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.
This paper investigates the impact of different thermo- and photo-cycles of distinct wavelengths on
Solea senegalensis larvae from day 1 to 30 post-hatching. In experiment 1, larvae were exposed to ...12
h light:12
h dark (12
L:12D) cycle and (A) constant temperature (20.7
°C), (B) thermocycle of 12
h thermophase: 12
h cryophase, 22.1
°C day: 19.0
°C night (referred to as TC) or (C) 12
h cryophase: 12
h thermophase, 19.2
°C day: 22.0
°C night (referred to as CT). In experiment 2, larvae were kept under constant temperature (20.8
°C) and exposed to (A) continuous light (LL), (B) continuous darkness (DD), and LD 12
L:12D cycles of (C) white light (LD
W), (D) blue light (LD
B) or (E) red light (LD
R). The sole larvae achieved the best performance, and showed fastest development and lowest degree of deformity under natural thermocycle conditions (TC) with a deformity percentage of 31.1% and LD
B cycles with 27.7% of malformation, conditions which were nearest their natural aquatic environment. Larvae reared under TC started eye migration at 9
day post-hatching (DPH), while larvae exposed to CT started eye migration at 11 DPH. In larvae under the LD
B treatment the migration of the eye started earlier than in the other treatments (9 DPH), while larvae reared under LL and DD photoperiods died before metamorphosis. These findings highlight the importance of light and temperature cycles during the early development of
S.
senegalensis larvae, which should be taken into consideration in experimental or rearing protocols.
The endocrine axis controlling the stress response displays daily rhythms in many factors such as adrenal sensitivity and cortisol secretion. These rhythms have mostly been described in mammals, ...whereas they are poorly understood in teleost fish, so that their impact on fish welfare in aquaculture remains unexplored. In the present research, the authors investigated the daily rhythms in the hypothalamus-pituitary-interrenal (HPI) axis in the flatfish Solea senegalensis, which has both scientific and commercial interest. In a first experiment, hypothalamic expression of corticotropin-releasing hormone (crh) and its binding protein (crhbp), both pituitary proopiomelanocortin A and B (pomca and pomcb) expression, as well as plasma cortisol, glucose, and lactate levels were analyzed throughout a 24-h cycle. All variables displayed daily rhythms (cosinor, p < .05), with acrophases varying depending on the factor analyzed: crh and cortisol peaked at the beginning of the dark phase (zeitgeber time ZT = 14.5 and 14.4 h, respectively), pomca and pomcb as well as glucose at the beginning of the light phase (ZT = 1.2, 2.4, and 3.4 h, respectively), and crhbp and lactate at the end of the dark phase (ZT = 22.3 and 23.0 h, respectively). In a second experiment, the influence of an acute stressor (30 s of air exposure), applied at two different time points (ZT 1 and ZT 13), was tested. The stress response differed depending on the time of day, showing higher cortisol values (96.2 ± 10.7 ng mL) when the stressor was applied at ZT 1 than at ZT 13 (52.6 ± 11.1 ng mL). This research describes for the first time the daily rhythms in endocrine factors of the HPI axis of the flatfish S. senegalensis, and the influence of daytime on the stress responses. A better knowledge of the chronobiology of fish provides a helpful tool for understanding the circadian physiology of the stress response, and for designing timely sound protocols to improve fish welfare in aquaculture. (Author correspondence: jflopez@um.es)
Abstract Reproduction in most fish is a seasonal phenomenon, since spawning occurs at a precise moment of the year to ensure maximal survival of the offspring. Nevertheless, fish reproduction cannot ...be considered an exclusively annual phenomenon, since spawning might also show daily rhythmicity. In this study, we used an automatic programmable egg collector to investigate the existence of circadian spawning and activity rhythms in zebrafish ( Danio rerio L.), and their synchronization to different light and feeding cycles. Under 14L:10D, the results showed a diurnal spawning rhythm with an acrophase at ZT3 (lights went on at ZT0). Activity rhythms were also diurnal (74.4% of the total daily activity occurring during daytime), peaking immediately after lights on, in anticipation of spawning. Feeding at night did not change the diurnal spawning rhythm, but altered the daily pattern of activity, whose diurnal percentage dropped to 49.6%. When applying 1 h of darkness at ZT3, fish shifted the time of spawning to ZT7, while 1 h of darkness applied at ZT7 resumed spawning to ZT3. Under continuous light, locomotor activity rhythms persisted with τ = 22.3 h and the spawning rhythm maintained its phase relationship with them, with an acrophase at CT3. In short, these findings revealed the existence of circadian spawning and locomotor rhythms in zebrafish. The two rhythms are in phase with each other and both are synchronized by light, though only locomotion is influenced by feeding time.
