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To investigate the roles of the ANT gene, which codes for adenine nucleotide translocase (ANT) during crustacean development, a full-length cDNA sequence of EcANT in the ridgetail white prawn Exopalaemon carinicauda, was cloned, and its expression profile was analyzed at different developmental stages and post-molting times. The EcANT gene (GenBank accession number: KP892663) contained an open reading frame of 924 bp encoding a 307 amino acid protein with a theoretical size of about 33.42 kDa and a predicted isoelectric point of 9.77. Tissue expression analysis revealed that EcANT was mainly expressed in muscle and its expression level tended to increase with the developmental stages. In addition, the expression level of EcANT after molting increased following the lengthening of post-molting time. Our results suggest that EcANT is an important gene related to the growth and development of E. carinicauda.

Coelomactra antiquata is a famous delicacy and a promising new candidate for aquaculture, which belongs to the family Mactridae (Mollusca: Veneroida). The complete mitochondrial genome of C. antiquata (Liao Ning province, in China, LN) was finished, which is the first representative from this province. The results showed that the total length of LN-mtDNA sequence is 16,797 bp and the content of A + T is 65.01%. It encodes 35 genes, including 12 protein-coding genes, 21 transfer RNA genes and two ribosomal RNA genes. All coding genes are encoded on the heavy strand. Compared with the typical gene content of animal mitochondrial genomes, atp8 and trnSer(UCN) genes are missing in the mitochondrial genome. The complete mitochondrial genome contains 26 non-coding regions (1598 bp), one major non-coding region consists of 1046 bp in which 4.9 tandem repeat sequences (99bp per sequence) was observed. The phylogenetic tree showed that Liaoning population was clustered into one clade with Shandong (Rizhao, Jiaonan and Jimo) and Guangxi (Beihai) populations, meanwhile all of them are far from the Fujian populations (Pingtan, Zhangzhou and Changle). So, Liaoning, Shandong and Guangxi populations have a close relationship. Actually, Fujian is located between Liaoning, Shandong and Guangxi. So, the result challenges the previously assumed relevance between geographic distance and genetic distance. The genetic distance of Liaoning C. antiquata and Fujian (Changle, Zhangzhou and Pingtan) C. antiquata (0.176–0.177) is greater than the genetic distance between Mytilus galloprovincialis and Mytilus trossulus (0.160). The genetic difference of Liaoning population and Fujian populations has reached species level.

Long chain acyl-CoA synthetase 1 (ACSL1), a key regulatory enzyme of fatty acid metabolism, catalyzes the conversion of long-chain fatty acids to acyl-coenzyme A. The full-length cDNAs of ACSL1a and ACSL1b were cloned from the liver of a grass carp. Both cDNAs contained a 2094bp open reading frame encoding 697 amino acids. Amino acid sequence alignment showed that ACSL1a shared 73.5% sequence identity with ACSL1b. Each of the two ACSL1s proteins had a transmembrane domain, a P-loop domain, and L-, A-, and G-motifs, which were relatively conserved in comparison to other vertebrates. Relative expression profile of ACSL1 mRNAs in different tissues indicated that ACSL1a is highly expressed in heart, mesenteric adipose, and brain tissues, whereas ACSL1b is highly expressed in heart, white muscle, foregut, and liver tissues. Nutrient regulation research showed that the expression levels of ACSL1a and ACSL1b were significantly down-regulated when 3, 6, and 9% fish oil were added in diet of grass carp as compared to the control group. However, no significant difference in the levels of ACSL1 mRNA was observed between the experimental groups. This study demonstrated the relationship between ACSL1a and ACSL1b genes in grass carp and laid a foundation for further research on ACSL family members in other species.

