Implications of white spot syndrome virus disease on DNA integrity, histology and biochemistry of Procambarus clarkii in Egypt

White spot syndrome virus (WSSV) is a widespread and highly pathogenic virus; that infects shrimp, crayfish and other crustaceans. The objectives of the present study were to investigate WSSV implications on some crayfish tissues, within light and sever stages of infections. Several parameters have been investigated including DNA integrity, oxidative stress, and histological changes in gills, muscles and hepatopancreas cells, using several techniques such as comet assay, DNA fragmentation assay, oxidative stress biomarkers estimation and histopathological examination. Specimens were divided into three groups according to the nested PCR results. Group I included healthy specimens whose tissues were all negative two-step PCR; Group II involved lightly infected specimens with positive two-step PCR. Group III included heavily infected specimens whose tissues were tested mostly positive one-step PCR. WSSV generates an increase in the different parameters of DNA damage (P<0.05) with abnormal histological features and notable reduction (P<0.05) of the endogenous scavengers in the tested tissues of the infected crayfish in comparison with the normal healthy ones. Furthermore, gills were found to be the most affected organ followed by muscle and finally hepatopancreas. These outcomes additionally demonstrated that comet test could profitably be utilized in genotoxicity evaluation protocols in aquatic invertebrates

Vulnerability of Tunisian soil ecosystemic services to regional climatic changes : sensitivity of soil respiration to temperature

Afin de mieux comprendre et évaluer l'impact du changement climatique sur les stocks de carbone organique du sol (COS) et les flux de carbone, et en particulier la respiration hétérotrophe du sol (RS), il est nécessaire d'étudier la sensibilité de la RS à la température. Plusieurs études sur les facteurs contrôlant la dépendance de la RS à la température ont été faites antérieurement et montrent que la sensibilité de la RS à la température diminue avec la température. Ces études ont suggéré que cette diminution de sensibilité de la RS à la température était liée à la modification de la disponibilité en substrat. D'autres études ont suggéré que cette diminution est liée à l'adaptation de la communauté microbienne aux températures élevées. La sensibilité de la RS à la température est plus particulièrement critique dans les régions semi-arides, comme le Nord Ouest de la Tunisie où le stock de COS est faible. Il est nécessaire de connaître l'effet de la disponibilité en substrat sur la sensibilité de la RS à la température. Dans cette étude, les échantillons de sol ont été incubés pendant 28 jours après une période de 28 jours de pré-incubation. Les pré-incubations et incubations ont été réalisées à 20, 30, 40 et 50°C. Pour tester l'effet de la disponibilité en substrat sur la sensibilité de la RS à la température, du glucose a été ajouté au sol au début de la période d'incubation. L'analyse des résultats a montré que les températures élevées de pré-incubation réduisent la sensibilité de la RS à la température d'incubation. L'addition de glucose réduit l'effet de températures élevées de pré-incubation sur la réponse de la RS. Il apparaît ainsi que la diminution de la sensibilité de la RS après un mois de pré-incubation aux fortes températures est due à la diminution de la disponibilité en substrat. Elle semble aussi liée à une diminution de la biomasse microbienne. Puisque, le sol utilisé pour cette étude est un Cambi sol Calco-magnésimorphe, une deuxième expérimentation a été réalisée afin de déterminer la part de CO2 provenant des carbonates et la part de CO2 provenant du COS. Cette étude a été réalisée par des mesures des signatures isotopiques (δ13C) du COS, des carbonates et du CO2 émis. Après 28 jours d'incubation, 23±9% de CO2 provient des carbonates. Cette contribution est faible par rapport à la teneur initiale élevée de C-CaCO3 dans le sol (4,3%) et est indépendante de la température d'incubation. Cette étude a montré que la réduction de la sensibilité de la RS aux fortes températures est surtout liée à une réduction de la disponibilité en substrat organique et de la biomasse microbienne aux fortes températures.To better understand and assess the impact of climate change on the stocks of soil organic carbon (SOC) and carbon fluxes, and particularly heterotrophic soil respiration (SR), it is necessary to study the sensitivity of SR to temperature. Several studies have been achieved to improve the understanding of factors controlling the temperature dependence of SR and showed that the temperature sensitivity of SR decreases with temperature. These studies suggested that this decrease in temperature sensitivity of SR was related to change in substrate availability. Other studies presented microbial adaptation to warmed conditions. The temperature sensitivity of SR is especially critical in semi-arid regions, such as North West Tunisia, where the SOC stock is low. It is necessary to know the influence of substrate availability on the sensitivity of SR to temperature. In this study, soil samples were incubated for 28 days after a 28-day pre-incubation per iod. Pre-incubation and incubation were carried out at 20, 30, 40 and 50°C. To test the substrate availability effect on the temperature sensitivity of SR, glucose was added to soil at the beginning of the incubation period. Results showed that the highest pre-incubation temperature reduced the temperature sensitivity of SR during the subsequent incubation period. Glucose addition reduced the effect of high pre-incubation temperature on SR response. Thus, it appears that the observed decrease in SR sensitivity to temperature after one month pre-incubation at high temperature was due to a reduce in substrate availability and to a decrease in microbial biomass. Since the soil used in this study is a Calcari-Leptic Cambisol, a second experiment was also performed to determine the amount of CO2 from carbonates and the amount of CO2 from SOC. This study was carried out by measurements of the isotopic signatures (δ13C) of SOC, carbonates and emitted CO2. After 28 days of inc ubation, 23±9% of CO2 came from carbonates. This contribution was low compared to the high initial C-CaCO3 content in soil (4.3%), and it was independent to the incubation temperature. This study showed that reduce in the sensitivity of SR to high temperatures was probably due to a reduction in the substrate availability and to a decrease in microbial biomass

