Male-specific protein (MSP): a new gene linked to sexual behavior and aggressiveness of tilapia males

The Immune Functions of α1 Acid Glycoprotein

α1-acid glycoprotein (orosomucoid, AGP) is an Acute Phase Protein produced by liver and peripheral tissues in response to systemic reaction to inflammation. AGP functions have been studied mostly in human, cattle and fish, although the protein has been also found in many mammalian species and birds. AGP fulfils at least two set of functions, which are apparently different from each other but in fact intimately linked. On one hand, AGP is an immunomodulatory protein. On the other hand, AGP is one of the most important binding proteins in plasma and, beside modulating pharmacokinetics and pharmacodynamics of many drugs, it is also able to bind and transport several endogen ligands related to inflammation. The focus of this review is the immunomodulatory activity of AGP. This protein regulates every single event related to inflammation, including binding of pathogens and modulating white blood cells activity throughout the entire leukocyte attacking sequence. The regulation of AGP activity is complex: the inflammation induces not only an increase in AGP serum concentration, but also a qualitative change in its carbohydrate moiety, generating a multitude of glycoforms, each of them with different, and sometimes opposite and contradictory, activities. We also present the most recent findings about the relationship between AGP and adipose tissue: AGP interacts with leptin receptor and, given its immunomodulatory function, it may be included among the potential players in the field of immunometabolism.

Prostate cancer susceptibility and growth linked to Y chromosome genes

The role of Y chromosome in prostate cancer progression and incidence is not well known. Among the 46 chromosomes, Y chromosome determines the male gender. The Y chromosome is smaller than the X chromosome and contains only 458 genes compared to over 2000 genes found in the X chromosome. The Y chromosome is prone to high mutation rates, created exclusively in sperm cells due to the highly oxidative environment of the testis. Y chromosome harbors epigenetic information, which affects the expression of genes associated with the incidence and progression of prostate cancer. In this review, we focus on Y chromosome related genetic abnormalities, likely to be involved in the development and progression of prostate cancer.

Characterization and evolutionary analysis of tributyltin-binding protein and pufferfish saxitoxin and tetrodotoxin-binding protein genes in toxic and nontoxic pufferfishes

Understanding the evolutionary mechanisms of toxin accumulation in pufferfishes has been long-standing problem in toxicology and evolutionary biology. Pufferfish saxitoxin and tetrodotoxin-binding protein (PSTBP) is involved in the transport and accumulation of tetrodotoxin and is one of the most intriguing proteins related to the toxicity of pufferfishes. PSTBPs are fusion proteins consisting of two tandem repeated tributyltin-binding protein type 2 (TBT-bp2) domains. In this study, we examined the evolutionary dynamics of TBT-bp2 and PSTBP genes to understand the evolution of toxin accumulation in pufferfishes. Database searches and/or PCR-based cDNA cloning in nine pufferfish species (6 toxic and 3 nontoxic) revealed that all species possessed one or more TBT-bp2 genes, but PSTBP genes were found only in 5 toxic species belonging to genus Takifugu. These toxic Takifugu species possessed two or three copies of PSTBP genes. Phylogenetic analysis of TBT-bp2 and PSTBP genes suggested that PSTBPs evolved in the common ancestor of Takifugu species by repeated duplications and fusions of TBT-bp2 genes. In addition, a detailed comparison of Takifugu TBT-bp2 and PSTBP gene sequences detected a signature of positive selection under the pressure of gene conversion. The complicated evolutionary dynamics of TBT-bp2 and PSTBP genes may reflect the diversity of toxicity in pufferfishes.

