1,721,012 research outputs found
Maternal mRNAs asymmetrically localized and differentially expressed during oogenesis of the hybidogenetic model system Rana
No full textMolecular cloning and developmental expression of 5-HT1A receptor gene in Xenopus laevis
No full textIdentification of different forms of calpastatin mRNA co-expressed in the notochord of Xenopus laevis embryos
No full textThe hybridogenetic Rana (Pelophylax) esculenta complex studied in a molecular context
No full textThe study of hybridogenesis is expected to shed light on the role played by the so-called ‘asexual reproduction’ in vertebrate evolution, since hybridogenesis, gynogenesis and parthenogenesis are restricted to lower vertebrates. Hence, it seemed interesting to define the stage and time of germline differentiation in reproductively unstable organisms which, to accomplish functional gamete maturation, can change the normal approach to meiosis by means of unusual cytological steps, such as genome elimination and endoreduplication. The cytogenetic aspects of ‘asexual’ meiosis have already been thoroughly studied. At present, molecular investigations are in progress to characterise the single steps of germline differentiation in a hybridogenetic green frog system, and the results obtained so far can be considered promising, as shown in this work. Vasa, PL10 and Y-box homolog genes, first isolated in Rana (Pelophylax), are expressed during early phases of
gametogenesis in R. (P.) ridibunda and R. (P.) lessonae (parental species), and R. (P.) esculenta (their natural hybrid), suggesting that gametogenesis, during the adult life, follows a unique genetic sequence in the two parental species as well as in hybridogenetic hybrids. Similar molecular investigations need to be carried out on larval stages prior to metamorphosis, when the genetic plasticity of gemline cells allows their commitment versus either the standard and/or hybridogenetic reproduction mode
The European plethodontid salamanders and their evolutionary relationships: a cytomolecular approach
No full textIsolation and expression of RlYB2, a germ cell-specific Y-box gene in Rana
No full textY-box proteins are a highly conserved family of gene expression regulatory factors. During gametogenesis they may play a dual role, as both transcriptional activators of germ cell-specific genes and as translational repressors of stored maternal transcripts. We report the identification of RlYB2, a Y-box homolog gene specifically expressed in the germ cells of green frogs belonging to Rana esculenta complex, a model system characterized by a hybridogenetic gametogenesis. In developing germ cells of the hybrid R. esculenta, arisen by natural cross of the parental species R. ridibunda and R. lessonae, one set of the parental genomes is excluded and the remaining one, first endoreduplicates and then is transmitted to gametes. In situ hybridizations performed on gonadal tissues showed that the RlYB2 transcript was widely expressed in the ooplasm at early stages of oogenesis in both the parental species and hybrids. Interestingly, a hybridization signal, presumably related to RlYB2-like nascent transcripts, was observed in nuclei of stage II oocytes. The presence of RlYB2 mRNA during early oogenesis suggests that this gene may be involved in regulating the transcription and/or translation of maternal mRNAs in this special vertebrate model system
Surveys on populations of green frogs (Pelophylax) of Western Tuscany sites with molecular and morphometric methods
No full textThe water frogs of western Tuscany (Italy) belong to the L-E hybridogenetic system, and comprise one parental
species and its hybrid. A stringent morphological approach for discriminating the Italian hybrids from non-hybrids has yet
to be established. In this work, using the molecular marker RrS1, we have determined the hybrid versus non-hybrid status
of 43 water frogs collected from two sampling sites (“Fiume Morto Vecchio” and “Padule di Bientina”). At “Fiume Morto
Vecchio” we determined 25 non-hybrids and nine hybrids and in “Padule di Bientina” we determined eight hybrids and one
non-hybrid individual. All individuals of these two frog populations were analyzed morphologically. We used the derived
residuals from regression analysis of all normally distributed morphological parameters on callus internus length (snout to
vent length, tibia length, head width, distance nostril eye, first toe length and body mass) to build sex independent variables
in discriminant analysis providing a valid contribution to morphologically distinguish hybrids from non-hybrid green frogs
in Italy
Kidins220/ARMS is dynamically expressed during Xenopus laevis development.
No full textKidins220 (Kinase D interacting substrate of 220 kDa)/ARMS (Ankyrin Repeat-rich Membrane Spanning) is a conserved scaffold protein that acts as a downstream substrate for protein kinase D and mediates multiple receptor signalling pathways. Despite the dissecting of the function of this protein in mammals, using both in vitro and in vivo studies, a detailed characterization of its gene expression during early phases of embryogenesis has not been described yet. Here, we have used Xenopus laevis as a vertebrate model system to analyze the gene expression and the protein localization of Kidins220/ARMS. We found its expression was dynamically regulated during development. Kidins220/ARMS mRNA was expressed from neurula to larval stage in different embryonic regions including the nervous system, eye, branchial arches, heart and somites. Similar to the transcript, the protein was present in multiple embryonic domains including the central nervous system, cranial nerves, motor nerves, intersomitic junctions, retinal ganglion cells, lens, otic vesicle, heart and branchial arches. In particular, in some regions such as the retina and somites, the protein displayed a differential localization pattern in stage 42 embryos when compared to the earlier examined stages. Taken together our results suggest that this multidomain protein is involved in distinct spatio-temporal differentiative events
Repetitive DNA components of the large Hydromantes genome: phylogenetic and molecular aspects
No full textXdtx1, a Xenopus Deltex homologue expressed in differentiating neurons and in photoreceptive organs
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