• Journal of Sericultural and Entomological Science
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• v.35 no.1
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• pp.28-35
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• 1993

Treatment of juvenile hormone analogue(JHA) at the 5th instar larvae prolonged the duration of adult development one to one and half days as well as the elongation of feeding time with the increasing of larval body weight. Morphological observation and protein analysis in hemolymphs, integuements, alimentary canals, fat bodies and ovaries also revealed that the development of these tissues and organs for adultation are affected by the JHA treatment.

• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.161.1-161
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• 1996

No Abstract, See Full Text

• Proceedings of the Botanical Society of Korea Conference
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• 1987.07a
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• pp.191-211
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• 1987

Common usage of the concept of juvenility implies that there is one physiological phase, the juvenile phase, which manifests itself in the various morphological and physiological phenomena observed in juvenile higher plants. The juvenile phase is often defined as that time from seed germination until the plant attains the ability to flower regulating such behaviour. This definition precludes plants from flowering in the juvenile phase. It is of major interest, therefore, to identify the physiological controls(Bluehreife) regulating such behavior. The length of the juvenile period in higher plants ranges from one year to over 60 years in different species. The long juvenile period of seedling is the main cause of the long duration of the breeding process. I determined the length of the juvenile period in various plants and its control of phase changes in natural system in relation to factors such as plant size and age, shoot morphology, apex size, root system and phytohormonal and nutritional status is reviewed. From the own experimental and observational evidence available it appears that both hormonal and nutritional factors can be involved in control of juvenility but that a specific juvenile or flowering hormone is not involved. Grafting, ringing, scoring, root pruning and fertilization have been used to accelerate flowering, but in most cases these cultured treatments are only successful on plants that were passed the juvenile phase. It is suggested that there are intrinsic difference between the meristematic cells of the apieces of juvenile and adult shoot, which are thus determined with respect to there development potentialities. The problems associated with the maintenance of the determined state through mitosis are discussed. The properties of transitional forms of Ribes nigrum L. intermediate between the juvenile and adult phase, are descrived and there implications discussed. Analogies are drawn between juvenile phenomena in woody perennials and in herbaceous species.

• Journal of Sericultural and Entomological Science
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• v.39 no.2
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• pp.161-168
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• 1997

To clarify the effect of anti-juvenile hormone analogue (AJH) on the larval ecdysis by feeding at early stage of the 4th instar, the total amount of protein and activity of chitinolytic enzymes in the integument of Bombyx mori were analyzed, PAGE pattern of the protein was observed and the morphological changes of integument during molting period were also observed and the morphological changes of integument during molting period were also observed by means of TEM. The total amount of protein was greatly increased in premolting, then reached maximum level just before ecdysis, and rapidly decreased after the larval ecdysis in the control, while in the AJH treatment, increased 12 hr later than the control and its maximum was only 82.6% of the control. Two specific proteins, which were presumed as the protein originated from endocuticle, also appeared 12 hr later than the control and were maintained to 132 hr after AJH treatment from the aspects of the Native- and SDS-PAGE patterns, although those of the control disappeared instantly after ecdysis. Chitinase and $\beta$-N-acetylglucosaminidase activities were also suppressed and delayed by AJH treatment. Furthermore, it was observed that the apolysis took place 12 hr later than the control but new epicuticle was not formed at least until 132 hr after AJH treatment. From these results, it is suggested that the larval molting process of silkworm develops 12 hr later than the control but new epicuticle was not formed at least until 132 hr after AJH treatment. From these results, it is suggested that the larval molting process of silkworm develops 12 hr later than the control by AJH treatment but no further processing takes place just after apolysis.

• Korean journal of applied entomology
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• v.35 no.3
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• pp.238-242
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• 1996

The second instar milkweed bugs, Oncopeltus fasciatus were exposed to the residue of 6-methoxy-7-ethoxy-2, 2- dimethylchromene(or 7-ethoxy precocene 11, 7-EP-11) with one, two, or four different kinds of synergist(s) deposited as a residue on 9 cm diameter petri dishes. The anti juvenile hormone analog, 7-EP-I1 yielded a 50% effectiveness concentration at 1.18 wg/cmZ. The concentration of 7-EP-I1 and R020-9747 combined gave 0.084 ~*g/cm', as much 14 times more potent than with 7-EP-I1 alone. Most of the other synergists, including geraniol, 4-chalcone oxide, isosafrole, and piperonyl butoxide however, showed comparatively low level synergism with 1.0-4.3 times, depending upon the combinations of the synergist(s). The obtained results were considered that R020-9747, an analog of benzopyran with similar structure to that of 7-EP-I1 inhibited selectively the insect monooxygenase oxidative defense mechanism, in the body except for corpora allata because general antioxidants of piperonyl butoxide, isosafrole, and 4-phenyl chalcone oxide showed relatively mild synergism.

