Various types of karst topographies are found worldwide. Owing to their global distribution, karst areas have been extensively studied by scientists who investigate new discoveries by linking the characteristics of karst topographies with their own research fields. However, there have been only a few studies on karsts in the Republic of Korea, and little research exists on their hydrogeology. Fragmentary studies have been conducted on the hydrochemical characteristics of groundwater in limestone areas, the causes of high arsenic concentrations in groundwater, and the hydraulic conductivity of limestone areas. Research on hydrogeological characterization and flow mechanisms in these areas has only began recently. Identification and the proper management of available groundwater resources in karst (limestone) areas is essential as their unique geological characteristics render it difficult to construct reservoirs or dams at appropriate scales. We have reviewed prior work on karsts in the Republic of Korea to provide information that supports water resource security in the karst areas, to improve the understanding of the equitable use of water resources, and to identify the best management practices for groundwater resource resilience improvement.

Bursaphelenchus sinensis was first found in Austria from the wood packaging material imported from China. In Korea, B. sinensis was detected from dead branches of Pinus densiflora located in Jinju, Gyeongnam province. Morphology of B. sinensis was characterized by unique male spicule with weak rostrum and squared condylus, and female with small vulval flap and conical shaped tail. Genomic DNA of B. sinensis was extracted and ITS region was fully amplified by PCR. ITS-PCR product was analyzed by RFLP and also directly sequenced. Polymorphism by RFLP-ITS was matched with that of B. sinensis and ITS sequence data was identical to B. sinensis information in GenBank. The Korean isolate of B. sinensis, Bs-Jinju, was submitted to GenBank and acquired the accession number, #MG934676. Host pathogenicity of B. sinensis was tested by artificial inoculation of nematode (30,000/ sapling) on 5-year-old P. densiflora. There were no disease symptoms in all tested pines inoculated by B. sinensis, whereas 100% mortality showed on pine saplings by B. xylophilus inoculation. This is the first report of B. sinensis in South Korea.

재선충속(Bursaphelenchus) 선충의 식물 기주체내 증식 능력 및 병원성을 비교하기 위하여 선충 3종 (이하 Bursaphelenchus xylophilus: Bx, B. mucronatus: Bm, B. thailandae: Bt)과 해송(Pinus thunbergii), 잣나무(Pinus koraiensis) 2종을 실험에 사용하였다. 5가지 선충 처리 조합 (①Bx+Bt, ②Bx+Bm, ③Bx+Bt+Bm, ④Bt+Bm, ⑤Bm)으로 한 본당 10,000마리씩 접종 한 후 7주 동안 외부 병징 및 선충 밀도를 조사하였다. 그 결과, Bx가 포함된 대부분 처리구에서는 5주 차에 전체 고사가 진행 되었고, Bx가 포함되지 않은 처리구는 병징이 나타나지 않았다. 예외적으로, Bx+Bm, Bx+Bt+Bm 해송 처리구에서는 7주 후에도 전체고사가 나타나지 않았다. 이 경우 선충 밀도 조사 결과, Bm이 약 42%를 차지하였으며, 이는 소나무재선충병의 병징 발현을 약화를 유도하는 역할을 하는 것으로 추정된다. 모든 처리구에서 Bx의 밀도가 가장 높았으며, Bt는 전혀 검출되지 않았다.

소나무재선충과 근연종인 Bursaphelenchus 속 2종간의 매개충 채내 침입력과 경쟁력을 비교 실험하였다. 공시충은 Bursaphelenchus xylophilus (이하 Bx), B. mucronatus (이하 Bm), B.thailandae (이하 Bt) 선충 3종과 솔수염하늘소 (Monochamus alternatus)와 북방수염하늘소 (M. saltuarius) 2종을 사용하였다. 매개충 번데기에 선충 3종을 10,000 마리씩 단독 또는 혼합접종을 하고, 우화 후 체내 선충 개체수를 조사한 결과, 솔수염하늘소에서는 Bx, Bm, Bt가 각각 2,283마리, 1,575마리, 3,083마리로써 Bt의 침입력이 가장 높게 나타났다. Bx+Bt 처리 시에는 Bx 24%, Bt 76%, Bx+Bm 처리 시, Bx 68%, Bm 32% 비율로 조사되어 Bt>Bx>Bm 순으로 침입력이 강한 것이 확인되었다. 북방수염하늘소 에서 Bx, Bm의 침입력을 비교한 결과 Bx는 2,120마리, Bm 1,730마리로 솔수염하늘소에서와 유사한 결과를 나타내었다. 이로써 선충 종간 침입력은 다양하며 이는 매개충 종과는 무관함을 알 수 있다.

