Table 1.
Sequences of the primers and probes used in this study.
Figure 1.
The structures of Tgfbr1 gene and Tgfbr1 protein in Zhikong scallop.
The gene contains 10 exons. The 3′ and 5′ UTR (untranslated region, pink), and exons encoding the amino acid sequences (blue) are shown relative to their lengths in the cDNA sequences obtained. The position of the SNP c. 1815 C>T in the 3′ UTR is indicated with a star. Protein domains are shown relative to their lengths and positions in the amino acid sequences. SP, signal peptide (gray); TM, transmembrane domain (orange); GS, SGSGSG motif (purple); ABR, ATP binding region (yellow); L45, L45 loop (red); KD, kinase domain (green).
Figure 2.
Phylogenetic analysis of scallop Tgfbr1 and other TGF-β superfamily receptors.
This tree was built by the neighbor-joining method. Aligned sequences were bootstrapped 1000 times, and the numbers at the forks indicate the bootstrap proportions. The protein sequences used for phylogenetic analysis include the following: Chlamys farreri Tgfbr1 (JQ366030), Crassostrea gigas Tgfbr1 (CAD20573), Homo sapiens Tgfbr1 (CAF02096.2), Rattus norvegicus Tgfbr1 (AAA83216.1), Danio rerio Tgfbr1a (ABR20509.1), D. rerio Tgfbr1b (ABR20510.1), H. sapiens Acvr1b (AAH40531.1), H. sapiens Acvr1c (AAH22530.1), Drosophila melanogaster Baboon (AAF59011), C. gigas Bmpr1b (CAE11917), H. sapiens Bmpr1a (EAW80320.1), D. rerio Bmpr1a (AAI63471.1), H. sapiens Bmpr1b (AAH47773.1), D. rerio Bmpr1b (AAH81625.1), D. melanogaster Thickveins (XP_079689), C. gigas Alr1 (AJ309316), Pinctada fucata Alr1 (ADD80738.1), H. sapiens Acvr1 (AAH33867.1), D. rerio Acvr1 (AAI62317.1), H. sapiens Alk1 (CAA80255.1), D. rerio Acvrl1 (AAI00044), D. melanogaster Saxophone (AAA28878), H. sapiens Acvr2b (AAH96245.1), D. rerio Acvr2b (AAI64219.1), C. gigas Actr2 (CAR92545.1), D. melanogaster Punt (AAC41566), H. sapiens Bmpr2 (AAH52985.1), C. gigas Tgfbr2 (CAD20574), D. melanogaster Wishful thinking (AAF47832.1).
Figure 3.
Molecular model of the three-dimensional structure of the kinase domain of scallop Tgfbr1 (A) and human Tgfbr1 (B).
Cylinders and flat arrows represent α helices and β sheets, respectively. Conserved structures were found in the kinase domains of scallop Tgfbr1 and human Tgfbr1; the GS domain and L45 loop are colored red and green, respectively.
Figure 4.
Multiple alignment of the scallop Tgfbr1 peptide sequence with orthologs from other species.
Identical and similar amino acids are shaded. The signal peptide (SP), transmembrane domain (TM) and serine/threonine kinase domain (KD) are indicated with the solid-line horizontal arrows above the alignment. The ten conserved cysteine residues in the extracellular domain and the GS motif in the kinase domain are indicated with bold and underlined text. The L45 loop is highlighted with the dashed-line arrows under the alignment. The exon-intron junctions within the bivalve (scallop and oyster) Tgfbr1 genes are indicated with black arrowheads. The species and the GenBank accession numbers are as follows: C. gigas (CAD20573), D. rerio (ABR20510.1), X. laevis (AAA84997.1), R. norvegicus (AAA83216.1) and H. sapiens (CAF02096.2).
Figure 5.
Spatiotemporal distribution of Tgfbr1 transcripts in Zhikong scallop.
(A) Relative expression levels of Tgfbr1 at different embryonic and larval stages. Three biological replicates (n>500 for every replicate) were performed for each developmental stage, and three technical replicates were conducted for each PCR reaction. (B) Relative expression levels of Tgfbr1 in various adult tissues (n = 6). The comparison of expression levels of Tgfbr1 among different developmental stages, and among adult tissues was performed one way ANOVA with post hoc test. Bars with different superscripts indicate significant differences (P<0.05).
Table 2.
Growth traits of Zhikong scallops in a full-sib family with respect to genotypes at SNP c. 1815C>T in the Tgfbr1 gene.
Table 3.
Growth traits of Zhikong scallops in a population with respect to genotypes at SNP c. 1815C>T in the Tgfbr1 gene.
Figure 6.
Tgfbr1 expression levels in striated muscle and the striated muscle weights in scallops with different genotypes.
For each genotype, six scallops were randomly selected. Associations of the SNP c. 1815C>T with the Tgfbr1 expression level in striated muscle (A), and the striated muscle weight (B) were tested in the 18 scallops. One way ANOVA was performed with post hoc test to compare the expression levels of Tgfbr1 among different genotypes, and the growth traits among the genotypes. Bars with different superscripts indicate significant differences (P<0.05). Pearson product-moment correlation analysis revealed inverse correlation between Tgfbr1 expression level in striated muscle and the striated muscle weight (r = −0.56, p = 0.03).