Search results for "Neurula"
showing 4 items of 4 documents
Regulatory factor for the transcription of the ribosomal genes in amphibian oocytes.
1970
AMPHIBIAN oocytes provide very convenient material for the study of the mechanisms that control ribosomal RNA synthesis because their pattern of ribosomal RNA synthesis does not change greatly during oogenesis. During the lampbrush stage of oogenesis (stage 4) more than 97 per cent of the RNA synthesized per unit time in the oocytes is ribosomal. This happens because the genes for ribosomal RNA are specifically amplified3–5 to such an extent that the oocyte nucleus (germinal vesicle) has an rDNA content approximately 1,500 times more than the haploid amount4. On the other hand, in mature oocytes (stage 6) no ribosomal RNA is synthesized1,2, although the extra copies of the ribosomal cistron…
The expression of an immune-related phenoloxidase gene is modulated inCiona intestinalisovary, test cells, embryos and larva
2015
Two distinct Ciona intestinalis phenoloxidases (CinPO1, 2) had previously been cloned and sequenced. The CinPO2 is involved in innate immunity and is expressed by inflammatory hemocytes that populate the tunic and pharynx vessels as a response to LPS inoculation. In situ hybridization and immunohistochemistry assays on histological section, showed that the expression of this gene and the produced protein are shared with oogenesis, embryogenesis and larval morphogenesis. Intriguingly, upregulation of gene transcription was found in the test cell layer that envelopes the ovary follicle, ovulated egg, and gastrula, as well as it was modulated in the zygotic nucleus of outer balstomers of 32-ce…
Indagini ultrastrutturali sugli effetti di un organometallo dello stagno [tributyltin (IV) chloride] sul processo di neurulazione delle Ascidie.
2006
Un’attenzione particolare è stata rivolta, negli anni più recenti, allo studio degli effetti di un organo metallo contenente stagno, il TBT (IV) chloride, sugli stadi iniziali dello sviluppo embrionale di animali marini. Gli effetti di questo potente inquinante sullo sviluppo e sulla sopravvivenza degli embrioni sono stati proposti come parametri utili per il controllo e il monitoraggio delle acque. Nel presente lavoro sono riportati gli effetti tossici del TBT (IV) chloride sulla neurulazione sull’ascidia Ciona intestinalis, stadio molto importante durante il quale avviene la determinazione del sistema nervoso e la formazione del tubo neurale. L’esposizione degli embrioni allo stadio di ne…
Effects of tri-n-butyltin(IV) chloride on neurulation of Ciona intestinalis (Tunicata, Ascidiacea): an ultrastructural study
2005
This paper reports the cytotoxic effects of tri-n-butyltin (IV) chloride, TBTCl, on the neurulation process of the ascidian Ciona intestinalis. Exposure of the embryos at early neurula stage in 10−5 and 10−7M TBT (IV) chloride solutions for 1–2 h provoked the irreversible arrest of their development. Morphological and ultrastructural observations suggested that most probably there are two principal causes determining the neurulation process block. The first is due to the TBT effects of inhibiting the polymerization and/or degradation of microfilaments and microtubules, proteins that constitute the cytoskeleton. The lack of orientation and extension of both microtubules and microfilaments of…