Discovery of prolactin-like in lamprey: Role in osmoregulation and new insight into the evolution of the growth hormone/prolactin family.

We used a representative of one of the oldest extant vertebrate lineages (jawless fish or agnathans) to investigate the early evolution and function of the growth hormone (GH)/prolactin (PRL) family. We identified a second member of the GH/PRL family in an agnathan, the sea lamprey (). Structural, phylogenetic, and synteny analyses supported the identification of this hormone as prolactin-like (PRL-L), which has led to added insight into the evolution of the GH/PRL family.

Roles of leptin in initiation of acquired growth hormone resistance and control of metabolism in rainbow trout.

Catabolic conditions often induce concomitant changes in plasma leptin (Lep), growth hormone (GH), and insulin growth factor I (IGF-I) levels in teleost fish, but it is unclear whether these parts of the endocrine system are responding independently or functionally linked. In this study, fasted rainbow trout was used to study the effects of Lep on the GH-IGF-I system and metabolism. Fish were implanted intraperitoneally with recombinant rainbow trout Lep pellets and remained unfed.

Divergent genes encoding the putative receptors for growth hormone and prolactin in sea lamprey display distinct patterns of expression.

Growth hormone receptor (GHR) and prolactin receptor (PRLR) in jawed vertebrates were thought to arise after the divergence of gnathostomes from a basal vertebrate. In this study we have identified two genes encoding putative GHR and PRLR in sea lamprey (Petromyzon marinus) and Arctic lamprey (Lethenteron camtschaticum), extant members of one of the oldest vertebrate groups, agnathans. Phylogenetic analysis revealed that lamprey GHR and PRLR cluster at the base of gnathostome GHR and PRLR clades, respectively.

The Impact of Initial Energy Reserves on Growth Hormone Resistance and Plasma Growth Hormone-Binding Protein Levels in Rainbow Trout Under Feeding and Fasting Conditions.

The growth hormone (GH)-insulin-like growth factor I (IGF-I) system regulates important physiological functions in salmonid fish, including hydromineral balance, growth, and metabolism. While major research efforts have been directed toward this complex endocrine system, understanding of some key aspects is lacking. The aim was to provide new insights into GH resistance and growth hormone-binding proteins (GHBPs).

Impaired central leptin signaling and sensitivity in rainbow trout with high muscle adiposity.

The hormone leptin has been identified in all vertebrate classes, but its physiological roles in non-mammalian vertebrates are not well defined. To elucidate leptin regulation in energy homeostasis in a teleost fish species, this study compares hypothalamic and pituitary leptin signaling systems in energetically divergent rainbow trout lines selected for low (lean line, LL) and high (fat line, FL) muscle adiposity under feeding and starvation conditions. In fed fish, hypothalamic gene expression and protein density of the full-functional leptin receptor (LepRL), as well as a leptin binding protein (LepBP) expression, are lower in FL than LL fish.

Energy stores, lipid mobilization and leptin endocrinology of rainbow trout.

The physiological role of leptin in fish is not fully elucidated. In the present study, the involvement of the leptin system in lipid deposition and mobilization in rainbow trout during feeding and 1, 2 and 4 weeks of fasting was investigated in two lines of rainbow trout with different muscle and visceral adiposity: a fat line (FL) with high total energy reserves, high muscle adiposity, but low visceral adiposity and a lean line (LL) with lower total energy reserves and lower muscle adiposity, but higher visceral adiposity. During 4 weeks of fasting, muscle lipids decreased by 63 % in the FL fish, while no such energy mobilization from muscle occurred in the LL fish.

Acute anorexigenic action of leptin in rainbow trout is mediated by the hypothalamic Pi3k pathway.

Leptin (Lep) is an anorexigenic hormone and regulates appetite-related neuropeptides in mammals. A number of neuropeptides have also been linked to appetite regulation in teleost fish, but Lep signaling activation and effects on appetite-regulating neurons are poorly elucidated in early vertebrates. This study uses cellular, tissue and organismal approaches to elucidate the acute, central Lep action in rainbow trout.

Leptin signaling in the rainbow trout central nervous system is modulated by a truncated leptin receptor isoform.

Central leptin (Lep) signaling is important in control of appetite and energy balance in mammals, but information on Lep signaling and physiological roles in early vertebrates is still lacking. To elucidate fish Lep signaling activation and modulation, a long-form Lep receptor (LepRL) and a truncated LepR (LepRT) are functionally characterized from rainbow trout. The receptors generated in alternatively splicing events have identical extracellular and transmembrane domains but differ in the intracellular sequence, both in length and identity.

Ocean acidification and host-pathogen interactions: blue mussels, Mytilus edulis, encountering Vibrio tubiashii.

Ocean acidification (OA) can shift the ecological balance between interacting organisms. In this study, we have used a model system to illustrate the interaction between a calcifying host organism, the blue mussel Mytilus edulis and a common bivalve bacterial pathogen, Vibrio tubiashii, with organisms being exposed to a level of acidification projected to occur by the end of the 21st century. OA exposures of the mussels were carried out in relative long-term (4 months) and short-term (4 days) experiments.

Long-term fasting in the anadromous Arctic charr is associated with downregulation of metabolic enzyme activity and upregulation of leptin A1 and SOCS expression in the liver.

