This study was designed to examine the immune response in Korean rockfish during water temperature fluctuation and to elucidate the factors contributing to streptococcal pathogenesis in cultured Korean rockfish, S. schlegeli. We investigated cumulative mortality against Streptococcus iniae (FP5228 strain) infection in the exposed Korean rockfish (39.7±5.8 g) to environmentally relevant temperature (Control, 23℃; High temperature, 28℃ and 23℃ and 28℃ with 12 hours interval exchange, 23↔28℃) for 48 hours. Also, the expression of the mRNA related to the immune response genes (heat shock protein 70, interleukin- 1β, lysozyme g-type and thioredoxin-like 1) were measured in spleen and head kidney by real-time PCR analysis in the exposed fish to thermal stress. In this study, the combined stress with bacterial challenge in fishes exposed to thermal stress lowered the survival rate than that of control (23℃). The cumulative mortality in the group of control, 28℃ and 23↔28℃ was 24%, 24% and 40% (P<0.05), respectively. Also, thermal stress modulated the mRNA level of immune related genes; heat shock protein 70, interleukin-1β, lysozyme g-type and thioredoxin-like 1 in Korean rockfish. The present study indicates that a high and sudden water temperature change affect immune responses and reduce the disease resistance in Korean rockfish.

Diaporthe속은 전세계적으로 중요한 곰팡이 병원균 중 하나이다. 블루베리에 발생하는 병에 관한연구 결과 강원도 춘천시와 고성시의 블루베리 농가에서 5균주의 Diaporthe속을 분리하였다. 이들의 형태적 특징과 분자생물학적 특징을 조사한결과 Diaporthe amygdali, D. eres, D. nobilis, D. phaseolorum, Diaporthe sp.로 동정되었다. 병원성 검정결과 Diaporthe amygdali, D. nobilis, D. phaseolorum 은 상처를 낸 잎에서 5~10mm의 병반을 형성하였다. Diaporthe eres는 상처낸 잎에서 10mm 이상의 병반을 형성하였고 Diaporthe sp.는 상처를 낸 잎에서 5mm 이하의 병반을 형성하였다. 하지만 상처를 내지 않은 잎과 과실에서는 병반을 확인할 수 없었다. 온도 생장특성은 D. eres, D. nobilis, D. phaseolorum, Diaporthe sp.는 25℃에서 D. amygdali는 30℃에서 가장 높은 생장을 보였다. 모든 분리균들은 oxine-copper, benomyl, fluzinam, prochloraz manganese complex에서 80%이상 의 생장저해율을 보였고 captan과 mancozeb는 250ppm, 500ppm에서 dithianon는 500ppm에서 80%이상의 생장저해율을 보였다.

Metarhizium anisopliae (녹강균)는 흰점박이꽃무지에게 질병을 일으키는 곤충 병원성 곰팡이 중 하나이다. 이러한 곰팡이의 병원성은 환경 조건에 의해 영향을 받는다. 녹강균에 대한 흰점박이꽃무지 유충의 민감성을 알기 위해 온도(20℃, 25℃, 30℃), 상대습도 (RH 40%, 50%, 60%, 70%), 톱밥 수분함량 (40%, 50%, 60%)이 다른 사육 조건에서 유충의 치사율을 확인하였다. 녹강균을 처리한 흰점박이꽃무지 유충의 치사율은 온도에 따라 차이가 나타나지 않았으나, 낮은 상대습도 (RH 40%)와 톱밥 수분함량 (40%)에서 유충의 치사율이 높았다. 녹강균에 대한 1령, 2령, 3령 유충의 치사율은 1령에서 가장 높게 나타났다.

In order to deal with various environmental conditions, most living organisms adapt and respond to environmental cues through nucleotide-based second-messenger signaling. Such signals regulate various endogenous factors required for environmental adaptation. In bacteria, there are five kinds of nucleotide-based second messengers, one of which is cyclic di-guanosine monophosphate (c-di-GMP). The molecule is known to regulate many cellular functions including growth, motility, biofilm formation, and virulence. Various environmental cues cause changes in the intracellular concentration of c-di-GMP, depending on the activity of specific c-di-GMP synthases and hydrolases in cells. In this review, we provide insights into nucleotide signaling in bacteria, emphasizing its impact on basic metabolism, its association with other signaling mechanisms, and its role in regulating the virulence of a wide range of bacteria. Moreover, we discuss recent studies suggesting a role for the implicated signaling molecules in bacterial persistence and antibiotic resistance.

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.

