Molecular Markers of Yolk Sac Fry Development in Nine Families of Lake Trout

Salmonids in certain areas of North America and northern Europe suffer from reproductive disturbances manifested through the death of yolk sac fry. These disturbances are referred to as early mortality syndrome (EMS) in the Great Lakes region and M74 in the Baltic Sea. Both of these syndromes have been associated with reduced concentrations of thiamine in affected females and their eggs. However, large variations in signs and mortality, both within and between the individual syndromes, have been reported. Yolk sac fry mortality (M74) in Atlantic salmon Salmo salar has been shown to be associated with reduced DNA binding of the hypoxia-inducible transcription factor 1 (HIF-1), reduced production of vascular endothelial growth factor (VEGF) protein, decreased capillary density, and down-regulation of adult-type globin gene transcription (which is responsible for the protein part of adult hemoglobin). One of the main effects of all of these changes is reduced oxygen transport to the tissues of affected fry. In this study, the developmental patterns of HIF-1 DNA binding, VEGF protein expression, and adult-type globin gene transcription were analyzed in nine family groups of Lake Michigan lake trout Salvelinus namaycush. The results indicate that HIF-1 DNA binding and globin gene transcription increase from hatch to the end of yolk sac stage. Interindividual and between-family biological variations were detected, especially in VEGF protein expression and globin gene transcription. Our results demonstrate the possibility of using these molecular markers in investigating the etiology of EMS and making comparisons between the mechanisms of different salmonid yolk sac fry mortalities

Copepod reproductive effort and oxidative status as responses to warming in the marine environment

The marine ecosystems are under severe climate change-induced stress globally. The Baltic Sea is especially vulnerable to ongoing changes, such as warming. The aim of this study was to measure eco-physiological responses of a key copepod species to elevated temperature in an experiment, and by collecting field samples in the western Gulf of Finland. The potential trade-off between reproductive output and oxidative balance in copepods during thermal stress was studied by incubating female Acartia sp. for reproduction rate and oxidative stress measurements in ambient and elevated temperatures. Our field observations show that the glutathione cycle had a clear response in increasing stress and possibly had an important role in preventing oxidative damage: Lipid peroxidation and ratio of reduced and oxidized glutathione were negatively correlated throughout the study. Moreover, glutathione-s-transferase activated in late July when the sea water temperature was exceptionally high and Acartia sp. experienced high oxidative stress. The combined effect of a heatwave, increased cyanobacteria, and decreased dinoflagellate abundance may have caused larger variability in reproductive output in the field. An increase of 7 degrees C had a negative effect on egg production rate in the experiment. However, the effect on reproduction was relatively small, implying that Acartia sp. can tolerate warming at least within the temperature range of 9-16 degrees C. However, our data from the experiment suggest a link between reproductive success and oxidative stress during warming, shown as a significant combined effect of temperature and catalase on egg production rate.Peer reviewe

Identification of modifiable pre- and postnatal dietary and environmental exposures associated with owner-reported canine atopic dermatitis in Finland using a web-based questionnaire

A cross-sectional hypothesis generating study was performed to investigate modifiable exposures such as whether feeding pattern (a non-processed meat based diet, NPMD, or an ultra-processed carbohydrate based diet, UPCD), certain environmental factors and their timing of exposure might be associated with the development of canine atopic dermatitis (CAD). Also, genetic and demographic factors were tested for associations with CAD. The data was collected from the validated internet-based DogRisk food frequency questionnaire in Finland. A total of 2236 dogs were eligible for the study (the owners reported 406 cases and 1830 controls). Our main interest was to analyze modifiable early risk factors of CAD, focusing on nutritional and environmental factors. We tested four early life periods; prenatal, neonatal, early postnatal and late postnatal periods. Twenty-two variables were tested for associations with CAD using logistic regression analysis. From the final models we identified novel dietary associations with CAD: the NPMD during the prenatal and early postnatal periods had a significant negative association with the incidence of CAD in adult dogs (age above 1 year). Oppositely, UPCD was associated with a significantly higher risk for CAD incidence. Other variables that were associated with a significantly lower risk for CAD were maternal deworming during pregnancy, sunlight exposure during early postnatal period, normal body condition score during the early postnatal period, the puppy being born within the same family that it would stay in, and spending time on a dirt or grass surface from 2 to 6 months. Also, the genetic factors regarding maternal history of CAD, allergy-prone breeds and more than 50% white-colored coat all showed a significant positive association with CAD incidence in agreement with previous findings. Although no causality can be established, feeding NPMD early in life seemed to be protective against CAD, while UPCD could be considered a risk factor. Prospective intervention studies are needed to establish the causal effects of the protective role of NPMD on prevalence of CAD during the fetal and early postnatal life.Peer reviewe

