scholarly journals THERMAL DEPOLARIZATION OF FLUORESCENCE FROM POLYTENE CHROMOSOMES STAINED WITH ACRIDINE ORANGE

1967 ◽  
Vol 33 (3) ◽  
pp. 597-604 ◽  
Author(s):  
James W. MacInnes ◽  
Robert B. Uretz
Keyword(s):  
Acridine Orange ◽  
Rotational Diffusion ◽  
Polytene Chromosomes ◽  
Degree Of Polarization ◽  
Fourth Chromosome ◽  
Thermal Change ◽  
Low Concentrations ◽  
Thermal Denaturation Temperature ◽  
Dna Thermal Denaturation ◽  
Increasing Temperature

The degree of polarization of fluorescence from stretched Chironomus thummi polytene chromosomes, stained with low concentrations of acridine orange (AO), decreases with increasing temperature. The "half temperature" of this decrease (T½R) is lower than the expected DNA thermal denaturation temperature (Tm) by about 20°C. T½R is lowered as histone is removed from chromosomes. Balbiani ring regions of the fourth chromosome have T½R's much lower than other regions, and nearly as low as chromosomes which had been extensively pretreated with trypsin to remove histone and other proteins. Measurements of the thermal change in the rotational diffusion rate of AO in solution with DNA indicate that the temperature at which the DNA-AO bonding changes from a "rigid" to a "loose" mode varies with the GC percentage of the DNA, and in the same fashion as Tm, although 20°C lower.

scholarly journals Protein aggregation in C-phycocyanin. Studies at very low concentrations with the photoelectric scanner of the ultracentrifuge

1971 ◽  
Vol 122 (4) ◽  
pp. 421-426 ◽  
Author(s):  
R. MacColl ◽  
J. J. Lee ◽  
D. S. Berns
Keyword(s):  
Protein Aggregation ◽  
Temperature Dependence ◽  
Equilibrium Constant ◽  
Ph Dependence ◽  
Sedimentation Velocity ◽  
Scanning System ◽  
High Concentration ◽  
Low Concentrations ◽  
Increasing Temperature ◽  
Schlieren Optics

Solutions of C-phycocyanin of very low concentrations were examined by sedimentation-velocity studies in the Spinco model E ultracentrifuge equipped with a photoelectric scanning system and a monochromator. At sufficiently low concentrations complete disaggregation from the hexamer to the monomer was observed. The equilibrium constant of monomer to hexamer was estimated to be approx. 1030. For studies of aggregation over the complete range of concentration, C-phycocyanins from Phormidium luridum and Lyngbya sp. were used. Sedimentation-velocity studies at high concentration with schlieren optics are reported for C-phycocyanins from Anabaena variabilis and Lyngbya sp. The pH-dependence of aggregation and the temperature-dependence of trimer–hexamer equilibrium for phycocyanins from these algae were found to be similar to those of other C-phycocyanins. The principal feature of the pH-dependence is the dominance of hexamers at the isoelectric point. Increasing temperature increased the amount of hexamer and decreased the amount of trimer.

scholarly journals Polytene chromosomes reflect functional organization of the Drosophila genome

2019 ◽  
Vol 23 (2) ◽  
pp. 148-153
Author(s):  
D. S. Sidorenko ◽  
T. Yu. Zykova ◽  
V. A. Khoroshko ◽  
G. V. Pokholkova ◽  
S. A. Demakov ◽  
...  
Keyword(s):  
Banding Pattern ◽  
Functional Organization ◽  
Polytene Chromosomes ◽  
Diploid Cell ◽  
Regulatory Elements ◽  
Molecular Organization ◽  
Open Chromatin ◽  
Drosophila Genome ◽  
Fourth Chromosome ◽  
Molecular Map

Polytene chromosomes of Drosophila melanogaster are a convenient model for studying interphase chromosomes of eukaryotes. They are giant in size in comparison with diploid cell chromosomes and have a pattern of cross stripes resulting from the ordered chromatid arrangement. Each region of polytene chromosomes has a unique banding pattern. Using the model of four chromatin types that reveals domains of varying compaction degrees, we were able to correlate the physical and cytological maps of some polytene chromosome regions and to show the main properties of genetic and molecular organization of bands and interbands, that we describe in this review. On the molecular map of the genome, the interbands correspond to decompacted aquamarine chromatin and 5’ ends of ubiquitously active genes. Gray bands contain lazurite and malachite chromatin, intermediate in the level of compaction, and, mainly, coding parts of genes. Dense black transcriptionally inactive bands are enriched in ruby chromatin. Localization of several dozens of interbands on the genome molecular map allowed us to study in detail their architecture according to the data of whole genome projects. The distribution of proteins and regulatory elements of the genome in the promoter regions of genes localized in the interbands shows that these parts of interbands are probably responsible for the formation of open chromatin that is visualized in polytene chromosomes as interbands. Thus, the permanent genetic activity of interbands and gray bands and the inactivity of genes in black bands are the basis of the universal banding pattern in the chromosomes of all Drosophila tissues. The smallest fourth chromosome of Drosophila with an atypical protein composition of chromatin is a special case.  Using the model of four chromatin states and fluorescent in situ hybridization, its cytological map was refined and the genomic coordinates of all bands and interbands were determined. It was shown that, in spite of the peculiarities of this chromosome, its band organization in general corresponds to the rest of the genome. Extremely long genes of different Drosophila chromosomes do not fit the common scheme, since they can occupy a series of alternating bands and interbands (up to nine chromosomal structures) formed by parts of these genes.

