Seasonality is an important adaptive trait in temperate fish species as it entrains or regulates most physiological events such as reproductive cycle, growth profile, locomotor activity and key ...life‐stage transitions. Photoperiod is undoubtedly one of the most predictable environmental signals that can be used by most living organisms including fishes in temperate areas. This said, however, understanding of how such a simple signal can dictate the time of gonadal recruitment and spawning, for example, is a complex task. Over the past few decades, many scientists attempted to unravel the roots of photoperiodic signalling in teleosts by investigating the role of melatonin in reproduction, but without great success. In fact, the hormone melatonin is recognized as the biological time‐keeping hormone in fishes mainly due to the fact that it reflects the seasonal variation in daylength across the whole animal kingdom rather than the existence of direct evidences of its role in the entrainment of reproduction in fishes. Recently, however, some new studies clearly suggested that melatonin interacts with the reproductive cascade at a number of key steps such as through the dopaminergic system in the brain or the synchronization of the final oocyte maturation in the gonad. Interestingly, in the past few years, additional pathways have become apparent in the search for a fish photoneuroendocrine system including the clock‐gene network and kisspeptin signalling and although research on these topics are still in their infancy, it is moving at great pace. This review thus aims to bring together the current knowledge on the photic control of reproduction mainly focusing on seasonal temperate fish species and shape the current working hypotheses supported by recent findings obtained in teleosts or based on knowledge gathered in mammalian and avian species. Four of the main potential regulatory systems (light perception, melatonin, clock genes and kisspeptin) in fish reproduction are reviewed.
Daily variation in the absorption, metabolism and excretion of toxic substances will ultimately determine the actual concentration to which the cells and tissues are exposed. In aquaculture, Atlantic ...salmon (Salmo salar) can be frequently exposed to hydrogen peroxide (H2O2) to treat topical skin and gill infections, particularly in relation to parasitic infections (e.g. sea lice Lepeophtheirus salmonis and amoebic gill disease caused by Neoparamoeba perurans). It is well accepted that the time of administration influences pharmacodynamics and pharmacokinetics of drugs which in turn affects their efficacy and toxicity. Consequently, a better understanding of drug side effects as a function of time of day exposure would help to improve treatment efficacy and fish welfare. To this end, salmon were exposed to H2O2 (1500 mg/L) for 20 min at six different times of the day during a 24-h cycle and we investigated the time-dependent effects of exposure on physiological stress (glucose, lactate and cortisol) and antioxidant enzyme expression (gpx1, cat, Mn-sod and hsp70) in liver and gills. In addition, at each sampling point, 8 control fish were also sampled. Our results revealed that the time of administration of H2O2 caused significant differences in the induction of both physiological and oxidative stress responses. Glucose and lactate were higher in the treated fish during daytime whereas cortisol levels appeared to be systematically increased (>1000 ng/mL) after H2O2 treatment irrespective of exposure time, although differences with control levels were higher during the day. In liver, gene expression of antioxidant enzymes displayed daily rhythmicity in both treated and control groups and showed higher mRNA expression levels in salmon treated with H2O2 at ZT6 (6 h after lights onset). In gills, rhythmic expression was only found for gpx1 in the control fish and for hsp70 and Mn-sod in the treated groups. However, in the treated salmon, higher gene expression levels of all the investigated enzymes were also observed at ZT6-10. Clock gene expression showed rhythmicity only in the liver in accordance with the daily rhythm of enzyme expression observed in this tissue. Altogether, this study provides first evidence of chronotoxicity in Atlantic salmon treated with H2O2 and suggests increased sublethal toxic effect during the first half of the day. These results have direct relevance to the salmon and broader aquaculture industry by optimising the timing of treatment administration, opening the door to chronotherapy to treat fish diseases.
