scholarly journals Direct Estimate of the Mutation Rate and the Distribution of Fitness Effects in the Yeast Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 441-452
Author(s):  
Dominika M Wloch ◽  
Krzysztof Szafraniec ◽  
Rhona H Borts ◽  
Ryszard Korona
Keyword(s):  
Spontaneous Mutation ◽  
Fruit Fly ◽  
Diploid Cell ◽  
Induced Mutations ◽  
Direct Estimate ◽  
Yeast Saccharomyces Cerevisiae ◽  
Related Trait ◽  
First Time ◽  
Defective Mismatch Repair

Abstract Estimates of the rate and frequency distribution of deleterious effects were obtained for the first time by direct scoring and characterization of individual mutations. This was achieved by applying tetrad analysis to a large number of yeast clones. The genomic rate of spontaneous mutation deleterious to a basic fitness-related trait, that of growth rate, was U = 1.1 × 10−3 per diploid cell division. Extrapolated to the fruit fly and humans, the per generation rate would be 0.074 and 0.92, respectively. This is likely to be an underestimate because single mutations with selection coefficients s < 0.01 could not be detected. The distribution of s ≥ 0.01 was studied both for spontaneous and induced mutations. The latter were induced by ethyl methanesulfonate (EMS) or resulted from defective mismatch repair. Lethal changes accounted for ~30–40% of the scored mutations. The mean s of nonlethal mutations was fairly high, but most frequently its value was between 0.01 and 0.05. Although the rate and distribution of very small effects could not be determined, the joint share of such mutations in decreasing average fitness was probably no larger than ~1%.

scholarly journals FRAMESHIFT SUPPRESSION IN SACCHAROMYCES CEREVISIAE. III. ISOLATION AND GENETIC PROPERTIES OF GROUP III SUPPRESSORS

Genetics ◽  
1980 ◽  
Vol 95 (4) ◽  
pp. 855-875 ◽  
Author(s):  
Claudia M Cummins ◽  
Richard F Gaber ◽  
Michael R Culbertson ◽  
Richard Mann ◽  
Gerald R Fink
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Induced Mutations ◽  
Yeast Saccharomyces Cerevisiae ◽  
Nonsense Mutations ◽  
Mapping Procedure ◽  
Group Iii ◽  
Frameshift Suppression ◽  
Group Ii ◽  
Chromosome Iii

ABSTRACT Suppressors of ICR-induced mutations that exhibit behavior similar to bacterial frameshift suppressors have been identified in the yeast Saccharomyces cerevisiae. The yeast suppressors have been divided into two groups. Previous evidence indicated that suppressors of one group (Group II: SUFI, SUF3, SUF4, SUF5 and SUF6) represent mutations in the structural genes for glycyl-tRNA's. Suppressors of the other group (Group III: SUF2 and SUF7) were less well characterized. Although they suppressed some ICR-revertible mutations, they failed to suppress Group II frameshift mutations. This communication provides a more thorough characterization of the Group III suppressors and describes the isolation and properties of four new suppressors in that group (SUF1, SUF9, SUF10 and suf11).—In our original study, Group III suppressors were isolated as revertants of the Group III mutations his4-712 and his4-713. All suppressors obtained as ICR-induced revertants of these mutations mapped at the SUF2 locus near the centromere of chromosome III. Suppressors mapping at other loci were obtained in this study by analyzing spontaneous and UV-induced revertants of the Group III mutations. SUF2 and SUF10 suppress both Group III his4 mutations, whereas SUF7, SUF8, SUF9 and suf11 suppress his4-713, but not his4-712. All of the suppressors except suf11 are dominant in diploids homozygous for his4-713. The suppressors fail to suppress representative UAA, UAG and UGA nonsense mutations.—SUP9 is linked to the centromere of chromosome VI, and SUF10 is linked to the centromere of chromosome XIV. A triploid mapping procedure was used to determine the chromosome locations of SUF7 and SUF8. Subsequent standard crosses revealed linkage of SUF7 to cdc5 on chromosome XIII and linkage of SUF8 to cdcl2 and pet3 on chromosome VIII.

