Influence of a 1000 Times Weakened Magnetic Field on Embryogenesis and Ontogenesis of the Japanese Quail in Several Generations.

The paper presents experimental data on the influence of a 1000-fold weakening of the Earth's magnetic field on the embryonic and postembryonic development of the Japanese quail in three generations. It has been shown that the weakening of the earth's magnetic field by a factor of 1000 affects the formation of blood vessels in Japanese quail embryos, in particular, causing a decrease in angiogenesis in seven-day-old embryos of both the first generation (F) and the next two ones (F and F). Pathological and anatomical studies of embryos of different ages in three generations have revealed various pathologies associated with vascular system disorders, as well as disorders in the development of the beak and eyes.

Radioprotective role of cyanobacterial phycobilisomes.

Cyanobacteria are thought to be responsible for pioneering dioxygen production and the so-called "Great Oxygenation Event" that determined the formation of the ozone layer and the ionosphere restricting ionizing radiation levels reaching our planet, which increased biological diversity but also abolished the necessity of radioprotection. We speculated that ancient protection mechanisms could still be present in cyanobacteria and studied the effect of ionizing radiation and space flight during the Foton-M4 mission on Synechocystis sp. PCC6803.

[Secondary Structure of Aβ(1-16) Complexes with Zinc: A Study in the Gas Phase Using Deuterium/Hydrogen Exchange and Ultra-High-Resolution Mass Spectrometry].

Complexes of peptide fragment 1-16 of beta-amyloid with transition metals play an important role in the development of a broad class of neurodegenerative diseases, which determines the interest in investigating the structures of these complexes. In this work, we have applied the method of the deuterium/hydrogen exchange in combination with ultra-high-resolution mass spectrometry to study conformational changes in (1-16) beta-amyloid peptide induced by binding of zinc(II) atoms. The efficiency of the deuterium/hydrogen exchange depended on the number of zinc atoms bound to the peptide and on the temperature of the ionization source region.

[ACUTE HEPATIC LESION ASSOCIATED WITH MYOCARDIAL INFARCTION: CLINICAL SIGNIFICANCE AND MODERN DIAGNOSTICS].

This review of the literature is devoted to the problem of acute kidney injury (AKI) in patients with acute myocardial infarction (MI). We discuss the occurrence of AKI in patients with MI, mechanisms of its development and modern diagnostic methods. The article examines biomarkers of kidney injury that may be useful for early diagnostics of AKI.

Origin of the heterogeneous distribution of the yield of guanyl radical in UV laser photolyzed DNA.

Oxidative guanine lesions were analyzed, at the nucleotide level, within DNA exposed to nanosecond ultraviolet (266 nm) laser pulses of variable intensity (0.002-0.1 J/cm(2)).

Temperature-dependence of UV laser one-electron oxidative guanine modifications as a probe of local stacking fluctuations and conformational transitions.

By monitoring R(pip)/R(Fpg), i.e. the relative sensitivity to hot piperidine and to formamidopyrimidine DNA glycosylase (Fpg protein) of the guanine lesions induced in DNA exposed to UV laser irradiation, we have previously observed that the formation of the two major types of one-electron oxidative guanine modifications, oxazolone and 7,8-dihydro-8-oxoguanine (8-oxodG), depends on DNA conformational features.

Chemical probing shows that the intron-encoded endonuclease I-SceI distorts DNA through binding in monomeric form to its homing site.

Despite its small size (27.6 kDa), the group I intron-encoded I-SceI endonuclease initiates intron homing by recognizing and specifically cleaving a large intronless DNA sequence. Here, we used gel shift assays and footprinting experiments to analyze the interaction between I-SceI and its target.

Influence of the local helical conformation on the guanine modifications generated from one-electron DNA oxidation.

Two major products, 2,2-diamino-4-[(2-deoxy-beta-D-erythro-pentafuranosyl)amino]-5-(2H )-oxazolone and its imidazole derivative have been generated from one-electron oxidation of the free 2'-deoxyguanosine. The formation of 7,8-dihydro-8-oxoguanine (8-oxodG), not detected in this case, has been observed from DNA exposed to oxidizing agents. Since these compounds are thought to reflect, respectively, either deprotonation or hydration of the transient guanyl radical cation, these findings suggested that the helical structure could influence the chemical decomposition pathway of the guanine moiety.

