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Shunsuke Yaguchi Atsuko Yamazaki Wakana Wada Yasutaka Tsuchiya Toshihiko Sato Hideo Shinagawa Yutaro Yamada Junko Yaguchi 《Development, growth & differentiation》2015,57(3):242-250
Sea urchins are model non‐chordate deuterostomes, and studying the nervous system of their embryos can aid in the understanding of the universal mechanisms of neurogenesis. However, despite the long history of sea urchin embryology research, the molecular mechanisms of their neurogenesis have not been well investigated, in part because neurons appear relatively late during embryogenesis. In this study, we used the species Temnopleurus reevesii as a new sea urchin model and investigated the detail of its development and neurogenesis during early embryogenesis. We found that the embryos of T. reevesii were tolerant of high temperatures and could be cultured successfully at 15–30°C during early embryogenesis. At 30°C, the embryos developed rapidly enough that the neurons appeared at just after 24 h. This is faster than the development of other model urchins, such as Hemicentrotus pulcherrimus or Strongylocentrotus purpuratus. In addition, the body of the embryo was highly transparent, allowing the details of the neural network to be easily captured by ordinary epifluorescent and confocal microscopy without any additional treatments. Because of its rapid development and high transparency during embryogenesis, T. reevesii may be a suitable sea urchin model for studying neurogenesis. Moreover, the males and females are easily distinguishable, and the style of early cleavages is intriguingly unusual, suggesting that this sea urchin might be a good candidate for addressing not only neurology but also cell and developmental biology. 相似文献
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Yuzuru Hamada Toshifumi Udono Migaku Teramoto Ikuo Hayasaka 《Primates; journal of primatology》1998,39(2):157-169
Skeletal developmental of chimpanzees was studied cross-sectionally. By application of the TW2 method, we described the skeletal
development of chimpanzees and compared their skeletal development with humans'. A development pattern of chimpanzees repeated
accelerations and decelerations displaying “early-juvenile trough,” “pre-adolescent peak,” “mid-adolescent trough,” and “post-adolescent
peak” in incremental curves. Sex differences in skeletal development are slower development in males during infant and early
juvenile phases, and greater increment around the adolescent phase in males. Females are fully mature at younger ages than
males, e.g. about one and a half years. In comparison with chimpanzees, humans have such characteristics as a longer slower
period of juvenile development and a shorter spurt-like adolescent fast period which ends with full maturity. 相似文献
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Takahito Yamashita Miki Kawada‐Matsuo Tamaki Katsumata Atsuko Watanabe Yuichi Oogai Yoshihiro Nishitani Shouichi Miyawaki Hitoshi Komatsuzawa 《Microbiology and immunology》2019,63(7):251-260
Streptococcus mutans is a cariogenic bacterium that localizes in the oral cavity. Glycyrrhetinic acid (GRA) is a major component of licorice extract. GRA and several derivatives, including disodium succinoyl glycyrrhetinate (GR‐SU), are known to have anti‐inflammatory effects in humans. In this study, the antimicrobial effect of GRA and its derivatives against the S. mutans UA159 strain were investigated. Minimum inhibitory concentrations (MICs) of GRA and GR‐SU showed antibacterial activity against the S. mutans strain, whereas other tested derivatives did not. Because GR‐SU is more soluble than GRA, GR‐SU was used for further experiments. The antibacterial activity of GR‐SU against 100 S. mutans strains was evaluated and it was found that all strains are susceptible to GR‐SU, with MIC values below 256 µg/mL. A cell viability assay showed that GR‐SU has a bacteriostatic effect on S. mutans cells. As to growth kinetics, sub‐MICs of GR‐SU inhibited growth. The effect of GR‐SU on S. mutans virulence was then investigated. GR‐SU at sub‐MICs suppresses biofilm formation. Additionally, GR‐SU greatly suppresses the pH drop caused by the addition of glucose and glucose‐induced expression of the genes responsible for acid production (ldh and pykF) and tolerance (aguD and atpD). Additionally, expression of enolase, which is responsible for the carbohydrate phosphotransferase system, was not increased in the presence of GR‐SU, indicating that GR‐SU suppresses incorporation of sugars into S. mutans. In conclusion, GR‐SU has antibacterial activity against S. mutans and also decreases S. mutans virulence. 相似文献
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Egg predation by conspecific males of damselfishes,Pomacentrus nagasakiensis andChromis notatus notatus, was studied at Bohnotsu (31°15′ N, 131°15′ E) and Tsuyazaki (33°47′ N, 130°29′ E), respectively. InP. nagasakiensis, 7 egg-guarding males were removed from nests, and intrusion and egg predation by conspecific males took place in all of
the nests within an average time of 12.2 min. Frequency of attacks on eggs by other reef fishes during the period between
the removal of egg-guarding males and intrusion of conspecific males was lower than expected, considering the frequency of
aggressive displays of the egg-guarding males. The results of male removal experiments forChromis notatus notatus were almost the same, with intrusion and egg predation by conspecific males occurring in all 12 of the nests from which egg-guarding
males had been removed. SixP. nagasakiensis and 15C. notatus notatus which intruded into the nests and preyed on eggs were collected. All were males except for 1C. notatus notatus female. Results suggest that these males which intruded into vacant nests to eat eggs did not have clutches of their own
during the spawning bouts when the experiments were done. Results also showed that the intruding males were not inferior to
egg-guarding males in standard length, gonadosomatic index, and condition factor. It is clear that males which do not have
their own clutches during at least 1 spawning bout and prey on others' eggs when egg-guarding males disappear are common in
these 2 gregariously nesting damselfishes. It is discussed that conspecific eggs are potentially a good food source not only
for other species of reef fishes but also for conspecific males which do not have their own eggs during the spawning bouts.
The origin of males wich prey on eggs of other conspecifics is also considered. Some aspects of egg-guarding and aggressive
behavior of males in damselfishes are discussed. 相似文献
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We present conclusive evidence for the chromosomal location of the lac gene in a lactose-fermenting Salmonella litchfield strain (AO Lac+). Two Hfr strains constructed from AO Lac+ had abilities to transfer the lac gene to S. typhimurium LT2 at relatively high frequencies. Detailed characterization of the transconjugants suggested that the lac in AO Lac+ was located on the host chromosome between galE (18 min) and trpB (34 min). Transduction experiments using P22 phage showed that the lac was cotransduced with gal, but not with trpB. These results clearly indicate that the lac gene is located at a position near 18 min of the linkage map of Salmonella. 相似文献