Publications

TitleAbstractYear(sorted descending)
Filter
PMID
Filter
preserving genome integrity during the early embryonic dna replication cycles.during the very early stages of embryonic development chromosome replication occurs under rather challenging conditions, including a very short cell cycle, absence of transcription, a relaxed dna damage response and, in certain animal species, a highly contracted s-phase. this raises the puzzling question of how the genome can be faithfully replicated in such a peculiar metabolic context. recent studies have provided new insights into this issue, and unveiled that embryos are prone to accumulate ...201931137726
growth at cold temperature increases the number of motor neurons to optimize locomotor function.during vertebrate development, spinal neurons differentiate and connect to generate a system that performs sensorimotor functions critical for survival. spontaneous ca2+ activity regulates different aspects of spinal neuron differentiation. it is unclear whether environmental factors can modulate this ca2+ activity in developing spinal neurons to alter their specialization and ultimately adjust sensorimotor behavior to fit the environment. here, we show that growing xenopus laevis embryos at col ...201931130453
genome wide decrease of dna replication eye density at the midblastula transition of xenopus laevis.during the first rapid divisions of early development in many species, the dna:cytoplasm ratio increases until the midblastula transition (mbt) when transcription resumes and cell cycles lengthen. s phase is very rapid in early embryos, about 20-30 times faster than in differentiated cells. using a combination of dna fiber studies and a xenopus laevis embryonic in vitro replication system, we show that s phase slows down shortly after the mbt owing to a genome wide decrease of replication eye de ...201931130065
involvement of myt1 kinase in the g2 phase of the first cell cycle in xenopus laevis.during cleavage of xenopus laevis, the first mitotic cell cycle immediately following fertilization is approximately 90 min and consists of s, g2, and m phases. in contrast, the subsequent eleven cell cycles are approximately 30 min and consist mostly of s and m phases. the balance between cdc25 and wee1a/myt1 is thought to be crucial for xenopus first cell cycle progression; however, the role of myt1 in this period has not been fully investigated. in this study, we examined the roles of myt1, w ...201931128913
methods for studying dna single-strand break repair and signaling in xenopus laevis egg extracts.dna single-strand breaks (ssbs) are the most common type of dna lesions as they are generated approximately 10,000 times per mammalian cell each day. unrepaired ssbs compromise dna replication and transcription programs, leading to genome instability, and have been implicated in many diseases including cancer. in this chapter, we introduce methods to study the atr-chk1 dna damage response (ddr) pathway and dna repair pathway in response to a site-specific, defined ssb plasmid in xenopus laevis e ...201931127575
ptk7 proteolytic fragment proteins function during early xenopus development.protein tyrosine kinase 7 (ptk7) is as a critical regulator of canonical and non-canonical wnt-signaling during embryonic development and cancer cell formation. disrupting ptk7 activity perturbs vertebrate nervous system development, and also promotes human cancer formation. observations in different model systems suggest a complex cross-talk between ptk7 protein and wnt signaling. during xenopus laevis nervous system development, we previously showed that ptk7 protein positively regulates canon ...201931125531
development of an in vitro diagnostic method to determine the genotypic sex of xenopus laevis.a genotypic sex determination assay provides accurate gender information of individuals with well-developed phenotypic characters as well as those with poorly developed or absent of phenotypic characters. determination of genetic sex for xenopus laevis can be used to validate the outcomes of tier 2 amphibian assays, and is a requirement for conducting the larval amphibian growth and development assay (lagda), in the endocrine disruptor screening program (edsp), test guidelines. the assay we deve ...201931106075
composition and endocrine effects of water collected in the kibale national park in uganda.pesticides are used worldwide with potential harmful effects on both fauna and flora. the kibale national park in uganda, a site renowned for its biodiversity is surrounded by tea, banana and eucalyptus plantations as well as maize fields and small farms. we previously showed presence of pesticides with potential endocrine disruptive effects in the vicinity. to further investigate the water pollution linked to agricultural pressure in this protected area, we implemented a complementary monitorin ...201931103006
identification of a regeneration-organizing cell in the xenopus tail.unlike mammals, xenopus laevis tadpoles have a high regenerative potential. to characterize this regenerative response, we performed single-cell rna sequencing after tail amputation. by comparing naturally occurring regeneration-competent and -incompetent tadpoles, we identified a previously unrecognized cell type, which we term the regeneration-organizing cell (roc). rocs are present in the epidermis during normal tail development and specifically relocalize to the amputation plane of regenerat ...201931097661
embryonic expression of gins members in the development of the mammalian nervous system.the gins (go, ichi, nii, and san) complex contains four protein subunits (psf1, psf2, psf3, and sld5) and has been identified as a factor essential for the initiation and elongation stages of the dna replication process. a previous study indicated that psf2 participated in the developing central nervous system (cns) of xenopus laevis. however, the expression and function of gins members in the mammalian developing nervous system remains unclear. here, we examined the expression of gins members i ...201931095979
spindle-f-actin interactions in mitotic spindles in an intact vertebrate epithelium.mitotic spindles are well known to be assembled from and dependent on microtubules. in contrast, whether actin filaments (f-actin) are required for or are even present in mitotic spindles has long been controversial. here we have developed improved methods for simultaneously preserving f-actin and microtubules in fixed samples and exploited them to demonstrate that f-actin is indeed associated with mitotic spindles in intact xenopus laevis embryonic epithelia. we also find that there is an "f-ac ...201931091161
neurotoxicity and mode of action of fluralaner on honeybee apis mellifera l.fluralaner, a novel pesticide that targets the γ-aminobutyric acid (gaba) receptor (gabar) subunit of resistant to dieldrin (rdl), exhibits strong potential to be an insecticide to control agricultural insect pests. however, the risk and action of fluralaner to economic insects, e.g., honeybee apis mellifera linnaeus, remains unclear.201931081291
xenopus resources: transgenic, inbred and mutant animals, training opportunities, and web-based support.two species of the clawed frog family, xenopus laevis and x. tropicalis, are widely used as tools to investigate both normal and disease-state biochemistry, genetics, cell biology, and developmental biology. to support both frog specialist and non-specialist scientists needing access to these models for their research, a number of centralized resources exist around the world. these include centers that hold live and frozen stocks of transgenic, inbred and mutant animals and centers that hold mol ...201931073289
