Geir Lasse Taranger

Institute of Marine Research in Norway | IMR · Research Group of Reproduction and Growth

The timing of puberty can vary strongly in fishes and is modulated by environmental conditions and by somatic growth patterns; there are also strong genetic components affecting age and size at puberty. Combinations of genetics, growth patterns and environmental factors result in considerable plasticity of the timing of puberty, both within and bet...

Following publication of the original article [1], the authors would like to apologize for an error in Fig. 5e, the correct graph is presented below and shows the significant increase in pituitary mRNA levels of fshb in recruited males in the SGA stage.

The stocking density of fish in aquaculture is of major importance as it may have profound effects on water quality resulting in impact on fish health and possibly affect the external barriers that protect against pathogens There are many husbandry conditions, including stocking density, that may affect the primary protective barriers, i.e. the ski...

Background: Puberty in male Atlantic salmon in aquaculture can start as early as after the first winter in seawater, stunts growth and entails welfare problems due to the maturation-associated loss of osmoregulation capacity in seawater. A better understanding of the regulation of puberty is the basis for developing improved cultivation approaches...

Background: When puberty starts before males reach harvest size, animal welfare and sustainability issues occur in Atlantic salmon (Salmo salar) aquaculture. Hallmarks of male puberty are an increased proliferation activity in the testis and elevated androgen production. Examining transcriptional changes in salmon testis during the transition from...

Salmonid alphavirus (SAV) causes pancreas disease (PD) in Atlantic salmon (Salmo salar L.) and disease outbreaks are mainly detected after seawater transfer. The influence of the smoltification process on the immune responses, specifically the adaptive response of Atlantic salmon after SAV infection, is not fully understood. In this study, Atlantic...

Vgll3 is linked to age at maturity in Atlantic salmon (Salmo salar). However, the molecular mechanisms involving Vgll3 in controlling timing of puberty as well as relevant tissue and cell types are currently unknown. Vgll3 and the associated Hippo pathway has been linked to reduced proliferation activity in different tissues. Analysis of gene expre...

Pancreas disease (PD) caused by salmonid alphavirus (SAV) is the most serious viral disease in Norwegian aquaculture. Study of the immune response to SAV will aid preventative measures including vaccine development. The innate immune response was studied in Atlantic salmon infected by either bath immersion (BI) or by intra-muscular (i.m.) injection...

Background Our understanding of the molecular mechanisms implementing pubertal maturation of the testis in vertebrates is incomplete. This topic is relevant in Atlantic salmon aquaculture, since precocious male puberty negatively impacts animal welfare and growth. We hypothesize that certain miRNAs modulate mRNAs relevant for the initiation of pube...

[This corrects the article DOI: 10.1371/journal.pone.0175468.].

Triploid Atlantic salmon (Salmo salar L.) may play an important role in the sustainable expansion of the Norwegian aquaculture industry. Therefore, the susceptibility of triploid salmon to common infections such as salmonid alphavirus (SAV), the causative agent of pancreas disease (PD), requires investigation. In this study, shortly after seawater...

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Salmonid alphavirus (SAV) causes pancreatic disease (PD) in salmonids in Northern Europe which results in large economic losses within the aquaculture industry. In order to better understand the underlying immune mechanisms during a SAV3 infection Atlantic salmon post-smolts were infected by either i.m.-injection or bath immersion and their immune...

Salmonid alphavirus subtype 3 (SAV3) causes pancreas disease (PD) and adversely affects salmonid aquaculture in Europe. A better understanding of disease transmission is currently needed in order to manage PD outbreaks. Here, we demonstrate the relationship between viral dose and the outcome of SAV3 infection in Atlantic salmon post-smolts using a...

In Atlantic salmon, a species of great relevance for aquaculture in Northern Europe, precocious puberty in males increases susceptibility to disease, affects flesh quality, reduces growth and cause hypo-osmoregulatory problems (Taranger et al. 2010). It is therefore of high importance to understand the underlying causative molecular processes invol...

Maturing male and female Atlantic salmon (Salmo salar L.) were held under three temperature regimes for 10 weeks between September and December: warm (constant 14–16 °C), ambient (decreasing from 11 to 5 °C), and cold (decreasing from 7 to 3 °C). Blood samples were analyzed for plasma steroid levels, and the fish were inspected for the presence of...

Background Pancreas disease (PD), caused by salmonid alphavirus (SAV), is an important disease affecting salmonid aquaculture. It has been speculated that Atlantic salmon post-smolts are more prone to infections in the first few weeks following seawater- transfer. After this period of seawater acclimatization, the post-smolts are more robust and be...

Introgression of farmed salmon escapees into wild stocks is a major threat to the genetic integrity of wild populations. Using germ cell-free fish in aquaculture may mitigate this problem. Our study investigated whether it is possible to produce germ cell-free salmon in F0 by using CRISPR-Cas9 to knock out dnd, a factor required for germ cell survi...

