• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.10 no.2
• /
• pp.97-114
• /
• 1977

The fresh water prawn, Macrobrachium rosenbergi(de Man) is a very common species in Indopacific region, which inhaits both fresh and brackish water in low land area, most of rivers and especially aboundant in the lower reaches which are influenced by sea water. It is one of the largest and commercial species of genus Macrobrachium, which is commonly larger than $18\~21cm$ in body length, from the basis of eye-stalked to the distal of telson. As a part of the researches in order to investigate the possibilities on transplantation and propagation of this species, this work dealt with the problems on the effects of chlorinities upon zoeal larvae and post-larvae 1). metamorphosis rate and optimum chlorinity for metamorphosis to post-larve, 2). tolerance and comparative survival rate on various chlorinties, from fresh water to sea water $(19.38\%_{\circ}\;Cl)$, which reared for six days upon each stage of zoeal larvae, 3). accomodation rate on chlonities which reared for twelve days after transmigration into variant chlorinities of the range from $3.68\%_{\circ}$ Cl to $1.53\%_{\circ}$ Cl in the way of rearing of the range from $3.82\%_{\circ}$ Cl to $11.05\%_{\circ}$ upon each stage of zoea, 4). tolerance on both of fresh and sea water upon zoeal larva and post-larva under the condition of $28^{\circ}C{\pm}1$ in temperature and feeding on Artenia salina nauplii, 5). relationship between various chlorinities and grwth of post-larvae under the condition of $28^{\circ}C$ in tmperature and feeding on meat of clam. Thus these investigations were performed in order to grope for a comfortable method on seedmass production. Up to the present, the study on the effects of chlorinity upon earlier zoeal larvae and post-larvae of Macrobrachium species has been scarcely performed by workers with the exception of Lewis(1961) and Ling (1962,, 1967), even so their works were not so detailed. On the other hand, larvae of several species of this genus were reared at the water which mixed sea water so as to carry out complete metamorphosis to post-larva by workers in order to investigate on earlier 1 arval and earlier post-larval development, such as Macrobrachium lamerrei (Rajyalakshmi, 1961), M. rosenbergi and M. nipponense (Uno and Kwoa, 1969; Kwon and Uno, 1969), M. acanthurs (Choudhury, 1970; Dobkin, 1971), M. carcinus(Choudhury, 1970), M. formosense(Shokita, 1970), M. olfersii (Duggei et al., 1975), M. novaehallandiae (Greenwood et al., 1976), M. japonicum (Kwon, 1974) and M. lar (Shokita, personal communication), and there fore it is regarded that chlorinity is, generally, one of absolute factors to rear zoeal larvae of brackish species of Macrobrachium genus. Synthetic results on this work is summarized as the follwings: 1) Zoeal larvae required different chlorinities to grow according to each stage, and generally, it is regarded that optimum range of living and growing is from $7.63\%_{\circ}Cl\to\;7.63\%_{\circ}Cl$, and while differences of metamorphsis rate, from first zoea to post-larva, is rarely found in this range, and however it occurs apparently in both of situation at $7.63\%_{\circ}Cl$ below and $16.63\%_{\circ}Cl$ above and moreover, metamorphosis rate is delayed somewhat in case of lower chlorinity as compared with high chlorinity in these situations. 2) Accomodation in each chlorinity on the range, from fresh water to sea water, is different according to larval stages and while the best of it is, generally, on the range from $14.24\%_{\circ}Cl$ to $8.28\%_{\circ}Cl$ and favorite chlorinity of zoea have a tendency to remove from high chlorinity to lower chlorinity in order to advance larval age throughout all zoeal stages, setting a conversional stage for eighta zoea stage. 3) Optimum chlorinity of living and growth upon postlarvae is on the range of $4.25\%_{\circ}Cl$ below, and in proportion as approach to fresh water, growth rate is increased. 4) Post-large are able to live better in fresh water in comparison with zoeal larvae, which are only able to live within fifteen hours, and by contraries, post-larvae are merely able to live for one day as compared with ?미 larvar, which are able to live for six days more in sea water $19.38\%_{\circ}Cl\;above$. 5) Also, in case of transmigration into higher and lower chlorinities in the way of rearing in the initial chlorinities $ 3.82\%_{\circ}Cl,\;7.14%_{\circ}Cl\;and\;11.05%_{\circ}Cl$, accoodation rate is a follow: accomodation capacity in ease of removing into higher chlorinities from lower chlorinities is increased in proportion as earlier stages, setting a conversional stage for eighth zoea stage, and by contraries, in case of advanced stages from eighth zoea it is incraesed in proportion as approach to post-larva stage in the case of transmigration into lower chlorinity from higher chlorinity. On the other hand, it is interesting that in case of reciprocal transmigration between two different chlorinitiess, each survival rate is different, and in this case, also, its accomodation in each zoea stage has a tendency to vary according to larval stages as described above, setting a conversional stage for eighth zoea stage. 6) It is likely that expension of radish pigments on body surface is directly proportional to chlorinity during the period of zoea rearing, and therefore it seems like all body surfacts of zoea larvae be radish coloured in case of higher chlorinity. 7) By the differences that each zoeal larvae, postlarvae, juvaniles and adult prawn are required different chlorinity for inhabiting in each, it is regarded that this species migrats from up steam to near the estuary of the river which the prawns inhabits commonly in natural field for spawning and growth migration. 8) It had better maintainning chlorinities according to zoeal stage for a comfortable method on seed-mass production that earlier larva stages than eighth zoea are maintained on the range from $8\%_{\circ}Cl\;to\;12\%_{\circ}Cl$ to rear, and later larva stages than eighth zoea, by contraries, are gradually regula ted-to love chlorininity of the range from $7\%_{\circ}Cl\;to\;4\%_{\circ}Cl$ according to advance for post-larva stage.