pdgf-b: the missing piece in the mosaic of pdgf family role in craniofacial development.the platelet-derived growth factor (pdgf) family consists of four ligands (pdgf-a, pdgf-b, pdgf-c, pdgf-d) and two tyrosine kinase receptors (pdgfr-α and pdgfr-β). in vertebrates, pdgf signaling influences cell proliferation, migration, and matrix deposition, and its up-regulation is implicated in cancer progression. despite this evidence, the role of each family member during embryogenesis is still incomplete and partially controversial. in particular, study of the role of pdgf signaling during ...201931070827
the xenopus tropicalis model for studies of developmental and reproductive toxicity.the reproductive cycle encompasses processes such as sex organ differentiation and development in the early life stages and maturation of the gametes in the adult organism. during the early life stages, critical developmental programming of the endocrine and reproductive systems occurs, and exposure to chemicals during these critical developmental windows can result in impaired reproductive function later in life. it is therefore important to evaluate long-term consequences of early life stage e ...201931069675
disrupted plasma membrane protein homeostasis in a xenopus laevis model of retinitis pigmentosa.rhodopsin mislocalization is frequently observed in retinitis pigmentosa (rp) patients. for example, class i mutant rhodopsin is deficient in the vxpx trafficking signal, mislocalizes to the plasma membrane (pm) of rod photoreceptor inner segments (iss), and causes autosomal dominant rp. mislocalized rhodopsin causes photoreceptor degeneration in a manner independent of light-activation. in this manuscript, we took advantage of xenopus laevis models of both sexes expressing wild-type human rhodo ...201931061086
antinociceptive effects of new pyrazoles compounds mediated by the asic-1α channel, trpv-1 and μmor receptors.pyrazoles are potent medicinal scaffolds and exhibit a wide spectrum of biological activities, such as analgesic, anti-inflammatory and antipyretic. in this paper we report on research we have performed with the aim of continuing the biological evaluation of the regio-isomeric pyrazole compounds, lqfm-020 (fluorine, para position), lqfm-021 (fluorine, meta position), and lqfm-039 (fluorine, ortho position) in models of pain induced by acidified saline, capsaicin, and formalin. we also investigat ...201931055237
isolation of nanobodies against xenopus embryonic antigens using immune and non-immune phage display libraries.the use of xenopus laevis as a model for vertebrate developmental biology is limited by a lack of antibodies specific for embryonic antigens. this study evaluated the use of immune and non-immune phage display libraries for the isolation of single domain antibodies, or nanobodies, with specificities for xenopus embryonic antigens. the immune nanobody library was derived from peripheral blood lymphocyte rna obtained from a llama immunized with xenopus gastrula homogenates. screening this library ...201931048885
positively charged tags impede protein mobility in cells as quantified by 19f nmr.proteins are often tagged for visualization or delivery in the "sea" of other macromolecules in cells but how tags affect protein mobility remains poorly understood. here, we employ in-cell 19f nmr to quantify the mobility of proteins with charged tags in escherichia coli cells and xenopus laevis oocytes. we find that the transient charge-charge interactions between the tag and cellular components affect protein mobility. more specifically, positively charged tags impede protein mobility.201931042382
wolf-hirschhorn syndrome-associated genes are enriched in motile neural crest cells and affect craniofacial development in xenopus laevis.wolf-hirschhorn syndrome (whs) is a human developmental disorder arising from a hemizygous perturbation, typically a microdeletion, on the short arm of chromosome four. in addition to pronounced intellectual disability, seizures, and delayed growth, whs presents with a characteristic facial dysmorphism and varying prevalence of microcephaly, micrognathia, cartilage malformation in the ear and nose, and facial asymmetries. these affected craniofacial tissues all derive from a shared embryonic pre ...201931031646
methods for investigating trp channel gating.a complete characterization of temperature -and voltage-activated trp channel gating requires a precise determination of the absolute probability of opening in a wide range of voltages, temperatures, and agonist concentrations. we have achieved this in the case of the trpm8 channel expressed in xenopus laevis oocytes. measurements covered an extensive range of probabilities and unprecedented applied voltages up to 500 mv. in this chapter, we describe animal care protocols of patch-clamp pipette ...201931028680
the c-type atp-binding cassette transporter osabcc7 is involved in the root-to-shoot translocation of arsenic in rice.rice is a major dietary source of inorganic arsenic (as), a nonthreshold carcinogen. reducing as accumulation in rice grain is of critical importance for food safety. in the present study, we investigated the role of a member of the rice c-type atp-binding cassette (abc) transporter (osabcc) family, osabcc7, in arsenite [as(iii)] accumulation in rice. quantitative real-time rt-pcr showed that osabcc7 was expressed intensively in the roots and the expression was strongly suppressed by as(iii) exp ...201931028396
a ywhaz variant associated with cardiofaciocutaneous syndrome activates the raf-erk pathway.cardiofaciocutaneous (cfc) syndrome is a genetic disorder characterized by distinctive facial features, congenital heart defects, and skin abnormalities. several germline gain-of-function mutations in the ras/raf/mek/erk pathway are associated with the disease, including kras, braf, mek1, and mek2. cfc syndrome thus belongs to a group of disorders known as rasopathies, which are all caused by pathogenic mutations in various genes encoding components of the ras pathway. we recently identified nov ...201931024343
effects of nonylphenols on embryonic development and metamorphosis of xenopus laevis: fetax and amphibian metamorphosis toxicity test (oecd tg231).nonylphenols (nps) are a group of endocrine-disrupting surfactants that mimic estrogen. to determine the developmental toxicity and thyroid-disrupting effect of nps, the effects of exposure to nonylphenol (np), 4-nonylphenol (4-np), and nonylphenol ethoxylate (np-12) were examined according to the frog embryo teratogenesis assay-xenopus (fetax) and organization for economic co-operation and development test guidelines 231 (tg231). in fetax, the lc50 values of np, 4-np, and np-12 were 59.14 mg/l, ...201931022611
slpi inhibits atp-mediated maturation of il-1β in human monocytic leukocytes: a novel function of an old player.interleukin-1β (il-1β) is a potent, pro-inflammatory cytokine of the innate immune system that plays an essential role in host defense against infection. however, elevated circulating levels of il-1β can cause life-threatening systemic inflammation. hence, mechanisms controlling il-1β maturation and release are of outstanding clinical interest. secretory leukocyte protease inhibitor (slpi), in addition to its well-described anti-protease function, controls the expression of several pro-inflammat ...201931019507
