• Korean Journal of Ichthyology
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• v.35 no.3
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• pp.207-210
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• 2023

While an investigation on the old samples kept at collection room in National Institute of Fisheries Science (NIFS), we found a unique single specimen of burbot, Lota lota (54.7 cm in standard length) from Amnokgang River, North Korea on 14 April 1935. Burbot is the only stream dweller among members of the Gadiformes and found in the northern parts of Eurasia and North America. There was a little information in Korea, because it inhabits only the northern part of North Korea. This species is easily distinguished by having two dorsal fins, one anal fin, a barbel, and posterior of caudal fin rounded. This study provides detailed morphological characteristics and compares it with those of previous literatures on the North Korean L. lota.

• Fisheries and Aquatic Sciences
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• v.22 no.8
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• pp.18.1-18.5
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• 2019

The development of sex-specific genetic assays in a species provides both a method for identifying the system of sex determination and a valuable tool to address questions of conservation and management importance. In this study, we focused on the identification of single nucleotide polymorphisms (SNPs) that differentiate genetic sex in burbot Lota lota. Burbot are the only true freshwater representative of the cod family and a species of conservation and management importance throughout Eurasia and North America. To identify sex-specific SNPs, we utilized restriction site-associated DNA sequencing (RADseq) to interrogate thousands of SNPs in burbot samples of known phenotypic sex. We discovered 170,569 biallelic SNPs, none of which fit the pattern expected under female heterogamety. However, we identified 22 SNPs that fit the pattern expected under male heterogamety (males heterozygous XY, females fixed XX) and, from these, developed two genetic assays that robustly (~ 97% genotyping success) and accurately (> 99% correct) sexed burbot samples. These sex-specific genetic assays will benefit growing conservation aquaculture programs for this species and allow future assessments of sex-specific migration, growth, and mortality.

• Journal of IKEEE
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• v.12 no.3
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• pp.167-171
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• 2008

A bridge resistance deviation-to-frequency (BRD-to-F) converter is presented for interfacing resistive sensor bridges. It consists of a linear operational transconductance amplifier (LOTA), a current-controlled oscillator (CCO). The prototype converter was simulated using commercially available discrete components. The result shows that the converter has a conversion sensitivity amounting to 16.90 kHz/${\Omega}$ and a linearity error less than ${\pm}$0.03 %.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.6
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• pp.405-412
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• 1991

Whitefish(Coregonus clupeaformis) and Burbot(Lota iota) muscle was filleted, treated with dipotassium phosphate(pH 8.0) by means of high pressure injection method, and finally stored at $-l2^{\circ}C$ for 3 months. Factors, the pH, moisture content, and total amount of collagen were analyzed on the samples before and after the frozen storage. The pH of the sample showed substantially higher values in the phosphate treated muscles than the controls and decreased after 3 months storage in all of the whitefish and burbot samples, there was no significant differences in the moisture content between the control and treated but some reduction occurred during frozen storage. The amount of total collagen in the tail sections of burbot was significantly high comparing with head sections and hardness of the tail section also showed high values which indicated that total collagen might be related to the texture of fish muscle. However, in the case of whitefish the effect was not apparent. The effects of these factors on the hardness determined by Instron texturometer were analyzed through standardized multiple regression. A specific factor was not apparent to the texture of white fish while pH showed the highest correlation to the hardness of the burbot muscle.

• The Korean Journal of Zoology
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• v.39 no.3
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• pp.273-281
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• 1996

Previously, we have proposed a two-cell type model for follicular steroidogenesis inamphibians with Rana nigromacu lota. Present experiments were carried out to ascertain whether the model Is applicable to R. dybowskii. The role of theca layer were also reassessed by using granulosa cell-free pure theca layer (P-THEP). Theca/epithelium (THEP) layers, P-THEP layers, and granulosa cell enclosed-oocytes () were obtained from ovarian follicles of R. dybowskii by microdissection. Intact follicles (IFs) and different types of tissues were cultured for 6 hour in amphibian Ringer's m the presence or absence of FPII (0.05 gland/mi) or various steroid precursor (100 ng/ml). The amounts of product steroids converted by the components were measured by RIA. Exogenously added pregnenolone (P5) resulted in a marked increase in progesterone (P$_4$) by GCEOs (2143 pg/follicle) and IFs (2346 pg/follicle) but a smaller increase in P4 by THEP layer (495 pg/follicle). Addition of P$_4$ increased 17 a-hydroxyprogesterone (17 $\alpha$-OHP$_4$) levels by GCEOs (1118 pg/follicle) and IFs (1333 pg/follicle) but less by THEP layer (290 pg/follicle). However, much less amounts of P$_4$ or 17 $\alpha$-OHP$_4$ were producad by P-THEP layers than THEP in the presence of P5. Exogenous 1 7$\alpha$-OIIP$_4$ increased androstenedione (AD) levels by GCEOs (1415 pg/follicle) and IFs (561 pg/follicle) but not by THEP layers. In contrast, addition of AD resulted m a marked increase in testosterone (T) levels by TIIEP (2594 pg/follicle) and IFs (2223 pg/follide) but much less by GCEOs (339 pg/follicle). Exogenous T increased estradiol (E$_2$) levels by GCEOs (551pg/follicle) and IFs (887 pg/follicle), but not by THEP layer (<10 pg/follicle). Without addition of FPH or steroid precursors, very low or nondetectable levels of steroids were produced (< 20 pg/follicle) by all the types of follicular components examined. The data presented here indicate that the two-cell type model based on the study with R. nigromacu Iota is applicable to R. dybowskii and also suggest that the minor pathway, which convert P5 to 17$\alpha$-OHP$_4$, is not present in theca layer.