scholarly journals Cytogenetic study of three closely related species of Hawaiian Drosophila

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 47-57 ◽  
Author(s):  
Jayne N. Ahearn ◽  
Visut Baimai
Keyword(s):  
Cytogenetic Study ◽  
Hybrid Sterility ◽  
Polytene Chromosomes ◽  
Low Frequency ◽  
Small Mass ◽  
Fourth Chromosome ◽  
Metaphase Chromosomes ◽  
Chromosome Inversion ◽  
Hawaiian Drosophila ◽  
Allopatric Species

Three allopatric species from the Hawaiian islands, Drosophila bostrycha (Molokai), D. affinidisjuncta (West Maui), and D. disjuncta (East Maui), are extremely similar in morphology but differ in metaphase chromosomes by the amount and distribution of heterochromatin. Their polytene chromosomes are virtually homosequential with only slight differences at the tip of the microchromosome. Each is polymorphic for one or more inversions, especially in chromsome 4. Salivary gland chromosomes of F1 larvae reared either from wild-caught females or wild-caught males mated to standard laboratory stocks were examined for gene arrangements. Drosophila bostrycha and D. affinidisjuncta share a polymorphism for inversion 4v, which is much more frequent in the latter than in the former. In D. disjuncta 4v has been found only joined in a haplotype with three other inversions (g2 h2 i2) at a low frequency at Kipahulu Valley. Drosophila disjuncta is unique in having another fourth chromosome inversion, 4k, which is highest in frequency at Waikamoi. A new inversion, 2s, was discovered at Uluini Stream. Interspecific hybridizations were carried out in small mass matings. Backcrosses and dissections demonstrated that all F1 females were fertile. All F1 males were sterile in either of two categories with reciprocal hybrids uniformly manifesting one or the other type. Attempts to model the sterility mechanism suggest that more than chromosomal sterility is involved. Our results are discussed in relation to other closely related clusters of species having heterochromatin-based karyotype variations. Key words: heterochromatin, hybrid sterility, inversion, polymorphism, species divergence.

Rotational diffusion of Acridine Orange attached to SDS micelles

1989 ◽  
Vol 93 (22) ◽  
pp. 7694-7698 ◽  
Author(s):  
Shiow Hwa Chou ◽  
Mary J. Wirth
Keyword(s):  
Acridine Orange ◽  
Rotational Diffusion ◽  
Sds Micelles

Spectrophotometric investigation on the interaction of acridine orange with methylene blue, phenosafranine, and disulphine blue in aqueous medium

1981 ◽  
Vol 59 (16) ◽  
pp. 2449-2456 ◽  
Author(s):  
Suhaschandra Ghosh ◽  
Satya P. Moulik ◽  
Akhil R. Das
Keyword(s):  
Methylene Blue ◽  
Absorption Band ◽  
Acridine Orange ◽  
Aqueous Medium ◽  
Vital Role ◽  
Spectrophotometric Investigation ◽  
Experimental Demonstration ◽  
Low Concentrations ◽  
Dye Aggregation

The results of dye–dye interactions for the pairs, acridine orange – methylene blue, acridine orange – phenosafranine, and acridine orange – disulphine blue have been presented. It has been found that at comparable concentrations the interaction is rather weak, and the formation of mixed entities is only possible at relatively high proportions of one of the components. However, the evidence of mixed dimers in the form of a new absorption band is lacking. Phenosafranine remarkably promotes dimerization of acridine orange. An experimental demonstration of the dimer spectra of acridine orange has thus been possible. The interaction of the anionic dye disulphine blue with cationic acridine orange has been observed to be the weakest of all the pairs, indicating the vital role of the structural parity for interaction. At comparable low concentrations, none of the dye-pairs studied have revealed compound metachromasy in the presence of a polyelectrolyte, suggesting unfavorable mixed dye aggregation under ordinary conditions.

