Efficiency and midgut histopathological effect of the newly isolated Bacillus thuringiensis KS δ-endotoxins on the emergent pest Tuta absoluta.

Tuta absoluta (Povolny, 1994) is a devastating moth to the Solanaceae plants. It is a challenging pest to control, especially on tomatoes. In this work, we studied the entomopathogenic activity of the Cry-forming δ-endotoxins produced by Bacillus thuringiensis strain KS and B. thuringiensis kurstaki reference strain HD1 against T. absoluta. These strains carried the cry2, cry1Ab, cry1Aa / cry1Ac, and cry1I genes, and KS also carried a cry1C gene. The δ-endotoxins of KS were approximately twofold more toxic against the third instar larvae than those of HD1, as they showed lower 50% and 90% lethal concentrations (0.80 and 2.70 µg/cm² (δ-endotoxins/tomato leaf)) compared with those of HD1 (1.70 and 4.50 µg/cm²) (p < 0.05). Additionally, the larvae protease extract showed at least six caseinolytic activities, which activated the KS and HD1 δ- endotoxins, yielding the active toxins of about 65 kDa and the protease-resistant core of about 58 kDa. Moreover, the histopathological effects of KS and HD1 δ-endotoxins on the larvae midgut consisted of an apical columnar cell vacuolization, microvillus damage, and epithelial cell disruption. These results showed that the KS strain could be a candidate for T. absoluta control.

[Histological features of celiac disease in south Tunisia: a study of 114 pediatric cases]. / Aspects histologiques de la maladie coeliaque dans le sud Tunisien: etude de 114 cas pédiatriques.

AIM: To report the histological features of celiac disease in a paediatric population originating from south Tunisia. METHODS: A retrospective study of a series of duodenal biopsies from 114 children with celiac disease diagnosed over a period of 6 years (from January 1999 to December 2004). The diagnosis was confirmed by histological results, serological studies and clinical response to gluten free diet. RESULTS: The average age of patients was of 6.2 years (range 6 months-15 years). Sex ratio was 0.71. Symptoms were dominated by chronic diarrhea (48%), weight loss (50%) and anemia (20.1%). Histological findings showed an intraepithelial lymphocytosis (Marsh type 1) in 12.2% of cases, type 2 was present in 1.7% of cases and type 3 (villous atrophy) in 86% of cases. A treatment with a gluten-free diet was indicated for all patients, only the cases who haven't presented a clinical amelioration (11 cases) have beneficed a control biopsie; a villous atrophy was persistent in 80% of this patients. CONCLUSION: Histological features in duodenal biopsies for the diagnosis and the follow-up of patients with coeliac disease. This allows an appropriate treatment and prevents further complications.