Recently, mass mortality of the young abalone Haliotis discus hannai has occurred in commercial seed production farms in Korea. The mortality rate was above 50% of the total cultured organisms in the farm, and the shell length of the moribund organisms was about 3cm. The mortal phenomenon was that the young abalones were weakly scattered on the bottom of the pond from the attachment matrix, or that they could not be moved back to their normal positions. The diseased farmed Pacific abalone had abdominal edema. From the edema in the moribund individuals, three bacterial strains were isolated and all the strains were identified as Vibrio harveyi. These strains were compared with thirty six strains isolated from the fish. The results was that the Vibrio harveyi from the fish were sorted into genogroup A or B; however, the three strains of the diseased farmed Pacific abalone were sorted into genogroup A and the new genogroup C. The identical mortality and pathological symptoms of the naturally infected organisms were reproduced by artificial infection with WA AG-1 and WA CS-5 strains. The LD50 of WA AG-1 and WA CS-5 were each 1.0×103 cfu animal-1 and 1.7×104 cfu animal-1.

Spodoptera exigua (Hübner) is an important pest with wide host range including cabbage, beans, potato etc. We evaluate the virulence of Beauveria bassiana ARP14, B. bassiana GHA, and Isaria japonica with concentration of 1×108 conidia/mL against larval stage of S. exigua using glass scintillation vial. Lethal median time (LT50) of these three fungi was not found significantly different in both fourth and second instar. Infection rate was higher in fourth instar than second instar. Infection rate was highest by B. bassiana ARP14 (84.0%) followed by B. bassiana GHA (63.6%) and I. japonica (45.8%) in fourth instars of S. exigua. Our results suggest that B. bassiana ARP14 can be a new component of integrated pest management of S. exigua.

본 연구는 수입에 의존하고 있는 꽃가루의 안전성을 검토하기 위하여 수행되었다. 수입된 사과 꽃가루에서 동정된 세균은 6종류로 나타났으며, 복숭아 꽃가루에서는 4종 배 꽃가루에서는 5종 키위 꽃가루에서는 5종의 세균이 검출되었다. 이 중 사과와 복숭아에서 분리된 Pantoea ananatis와 Pantoea agglomera는 2007년 검역대상 병으로 고시되었다가 현재는 국내에서 발견되어 보고되어있는 세균이다. 꽃가루에서 분리된 세균 20종을 담배에 접종하여 과민성반응을 조사한 결과 총 9종의 세균이 과민성반응을 일으키는 것으로 나타났다. 아세톤 처리에 따른 세균의 밀도는 대조구와 비교하여 감소하는것으로 나타났다. 아세톤을 처리한 후 발아율을 검정한 결과 사과 꽃가루는 37%에서 13%로 발아율이 떨어졌으며, 복숭아는 39%에서 22%로 떨어졌다. 배 꽃가루 역시 32%에서 19%로 발아율이 떨어졌으며키위의 38%에서 3%로 가장 많이 떨어지는 것으로 나타났다.

Chitin synthase (CHS) is an important enzymatic component, which is required for chitin formation in the cuticles and cuticular linings of other tissues in insects. CHSs have been divided into two classes, class A and B, based on their amino acid sequence similarities and functions. Class A CHS (CHS-A) is specifically expressed in the epidermis and related ectodermal cells such as tracheal cells, while expression of class B CHS (CHS-B) is expressed in gut epithelial cells that produce peritrophic matrices. In this study, we cloned the CHS-A gene from the beet armyworm, Spodoptera exigua. The SeCHS-A mRNA was expressed in all developmental stages and specifically in the epidermis and tracheae tissue by RT-PCR analysis. Expression of SeCHS-A gene was suppressed by feeding double-stranded RNA (dsRNASeCHS-A, 150 ng/larva) in the fifth instar of S. exigua. The suppression of SeCHS-A gene expression significantly induced mortality on pupal stage. Also, larvae fed with dsRNASeCHS-A significantly enhanced pathogenicity of an entomopathogenic fungus, Beauveria bassiana ANU1. These results suggest that the SeCHS-A gene plays an important role in development of S. exigua and dsRNA, which is a specific to SeCHS-A gene, may be applied to effective pest control with B. bassiana.

Entomopathogenic fungi are facultative microorganisms, dwelling in soil or infecting host insects, and some of the genera have been used as biological control agents worldwide. Collection of fungal isolates should be a platform for the development of highly effective resources, thus in this work we constructed a fungal library using a mealworm (Tenebrio molitor) pathogenicity-based fungal collection method and further characterized some isolates with high virulence. A phylogenetic three was generated, and of the isolates 17 isolates’ biological features were characterized, such as morphology, spectrum of virulence, cultural characteristics, thermo-stability of fungi, production of biologically active materials, such as enzymes. This work reports an attractive entomopathogenic fungal library including the information of effective isolates in pest management.