Leptin, a hormone secreted by peripheral adipose tissues, regulates the appetite in animals. Recently, evidence has shown that leptin also plays roles in behavioral response in addition to controlling appetite. In this study, we examined the potential function of leptin on non-appetite behaviors in zebrafish model. By using genome editing tool of Transcription activator-like effector nuclease (TALEN), we successfully knocked out leptin a (lepa) gene by deleting 4 bp within coding region to create a premature-translation stop. Morphological and appetite analysis showed the lepa KO fish display a phenotype with obese, good appetite and elevation of Agouti-related peptide (AgRP) and Ghrelin hormones, consistent with the canonical function of leptin in controlling food intake. By multiple behavior endpoint analyses, including novel tank, mirror biting, predator avoidance, social interaction, shoaling, circadian rhythm, and color preference assay, we found the lepa KO fish display an anxiogenic phenotype showing hyperactivity with rapid swimming, less freezing time, less fear to predator, loose shoaling area forming, and circadian rhythm and color preference dysregulations. Using biochemical assays, melatonin, norepinephrine, acetylcholine and serotonin levels in the brain were found to be significantly reduced in lepa KO fish, while the levels of dopamine, glycine and cortisol in the brain were significantly elevated. In addition, the brain ROS level was elevated, and the anti-oxidative enzyme catalase level was reduced. Taken together, by performing loss-of-function multiple behavior endpoint testing and biochemical analysis, we provide strong evidence for a critical role of lepa gene in modulating anxiety, aggression, fear, and circadian rhythm behaviors in zebrafish for the first time.

Magnetic Nanoparticles (MNPs) are widely being investigated as novel promising multifunctional agents, specifically in the fields of development for theranostics, electronics, waste water treatment, cosmetics, and energy storage devices. Unique, superior, and indispensable properties of magnetization, heat transfer, and melting temperature make MNPs emerge in the field of therapeutics in future healthcare industries. However, MNPs ecotoxicity as well as behavioral toxicity is still unexplored. Ecotoxicity analysis may assist investigate MNPs uptake mechanism and its influence on bioavailability under a given set of environmental factors, which can be followed to investigate the biomagnification of MNPs in the environment and health risk possessed by them in an ecological food chain. In this study, we attempted to determine the behavioral changes in zebrafishes at low (1 ppm) or high (10 ppm) concentration levels of Fe3O4 MNPs. The synthesized Fe3O4 MNPs sized at 15 nm were characterized by the transmission electron microscope (TEM), the superconducting quantum interference device (SQUID) magnetometer, and the multiple behavior tests for novel tank, mirror biting, conspecific social interaction, shoaling, circadian rhythm, and short-term memory of zebrafish under MNPs chronic exposure were demonstrated. Low concentration MNP exposure did not trigger alteration for majority behavioral and biochemical tests in adult zebrafish. However, tight shoal groups were observed at a high concentration of MNPs exposure along with a modest reduction in fish exploratory behavior and a significant reduction in conspecific social interaction behavior. By using enzyme-linked immunosorbent assays (ELISA), we found a high dose of MNPs exposure significantly elevated cortisol, acetylcholine, and catalase levels while reducing serotonin, acetylcholine esterase, and dopamine levels in the brain. Our data demonstrates chronic MNPs exposure at an environmentally-relevant dose is relatively safe by supporting evidence from an array of behavioral and biochemical tests. This combinational approach using behavioral and biochemical tests would be helpful for understanding the MNPs association with anticipated colloids and particles effecting bioavailability and uptake into cells and organisms.

In this study, the complete mitogenome sequence of sea slug, Chromodoris annae (Mollusca: Chromodorididae), has been decoded for the first time by genome skimming method. The overall base composition of C. annae mitogenome is 30.6% for A, 14.5% for C, 17.8% for G, and 37.2% for T, and has GC content of 32.2%. The assembled mitogenome, consisting of 14,260 bp, has unique 13 protein-coding genes (PCGs), 22 transfer RNAs, and two ribosomal RNAs genes. The C. annae has the common mitogenome gene organization and feature of Chromodorididae. The complete mitogenome of C. annae provides essential and important DNA molecular data for further phylogenetic and evolutionary analysis for sea slugs.

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In this study, the complete mitogenome sequence of nereid worm, Neanthes glandicincta (Annelida: Nereididae), has been decoded for the first time by PCR amplification and Sanger sequencing methods. The overall base composition of N. glandicincta mitogenome is 31.5% for A, 22.2% for C, 14.5% for G and 31.7% for T, and has GC content of 36.7%. The assembled mitogenome, consisting of 16,126 bp, has unique 13 protein-coding genes (PCGs), 22 transfer RNAs and 2 ribosomal RNAs genes. The complete mitogenome of N. glandicincta shows 65% identities to Namalycastis abiuma. All PCGs, tRNA and rRNA genes were encoded on H-strand. The potential D-loop is 1625 bp in length and located between tRNA-Gly and tRNA-Met. The complete mitogenome provides essential and important DNA molecular data for further phylogenetic and evolutionary analysis for Annelida.

In this study, the complete mitogenome sequence of nereid worm, Namalycastis abiuma (Annelida: Nereididae), has been decoded for the first time by low coverage genome sequencing method. The overall base composition of N. abiuma mitogenome is 30.8% for A, 24.6% for C, 14.0% for G and 30.6% for T, and has GC content of 38.6%. The assembled mitogenome, consisting of 15 265 bp, has unique 13 protein-coding genes (PCGs), 21 transfer RNAs and two ribosomal RNA genes. The complete mitogenome of N. abiuma shows 69% identities to Tylorrhynchus heterochaetus . All PCGs, tRNA and rRNA genes were encoded on H-strand. The potential D-loop is 827 bp in length and located between tRNA-Gly and tRNA-Trp. The complete mitogenome provides essential and important DNA molecular data for further phylogenetic and evolutionary analysis for Annelida.

Green algae, Chlorella ellipsoidea, Haematococcus pluvialis and Aegagropila linnaei (Phylum Chlorophyta) were simultaneously decoded by a genomic skimming approach within 18-5.8-28S rRNA region. Whole genomic DNAs were isolated from green algae and directly subjected to low coverage genome skimming sequencing. After de novo assembly and mapping, the size of complete 18-5.8-28S rRNA repeated units for three green algae were ranged from 5785 to 6028 bp, which showed high nucleotide diversity (π is around 0.5–0.6) within ITS1 and ITS2 (Internal Transcribed Spacer) regions. Previously, the evolutional diversity of algae has been difficult to decode due to the inability design universal primers that amplify specific marker genes across diverse algal species. In this study, our method provided a rapid and universal approach to decode the 18-5.8-28S rRNA repeat unit in three green algal species. In addition, the completely sequenced 18-5.8-28S rRNA repeated units provided a solid nuclear marker for phylogenetic and evolutionary analysis for green algae for the first time.

In this study, the complete mitogenome sequence of sea hares, Dolabella auricularia (Mollusca: Aplysiidae), has been decoded for the first time by low coverage whole genome sequencing method. The overall base composition of D. auricularia mitogenome is 31.5% for A, 14.0% for C, 16.4% for G, and 38.0% for T, and has low GC content of 30.5%. The assembled mitogenome, consisting of 14,598 bp, has unique 13 protein-coding genes (PCGs), 22 transfer RNAs, and two ribosomal RNAs genes. The D. auricularia has the common mitogenome gene organization and feature of Aplysiidae. The complete mitogenome of D. auricularia provides essential and important DNA molecular data for further phylogenetic and evolutionary analysis for Aplysiidae.