Canadian Journal of Fisheries and Aquatic Sciences, 2016
Assessment of stress from varied sources is usually evaluated using individuals derived from a si... more Assessment of stress from varied sources is usually evaluated using individuals derived from a single population and is assumed to represent all populations of that species. However, recent research has identified intraspecies variations in the stress response, which may be mediated by life history. We examined how life history can influence the physiological responses to an acute stress event by evaluating sea lamprey (Petromyzon marinus) parasitism response in two lake trout (Salvelinus namaycush) morphotypes: the lean and the siscowet. The morphotypes differ in that the lean grows faster, is more fecund, and has a shorter life span. In contrast, the siscowet grows slower, is older at maturity, and lives longer. Our study compared long-term parasitism responses between wild leans and siscowets in Lake Superior and immediate responses in laboratory parasitism trials using lake trout reared under common environmental conditions. Leans, but not siscowets, showed changes in steroid-bi...
Rainbow trout can smell virus and bacteria cues that in turn activate an immune response in the b... more Rainbow trout can smell virus and bacteria cues that in turn activate an immune response in the brain in absence of a systemic response (i.e. the immune response is activated by the nervous system instead of the pathogen inside tissues or bloodstream). However, little is known if pathogen odors can elicit different physiological responses (i.e. behavioral and immune) and how are pathogen odors integrated into different responses in the brain. We hypothesize that pathogen odors not only activate immune responses but also induce avoidance behavior. Moreover, we hypothesized that pathogen olfactory responses are modulated by neurosteroids at different times in different parts of the brain. We used a two-choice maze test to determine whether inactivated Yersinia ruckeri elicits aversive behavior. Furthermore, to check if behavioral and immune responses are modulated by neurosteroids, we performed a second experiment where we nasally administered inactivated Y. ruckeri to rainbow trout. After that, the nose, olfactory bulb, cerebellum, and optic tectum were collected at four different time points (15 min, 4 hours, 24 hours, and 7 days) and samples were extracted to measure gene expression of several steroidogenic enzymes ( cyp19a1, 3βHSD, 11HSD, and 17HSD) and fish production of neurosteroids (e.g. cortisol, estradiol, and progesterone). We found that rainbow trout actively avoids pathogen odors. Moreover, we found a different expression of neuro steroidogenic enzymes at different brain areas and times post-exposure. Fish exposed to pathogen odor express a significant increase (ANOVA 2 factor, P<0.05) of cyp19a1 (involved in estradiol synthesis) as soon as 15 min in the nose and olfactory bulb, and 4 hours post-exposure in the cerebellum and optic tectum. This gene expression was parallel to a significant increase of estradiol in the nose, bulb, and rest of the brain between 15 min and 4 hours. Moreover, there was a significant increase of 11HSD and 17HSD (related to the production of testosterone, cortisol, and corticosterone) 4 hours after exposure in the nose and cerebellum but a significant decrease in the olfactory bulb and optic tectum. These gene expression patterns were parallel o an increase of cortisol in the nose and olfactory bulb. Finally, we found a significant increase of 3βHSD (involved in the first steps of steroidogenesis) after 24 hours in the nose and olfactory bulb, although we didn’t find an increase in steroid production in our preliminary assays. Our results showed that exposure to pathogen odors activates different neuro steroidogenic pathways at different times after exposure, and at different areas of the brain. These findings pinpoint the use of the sense of smell by fish to control behavioral and immune responses to pathogens, with neurosteroids playing a key role in modulating and integrating these olfactory responses. This material is based upon work supported by the National Science Foundation under Grant No. 1755348 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Abstract: Eels of the Genus Anguilla are important fish in both scientific and economic terms. Un... more Abstract: Eels of the Genus Anguilla are important fish in both scientific and economic terms. Unfortunately, current stocks of the European eel in particular (Anguilla anguilla L.) are becoming increasingly endangered. Chemical communication plays important roles in several key aspects of fish biology. Due to its complex life-cycle, the eel offers a unique opportunity to study various aspects of olfactory biology and chemical communication almost in isolation, feeding (during freshwateryellow'stage), adaptation to seawater, migration ...
