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To understand the lipid metabolism in invertebrate species, identification of the fatty acid (FA) synthesis gene families in invertebrate species is important, since some FA are unable to be synthesized in the organisms by themselves. In the study, to identify the elongation of very long chain fatty acid (Elovl) genes in the marine rotifer Brachionus koreanus , the genome-wide identification and phylogenetic analysis of Elovl genes have been conducted with the expression profile of Elovl genes on the alga Tetraslemis suecica -fed B. koreanus. A total 10 Elovl genes have been identified from the genome of B. koreanus , with conserved HXXHH motif. Synteny analysis showed that tandem duplication event has occurred (Elovl3/6a and b , Elovl9a and b , and Elovl9c and d) in the ancestor. Phylogenetic analysis have clearly revealed that Brachionus spp. has only 2/5 and 3/6 subfamilies, and two novel Elovl classes have been revealed, namely Elovl9 and 10. Transcriptional data showed that the 10 Elovl genes were differently expressed and their expression could be regulated by feeding the alga T. suecica. From fatty acid (FA) profile data of the alga Tetraslemis suecica -fed B. koreanus , we revealed that the marine rotifer B. koreanus may synthesize very long chain fatty acid (VLCFA; >22 carbons) by themselves, as VLCFA was hardly detected in the alga T. suecica. The study provides a better understanding of FA metabolism of the marine rotifer B. koreanus after feeding the T. suecica. Unlabelled Image • Total 10 Elovl genes have been identified from the genome of B. koreanus. • Tandem duplication event has occurred (Elovl3/6a and b , Elovl9a and b , and Elovl9c and d). • Brachionus spp. has only 2/5 and 3/6 subfamilies with two novel Elovl classes Elovl9 and 10. • 10 Elovl genes were differently expressed and their expression could be regulated by feeding the alga T. suecica. • B. koreanus may synthesize very long chain fatty acid (VLCFA; > 22 carbons) by themselves. [ABSTRACT FROM AUTHOR]

Abstract Genome-wide identification of glutathione S -transferase (GST), a major phase II detoxification enzyme, was investigated in four different aquatic model rotifer species Brachionus koreanus , B. plicatilis , B. rotundiformis , and B. calyciflorus. GSTs are ubiquitous antioxidant enzymes that play versatile function including cellular detoxification, stress alleviation, and production of the radical conjugates. Among the four rotifers, B. rotundiformis was found with the least number of GST genes (total 19 GST genes), whereas the other three species shared 23 to 24 GST genes. Among the identified GST genes, belonging to the cytosolic GST superfamily, the expansion of GST sigma classes mainly occurs through tandem duplication, resulting in tandem-arrayed gene clusters on the chromosomes. Overall, the number of genes discovered in this study was highest in the sigma class, zeta, alpha, and omega in descending order. With integration of phylogenetic analysis and xenobiotic-mediated GST mRNA expression patterns along with previous enzymatic activities, the functional divergence among species-specific GST genes was clearly observed. This study covers full identification of GST classes in three marine rotifer and one fresh-water rotifer species and their important role in marine environmental ecotoxicology. Graphical abstract Unlabelled Image Highlights • B. rotundiformis has total 19 GST genes but the other three species shared 23 to 24 GST genes. • The expansion of GST sigma classes mainly occurs through tandem duplication. • The number of GST genes was highest in the sigma class, zeta, alpha, and omega in descending order. • The functional divergence among species-specific GST genes was clearly observed on xenobiotic-mediated GST mRNA expression patterns. [ABSTRACT FROM AUTHOR]