Localization and possible function of nrF-AGP, an alpha-1-acid glycoprotein-like protein in viviparous fish Neoditrema ransonnetii (Perciformes, Embiotocidae)

The nrF-AGP, a 51-kDa acidic glycoprotein found in surfperch (Neoditrema ransonnetii; Perciformes, Embiotocidae), is a member of the lipocalin superfamily. nrF-AGP is the major component in ovarian cavity fluid (OCF), but not in plasma of pregnant females, which suggests its potential relevance in pregnancy. However, its production in the liver, irrespective of reproductive cycle and sex, indicates that the protein also has physiological functions other than its contribution to reproduction. In the present study, Western blot analysis indicated that this protein is widely distributed in the cutaneous and intestinal mucosa, bile, and abdominal adipose tissue of fish, as well as plasma and OCF. Immunohistochemical staining of nrF-AGP was observed in hepatocytes, adipocytes, pancreatic cells, epidermal cells, and epithelial cells of ovigerous lamellae. Transcripts were detected in adipose tissue as well as hepatocytes by reverse transcription PCR analysis. This broad distribution of nrF-AGP suggests that this protein participates in various biological processes through its ability to bind to hydrophobes. After administration of biotinylated F-AGP into the ovarian cavity, the protein was detected in the cytoplasm of the intestinal epithelial cells of the fetus within 4 h. This suggests that nrF-AGP in the ovarian cavity acts as a transporter delivering maternal resources to the fetus.

RT-PCR- and MALDI-TOF mass spectrometry-based identification and discrimination of isoforms homologous to pufferfish saxitoxin- and tetrodotoxin-binding protein in the plasma of non-toxic cultured pufferfish (Takifugu rubripes)

Four genes of Takifugu rubripes, tentatively designated Tr1-Tr4, encoding homologs of pufferfish saxitoxin- and tetrodotoxin-binding protein, were identified by BLAST search and 3'-RACE. RT-PCR and MALDI-TOF mass spectrometry allowed the identification and discrimination of Tr isoforms from the non-toxically cultured specimens. The expression of Tr1 and Tr3 mRNAs exclusively in the liver and the presence of their products as 120-kDa plasma proteins were confirmed.

The social status of the male Nile tilapia (Oreochromis niloticus) influences testis structure and gene expression

Dominant and territorial behaviour are known social phenomena in cichlids and social stress influences reproduction and growth. The gonadotropic hormones trigger spermatogenesis and subordinate males have typically lower levels of gonadotropins than dominant males. In this study, we compared testis morphology and gene expression of dominant and subordinate Nile tilapia males (d- and s-males) in socially stable communities. The d-males had the highest gonadosomatic index but they were not the largest animals in the majority of studied cases. Long-term d-males showed large groups of Leydig cells and hyperplasia of the tunica albuginea due to numerous cytochrome-P450-11β-hydroxylase (Cyp11b) expressing myoid cells. Increased Cyp11b expression in d-males was reflected by elevated 11-ketotestosterone plasma values. However, immunofluorescence microscopy and expression analysis of selected genes revealed that most s-males conserved their capability for spermatogenesis and are, therefore, ready for reproduction when the social environment changes. Moreover, in s-males gene expression analysis by quantitative RT-PCR showed increased transcript levels for germ line-specific genes (vasa,sox2anddmc1) and Sertoli-specific genes (amh,amhrIIanddmrt1) whereas gene expression of key factors for steroid production (sf1andcyp11b) were reduced. The Nile tilapia is a promising model to study social cues and gonadotropic signals on testis development in vertebrates.

Tributyltin-binding protein type 1, a lipocalin, prevents inhibition of osteoblastic activity by tributyltin in fish scales

Tributyltin-binding protein type 1 (TBT-bp1) is a member of the lipocalin family of proteins which bind to small hydrophobic molecules. In this study, we expressed a recombinant TBT-bp1 (rTBT-bp1, ca. 35kDa) in a baculovirus expression system and purified the protein from the hemolymph of silkworm larvae injected with recombinant baculovirus. After incubation of a mixture of rTBT-bp1 and TBT and its fractionation by means of gel filtration chromatography, TBT was detected in the elution peak of rTBT-bp1, confirming the binding potential of rTBT-bp1 for TBT. An assay of the ability of rTBT-bp1 or native TBT-bp1 (nTBT-bp1) to restore osteoblastic activity inhibited by TBT showed that co-treatment of the scales with rTBT-bp1 or nTBT-bp1 in combination with TBT restored osteoblastic activity in goldfish scales, whereas treatment with TBT alone significantly inhibited osteoblastic activity. These results suggest that TBT-bp1 as a lipocalin member might function to decrease the toxicity of TBT by binding to TBT.

