Search

The triangle barnacle Balanus trigonus Darwin, 1854, a cosmopolitan inhabitant of tropical and warm temperate seas, is a member of robust system for the study of evolutionary processes in the intertidal zone. The first mitochondrial genome of B. trigonus is presented. The complete mitochondrial genome of B. trigonus is a circular molecule of 15,560 bp, which encodes 13 protein-coding genes (PCGs), 2 rRNA genes, and 22 tRNA genes. In comparison within Sessilia, the arrangement of the mitochondrial genome of B. trigonus is more similar to Megabalanus spp. than the congener Balanus balanus, which share a same inversion of a large gene block (P-nd4L-nd4-H-nd5-F). Phylogenetic analysis based on mitochondrial PCGs reveals that B. trigonus clusters with Acasta Sulcata (BP = 100), then grouped with Megabalanus volcano and Megabalanus ajax with high support (BP = 90). In further, more data and research are needed to reveal the phylogeny within Cirripedia.

The complete mitochondrial genome of Tetraclita japonica (Crustacea: Maxillopoda: Sessilia) from Zhejiang (China) was presented (T. japonica ZJ). The genome is a circular molecule of 15,192 bp, all non-coding regions are 694 bp in length, and the longest one (307 bp) is located between 12S rRNA and trnK. Phylogenetic analysis based on mitochondrial PCGs shows that T. japonica ZJ clusters with T. japonica CN, and they grouped with T. japonica (BP = 100), then grouped with Tesseropora rosea, Tetraclita serrata, Tetraclita rufotincta, Epopella plicata, and Tetraclitella divisa successively . The phylogenetic tree indicated that the Balanidae and Archaeobalanidae are polyphyletic, while the Chthamalidae is monophyletic. The result can help us to understand the phylogenetic history within Sessilia.

Acorn barnacles are important model species in researches on intertidal ecology, larval development and biofouling. At present, with the development of mitochondrial genomics, it is helpful to understand the phylogenetic relationship from the mitogenomic level. The complete mitochondrial genome of Chthamalus challengeri was presented. The genome is a circular molecule of 15 358 bp. Compared with other species in Balanomorpha, the non-coding region is longer, while the length of the genes is similar to the other species. The overall A+T content of the mitochondrial genome of C. challengeri is 70.5%. There are variations of initiation and stop codons in the known Balanomorpha mitochondrial genomes. The C. challengeri and C. antennatus within the same genus share the identical gene arrangement. However, the gene arrangement of different genera in Chthamalidae is different, as there is a translocation between two tRNA genes and an inversion involving a large gene block. In particular, both srRNA and lrRNA of the two species in Chthamalus are encoded in the heavy strand, differing from the former Balanomorpha species. The topology and gene arrangement in Chthamalidae support each other. Phylogenetic analysis indicates that the Chthamalidae is monophyletic, while the Balanidae and Archaeobalanidae are polyphyletic.

Cirripedia is a lower crustacean that has an invaluable place in several aspects of intertidal ecology and anti-fouling research. In this study, we present the first mitochondrial genome of Chthamalus malayensis. The complete mitochondrial genome of C. malayensis is a circular molecule of 15,230 bp. In comparison to the pancrustacean ground pattern, the mitochondrial genome of C. malayensis has a deletion of the trnC gene. Phylogenetic analysis based on mitochondrial protein-coding genes showed that C. malayensis clusters with C. antennatus (BP = 98) and is grouped with C. challengeri, Octomeris sp. BKKC-2014, and Notochthamalus scabrosus. Further studies are needed to reveal the specific phylogenic relationships within Cirripedia.

The first mitochondrial genome of Tetraclita japonica from China was presented. The mitochondrial genome of T. japonica CN is a circular DNA molecule containing 15,192 bp. It contains 13 protein-co...

Macrobrachium rosenbergii de Man, 1879 (Caridea: Palaemonidae), commonly referred to as giant freshwater prawn, is commercially important worldwide, and a primary inland cultured species. The first...

We determined the first mitochondrial genome of Tetraclita kuroshioensis from China. The mitochondrial genome of T. kuroshioensis was found to be 15,175 bp in length and consisted of 13 protein-coding genes (PCGs), 22 tRNAs, and 2 rRNAs. The longest non-coding region was 425 bp in length. Phylogenetic analysis showed that T. kuroshioensis clustered with T. serrata and then clustered with T. squamosa squamosa with high bootstrap value (BP = 100). In the future, sequencing of additional mitochondrial genomes should provide additional insights into the deep phylogeny of Cirripedia.