Abstract Feeding cycles entrain biological rhythms, which enable animals to anticipate feeding times and so maximize food utilization and welfare. In this article, the effect of mealtime was ...investigated in two groups of sea bream ( Sparus aurata ): one group received a single daily meal at random times during the light period (random daytime feeding, RDF), whereas the other group received the meal during the light period but at the same time (scheduled daytime feeding, SDF). All the fish showed diurnal behavior, although the SDF group showed a lower percentage of diurnalism (84.4% vs. 79.5% in RDF and SDF respectively) and developed food anticipatory activity some hours before the mealtime. In addition, the mean daily locomotor activity of the RDF group was significantly higher than that of the SDF group (3132 vs. 2654 counts/day, respectively). Although the mean weight differed between both groups on day 30 (115.7 g and 125.6 g in RDF and SDF respectively), these differences had disappeared by day 60. Plasma cortisol and glucose significantly differed in both groups (cortisol: 71.8 vs. 8.7 ng/ml, glucose: 53.7 vs. 43.8 mg/dl in RDF and SDF, respectively), whereas lactate did not differ significantly. The results obtained suggest that altering the feeding time (scheduled vs. random) affects the behavior and physiology of sea bream, indicating that a single daily feeding cycle (compared to random) is beneficial for fish welfare because they can prepare themselves for the forthcoming feed.
Light plays a key role in the development of biological rhythms in fish. Recent research in Senegal sole has revealed that spawning and hatching rhythms, larval development, and growth performance ...are strongly influenced by lighting conditions. However, the effect of light on the daily patterns of behavior remains unexplored. Therefore, the aim of this study was to investigate the impact of different photoperiod regimes and white, blue, and red light on the activity rhythms and foraging behavior of Solea senegalensis larvae up to 40 days posthatching (DPH). To this end, eggs were collected immediately after spawning during the night and exposed to continuous white light (LL), continuous darkness (DD), or light-dark (LD) 12L:12D cycles of white (LDW), blue (LDB, λpeak = 463 nm), or red light (LDR, λpeak = 685 nm). A filming scenario was designed to video record activity rhythms during day and night times using infrared lights. The results revealed that activity rhythms in LDB and LDW changed from diurnal to nocturnal on days 9 to 10 DPH, coinciding with the onset of metamorphosis. In LDR, sole larvae remained nocturnal throughout the experimental period, while under LL and DD, larvae failed to show any rhythm. In addition, larvae exposed to LDB and LDW had the highest prey capture success rate (LDB = 82.6% ± 2.0%; LDW = 75.1% ± 1.3%) and attack rate (LDB = 54.3% ± 1.9%; LDW = 46.9% ± 3.0%) during the light phase (ML) until 9 DPH. During metamorphosis, the attack and capture success rates in these light conditions were higher during the dark phase (MD), when they showed the same nocturnal behavioral pattern as under LDR conditions. These results revealed that the development of sole larvae is tightly controlled by light characteristics, underlining the importance of the natural underwater photoenvironment (LD cycles of blue wavelengths) for the normal onset of the rhythmic behavior of fish larvae during early ontogenesis.
Light plays a key role in the development of biological rhythms in fish. Previous research on Senegal sole has revealed that both spawning rhythms and larval development are strongly influenced by ...lighting conditions. However, hatching rhythms and the effect of light during incubation are as yet unexplored. Therefore, the aim of this study was to investigate the impact of the light spectrum and photoperiod on Solea senegalensis eggs and larvae until day 7 post hatching (dph). To this end, eggs were collected immediately after spawning during the night and exposed to continuous light (LL), continuous darkness (DD), or light-dark (LD) 12L:12D cycles of white light (LDW), blue light (LDB; λpeak = 463 nm), or red light (LDR; λpeak = 685 nm). Eggs exposed to LDB had the highest hatching rate (94.5% ± 1.9%), whereas LDR and DD showed the lowest hatching rate (54.4% ± 3.9% and 48.4% ± 4.2%, respectively). Under LD conditions, the hatching rhythm peaked by the end of the dark phase, but was advanced in LDB (zeitgeber time 8 ZT8; ZT0 representing the onset of darkness) in relation to LDW and LDR (ZT11). Under DD conditions, the same rhythm persisted, although with lower amplitude, whereas under LL the hatching rhythm split into two peaks (ZT8 and ZT13). From dph 4 onwards, larvae under LDB showed the best growth and quickest development (advanced eye pigmentation, mouth opening, and pectoral fins), whereas larvae under LDR and DD had the poorest performance. These results reveal that developmental rhythms at the egg stage are tightly controlled by light characteristics, underlining the importance of reproducing their natural underwater photoenvironment (LD cycles of blue wavelengths) during incubation and early larvae development of fish. (Author correspondence: borja@um.es)
Circadian rhythms are common in a wide variety of physiological processes. Our knowledge of biological rhythms in fish can be exploited to improve some key aspects of aquaculture such as feed ...optimization and fish welfare. The aim of this paper was to investigate daily rhythms in behavioural and physiological variables of the European eel. To this end, we first analysed the daily rhythms in locomotor activity measured by means of infrared photocells and feeding activity by means of self-feeders. The eels were then submitted to scheduled feeding (single meals once a day at a fixed time), and the levels of cortisol, glucose and digestive enzymes were analysed. Locomotor activity was predominantly nocturnal (63 % of daily activity occurring at night) with peaks located around light transitions, whereas feeding activity was less clearly defined. Cortisol and glucose showed daily rhythms, with acrophases located in the middle and at the beginning of the light phase, respectively, which should be carefully considered when using these parameters as welfare indicators. Significant variations were found during the day in acid protease levels, which increased in anticipation of mealtime. Taken together, these results describe for the first time a picture of the circadian physiology of the European eel, providing hints to improve feeding methods and welfare assessment.