Primordial germ cells (PGCs) are specified by maternally provided determinants in fish. PGCs migrate then into prospective gonadal sites during early development and give rise to germ cell lineage. ...PGC disrupted animals do not sexually mature which has a range of commercial as well as environmental benefits. To find potential target genes for sterilisation of Nile tilapia, relative mRNA abundance patterns and tissue distribution of four nanos, two piwil, dnd1, vasa and three pum genes were investigated during ontogenic development from unfertilised eggs to newly hatched larvae and in adult tissues, respectively. The ontogenic pattern of RNA abundance revealed that all the investigated gene transcripts are maternally deposited to varying degrees, except for nanos2 which is not expressed in eggs. The ontogenic patterns of relative RNA abundance could be grouped into three categories. The first one, including nanos3, piwil1, piwil2, dnd1 and vasa, showed abundant transcript levels during early developmental stages which are then degraded during the period of maternal to zygotic transition between blastula and gastrula stages with a reduction in expression of four to five orders of magnitude by hatching stage. Another, including pum2 and pum3, showed similar patterns to the first group, but the transcript levels are reduced by only two orders of magnitude. The third group, including nanos1a, nanos1b and pum1, was characterised by a zygotic increase. nanos2 had no detectable transcripts until hatching stage. The tissue screening of nanos1a, nanos1b, pum1, pum2 and pum3 showed that they are expressed in various tissues, implying their potential pleiotropic effects in these tissues apart from gonads. In contrast, nanos3, piwil1, piwil2, dnd1 and vasa appeared to be exclusively expressed in gonads (both ovary and testis), and nanos2 showed testis-specific expression. Based on these results nanos3, piwil1, piwil2, dnd1 and vasa were prioritised among the 11 selected genes as potential target genes for sterilisation in Nile tilapia as they have no significant zygotic expression during embryogenesis, they are expressed exclusively in gonads and maternally deposited. These features suggest a potential role of these genes in the specification and maintenance of PGCs during the ontogenic development of Nile tilapia.
•Three different patterns of transcript expression were found (11 genes screened).•Gonad specificity and ontogenic pattern revealed maternally deposited germline genes.•New potential target genes (piwil) were prioritised for gene editing in Nile tilapia.
Abstract Melatonin is a much conserved feature in vertebrates that plays a central role in the entrainment of daily and annual physiological rhythms. Investigations aiming at understanding how ...melatonin mediates the effects of photoperiod on crucial functions and behaviors have been very active in the last decades, particularly in mammals. In fish a clear-cut picture is still missing. Here we review the available data on (i) the sites of melatonin production in fish, (ii) the mechanisms that control its daily and annual rhythms of production and (iii) the characterization of its different receptor subtypes, their location and regulation. The in vivo and in vitro data on melatonin effects on crucial neuroendocrine regulations, including reproduction, growth, feeding and behavioral responses, are also reviewed. Finally we discuss how manipulation of the photic cues impact on fish circannual clock and annual cycle of reproduction, and how this can be used for aquaculture purposes.
Light is a key environmental factor that synchronizes all life-stages of fish, from embryo development to sexual maturation. The underwater photo-environment is complex since light characteristics ...(i.e. intensity, photoperiod and spectrum) depend on the absorbance properties of the water column. The aim of this paper is to review the effects of artificial lighting conditions on the performance, development and welfare of some fish larvae of commercial interest. Reviewed results show that larvae were significantly affected by light characteristics. For example, European sea bass and sole larvae achieved the best performance, and showed fastest development and lowest degree of deformity under a light/dark cycle using blue light (half-peak bandwidth
=
435–500
nm), conditions which were the closest to their natural aquatic environment. However, constant light (LL) or constant darkness (DD) was shown to negatively affect normal larval development and resulted in increased malformations and poor survival in most of the studied species. Similar results have been observed in other fish larvae such as Atlantic cod, which performed better under short wavelengths (blue and green). These findings highlight the role of lighting conditions during the early development of fish larvae and should be taken into account for the optimization of rearing protocols in fish hatcheries as juvenile supply is one of the main production bottlenecks.
