Digestion of human chromosomes by means of the isoschizomers MspI and HpaII

Genome ◽  
1994 ◽  
Vol 37 (5) ◽  
pp. 770-774 ◽  
Author(s):  
A. M. Fernandez-Peralta ◽  
P. Navarro ◽  
I. Tagarro ◽  
J. J. Gonzalez-Aguilera
Keyword(s):  
Mechanism Of Action ◽  
Satellite Dna ◽  
High Frequency ◽  
Chromosome Region ◽  
Cpg Methylation ◽  
Restriction Endonucleases ◽  
High Rate ◽  
Human Chromosomes ◽  
Banding Patterns ◽  
Insight Into

The isoschizomers MspI and HpaII are four base cutter (C↓CGG) restriction endonucleases, HpaII being sensitive to methylation of the internal cytosine. Human chromosomes treated with MspI have produced inconsistent results between laboratories, while HpaII has always been described as a nonbanding enzyme when used on human chromosomes. These results have been explained on the basis of both rarity of the CpG doublet in vertebrate genomes and high rate of CpG methylation (5mCpG). We demonstrated consistent banding patterns subsequent to digestions with MspI and HpaII. On euchromatin, MspI (but not HpaII) digests the DNA of R regions and thus R-bands apparently contain many more CCGG sites (mostly methylated) than G-bands. In heterochromatin, extensive digestion of the 9q12 region not only by MspI but also by HpaII reveals a heterochromatic domain with a high frequency of unmethylated CCGG sites, most probably within the satellite 3 DNA fraction. In addition, enzymatic digestions of the Yq12 heterochromatin, when this region is undercondensed by 5-azacytidine, contribute to deepen the insight into the mechanism of action of this cytidine analog and at the same time reinforce the idea of the heterogeneity of this chromosome region where domains with unmethylated CCGG sites may also exist.Key words: human chromosomes, methylation, restriction endonucleases, heterochromatin, satellite DNA.

scholarly journals A Molecular Insight into the Synergistic Mechanism of Nigella sativa (Black Cumin) with β-Lactam Antibiotics against Clinical Isolates of Methicillin-Resistant Staphylococcus aureus

2021 ◽  
Vol 11 (7) ◽  
pp. 3206
Author(s):  
Lorina I. Badger-Emeka ◽  
Promise Madu Emeka ◽  
Hairul Islam M. Ibrahim
Keyword(s):  
Staphylococcus Aureus ◽  
Mechanism Of Action ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Nigella Sativa ◽  
Synergistic Effects ◽  
Diffusion Method ◽  
Methicillin Resistant ◽  
Cell Wall Disruption ◽  
Time Kill ◽  
Insight Into

Methicillin-resistant Staphylococcus aureus (MRSA) infection is detrimental to hospitalized patients. With diminishing choices of antibiotics and the worry about resistance to colistin in synergistic combined therapy, there are suggestions for the use of herbal derivatives. This investigation evaluated the synergistic effects of Nigella sativa (NS) in combination with beta-lactam (β-lactam) antibiotics on extreme drug-resistant (XDR) MRSA isolates. NS concentrations of 10, 7.5, 5.0, 2.5, 1.0, and 0.1 µg/mL, alone and in combination with β-lactam antibiotics, were used to determine the antimicrobial susceptibility of MRSA isolates by the well diffusion method. Time–kill assays were performed using a spectrophotometer, with time–kill curves plotted and synergism ascertained by the fractional inhibitory concentration (FIC). Scanning and transmission electron microscopy were used to gain insight into the mechanism of action of treated groups. Isolates were inhibited by the NS concentrations, with differences in the zones of inhibition being statistically insignificant at p < 0.05. There were statistically significant differences in the time–kill assay for the MRSA isolates. In addition, NS combined with augmentin showed better killing than oxacillin and cefuroxime. The mechanism of action shown by the SEM and TEM results revealed cell wall disruption, which probably created interference that led to bacterial lysis.

