• The Korean Journal of Zoology
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• v.33 no.2
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• pp.183-190
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• 1990

The present study exarnines the physiological alteradons in prolactin (PRL) messenger ribonucleic acid (mRNA) and serum PRL levels during the rat estrous cycle and the effed of naloxone, an endogenous oploid peptide receptor antagonist, on PRL gene expression during the rat estrous cycle. Adult female rats exhibiting at least two consecutive 4-day estrous cycles were used in this study. A single injection of naloxone (2mg/kg b.w.) or saline was given sc 30 mm prior to decapitation. Animals were sacrificed at 10:00 h of each stage of the estrous cycle, and at 2-h intervals from 10:00 h to 20:00 h during the proestrus. PRL mRNA and serum PRL levels were determined by a RNA-blot hybridization with the rat PRL cDNA probe and by a PRL radjoimmunoassay, respectively. PRL mRNA and serum PRL levels were not dramatically altered in the morning of each stage of diestrus I, II and proestrus, and naloxone failed to modify the two parameters. During estrus naloxone clearly suppressed serum PRL levels, but it was unable to modify PRL mRNA levels. A more detailed examination of the proestrus stage revealed that PRL mRNA and serum PRL levels were fluctuated as a function of time: PRL mRNA levels reached a maximum level at 12:00 h and gradually decreased until 18:00 h. PRL mRNA levels then rose at 20:00 h. No difference of PRL mRNA levels between the control and naloxone-treated groups was observed. Changes in serum PRL levek during proestrus were conversely related to changes in PRL mRNA: serum PRL levels were low from 10:00 h to 14:00 h, then increased and reached a maximum level at 16:00-18:00 h. Following then, serum PRL levels were decreased. Naloxone was effective in suppressing the charaderistic afternoon surge of PRL from 16:00 h to 20:00 h. These data clearly showed that alterations in PRL mRNA levels were conversely correlated with changes mn serum PRL levels on proestrus, indicating a differential regulation of PRL gene expression and secretion.

• The Korean Journal of Zoology
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• v.27 no.2
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• pp.85-92
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• 1984

The effect of copper ion on the lactate dehydrogenase isozyme patterns in the heart, liver, kidney, skeletal muscle, and ovary of catfish, Parasilurus asotus, was studied by cellulose acetate gel electrophoresis. 1. The LDH-1 and LDH-2 of heart type appeared in the heart muscle of control fish. When the fish were exposed to copper ion, however, the LDH-1, LDH-2, LDH-3, and LDH-4 appeared. The amount of LDH-1 was decreased and those of LDH-2, LDH-3, and LDH-4 were increased. 2. There was one band of LDH-4 in the liver of normal fish. But the amount of LDH-4 was decreased and additional new LDH-5 appeared by exposure to copper ion. 3. There were LDH-1, LDH-2, and LDH-4 in the kidney tissue of both control and experimental groups. The LDH-1 was increased, whereas LDH-2 and LDH-4 were decreased after exposure to copper ion. 4. There was broad band of LDH-5 in the skeletal muscle of the control fish. However, the LDH-4 and LDH-5 with M sub-band appeared by the exposure to copper ion. 5. There was LDH-3 band only in the ovary of control, wheras all five LDH isozymes appeared in the ovary of the fish exposed to copper iion. 6. During the period of exposure to copper ion, the LDH isozyme of heart type which associated with aerobic metabolism was decreased, but the LDH isozyme of muscle type of anaerobic metabolism was increased in most of heart, liver, and skeletal muscle. It seems that these organs are related to some of important functions for anaerobic metabolism during the copper poisoning period.

• The Korean Journal of Zoology
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• v.32 no.2
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• pp.120-133
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• 1989

