Dietary exposure of the water flea Daphnia galeata to microcystin-LR.

Harmful substances like the cyanotoxin microcystin-leucine-arginine (MC-LR) are commonly found in eutrophic freshwater environments, posing risks to aquatic organisms. The water flea, Daphnia, is a well-established model organism for environmental toxicology research. Nevertheless, there is currently insufficient research on the genes that respond to MC-LR in Daphnia galeata. This study aimed to gain insights into the notable genes that react significantly to MC-LR. In this study, we generated an extensive RNA-Seq sequences isolated from the D. galeata HK strain, Han River in Korea. This strain was nourished with a diet of the green microalga Chlorella vulgaris and treated with pure MC-LR at a concentration of 36 ug/L. The transcriptome profile in response to the MC-LR treatment was obtained and 336 differentially expressed genes were subjected to Gene Ontology (GO) and euKaryotic Orthologous Groups of proteins analyses. GO enrichment analysis showed that chemical stimulus, amino sugar metabolic and catabolic process, oxidative stress, and detoxification were highly enriched, in reverse, proteolysis and fucosylation were underpresented. Detoxification process related genes such as peroxidase-like, chorion, and thyroid peroxidase-like were enriched for eliminating or neutralizing MC_LR from an organism's body. Furthermore, functional protein classification revealed an upregulation of lipid and inorganic ion transport processes, while amino acid and carbohydrate transport processes were found to be downregulated. These findings offer insights into how organisms respond to ecotoxic stimuli, providing valuable information for understanding adaptation or defense pathways.

The complete mitochondrial genome of Labidocera rotunda Mori, 1929 (Copepoda: Calanoida) from Jeju Island, Korea.

We sequenced the complete mitochondrial genome of the copepod Labidocera rotunda (family Pontellidae) collected from Ihotaewoo Beach in Jeju, Korea. The mitochondrial genome was 16,564 bp in length and contained 13 protein-coding genes (PCGs), 22 transfer RNAs, and two ribosomal RNAs. The concatenated phylogenetic tree of L. rotunda was reconstructed using the maximum-likelihood method based on the eight PCGs obtained from eight species of copepods including L. rotunda. The results of the phylogeny analysis showed that L. rotunda was closely related to the family Temoridae among the three families. The complete mitochondrial genome of L. rotunda analyzed for the first time in this study provides insight into the phylogenetic and evolutionary relationship of Labidocera.

Behavioral variation according to feeding organ diversification in glossiphoniid leeches (Phylum: Annelida).

Adaptive radiation is a phenomenon in which various organs are diversified morphologically or functionally as animals adapt to environmental inputs. Leeches exhibit a variety of ingestion behaviors and morphologically diverse ingestion organs. In this study, we investigated the correlation between behavioral pattern and feeding organ structure of leech species. Among them, we found that Alboglossiphonia sp. swallows prey whole using its proboscis, whereas other leeches exhibit typical fluid-sucking behavior. To address whether the different feeding behaviors are intrinsic, we investigated the behavioral patterns and muscle arrangements in the earlier developmental stage of glossiphoniid leeches. Juvenile Glossiphoniidae including the Alboglossiphonia sp. exhibit the fluid ingestion behavior and have the proboscis with the compartmentalized muscle layers. This study provides the characteristics of leeches with specific ingestion behaviors, and a comparison of structural differences that serves as the first evidence of the proboscis diversification.

Meiobenthic nematodes in the assessment of the relative impact of human activities on coastal marine ecosystem.

Ecological quality (EcoQ) status of the Southwest and West coasts of South Korea was evaluated within the "National Investigation of Marine Ecosystems in Korea" in the 2015. In particular, the study dealt to assess the ecological quality of the sediments using free-living nematode communities. A total of 149 species were found in the study area, and Daptonema, Sabatieria, Parodontophora, Sphaerolaimus, and Viscosia were found as dominant genera. Statistical analysis of both environmental and faunal parameters showed an increasing human pressure from Western to Southern coasts. The community structure changed with the environmental features of the study area and allowed the detection of a suite of possible nematode indicators that might be used in monitoring studies. In particular, Dorylaimopsis spp. appeared heavy metal and organic matter resistant taxa, Sabatieria an eutrophication resistant genus, while Paracanthonchus and Neotonchus as heavy metal and organic matter sensitive genera. The principal component analysis (PCA) results showed a clear negative correlation between maturity index and both heavy metal and organic matter increasing, while diversity indices did not appear to be significantly influenced by them. Appling the thresholds of the synthetic nematode indices, the EcoQ of the study area was assessed as poor to moderate.

