Effects of Cadmium and High Temperature on Some Parameters of Calcium Metabolism in the Killifish (Aphanius fasciatus)

This study aims to investigate the influence of high temperature on cadmium (Cd) toxicity in Aphanius fasciatus (Pisces: Cyprinodontidae). For this reason, Cd, mineral, and organic content in the vertebral column as well as the histological structure of gills and bone were compared in fishes exposed for 30 days to Cd (2 mg/L CdCl₂) and/or high temperature (26 °C). Cd exposure caused a negative correlation between Cd and Ca concentrations (r?=?0.98, p?<?0.05), as well as a significant decrease in inorganic components (p?<?0.05) and ash weight/dry weight ratio (p?<?0.05) in the vertebral column. These changes were accompanied by an increased frequency of histological alterations in gills and bone. Concomitant treatment with Cd and high temperature increases Cd accumulation and Ca depletion in the skeletal tissue and increases the frequency and the severity of histological alterations. These results confirm that temperature increases Cd toxicity and needs to be taken into account for the accurate prediction and assessment of Cd-induced spinal deformities in fish.     

Sequence Polymorphism of Cytochrome b Gene in Theileria annulata Tunisian Isolates and Its Association with Buparvaquone Treatment Failure

Background

Buparvaquone (BW 720C) is the major hydroxynaphtoquinone active against tropical theileriosis (Theileria annulata infection). Previous studies showed that buparvaquone, similarly to others hydroxynaphtoquinone, probably acts by binding to cytochrome b (cyt b) inhibiting the electron transport chain in the parasite. Several observations suggested that T. annulata is becoming resistant to buparvaquone in many endemic regions (Tunisia, Turkey and Iran), which may hinder the development of bovine livestock in these areas.

Methodology/Principal Findings

In the present study we sought to determine whether point mutations in T. annulata cytochrome b gene could be associated to buparvaquone resistance. A total of 28 clones were studied in this work, 19 of which were obtained from 3 resistant isolates (ST2/12, ST2/13 and ST2/19) collected at different time after treatment, from a field treatment failure and nine clones isolated from 4 sensitive stocks of T. annulata (Beja, Battan, Jed4 and Sousse). The cytochrome b gene was amplified and sequenced. We identified five point mutations at the protein sequences (114, 129, 253, 262 and 347) specific for the clones isolated from resistant stocks. Two of them affecting 68% (13/19) of resistant clones, are present in the drug-binding site Q₀₂ region at the position 253 in three resistant clones and at the position 262 in 11 out of 19 resistant clones. These two mutations substitute a neutral and hydrophobic amino acids by polar and hydrophilic ones which could interfere with the drug binding capabilities. When we compared our sequences to the Iranian ones, the phylogenetic tree analyses show the presence of a geographical sub-structuring in the population of T. annulata.

Conclusions/Significance

Taken together, our results suggest that the cytochrome b gene may be used as a tool to discriminate between different T. annulata genotypes and also as a genetic marker to characterize resistant isolates of T. annulata.     

Association analysis of interleukin gene polymorphisms in autoimmune thyroid diseases in the Tunisian population

Autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and autoimmune hypothyroidism (AH), are inherited as complex traits. Among the genes contributing to AITDs susceptibility are genes of the IL-1 family. IL-1 regulates T and B lymphocyte maturation, including the induction of several cytokines and cytokine receptors. Therefore, disturbances of this balance may not only play a role in inflammation but also in the pathogenesis of autoimmunity. In order to investigate genetic association of IL-1 gene polymorphisms with AITDs, we performed both a familial study in a large Tunisian pedigree with high prevalence of AITDs (64 patients and 176 controls), and a case-control study (131 GD unrelated patients and 225 healthy controls). PCR and PCR-RFLP methods were used to analyse respectively a VNTR in the IL-1RN gene and three SNPs in both IL-1B genes (-511 C/T and +3954 C/T) and IL-1A (-889 C/T). The family-based association study showed an association of the IL-1B+3954 C/T polymorphism (p=0.02) and two haplotypes IL-1RN*3/C/T/T and IL-1RN*1/C/T/T (p=0.009 and p=0.047 respectively) with AITDs. The case-control study is the first study revealing a significant association of the IL-1A-889 C/T polymorphism (chi2=10.23; p=0.0014) with susceptibility to GD. Our data suggest that the IL-1 gene cluster may harbour susceptibility genes for AITDs and GD pathogenesis in the Tunisian population.     

The CRISPRdb database and tools to display CRISPRs and to generate dictionaries of spacers and repeats

Background  

In Archeae and Bacteria, the repeated elements called CRISPRs for "clustered regularly interspaced short palindromic repeats" are believed to participate in the defence against viruses. Short sequences called spacers are stored in-between repeated elements. In the current model, motifs comprising spacers and repeats may target an invading DNA and lead to its degradation through a proposed mechanism similar to RNA interference. Analysis of intra-species polymorphism shows that new motifs (one spacer and one repeated element) are added in a polarised fashion. Although their principal characteristics have been described, a lot remains to be discovered on the way CRISPRs are created and evolve. As new genome sequences become available it appears necessary to develop automated scanning tools to make available CRISPRs related information and to facilitate additional investigations.     