The mitogen-activated protein kinases (MAPKs) family is known to mediate various biological processes in response to diverse environmental pollutants. Although MAPKs are well characterized and studied in vertebrates, in invertebrates the cross-reactivities of MAPKs antibodies were not clearly known in response to environmental pollutants due to limited information of antibody epitopes with material resources for invertebrates. In this paper, we performed phylogenetic analysis of MAPKs genes in the marine rotifer Brachionus koreanus and the copepods Paracyclopina nana and Tigriopus japonicus . Also in rotifer and copepods, several studies of Western blot of MAPK signaling pathways were shown in response to environmental pollutants, including multi-walled carbon nanotubes (MWCNTs), water-accommodated fractions (WAFs) of crude oil, and microplastics. This paper will provide a better understanding of the underlying mechanistic scenario in terms of cross-reactivities of mammalian antibodies in rotifer and copepod. [ABSTRACT FROM AUTHOR]

Whole transcriptomes of the rotifer Brachionus plicatilis were analyzed using an Illumina sequencer. De novo assembly was performed with 49,122,780 raw reads using Trinity software. Among the assembled 42,820 contigs, 27,437 putative open reading frame contigs were identified (average length 1235 bp; N50 = 1707 bp). Functional gene annotation with Gene Ontology and InterProScan, in addition to Kyoto Encyclopedia of Genes and Genomes pathway analysis, highlighted the metabolism of xenobiotics by cytochrome P450 (CYP). In addition, 28 CYP genes were identified, and their transcriptional responses to benzo[ α ]pyrene (B[ α ]P) were investigated. Most of the CYPs were significantly upregulated or downregulated ( P < 0.05) in response to B[ α ]P, suggesting that Bp-CYP genes play a crucial role in detoxification mechanisms in response to xenobiotics. This study sheds light on the molecular defense mechanisms of the rotifer B. plicatilis in response to exposure to various chemicals. [ABSTRACT FROM AUTHOR]

2,2′,4,4′-Tetrabromodiphenyl ether (BDE-47) is widely dispersed endocrine disrupting chemicals (EDCs) in the aquatic ecosystem. Due to its devastating effect on marine organisms and insufficient database on toxicology, we investigated the adverse effects of BDE-47 on life parameters and antioxidant defense system following the reactive oxygen species (ROS) production in the monogonont rotifer Brachionus koreanus . In B. koreanus , the reduction in life cycle, fecundity, and population growth were observed in response to BDE-47. 50 μg/L BDE-47 significantly reduced ( P < 0.05) life expectancy and net reproductive rate. In response to 10–50 μg/L BDE-47 exposure, the oxidative stress was elicited via the generation of ROS, while the antioxidant related enzymes (e.g. glutathione S -transferase [GST] and glutathione reductase [GR]) have demonstrated significant activity levels ( P < 0.05) to further alleviate the oxidative stress in a concentration dependent manner. Furthermore, transcript profiles of antioxidant function ( GST-A , -O , and - S1–S8 )-related genes have shown the significant increase over 24 h in response to BDE-47 (0, 10, 25, and 50 μg/L). As for MAPK signaling pathway analysis, up-regulation of their activities was observed at 25 μg/L BDE-47 but their activities have reduced at adult NOEC concentration of 50 μg/L. This study provides a better understanding of the effects of BDE-47 on life parameters, molecular defense system, and activation of MAPK signaling pathway against generated oxidants in the rotifer. [ABSTRACT FROM AUTHOR]

Triclosan (TCS) and Triclocarban (TCC) are used as antimicrobial agents and have been widely dispersed and detected in the marine environment. However, the toxicities of TCS and TCC have been poorly investigated in marine invertebrates. In this study, the effects of TCS and TCC on mortality, population growth, lifespan, and fecundity were examined in the monogonont rotifer ( Brachionus koreanus ) using cellular ROS levels, GST enzymatic activity, and gene expression of defensomes. The median lethal concentration (LC50) of TCS (393.1 μg/L) and TCC (388.1 μg/L) was also determined in the same species. In TCS- and TCC-exposed B. koreanus , growth retardation and reduced fecundity were observed and were shown to have a potentially deleterious effect on the life cycle of B. koreanus . In addition, time-dependent increases in ROS content (%) and GST enzymatic activity were shown in response to TCS and TCC exposure. Additionally, transcript levels of detoxification proteins (e.g., CYP s), antioxidant proteins (e.g., GST-sigma , Cu / ZnSOD , CAT ), and heat shock proteins ( Hsp s) were modulated in response to TCS and TCC exposure over a 24 h period. Our results indicate that TCS and TCC induce oxidative stress and transcriptional regulation of detoxification, antioxidant, and heat shock proteins, resulting in changes in lifespan and fecundity. [ABSTRACT FROM AUTHOR]

