scholarly journals Characterization of a hypercontraction-induced myopathy in Drosophila caused by mutations in Mhc

2004 ◽  
Vol 164 (7) ◽  
pp. 1045-1054 ◽  
Author(s):  
Enrico S. Montana ◽  
J. Troy Littleton
Keyword(s):  
Troponin I ◽  
Troponin T ◽  
Single Point ◽  
Point Mutations ◽  
Temperature Sensitive ◽  
Giant Fiber ◽  
Neuronal Stimulation ◽  
Mhc Locus ◽  
Mhc Alleles

The Myosin heavy chain (Mhc) locus encodes the muscle-specific motor mediating contraction in Drosophila. In a screen for temperature-sensitive behavioral mutants, we have identified two dominant Mhc alleles that lead to a hypercontraction-induced myopathy. These mutants are caused by single point mutations in the ATP binding/hydrolysis domain of Mhc and lead to degeneration of the flight muscles. Electrophysiological analysis in the adult giant fiber flight circuit demonstrates temperature-dependent seizure activity that requires neuronal input, as genetic blockage of neuronal activity suppresses the electrophysiological seizure defects. Intracellular recordings at the third instar neuromuscular junction show spontaneous muscle movements in the absence of neuronal stimulation and extracellular Ca2+, suggesting a dysregulation of intracellular calcium homeostasis within the muscle or an alteration of the Ca2+ dependence of contraction. Characterization of these new Mhc alleles suggests that hypercontraction occurs via a mechanism, which is molecularly distinct from mutants identified previously in troponin I and troponin T.

scholarly journals First Characterization of Fluoroquinolone Resistance in Streptococcus suis

2006 ◽  
Vol 51 (2) ◽  
pp. 777-782 ◽  
Author(s):  
Jose Antonio Escudero ◽  
Alvaro San Millan ◽  
Ana Catalan ◽  
Adela G. de la Campa ◽  
Estefania Rivero ◽  
...  
Keyword(s):  
Horizontal Gene Transfer ◽  
Single Point ◽  
Point Mutations ◽  
Streptococcus Suis ◽  
Fluoroquinolone Resistance ◽  
Genes Encoding ◽  
Resistant Strains ◽  
Single Point Mutations ◽  
Clonal Spread

ABSTRACT We have identified and sequenced the genes encoding the quinolone-resistance determining region (QRDR) of ParC and GyrA in fluoroquinolone-susceptible and -resistant Streptococcus suis clinical isolates. Resistance is the consequence of single point mutations in the QRDRs of ParC and GyrA and is not due to clonal spread of resistant strains or horizontal gene transfer with other bacteria.

scholarly journals Molecular Basis of Resistance to Selected Antimicrobial Agents in the Emerging Zoonotic Pathogen Streptococcus suis

2015 ◽  
Vol 53 (7) ◽  
pp. 2332-2336 ◽  
Author(s):  
Mamata Gurung ◽  
Migma Dorji Tamang ◽  
Dong Chan Moon ◽  
Su-Ran Kim ◽  
Jin-Ha Jeong ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Antimicrobial Agents ◽  
Single Point ◽  
Point Mutations ◽  
Streptococcus Suis ◽  
Quinolone Resistance ◽  
Content Type ◽  
Zoonotic Pathogen ◽  
Single Point Mutations

Characterization of 227Streptococcus suisstrains isolated from pigs during 2010 to 2013 showed high levels of resistance to clindamycin (95.6%), tilmicosin (94.7%), tylosin (93.8%), oxytetracycline (89.4%), chlortetracycline (86.8%), tiamulin (72.7%), neomycin (70.0%), enrofloxacin (56.4%), penicillin (56.4%), ceftiofur (55.9%), and gentamicin (55.1%). Resistance to tetracyclines, macrolides, aminoglycosides, and fluoroquinolone was attributed to thetetgene,erm(B),erm(C),mph(C), andmef(A) and/ormef(E) genes,aph(3′)-IIIaandaac(6′)-Ie-aph(2″)-Iagenes, and single point mutations in the quinolone resistance-determining region of ParC and GyrA, respectively.

scholarly journals Characterization of a Lineage C.36 SARS-CoV-2 Isolate with Reduced Susceptibility to Neutralization Circulating in Lombardy, Italy

