Rare splicing defects of FAS underly severe recessive autoimmune lymphoproliferative syndrome.

Autoimmune lymphoproliferative syndrome (ALPS) is a prototypic disorder of impaired apoptosis characterized by autoimmune features and lymphoproliferation. Heterozygous germline or somatic FAS mutations associated with preserved protein expression have been described. Very rare cases of homozygous germline FAS mutations causing severe autosomal recessive form of ALPS with a complete defect of Fas expression have been reported. We report two unrelated patients from highly inbred North African population showing a severe ALPS phenotype and an undetectable Fas surface expression. Two novel homozygous mutations have been identified underlying rare splicing defects mechanisms. The first mutation breaks a branch point sequence and the second alters a regulatory exonic splicing site. These splicing defects induce the skipping of exon 6 encoding the transmembrane domain of CD95. Our findings highlight the requirement of tight regulation of FAS exon 6 splicing for balanced alternative splicing and illustrate the importance of such studies in highly consanguineous populations.

Theoretical Investigation of the Electronic Structure and Spectra of Mg(2+)He and Mg(+)He.

The ground and many excited states of the Mg(+)He van der Waals molecular system have been explored using a one-electron pseudopotential approach. In this approach, effective potentials are used to consider the Mg(2+) core and the electron-He effects. Furthermore, a core-core interaction is included. This has reduced the number of active electrons of the Mg(+)He, to be considered in the calculation, to a single valence electron. This has permitted to use extended Gaussian basis sets for Mg and He. Therefore, the potentianl energy and dipole moments calculations are carried out at the Hartree-Fock level of theory, and the spin-orbit effect is included using a semiclassical approach. The core-core interaction for the Mg(2+)He ground state is included using accurate CCSD(T) calculations. The spectroscopic constants of the Mg(+)He electronic states are extracted and compared with the existing theoretical works, where very good agreement is observed. Moreover, the transition dipole function has been determined for a large and dense grid of internuclear distances including the spin-orbit effect.

ANALYSIS OF BIOTIC AND ABIOTIC FACTORS INFLUENCING THE OCCURRENCE OF WEST NILE VIRUS INFECTION IN TUNISIA.

Eco-climatic conditions are often associated with the occurrence of West Nile Disease (WND) cases. Among the complex set of biotic and abiotic factors influencing the emergence and spread of this vector-borne disease, two main variables have been considered to have a great influence on the probability of West Nile Virus (WNV) introduction and circulation in Tunisia: the presence of susceptible bird populations and the existence of geographical areas where the environmental and climatic conditions are more favourable to mosquito multiplications. The aim of this study was to identify and classify the climatic and environmental variables possibly associated with the occurrence of WNVhuman cases in Tunisia. The following environmental and climatic variables have been considered: wetlands and humid areas, Normalised Difference Vegetation Index (NDVI), temperatures and elevation. A preliminary analysis for the characterization of main variables associated with areas with a history of WNV human cases in Tunisia between 1997 and 2011 has been made. This preliminary analysis clearly indicates the closeness to marshes ecosystem, where migratory bird populations are located, as an important risk factor for WNV infection. On the contrary the temperature absolute seems to be not a significant factor in Tunisian epidemiological situation. In relation to NDVI values, more complex considerations should be made.

High frequency of autoimmunization among transfusion-dependent Tunisian thalassaemia patients.

BACKGROUND: Limited data are available on the frequency of RBC alloimmunization and autoimmunization in transfusion-dependent Tunisian ß thalassaemia patients. MATERIALS AND METHODS: We analyzed the clinical and transfusion records of 130 patients (57 females and 73 males; mean age 119 months; range 12-11 months) with ß thalassaemia major and who had regular blood transfusions for periods ranging from 12 to 311 months. RESULTS: Of the 130 patients, ten (7.7%) developed RBC alloantibodies. The most common alloantibodies were directed against antigens in the Rh systems. Erythrocyte-autoantibodies as determined by a positive direct antiglobulin Coombs test, developed in 52(40%) patients with and without underlying RBC alloantibodies, thereby causing autoimmune haemolytic anaemia in eleven patients (21%). CONCLUSIONS: Autoimmunization to erythrocyte antigens is a frequent complication in patients with ß thalassaemia major. Several factors might have contributed to the high autoimmunization rate observed in this study, including non phenotypic blood exposure and alloantibody formation prior to positive Coombs test.