ABSTRACT Although triphenyltin (TPT) compounds are ubiquitous pollutants in urbanised coastal environments in Asian regions, their toxicities to marine organisms are still poorly known. This study was designed to investigate the toxicity of triphenyltin chloride (TPTCl) on the rotifer Brachionus koreanus across different levels of biological organisation. Firstly, we concurrently performed a 24 h static-acute toxicity test and a 6-day semi-static multigenerational life-cycle test using the rotifer. Our results demonstrated that the 24-h median lethal concentration of TPTCl for the rotifer was 29.6 μg/L and the 6-day median effect concentration, based on the population growth inhibition, was 3.31 μg/L. Secondly, we examined the expression of 12 heat shock protein ( hsp) genes, four glutathione S-transferase ( GST) genes, one retinoid X receptor ( RXR) gene and 13 cytochrome P450 ( CYP) genes in the rotifers after exposure to 20 µg/L TPTCl for 24 h. Among these studied genes, hsp90α2, GST-O and CYP3045C1 were the most significantly up-regulated genes with a relative expression level up to 32.9, 4.4 and 62.6 folds, respectively. The expression of these three genes in the rotifers showed an increasing trend in the first few hours of TPTCl exposure, peaked at 3 h ( hsp90α2 and GST-O) and 12 h ( CYP3045C1) respectively, and then gradually returned to a lower level at 24 h. Such up-regulations of hsp and GST genes probably offer cellular protection against the TPT-mediated oxidative stress while the accelerated induction of CYP genes possibly facilitates the detoxification of this toxicant in the rotifer. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 13-23, 2016. [ABSTRACT FROM AUTHOR]

This study compared in vivo acute toxicities of nine engineered nano metal oxides to the marine diatom Skeletonema costatum and rotifer Brachionus koreanus. The sequence of their toxicities to S. costatum , based on growth inhibition, was: nano zinc oxide (nZnO) > nTiO 2 (rutile) > nMgO > Annealed nMgO > nTiO 2 (anatase) > γ-nAl 2 O 3 > nIn 2 O 3 > α-nAl 2 O 3 > nSnO 2. Similarly, nZnO was also the most toxic to B. koreanus , but the other nano metal oxides were non-lethal. nMgO and nZnO were confirmed to trigger reactive oxygen species (ROS) mediated toxicity to the two marine organisms, while nTiO 2 (both anatase and rutile forms) likely induced oxidative stress as shown by their acellular ROS production. nZnO may also cause damage in the endocrine system of B. koreanus , as indicated by the increased transcription of retinoid X receptor. Annealed nMgO reduces its toxicity via removal of O 2 – and impurities from its surface. • nZnO was the most toxic to S. costatum while nSnO 2 was the least toxic. • nZnO was the most toxic to B. koreanus , while other nanoparticles were non-lethal. • nMgO and nZnO showed ROS mediated toxicity to the two marine organisms. • nTiO 2 (both forms) might induce oxidative stress through acellular ROS production. • Annealed nMgO reduced its toxicity via removal of O 2 – and impurities from surface. [ABSTRACT FROM AUTHOR]

