Significant genetic differentiation of Gobiopterus lacustris, a newly recorded transparent goby in China.

In our recent survey, the transparent small Lacustrine goby, Gobiopterus lacustris had reported as the endemic species of Luzon, Philippines, was identified as an abundant species in mangroves of Leizhou Peninsula, China. Here, high diversity and significant differentiation of five sites of samples representing the west and east populations were revealed by mitochondrial DNA sequences. Five haplotypes of 56 cytochrome oxidase subunit I (Cox1) with the lengths of 623 base pairs (bp) have the high pairwise identity (>98.8%). Moreover, a total of 31 haplotypes for 129 partial D-loop regions were clustered into two clades corresponding to the east and west sampling sites. The strong population structure was confirmed (ΦST = 0.43017, p < .0001) with high haplotype diversity (h = 0.880 ± 0.017) and low nucleotide diversity (p=.00484). Moreover, both the mismatch distribution analysis and neutral test of D-loop revealed that the west group might experience a recent demographic expansion. Lastly, the isolation-with-migration analysis supported the expansion and indicated that the east-west split happened at approximately 7.1 kyr ago. Given the distribution and diversity, G. lacustris could be a good model for the study of the sea-level fluctuations and coast evolution of the South China Sea.

Analysis of the complete mitochondrial genome sequence of Palinura homarus.

The complete mitochondrial genome sequence of Palinura homarus was obtained using PCR amplification and walking sequencing (GenBank accession no. JN_542716). The complete mitochondrial genome of P. homarus was 15,665 bp long and showed significant AT bias (67% AT content, 33% GC content). The A + T-rich region included copy-related control information and a poly (dT) structure that related to replication and transcription. In this study, the gene arrangement was consistent with other Palinura mitochondrial genomes and the sequence was strikingly similar to Panulirus ornatus, which would be useful in species identification and natural resources conservation.

Morphological Characters and Transcriptome Profiles Associated with Black Skin and Red Skin in Crimson Snapper (Lutjanus erythropterus).

In this study, morphology observation and illumina sequencing were performed on two different coloration skins of crimson snapper (Lutjanus erythropterus), the black zone and the red zone. Three types of chromatophores, melanophores, iridophores and xanthophores, were organized in the skins. The main differences between the two colorations were in the amount and distribution of the three chromatophores. After comparing the two transcriptomes, 9200 unigenes with significantly different expressions (ratio change ≥ 2 and q-value ≤ 0.05) were found, of which 5972 were up-regulated in black skin and 3228 were up-regulated in red skin. Through the function annotation, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the differentially transcribed genes, we excavated a number of uncharacterized candidate pigment genes as well as found the conserved genes affecting pigmentation in crimson snapper. The patterns of expression of 14 pigment genes were confirmed by the Quantitative real-time PCR analysis between the two color skins. Overall, this study shows a global survey of the morphological characters and transcriptome analysis of the different coloration skins in crimson snapper, and provides valuable cellular and genetic information to uncover the mechanism of the formation of pigment patterns in snappers.

DNA barcoding South China Sea fishes.

We have determined 222 DNA barcode sequences of 95 fish species in 86 genera of 69 families from 15 orders. Fish were captured by trawl from two important fisheries regions in South China Sea: Spratly Islands (Nansha Islands) and Beibu Gulf. The average genetic distances between intraspecies were about 60-fold less than those of interspecies within different taxonomic levels, as Kimura two-parameter genetic distances averaged 17.260% among congeners, 20.097% among genus, and only 0.317% for intraspecific individuals. There were a few examples of deep divergence within species, suggesting the need for further taxonomic work, and a few examples of closely allied species, perhaps reflecting introgressive hybridization. The results provide further evidence for the reliability and accessibility of DNA barcodes for marine fish identification, and also highlight their effectiveness for flagging cases needing taxonomical reexamination.

[Screening and genetic diversity analysis of microsatellite markers in Chinese lobster (Panulirus stimpsoni)].

With the construction of a library of partial fractionated genomic DNA of Panulirus stimpsoni Hoehuis, the microsatellite sequences of P. stimpsoni were screened by PCR technique. Then, the genetic diversity was analyzed with the microsatellite markers. Seventy-eight microsatellite sequences in 55 positive recombinant clones were obtained by PCR technique with primers of M13+/- and (CT)15, and (AT)15. Among these microsatellite sequences, the numbers of perfect, imperfect, compound perfect, and compound imperfect sequences were 50 (64%), 3 (3.8%), 5 (7.7%), and 19 (24.5%), respectively. To analyze genomic DNA diversity of P. stimpsoni, 15 pairs of primers were designed from the microsatellite flanking sequences. In these microsatellite loci, the alleles numbers ranged from 3 to 12; and the sizes of these alleles ranged from 78 to 425 bp, which are in accordance with their predicted size range. The expected heterozygosity (He) and the polymorphism information content (PIC) ranged from 0.48 to 0.87 and 0.44 to 0.84 with the average values of 0.71 and 0.60, respectively. These results showed that these microsatellite loci were suitable for P. stimpsoni molecule markers and genetic analysis because of their richness in genetic information.

