• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.4
• /
• pp.426-433
• /
• 2021

This study aimed to determine the appropriate salinity condition for optimal cultivation of the juvenile hybrid grouper Epinephleus akaara♀×E. lanceolatus♂ in conditions of decreasing salinity. The survival, growth, metabolic rate, stress, and histological response were investigated in juvenile hybrid grouper exposed to different salinities for 30 days. At 0 psu, the survival rate of the juvenile hybrid grouper was 60% on the 2nd day of exposure and all individuals died on the 3rd day of exposure. At salinities above 3 psu, all animals survived throughout the exposure period. Growth rate for body weight of the juvenile hybrid grouper was the highest in the control and the lowest at 10 psu. Plasma osmolality of the juvenile hybrid grouper exposed to different salinities was 313-355 mg Osmol/kg at salinities above 10 psu, and then decreased to 225-264 mg Osmol/kg at salinities below 5 psu. The oxygen consumption rate tended to decrease as the salinity decreased. Stress responses of the juvenile hybrid grouper were analyzed with decreasing salinity. Therefore, it is considered that a salinity of more than 20 psu is suitable for the culture of the juvenile hybrid grouper.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.42 no.6
• /
• pp.585-590
• /
• 2009

The purpose of this study was to examine the effects of oral-administered sex hormone for hybrid sturgeon, bester juvenile. The bester juveniles (2 months after hatching) were received a diet containing various doses of $17\alpha$-methyltestosterone (MT) or estradiol-$17\beta$ ($E_2$) for 6 months. Somatic growth of bester sturgeon juvenile did not show significant differences between experimental and control groups (27.9-30.5 cm; 125.1-161.7 g), although survival percentages showed a decreasing tendency in MT-treated animals. By histological examination, germ cells were recorded as smooth type in MT-treated fish and uneven type of germinal epithelium in $E_2$-treated animals. Their sex ratios were 5:4:1 (male: female: undifferentiation) in control and low dose of MT-treated fish (1 mg/kg), and 9:1:0 in fish treated with high dose of MT (10 mg/kg), whereas the ratios were reversed by both low and high doses of $E_2$ treatment, recorded as 2:8:0. Gonadal areas were not significantly differed in all trials (424,600.4 - 1,039,656.3 ${\mu}m^2$). Total number of germ cells, number of germ cells per gonadal areas and number of germ cells per area were significantly higher to 144.7-148.7 cells/section, 374.0-408.5 $cells/mm^2$ and 1,599.5-1,670.9 $cells/mm^2$ in $E_2$ treatment than those of others (30.4-63.9 cells/section, 148.4-226.9 $cells/mm^2$ and 850.0-1,050.6 $cells/mm^2$), respectively. And somatic growth according to their gender was not significantly differed between male and female.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.44 no.5
• /
• pp.560-564
• /
• 2011

Two feeding experiments were conducted to investigate the effects of dietary inclusion of genetically modified (GM) soybean and corn on the growth performance, feed utilization and body composition of juvenile abalone Haliotis discus hannai. Four isonitrogenous (31% crude protein) and isolipidic (6% crude lipid) diets (designated as nGM-soya, GM-soya, nGM-corn and GM-corn) were formulated to contain 20% non-GM (nGM) and GM soya and corn. Fifty juvenile abalone (initial body weight, 2.0 g) were distributed in each 50 L tank in a flow-through system. Each experimental diet was fed to duplicate groups of abalone to satiation once a day for 10 weeks. No effects of GM feedstuffs on survival were observed. Dietary inclusion of GM feedstuffs did not affect either growth performance or feed utilization of abalone. Body composition was not altered by the inclusion of GM feedstuffs. These results indicate that dietary inclusion of GM soybean and corn could have no effect on the growth performance and body composition of juvenile abalone. Further studies to investigate the effects of GM feedstuffs on transgenic fragment residues in ambient environments and in animals are necessary for the safe use of such ingredients in aquaculture.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 2001.05a
• /
• pp.144-145
• /
• 2001

