Effect of nanoparticle stabilization and physicochemical properties on exposure outcome: acute toxicity of silver nanoparticle preparations in zebrafish (Danio rerio).

Nanotechnology has vast potential for expanded development and novel application in numerous sectors of society. With growing use and applications, substantial production volumes and associated environmental release can be anticipated. Exposure effect of nanoparticles (NP) on biological systems may be intrinsic to their physicochemical properties introducing unknown associated risk.

Loss of plakophilin 2 disrupts heart development in zebrafish.

The desmosomal armadillo protein plakophilin 2 is the only plakophilin expressed in the heart, and mutations in the human plakophilin 2 gene result in arrhythmogenic right ventricular cardiomyopathy. To investigate loss of function, we knocked down plakophilin 2 by morpholino microinjection in zebrafish. This resulted in decreased heart rate, cardiac oedema, blood pooling, a failure of the heart to pattern correctly and a twisted tail.

Insulin-like growth factor-2 regulates early neural and cardiovascular system development in zebrafish embryos.

The insulin-like growth factor (IGF) family is essential for normal embryonic growth and development and it is highly conserved through vertebrate evolution. However, the roles that the individual members of the IGF family play in embryonic development have not been fully elucidated. This study focuses on the role of IGF-2 in zebrafish embryonic development.

Regulation of expression of zebrafish (Danio rerio) insulin-like growth factor 2 receptor: implications for evolution at the IGF2R locus.

The insulin-like growth factor 2 receptor (IGF2R) is an unusual multifunctional receptor that interacts with a diverse variety of ligands. While the receptor has been well-characterized in mammals, little is known of its biology in other vertebrates. In this report, we characterize the expression of the zebrafish (Danio rerio) ortholog of the IGF2R gene.

Plakoglobin has both structural and signalling roles in zebrafish development.

Plakoglobin, or gamma-catenin, is found in both desmosomes and adherens junctions and participates in Wnt signalling. Mutations in the human gene are implicated in the congenital heart disorder, arrhythmogenic right ventricular cardiomyopathy (ARVC), but the signalling effects of plakoglobin loss in ARVC have not been established. Here we report that knockdown of plakoglobin in zebrafish results in decreased heart size, reduced heartbeat, cardiac oedema, reflux of blood between heart chambers and a twisted tail.

Mouse induced pluripotent stem cells.

The recent discovery that it is possible to directly reprogramme somatic cells to an embryonic stem (ES) cell-like pluripotent state, by retroviral transduction of just four genes (Oct3/4, Sox2, c-Myc and Klf4), represents a major breakthrough in stem cell research. The reprogrammed cells, known as induced pluripotent stem (iPS) cells, possess many of the properties of ES cells, and represent one of the most promising sources of patient-specific cells for use in regenerative medicine. While the ultimate goal is the use of iPS cells in the treatment of human disease, much of the research to date has been carried out with murine cells, and improved mouse iPS cells have been shown to contribute to live chimeric mice that are germ-line competent.

Molecular cloning and developmental expression of plakophilin 2 in zebrafish.

Armadillo proteins are involved in providing strength and support to cells and tissues, nuclear transport, and transcriptional activation. In this report, we describe the identification and characterisation of the cDNA of the desmosomal armadillo protein plakophilin 2 in zebrafish. The 2448bp coding sequence encodes a predicted 815 amino acid protein, with nine armadillo repeats characteristic of the p120-catenin subfamily.

Molecular cloning and expression analysis of two distinct beta-glucosidase genes, bg1 and aven1, with very different biological roles from the thermophilic, saprophytic fungus Talaromyces emersonii.

Recent sequencing of a number of fungal genomes has revealed the presence of multiple putative beta-glucosidases. Here, we report the cloning of two beta-glucosidase genes (bg1 and aven1), which have very different biological functions and represent two of a number of beta-glucosidases from Talaromyces emersonii. The bg1 gene, encoding a putative intracellular beta-glucosidase, shows significant similarity to other fungal glucosidases from glycosyl hydrolase family 1, known to be involved in cellulose degradation.

Identification of zygotic genes expressed at the midblastula transition in zebrafish.

Early development of the embryo is directed by maternal gene products and characterised by limited zygotic gene activity, cell division synchrony and no cell motility in several vertebrates including fish and frogs. At the midblastula transition (MBT), zygotic transcription is grossly activated, cells become motile and cell divisions become asynchronous. The aim of this study was to identify genes whose expression is up-regulated at the MBT in zebrafish.

Mannose 6-phosphate receptors in an ancient vertebrate, zebrafish.

The endosome/lysosome system plays key roles in embryonic development, but difficulties posed by inaccessible mammalian embryos have hampered detailed studies. The accessible, transparent embryos of Danio rerio, together with the genetic and experimental approaches possible with this organism, provide many advantages over rodents. In mammals, mannose 6-phosphate receptors (MPRs) target acid hydrolases to endosomes and lysosomes, but nothing is known of acid hydrolase targeting in zebrafish.

nanor, a novel zygotic gene, is expressed initially at the midblastula transition in zebrafish.

A novel, developmentally regulated gene, nanor, was identified by suppression subtractive hybridization. It is first expressed following the midblastula transition (MBT), a critical developmental stage in the early vertebrate embryo when the zygotic genome is activated. The nanor cDNA (626bp) includes a complete open reading frame but neither the gene nor the deduced amino acid sequence shows significant similarity to any known gene or protein.

Insulin-like growth factor (IGF) signalling is required for early dorso-anterior development of the zebrafish embryo.

The insulin-like growth factor (IGF) signalling pathway has been highly conserved in animal evolution and, in mammals and Xenopus, plays a key role in embryonic growth and development, with the IGF-1 receptor (IGF-1R) being a crucial regulator of the signalling cascade. Here we report the first functional role for the IGF pathway in zebrafish. Expression of mRNA coding for a dominant negative IGF-1R resulted in embryos that were small in size compared to controls and had disrupted head and CNS development.

Three-dimensional structure of a thermostable native cellobiohydrolase, CBH IB, and molecular characterization of the cel7 gene from the filamentous fungus, Talaromyces emersonii.

The X-ray structure of native cellobiohydrolase IB (CBH IB) from the filamentous fungus Talaromyces emersonii, PDB 1Q9H, was solved to 2.4 A by molecular replacement. 1Q9H is a glycoprotein that consists of a large, single domain with dimensions of approximately 60 A x 40 A x 50 A and an overall beta-sandwich structure, the characteristic fold of Family 7 glycosyl hydrolases (GH7).

Cellular longevity: role of apoptosis and replicative senescence.

Cellular longevity refers to the lifespan of an individual cell. Normal cells have a finite lifespan and typically die by undergoing apoptosis, or enter into a state of irreversible growth arrest, termed replicative senescence, at the end of that lifespan. The lifespan of a cell is a balance between pro-survival/anti-apoptotic and pro-apoptotic death-promoting factors.

Cyclin-dependent kinase 8 is expressed both maternally and zygotically during zebrafish embryo development.

Cyclin-dependent kinase 8 (cdk8) regulates transcription by phosphorylating RNA polymerase II and TFIIH. The mechanism of zygotic transcription activation during vertebrate embryonic development is poorly understood. Here we describe the cloning and developmental expression pattern of zebrafish cdk8 mRNA.