9 research outputs found
Evoked potentials in the Atlantic cod following putatively innocuous and putatively noxious electrical stimulation: a minimally invasive approach
Aspects of peripheral and central nociception
have previously been studied through recording of
somatosensory evoked potentials (SEPs) to putative
noxious stimuli in specific brain regions in a few
freshwater fish species. In the present study, we
describe a novel, minimally invasive method for
recording SEPs from the central nervous system of the
Atlantic cod (Gadus morhua). Cutaneous electric
stimulation of the tail in 15 fish elicited SEPs at all
stimulus intensities (2, 5, 10 and 20 mA) with
quantitative properties corresponding to stimulus
intensity. In contrast to previous fish studies, the
methodological approach used in Atlantic cod in the
current study uncovered a number of additional
responses that could originate from multiple brain
regions. Several of these responses were specific to
stimulation at the highest stimulus intensities, possibly
representing qualitative differences in central processing
between somatosensory and nociceptive stimuli
Identification of a sex-linked SNP marker in the salmon louse (Lepeophtheirus salmonis) using RAD sequencing
The salmon louse (Lepeophtheirus salmonis (Krøyer, 1837)) is a parasitic copepod that can, if untreated, cause considerable damage to Atlantic salmon (Salmo salar Linnaeus, 1758) and incurs significant costs to the Atlantic salmon mariculture industry. Salmon lice are gonochoristic and normally show sex ratios close to 1:1. While this observation suggests that sex determination in salmon lice is genetic, with only minor environmental influences, the mechanism of sex determination in the salmon louse is unknown. This paper describes the identification of a sex-linked Single Nucleotide Polymorphism (SNP) marker, providing the first evidence for a genetic mechanism of sex determination in the salmon louse. Restriction site-associated DNA sequencing (RAD-seq) was used to isolate SNP markers in a laboratory-maintained salmon louse strain. A total of 85 million raw Illumina 100 base paired-end reads produced 281,838 unique RAD-tags across 24 unrelated individuals. RAD marker Lsa101901 showed complete association with phenotypic sex for all individuals analysed, being heterozygous in females and homozygous in males. Using an allele-specific PCR assay for genotyping, this SNP association pattern was further confirmed for three unrelated salmon louse strains, displaying complete association with phenotypic sex in a total of 96 genotyped individuals. The marker Lsa101901 was located in the coding region of the prohibitin-2 gene, which showed a sex-dependent differential expression, with mRNA levels determined by RT-qPCR about 1.8-fold higher in adult female than adult male salmon lice. This study's observations of a novel sex-linked SNP marker are consistent with sex determination in the salmon louse being genetic and following a female heterozygous system. Marker Lsa101901 provides a tool to determine the genetic sex of salmon lice, and could be useful in the development of control strategies
Melanogenesis in visceral tissues of Salmo salar. A link between immunity and pigment production?
Melanogenesis is mostly studied in melanocytes and melanoma cells, but much less is known about other
pigment cell systems. Liver, spleen, kidney, and other organs of lower vertebrates harbour a visceral pigment cell system with an embryonic origin that differs from that of melanocytes. In teleosts, melanin-containing
cells occur in the reticulo-endothelial system and are mainly in the kidney and spleen. The Atlantic salmon (Salmo salar L.) is an ichthyic breeding species of considerable economic importance. The accumulation of pigments in salmon visceral organs and musculature adversely affects the quality of fish products and is a problem for the aquaculture industry. With the aim to reveal novel functions and behaviour of the salmonid extracutaneous pigment system, we investigated aspects of
the melanogenic systems in the tissues of Atlantic salmon, as well as in SHK-1 cells, which is a long-term cell line derived from macrophages of the Atlantic salmon head-kidney. We demonstrate that a melanogenic system is present in SHK-1 cells, head-kidney, and spleen tissues. As teleosts lack lymph nodes and Peyerâs patches, the head-kidney and spleen are regarded as the most important secondary lymphoid organs. The detection of tyrosinase activity in lymphoid organs indicates that a link exists between the extracutaneous pigmentary system and the immune system in salmo
MELANOGENESIS IN VISCERAL TISSUES OF SALMO SALAR. A LINK BETWEEN IMMUNITY AND PIGMENT PRODUCTION?
