As part of the 2024 research initiative, “Investigation and Discovery of Prokaryotes in Freshwater Systems,” samples were collected from diverse freshwater habitats, including both water and soil environments. Approximately 2,000 bacterial strains were isolated as single colonies and identified through 16S rRNA gene sequence analysis. Among these, 38 strains shared ≥98.7% 16S rRNA gene sequence similarities with those of known bacterial species not previously reported in Korea. These strains were thus categorized as newly recorded bacterial species in Korea. These 38 bacterial strains displayed significant phylogenetic diversities, spanning 2 phyla, 4 classes, 15 orders, 24 families, and 34 genera. These unrecorded species were classified into the following classes: Actinomycetia (with genera including Microcella, Conyzicola, Curtobacterium, Leucobacter, Microbacterium, Frigoribacterium, Lysinibacter, Streptomyces, Nonomuraea, Actinocorallia, Ruania, and Actinoplanes), Alphaproteobacteria (Paracoccus, Youngimonas, Loktanella, Corticibacterium, Neorhizobium, Onobrychidicola, Ferranicluibacter, Aureimonas, Asticcacaulis, and Novosphingobium), Betaproteobacteria (Rhodoferax, Rugamonas, and Cupriavidus), and Gammaproteobacteria (Rheinheimera, Shewanella, Kosakonia, Leclercia, Hafnia, Yersinia, Pseudomonas, Lysobacter, and Acinetobacter ). Further characterization included assessment of Gram reaction, colony and cell morphology, biochemical properties, and phylogenetic relationships. This report presents detailed phylogenetic and phenotypic characteristics of these bacterial species.

Light is a major external environmental factor that influences the circadian rhythm of photosynthetic organisms and various physiological phenomena, such as growth, maturation, and behavior. The number of light-reaching organisms changes depending on the season and atmospheric conditions, and the intensity and wavelength of light differ depending on the organisms inhabiting the environment. Altered light changes the circadian rhythm of fish, which is controlled by clock genes, such as period 2 (Per2), cryptochrome 1 (Cry1), and melatonin. In this study, we set the zeitgeber time (ZT; 14 light-10 dark, LD) based on the actual sunrise and sunset times and examined Per2 and Cry1 activities, levels of aralkylamine N-acetyltransferase (AANAT), and melatonin in Pholis nebulosa, a drifting seaweed species exposed to irregular light. Per2 and Cry1 levels increased during the daytime and decreased after sunset. The AANAT levels decreased during the daytime and increased during the night. Melatonin concentration was highest around midnight (ZT21, 23:30), but exhibited similar concentrations during the daytime. While the activity of Per2, Cry1, and AANAT levels exhibited a typical circadian rhythm observed in most vertebrates, melatonin concentrations did not show a significant difference between the daytime and nighttime. These findings provide insights into the circadian rhythm patterns of organisms exposed to irregular light environments, such as P. nebulosa, which differ from those of typical fish species.

Pasture formation and management are crucial to avoid yield reduction. This experiment aimed to examine the effects of tall fescue-centered mixed-seeding combinations on yield and vegetation changes in perennial pastures in the central region for two years, from September 2020 to October 2022. The treatments were arranged in three replications in a randomized block design: control (C), tall fescue-based mixture-1 (T-1), and tall fescue-based mixture-2 (T-2). The tall fescue (TF), orchard grass (OG), perennial ryegrass (PRG), Kentucky bluegrass (KBG), and white clover (WC) were used. The emergency rate of grasses (70.0 to 73.3%) did not differ among mixed seeding combinations. Overwintering rates (81.7 to 83.3%) were similar among treatments. The plant height of grasses was similar at each harvest date, with the highest height (86.2 cm) recorded in the second harvest of the first year, followed by that (58.4 cm) in the third harvest of the first year; it was least (38.9 cm) in the fourth harvest of the second year. There was no significant difference in the dry matter yield of grasses among the mixed seeding combination treatments in the first, third, or fourth harvests of the first year (p>0.05). For second-year grasses, dry matter yield was not significantly different in harvest date among the treatments (p>0.05). Based on mixed seeding ratio, orchard grass showed the highest yield at 70% in the C treatment, followed by tall fescue at 80% and 60% in the T-1 and T-2 treatments, respectively, in the first harvest after seeding. There was no significant difference in feed value between treatments (p>0.05), but a significant difference was observed between the third and fourth harvest (p<0.05). Therefore, it indicated that it is important to create perennial pastures in the central region through mixed seeding combinations centered on tall fescue.