[Identification of Enterocytozoon bieneusi by PCR in stools of Tunisian immunocompromised patients]. / Identification d'Enterocytozoon bieneusi par PCR dans les selles des patients immunodéprimés tunisiens.

INTRODUCTION: Intestinal microsporidiosis is recognised as an important cause of opportunistic parasitosis in immunocompromised patients, especially HIV-infected patients. Enterocytozoon bieneusi is the common causal agent. The diagnosis of intestinal microsporidiosis has usually based on microscopic detection of the spores of microsporidia species in stool samples, requires additional staining techniques as Modified Weber's trichrome stain. However, the detection of the spores can be difficult and species determination, which is important for defining the appropriate treatment, is impossible. Polymerase chain reaction (PCR)-based methods have been successfully used for detection of microsporidian infections. They are more sensitive and are able to identify microsporidia species. The purpose of this study is to identify E. bieneusi to adapt treatment and assess the true prevalence of the intestinal microsporidiosis due to this species in compromised patients in Tunisia. PATIENTS AND METHODS: One hundred and eighteen stools from immunocompromised patients, with a symptomatology in favour of the intestinal microsporidiosis, were analysed using light microscopy after staining with Modified Weber's trichrome stain and PCR. RESULTS: Only four were positive by Modified Weber's trichrome stain whereas eleven stools were positive by PCR, giving a prevalence of 20% in HIV-infected patients and 5,35% in human immunodeficiency virus-negative patients. CONCLUSION: This study confirms the usefulness of PCR in the diagnosis of the intestinal microsporidiosis due to E. bieneusi. Indeed, PCR has greater sensitivity than Modified Weber's trichrome stain and can identify the species of microsporidia in order to adapt the treatment.

Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia.

In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models' procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

Successful treatment of influenza A virus by oseltamivir in bone marrow transplant recipients.

INFVA is an important cause of pulmonary infections in patients receiving BMT, and is associated with considerable morbidity and mortality for a readily preventable and treatable infection. Few studies have addressed the impact of the new neuraminidase inhibitors in the prognosis of influenza after BMT. The aim of this study is to assess the impact of oseltamivir on the control of INFVA infection in BMT recipients. INFVA was screened in NPA and/or bronchoalveolar lavage using IF in all BMT recipients having respiratory symptoms. Three URTI and one associated upper and LRTI were diagnosed in three BMT recipients out of six patients admitted to the BMT unit, during eight-wk period (March and April 2008). All patients having INFVA respiratory infection were treated by oral oseltamivir 60 mg/day, begun more than 48 h after symptom onset. Respiratory symptoms disappeared within a mean of 60 h (48-96 h) of treatment. However, viral tests had remained positive for 8-39 days. Outside the initial associated URTI and LRTI, no further viral pneumonia occurred. No patient died of INFVA. Oseltamivir was well tolerated outside vomiting during the first three days of treatment in one patient. Oseltamivir appears to play an important role in the outcome of INFVA infection as well in URTI as in severe LRTI in patients receiving BMT.

[Immune recovery after allogeneic stem cell transplantation: study of 19 patients]. / La reconstitution immuno hematologique en post allogreffe de moelle osseuse: etude prospective de 19 cas.

