Search results for "mutation."
showing 10 items of 2808 documents
A Red Eye Colour Mutation in Culex pipiens after X-irradiation
1963
FOUR 1–2-day-old males of Culex pipiens were irradiated with a dose of 4,000 r. The mutant ‘red eye’ (r) was isolated from F3 cultures of two of the irradiated males (♂ II and ♂ IV). From male II, there were three red-eyed females which arose out of a single F2 brother–sister mating; from male IV, 80 red-eyed females and one red-eyed male from 14 F2 brother–sister matings. According to the experimental procedure, this means that at least one sperm from male II and at least fourteen sperms from male IV carried the mutation r. Thus, the same mutation was recovered in parallel from two irradiated males. The clustered appearance of the mutation in male IV was presumably caused by the occurrence…
Recapitulating thyroid cancer histotypes through engineering embryonic stem cells
2023
AbstractThyroid carcinoma (TC) is the most common malignancy of endocrine organs. The cell subpopulation in the lineage hierarchy that serves as cell of origin for the different TC histotypes is unknown. Human embryonic stem cells (hESCs) with appropriate in vitro stimulation undergo sequential differentiation into thyroid progenitor cells (TPCs-day 22), which maturate into thyrocytes (day 30). Here, we create follicular cell-derived TCs of all the different histotypes based on specific genomic alterations delivered by CRISPR-Cas9 in hESC-derived TPCs. Specifically, TPCs harboring BRAFV600E or NRASQ61R mutations generate papillary or follicular TC, respectively, whereas addition of TP53R248…
Preneoplastic somatic mutations including MYD88(L265P) in lymphoplasmacytic lymphoma
2022
Normal cell counterparts of solid and myeloid tumors accumulate mutations years before disease onset; whether this occurs in B lymphocytes before lymphoma remains uncertain. We sequenced multiple stages of the B lineage in elderly individuals and patients with lymphoplasmacytic lymphoma, a singular disease for studying lymphomagenesis because of the high prevalence of mutated MYD88 . We observed similar accumulation of random mutations in B lineages from both cohorts and unexpectedly found MYD88 L265P in normal precursor and mature B lymphocytes from patients with lymphoma. We uncovered genetic and transcriptional pathways driving malignant transformation and leveraged these to model lymph…
A Multivariate Analysis on Non-nucleoside HIV-1 Reverse Transcriptase Inhibitors and Resistance Induced by Mutation
2003
This paper describes the use of multivariate statistical procedure PCA as a tool to explore the inhibitory activity of classes of NNRTIs against HIV-1 viruses (wild type and more frequent mutants, Y181C, V106A, K103N, L100I) and against RT enzyme. The analysis of correlations between biological activity and molecular descriptors or similarity indexes allowed a reliable classification of the fifty five derivatives considered in this study. The best results were obtained in the case of L100I and K103N mutants for which the higher number of assignments was found when the principal components derived from the descriptors were used. On this basis this statistical approach is proposed as a reliab…
Protein aggregate myopathies.
2006
Protein aggregate myopathies (PAMs) based on the morphologic phenomenon of aggregation of proteins within muscle fibers may occur in children (selenoproteinopathies, actinopathies, and myosinopathies) or adults (certain myofibrillar myopathies and myosinopathies). They may be mutation related, which includes virtually all childhood forms but certain other forms as well, or sporadic, which are largely seen in adults. Their classification as myofibrillar or desmin-related myopathies, actinopathies, or myosinopathies is based on the identification of respective mutant proteins, most of them components of the sarcomeres. Recognition of PAM requires muscle biopsy and an extensive immunohistochem…
The phosphorylated pathway of serine biosynthesis is essential both for male gametophyte and embryo development and for root growth in Arabidopsis.
2013
This study characterizes the phosphorylated pathway of Ser biosynthesis (PPSB) in Arabidopsis thaliana by targeting phosphoserine phosphatase (PSP1), the last enzyme of the pathway. Lack of PSP1 activity delayed embryo development, leading to aborted embryos that could be classified as early curled cotyledons. The embryo-lethal phenotype of psp1 mutants could be complemented with PSP1 cDNA under the control of Pro35S (Pro35S:PSP1). However, this construct, which was poorly expressed in the anther tapetum, did not complement mutant fertility. Microspore development in psp1.1/psp1.1 Pro35S:PSP1 arrested at the polarized stage. The tapetum from these lines displayed delayed and irregular devel…
Variability in the cadherin gene in an Ostrinia nubilalis strain selected for Cry1Ab resistance
2008
Transgenic corn expressing Cry1Ab (a Bacillus thuringiensis toxin) is highly effective in the control of Ostrinia nubilalis. For its toxic action, Cry1Ab has to bind to specific insect midgut proteins. To date, in three Lepidoptera species resistance to a Cry1A toxin has been conferred by mutations in cadherin, a protein of the Lepidoptera midgut membrane. The implication of cadherin in the resistance of an Ostrinia nubilalis colony (Europe-R) selected with Bacillus thuringiensis Cry1Ab protoxin was investigated. Several major mutations in the cadherin (cdh) gene were found, which introduced premature termination codons and/or large deletions (ranging from 1383 to 1701bp). The contribution …
Coordinate overexpression of two RND efflux systems, ParXY and TtgABC , is responsible for multidrug resistance in Pseudomonas putida
2020
Resistance Nodulation cell Division (RND) efflux pumps are known to contribute to the tolerance of Pseudomonas putida to aromatic hydrocarbons, but their role in antibiotic resistance has not been fully elucidated. In this study, two types of single-step multidrug-resistant (MDR) mutants were selected in vitro from reference strain KT2440. Mutants of the first type were more resistant to fluoroquinolones and β-lactams except imipenem, and overproduced the efflux system TtgABC as a result of mutations occurring in regulator TtgR. In addition to TtgABC, mutants of the second type such as HPG-5 were found to upregulate a novel RND pump, dubbed ParXY/TtgC, which accommodates cefepim, fluoroquin…
LisRK is required for optimal fitness ofListeria monocytogenesin soil
2020
ABSTRACTListeria monocytogenes is a food-borne pathogen responsible for the disease listeriosis. It is ubiquitously found in the environment and soil is one of its natural habitats. Listeria monocytogenes is highly capable of coping with various stressful conditions. We hypothesized that stress-responsive two-component systems such as LisRK might contribute to the adaptation of L. monocytogenes to the soil environment. Indeed, investigations of the population dynamics of wild-type and mutant strains suggest an important role of LisRK for optimal fitness of L. monocytogenes in sterile soil. Results from non-sterile soil showed that the parental strain was capable of surviving longer than mut…
Mutants of Saccharomyces cerevisiae cell division cycle defective in cytokinesis. Biosynthesis of the cell wall and morphology
1982
The four temperature-sensitive mutants of Saccharomyces cerevisiae in the cell division cycle defective in cytokinesis (cdc, 3, 10, 11 and 12), have been analyzed with respect to the biosynthesis of the cell wall polymers. After 3 hours of incubation at the non-permissive temperature (37 degrees C) these strains stop growing. The synthesis of glucan, mannan and chitin (wall polymers) level off in a similar time, but glucan, mannan and chitin synthases remained active for at least 4 hours. If the mutants are analyzed by transmission and scanning electron microscopy different pictures emerge. Two of the mutants cdc 10 and cdc 12, after 3 hours of incubation at 37 degrees C present apparently …