• Journal of Sericultural and Entomological Science
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• v.28 no.1
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• pp.37-42
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• 1986

The experiment was carried out to investigate the effects of juvenile hormone analogue on changes of protein and amino acids in haemolymph of silkworm larva. Juvenile hormone analogue was topically administered to larvae at dose of 1$\mu\textrm{g}$ 10$\mu\textrm{g}$ per gm of body weight at 60hr. of the 5th instar. The results obtained were as follows ; 1. Larval duration of the fifth instar was extended about 1 day by JHA-1 and 4 days by JHA-10 as compared with the control. 2. Cocoon weight and cocoon layer weight by topical application of JHA were heavier than those of the control, but cocoon layer ratio was decreased in JHA-10 to the exclusion of JHA-1. 3. The concentration of haemolymph protein during the fifth instar was increased remarkably by the JHA application. 4. The total content of amino acids in haemolymph proteins of JHA-10 approximately doubled that of the control, with the conspicuous increase of glycine and arginine level.

• Biomolecules & Therapeutics
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• v.26 no.5
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• pp.512-519
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• 2018

Phthalates widely used in the manufacture of plastics have deeply penetrated into our everyday lives. Recently, a concern over the toxicity of phthalates on thyroid, has been raised but in most of cases, the doses employed were unrealistically high. To investigate the effects of phthalates on thyroid, we investigated the effects of the repeated oral exposure to low to high doses (0.3, 3, 30 and 150 mg/kg) di-2-ethylhexylphthalate (DEHP) from weaning to maturity for 90 days in juvenile rats on the thyroid. The histological examination revealed that DEHP significantly induced hyperplasia in the thyroid from the doses of 30 mg/kg, which was confirmed with Ki67 staining. In line with this finding, increased mRNA expression of thyrotropin releasing hormone (Trh) was observed in the thyroid of female at 0.3 mg/kg and 150 mg/kg as determined by RNAseq analysis. Moreover, significantly increased expression of parathyroid hormone (Pth) in the female at 0.3 mg/kg, and thyroglobulin (Tg) and thyroid hormone responsive (Thrsp) in the male at 0.3 mg/kg were noted in the blood, of which changes were substantially attenuated at 150 m/kg, alluding the meaningful effects of low dose DEHP on the thyroid hormone regulation. Urinary excretion of mono-2-ethylhexyl-phthalate (MEHP), a major metabolite of DEHP was determined to be 4.10 and 12.26 ppb in male, 6.65 and 324 ppb in female at 0.3 and 30 mg/kg DEHP, respectively, which fell within reported human urine levels. Collectively, these results suggest a potential adverse effects of low dose phthalates on the thyroid.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2000.10a
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• pp.37-37
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• 2000

• Korean journal of applied entomology
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• v.34 no.1
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• pp.20-32
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• 1995

Adult diapause in insects is characterized by suppression of reproductive development. It is induced by environmental cues such as photoperiod, temperature, food availability, and other conditions Diapause-inducing environment is recognized and analyzed by the brain of the insects. The interpreted information is conveyed via endocrine system to target tissues such as ovaries, fat body, and other tissues. From this signal hierarchy of a brain-endocrine-target tissue axis, several factors are involved to express a diapause trait in a quantitative mode, even though the insects show a binomial phenotye between being in diapause or not. Recent works estimated that the number of the factors is relatively small by a series of crossing trials between high and low diapause lines. Heritability of the diapause is quite high (ca. 70%) in some species. Epistasis, sex-linkage, pleiotropism, and other nongenetic components also affect diapause inheritance. Most physiological studies have been focused on control mechanisms of the juvenile hormone (JH) synthesis in corpora allata (CA) because JH level in hemolymph of teneral adults is critical to decide a later developmental mode. Allatostatin, an antagonizer of JH synthesis, has been believed to be a potent brain message to CA for adult diapause induction.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.109-115
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• 2022

Vitellogenesis is the process by which yolk accumulates in developing oocytes. The initiation of vitellogenesis represents an important control point in oogenesis. When females of the model insect Drosophila melanogaster molt to become adults, their ovaries lack mature vitellogenic oocytes, only producing them after reproductive maturation. After maturation, vitellogenesis stops until a mating signal re-activates it. Juvenile hormone (JH) from the endocrine organ known as the corpora allata (CA) is the major insect gonadotropin that stimulates vitellogenesis, and the seminal protein sex peptide (SP) has long been implicated as a mating signal that stimulates JH biosynthesis. In this review, we discuss our new findings that explain how the nervous system gates JH biosynthesis and vitellogenesis associated with reproductive maturation and the SP-induced post-mating response. Mated females exhibit diurnal rhythmicity in oogenesis. A subset of brain circadian pacemaker neurons produce Allatostatin C (AstC) to generate a circadian oogenesis rhythm by indirectly regulating JH and vitellogenesis through the brain insulin-producing cells. We also discuss genetic evidence that supports this model and future research directions.