special considerations for making explants and transplants with xenopus tropicalis.although xenopus laevis is an important model organism for embryological experimentation, the smaller, more genetically tractable, and faster developing xenopus tropicalis provides advantages for using genetic approaches to understand developmental mechanisms. explant cultures and transplants of x. tropicalis embryonic tissues present unique opportunities to examine embryonic tissue determination in a simplified setting. here we demonstrate preparation of explants and transplants of preplacodal ...201931010887
altering the levels of nuclear import factors in early xenopus laevis embryos affects later development.more than just a container for dna, the nuclear envelope carries out a wide variety of critical and highly regulated cellular functions. one of these functions is nuclear import, and in this study we investigate how altering the levels of nuclear transport factors impacts developmental progression and organismal size. during early xenopus laevis embryogenesis, the timing of a key developmental event, the midblastula transition (mbt), is sensitive to nuclear import factor levels. how might alteri ...201931009515
urokinase-type plasminogen activator (upa) is not essential for epithelial sodium channel (enac)-mediated sodium retention in experimental nephrotic syndrome.in nephrotic syndrome, aberrantly filtered plasminogen (plg) is converted to active plasmin by tubular urokinase-type plasminogen activator (upa) and thought to lead to sodium retention by proteolytic activation of the epithelial sodium channel (enac). this concept predicts that upa is an important factor for sodium retention and that inhibition of upa might be protective in nephrotic syndrome.201931006168
studies of limb regeneration in larval xenopus.a basic protocol is given for animal maintenance and surgery in studies of hindlimb regeneration in larval xenopus laevis unlike urodele limbs, those of larval frogs typically show much more variation in the extent of regeneration after amputation. such variation can be reduced by optimizing the conditions of larval maintenance to regulate the rates of growth and development, by selecting only larvae with normal rates of growth and morphological development for experimental use, and by attention ...201929895566
investigating the cellular and molecular mechanisms of wound healing in xenopus oocytes and embryos.the african clawed frog xenopus has remarkable capacities to heal wounds rapidly and to regenerate complex tissues. because of its experimental tractability, studies using xenopus oocytes, embryos, and larvae have contributed extensively to our understanding of the molecular and cellular mechanisms underpinning wound healing and tissue regeneration. in this protocol, we describe wound-healing assays following mechanical or laser injuries of oocytes and multicellular epithelia in xenopus laevis e ...201929895564
ex vivo eye tissue culture methods for xenopus.lens regeneration can be studied in whole animals following removal of the original lens (lentectomy). however, culturing a whole animal can be impractical for assays involving small molecule inhibitors or proteins. ex vivo eye tissue culture is an alternative approach for examining lens regeneration. the ex vivo culture system offers certain advantages when compared to the in vivo regeneration assay, as the percentage of cases showing lens differentiation can exceed that seen in whole animals. ...201929895561
copper uptake mechanism of arabidopsis thaliana high-affinity copt transporters.copper (cu) is an essential plant micronutrient. under scarcity, cu2+ is reduced to cu+ and taken up through specific high-affinity transporters (copts). in arabidopsis, the copt family consists of six members, either located at the plasma membrane (copt1, copt2, and copt6) or in internal membranes (copt3 and copt5). cu uptake by copt proteins has been mainly assessed through complementation studies in corresponding yeast mutants, but the mechanism of this transport has not been elucidated. to t ...201930043153
following endocrine-disrupting effects on gene expression in xenopus laevis.endocrine-disrupting chemicals (edcs), found in all categories of chemicals, are suspected to be a cause of declining well-being and human health, both as single molecules and as mixtures. it is therefore necessary to develop high throughput methods to assess the endocrine-disrupting potential of multiple chemicals currently on the market that are as yet untested. an advantage of in vivo chemical screening is that it provides a full spectrum of physiological impacts exerted by a given chemical. ...201930042138
assessing antibody responses to pathogens or model antigens in xenopus by enzyme-linked immunosorbent assay (elisa).xenopus laevis-specific monoclonal antibodies recognize igm and igy antibodies not only from x. laevis but also x. tropicalis as well as a variety of amphibian species including ranidae, bufonidae, and even some salamanders. these reagents are very useful to assess antibody responses from the serum or other animal secretions (e.g., peritoneal fluid). we present here an enzyme-linked immunosorbent assay (elisa) optimized for amphibians that permits users to detect and titrate the presence of each ...201930042135
expression cloning human and rat renal cortex na/pi cotransporters: behind the scenes in the murer laboratory.in the pre-genomic era, the cloning of a cdna represented a significant achievement, particularly if the gene of interest encoded a membrane protein. at the time, molecular probes such as partial peptide sequences, suitable nucleic acid sequences, or antibodies were unavailable for most proteins and the "sodium-phosphate transporter" was no exception. in contrast, brush-border membrane vesicles and epithelial cell culture experiments had established a reliable set of functional hallmarks that de ...201930175377
endoplasmic reticulum network formation with xenopus egg extracts.the endoplasmic reticulum (er) consists of morphologically distinct domains, including a polygonal network of tubules that is connected by three-way junctions. this network is found in all eukaryotic cells. extracts from xenopus laevis eggs contain stockpiles of components that allow the assembly of an er network in vitro. here we provide protocols for assembly of er networks in extracts that are arrested at different stages of the cell cycle. unfertilized xenopus laevis eggs contain a cytostati ...201929475993
lymphocyte deficiency induced by sublethal irradiation in xenopus.in many studies of diseases affecting amphibians, it is important to determine to what extent lymphocyte-mediated defenses are involved. for example, in studies of the nature of the immune response of xenopus laevis to the amphibian chytrid fungus, batrachochytrium dendrobatidis, it was essential to determine if mucosal antimicrobial peptides or lymphocyte-mediated immunity was most important for resistance to this skin pathogen. in this protocol, we describe a method for sublethal irradiation t ...201930104411
mass spectrometry-based absolute quantification of single xenopus embryo proteomes.early xenopus development is characterized by a poor correlation between global mrna and protein abundances due to maternal mrna and protein loading. therefore, proteome profiling is necessary to study gene expression dynamics during early xenopus development. in contrast to mammals, single xenopus eggs and embryos contain enough protein to allow identification and quantification of thousands of proteins using mass spectrometry-based proteomics. in addition to investigating developmental process ...201930104410
