Prominin-1 and Photoreceptor Cadherin Localization in Xenopus laevis: Protein-Protein Relationships and Function

2019 ◽  
pp. 483-487
Author(s):  
Brittany J. Carr ◽  
Lee Ling Yang ◽  
Orson L. Moritz
Keyword(s):  
Xenopus Laevis ◽  
And Function

Ca2+ oscillations in melanotropes of Xenopus laevis: their generation, propagation, and function

2003 ◽  
Vol 131 (3) ◽  
pp. 209-219 ◽  
Author(s):  
Bruce G. Jenks ◽  
Eric W. Roubos ◽  
Wim J.J.M. Scheenen
Keyword(s):  
Xenopus Laevis ◽  
And Function

scholarly journals Histone H1 is essential for mitotic chromosome architecture and segregation in Xenopus laevis egg extracts

2005 ◽  
Vol 169 (6) ◽  
pp. 859-869 ◽  
Author(s):  
Thomas J. Maresca ◽  
Benjamin S. Freedman ◽  
Rebecca Heald
Keyword(s):  
Xenopus Laevis ◽  
Metaphase Plate ◽  
Histone H1 ◽  
Linker Histone ◽  
Chromosome Architecture ◽  
Linker Histone H1 ◽  
Egg Extracts ◽  
Chromatin Proteins ◽  
And Function

During cell division, condensation and resolution of chromosome arms and the assembly of a functional kinetochore at the centromere of each sister chromatid are essential steps for accurate segregation of the genome by the mitotic spindle, yet the contribution of individual chromatin proteins to these processes is poorly understood. We have investigated the role of embryonic linker histone H1 during mitosis in Xenopus laevis egg extracts. Immunodepletion of histone H1 caused the assembly of aberrant elongated chromosomes that extended off the metaphase plate and outside the perimeter of the spindle. Although functional kinetochores assembled, aligned, and exhibited poleward movement, long and tangled chromosome arms could not be segregated in anaphase. Histone H1 depletion did not significantly affect the recruitment of known structural or functional chromosomal components such as condensins or chromokinesins, suggesting that the loss of H1 affects chromosome architecture directly. Thus, our results indicate that linker histone H1 plays an important role in the structure and function of vertebrate chromosomes in mitosis.

scholarly journals Urocortins of the South African Clawed Frog, Xenopus laevis: Conservation of Structure and Function in Tetrapod Evolution

Endocrinology ◽  
2005 ◽  
Vol 146 (11) ◽  
pp. 4851-4860 ◽  
Author(s):  
Graham C. Boorse ◽  
Erica J. Crespi ◽  
Frank M. Dautzenberg ◽  
Robert J. Denver
Keyword(s):  
Xenopus Laevis ◽  
South African ◽  
The South ◽  
Functional Relationships ◽  
African Clawed Frog ◽  
Urocortin 1 ◽  
Crf2 Receptor ◽  
Urocortin 3 ◽  
And Function ◽  
Clawed Frog

Several corticotropin-releasing factor (CRF) family genes have been identified in vertebrates. Mammals have four paralogous genes that encode CRF or the urocortins 1, 2, and 3. In teleost fishes, a CRF, urotensin I (a fish ortholog of mammalian urocortin 1) and urocortin 3 have been identified, suggesting that at least three of the four mammalian lineages arose in a common ancestor of modern bony fishes and tetrapods. Here we report the isolation of genes orthologous to mammalian urocortin 1 and urocortin 3 from the South African clawed frog, Xenopus laevis. We characterize the pharmacology of the frog peptides and show that X. laevis urocortin 1 binds to and activates the frog CRF1 and CRF2 receptors at picomolar concentrations. Similar to mammals, frog urocortin 3 is selective for the CRF2 receptor. Only frog urocortin 1 binds to the CRF-binding protein, although with significantly lower affinity than frog CRF. Both urocortin genes are expressed in brain, pituitary, heart, and kidney of juvenile frogs; urocortin 1 is also expressed in skin. We also identified novel urocortin sequences in the genomes of pufferfish, zebrafish, chicken, and dog. Phylogenetic analysis supports the view that four paralogous lineages of CRF-like peptides arose before the divergence of the actinopterygian and sarcopterygian fishes. Our findings show that the functional relationships among CRF ligands and binding proteins, and their anorexigenic actions mediated by the CRF2 receptor, arose early in vertebrate evolution.

