• The Korean Journal of Malacology
• /
• v.20 no.2
• /
• pp.111-120
• /
• 2004

We investigated the reproductive cycle of Corbicula japonica with its gonadal development by histological observations, and the seasonal changes in biochemical mass and foot muscle of the adductor muscle, visceral mass and foot muscle of the clam by biochemical analysis, from January to December, 2003. The reproductive cycle of this species can be classified into five successive stages: early active stage (February to April), late active stage (April to July), ripe stage (June to August), partially spawned stage (July to September) and spent/inactive stage (September to March). According to ANOVA test, there were significant differences (p < 0.05) in total protein, total lipid and glycogen contents among months for all of the visceral mass, adductor muscle and foot muscle. Total protein content was highest in adductor muscle, while lowest in visceral mass. There was no correlation in total protein content between visceral mass and adductor muscle (p = 0.208). However, strong positive correlation was found between adductor muscle and foot muscle (r = 0.769, p < 0.001). In visceral mass, total lipid content was the highest; it was 2 or 3-fold higher than in adductor muscle or foot muscle. The monthly change was also most dynamic in visceral mass. It decreased from January to March (early active stage), and reached maximum in April (late active stage). From May to August (ripe and partially spawned stage), it dradually decreased and then increased again until October (spent/inactive stage). Multiple comparisons showed that total lipid content in visceral mass between all of the adjacent two months was significaltly different (p < 0.05). There were strong negative correlations in total lipid content between visceral mass and adductor muscle (r = 0.687, p < 0.001), and between visceral mass and foot muscle (r = 0.473, p = 0.008). Changes of glycogen content were more or less similar to the changes of lipid contents in visceral mass, adductor muscle and foot muscle, except for April. In April, glycogen content in visceral mass was over four times higher than that in adductor muscle or foot muscle. There was a positive correlation in glycogen content between adductor muscle and foot muscle (r = 0.686, p < 0.001). Especially, total lipid content showed a negative correlation between the adductor muscle and visceral mass. Therefore, these results indicate that the nutrient content of the adductor muscle, visceral muscle and foot muscle changed in response to gonadal energy needs.

• Food Science and Preservation
• /
• v.11 no.2
• /
• pp.195-200
• /
• 2004

Microbial lethal value and nutrient retention of sous vide processed spinach were evaluated with mathematical model prediction and experimental trial for different package sizes and pasteurization temperatures. The package size covers 500 g, 1 kg and 2 kg, while the pasteurization temperature includes 80, 90 and 97$^{\circ}C$. The basic process scheme consists of filling blanched spinach into barrier plastic film pouch, sealing under vacuum, pasteurization in hot water with over pressure and final cooling to 3$^{\circ}C$. Pasteurization condition was designed based on attainment of 6 decimal inactivation of Listeria monocytogenes at geometric center of the pouch package by heating cycle, which was determined by general method. Heat penetration property of the package and thermal destruction kinetics were combined to estimate the retention of ascorbic acid and chlorophyll. Smaller packages with shorter pasteurization time gave better nutrient retention, physical and chemical qualities. Larger package size was estimated and confirmed experimentally to give higher pasteurization value at center, lower ascorbic acid and chlorophyll contents caused by longer heat process time. Lower pasteurization temperature with longer process time was predicted to give lower pasteurization value at center and lower ascorbic acid, while chlorophyll content was affected little by the temperature. Experimental trial showed better retention of ascorbic acid and chlorophyll for smaller package and higher pasteurization temperature with shorter heating time. The beneficial effect of smaller package and higher pasteurization temperature was also observed in texture, color retention and drip production.

• Asian-Australasian Journal of Animal Sciences
• /
• v.22 no.10
• /
• pp.1391-1399
• /
• 2009

Two hundred and sixteen 68-week-old Hy-Line brown laying hens were used in a 6-week feeding trial to compare the efficacy of phytases Optiphos (OPT) and Natuphos (NAT), which were isolated from Escherichia coli and Aspergillus niger, respectively. Hens were randomly allotted into six treatments with six replications (six layers in three adjacent cages) per treatment according to their initial BW. The hens were then subjected to one of the following dietary treatments: i) Positive Control (PC; available phosphorus (AP) 0.4%); ii) Negative control (NC; AP 0.2%); iii) NAT1 (NC+250 FTU/kg NAT); iv) NAT2 (NC+500 FTU/kg NAT); v) OPT1 (NC+250 FTU/kg OPT); vi) OPT2 (NC+500 FTU/kg OPT). Feed intake, egg production, egg quality, apparent nutrient digestibility and serum P and Ca concentration were evaluated to compare the effect of the two phytases. Feed intake and eggshell thickness were not affected by the treatments. Superior effects (p<0.05) of OPT were only observed in egg production and egg weight compared with NAT. Characteristics such as eggshell breaking strength, apparent digestibility of N, Ca and P and serum P concentration were equally increased with the supplementation of both phytases (p<0.05), where no significant difference was observed in those characteristics between PC and phytase supplementation at 500 FTU/kg. Equally effective improvements (p<0.05) were also observed in egg production and DM digestibility, where no improvements were observed (p<0.05) between the PC group and the groups with phytase supplementation at 500 FTU/kg. Equal increases in the serum Ca level were observed when the groups with phytase supplementation were compared to the PC group. Overall, the results of this study suggest that NAT and OPT are equally effective at liberating phytate-bound complexes when included in 0.2% available phosphorus diets for 68-week laying hens; either source of phytase can be fed to commercial 68-week laying hens at 500 FTU/kg to correct the negative effects associated with a 0.2% available phosphorus diet. In conclusion, either source of phytase can be fed to commercial first cycle laying hens at 500 FTU/kg to effectively replace inorganic phosphorus when economically justified.