• Korean Journal of Agricultural Science
• /
• v.29 no.2
• /
• pp.20-34
• /
• 2002

This study was conducted to examine the effects of an Aspergillus oryzae fermentation culture on the in vitro digestibilities of dry matter, crude fiber, acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein, and pH in in vitro experiment of diets for dairy cows. A fungal species, Aspergillus oryzae was supplied by Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea (KCTC 1229). The experimental diets were commercial compound feed (concentrate) and total mixed ration (TMR) for lactating cows, of which chemical analyses were determined at Research and Development Institute, Woosung Feed Co., Ltd., while the digestibilities were done at the laboratory of Chungnam National University. Aspergillus oryzae culture products were added to compound feed and TMR at the rate of 0, 1.0, 2.0, 3.0% respectively. The experimental diet with the rumen fluid sampled from Holstein fresian milking cows were used and digested for 24 hrs, 48hrs and 72hrs in the shaking incubator. The residues of the digesta were digested for 48hrs in the incubator in which put 30ml of 0.1N HCl with 0.2% pepsin at $39^{\circ}C$. The final precipitates were dried for 48hrs in the drier at $60^{\circ}C$. These experimental procedures were triplicated to determine the in vitro digestibility of dry matter, crude fiber, ADF, NDF, crude protein and pH. Compared to control diet, not added Aspergillus oryzae, the DM digestibility of fungal diets were improved 2.1%(63.1%), 9.7%(68.5%) and 9.0%(68.0%) for 24 hour fermentation in compound feed while 4.8%(60.0%), 6.4%(61.1%) and 2.9%(58.8%) in TMR. On the contrary, for 48 hour and 72 hour digestibilities, the effects of Aspergillus oryzae culture on the digestibility of dry matter were relatively lowered compared to 24 hour digestibility. Referring to the digestibility of dietary fiber, Aspergillus oryzae was believed to significantly improve digestibilities of crude fiber, ADF and NDF. Those were increased up to 13.3%(53.3%) for 24 hour fermentation, while 2.4%(54.6%) for 3.0% added for 72 hour fermentation in compound feed. However, there were no significant differences among the treatments for the inclusion rate of Aspergillus oryzae, even though the more inclusion rate, the better digestibility. The protein digestibilities were significantly improved from 0.4%(79.7%) to 9.4%(71.8%) by adding Aspergillus oryzae into compound feed. However, there were no significant differences between the two experimental diets, 2.0% and 3.0% Aspergillus oryzae included diets. In case of TMR, the protein digestibilities were significantly improved from 4.0%(70.4%) to 6.3%(65.1%) by adding Aspergillus oryzae. However, there were no significant differences between the two experimental diets, 2.0% and 3.0% Aspergillus oryzae included diets. In this study, there were no significant differences among the treatments in pH. On the contrary, there were slightly decrease in pH by adding Aspergillus oryzae into experimental diets but not significant. Summarizing the results of this examination, Aspergillus oryzae fermentation culture is believed to improve the digestibilities of dry matter, fiber and crude protein in cattle diets. However, more detailed research for the mechanism of the fungal culture is required to improve ruminal environment.