Marine microalgae are used extensively in mariculture as food for marine animals, in particular larval and juvenile molluscs, crustaceans and fish. A wide range of microalgae has been tested, because not all species are equally successful in supporting growth of a particular animal. In addition, bioactivities of marine microalgae are recently investigated for the effective exploitation of unutilized marine resources. (omitted)

• Journal of Aquaculture
• /
• v.16 no.4
• /
• pp.223-228
• /
• 2003

An exfoliation, the detachment of juvenile abalones from a culture substrate, is essential for selection and population density control in abalone culture. Physical instruments and anesthetics are currently available for the exfoliation but the latter is regarded as more effective in reducing physical damage to the animals. In the present study, urea ($Co(NH_2)_2$), a chemical fertilizer, was selected as a anesthetic, and its optimal concentration and sea water temperature for exfoliation of Haliotis discus were determined in order to develop an exfoliation technique which is more economical and effective. A 97% cumulated exfoliation rate was observed within 3 min at all temperatures observed when the concentration rate of urea was 9∼15%. This range of urea concentration can be ideal for both exfoliation and recovery. Also it was found that the higher concentration of urea and temperature the higher exfoliation rate, however, these conditions reduced the recovery rates of the animals tested. These results could indicate that urea is a good tool for exfoliation of various species of young abalones, and urea could substitute for all techniques and anesthetics methods currently available for abalone exfoliation.

• Biomolecules & Therapeutics
• /
• v.27 no.2
• /
• pp.168-177
• /
• 2019

Dysregulation of excitatory neurotransmission has been implicated in the pathogenesis of neuropsychiatric disorders. Pharmacological inhibition of N-methyl-D-aspartate (NMDA) receptors is widely used to model neurobehavioral pathologies and underlying mechanisms. There is ample evidence that overstimulation of NMDA-dependent neurotransmission may induce neurobehavioral abnormalities, such as repetitive behaviors and hypersensitization to nociception and cognitive disruption, pharmacological modeling using NMDA has been limited due to the induction of neurotoxicity and blood brain barrier breakdown, especially in young animals. In this study, we examined the effects of intraperitoneal NMDA-administration on nociceptive and repetitive behaviors in ICR mice. Intraperitoneal injection of NMDA induced repetitive grooming and tail biting/licking behaviors in a dose- and age-dependent manner. Nociceptive and repetitive behaviors were more prominent in juvenile mice than adult mice. We did not observe extensive blood brain barrier breakdown or neuronal cell death after peritoneal injection of NMDA, indicating limited neurotoxic effects despite a significant increase in NMDA concentration in the cerebrospinal fluid. These findings suggest that the observed behavioral changes were not mediated by general NMDA toxicity. In the hot plate test, we found that the latency of paw licking and jumping decreased in the NMDA-exposed mice especially in the 75 mg/kg group, suggesting increased nociceptive sensitivity in NMDA-treated animals. Repetitive behaviors and increased pain sensitivity are often comorbid in psychiatric disorders (e.g., autism spectrum disorder). Therefore, the behavioral characteristics of intraperitoneal NMDA-administered mice described herein may be valuable for studying the mechanisms underlying relevant disorders and screening candidate therapeutic molecules.