Formation of cyclobutane thymine dimers from UVA photosensitization of pyridopsoralen monoadducted DNA.

The present report provides evidence that thymine dimerization can be UVA photosensitized at a tetranucleotide, 5'-TATT-3', by a 7-methyl-pyrido(3,4-c)psoralen monoadduct in DNA. The efficiency of the photoprocess depends on the tetranucleotide flanking sequences. These results demonstrate that one DNA lesion can originate the contiguous formation of a second type of lesion and emphasize the sequence-specific response to interaction of drugs with DNA.

DNA-stacking interactions determine the sequence specificity of the deoxyribonuclease activity of 1,10-phenanthroline-copper ion.

Bis(1,10-phenanthroline)-copper(I) ion (OP2Cu+) binds reversibly to B-DNA and makes single-stranded cuts by oxidative attack on the deoxyribose moiety. The deoxyribonuclease activity is sequence-dependent yet not nucleotide-specific at the cutting site. OP2Cu+ sequence specificity was analysed in terms of local variations of DNA stability.

Selective DNA thymine dimerization during UVA irradiation in the presence of a saturated pyridopsoralen.

It has been recently shown that UVA (320-400 nm) irradiation of DNA in the presence of pyridopsoralens induces the formation of thymine cyclobutane dimers in addition to monoadducts. In this work, we measured the potency of a saturated pyridopsoralen to photosensitize DNA, despite its inability to covalently attach to DNA. First, from spectroscopic fluorescence measurements, we have shown that both analogs, saturated and unsaturated pyridopsoralens, namely 4',5'-dihydro-7-methyl-pyrido[3,4-c]psoralen (DH-MePyPs) and 7-methylpyrido[3,4-c]psoralen, exhibit a similar global affinity for DNA.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry of DNA-Pt(II) complexes.

Matrix-assisted laser desorption ionization (MALDI) time-of-flight mass spectrometry has been used to characterize the reaction products of the 18-mer deoxyribonucleotide d(AACGGTTAACCGTTAATT) with [Pt(NH3)3(H2O)]2+ and cis-[Pt(NH3)2(H2O)2]2+. Characteristic peaks corresponding to different monofunctional adducts (18-mer+n[Pt(NH3)3]) (n = 1, 2, 3 and 4) have been observed with the triamino-monoaqua complex. With the diamino-diaqua cis-Pt complex, formation of a chelate (18-mer+[Pt(NH3)2]) involving two adjacent guanines has been demonstrated.

Passage of RNA polymerase from open complex to elongation mode at the Escherichia coli lacUV5 promoter: nucleolytic hypersensitivity as a probe for complex conformational changes.

In transcriptionally active complexes between RNA polymerase and promoters, the center of the melted region is hyperreactive to the nucleolytic activity of the cuprous complex of 1,10-phenanthroline (OP-Cu). In the first part of this work, using synthetic oligonucleotides and exploiting gel retardation assays, I demonstrate that DNA unpairing is not the only determinant of this hyperreactivity. Polymerase binding is directly implicated, presumably participating in the stabilization of an intermediate required for the cutting.

Histone-like protein H1 (H-NS), DNA supercoiling, and gene expression in bacteria.

Changes in DNA supercoiling in response to environmental signals such as osmolarity, temperature, or anaerobicity appear to play an underlying role in the regulation of gene expression in bacteria. Extensive genetic analyses have implicated the osmZ gene in this regulatory process: osmZ mutations are highly pleiotropic and alter the topology of cellular DNA. We have shown that the product of the osmZ gene is the "histone-like" protein H1 (H-NS).

The organization of open complexes between Escherichia coli RNA polymerase and DNA fragments carrying promoters either with or without consensus -35 region sequences.

Transcription initiation at the Escherichia coli galP1 promoter does not depend on specific nucleotide sequences in the -35 region. Footprint analysis of transcriptionally competent complexes between E. coli RNA polymerase and DNA fragments carrying galP1 shows that RNA polymerase protects sequences as far upstream as -55, whereas sequences around the -35 region are exposed.

Chemical nuclease activity of 5-phenyl-1,10-phenanthroline-copper ion detects intermediates in transcription initiation by E. Coli RNA polymerase.