Vulnerability of Tunisian soil ecosystemic services to regional climatic changes (sensitivity of soil respiration to temperature)

Afin de mieux comprendre et évaluer l'impact du changement climatique sur les stocks de carbone organique du sol (COS) et les flux de carbone, et en particulier la respiration hétérotrophe du sol (RS), il est nécessaire d'étudier la sensibilité de la RS à la température. Plusieurs études sur les facteurs contrôlant la dépendance de la RS à la température ont été faites antérieurement et montrent que la sensibilité de la RS à la température diminue avec la température. Ces études ont suggéré que cette diminution de sensibilité de la RS à la température était liée à la modification de la disponibilité en substrat. D'autres études ont suggéré que cette diminution est liée à l'adaptation de la communauté microbienne aux températures élevées. La sensibilité de la RS à la température est plus particulièrement critique dans les régions semi-arides, comme le Nord Ouest de la Tunisie où le stock de COS est faible. Il est nécessaire de connaître l'effet de la disponibilité en substrat sur la sensibilité de la RS à la température. Dans cette étude, les échantillons de sol ont été incubés pendant 28 jours après une période de 28 jours de pré-incubation. Les pré-incubations et incubations ont été réalisées à 20, 30, 40 et 50C. Pour tester l'effet de la disponibilité en substrat sur la sensibilité de la RS à la température, du glucose a été ajouté au sol au début de la période d'incubation. L'analyse des résultats a montré que les températures élevées de pré-incubation réduisent la sensibilité de la RS à la température d'incubation. L'addition de glucose réduit l'effet de températures élevées de pré-incubation sur la réponse de la RS. Il apparaît ainsi que la diminution de la sensibilité de la RS après un mois de pré-incubation aux fortes températures est due à la diminution de la disponibilité en substrat. Elle semble aussi liée à une diminution de la biomasse microbienne. Puisque, le sol utilisé pour cette étude est un Cambi sol Calco-magnésimorphe, une deuxième expérimentation a été réalisée afin de déterminer la part de CO2 provenant des carbonates et la part de CO2 provenant du COS. Cette étude a été réalisée par des mesures des signatures isotopiques ( 13C) du COS, des carbonates et du CO2 émis. Après 28 jours d'incubation, 23+-9% de CO2 provient des carbonates. Cette contribution est faible par rapport à la teneur initiale élevée de C-CaCO3 dans le sol (4,3%) et est indépendante de la température d'incubation. Cette étude a montré que la réduction de la sensibilité de la RS aux fortes températures est surtout liée à une réduction de la disponibilité en substrat organique et de la biomasse microbienne aux fortes températures.To better understand and assess the impact of climate change on the stocks of soil organic carbon (SOC) and carbon fluxes, and particularly heterotrophic soil respiration (SR), it is necessary to study the sensitivity of SR to temperature. Several studies have been achieved to improve the understanding of factors controlling the temperature dependence of SR and showed that the temperature sensitivity of SR decreases with temperature. These studies suggested that this decrease in temperature sensitivity of SR was related to change in substrate availability. Other studies presented microbial adaptation to warmed conditions. The temperature sensitivity of SR is especially critical in semi-arid regions, such as North West Tunisia, where the SOC stock is low. It is necessary to know the influence of substrate availability on the sensitivity of SR to temperature. In this study, soil samples were incubated for 28 days after a 28-day pre-incubation per iod. Pre-incubation and incubation were carried out at 20, 30, 40 and 50C. To test the substrate availability effect on the temperature sensitivity of SR, glucose was added to soil at the beginning of the incubation period. Results showed that the highest pre-incubation temperature reduced the temperature sensitivity of SR during the subsequent incubation period. Glucose addition reduced the effect of high pre-incubation temperature on SR response. Thus, it appears that the observed decrease in SR sensitivity to temperature after one month pre-incubation at high temperature was due to a reduce in substrate availability and to a decrease in microbial biomass. Since the soil used in this study is a Calcari-Leptic Cambisol, a second experiment was also performed to determine the amount of CO2 from carbonates and the amount of CO2 from SOC. This study was carried out by measurements of the isotopic signatures ( 13C) of SOC, carbonates and emitted CO2. After 28 days of inc ubation, 23+-9% of CO2 came from carbonates. This contribution was low compared to the high initial C-CaCO3 content in soil (4.3%), and it was independent to the incubation temperature. This study showed that reduce in the sensitivity of SR to high temperatures was probably due to a reduction in the substrate availability and to a decrease in microbial biomass.MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Testing the application of an agronomic concept to microbiology : a degree-day model to express cumulative co(2) emission from soils

