Effects of stocking density on reared Siberian sturgeon (Acipenser baerii) larval growth, muscle development and fatty acids composition in a recirculating aquaculture system

This study evaluated the effects of rearing density on muscle growth and development in Siberian sturgeon (Acipenser baerii) larvae. Three different stocking densities were tested: low (LD, 30 larvae/l), mid (MD, 80 larvae/l) and high (HD, 150 larvae/l) in a recirculating aquaculture system. Larvae were sampled at hatching (T0), schooling (T1) and complete yolk-sac absorption (T2) stage and were weighed and processed for muscle tissue histometrical analyses and for qualitative morphological study analyses; fatty acid profile was also determined by Gas Chromatography\u2014Flame Ionization Detector analysis. Low-density larvae presented a higher weight than MD or HD at T2 (p < 0.05). Histometrical analysis revealed that total muscle area was similar at T1 and T2, but higher than T0, while it was lower at HD at schooling (p < 0.05). The fatty acid profile revealed no differences between densities while, during development, there was a selective consumption: sparing or increasing of essential fatty acids to the detriment of their precursors. Our study suggests that lower densities appear to be more suitable to rear Siberian sturgeon in this particular stage of development. Indeed, larvae reared at the lower density were heavier and longer while larvae reared at the higher density showed lower muscle proliferation rate. As a consequence, LD larvae may exert an increase of potential growth at a mid-long term

Effects of different rearing temperatures on muscle development and stress response in the early larval stages of acipenser baerii

The present study aims at investigating muscle development and stress response in early stages of Siberian sturgeon when subjected to different rearing temperatures, by analysing growth and development of the muscle and by assessing the stress response of yolk-sac larvae. Siberian sturgeon larvae were reared at 16\uc2\ub0C, 19\uc2\ub0C and 22\uc2\ub0C until the yolk-sac was completely absorbed. Sampling timepoints were: hatching, schooling and complete yolk-sac absorption stage. Histometrical, histochemical and immunohistochemical analyses were performed in order to characterize muscle growth (total muscle area, TMA; slow muscle area, SMA; fast muscle area, FMA), development (anti-prolif erating cell nuclear antigen -PCNA or anticaspase) as well as stress conditions by specific stress biomarkers (heat shock protein 70 or 90, HSP70 or HSP90). Larvae subjected to the highest water temperature showed a faster yolk-sac absorption. Histometry revealed that both TMA and FMA were larger in the schooling stage at 19\uc2\ub0C while no differences were observed in the SMA at any of the tested rearing temperatures. PCNA quantification revealed a significantly higher number of proliferating cells in the yolk-sac absorption phase at 22\uc2\ub0C than at 16\uc2\ub0C. HSP90 immunopositivity seems to be particularly evident at 19\uc2\ub0C. HPS70 immunopositivity was never observed in the developing lateral muscle

Meniscus maturation in the swine model: role of endostatin in cellular differentiation

The development of an engineered meniscus derives from the need to regenerate a tissue which is largely unable to self-repair with consequent loss of functionality. Hence a deeper knowledge of the native meniscus morphology and biomechanics in its different regions, including molecules involved in regulation of the maturation process, is essential. The meniscus is a complex tissue, displaying great regional variation in extracellular matrix components and in vascularization, as a result of several biomechanical stimuli. Its biochemical composition is modulated to adapt the tissue to the different functions that are required throughout growth, until a \u201cmature\u201d phase is reached in adulthood. The aim of this work is to evaluate the biological role of Endostatin in the regulation of angiogenesis as in the fibro-chondrogenic differentiation of neonatal meniscal cells in the pig. The swine is an attractive model for meniscal repair studies, as its knee joint is closely comparable to the human one in terms of anatomical structure, vascularization, and healing potential. Our preliminary data show that Endostatin contributes to the acquisition of chondrocyte phenotype in an undifferentiated but committed cellular population. Thus, a better understanding of the role of Endostatin in cell metabolism might lead to a deeper knowledge of the events regulating meniscus maturation. These findings may be crucial for the development of an engineered scaffold able to induce meniscal cell differentiation by releasing Endostatin-rich microspheres