The life strategy of the anadromous Arctic charr (Salvelinus alpinus) includes several months of voluntary fasting during overwintering in freshwater, leading to emaciation prior to seawater migration in spring. In this study we compared changes in condition, substrate utilization and liver metabolism between captive anadromous charr subjected to food deprivation during late winter and spring, and conspecifics fed in excess. In March, nine out of the 10 sampled fed fish had not eaten, indicating that they were in a voluntary anorexic state.

Alternative splice variants of the rainbow trout leptin receptor encode multiple circulating leptin-binding proteins.

In mammals, leptin (Lep) binding proteins (LepBPs) derived from Lep receptor (LepR) gene or protein bind most of the circulating Lep, but to date, information on LepBPs in nonmammalian vertebrate classes is lacking. This study details the characterization of multiple LepBPs in rainbow trout (Oncorhynchus mykiss), an early poikilothermic vertebrate, and presents the complete coding sequences for 3 of them. Size-exclusion chromatography and cross-linking assay identified plasma proteins bound to Lep ranging from 70 to 100 kDa.

Biosilicification of loricate choanoflagellate: organic composition of the nanotubular siliceous costal strips of Stephanoeca diplocostata.

Loricate choanoflagellates (unicellular, eukaryotic flagellates; phylum Choanozoa) synthesize a basket-like siliceous lorica reinforced by costal strips (diameter of approximately 100 nm and length of 3 μm). In the present study, the composition of these siliceous costal strips is described, using Stephanoeca diplocostata as a model. Analyses by energy-dispersive X-ray spectroscopy (EDX), coupled with transmission electron microscopy (TEM), indicate that the costal strips comprise inorganic and organic components.

Cloning and characterization of the activin like receptor 1 homolog (Pf-ALR1) in the pearl oyster, Pinctada fucata.

The signal transduction mechanisms in mollusks are still elusive since the genome information is incomplete and cell lines are not available. In previous study, we cloned a highly conserved Smad3 homolog (designated as Pf-Smad3) from the pearl oyster, Pinctada fucata. It seems that transforming growth factor beta (TGFbeta) signaling may play similar roles in the oyster as in vertebrate.

Cloning and characterization of Prisilkin-39, a novel matrix protein serving a dual role in the prismatic layer formation from the oyster Pinctada fucata.

Molluscs form their shells out of CaCO(3) and a matrix of biomacromolecules. Understanding the role of matrices may shed some light on the mechanism of biomineralization. Here, a 1401-bp full-length cDNA sequence encoding a novel matrix protein was cloned from the mantle of the bivalve oyster, Pinctada fucata.

Immunolocalization of matrix proteins in nacre lamellae and their in vivo effects on aragonitic tablet growth.

How matrix proteins precisely control the growth of nacre lamellae is an open question in biomineralization research. Using the antibodies against matrix proteins for immunolabeling and in vivo experiments, we investigate the structural and functional roles of EDTA-soluble matrix (SM) and EDTA-insoluble matrix (ISM) proteins in nacre biomineralization of the pearl oyster Pinctada fucata. Immunolabeling reveals that a SM protein, nacrein, distributes within aragonitic tablets and intertabular matrix.

Culture of outer epithelial cells from mantle tissue to study shell matrix protein secretion for biomineralization.

Mantle tissue plays an important role in shell biomineralization by secreting matrix proteins for shell formation. However, the mechanism by which it regulates matrix protein secretion is poorly understood, largely because of the lack of cellular tools for in vitro study and techniques to evaluate matrix protein secretion. We have isolated the outer epithelial cells of the mantle of the pearl oyster, Pinctada fucata, and evaluated cellular metabolism by measuring the secretion of the matrix protein, nacrein.

Characterization of calcium deposition and shell matrix protein secretion in primary mantle tissue culture from the marine pearl oyster Pinctada fucata.

In this study, we established and characterized a long-term primary mantle tissue culture from the marine pearl oyster Pinctada fucata for in vitro investigation of nacre biomineralization. In this culture system, the viability of mantle tissue cells lasted up to 2 months. The tissue cells were demonstrated to express nacre matrix proteins by RT-PCR, and a soluble shell matrix protein, nacrein, was detected in the culture medium by Western blot analysis.

N40, a novel nonacidic matrix protein from pearl oyster nacre, facilitates nucleation of aragonite in vitro.

A novel nonacidic matrix protein from pearl oyster nacre has been purified by cation-exchange chromatography. It was designated N40 for the nacreous protein of approximately 40 kDa. On the basis of the extraction method (with Tris-buffered Milli-Q water) and amino acid compositions (Gly- and Ala-rich), N40 was inferred to be a conventional "insoluble matrix protein".

Cloning, characterization and expression analysis of calcium channel beta subunit from pearl oyster (Pinctada fucata).

The absorption, transport and localization of calcium underlie the basis of biomineralization, and Ca(2+) entry into epithelial cell is the primary step in shell formation. However, the related mechanism of Ca(2+) transport is poorly documented at the gene or protein level. L-type voltage-dependent calcium channels may be involved in calcium transport for biomineralization in some marine invertebrates.

Characterization of a thermostable alkaline phosphatase from a novel species Thermus yunnanensis sp. nov. and investigation of its cobalt activation at high temperature.

A thermostable alkaline phosphatase with high specific activity and thermal resistance was purified from a novel species of Thermus sp. named as Thermus yunnanensis sp. nov.