Oxathiapiprolin은 병원균의 포자형성과 효모성장을 저해하여 노균병을 방제하는 piperidinyl thiazole isoxazoline 계열 살균제로 2015년 국내 사용등록이 요청된 신규약제이다. 본 연구에서는 oxathiapiprolin의 신규등록과 관련해 안전관리를 위한 공정시험법 마련이 요구되어 농산물 중 잔류분석법을 개발하였다. 농산물 중 oxathiapiprolin은 acetonitrile로 추출한 뒤 분배효율 향상을 위해 1 N sodium hydroxide (NaOH)를 이용해 염기성으로 조절하여 비해리상태로 만든 뒤 dichloromethane으로 액액분배하였으며 분배추출액은 silica SPE 카트리지로 정제한 뒤 HPLC-UVD로 분석하였다. 개발된 분석법의 검출한계(LOD) 및 정량한계(LOQ)는 각각 0.003, 0.01 mg/kg이었고, 대표농산물 5종(고추, 감귤, 감자, 대두, 현미) 중 oxathiapiprolin의 평균 회수율은 86.7-112.7%(상대표준편차, RSD ≤ 10%)으로 나타났다. 이는 잔류물 분석에 관한 CODEX 가이드라인 (CAC/GL 40)을 만족하는 것으로 확인되었다. 따라서 개발된 분석법은 국내외 유통 농산물 중 oxathiapiprolin의 안전평가를 위한 잔류량 적부 판정에 있어 공정시험법으로 사용되기에 적합할 것으로 판단된다.

이 연구는 축산물 중 포레이트 및 대사산물 5종의 안전관리를 위한 공정분석법을 확립하기 위하여 수행하였으며 분석법의 선택성, 검출한계 및 정량한계, 회수율에 대한 검증을 통하여 포레이트 및 대사산물 5종의 공정시험법으로의 유효성을 확인하였다. 포레이트 및 대사산물 5종을 신속하고 효과적으로 동시에 분석하기 위하여 LC-MS/MS를 사용하였고, 1% 아세트산 포함 아세토니트릴 추출 후PSA, C18을 이용해 정제하였다. 개발된 분석법의 평균 회수율은 79.2-113.9%였으며, 분석오차는 19.2% 이하로 정확성 및 재현성이 우수함을 확인할 수 있었다. 개발된 분석법은 국제적 잔류농약 분석 가이드라인에 적합한 수준이었으며 축산물 중 포레이트 및 대사산물 5종의 잔류검사를 위한 공정분석법으로 활용할 수 있을 것으로 판단된다.

Nesfatin-1/NUCB2, which is associated with the control of appetite and energy metabolism, was reported for the first time to be expressed in the hypothalamus. However, recent studies have shown that nesfatin-1/NUCB2 was expressed not only in the hypothalamus, but also in various tissues including digestive and reproductive organs. We also demonstrated that nesfatin-1/NUCB2 was expressed in the reproductive organs, pituitary gland, heart, lung, and gastrointestinal tract of the adult mouse. However, little is known about nesfatin-1/NUCB2 expression in fetal and neonatal mice. Therefore, we examined here the distribution of nesfatin-1/NUCB2 in various organs of fetal and neonatal mice and compared them with the distribution in adult mice. As a result of immunohistochemical staining, nesfatin-1/NUCB2 protein was expressed relatively higher in the lung, kidney, heart, and liver compared to other organs in the fetus. Western blot results also showed that nesfatin-1/NUCB2 protein was detected in the lung, kidney, heart, and stomach. Next, we compared the expression levels of nesfatin-1/NUCB2 mRNA in the fetus and neonate with the expression levels in both male and female adult mice. The expression levels in heart, lung, stomach, and kidney were higher compared with other organs in fetal and neonatal mice and in both male and female adult mice. Interestingly, the expression of nesfatin-1/NUCB2 mRNA in the kidney was dramatically increased in male and female adult mice compared to fetal and neonatal mice. These results indicate that nesfatin-1/NUCB2 may regulate the development and physiological function of mouse organs. In the future, we need more study on the function of nesfatin-1/NUCB2, which is highly expressed in the heart, lung, and kidney during mouse development.

Recent study showed that T cells in the immune organs and peripheral blood are influenced by estradiol, leading to a dysfunction of the immune system. However, little is known about the thymic-gonadal relationship during the estrous cycle in mouse. Therefore, the purpose of this study was to elucidate the mechanism by which a change in estradiol levels during the estrous cycle regulates the development of T cells in the mouse thymus. Six-week-old ICR mice were used and divided into four groups, including diestrous, proestrous, estrous, and metestrous. We first confirmed that ER-α and - β estrogen receptors were expressed in thymic epithelial cells, showing that their expression was not different during the estrous cycle. There was also no significant difference in thymic weight and total number of thymocytes during the estrous cycle. To determine the degree of thymocyte differentiation during the estrous cycle, we analyzed thymocytes by flow cytometry. As a result, the percentage of CD4+CD8+ double-positive (DP) T cells was significantly decreased in the proestrous phase compared to the diestrous phase. However, CD4+CD8- or CD4-CD8+ (SP) T cells were significantly increased in the proestrous phase compared to the diestrous phase. In addition, the percentage of CD44+CD25- (DN1) T cells was significantly decreased in the estrous phase compared to other phases, whereas the percentages of CD44+CD25+ (DN2), CD44-CD25+ (DN3), and CD44-CD25- (DN4) were not changed during the estrous cycle. These results indicate that the development of thymocytes may arrest in the DP to SP transition stage in the proestrous phase displaying the highest serum level of estradiol. This study suggests that a change in estradiol levels during the estrous cycle may be involved in the regulation of thymocyte differentiation in the mouse thymus.