Striped Bass Morone saxatilis are an iconic North American fish. This species, and it’s hybrid wi... more Striped Bass Morone saxatilis are an iconic North American fish. This species, and it’s hybrid with White Bass Morone chrysops, Palmetto Bass are intensively cultured for stocking into Texas water bodies. However, a large proportion of hatchery‐spawned Palmetto Bass larvae were recently plagued with malformations. Pug headedness is a common malformation that restricts the fish’s ability to intake food by misshaping the skull and mouth. Malformations such as this drastically reduce larval survival. Female Striped Bass broodfish used to produce Palmetto Bass are caught in the wild, hormonally induced to maturation, transported to the hatchery, and hand‐spawned by stripping. Consequently, we hypothesize that this extreme handling stress affects larval development and viability. Eight Striped Bass females were strip‐spawned, and samples of plasma, ovary, eggs, and hatchlings where collected to measure the concentrations of glucose, lactate and cortisol. Percentage of hatch, malformations and viability were also recorded for each spawn. A standard ELISA plate was used to measure cortisol and colorimetric protocols were used to measure glucose and lactate. Females that produced spawns with lower hatch (9.9 %) and larvae with elevated malformations rates (53.2%) showed significantly higher concentrations of plasma cortisol (290.7 ± 80.7 ng/mL) than females associated with low larval malformation rates (120.6 ± 16.0 ng/mL). Interestingly, females with low hatching rate had significantly less cortisol in ovarian tissue but more cortisol in their eggs than females with a higher performance. Spawns with higher malformation rates also had higher values of larval tissue cortisol (4.5 ± 1.0 ng/g) than spawns with lower malformation rates (0.2 ± 0.0 ng/g). This data points to a transfer of cortisol from maternal gonads to the spawn while under handling stress. Glucose and lactate had similar values in all individuals. Thus, only cortisol correlated with the presence of malformations in larvae. This study demonstrates the need to reduce handling stress in Striped Bass culture to minimize the production of malformed larvae. The impact of integrating saltwater baths, anesthetics, and reducing handling time, can be easily monitored with cortisol measurements and may improve production outcomes.
Around 50% of fish consumption comes from aquaculture. An increase in world population and food d... more Around 50% of fish consumption comes from aquaculture. An increase in world population and food demands requires fish production to dramatically increase over the next decade. One of the major obstacles of increasing aquaculture production is disease. Thus, a key aspect of aquaculture research is understanding immune health and the spread of disease within farmed populations and into wild stocks. A major portal for pathogen entry in fish is the nose; nasal infections tend to be severe and result in damage to the olfactory and nervous systems. Immune health is impacted by numerous systems including the microbiome. The microbiome trains the immune system, provides a barrier for pathogens, and helps maintain homeostasis. Therefore, dysbiosis, a disruption of the microbiome due to changes in diet, exposure to pollutants, antibiotic consumption, and physiological stress, can contribute to disease. One common pollutant in water is agricultural runoff containing nitrates and nitrites, which are known to cause stress in fish and can be deadly in some concentrations. However, it is unknown how nitrites impact the microbiomes of sensitive tissues and how these changes impact immune health. I hypothesize that increased nitrite concentrations will cause dysbiosis of the microbiome resulting in changing abundance and diversity of the microbiome. This work aims to determine the impacts of sublethal levels of nitrite on the nasal microbiome and compare it to the microbiomes of the gills and gut. For 2 months goldfish (10 fish/30L tank) were held under various nitrite concentrations, 0.0mM (control), 0.01mM, 0.1mM, and 1.0mM. The system utilized continuous aerated water flow at 24°C to maintain the desired concentrations of nitrite. Tissue samples were collected from each fish with water collected to serve as a control to determine the host‐specific microbiome. The DNA from the tissues were extracted, amplified, and prepared as a library for sequencing using 16S rRNA gene primers for Illumina MiSeq. The sequences were analyzed using the DADA2 pipeline in R and MaAsLin from Galaxy. The gill microbiome showed no significant changes in abundance compared to the control treatment. The nose microbiome appears to show an increase in diversity compared to the control microbiome; however, these changes were not determined to be significant. Both the gut and water microbiomes showed significant changes in abundance compared to their control levels, with the gut microbiome changing the most. Sublethal levels of nitrite exposure significantly increase the diversity of the microbial communities of the water and the gut microbiomes. There are also some indications that the nose and gill microbiomes are impacted, however, small sample sizes could be obscuring the changes. These impacts imply that sublethal nitrite concentrations can cause dysbiosis of the fish microbiomes and could have negative impacts of fish health.