Melanogenesis is mostly studied in melanocytes and melanoma cells, but much less is known about other
pigment cell systems. Liver, spleen, kidney, and other organs of lower vertebrates harbour a visceral pigment cell system
with an embryonic origin that differs from that of melanocytes distinct embryonic origin. In teleosts, melanin-containing
cells occur in the reticulo-endothelial system and are mainly in the kidney and spleen. The Atlantic salmon (Salmo salar
L.) is an ichthyic breeding species of considerable economic importance. The accumulation of pigments in salmon visceral
organs and musculature adversely affects the quality of fish products and is a problem for the aquaculture industry. With
the aim to reveal novel functions and behaviour of the salmonid extracutaneous pigment system, we investigated aspects of
the melanogenic systems in the tissues of Atlantic salmon, as well as in SHK-1 cells, which is a long-term cell line derived
from macrophages of the Atlantic salmon head-kidney. We demonstrate that a melanogenic system is present in SHK-1
cells, head-kidney, and spleen tissues. As teleosts lack lymph nodes and Peyerâs patches, the head-kidney and spleen are
regarded as the most important secondary lymphoid organs. The detection of tyrosinase activity in lymphoid organs
indicates that a link exists between the extracutaneous pigmentary system and the immune system in salmon
Endocrine Disruption and Organochlorine Pesticides
Le plus ancien rĂ©cit de lutte contre la pollution remonte Ă une lĂ©gende indienne racontant que la divinitĂ© Sing-bonga Ă©tait incommodĂ©e par les Ă©manations des fours dans lesquels les Asuras fondaient leurs mĂ©taux (1). Evidemment depuis, la problĂ©matique nâa cessĂ© de sâaccroĂźtre et la contamination de la Terre par de nombreux polluants est devenue aujourdâhui un problĂšme majeur de notre SociĂ©tĂ©. La protection de notre environnement est une question capitale qui doit ĂȘtre respectĂ©e malgrĂ© la pression Ă©conomique actuelle et qui ne cessera de croĂźtre au cours des prochaines annĂ©es mĂȘme si lâidentification objective et indiscutable de ce qui est essentiel â donc devant ĂȘtre prioritairement garanti sur la planĂšte â est difficile Ă cerner (2). « Un oiseau en mauvais Ă©tat ne pond pas de bons oeufs » disait un proverbe grec. Mais ce nâest quâĂ partir de la seconde moitiĂ© du XXĂšme siĂšcle que les toxicologues ont commencĂ© Ă identifier les effets quâavaient entraĂźnĂ©s Ă lâĂ©chelle mondiale les pollutions Ă©mises aux XIXĂšme siĂšcle sur la faune sauvage et sur le cheptel (3). Lâhistoire contemporaine des pesticides industriels commence vers 1874 (synthĂšse des organochlorĂ©s) et se poursuit tout au long de ces 2 siĂšcles en passant par la synthĂšse des organophosphorĂ©s (1950), des carbamates (1970) et des pyrĂ©throĂŻdes (1975) (4). Le dichlorodiphĂ©nyltrichloroĂ©thane (DDT) a Ă©tĂ© synthĂ©tisĂ© pour la premiĂšre fois par un Ă©tudiant en cours de prĂ©paration de sa thĂšse de doctorat : Othmer Zeidler. La production, reprise par les entreprises F.Mayo puis par la Geigy Co. a dâabord intĂ©ressĂ© lâarmĂ©e, puis lâagriculture. DĂšs la fin de la 2Ăšme guerre mondiale, des mises en garde furent lancĂ©es Ă propos des effets nocifs du produit (4). Un