Cardiac myoglobin deficit has evolved repeatedly in teleost fishes

Peer reviewedPublisher PD

What determines growth potential and juvenile quality of farmed fish species?

Enhanced production of high quality and healthy fry is a key target for a successful and competitive expansion of the aquaculture industry. Although large quantities of fish larvae are produced, survival rates are often low or highly variable and growth potential is in most cases not fully exploited, indicating significant gaps in our knowledge concerning optimal nutritional and culture conditions. Understanding the mechanisms that control early development and muscle growth are critical for the identification of time windows in development that introduce growth variation, and improve the viability and quality of juveniles. This literature review of the current state of knowledge aims to provide a framework for a better understanding of fish skeletal muscle ontogeny, and its impact on larval and juvenile quality as broadly defined. It focuses on fundamental biological knowledge relevant to larval phenotype and quality and, in particular, on the factors affecting the development of skeletal muscle. It also discusses the available methodologies to assess growth and larvae/juvenile quality, identifies gaps in knowledge and suggests future research directions. The focus is primarily on the major farmed non-salmonid fish species in Europe that include gilthead sea bream, European sea bass, turbot, Atlantic cod, Senegalese sole and Atlantic halibut

Growth hormone transgenesis in coho salmon disrupts muscle immune function impacting cross-talk with growth systems

Acknowledgements We thank Dwight Causey (Macqueen lab, University of Aberdeen) for providing critical comments on the manuscript. Funding AA was supported by a PhD studentship from Kuwait University. The research was supported by the Canadian Regulatory System for Biotechnology (RHD, JHK).Peer reviewedPublisher PD

Divergent regulation of insulin-like growth factor binding protein genes in cultured Atlantic salmon myotubes under different models of catabolism and anabolism

This work received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.Much attention has been given to insulin-like growth factor (Igf) pathways that regulate the balance of skeletal muscle protein synthesis and breakdown in response to a range of extrinsic and intrinsic signals. However, we have a less complete understanding of how the same signals modulate muscle mass upstream of such signalling, through a family of functionally-diverse Igf-binding proteins (Igfbps) that modify the availability of Igfs to the cell receptor Igf1r. We exposed cultured myotubes from Atlantic salmon (Salmo salar L.) to treatments recapturing three catabolic signals: inflammation (interleukin-1β), stress (dexamethasone) and fasting (amino acid deprivation), plus one anabolic signal: recovery of muscle mass post-fasting (supplementation of fasted myotubes with Igf-I and amino acids). The intended phenotype of treatments was confirmed by significant changes in myotube diameter and immunofluorescent staining of structural proteins. We quantified the mRNA-level regulation of the full expressed Igf and Igfbp gene complement across a post-treatment time course, along with marker genes for muscle structural protein synthesis, as well as muscle breakdown, via the ubiquitin-proteasome and autophagy systems. Our results highlight complex, non-overlapping responses of Igfbp family members to the different treatments, suggesting that the profile of expressed Igfbps is differentially regulated by distinct signals promoting similar muscle remodelling phenotypes. We also demonstrate divergent regulation of salmonid-specific gene duplicates of igfbp5b1 and igfbp5b2 under distinct catabolic and anabolic conditions. Overall, this study increases our understanding of the regulation of Igfbp genes in response to signals that promote remodelling of skeletal muscle.PostprintPeer reviewe

Transcriptional regulation of the IGF signaling pathway by amino acids and insulin-like growth factors during myogenesis in Atlantic salmon