General and Comparative Endocrinology, Jul 1, 2006
This study was aimed to investigate whether sexual maturation of immature male eels could be stim... more This study was aimed to investigate whether sexual maturation of immature male eels could be stimulated indirectly by placing them in contact with either male (Minj) or female (Finj) eels in which sexual maturation had been stimulated directly by weekly injections of human chorionic gonadotropin (hCG) or salmon pituitary extract (SPE), respectively. Untreated males were placed either in the same tank or in a separate tank that was linked to the injected fish via a recirculation system. The hormonal treatments stimulated spermatogenesis and spermiation in Minj, and ovulation in Finj as well as an increase of the ocular (Io) and gonadosomatic (GSI) indices in both sexes. Plasma levels of testosterone (T) and 11-ketotestosterone (11-KT) increased in Minj and T and 17beta-estradiol (E2) in Finj. A small peak of plasma 17,20beta-dihydroxypregn-4-en-3-one (17,20betaP) occurred during ovulation, while the plasma levels of 17alpha-hydroxypregn-4-ene-3,20-dione (17P) were undetectable in both males and females. The water conditioned by Minj and Finj induced significant, though relatively minor, increases in Io and GSI in uninjected males. In addition, uninjected fish showed small changes in plasma T and 11-KT levels, apparently related to the timing of spermiation and ovulation of Minj and Finj, respectively, as well as an activation of spermatogenesis (but not spermiation). Injected fish released free and conjugated T, 11-KT and E2 into the water, although immature eels were unable to smell (by electro-olfactogram) any of these steroids or prostaglandin F2alpha. However, immature males were highly sensitive to water extracts conditioned by spermiating Minj and pre-ovulatory and ovulated Finj. These preliminary results suggest the existence of chemical communication between maturing eels and immature males that stimulates gonad development, although the putative pheromone(s) involved has/have not yet been identified.
Anosmia, loss of smell, is a prevalent symptom of SARS-CoV-2 infection. Anosmia may be explained ... more Anosmia, loss of smell, is a prevalent symptom of SARS-CoV-2 infection. Anosmia may be explained by several mechanisms driven by infection of non-neuronal cells and damage in the nasal epithelium rather than direct infection of olfactory sensory neurons (OSNs). Previously, viral proteins have been shown to be sufficient to cause neuroimmune responses in the olfactory organ (OO) by our group. We hypothesize that SARS-CoV-2 spike (S) protein is sufficient to cause olfactory damage and olfactory dysfunction. Using an adult zebrafish model, we report that intranasally delivered SARS-CoV-2 S RBD mostly binds to the non-sensory epithelium of the olfactory organ and causes severe olfactory histopathology characterized by loss of cilia, hemorrhages and edema. Electrophysiological recordings reveal impaired olfactory function to both food and bile odorants in animals treated intranasally with SARS-CoV-2 S RBD. However, no loss of behavioral preference for food was detected in SARS-CoV-2 S RBD treated fish. Single cell RNA-Seq of the adult zebrafish olfactory organ indicated widespread loss of olfactory receptor expression and inflammatory responses in sustentacular, endothelial, and myeloid cell clusters along with reduced numbers of Tregs. Combined, our results demonstrate that intranasal SARS-CoV-2 S RBD is sufficient to cause structural and functional damage to the zebrafish olfactory system. These findings may have implications for intranasally delivered vaccines against SARS-CoV-2.