Structure and expression of ribosomal protein genes in Xenopus laevis

1995 ◽  
Vol 73 (11-12) ◽  
pp. 969-977 ◽  
Author(s):  
Francesco Amaldi ◽  
Olga Camacho-Vanegas ◽  
Francesco Cecconi ◽  
Fabrizio Loreni ◽  
Beatrice Cardinali ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Translational Regulation ◽  
Cultured Cells ◽  
Structural Features ◽  
Ribosomal Protein Genes ◽  
Translation Apparatus ◽  
And Function

In Xenopus laevis, as well as in other vertebrates, ribosomal proteins (r-proteins) are coded by a class of genes that share some organizational and structural features. One of these, also common to genes coding for other proteins involved in the translation apparatus synthesis and function, is the presence within their introns of sequences coding for small nucleolar RNAs. Another feature is the presence of common structures, mainly in the regions surrounding the 5′ ends, involved in their coregulated expression. This is attained at various regulatory levels: transcriptional, posttranscriptional, and translational. Particular attention is given here to regulation at the translational level, which has been studied during Xenopus oogenesis and embryogenesis and also during nutritional changes of Xenopus cultured cells. This regulation, which responds to the cellular need for new ribosomes, operates by changing the fraction of rp-mRNA (ribosomal protein mRNA) engaged on polysomes. A typical 5′ untranslated region characterizing all vertebrate rp-mRNAs analyzed to date is responsible for this translational behaviour: it is always short and starts with an 8–12 nucleotide polypyrimidine tract. This region binds in vitro some proteins that can represent putative trans-acting factors for this translational regulation.Key words: ribosomal proteins, snoRNA, translational regulation, Xenopus laevis.

scholarly journals Study of the structure and function of the HURP protein during mitotic division

2013 ◽  
Author(s):  
Κωνσταντίνος Νάκος
Keyword(s):  
Dna Binding ◽  
Xenopus Laevis ◽  
Histone Deacetylase ◽  
Dna Binding Protein ◽  
Mitotic Division ◽  
Structure And Function ◽  
Aurora A ◽  
Nucleosome Remodeling ◽  
And Function

Η πρωτεΐνη HURP (Hepatoma Up-Regulated protein) έχει αναγνωριστεί ως παράγονταςσυναρμολόγησης της ατράκτου (SAF) που ρυθμίζεται από τη RanGTP. Αρχικά βρέθηκε σε μιτωτικάεκχυλίσματα αυγών Xenopus laevis, σε σύμπλοκο με τις TPX2, XMAP215, Eg5 και Aurora A. Η HURPπροσδένεται στους μικροσωληνίσκους, εντοπίζεται κυρίως στους μικροσωληνίσκους των κινητοχώρωνκαι είναι απαραίτητη για την σωστή συναρμολόγηση της μιτωτικής ατράκτου. Παρόλο αυτά, πρωτεΐνεςπου αλληλεπιδρούν με τη HURP σε ανθρώπινα κύτταρα παραμένουν άγνωστες.Σε αυτή τη μελέτη περιγράφουμε την αναγνώριση μίας νέας πρωτεΐνης που αλληλεπιδρά με τη HURP,τη CHD4 (Chromodomain Helicase DNA binding protein 4) μία ATPάση της αναδιαμόρφωσης τηςχρωματίνης και καταλυτική υπομονάδα του συμπλόκου αποκετυλασών που ευθύνεται για τηναναδιαμόρφωση του νουκλεοσώματος (Nucleosome remodeling and histone Deacetylase - NuRD).Πρόσφατα η πρωτεΐνη CHD4 αναγνωρίστηκε ως πρωτεΐνη που προσδένεται στους μικροσωληνίσκουςκαι ρυθμίζεται από την RanGTP.Οι μελέτες μας σε ανθρώπινα κύτταρα έδειξαν ότι η CHD4 κατά τη μίτωση απελευθερώνεται από ταμιτωτικά χρωμοσώματα και εντοπίζεται στην άτρακτο, υποδεικνύοντας ένα καινούριο ρόλο της CHD4στη συναρμολόγηση της ατράκτου. Για να κατανοήσουμε τη λειτουργία της CHD4 πραγματοποιήσαμεμελέτες απαλοιφής της CHD4 με την τεχνική της αποσιώπισης γονιδίου με siRNA. Μείωση της CHD4προκαλεί βλάβες στη συναρμολόγηση της μιτωτικής ατράκτου και στη στοίχιση των χρωμοσωμάτωνστις αρχές της μίτωσης, οδηγώντας σε ανώμαλο διαχωρισμό των χρωμοσωμάτων. Επιπλέον, ηαπώλεια της CHD4 επηρρεάζει τη σταθερότητα των K-fibers μειώνοντας σημαντικά την ποσότητα των μικροσωληνίσκων των κινητοχώρων. Μετά την απαλοιφή της CHD4, ο εντοπισμός της HURP βρέθηκενα αλλάζει, χάνοντας την προτίμησή της για τους μικροσωληνίσκους, των κινητοχώρων,υποδεικνύοντας την πιθανή ρύθμιση του εντοπισμού της HURP από την CHD4. Τέλος από in vitro καιin vivo πειράματα, βρήκαμε ότι η CHD4 αλληλεπιδρά με τη μιτωτική κινάση Aurora A και την πρωτεΐνηTPX2 που συνδέεται με μικροσωληνίσκους, δημιουργώντας ένα καινούριο σύμπλοκο σημαντικό για τηλειτουργία της μιτωτικής ατράκτου στα κύτταρα θηλαστικών.