• The total length of the assembled genome was 106.9 Mb with an N50 value of 1.15 Mb. • A total of 20,154 genes were annotated after manual curation. • 28 B. plicatilis -CYPs were apparently separated into 2, 3, 4, mitochondrial (MT), and 46 clans. • Most B. plicatilis CYP s were significantly modulated (P < 0.05) in response to chlorpyrifos and 2-ethyl-phenanthrene. • XNR response element sequences were identified in the 5 kb upstream of promoter regions of 28 CYP s. Brachionus spp. (Rotifera: Monogononta) are globally distributed in aquatic environments and play important roles in the aquatic ecosystem. The marine monogonont rotifer Brachionus plicatilis is considered a suitable model organism for ecology, evolution, and ecotoxicology. In this study, we assembled and characterized the B. plicatilis genome. The total length of the assembled genome was 106.9 Mb and the number of final scaffolds was 716 with an N50 value of 1.15 Mb and a GC content of 26.75%. A total of 20,154 genes were annotated after manual curation. To demonstrate the use of whole genome data, we targeted one of the main detoxifying enzyme of phase I detoxification system and identified in a total of 28 cytochrome P450 s (CYPs). Based on the phylogenetic analysis using the maximum likelihood, 28 B. plicatilis -CYPs were apparently separated into five different clans, namely, 2, 3, 4, mitochondrial (MT), and 46 clans. To better understand the CYPs-mediated xenobiotic detoxification, we measured the mRNA expression levels of 28 B. plicatilis CYP s in response to chlorpyrifos and 2-ethyl-phenanthrene. Most B. plicatilis CYP s were significantly modulated (P < 0.05) in response to chlorpyrifos and 2-ethyl-phenanthrene. In addition, xenobiotic-sensing nuclear receptor (XNR) response element sequences were identified in the 5 kb upstream of promoter regions of 28 CYP s from the genome of B. plicatilis , indicating that these XNR can be associated with detoxification of xenobiotics. Overall, the assembled B. plicatilis genome presented here will be a useful resource for a better understanding the molecular ecotoxicology in the view of molecular mechanisms underlying toxicological responses, particularly on xenobiotic detoxification in this species. [ABSTRACT FROM AUTHOR]

Highlights • Low concentrations of two pharmaceuticals APAP and OTC elicited oxidative stress through the generation of ROS.. • Low concentrations of two pharmaceuticals APAP and OTC increased glutathione S-transferase activity. • APAP and OTC have no-observed effect in in-vivo population growth. • CYP3045A2 and GSTs1 , GSTs4 , and GSTo1 were responsible in detoxification of APAP and OTC. • These led no significant changes in the population growth and undetermined NOEC in rotifer. Abstract To investigate the adverse effect of two widely used pharmaceuticals, paracetamol (acetaminophen [APAP]) and oxytetracycline (OTC) on the marine rotifer Brachionus rotundiformis (B. rotundiformis), the animals were exposed to various environmentally-relevant concentrations. Up to date, acetaminophen and oxytetracycline have been considered as toxic, if used above threshold concentration, i.e. overdosed. However, this study demonstrated these two pharmaceuticals even at low concentration (i.e. , μg/L scale) elicited oxidative stress through the generation of reactive oxygen species (ROS) along with the increased glutathione S -transferase activity, despite no-observed effect in in-vivo population growth. To validate the adverse effects of the two pharmaceuticals at relatively low concentrations, mRNA expression analysis was performed of the entire set of genes encoding 26 cytochrome P450s (CYPs) of phase I and 19 glutathione S -transferases (GSTs) of phase II of the rotifer B. rotundiformis. The mRNA expression analysis suggested specific genes CYP3045A2 and GSTσ1 , GSTσ4 , and GSTω1 take part in detoxification of APAP and OTC, resulting in no significant changes in the population growth and undetermined no observed effect concentration (NOEC) in the marine rotifer B. rotundiformis. [ABSTRACT FROM AUTHOR]