The complete mitochondrial genome of Glycera chirori Izuka (Annelida: Polychaeta) was presented, which is a circular molecule of 15,930 bp nucleotides. It encodes 37 genes, including 13 PCGs, 22 tRNAs, and two rRNAs. The length of non-coding regions is 1428 bp, and the longest one (1346 bp) is speculated as the control region, which is located between trnA and trnL2 and is longer than most species in Glycera. The complete mitogenome of G. chirori Izuka consists of 31.2% A, 23.6% C, 12.9% G, and 32.2% T, which has T vs. A skew (−0.02) and C vs. G skew (−0.29), respectively. Phylogenetic analysis indicates the classification status of G. chirori Izuka and the relationship with other species in Glycera, which is closer with Glycera unicornis and Glycera fallax (bootstrap = 100). By comparisons, the gene arrangement of G. chirori Izuka and other seven species in Glycera are identical and they also cluster together in phylogenetic tree with higher support rate, which indicates the conservativeness between gene arrangement and phylogenetic analysis in Glycera. In conclusion, the complete mitochondrial genome of G. chirori Izuka can provide supportive data for further molecular and evolutionary analysis of Glycera.

Polycyclic aromatic hydrocarbons (PAHs) are known for their carcinogenic, teratogenic and mutagenic properties. Benzo(a)pyrene (BaP) possesses the greatest carcinogenic potential among the various PAHs. In this study, digital gene expression (DGE) was performed to investigate the digestive gland transcriptome profile of the clam Ruditapes philippinarum exposed to BaP. A total of 10,508,312 and 11,414,297 clean reads were generated respectively, from control and BaP exposure DGE libraries. One hundred and forty-five differentially expressed genes were detected after comparing two libraries with 58 up-regulated and 87 down-regulated genes. GO annotation and KEGG pathway analyses were performed on all genes to understand their biological functions and processes. The results showed that numerous enriched differentially expressed genes are related to growth and development, antioxidant metabolism, apoptosis and detoxification metabolism. Quantitative real-time PCR was performed to verify the expressed genes of DGE. Our results provide evidences that RNA-seq is a powerful tool for toxicology and capable of generating novel and valuable information at the transcriptome level for characterizing deleterious effects caused by BaP.

Benzo[a]pyrene (B[a]P) has a high carcinogenic potential. B[a]P concentrations and molecular biomarkers (mRNA expressions of Pgp, AhR, CYP4, CYP414A1, GST-pi, GST-S2, Cu/Zn-SOD and Mn-SOD) were assayed in gills and digestive glands of the clam Ruditapes philippinarum exposed to 0.03, 0.3 and 3 μg/L B[a]P for 21 days and then exposed to natural seawater for 15 days. Results showed that B[a]P was rapidly accumulated in and then eliminated from tissues of the clams. All gene mRNA expressions in the treated groups were induced significantly with the exception of CYP414A1 and Cu/Zn-SOD in the 0.03 μg/L B[a]P group. According to correlation analysis, mRNA expressions of AhR, GST-pi and Mn-SOD in gills and GST-pi in digestive glands had good correlations with B[a]P concentrations and could be used as molecular biomarkers of B[a]P exposure. This study investigated the molecular response of the genes mentioned above and selected useful molecular biomarkers for B[a]P pollution monitoring.

Gonadotropin-releasing hormone (GnRH) is a key neuropeptide regulating reproduction in vertebrates. In the present study, we have cloned and identified the cDNA sequence of the prepro-GnRH (rp-GnRH) in the Manila clam Ruditapes philippinarum. The open reading frame encodes a protein of 94 amino acids, which consists of a signal peptide, a GnRH dodecapeptide, a cleavage site, and a GnRH-associated peptide. These deduced peptides were highly homologous to that reported for other molluscs. We used temperature control to promote gonadal development of the clams. The mRNA expression of rp-GnRH in the visceral ganglia from clams at different reproductive stages was determined by quantitative RT-PCR. The levels of steroids progesterone (P), testosterone (T), and estradiol-17β (E2) in the hemolymph of the corresponding clam were measured by ELISA. The rp-GnRH mRNA was highly expressed at the gonadal early development stage. Concentrations of P, T, and E2 also increased at the early development stage in both sexes. Positive significant correlations between rp-GnRH expression and P content as well as between rp-GnRH expression and T content were observed throughout the gonadal maturation. The results from this study may help to better understand the physiological functions of the native forms of GnRH-like peptides and the actions of GnRH on sex steroids release in bivalve molluscs.

Suppression subtractive hybridization (SSH) was used to identify alterations in gene transcription of the manila clam Ruditapes philippinarum after exposure to 5μg/L 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) for 15days. The ability to accumulate BDE-47 in digestive gland and gill was also evaluated in order to provide information for food safety. Analysis of tissue extracts indicated that digestive gland had the higher BDE-47 levels (12,463.1±1334.8 ng/g d.w.) compared to gill (6368.6±738.7ng/g d.w.) after a 15-day exposure period. Forward and reverse SSH libraries were made from pooled digestive glands of R. philippinarum, from which 75 high quality sequences were obtained by BLAST analysis. The expression of 39 genes with significant homology (E-value