Upregulation of cellulase activity and mRNA levels by bacterial challenge in the earthworm Eisenia andrei, supporting the involvement of cellulases in innate immunity.

To investigate whether earthworm cellulases contribute to the innate immune system, the responsiveness of cellulase activity and mRNA expression to bacterial challenge was examined by zymography and RNA sequencing. A zymographic analysis revealed that the activity levels of earthworm cellulases were upregulated in response to either a bacterial (Bacillus subtilis or Escherichia coli) or LPS challenge. After the challenge, significant increases in cellulase 1 and cellulase 2 activity levels were observed within 8-16 and 16-24 h, respectively. In the coelomic fluid, both activities were significantly upregulated at 8 h post-injection with B. subtilis. Based on RNA sequencing, cellulase-related mRNAs encoding beta-1,4-endoglucanases were upregulated by 3-fold within 6 h after B. subtilis injection. Our results clearly demonstrated that earthworm cellulases are upregulated by bacterial challenge at the mRNA and protein levels. These results support the view that earthworm cellulases act as inducible humoral effectors of innate immunity against bacterial infection.

New species of Caromiobenella Jeon, Lee & Soh, 2018 (Crustacea, Copepoda, Monstrilloida) from Chuja Island, Korea.

Male monstrilloid copepods belonging to the genus Caromiobenella Jeon, Lee & Soh, 2018 were collected from Chuja Island, Jeju, Korea, using a light trap. This paper describes a new species, Caromiobenellaohtsukai sp. n., based on the display of reduced, knob-like fifth legs on the ventral side of the first urosomal somite. A unique combination of male genitalia features and number of caudal setae further confirms its specificity. Molecular analysis based on two partial gene sequences of mitochondrial cytochrome c oxidase subunit I (mtCOI) and 28S ribosomal RNA (28S rRNA) also supports the designation of this species by showing a relevant divergence from known congeners. Caromiobenellaohtsukai sp. n. is the ninth member of this genus and also the ninth monstrilloid reported from Korea.

First use of molecular evidence to match sexes in the Monstrilloida (Crustacea: Copepoda), and taxonomic implications of the newly recognized and described, partly Maemonstrilla-like females of Monstrillopsis longilobata Lee, Kim & Chang, 2016.

Two forms of the monstrilloid copepod, one represented by males, the other by females, were dominant among the monstrilloids collected while sampling zooplankton with a light trap in southern coastal waters of Korea. Morphological examination revealed that the males are conspecific with the previously reported and rather specialized Korean species Monstrillopsis longilobata Lee, Kim & Chang, 2016, hitherto known only from males that have extremely long genital lappets. The females also show several diagnostic features of Monstrillopsis, such as prominent eyes, bilobed fifth legs with the inner lobe unarmed and reduced, and four urosomal somites. In addition, though, these females are extraordinary among all Monstrilloida in that their ovigerous spines are directed ventrally, not posteriorly as in most species or anteriorly as in those assigned to Maemonstrilla. Genetic divergence analyses based on partial mitochondrial cytochrome c oxidase subunit I, complete Internal Transcribed Spacer 1 (ITS1)-5.8S-ITS2, and partial 28S rRNA revealed little or no genetic divergence between the present males and females, thus demonstrating that they are mutually conspecific. The present report (1) provides the first morphological description of female M. longilobata with the proposal of a revised nomenclature for antennular setal armament; (2) presents the molecular evidence for conspecificity of the males and females; and (3) lists several morphological characteristics that are sexually dimorphic in this species, and thus likely also in other monstrilloids. Matters bearing on the validity of the genera Haemocera, Monstrillopsis, and Maemonstrilla are discussed.