The objective of this experiment was to investigate the effect of drip irrigation volume on tomatoes (Solanum lycopersicum L.) grown in a greenhouse using perlite medium. Plants were treated by three different irrigation treatment I0, I25, and I50 (where irrigation volume of I25 and I50 was 25% and 50% higher than I0, having limited or no leaching). Growth characteristics of plants, yield and water use efficiency were measured. The result showed that plant height, leaf length and leaf width were lowest in the I0 treated plants. However, these parameters were not statistically significant differences between the plants that were grown in the I25 and I50 treatment. Soluble solids content, acidity and dry matter of 111th, 132nd, and 143rd days harvested tomato were higher in the plants irrigated with lowest volume (I0) than the higher volume (I25 or I50). In addition, water content was lower in the 111th and 132nd days of harvested tomatoes from the I0 treatment. The number of big-size tomatoes (>180 g) was significantly higher in the I25 irrigated plants. There was no significant difference in the total number of harvested fruits among the treatments. The average fruit weight and total yield of harvested tomatoes were lowest in the I0 treated plants. The water consumption of tomato was not significantly different amongst the treatments but water use efficiency was lowest in the I0 treatment. Principal component analysis revealed that total soluble solid and acidity of tomato showed a positive correlation between each other. These results suggest that I25 was the optimum irrigation treatment for tomato based on its measured growth characteristics, yield and water use efficiency.

This investigation aimed to assess the appetite response changes of olive flounder to starving and re-feeding conditions. Three different feeding groups (2 weeks feeding, fed; 2 weeks starving, starved; and 1 week starving and 1 week feeding, re-fed) were established to examine the changes in appetite-related genes for each group. The weight gain of the fish was highest for the fed group and lowest for the starving group. Based on the daily feed intake (DFI) and cumulative feed intake (CFI), overall food intake was found to increase in the re-fed group more than in the fed group from week 1 to week 2 of the experiment. Hypocretin neuropeptide precursor (HCRT) and galanin receptor 1 (GAL-R1) mRNA expression in the brain of olive flounder were decreased in the starved group. Corticotropin-releasing hormone (CRH) was decreased in all experimental groups, except for the fed group. However, overall leptin concentrations in the plasma did not change across groups. Considering the differences between this study and previous studies on starving and feeding, various factors (except the production and expression mechanisms of appetite-related factors in response to starving) are likely acting on the appetite responses of the fish. In this study, a 1-week re-feeding period induced substantial effects on appetite response when compared to a 2-week feeding period. These findings show that even if re-feeding is performed after starving, the unbalance caused by the re-feeding can affect various physiological changes in fish by feed intake efficiency.

Periodontitis and periimplantitis are caused as a result of dental biofilm formation. This biofilm is composed of multiple species of pathogens. Therefore, controlling biofilm formation is critical for disease prevention. To inhibit biofilm formation, sugars can be used to interrupt lectin-involving interactions between bacteria or between bacteria and a host. In this study, we evaluated the effect of D-Arabinose on biofilm formation of putative periodontal pathogens as well as the quorum sensing activity and whole protein profiles of the pathogens. Crystal violet staining, confocal laser scanning microscopy, and scanning electron microscopy revealed that D-Arabinose inhibited biofilm formation of Porphyromonas gingivalis , Fusobacterium nucleatum , and Tannerella forsythia . D-Arabinose also significantly inhibited the activity of autoinducer 2 of F. nucleatum and the expression of representative bacterial virulence genes. Furthermore, D-Arabinose treatment altered the expression of some bacterial proteins. These results demonstrate that D-Arabinose can be used as an antibiofilm agent for the prevention of periodontal infections.

