Zhenhua Ma

Molecular cloning and expression analysis of the retinoid X receptor (RXR) gene in golden pompano Trachinotus ovatus fed Artemia nauplii with different enrichments

The retinoid X receptors (RXRs) are involved in the skeletal development and other biological process such as blood vessel formation and metabolism. Partial sequences of RXRα and β genes were obtained, and their expressions were quantified on golden pompano Trachinotus ovatus at 28 days post hatching (DPH) to explore the molecular response to nutritional manipulation in fish larvae. As live food, Artemia nauplii were separately enriched with Nannochloropsis and Algamac 3080 and non-enriched Artemia nauplii (control) for fish feeding. The expressions of RXRs were detected in the embryos and fish larvae at early stages, suggesting that the skeletal development in golden pompano initiated before yolk re-sorption completion. Fish fed non-enriched Artemia nauplii ended up with higher jaw malformation. The highest specific growth rate was obtained when fish were fed with the Artemia nauplii enriched with Algamac 3080, and the lowest growth rate was observed when fish were fed with unenriched Artemia nauplii. The highest survival was obtained when fish were fed with non-enriched or Nannochloropsis-enriched Artemia nauplii. This study indicates that the use of enriched formula for Artemia nauplii can significantly affect the expression levels of RXRs and jaw malformation of golden pompano larvae, but there is no clear correlation between RXRs expressions and malformation rates when fish are subjected to nutrient challenge.

Effects of prey color, wall color and water color on food ingestion of larval orange-spotted grouper Epinephelus coioides (Hamilton, 1822)

Effects of prey color, wall color and water color on the food ingestion of orange-spotted grouper Epinephelus coioides larvae were studied under a laboratory condition. The food ingestion of fish larvae was significantly affected by wall color. The highest food ingestion was observed when fish were stocked in white containers, while the lowest food ingestion occurred in black containers. Fish larvae ingested significantly more green-stained rotifers than red- and purple-stained rotifers. Furthermore, the number of rotifers ingested by fish in Nannochloropsis-colored rotifers was significantly higher than fish ingesting artificially stained green rotifers. This study indicates that orange-spotted grouper larvae prefer green food particle and ingest more food in white containers. Nanochloropsis is a suitable additive in the tank to produce green rotifers that are preferred by fish larvae.

Gene expression of bone morphogenetic proteins and jaw malformation in golden pompano Trachinotus ovatus larvae in different feeding regimes

ABSTRACT To explore the molecular response of fish larvae to nutritional manipulation, the partial sequences of bone morphogenetic protein (BMP1, BMP2, BMP4, BMP5, and BMP10) genes were obtained, and their expressions were quantified on golden pompano Trachinotus ovatus at 28 days post hatching. Artemia nauplii were separately enriched with Nannochloropsis and Algamac 3080, and non-enriched Artemia nauplii were used as a control feed. The lowest jaw deformity rate occurred in fish fed Algamac 3080 enriched Artemia nauplii. The expression level of BMP4 of fish fed Algamac 3080 enriched Artemia nauplii was significantly lower than those fed Nannochloropsis enriched and non-enriched Artemia nauplii. The lowest expression level of BMP10 was found in fish fed non-enriched Artemia nauplii, and the highest expression of BMP10 was observed in fish fed Algamac 3080 enriched Artemia nauplii. Correlation analysis indicates that nutritional manipulations can significantly affect the expression level of BMP4 and BMP10 genes. The concentration of dietary docosahexaenoic acid (DHA) can significantly affect the expression level of BMP10. This study indicates that the use of Algamac 3080 enriched Artemia nauplii results in fast fish growth and low jaw deformity, and BMP4 and BMP10 gene expressions were closely related to jaw deformity in golden pompano larvae.

