Heidi Kongshaug - Academia.edu (original) (raw)

Papers by Heidi Kongshaug

Frontiers in Genetics, Jan 16, 2024

Scientific Reports, Sep 23, 2020

Experimental Parasitology, May 1, 2018

The salmon louse Lepeophtheirus salmonis (Copepods, Caligida) is a marine ectoparasite infecting ... more The salmon louse Lepeophtheirus salmonis (Copepods, Caligida) is a marine ectoparasite infecting salmonid fishes in the northern hemisphere. At present, salmon lice infections are the most severe disease problem in the salmon farming industry causing significant economic losses. Due to development of resistance towards available chemotherapeutants, it is clear that new chemotherapeutants or non-chemical control methods are essential to manage the parasite in the future. The TOR signaling pathway is present in all metazoans and is a major regulator of cellular activity according to nutrient availability. In this study, we identified the TOR pathway genes in salmon louse; LsTSC1, LsTSC2, LsRheb, LsTOR, LsRaptor and LsRictor. RNA interference mediated gene silencing was performed to elucidate the functional role of each member of the pathway. Our results show that interference of the TOR signaling pathway either directly or indirectly inhibits many biological processes including egg maturation. In addition, the effect of gene knock-down results in more comprehensive physiological defects when targeting TORC1 and the upstream regulator Rheb. This is the first report on the TOR pathway in the salmon louse and that our research contributes to the basic knowledge of the parasite that could lead to development of novel treatment methods.

Experimental Parasitology, Oct 1, 2015

The salmon louse has two IRP1 homologues, LsIRP1A and LsIRP1B. Starvation of adult lice caused de... more The salmon louse has two IRP1 homologues, LsIRP1A and LsIRP1B. Starvation of adult lice caused decreased levels of LsIRP1A, but not LsIRP1B mRNA. Knockdown of LsIRP1B lead to less offspring due to slightly shorter egg strings.

PLOS ONE, Feb 5, 2018

The salmon louse is a marine ectoparasitic copepod on salmonid fishes. Its lifecycle consists of ... more The salmon louse is a marine ectoparasitic copepod on salmonid fishes. Its lifecycle consists of eight developmental stages, each separated by a molt. In crustaceans and insects, molting and reproduction is controlled by circulating steroid hormones such as 20-hydroxyecdysone. Steroid hormones are synthesized from cholesterol through catalytic reactions involving a 7,8-dehydrogenase Neverland and several cytochrome P450 genes collectively called the Halloween genes. In this study, we have isolated and identified orthologs of neverland, disembodied and shade in the salmon louse (Lepeophtheirus salmonis) genome. Tissue-specific expression analysis show that the genes are expressed in intestine and reproductive tissue. In addition, levels of the steroid hormones ecdysone, 20-hydroxyecdysone and ponasterone A were measured during the reproductive stage of adult females and in early life stages.

BMC Evolutionary Biology, 2009

Background: The multiplicity or loss of the vitellogenin (vtg) gene family in vertebrates has bee... more Background: The multiplicity or loss of the vitellogenin (vtg) gene family in vertebrates has been argued to have broad implications for the mode of reproduction (placental or non-placental), cleavage pattern (meroblastic or holoblastic) and character of the egg (pelagic or benthic). Earlier proposals for the existence of three forms of vertebrate vtgs present conflicting models for their origin and subsequent duplication. Results: By integrating phylogenetics of novel vtg transcripts from old and modern teleosts with syntenic analyses of all available genomic variants of non-metatherian vertebrates we identify the gene orthologies between the Sarcopterygii (tetrapod branch) and Actinopterygii (fish branch). We argue that the vertebrate vtg gene cluster originated in proto-chromosome m, but that vtg genes have subsequently duplicated and rearranged following whole genome duplications. Sequencing of a novel fourth vtg transcript in labrid species, and the presence of duplicated paralogs in certain model organisms supports the notion that lineage-specific gene duplications frequently occur in teleosts. The data show that the vtg gene cluster is more conserved between acanthomorph teleosts and tetrapods, than in ostariophysan teleosts such as the zebrafish. The differential expression of the labrid vtg genes are further consistent with the notion that neofunctionalized Aatype vtgs are important determinants of the pelagic or benthic character of the eggs in acanthomorph teleosts. Conclusion: The vertebrate vtg gene cluster existed prior to the separation of Sarcopterygii from Actinopterygii >450 million years ago, a period associated with the second round of whole genome duplication. The presence of higher copy numbers in a more highly expressed subcluster is particularly prevalent in teleosts. The differential expression and latent neofunctionalization of vtg genes in acanthomorph teleosts is an adaptive feature associated with oocyte hydration and spawning in the marine environment.