ABSTRACT Two experiments were carried out in which male and female tench Tinca tinca were placed ... more ABSTRACT Two experiments were carried out in which male and female tench Tinca tinca were placed in individual containers and tritiated steroids then added to the water. Water samples were collected over the next 6 or 7 h and the fish then sacrificed, bled and the gall bladder removed. Radioactivity was counted in all the samples. Over the course of the exposure period in the first experiment (7 h), radioactivity of 11‐ketotestosterone (11‐KT) in the water was depleted by 11%, 17,20β‐dihydroxypregn‐4‐en‐3‐one (17,20ß‐P) and 17,20α‐dihydroxypregn‐4‐en‐3‐one (17,20α‐P) by 28%, testosterone (T) by 56% and androstenedione (AD) by 68%. HPLC analysis of water samples at 3 h indicated that none of the steroids was extensively metabolized during the experiment. Females had a faster rate of uptake of AD than males. In the second experiment (6 h), radioactivity of cortisol in the water was depleted by 5%, 11‐KT by 7%, 17‐hydroxypregnen‐4‐ene (17‐P) by 17%, 17β‐oestradiol (E2) by 35%, T by 37% and AD by 44%. In both experiments, the amounts of radioactivity that were recovered from the gall bladder and plasma were positively correlated with the rate of disappearance of radioactivity from the water. The ability of the steroids to bind to sex steroid binding protein (SBP) of tench plasma was tested by incubating plasma with radioactive steroids and then separating bound and free with ice cold dextran‐coated charcoal. When plasma at a final dilution of 1 : 60 (v/v) was incubated with 5 nM of each steroid, the percentage of radiolabel bound to SBP was: T 48% AD 44%, E2 30%, 17‐P 17%, 11‐KT 13·2%, 17,20α‐P 10·3%, 17,20β‐P 4·5% and cortisol 0%. Saturation analysis established dissociation constants (Kd; mean ± s.e.) of 3·4 ± 0·4, 2·2 ± 0·2, 4·0 ± 0·3. 9·0 ± 2·8 and 51·8 nM and binding capacities (Bmax) of 201 ± 29, 201 ± 33, 165 ± 3, 187 ± 15 and 13·4 nM for T, AD, E2,17‐P and 17,20β‐P respectively. The ability of steroids to displace tritiated T and AD from SBP was in the rank order AD > T > E2 > 17,20αP = 17,20β‐P = 11‐KT = 17‐P > cortisol. Thus, the ability of tench plasma to bind certain steroids showed a relatively strong correlation with the ability of the fish to take up these steroids from water. Modelling of data for AD and 17,20β‐P helped to show why and how plasma binding had a strong influence on the rate of uptake (and hence release) of the steroids.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2005
Cerda, Joan ... et al.-- Abstracts of the Annual Main Meeting of the Society for Experimental Bio... more Cerda, Joan ... et al.-- Abstracts of the Annual Main Meeting of the Society for Experimental Biology, A2 Genomics in Aquaculture, 11-15 July 2005, Universitat Autonoma de Barcelona, Barcelona, Spain.-- 1 page
Anosmia, loss of smell, is a prevalent symptom of SARS-CoV-2 infection. Anosmia may be explained ... more Anosmia, loss of smell, is a prevalent symptom of SARS-CoV-2 infection. Anosmia may be explained by several mechanisms driven by infection of non-neuronal cells and damage in the nasal epithelium rather than direct infection of olfactory sensory neurons (OSNs). Previously, viral proteins have been shown to be sufficient to cause neuroimmune responses in the olfactory organ (OO) by our group. We hypothesize that SARS-CoV-2 spike (S) protein is sufficient to cause olfactory damage and olfactory dysfunction. Using an adult zebrafish model, we report that intranasally delivered SARS-CoV-2 S RBD mostly binds to the non-sensory epithelium of the olfactory organ and causes severe olfactory histopathology characterized by loss of cilia, hemorrhages and edema. Electrophysiological recordings reveal impaired olfactory function to both food and bile odorants in animals treated intranasally with SARS-CoV-2 S RBD. However, no loss of behavioral preference for food was detected in SARS-CoV-2 S RBD treated fish. Single cell RNA-Seq of the adult zebrafish olfactory organ indicated widespread loss of olfactory receptor expression and inflammatory responses in sustentacular, endothelial, and myeloid cell clusters along with reduced numbers of Tregs. Combined, our results demonstrate that intranasal SARS-CoV-2 S RBD is sufficient to cause structural and functional damage to the zebrafish olfactory system. These findings may have implications for intranasally delivered vaccines against SARS-CoV-2.