The aim of this study was to access average delays for novogeneration of myeloid and lymphoid cells after allogeneic bone marrow transplantation (BMT) outcome and factors affecting this organization. A prospective analysis over 2 years (01/01/07 to 31/12/08) enrolling 19 children treated with allogeneic intrafamilial bone marrow transplantation. Indications for bone marrow transplantation were: aplastic anemia (3 cases), bemoglobinopathies (9 cases), myelodysplastic syndrome (1 case) and primary immunodeficiency (6 cases). Different conditioning regiments were used according to the indication. The study of immune reconstitution was based on the quantitative determination of immunoglobulin and lymphocyte subpopulation. These tests were routinely requested to 1 month, 2 months, 3 months, 6 months, 9 months and 12 months. The average time of engraftment was 18 days (12-24). A rate of CD4+T lymphocytes>200/mm3 was provided within an average of 2,5 months (1-7). The average time to obtain CD8+T lymphocytes>200/mm3 was 2 months (1-5). The humoral immune reconstitution was made within an average of 2 months (1-4). A report of CD4+/CD8+T lymphocytes>I was obtained within 10 months and a half (1-24). Univaried analysis showed a correlation between the bone marrow sex matched and the faster reorganization of CD8+T cells (p=0.042). A quantity of CD34+>6 10(6)/kg was significantly associated with the recapture of a formula lymphocyte CD4+/CD8+T>1 (p=0.03) Immune recovery post bone marrow transplantation in children begins with myeloid lineage then lymphoid B then lymphoid T The inversion of the report CD4+/CD8+T lymphocytes, seems to be influenced by the high contain of CD34+cells in the graft as well as the type of conditioning.

Spatial correlation between Phlebotomus papatasi Scopoli (Diptera: Psychodidae) and incidence of zoonotic cutaneous leishmaniasis in Tunisia.

The geographical distribution of Phlebotomus papatasi Scopoli, vector of Leishmania major Yakimoff and Schokhor (Kinetoplastida: Trypanosomatidae), the etiologic agent of zoonotic cutaneous leishmaniasis (ZCL), was assessed during September 2006 through a transect from the north to the south of Tunisia using CDC light traps. P. papatasi was found to be abundant in the arid and Saharan bioclimatic zones and rare in the humid, subhumid, and semiarid bioclimatic zones. Similarly, the highest incidence of ZCL was observed in the arid and Saharan bioclimatic zones and the lowest in the humid, subhumid, and semiarid bioclimatic zones. Our overall findings confirm the close spatial association between the abundance of P. papatasi and the incidence of ZCL.

Detection of SHV-1 beta-lactamase in Pseudomonas aeruginosa strains by genetic methods.

Twelve multidrug-resistant Pseudomonas aeruginosa (MDRPA) isolates were recovered over a period of two years in the National Bone Marrow Transplant Centre of Tunisia. MDRPA isolates were isolated from seven patients and from three environmental samples. Isoelectric focusing revealed pIs of 8.2, 5.5 and 7.6 in all MDRPA isolates. These strains produced the OXA-18 extended spectrum beta-lactamase and an SHV type beta-lactamase as shown by screening PCR analysis. DNA hybridization confirmed this inference, detecting bla(SHV) gene in these isolates. Pulsed-field gel electrophoresis (PFGE) defined one predominant genomic group; group A (seven isolates) and four different genotypes containing one to two isolates. Clonally related isolates were recovered from three patients and from two washbasins. Sequencing DNA of cluster representative strains identified the classical bla(SHV-1) gene. For these strains, the nucleotide sequence of the structural bla(SHV-1) gene was nearly identical to those previously described. Such enzyme has not been reported from P. aeruginosa. This is the first report of the SHV-1 penicillinase in epidemic P. aeruginosa strain.

[HLA-G: an immunoregulatory non classical class I HLA molecule]. / HLA-G: une molécule HLA de classe I non classique à pouvoir immunorégulateur.