Comparative Biochemistry and Physiology B, Feb 1, 2007

Clip domain containing serine peptidases (CSPs) include one or more N-terminal clip domain(s) and... more Clip domain containing serine peptidases (CSPs) include one or more N-terminal clip domain(s) and a C-terminal serine peptidase domain that shares traits with both chymotrypsin and trypsin. CSPs are found in arthropods and are involved in embryonic patterning, immune responses and blood clotting. Among crustaceans only one CSP, which activates prophenoloxidase in crayfish, have previously been reported. We here present LsCSP1, the first CSP found in copepods. LsCSP1 is expressed in the subcuticular tissue and the transcription appears to be upregulated during development. In conjunction with previous studies of CSPs, this study suggests that LsCSP1 may play a role in the immune responses of L. salmonis. Phylogenetic and structural analyses indicate that the CSPs and catalytically inactive CSP homologs (CSPHs) constitute a monophyletic lineage.

International Journal for Parasitology, Feb 1, 2015

The salmon louse Lepeophtheirus salmonis (Copepoda, Caligidae) is an important parasite in the sa... more The salmon louse Lepeophtheirus salmonis (Copepoda, Caligidae) is an important parasite in the salmon farming industry in the Northern Hemisphere causing annual losses of hundreds of millions of dollars (US) worldwide. To facilitate development of a vaccine or other novel measures to gain control of the parasite, knowledge about molecular biological functions of L. salmonis is vital. In arthropods, a nuclear receptor complex consisting of the ecdysone receptor and the retinoid X receptor, ultraspiracle, are well known to be involved in a variety of both developmental and reproductive processes. To investigate the role of the ecdysone receptor in the salmon louse, we isolated and characterised cDNA with the 5 0 untranslated region of the predicted L. salmonis EcR (LsEcR). The LsEcR cDNA was 1608 bp encoding a 536 amino acid sequence that demonstrated high sequence similarities to other arthropod ecdysone receptors including Tribolium castaneum and Locusta migratoria. Moreover, in situ analysis of adult female lice revealed that the LsEcR transcript is localised in a wide variety of tissues such as ovaries, sub-cuticula and oocytes. Knock-down studies of LsEcR using RNA interference terminated egg production, indicating that the LsEcR plays important roles in reproduction and oocyte maturation. We believe this is the first report on the ecdysone receptor in the economically important parasite L. salmonis.

Journal of Natural History, Mar 1, 2013

Molecular genetic tools have become standard in biological studies of both model and non-model sp... more Molecular genetic tools have become standard in biological studies of both model and non-model species. This has created a growing need for sequence information, a resource hitherto limited for many species. With new sequencing technologies this is rapidly changing, and whole genome shotgun sequencing has become a realistic goal for many species. However, present sequencing protocols require more DNA than can be extracted from single individuals of many small metazoans, potentially forcing sequencing projects to perform sequencing on samples derived from several individuals. A pertinent question thus arises: can wild samples be used or is inbreeding necessary? In the present study we compare assemblies generated using sequence data from inbred and wild Lepeophtheirus salmonis. The results indicate not only that measures to reduce the genetic variability may significantly improve the final assemblies but also that deeper coverage to some extent can compensate for the detrimental effects of natural sequence variability.

