L.Q. Chen

Characterization of the complete mitochondrial genome of the Rock pigeon, Columba livia (Columbiformes: Columbidae)

The rock pigeon (Columba livia), or Rock dove, is a member of the bird family Columbidae. We mapped the complete mitochondrial genome of the Rock pigeon. The mitochondrial genome of this species is a circular molecule of 17,229 bp in length, encoding a standard set of 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes, plus a putative control region, demonstrating a structure very similar to that of other birds. As found in other vertebrates, most of these genes are coded on the H-strand, except for NADH dehydrogenase subunit 6 (nad6) and eight tRNA genes (Gln, Ala, Asn, Cys, Tyr, Ser(UCN), Pro, Glu). The AT skew and GC skew of the whole genome, protein-coding genes, tRNA, rRNA, and the control region were calculated for the complete mitochondrial genomes of 30 avian species, representing 29 orders. All protein-coding genes initiated with ATG, except for cox1 and nad5, which began with GTG. One extra nucleotide C was present in NADH dehydrogenase subunit 3 (nad3). All tRNA gene sequences have the potential to fold into typical cloverleaf secondary structures. Within the control region, conserved sequences were identified in three domains. Although the conserved blocks, such as ETAS1, ETAS2, CSB1, CSB1-like, and boxes C, D, E, and F, are readily identifiable in the C. livia control region, the typical origin of H-strand replication (O(H)), CSB2 and CSB3 could not be detected. These results provide basic information for phylogenetic analyses of birds, especially Columbiformes species.

Acute tolerance and metabolic responses of Chinese mitten crab (Eriocheir sinensis) juveniles to ambient nitrite.

The lethal concentration of nitrite to the Chinese mitten crab Eriocheir sinensis was tested by exposing the animals to 17.78, 23.71, 31.62, 42.17, and 56.23 mg NaNO2 L(-1) at 20 degrees C for 24, 48, 72, and 96 h. The corresponding LC50 value for each time exposure was 43.87 (38.70-51.70), 40.24 (34.88-46.01), 38.87 (33.72-46.01) and 38.87 (33.72-46.01) mg NaNO2 L(-1) or 29.25 (25.80-34.47), 26.83 (23.25-30.67), 25.91(22.48-30.67), 25.91(22.48-30.67) mg NO2-N L(-1), respectively. The physiological response of the crab to nitrite toxicity was further investigated by exposing the crab to 0, 10, 20, 30 and 40 mg NaNO2 L(-1) for 2 d. The changes of nitrogenous compounds in haemolymph, oxyhemocyanin and metabolism were measured at 3, 6, 24 and 48 h upon exposure. Haemolymph nitrite was significantly enhanced by the increase of nitrite from 10 to 40 mg NaNO2 L(-1) during the 2-day exposure. The concentrations of nitrate, urea and glutamate in haemolymph increased concomitantly with the exposing time and ambient nitrite levels, suggesting that the formation of nitrate, urea and glutamine may be the possible end products of nitrite detoxification in crabs. The diffusion of nitrite caused a reduction of oxyhemocyanin, resulting to hypoxia in tissues. Under a hypoxia condition, crabs increased energy demand for metabolism as indicated by the elevated levels of glucose and lactate in haemolymph. Our data showed that ambient nitrite could affect oxygen carrying capacity through oxyhemocyanin reduction and the increase of energy catabolism in crabs. This study suggests that nitrite could be detoxified through the pathway of nitrate, urea and glutamine formation in crabs.