regulation of melanopsin signaling: key interactions of the nonvisual photopigment.melanopsin is a g protein-coupled receptor with a peak sensitivity in the blue part of the spectrum, which plays a key role in nonvisual light-mediated signaling. recently, its importance in forming visual pathway as well as its role in blood vessels photorelaxation was also revealed. melanopsin was discovered in 1998 in xenopus leavis. since then, the melanopsin presence was demonstrated across the species. the existence of two melanopsin genes (opn4m and opn4x) as well as melanopsin isoforms r ...201930102761
nucleotide receptor p2ry4 is required for head formation via induction and maintenance of head organizer in xenopus laevis.vertebrates have unique head structures that are mainly composed of the central nervous system, the neural crest, and placode cells. these head structures are brought about initially by the neural induction between the organizer and the prospective neuroectoderm at early gastrula stage. purinergic receptors are activated by nucleotides released from cells and influence intracellular signaling pathways, such as phospholipase c and adenylate cyclase signaling pathways. as p2y receptor is vertebrat ...201930069871
chromatin characterization in xenopus laevis cell-free egg extracts and embryos.xenopus laevis development is marked by accelerated cell division solely supported by the proteins maternally deposited in the egg. oocytes mature to eggs with concomitant transcriptional silencing. the unique maternal chromatin state contributing to this silencing and subsequent zygotic activation is likely established by histone posttranslational modifications and histone variants. therefore, tools for understanding the nature and function of maternal and embryonic histones are essential to de ...201929475998
environmental oxygen exposure allows for the evolution of interdigital cell death in limb patterning.amphibians form fingers without webbing by differential growth between digital and interdigital regions. amniotes, however, employ interdigital cell death (icd), an additional mechanism that contributes to a greater variation of limb shapes. here, we investigate the role of environmental oxygen in the evolution of icd in tetrapods. while cell death is restricted to the limb margin in amphibians with aquatic tadpoles, eleutherodactylus coqui, a frog with terrestrial-direct-developing eggs, has ce ...201931204171
transcriptome profiling reveals male- and female-specific gene expression pattern and novel gene candidates for the control of sex determination and gonad development in xenopus laevis.xenopus laevis is an amphibian (frog) species widely used in developmental biology and genetics. to unravel the molecular machinery regulating sex differentiation of xenopus gonads, we analyzed for the first time the transcriptome of developing amphibian gonads covering sex determination period. we applied microarray at four developmental stages: (i) nf50 (undifferentiated gonad during sex determination), (ii) nf53 (the onset of sexual differentiation of the gonads), (iii) nf56 (sexual different ...201930972573
expression of tcr genes in adult and larval xenopus laevis.in order to better understand the development and function of γδ t cells in xenopus frogs, it is necessary to determine where and when γδ t cells are found in xenopus tissues. this study examined the expression of tcr genes, focused primarily on tcr γ, in tissues of adult and larval xenopus laevis and provide new data about the expression pattern of these different tcr genes in this anuran amphibian. tcr gene expression was detected by rt-pcr in adult frog tissues including the thymus, spleen, s ...201930738793
in vitro inhibition of human nucleoside transporters and uptake of azacitidine by an isocitrate dehydrogenase-2 inhibitor enasidenib and its metabolite agi-16903.1. the present study investigated inhibitory effects of enasidenib and its metabolite agi-16903 on (a) recombinant human nucleoside transporters (hnts) in hnt-producing xenopus laevis oocytes, and (b) azacitidine uptake in a normal b-lymphoblast peripheral blood cell line (pbc) and acute myeloid leukemia (aml) cell lines. 2. enasidenib inhibited hent1, hent2, hent3, and hent4 in oocytes with ic50 values of 7, 63, 27, and 76 μm, respectively, but exhibited little inhibition of hcnt1-3. agi-16903 ...201930394160
paracetamol-induced liver injury modelled in xenopus laevis embryos.failure to predict drug-induced liver injury (dili) remains a major contributing factor to lead compound drop-out during drug development. xenopus embryos are amenable for early stage medium throughput small molecule screens and so have the potential to be used in pre-clinical screens. to begin to assess the usefulness and limitations of xenopus embryos for safety assessment in the early phases of drug development, paracetamol was used as a model hepatotoxin. paracetamol overdose is associated w ...201930282005
conservation and divergence of protein pathways in the vertebrate heart.heart disease is the leading cause of death in the western world. attaining a mechanistic understanding of human heart development and homeostasis and the molecular basis of associated disease states relies on the use of animal models. here, we present the cardiac proteomes of 4 model vertebrates with dual circulatory systems: the pig (sus scrofa), the mouse (mus musculus), and 2 frogs (xenopus laevis and xenopus tropicalis). determination of which proteins and protein pathways are conserved and ...201931490923
discovery of the arp2 protein as a determining molecule in tumor cell death.cancer is a multifactorial disease that constitutes a serious public health problem worldwide. prostate cancer advanced stages are associated with the development of androgen-independent tumors and an apoptosis-resistant phenotype that progresses to metastasis. by studying androgen-independent lymphoid nodule carcinoma of the prostate (lncap) cells induced to apoptosis by serum elimination, we identified the activation of a non-selective cationic channel of 23ps conductance that promotes incomin ...201932091029
descubrimiento de la proteína reguladora de apoptosis 2 como determinante en la muerte de células tumorales.cancer is a multifactorial disease that constitutes a serious public health problem worldwide. prostate cancer advanced stages are associated with the development of androgen-independent tumors and an apoptosis-resistant phenotype that progresses to metastasis. by studying androgen-independent lymphoid nodule carcinoma of the prostate (lncap) cells induced to apoptosis by serum elimination, we identified the activation of a non-selective cationic channel of 23ps conductance that promotes incomin ...201931695224
a flipr assay for discovery of gabaa receptor modulators of natural origin.a fluorometric imaging plate reader (flipr) assay utilizing chinese hamster ovary (cho) cells stably transfected with gabaa receptors of α1β2γ2 subunit composition was evaluated and validated for rapid screening of plant extract libraries and efficient localization of active compounds in extracts. validation was performed with pure compounds and extracts known to contain allosteric gabaa receptor modulators. plants extracts that had been previously reported as active in an assay using xenopus la ...201931127604