Archives of Virology, Dec 7, 2018

The complete genome sequence of a novel mononegavirus, Lepeophtheirus salmonis negative-stranded ... more The complete genome sequence of a novel mononegavirus, Lepeophtheirus salmonis negative-stranded RNA virus 1 (LsN-SRV-1), obtained from a salmonid ectoparasite, Lepeophtheirus salmonis was determined. The viral genome contains five open reading frames encoding three unknown proteins (ORF I, II and III), a putative glycoprotein (G), and a large (L) protein. Phylogenetic analysis placed LsNSRV-1 in the recently established mononegaviral family Artoviridae. LsNSRV-1 showed a prevalence of around 97% and was detected in all L. salmonis developmental stages. Viral genomic and antigenomic RNA was localized to nerve tissue, connective tissue, epithelial cells of the gut, subepidermal tissue, exocrine and cement glands, as well as the testis, vas deferens and spermatophore sac of male L. salmonis and the ovaries and oocytes of females. Viral RNA was detected in both the cytoplasm and the nucleoli of infected cells, and putative nuclear export and localization signals were found within the ORF I, III and L proteins, suggesting nuclear replication of LsNSRV-1. RNA interference (RNAi) was induced twice during development by the introduction of a double-stranded RNA fragment of ORF I, resulting in a transient knockdown of viral RNA. A large variation in the knockdown level was seen in adult males and off springs of knockdown animals, whereas the RNA level was more stable in adult females. Together with the localization of viral RNA within the male spermatophore and female oocytes and the amplification of viral RNA in developing embryos, this suggests that LsNSRV-1 is transmitted both maternally and paternally. Small amounts of viral RNA were detected at the site where chalimi were attached to the skin of Atlantic salmon (Salmo salar). However, as the RNAi-mediated treatment did not result in LsNSRV-1-negative offspring and the virus failed to replicate in the tested fish cell cultures, it is difficult to investigate the influence of secreted LsNSRV-1 on the salmon immune response.

Scientific Reports, Oct 25, 2017

Rhabdoviruses are a family of enveloped negative-sense single-stranded RNA viruses infecting a va... more Rhabdoviruses are a family of enveloped negative-sense single-stranded RNA viruses infecting a variety of hosts. Recently, two vertically transmitted salmon louse (Lepeophtheirus salmonis) rhabdoviruses (LsRV) have been identified. The prevalence of these viruses was measured along the Norwegian coast and found to be close to 100%, and with the present lack of suitable cell lines to propagate these viruses, it is challenging to obtain material to study their host impact and infection routes. Thus, virus free lice strains were established from virus infected lice carrying one or both LsRVs by treating them with N protein dsRNA twice during development. The viral replication of the N protein was specifically down-regulated following introduction of virus-specific dsRNA, and virus-free lice strains were maintained for several generations. A preliminary study on infection routes suggested that the LsRV-No9 is maternally transmitted, and that the virus transmits from males to females horizontally. The ability to produce virus free strains allows for further studies on transmission modes and how these viruses influences on the L.salmonis interaction with its salmonid host. Moreover, this study provides a general fundament for future studies on how vertically transmitted rhabdoviruses influence the biology of their arthropod hosts. RNA interference (RNAi), sequence-specific post-transcriptional gene silencing, was initially discovered in transgenic tobacco plants expressing untranslated sense or antisense RNAs of a viral coat-protein gene 1,2. The transgenic plants showed anti-viral activities, however, it was later that the requirement for double stranded RNA (dsRNA) to activate the RNAi pathway was reported 3. Now it is clear that RNAi is a conserved mechanism in eukaryotic cells that can silence the gene expression of both viral and endogenous genes. Hence, it has been postulated to be a promising therapeutic method for viral diseases such as HIV, hepatitis B and the Ebola virus 4-6. As the major challenge regarding the use of RNAi as antiviral treatment in mammals has been the delivery method 7,8 , this has been more promising in invertebrates due to the systemic nature of RNAi in many of these species. Trials in farmed shrimps have shown that muscular injection of dsRNA can be used therapeutically against yellow head virus and infectious myonecrosis virus, at least to decrease the viral load and increase survival rate of infected animals 9-11. In insects such as the honeybee, oral treatment with dsRNA simultaneously with virus inoculation has been shown to induce resistance to the israeli acute paralysis virus (IAPV) 12 , and even large scale application of dsRNA against this virus has been attempted 13. Also in mosquitos such as the Aedes aegypti, a vector for many human diseases like the zika and dengue virus, trials have been performed. Genetically manipulated A. aegypti expressing inverted-repeat dengue virus RNA sequences showed an increased protection against the virus 14,15 , and recently it was shown that RNAi can be induced by soaking larvae in a dsRNA solution 16 , important for using the method as a viral control measure. Salmon louse (Lepeophtheirus salmonis Krøyer, 1838) is a marine ectoparasitic copepod on salmonid fish, representing a severe problem for the salmon farming industry due to antiparasitic treatment resistance and the consecutive impact on wild salmonid fish 17-20. Its life cycle consists of eight developmental stages each separated by a molt 21,22. The two initial instars, nauplius I and II, are planktonic, whereas the next instar, the copepodid, detects and attaches to the epidermis or gill of the host fish. Here the louse passes through two chalimus and two

