Juvenile Greenland halibut (Reinhardtius hippoglossoides) growth in the context of rising temperature in the Estuary and Gulf of St. Lawrence

In a context of climate change, understanding the influence of temperature on fish species growth is important for the management of fisheries. The effect of increasing temperature on the growth of juvenile Greenland halibut (Reinhardtius hippoglossoides), a cold-water species, circum-continental in the Arctic, was investigated on juveniles that had been captured in the wild and kept in captivity. Mortality rate increased with higher temperature, from 4.5 % at 4.0 °C to 15.2 % at 7.5 °C. Relative growth (normalized in degree-days) was lower at 7.5 °C than at the two other temperatures tested. Food conversion efficiency, muscle energy content, and the Fulton condition index were not influenced by temperature, but food intake significantly increased over time at 5.5 °C. No clear difference in growth trajectories between sexes was highlighted. Overall, the results suggest that optimal temperature conditions were exceeded at 7.5 °C and that any further increase in temperature would significantly decrease survival and impair juvenile growth. With the current deep-water warming trends in the Estuary and Gulf of St. Lawrence, recruitment and commercial fishing of Greenland halibut may be impaired in the near future. -- Keywords : Greenland Halibut ; Growth ; Temperature ; Juveniles ; Fisheries ; Mortality

Local, Seasonal, and Yearly Condition of Juvenile Greenland Halibut Revealed by the Le Cren Condition Index

An understanding of biological characteristics, such as growth patterns, condition, and energy reserves, is important for better understanding the environmental constraints exerted on fish populations. This is especially true for exploited fish stocks in the current context of climate change. Using biological data collected from 2006 to 2009 during bottom trawl research surveys by Fisheries and Oceans Canada in the estuary and Gulf of St. Lawrence (EGSL) as well as data from 2000 to 2018 in the northwest Atlantic, we sought to improve our knowledge on the seasonal condition of Greenland Halibut Reinhardtius hippoglossoides juveniles and to better understand the divergence in some life history traits between juveniles captured in these two regions. We validated the use of the Le Cren condition index and evaluated its relationship with energetic status in juvenile (20–32-cm TL) Greenland Halibut. In the EGSL, juvenile condition was higher in winter and spring compared to summer and fall. Such variations may result from this species’ pelagic predation activity and prey availability. Juveniles captured in the EGSL during 2016–2017 were larger but had a lower condition index than those captured in the northwest Atlantic, but we found no indication of earlier sexual maturation in the EGSL that could explain the sex ratio differences we observed in catches from these two areas

Evaluating the use of the autodiametric method for estimating fecundity of Reinhardtius hippoglossoides, a species with an unusual oocyte development strategy

The autodiametric method is a highly streamlined method for estimating fecundity of fish with determinate oocyte development pattern. Greenland halibut presents a peculiar reproductive strategy with two simultaneously cohorts one of large vitellogenic oocytes (for the current year) and another one of small vitellogenic oocytes (for the subsequent year). Results of this study showed that autodiametric method can be applied to estimate fecundity in Greenland halibut. Additionally, spatial differences in the autodiametric calibration curve were observed in the Northwest Atlantic, but did not translate into differences in fecundity at length. This is the first time that spatial differences between ACCs of the same species have been reported, what could be the result of (i) the unusual oocyte development pattern, or (ii) spatial differences in oocyte biochemistry. More research on the relative dynamics of oocyte cohorts simultaneously present in Greenland halibut ovaries and the factors (endo- or exogenous) influencing oocyte packing density could provide a better understanding of observed geographical differences.En prens

