Genetic Signature of Pinctada fucata Inferred from Population Genomics: Source Tracking of the Invasion in Mischief Reef of Nansha Islands.

Among the anthropogenic stresses that marine ecosystems face, biological invasions are one of the major threats. Recently, as a result of increasingly intense anthropogenic disturbance, numerous marine species have been introduced to their non-native ranges. However, many introduced species have uncertain original sources. This prevents the design and establishment of methods for controlling or preventing these introduced species. In the present study, genomic sequencing and population genetic analysis were performed to detect the geographic origin of the introduced Pinctada fucata population in the Mischief Reef of the South China Sea. The results of population genetic structure analysis showed a close relationship between the Mischief Reef introduced population and the Lingshui population, indicating that Lingshui may be the potential geographical origin. Furthermore, lower heterozygosity and nucleotide diversity were observed in the introduced population in Mischief Reef, indicating lower genetic diversity than in other native populations. We also identified some selected genomic regions and genes of the introduced population, including genes related to temperature and salinity tolerance. These genes may play important roles in the adaptation of the introduced population. Our study will improve our understanding of the invasion history of the P. fucata population. Furthermore, the results of the present study will also facilitate further control and prevention of invasion in Mischief Reef, South China Sea.

The complete mitochondrial genome and phylogenetic analysis of the ocellated angelshark: Squatina tergocellatoides Chen, 1963.

The ocellated angelshark (Squatina tergocellatoides Chen, 1963) is a threatened shark within the family Squatinidae. In the present study, we reported the mitochondrial genome sequence of the ocellated angelshark. The complete mitochondrial genome is 16,683 bp in length and contains 37 mitochondrial genes and a control region as similar to most fishes. In addition, we constructed a maximum-likelihood phylogenetic tree of S. tergocellatoides and its relative species. This work will provide molecular data for further studies on S. tergocellatoides.

Complete Mitochondrial Genome of Two Ectoparasitic Capsalids (Platyhelminthes: Monogenea: Monopisthocotylea): Gene Content, Composition, and Rearrangement.

The capsalid monogeneans are important pathogens that generally infect marine fishes and have a substantial impact on fish welfare in aquaculture systems worldwide. However, the current mitogenome information on capsalids has received little attention, limiting the understanding of their evolution and phylogenetic relationships with other monogeneans. This paper reports the complete mitochondrial genomes of Capsala katsuwoni and Capsala martinieri for the first time, which we obtained using a next-generation sequencing method. The mitogenomes of C. katsuwoni and C. martinieri are 13,265 and 13,984 bp in length, respectively. Both species contain the typical 12 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and a control region. The genome compositions show a moderate A+T bias (66.5% and 63.9% for C. katsuwoni and C. martinieri, respectively) and exhibit a negative AT skew but a positive GC skew in both species. One gene block rearrangement was found in C. katsuwoni in comparison with other capsalid species. Instead of being basal to the Gyrodactylidea and Dactylogyridea or being clustered with Dactylogyridea, all species of Capsalidea are grouped into a monophyletic clade. Our results clarify the gene rearrangement process and evolutionary status of Capsalidae and lay a foundation for further phylogenetic studies of monogeneans.

Spatial Distribution, Potential Risks and Source Identification of Heavy Metals in the Coastal Sediments of the Northern Beibu Gulf, South China Sea.

Thirty samples of surface sediments (0-5 cm) from the northern Beibu Gulf were analyzed to determine the spatial distribution, potential risks and sources of six heavy metals (Cr, Cu, Zn, As, Cd and Pb). The concentrations (mg/kg, dw) of Cr, Cu, Zn, As, Cd and Pb were 15.38 ± 6.06, 6.54 ± 3.23, 41.86 ± 17.03, 6.92 ± 2.75, 0.04 ± 0.02 and 17.13 ± 6.38, respectively. Higher levels of Cr, Cu, Cd and Zn were observed in the western part of the study area. According to the potential ecological risk indexes and sediment quality guidelines, the measured metals were assessed at low contamination levels, with Pb posing the largest ecological risks. The results of positive matrix factorization (PMF) indicated that Cr and Zn mainly originated from natural geological background sources, while Cu, As, Cd and Pb were influenced by anthropogenic sources such as atmospheric deposition and anthropogenic activities. These three sources contributed 60.4%, 28.1% and 11.5% of the heavy metals, respectively. In addition, further research should be conducted focusing on the general relationships between As and various controls in sediments of the northern Beibu Gulf.

Transcriptomic analysis of male three-spot swimming crab (Portunus sanguinolentus) infected with the parasitic barnacle Diplothylacus sinensis.