• The Korean Journal of Mycology
• /
• v.7 no.2
• /
• pp.91-116
• /
• 1979

This paper is to investigate the standing crops and microfungal flora in soil in Phyllostachys reticulata forests in both the Yesan area (A) and the Kwangsan area (B). The stand density of the bamboo revealed 17,250 shoots per ha in area A, and in area B 14,780 shoots which were 16.1% less in number than area A. In respect to the environmental factors between the two areas, the mean temperature during the growth period was $1.5{\sim}2^{\circ}C$ higher in area B than in area A, soil tempeature also was $1{\sim}2^{\circ}C$ higher in area B, and the total quantities of nitrogen, phosphoric acid and organic compounds contained in the soil of area B were also slightly higher than those of area A. In area B the quantities of dried leaf matter, humus, and vegetation in the bamboo forest were also larger than in area A. In addition, five more species of microfungi which playa role in the decomposition of the various organic materials in the bamboo forests were identified in area B: Mortierella elongata, Mucor circinelloides, Aspergillus japonicus, Penicillium waksmani and Trichoderma lignorum. The atmospheric temperature in the inner portions of the bamboo forests was lower than the outside temperature, but the humidity was higher. The rates of relative illuminance were measured in area A at 4.19%, and in area B at 2.7%. These values revealed that the photosynthetic acitivity in the lower part of the bamboo was lost but it was considered that lower illuminance increased the microfungal activities in the vicinity of the surface soil. Since the productive structure of the bamboo showed that the maximum amount of photosynthesis was located in the upper portion of the bamboo in area B, it was considered to be an effective structure in maintaining the high productivity of the bamboo. The allometric relation between $D^2H$ and dry weight of stems(Ws), branches(Wb) and leaves(Wl) of the bamboo in area A were appoximated by log Ws=0.5262 log $D^2H$+1.9546; log Wb=0.6288 log $D^2H$+1.5723; log Wl=0.5181 log $D^2H$+1.8732, and those of the bamboo in area B were approximated by log Ws=0.5433 log $D^2H$+1.8610; log Wb=0.1630 log $D^2H$+2.3475; log Wl=0.4509 log $D^2H$+2.0041. From the above, the standing crops in area A were measured thus: Ws was 1,128. 83kg; Wb, 689.05kg; Wl, 926.69kg and Wl, 2,744.57kg per 10a. In area B, Ws was 1,206. 66kg; Wb, 679.92kg; Wl, 1,112.51kg and Wt, 2.999kg per l0a. Significant differences from the result of t-test were for $D^2H$ Ws, Wl and Wt between areas A and B. But no significant difference was found for Wb. In order to record as completely as possible the microfungal flora of the areas, every possible means was tried, and 158 strains of fungi were isolated, and of these, the microfungi of 55 species were identified. The dominant species were Trichoderma viride, Penicillium janthinellum, P. commune, Aspergillus oryzae, A. niger, A. gigantus, A. fumigatus, Mortierella ramaniana, var. anguliFPora, Mucor hiemalis and Zygorhynchus moelleri. According to the above results, it was revealed that optimum soil, the increases of soil materials, more species of soil microfungi, and the atmospheric temperature during the growth period have made the bamboo flourish and bring more species and larger quantities of vegetation in the bamboo forests. The correlation between the standing crops and environmental factors in the bamboo forest is considered to be a complicated relationship of all the factors, but the stand density is thought to be the most important factor involved.