scholarly journals Trastuzumab Mechanism of Action; 20 Years of Research to Unravel a Dilemma

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3540
Author(s):  
Hamid Maadi ◽  
Mohammad Hasan Soheilifar ◽  
Won-Shik Choi ◽  
Abdolvahab Moshtaghian ◽  
Zhixiang Wang
Keyword(s):  
Breast Cancer ◽  
Targeted Therapy ◽  
Cancer Patients ◽  
Mechanism Of Action ◽  
Mechanisms Of Action ◽  
Breast Cancer Patients ◽  
Her2 Positive ◽  
Her2 Positive Breast Cancer ◽  
Insight Into ◽  
Positive Breast Cancer

Trastuzumab as a first HER2-targeted therapy for the treatment of HER2-positive breast cancer patients was introduced in 1998. Although trastuzumab has opened a new avenue to treat patients with HER2-positive breast cancer and other types of cancer, some patients are not responsive or become resistant to this treatment. So far, several mechanisms have been suggested for the mode of action of trastuzumab; however, the findings regarding these mechanisms are controversial. In this review, we aimed to provide a detailed insight into the various mechanisms of action of trastuzumab.

QUINACRINE FLUORESCENCE AND Q-BANDING PATTERNS OF HUMAN CHROMOSOMES.: I. Effects of Varying Factors

1975 ◽  
Vol 17 (1) ◽  
pp. 81-92 ◽  
Author(s):  
C. C. Lin ◽  
H. van de Sande ◽  
W. K. Smink ◽  
D. R. Newton
Keyword(s):  
Exposure Time ◽  
Uv Light ◽  
Human Chromosomes ◽  
Concave Mirror ◽  
Banding Patterns ◽  
Fluorescent Microscope ◽  
Sperm Dna ◽  
Quinacrine Fluorescence ◽  
Well Differentiated ◽  
Salmon Sperm Dna

Various factors involved in the production of "Q-bands" have been studied. It was found that a Zeiss standard WL fluorescent microscope required a shorter exposure time for photography as compared to a Zeiss photomicroscope. The minimal exposure time was obtained when the standard WL microscope was equipped with a UV light source containing a DC powered mercury burner and a concave mirror. Further, the pH and type of water used in the staining, washing and mounting of the slide were also important factors in producing clear and well differentiated "Q-bands". It also appears that the factors involved in the production of "Q-bands" effect the enhancement or quenching of fluorescence by poly d(A-T).poly d(A-T) and salmon sperm DNA or poly dG∙poly dC respectively. This preliminary report also suggests that DNA or polynucleotides with a specific base sequence may play an important role in Q-banding patterns on chromosomes.

High-rate a-Si:H and μc-Si:H Film Growth Studied by Advanced Plasma and in situ Film Diagnostics

2002 ◽  
Vol 715 ◽  
Author(s):  
W.M.M. Kessels ◽  
P.J. van den Oever ◽  
J.P.M. Hoefnagels ◽  
J. Hong ◽  
I.J. Houston ◽  
...  
Keyword(s):  
Film Growth ◽  
Film Studies ◽  
Interface Layer ◽  
Surface Reactivity ◽  
Attenuated Total Reflection ◽  
High Rate ◽  
High Deposition Rate ◽  
Basic Insight ◽  
Insight Into

AbstractPlasma and in situ film studies have been applied to the expanding thermal plasma to obtain basic insight into the deposition of a-Si:H and μc-Si:H at high rates (> 10 Å/s). A study of the density of plasma radicals (Si, SiH, SiH3) and of the radicals' surface reactivity has revealed that SiH3 is the most important radical for the growth of both materials. In situ attenuated total reflection infrared spectroscopy and spectroscopic ellipsometry have revealed a thick interface layer and consequently long incubation time for the materials deposited at a high deposition rate.

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