NGFI-B is an immediate-early gene that encodes an orphan nuclear receptor. The present study was designed to examine the localization and gonadotropin regulation of NGFI-B expression in the rat ovary. Northern blot analysis of ovaries obtained from prepubertal rats revealed the increased expression of NGFI-B during prepubertal development. Treatment of immature rats with PMSG, however, decreased ovarian NGFI-B expression. The major cell types expressing NGFI-B messenger RNA were thecal cells of follicles in different sizes. In contrast, treatment of PMSG-primed rats with human (h) CG resulted in the rapid and transient stimulation of ovarian NGFI-B messenger RNA, reaching a peak within 1 h. In situ hybridization analysis revealed that hCG treatment induced the expression of NGFI-B in granulosa cells of preovulatory follicles. Treatment of cultured preovulatory follicles in vitro with LH further confirmed the time- and dose-dependent stimulation of NGFI-B messenger RNA and protein. LH-stimulated NGFI-B expression in preovulatory follicles was abolished by alpha-amanitin, but was superinduced by cycloheximide. Furthermore, treatment of adult cycling rats with pentobarbital abolished NGFI-B expression on proestrus, and exogenous administration of hCG restored it, indicating the role of the preovulatory surge of LH in the stimulation of NGFI-B expression. These results demonstrate the cell type-specific expression and gonadotropin induction of NGFI-B in granulosa cells of preovulatory follicles and suggest a role for NGFI-B in the ovulatory process.
An experiment was conducted to investigate the annual reproductive cycle of a
Korean endemic species, Acheilognathus majusculus, from
Jeokseong-myeon located in Seomjin River. The reproductive cycle is examined
histologically regarding water temperature and day length of the habitat, the
gonadosomatic index (GSI), the female ovipositor length index (OLI), monthly
variation in egg diameter distribution, and developmental characteristics of
female and male gonads. The maximum GSI was found in 19.21±2.32 and 6.90±0.53
for female and male respectively when water temperature (14℃) and day length
(11.1hr) began to rise. On the other hand, the minimum level was reached during
August (1.87±0.67 for female and 0.88±0.50 for male). No samples represent with
measurable ovipositor between September and November, while the longest
ovipositor length index was in April (79.68±4.69%). We compared and calculated
the stages of testis and ovary development process in order to determine the
germ cell development characteristics and the reproductive cycle. According to
the result, we classified the female Acheilognathus majusculus
reproductive cycle into four stages: Ripe (April) and spawning phase (May to
June), degenerative phase (July), growing phase (August to December), and mature
phase (January to March). The annual reproductive cycle of male
Acheilognathus majusculus was categorized into five stages viz.
Ripe and spawning phase (May to June), degenerative phase (July to August),
resting phase (September to November), growing phase (December to February), and
mature phase (March to April).
The annual reproductive cycle of the Korean endemic slender catfish,
Silurus microdorsalis, was examined histologically
regarding water temperature and day length of habitat, gonadosomatic index
(GSI), and development characteristics of female and male gonads. The maximum
GSI value was found in May, 1.23±0.33 and 11.77±3.23 for male and
female respectively (habitat water temperature 21.5°C/13.59hr day
length). On the other hand, the minimal level was 0.63±0.10 in July
(26.5°C/14.17) for male and 1.36±0.08 in October
(20°C/11.2hr) for female. We compared and calculated the stages of testis
and ovary development process in order to determine the germ cell development
characteristics and the reproductive cycle. According to results, we classified
the annual reproductive cycle of the slender catfish into five stages: Growing
phase (December-February), Mature phase (March-April), Ripe and spawning phase /
Releasing phase in male (May-June), Degenerative phase (July-August), and
Resting phase (September-November).
In this study, an experiment was conducted to investigate the annual reproductive cycle of a Korean flat bittering, Acheilognathus rhombeus, from Ogok-myeon located in Seomjin River. The reproductive cycle was examined histologically regarding water temperature and day length of the habitat, the gonadosomatic index (GSI), and developmental characteristics of female and male gonads. The maximum GSI was found to be 3.50±0.53 and 1.36±0.14 for females and males, respectively, when the water temperature and day light was 16.9℃ and 11.3 hours, respectively in October 2018. On the other hand, the minimum GSI was found to be 0.16±0.09 and 0.69±0.15 for males and females in December 2018 and February 2019, respectively. The ovipositor of females appeared from August to November 2018. We compared and calculated the stages of germ cell developmental characteristics in the testis and ovaries to determine the reproductive cycle. According to the result, we classified the female A. rhombeus reproductive cycle into four phases, which are ripe and spawning phase (October), degenerative phase (November to December), growing phase (January to March) and mature phase (April to September). The annual reproductive cycle of male A. rhombeus was categorized into four phases: mature phase (June to October), degenerative phase (November to March), resting phase (April) and growing phase (May). The Korean flat bittering is an autumn-spawner as the main spawning season in October. In male, testicular spermatogonia appeared all yearround, and the ripe and releasing phase, which is characteristics of the spawning season in other fish, did not appear.
Forest fire can cause a serious damage to overhead conductors. Therefore, detailed investigation on the changes of mechanical and electrical properties of damaged conductors should be carried out to understand the effect of forest fires on conductors. This is of critical importance in maintaining transmission line safely. This paper examines the changes of mechanical and electrical properties of flame exposed conductor. Tensile strength (TS) decreased according to increase of forest fire temperature and conductivity changed according to forest fire temperature. Specimens were aluminum conductors of aluminium conductor steel reinforced (ACSR) 410, 240, 480 ㎟. In this paper, the electrical and mechanical characteristics of forest fires exposed overhead conductors depending on the diameter of aluminum conductors are presented. It was possible to estimate the degree of deterioration caused by forest fires. The detailed results are given in the paper.
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