[Suffocation point and diurnal metabolism pattern of Hemifusus tuba (Gmelin)].

The individuals of Hemifusus tuba (Gmelin) were divided into 3 groups, i. e., small [S, (6.48 +/- 0.46) cm], medium[ M, (7.59 +/- 0.41) cm], and large [L, (9.08 +/- 0.37) cm], according to their shell height, and their suffocation points and diurnal metabolism patterns were investigated at water temperature (22 +/- 0.5) degrees C. The results indicated that the oxygen consumption rate of H. tuba was relatively stable and maintained at 1.81 mg x g(-1) x h(-1) when dissolved oxygen (DO) content was higher than 4.37 mg x L(-1), but decreased with decreasing DO when DO content was lower than 4.37 mg L(-1) x 0.43 mg L(-1) of DO was the suffocation point of H. tuba, with the oxygen consumption rate being 0. The standard metabolism (SM) and routine metabolism (RM) of H. tuba decreased significantly with increasing body mass, and changed with the same pattern in the 3 groups, i. e., being higher at night than in daytime. There was a significant difference in the SM (F = 36.263, P < 0.01) and RM (F = 6.788, P < 0.01) among the 3 groups. The peak values of the specific dynamic metabolism of groups S, M, and L were 2.11, 1.62, and 1.42 mg x g(-1) h(-1), being 1.09, 0.75, and 0.71 times higher than their SM, respectively, and maintained about 15 h. The ammonia excretion rates of groups S, M, and L reached the peak after 24, 24, and 27 hours of feeding, with the peak values being 3.94, 2.64, and 1.71 micromol x g(-1) x h(-1), and 0.87, 0.73 and 0.31 times higher than those in starvation state, respectively,.

[Microsatellite analysis of genetic diversity and phylogenetic relationship of nine species of grouper in genus Epinephelus].

Thirteen microsatellite markers of Epinephelus awoara previously discovered by our lab were selected to analyze the genetic diversity and phylogenetic relationship of nine species of grouper (E. awoara, E. merra, E. fario, E. fasciatus, E. lanceolatus, E. akaara, E. septemfasciatus, E. coioides and E. fuscoguttatus) from South China Sea. The results showed that the number of total alleles of these 13 microsatellite loci was 84 in these fishes, the mean number of alleles ranged from 2.69 to 5.38, mean polymorphism information content (PIC) ranged from 0.1976 to 0.4267, mean observed heterozygosity (Ho) from 0.4615 to 0.6239, mean expected heterozygosity (He) from 0.3510 to 0.4754 and mean Hardy-Weinberg departure value (D) from 0.1097 to 0.2836, respectively. All of these indicated that genetic diversity of the nine species of grouper was at a medium level. Two NJ dendrograms showed that E. coioides, E. fuscoguttatus and E. lanceolatus were grouped together, while E. awoara, E. akaara and E. septemfasciatus were in a second group, and E. merra, E. fasciatus and E. fario were in a third group which had a relatively closed relationship with the second group. The dendrograms could also support a conclusion that Promicrops lanceolatus (E. lanceolatus) should be included in genus Epinephelus.

[Rapid isolation and characteristics analysis of microsatellites from Lutjanus russelli].

The (CA)n DNA sequences in Lutjanus russelli were isolated through PCR arrays, and the characteristics of the microsatellite were analyzed. DNA was extracted from a sample of Lutjanus russelli, and digested with Hae+Dra. The fragments were ligated to pUCm-T vector and transferred into DH5alpha to construct a genomic library. The positive clones were isolated with universal M13 reverse and forward primers, M13 forward primer and the simple sequence repeats (SSRs) probes (CA)15, M13 reverse primer and (CA)15. After twice isolation, 121 positive clones, whose PCR products with M13 forward primer and probes (CA)15 or M13 reverse primer and (CA)15 were smaller than those with universal M13 reverse and forward primers probably contained microsatellites, were obtained. Then, 53 (CA)n(n> or =7) microsatellites were obtained by sequencing. The repeat length mainly distributed in 7-15(80.77%). Besides (CA)n repeats, other repeat motifs, such as An, (CAC)n and (AACA)n, were also obtained. Scorable and constant amplification of DNA fragments were observed with 48 pairs of SSR primers designed from the flank sequences. This research makes a positive contribution to explorating genomes of Lutjanus russelli, offers genetic tools to examine the genetic variations and constructs genetic linkage map.