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1514
Author(s):  
Matteo Castelli ◽  
Andreina Baj ◽  
Elena Criscuolo ◽  
Roberto Ferrarese ◽  
Roberta A. Diotti ◽  
...  
Keyword(s):  
Molecular Characterization ◽  
Single Point ◽  
Point Mutations ◽  
Humoral Response ◽  
Genomic Sequencing ◽  
Single Point Mutations

SARS-CoV-2 spike is evolving to maximize transmissibility and evade the humoral response. The massive genomic sequencing of SARS-CoV-2 isolates has led to the identification of single-point mutations and deletions, often having the recurrence of hotspots, associated with advantageous phenotypes. We report the isolation and molecular characterization of a SARS-CoV-2 strain, belonging to a lineage (C.36) not previously associated with concerning traits, which shows decreased susceptibility to vaccine sera neutralization.

scholarly journals Two Distinct Regions in a Yeast Myosin-V Tail Domain Are Required for the Movement of Different Cargoes

2000 ◽  
Vol 150 (3) ◽  
pp. 513-526 ◽  
Author(s):  
Natalie L. Catlett ◽  
Jason E. Duex ◽  
Fusheng Tang ◽  
Lois S. Weisman
Keyword(s):  
Amino Acids ◽  
Single Point ◽  
Point Mutations ◽  
Random Mutagenesis ◽  
Secretory Vesicles ◽  
Polarized Growth ◽  
Tail Domain ◽  
Myosin V ◽  
Vacuole Inheritance

The Saccharomyces cerevisiae myosin-V, Myo2p, is essential for polarized growth, most likely through transport of secretory vesicles to the developing bud. Myo2p is also required for vacuole movement, a process not essential for growth. The globular region of the myosin-V COOH-terminal tail domain is proposed to bind cargo. Through random mutagenesis of this globular tail, we isolated six new single point mutants defective in vacuole inheritance, but not polarized growth. These point mutations cluster to four amino acids in an 11-amino acid span, suggesting that this region is important for vacuole movement. In addition, through characterization of myo2-ΔAflII, a deletion of amino acids 1,459–1,491, we identified a second region of the globular tail specifically required for polarized growth. Whereas this mutant does not support growth, it complements the vacuole inheritance defect in myo2-2 (G1248D) cells. Moreover, overexpression of the myo2-ΔAflII globular tail interferes with vacuole movement, but not polarized growth. These data indicate that this second region is dispensable for vacuole movement. The identification of these distinct subdomains in the cargo-binding domain suggests how myosin-Vs can move multiple cargoes. Moreover, these studies suggest that the vacuole receptor for Myo2p differs from the receptor for the essential cargo.

scholarly journals A High-Enrollment Course-Based Undergraduate Research Experience Improves Student Conceptions of Scientific Thinking and Ability to Interpret Data

2015 ◽  
Vol 14 (2) ◽  
pp. ar21 ◽  
Author(s):  
Sara E. Brownell ◽  
Daria S. Hekmat-Scafe ◽  
Veena Singla ◽  
Patricia Chandler Seawell ◽  
Jamie F. Conklin Imam ◽  
...  
Keyword(s):  
Positive Impact ◽  
Undergraduate Research ◽  
Single Point ◽  
Point Mutations ◽  
Suppressor Gene ◽  
Scientific Thinking ◽  
Research Experience ◽  
Student Conceptions ◽  
Biology Students

We present an innovative course-based undergraduate research experience curriculum focused on the characterization of single point mutations in p53, a tumor suppressor gene that is mutated in more than 50% of human cancers. This course is required of all introductory biology students, so all biology majors engage in a research project as part of their training. Using a set of open-ended written prompts, we found that the course shifts student conceptions of what it means to think like a scientist from novice to more expert-like. Students at the end of the course identified experimental repetition, data analysis, and collaboration as important elements of thinking like a scientist. Course exams revealed that students showed gains in their ability to analyze and interpret data. These data indicate that this course-embedded research experience has a positive impact on the development of students’ conceptions and practice of scientific thinking.

