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In the wild, water temperature cycles daily: it warms up after sunrise, and cools rapidly after sunset. Surprisingly, the impact of such daily thermocycles during the early development of fish remains neglected. We investigated the influence of constant vs daily thermocycles in zebrafish, from embryo development to sexual differentiation, by applying four temperature regimens: two constant (24°C and 28°C) and two daily thermocycles: 28:24°C, TC (thermophase coinciding with daytime, and cryophase coinciding with night-time) and 24:28°C, CT (opposite to TC) in a 12:12 h light:dark cycle (LD). Embryo development was temperature-dependent but enhanced at 28°C and TC. Hatching rhythms were diurnal (around 4 h after lights on), but temperature- and cycle-sensitive, since hatching occurred sooner at 28°C (48 hours post fertilization; hpf) while it was delayed at 24°C (96 hpf). Under TC, hatching occurred at 72 hpf, while under CT hatching displayed two peaks (at 70 hpf and 94 hpf). In constant light (LL) or darkness (DD), hatching rhythms persisted with tau close to 24 h, suggesting a clock-controlled \"gating\" mechanism. Under 28°C or TC, larvae showed the best performance (high growth and survival, and low malformations). The sex ratio was strongly influenced by temperature, as the proportion of females was higher in CT and TC (79 and 83% respectively), contrasting with 28°C and 24°C, which led to more males (83 and 76%). Ovarian aromatase (cyp19a) expression in females was highest in TC and CT (6.5 and 4.6 fold higher than at 28°C, respectively); while anti-müllerian hormone (amh) expression in males increased in testis at 24°C (3.6 fold higher compared to TC) and particularly at 28°C (14.3 fold increase). Taken together, these findings highlight the key role of environmental cycles during early development, which shaped the daily rhythms in fish embryo and larvae, and ultimately influenced sex differentiation.

Ethanol is one of the most commonly abused drugs and consequently its toxic and psychoactive effect has been widely investigated, although little is known about the time-dependent effects of this drug. In the present research zebrafish was used to assess daily rhythms in ethanol toxicity and behavioural effects, as well as the temporal pattern of expression of key genes involved in ethanol detoxification in the liver (adh8a, adh5, aldh2.1 and aldh2.2). Our results showed marked differences in the mortality rate of zebrafish larvae depending on the time of day of the exposure to 5% ethanol for 1h (82% and 6% mortality in the morning and at night, respectively). A significant daily rhythm was detected with the acrophase located at \"zeitgeber\" time (ZT) = 04:22 h. Behavioural tests exposing zebrafish to 1% ethanol provoked a major decrease in swimming activity (68-84.2% reduction) at ZT2, ZT6 and ZT10. In contrast, exposure at ZT18 stimulated swimming activity (27% increase). During the day fish moved towards the bottom of the tank during ethanol exposure, whereas at night zebrafish increased their activity levels right after the exposure to ethanol. Genes involved in ethanol detoxification failed to show significant daily rhythms in LD, although all of them exhibited circadian regulation in constant darkness (DD) with acrophases in phase and located at the end of the subjective night. Taken altogether, this research revealed the importance of considering the time of day when designing and carrying out toxicological and behavioural tests to investigate the effects of ethanol, as the adverse effects of this drug were more marked when fish were exposed in the morning than at night.

The present study investigated nutritional programming in Atlantic salmon to improve utilisation of a vegetable-based diet. At first exogenous feeding, fry were fed either a marine-based diet (Diet Mstimulus, 80% fishmeal (FM)/4% fish oil (FO)) or a vegetable-based diet (Diet Vstimulus, 10% FM/0% FO) for 3 weeks. Subsequently, all fish were then fed under the same conditions with a commercial, marine-based, diet for 15 weeks and thereafter challenged with a second V diet (Diet Vchallenge, 10% FM/0% FO) for 6 weeks. Diploid and triploid siblings were run in parallel to examine ploidy effects. Growth performance, feed intake, nutrient utilisation and intestinal morphology were monitored. Fish initially given Diet Vstimulus (V-fish) showed 24 % higher growth rate and 23 % better feed efficiency compared with M-fish when later challenged with Diet Vchallenge. There was no difference in feed intake between nutritional histories, but increased nutrient retentions highlighted the improved utilisation of a V diet in V-fish. There were generally few significant effects of nutritional history or ploidy on enteritis scores in the distal intestine after the challenge phase as only V-triploids showed a significant increase (P<0·05) in total score. The data highlighted that the positive effects were most likely a result of nutritional programming and the ability to respond better when challenged later in life may be attributed to physiological and/or metabolic changes induced by the stimulus. This novel study showed the potential of nutritional programming to improve the use of plant raw material ingredients in feeds for Atlantic salmon.