dĂ©clin des populations de grives, dâaigles chauves, dâorfaies et de mammifĂšres consommateurs de poissons fut constatĂ© Ă partir des annĂ©es 50 et dĂ©noncĂ© par Rachel Carson dans son cĂ©lĂšbre appel du « Silent Spring » de 1962. Bien quâil soit interdit en Occident depuis les annĂ©es 70, ce produit a Ă©tĂ© tellement utilisĂ© et prĂ©sente une rĂ©manence si longue quâune contamination ubiquitaire existe aujourdâhui encore. De plus, ce produit continue Ă ĂȘtre produit aux USA pour ĂȘtre utilisĂ© Ă des fins de dĂ©moustification dans les pays en voie de dĂ©veloppement. Il en va de mĂȘme de lâHexachlorobenzĂšne (HCB), un autre organochlorĂ© dont lâusage est interdit sous nos latitudes, mais reste frĂ©quent dans dâautres pays. Ces deux exemples indiquent que le problĂšme de la contamination continue Ă nous concerner, mĂȘme pour des produits dont lâusage est aujourdâhui strictement rĂ©glementĂ© ou interdit. Des effets sur la faune semblent encore actuellement devoir ĂȘtre attribuĂ©s Ă ces produits. La diminution de la population des phoques dans la mer de Wadden pourrait ĂȘtre due Ă la forte contamination en composants organochlorĂ©s des poissons dont ces phoques se nourrissent (5). ExposĂ© au DDT et Ă son mĂ©tabolite dichlorodiphenyldichloroĂ©thylĂšne (DDE), le Seratherodon mossambicus prĂ©sente une rĂ©duction de la sĂ©crĂ©tion de cortisol par une action toxique cytospĂ©cifique sur lâaxe hypothalamo-hypophysaire (6). Des travaux rĂ©cents ont montrĂ© que le DDT et le DDE se lient chez les oiseaux et les mammifĂšres au moyen de liaisons covalentes aux cellules de la zona fasciculata - homologue du tissu interrĂ©nal du poisson - induisant des microhĂ©morragies. Cette « dĂ©faillance » cortisolique peut sâaccompagner dâune perturbation du mĂ©tabolisme glucidique et notamment dâun taux Ă©levĂ© de glycogĂšne hĂ©patique (7). Les pesticides organochlorĂ©s (DDT, DDE) entraĂźnent Ă©galement des perturbations dâordre mĂ©tabolique chez certaines espĂšces dâoiseaux, notamment le faucon pĂšlerin en Grande Bretagne et les oiseaux piscivores des grands lacs nord amĂ©ricains oĂč lâon a constatĂ© au cours des annĂ©es 1960 que leur reproduction Ă©tait menacĂ©e et quâune des manifestations les plus Ă©videntes des perturbations observĂ©es Ă©tait le taux Ă©levĂ© de malformations (8). Des mortalitĂ©s Ă©levĂ©es de poissons ou de coquillages ont Ă©tĂ© rapportĂ©es dans des Ă©levages situĂ©s Ă proximitĂ© des zones dâĂ©pandage de pesticides organophosphorĂ©s et de carbamates. En 1991, la dispersion aĂ©rienne de fenitrothion dans le but de provoquer la dĂ©moustication en Languedoc a Ă©tĂ© Ă lâorigine de la perte de plusieurs tonnes de crevettes japonaises. Lâutilisation de trichlorfon et de dichlorvos comme antiparasitaires dans des fermes dâĂ©levages de saumons a provoquĂ© des Ă©pisodes de mortalitĂ© importante (9).Xenoestrogens such organochlorine pesticides are known to induce changes in reproductive development, function or behaviour in wildlife. Because these compounds are able to modify the estrogens metabolism, or to compete with estradiol for binding to the estrogen receptor, it may be possible that these products affect the risk of developing impaired fertility, precocious puberty or some kinds of cancer in man