No abstract

The MAF family transcription factors are homologs of v-Maf, the oncogenic component of the avian retrovirus AS42. They are subdivided into 2 groups, small and large MAF proteins, according to their structure, function, and molecular size. MAFK is a member of the small MAF family and acts as a dominant negative form of large MAFs. In previous research we generated transgenic mice that overexpress MAFK in order to suppress the function of large MAF proteins in pancreatic β-cells. These mice developed hyperglycemia in adulthood due to impairment of glucose-stimulated insulin secretion. The aim of the current study is to examine the effects of β-cell-specific Mafk overexpression in endocrine cell development. The developing islets of Mafk-transgenic embryos appeared to be disorganized with an inversion of total numbers of insulin+ and glucagon+ cells due to reduced β-cell proliferation. Gene expression analysis by quantitative RT-PCR revealed decreased levels of β-cell-related genes whose expressions are known to be controlled by large MAF proteins. Additionally, these changes were accompanied with a significant increase in key β-cell transcription factors likely due to compensatory mechanisms that might have been activated in response to the β-cell loss. Finally, microarray comparison of gene expression profiles between wild-type and transgenic pancreata revealed alteration of some uncharacterized genes including Pcbd1, Fam132a, Cryba2, and Npy, which might play important roles during pancreatic endocrine development. Taken together, these results suggest that Mafk overexpression impairs endocrine development through a regulation of numerous β-cell-related genes. The microarray analysis provided a unique data set of differentially expressed genes that might contribute to a better understanding of the molecular basis that governs the development and function of endocrine pancreas.

Objective: The teeth play important roles in food mastication, prehension and defense against predators. Although several studies demonstrated the development of teeth in different mammalian species, no data are, to our knowledge, available in Egyptian buffalos. Therefore, the present investigation was conducted to study the development of incisor teeth in buffaloe. Design: Descriptive study. Animals: seventeen buffalo embryos and fetuses of both sexes were used. Their crown vertebral rump lengths (CVRL) ranged from 2 to 46 cm (equivalent to 38 - 177 days old). Procedure: Embryos and fetuses were fixed in 10% neutral buffered formalin and decalcified by 14% EDTA solution for several weeks. The samples were dehydrated, cleared and embedded in paraffin wax using standard techniques. Sections were cut on Leitz microtome and mounted on uncoated slides. For general histological structure, a selection of slides was routinely stained with haematoxylin–eosin and examined by the light microscope. Result: The present study reported for the first time that the prenatal development of incisors in buffalo passes through three sequential stages: the bud, cap and bell stages. Although each stage was easily differentiated based on its form and its distinct developmental features, the three stages were overlapped with each other’s. Generally, the bud stage was observed in 11 cm CVRL buffalo fetuses, meanwhile the cap and bell stages were detected in 23 cm and 30 cm CVRL fetuses respectively. Conclusion and clinical relevance: These results can be used as inductive index for determination of the ages of buffalo embryos and fetuses.

The teeth play importa nt roles in food mastication, prehens ion and defe ns e against predato rs . Althoug h severa l studie s demons tra te d the developm e nt of teeth in differe nt mammalia n species , no data are, to our knowle d g e , available in Egyptia n buffalos . Therefore, the present investig a tion was conducte d to study the develop me n t of incisor teeth in buffaloe . Design: Descriptive study. Animals : sevente e n buffalo embryos and fetuses of both sexes were used. Their crown verte bra l rump lengths (CVRL) ranged from 2 to 46 cm (equiva le nt to 38 -177 days old). Proce dure: Embryos and fetuses were fixed in 10% neutra l buffere d formalin and decalcifie d by 14% EDTA solution for several weeks . The samples were dehydra te d , cleare d and embedde d in paraffin wax using standa rd technique s . Sections were cut on Leitz microtom e and mounte d on uncoa te d slides. For general histolog ica l structure , a selection of slides was routine ly stained with haematoxylin -e osin and examine d by the light micros cope . Result: The present study reporte d for the first time that the prenata l developme nt of incisors in buffalo passes throug h three sequentia l stages: the bud, cap and bell stag e s . Althoug h each stage was easily differe ntia te d based on its form and its distinc t developm e ntal features , the three stages were overla ppe d with each other's . Genera ll y , the bud stage was observe d in 11 cm CVRL buffalo fetuses, meanwhile the cap and be ll stages were detecte d in 23 cm and 30 cm CVRL fetuses respective ly. Conclus ion and clinical relevance:These results can be used as inductive index for determina tion of the ages of buffalo embryos and fetuses.