Fish & Shellfish Immunology, Jul 1, 2023

BMC Genomics, Aug 19, 2015

Background: An emerging field in biomedical research is focusing on the roles of aquaporin water ... more Background: An emerging field in biomedical research is focusing on the roles of aquaporin water channels in parasites that cause debilitating or lethal diseases to their vertebrate hosts. The primary vectorial agents are hematophagous arthropods, including mosquitoes, flies, ticks and lice, however very little is known concerning the functional diversity of aquaporins in non-insect members of the Arthropoda. Here we conducted phylogenomic and functional analyses of aquaporins in the salmon louse, a marine ectoparasitic copepod that feeds on the skin and body fluids of salmonids, and used the primary structures of the isolated channels to uncover the genomic repertoires in Arthropoda. Results: Genomic screening identified 7 aquaporin paralogs in the louse in contrast to 42 in its host the Atlantic salmon. Phylogenetic inference of the louse nucleotides and proteins in relation to orthologs identified in Chelicerata, Myriapoda, Crustacea and Hexapoda revealed that the arthropod aquaporin superfamily can be classified into three major grades (1) classical aquaporins including Big brain (Bib) and Prip-like (PripL) channels (2) aquaglyceroporins (Glp) and (3) unorthodox aquaporins (Aqp12-like). In Hexapoda, two additional subfamilies exist as Drip and a recently classified entomoglyceroporin (Eglp) group. Cloning and remapping the louse cDNAs to the genomic DNA revealed that they are encoded by 1-7 exons, with two of the Glps being expressed as N-terminal splice variants (Glp1_v1, −1_v2, −3_v1, −3_v2). Heterologous expression of the cRNAs in amphibian oocytes demonstrated that PripL transports water and urea, while Bib does not. Glp1_v1, −2, −3_v1 and −3_v2 each transport water, glycerol and urea, while Glp1_v2 and the Aqp12-like channels were retained intracellularly. Transcript abundance analyses revealed expression of each louse paralog at all developmental stages, except for glp1_v1, which is specific to preadult and adult males. Conclusions: Our data suggest that the aquaporin repertoires of extant arthropods have expanded independently in the different lineages, but can be phylogenetically classified into three major grades as opposed to four present in deuterostome animals. While the aquaporin repertoire of Atlantic salmon represents a 6-fold redundancy compared to the louse, the functional assays reveal that the permeation properties of the different crustacean grades of aquaporin are largely conserved to the vertebrate counterparts.

Gene, Jun 1, 2005

Trypsins constitute a subclass of the S1A family of serine peptidases found in all groups of anim... more Trypsins constitute a subclass of the S1A family of serine peptidases found in all groups of animal and some bacteria. At present, no information about the genomic organisation of trypsins is available for copepods. The only data of copepod trypsins indicate several different trypsins in the marine parasitic copepod Lepeophtheirus salmonis. In the present study, 31.7 kbp of genomic DNA surrounding the previously described LsTryp1-5 sequences was sequenced. The sequenced regions contain nine full-length and three partial trypsin genes. A conservative estimate based on PCR analysis and genomic sequence indicated at least 22 different trypsin genes in L. salmonis, of which 18 are most similar to the previously described LsTryp1 and-2 cDNA sequences. Four of these genes are putative pseudogenes. In addition, a putative mariner like transposase gene was identified. The genomic sequences suggest that the L. salmonis trypsin genes reside within one or more gene clusters. Three different LsTryp intron exon structures were identified, and all three are different from the intron exon organisation previously reported for other S1A peptidases. This implies several intron loss and gain events in the evolution of the L. salmonis trypsin genes.