[exploring the mysteries of megakaryocytopoiesis and thrombopoiesis through comparative hematology].in modern hematology, research on hematopoiesis and blood cells in vertebrates, such as birds, reptiles, amphibians, and fish, is lagging. this is because there are many experimental constraints when selecting subjects other than humans and mice as research subjects. currently, the availability of flow cytometry to count classified nucleated blood cells and utilization of whole genome information have led to novel findings. for example, in case of amphibian hematopoiesis studies, megakaryocytes ...201931597828
distinct host-mycobacterial pathogen interactions between resistant adult and tolerant tadpole life stages of xenopus laevis.mycobacterium marinum is a promiscuous pathogen infecting many vertebrates, including humans, whose persistent infections are problematic for aquaculture and public health. among unsettled aspects of host-pathogen interactions, the respective roles of conventional and innate-like t (it) cells in host defenses against m. marinum remain unclear. in this study, we developed an infection model system in the amphibian xenopus laevis to study host responses to m. marinum at two distinct life stages, t ...201931591148
different pharmacological properties of glut9a and glut9b: potential implications in preeclampsia.glucose transporter 9 (glut9/slc2a9) is the major regulator of uric acid homeostasis in humans. hyperuricemia due to impaired regulation by glut9 in pregnancy is closely associated with preeclampsia. while glut9 is expressed in two alternative splice variants, glut9a and glut9b, with different subcellular localizations, no functional differences of the two splice variants are known to date. the aim of this study was to investigate the function of both glut9 isoforms.201931502429
heterologous hyaluronic acid production in kluyveromyces lactis.hyaluronic acid (ha) is a biopolymer composed by the monomers glucuronic acid (glcua) and n-acetyl glucosamine (glcnac). it has a broad range of applications in the field of medicine, being marketed between usd 1000-5000/kg. its primary sources include extraction of animal tissue and fermentation using pathogenic bacteria. however, in both cases, extensive purification protocols are required to prevent toxin contamination. in this study, aiming at creating a safe ha producing microorganism, the ...201931466214
advancing genetic and genomic technologies deepen the pool for discovery in xenopus tropicalis.xenopus laevis and xenopus tropicalis have long been used to drive discovery in developmental, cell, and molecular biology. these dual frog species boast experimental strengths for embryology including large egg sizes that develop externally, well-defined fate maps, and cell-intrinsic sources of nutrients that allow explanted tissues to grow in culture. development of the xenopus cell extract system has been used to study cell cycle and dna replication. xenopus tadpole tail and limb regeneration ...201931254427
adaptive correction of craniofacial defects in pre-metamorphic xenopus laevis tadpoles involves thyroid hormone-independent tissue remodeling.although it is well established that some organisms can regenerate lost structures, the ability to remodel existing malformed structures has been less well studied. therefore, in this study we examined the ability of pre-metamorphic xenopus laevis tadpoles to self-correct malformed craniofacial tissues. we found that tadpoles can adaptively improve and normalize abnormal craniofacial morphology caused by numerous developmental perturbations. we then investigated the tissue-level and molecular me ...201931253636
the amphibian (xenopus laevis) colony-stimulating factor-1 and interleukin-34-derived macrophages possess disparate pathogen recognition capacities.pathogens such as the frog virus 3 (fv3) ranavirus are contributing to the worldwide amphibian declines. while amphibian macrophages (mϕs) are central to the immune defenses against these viruses, the pathogen recognition capacities of disparate amphibian mϕ subsets remain unexplored. in turn, mϕ differentiation and functionality are interdependent on the colony-stimulating factor-1 receptor (csf-1r), which is ligated by colony-stimulating factor-1 (csf-1) and the unrelated interleukin-34 (il-34 ...201931029710
the voltage sensing phosphatase (vsp) localizes to the apical membrane of kidney tubule epithelial cells.voltage-sensing phosphatases (vsps) are transmembrane proteins that couple changes in membrane potential to hydrolysis of inositol signaling lipids. vsps catalyze the dephosphorylation of phosphatidylinositol phosphates (pips) that regulate diverse aspects of cell membrane physiology including cell division, growth and migration. vsps are highly conserved among chordates, and their rna transcripts have been detected in the adult and embryonic stages of frogs, fish, chickens, mice and humans. how ...201930964862
developmental exposure to chemicals associated with unconventional oil and gas extraction alters immune homeostasis and viral immunity of the amphibian xenopus.although aquatic vertebrates and humans are increasingly exposed to water pollutants associated with unconventional oil and gas extraction (uog), the long-term effects of these pollutants on immunity remains unclear. we have established the amphibian xenopus laevis and the ranavirus frog virus 3 (fv3) as a reliable and sensitive model for evaluating the effects of waterborne pollutants. x. laevis tadpoles were exposed to a mixture of equimass amount of uog chemicals with endocrine disrupting act ...201930939317
developmental regulation of wnt signaling by nagk and the udp-glcnac salvage pathway.in a screen for human kinases that regulate xenopus laevis embryogenesis, we identified nagk and other components of the udp-glcnac glycosylation salvage pathway as regulators of anteroposterior patterning and wnt signaling. we find that the salvage pathway does not affect other major embryonic signaling pathways (fgf, tgfβ, notch, or shh), thereby demonstrating specificity for wnt signaling. we show that the role of the salvage pathway in wnt signaling is evolutionarily conserved in zebrafish a ...201930904594
stage-dependent cardiac regeneration in xenopus is regulated by thyroid hormone availability.despite therapeutic advances, heart failure is the major cause of morbidity and mortality worldwide, but why cardiac regenerative capacity is lost in adult humans remains an enigma. cardiac regenerative capacity widely varies across vertebrates. zebrafish and newt hearts regenerate throughout life. in mice, this ability is lost in the first postnatal week, a period physiologically similar to thyroid hormone (th)-regulated metamorphosis in anuran amphibians. we thus assessed heart regeneration in ...201930755533
ketone body modulation of ligand-gated ion channels.ketogenesis is a metabolic process wherein ketone bodies are produced from the breakdown of fatty acids. in humans, fatty acid catabolism results in the production of acetyl-coa which can then be used to synthesize three ketone bodies: acetoacetate, acetone, and β-hydroxybutyrate. ketogenesis occurs at a higher rate in situations of low blood glucose, such as during fasting, heavy alcohol consumption, and in situations of low insulin, as well as in individuals who follow a 'ketogenic diet' consi ...201930562540
