Guifeng Li

Comparative sperm ultrastructure of three species in Siniperca (Teleostei: Perciformes: Sinipercidae)

Siniperca chuatsi, Siniperca kneri, and Siniperca scherzeri are three of the most economically important sinipercid species. The ultrastructure and morphology of the mature spermatozoa of them are examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The sperm consists of an acrosome-less head, a short midpiece and a long flagellum. Ultrastructurally, it has a homogeneously electron-dense nucleus in a granular pattern with nuclear lucent and a nuclear fossa excluding the centriolar complex. One to four mitochondria with lamellar cristae encircle the basal body of the flagellum in the midpiece. The cytoplasm surrounding the centrioles and the cylindric cytoplasmic channel contains glycogen granules and vesicles. Comprising the conventional 9+2 axoneme, vesicles and lateral fins, the sperm flagellum is inserted laterally on the nucleus, therefore the spermatozoon is asymmetrical. All of the spermatozoa of the three species are of the primitive or ect-aquasperm form and conform to the teleostean type II spermatozoa instead of the previously supposed type I. Variations in the shape of the heads, angles between the two centrioles, location of the cytoplasmic vesicles, mitochondrial number and structural characteristics of the lateral fins are notable among the three species. S. chuatsi is a sister-group of the other two species and is the most differentiated. The present study provides fresh insights to the comparative spermatology of Siniperca fishes and will be useful to the existing knowledge of the sinipercid fishes in systematic characters, biodiversity conservation and reproduction.

The complete mitochondrial genome of the Clarias fuscus (Siluriformes, Clariidae)

Abstract We present the complete mitochondrial genome of the Clarias fuscus in this study. The mitochondrial genome is 16,525 bp in length and consists of 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a control region. The nucleotide compositions of the light strand are 31.17% of A, 27.54% of C, 25.34% of T, and 14.95% of G. With the exception of ND6 and eight tRNA genes, all other mitochondrial genes are encoded on the heavy strand. All the protein-coding genes begin with an ATG initiation codon except for COXІ with GTG. Five types of termination codons revealed are TAA (COXІ, ATP8, ND4L), T (ND2, ND3, ND4, COXП, Cytb), AGG (COXШ), TA (ATP6), and TAG (ND1, ND5, ND6). Most genes are either abutted or overlapped and many features keep consistent with the other vertebrates.

Comparative analysis of sequence feature and expression of two heat shock cognate 70 genes in mandarin fish Siniperca chuatsi.

Heat shock cognate protein 70 (HSC70) is a molecular chaperone that plays essential roles in maintaining the cellular protein homeostasis. In this study, two HSC70 isoforms were identified and characterized from mandarin fish Siniperca chuatsi. They have similar sequence structures, containing seven introns in their coding regions and sharing 94% similarity of their deduced amino acid sequences with 38 substitutions. Transcripts of both isoforms were detected throughout the embryogenesis, at low levels during the early developmental stages and up-regulated at blastula for ScHSC70-1 and appearance of myomere stage for ScHSC70-2. They were ubiquitously expressed in tissues under normal conditions, whereas with tissue-specific variation. Following acute heat shock at 34°C, the expression of ScHSC70-1 showed no significant changes in the liver, and just a modest increase in the heart and head kidney, while the ScHSC70-2 mRNA levels were markedly up-regulated in these tissues. Compared with their expression under gradual heat shock, the ScHSC70-2 mRNA was rising at a higher rate under fast heat shock, whereas the ScHSC70-1 mRNA increasing rate was lower under fast heat shock. Under hypoxia, transcripts of ScHSC70-1 were not significantly changed, while the expression of ScHSC70-2 was suppressed. Aeromonas hydrophila infection significantly increased the ScHSC70-1 mRNA levels in the head kidney and spleen on early infective stages, while failed to have any significant impact on the expression of ScHSC70-2 in both immune tissues. These results suggest that ScHSC70-1 and ScHSC70-2 are differently involved in the embryogenesis and the stress responses of high temperature, hypoxia and bacterial infection. This study will contribute to further study on enhancing stress tolerance and disease resistance of mandarin fish.

Microstructure assessment of the thalamus in Wilson's disease using diffusion tensor imaging.