Diplothylacus sinensis is reported as an intriguing parasitic barnacle that can negatively affect the growth, molting, reproduction in several commercially important portunid crabs. To better understand the molecular mechanisms of host-parasite interactions, we characterized the gene expression profiles from the healthy and D. sinensis infected Portunus sanguinolentus by high-through sequence method. Totally, the transcriptomic analysis generated 52, 266, 600 and 51, 629, 604 high quality reads from the infected and control groups, respectively. The clean reads were assembled to 90,740 and 69,314 unigenes, with the average length of 760 bp and 709 bp, respectively. The expression analysis showed that 18,959 genes were significantly changed by the parasitism of D. sinensis, including 4769 activated genes and 14,190 suppressed genes. The differentially expressed genes were categorized into 258 KEGG pathways and 647 GO terms. The GO analysis mapped 13 DEGs related to immune system process and 32 DEGs related to immune response, respectively, suggesting a potential alteration of transcriptional expression patterns in complement cascades of P. sanguinolentus. Additionally, 4 representative molting-related genes were down-regulated in parasitized group, indicating D. sinensis infection appeared to suppress the producing of ecdysteroid hormones. In conclusion, the present study improves our understanding on parasite-host interaction mechanisms, which focuses the function of Ecdysone receptor, Toll-like receptor and cytokine receptor of crustacean crabs infestation with rhizocephalan parasites.

Next generation sequencing yields the complete mitochondrial genome of the darkfin hind Cephalopholis urodeta (Serranidae) from the Mischief Reef, South China Sea.

The complete mitochondrial genome of the Cephalopholis urodeta (Serranidae: Epinephelinae) was sequenced by next-generation sequencing method on the basis of one female specimen collected from coral reef areas at the Mischief Reef, South China Sea. The mitogenome is 16,593 bp in length, including 13 protein-coding genes, 22 tRNA genes, two rRNA genes and a D-loop region. The overall content of A + T is 55.66%, which is significantly higher than the C + G content (44.34%). Among four bases, C shows the lowest frequency (15.99%). Phylogenetic tree based on the 13 protein-coding genes was constructed for analyzing the position of C. urodeta. The results provide useful insights into further studies on population genetics and phylogenetics of groupers.

The complete mitochondrial genome and phylogenetic analysis of the reticulated swellshark: Cephaloscyllium fasciatum Chan, 1966.

In the present study, the complete mitogenome of Cephaloscyllium fasciatum has been sequenced and assembled. The complete mitochondrial genome is 16,509 bp in length and contains 37 mitochondrial genes and a control region as other fishes. The nucleotide composition of C. fasciatum mitogenome showed an anti-G bias and an excess of AT content. Furthermore, maximum-likelihood phylogenetic tree was constructed based on 13 protein-coding genes of C. fasciatum and other 15 sharks. This work will provide molecular data for studies on phylogeny and evolution in the family Scyliorhinidae.

De novo assembly and annotation of the whole transcriptome of Muraenesox cinereus.

In this study, we generated the transcriptome of Muraenesox cinereus from four combined tissues (muscle, sexual, liver and heart) using high-seq sequencing technology. De novo assembly was performed using Trinity software and a total of 62,125,296 high-quality clean reads were assembled and clustered into 75,862 unigene with an N50 of 2034 nt. After annotation, 43,157 unigenes had significant hit in Nr database. And then, 24,510 unigenes were annotated into three GO categories: biological processes, cellular components, and molecular functions. Moreover, 33,032 unigenes were mapped 25 different clusters of eukaryotic proteins. Furthermore, we predicted the structure of all unigenes using HMMER and MISA software, respectively. The result showed that a total of 33,183 nucleotide sequences of coding regions (direction of the sequences is 5'- > 3') were confirmed to the protein database and a total of 29,487 simple sequence repeats (SSR) were identified. The whole transcriptome is an important foundation for future genomic research on the M. cinereus, it could provide comprehensively understanding and further characterizations of transcriptomes of non-model organisms.

The complete mitochondrial genome of the Capsaloides cristatus (Platyhelminthes, Monogenea), a pathogen of the sailfish (Istiophorus platypterus).

