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Deep Brain Photoreceptors and Photoperiodism in Vertebrates
Oishi, Tadashi,Haida, Yuka,Okano, Keiko,Yoshikawa, Tomoko,Kawano, Emi,Nagai, Kiyoko,Fukada, Yoshitaka,Tsutsui, Kazuyoshi,Tamotsu, Satoshi Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
Photoperiodism is an important adaptive phenomenon in various physiological parameters including reproduction to cope with seasonal changes. Involvement of extraretinal photoreceptors in the photoperiodism in non-mammalian vertebrates has been well established. In addition, circadian clock system is known to be involved in the photoperiodic time measurement. The pathway consists of light-input system, time measurement system (circadian clock), gonadotropin releasing hormone (GnRH) production in the hypothalamus, luteinizing hormone (LH) and follicle stimulating hormone (FSH) production in the pituitary, and final gonadal development. Recently, several laboratories reported photopigments newly cloned in the pineal, eyes and deep brain in addition to already known visual pigments in the retina. These are pinopsin, parapinopsin, VA-opsin, melanopsin, etc. All these photopigments belong to the opsin family having retinal as the chromophore. However, the function of these photopigments remains unknown. I reviewed the studies on the location of the photopigments by immunocytochemistry. I also discussed the results on the action spectra for induction of gonadal development in relation with the location of the photoreceptors. Various physiologically active substances distribute in the vertebrate brain. Such substances are GnRH, GnIH, neuropeptide Y, vasoactive intestinal peptide, c-Fos, galanin, neurosteroids, etc. I summarized the immunhistochemical studies on the distribution and the photoperiodic changes of these substances and discussed the route from the deep brain photoreceptor to GnRH cells.
Isobe, Yu,Oishi, Tadashi,Katano, Izumi The Korean Society of Limnology 2005 생태와 환경 Vol.38 No.S
We investigated the diel periodicity in the drift in relation to body size by field survey using the fourth instar grazing larvae of Micrasema quadriloba Martynov (Trichoptera, Brachycentridae) as a material. Although the larvae showed nocturnal drift periodicity, drift density in the nighttime was only twice that in the daytime. In both time periods, smaller individuals drifted significantly more, and the drift individuals in the daytime was the smallest in size (P< 0.05 in Sheffe's F). We discussed whether the drift of the fourth instar larvae drift behaviorally or accidentally considering larval size and food depletion.
Immunocytochemistry of serotonin and galanin in the hypothalamus of the Japanese quail
Haida, Yuka,Oishi, Tadashi,Tsutsui, Kazuyoshi,Tamotsu, Satoshi Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
We investigated the interaction of serotonin and galanin (GA) by a double immunostaining method in the Japanese quail. Serotonin-immunoreactive (IR) cells were located in the paraventricular organ (PVO) and infundibular nucleus (IF). The number of the cells under short-day photoperiod (SD) was less in the dark phase than in the light phase. GA-IR cells were found in the PVO, IF and median eminence. The number of GA-IR cells in SD was significantly greater than that in long-day photoperiod (LD). Numerous GA- IR varicose fibers ran along serotonin- IR cell bodies and nerve fibers in the PVO and IF of the same sections. Very few serotonin-IR fibers ran along GA-IR cell bodies and GA-IR nerve fibers in the ventral part of the IF. The present results suggest that the possibility of functional interaction takes place between serotonin- and GA- IR neurons in the PVO and IF.
Okano, Keiko,Okano, Toshiyuki,Oishi, Tadashi,Fukada, Yoshitaka Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
In birds, the photoperiodic seasonal breeding involves encephalic photoreception at the initial step of triggering the well-known endocrinal cascade. Especially in Japanese quail (Coturnix coturnixjaponica), the reproductive neuroendocrine function responds to a single long day, and hypothalamic regions are known to be important for the reproductive response. However, little is known about where and how the light and time signals are integrated to detect daylength information and transduced to the endocrinal responses. To gain insights into this issue, we are interested in the c-Fos expression in the hypothalamus of the Japanese quail. Meddle and Follett (1997) previously identified two hypothalamic regions where c-Fos-like immunoreactivities were induced in response to a long day by using an antibody to carboxyl terminal region of human c-Fos (Lys$^{347}$ -Leu$^{367}$ ). In the present study, we used a different anti-c-Fos antibody recognizing a region from Lys$^{128}$ to Ala$^{152}$ of human c-Fos, and found in long-day- stimulated quails many c-Fos-like immunoreactive nuclei localizing within two regions, nucleus anterior medialis hypothalami and nucleus periventricularis hypothalami, which are distinct from those identified in the previous study. Then, we focused on the difference in the cross-reactivities of the antibodies used, and determined the whole coding sequence of quail c-Fos to compare the antigenic sequences of the two antibodies with the amino acid sequence of quail c-Fos. We found that the antibody we used would recognize quail c-Fos more specifically than that used in the previous study.