• Archives of Pharmacal Research
• /
• v.19 no.4
• /
• pp.280-285
• /
• 1996

The sustained release dosage form which delivers melatonin (MT) in a circadian fashion over 8 h is of clinical value for those who have disordered circadian rhythms because of its short halflife. The purpose of this study was to evaluate the gelling properties and release characteristics of alginate beads varying multivalent cationic species $(Al^{+++}, \; Ba^{++}, \; Ca^{++}, \; Mg^{++}, \; Fe^{+++}, \; Zn^{++})$. The surface morphologies of Ca- and Ba-alginate beads were also studied using scanning electron microscope (SEM). MT, an indole amide pineal hormone was used as a model drug. The $Ca^{++}, \; Ba^{++}, \; Zn^{++}, \; Al^{++}\; and\; Fe^{+++}\; ions\; except\; Mg^{++}$ induced gelling of sodium alginate. The strength of multivalent cationic alginate beads was as follows: $Al^{+++}\llFe^{+++} the induced hydrogel beads were very fragile and less spherical. Fe-alginate beads were also fragile but stronger compared to Al-alginate beads. Ba-alginate beads had a similar gelling strength but was less spherical when compared to Ca-alginate beads. Zn-alginate beads were weaker than Ca- and Ba-alginate beads. Very crude and rough crystals of Ba- and Ca-alginate beads at higher magnifications were observed. However, the type and shape of rough crystals of Ba- and Ca-alginate beads were quite different. No significant differences in release profiles from MT-loaded multivalent cationic alginate beads were observed in the gastric fluid. Most drugs were continuously released upto 80% for 5 h, mainly governed by the passive diffusion without swelling and disintegrating the alginate beads. In the intestinal fluid, there was a significant difference iq the release profiles of MT-loaded multivalent cationic alginate beads. The release rate of Ca-alginate beads was faster when compared to other multivalent cationic alginate beads and was completed for 3 h. Ba-alginate beads had a very long lag time (7 h) and then rapidly released thereafter. MT was continuously released from Feand Zn-alginate beads with initial burstout release. It is assumed that the different release rofiles of multivalent cationic alginate beads resulted from forces of swelling and disintegration of alginate beads in addition to passive diffusion, depending on types of multivalent ions, gelling strength and drug solubility. It was estimated that 0.2M $CaCl_2$ concentration was optimal in terms of trapping efficiency of MT and gelling strength of Ca-alginate beads. In the gastric fluid, Ca-alginate beads gelled at 0.2 M $CaCl_2$ concentration had higher bead strength, resulting in the most retarded release when compared to other concentrations. In the intestinal fluid, the decreased release of Ca-alginate beads prepared at 0.2 M $CaCl_2$ concentration was also observed. However, release profiles of Ca-alginate beads were quite similar regardless of $CaCl_2$ concentration. Either too low or high $CaCl_2$ concentrations may not be useful for gelling and curing of alginate beads. Optimal $CaCl_2$ concentrations must be decided in terms of trapping efficiency and release and profiles of drug followed by curing time and gelling strength of alginate beads.