Noble scallop, Chlamys nobilis, sperm motility duration in the post-activation phase

Sperm motility in the post-activation phase is important for conducting and assessing species-specific artificial fertilization protocols. This study characterizes spermatozoa movement of the noble scallop, Chlamys nobilis, during the post-activation phase. Sperm samples were diluted and activated by fresh seawater, and subsequently incubated at 26 °C for 4 h. Sperm movement variables including total motile sperm (TM), rapid sperm (RAP), curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP), lateral head displacement (ALH) and beat-cross frequency (BCF) after sperm activation was recorded and analyzed using the computer assisted semen analyze system. Based on the motility index (MI), the sperm movement was categorized into four groupings (twitching before full activation, full activation, twitching after full activation, and decreasing during the latter portion of the sperm motility pattern). The full activation lasted 21 min with the greatest movement characteristics except BCF, and there was no difference with twitching before full activation except for the RAP. The greatest TM was observed at 24.5 min after activation. The RAP, VCL, VSL, VAP and ALH values in the post-activation phase increased at full activation, followed by a subsequent decrease, while the BCF continued to trend downward throughout the study. This study contributes to the understanding on the sperm property of the noble scallop for gamete management, fertilization and spat production in aquaculture.

Complete mitochondrial genome of Florida pompano Trachinotus carolinus (Teleostei, Carangidae)

Abstract The complete mitochondrial genome sequence of Florida pompano Trachinotus carolinus was determined by the overlapped polymerase chain reaction. The complete mitochondrial DNA sequence is 16,544 bp in length. It consists of 13 protein-coding genes, 22 transfer RNA genes, two rRNA genes and two non-coding regions. Overall base composition of its mitochondrial genome is estimated to be 28.68% for A, 16.27% for G, 26.00% for T, 29.06% for C, respectively, with a high A+T content (54.68%). The control region contains three conserved sequence blocks, a termination-associated sequence and a TATA box. The sequence data of T. carolinus can provide useful information for the studies on population structure, molecular systematic, stock evaluation and conservation genetics. It is also helpful to develop the rational management strategies for T. carolinus resource.

The complete mitochondrial genome of snubnose pompano Trachinotus blochii (Teleostei, Carangidae).

Abstract The complete mitochondrial genome of Trachinotus blochii was determined using the polymerase chain reaction. The complete mitochondrial DNA sequence is 16,558 bp in length. It consists of 13 protein-coding genes, 22 transfer RNA genes, two rRNA genes and two non-coding regions. Overall base composition of its mitochondrial genome is estimated to be 29.21% for A, 15.74% for G, 26.49% for T, 28.56% for C, respectively, with a high A + T content (55.70%). The control region contains three conserved sequence blocks, a termination-associated sequence and a TATA box. The complete mitochondrial genome sequence of T. blochii can provide a basic data for the studies on population structure, molecular systematic, stock evaluation and conservation genetics. It is also helpful to develop the rational management strategies for T. blochii resource.

Effect of feeding Artemia nauplii enriched with different enhancement products on larval performance of golden pompano Trachinotus ovatus (Linnaeus, 1758)

This study evaluated the efficacy of Artemia nauplii enriched with three enhancement products as live feed for golden pompano Trachinotus ovatus larvae. Artemia were separately enriched with Nannochloropsis, Algamac 3080® and Spirulina and unenriched Artemia nauplii served as control feed. Growth and survival of fish larvae were affected significantly (p<0.05) by the enrichment products. Highest specific growth rate was obtained when fish were fed with Artemia nauplii enriched with Algamac 3080 and the lowest growth rate in fish fed with unenriched or spirulina enriched Artemia nauplii. Highest survival was obtained in groups fed with unenriched or Nannochloropsis enriched Artemia nauplii. Feeding with enriched Artemia nauplii also helped to reduce incidence of skeletal malformation during larval phase. Significantly lower (p<0.05) vertebral column malformation was observed when fish were fed with spirulina enriched Artemia nauplii. The highest docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) ratio in Artemia was obtained when Artemia nauplii were enriched with Algamac 3080 and the lowest in unenriched Artemia nauplii. Results of the study indicated that the enrichment protocols attempted for Artemia nauplii significantly (p<0.05) helped to enhance the growth, survival and quality of golden pompano larvae.