Tsurumi, Toshiko,Masuda, Atsuko,Oishi, Tadashi Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
Djungarian hamsters show distinct seasonal rhythms in several physiological parameters. One of them is daily torpor that occurs in winter with decreased body temperature (about 1O-20$^{\circ}$C) during daytime. Daily torpor is induced by short-day photoperiod, food restriction and castration. But the mechanism to induce daily torpor has not been clarified. In the present study, we tried to clarify the process of daily torpor induction in detail. Adult male hamsters were kept in long photoperiod and high temperature (LP-HT) before the experiment and, thereafter, the animals were transferred to short photoperiod and low temperature (SP-LT), and they were kept in this condition for about six months. The daily rhythms of locomotor activity and body temperature were recorded every three-minutes by using the Minimitter telemetry system. Locomotor activity and body temperature showed very closely synchronized rhythms. All animals under LP-HT showed daily rhythms with higher locomotor activity and body temperature in nighttime than in daytime. Under SP-LT, there were two types of animals with and without showing daily torpor. Thus, they have individual differences in the response to SP -LT.
Actionspectra for Circadian Melatonin Rhythms in the Avian Pineal In Vitro
Kondo, Chieko,Haldar, Chandana,Tamotsu, Satoshi,Oishi, Tadashi Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
The avian pineal as well as the retina has been known to contain several types of photoreceptors with different visual pigments such as rhodopsin, iodopsin and the pineal specific opsin, pinopsin. These organs are also known to have circadian clock to regulate melatonin production. Exposure of animals to light causes a decline of the melatonin level and the phase shifts of melatonin rhythms in the pineal and retina. Therefore, the circadian clock system of these organs seem to consist of three elements, i.e., light input, oscillator and melatonin output systems. In birds, it was suggested that rhodopsin might be involved in the entrainment of pineal melatonin rhythms from the action spectrum experiment for controlling NAT activity rhythms. However, there are much more pinopsin-immunoreactive (Pino-IR) cells than rhodopsin (Rho-IR) and iodopsin (Iodo-IR) cells in the avian pineal. We found that Pino-IR cells appeared earlier embryonic stages than Rho-IR and Iodo-IR cells. So, we tried to identify the visual pigments involved in the circadian melatonin rhythms in the pineal and retina. Organ cultured pineals were exposed to monochromatic light to find out which opsin participates in regulation of melatonin rhythms. The action spectra showed a peak at 475nm, suggesting that pinopsin is the major photopigment to regulate melatonin production in birds.
Tamotsu, Satoshi,Kinugawa, Yoshimi,Kawano, Emi,Watanabe, Mai,Samejima, Michikazu,Oishi, Tadashi Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
Pineal organs of poikilotherm vertebrates transform the environmental light information into a humoral message and a neuronal activity. The former is melatonin, and the latter is modulation of the impulse in ganglion cells. The ganglion cells are physiologically classified into luminosity (achromatic) type and chromatic one, as the neural activity is modulated in two ways. We attempted to classify the pineal ganglion cells with morphological characteristics by means of the three- dimensional reconstruction method. In the pineal ganglion cells of river lamprey, there are two different features, oval and spherical. For comparison of their projection region in the brain, the tracing investigation was also carried out. The application of the neural tracer near mesencephalic tegmentum showed that only oval-shaped ganglion cells were labeled in the pineal organ. These results suggest that the oval-shaped ganglion cell is functionally different from the spherical one.