The Ministry of Oceans and Fisheries promoted the installation of eel-ladder for the purpose of creating inland water resources. Currently, eel-ladder have been installed and operated at the Geumgang Estuary Bank (2018), Yeongam Embankment (2019), and Asanman Embankment (2020). In this study, the number of glass eels in eel-ladder in 2021 was monitored and factors affecting the rise that from ocean to river of eels were investigated. Glass eels in eel-ladder were found when the salinity was relatively low, and they started when the freshwater and seawater temperatures were above 20℃. Comparing the number of occurrences by year, the largest number of glass eels was observed in 2021, but it is judged that this is not according to the distribution of glass eels in sea, but rather as a result of the investigator’s eel-ladder repair and guidance on illegal fishing.

2020년 3월부터 10월까지 군산시의 중초산 저수지와 북초산 저수지의 어류상 및 군집분석을 하였다. 조사기간 동안 채집된 어류는 중초산 저수지에서 4목 5과 8종 1,895개체, 북초산 저수지에서 3목 5과 7종 171개체였다. 중초산 저수지의 우점종은 참붕어 (661개체, 상대풍부도: 34.7%) 아우점 종은 흰줄납줄개 (660개체, 상대풍부도: 34.7%), 북초산 저수지는 배스 (77개체, 45.0%)와 붕어 (60개체, 35.1%) 순으로 나타났다. 군집분석 결과 중초산 저수지는 우점도 0.697, 다양도 1.483, 균등도 0.713, 종 풍부도 0.928, 북초산 저수지는 우점도 0.801, 다양도 1.304, 균등도 0.670, 종 풍부도 1.167을 보였다. 본 연구 결과를 통해 생태계 교란생물인 배스의 영향으로 토착어종의 개체수와 군집의 다양도가 감소한 것을 확인할 수 있었다. 따라서 외래어종의 지속적인 제거와 유입을 막는 관리가 요구된다.

미국가재는 멕시코 북동부 및 미국 중남부가 원산지로, 전 세계에 유입되어 서식처 파괴와 토착종과의 경쟁 등 많은 문제를 야기하고 있다. 본 조사에서 영산강 6개 지점, 만경강 5개 지점, 섬진강 2개 지점 금강 1개 지점에서 확인되었으며, 주요 수계에서 정착 서식하는 것으로 나타났다. 완주군 서봉리와 함평군 모산리는 20개체 이상이 확인 되어 비교적 큰 개체군을 형성하고 있을 것으로 추정된다. 높은 이동성과 환경적응력으로 보아 확인된 지점에서 타 수계로의 유입 가능성이 매우 높을 것으로 생각되며, 이에 지속적인 확산 현황 파악과 생태계 피해 예방을 위한 지속적 제거 노력이 필요하다.

내시경 역행 췌담관조영술 중 경췌중격절개술은 선택적 담관 삽관이 어려운 환자에서 성공률을 높일 수 있는 방법으로 알려져 있다. 최근 후향적 연구에서는 경췌중격절개술이 침형절개도를 이용한 조임근절개술보다 효과적이며 안전한 것으로 보고되었다. 그러나 이번 증례에서 담석췌장염 환자에서 경췌중격절개술 후 벽내 십이지장 혈종 및 십이지장 폐쇄가 발생하였고 이로 인해 저혈량쇼크 등 치명적인 합병증이 발생하였다. 따라서 급성 췌장염이 동반된 환자에서 내시 경역행췌담관조영술 중 경췌 중격절개술을 시행한 후에는 벽내 십이지장 혈종과 같은 합병증 발생 여부를 주의 깊게 관찰할 필요가 있다고 생각된다.