In recent years, importance of blockchain systems has been grown after success of bitcoin. Distributed consensus algorithm is used to achieve an agreement, which means the same information is recorded in all nodes participating in blockchain network. Various algorithms were suggested to resolve blockchain trilemma, which refers conflict between decentralization, scalability, security. An algorithm based on Byzantine Agreement among Decentralized Agents (BADA) were designed for the same manner, and it used limited committee that enables an efficient consensus among considerable number of nodes. In addition, election of committee based on Proof-of-Nonce guarantees decentralization and security. In spite of such prominence, application of BADA in actual blockchain system requires further researches about performance and essential features affecting on the performance. However, performance assessment committed in real systems takes a long time and costs a great deal of budget. Based on this motivation, we designed and implemented a simulator for measuring performance of BADA. Specifically, we defined a simulation framework including three components named simulator Command Line Interface, transaction generator, BADA nodes. Furthermore, we carried out response surface analysis for revealing latent relationship between performance measure and design parameters. By using obtained response surface models, we could find an optimal configuration of design parameters for achieving a given desirable performance level.

우리나라에서 흰등멸구는 매년 해외로부터 비래, 정착한 후 2~3세대를 경과하며 벼의 생육 및 품질 저하에 영향을 미치는 벼의 중요 해충 중 하나이며, 비래해충의 경우 비래 후 세대에 따른 변화 양상을 정확하게 예측하는 것은 방제시기와 방제수단을 결정하는데 중요하다. 공시충은 2018년 사육실에서(25±2 ℃, 60±5% RH, L:D=16:8) 누대사육하여 사용하였다. 흰등멸구가 국내에 비래 후 3세대까지 세대증식하면서 피해를 주는 것으로 가정하여 1세대와 3세대 간의 발육과 산란 등을 조사하였으며 얻어진 결과를 토대로 생명표를 작성하였다. 약충기간은 1세대와 3세대에서 각각 14.5일, 13.6일, 암컷 성충기간은 각각 17.2일, 11.8일로 나타났으며, 우화율은 98.3%, 85.0%로 조사되었 다. 산란기간은 각각 6.8일, 6.0일이었으며 산란수는 47.5마리, 122.6마리로 세대가 늘어나면서 증가하는 것으로 나타났다. 생명표 분석 결과, 순증가율, 내적자연증가율이 각각 5배, 1.7배 증가한 것으로 나타났다.

최근 지구온난화로 인한 기후변화는 육상 및 해양 생태계에 다양한 영향을 미치고 있다. 농업생태계 역시 이들 생태계에 의존하고 있는 생물 및 인간에게 생물학적, 경제학적, 사회학적으로 다양한 영향을 주고 있다. 기후변화를 쉽게 감지할 수 있는 지표종은 기후변화에 비교적 민감하게 반응을 나타내기 때문에 농업생태계와 같은 경제 사회적 영향을 많이 받는 곳에서 다양하게 활용될 수 있다. 2017년 농업과학원에서는 농업생태계에서 기후변화에 따른 영향을 잘 나타낼 수 있는 식물과 무척처동물 30종을 지표종으로 선정하였다. 30종 중 나비목에 속하는 종으로는 배추흰나비(Pieris rapae), 남방노랑나비(Eurema mandarina), 노랑나비(Colias erate), 호랑나비(Papilio xuthus) 4종이다. 이 연구는 나비 지표종 중 농업생태계에서 가장 풍부하고 확인이 쉬운 배추흰나비를 대상으로 전남, 충북, 경기, 강원지역에서 4월부터 월 1-2회 모니터링을 실시하여 생물계절의 차이를 알아보았다. 조사는 각 지역에서 논과 밭, 산림 등을 포함하는 경로를 선정하여 30분간 이동하면서 좌우 5m내외 출현하는 나비를 조사하는 선 조사법을 실시하였다. 4월 이후부터 조사한 결과 전남에서는 4월초인 14째 주에 이미 많은 수가 관찰된 반면 충북, 경기 등지에선 15째 주 이후 관찰되기 시작하였다. 강원도에서는 6월 중순인 24째부터 관찰되어 위도별 출현 양상의 차이를 나타내었다. 9월말까지 관찰된 생활사 수는 전남에서는 5회, 경기도에서는 4-5회, 충북에서는 4회, 강원에서는 2회로 지역별 차이를 나타내었다. 이러한 결과는 농업생태계에서 흔히 볼 수 있는 배추흰나비가 위도별로 출현시기와 출현횟수를 달리하면서 나타나는 것을 통해 기후변화를 나타낼 수 있는 지표종으로 적절하다고 여겨지며 앞으로도 전국적으로 지속적인 모니터링을 통해 정밀한 출현양상과 미래 분포 변화 모델링 작업에 효과적으로 이용될 수 있는 기초자료를 제공할 수 있을 것으로 여겨진다.