scholarly journals Size-dependent functional response of Xenopus laevis feeding on mosquito larvae

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5813 ◽  
Author(s):  
Corey J. Thorp ◽  
Mhairi E. Alexander ◽  
James R. Vonesh ◽  
John Measey
Keyword(s):  
Xenopus Laevis ◽  
Functional Response ◽  
Handling Time ◽  
Mosquito Larvae ◽  
Agricultural Pests ◽  
Food Web Structure ◽  
Predator Prey ◽  
Predator Attack ◽  
Considerable Individual Variation ◽  
And Function

Predators can play an important role in regulating prey abundance and diversity, determining food web structure and function, and contributing to important ecosystem services, including the regulation of agricultural pests and disease vectors. Thus, the ability to predict predator impact on prey is an important goal in ecology. Often, predators of the same species are assumed to be functionally equivalent, despite considerable individual variation in predator traits known to be important for shaping predator–prey interactions, like body size. This assumption may greatly oversimplify our understanding of within-species functional diversity and undermine our ability to predict predator effects on prey. Here, we examine the degree to which predator–prey interactions are functionally homogenous across a natural range of predator body sizes. Specifically, we quantify the size-dependence of the functional response of African clawed frogs (Xenopus laevis) preying on mosquito larvae (Culex pipiens). Three size classes of predators, small (15–30 mm snout-vent length), medium (50–60 mm) and large (105–120 mm), were presented with five densities of prey to determine functional response type and to estimate search efficiency and handling time parameters generated from the models. The results of mesocosm experiments showed that type of functional response of X. laevis changed with size: small predators exhibited a Type II response, while medium and large predators exhibited Type III responses. Functional response data showed an inversely proportional relationship between predator attack rate and predator size. Small and medium predators had highest and lowest handling time, respectively. The change in functional response with the size of predator suggests that predators with overlapping cohorts may have a dynamic impact on prey populations. Therefore, predicting the functional response of a single size-matched predator in an experiment may misrepresent the predator’s potential impact on a prey population.

Skin Morphology and Function in Xenopus laevis Exposed to a Saline Environment for up to One Week

2000 ◽  
Vol 38 (3) ◽  
pp. 176-185 ◽  
Author(s):  
G. Lodi ◽  
D. Donna ◽  
B. Dore ◽  
P. Usai ◽  
M. Biciotti
Keyword(s):  
Xenopus Laevis ◽  
Saline Environment ◽  
Skin Morphology ◽  
And Function
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