Fish gonadal melatonin production is still unexplored and could contribute to a better understanding of its role in reproduction control, especially for species with reproductive impairments. This study aimed to comprehend if Senegalese sole testes are an extra-pineal production site of melatonin and if it has seasonal and daily variations. Wild and F1 broodstocks were sampled in the breeding season (BS) and out of the reproductive season (OS), at mid-light (ML) and mid-dark (MD) daytimes. Blood plasma melatonin concentration was determined by radioimmunoassay (RIA). The expression of genes involved in melatonin biosynthesis (tph1a, tph2, hiomt1, aanat1a, aanat1b, and aanat2) and melatonin receptors (mel1, mel1c, and mel2) was evaluated in the brain, eye, and testis by quantitative real-time PCR (qPCR). Plasma melatonin concentration in wild sole displayed day/night differences in both seasons (average ML: 36 +/- 22 pg/mL, MD: 108 +/- 63 pg/mL), whereas differences in the F1 broodstock were only found OS (ML: 100 +/- 54 pg/mL, MD: 187 +/- 88 pg/mL). Gene expression of mel1 and mel2 receptors, and tph1a, aanat1a, aanat2, and hiomt1 enzymes was detected and quantified in the fish testes. Moreover, daily and seasonal fluctuations in the expression of those genes were found in all tissues and broodstock groups. However, the F1 group showed distinct gene expression patterns compared to the wild type, suggesting a disruption in the circadian system. This study revealed that Senegalese sole testes are a melatonin production site and, at the same time, suggested a dysregulation in the hypothalamus-pituitary-gonad (HPG) axis of F1 males.