Curcuma longa and Boswellia serrata Extracts Modulate Different and Complementary Pathways on Human Chondrocytes In Vitro: Deciphering of a Transcriptomic Study

peer reviewedObjectives:Curcuma longa (CL) and Boswellia serrata (BS) extracts are used to relieve osteoarthritis symptoms. The aim of this in vitro study was to investigate their mechanisms of action at therapeutic plasmatic concentrations on primary human osteoarthritic (OA) chondrocytes.Methods: BS (10–50 μg/ml) and CL (0.4–2 μg/ml corresponding to 1–5 µM of curcumin) were evaluated separately or in combination on primary chondrocytes isolated from 17 OA patients and cultured in alginate beads. Ten patients were used for RNA-sequencing analysis. Proteomic confirmation was performed either by immunoassays in the culture supernatant or by flow cytometry for cell surface markers after 72 h of treatment.Results: Significant gene expression modifications were already observed after 6 h of treatment at the highest dose of CL (2 μg/ml) while BS was significantly effective only after 24 h of treatment irrespective of the concentration tested. The most over-expressed genes by CL were anti-oxidative, detoxifying, and cytoprotective genes involved in the Nrf2 pathway. Down-regulated genes were principally pro-inflammatory cytokines and chemokines. Inversely, BS anti-oxidant/detoxifying activities were related to the activation of Nrf1 and PPARα pathways. BS anti-inflammatory effects were associated with the increase in GDF15, decrease in cholesterol cell intake and fatty acid metabolism-involved genes, and down-regulation of Toll-like receptors (TLRs) activation. Similar to CL, BS down-regulated ADAMTS1, 5, and MMP3, 13 genes expression. The combination of both CL and BS was significantly more effective than CL or BS alone on many genes such as IL-6, CCL2, ADAMTS1, and 5.Conclusion: BS and CL have anti-oxidative, anti-inflammatory, and anti-catabolic activities, suggesting a protective effect of these extracts on cartilage. Even if they share some mechanism of action, the two extracts act mainly on distinct pathways, and with different time courses, justifying their association to treat osteoarthritis

Codon usage bias and tRNA over-expression in Buchnera aphidicola after aromatic amino acid nutritional stress on its host Acyrthosiphon pisum

Codon usage bias and relative abundances of tRNA isoacceptors were analysed in the obligate intracellular symbiotic bacterium, Buchnera aphidicola from the aphid Acyrthosiphon pisum, using a dedicated 35mer oligonucleotide microarray. Buchnera is archetypal of organisms living with minimal metabolic requirements and presents a reduced genome with high-evolutionary rate. Codonusage in Buchnera has been overcome by the high mutational bias towards AT bases. However, several lines of evidence for codon usage selection are given here. A significant correlation was found between tRNA relative abundances and codon composition of Buchnera genes. A significant codon usage bias was found for the choice of rare codons in Buchnera: C-ending codons are preferred in highly expressed genes, whereas G-ending codons are avoided. This bias is not explained by GC skew in the bacteria and might correspond to a selection for perfect matching between codon–anticodon pairs for some essential amino acids in Buchnera proteins. Nutritional stress applied to the aphid host induced a significant overexpression of most of the tRNA isoacceptors in bacteria. Although, molecular regulation of the tRNA operons in Buchnera was not investigated, a correlation between relative expression levels and organization in transcription unit was found in the genome of Buchnera

Practical guidelines for rigor and reproducibility in preclinical and clinical studies on cardioprotection

The potential for ischemic preconditioning to reduce infarct size was first recognized more than 30 years ago. Despite extension of the concept to ischemic postconditioning and remote ischemic conditioning and literally thousands of experimental studies in various species and models which identified a multitude of signaling steps, so far there is only a single and very recent study, which has unequivocally translated cardioprotection to improved clinical outcome as the primary endpoint in patients. Many potential reasons for this disappointing lack of clinical translation of cardioprotection have been proposed, including lack of rigor and reproducibility in preclinical studies, and poor design and conduct of clinical trials. There is, however, universal agreement that robust preclinical data are a mandatory prerequisite to initiate a meaningful clinical trial. In this context, it is disconcerting that the CAESAR consortium (Consortium for preclinicAl assESsment of cARdioprotective therapies) in a highly standardized multi-center approach of preclinical studies identified only ischemic preconditioning, but not nitrite or sildenafil, when given as adjunct to reperfusion, to reduce infarct size. However, ischemic preconditioning—due to its very nature—can only be used in elective interventions, and not in acute myocardial infarction. Therefore, better strategies to identify robust and reproducible strategies of cardioprotection, which can subsequently be tested in clinical trials must be developed. We refer to the recent guidelines for experimental models of myocardial ischemia and infarction, and aim to provide now practical guidelines to ensure rigor and reproducibility in preclinical and clinical studies on cardioprotection. In line with the above guideline, we define rigor as standardized state-of-the-art design, conduct and reporting of a study, which is then a prerequisite for reproducibility, i.e. replication of results by another laboratory when performing exactly the same experiment