A transcriptomic scan for positively selected genes in two closely related marine fishes: Sebastes caurinus and S. rastrelliger

Comparative genomic analyses can provide valuable insight into functional evolutionary divergence among closely related species. Here we employ a comparative evolutionary analysis of expressed sequence tags (ESTs) from two closely related species of marine fishes (genus Sebastes--rockfish). Sebastes is a highly diverse group of marine fishes that inhabit a wide array of marine habitats and the study of this group can provide insights into speciation in the marine environment. ESTs were developed for S. caurinus (23,668 from brain, kidney, and spleen tissues) and S. rastrelliger (11,207 from brain and pituitary tissues). Following assembly we were able to identify, with high confidence, 257 orthologous sequence pairs between the two species through a reciprocal best hit blast search. An analysis of functional divergence between orthologs revealed that 19.46% had Ka/Ks values greater than 0.5 and 8.17% had Ka/Ks values greater than one, identifying a large pool of candidate genes to further study adaptive divergence in the group. Genes with elevated Ka/Ks values belonged to the following functional categories: immune function, metabolism, longevity, and reproductive behavior, indicating that adaptive divergence in these functional groups may be important in the diversification of this group of fishes. This study provides the ground work to better understand the molecular evolution of genes involved in a radiation of marine fishes.

Purification and characterization of tributyltin-binding protein of tiger puffer, Takifugu rubripes

We successfully purified Trub.TBT-bpα, a tributyltin (TBT) binding protein (bp) of the tiger puffer, Takifugu rubripes. Tiger puffer was injected intraperitoneally with TBT (1.0mg/kg body weight) and Trub.TBT-bpα was purified from serum by ammonium sulfate fractionation, gel filtration chromatography and polyacrylamide gel electrophoresis. Gel electrophoresis revealed that the Trub.TBT-bpα has a molecular mass of approximately 48.5kDa and contains at least 40% N-glycan. The deduced 212 amino acid sequence of the protein showed the highest identity (41%, 212 amino acid overlap and E-value: 9e-42) with TBT-binding protein type 1 (TBT-bp1) of Paralichthys olivaceus (Japanese flounder). Analysis of the gene structure of Trub.TBT-bpα suggests that this protein belongs to the lipocalin superfamily, which may be important in the accumulation and elimination of TBT. Phylogenetic analysis suggests that functionalization of TBT-bps has occurred during evolution, and that the functions of this group of proteins might be important for fish survival.

An alpha-1-acid glycoprotein-like protein as a major component of the ovarian cavity fluid of viviparous fish, Neoditrema ransonnetii (Perciformes, Embiotocidae)

Developing fetuses of surfperch (Neoditrema ransonnetii, Perciformes; Embiotocidae) are retained in the ovarian cavity until birth, where they are surrounded by ovarian cavity fluid (OCF). Expecting the OCF to have key roles in maintaining pregnancy, we purified and characterized a major glycoprotein of 51 kDa in the OCF of surfperch. On the basis of the N-terminal amino acid sequence, we cloned and sequenced a full-length cDNA. The deduced sequence comprises 214 amino acids (aa) including a signal peptide of 20 aa and a mature protein of 194 aa. This protein had an extremely low pI (below 2.8) and extraordinarily high glycosylation rate (more than 50%), characteristics being shared with alpha-1-acid glycoprotein (AGP), a member of the lipocalin superfamily. A homology search and phylogenetic analysis indicated that the 51 kDa protein and tributyltin-binding protein found in Japanese flounder are the closest known relatives of AGP. We therefore named the protein nrF-AGP. Messenger RNA of nrF-AGP was expressed intensively in the liver, but not at all in the ovarian tissue. Because nrF-AGP is the most salient component in OCF but not in plasma, we reasoned that it was selectively sequestered from blood to the ovarian cavity in pregnant females, and consequently, plays crucial roles in pregnancy.