Canadian Journal of Fisheries and Aquatic Sciences, 2016
Assessment of stress from varied sources is usually evaluated using individuals derived from a si... more Assessment of stress from varied sources is usually evaluated using individuals derived from a single population and is assumed to represent all populations of that species. However, recent research has identified intraspecies variations in the stress response, which may be mediated by life history. We examined how life history can influence the physiological responses to an acute stress event by evaluating sea lamprey (Petromyzon marinus) parasitism response in two lake trout (Salvelinus namaycush) morphotypes: the lean and the siscowet. The morphotypes differ in that the lean grows faster, is more fecund, and has a shorter life span. In contrast, the siscowet grows slower, is older at maturity, and lives longer. Our study compared long-term parasitism responses between wild leans and siscowets in Lake Superior and immediate responses in laboratory parasitism trials using lake trout reared under common environmental conditions. Leans, but not siscowets, showed changes in steroid-bi...
Rainbow trout can smell virus and bacteria cues that in turn activate an immune response in the b... more Rainbow trout can smell virus and bacteria cues that in turn activate an immune response in the brain in absence of a systemic response (i.e. the immune response is activated by the nervous system instead of the pathogen inside tissues or bloodstream). However, little is known if pathogen odors can elicit different physiological responses (i.e. behavioral and immune) and how are pathogen odors integrated into different responses in the brain. We hypothesize that pathogen odors not only activate immune responses but also induce avoidance behavior. Moreover, we hypothesized that pathogen olfactory responses are modulated by neurosteroids at different times in different parts of the brain. We used a two-choice maze test to determine whether inactivated Yersinia ruckeri elicits aversive behavior. Furthermore, to check if behavioral and immune responses are modulated by neurosteroids, we performed a second experiment where we nasally administered inactivated Y. ruckeri to rainbow trout. After that, the nose, olfactory bulb, cerebellum, and optic tectum were collected at four different time points (15 min, 4 hours, 24 hours, and 7 days) and samples were extracted to measure gene expression of several steroidogenic enzymes ( cyp19a1, 3βHSD, 11HSD, and 17HSD) and fish production of neurosteroids (e.g. cortisol, estradiol, and progesterone). We found that rainbow trout actively avoids pathogen odors. Moreover, we found a different expression of neuro steroidogenic enzymes at different brain areas and times post-exposure. Fish exposed to pathogen odor express a significant increase (ANOVA 2 factor, P<0.05) of cyp19a1 (involved in estradiol synthesis) as soon as 15 min in the nose and olfactory bulb, and 4 hours post-exposure in the cerebellum and optic tectum. This gene expression was parallel to a significant increase of estradiol in the nose, bulb, and rest of the brain between 15 min and 4 hours. Moreover, there was a significant increase of 11HSD and 17HSD (related to the production of testosterone, cortisol, and corticosterone) 4 hours after exposure in the nose and cerebellum but a significant decrease in the olfactory bulb and optic tectum. These gene expression patterns were parallel o an increase of cortisol in the nose and olfactory bulb. Finally, we found a significant increase of 3βHSD (involved in the first steps of steroidogenesis) after 24 hours in the nose and olfactory bulb, although we didn’t find an increase in steroid production in our preliminary assays. Our results showed that exposure to pathogen odors activates different neuro steroidogenic pathways at different times after exposure, and at different areas of the brain. These findings pinpoint the use of the sense of smell by fish to control behavioral and immune responses to pathogens, with neurosteroids playing a key role in modulating and integrating these olfactory responses. This material is based upon work supported by the National Science Foundation under Grant No. 1755348 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Abstract: Eels of the Genus Anguilla are important fish in both scientific and economic terms. Un... more Abstract: Eels of the Genus Anguilla are important fish in both scientific and economic terms. Unfortunately, current stocks of the European eel in particular (Anguilla anguilla L.) are becoming increasingly endangered. Chemical communication plays important roles in several key aspects of fish biology. Due to its complex life-cycle, the eel offers a unique opportunity to study various aspects of olfactory biology and chemical communication almost in isolation, feeding (during freshwateryellow'stage), adaptation to seawater, migration ...
