Cloning and characterization of p8 homolog cDNA in the Atlantic halibut (Hippoglossus hippoglossus)

Localization, developmental regulation and stress induction of p8-L1 and p8-L2 in zebrafish

The transcription cofactor, p8, has a basic helix-loop-helix motif and is involved in several metabolic processes. It has previously been reported that p8 plays an important role in stress response in zebrafish. We expanded on these studies to further investigate the roles of two p8-like cDNAs found in zerbrafish, p8-L1 and p8-L2. Zebrafish p8-L1 and p8-L2 cDNAs consist of 742 bp and 813 bp, respectively. Both have the same open reading frame despite different genomic structures and encode a 76 amino acid polypeptide with conserved a Phospho_p8 domain. These two cDNA’s were abundant in different tissues in the zebrafish: p8-L1 was high in intestine and muscle tissue and in low abundance in the backbone, whereas the highest amount of p8-L2 was found in the backbone, similar to p8. During embryogenesis, both p8-L1 and p8-L2 were abundant at the cleavage stage and decreased gradually in abundance from blastula to pharyngula stage. However, p8-L1 abundance increased during hatching as observed in p8. Quantitative real-time PCR assay suggested that p8-L1 and p8-L2 were both up-regulated significantly under osmotic pressure and pH value challenges, suggesting an important role of p8-L1 and p8-L2 genes in stress response.

Molecular characterization and expression of As-nurp1 gene from Artemia sinica during development and in response to salinity and temperature stress

Nuclear protein 1 (NURP1) is a stress-related protein and closely related to diapause in the development of Artemia. In the present paper, the full-length 568-bp cDNA sequence of the nurp1 homolog of Artemia sinica (As-nurp1) was isolated by RACE technology for the first time. The putative As-nurp1 protein consists of 66 amino acids with a basic helix-loop-helix (bHLH) motif and a bipartite nuclear localization signal (NLS). Multiple sequence alignments revealed that the putative As-nurp1 protein sequence was relatively conserved across species, especially in the bHLH domain. The expression of As-nurp1 is widely distributed during A. sinica development. This is followed by a dramatic downregulation after diapause and is newly upregulated from the larval nauplius stage. Furthermore, As-nurp1 transcripts are highly upregulated under conditions of high salinity and low temperature. These findings suggest that As-nurp1 is stress-related and may act as a protective factor in embryonic development.

Molecular analysis and its expression of a pou homeobox protein gene during development and in response to salinity stress from brine shrimp, Artemia sinica

Brine shrimps of the genus Artemia are aquatic species of economic importance because of their important significance to aquaculture and are used as a model species in physiology and developmental biology. Research on Artemia POU homeobox gene function will enhance our understanding of the physiological and developmental processes of POU homeobox gene in animals. Herein, a full-length cDNA encoding an Artemia POU homeobox protein gene 1 (APH-1) from Artemia sinica (designated as As-APH-1) was cloned and characterized by a reverse-transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA end (RACE) method. The As-APH-1 gene encoded a protein of 388 amino acid polypeptide with a calculated molecular mass of 42.85kDa and an isoelectric point of 6.90 and the protein belongs to the POU III family. Multiple sequence alignments revealed that A. sinica As-APH-1 protein sequence shared a conserved POU homeobox domain with other species. The early and persistent expression of As-APH-1 in the naupliar stages by semi-quantitative RT-PCR and whole-mount embryonic immunohistochemistry suggest that As-APH-1 functions very early in the salt gland and may be required continuously in this organ. Later in development, expression of As-APH-1 begins to dramatically decrease and disappear in salt gland of the sub-adult Artemia. In addition, we also discovered that As-APH-1 increased obviously as the salinity increased, indicating that As-APH-1 might be used as a good indicator of salinity stress. In summary, we are the first to identify the As-APH-1 gene and to determine its gene expression patterns in early embryogenesis stages and in different salinity stress in brine shrimp, A. sinica. The result of expression of As-APH-1 affected by salinity changes will provide us further understanding of the underlying mechanisms of osmoregulation in Artemia early embryonic development.