TBE in Sweden

2020 ◽  
Keyword(s):  
Genetic Characterization ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Second Phase ◽  
Serum Samples ◽  
Tick Borne Encephalitis ◽  
Specific Immunoglobulin ◽  
Tick Borne Encephalitis Virus ◽  
First Time

Tick-borne encephalitis virus (TBEV) was isolated for the first time in Sweden in 1958 (from ticks and from 1 tick-borne encephalitis [TBE] patient).1 In 2003, Haglund and colleagues reported the isolation and antigenic and genetic characterization of 14 TBEV strains from Swedish patients (samples collected 1991–1994).2 The first serum sample, from which TBEV was isolated, was obtained 2–10 days after onset of disease and found to be negative for anti-TBEV immunoglobulin M (IgM) by enzyme-linked immunosorbent assay (ELISA), whereas TBEV-specific IgM (and TBEV-specific immunoglobulin G/cerebrospinal fluid [IgG/CSF] activity) was demonstrated in later serum samples taken during the second phase of the disease.

Chemical Constituents and Antibacterial Activity of Cissus Aralioides.

2020 ◽  
Vol 17 ◽  
Author(s):  
Balogun Olaoye Solomon ◽  
Ajayi Olukayode Solomon ◽  
Owolabi Temitayo Abidemi ◽  
Oladimeji Abdulkarbir Oladele ◽  
Liu Zhiqiang
Keyword(s):  
Plant Extract ◽  
Chemical Constituents ◽  
Ethyl Acetate Fraction ◽  
Antibacterial Activities ◽  
Sub Saharan Africa ◽  
Chromatographic Purification ◽  
Whole Plant ◽  
Sub Saharan ◽  
First Time

: Cissus aralioides is a medicinal plant used in sub-Saharan Africa for treatment of infectious diseases; however the chemical constituents of the plant have not been investigated. Thus, in this study, attempt was made at identifying predominant phytochemical constituents of the plant through chromatographic purification and silylation of the plant extract, and subsequent characterization using spectroscopic and GC-MS techniques. The minimum inhibitory concentration (MICs) for the antibacterial activities of the plant extract, chromatographic fractions and isolated compounds were also examined. Chromatographic purification of the ethyl acetate fraction from the whole plant afforded three compounds: β-sitosterol (1), stigmasterol (2) and friedelin (3). The phytosterols (1 and 2) were obtained together as a mixture. The GC-MS analysis of silylated extract indicated alcohols, fatty acids and sugars as predominant classes, with composition of 24.62, 36.90 and 26.52% respectively. Results of MICs indicated that friedelin and other chromatographic fractions had values (0.0626-1.0 mg/mL) comparable with the standard antibiotics used. Characterization of natural products from C. aralioides is being reported for the first time in this study.

Green Synthesis and Spectroscopic Studies of Ag-rGO Nanocomposites for Highly Selective Mercury (II) Sensing

2018 ◽  
Vol 9 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Shubhangi J. Mane-Gavade ◽  
Sandip R. Sabale ◽  
Xiao-Ying Yu ◽  
Gurunath H. Nikam ◽  
Bhaskar V. Tamhankar
Keyword(s):  
Green Synthesis ◽  
Color Change ◽  
Limit Of Detection ◽  
Aqueous Media ◽  
Suitable Condition ◽  
Cost Effective ◽  
Spectroscopic Studies ◽  
Calibration Plot ◽  
First Time

Introduction: Herein we report the green synthesis and characterization of silverreduced graphene oxide nanocomposites (Ag-rGO) using Acacia nilotica gum for the first time. Experimental: We demonstrate the Hg2+ ions sensing ability of the Ag-rGO nanocomposites form aqueous medium. The developed colorimetric sensor method is simple, fast and selective for the detection of Hg2+ ions in aqueous media in presence of other associated ions. A significant color change was noticed with naked eye upon Hg2+ addition. The color change was not observed for cations including Sr2+, Ni2+, Cd2+, Pb2+, Mg2+, Ca2+, Fe2+, Ba2+ and Mn2+indicating that only Hg2+ shows a strong interaction with Ag-rGO nanocomposites. Under the most suitable condition, the calibration plot (A0-A) against concentration of Hg2+ was linear in the range of 0.1-1.0 ppm with a correlation coefficient (R2) value 0.9998. Results & Conclusion The concentration of Hg2+ was quantitatively determined with the Limit of Detection (LOD) of 0.85 ppm. Also, this method shows excellent selectivity towards Hg2+ over nine other cations tested. Moreover, the method offers a new cost effective, rapid and simple approach for the detection of Hg2+ in water samples.

