Despite playing a crucial role in germline-soma differentiation, the evolutionary significance of developmentally regulated genome rearrangements (DRGRs) has received scant attention. An example of DRGR is DNA splicing, a process that removes segments of DNA interrupting genic and/or intergenic sequences. Perhaps, best known for shaping immune-system genes in vertebrates, DNA splicing plays a c...

Ciliated protozoa contain two types of nuclei, germ line micronuclei (Mic) and transcriptionally active macronuclei (Mac). During sexual reproduction, the parental Mac degenerates and a new Mac develops from a mitotic product of the zygotic Mic. Macronuclear development involves extensive endoreplication of the genome. The present study shows that endoreplication of macronuclear DNA in Tetrahym...

Early in evolution, Ca(2+) emerged as the most important second messenger for regulating widely different cellular functions. In eukaryotic cells Ca(2+) signals originate from several sources, i.e. influx from the outside medium, release from internal stores or from both. In mammalian cells, Ca(2+)-release channels represented by inositol 1,4,5-trisphosphate receptors and ryanodine receptors (I...

Extensive, programmed chromosome breakage occurs during formation of the somatic macronucleus of ciliated protozoa. The cis-acting signal directing breakage has been most rigorously defined in Tetrahymena thermophila, where it consists of a 15-bp DNA sequence known as Cbs, for chromosome breakage sequence. We have identified sequences identical or nearly identical to the T. thermophila Cbs at s...

Germ line micronuclear genes in ciliated protozoa contain two types of interrupting sequences. Some genes contain introns, but internal eliminated segments (IESs) are much more prevalent. IESs are AT-rich DNA segments that separate macronucleus-destined segments (MDSs) in micronuclear genes. All IESs are excised and destroyed when a micronucleus develops into a macronucleus after each cell mati...

BACKGROUND Equine motor neuron disease (EMND) is a neuromuscular disorder that affects adult horses. Although EMND has been linked to vitamin E deficiency, its etiopathogenesis is poorly understood. OBJECTIVES To describe clinical features, laboratory results, and postmortem findings in a series of young horses with motor neuron disease (MND). ANIMALS A herd of 15 young Andalusian horses wi...

Ciliated protozoa undergo extensive DNA rearrangements, including DNA elimination, chromosome breakage and DNA unscrambling, when the germline micronucleus produces the new macronucleus during sexual reproduction. It has long been known that many of these events are epigenetically controlled by DNA sequences of the parental macronuclear genome. Recent studies in some model ciliates have reveale...

INTRODUCTION The ciliated cyst is a rare anomaly that develops from the anterior primitive intestine. Its localization is essentially supra diaphragmatic. It's localization in the gallbladder is very uncommon. CASE REPORT We report the first case in Tunisia of a ciliated cyst of the gallbladder in a 34 years old woman who was operated for a gallbladder stone and in whom the discovery of a cys...

The avian oviduct is subdivided into five regions according to its function in egg formation and histological features. They are the infundibulum, albumen secreting region (magnum), isthmus, shell gland (uterus), and vagina. The epithelium of these regions consists of ciliated and nonciliated cells. In addition to secretion granules, specific to each region, in the non-ciliated cells, considera...

BACKGROUND Interleukin (IL)-13 induces goblet cell metaplasia and plays an important role in mucus hypersecretion in asthma. We previously reported that IL-13 induced goblet cell differentiation along with less ciliated cell differentiation in guinea pig tracheal epithelial cells in vitro. In this study, we asked whether elimination of IL-13 could reverse the established goblet cell metaplasia ...