Although white-matter abnormalities have been reported in middle-aged patients with major depressive disorder (MDD), few data are available on treatment-resistant MDD and the influence of relevant ...variables related to clinical burden of illness is far from being well established.
The present study examined white-matter microstructure in a sample of 52 patients with MDD in different stages (treatment-resistant/chronic MDD, n = 18; remitted-recurrent MDD, n = 15; first-episode MDD, n = 19) and 17 healthy controls, using diffusion tensor imaging with a tract-based spatial statistics approach. Groups were comparable in age and gender distribution, and results were corrected for familywise error (FWE) rate.
Widespread significant reductions of fractional anisotropy (FA) - including the cingulum, corpus callosum, superior and inferior longitudinal fascicule - were evident in treatment-resistant/chronic MDD compared with first-episode MDD and controls (p < 0.05, FWE-corrected). Decreased FA was observed within the ventromedial prefrontal region in treatment-resistant/chronic MDD even when compared with the remitted-recurrent MDD group (p < 0.05, FWE-corrected). Longer duration of illness (β = -0.49, p = 0.04) and higher depression severity (at a trend level: β = -0.26, p = 0.06) predicted lower FA in linear multiple regression analysis at the whole-brain level. The number of previous episodes and severity of symptoms were significant predictors when focused on the ventromedial prefrontal area (β = -0.28, p = 0.04; and β = -0.29, p = 0.03, respectively). Medication effects were controlled for in the analyses and results remained unaltered.
Our findings support the notion that disruptions of white-matter microstructure, particularly in fronto-limbic networks, are associated with resistance to treatment and higher current and past burden of depression.
It is unclear whether preoperative serum uric acid (SUA) elevation may play a role in the development of acute kidney injury (AKI) associated with cardiac surgery (CSA-AKI). We conducted a cohort ...study to evaluate the influence of preoperative hyperuricemia on AKI in patients at high risk for developing SC-AKI.
Multicenter prospective international cohort study.
Fourteen university hospitals in Spain and the United Kingdom.
We studied 261 consecutive patients at high risk of developing CSA-AKI, according to a Cleveland score ≥ 4 points, from July to December 2017.
None.
AKIN criteria were used for the definition of AKI. Multivariable logistic regression models and propensity score-matched pairwise analysis were used to determine the adjusted association between preoperative hyperuricemia (≥7 mg/dL) and AKI. Elevated preoperative AUS (≥7 mg/dL) was present in 190 patients (72.8%), whereas CSA-AKI occurred in 145 patients (55.5%). In multivariable logistic regression models, hyperuricemia was not associated with a significantly increased risk of AKI (adjusted Odds Ratio OR: 1.58; 95% confidence interval CI: 0.81–3; P = .17). In propensity score-matched analysis of 140 patients, the hyperuricemia group experienced similar adjusted odds of AKI (OR 1.05, 95%CI 0.93–1.19, P = .37).
Hyperuricemia was not associated with an increased risk of AKI in this cohort of patients undergoing cardiac surgery at high risk of developing CSA-AKI.
No está claro si la elevación de ácido úrico sérico (AUS) preoperatorio puede desempeñar un papel en el desarrollo de daño renal agudo (DRA) asociado a cirugía cardiaca (DRA-CS). Se realizó un estudio de cohortes para evaluar la influencia de la hiperuricemia en el DRA en pacientes de alto riesgo para desarrollar DRA-CS.
Estudio de cohortes prospectivo multicéntrico.
Catorce hospitales universitarios en España y en Reino Unido.
Se estudiaron a 261 pacientes consecutivos con alto riesgo de desarrollar DRA-CS, según una puntuación de Cleveland ≥ 4 puntos, de julio a diciembre de 2017.
Ninguna.
Se utilizaron los criterios AKIN para la definición de DRA. Para determinar la asociación ajustada entre hiperuricemia (≥7 mg/dL) e DRA se utilizaron modelos de regresión logística multivariable y análisis de pares emparejados por puntuaje de propensión.
El AUS preoperatorio elevado (≥7 mg/dL) estaba presente en 190 pacientes (72,8%), mientras que la DRA-CS se produjo en 145 pacientes (55,5%). En los modelos de regresión logística multivariable, la hiperuricemia no se asoció con un aumento significativo del riesgo de DRA (Odds Ratio OR ajustado: 1,58; intervalo de confianza IC 95%: 0,81–3; P = ,17). En el análisis de emparejamiento por puntaje de propensión de 140 pacientes, el grupo de hiperuricemia experimentó probabilidades ajustadas similares de DRA (OR 1,05; IC 95%: 0,93–1,19; P = ,37).
La hiperuricemia no se asoció con un mayor riesgo de DRA en esta cohorte de pacientes con alto riesgo de desarrollar DRA-CS.
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