Melatonin was found in the earliest life forms and is present in all organisms studied to date, ranging from bacteria to humans (Conti et al. 2002, Tan et al. 2003). In mammals and humans, melatonin acts as a sleep regulator and was reported to have a role in sleep initiation (Shochat et al. 1997, Zisapel 2007, Pandi-Perumal et al. 2008). Melatonin has been described to have other roles: it can act as a dopamine release inhibitor from the hypothalamus and retina (Zisapel 2001), it can be involved in the aging process (Reiter et al. 1998), and it can regulate blood pressure (Cavallo et al. 2004, Grossman et al. 2006) and immune response (Carrillo-Vico et al. 2006) among other roles. Melatonin is phylogenetically conserved across vertebrates and acts as a time-keeping signal but also as a direct output of the circadian clock, playing an important role in the synchronization of the circadian system (Cassone 1998). Melatonin was found to be produced mainly by the pineal gland and retina but also by many other organs and tissues including the gastrointestinal tract (Bubenik and Pang 1997), skin (Slominski et al. 2005), lymphocytes (Carrillo-Vico et al. 2004) and bone marrow (Conti et al. 2000), suggesting that melatonin is involved in a range of physiological processes. The daily cycle of illumination is the main environmental factor influencing melatonin production and hence, it is described as a \"zeitgeber\" or the biological time keeping hormone which entrains circadian (daily) and circannual (seasonal) rhythms in vertebrates (Menaker et al. 1997, Falcón et al. 2006, Pandi-Perumal et al. 2006). In all the species studied so far, the synthesis of this hormone by the pineal organ takes place during the dark phase of the daily light/dark (LD) cycle, providing an internal signal of night time to the organisms, and thus timing and controlling several biological rhythms (Arendt 1995, Zachmann et al. 1992a). Daily rhythms in fish include locomotor activity, rest, food intake, vertical migration and shoaling, skin pigmentation, osmoregulation and metabolism, whereas seasonal processes include growth, reproduction and smoltification for migrating salmonids (Falcón et al. 2007, Migaud et al. 2010). However, the profile of the melatonin rhythm varies among vertebrate species and three different variants have been described (Fig. 1). The A-type is characterised by a delay of melatonin rise after the start of the dark phase, showing the peak towards the end of the dark phase (Reiter 1988). This pattern was found in mouse and Syrian hamster as well as in gadoid species (Atlantic cod and haddock) (Reiter 1988, Porter et al. 2001, Davie et al. 2007a ,b,c). The B-type profile is characterised by a distinct peak in the middle of the dark phase as found in human and tilapia (Reiter 1988, Nikaido et al. 2009). The third profile is the C-type; it is the most common profile in vertebrates, where melatonin rises immediately following the onset of the dark phase to the maximum, which remains high and then falls rapidly to the basal level once the light phase starts. This profile is found in salmonids as well as other vertebrates (Reiter 1988, Randall et al. 1995). Also, large differences in melatonin peak levels between teleosts species has been observed (ranging from 50 to 200 pg.ml-1) such as in sea bass (Bayarri et al. 2004b, Migaud et al. 2007), Atlantic cod and haddock (Bromage et al. 2001, Davie et al. 2007a ,b,c), Nile tilapia (Martínez-Chávez et al. 2008) and Atlantic halibut (Davie et al. unpublished data), to 300-800 pg.ml-1 mainly observed in salmonid species (Migaud et al. 2010). Melatonin functions both as a clock and a calendar: the daily rhythm provides the animal information about the time of the day, since the maximum production occurs during the night, whereas the duration of the nocturnal increase would inform about the length of the photoperiod and thus about the season (Reiter 1993). In addition, in fish, the amplitude of the melatonin rhythm changes with water temperature, contributing to the seasonal variations in melatonin synthesis (Iigo and Aida 1995). Therefore, in fish, melatonin rhythms regulate the temporal coordination of many physiological processes, such as smoltification and reproduction (Ekström and Meissl 1997), growth, development, aging and cellular immunity (Yu and Reiter 1993).

Sustainable farming of fish species depends on emerging new feed ingredients, which can alter the features of the digestive tract and influence animals’ overall health. Recent research has shown that functional feeds hold great potential for enhancing fish robustness by evoking appropriate responses at the intestine level. However, there is a lack of extensive and accurate descriptions of the morphology of the gastrointestinal tract of most farmed fish. We have characterised the intestine of European seabass thoroughly, by targeting four segments − anterior, mid, posterior and rectum. Results indicated that the anterior segment is mostly associated with absorption-related features; this segment has the largest absorptive area, the longest villi, and the highest number of neutral goblet cells (GC). The posterior segment and rectum have distinct histomorphometric features, but both seem to be important for immunity, displaying the highest count of acid GC and the highest expression of immune-related genes. The strongest proliferating cell nuclear antigen (PCNA) signal was observed in the anterior intestine and rectum, with PCNA + cells appearing at the base of the villi and the corresponding villi branches. We have also evaluated the impact of a novel feed supplemented with a macro- and microalgae blend and found that there were no differences in terms of growth. However, the alterations observed in the mid intestine of fish fed the blend, such as thickening of the submucosa and lamina propria, an increased number of leucocytes, and higher expression of immune- and oxidative stress-related genes, suggest that algae may have an immunomodulatory effect. In the current article, we have described the morphology and expression patterns of the intestine segments of European seabass in detail and have presented a comprehensive report of the indices and methods used for the semi-quantitative and quantitative histomorphometric assessments, thereby providing useful information for future studies that aim to maintain intestinal health through dietary interventions.

