Atlantic salmon male post-smolt maturation can be reduced by using a 3-hour scotophase when inducing smoltification

Photoperiod regulates the occurrence of unwanted male post-smolt maturation during the production of large (>100 g) Atlantic salmon (Salmo salar) smolts. However, the optimal daylength for triggering smoltification, but not male puberty, has yet to be established. We used either continuous light (24:0 light/dark) or long days (18:6 and 21:3) after a six week “winter” zeitgeber (12:12) to induce smoltification in fish of around 120 g reared at 16 °C. The fish were sampled 1, 2, 3, and 6 weeks after the initiation of the three different photoperiod treatments (n = 153 males in total with 9–18 males/photoperiod/time point). As expected, the smoltification indicator gill Na+/K+-ATPase (NKA) was significantly (p < 0.05) elevated and peaked 2 to 3 weeks after the initiation of the different photoperiods. Pubertal males were identified in all treatments via the combined use of relative testis size and histology, plasma 11-ketotestosterone, changes in body condition, and growth rate. The total incidence of puberty was significantly higher among males on continuous light at 33% (n = 16/49) compared to 10% (6/61) and 12% (5/43) in 21:3 and 18:6, respectively. The incidence of puberty increased over time in all photoperiods, with 62% (8/13), 19% (3/16), and 38% (3/8) of the males from 24:0, 21:3, and 18:6 pubertal at week 6, respectively. The mean weight of males that went on to initiate puberty was significantly higher (13%) at the beginning of the trial compared to those that remained immature (mean weight, 127 vs 112 g, respectively), but there was no initial difference in body condition. Puberty significantly reduced gill NKA by 35% compared to immature males at week six but had no effect at earlier time-points. Photoperiod had no effect on the female GSI, and they were all considered immature. In conclusion, the incidence of male puberty during smoltification is regulated by photoperiod and leads to an earlier decline in a key indicator of seawater readiness. As such, photoperiods with a short scotophase (21:3 or 18:6) following the winter zeitgeber in a square-wave (long-short-long day) smolt regime are recommended to limit the incidence of male puberty.publishedVersio

The Piwil1 N domain is required for germ cell survival in Atlantic salmon

Genetic introgression of farmed salmon into wild populations can damage the genetic integrity of wild stocks and is therefore considered as an environmental threat. One possible solution is to induce sterility in farmed salmon. We have searched for proteins potentially essential for germline survival in Atlantic salmon. One of these is the argonaute protein Piwil1, known to be required for germ cell survival. To examine Piwil1 function in salmon, we induced indels in the N domain by CRISPR-Cas9. The encoded domain is present in all vertebrate Piwi proteins and has been linked to Tdrd1 protein interaction and PAZ lobe structure. The F0 founder generation of piwil1 crispant males and females displayed a mosaic pattern of piwil1 mutations, exhibiting highly mutated alleles (53%–97%) in their fin gDNA samples. In general, piwil1 crispants carried germ cells, went through puberty and became fertile, although a transient and partial germ cell loss and delays during the spermatogenic process were observed in many male crispants, suggesting that Piwil1 functions during salmon spermatogenesis. By crossing highly mutated F0 founders, we produced F1 fish with a mixture of: loss-of-function alleles (−); functional in frame mutated alleles (+) and wt alleles (+). In F1, all piwil1−/− fish lacked germ cells, while piwil1+/+ siblings showed normal ovaries and testes. Yet, most juvenile F1 piwil1+/−males and females displayed an intermediate phenotype with a higher somatic/germ cell ratio without an increase in germ cell apoptosis, suggestive of a gene dose effect on the number of germ cells and/or insufficient replacement of lost germ cells in heterozygous fish. Interestingly, the two longest in-frame indels in the N domain also ensured germ cell loss. Hence, the loss of 4–6 aa in this region Phe130-Ser136 may result in crucial changes of the protein structure, potentially affecting piRNA binding of the PAZ lobe, and/or affecting the binding of Piwil1 interacting proteins such as Tdrd protein, with critical consequences for the survival of primordial germ cells. In conclusion, we show that loss of piwil1 leads to loss of germ cells in salmon and that part of the N domain of Piwil1 is crucial for its function.publishedVersio

Full production cycle performance of gene-edited, sterile Atlantic salmon - growth, smoltification, welfare indicators and fillet composition