Size and temperature-dependent variations in intermolt duration and size increment at molt of Northern Shrimp, Pandalus borealis

Growth of Pandalus borealis post-larval stages was measured in relation to size and temperature. Growth characteristics, including intermolt period (IP), molt increment (MI) in size and mass, and tissue allocation in juvenile, male, and female shrimp, were evaluated at 2, 5, and 8°C, the temperature range where this species is generally found in the Northwest Atlantic. Significant variations in growth were associated with temperature and shrimp size. IP (days) increased significantly with shrimp size and was inversely related to temperature. Size (cephalothorax length in mm) and temperature effects were best described by IP = 10(0.67 log(CL) − 0.06 T − 1.34). The pronounced effect of temperature on IP while MIS changed little indicated that the main influence of temperature on growth rate of P. borealis was through IP. Specific growth rate (SGRS) decreased rapidly with size to near zero values in females. Overall, juveniles were much more sensitive to temperature variations than adults, suggesting that temperatures encountered during the juvenile stage will largely influence the growth trajectory of the population. -- Keywords : Molt Cycle ; Size Increment ; Shrimp Population ; Juvenile Shrimp ; Intermolt Period

Influence of different levels of dissolved oxygen on the success of Greenland halibut (Reinhardtius hippoglossoides) egg hatching and embryonic development

The aim of this study was to determine the influence of different levels of dissolved oxygen (DO) on embryonic development (ED) and hatching success of Greenland halibut (Reinhardtius hippoglossoides) eggs. Fertilized eggs from six females were exposed to five DO levels: severely hypoxic (10 and 20 %sat [percent saturation]), moderately hypoxic (35 and 50 %sat), and normoxic (100 %sat). Greenland halibut eggs were highly tolerant to hypoxia, with hatching occurring at levels as low as 20 %sat. In severely hypoxic conditions (10 %sat), ED was impaired and no hatching occurred. Lipid composition, during ED, changed as a function of female origin and DO levels. Phospholipids were the dominant lipid class in eggs. Although triacylglycerols were a minor lipid class in terms of abundance, they were only used under severe hypoxia. The results suggest that severe hypoxia (between 10 and 20 %sat) has detrimental effect on the early development of Greenland halibut and may result in reduced recruitment and lower population abundance if the decreasing trend in the DO levels observed in the bottom waters of the Gulf of St. Lawrence continues in the future. Other species that share similar life histories may also be at risk. -- Keywords : Dissolve Oxygen ; Embryonic Development ; Lipid Class ; Hatching Success ; Severe Hypoxia

How variable is the fecundity within and between cod stocks?

Stock reproductive potential is determined by the number of fish at age, sex ratio, proportion of mature female at age and fecundity. Fecundity data, which are fundamental in estimating egg production are not collected routinely for most fish stocks. Thus, variability in fecundity is largely ignored in the estimations of reproductive potential. The objective of this study was to identify patterns of spatial and temporal variation in the fecundity within and between different stocks of Atlantic cod (Gadus morhua) in the North Atlantic and Baltic Sea. A review of fecundity data for cod of different stocks and years was made. The examination of fecundity at size indicated a very large variability in the fecundity of cod between stocks and years. The fecundity of a 60 cm cod varied from 210 000 eggs to 2 250 000 eggs. Baltic and North Sea cod stocks were very distinct from the others, highest fecundity-at-size notwithstanding years being observed for these stocks. A different pattern of variation was observed for the other stocks. Temporal variation in fecundity appeared as important as or even more important than differences associated with stocks. Without excluding genetic differences, variations in the environmental conditions and fishing pressure could possibly explain much of the variation in the fecundity of these stocks. At a smaller scale, it also appears that the increase in the reproductive investment with age/size can differ between stocks and years. Thus, routine measurement of fecundity should be essential in estimating reproductive potential of cod