loc496300 is expressed in the endoderm of developing xenopus laevis embryos. 201932550462
using hdr and a template to introduce an in-frame ha tag on the 3' end of the xenopus laevis gata2.l open reading frame. 201932550411
evaluating potential distribution of high-risk aquatic invasive species in the water garden and aquarium trade at a global scale based on current established populations.aquatic non-native invasive species are commonly traded in the worldwide water garden and aquarium markets, and some of these species pose major threats to the economy, the environment, and human health. understanding the potential suitable habitat for these species at a global scale and at regional scales can inform risk assessments and predict future potential establishment. typically, global habitat suitability models are fit for freshwater species with only climate variables, which provides ...201930428498
the role of ambient temperature and body mass on body temperature, standard metabolic rate and evaporative water loss in southern african anurans of different habitat specialisation.temperature and water availability are two of the most important variables affecting all aspects of an anuran's key physiological processes such as body temperature (tb), evaporative water loss (ewl) and standard metabolic rate (smr). since anurans display pronounced sexual dimorphism, evidence suggests that these processes are further influenced by other factors such as vapour pressure deficit (vpd), sex and body mass (mb). however, a limited number of studies have tested the generality of thes ...201931660269
lissamphibian limbs and the origins of tetrapod hox domains.the expression and function of hox genes have played a key role in the debate on the evolution of limbs from fins. as an early branching tetrapod lineage, lissamphibians may provide information on the origin of the limb's hox domains and particularly how the plesiomorphic tetrapod pattern compares to the hox pattern present in fish fins. here, we comparatively investigated the expression of hox genes in the developing limbs of axolotl and xenopus laevis as well as in the fins of the direct devel ...201931445923
broad applicability of a streamlined ethyl cinnamate-based clearing procedure.turbidity and opaqueness are inherent properties of tissues that limit the capacity to acquire microscopic images through large tissues. creating a uniform refractive index, known as tissue clearing, overcomes most of these issues. these methods have enabled researchers to image large and complex 3d structures with unprecedented depth and resolution. however, tissue clearing has been adopted to a limited extent due to a combination of cost, time, complexity of existing methods and potential nega ...201930665888
preventing ethanol-induced brain and eye morphology defects using optogenetics.background: embryonic exposure to the teratogen ethanol leads to dysmorphias, including eye and brain morphology defects associated with fetal alcohol spectrum disorder (fasd). exposure of xenopus laevis embryos to ethanol leads to similar developmental defects, including brain and eye dysmorphism, confirming our work and the work of others showing xenopus as a useful system for studies of the brain and eye birth defects associated with fasd. several targets of ethanol action have been hypothesi ...201932685918
myelopoiesis of the amphibian xenopus laevis is segregated to the bone marrow, away from their hematopoietic peripheral liver.across vertebrates, hematopoiesis takes place within designated tissues, wherein committed myeloid progenitors further differentiate toward cells with megakaryocyte/erythroid potential (mep) or those with granulocyte/macrophage potential (gmp). while the liver periphery (lp) of the xenopus laevis amphibian functions as a principal site of hematopoiesis and contains meps, cells with gmp potential are instead segregated to the bone marrow (bm) of this animal. presently, using gene expression and w ...201932038608
antiarrhythmic properties of ranolazine: inhibition of atrial fibrillation associated task-1 potassium channels.background: atrial fibrillation (af) is the most common sustained cardiac arrhythmia and one of the major causes of cardiovascular morbidity and mortality. despite good progress within the past years, safe and effective treatment of af remains an unmet clinical need. the anti-anginal agent ranolazine has been shown to exhibit antiarrhythmic properties via mainly late ina and ikr blockade. this results in prolongation of the atrial action potential duration (apd) and effective refractory period ( ...201932038227
fluorescence lifetime imaging reveals heterogeneous functional distribution of egfp expressed in xenopus oocytes.the oocytes from xenopus laevis are well known for their polarity, presenting a distinct animal and vegetal pole. other heterogeneities are less known. to study the heterogeneity of the xenopus oocyte, we expressed egfp and analyzed the protein distribution with fluorescence lifetime microscopy. the vegetal pole exhibited higher levels of fluorescence, than the animal pole. however, the fluorescence lifetimes between the two areas were indistinguishable, suggesting similar environments. in contr ...201931658452
nutrient restriction causes reversible g2 arrest in xenopus neural progenitors.nutrient status affects brain development; however, the effects of nutrient availability on neural progenitor cell proliferation in vivo are poorly understood. without food, xenopus laevis tadpoles enter a period of stasis during which neural progenitor proliferation is drastically reduced, but resumes when food becomes available. here, we investigate how neural progenitors halt cell division in response to nutrient restriction and subsequently re-enter the cell cycle upon feeding. we demonstrat ...201931649012
bioinformatics screening of genes specific for well-regenerating vertebrates reveals c-answer, a regulator of brain development and regeneration.the molecular basis of higher regenerative capacity of cold-blooded animals comparing to warm-blooded ones is poorly understood. although this difference in regenerative capacities is commonly thought to be a result of restructuring of the same regulatory gene network, we hypothesized that it may be due to loss of some genes essential for regeneration. we describe here a bioinformatic method that allowed us to identify such genes. for investigation in depth we selected one of them encoding trans ...201931644900
azi-medetomidine: synthesis and characterization of a novel α2 adrenergic photoaffinity ligand.agonists at the α2 adrenergic receptor produce sedation, increase focus, provide analgesia, and induce centrally mediated hypotension and bradycardia, yet neither their dynamic interactions with adrenergic receptors nor their modulation of neuronal circuit activity is completely understood. photoaffinity ligands of α2 adrenergic agonists have the potential both to capture discrete moments of ligand-receptor interactions and to prolong naturalistic drug effects in discrete regions of tissue in vi ...201931638765
nucleoplasmin is a limiting component in the scaling of nuclear size with cytoplasmic volume.how nuclear size is regulated relative to cell size is a fundamental cell biological question. reductions in both cell and nuclear sizes during xenopus laevis embryogenesis provide a robust scaling system to study mechanisms of nuclear size regulation. to test if the volume of embryonic cytoplasm is limiting for nuclear growth, we encapsulated gastrula-stage embryonic cytoplasm and nuclei in droplets of defined volume using microfluidics. nuclei grew and reached new steady-state sizes as a funct ...201931636119