The paraidehyde-fuchsin(PAE)-positive neurosecretory cells in the brains of wax moth Galleria mellonella have been morphologically examined at the six different metamorphic stages. During the metamorphosis, neurosecretory cells in the brain can be found in the five unclei of pars intercerebralis, lateral region of protocerebrum, optic lobe, deutocrebrum and tritocerebrum. The five nuelel include one to seven neurosecretory cells. On the bases of cell sizes and histochemical specificities of neurosercretion within cells, all the PAF-positive neurosercretory cells included in the six different metamorphic brains can be recognized as four species of neurosecretory cells as follows; (1) large (about 25 $\mu$m), neurosecretion-parcked cell (type I neurosecretory cell), (2) large, granule-dispersed cell (type II neurosecretury cell), (3) small (about 15 $\mu$m), neurosecretion-packed cell (type III neurosecretory cell), and (4) small, granule-dispersed cell (type IV neurose-cretory cell). The three tb seven medial neurosecretory cells are included in the pars intercerebralis of the six different metamorphic brains. With the increase of days from the late larva to the adult the type I cells of medial neurosecretory cells gradually decrease in number, but the respective three type II neurosecretory cells appear in the five different metamorphic brains except in pupa 2 day before the emeregnce of the adult which has only one type II. The one to five lateral neurosecretory cells are observed in the lateral region of protocerebrum from thepupa just after pupation to the adult. The type IV neurosecretory cells are the most in number of lateral neurosecretory cells. The one type Ineurosecretory cells are included near the optic lobe of only the 4-day-old pupa. the one deutocerebral neurosecretory cell, type II, appears only in the adult. The tritocerebrum includes both three neurosecretory cells in the late larva and one neuresecretory cell in the adult. In the late larva the two tritocerebral neurosecretory cells are type Ill neurosecretory cell and the one is type IV. The remaining one tritocerebral neurosecretory cell is type IV.

• The Korean Journal of Zoology
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• v.18 no.2
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• pp.87-101
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• 1975

Electron microscopic studies on the ultrastructure of the mouse oocyte were made to investigate the inhibition of germinal vesicle breakdown by dibutyryl cAMP. The nuclear membrane of the dibutyryl cAMP-treated oocyte is characterized by a decreased degree of folding, maintains the normal double membrane structure, and shows an increased occurrence of the nuclear pore. It is suggested that these may be related to the suppression of the maturation of oocytes at the germinal vesicle. Mitochondria in the control cell were shown to be spread evenly throughout the cytoplasm and structurally underdeveloped or transitionary having little cristae development. On the contrary, mitochondria in the treated oocyte were found to be localized mainly around the nucleus and to show a greater extent of cristae development. The oocyte treated with dibutyryl cAMP appears to have fewer and structurally simpler lysosomes as compared to the control. The Golgi complex in the control oocyte exhibits the typical granular and lamellar structure, whereas that in the treated cell is poorly developed. Many multivesicular bodies, tonofilaments, and free ribosomes were observed in the control as well as in treated cells. The microvilli become structurally irregular, and a development of the perivitelline space is apparent in the treated oocyte. It is concluded that there is no basic difference in the ultrastructure between the oocytes treated with dibutyryl cAMP for 24 hours in the medium and those collected directly from the follicle. However, the finding that dibutyryl cAMP induces a development of more pores along the nuclear membrane strongly suggests the possibility that this compound inhibits the maturation of oocytes by influencing the permeability of the nuclear membrane.

• The Korean Journal of Zoology
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• v.23 no.2
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• pp.69-76
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• 1980

Mice were dosed with $HgCl_2$ (5, 10 and 20 mg per kilogram body weight) and $CdCl_2$ (10, 15 and 20 mg per kilogram body weight) by the abdominal injection. Acid phosphatase activites of the liver at 24, 48 and 72 hours following the injection were measured by the Mundry colorimetric method using disodium p-nitrophenyl phosphate as the substrate, and the following results were obtained. The enzyme activities measured were 3.47 mg Pi/ml/0.5 hr at 24 hr and 5.00mg/ml/0.5 hr at 72hr respectively following the injection of 5 mg/kg body weight of $HgCl_2$ and 6.79 mg Pi/ml0.5 hr at 24 hr and 3.47 mg Pi/ml/0.5 hr respectively following the injection of 20 mg/kg body weight of the mercury compound, as compared with the activity of 8.3 mg Pi/ml/0.5 hr for the control. With the cadmium treatment, about 50% of the animals injected with 10mg/kg body weight, and none of the animals injected with 15 and 20mg/kg body weight, survived. Of the surviving animals, the sublethal concentration of cadmium was shown to activate the enzyme: the activities at 24, 48 and 72hr following the injection were around 11.2 mg Pi/ml/0.5 hr as compared with 8.63 mg Pi/ml/0.5 hr for the control.