• Biomolecules & Therapeutics
• /
• v.25 no.5
• /
• pp.545-552
• /
• 2017

Increasing concern is being given to the association between risk of cancer and exposure to low-dose bisphenol A (BPA), especially in young-aged population. In this study, we investigated the effects of repeated oral treatment of low to high dose BPA in juvenile Sprague-Dawley rats. Exposing juvenile rats to BPA (0, 0.5, 5, 50, and 250 mg/kg oral gavage) from post-natal day 9 for 90 days resulted in higher food intakes and increased body weights in biphasic dose-effect relationship. Male mammary glands were atrophied at high dose, which coincided with sexual pre-maturation of females. Notably, proliferative changes with altered cell foci and focal inflammation were observed around bile ducts in the liver of all BPA-dosed groups in males, which achieved statistical significance from 0.5 mg/kg (ANOVA, Dunnett's test, p<0.05). Toxicokinetic analysis revealed that systemic exposure to BPA was greater at early age (e.g., 210-fold in $C_{max}$, and 26-fold in AUC at 50 mg/kg in male on day 1 over day 90) and in females (e.g., 4-fold in $C_{max}$ and 1.6-fold in AUC at 50 mg/kg vs. male on day 1), which might have stemmed from either age- or gender-dependent differences in metabolic capacity. These results may serve as evidence for the association between risk of cancer and exposure to low-dose BPA, especially in young children, as well as for varying toxicity of xenobiotics in different age and gender groups.

• Journal of Aquaculture
• /
• v.11 no.4
• /
• pp.429-435
• /
• 1998

This study compared acute ammonia toxicity in juvenile rockfish and red sea bream. Oxygen concentration affected ammonia toxicity to aquatic animals. Without aeration, the 96-hr $LC_50$ values of $NH_4^+$and un-ionhized ammonia for juvenil rockfish(3.6g, 6.6cm) were 2.61 and 0.09 mg/l, respectively. The 3-hr $LC_50$ values of $NH_4^+$ for the size of 1.9g (5.2cm) and 3.6g (6.6cm) rockfish, and 1.0g (3.8cm) and 2.0g (5.0cm) red sea bream without aeration were 3.96, 3.94, 4.35 and 3.75 mg/l, respectively. When oxygen level was low, larger fish were more susceptible to ammonia toxicity than smaller one because of stress resulted from low oxygen. However, with aeration, the 96-hr $LC_50$ values of $NH_4^+$ for the size of 1.2g (3.9cm) and 2.3g (5.1cm) red sea bream with aeration were 3.84 and 3.90mg/l, respectively. The 6-hr $LC_50$values of $NH_4^+$ for the size of 3.1g (5.9cm) and 6.2g (7.0cm) rockfish with aeration were 3.83 and 3.94 mg/l, respectively. When oxygen level was high, larger rockfish and red sea bream were less susceptible to ammonia toxicity than smaller ones. The 6 hr-or 96 hr-$LC_50$ values of $NH_4^+$for rockfish with reduced ammonia toxicity. In comparing 96 hr-$LC_50$ values of $NH_4^+$ and un-ionized ammonia for juvenil rockfish with those for juvenil red sea bream, the values for rockfish were lower than for red sea bream. This indicates that juvenile rockfish is more susceptible to ammonia toxicity than juvenile red sea bream.

• Korean journal of applied entomology
• /
• v.31 no.3
• /
• pp.289-303
• /
• 1992

Investigation of the environmental impact of widespread pesticide use has revealed a virtue/vice relationship. Although many pesticides perform their function and disappear without harm to the environment, others persist beyond their useful purpose and cause direct of indirect hazard to man, domestic animals and wildlife. Concurrently, many pests have rapidly adjusted to chemical control practices through changes in behavior that avoid exposure to pesticides of throuth genetic selection for populations resistant to the toxicants. The prospect of losing control over insect herbivores and desease vectors and returning to the days of global hunger and disease is unthinkable. Fortunately, from basic studies of insect and plant biology many opportunities for the development of safe, selective and environmentally pacific strategies for insect pest management are being realized.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 2001.05a
• /
• pp.295-296
• /
• 2001

Dietary lipids are important sources of energy and of essential fatty acids (EFA). Providing desired amounts of EFA is necessary for the normal growth and survival of juvenille fish. EFA requirements of fish are affected by fish species, water temperature and salinity, and different from those of terrestrial animals (Castell 1979). EFA affect the fluidity and permeability of membranes, enzymes activity and are known as the precursors of the eicosanoids. (omitted)