• Korean Journal of Microbiology
• /
• v.50 no.2
• /
• pp.137-151
• /
• 2014

Various studies have been conducted to investigate effects of dams on river ecosystems, but less information is available regarding damming impacts on downstream denitrification. We measured denitrification enzyme activity (potential denitrification rate) and denitrifier abundances (using nirS, nirK, and nosZ as markers) in dammed headstreams of the Nakdong River in South Korea. Sediments in Phragmites-dominated riparian areas and in-stream areas across streams (dammed vs. reference) with different streambed materials (gravel and sand) were sampled occasionally. We hypothesized that (i) the higher available N and C contents in sediments downstream of dams foster larger denitrifier communities than in the reference system and (ii) differences in potential denitrification rates across the systems correspond with denitrifier abundances. Despite 30 years of different hydrological management with dams and greater inorganic N and DOC contents in sediments downstream of dams, compared to the references, abundances of denitrifier communities and potential denitrification rates within the whole sediment were not significantly different across the systems. However, nirS and nosZ denitrifier abundances and potential denitrification rates were considerably increased in specific sediments downstream of dams (gravelly riparian and sandy in-stream) with regard to flooding events and seasonal temperature variation. nirK was not amplified in all sediments. Canonical correspondence analyses (CCA) revealed that the relationship between abundances of denitrifier communities and nutrient availabilities and potential denitrification rates was a weak one.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.5
• /
• pp.895-905
• /
• 2000

This study was performed to investigate the removal efficiencies of pollutants at various filtration rates and the quality of the filtered water along the depth of filter media during treatment of a BNR process effluent by a dual-media gravitational rapid filtration. The results of the experiments at filtration rates of 200, 300 and 400 m/day using the effluent of a pilot scale 4-stage BNR plant showed that turbidity of the filtered water was below 2.6 NTU, satisfying the Korean standard for water for reuse. Even though the SS removal efficiency deteriorated as the filtration rate increased, the average SS concentration of the filtered water was 1.3 mg/L at all filtration rates. Simultaneous biological nitrification and denitrification was observed with nitrification efficiencies of 17.4, 18.8 and 14.3%, and denitrification efficiencies of 32.3, 27.7 and 21.4% respectively at filtration rates of 200, 300 and 400 m/day. At the latter period of each filtration cycle, the effluent T-P concentration was higher than influent T-P concentration by 6.1 to 21.4% due to phosphorous release under DO-deficient condition.

• Korean Journal of Environment and Ecology
• /
• v.29 no.5
• /
• pp.777-784
• /
• 2015

This study verified the correlations between vegetation factors, such as the number of individual species and species diversity, and soil factors in Chamaecyparis obtusa (CO) stands in Jeollanam-do. Also, the site environmental factors that affect the annual growth of CO ring width were analyzed. Positive correlations were found between the species diversity index and Cation Exchange Capacity (CEC), available phosphate, and exchangeable $K^+$ (P<0.01). In addition, strong positive correlations were also found between the number of species that appeared in the study site and CEC, available phosphorus, exchangeable $K^+$ and exchangeable $Mg^{2+}$ (P<0.01). Tree ring growth showed strong correlations with the nutrient holding capacity and fertility of soil, including available phosphate, exchangeable $K^+$, CEC, and electrical conductivity (P<0.01). The explanatory variables of tree ring growth in CO were composed of exchangeable $K^+$, organic matter content, and soil pH. The regression model had a high level of explanatory power, 74.4%. In this model, the annual growth of CO ring width increased when exchangeable $K^+$ and organic matter content were higher but decreased when soil pH was lower. According to the analysis, it is found that the annual growth of CO ring width was significantly affected by soil fertility, including available phosphate, exchangeable $K^+$, CEC, and electrical conductivity. In addition, the soil fertility of CO stands seems to be significantly affected by the supply of fallen leaves from the understory vegetation of CO.