This study reports the complete mitochondrial genome of the Capsaloides cristatus (Monogenea: Capsalidae) collected from the gill lamella of Istiophorus platypterus. The total length of the mitogenome was 13,948 bp, containing 12 typical platyhelminthic protein-coding genes, 22 tRNA genes, 2 rRNA genes and a putative non-coding region, with the atp8 gene being absent. The total A + T content was 65.99%, which was significantly higher than that of the C + G content (34.01%). There were two kinds of start codons (ATG and GTG) and three kinds of terminated codons (TAA, TAG and TGA) in the 12 protein-coding genes. Phylogentic analysis revealed close relationships among the genera Capsaloides, Capsala, Benedenia and Neobenedenia with high bootstrap value supported. This study will provide useful molecular data for a better understanding of the species identification and phylogenetic position of C. cristatus.

Heavy metal pollution and stable isotope ratios (δ13C and δ15N) in marine organisms from the Northern Beibu Gulf, South China Sea.

Twenty biota species were collected from the Northern Beibu Gulf to understand the heavy metal pollution status and biomagnification characteristics. Mean concentrations (µg/g) of Mn, Zn, Pb, Cr, Ni, As, Cu, and Cd in the biota species were 0.99, 38.33, 0.14, 0.079, 0.085, 51.10, 7.92, and 0.21, respectively. As levels in most biota species exceeded the corresponding guidelines. Crabs were detected with high metal accumulation ability for each heavy metal except Pb. The ranges of δ15N and δ13C in organisms were from 8.0‰ to 15.6‰ and from -21.4‰ to -15.6‰, respectively. Cr, Mn, Ni, and As showed potential biomagnification trends in the food webs. The EDI values of these elements decreased by the sequence of As > Zn > Cu > Mn > Cd > Pb > Ni > Cr. High THQ and CR values for As indicated a potential health risk by consumption of these aquatic products.

Microcephaly, disproportionate pontine, and cerebellar hypoplasia syndrome: Two novel mutations in the CASK gene were discovered in Chinese females.

Microcephaly, disproportionate pontine and cerebellar hypoplasia (MICPCH) syndrome is a rare and genetic disorder, which is mainly caused by mutations in the CASK gene. We described four variations in the CASK gene in Chinese female patients with MICPCH, who presented with microcephaly, developmental delay, and motor disorder. The CASK mutations were identified using NGS (the next-generation sequencing), copy number variation sequencing. Two novel variations in the CASK gene were revealed including a frameshift mutation c.1000_1001insG (p.Asp334GlyfsTer32) and a nonsense mutation c.2110A > T (p.Lys704Ter). Two other aberrations were c.316C > T (p.Arg106Ter) and Xp11.4-p11.3 (41,700,001-44,660,000) × 1 loss. We provided clinical manifestations and neuroimaging findings of the four patients. The genetic variation spectrum of MICPCH caused by CASK was updated. Furthermore, we expounded on the molecular mechanism of the disease and noticed that it was not possible to relate the magnitude of the genetic alteration to a particular phenotype.

Comparative transcriptomic analysis for identification of candidate sex-related genes and pathways in Crimson seabream (Parargyrops edita).

Teleost fishes display the largest array of sex-determining systems among animals, resulting in various reproductive strategies. Research on sex-related genes in teleosts will broaden our understanding of the process, and provide important insight into the plasticity of the sex determination process in vertebrates in general. Crimson seabream (Parargyrops edita Tanaka, 1916) is one of the most valuable and abundant fish resources throughout Asia. However, little genomic information on P. edita is available. In the present study, the transcriptomes of male and female P. edita were sequenced with RNA-seq technology. A total of 388,683,472 reads were generated from the libraries. After filtering and assembling, a total of 79,775 non redundant unigenes were obtained with an N50 of 2,921 bp. The unigenes were annotated with multiple public databases, including NT (53,556, 67.13%), NR (54,092, 67.81%), Swiss-Prot (45,265, 56.74%), KOG (41,274, 51.74%), KEGG (46,302, 58.04%), and GO (11,056, 13.86%) databases. Comparison of the unigenes of different sexes of P. edita revealed that 11,676 unigenes (9,335 in females, 2,341 in males) were differentially expressed between males and females. Of these, 5,463 were specifically expressed in females, and 1,134 were specifically expressed in males. In addition, the expression levels of ten unigenes were confirmed to validate the transcriptomic data by qRT-PCR. Moreover, 34,473 simple sequence repeats (SSRs) were identified in SSR-containing sequences, and 50 loci were randomly selected for primer development. Of these, 36 loci were successfully amplified, and 19 loci were polymorphic. Finally, our comparative analysis identified many sex-related genes (zps, amh, gsdf, sox4, cyp19a, etc.) and pathways (MAPK signaling pathway, p53 signaling pathway, etc.) of P. edita. This informative transcriptomic analysis provides valuable data to increase genomic resources of P. edita. The results will be useful for clarifying the molecular mechanism of sex determination and for future functional analyses of sex-associated genes.