Meniscus Matrix Structural and Biomechanical Evaluation: Age-Dependent Properties in a Swine Model

The analysis of the morphological, structural, biochemical, and mechanical changes of the Extracellular Matrix (ECM), which occur during meniscus development, represents the goal of the present study. Medial fully developed menisci (FD, 9-month-old pigs), partially developed menisci (PD, 1-month-old piglets), and not developed menisci (ND, from stillbirths) were collected. Cellularity and glycosaminoglycans (GAGs) deposition were evaluated by ELISA, while Collagen 1 and aggrecan were investigated by immunohistochemistry and Western blot analyses in order to be compared to the biomechanical properties of traction and compression tensile forces, respectively. Cellularity decreased from ND to FD and GAGs showed the opposite trend (p &lt; 0.01 both). Collagen 1 decreased from ND to FD, as well as the ability to resist to tensile traction forces (p &lt; 0.01), while aggrecan showed the opposite trend, in accordance with the biomechanics: compression test showed that FD meniscus greatly resists to deformation (p &lt; 0.01). This study demonstrated that in swine meniscus, clear morphological and biomechanical changes follow the meniscal maturation and specialization during growth, starting with an immature pattern (ND) to the mature organized meniscus of the FD, and they could be useful to understand the behavior of this structure in the light of its tissue bioengineering

How different rearing temperatures affect growth and stress status of Siberian sturgeon Acipenser baerii larvae

Environmental temperature is one of the critical factors affecting fish development. The aim of this study was to examine the impact of three different rearing temperatures (16, 19 and 22\ub0C) throughout the endogenous feeding phase of the Siberian sturgeon Acipenser baerii. This was performed by assessing (a) larval survival and growth; (b) immunofluorescence localization and expression of genes involved in muscle development and growth - myog and Igf1; and (c) stress status through the expression of thermal stress genes - Hsp70, Hsp90\u3b1 and Hsp90\u3b2 - and whole body cortisol. Overall survival rate and larval weight did not differ significantly across temperatures. Larvae subjected to 22\ub0C showed faster absorption of the yolk-sac than larvae subjected to 19 or 16\ub0C. Both at schooling and at the end of the trial, larvae reared at 16\ub0C showed significantly lower levels of cortisol than those reared at 19 or 22\ub0C. IGF-1 immunopositivity was particularly evident in red muscle at schooling stage in all temperatures. The expression of all Hsps as well as the myog and Igf1 genes was statistically higher in larvae reared at 16\ub0C but limited to the schooling stage. Cortisol levels were higher in larvae at 22\ub0C, probably because of the higher metabolism demand rather than a stress response. The observed apparent incongruity between Hsps gene expression and cortisol levels could be due to the lack of a mature system. Further studies are necessary, especially regarding the exogenous feeding phase, in order to better understand if this species is actually sensitive to thermal stress

Effect of temperature on fatty acid composition and development of unfed Siberian sturgeon (A. baerii) larvae

