Browsing by Author "Matondo, RB"

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Atypical E2f functions are critical for pancreas polyploidization
(PLOS ONE, 2018-01-12) Matondo, RB; Moreno, E; Toussaint, MJM; Tooten, PCJ; van Essen, SC; van Liere, EA; Youssef, SA; Bongiovanni, L; de Bruin, A
The presence of polyploid cells in the endocrine and exocrine pancreas has been reported for four decades. In rodents, pancreatic polyploidization is initiated after weaning and the number of polyploid cells increases with age. Surprisingly the molecular regulators and biological functions of polyploidization in the pancreas are still unknown. We discovered that atypical E2f activity is essential for polyploidization in the pancreas, using an inducible Cre/LoxP approach in new-born mice to delete biquitously the atypical E2f transcription factors, E2f7 and E2f8. In contrast to its critical role in embryonic survival, conditional deletion of both of both atypical E2fs in newborn mice had no impact on postnatal survival and mice lived until old age. However, deficiency of E2f7 or E2f8 alone was sufficient to suppress polyploidization in the pancreas and associated with only a minor decrease in blood serum levels of glucose, insulin, amylase and lipase under 4 hours starvation condition compared to wildtype littermates. In mice with fewer pancreatic polyploid cells that were fed ad libitum, no major impact on hormones or enzymes levels was observed. In summary, we identified atypical E2fs to be essential for polyploidization in the pancreas and discovered that postnatal induced loss of both atypical E2fs in many organs is compatible with life until old age.
Deletion of the serotonin transporter in rats disturbs serotonin homeostasis without impairing liver regeneration
(American Physiological Society, 2009-04-01) Matondo, RB; Punt, C; Homberg, J; Toussaint, MJM; Kisjes, R; Korporaal, SJA; Akkerman, JWN; Cuppen, E; de Bruin, A
The serotonin transporter is implicated in the uptake of the vasoconstrictor serotonin from the circulation into the platelets, where 95% of all blood serotonin is stored and released in response to vascular injury. In vivo studies indicated that platelet-derived serotonin mediates liver regeneration after partial hepatectomy. We have recently generated serotonin transporter knockout rats and demonstrated that their platelets were almost completely depleted of serotonin. Here we show that these rats exhibit impaired hemostasis and contain about 1–6% of wild-type serotonin levels in the blood. Despite the marked reduction of serotonin levels in blood and platelets, efficient liver regeneration and collagen-induced platelet aggregation occur in rats lacking the serotonin transporter. These results provide evidence that liver regeneration is not dependent on the release of serotonin from platelets. Our findings indicate that very low levels of serotonin in blood are sufficient for liver regeneration.
Pathogenic Escherichia fergusonii and Staphylococcus gallinarum co-infection in a free-ranging domestic chicken
(ROAVS, 2012) Misinzo, G; Mathew, C; Matondo, RB; Jumapili, F; Ludosha, M; Masola, S; Munisi, W; Viaene, W; Doorsselaere, J.
Examination was carried out in an emaciated and depressed free-range domestic chicken from Mpwapwa where multiple cases of a similar condition were observed in 2010. A loosely attached unilateral nodule on the ventral aspect of the right eye and similar other nodules around the base of feathers mainly on dorsal aspects of wings, neck and head were observed. The cut nodules were yellowish with a firm and cheesy consistency surrounded by hyperaemic skin. In addition, multiple grey foci of variable size on liver and localized areas of hyperaemia on duodenal mucosa with mucoid exudates in the lumen were observed. On histopathology, the nodular lesions consisted of hyperplastic feather follicles with broad bands of keratinocytes and extension of follicular epithelium into surrounding dermis. In addition, luminal folliculitis in the skin and hepatic portal vasculitis were observed. Excised lesions from the eye, skin and liver were streaked on bacteriological agar with or without penicillin and streptomycin to isolate bacteria. Bacteria grew in agar without antibiotics but not in agar containing antibiotics. Bacterial colonies were subcultured and passaged four times to obtain pure cultures. Based on colony morphology, two types of bacteria were isolated from each of the organs. DNA was extracted from bacteria followed by amplification and sequencing of the 16S rDNA using 27F and 1492R primers. Sequence similarity search in GenBank showed that the bacteria were Escherichia fergusonii and Staphylococcus gallinarum. The present study shows that the chicken had E. fergusonii and S. gallinarum co-infection sensitive to penicillin and streptomycin