HLA-G is a particular non classical HLA class I molecule. Despite its tissue-restricted expression and low polymorphism, this molecule plays an important role in innate and adaptative immunity. The tolerogenic propriety of HLA-G makes it an immunomodulatory molecule acting in the early phases of conception, protecting fetal tissues from the maternal immune system. Immunomodulatory functions of HLA-G and the associations of this molecule with some pathological states are reported in this review. So, little amounts of soluble HLA-G or particular allelic expression of this molecule are associated with some pregnancy complications. HLA-G expression on tumor cells by preventing antitumor responses via a trogocytosis mechanism and regulatory T cells induction is associated with invasiveness and clinical evolution of some tumor types. HLA-G is also involved in the protection of the transplanted tissues from rejection. Revealing of new more functional homomultimeric isoforms of this molecule offers new insight in a better understanding of clinical and biological role of HLA-G.

[The use of hydroxyurea in severe forms of sickle cell disease: study of 47 Tunisian paediatric cases]. / L'utilisation de l'hydroxyurée dans les formes sévères de la drépanocytose: étude de 47 cas pédiatriques tunisiens.

INTRODUCTION: The Sickle Cell Disease (SCD) is a serious illness considering its complications. For the children seriously affected, three therapeutic options are currently validated: transfusion therapy, hydroxyurea and bone-marrow transplantation. OBJECTIVES: To see the contribution of hydroxyurea therapy on severe forms of SCD in affected Tunisian children. MATERIAL AND METHODS: This investigative study lasted over 6 years and 9 months, (September 2000-May 2007), enrolling 47 patients including 27 homozygous SCD and 20 double heterozygote SCD-S/beta thalassemia. The median age was 12 years and a half. The average dosage were 20mg/kg/d (14-30 mg/kg/d). The average duration of treatment was 52 months (18-81 months). RESULTS: The main indication for hydroxyurea treatment was prevention of recurrence of an acute chest syndrome in seven cases; episodic vaso-occlusive crises exceeding three events per year in 38 cases and prevention of deterioration of cerebral vascular accident in two cases. We observed a fast and sustained improvement of the clinical expression of the disease with a significant decrease of the number of days of hospitalization per patient and per annum from 29.3 d (10-84 d) to 3.2 d/(p<0.01). Treatment was well tolerated. We observed a significant increase of haemoglobin fetus (HbF) rates from 3 to 30% (p<0.01), hemoglobin from 7.8 to 9.6g/dl (p<0.05), average blood cells volume from 79.1 to 100.3 fl (p<0.05) and a significant fall of the white blood cells rates from 14,914 to 8464 per millimetre cube (p<0.05), polynuclear neutrophils from 6799 to 3486 per millimetre cube (p<0.05) and platelets from 508,666 to 293,500 per millimetre cube (p<0.05). CONCLUSIONS: Hydroxyurea represents a privileged choice of treatment in the severe forms of SCD in children, for homozygous SCD-SS as well as for double heterozygote SCD-S/beta thalassemia. Used carefully, with frequent monitoring, it appeared as a safe treatment in short and medium term, but studies of long-term tolerance should be undertaken.

[Antiphospholipid syndrome: pathophysiology and clinicobiological aspects]. / Le syndrome des anti-phospholipides: physiopathologie et aspects clinico-biologiques.

Due to its heterogeneity and pathogenesis diversity, antiphospholipid syndrom remains a challenge for researchers more than a century after first antibody, the anticardiolipin antibody for syphilis diagnosis was discovered. After a review of the etiology and epitopic specificities of antiphospholipid antibodies, we propose a detailed overview of mechanisms and clinical aspects of antiphospholipid syndrome. We emphasize on the role of innate immunity and the involvement of endothelial cells Toll like receptors in the transduction signal of anti-beta2-glycoprotein I antibodies fixation, which induce a thrombogenic state. The thrombogenic role of the anti-beta2GPI antibodies direct against beta2GPI domain I in the clinical onset of this syndrome is also evoked. Diagnosis problems and clinicobiological manifestations in the light of the last international consensus statement of the classification criteria for antiphospholipid syndrome end this review.

Nosocomial outbreak of OXA-18-producing Pseudomonas aeruginosa in Tunisia.