• Journal of Embryo Transfer
• /
• v.28 no.1
• /
• pp.7-12
• /
• 2013

Body condition score (BCS) is a useful management tool for distinguishing differences in nutritional needs of cows in the herd. Although it is not always possible to quantify the nutrient content of the feed supplied to the donor cow, the nutritional status can be determined by the BCS. The objective of this study was to evaluate in vivo embryo production, return to estrous of donor and pregnancy rate of recipients following BCS in Hanwoo superovulation. Sixty nine Hanwoo donor cows were flushed on day 7 of estrus cycle with same FSH and artificial insemination by the same technicians. Embryos were recovered on 7 days after the third insemination by flushing the uterus with Embryo Collection Medium. The results obtained were as follows: No differences were observed in the efficiency of superovulation rates regardless of BCS ($${\leq_-}2.0$$, 2.5 to 3.0, and $${\geq_-}3.5$$). The mean number of total embryos was each $5.20{\pm}0.86$, $11.56{\pm}1.04$, and $6.23{\pm}1.07$. The mean number of transferable embryo from $${\leq_-}2.0$$, 2.5 to 3.0, and $${\geq_-}3.5$$ of BCS was $2.60{\pm}0.87$, $7.94{\pm}0.89$, and $4.75{\pm}1.32$, respectively (p<0.05). Return to estrous regardless of donor BCS was no difference. The pregnancy rates of recipient were BCS $${\leq_-}2.0$$ 11.76%, 2.5 to 3.0 40.79%, and $${\geq_-}3.5$$ 11.11%, following transfer of fresh embryos produced in vivo, respectively. These results indicate that if the Hanwoo with BCS 2.5 to 3.3 are used for donor and recipient, the embryo production and the conception rate will be greater.

• Korean Journal of Environmental Agriculture
• /
• v.17 no.1
• /
• pp.26-33
• /
• 1998

This experiment was conducted to classify the plant species occurring in the saline reclaimed land by saline tolerance. The vegetation of reclaimed land was composed of various plant species from halophyte to glycophyte showing different saline tolerances. In the investigated saline region, reclaimed land of Youngjong island, Inchun city, 175 species belonging to 32 families were found. Our survey was carried out in two region, having different salinity due to different desalinization. The electricalconductivity (EC) of more saline region showed 48.0mS/cm nd the other region showed 13.0mS/cm. It is assumed that intensity of precipitation and runoff of rainfall may cause salinity gradient in the investigated region. The plant species occurred in the experimental region were classified as 72 species of annual, 42 species of biennial, and 61 species of perennial according to life cycle. For knowing relationship between vegetation of saline region and saline tolerance of occurring species, we tested the saline susceptibility of plant species collected at the saline regions. Testing plants were cultured by nutrient solution containing 200 mM NaCl, the critical concentration of survival in glycophytes. The saline tolerance was graded by the growing capacity in the sand-culture system. The more saline-tolerant species screened by sand culture were Atriplex gmelini, Suaeda asparagoides, Aster tripolium, Suaeda maritima, Salicornia herbacea, and Suaeda japonica. The most saline tolerant family was Chenopodiaceae. Poaceae, Cyperaceae, and Brassicaceae showed relatively high tolerance to saline stress. In the course of growth under the high saline condition, the most noticeable change was the darkening of leaves by increasing of chlorophyll content. The chlorophyll contents were increased with saline stress in most species.

• Korean Journal of Environmental Biology
• /
• v.20 no.4
• /
• pp.339-346
• /
• 2002

From March 1998 to August 2000, the phonology and morphometrics change of Zostera caespitosa Miki were examined at the Duksan Port in the eastern coast of Korea. Morphometric characteristics (shoot height, leaf length, sheath length, leaf width, and number of leaf per shoot), size and number of reproductive structures (spathe, spadix, and seeds), shoot density, biomass and physiochemical parameters (water temperature and nutrient concentrations) were measured. Significant differences between months (p < 0.05) existed for morphometric characteristics except for sheath length. The sequence of shoot heights clearly showed cyclical annual variation with water temperature. Vegetative shoots of Z. caespitosa were present throughout the year, but reproductive shoots were rarely occurred from mid January to early April in water temperature of $9-12^\circ{C}$. Flowering in the spathe began in mid February, and seed maturing was occurred in early April. Water column nitrate and phosphate concentration showed seasonal variation, but ammonia concentration was variable with season. Relationships between shoot morphometrics and physiochemical parameters were not significantly correlated but water temperature seemed to regulate the re-productive phase and annual life cycle. The mean shoot density and above biomass of the populations were $511.6\pm{25.6}\;shoots\;m^{-2}$ and $413.4\pm{19.8}\;g\;dry\;wt\;m^{-2}$, respectively.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.13 no.2 s.29
• /
• pp.111-118
• /
• 2007

Simple box budgets models are useful tools to understand the phenomena of natural system and to provide an insight into the complex processes including physical, chemical and biological processes occurring in natural system. Budgets of fresh water, salt and nutrients were estimated in order to clarify the characteristics of seasonal material cycle in the Masan Bay. Outflow volume of freshwater into system was approximately $307.4\times10^3\sim1,210\times10^3\;m^3/day$. Inflow masses of DIP and DIN were approximately $410.8\sim795.7\;kg/day$ and $4081.4\sim6525.3\;kg/day$, respectively. DIN is expected to accumulate in the system. The removal of nutrients from bottom sediments will contribute to the reduction of 21.0% of COD concentration in the system.