Search results for "nuclei"
showing 10 items of 1273 documents
Down-regulation of early sea urchin histone H2A gene relies on cis regulative sequences located in the 5' and 3' regions and including the enhancer b…
2004
The tandem repeated sea urchin alpha-histone genes are developmentally regulated by gene-specific promoter elements. Coordinate transcription of the five genes begins after meiotic maturation of the oocyte, continues through cleavage, and reaches its maximum at morula stage, after which these genes are shut off and maintained in a silenced state for the life cycle of the animal. Although cis regulative sequences affecting the timing and the level of expression of these genes have been characterized, much less is known about the mechanism of their repression. Here we report the results of a functional analysis that allowed the identification of the sequence elements needed for the silencing …
Endogenous fluctuations of DNA topology in the chloroplast of Chlamydomonas reinhardtii.
1998
DNA supercoiling in the chloroplast of the unicellular green alga Chlamydomonas reinhardtii was found to change with a diurnal rhythm in cells growing in alternating 12-h dark-12-h light periods. Highest and lowest DNA superhelicities occurred at the beginning and towards the end of the 12-h light periods, respectively. The fluctuations in DNA supercoiling occurred concurrently and in the same direction in two separate parts of the chloroplast genome, one containing the genes psaB, rbcL, and atpA and the other containing the atpB gene. Fluctuations were not confined to transcribed DNA regions, indicating simultaneous changes in DNA conformation all over the chloroplast genome. Because the d…
Phylogenetic relationship of the green alga Nanochlorum eukaryotum deduced from its chloroplast rRNA sequences.
1995
The marine green coccoidal alga Nanochlorum eukaryotum (N.e.) is of small size with an average diameter of 1.5 microns. It is characterized by primitive-appearing biochemical and morphological properties, which are considerably different from those of other green algae. Thus, it has been proposed that N.e. may be an early developed algal form. To prove this hypothesis, DNA of N.e. was isolated by a phenol extraction procedure, and the chloroplast DNA separated by preparative CsCl density-gradient centrifugation. The kinetic complexity of the nuclear and of the chloroplast DNA was evaluated by reassociation kinetics to 3 x 10(7) bp and 9 x 10(4) bp, respectively. Several chloroplast genes, i…
The cytotoxin-hemolysin genes of human and eel pathogenic Vibrio vulnificus strains: comparison of nucleotide sequences and application to the geneti…
2005
Vibrio vulnificus can be divided into two groups on the basis of pathogenesis. Group 1 is pathogenic only to humans, whereas group 2 is pathogenic to eels and occasionally to humans. Although both groups produce a 50-kDa cytotoxin-hemolysin (V. vulnificus hemolysin; VVH), the toxins are different. In the present study, the nucleotide sequence of the toxin gene (vvhA ) of strain CDC B3547 (a group 2 strain) was determined, and the deduced amino acid sequence was compared to that of strain L-180 (a group 1 strain). The nucleotide sequence of vvhA of strain CDC B3547 was about 96% identical with that of strain L-180, which results in a difference of 3 amino acid residues in the C-terminal lect…
Complete decontamination and regeneration of DNA purification silica colum
2008
Silica columns are among the most used DNA purification systems, allowing a good yield of high-quality nucleic acids without organic extractions. Silica column regeneration protocols reported up to now to remove DNA traces are time-consuming, and their effectiveness on genomic DNA has not been demonstrated. Here we report a very rapid regeneration procedure that ensures no DNA carryover, independent of its size, without impairing column efficiency. The method takes advantage of the improved DNA removal by low concentrations of Triton X-100.
Protein/lipid coaggregates are formed during α-synuclein-induced disruption of lipid bilayers.
2014
Amyloid formation is associated with neurodegenerative diseases such as Parkinson's disease (PD). Significant α-synuclein (αSN) deposition in lipid-rich Lewy bodies is a hallmark of PD. Nonetheless, an unraveling of the connection between neurodegeneration and amyloid fibrils, including the molecular mechanisms behind potential amyloid-mediated toxic effects, is still missing. Interaction between amyloid aggregates and the lipid cell membrane is expected to play a key role in the disease progress. Here, we present experimental data based on hybrid analysis of two-photon-microscopy, solution small-angle X-ray scattering and circular dichroism data. Data show in real time changes in liposome …
Acid–base behaviour and binding to double stranded DNA/RNA of benzo[g]phthalazine-based ligands
2019
The affinity and the binding mode of two benzo[g]phthalazine compounds, functionalized with one or two 2-(imidazole-4-yl)-ethylamine groups, to DNA and RNA models have been evaluated by means of UV-Vis, fluorescence and circular dichroism (CD) spectroscopies in combination with viscometry and molecular dynamics. Both organic molecules bind strongly to all nucleic acid models via the intercalation mode in the duplex structure, especially compound 1. Intriguingly, 1 exhibits different emission responses depending on the base composition of duplex DNA/RNAs, which points out the possibility of using it as a base selective nucleic acid probe. Moreover, the acid-base behaviour of both compounds h…
The interaction of native calf thymus DNA with FeIII-dipyrido[3,2-a:2’,3’-c]phenazine
2008
The mono and bis dipyrido[3,2-a:2',3'-c]phenazine (dppz) adducts of iron(III) chloride, i.e. [Fe(dppz)]Cl(3) and [Fe(dppz)(2)]Cl(3), have been synthesized and characterized. The interaction of the Fe(III)dppz hydrolyzed aquo complex with native calf thymus DNA has been monitored as a function of the metal complex-DNA molar ratio, by variable temperature UV absorption spectrophotometry, circular dichroism (CD) and fluorescence spectroscopy. The results obtained in solution at various ionic strength values give support for a tight intercalative binding of the Fe(III)dppz cation with DNA. In particular, the appearance of induced CD bands, caused by the addition of Fe(III)dppz, indicate the exi…
The interaction of native DNA with iron(III)- N ,N'-ethylene-bis(salicylideneiminato)-chloride.
2004
Abstract The interaction between native calf thymus deoxyribonucleic acid (DNA) and Fe III - N , N ′ -ethylene-bis (salicylideneiminato)-chloride, Fe(Salen)Cl, was investigated in aqueous solutions by UV–visible (UV–vis) absorption, circular dichroism (CD), thermal denaturation and viscosity measurements. The results obtained from CD, UV–vis and viscosity measurements exclude DNA intercalation and can be interpreted in terms of an electrostatic binding between the Fe(Salen) + cation and the phosphate groups of DNA. The trend of the UV–vis absorption band of the Fe(Salen)Cl complex at different ratios [DNA phosphate ]/[Fe(Salen)Cl] and the large increase of the melting temperature of DNA in …
The interaction of native DNA with Zn(II) and Cu(II) complexes of 5-triethyl ammonium methyl salicylidene orto-phenylendiimine
2007
The interaction of native calf thymus DNA with the Zn(II) and Cu(II) complexes of 5-triethyl ammonium methyl salicylidene orto-phenylendiimine (ZnL(2+) and CuL(2+)), in 1 mM Tris-HCl aqueous solutions at neutral pH, has been monitored as a function of the metal complex-DNA molar ratio by UV absorption spectrophotometry, circular dichroism (CD) and fluorescence spectroscopy. The results support for an intercalative interaction of both ZnL(2+) and CuL(2+) with DNA, showing CuL(2+) an affinity of approximately 10 times higher than ZnL(2+). In particular, the values of the binding constant, determined by UV spectrophotometric titration, equal to 7.3x10(4) and 1.3x10(6)M(-1), for ZnL(2+) and CuL…