Heavy metal concentrations and associated health risks in edible tissues of marine nekton from the outer Pearl River Estuary, South China Sea.

Seven heavy metals including Hg, Cu, Pb, Cd, Zn, Cr, and As were examined in seventeen marine nekton species from the outer Pearl River Estuary (PRE), South China Sea. On the wet weight basis, the metal concentration ranges were 0.016-0.157 µg/g for Hg, 0.18-14.3 µg/g for Cu, 0.26-1.48 µg/g for Pb, 0.021-0.873 µg/g for Cd, 1.35-57.15 µg/g for Zn, 0.15-0.53 µg/g for Cr, and 0.42-7.83 µg/g for As, respectively. The levels of tested metals except for Pb in crustaceans were found to be higher than those in fish and cephalopods, suggesting that the diet and habitat played important roles on heavy metal accumulation ability of marine organism. Except for Cd in Champsodon capensis, Calappa lophos, and Portunus argentatus, all the left metal concentrations of investigated nekton species were below their permissible upper limits, indicating that consumption of examined marine nekton should be considered as safe for human health. The values of single target hazard quotient (THQ) and total THQ were all less than 1 and also suggested that there was no health risk for consumption. Even so, the local people should control their daily intake of crustacean foods from the outer PRE, since there might be potential As and Cd cumulative risks.

Four novel compound heterozygous mutations in C5orf42 gene in patients with pure and mild Joubert syndrome.

Joubert syndrome (JS) is a rare clinically and genetically heterogeneous disease. Using whole or targeted exome sequencing, we identified four novel compound heterozygous mutations in chromosome 5 open reading frame 42 gene (C5orf42), including c.2876C>T (missense mutation) and c.3921+1G>A (splicing mutation), c.2292 -2delA (splicing mutation) and c.4067C>T (missense mutation), c.6997_6998insT (frameshift mutation) and c.8710C>T (nonsense mutation), c.3981G>C (nonsense mutation) and c.230 _233del (frameshift mutation), in four Chinese JS families. They were all inherited from their heterozygosis parents in the autosomal recessive inheritance mode. Pure JS clinical manifestations and mild neuroimaging findings were found in these patients. These verified the previous findings that C5orf42 mutations generally resulted in a purely neurological Joubert phenotype, and neuroimaging findings were mild in JS with C5orf42 mutations. Our report analyzed these C5orf42 mutations-associated phenotypes and neuroimaging findings in JS and updated the genetic variation spectrum of JS caused by C5orf42.These will help clinicians and geneticists reach a more accurate diagnosis for JS.

Occurrence of microplastics in gastrointestinal tracts and gills of fish from Beibu Gulf, South China Sea.

Microplastics are widespread across the global oceans, yet the potential risks of the ubiquitous environmental contaminant to marine organisms has been less known. Accumulation of microplastics and associated contaminants in marine fish, may pose adverse impacts to human health via seafood consumption. This study evaluated microplastic contamination in 24 fish species collected from Beibu Gulf, one of the world's largest fishing grounds in South China Sea. Microplastics were detected in 12 fish species at an abundance of 0.027-1.000 items individual-1 and found in fish stomach, intestines and gills with the count percentage of 57.7%, 34.6% and 7.7%, respectively. Transparent fibers were observed as the predominant microplastics, which might be ingested accidently by fish or transferred through other animals at lower trophic levels. Majority of microplastics were identified as polyester (44%) and nylon (38%), whereas polypropylene (6%), polyethylene (6%), and acrylics (6%) were also found. Relatively, higher microplastic abundances were found in demersal fish compared to the pelagic species. Overall, the abundance of microplastics was documented as relatively low in the commercial fish collected from the open water of Beibu Gulf, South China Sea.

The complete mitochondrial genome of milk shark, Rhizoprionodon acutus (Ruppell 1837).

The complete mitogenome sequence of the milk shark, of which Rhizoprionodon acutus was determined using long PCR. The genome was 16,693 bp in length and it contained 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and 1 D-loop region. The overall base composition of the heavy strand is A (31.63%), C (23.91%), T (31.38%), and G (13.08%). However, the base composition of A (31.38%), C (13.08%), T (31.63%), and G (23.91%) was in the light strand. Except for that COXI began with GTG, all the protein initiation codons were ATG. What's more, all the protein termination codons were TAA, in addition to ND2, ND3, and Cytb ended with TAG, COXII and ND4 finished only with T, and ND6 with AGG. Moreover, based on thirteen concatenated PCGs nucleotide datasets, the phylogenetic analysis showed high value support for the following sister clade among the two genera (Rhizoprionodon acutus, Rhizoprionodon; Scoliodon macrorhynchos and Scoliodon laticaudus, Scoliodon).