Symbiotic bacteria are common in insects. Because symbiotic bacteria are known to intimately affect the various aspects of insect host biology, ideally insects can be controlled by manipulating their symbiont. However, the attempts to control insects through their symbiont have been very limited. The paucity of the insect pest control using their symbiont is most likely due to the poor understanding of the symbiotic interactions between host insect and symbiont, which is attributed to the difficulty in cultivation of insect symbionts. However, the recently established bean bug, Riptortus pedestris, symbiotic system provides good opportunities to study insect’s symbiont in molecular level through their cultivable symbionts. Bean bugs acquire genus Burkholderia cells from environment and harbor them as their gut symbionts in the specialized posterior midgut. The genome of the Burkholderia symbiont was sequenced, and the genomic information has been used to generate the genetically manipulated Burkholderia symbiont strains. After orally administering the mutant Burkholderia symbionts into bean bugs for symbiotic association, the bacterial colonization levels in the host gut and host phenotypes were analyzed. As a result, we have identified novel symbiotic factors necessary for establishing successful association with host. Our recent understandings on the bacterial symbiotic factors demonstrate a great possibility to control the bean bug pest using genetically modified Burkholderia symbiont.

The Riptortus (stinkbug) has a specialized symbiotic organ, M4 midgut, to harboring symbiont Burkholderia. M4 midgut is located in abdomen and surrounded with insect hemolymph. Recently our group demonstrated that symbiotic Burkholderia showed different physiology after adapting in M4 gut compare with in vitro cultured Burkholderia. And population of symbiotic Burkholderia in the M4 midgut is regulated by special organ. However, the molecular mechanism to prevent spreading and migrating symbiont bacteria to other host tissues from symbiotic organ is not clear. Therefore, we assumed that symbiont Burkholderia are susceptible to host humoral immunity after established infection in M4 midgut to prevent spreading and migrating into the other host tissues through Riptortus hemolymph. To prove this assuming, we tested the susceptibility and survival rate of symbiont Burkholderia in hemolymph of Riptortus in vitro and in vivo. We also examined the susceptibility of symbiont Burkholderia using purified antimicrobial peptides (AMP), pyrrhocoricin-like, thanatin-like and defensin-like AMPs. Finally, we tested inducing ability for AMPs by systemic infection of symbiotic Burkholderia. Gene expression of purified AMPs was not different after systemic infection of both symbiont and in vitro cultured Burkholderia. Surprisingly, in vitro cultured Burkholderia resisted on bacteria injected hemolymph and purified AMPs but symbiont Burkholderia were highly susceptible in bacteria injected hemolymph and purified AMP. These results suggest that symbiont Burkholderia can't survive in the hemolymph after escaping symbiotic organ. Moreover, humoral immunity of host Riptortus is important to prevent spreading and migrating symbiont Burkholderia into the other host tissue or organ from symbiotic organ.

We investigated the effects of temperature changes on the oxygen consumption rhythm in Japanese eels, Anguilla japonica, using an automatic intermittent flow respirometer (AIFR). The endogenous rhythm of the oxygen consumption rate (OCR) in the eels (n = 18; 44-74 cm, 145-690 g), freshly collected by bag net from estuaries, was nearly synchronous with the tidal pattern of the estuarine collection site. The magnitude of mean OCR (mOCR) of eels showed variable range of 82.2 - 116.5 ml O2 kg-1 ww h-1 under constant conditions. In case of increasing temperature from 25 to 38℃, the OCR of eels exhibited a gradually increasing trend with a rhythmic pattern until 36℃. Above 36℃, the rhythms of the OCR dampened and the OCR decreased rapidly at around 36 - 37℃. The OCR of the eels exhibited the maximum value at 38℃, and then it sharply decreased. The results suggested that the critical thermal maximum (CTM) regarding the endogenous rhythms of the eels was at around 36 - 37℃ when water temperature increased at 0.5℃/14 h following the acclimation at 25℃. In case of decreasing temperature (0.5℃/14 h) from 25 to 0℃, the OCR of the eels displayed a abrupt decrease up to 23℃, and between at 23 and 20℃, there was an agitation which showed a slight increase in the OCR with a duration of 1-2 days. Below 9℃, the OCR rhythm of the eels showed a constant state regardless of temperature decreasing. These results suggest that the Japanese eel has an upper incipient lethal temperature at 36℃, with a lower thermal limit at 9℃. The biochemical aspects of the eels influenced by water temperature need to be further studied.