n-glycosylation of trek-1/hk2p2.1 two-pore-domain potassium (k2p) channels.mechanosensitive htrek-1 two-pore-domain potassium (hk2p2.1) channels give rise to background currents that control cellular excitability. recently, trek-1 currents have been linked to the regulation of cardiac rhythm as well as to hypertrophy and fibrosis. even though the pharmacological and biophysical characteristics of htrek-1 channels have been widely studied, relatively little is known about their posttranslational modifications. this study aimed to evaluate whether htrek-1 channels are n- ...201931635148
an optimized screen reduces the number of ga transporters and provides insights into nitrate transporter 1/peptide transporter family substrate determinants.based on recent in vitro data, a relatively large number of the plant nitrate transporter 1/peptide transporter family (npf) proteins have been suggested to function as gibberellic acid (ga) transporters. most ga transporting npf proteins also appear to transport other structurally unrelated phytohormones or metabolites. several of the gas used in previous in vitro assays are membrane permeable weak organic acids whose movement across membranes are influenced by the ph-sensitive ion-trap mechani ...201931632416
kif2a scales meiotic spindle size in hymenochirus boettgeri.size is a fundamental feature of biological systems that affects physiology at all levels. for example, the dynamic, microtubule-based spindle that mediates chromosome segregation scales to a wide range of cell sizes across different organisms and cell types. xenopus frog species possess a variety of egg and meiotic spindle sizes, and differences in activities or levels of microtubule-associated proteins in the egg cytoplasm between xenopus laevis and xenopus tropicalis have been shown to accoun ...201931630945
repression of inappropriate gene expression in the vertebrate embryonic ectoderm.during vertebrate embryogenesis, precise regulation of gene expression is crucial for proper cell fate determination. much of what we know about vertebrate development has been gleaned from experiments performed on embryos of the amphibian xenopus laevis; this review will focus primarily on studies of this model organism. an early critical step during vertebrate development is the formation of the three primary germ layers-ectoderm, mesoderm, and endoderm-which emerge during the process of gastr ...201931698780
cell type-specific transcriptome analysis unveils secreted signaling molecule genes expressed in apical epithelial cap during appendage regeneration.wound epidermis (we) and the apical epithelial cap (aec) are believed to trigger regeneration of amputated appendages such as limb and tail in amphibians by producing certain secreted signaling molecules. to date, however, only limited information about the molecular signatures of these epidermal structures is available. here we used a transgenic xenopus laevis line harboring the enhanced green fluorescent protein (egfp) gene under control of an es1 gene regulatory sequence to isolate we/aec cel ...201931713234
in vitro modeling of batrachochytrium dendrobatidis infection of the amphibian skin.the largest current disease-induced loss of vertebrate biodiversity is due to chytridiomycosis and despite the increasing understanding of the pathogenesis, knowledge unravelling the early host-pathogen interactions remains limited. batrachochytrium dendrobatidis (bd) zoospores attach to and invade the amphibian epidermis, with subsequent invasive growth in the host skin. availability of an in vitro assay would facilitate in depth study of this interaction while reducing the number of experiment ...201931725762
overexpression of ataap1 increased the uptake of an alanine-chlorantraniliprole conjugate in arabidopsis thaliana.transporters play an important role in the uptake and redistribution of agrochemicals to the site of insect feeding. the product of the arabidopsis thaliana gene ataap1 substantially contributes to inorganic nitrogen acquisition under ecologically relevant amino acid concentrations. here, the transporter ability of ataap1 to a chlorantraniliprole-alanine conjugate (cap-ala-1) was tested both in planta and in vitro. thirty-day-old and 15-day-old plants overexpressing ataap1 increased the uptake o ...201931741272
a prototype of the mammalian sulfotransferase 1 (sult1) family in xenopus laevis: molecular and enzymatic properties of xlsult1b.s.the cytosolic sulfotransferase 1 (sult1) proteins are a family of highly divergent proteins that show variable expansion in different species during vertebrate evolution. to clarify the evolutionary origin of the mammalian lineage of the sult1 family, we compiled xenopus laevis and x. tropicalis sult1 (xsult1) sequences from public databases. the xsult1 family was found to comprise at least six subfamilies, which corresponded in part to five mammalian sult1 subfamilies but only poorly to zebrafi ...201931748465
the chalcone lonchocarpin inhibits wnt/β-catenin signaling and suppresses colorectal cancer proliferation.the deregulation of the wnt/β-catenin signaling pathway is a central event in colorectal cancer progression, thus a promising target for drug development. many natural compounds, such as flavonoids, have been described as wnt/β-catenin inhibitors and consequently modulate important biological processes like inflammation, redox balance, cancer promotion and progress, as well as cancer cell death. in this context, we identified the chalcone lonchocarpin isolated from lonchocarpus sericeus as a wnt ...201931817828
optimized photo-stimulation of halorhodopsin for long-term neuronal inhibition.optogenetic silencing techniques have expanded the causal understanding of the functions of diverse neuronal cell types in both the healthy and diseased brain. a widely used inhibitory optogenetic actuator is enphr3.0, an improved version of the light-driven chloride pump halorhodopsin derived from natronomonas pharaonis. a major drawback of enphr3.0 is related to its pronounced inactivation on a time-scale of seconds, which renders it unsuited for applications that require long-lasting silencin ...201931775747
the tff peptides xp1 and xp4 appear in distinctive forms in the xenopus laevis gastric mucosa: indications for different protective functions.the gastric secretory trefoil factor family (tff) peptides xp1 and xp4 are the xenopus laevis orthologs of mammalian tff1 and tff2, respectively. the aim of this study was to analyze the molecular forms of xp1 and xp4 in the x. laevis gastric mucosa by fplc. xp1 mainly occurred in a monomeric low-molecular-mass form and only a minor subset is associated with the mucus fraction. the occurrence of monomeric xp1 is unexpected because of its odd number of cysteine residues. probably a conserved acid ...201931801293
mathematical model explaining the role of cdc6 in the diauxic growth of cdk1 activity during the m-phase of the cell cycle.in this paper we propose a role for the cdc 6 protein in the entry of cells into mitosis. this has not been considered in the literature so far. recent experiments suggest that cdc 6 , upon entry into mitosis, inhibits the appearance of active cdk 1 and cyclin b complexes. this paper proposes a mathematical model which incorporates the dynamics of kinase cdk 1 , its regulatory protein cyclin b, the regulatory phosphatase cdc 25 and the inhibitor cdc 6 known to be involved in the regulation of ac ...201931795221