Following systematic screening for ceftazidime-resistant (CAZ-R) Pseudomonas aeruginosa, 24 isolates producing extended-spectrum beta-lactamase (ESBL) were recovered during a 24-month period at the National Bone Marrow Transplant Centre of Tunisia. These isolates were from seven immunocompromised patients and from environmental swabs. ESBLs inhibited by clavulanic acid were detected by double-disk diffusion tests. Isoelectric focusing revealed that these isolates produced two to four beta-lactamases with pIs of 5.5, 6.1, 6.4, 7.6 or 8.2, and PCR detected the presence of bla(OXA-18), bla(SHV) and bla(TEM) genes in 24, 21 and two isolates, respectively. Pulsed-field gel electrophoresis defined two dominant genotypic groups: group A (16 isolates) and group B (four isolates). Sequencing of PCR products from representative isolates identified the bla(OXA-18) gene and revealed nucleotide sequences belonging to the bla(SHV-1) and bla(TEM-1) genes. Isolates producing OXA-18 belonged to genomic group A and were isolated from four immunocompromised patients in the haematology and graft units, and from two wash-basins in the graft unit. No immunocompromised patient harboured the clonal epidemic strain upon admission. This is the first report of the OXA-18-type ESBL in P. aeruginosa in Tunisia, and the first description of an outbreak caused by an OXA-18-producing strain of P. aeruginosa.

[Prevalence of Pneumocystis jiroveci pneumonia in Tunisian primary immunodeficient patients]. / Prévalence de la pneumopathie à Pneumocystis Jiroveci au cours des déficits immunitaires héréditaires observés en Tunisie.

UNLABELLED: Pneumocystis Jiroveci pneumonia (PJP) is a rare opportunistic infection in immunodeficient patients in Tunisia, as well as in other Africain countries including those with a high prevalence of AIDS. In the literature, PJP has been reported in primary immunodeficiency diseases (PID) namely SCID T-B- or T-B+ or X-linked hyper-IgM syndrome. OBJECTIVE: To evaluate the prevalence of PJP in the different PID observed in Tunisia. PATIENTS AND METHODS: This retrospective study concerned 290 cases of PID confirmed by immunological investigation including the study of specific and/or non-pecific humoral and cellular immunity. The identification of P. Jiroveci in patients suspected of pneumocystosis was achieved by parasitological investigation in bronchoalveolar lavages. RESULTS: A PID associated to a parasitologically confirmed pneumocystic infection was found in 9 out of 290 patients (3%) among whom the majority (7 patients) had an HLA class II combined immunodeficiency. The latter is an autosomic recessive disease which has been reported mainly in North African families. Indeed, this population is characterized by a high rate of consanguinity. Interestingly, no PJP has been observed neither in SCID T-B- or T-B+ nor in X-linked hyper-IgM syndrome. DISCUSSION AND CONCLUSION: PJP seems to be particularly frequent in HLA class II deficiency patients, since 7 out of 22 patients with this deficiency had a PJP (31%). Due to this defect, antigen presenting cells are unable to present the antigen to T lymphocytes demonstrating the critical role of CD4+ T lymphocytes responses in the immune response to this pathogen.

Identification of Suitable Areas for West Nile Virus Circulation in Tunisia.

West Nile virus (WNV) is a mosquito-transmitted Flavivirus belonging to the Japanese encephalitis antigenic complex of the Flaviviridae family. It is transmitted primarily by the bite of infected mosquitoes, particularly Culex spp. and Aedes/Ochlerotatus spp., which acquire the virus by feeding on viraemic birds. Humans, horses and other mammals are regarded as incidental or dead-end hosts. In the last decades, an increasing number of cases of WNV infection in horses and humans have been notified in the Mediterranean basin. In Tunisia, human cases of WNV-related meningoencephalitis were detected in 1997, 2003, 2007, 2010, 2011 and 2012. Based on the analysis of climatic and environmental conditions found in the locations where human cases have been reported in 2012, the aim of this study was to identify similar areas in Tunisia potentially at risk of disease occurrence. Data related to 85 neuroinvasive West Nile fever (WNF) human cases were georeferenced and a set of environmental and climatic variables (wetlands and humid areas, normalized difference vegetation index (NDVI), temperatures and elevation, migratory bird settlements) were used in the analysis. Areas, ecologically similar to those where human cases were detected, were identified using the Mahalanobis distance statistic. A leave-one-out cross-validation was performed to validate the sensitivity of the model, and 78 of 85 points were correctly classified.

Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia / Padrões de distribuição espaço-temporal de comunidades Chironomidae nos wadis do norte da Tunísia

In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models' procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

No norte da Tunísia, riachos sazonais chamados wadi são caracterizados por condições hidrológicas e térmicas extremas. Esses sistemas de água doce têm características muito particulares como resultado de sua forte irregularidade de fluxo devido ao regime de escoamento de precipitação limitado, levando a fortes flutuações hidrológicas sazonais. O estudo atual enfocou a distribuição espaço-temporal dos quironomídeos em 28 locais de amostragem espalhados pelo norte da Tunísia. Ao aplicar PERMANOVA, os resultados indicaram uma variação espaço-temporal significativa ao longo de vários gradientes ambientais. Os principais fatores abióticos responsáveis pelas diferenças observadas na distribuição espacial dos quironomídeos no wadi foram a condutividade e a temperatura, seguidos de perto por altitude, pH, salinidade, declive do talvegue e oxigênio dissolvido, identificados como tais empregando o procedimento de modelos lineares baseados na distância. A ordenação da análise de redundância baseada em distância mostrou dois grupos principais: o primeiro agrupou os sítios Bizerte, que foram caracterizados por alta condutividade da água, concentração de sódio e salinidade. O segundo grupo principal compreendia locais da zona de Tell e era caracterizado por baixas temperaturas, pH neutro, baixa condutividade e conteúdo de nutrientes. A subfamília Tanypodiinae (por exemplo, Prochladius sp., Prochladius choerus [Meigen, 1804] e Macropelopia sp.) era o grupo dominante na zona de Tell, enquanto espécies como Diamesa starmachi (Kownacki et Kownacha, 1970) e Potthastia gaedii (Meigen, 1838) foram encontradas apenas em Tell Wadis. Em contraste, espécies de quironomídeos, como Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804), eram específicas para Tell Mountain. A região de Cap Bon wadis [...].

Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia

Abstract In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

Resumo No norte da Tunísia, riachos sazonais chamados wadi são caracterizados por condições hidrológicas e térmicas extremas. Esses sistemas de água doce têm características muito particulares como resultado de sua forte irregularidade de fluxo devido ao regime de escoamento de precipitação limitado, levando a fortes flutuações hidrológicas sazonais. O estudo atual enfocou a distribuição espaço-temporal dos quironomídeos em 28 locais de amostragem espalhados pelo norte da Tunísia. Ao aplicar PERMANOVA, os resultados indicaram uma variação espaço-temporal significativa ao longo de vários gradientes ambientais. Os principais fatores abióticos responsáveis pelas diferenças observadas na distribuição espacial dos quironomídeos no wadi foram a condutividade e a temperatura, seguidos de perto por altitude, pH, salinidade, declive do talvegue e oxigênio dissolvido, identificados como tais empregando o procedimento de modelos lineares baseados na distância. A ordenação da análise de redundância baseada em distância mostrou dois grupos principais: o primeiro agrupou os sítios Bizerte, que foram caracterizados por alta condutividade da água, concentração de sódio e salinidade. O segundo grupo principal compreendia locais da zona de Tell e era caracterizado por baixas temperaturas, pH neutro, baixa condutividade e conteúdo de nutrientes. A subfamília Tanypodiinae (por exemplo, Prochladius sp., Prochladius choerus [Meigen, 1804] e Macropelopia sp.) era o grupo dominante na zona de Tell, enquanto espécies como Diamesa starmachi (Kownacki et Kownacha, 1970) e Potthastia gaedii (Meigen, 1838) foram encontradas apenas em Tell Wadis. Em contraste, espécies de quironomídeos, como Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804), eram específicas para Tell Mountain. A região de Cap Bon wadis foi dominada pelo gênero Cladotanytarsus sp. Os resultados desta pesquisa gostaram da composição taxonômica das assembleias de quironomídeos com a variação dos gradientes hidromorfológicos e físico-químicos nos wadis do norte da Tunísia.

Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia / Padrões de distribuição espaço-temporal de comunidades Chironomidae nos wadis do norte da Tunísia

In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models' procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

No norte da Tunísia, riachos sazonais chamados wadi são caracterizados por condições hidrológicas e térmicas extremas. Esses sistemas de água doce têm características muito particulares como resultado de sua forte irregularidade de fluxo devido ao regime de escoamento de precipitação limitado, levando a fortes flutuações hidrológicas sazonais. O estudo atual enfocou a distribuição espaço-temporal dos quironomídeos em 28 locais de amostragem espalhados pelo norte da Tunísia. Ao aplicar PERMANOVA, os resultados indicaram uma variação espaço-temporal significativa ao longo de vários gradientes ambientais. Os principais fatores abióticos responsáveis pelas diferenças observadas na distribuição espacial dos quironomídeos no wadi foram a condutividade e a temperatura, seguidos de perto por altitude, pH, salinidade, declive do talvegue e oxigênio dissolvido, identificados como tais empregando o procedimento de modelos lineares baseados na distância. A ordenação da análise de redundância baseada em distância mostrou dois grupos principais: o primeiro agrupou os sítios Bizerte, que foram caracterizados por alta condutividade da água, concentração de sódio e salinidade. O segundo grupo principal compreendia locais da zona de Tell e era caracterizado por baixas temperaturas, pH neutro, baixa condutividade e conteúdo de nutrientes. A subfamília Tanypodiinae (por exemplo, Prochladius sp., Prochladius choerus [Meigen, 1804] e Macropelopia sp.) era o grupo dominante na zona de Tell, enquanto espécies como Diamesa starmachi (Kownacki et Kownacha, 1970) e Potthastia gaedii (Meigen, 1838) foram encontradas apenas em Tell Wadis. Em contraste, espécies de quironomídeos, como Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804), eram específicas para Tell Mountain. A região de Cap Bon wadis foi dominada pelo gênero Cladotanytarsus sp. Os resultados desta pesquisa gostaram da composição taxonômica das assembleias de quironomídeos com a variação dos gradientes hidromorfológicos e físico-químicos nos wadis do norte da Tunísia.

[HFE gene mutations in Tunisian major beta-Thalassemia and iron overload]. / Mutations du gène HFE chez des beta-thalassémiques majeurs tunisiens et surcharge en fer.

OBJECTIVES: In this study we have determined the allele frequency of HFE mutations H63D and C282Y in a group of Tunisian beta-thalassemia major patients. These two mutations are implicated in hereditary hemochromatosis among Caucasians. In this study we wanted to correlate these mutations with the iron status in major beta-thalassemia patients. DESIGN AND METHODS: Fifty Tunisian major beta-thalassemia were screening for the C282Y and H63D by digestion of polymerase chain reaction products (RFLP). Serum ferritin level was measured by immunoenzymatic microparticular essay. RESULTS: The allele frequency of H63D mutation was 17%. C282Y mutation was not present in our studied patients. No statistically significant difference of serum ferritin level was found between major beta-thalassemia with and without HFE mutations. CONCLUSION: Our results suggest that H63D mutation is so frequent in Tunisian major beta-thalassemia patients than in the general population and that the coinheritance of H63D mutation does not influence the severity of iron overload in these patients.