Molecular characterization of GATA/GACA microsatellite repeats in tomato

Genome ◽  
1997 ◽  
Vol 40 (1) ◽  
pp. 25-33 ◽  
Author(s):  
B. Vosman ◽  
P. Arens
Keyword(s):  
Repetitive Dna ◽  
Cultivar Identification ◽  
Single Point ◽  
Point Mutations ◽  
Single Point Mutation ◽  
New Class ◽  
Microsatellite Repeats ◽  
Flanking Sequences ◽  
Simple Sequence

Microsatellite repeats like GATA or GACA display a degree of variability that allows their use in cultivar identification. Southern hybridization with oligonucleotide probes complementary to these microsatellites were used for the detection of polymorphisms. To understand the molecular structure of the detected DNA, fragments hybridizing to GATA and GACA probes were cloned and sequenced. In the four clones analyzed, repeats of GATA and GACA were found intertwined. The GATA and GACA arrays were not perfect but were heavily degenerated, in that they contained many tetranucleotides that might have been derived by a single point mutation from GATA or GACA. Some of these derived sequences, like GGTA and GGAT, were present as relatively long stretches that also contained some point mutations. This supports the hypothesis that long stretches of repeats are stabilized by the accumulation of point mutations. Analysis of the flanking sequences of the fragments obtained with the GACA probe showed that one of them was homologous to a Lilium henryi retrotransposon and the other to a sequence upstream of a potato patatin gene. The two fragments obtained using the GATA probe were flanked by DNA that had no homology to any known sequence but they were highly homologous to each other. This DNA was frequently associated with GATA elements and was present in the tomato genome in approximately 4300 copies. The function of this new class of repetitive DNA, here termed U30, is presently unknown.Key words: simple sequence repeats, Lycopersicon esculentum, cultivar identification, repetitive DNA.

scholarly journals Characterization of a novel large deletion and single point mutations in the BRCA1gene in a Greek cohort of families with suspected hereditary breast cancer

BMC Cancer ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Ioulia Belogianni ◽  
Angela Apessos ◽  
Markos Mihalatos ◽  
Evangelia Razi ◽  
Stefanos Labropoulos ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Hereditary Breast Cancer ◽  
Single Point ◽  
Point Mutations ◽  
Large Deletion ◽  
Single Point Mutations

scholarly journals Genetic characterization of the Saccharomyces cerevisiae translational initiation suppressors sui1, sui2 and SUI3 and their effects on HIS4 expression.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 483-495 ◽  
Author(s):  
B Castilho-Valavicius ◽  
H Yoon ◽  
T F Donahue
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Translation Initiation ◽  
Genetic Characterization ◽  
Point Mutations ◽  
Base Change ◽  
Temperature Sensitive ◽  
Mrna Levels ◽  
Translational Initiation ◽  
Initiator Codon

Abstract Saccharomyces cerevisiae strains containing mutations of the HIS4 translation initiation AUG codon were studied by reversion analysis in an attempt to identify components of the translation initiation complex that might participate in initiation site selection during the scanning process. The genetic characterization of these revertants identified three unlinked suppressor loci: SUI1, SUI2 and sui3, which when mutated restored the expression of the HIS4 allele despite the absence of the AUG initiator codon. Both sui1 and sui2 are recessive and cause temperature-sensitive growth on enriched medium. The temperature-sensitive phenotype and the ability to restore HIS4 expression associated with either sui1 or sui2 mutations cosegregate in crosses. SUI3 mutations are dominant and do not alter the thermal profile for growth. None of the mutations at the three loci suppresses known frameshift, missense or nonsense mutations. Each is capable of suppressing the nine different point mutations of the initiator codon at HIS4 or HIS4-lacZ as well as a two base change (ACC) and a three base deletion of the AUG codon, suggesting that the site of suppression resides outside the normal initiator region. sui1 and sui2 suppressor mutations were mapped to chromosomes XIV and X, respectively. Suppression by sui1, sui2 and SUI3 mutations results in 14-, 11- and 47-fold increases, respectively, relative to isogenic parent strains, in the expression of a HIS4 allele lacking the initiator AUG codon. Part of this increase in the HIS4 expression by sui2 and SUI3 can be attributed to increases of HIS4 mRNA levels, presumably mediated by perturbation of the general amino acid control system of yeast.

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