Wild and domesticated Atlantic salmon males display large variation for sea age at sexual maturation, which varies between 1-5 years. Previous studies have uncovered a genetic predisposition for variation of age at maturity with moderate heritability, thus suggesting a polygenic or complex nature of this trait. The aim of this study was to identify...

Wild and domesticated Atlantic salmon males display large variation for sea age at sexual maturation, which varies between 1-5 years. Previous studies have uncovered a genetic predisposition for age at maturity with moderate heritability, thus suggesting a polygenic or complex nature of this trait. The aim of this study was to identify associated g...

Fish in use in aquaculture display large variation in gamete biology. To reach better understanding around this issue, this study aims at identifying if species specific "egg life history traits" can be hidden in the unfertilized egg. This was done by investigating egg transcriptome differences between Atlantic salmon and Atlantic cod. Salmon and c...

Norwegian aquaculture has grown from its pioneering days in the 1970s to be a major industry. It is primarily based on culturing Atlantic salmon and rainbow trout and has the potential to influence the surrounding environment and wild populations. To evaluate these potential hazards, the Institute of Marine Research initiated a risk assessment of N...

Water homeostasis and the structural integrity of the vertebrate lens is partially mediated by AQP0 channels. Emerging evidence indicates that external pH may be involved in channel gating. Here we show that a tetraploid teleost, the Atlantic salmon, retains 4 aqp0 genes (aqp0a1, -0a2, -0b1, and -0b2), which are highly, but not exclusively, express...

We studied the effects of androgens on early stages of spermatogenesis along with androgen receptor binding characteristics and the expression of selected testicular and pituitary genes. To this end, immature Atlantic salmon postsmolts received testosterone (T), adrenosterone (OA, which is converted in vivo into 11-ketotestosterone, 11-KT) or a com...

The molecular mechanisms underlying oogenesis and maternally controlled embryogenesis in fish are not fully understood, especially in marine species. Our aim was to study the egg and embryo transcriptome during oogenesis and early embryogenesis in Atlantic cod. Follicles from oogenesis stages (pre-, early-, and late-vitellogenic), ovulated eggs, an...

Introduction Previous studies have revealed a differential expression of small RNA repertoires between immature and mature testis, however no such global small RNA expression studies have been performed in salmonides. Since both precocious maturation and fertility are current problems in salmon aquaculture, increased knowledge about molecular regul...

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The Atlantic salmon shows substantial lifecycle plasticity, which also applies to the timing of puberty. While it is characterized by the activation of the brain-pituitary-gonad axis, many morpho-physiological aspects of puberty and the influence of environmental conditions, such as water salinity, are not well understood in fish. Here, 12 months o...

The current paper compares the use of adipose fin and muscle biopsies as non-lethal sampling procedures, and the suitability of triacylglycerol (TAG) versus total lipid (TOT) fatty acid composition (fatty acid methyl esters, FAME) to estimate dietary history in farmed and wild maturing Atlantic salmon Salmo salar. TAG FAME gives best resemblance to...

Two studies were performed to study the effect of different light intensities on melatonin secretory profiles in Atlantic cod (Gadus morhua L.). In an indoor tank study, plasma melatonin profiles were measured over a 24-hour cycle in juvenile Atlantic cod reared under a 12 h light:12 h dark photoperiod, having either a high or low daytime light int...

In female Atlantic salmon kept at normal light conditions, pituitary follicle-stimulating hormone beta (fshb) transcript levels were transiently elevated one year before spawning, re-increased in February, and remained high during spawning in November and in post-ovulatory fish in December. The first increase in plasma 17b-estradiol (E2), testoster...

The vertical distribution and seasonal timing of sexual maturation were investigated in Atlantic cod in four large commercial sea cages in Northern Norway during their second year of on‐growth. Replicate cages were exposed to either natural light (NL) or continuous light (LL) from May 2007 to January 2008. Hydro‐acoustic monitoring revealed that th...

This study investigated the performance of triploid Atlantic cod (Gadus morhua L.) produced in an intensive feeding system. Eggs pooled from three females fertilized with sperm from two males were either triploidized by hydrostatic pressure (58,600 kPa, 5 min, 6 °C) 30 min post-fertilization, or were maintained as untreated controls, and then reare...

Zygotic transcription in fish embryos initiates around the time of gastrulation, and all prior development is initiated and controlled by maternally derived messenger RNAs. Atlantic cod egg and embryo viability is variable, and it is hypothesized that the early development depends upon the feature of these maternal RNAs. Both the length and the pre...

Gene expression of reference genes in oocyte, 1-2 cell, blastula and gastrula stage in cod. mRNA levels are shown as cycle threshold (Ct)-values when 250 ng RNA was used for cDNA synthesis. All data are shown as mean with SEM. N = 2.