Abstract Introduction Dislocation after total hip arthroplasty (THA) is a leading reason for surgical revision. The risk factors for dislocation are controversial, particularly those related to the ...patient and to the surgical procedure itself. The differences in opinion on the impact of these factors stem from the fact they are often evaluated using retrospective studies or in limited patient populations. This led us to carry out a prospective case-control study on a large population to determine: 1) the risk factors for dislocation after THA, 2) the features of these dislocations, and 3) the contribution of patient-related factors and surgery-related factors. Hypothesis Risk factors for dislocation related to the patient and procedure can be identified using a large case-control study. Patients and methods A multicenter, prospective case-control study was performed between January 1 and December 31, 2013. Four patients with stable THAs were matched to each patient with a dislocated THA. This led to 566 primary THA cases being included: 128 unstable, 438 stable. The primary matching factors were sex, age, initial diagnosis, surgical approach, implantation date and type of implants (bearing size, standard or dual mobility cup). Results The patients with unstable THAs were 67 ± 12 37–73 years old on average; there were 61 women (48%) and 67 men (52%). Hip osteoarthritis (OA) was the main reason for the THA procedure in 71% (91/128) of the unstable group. The dislocation was posterior in 84 cases and anterior in 44 cases. The dislocation occurred within 3 months of the primary surgery in 48 cases (38%), 3 to 12 months after in 23 cases (18%), 1 to 5 years after in 20 cases (16%), 5 to 10 years after in 17 cases (13%) and more than 10 years later in 20 cases. The dislocation recurred within 6 months of the initial dislocation in 23 of the 128 cases (18%). The risk factors for instability were a high ASA score with an odds ratio (OR) of 1.93 (95% CI: 1.4–2.6), neurological disability(cognitive, motor or psychiatric disorders) with an OR of 3.9 (95% CI: 2.15–7.1), history of spinal disease (lumbar stenosis, spinal fusion, discectomy, scoliosis and injury sequelae) with an OR of 1.89 (95% CI: 1.0–3.6), unrepaired joint capsule (all approaches) with an OR of 4.1 (95% CI: 2.3–7.37), unrepaired joint capsule (posterior approach) with an OR of 6.0 (95% CI: 2.2–15.9), and cup inclination outside Lewinnek'ssafe zone (30°–50°) with OR of 2.4 (95% CI: 1.4–4.0). Discussion This large comparative study isolated important patient-related factors for dislocation that surgeons must be aware of. We also found evidence that implanting the cup in 30° to 50° inclination has a major impact on preventing dislocation. Level of evidence Level III – Case-control study
Summary Introduction A medial opening wedge high tibial osteotomy (HTO), where the osteotomy site is filled, is often preferred to a lateral closing osteotomy, but filling the defect can lead to ...certain complications. Hypothesis A medial opening HTO can be performed without filling the bone defect if fixation is carried out with a specially-designed stiff locking plate. Patients and methods Fifty-one patients, 37 to 72 years of age where followed prospectively and continuously from 2003 to 2006. A single surgical technique was used: medial opening HTO with locked plate fixation (TomoFix™, Synthes) but without filling the defect. The preoperative genu varum could not exceed 15°. The following were evaluated: time to return to weight-bearing, IKS functional score, long-leg standing film performed preoperative, postoperative and at follow-up to evaluate limb alignment and validate the precision of the correction and its stability over time. A measurement of the area of bone union in the osteotomy site was used to quantify the rate of union. Results Bone union occurred at 4.5 months on average; two cases of incomplete union (7%) were found and revised with an autograft at 7 and 9 months. Lower-limb alignment was 7.5° of varus on average before surgery (3° to 15° varus, SD = 2.85) and 1.2° of valgus on average after the surgery (4° varus to 5° valgus, SD = 1.78). The correction was maintained at 1 year post-surgery. The average IKS knee score went from 69 ± 15.5 (range 25 to 96) before surgery to 90 ± 7.4 (range 66 to 98) at follow-up ( P = 0.0001). Full weight-bearing without assistance was possible after 3 months on average (range 1.5 to 8, SD = 1.21). Forty-seven patients (92%) were fully weight-bearing after 2 months. Forty-eight patients were able to return to work and sporting activities at the same or a higher level than before the procedure. Discussion Bone union seems to happen more slowly when the defect is filled; however, there are doubts about radiological evaluation of bone union in different published studies. When osteotomy defect was left unfilled in this study, union and filling of 4/5 of the osteotomy site was obtained in 4.2 months for 49 of the 51 cases. Fixation with the locking plate is reliable and provides stable correction and the option for early weight-bearing. Level of proof Level IV, prospective cohort study.
Evidence from mammals and aves alludes to a possibly conserved seasonal photoperiod induced neuroendocrine cascade which stimulates subsequent sexual maturation however our understanding of this ...mechanism in teleosts is lacking. Unlike all teleosts studied to date, the Atlantic cod (Gadus morhua) is a short day breeder with the reduction in day-length from the summer solstice stimulating gametogenesis. Cod specific orthologues of eya3, tshβ and dio2 were identified and their expression was monitored in the brain and pituitary of cod held under either stimulated or inhibited photoperiod conditions. While no differential expression was apparent in brain dio2 &tshβ and pituitary tshβ, there was significant temporal variation in expression of pituitary eya3 under the SNP treatment, with expression level elevating in association with active gametogenesis. Under the LL treatment, sexual maturation was inhibited and there was a corresponding suppression of eya3 expression. In a second study the impact of size/energetic status on the initiation of sexual maturation was investigated. In the feed restricted population maturation was significantly suppressed (5% sexually mature) compared to the ab libitum fed stock (95% sexually mature) with there being a concomitant significant suppression in pituitary eya3 expression. Overall, these results suggest that pituitary eya3 has the potential to act as an integrator of both environmental and energetic regulation of sexual maturation of cod. Being the first account of eya3 induction in a short day breeding teleost, the conserved association with stimulation of reproduction and not seasonal state indicates that the upstream drivers which initiate the pathway differ among vertebrates according to their breeding strategies, but the pathway itself and its role in the reproductive cascade appears to be conserved across the vertebrate clade.
