This research investigated various aspects of language learning strategies used by undergraduate and graduate students studying Korean. The study focused on four language skills, pronunciation, and vocabulary. The survey was conducted on 322 participants, Korean learners both in Korea and in other countries. It examined the usage of learning strategies used by the learners including the following variables: gender, experiences of living in Korea, first languages, and the countries Korean was learned. The quantitative data from the survey were analyzed by univariate ANOVAs to find out which skill is significant among the variables and the findings are as follows: 1) The greatest frequency of learning strategies appeared in the order of listening, pronunciation, writing, speaking, vocabulary, and reading. Listening skill showed the most varied learning strategies. 2) The analysis of learning strategies according to the variables with respect to the language skills revealed that gender influenced listening, the experience of the target country influenced reading, and the first language influenced writing. Pedagogical implications and further research suggestions are discussed.

The aim of this study was to investigate change of plasminogen activators (PAs) and their inhibitors (PAIs) mRNA and protein expression level by heat stress in porcine endometrial cells. The endometrial epithelial cells were isolated from endometrial epithelium in porcine uterus and cultured in different temperature conditions (38.5 and 41.5℃) for 24 h. Expression of urokinase-type PA (uPA), tissue-type PA (tPA), PA inhibitor-1 (PAI-1) and -2 (PAI-2) mRNA in epithelial cells were analyzed using reverse transcription-PCR and protein levels were measured by immunofluorescence. In result, mRNA expression of uPA, tPA, PAI-1 and PAI-2 were decreased in 41.5℃ than 38.5℃ culture condition, however, significant differences were no detected. uPA, tPA and PAI-2 protein were mainly expressed in nucleus, whereas PAI-1 was distributed in cytoplasm and nucleus. uPA and tPA protein levels were increased by heat stress treatment and significant difference was only detected in tPA level (p<0.05). In contrast, two types of PAIs protein level were decreased in 41.5℃ cultured group compared with 38.5℃ group. In present study, tPA protein expression was upregulated by heat stress in porcine endometrial cells. This result suggest that change of tPA by heat stress may be related to blood flow into uterus and intrauterine microenvironments, and could directly and indirectly influence to reproductive performance in pigs.

The aim of this study was to evaluate effect of α-linolenic acid (ALA) on viability, acrosome reaction and mitochondrial intact in frozen-thawed boar sperm. The boar semen was collected by gloved-hand method and cryopreserved in 20% egg yolk freezing extender containing ALA (0, 3, 5, and 10 ng/mL) with 0.05% ethanol. The frozen-boar spermatozoa were thawed at 37.5°C for 45 sec in water-bath. The spermatozoa samples were evaluated the plasma membrane integrity, acrosome reaction, and mitochondrial integrity using flow cytometry. In results, population of live sperm with intact plasma membrane was significantly higher in control and 3 ng/mL ALA treatment group than ethanol group (p<0.05). In contract, dying sperms were higher in ethanol group than 3 ng/mL ALA treatment (p<0.05). Acrosomal membrane damage in all sperm population was reduced in 3 ng/mL ALA groups compared with ethanol treatment (p<0.05). However, acrosome damage in live sperm population was no significant difference among the all treatment groups. Mitochondrial integrity was not influenced by ALA treatments in both of live and all sperm population. In conclusion, this results show that supplement of ALA during the cryopreservation process could reduce the membrane damages including plasma and acrosomal membrane, whereas ALA did not influence to mitochondria in boar spermatozoa. Therefore, these results suggest that ALA can protect against the membrane damage derived cryo-stress, and cryopreservation efficiency of boar semen would be improved by use of ALA.

As a one of unsaturated fatty acid, polyunsaturated fatty acids (PUFAs) have multiple actions: as precursor of prostaglandins (PGs), steroid hormone synthesis and energy production in animal reproduction. PUFAs, which include omega-3 (n-3) and omega-6 (n-6), are derived from the diet and changed by diet, species, breed and season. The plasma membrane of spermatozoa in mammals contain various PUFAs. These composition of PUFAs regulate the membrane fluidity and cause lipid peroxidation via generation of reactive oxygen species (ROS). Induced lipid peroxidation by ROS decreased viability and motility of spermatozoa, and it is reduced by addition of antioxidant and low concentration of PUFAs. Because oocytes of animal have a high lipid components, process of oocyte maturation and embryo development are influenced by PUFAs. In in vitro study, oocyte maturation, embryo development, intracellular cAMP and MAPK activity were increased by treatment of n-3 α-linolenic acid (ALA) during maturation, whereas n-6 linoleic acid (LA) negatively influenced. Also, inhibition of fatty acid metabolism in oocyte influenced blastocyst formation of cattle. PGs are synthesized from PUFAs and various PUFAs influence PGs via regulation of PG-endoperoxide synthase (PTGS). Steroid hormone synthesis from cholesterol is regulated by expression of steroid acute regulator (StAR) protein and mRNA. Exogenous n-3 and n-6 PUFAs altered sex hormone in animal through stimulate or inhibit StAR activity. Because PUFAs altered PG and steroid hormone synthesis, follicular development was influenced by PUFAs. This effect of unsaturated fatty acid could provide information for improvement of reproductive ability in animals.