The interest in the use of ceilometers for optical aerosol characterization has increased in the last few years. They operate continuously almost unattended and are also much less expensive than lidars; hence, they can be distributed in dense networks over large areas. However, due to the low signal-to-noise ratio it is not always possible to obtain particle backscatter coefficient profiles, and the vast number of data generated require an automated and unsupervised method that ensures the quality of the profiles inversions. In this work we describe a method that uses aerosol optical depth (AOD) measurements from the AERONET network that it is applied for the calibration and automated quality assurance of inversion of ceilometer profiles. The method is compared with independent inversions obtained by co-located multiwavelength lidar measurements. A difference smaller than 15 % in backscatter is found between both instruments. This method is continuously and automatically applied to the Iberian Ceilometer Network (ICENET) and a case example during an unusually intense dust outbreak affecting the Iberian Peninsula between 20 and 24 February 2016 is shown. Results reveal that it is possible to obtain quantitative optical aerosol properties (particle backscatter coefficient) and discriminate the quality of these retrievals with ceilometers over large areas. This information has a great potential for alert systems and model assimilation and evaluation.

One of the most attractive applications of carbon nanomaterials is as catalysts, due to their extreme surface-to-volume ratio. The substitution of C with heteroatoms (typically B and N as p- and n-dopants) has been explored to enhance their catalytic activity. Here we show that encapsulation within weakly doping macrocycles can be used to modify the catalytic properties of the nanotubes towards the reduction of nitroarenes, either enhancing it (n-doping) or slowing it down (p-doping). This artificial regulation strategy presents a unique combination of features found in the natural regulation of enzymes: binding of the effectors (the macrocycles) is noncovalent, yet stable thanks to the mechanical link, and their effect is remote, but not allosteric, since it does not affect the structure of the active site. By careful design of the macrocycles’ structure, we expect that this strategy will contribute to overcome the major hurdles in SWNT-based catalysts: activity, aggregation, and specificity. Doping carbon nanomaterials with heteroatoms is the most common way to change their catalytic activity. Here, the authors show that the catalytic properties of single-walled carbon nanotubes can be modified by non-covalently encapsulating them within electron-accepting or electron-donating macrocycles to form rotaxane-like structures.

Women are born with all of their oocytes. The oocyte proteome must be maintained with minimal damage throughout the woman’s reproductive life, and hence for decades. Here we report that oocyte and ovarian proteostasis involves extreme protein longevity. Mouse ovaries had more extremely long-lived proteins than other tissues, including brain. These long-lived proteins had diverse functions, including in mitochondria, the cytoskeleton, chromatin and proteostasis. The stable proteins resided not only in oocytes but also in long-lived ovarian somatic cells. Our data suggest that mammals increase protein longevity and enhance proteostasis by chaperones and cellular antioxidants to maintain the female germline for long periods. Indeed, protein aggregation in oocytes did not increase with age and proteasome activity did not decay. However, increasing protein longevity cannot fully block female germline senescence. Large-scale proteome profiling of ~8,890 proteins revealed a decline in many long-lived proteins of the proteostasis network in the aging ovary, accompanied by massive proteome remodeling, which eventually leads to female fertility decline. Harasimov, Gorry, Welp, Penir, Horokhovskyi et al. analyse proteostasis in mammalian oocytes and ovaries: the maintenance of oocytes involves exceptional protein longevity, and many of the extremely long-lived proteins decline as the ovary ages.

Perovskite solar cells (PSCs) are the most rapidly advancing photovoltaic technology in terms of power conversion efficiency. An efficiency of 26.1% was achieved in a decade, which is on par with the efficiency of very mature silicon panels. However, PSC commercialisation is partly hindered by the difficulty of scaling these devices without efficiency loss, mostly due to the increasing sheet resistance of the transparent conductive layer substrates and the nonuniformity of the layers when deposited across large areas. Therefore, it is crucial for the commercialisation of PSCs to implement easily scalable deposition processes with low material waste and compatibility with roll-to-roll (R2R) processes to reduce manufacturing costs. Slot-die coating can meet all these requirements, allowing for great uniformity over large areas. The most recent developments in PSC upscaling using slot-die coating as the main deposition process, along with its extension to the R2R process, are reviewed, including a thorough discussion of the slot-die coating process and the theory behind its operating limits. In fact, R2R coating is a very promising strategy for PSC industrialisation, since all processing steps use low-cost materials and scalable processes at temperatures lower than 120 °C, allowing the cost-effective and high-throughput production of PSC devices.