Results from repeated 3’UTR structure analyses, with less strict criteria for classification and excluding all ribosomal genes. Results from repeated analyses on 3’UTR structure, with less strict classification of gene groups and excluding all ribosomal genes. In addition to genes with above 95% of transcripts present in oocyte until blastula stage...

Distribution of nuclear genes with and without transcript number threshold. The bar to the left represents the proportion of nuclear genes that were expressed exclusively in maternal stages, gastrula or in all four stages, when analyzing the dataset with a transcript number threshold (n > 8). The bar to the right represents the dataset when no thre...

Gene Ontology annotation based on UniRef90 BLAST hits. This file contains Gene Ontology annotation based on UniRef90 BLAST hits. 1) UniRef hit, 2) Ensembl gene, 3) Ensembl annotation, 4) UniRef90 hit, 5) UniRef90 hit e-value, 6) UniRef90 hit score, 7) Total UniRef90 hits in the whole predicted gene set, 8) GO UniRef, 9) GO gene name, 10) GO number,...

Gene expression levels of candidate genes to reveal timing of midblastula transition in cod. mRNA levels of 3 candidate genes were measured in oocyte, 1-2 cell, blastula and gastrula stage. mRNA levels are relative to hba. Bars with different letters represent significant different mRNA levels for each gene. All data are shown as mean with SEM. N =...

Functional profile of transcripts that showed a difference in abundance between maternal and zygotic stages. Three levels of function (parent ontologies) are shown: cellular component, molecular function and biological process. The number on top of each bar represents the total number of transcripts in that stage, which could be coupled to the pare...

Contig annotations. This file shows the mapping of EST-contigs to the Atlantic cod genome. Contig annotations for the 257 genes analysed in this study are shown.

Contigs based on clustered sequences. This file contains clustered sequences from all libraries, with given contig name. The contig name can be linked to annotation and accession number in [Additional file 7].

To better understand the role(s) of progesterone in fish spermatogenesis, we cloned the nuclear progesterone receptor (Pgr) of Atlantic cod. The open-reading frame of the cod pgr consists of 2076bp, coding for a 691-amino acids-long protein that shows the highest similarity with other piscine Pgr proteins. Functional characterization of the recepto...

In differentiated gonochoristic species, a bipotential gonad develops into an ovary or testis during sex differentiation. Knowledge about this process is necessary to improve methods for masculinizing genetically female Atlantic cod for the subsequent purpose of producing all-female populations. Gonads were examined histologically in juveniles from...

Figure S2. Scatter plot of Ct values for ef1α mRNA from the mixed sex (open triangles) and all-female (closed circles) Atlantic cod individuals. Data are from quantitative real time PCR. All samples had similar template RNA concentrations loaded into the qPCR reaction.

Figure S3. Phylogenetic analysis of Sox9 amino acid sequences from different teleost species depicted as trees generated by the Neighbor-Joining (NJ) method (left) and Maximum Likelihood (ML) method (right). The bar represents 5% divergence between sequences. The sequences group into two large classes as noted as a and b to the right. The sequences...

Figure S1. Gene expression profiles of sox9b in early life stages of mixed sex (open triangles) and all-female (closed circles) Atlantic cod. Data are presented on a logarithmic scale as fold change in mRNA compared to the smallest and youngest fish.

The gastrointestinal (GI) tract has many important biological functions. One is to serve as a barrier between the fish and the external environment. A decreased physical barrier function of the intestine may lead to increased inflow of luminal content and subsequent activation of the intestinal mucosal immune system. This activation is governed by...

Atlantic cod (Gadus morhua) is a fish species of high importance, as a key species in a range of Northern ecosystems, in fisheries, and as an emerging species in aquaculture. So far, little is known about the transcriptional activity during early developmental stages of Atlantic cod. Hence, we decided to use a cDNA microarray covering 7,000 genes t...

Produced water (PW), a by-product of the oil-production process, contains large amount of alkylphenols (APs) and other harmful oil compounds. In the last 20 years, there have been increasing concerns regarding the environmental impact of large increases in the amounts of PW released into the North Sea. We have previously shown that low levels of AP...

Pituitary mRNA levels of gonadotropin β-subunits and of their cognate receptors in the testis were studied during puberty in Atlantic cod under normal and experimental photoperiod conditions that suppressed, delayed or accelerated testis maturation. Results are discussed in context with changes in testicular histology and plasma androgen levels, co...

Potential 1 + smolts of Atlantic salmon (Salmo salar) were reared under three light regimes: simulated natural photoperiod (LDN), continuous light (LD24:0), or a combination of continuous, low-intensity background light and a superimposed simulated natural photoperiod (dual photoperiod, LDD). Growth rate in freshwater was enhanced by LD24:0 and LDD...