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

A novel hyaluronic acid hydrogel as an extracellular matrix to improve graft survival in autologous adipose tissue transfer

Introduction Adipose tissue transfer is used for correcting breast defects after cancer surgery and reconstruction after trauma or congenital defects. Graft survival can be as poor as 15%. Modified hyaluronic acid (HA) hydrogels can be used to suspend adipocytes to aid survival. The study aims were to synthesise a HA hydrogel with robust mechanical properties to support injection, and to assess adipocyte viability with HA hydrogel in vitro and in vivo. Methods A HA hydrogel with cross-linked aldehyde and hydrazine groups allowing self-healing around cells was engineered, with rheology and degradation properties characterised. Per2-dLuc 3T3-L1 murine pre-adipocytes expressing luciferase, CAG-luc-eGFP murine and human adipocytes were grown under, on, and encapsulated within HA hydrogel, with cell survival and gene expression investigated. A murine animal model underwent subcutaneous injection of primary murine adipocytes mixed with HA hydrogel, with cell survival and gene expression of mature adipocyte markers investigated. Results HA hydrogel can be degraded by tissue hyaluronidases in 4-5 days. Self-healing occurred in 30 minutes and is robust enough to resist deformation forces. Per2-dLuc 3T3-L1 and CAG-luc-eGFP murine adipocytes were encapsulated within HA hydrogel and showed a <15% reduction in photon emission compared to control. Mature adipocyte markers gene expression levels in HA hydrogel encapsulated murine and human cells were similar to those of control (no HA hydrogel) cells. Primary murine adipocytes injected subcutaneously with HA hydrogel in wild type mice showed no difference in survival at higher gel volumes compared to control. Gene expression markers of differentiation in injected primary adipocytes mixed with HA hydrogel showed no difference compared to control cells. Conclusion The novel engineered HA hydrogel has suitable mechanical characteristics for injection and can support adipocyte survival in vitro and in vivo. A human pilot trial may be the next step in development of the novel HA hydrogel