Although much research has been carried out, there is still no consensus about the temperature dependence of CO2 emissions from soil organic carbon (SOC) decomposition. The temperature sensitivity of soil CO2 emissions varies with the time and the temperature levels used in laboratory experiments. Although combined models have been used to take account of the incubation time and temperature to describe the decomposition of SOC, the factors temperature and time in these models are still independent. These models were fitted to CO2 data obtained from parallel laboratory incubations. In this study, sequential incubations were carried out for 2 months at temperatures between 20 degrees C and 50 degrees C, assuming that (1) the sequence of temperature levels did not affect the soil CO2 emissions and (2) the CO2 emissions depended only on the temperature sum accumulated by the soil. A degree-day model, which is commonly used in agronomy, was applied to predict soil CO2 emission variations with time and temperature. The results showed that, for any sequence of temperature levels, the accumulation of degree-days explained the cumulative CO2 emissions during two months laboratory incubation over the 20-40 degrees C range, where 6% of SOC was emitted as CO2. However, at 50 degrees C, soil CO2 emissions were higher than predicted by the degree-day model. This underestimation of soil CO2 emissions lasted for one month after the soil had been at 50 degrees C. These results suggest that, for the range of incubation temperatures (20-40 degrees C) and time tested (56 days), or 2000 degree-days, (i) the degree-day model is valid only between 20 and 40 degrees C, (ii) the main determinant of soil temperature sensitivity is the amount of labile carbon rather than microbial adaptation of soil respiration to temperature

Cytotoxic and genotoxic effects of epoxiconazole on F98 glioma cells

International audienceEpoxiconazole (EPX) is a very effective fungicide of the triazole family. Given its wide spectrum of use, the increased application of this pesticide may represent a serious risk on human health. Previous studies have found that EPX is cytotoxic to cells, although the exact mechanism remains elusive. In particular, the effect on the nervous system is poorly elucidated. Here we evaluated the implication of oxidative stress in the neurotoxicity and studied its apoptotic mechanism of action. We demonstrated that the treatment by EPX reduces the viability of cells in a dose dependent manner with an IC50 of 50 μM. It also provokes the reduction of cell proliferation. EPX could trigger arrest in G1/S phase of cell cycle with low doses, however with IC50, it induced an accumulation of F98 cells in G2/M phase. Moreover, EPX induced cytoskeleton disruption as evidenced by immunocytochemical analysis. It provoked also DNA fragmentation in a concentration dependent manner. The EPX induced apoptosis, which was observed by morphological changes and by positive Annexin V FITC-PI staining concurrent with a depolarization of mitochondria. Furthermore, the cell mortality provoked by EPX was significantly reduced by pretreatment with Z-VAD-FMK, a caspase inhibitor. Moreover, N-acetylcysteine (NAC) strongly restores cell viability that has been inhibited by EPX. The results of these findings highlight the implication of ROS generation in the neurotoxicity induced by EPX, indicating that the production of ROS is the main cause of the induction of apoptosis probably via the mitochondrial pathway.</p

Temperature dependence of CO2 emissions rates and isotopic signature from a calcareous soil