scholarly journals Waste-Based One-Part Alkali Activated Materials

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2911
Author(s):  
Margarida Gonçalves ◽  
Inês Silveirinha Vilarinho ◽  
Marinélia Capela ◽  
Ana Caetano ◽  
Rui Miguel Novais ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Microstructural Analysis ◽  
Construction Materials ◽  
Sodium Metasilicate ◽  
High Compressive Strength ◽  
Hardened State ◽  
First Time ◽  
Furnace Slag ◽  
Alkali Activated

Ordinary Portland Cement is the most widely used binder in the construction sector; however, a very high carbon footprint is associated with its production process. Consequently, more sustainable alternative construction materials are being investigated, namely, one-part alkali activated materials (AAMs). In this work, waste-based one-part AAMs binders were developed using only a blast furnace slag, as the solid precursor, and sodium metasilicate, as the solid activator. For the first time, mortars in which the commercial sand was replaced by two exhausted sands from biomass boilers (CA and CT) were developed. Firstly, the characterization of the slag and sands (aggregates) was performed. After, the AAMs fresh and hardened state properties were evaluated, being the characterization complemented by FTIR and microstructural analysis. The binder and the mortars prepared with commercial sand presented high compressive strength values after 28 days of curing-56 MPa and 79 MPa, respectively. The mortars developed with exhausted sands exhibit outstanding compressive strength values, 86 and 70 MPa for CT and CA, respectively, and the other material’s properties were not affected. Consequently, this work proved that high compressive strength waste-based one-part AAMs mortars can be produced and that it is feasible to use another waste as aggregate in the mortar’s formulations: the exhausted sands from biomass boilers.

scholarly journals Isolation and characterization of a new cold-active protease from psychrotrophic bacteria of Western Himalayan glacial soil

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saleem Farooq ◽  
Ruqeya Nazir ◽  
Shabir Ahmad Ganai ◽  
Bashir Ahmad Ganai
Keyword(s):  
Specific Activity ◽  
Temperature Range ◽  
Psychrotrophic Bacteria ◽  
Isolation And Characterization ◽  
Cold Active ◽  
Active Protease ◽  
Quantitative Screening ◽  
First Time ◽  
Low K

AbstractAs an approach to the exploration of cold-active enzymes, in this study, we isolated a cold-active protease produced by psychrotrophic bacteria from glacial soils of Thajwas Glacier, Himalayas. The isolated strain BO1, identified as Bacillus pumilus, grew well within a temperature range of 4–30 °C. After its qualitative and quantitative screening, the cold-active protease (Apr-BO1) was purified. The Apr-BO1 had a molecular mass of 38 kDa and showed maximum (37.02 U/mg) specific activity at 20 °C, with casein as substrate. It was stable and active between the temperature range of 5–35 °C and pH 6.0–12.0, with an optimum temperature of 20 °C at pH 9.0. The Apr-BO1 had low Km value of 1.0 mg/ml and Vmax 10.0 µmol/ml/min. Moreover, it displayed better tolerance to organic solvents, surfactants, metal ions and reducing agents than most alkaline proteases. The results exhibited that it effectively removed the stains even in a cold wash and could be considered a decent detergent additive. Furthermore, through protein modelling, the structure of this protease was generated from template, subtilisin E of Bacillus subtilis (PDB ID: 3WHI), and different methods checked its quality. For the first time, this study reported the protein sequence for psychrotrophic Apr-BO1 and brought forth its novelty among other cold-active proteases.

scholarly journals Synthesis and Characterization of Exopolysaccharide Encapsulated PCL/Gelatin Skin Substitute for Full-Thickness Wound Regeneration

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 854
Author(s):  
Ahmad Hivechi ◽  
Peiman Brouki Milan ◽  
Khashayar Modabberi ◽  
Moein Amoupour ◽  
Kaveh Ebrahimzadeh ◽  
...  
Keyword(s):  
Cell Activity ◽  
Average Diameter ◽  
Skin Substitute ◽  
Full Thickness ◽  
Skin Integrity ◽  
Hematoxylin And Eosin ◽  
First Time ◽  
Full Thickness Wound