• The Korean Journal of Zoology
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• v.24 no.3
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• pp.133-144
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• 1981

The ultrastructures of the pigment cells in the Asiatic land salamander (Hynobius leechi) dorsal skin were obtained by means of electron microscope. The results were as follows; 1. The pigment cells of the epidermis consisted of the melanocytes in the germinal layer and of the melanophores distributing to the keratinocyte layer. The traits of these cells in the epidermis were as follows: A. The nuclei of the melanocytes were round or oval in shape and appeared as partly small or large infoldings of the nuclear envelope. B. Rough-surfaced endoplasmic reticulums and Golgi complexes were well developed in infranuclear cytoplasm. Many ribosomes were mainly distributed around the perinuclear portion. C. The melanosomes of the melanocytes were observed as a found or an oval shape and strong electron-dense or less electron-dense melanosomes were observed. D. The infoldings of the nuclear envelope in the melanophore were partly found deeper than those of the melanocyte. The cytoplasm of the melanophore filled with melanosomes caused organelles not to be observed in that. 2. The pigment cells in the dermis were composed of the xanthophores just beneath basement membrane and the melanophores in the connective tissue. The traits of these cells in the dermis were as follows: A. The xanthophores contained round or oval vesicles, and these vesicles were divided into 6 types (type I pterinosome, type II pterinosome, type III pterinosomes, type iv pterinosome, type V pterinosome, type VI pterinosome). B. Most of the nuclei of the melanophores in the dermis were elongate in shape, and a portion of the nuclear envelope was deep infolded. C. Becuase the cytoplasm was filled with the melanosomes of the same electron-density, organelles were not observed in the cytoplasm. D. Two processes of the melanophore in the dermis extended in parallel with a xanthophore and the cytoplasm in those processes were filled with the melanosomes.

• The Korean Journal of Zoology
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• v.9 no.1
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• pp.1-6
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• 1966

Frequently , large masses of the young short necked clam, Tapes japonica , die at their tidal flats in summer and this phenomenon has not been explained clearly. The purpose of the present investigation is to study the thermal condition and the chlorinity level of tidal flats in which the young clam appears to be injured. A study is also mad efor the burrowing organism in the lower layer of the esturay over which the fresh water flow during the low tide. Observation are made at five places of the tidal flat near Ikawazu Fixheries Laboratory of Tokyo University during the ebb and flow tide period of the spring tide. The diurnal and monthly changes of tidal temperatures and chlorinities are measured. Results of the study are ; 1. The surface temperature of the tidal flat increases with the ebb tide, reaches the highest between 12-14PM, and gradually decreases thereafter. The temperatures of tidal flat below 5 and 10 cm increase gradually until the flow tide reaches the surface. 2. At the spring tide in summer , the diurnal change of surface of the tidal flat temperature is very extensive ; it reaches 37-39$^{\circ}C$ in August. At the depths of 5 and 10 cm the temperature remains at 33 $^{\circ}C$ and 31$^{\circ}C$ , respectively. 3. The chlorinity of the tidal flat is higher during May through June and lower July through August, and this seems to be related to the amount of rainfall. 4. The chlorinity of the surface of tidal flat increases slightly during the ebb and flow tide periods. The observed higher chlorinity of surface of the tidal flat was 18.82% Cl. 5. At near the esturay, the fresh water that overflows the tidal flat affects the chlorinity of the surface but no such influence to the depth of the flat. 6. From above observations, it is assumed that the young short necked clam in the tidal flat could be exposed to the severe change of environmental conditions. The high temperature of the tidal flat in summer and the low chlorinity of it at flood period may be considered as the change in environment.

• The Korean Journal of Zoology
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• v.9 no.1
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• pp.7-15
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• 1966