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•Evidence of conservation of the PNES across the vertebrate clade.•Eya3 exhibits a strong seasonal expression pattern which is photoperiod sensitive•First evidence of nutritional regulation of Eya3 expression associated with maturation
Use of a locking plate during medial opening high tibial osteotomy (HTO) eliminates the need to fill the defect and its associated complications. It also allows early weight-bearing. Since long-term ...data with this type of construct are rare, we wanted to report the outcomes of a 51-patient cohort evaluated after a mean follow-up of 10.2years. The goals were to determine (1) the HTO survival and whether the correction was maintained between 2 and 10years later, (2) the stability of the functional outcomes, (3) the complication rate related to use of locking plates.
The correction following medial opening HTO with a Tomofix™ plate without void filling is maintained after 10years’ follow-up.
Fifty-one patients ranging from 37 to 72years of age at the time of surgery between 2003 and 2005 underwent a medial opening HTO that was stabilized with a Tomofix™ locking plate (Synthes, Oberdorf, Switzerland) without void filling. Forty-eight patients were reviewed between March and September 2014; 1 patient had died and 2 were lost to follow-up.
The mean HKA angle went from 172±3.18° (165–178°) preoperatively to 181±1.18° (176–185°) postoperatively, to 181±1.60° (176–185°) at 2years, and 180.8±2.4° (175–184°) at 10years’ follow-up. This equates to a loss of correction of 0.71±1.9° (0–6°) (p=0.02) between 2 and 10years after the surgery. Five patients underwent total knee arthroplasty (TKA), thus the 10-year survival of the HTO procedure was 88% (95% CI: 81–98%). If the five TKA procedures are excluded, the mean IKS knee score went from 90±7.4 (66–98) at 2years’ follow-up to 77±15.3 (43–97) at 10years (p>0.05). There were four complications in all (8%), of which three occurred within 2years (2 cases of nonunion and 1 surgical site infection) and one occurred later (infection after 118months that resolved once the hardware was removed and the patient given appropriate antibiotics). There were no complications related to the five subsequent TKA procedure and no bone grafting was required.
There was a small (less than 1 degree) but statistically significant loss of correction and non-significant deterioration in the functional outcomes. Conversely, the complication rate did not increase over time, despite the lack of void filling, particularly in patients who subsequently underwent TKA. The 10-year survival was similar to other HTO procedures. This locking plate construct without void filling is reliable after 10years.
Level IV, prospective study without control group.
To ensure sustainability of aquaculture, plant-based ingredients are being used in feeds to replace marine-derived products. However, plants contain secondary metabolites which can affect food intake ...and nutrient utilisation of fish. The application of nutritional stimuli during early development can induce long-term changes in animal physiology. Recently, we successfully used this approach to improve the utilisation of plant-based diets in diploid and triploid Atlantic salmon. In the present study we explored the molecular mechanisms occurring in the liver of salmon when challenged with a plant-based diet in order to determine the metabolic processes affected, and the effect of ploidy.
Microarray analysis revealed that nutritional history had a major impact on the expression of genes. Key pathways of intermediary metabolism were up-regulated, including oxidative phosphorylation, pyruvate metabolism, TCA cycle, glycolysis and fatty acid metabolism. Other differentially expressed pathways affected by diet included protein processing in endoplasmic reticulum, RNA transport, endocytosis and purine metabolism. The interaction between diet and ploidy also had an effect on the hepatic transcriptome of salmon. The biological pathways with the highest number of genes affected by this interaction were related to gene transcription and translation, and cell processes such as proliferation, differentiation, communication and membrane trafficking.
The present study revealed that nutritional programming induced changes in a large number of metabolic processes in Atlantic salmon, which may be associated with the improved fish performance and nutrient utilisation demonstrated previously. In addition, differences between diploid and triploid salmon were found, supporting recent data that indicate nutritional requirements of triploid salmon may differ from those of their diploid counterparts.
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