Abstracts To understand the adverse outcome in response to bisphenol A and its analogs bisphenol F and S (BPA, BPF, and BPS), we examined acute toxicity, life parameter, and defensome in the marine rotifer Brachionus koreanus . Among the bisphenol analogs, BPA showed the highest acute toxicity and then BPF and BPS, accordingly in the view of descending magnitude of toxicity. In life parameters including life span and reproduction, BPA, BPF, and BPS were found to cause adverse effect. Both intracellular ROS level and GST activity were significantly increased ( P <  0.05) in response to each dosage of bisphenol analogs exposures. In response to bisphenol analogs, defensomes of phase I, II, and III detoxification mechanism demonstrated inverse relationship between the lipophilicity of bisphenol analogs and the expression patterns of defensomes. BPA and BPF were found to have significant modulation ( P <  0.05) in the expression of cytochrome P450 ( CYP ) and GST genes. In phase III, BPS with comparatively lower lipophilicity demonstrated highly diversified expressional pattern, suggesting that BPS is likely caused less toxicity compared to BPA and BPF. In this study, via phase I, II, and III detoxification mechanism, bisphenol A and its analogs F and S demonstrated specific detoxification mechanism in rotifer. [ABSTRACT FROM AUTHOR]

Salinity is a critical key abiotic factor affecting biological processes such as lipid metabolism, yet the relationship between salinity and lipid metabolism has not been studied in the rotifer. To understand the effects of salinity on the monogonont rotifer B. koreanus , we examined high saline (25 and 35 psu) conditions compared to the control (15 psu). In vivo life cycle parameters (e.g. cumulative offspring and life span) were observed in response to 25 and 35 psu compared to 15 psu. In addition, to investigate whether high salinity induces oxidative stress, the level of reactive oxygen species (ROS) and glutathione S -transferase activity (GST) were measured in a salinity- (15, 25, and 35 psu; 24 h) and time-dependent manner (3, 6, 12, 24 h; 35 psu). Furthermore composition of fatty acid (FA) and lipid metabolism-related genes (e.g. elongases and desaturases ) were examined in response to different salinity conditions. As a result, retardation in cumulative offspring and significant increase in life span were demonstrated in the 35 psu treatment group compared to the control (15 psu). Furthermore, ROS level and GST activity have both demonstrated a significant increase ( P < 0.05) in the 35 psu treatment. In general, the quantity of FA and mRNA expression of the lipid metabolism-related genes was significantly decreased ( P < 0.05) in response to high saline condition with exceptions for both GST - S4 and S5 demonstrated a significant increase in their mRNA expression. This study demonstrates that high salinity induces oxidative stress, leading to a negative impact on lipid metabolism in the monogonont rotifer, B. koreanus . [ABSTRACT FROM AUTHOR]

• Adverse effects of SSRIs on the survival and reproduction were observed in Brachionus koreanus. • Oxidative stress and antioxdant system were induced in response to SSRIs. • Significant modulation of antioxidant enzymatic activities were observed in response to SSRIs in Brachionus koreanus. • Up-regulation of antioxidant genes enhanced life parameters in SSRI-exposed Brachionus koreanus. To understand effects of two widely used antidepressant on the antioxidant defense mechanism in the marine rotifer Brachionus koreanus , we assessed acute toxicity and measured population growth, reactive oxygen species (ROS) levels, glutathione (GSH) levels, and antioxidant enzymatic activities (GST, GR, and SOD) in response to fluoxetine hydrochloride (FLX) and sertraline hydrochloride (SER). The no observed effect concentration-24 h of fluoxetine and sertraline were 1000 μg/L and 450 μg/L, respectively, whereas the median lethal concentration (LC50)-24 h of fluoxetine and sertraline were 1560 μg/L and 507 μg/L, respectively. Both fluoxetine and sertraline caused significant reduction (P < 0.05) in the population growth rate indicating that both antidepressants have a potential adverse effect on life cycle parameters of B. koreanus. The intracellular ROS level and GSH level were significantly modulated (P < 0.05) in response to fluoxetine and sertraline. In addition, antioxidant enzymatic activities have shown significant modulation (P < 0.05) in response to FLX and SER in B. koreanus. Furthermore, transcriptional profiles of antioxidant genes (GSTs, SODs, and GR) have shown modulation in response to FLX compared to SER-exposed B. koreanus. Our results indicate that fluoxetine and sertraline induce oxidative stress, leading to reduction in the population density and modulation of antioxidant defense mechanism in the marine rotifer B. koreanus. [ABSTRACT FROM AUTHOR]