A novel gene with a vWD domain and three Kazal-type domains: Molecular cloning and expression in the ovary of the oriental river prawn, Macrobrachium nipponense

A novel gene encoding a von Willebrand factor D (vWD) domain and three Kazal-type domains was firstly indentified from the ovary of the oriental river prawn Macrobrachium nipponense and this gene was named as MnvWD-Kazal. Bioinformatics analyses showed that this gene encodes a protein of 857 amino acids with a predicted molecular mass of 92.7 kDa. Real-time quantitative PCR (RT-QPCR) analyses revealed that the level of MnvWD-Kazal mRNA expression varied in the developing ovary and substantially differed between other tissues. In the ovary, the level of MnvWD-Kazal expression gradually increased from the perinucleolus (PN) stage to the yolk granule (YG) stage, and then abruptly decreased at the sexual maturation (MA) stage. The maximum expression occurred in the YG stage and the minimum was at the paracmasis (PM) stage. The expression level of MnvWD-Kazal in the intestine was much higher than that in other tissues. The differential expressions of MnvWD-Kazal at different stages of the ovary suggest that this novel gene may play a critical role in the oocyte maturation of M. nipponense.

Characterization of eight novel microsatellite markers in the green-lipped mussel Perna viridis (Mytilidae).

The green lipped mussel, also known as the Asian green mussel (Perna viridis) is a fast reproducing and valuable food source, but it is also considered an invasive species and can clog and damage pipes and marine equipment. Eight novel polymorphic microsatellite loci for P. viridis were isolated and characterized. Microsatellite polymorphism was evaluated in 30 individuals collected from Xiamen, China. The number of alleles per locus and the polymorphism information content ranged from 2 to 5 and from 0.3092 to 0.7031, respectively. The observed and expected heterozygosities were 0.1538-0.8400 and 0.1448-0.6833, respectively. The loci identified in this study could provide a useful tool for the genetic population structure analysis of P. viridis.

Molecular characterization of a cytosolic manganese superoxide dismutase from the Chinese mitten crab, Eriocheir sinensis.

A cytosolic manganese superoxide dismutase gene (Es-cMnSOD) was cloned from the Chinese mitten crab Eriocheir sinensis, using reverse transcription-polymerase chain reaction and the rapid amplification of cDNA ends. The open reading frame of Es-cMnSOD is 867 bp in length and encodes a 288-amino acid protein without a signal peptide. The calculated molecular mass of the translated protein of Es-cMnSOD is 31.43 kDa, with an estimated isoelectric point of 6.30. The deduced amino acid sequence of Es-cMnSOD has similarities of 90, 89, 84, 87, and 81% to those of white shrimp Litopenaeus vannamei MnSOD, black tiger shrimp Penaeus monodon MnSOD, giant freshwater prawn Macrobrachium rosenbergii MnSOD, blue crab Callinectes sapidus MnSOD, and red swamp crayfish Procambarus clarkii MnSOD, respectively. Es-cMnSOD contains a manganese superoxide dismutase domain (DVWEHAYY) and 4 conserved amino acids responsible for binding manganese. Es-cMnSOD was expressed in the hemocytes, eyestalk, muscle, intestine, gill, and hepatopancreas. Es-cMnSOD transcripts in hemocytes of E. sinensis increased at 1.5 and 48 h after injection of Aeromonas hydrophila, indicating that the induction of the SOD system response occurred within a short period of time. This study suggests that MnSOD may play a critical role in crab immunity, allowing efficient activation of an early innate immune response in the crab.

Promoter and first exon methylation regulate porcine FASN gene expression

DNA methylation is a stable epigenetic mark mediating gene expression. Methylation is crucial for diverse biological processes, including aging and embryo development. FASN (fatty acid synthase) plays an important role in de novo lipogenesis, through catalyzing the reductive synthesis of long-chain fatty acids. In this study, we investigated the FASN gene expression pattern and corresponding DNA methylation status in the inner layer of backfat from Jinhua pigs at different developmental stages. Our results showed that FASN gene expression increases with age and is positively associated with adipocyte volume (r = 0.98, P < 0.01). In addition, the DNA methylation level for the first exon (0.11, CGI 3) of the FASN gene is approximately 8-fold lower than levels for its promoter (0.94, CGI 1&2) (two-way ANOVA, PCGI < 0.01). The association analysis revealed that both promoter (r = -0.944, P < 0.01) and first exon methylation (r = -0.774, P < 0.01) are significantly and negatively correlated with FASN gene expression. Our results will benefit future investigations of the epigenetic mechanism underlying FASN gene expression.