Developmental disturbances in early life stage mortality (M74) of Baltic salmon fry as studied by changes in gene expression

BACKGROUND: We have studied alterations of gene expression associated with naturally-occurring early life stage mortality (M74) in Baltic salmon using a cDNA microarray and real time PCR. M74-affected fry have several typical neurological, cardiovascular and pathological symptoms. They are also characterized by low thiamine content and show signs of oxidative stress. RESULTS: Affected fry can be divided into three major groups with early, intermediate or late onset of mortality. If mortality starts during the first third of the yolk-sac stage, virtually all the responses are compatible with stress, which rapidly leads to the common terminal responses. If death occurs during the second third of the yolk sac stage, the terminal stage is preceded by a decrease in globin gene expression, which leads to internal hypoxia when the animals grow and shift from skin- to gill-breathing. Fry will eventually proceed to the terminal responses. The group developing M74 most slowly appears to compensate for reduced oxygen delivery by downregulation of metabolism, and hence some fry can escape death. CONCLUSION: Our study is the first demonstration of diverse transcriptional responses to a naturally-occurring developmental disturbance. Since many of the genes differentially expressed in M74-fry are evolutionarily conserved, the M74 of Baltic salmon can serve as a model for developmental disturbances and environmental stress responses in vertebrates in general

Diet and dog characteristics affect major and trace elements in hair and blood of healthy dogs

Obtaining correct amounts of essential elements, and avoiding toxic metals are key factors in dog health. Through analyzing major and trace elements in hair and blood of 50 healthy companion dogs using ICP-MS, we study their associations with dog characteristics and diet, hypothesizing that eating the same diet long-term results in strong correlations between hair and blood element concentrations, and that dog characteristics and diet affect element status. The correlation between hair and blood was significant for Hg (R = 0.601, p = 0.000) and Pb (R = 0.384, p = 0.010). The following associations were significant (p < 0.05): Dark hair had higher Ca and Mg compared to light hair. Females had higher hair Zn, blood Mn, and blood As compared to males. Blood Mn and Se increased, while blood Pb decreased with age. Raw diet fed dogs had higher hair Zn and Se compared to dry or mixed diet fed dogs, and lower blood Mn compared to dry diet fed dogs. Dry and mixed diet fed dogs had higher blood Cd compared to raw diet fed dogs. Mixed diet fed dogs had higher hair Ca and Mg compared to raw or dry diet fed dogs, and higher hair Pb compared to dry diet fed dogs. Wild game consumption was associated with higher blood Pb, and rice consumption with higher blood As. In conclusion, hair provides an alternative for assessing Hg and Pb exposure, and major and trace elements status is affected by hair color, sex, age, and diet.Peer reviewe

Copepod reproductive effort and oxidative status as responses to warming in the marine environment

