붉은불개미는 세계 100대 침입외래 해충 중의 하나로 우리나라에서는 관리 해충으로 1996년도에 지정되었다. 2017년 9월28일 부산항 감만 부두에서 국내 최초로 발견된 후, 2018년에 부산항, 평택항 과 인천항에서 발견이 되었고, 9월18일에 대구의 아파트 공사장에서 내륙에서는 처음으로 발견이 되었다. 대구에서 발견된 붉은불개미도 아파트 건설을 위하여 중국에서 수입한 석재에 혼합되어 수입된 토양과 식물체와 같이 혼입된 것으로 추측이 된다. 그러므로, 현재까지 국내에서 붉은불개미가 번식을 하여 토착화되었다는 증거는 없다. 현재까지 붉은불개미에 대한 종 판명은 전문가에 의한 형태적인 분류가 대부분이다. 그래서, 붉은불개미에 대한 확증을 위해서는 채집된 개체를 검역기관으로 이송하여 분자진단을 실시해야 하므로, 최소 이틀의 시간이 필요하다. 현재 항원항체 반응을 이용한 붉은불개미 진단 키트가 해외에서 개발되어 판매되고 있지만, 낮은 민감도로 최소 3~5개의 충체가 필요한 실정이다. 현재 판매되고 있는 진단키트가 가지는 문제점은 이를 대신할 새로운 키트의 개발이 필요함을 보여주고 있다. 신속한 붉은불개미의 검역현장에서 진단을 가능하게하기 위한 노력 중의 하나로 우리는 붉은불개미의 복부에서 발현되는 유전체에 대한 연구를 수행하였다. 본 발표에서는 그에 대한 현재까지의 연구 진행과 결과를 설명하도록 하겠다. (본 연구는 농림축산 검역본부의 연구비 지원으로 이루어졌음).

Ticks are obligatory ectoparasites of many vertebrates and transmit pathogens causing diseases such as Heartland virus and Ehrlichiosis. The lone star tick, Ambloyomma americanum L., is the primary vector of Ehrlichia chaffeensis, which causes human monocytic Ehrlichiosis. We aimed to investigate the genomic levels of gene regulation in the processes of acquiring the pathogen and of immune to pathogen. We designed six experimental groups: E. chaffeensis positive and negative groups of males and females, and pathogen free male and female ticks. Illumine HiSeq 2500 sequenced six libraries with 100-cycle single direction. Raw sequence reads (more than 209 million) were trimmed and filtered based on minimum quality score (Q-value >30) and size (> 40nt) for de novo assembly. Assembly using Trinity pipeline produced 140,574 contigs from trimmed and filtered sequence reads (about 117 million reads, 56% of raw data). For quality control of the de novo assembly of transcripts, we filtered out the sequences for mitochondrial, E. chaffeensis, and transposable elements sequences, and tested for contig redundancy and gap separations of the assembled sequences. RSEM and edgeR analyses of 61,802 contigs for identifying differentially expressed genes were followed by Blast2GO analyses for annotations of contigs and enriched-gene ontology (GO) term analyses in pairwise comparisons of the libraries. Further investigation of major groups of genes induced by pathogen would provide better understanding of pathogen-vector interaction, which will allow us to prevent of pathogen transmission by interrupting interaction between pathogen and ticks.

Chironomus riparius, a non-biting midge (Chironomidae, Diptera), is extensively used in aquatic ecotoxicological studies for assessing acute and sub-lethal toxicities of contaminated sediments and for water monitoring due to their widespread occurrence, short life-cycle, easy to be reared in the laboratory, physiological tolerance to various environmental conditions. To date, the endpoints used for monitoring such effects in C. riparius are based on a small number of specific biomarkers and measurements of organism level effects, such as survival and reproduction. Genomic-based techniques based on expression analysis of genes are important tools for investigating molecular level effects caused by exposure to environmental pollutants, which will provide the ability to detect mechanisms of action and subsequent adverse cellular level effects and associated with different types of toxicity. As a pre-requisite for genomic based ecotoxicological studies knowledge on the C. riparius transcriptome is important but despite its ecotoxicological importance, no large scale transcriptome analysis of C. riparius has been done so far. Therefore, to gain a better understanding of C. riparius transcriptome, we recently developed Expressed Sequence Tags (ESTs) sequencing project on C. riparius larvae using 454 pyrosequencing. Sequencing runs, using normalized cDNA collections from fourth instar larvae, yielded 20,020 expressed sequence tags, which were assembled into 8,565 contigs and 11,455 singletons. Sequence analysis was performed by BlastX search against the National Center for Biotechnology Information (NCBI) nucleotide (nr) and uniprot protein database. Based on the gene ontology classifications, 24% (E-value ≤1-5) of the sequences had known gene functions, 24% had unknown functions and 52% of sequences did not match any known sequences in the existing database. Sequence comparison revealed 81% of the genes have homologous genes among other insects belonging to the order Diptera providing tools for comparative genome analyses. Targeted searches using these annotations identified genes associated with essential metabolic pathways, signaling pathways, detoxification of toxic metabolites and stress response genes of ecotoxicological interest. The results obtained from this study would eventually make ecotoxicogenomics possible in a truly environmentally relevant species, C. riparius. Various C. riparius ecotoxicity studies using stress response genes developed from 454 sequencing will be presented in the conference.

The rice blast disease caused by Magnaporthe oryzae (M. oryzae) is one of the most serious diseases of cultivated rice (Oryza sativa L.) in most rice-growing regions of the world. In order to investigate early responsible genes in rice in response to M. oryzae, we analyzed transcriptomics analysis using 300 K tilling microarray chip. The quality of RNA samples was initially validated by 4 defense related genes and phytoalexins measurement using RT-PCR and HPLC, respectively, which are well known defense markers. We determined that accumulation of 608 genes showed statistically significant changes in the level of transcription (>2 fold change, P<0.05). Among them, 261 genes were more up-regulated in incompatible interaction than that of compatible one. We further analyzed GO enrichment analysis of the 41 and 231 which were 2 fold up-regulated genes at 12h and 48h in incompatible interaction, respectively, using Rice Oligo nucleotide Array Database (http://ricearray.org). Furthermore, MapMan analysis (http://mapman.gabipd.org/) revealed that 21 and 85 genes including 18 receptor-like genes which were more induced in incompatible interaction compared to compatible interaction were found to be involved in biotic stress. Thus, this study suggests that early inducible genes including receptor-like protein kinases in incompatible interaction may play a key role in disease resistance against M. oryzae attacks.