The insulin-like growth factor signalling pathway is an important regulator of skeletal muscle growth. We examined the mRNA expression of components of the insulin-like growth factor (IGF) signalling pathway as well as Fibroblast Growth Factor 2 (FGF2) during maturation of myotubes in primary cell cultures isolated from fast myotomal muscle of Atlantic salmon (Salmo salar). The transcriptional regulation of IGFs and IGFBP expression by amino acids and insulin-like growth factors was also investigated. Proliferation of cells was 15% d(-1) at days 2 and 3 of the culture, increasing to 66% d(-1) at day 6. Three clusters of elevated gene expression were observed during the maturation of the culture associated with mono-nucleic cells (IGFBP5.1 and 5.2, IGFBP-6, IGFBP-rP1, IGFBP-2.2 and IGF-II), the initial proliferation phase (IGF-I, IGFBP-4, FGF2 and IGF-IRb) and terminal differentiation and myotube production (IGF2R, IGF-IRa). In cells starved of amino acids and serum for 72 h, IGF-I mRNA decreased 10-fold which was reversed by amino acid replacement. Addition of IGF-I and amino acids to starved cells resulted in an 18-fold increase in IGF-I mRNA indicating synergistic effects and the activation of additional pathway(s) leading to IGF-I production via a positive feedback mechanism. IGF-II, IGFBP-5.1 and IGFBP-5.2 expression was unchanged in starved cells, but increased with amino acid replacement. Synergistic increases in expression of IGFBP5.2 and IGFBP-4, but not IGFBP5.1 were observed with addition of IGF-I, IGF-II or insulin and amino acids to the medium. IGF-I and IGF-II directly stimulated IGFBP-6 expression, but not when amino acids were present. These findings indicate that amino acids alone are sufficient to stimulate myogenesis in myoblasts and that IGF-I production is controlled by both endocrine and paracrine pathways. A model depicting the transcriptional regulation of the IGF pathway in Atlantic salmon muscle following feeding is proposed.Publisher PDFPeer reviewe

Characterisation and expression of calpain family members in relation to nutritional status, diet composition and flesh texture in gilthead sea bream (Sparus aurata).

Calpains are non-lysosomal calcium-activated neutral proteases involved in a wide range of cellular processes including muscle proteolysis linked to post-mortem flesh softening. The aims of this study were (a) to characterise several members of the calpain system in gilthead sea bream and (b) to examine their expression in relation to nutritional status and muscle tenderisation. We identified the complete open reading frame of gilthead sea bream calpains1-3, sacapn1, sacapn2, sacapn3, and two paralogs of the calpain small subunit1, sacapns1a and sacapns1b. Proteins showed 63-90% sequence identity compared with sequences from mammals and other teleost fishes, and the characteristic domain structure of vertebrate calpains. Transcripts of sacapn1, sacapn2, sacapns1a and sacapns1b had a wide tissue distribution, whereas sacapn3 was almost exclusively detected in skeletal muscle. Next, we assessed transcript expression in skeletal muscle following alteration of nutritional status by (a) fasting and re-feeding or (b) feeding four experimental diets with different carbohydrate-to-protein ratios. Fasting significantly reduced plasma glucose and increased free fatty acids and triglycerides, together with a significant increase in sacapns1b expression. Following 7 days of re-feeding, plasma parameters returned to fed values and sacapn1, sacapn2, sacapns1a and sacapns1b expression was significantly reduced. Furthermore, an increase in dietary carbohydrate content (11 to 39%) diminished growth but increased muscle texture, which showed a significant correlation with decreased sacapn1 and sacapns1a expression, whilst the other calpains remained unaffected. This study has demonstrated that calpain expression is modulated by nutritional status and diet composition in gilthead sea bream, and that the expression of several calpain members is correlated with muscle texture, indicating their potential use as molecular markers for flesh quality in aquaculture production

The Actin Gene Family: Function Follows Isoform

Although actin is often thought of as a single protein, in mammals it actually consists of six different isoforms encoded by separate genes. Each isoform is remarkably similar to every other isoform, with only slight variations in amino acid sequence. Nevertheless, recent work indicates that actin isoforms carry out unique cellular functions. Here, we review evidence drawn from localization studies, mouse models, and biochemical characterization to suggest a model for how in vivo mixing of actin isoforms may influence cytoskeletal function in cells. © 2010 Wiley-Liss, Inc

Talking Less during Social Interactions Predicts Enjoyment: A Mobile Sensing Pilot Study

Can we predict which conversations are enjoyable without hearing the words that are spoken? A total of 36 participants used a mobile app, My Social Ties, which collected data about 473 conversations that the participants engaged in as they went about their daily lives. We tested whether conversational properties (conversation length, rate of turn taking, proportion of speaking time) and acoustical properties (volume, pitch) could predict enjoyment of a conversation. Surprisingly, people enjoyed their conversations more when they spoke a smaller proportion of the time. This pilot study demonstrates how conversational properties of social interactions can predict psychologically meaningful outcomes, such as how much a person enjoys the conversation. It also illustrates how mobile phones can provide a window into everyday social experiences and well-being