; RAB17: RAB17, member RAS oncogene family; RAB24: RAB24, member RAS oncogene family; RPS6KB1: ribosomal protein S6 kinase B1; SLO: streptolysin O; SQSTM1: sequestosome 1; ULK1: unc-51 like autophagy activating kinase 1; WIPI2: WD repeat domain, phosphoinositide interacting 2 相似文献
836.
Butyric acid is one of the major extracellular metabolites of periodontopathic Gram-negative bacteria. We previously demonstrated that butyric acid induced apoptosis in human T cells. In the present study, we examined the interaction between butyric acid and TNF-alpha in Jurkat T-cell apoptosis. Simultaneous treatment with TNF-alpha enhanced butyric acid-induced apoptosis by promoting caspase activity more than was achieved by either reagent alone. We examined which genes were associated with the increased susceptibility to TNF-alpha caused by butyric acid, and revealed that expression of cFLIP decreased with increased concentrations of butyric acid. Furthermore, exogenous expression of cFLIP protein suppressed the enhancing effect by TNF-alpha in the apoptosis. These results suggest that butyric acid downregulates cFLIP expression and increases the susceptibility to TNF-alpha by activating caspases via the death receptor signal. 相似文献
837.
Masataka Oda Mie Kurosawa Hirofumi Yamamoto Hisanori Domon Shoji Takenaka Tatsuya Ohsumi Tomoki Maekawa Naoto Yamasaki Yui Furue Yutaka Terao 《Microbiology and immunology》2020,64(7):493-501
Streptococcus mutans is the main pathogen of dental caries and adheres to the tooth surface via soluble and insoluble glucans produced by the bacterial glucosyltransferase enzyme. Thus, the S. mutans glucosyltransferase is an important virulence factor for this cariogenic bacterium. Sulfated vizantin effectively inhibits biofilm formation by S. mutans without affecting its growth. In this study, less S. mutans biofilm formation occurred on hydroxyapatite discs coated with sulfated vizantin than on noncoated discs. Sulfated vizantin showed no cytotoxicity against the human gingival cell line Ca9-22. Sulfated vizantin dose-dependently inhibited the extracellular release of cell-free glucosyltransferase from S. mutans and enhanced the accumulation of cell-associated glucosyltransferase, compared with that observed with untreated bacteria. Sulfated vizantin disrupted the localization balance between cell-associated glucosyltransferase and cell-free glucosyltransferase, resulting in inhibited biofilm maturation. These results indicate that sulfated vizantin can potentially serve as a novel agent for preventing dental caries. 相似文献
838.
Jun-Hye Shin Kohki Yoshimoto Yoshinori Ohsumi Jong-seong Jeon Gynheung An 《Molecules and cells》2009,27(1):67-74
Autophagy degrades toxic materials and old organelles, and recycles nutrients in eukaryotic cells. Whereas the studies on
autophagy have been reported in other eukaryotic cells, its functioning in plants has not been well elucidated. We analyzed
the roles of OsATG10 genes, which are autophagy-related. Two rice ATG10 genes - OsATG10a and OsATG10b - share significant sequence homology (about 75%), and were ubiquitously expressed in all organs examined here. GUS assay
indicated that OsATG10b was highly expressed in the mesophyll cells and vascular tissue of younger leaves, but its level of expression decreased
in older leaves. We identified T-DNA insertional mutants in that gene. Those osatg10b mutants were sensitive to treatments with high salt and methyl viologen (MV). Monodansylcadaverine-staining experiments showed
that the number of autophagosomes was significantly decreased in the mutants compared with the WT. Furthermore, the amount
of oxidized proteins increased in MV-treated mutant seedlings. These results demonstrate that OsATG10b plays an important
role in the survival of rice cells against oxidative stresses. 相似文献
839.
Misaki Sakashita Shintaro Yamasaki Kentaro Yaji Atsushi Kawamoto Shigeru Kondo 《PLoS computational biology》2021,17(6)
Elucidation of the mechanism by which the shape of bones is formed is essential for understanding vertebrate development. Bones support the body of vertebrates by withstanding external loads, such as those imposed by gravity and muscle tension. Many studies have reported that bone formation varies in response to external loads. An increased external load induces bone synthesis, whereas a decreased external load induces bone resorption. This relationship led to the hypothesis that bone shape adapts to external load. In fact, by simulating this relationship through topology optimization, the internal trabecular structure of bones can be successfully reproduced, thereby facilitating the study of bone diseases. In contrast, there have been few attempts to simulate the external structure of bones, which determines vertebrate morphology. However, the external shape of bones may be reproduced through topology optimization because cells of the same type form both the internal and external structures of bones. Here, we constructed a three-dimensional topology optimization model to attempt the reproduction of the external shape of teleost vertebrae. In teleosts, the internal structure of the vertebral bodies is invariable, exhibiting an hourglass shape, whereas the lateral structure supporting the internal structure differs among species. Based on the anatomical observations, we applied different external loads to the hourglass-shaped part. The simulations produced a variety of three-dimensional structures, some of which exhibited several structural features similar to those of actual teleost vertebrae. In addition, by adjusting the geometric parameters, such as the width of the hourglass shape, we reproduced the variation in the teleost vertebrae shapes. These results suggest that a simulation using topology optimization can successfully reproduce the external shapes of teleost vertebrae. By applying our topology optimization model to various bones of vertebrates, we can understand how the external shape of bones adapts to external loads. 相似文献
840.
Dependence of removal of sperm-specific proteins from Xenopus sperm nuclei on the phosphorylation state of nucleoplasmin 总被引:1,自引:0,他引:1
Keita Ohsumi Arata Shimada Eiichi Okumura Takeo Kishimoto Chiaki Katagiri 《Development, growth & differentiation》1995,37(3):329-336
In Xenopus laevis , nucleoplasmin from fully grown oocytes is not highly phosphorylated, but is more extensively phosphorylated during oocyte maturation to retain this state until mid-blastula transition. Incubation of demembranated sperm with nucleoplasmin from oocytes or mature eggs revealed that egg nucleoplasmin is twice as potent as oocyte nucleoplasmin in removing sperm-specific basic proteins from chromatin (protamine-removing activity: PRA). Dephosphorylation of egg nucleoplasmin by alkaline phosphatase induced a remarkable decline of PRA in nucleoplasmin. Treatment of oocyte nucleoplasmin with cdc2 protein kinase induced an increase of the extent of phosphorylation, but to a level lower than that exhibited by egg nucleoplasmin, suggesting the involvement of other unspecified kinase(s) in phosphorylating nucleoplasmin during oocyte maturation. Incubation of sperm with cdc2 kinase induced selective phosphorylation of sperm-specific basic proteins, accompanied by their enhanced removal from sperm chromatin upon exposure to high-salt solutions. These results suggest that removal of sperm-specific basic proteins from sperm chromatin in fertilized eggs is facilitated by phosphorylation of both nucleoplasmin and sperm-specific basic proteins. 相似文献