In a previous paper, the dirunal and monthly changes of the tidal flat temperature and chlorinity were observed. In this paper the resistance of the young short necked clam in various growth stages to the temperature, to the chlorinity and to the exposure were studies. The young clam used were in early (E), medium (M) and late (L) young stages whose shell lengths were 2.0-3.5mm, 9.0-11.0mm. and 14.0-16.0mm., respectively. The results were : 1. At various sea water temperatures , the chlorinity resistance of the young clam was directly proportional to the shell length. 2. When both inadequate sea water temperature and abnormal chlorinity are simultaneously applied, the resistance of these young clams was more markedly reduced than the case of applying either one of these conditions. 3. In clams of M and L, no lethal effect were observed when daily immersion of four to eight hours for a week into the sea water of any concentration of chloriity at 26-34$^{\circ}C$, whereas in E, 37-90% of mortalities were obtained by immersion of eight hours daily into both the fresh water and the sea water of higher chloriniites (more than 23.5$\textperthousand$ Cl) at the same temperature above. 4. The lower critical thermal maximum for lethal to the young clam was 38$^{\circ}C$. With four hours immersion daily at the water temperature of 38$^{\circ}C$, the mortalities of E, M and L to the lower chlorinities (less than 6.7$\textperthousand$Cl) were 100, 70-100 and 27-37% respectively ; to the higher chlorinities (more than 23.5$\textperthousand$Cl) 10-70, 10-37 and 3 % respectively ; to the normal range of chlorinities (13.4-16.8$\textperthousand$Cl) 0-13, 3 and 0 % respectively. 5. No lethal effects were observed in E and M clams immersed continuously for seven days in sea water with chlornities of 7.2 -21.7$\textperthousand$Cl at 18-24$^{\circ}C$, while notable mortalities were observed in E which had been kept at lower (less than 4.8$\textperthousand$ Cl) and higher (more than 24.1$\textperthousand$ Cl) chlorinites. 6. Although the resistance of the young clam to the chlorinity may have to be related closely to the life history of the clam prior subject to the experiment, the adapted chlorinity range was 7.2-19.3$\textperthousand$ Cl and the optimum range was 13.4-16.8$\textperthousand$Cl. 7. Remarkable lethal effects were observed for the E and M clams to the exposure temperature of 38$^{\circ}C$ whereas the L and had no such fatal results.

• The Korean Journal of Zoology
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• v.24 no.3
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• pp.151-161
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• 1981

The field studies on the seasonal population prevalences of the vector mosquito larvae and other aquatic invertebrates were weekly carried out in the rice fields located in front of a village of Kwangtan-samri, Byeogje-myeon, Goyang-gun, Gyeonggido throughout mosquito breeding season (June-September) in 1980, and the results are as follows. The population of C. tritaeniorhynchus larvae increased soon after heavy rainfall, and decreased to some extent during the period of the insecticide application. The seasonal prevalence of A. sinensis was rather stable, not being affected by insecticide pressure at all. The population densities of other aquatic invertebrates in rice fields were seriously suppressed by the pesticide application, and their recovery was not as same as the previous level or not at all: (1) The populations of Odonata and Ephemeroptera nymphs were drastically decreased by the first application of insecticides and never recovered through out season. (2) Coleoptera seemed very susceptible to the insecticide application, as densities were markedly decreased whenever the insecticides were applied. (3) The high density of Hemiptera shown in early June were decreased sharply after the first application of pesticides, and thereasfter, some degree of recovery was shown, but suppressed by successive each application of pesticides. (4) A native species of planaria was exceptionally not influenced by the insecticide pressure, and two peaks of the density were appeared during the heavy rainfall.

• The Korean Journal of Zoology
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• v.32 no.2
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• pp.107-119
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• 1989

The histochemical characteristics of the cutaneous granular glands and its fine structure of the Korean fire bellied toad, Bombino orientalis Boulenger the only species inhabitated in Korea, were studied with light and electron microscopes. By the granular size and histochemical properties, the granular glands were subdivided into two types. The type I glands have small secretory granules (3.6 $\mu$ m), whereas the type II glands contain relatively larger granules (7.5 $\mu$ m). These two types of glands were simple alveolar gland, and they were commonly composed of inner glandular epithelial cells and outermost myoepithelial cells. By the histochemical reactions, these two secretory granules were not responsed to Alcian blue, but weakly positive reaction was observed in type I granular glands by the PAS reaction. And by the scanning electron microscopic observation, extemal morphology of the opening site of the gland duct was resembled to the stomata of the plant leaves. Especially the epithelial cells of the type I glands had fine reticular surface whereas, type II glands had large vesicular surface. These types of the glands conimonly had larger cavities than those of mucous glands, and forming the multinucleated unicellulr structure (syncytium) at the glandular epithelial layers. Secretory granules of these glands were originated from the rough endoplasmic reticulum of the glandular epithelial cells, and by the maturation level of the granule, morphological diversities appeared.