Striped Bass Morone saxatilis are an iconic North American fish. This species, and it’s hybrid wi... more Striped Bass Morone saxatilis are an iconic North American fish. This species, and it’s hybrid with White Bass Morone chrysops, Palmetto Bass are intensively cultured for stocking into Texas water bodies. However, a large proportion of hatchery‐spawned Palmetto Bass larvae were recently plagued with malformations. Pug headedness is a common malformation that restricts the fish’s ability to intake food by misshaping the skull and mouth. Malformations such as this drastically reduce larval survival. Female Striped Bass broodfish used to produce Palmetto Bass are caught in the wild, hormonally induced to maturation, transported to the hatchery, and hand‐spawned by stripping. Consequently, we hypothesize that this extreme handling stress affects larval development and viability. Eight Striped Bass females were strip‐spawned, and samples of plasma, ovary, eggs, and hatchlings where collected to measure the concentrations of glucose, lactate and cortisol. Percentage of hatch, malformations and viability were also recorded for each spawn. A standard ELISA plate was used to measure cortisol and colorimetric protocols were used to measure glucose and lactate. Females that produced spawns with lower hatch (9.9 %) and larvae with elevated malformations rates (53.2%) showed significantly higher concentrations of plasma cortisol (290.7 ± 80.7 ng/mL) than females associated with low larval malformation rates (120.6 ± 16.0 ng/mL). Interestingly, females with low hatching rate had significantly less cortisol in ovarian tissue but more cortisol in their eggs than females with a higher performance. Spawns with higher malformation rates also had higher values of larval tissue cortisol (4.5 ± 1.0 ng/g) than spawns with lower malformation rates (0.2 ± 0.0 ng/g). This data points to a transfer of cortisol from maternal gonads to the spawn while under handling stress. Glucose and lactate had similar values in all individuals. Thus, only cortisol correlated with the presence of malformations in larvae. This study demonstrates the need to reduce handling stress in Striped Bass culture to minimize the production of malformed larvae. The impact of integrating saltwater baths, anesthetics, and reducing handling time, can be easily monitored with cortisol measurements and may improve production outcomes.
Around 50% of fish consumption comes from aquaculture. An increase in world population and food d... more Around 50% of fish consumption comes from aquaculture. An increase in world population and food demands requires fish production to dramatically increase over the next decade. One of the major obstacles of increasing aquaculture production is disease. Thus, a key aspect of aquaculture research is understanding immune health and the spread of disease within farmed populations and into wild stocks. A major portal for pathogen entry in fish is the nose; nasal infections tend to be severe and result in damage to the olfactory and nervous systems. Immune health is impacted by numerous systems including the microbiome. The microbiome trains the immune system, provides a barrier for pathogens, and helps maintain homeostasis. Therefore, dysbiosis, a disruption of the microbiome due to changes in diet, exposure to pollutants, antibiotic consumption, and physiological stress, can contribute to disease. One common pollutant in water is agricultural runoff containing nitrates and nitrites, which are known to cause stress in fish and can be deadly in some concentrations. However, it is unknown how nitrites impact the microbiomes of sensitive tissues and how these changes impact immune health. I hypothesize that increased nitrite concentrations will cause dysbiosis of the microbiome resulting in changing abundance and diversity of the microbiome. This work aims to determine the impacts of sublethal levels of nitrite on the nasal microbiome and compare it to the microbiomes of the gills and gut. For 2 months goldfish (10 fish/30L tank) were held under various nitrite concentrations, 0.0mM (control), 0.01mM, 0.1mM, and 1.0mM. The system utilized continuous aerated water flow at 24°C to maintain the desired concentrations of nitrite. Tissue samples were collected from each fish with water collected to serve as a control to determine the host‐specific microbiome. The DNA from the tissues were extracted, amplified, and prepared as a library for sequencing using 16S rRNA gene primers for Illumina MiSeq. The sequences were analyzed using the DADA2 pipeline in R and MaAsLin from Galaxy. The gill microbiome showed no significant changes in abundance compared to the control treatment. The nose microbiome appears to show an increase in diversity compared to the control microbiome; however, these changes were not determined to be significant. Both the gut and water microbiomes showed significant changes in abundance compared to their control levels, with the gut microbiome changing the most. Sublethal levels of nitrite exposure significantly increase the diversity of the microbial communities of the water and the gut microbiomes. There are also some indications that the nose and gill microbiomes are impacted, however, small sample sizes could be obscuring the changes. These impacts imply that sublethal nitrite concentrations can cause dysbiosis of the fish microbiomes and could have negative impacts of fish health.