Clinical characteristics and functional status of children with different subtypes of dyskinetic cerebral palsy.

Dyskinetic cerebral palsy (CP) is the second major subtype of CP. Dyskinetic CP can be classified into different subtypes, but the exact clinical characteristics of these subtypes have been poorly studied. To investigate the clinical characteristics and functional classification of dyskinetic CP from the perspective of neurologic subtypes in a hospital-based follow-up study.This was an observational study of consecutive children with dyskinetic CP treated at The Affiliated Women & Children Hospital of Qingdao University (China) from October 2005 to February 2015. The children were stratified according to their neurologic subtype and assessed with the Gross Motor Function Classification System (GMFCS), Manual Ability Classification System (MACS), and Communication Function Classification System (CFCS). MRI scanning was conducted at 1 year of age for most children.Twenty-six participants (28.0%) had dystonic CP, 26 (28.0%) had choreoathetotic CP, and 41 (44.1%) had mixed CP. Auditory impairment and basal ganglion lesions occurred more frequently in the dystonia group (n = 8, 31%; and n = 16, 67%), while seizures, microcephaly, white matter lesions, and mixed lesions were more frequent in the mixed type (n = 14, 34%; n = 10, 24%; n = 15, 41%; n = 12, 32%). Functional classification levels were distributed unequally among the 3 subgroups (P < .01). No significant difference between GMFCS and MACS was found among the 3 subgroups (P > .05).Different subtypes of dyskinetic CP have specific comorbidities, radiological characteristics, and functional attributes according to their etiological factors and brain lesions. Children with dystonic CP have more limited functional status than children with choreoathetotic CP.

Gene analysis: A rare gene disease of intellectual deficiency-Cohen syndrome.

Cohen syndrome is a rare, genetic, connective-tissue disorder, which is caused by mutations in the gene COH1 (VPS13B, Vacuolar Protein Sorting 13 Homolog B) at the chromosome 8q22. The disease is rare reported, which major clinical features include postnatal microcephaly, obesity, short stature, intellectual disability, progressive retinal dystrophy, intermittent neutropenia and many other unusual facial feature. We report four patients in China who were diagnosed with Cohen syndrome by genetic testing and clinical manifestations. At the same time, we review the related literature, and further expound the molecular mechanism of the disease, a variety of clinical manifestations, treatment and prognosis.

Phylogeography and population structure of - grypotus (Richardson, 1846) as revealed by mitochondrial control region sequences.

The 137 individuals of Johnius grypotus were collected from seven localities from the Bohai Sea to the East China Sea. A 549 base pair (bp) fragment of the hypervariable region of the mtDNA control region was sequenced to examine genetic diversity and population structure. The populations of J. grypotus showed high haplotype diversity (h) with a range from 0.7500 to 0.9740 and low nucleotide diversity (π) with a range from 0.0024 to 0.0067. Low and non-significant genetic differentiation was estimated among populations except for North Yellow Sea population, which has a significant genetic difference with other populations. The demographic history examined by mismatch distribution analyses and Bayesian skyline plot (BSP) analyses revealed that a sudden population expansion occurred almost 20 to 40 thousand years before. Relatively recent population expansion in the last glacial period, large dispersal of eggs or larvae carried by coastal current, and the homogeneity of living environment may have an important influence on the population genetic pattern.

Characterization of the mitochondrial genome of the Shortfin scad Decapterus macrosoma (Perciformes: Carangidae).

The complete mitochondrial genome sequence of Decapterus macrosoma has been obtained with overlapped polymerase chain reaction. The genome was 16,545 bp in length which contained 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and 2 non-coding regions (the control region and the light strand replication origin). Gene organization was similar to that observed in most other vertebrates. With the exception of the ND6 and eight tRNA genes, all other genes were encoded on the heavy strand. The genome was composed of 27.0% A, 30.4% C, 25.4% T and 17.2% G, showing an obvious anti-G bias commonly observed in teleosts. Two termination-associated sequence regions (TAS-1 and TAS-2), three central conserved sequence blocks (CSB-F, CSB-E and CSB-D), and three conserved sequence blocks (CSB-1, CSB-2 and CSB-3) were identified within the control region. The sequence data of D. macrosoma could provide useful information for the studies on molecular systematics and population genetics.