In the context of climate change, studies have focused on the temperature dependence of soil CO2 emissions. Although calcareous soils cover over 30% of the earth's land surface, few studies have considered calcareous soils where soil inorganic carbon (SIC) makes the analysis of the C fluxes at the soil to air interface more complex. This study tested how temperature could affect the contributions of soil organic carbon (SOC) and SIC to the CO2 emitted from a calcareous soil. The soil pH, CO2 emissions and delta C-13 signatures of CO2 were measured after soil incubations at 4 temperatures (20 degrees C, 30 degrees C, 40 degrees C and 50 degrees C). The CO2 emissions and the C-delta 13 signature of the emitted CO2 increased with temperature. The proportion of SIC-derived CO2 in these emissions seemed to be stimulated by temperature. Three processes were discussed: (1) isotopic fractionations, (2) temperature impacts on SIC- and SOC-derived CO2, and (3) isotope exchanges between SIC-and SOC-derived CO2. The use of delta C-13 signature analysis to determine the contribution of SIC and SOC to the total CO2 emissions from soil is not straightforward. An increase in the SIC signature of emitted CO2 does not directly imply an increase in SIC as a source of CO2

The light microscopy and ultrastructural characteristics of Myxobolus naffari (Myxosporea, Myxobolidae) infecting the Nile carp Labeo niloticus (Cyprinidae) and its histological impact

During a survey of myxosporean parasites infecting freshwater fishes from the River Nile at Giza Governorates, Egypt between March and September 2016, nine out of 30 specimens of the Nile carp Labeo niloticus (Cyprinidae) were found to be naturally infected with Myxobolus naffari (Myxobolidae). Small macroscopic plasmodia appeared embedded in the host gill tissue accompanied with fusion of the gill epithelia, and atrophy was observed at the site of infection. The host reaction was manifested by the encapsulation of the plasmodia with a thick layer of connective tissue. The plasmodia appeared as white, elongated rods between gill filaments with an intensity ranging from three to eight cysts/fish. The average dimensions of plasmodia were 1.2–2.0 (1.8 ± 0.2) mm long × 0.4–0.7 (0.6 ± 0.2) mm wide. The spores were oval, reaching 9.56–11.2 (10.2 ± 0.2) μm long and 6.5–7.7 (7.0 ± 0.4) μm wide with two equal-sized polar capsules regularly arranged at the anterior pole of each spore. They were 4.51–5.5 (5.1 ± 0.4) μm in length and 1.5–2.0 (1.7 ± 0.2) μm in width. Histological, semi-thin sections were taken through parasite plasmodia and transmission electron microscopic examination of ultrathin sections was performed to describe the developmental stages of the recorded parasite within the host fish

Soil carbon as an indicator of Mediterranean soil quality

This book, coordinated by AllEnvi, is published on the occasion of the 22nd Conference of the Parties to the United Nations Framework Convention on Climate Change (COP22, Marrakech, 2016)Soil carbon as an indicator of Mediterranean soil qualit

Increased skin autofluorescence of advanced glycation end products (AGEs) in subjects with cardiovascular risk factors

Background As a clinical and non-invasive tool, the AGE Reader measures skin autofluorescence (SAF) to estimate the accumulation of advanced glycation end products (AGEs) in the skin. Accumulation of AGEs has been implicated in several inflammation-associated diseases, including diabetes and cardio-metabolic diseases. This study aimed to assess SAF in subjects with and without cardiovascular risk (CVR) factors and examine the association between SAF and various bio-clinical parameters. Methods In a cross-sectional study, we included 250 participants between 19 and 86 years of age divided into two groups: a healthy group (n = 88) and subjects with CVR factors (n = 162 in total, diabetes n = 48, hypertension n = 62, and both n = 52). We assessed skin AGE measures and biological and clinical data. Results SAF was significantly higher in subjects with CVR factors than in healthy participants (2.42 +/- 0.38 vs 1.90 +/- 0.29 respectively; p &lt; 0.001). SAF was associated with age, gender, BMI, duration of diabetes, HbA1c, triglyceride, and obesity. Multivariate analysis showed that age and duration of diabetes were the independent determinants of SAF. The ROC analysis indicated that a SAF &gt; 2.25 AU was the optimal cut-off point to predict the presence of diabetes and/or hypertension and dyslipidemia (p &lt; 0.001). Conclusion This Tunisian population-based study shows an increased SAF level in subjects with diabetes and/or hypertension and dyslipidemia compared to healthy subjects. The AGE Reader device is a rapid and non-invasive tool in clinical practice to evaluate and screen CVR factors in Tunisia with a North African phototype.</p