• Korean Journal of Plant Taxonomy
• /
• v.37 no.2
• /
• pp.115-129
• /
• 2007

Using internal transcribed spacer (ITS) sequences and inter-simple sequence repeats (ISSRs) data, genetic diversity of a rare species, Hibiscus hamabo Siebold & Zucc. was examined for 3 populations in Jeju Island, Korea. A total of 14 nucleotide (excluding 3 ambiguous nucleotide) site variation in the ITS was observed from 18 individuals (Population 1, Hadori), which differed up to 13 bp in pair-wise comparison. On the contrary, the ITS sequences of all individuals in Populations 2 and 3 were identical. Genetic diversity estimates including Nei's gene diversity (h) generated by ISSR data were substantially high in Population 1 compared to other two populations. Low genetic variation in Populations 1 and 2 is considered due to genetic drift (bottleneck effect) and limited gene flow in these populations. Considering the differences in genetic diversity, protection of the Population 1(Hadori) is very critical for in situ conservation of Hibiscus hamabo in Korea. If ex situ conservation is required, making the full use of Population 1 will be most efficient.

• Korean Journal of Microbiology
• /
• v.21 no.2
• /
• pp.71-78
• /
• 1983

The number of aerobic free-living nitrogen fixation bacteria and factors in soil at different stands covered with Pinus rigida, Quercus acutissima and Zoysia japonica in Cheongju area were investigated from Feb. to Sept 1981. 1. The numbers of $N_2-fixation$ bacteria, according to the seasonal changes, increased gradually from winter to spring and summer. But the growth pattern revealed some differences in accordance with plant cover stands : the numbers increased abruptly in May at Pinus, May-June at Quercus and Apr. May at Zoysia stand. The pick of numbers represented in Aug. Sept, at Pinus, Jul-Aug. at Quercus and May-Jun. at Zoysia stand, respectively. 2. The interrelationship between the monthly changes of enviotnmental factors and numbers of $N_2-fixation$ bacteria at different stands, mainly depends upon the soil temperature than other soil factors (r=0.71-0.84). The numbers of $N_2-fixation$ bacteria may increase 5-7 times according to increase $10^{\circ}C$ of soil temperature, and optimal range was $20{\sim}30^{\circ}C$ for growth. Equation of the interrelation between soil temperature and numbers could be stated as follows : log y=ax+b. 3. In the case of high soil temperature, the bacterial numbers presented high level in drought periods. Therefore, the $N_2-fixation$ bacterial species in these soil seem to consist of resistant to desication. 4. The influence of soil organic matter for growth of $N_2-fixation$ bacteria indicated low conrelation. The reason may seen the content of organic matter in these soil existed abundantly above the quantities of limitation for growth. 5. In artifical gradients, the $N_2-fixation$ bacteria were predominated at $20{\sim}30^{\circ}C$ same as natural condition, pH7-8, and 20-30% of soil water contents. 6. The vertical distribution of bacteria marked decreasing trends from surface to lower layers, and the decreasing degree was shown well in Zoysia, Quercus and Pinus stand in order. But in the trees, the numbers increased at 30cm layer estimated the region of root than 20cm layer. 7. Both catalase megative and positive group of $N_2-fixation$ bacteria in soil increased according to the rise of the soil temperature. Catalase positive group was revealed as dominant group in winter, and catalase negative group revealed in summer. The change of dominant pattern was shown during Feb. to Apr.

• Korean Journal of Ecology and Environment
• /
• v.36 no.4 s.105
• /
• pp.434-446
• /
• 2003

The fate and transport of many trace metals, metalloids, and radionuclides in porous media is closely linked to the biogeochemical reactions that occur as a result of organic carbon being sequentially degraded by different microorganisms using a series of terminal electron acceptors. The spatial distribution of these biogeochemical reactions is affected by processes that are often unique and/or characteristic to a specific environment. Generic model formulations have been developed and applied to simulate the fate and transport of arsenic in two hydrologic settings, permanently flooded freshwater sediments, namely non-vegetated wetland sediments and vegetated wetland sediments. The key physical processes that have been considered are sedimentation, effects of roots on biogeochemistry, advective transport, and differences in mixing processes. Steady-state formulations were applied to the sedimentary environments. Results of numerical simulations show that these physical processes significantly affect the chemical profiles of different electron acceptors, their reduced species, and arsenate as well as arsenite that will result from the degradation of an organic carbon source in the sediments. Even though specific biological transformations are allowed to proceed only in zones where they are thermodynamically favorable, the results show that mixing as well as abiotic reactions can make the profiles of individual electron acceptors overlap and/or appear to reverse their expected order.