Loss of skin integrity can lead to serious problems and even death. In this study, for the first time, the effect of exopolysaccharide (EPS) produced by cold-adapted yeast R. mucilaginosa sp. GUMS16 on a full-thickness wound in rats was evaluated. The GUMS16 strain’s EPS was precipitated by adding cold ethanol and then lyophilized. Afterward, the EPS with polycaprolactone (PCL) and gelatin was fabricated into nanofibers with two single-needle and double-needle procedures. The rats’ full-thickness wounds were treated with nanofibers and Hematoxylin and eosin (H&E) and Masson’s Trichrome staining was done for studying the wound healing in rats. Obtained results from SEM, DLS, FTIR, and TGA showed that EPS has a carbohydrate chemical structure with an average diameter of 40 nm. Cell viability assessments showed that the 2% EPS loaded sample exhibits the highest cell activity. Moreover, in vivo implantation of nanofiber webs on the full-thickness wound on rat models displayed a faster healing rate when EPS was loaded into a nanofiber. These results suggest that the produced EPS can be used for skin tissue engineering applications.

scholarly journals Morphological and Ultrastructural Characterization of Hemocytes in an Insect Model, the Hematophagous Dipetalogaster maxima (Hemiptera: Reduviidae)

Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 640
Author(s):  
Natalia R. Moyetta ◽  
Fabián O. Ramos ◽  
Jimena Leyria ◽  
Lilián E. Canavoso ◽  
Leonardo L. Fruttero
Keyword(s):  
Cell Biology ◽  
Cell Types ◽  
Transmission Electron ◽  
Ultrastructural Characterization ◽  
Current Classification ◽  
Contrast Microscopy ◽  
First Time ◽  
Controversial Aspect

Hemocytes, the cells present in the hemolymph of insects and other invertebrates, perform several physiological functions, including innate immunity. The current classification of hemocyte types is based mostly on morphological features; however, divergences have emerged among specialists in triatomines, the insect vectors of Chagas’ disease (Hemiptera: Reduviidae). Here, we have combined technical approaches in order to characterize the hemocytes from fifth instar nymphs of the triatomine Dipetalogaster maxima. Moreover, in this work we describe, for the first time, the ultrastructural features of D. maxima hemocytes. Using phase contrast microscopy of fresh preparations, five hemocyte populations were identified and further characterized by immunofluorescence, flow cytometry and transmission electron microscopy. The plasmatocytes and the granulocytes were the most abundant cell types, although prohemocytes, adipohemocytes and oenocytes were also found. This work sheds light on a controversial aspect of triatomine cell biology and physiology setting the basis for future in-depth studies directed to address hemocyte classification using non-microscopy-based markers.

Whole-Genome Effects of Ethyl Methanesulfonate-Induced Mutation on Nine Quantitative Traits in Outbred Drosophila melanogaster

Genetics ◽  
2001 ◽  
Vol 157 (3) ◽  
pp. 1257-1265 ◽  
Author(s):  
Hsiao-Pei Yang ◽  
Ana Y Tanikawa ◽  
Wayne A Van Voorhies ◽  
Joana C Silva ◽  
Alexey S Kondrashov
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Traits ◽  
Spontaneous Mutation ◽  
Developmental Time ◽  
Ethyl Methanesulfonate ◽  
Induced Mutations ◽  
Mean Values ◽  
Eye Color ◽  
Recessive Mutations ◽  
The Mean

Abstract We induced mutations in Drosophila melanogaster males by treating them with 21.2 mm ethyl methanesulfonate (EMS). Nine quantitative traits (developmental time, viability, fecundity, longevity, metabolic rate, motility, body weight, and abdominal and sternopleural bristle numbers) were measured in outbred heterozygous F3 (viability) or F2 (all other traits) offspring from the treated males. The mean values of the first four traits, which are all directly related to the life history, were substantially affected by EMS mutagenesis: the developmental time increased while viability, fecundity, and longevity declined. In contrast, the mean values of the other five traits were not significantly affected. Rates of recessive X-linked lethals and of recessive mutations at several loci affecting eye color imply that our EMS treatment was equivalent to ∼100 generations of spontaneous mutation. If so, our data imply that one generation of spontaneous mutation increases the developmental time by 0.09% at 20° and by 0.04% at 25°, and reduces viability under harsh conditions, fecundity, and longevity by 1.35, 0.21, and 0.08%, respectively. Comparison of flies with none, one, and two grandfathers (or greatgrandfathers, in the case of viability) treated with EMS did not reveal any significant epistasis among the induced mutations.

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