General and Comparative Endocrinology, Jul 1, 2006
This study was aimed to investigate whether sexual maturation of immature male eels could be stim... more This study was aimed to investigate whether sexual maturation of immature male eels could be stimulated indirectly by placing them in contact with either male (Minj) or female (Finj) eels in which sexual maturation had been stimulated directly by weekly injections of human chorionic gonadotropin (hCG) or salmon pituitary extract (SPE), respectively. Untreated males were placed either in the same tank or in a separate tank that was linked to the injected fish via a recirculation system. The hormonal treatments stimulated spermatogenesis and spermiation in Minj, and ovulation in Finj as well as an increase of the ocular (Io) and gonadosomatic (GSI) indices in both sexes. Plasma levels of testosterone (T) and 11-ketotestosterone (11-KT) increased in Minj and T and 17beta-estradiol (E2) in Finj. A small peak of plasma 17,20beta-dihydroxypregn-4-en-3-one (17,20betaP) occurred during ovulation, while the plasma levels of 17alpha-hydroxypregn-4-ene-3,20-dione (17P) were undetectable in both males and females. The water conditioned by Minj and Finj induced significant, though relatively minor, increases in Io and GSI in uninjected males. In addition, uninjected fish showed small changes in plasma T and 11-KT levels, apparently related to the timing of spermiation and ovulation of Minj and Finj, respectively, as well as an activation of spermatogenesis (but not spermiation). Injected fish released free and conjugated T, 11-KT and E2 into the water, although immature eels were unable to smell (by electro-olfactogram) any of these steroids or prostaglandin F2alpha. However, immature males were highly sensitive to water extracts conditioned by spermiating Minj and pre-ovulatory and ovulated Finj. These preliminary results suggest the existence of chemical communication between maturing eels and immature males that stimulates gonad development, although the putative pheromone(s) involved has/have not yet been identified.
Anosmia, loss of smell, is a prevalent symptom of SARS-CoV-2 infection. Anosmia may be explained ... more Anosmia, loss of smell, is a prevalent symptom of SARS-CoV-2 infection. Anosmia may be explained by several mechanisms driven by infection of non-neuronal cells and damage in the nasal epithelium rather than direct infection of olfactory sensory neurons (OSNs). Previously, viral proteins have been shown to be sufficient to cause neuroimmune responses in the olfactory organ (OO) by our group. We hypothesize that SARS-CoV-2 spike (S) protein is sufficient to cause olfactory damage and olfactory dysfunction. Using an adult zebrafish model, we report that intranasally delivered SARS-CoV-2 S RBD mostly binds to the non-sensory epithelium of the olfactory organ and causes severe olfactory histopathology characterized by loss of cilia, hemorrhages and edema. Electrophysiological recordings reveal impaired olfactory function to both food and bile odorants in animals treated intranasally with SARS-CoV-2 S RBD. However, no loss of behavioral preference for food was detected in SARS-CoV-2 S RBD treated fish. Single cell RNA-Seq of the adult zebrafish olfactory organ indicated widespread loss of olfactory receptor expression and inflammatory responses in sustentacular, endothelial, and myeloid cell clusters along with reduced numbers of Tregs. Combined, our results demonstrate that intranasal SARS-CoV-2 S RBD is sufficient to cause structural and functional damage to the zebrafish olfactory system. These findings may have implications for intranasally delivered vaccines against SARS-CoV-2.