The marine ecosystems are under severe climate change-induced stress globally. The Baltic Sea is especially vulnerable to ongoing changes, such as warming. The aim of this study was to measure eco-physiological responses of a key copepod species to elevated temperature in an experiment, and by collecting field samples in the western Gulf of Finland. The potential trade-off between reproductive output and oxidative balance in copepods during thermal stress was studied by incubating female Acartia sp. for reproduction rate and oxidative stress measurements in ambient and elevated temperatures. Our field observations show that the glutathione cycle had a clear response in increasing stress and possibly had an important role in preventing oxidative damage: Lipid peroxidation and ratio of reduced and oxidized glutathione were negatively correlated throughout the study. Moreover, glutathione-s-transferase activated in late July when the sea water temperature was exceptionally high and Acartia sp. experienced high oxidative stress. The combined effect of a heatwave, increased cyanobacteria, and decreased dinoflagellate abundance may have caused larger variability in reproductive output in the field. An increase of 7 degrees C had a negative effect on egg production rate in the experiment. However, the effect on reproduction was relatively small, implying that Acartia sp. can tolerate warming at least within the temperature range of 9-16 degrees C. However, our data from the experiment suggest a link between reproductive success and oxidative stress during warming, shown as a significant combined effect of temperature and catalase on egg production rate

Oxidative stress and antioxidant defense responses in Acartia copepods in relation to environmental factors

On a daily basis, planktonic organisms migrate vertically and thus experience widely varying conditions in their physico-chemical environment. In the Gulf of Finland, these changes are larger than values predicted by climate change scenarios predicted for the next century (up to 0.5 units in pH and 5 degrees C in temperature). In this work, we are interested in how temporal variations in physico-chemical characteristics of the water column on a daily and weekly scale influence oxidative stress level and antioxidant responses in the planktonic copepod of the genus Acartia. Responses were determined from samples collected during a two-week field survey in the western Gulf of Finland, Baltic Sea. Our results showed that GST (Glutathione-S-transferase) enzyme activity increased in the surface waters between Weeks I and II, indicating antioxidant defense mechanism activation. This is most likely due to elevating temperature, pH, and dissolved oxygen observed between these two weeks. During Week II also GSSG (oxidized glutathione) was detected, indicating that copepods responded to stressor(s) in the environment. Our results suggest that Acartia copepods seem fairly tolerant to weekly fluctuations in environmental conditions in coastal and estuarine areas, in terms of antioxidant defense and oxidative stress. This could be directly connected to a very efficient glutathione cycling system acting as antioxidant defense system for neutralizing ROS and avoiding elevated levels of LPX

Whole blood trace element and toxic metal concentration in dogs with idiopathic epilepsy and healthy dogs : A case-control study

Peer reviewe

The alpha v beta 1 integrin functions as a fibronectin receptor but does not support fibronectin matrix assembly and cell migration on fibronectin

The fibronectin receptor, alpha 5 beta 1, has been shown to be required for fibronectin matrix assembly and plays an important role in cell migration on fibronectin. However, it is not clear whether other fibronectin binding integrins can take the place of alpha 5 beta 1 during matrix assembly and cell migration. To test this, we expressed the human alpha v subunit in the CHO cell line CHO-B2 that lacks the alpha 5 subunit. We found that the human alpha v combined with CHO cell beta 1 to form the integrin alpha v beta 1. Cells that expressed alpha v beta 1 attached to and spread well on fibronectin-coated dishes, but did so less well on vitronectin-coated dishes. This, along with other data, indicated that alpha v beta 1 functions as a fibronectin receptor in CHO-B2 cells. The alpha v beta 1-expressing cells failed to produce a fibronectin matrix or to migrate on fibronectin, although the same cells transfected with alpha 5 do produce a matrix and migrate on fibronectin. The affinity of the alpha v beta 1-expressing cells for fibronectin was fourfold lower than that of the alpha 5 beta 1- expressing cells. In addition, alpha v beta 1 was distributed diffusely throughout the cell surface, whereas alpha 5 beta 1 was localized to focal adhesions when cells were seeded onto fibronectin-coated surfaces. Thus, of the two fibronectin receptors, alpha v beta 1 and alpha 5 beta 1, only alpha 5 beta 1 supports fibronectin matrix assembly and promotes cell migration on fibronectin in the CHO-B2 cells. Possible reasons for this difference in the activities of alpha v beta 1 and alpha 5 beta 1 include the lower affinity of alpha v beta 1 for fibronectin and the failure of this integrin to localize in adhesion plaques on a fibronectin substrate. These results show that two integrins with similar ligand specificities and cell attachment functions may be quite different in their ability to support fibronectin matrix assembly and cell motility on fibronectin