characterization of spinal cord damage based on automatic video analysis of froglet swimming.xenopus laevis frogs are a widely used organism to study aspects of modern biology ( harland and grainger, 2011). its central nervous system is particularly interesting, because in certain stages of metamorphosis the spinal cord can regenerate after injury and recover swimming. with this in mind, automatic gait analysis could help evaluate the regenerative performance by means of a method that automatically and quantitatively establishes the degree in froglets' limb movement. here, we present an ...201931852668
expression and ion transport activity of rice oshkt1;1 variants.oshkt1;1 in rice, belongs to the high-affinity k+ transporter family, has been found to be involved in salt tolerance. oshkt1;1 in japonica rice (nipponbare) produces mrna variants, but their functions remain elusive. in salt tolerant rice, pokkali, eight oshkt1;1 variants (v1-v8) were identified in addition to the full-length oshkt1;1 (fl) cdna. absolute quantification by qpcr revealed that accumulation of oshkt1;1-fl mrna is minor in contrast to that of oshkt1;1-v1, -v2, -v4, and -v7 mrnas, al ...201931877741
a novel calcium-activated potassium channel controls membrane potential and intracellular ph in trypanosoma cruzi.trypanosoma cruzi develops in environments where nutrient availability, osmolarity, ionic concentrations, and ph undergo significant changes. the ability to adapt and respond to such conditions determines the survival and successful transmission of t. cruzi. ion channels play fundamental roles in controlling physiological parameters that ensure cell homeostasis by rapidly triggering compensatory mechanisms. combining molecular, cellular and electrophysiological approaches we have identified and ...201932010643
prominin-1 and photoreceptor cadherin localization in xenopus laevis: protein-protein relationships and function.retinal degenerative diseases are genetically diverse and rare inherited disorders that cause the death of rod and cone photoreceptors, resulting in progressive vision loss and blindness. this review will focus on two retinal degeneration-causing genes: prominin-1 (prom1) and photoreceptor cadherin (prcad). we will discuss protein localization, potential roles in photoreceptor outer segment disc morphogenesis, and areas for future investigation.201931884658
autophagy induction by hdac inhibitors is unlikely to be the mechanism of efficacy in prevention of retinal degeneration caused by p23h rhodopsin.we previously found that valproic acid (vpa) and other histone deacetylase inhibitors (hdacis) ameliorate retinal degeneration (rd) caused by p23h rhodopsin in xenopus laevis larvae and hypothesized that this may be due to enhancement of autophagy. here we use x. laevis expressing an autophagy marker to assess effects of hdacis on autophagy. we also assess the effects of non-hdaci activators and inducers of autophagy on rd caused by p23h rhodopsin.201931884645
the peptide transporter 1a of the zebrafish danio rerio, an emerging model in nutrigenomics and nutrition research: molecular characterization, functional properties, and expression analysis.peptide transporter 1 (pept1, alias slc15a1) mediates the uptake of dietary di/tripeptides in all vertebrates. however, in teleost fish, more than one pept1-type transporter might function, due to specific whole genome duplication event(s) that occurred during their evolution leading to a more complex paralogue gene repertoire than in higher vertebrates (tetrapods).201931890051
heterologous expression of aedes aegypti cation chloride cotransporter 2 (aeccc2) in xenopus laevis oocytes induces an enigmatic na⁺/li⁺ conductance.the yellow fever mosquito aedes aegypti possesses three genes encoding putative na⁺-coupled cation chloride cotransporters (cccs): aenkcc1, aeccc2, and aeccc3. to date, none of the aecccs have been functionally characterized. here we expressed aeccc2 heterologously in xenopus oocytes and measured the uptake of li⁺ (a tracer for na⁺) and rb⁺ (a tracer for k⁺). compared to control (h₂o-injected) oocytes, the aeccc2-expressing oocytes exhibited significantly greater uptake of li⁺, but not rb⁺. howe ...201930875796
the effects of insecticides on two splice variants of the glutamate-gated chloride channel receptor of the major malaria vector, anopheles gambiae.between half to 1 million people die annually from malaria. anopheles gambiae mosquitoes are major malaria vectors. unfortunately, resistance has emerged to the agents currently used to control a. gambiae, creating a demand for novel control measures. the pentameric glutamate-gated chloride channel (glucl) expressed in the muscle and nerve cells of these organisms are a potentially important biological target for malaria control. the pharmacological properties of anophiline glucl receptors are, ...201931479507
divergent axial morphogenesis and earlyshhexpression in vertebrate prospective floor plate.the notochord has organizer properties and is required for floor plate induction and dorsoventral patterning of the neural tube. this activity has been attributed to sonic hedgehog (shh) signaling, which originates in the notochord, forms a gradient, and autoinducesshhexpression in the floor plate. however, reported data are inconsistent and the spatiotemporal development of the relevantshhexpression domains has not been studied in detail. we therefore studied the expression dynamics ofshhin rab ...201829423139
cloning and spatiotemporal expression of xenopus laevis apolipoprotein ci.apolipoprotein ci (apoci) belongs to the apolipoprotein superfamily, members of which are involved in lipid transport, uptake and homeostasis. excessive apoci has been implicated in atherosclerosis and alzheimer's disease in humans. in this study we report the isolation of xenopus laevis apoci and describe the expression pattern of this gene during early development, using reverse transcription polymerase chain reaction and whole mount in situ hybridization. xenopus apoci is enriched in the dors ...201829346450
trrap is a central regulator of human multiciliated cell formation.the multiciliated cell (mcc) is an evolutionarily conserved cell type, which in vertebrates functions to promote directional fluid flow across epithelial tissues. in the conducting airway, mccs are generated by basal stem/progenitor cells and act in concert with secretory cells to perform mucociliary clearance to expel pathogens from the lung. studies in multiple systems, includingxenopus laevisepidermis, murine trachea, and zebrafish kidney, have uncovered a transcriptional network that regulat ...201829588376
embryonic lethality is not sufficient to explain hourglass-like conservation of vertebrate embryos.understanding the general trends in developmental changes during animal evolution, which are often associated with morphological diversification, has long been a central issue in evolutionary developmental biology. recent comparative transcriptomic studies revealed that gene expression profiles of mid-embryonic period tend to be more evolutionarily conserved than those in earlier or later periods. while the hourglass-like divergence of developmental processes has been demonstrated in a variety o ...201829568479
Refresh
firstprev
12345678910...
nextlast
Displaying items 501 - 600 of 17138