Three Locally Clays as A Surfaces for Adsorption of Cephalexin Monohydrate From Aqueous Solution: Thermodynamic and Desorption Equilibrium

2018 ◽  
pp. 198
Author(s):  
Saja S. Al-Taweel ◽  
Sadoon A. Isa ◽  
Ramzi R. Al-Ani
Keyword(s):  
Aqueous Solution ◽  
Adsorption Process ◽  
Ph Value ◽  
Fixed Temperature ◽  
Clay Particles ◽  
Drug Molecules ◽  
Hydronium Ions ◽  
Low Concentrations ◽  
Human Body Temperature ◽  
Increasing Temperature

    The  adsorption of cephalexin.H2O from aqueous solution on attapulgite, bentonite and kaolin has been studied at the human body temperature (37.5˚C) and at 5, 27, 47˚C in 0.1M hydrochloric acid (pH 1.2). The value of pH 1.2 has been chosen to simulate the pH of stomach fluid. The clays show the following order: Bentonite > attapulgite > kaolin, for their activity to adsorb cephalexin.H2O. The charged clay particles can attract molecules either by electrostatic forces, for the molecules of oppositely charged, or by inducing dipole formation in the neutral molecule. The L-shaped adsorption isotherm indicated that drug molecules arrangement in a flat geometry on the clay surface. The results indicated the applicability of Langmuir isotherm for adsorption of drug on three clays. The amount of cephalexin.H2O adsorbed on  the  three  clays was increased with  increasing pH value from 1.2 to 5. At the acidic pH, the competition between cephalexin.H2O molecules and hydronium ions results in a reduction in adsorption process. At fixed temperature and pH, the adsorption of cephalexin.H2O on the three clays was increased with increasing the ionic strength of solution. The data showed a little increase in the amount of drug adsorbed by attapulgite and bentonite with increasing temperature, so the adsorption process appeared endothermic. The reverse was observed with adsorption of cephalexin.H2O on kaolin surface (exothermic).The extent of desorption of cephalexin.H2O from the clays increased when the concentration of drug increased. This result may  refer to the difficulty of desorption of the drug at low concentrations, which reflects a relatively higher adsorbate - adsorbent interaction.

Etude du système acridine orange – poly(C) et de son interaction avec les complexes du palladium(II)

1984 ◽  
Vol 62 (9) ◽  
pp. 1681-1686 ◽  
Author(s):  
Robert Ménard ◽  
Miklos Zador
Keyword(s):  
Acridine Orange ◽  
Thermodynamic Parameters ◽  
Rate Constant ◽  
Kinetic Studies ◽  
Stopped Flow ◽  
Flow Method ◽  
Polycytidylic Acid ◽  
Low Concentrations ◽  
C Complex ◽  
Kinetics Of

The complex formed between acridine orange (AO) and polycytidylic acid (poly(C)) was studied by spectrophotometry and spectrofluorometry. The complex was characterized by its stoichiometry, structure, and the thermodynamic parameters of its formation. The results are in agreement with an external aggregation of the protonated dye along the negatively charged poly(C) chain and indicate that approximately two AO molecules are bound per nucleotide unit of poly(C). The kinetics of the reaction between this complex and a Pd(II) complex was studied by the stopped-flow method. The addition of (dien)Pd(II) to the AO–poly(C) complex leads to the dissociation of the latter, due to fixation of the Pd(II) complex to the N3 site of the cytosine base of poly(C). The rate constant for the AO liberation, extrapolated at zero AO concentration, corresponds to the rate constant of Pd(II) fixation on poly(C). This indicates that AO can be used as an indicator for this reaction and allows kinetic studies at very low concentrations (≤ 5 × 10−6 M).

scholarly journals A lot about a little dot — lessons learned from Drosophila melanogaster chromosome 4This paper is one of a selection of papers published in this Special Issue, entitled 29th Annual International Asilomar Chromatin and Chromosomes Conference, and has undergone the Journal’s usual peer review process.

2009 ◽  
Vol 87 (1) ◽  
pp. 229-241 ◽  
Author(s):  
Nicole C. Riddle ◽  
Christopher D. Shaffer ◽  
Sarah C.R. Elgin
Keyword(s):  
Drosophila Melanogaster ◽  
Peer Review Process ◽  
Position Effect ◽  
Polytene Chromosomes ◽  
Lessons Learned ◽  
Position Effect Variegation ◽  
Chromosomal Protein ◽  
Chromosome 4 ◽  
Fourth Chromosome ◽  
Heterochromatin Protein 1

The fourth chromosome of Drosophila melanogaster has a number of unique properties that make it a convenient model for the study of chromatin structure. Only 4.2 Mb overall, the 1.2 Mb distal arm of chromosome 4 seen in polytene chromosomes combines characteristics of heterochromatin and euchromatin. This domain has a repeat density of ~35%, comparable to some pericentric chromosome regions, while maintaining a gene density similar to that of the other euchromatic chromosome arms. Studies of position-effect variegation have revealed that heterochromatic and euchromatic domains are interspersed on chromosome 4, and both cytological and biochemical studies have demonstrated that chromosome 4 is associated with heterochromatic marks, such as heterochromatin protein 1 and histone 3 lysine 9 methylation. Chromosome 4 is also marked by POF (painting-of-fourth), a chromosome 4-specific chromosomal protein, and utilizes a dedicated histone methyltransferase, EGG. Studies of chromosome 4 have helped to shape our understanding of heterochromatin domains and their establishment and maintenance. In this review, we provide a synthesis of the work to date and an outlook to the future.

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