Search results for "Ovum"
showing 10 items of 96 documents
First morphogenetic analysis of parasite eggs from Schistosomiasis haematobium infected sub-Saharan migrants in Spain and proposal for a new standard…
2021
International audience; Schistosomiasis is a Neglected Tropical Disease caused by trematode species of the genus Schistosoma. Both, autochthonous and imported cases of urogenital schistosomiasis have been described in Europe. The present study focuses on eggs, considered pure S. haematobium by genetic characterisation (intergenic ITS region of the rDNA and cox1 mtDNA). A phenotypic characterisation of S. haematobium eggs was made by morphometric comparison with experimental populations of S. bovis and S. mansoni, to help in the diagnosis of S. haematobium populations infecting sub-Saharan migrants in Spain. Analyses were made by Computer Image Analysis System (CIAS) applied on the basis of …
Studies on sea urchin oocytes. II. Synthesis of RNA during oogenesis.
1972
Abstract Isolated oocytes of the sea urchin Paracentrotus lividus actively incorporate 3H-uridine into RNA. Labeled RNA was analysed by sucrose gradient and acrylamide gel electrophoresis following cell fractionation. Much of the radioactivity is incorporated at the nucleolar level in the form of rRNA precursors. The kinetics of maturation of these latter suggests that this occurs at a slower rate than during embryogenesis. Other non-nucleolar RNA classes are also actively labelled and retained in the nucleus for many hours. These results are confirmed by an autoradiographic investigation.
Constitutive hsp70 is essential to mitosis during early cleavage of Paracentrotus lividus embryos: The blockage of constitutive hsp70 impairs mitosis
1999
Localization of constitutive hsp70 in eggs and early embryos of sea urchin Paracentrotus lividus is shown by means of in situ immunostaining. An accumulation of this protein is shown in the mitotic structures (asters, spindles and centrosomes). Microinjection of anti-hsp70 antibodies into eggs causes impairment of formation of mitotic structures and of cell division. This impairment goes from a complete mitotic block, to irregular mitotic apparatus formation with irregular cleavage, depending upon the antibody concentration. The localization of hsp70 after antibody microinjection is also described. Blockage of mitotic apparatus formation by nocodazole also blocks the concentration of hsp70 …
Effect of temperature on the duration of sensitive period and on the number of photoperiodic cycles required for the induction of reproductive diapau…
2013
Abstract Correct timing of the induction of photoperiodic reproductive diapause has been found to play an important role in the life cycle of several northern insect species. However, even when the environmental conditions are favourable for diapause, the switch to diapause can only take place when the females are in a proper developmental and physiological stage, referred to as the sensitive period (SP) for diapause. We have previously shown that in a northern fly species, Drosophila montana, the developmental pathway of the ovaries (direct maturation vs. diapause) is determined by photoperiodic cues that the females receive after eclosion. Here, we have studied the effects of temperature …
Spatially restricted expression of PlOtp, a Paracentrotus lividus Orthopedia-related homeobox gene, is correlated with oral ectodermal patterning and…
1999
ABSTRACT Several homeobox genes are expressed in the sea urchin embryo but their roles in development have yet to be elucidated. Of particular interest are homologues of homeobox genes that in mouse and Drosophila are involved in patterning the developing central nervous system (CNS). Here, we report the cloning of an orthopedia (Otp)-related gene from Paracentrotus lividus, PlOtp. Otp is a single copy zygotic gene that presents a unique and highly restricted expression pattern. Transcripts were first detected at the mid-gastrula stage in two pairs of oral ectoderm cells located in a ventrolateral position, overlying primary mesenchyme cell (PMC) clusters. Increases in both transcript abund…
Cytochrome oxidase activity in the mitochondria of unfertilized and fertilized sea urchin eggs
1959
Abstract The cytochrome oxidase activity of isolated mitochondria of unfertilized and fertilized eggs of Paracentrotus lividus has been studied. It has been found that whereas in the mitochondria of unfertilized eggs saturation is reached at a cytochrome c concentration of 3.28 × 10−5 M, in those of fertilized eggs this occurs at a concentration of 5.74 × 10−5 M. It is shown that upon fertilization an increase of about 30 per cent of the activity of cytochrome oxidase takes place and no further changes appear to occur until blastula stage.
The use of morphokinetics as a predictor of embryo implantation.
2011
Background Time-lapse observation presents an opportunity for optimizing embryo selection based on morphological grading as well as providing novel kinetic parameters, which may further improve accurate selection of viable embryos. The objective of this retrospective study was to identify the morphokinetic parameters specific to embryos that were capable of implanting. In order to compare a large number of embryos, with minimal variation in culture conditions, we have used an automatic embryo monitoring system. Methods Using a tri-gas IVF incubator with a built-in camera designed to automatically acquire images at defined time points, we have simultaneously monitored up to 72 individual emb…
A new replacement name for the fossil spider Veterator Petrunkevitch, 1963 (Arthropoda: Arachnida: Araneae)
2021
A junior homonym was detected in the genera of fossil Araneae and the following replacement name is proposed within the family Trochanteriidae: Neoveterator Ceccolini & Cianferoni nom. nov. pro Veterator Petrunkevitch, 1963 nec Laws, 1944. Eight new combinations (comb. nov.) are proposed.
Pythium contiguanum nomen novum (syn. Pythium dreschleri Paul), its antagonism to Botrytis cinerea, ITS1 region of its nuclear ribosomal DNA, and its…
2000
Pythium drechsleri Paul was described as a new species from soil samples taken in a salt-marsh of Arzew, Algeria [Paul, B. (1988) Une nouvelle espece de Pythium isolee d'une saline de l'ouest Algerien. Cryptogam. Mycol. 9, 325-333]. The name of the fungus, P. drechsleri, is a nomen invalidum, as it is a later homonym of P. drechsleri Rajgopalan and Ramakrishnan [Rajagopalan, S. and Ramakrishnan, K. (1971) Phycomycetes in agricultural soils with special reference to the Pythiaceae. Madras Univ. J. Sect. B 37,38, 100-117]. A new name, Pythium contiguanum is now being given to P. drechsleri Paul. This species is characterised by its contiguous inflated type of sporangia, smooth-walled oogonia …
SOME COMPARATIVE REMARKS ON THE TRANSIENT CHANGE IN LACTIC ACID CONTENT IN SEA URCHIN EGGS FOLLOWING FERTILIZATION.
1964
Abstract During the first few minutes following fertilization a transient increase in the concentration of lactic acid occurs in the eggs of Arbacia lixula , whereas no change at all is observed in the eggs of Paracentrotus liuidus . In the eggs of Psammechinus miliaris there is a transient decrease, soon followed by a recovery so that the level of the unfertilized egg is again reached.