The fatty acid metabolism in fish is influenced by various factors, including fish species, water temperature, water environment and diet supply. The aim of present work is to investigate the fatty acid composition of yolk-stage Siberian sturgeon larvae reared at three different temperatures. Fertilized Siberian sturgeon eggs were transferred to the Lodi Aquaculture Research Center of the University of Milan, divided in three aquaria, each containing three incubators and incubated at 16\ub0C. After hatching the temperature was switched to 16, 19 and 22\ub0C. Larvae sampling was performed at the end of yolk sac reabsorption. No feed was dispensed during the trial. Eggs and larvae were weighed and fatty acid profile was determined by GC-FID analysis after lipid extraction by chloroform/methanol mixture and fatty acid transesterification by methanolic hydrogen chloride. The fertilized eggs had a weight of 23.27 mg and a lipid content of 2.67 mg/egg. At hatching, the weight was 12.2 (0.17 SD) mg and lipid content 1.9 (0.6 SD) mg/larva. At the end of the trial, larvae mean weight was 33.6 (3.6 SD), 34.7 (1.8 SD) and 36.9 (1.1 SD) mg, while lipid content was 2.0 (0.3 SD), 2.1 (0.3 SD) and 2.0 (0.2 SD) mg for larvae reared at 16, 19 and 22\ub0C respectively, without statistically significant difference. Larvae subjected to the highest water temperature showed a faster yolk-sac absorption. No differences were found across temperatures regarding survival rates and regarding ontogenic development. The fatty acid composition of larvae was affected by the temperature. Larvae reared at 16\ub0C had the lowest amount of saturated fatty acids, mainly due to a lower palmitic acid content, that was offset by a higher level of linolenic and linoleic acid, if compared with larvae reared at 19\ub0C and 22\ub0C. The study suggests that at a lower temperature sturgeon spare unsaturated fatty acid consuming preferably saturated fatty acids, increasing our knowledge of the fatty acid metabolism in this species

Characterization of Differentiated SH-SY5Y as Neuronal Screening Model Reveals Increased Oxidative Vulnerability

The immortalized and proliferative cell line SH-SY5Y is one of the most commonly used cell lines in neuroscience and neuroblastoma research. However, undifferentiated SH-SY5Y cells share few properties with mature neurons. In this study, we present an optimized neuronal differentiation protocol for SH-SY5Y that requires only two work steps and 6 days. After differentiation, the cells present increased levels of ATP and plasma membrane activity but reduced expression of energetic stress response genes. Differentiation results in reduced mitochondrial membrane potential and decreased robustness toward perturbations with 6-hydroxydopamine. We are convinced that the presented differentiation method will leverage genetic and chemical high-throughput screening projects targeting pathways that are involved in the selective vulnerability of neurons with high energetic stress levels

Environmental temperature variation on reared Acipenser baerii yolk-sac larvae: effect on cortisol and IGF-1 skeletal muscle fibres.

In the present study, Siberian sturgeon (Acipenser baerii) larvae were subjected to 16\ub0C, 19\ub0C and 22\ub0C from hatching until the yolk-sac was completely absorbed. Sampling was performed at hatching, schooling and complete yolk-sac absorption stage. Larval development length, survival rate, somatic growth, whole body cortisol and IGF-1 expression were assessed at the same developmental stage for each temperature, in order to evaluate the impact of temperature during the endogenous feeding phase in this species.. Larvae subjected to 22\ub0C showed a faster absorption of the yolk-sac than larvae subjected to 19\ub0C or larvae subjected to 16\ub0C. There were no significant differences across temperatures regarding overall survival rate Larval weight significantly increased from one stage of development to the other. Until the schooling stage, there were no differences concerning larval weight but, at the yolk- sac full absorption stage, larvae reared at 16\ub0C weighed significantly more than those reared at 19\ub0C (P <.0.05). Whole body cortisol significantly increased from schooling to the yolk-sac absorption stage. At schooling, larvae reared at 16\ub0C showed a lower level of cortisol than those reared at 19\ub0C or 22\ub0C (P < 0.05). Also at the end of the trial larvae reared at 16\ub0C presented lower cortisol levels than those reared at 19\ub0C or 22\ub0C, but these differences were highly significant (P < 0.01). IGF-1 immunopositivity was particularly evident at 16\ub0C than at 19\ub0C or 22\ub0C both in schooling and in the yolk-sac absorption stage. These results suggest that larvae in this stage of development are sensitive to temperature regimes and that cooler temperatures could be more suitable for larval development. It appears, indeed, that lower temperatures in this phase of development of Siberian sturgeon larvae may have a positive effect on growth and that higher temperatures may lead to a stress response