ABSTRACT Two experiments were carried out in which male and female tench Tinca tinca were placed ... more ABSTRACT Two experiments were carried out in which male and female tench Tinca tinca were placed in individual containers and tritiated steroids then added to the water. Water samples were collected over the next 6 or 7 h and the fish then sacrificed, bled and the gall bladder removed. Radioactivity was counted in all the samples. Over the course of the exposure period in the first experiment (7 h), radioactivity of 11‐ketotestosterone (11‐KT) in the water was depleted by 11%, 17,20β‐dihydroxypregn‐4‐en‐3‐one (17,20ß‐P) and 17,20α‐dihydroxypregn‐4‐en‐3‐one (17,20α‐P) by 28%, testosterone (T) by 56% and androstenedione (AD) by 68%. HPLC analysis of water samples at 3 h indicated that none of the steroids was extensively metabolized during the experiment. Females had a faster rate of uptake of AD than males. In the second experiment (6 h), radioactivity of cortisol in the water was depleted by 5%, 11‐KT by 7%, 17‐hydroxypregnen‐4‐ene (17‐P) by 17%, 17β‐oestradiol (E2) by 35%, T by 37% and AD by 44%. In both experiments, the amounts of radioactivity that were recovered from the gall bladder and plasma were positively correlated with the rate of disappearance of radioactivity from the water. The ability of the steroids to bind to sex steroid binding protein (SBP) of tench plasma was tested by incubating plasma with radioactive steroids and then separating bound and free with ice cold dextran‐coated charcoal. When plasma at a final dilution of 1 : 60 (v/v) was incubated with 5 nM of each steroid, the percentage of radiolabel bound to SBP was: T 48% AD 44%, E2 30%, 17‐P 17%, 11‐KT 13·2%, 17,20α‐P 10·3%, 17,20β‐P 4·5% and cortisol 0%. Saturation analysis established dissociation constants (Kd; mean ± s.e.) of 3·4 ± 0·4, 2·2 ± 0·2, 4·0 ± 0·3. 9·0 ± 2·8 and 51·8 nM and binding capacities (Bmax) of 201 ± 29, 201 ± 33, 165 ± 3, 187 ± 15 and 13·4 nM for T, AD, E2,17‐P and 17,20β‐P respectively. The ability of steroids to displace tritiated T and AD from SBP was in the rank order AD > T > E2 > 17,20αP = 17,20β‐P = 11‐KT = 17‐P > cortisol. Thus, the ability of tench plasma to bind certain steroids showed a relatively strong correlation with the ability of the fish to take up these steroids from water. Modelling of data for AD and 17,20β‐P helped to show why and how plasma binding had a strong influence on the rate of uptake (and hence release) of the steroids.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2005
Cerda, Joan ... et al.-- Abstracts of the Annual Main Meeting of the Society for Experimental Bio... more Cerda, Joan ... et al.-- Abstracts of the Annual Main Meeting of the Society for Experimental Biology, A2 Genomics in Aquaculture, 11-15 July 2005, Universitat Autonoma de Barcelona, Barcelona, Spain.-- 1 page
Anosmia, loss of smell, is a prevalent symptom of SARS-CoV-2 infection. Anosmia may be explained ... more Anosmia, loss of smell, is a prevalent symptom of SARS-CoV-2 infection. Anosmia may be explained by several mechanisms driven by infection of non-neuronal cells and damage in the nasal epithelium rather than direct infection of olfactory sensory neurons (OSNs). Previously, viral proteins have been shown to be sufficient to cause neuroimmune responses in the olfactory organ (OO) by our group. We hypothesize that SARS-CoV-2 spike (S) protein is sufficient to cause olfactory damage and olfactory dysfunction. Using an adult zebrafish model, we report that intranasally delivered SARS-CoV-2 S RBD mostly binds to the non-sensory epithelium of the olfactory organ and causes severe olfactory histopathology characterized by loss of cilia, hemorrhages and edema. Electrophysiological recordings reveal impaired olfactory function to both food and bile odorants in animals treated intranasally with SARS-CoV-2 S RBD. However, no loss of behavioral preference for food was detected in SARS-CoV-2 S RBD treated fish. Single cell RNA-Seq of the adult zebrafish olfactory organ indicated widespread loss of olfactory receptor expression and inflammatory responses in sustentacular, endothelial, and myeloid cell clusters along with reduced numbers of Tregs. Combined, our results demonstrate that intranasal SARS-CoV-2 S RBD is sufficient to cause structural and functional damage to the zebrafish olfactory system. These findings may have implications for intranasally delivered vaccines against SARS-CoV-2.
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