• The Korean Journal of Pesticide Science
• /
• v.16 no.1
• /
• pp.54-61
• /
• 2012

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pest species devastating many horticultural and ornamental crops and fruit trees. Difficulty in managing this mite is largely attributed to its ability to develop resistance to many important acaricides. Development of 3,700-folds resistance to etoxazole was found in the population of T. urticae collected from rose greenhouses in Buyeo, Chungnam Province in August 2000. This population has been selected for eleven years with etoxazole (over 500 times), and increased over 5,000,000-folds in resistance as compared with susceptible strain. Also, etoxazole-resistant strain was shown to be maternally inherited. The objective of this study was to determine whether resistance of T. urticae to etoxazole was linked with point mutations in the mitochondrial gene. DNA sequencing of cytochrome c oxidase subunit I (COX1), COX2, COX3, cytochrome b (CYTB), NADH dehydrogenase subunit 1 (ND1), ND2, ND3, ND4, ND5, and ND6 were analyzed by comparing two etoxazole-susceptible and etoxazole-resistant strains. As a result, differences were not detected between the nucleotide sequences of two strains within a mitochondrial gene.

• Korean Journal of Plant Taxonomy
• /
• v.43 no.1
• /
• pp.46-55
• /
• 2013

The purpose of this study is to review the taxonomic position of Taxus cuspidata var. latifolia endemic to Ulleung Island with related taxa T. cuspidata var. cuspidata, T. caespitosa, and T. cuspidata var. nana based on external morphological characters and DNA barcoding study. T. cuspidata var. latifolia was similar to T. cuspidata var. cuspidata in the arbor, straight trunk, and symmetric arrangement of leaf. But the unique differences between T. cuspidata var. latifolia and T. cuspidata var. cuspidata were leaf size and the exposure of seed from aril. Additionally, sequences of four chloroplast DNA regions including matK, rbcL, trnL intron and trnL-trnF spacer regions were analyzed. Korean Taxus species and their related taxon T. cuspidata var. nana were strongly supported as a monophyletic group in neighbor-joining analysis. Taxus cuspidata var. latifolia showed 100% sequence identity to related taxa. Korean endemic T. caespitosa is also distinguishable from related taxa by prostrate stems and spiral arrangement of leaf. The examinations of external morphology and DNA barcoding study suggest that the taxonomic position of T. cuspidata var. latifolia should be maintained as a variety of T. cuspidata.

• Journal of Life Science
• /
• v.22 no.4
• /
• pp.466-471
• /
• 2012

Sixty individuals of the scallop $Patinopecten$ $yessoensis$ (Genus Pecten) were sampled to examine the genetic diversity and population structure of this species. Random amplified polymorphic DNA (RAPD) identified 109 genotypes and produced 79 polymorphic loci (72.8%). Total genetic diversity values ($H_T$) and interlocus variation in the within-population genetic diversity ($H_S$) were 0.254 and 0.178, respectively. On a per-locus basis, the proportion of total genetic variation due to differences among populations ($G_{ST}$) was 0.299. This indicated that about 70.1% of the total variation was within populations. The unique loci and bands of $P.$ $yessoensis$ were shown in only one population among the three countries. RAPD markers were very effective in classifying the natural population levels of $P.$ $yessoensis$ in Korea, China, and Japan. In addition, insights into the relative gene diversity among and within populations of $P.$ $yessoensis$ would be useful in breeding and for the development of strategies for animal genetic resources.