SNP discovery and High Resolution Melting Analysis from massive transcriptome sequencing in the California red abalone Haliotis rufescens

Aldolase of Mytilus galloprovincialis, Lamarck, 1819: Gene structure, tissue specificity of expression level and activity

In the present study, the structure of the fructose-1,6-bisphosphataldolase (FBA) gene in Mytilus galloprovincialis (Lamarck, 1819) was analyzed and its tissue specificity of expression level and activity was determined. A 1092 base pairs (bps) complete coding sequence of the FBA gene was assembled from M. galloprovincialis transcriptome. Only one gene encoding FBA (MgFBA) was identified in the M. galloprovincialis genome. The length of MgFBA was 363 amino acids with a molecular mass of 39.7 kDa. According to the amino acid residues, the detected MgFBA gene is a type I aldolase. The FBA gene in M. galloprovincialis had 7 exons; the maximum intron length was about 2.5 kbps. Intraspecific nucleotide diversity (15 mutations) between MgFBAs from the Mediterranean mussels and the Black Sea mussels (present study) was detected. All mutations were synonymous. Tissue specificity in FBA expression level and activity was established. No direct correlation between these functions was found. The highest level of FBA gene expression is found in muscle tissue. According to the phylogenetic analyses, FBA gene in invertebrates could be considered the ancestral gene of muscle type aldolase, which may explain the character of tissue-specific expression.

Different Transcriptomic Responses to Thermal Stress in Heat-Tolerant and Heat-Sensitive Pacific Abalones Indicated by Cardiac Performance

The Pacific abalone Haliotis discus hannai is one of the most economically important mollusks in China. Even though it has been farmed in southern China for almost 20 years, summer mortality remains the most challengeable problem for Pacific abalone aquaculture recently. Here, we determined the different heat tolerance ability for five selective lines of H. discus hannai by measuring the cardiac performance and Arrhenius breakpoint temperature (ABT). The Red line (RL) and Yangxia line (YL) were determined as the most heat-sensitive and most heat-tolerant line, respectively. Heart rates for RL were significantly lower than those of the YL at the same temperature (p < 0.05). The differentially expressed genes (DEGs), which were enriched in several pathways including cardiac muscle contraction, glutathione metabolism and oxidative phosphorylation, were identified between RL and YL at control temperature (20°C) and heat stress temperature (28.5°C, the ABT of the RL) by RNA-seq method. In the RL, 3370 DEGs were identified between the control and the heat-stress temperature, while only 1351 DEGs were identified in YL between these two temperature tests. Most of these DEGs were enriched in the pathways such as protein processing in endoplasmic reticulum, nucleotide binding and oligomerization domain (NOD) like receptor signaling, and ubiquitin mediated proteolysis. Notably, the most heat-tolerant line YL used an effective heat-protection strategy based on moderate transcriptional changes and regulation on the expression of key genes.

Seasonal changes in gene expression and polymorphism of hsp70 in cultivated oysters (Crassostrea gigas) at extreme temperatures

The HSP70 proteins are an important element of the response against thermal stress and infectious diseases, and they are highly conserved and ubiquitous. In some species, variations on the hsp70 encoding sequence resulted in intraspecific differential expression, which leads to variations on thermo-tolerance among individuals. This phenomenon has not been described in the Pacific oyster Crassostrea gigas, which is cultivated in Mexico under temperature conditions highly above the optimal for this species. The present study was aimed to identify associations between hsp70 genotypes and their expression levels in C. gigas. By analyzing a 603 bp fragment from the 3' end of the hsp70 gene, 21 different genotypes with 60 nucleotide polymorphic sites were detected, of which 34 sites were found in heterozygous condition. Although no correlation was found between genotype-expression-season, a minimum expression threshold that should be taken into account as an important feature for a future breeding program is proposed.

Involvement of Antizyme Characterized from the Small Abalone Haliotis diversicolor in Gonadal Development

The small abalone Haliotis diversicolor is an economically important mollusk that is widely cultivated in Southern China. Gonad precocity may affect the aquaculture of small abalone. Polyamines, which are small cationic molecules essential for cellular proliferation, may affect gonadal development. Ornithine decarboxylase (ODC) and antizyme (AZ) are essential elements of a feedback circuit that regulates cellular polyamines. This paper presents the molecular cloning and characterization of AZ from small abalone. Sequence analysis showed that the cDNA sequence of H. diversicolor AZ (HdiODCAZ) consisted of two overlapping open reading frames (ORFs) and conformed to the +1 frameshift property of the frame. Thin Layer chromatography (TLC) analysis suggested that the expressed protein encoded by +1 ORF2 was the functional AZ that targets ODC to 26S proteasome degradation. The result demonstrated that the expression level of AZ was higher than that of ODC in the ovary of small abalone. In addition, the expression profiles of ODC and AZ at the different development stages of the ovary indicated that these two genes might be involved in the gonadal development of small abalone.

Transcriptome profiles of wild and cultured South African abalone, Haliotis midae

This report describes the use of pyrosequencing technologies to generate the first comparative analysis of de novo assembled transcriptome data from cultured and wild specimens of the South African abalone. The transcriptome data and database described here provide a significant genomic resource for abalone research. The data set annotated 11,240 genes, which matched genes with known functions in other species. A large number of transmembrane protein domains (4087) that may indicate a high portion of undiscovered gene receptors were identified. Further, we detected an interesting set of transcription factors (516) that are valuable candidates for participating in regulatory events in developmental (such as cell proliferation and differentiation) and reproductive processes.