Proceedings of the Japan Academy, Series B

Reviews

MAP kinase cascades regulating axon regeneration in C. elegans

Strahil Iv. PASTUHOV, Naoki HISAMOTO, Kunihiro MATSUMOTO

2015 Volume 91 Issue 3 Pages 63-75
Published: March 11, 2015
Released on J-STAGE: March 11, 2015

DOIhttps://doi.org/10.2183/pjab.91.63

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Mitogen-activated protein kinase (MAPK) signaling cascades are activated by diverse stimuli such as growth factors, cytokines, neurotransmitters and various types of cellular stress. Our evolving understanding of these signal cascades has been facilitated by genetic analyses and physiological characterization in model organisms such as the nematode Caenorhabditis elegans. Genetic and biochemical studies in C. elegans have shed light on the physiological roles of MAPK cascades in the control of cell fate decision, neuronal function and immunity. Recently it was demonstrated that MAPK signaling is also important for axon regeneration in C. elegans, and the use of C. elegans as a model system has significantly advanced our understanding of the largely conserved molecular mechanisms underlying axon regeneration. This review summarizes our current understanding of the role and regulation of MAPK signaling in C. elegans axon regeneration.

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Intraovarian control of selective follicular growth and induction of oocyte maturation in mammals

Eimei SATO

2015 Volume 91 Issue 3 Pages 76-91
Published: March 11, 2015
Released on J-STAGE: March 11, 2015

DOIhttps://doi.org/10.2183/pjab.91.76

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In newborn mammals, most of the germ cell population rests in a pool of quiescent small follicles in the ovaries. Regularly throughout adulthood, a small percentage of these oocytes and follicles grows to a certain stage of development and then either degenerates or matures and ovulates. This entire process is under both exogenous and endogenous control. Recent work, including my laboratory’s, has clarified that cytokines and glycosaminoglycans are involved as exogenous and endogenous factors in ovarian follicular development, atresia, and maturation in mammals. The present article describes our contribution regarding the cytokines and ovarian glycosaminoglycans that act as intraovarian regulators of follicular development and oogenesis, including oocyte maturation, in mammals.

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Original Article

Whole-body counter surveys of Miharu-town school children for four consecutive years after the Fukushima NPP accident

Ryugo S. HAYANO, Masaharu TSUBOKURA, Makoto MIYAZAKI, Hideo SATOU, Kat ...

2015 Volume 91 Issue 3 Pages 92-98
Published: March 11, 2015
Released on J-STAGE: March 11, 2015

DOIhttps://doi.org/10.2183/pjab.91.92

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Comprehensive whole-body counter surveys of Miharu-town school children have been conducted for four consecutive years, in 2011–2014. This represents the only long-term sampling-bias-free study of its type conducted after the Fukushima Dai-ichi accident. For the first time in 2014, a new device called the Babyscan, which has a low ^134/137Cs MDA of <50 Bq/body, was used to screen the children shorter than 130 cm. No child in this group was found to have detectable level of radiocesium. Using the MDAs, upper limits of daily intake of radiocesium were estimated for each child. For those screened with the Babyscan, the upper intake limits were found to be ≲1 Bq/day for ¹³⁷Cs. Analysis of a questionnaire filled out by the children’s parents regarding their food and water consumption shows that the majority of Miharu children regularly consume local and/or home-grown rice and vegetables. This however does not increase the body burden.

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Ca²⁺ and cAMP regulations of microtubule sliding in hyperactivated motility of bull spermatozoa

Sumio ISHIJIMA

2015 Volume 91 Issue 3 Pages 99-108
Published: March 11, 2015
Released on J-STAGE: March 11, 2015

DOIhttps://doi.org/10.2183/pjab.91.99

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To reach and fertilize the egg, mammalian spermatozoa change their flagellar movement in the female reproductive tract, named hyperactivation. The biochemical analyses of the hyperactivated movement using demembranated spermatozoa defined the factors inducing this peculiar movement; namely, large asymmetrical flagellar movement observed in the early stage of the hyperactivation was induced with a high Ca²⁺ concentration while large symmetrical flagellar movement in the late stage of the hyperactivation was generated with low Ca²⁺ and high cAMP concentrations. Under these conditions, the microtubule sliding of bull sperm flagella was investigated by disintegrating the sperm flagella with MgATP²⁻ after extracting their plasma membrane and mitochondria. The large asymmetrical flagellar movement was caused by a long sliding displacement of a fiber of the doublet microtubules. On the other hand, the large symmetrical flagellar movement was generated by a large amount of microtubule sliding by many doublet microtubules.

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