Complete mitochondrial genome plays an important role in the accurate revelation of phylogenetic relationships among metazoans. Here we present the complete mitochondrial genome sequence from a sea cucumber Apostichopus japonicus (Echinodermata: Holothuroidea), which is the first representative from the subclass Aspidochirotacea. The mitochondrial genome of A. japonicus is 16,096 bp in length. The heavy strand consists of 31.8% A, 20.2% C, 17.9% G, and 30.1% T bases (AT skew = 0.027: GC skew = 0.062). It contains thirteen protein-coding genes (PCGs), twenty-two transfer RNA genes, and two ribosomal RNA genes. There are a total of 3793 codons in all thirteen mitochondrial PCGs, excluding incomplete termination codons. The most frequently used amino acid is Leu (15.77%), followed by Set (9.73%), Met (8.62%), Phe (7.94%), and Ala (7.28%). Intergenetic regions in the mitochondrial genome of A. japonicus are 839 bp in total, with three relatively large regions of Unassigned Sequences (UAS) greater than 100 bp. The gene order of A. japonicus is identical to that observed in the five studied sea urchins, which confirms that the gene order shared by the two classes (Holothuroidea and Echinoidea) is a ground pattern of echinoderm mitochondrial genomes. Bayesian tree based on the cob gene supports the following relationship: (outgroup, (Crinoids, (Asteroids, Ophiuroids, (Echinoids, Holothuroids)))). (C) 2009 Elsevier B.V. All rights reserved.

The complete mitochondrial genome of Coelomactra antiquata (Guangxi, in China, GX) was determined. It is 16 801 bp in length and is the first representative from this province. The mitochondrial genome encodes 35 genes, including 12 PCGs, two ribosomal RNA, and 21 transfer RNA genes. Atp8 and trnSer(UCN) genes are missing, compared with the typical gene content of animal mitochondrial genomes. Three (cob, nad1, nad4, and nad6) of the 12 PCGs in the mitochondrial genome initiate with the ATA, while other PCGs start with ATG. Two PCGs (atp6 and nad4L) end with incomplete stop codons (T-), and the remaining ones have complete stop codons (TAA or TAG). The largest non-coding region of the C. antiquata (GX) contains one section of tandem repeats (5 × 99 bp). Among all PCGs and rRNAs, the nad5 gene contains the maximum polymorphic sites (430), followed by nad4 (261) and cox2 (240). Two ribosomal RNA genes (srRNA and lrRNA) and cox1 are most conservative. The proportions of polymorphic sites in six genes (nad4, nad2, nad6, nad5, cox2, and nad3) are more than 20% (ranging from 20.25% to 25.21%). These high variable genes can be used as molecular markers in the population genetic analysis of the species.

Mactra veneriformis (Bivalvia: Mactridae) is one commonly cultured bivalve species in the western Pacific Ocean. In the current study, the complete mitrochondrial DNA (mtDNA) of the clam M. veneriformis was determined. The M. veneriformis mt genome is 16,854 bp in length and encodes 34 genes on the same strand, including 12 protein-coding genes (PCGs), 2 ribosomal RNA genes and 20 transfer RNA genes. The length of 12 PCGs is 11,358 bp, which accounts for 67.4% in whole mt genome. The proportion is similar to other clams' mt genomes and within those of bivalves mt genomes. Gene order (which is the same as that of RZ C. antiquata) of M. veneriformis mt genome is compared with that of other veneroids. Compared with the typical gene content of animal mt genomes, atp8 and two tRNA(Ser) genes are missing in the mt genome. All non-coding regions are 1978 bp in length, among them the longest one is speculated as the control region, which is located between the tRNA(His) and tRNA(Arg). The secondary largest non-coding region (NCR(664)) between the tRNA(Gln) and tRNA(Thr) in the M. veneriformis mt genome contains one section of tandem repeats (125 nt × 5.2 or 249 nt × 2.6). The tandem repeats account for 97.89% (650/664) of the NCR(664), which is a unique characteristic of the M. veneriformis mt non-coding regions compared with those of other veneroids.

The mitochondrial genome sequence of Coelomactra antiquata (Mollusca: Bivalvia) in Zhangzhou (zz-mtDNA) was fully sequenced and compared with that in Rizhao (rz-mtDNA) in this study. A tRNA (tRNA (Met) ) located between tRNA (Ala) and cox1 genes was identified in zz-mtDNA but not in rz-mtDNA. The largest non-coding region (NCR; MNR) contained 11 copies 99nt tandem repeat sequences exclusively in rz-mtDNA, while the second largest NCR with 400 bp between tRNA (Ala) and tRNA (Met) in zz-mtDNA was absent in rz-mtDNA. Secondary structures of ZZ and RZ C. antiquata rRNAs are significantly different. The mitochondrial genomic characteristics clearly indicate that there are at least two subspecies in C. antiquata.