Using germ cell-free (GCF), sterile, dnd-knockout salmon for farming could solve the problems associated with precocious maturation and genetic introgression of farmed breeds into wild populations. However, prior to using GCF fish in the salmon farming industry, it is crucial to understand if, or how, the GCF phenotype differs from wild type (WT) counterparts in terms of growth and welfare. To characterize the GCF phenotype throughout a production cycle, we reared GCF and WT salmon in indoor common garden tanks for 3 years, until harvest size. Regarding body size, smoltification markers (mRNA levels of gill Na+/K+-ATPase [NKA] subunits), plasma stress indicators (pH, glucose, sodium, chloride, calcium), relative heart size, prevalence of vertebra deformities and fillet proximate composition, GCF fish could not be distinguished from WTs. Transient differences were detected in plasma concentrations of lactate and osmolality, and only a few genes were differentially expressed in WT and GCF transcriptomes of muscle and pituitary. At harvest, fillets from GCF and WT salmon contained the same amount of omega-3 fatty acids, however the relative content of omega-3 fatty acids was higher in GCF compared to WT males. Towards harvest size, body growth rate, condition factor and relative liver size were significantly higher in WT than in GCF fish, probably relating to initiation of puberty in WTs. Since GCF salmon never become sexually mature, it is possible to postpone the time of harvest to exploit the growth potential uninhibited by sexual maturation. In conclusion, GCF salmon performed to a large extent similarly to their WT counterparts but had the clear advantage of never maturing.publishedVersio

Proceedings of the 3rd Biennial Conference of the Society for Implementation Research Collaboration (SIRC) 2015: advancing efficient methodologies through community partnerships and team science

It is well documented that the majority of adults, children and families in need of evidence-based behavioral health interventionsi do not receive them [1, 2] and that few robust empirically supported methods for implementing evidence-based practices (EBPs) exist. The Society for Implementation Research Collaboration (SIRC) represents a burgeoning effort to advance the innovation and rigor of implementation research and is uniquely focused on bringing together researchers and stakeholders committed to evaluating the implementation of complex evidence-based behavioral health interventions. Through its diverse activities and membership, SIRC aims to foster the promise of implementation research to better serve the behavioral health needs of the population by identifying rigorous, relevant, and efficient strategies that successfully transfer scientific evidence to clinical knowledge for use in real world settings [3]. SIRC began as a National Institute of Mental Health (NIMH)-funded conference series in 2010 (previously titled the “Seattle Implementation Research Conference”; $150,000 USD for 3 conferences in 2011, 2013, and 2015) with the recognition that there were multiple researchers and stakeholdersi working in parallel on innovative implementation science projects in behavioral health, but that formal channels for communicating and collaborating with one another were relatively unavailable. There was a significant need for a forum within which implementation researchers and stakeholders could learn from one another, refine approaches to science and practice, and develop an implementation research agenda using common measures, methods, and research principles to improve both the frequency and quality with which behavioral health treatment implementation is evaluated. SIRC’s membership growth is a testament to this identified need with more than 1000 members from 2011 to the present.ii SIRC’s primary objectives are to: (1) foster communication and collaboration across diverse groups, including implementation researchers, intermediariesi, as well as community stakeholders (SIRC uses the term “EBP champions” for these groups) – and to do so across multiple career levels (e.g., students, early career faculty, established investigators); and (2) enhance and disseminate rigorous measures and methodologies for implementing EBPs and evaluating EBP implementation efforts. These objectives are well aligned with Glasgow and colleagues’ [4] five core tenets deemed critical for advancing implementation science: collaboration, efficiency and speed, rigor and relevance, improved capacity, and cumulative knowledge. SIRC advances these objectives and tenets through in-person conferences, which bring together multidisciplinary implementation researchers and those implementing evidence-based behavioral health interventions in the community to share their work and create professional connections and collaborations

Development and validation of a SAR wind emulator

It is realised that the spatial coverage and irregular revisit time of SAR sensors is not adequate for direct use of SAR-retrieved wind in operational weather forecasting or for assimilation into numerical forecast models. Therefore a new way is sought to take benefit from the obvious strength of SAR for high resolution wind speed retrieval. The approach investigated in this study is to develop a transfer function which can prescribe (emulate) a high resolution wind field from a given lower resolution weather forecast model field. Such a transfer function (or emulator) can be trained to “learn” the micrometeorological conditions of specific regions by co-locating a large historical dataset of model and SAR derived windfields. Once developed, this emulator can then be used in real time, or even forecast situation, to emulate the high resolution wind fields from the coarse model output, without the need for additional real time SAR data. The potential gain of such an emulator is largest in coastal regions with complex topography, where variations in wind speed and direction may be large on a fine scale. In this study, two regions with complex fjord-topography along the Norwegian coast are selected as study areas. Wind retrieval from Envisat ASAR Enivsat ASAR images are read and calibrated with Matlab software developed at NERSC. The backscatter images are downscaled from a pixel size of 75 metres to about 535 metres with an anti-aliasing lowpass filter (“resample” function in Matlab with N=10) to reduce noise, speckle and data volume. From these “quicklooks”, wind speed is calculated in this study with the CMOD4 algorithm (Stoffelen at al., 1997), where the auxiliary wind direction is taken from the NCEP Global Forecast System (GFS). The GFS model is initialised every 6 hours, and provides forecast output for every 3 hours. The 0 hour (initialization) or 3 hour forecast field, whichever is closest in time to the SAR image, is used for the SAR wind inversion. The pixel size of NCEP GFS is 0.5 degrees, and the wind direction is interpolated (component by component) to the ASAR grid with linear interpolation before the SAR wind retrieval.NERSC Tehnical report no. 304. ESRIN/Contract no. 18709/05/I-L