AIM To assess diffusion changes of the thalamus in Wilsons disease using diffusion tensor imaging (DTI). MATERIALS AND METHODS Fifteen patients with Wilsons disease and an abnormal signal in the thalamus (designated as group 1) and 18 patients with Wilsons disease with a normal-appearing thalamus (designated as group 2) at conventional magnetic resonance imaging (MRI) were recruited. Fifteen age-matched and sex-matched healthy volunteers were also enrolled as the control group (designated as group 3). The fractional anisotropy (FA), primary eigenvalue (λ1), second eigenvalue (λ2), and third eigenvalue (λ3) of the thalamus were measured and the differences were compared. RESULTS The FA values of the thalamus were different in the three groups (group 1: 0.36 ± 0.02; group 2: 0.38 ± 0.02; group 3: 0.43 ± 0.02; F = 54.51, p < 0.001). A statistically significant difference was observed between group 1 and group 2 (p = 0.003), group 1 and group 3 (p = 0.001), and group 2 and group 3 (p < 0.001). The λ1, λ2, and λ3 values of the thalamus were different in the three groups (1.11 ± 0.06 mm(2)/s, 1.11 ± 0.06 mm(2)/s, and 1.10 ± 0.04 mm(2)/s of λ1 in group 1, group 2, and group 3, respectively; 0.82 ± 0.08 mm(2)/s, 0.78 ± 0.05 mm(2)/s, and 0.72 ± 0.02 mm(2)/s of λ2 in group 1, group 2, and group 3, respectively; 0.52 ± 0.05 mm(2)/s, 0.49 ± 0.06 mm(2)/s, and 0.42 ± 0.06 mm(2)/s of λ3 in group 1, group 2, and group 3, respectively; F = 1.65, p = 0.203 of λ1; F = 10.55, p < 0.001 of λ2; F = 4.21, p = 0.021 of λ3; respectively). A statistically significant difference in the λ2 value was observed between group 1 and group 3 (p < 0.001) and group 2 and group 3 (p = 0.005). A statistically significant difference in the λ3 value was also observed between group 1 and group 3 (p = 0.007). No significant difference in the λ1 value was noted between each of the two groups. CONCLUSIONS Damage of the thalamus in Wilsons disease patients can be detected using DTI. DTI may provide information regarding thalamus damage in patients with Wilsons disease before abnormal signals on conventional MRI.

Two HSP90 genes in mandarin fish Siniperca chuatsi: identification, characterization and their specific expression profiles during embryogenesis and under stresses

HSP90 plays important roles in multiple cellular stress responses. Here, two cytoplasmic HSP90 isoforms, ScHSP90α and ScHSP90β, were identified from Siniperca chuatsi. Their cDNA and gDNA structures, amino acid sequence features, and sequence identities and phylogenetic analysis with other species were described. Their expression profiles during embryonic development in different tissues and under stressful conditions were analyzed using real-time quantitative PCR. During embryogenesis, transcripts of both genes were detected at low levels during the early developmental stages and were up-regulated from appearance of myomere for ScHSP90a and closure of blastopore for ScHSP90β. ScHSP90α showed a tissue-specific variation with high expression in ovary and brain under non-stressed conditions, while ScHSP90β was ubiquitously highly expressed in different tissues. Acute heat shock resulted in a strong up-regulation of ScHSP90α in heart, liver, and head kidney, while it only weakly induced ScHSP90β in these tissues. ScHSP90α was also markedly induced in liver in a time-dependent manner under hypoxia, while the expression of ScHSP90β was not affected by hypoxia. Additionally, Aeromonas hydrophila infection markedly augmented ScHSP90α in head kidney and spleen and mildly up-regulated ScHSP90β in spleen, while suppressing ScHSP90β in head kidney. These results suggest that ScHSP90α and ScHSP90β are differently involved in embryogenesis and under different environmental conditions including high temperature, hypoxia, and bacterial infection. This study will benefit to further clarify the roles of fish HSP90 isoforms in embryogenesis and under stressful conditions and contribute to further study on enhancing stress tolerance and disease resistance of mandarin fish.

The complete mitochondrial genome ofNibea coibor(Perciformes, Sciaenidae)

Abstract We present the complete mitochondrial genome of Nibea coibor in this study. The mitochondrial genome is 16,502 bp in length and consists of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a control region. All of them are encoded on the heavy strand except ND6 and 8 tRNA genes on the light strand. The nucleotide compositions of the light strand were 31.62% of G, 26.88% of T, 25.19% of A and 16.31% of C. Three types of initiation codons are ATA (ATP6), ATG (ND2, COXI, COXII, ATP8, COXIII, ND3, ND4L, ND4, ND5, ND6, Cytb) and GTG (ND1), and 3 types of termination codons are AGA (COXI), T (ND2, COXII, ND3, ND4) and TAA (ATP6, ATP8, COXIII, ND4L, ND5, ND6, Cytb, ND1). There are 13 intergenic spacers, 7 gene overlaps and no tandem repeat sequence. Gene arrangement and distribution are consistent with the typical vertebrates.