Journal of Helminthology, Mar 6, 2017

The cestode Hymenolepis microps is an intestinal parasite of tetraonid birds, including the willo... more The cestode Hymenolepis microps is an intestinal parasite of tetraonid birds, including the willow ptarmigan (Lagopus lagopus). This parasite is able to maintain a high prevalence and intensity throughout the year, even in a subarctic environment in bird populations with relatively low host densities, indicating effective transmission routes. Willow ptarmigan consume mainly vegetal material and active consumption of invertebrates is confined to the first two or three weeks of life. Ptarmigan are infected by different species of ectoparasites, of which two species of feather lice, Lagopoecus affinis and Goniodes lagopi, are the most abundant. In this study, we explored the hypothesis that feather lice may be suitable intermediate hosts for H. microps. We applied histological techniques and light microscopy to investigate lice for the presence of larval cestode stages (cysticercoids). We found 12 cysticercoid-like structures inside chewing lice collected on L. lagopus hosts harbouring H. microps. In addition, a polymerase chain reaction (PCR) screening of Ischnocera lice DNA, targeting the 18S rRNA gene of the cestode, showed positive results for two different short fragments of the 18S rRNA gene of H. microps which were sequenced from lice collected on birds. Both independent lines of evidence support the hypothesis that Ischnocera lice might be suitable intermediate hosts in the life cycle of H. microps in L. lagopus.

Fish & Shellfish Immunology

American Journal of Physiology-Heart and Circulatory Physiology, 1998

Both myocardial and plasma endothelin-1 (ET-1) are elevated in congestive heart failure (CHF). Ho... more Both myocardial and plasma endothelin-1 (ET-1) are elevated in congestive heart failure (CHF). However, the role played by endogenous ET-1 in the progression of CHF remains unknown. The aim of the present study was to investigate and correlate myocardial gene expression programs and left ventricular (LV) remodeling during chronic ET-receptor antagonism in CHF rats. After ligation of the left coronary artery, rats were randomized to oral treatment with a nonselective ET-receptor antagonist (bosentan, 100 mg ⋅ kg−1⋅ day−1, n = 11) or vehicle (saline, n = 13) for 15 days, starting 24 h after induction of myocardial infarction. Bosentan substantially attenuated LV dilatation during postinfarction failure as evaluated by echocardiography. Furthermore, bosentan decreased LV systolic and end-diastolic pressures and increased fractional shortening. Myocardial expression of preproET-1 mRNA and a fetal gene program characteristic of myocardial hypertrophy were increased in the CHF rats and we...

Extracellular views of cartoon renders of salmon louse aquaporins illustrating the ar/R constrict... more Extracellular views of cartoon renders of salmon louse aquaporins illustrating the ar/R constriction residues (spacefill) that determine the molecular selectivity of the channel. Labels are annotated as for Fig. 1 in the main text. Figure S2. Bayesian majority-rule mid-point rooted tree of an amino acid alignment of expressed transcripts in Maxillipoda. The tree was inferred from 500,000 MCMC generations on 8,085 amino acid sites. Posterior probabilities are shown at each node. Scale bar represents the number of amino acid substitutions per site. Grey bars highlight species with N-terminal splice-variants. Figure S3. Bayesian majority-rule mid-point rooted tree of a codon alignment of the aquaporin superfamilies in the Atlantic salmon and salmon louse. The tree was inferred from 1 million MCMC generations on 57,075 nucleotide sites. Posterior probabilities of the codon/amino acid analyses are shown at each node. Scale bar represents the number of nucleotide substitutions per site. F...

F1000Research, 2010

Francisella is a gram negative bacterium highly virulent in fishes and human. It could be potenti... more Francisella is a gram negative bacterium highly virulent in fishes and human. It could be potentially used for bioterrorism. Tilapia fishes are used as food resources and to control undesired aquatic plants. Francisella is causing serious problems in Tilapia that leads to mortality. The strain which is infecting Tilapia is called Francisella orientalis. It would be of high value to better understand the biology and virulence of the Francisella orientalis. We have completed the sequencing and assembly of the Francisella orientalis strain. Analysis and results are discussed below.

Scientific Reports, 2020

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.