On-line resources for bacterial micro-evolution studies using MLVA or CRISPR typing

The control of bacterial pathogens requires the development of tools allowing the precise identification of strains at the subspecies level. It is now widely accepted that these tools will need to be DNA-based assays (in contrast to identification at the species level, where biochemical based assays are still widely used, even though very powerful 16S DNA sequence databases exist). Typing assays need to be cheap and amenable to the designing of international databases. The success of such subspecies typing tools will eventually be measured by the size of the associated reference databases accessible over the internet. Three methods have shown some potential in this direction, the so-called spoligotyping assay (Mycobacterium tuberculosis, 40,000 entries database), Multiple Loci Sequence Typing (MLST; up to a few thousands entries for the more than 20 bacterial species), and more recently Multiple Loci VNTR Analysis (MLVA; up to a few hundred entries, assays available for more than 20 pathogens). In the present report we will review the current status of the tools and resources we have developed along the past seven years to help in the setting-up or the use of MLVA assays or lately for analysing Clustered Regularly Interspaced Short Palindromic Repeats called CRISPRs which are the basis for spoligotyping assays.     

Role of carbohydrate moiety of bleomycin-A2 in caspase-3 activation and internucleosomal chromatin fragmentation in apoptosis of laryngeal carcinoma cells

Bleomycin (BLM), an antitumor antibiotic, is currently used during anticancer therapy. The therapeutic efficiency of BLM for the treatment of malignant tumors is related to its ability to cleave DNA. However, little is known about the biological activity of the glycannic moiety in BLM-induced cytotoxicity. In this study, cell death induced by BLM-A2 and deglycosylated BLM-A2 was studied in a laryngeal carcinoma cell line (HEp-2 cells). Our results indicate that HEp-2 cells showed morphological and biochemical changes associated with apoptosis in the presence of low concentrations of BLM-A2. In contrast, the same changes, except activation of caspase-3 and internucleosomal digestion of genomic DNA, were observed when cells were exposed to high concentrations of deglycosylated BLM-A2. These observations indicate that the glycannic moiety from the bleomycin molecule has important biological effects on the cytotoxicity of the drug.     

Involvement of Cd Bioaccumulation in Spinal Deformities Occurrence in Natural Populations of Mediterranean Killifish

The aim of this study was to investigate the possible influence of environmental exposure to cadmium (Cd) on the spinal deformities occurrence in the Mediterranean killifish, Aphanius fasciatus (Pisces: Cyprinodontidae). For this purpose, some indicators of skeletal bone mineralization, Cd, and calcium (Ca) concentrations in spinal column as well as bioaccumulation of Cd from the water and the sediment have been compared in normal and deformed fish collected from polluted (S1) and nonpolluted (S2) areas in the Gulf of Gabès in Tunisia. When compared to the normal fish, the deformed fish showed signs of spinal column demineralization such as significant decrease in the ash weight/dry weight ratio, percentage of nonorganic components content, and Ca concentration. Cd concentrations in spinal column and liver were significantly higher in deformed fish than in normal fish. A highly significant negative correlation (r = −0.915, p < 0.01) between Cd and Ca concentrations was noted in spinal column of deformed fish. Bioaccumulation factors of Cd in the liver from the water and the sediment in deformed fish were also significantly higher (p < 0.0001) than in normal fish from S1 and S2. These findings suggest that the ability to accumulate large amount of Cd may represent a potential risk to induce spinal deformities in natural populations of Mediterranean killifish.     

Cardiomyopathy induced by incessant ventricular tachycardia originating in the vicinity of the His bundle

A 04-year-old boy was referred to our institution with severe, progressive heart failure of 4-months duration associated with a persistent wide QRS tachycardia with left bundle branch block and severe left ventricular dysfunction. Because of incessant wide QRS tachycardia refractory to antiarrhythmic drugs, he was referred for electrophysiological study. The ECG was suggestive of VT arising from the right ventricle near the His area. Electrophysiological study revealed that origin of tachycardia was septum of the right ventricle, near His bundle, however the procedure was not successful and an inadvertent complete atrioventricular conduction block occurred. The same ventricular tachycardia recurred. A second procedure was performed with a retrograd aortic approach to map the left side of the interventricular septum. The earliest endocardial site for ablation was localized in the anterobasal region of left ventricle near His bundle. In this location, one radiofrequency pulse interrupted VT and rendered it not inducible. The echocardiographic evaluation showed partial reversal of left ventricular function in the first 3 months. The diagnosis was idiopathic parahisian left ventricular tachycardia leading to a tachycardia mediated cardiomyopathy, an extremely rare clinical picture in children.     

Vasopressin and nitric oxide synthesis after three days of water or food deprivation

Nitric oxide has been suggested to be involved in the regulation of fluid and nutrient homeostasis. In the present investigation, vasopressin and nitric oxide metabolite (nitrite and nitrate) levels were determined in plasma of male Wistar rats submitted to water or food deprivation for three days. Hematocrit and plasma sodium showed marked increase in dehydrated and starved rats. Potassium levels and plasma volume decreased in both treated groups. Plasma osmolality and vasopressin levels were significantly elevated in water deprived (362.8 +/- 7.1 mOsm/kg H2O, 17.3 +/- 2.7 pg/ml, respectively, p < 0.001) rats, but not in food deprived (339.9 +/- 5.0, 1.34 +/- 0.28) rats, compared to the controls (326.1 +/- 4.1, 1.47 +/- 0.32). The alterations observed in plasma vasopressin levels were related to plasma osmolality rather than plasma volume. Plasma levels of nitrite and nitrate were markedly increased in both water and food deprived rats (respectively, 2.19 +/- 0.29 mg/l and 2.22 +/- 0.17 mg/l versus 1.33 +/- 0.19 mg/l, both p < 0.01). There was a significant negative correlation between plasma nitrite and nitrate concentration and plasma volume. These results suggest that both dehydration and starvation increase plasma nitric oxide, probably by activation of nitric oxide synthases. The release of nitric oxide may participate in the regulation of the alteration in blood flow, fluid and nutrient metabolism caused by water deprivation or starvation.