Ecological effects of dams, alien fish, and physiochemical environmental factors on homogeneity/heterogeneity of fish community in four tributaries of the Pearl River in China

Abstract In this study, we aimed to characterize the fish community structure and identify the drivers contributing to homogenization/differentiation processes in four tributaries to the Pearl River, Guangxi Province, China, over the past few decades. We sampled 22 sites seasonally from 2013 through 2015, and these sites were selected based on archived records of previous sampling conducted in the 1980s. Jaccards faunal similarity index, cluster analysis, and canonical correspondence analysis (CCA) were applied to describe the homogenization/differentiation of fish community and illustrate the potential effectors. The number of fish species present in three of the four sampled tributaries declined dramatically over the past 30 years, leading toward a trend of increased fish community homogeneity throughout the watershed. Results from multidimensional scaling and cluster analyses allowed us to divide the study area into two distinct ecoregions. Four species (yellow catfish Pelteobagrus fulvidraco, pond loach Misgurnus anguillicaudatus, Nile tilapia Oreochromis niloticus, and sharpbelly Hemiculter leucisculus) were considered to be indicative fish species contributing more than 5% of the dissimilarity between the two eco‐regions according to the results of similarity percentage procedure. Results from CCA revealed that pH and latitude corresponded with the dominant fish species of each respective tributary. More specifically, CCA results allowed us to classify dominant fish species into three distinct groups. The first group was mainly located in Guijiang characterized by higher latitudes and lower pH values, the second group was widespread in the four tributaries, and the last group was primarily distributed in Yujiang, Youjiang, and Zuojiang characterized by lower latitudes and higher pH values. Spatial differentiation of fish community structure and temporal homogeneity of species composition were attributed to the joint actions of human interventions including construction of dams and introductions of exotic fish species that led to habitat degeneration and fragmentation, and unequal interspecies competitions.

The effect of age on apparent diffusion coefficient values in normal spleen: A preliminary study

AIM To investigate and characterize the effect of age on apparent diffusion coefficient (ADC) values in normal spleen. MATERIALS AND METHODS A population of 127 patients (age range 10-79 years, mean age 44.4 years) without magnetic resonance imaging findings in abdominal scans, was selected over a 5-year period. The ADC values of the spleen were analysed in all ages, and dependency of ADC values on age was characterized using Spearmans correlation coefficient test. RESULTS A reduction of ADC values with ageing was found in the spleen (r = -0.702, p < 0.001). CONCLUSIONS The ADC values of the spleen decline with age. This should be taken into consideration when disease is diagnosed.

The mitochondrial genome of Spualiobarbus curriculus of Pearl River

Abstract Spualiobarbus curriculus is an important economic species in China. In this study, the complete mitochondrial genome of S. curriculus collected from three parts of Pearl River is cloned and analyzed. The complete sequence includes 22 tRNA genes, two rRNA genes, 13 protein-coding genes, and a D-loop region. The composition of nucleic acid is calculated and it is similar to the known S. curriculus mtDNA. The diversities of sequences and the phylogenetic tree approve that there is high similarity with the one of Yangtze, but there is geographic differences between the sequences. The complete mtDNA genome sequence would contribute to studying phylogenetics in S. curriculus and gemplasm protection of aquatic animal in Pearl River.

Diel distribution, migration and abundance assessment of Toxabramis houdermeri in Baise Reservoir, China

Abstract. The split-beam hydro-acoustics surveys were conducted to learn about the diel migration and distribution characters of Toxabramis houdermeri and to assess its current abundance in Baise Reservoir of China in October 2013. The study revealed the average density of T. houdermeri was 258 individuals/1000 m3, and gradually increased from downstream, through middle to upstream (203 individuals/1000 m3, 252 individuals/1000 m3 and 318 individuals/1000 m3, respectively). The study also showed that the target species always distributed in the 2–42 m water layer during the daytime, before migrating upward around dusk which led the fish density to sit in the 2–12 m water layer, to reaching a peak value of 1740 individuals/1000 m3 during the night. Finally, the fish volume density was found to positively correlate with the concentration of chlorophyll, dissolved oxygen (DO) and pH value in their studied areas. In conclusion, the results presented that T. houdermeri preferred a relatively higher average chlorophyll concentration of 3.58 ug/L DO of 6.33 mg/L, and pH of 7.96 in the upstream and upper layers of Baise Reservoir.