The nuclease activity of the copper complex of 5-phenyl-1,10-phenanthroline (5-phi-OP-Cu) detects conformational changes in the lac UV-5 promoter caused by E. Coli RNA polymerase. The template strand in melted regions of initiation complexes upstream of the site of nucleotide triphosphate incorporation is very reactive.

Sequence determinants for H1 binding on Escherichia coli lac and gal promoters.

The H1 protein is a likely candidate for structuring DNA in the bacterial nucleoid. We have studied determinants leading to its binding to DNA (and in particular to Escherichia coli lac and gal promoters) in vitro through the pattern of attack of both DNaseI and the copper-o-phenanthroline complex [(OP)2Cu+]. The binding of H1 depends on the primary sequence of DNA.

Sequence specificity of the deoxyribonuclease activity of 1,10-phenanthroline-copper ion.

A statistical analysis of a data set composed of over 1600 scission events of DNA produced by the 2:1 1,10-phenanthroline-copper complex (OP-Cu) has demonstrated that the nucleotide 5' to the site of phosphodiester bond scission is a primary influence in the kinetics of cleavage at any sequence position. The scission was less affected by the 3' neighbor. For each of the sixteen possible dinucleotides, a kinetic parameter can be computed reflecting scission at the 3' nucleotide.

Correlation between the conformation of Escherichia coli -10 hexamer sequences and promoter strength: use of orthophenanthroline cuprous complex as a structural index.

The lac and gal control regions contain two functional overlapping promoters P1 and P2. Point mutations can shift transcription from P1 to P2 and vice versa. We show that the reactivity of DNA fragments towards nucleolytic attack with orthophenanthroline cuprous complex can be used to predict which promoter competes more efficiently for RNA polymerase binding.

Studies with the Escherichia coli galactose operon regulatory region carrying a point mutation that simultaneously inactivates the two overlapping promoters. Interactions with RNA polymerase and the cyclic AMP receptor protein.

We report in vitro studies of the interactions between purified E. coli RNA polymerase and DNA from the regulatory region of the E. coli galactose operon which carries a point mutation that simultaneously stops transcription initiation at the two normal start points, S1 and S2.

RNA polymerase makes important contacts upstream from base pair -49 at the Escherichia coli galactose operon P1 promoter.

A G:C to T:A transversion at bp position -19 in the gal operon promoter region relieves the dependence of galP1 promoter activity on the cAMP-CRP complex. Deletion analysis shows that expression from the promoter is decreased on replacement of the sequence between 49 and 54 bp upstream from the P1 start point. Moreover, protection experiments show that RNA polymerase interacts with this region in open complexes at P1.

Visualization of the movement of the Escherichia coli RNA polymerase along the lac UV5 promoter during the initiation of the transcription.

Three probes have been used to detect changes in the contacts between Escherichia coli RNA polymerase and lac UV5 promoter during the formation of the open complex and the initiation of the transcription. The results presented here show how contacts between the enzyme and the UV5 promoter are modulated concomitantly with steady-state synthesis of ApApUpU. These results suggest a movement of the enzyme during the initiation of the transcription preceding the irreversible translocation into the elongation complex.

Nuclease activity of 1,10-phenanthroline-copper ion. Conformational analysis and footprinting of the lac operon.

The nuclease activity of 1,10-phenanthroline-copper [(OP)2Cu+] preferentially nicks the wild-type, Ps, and L8-UV-5 lac promoters in the conserved promoter specific sequence (Pribnow box). The preferred sites of attack of the wild-type fragment within this region are at positions -13 and -12 on the template strand. When the comparable fragment from the Ps promoter, which differs from the wild type at position -9 (T instead of C), is cleaved with (OP)2Cu+, a new strong band at position -10 in the gel patterns is clear.

RNA polymerase mutant able to express in vivo and in vitro the lactose operon in the absence of the cAMP-CRP complex.

By genetic analysis, we have localized a new mutation, isolated from rho-crp background, responsible for a carbohydrate-positive phenotype. The mutation maps in the rpoB gene coding for the beta-subunit of Escherichia coli RNA polymerase. Using reverse transcriptase analysis of transcripts obtained in vivo and transcription assays in vitro, we have shown that this altered RNA polymerase can efficiently initiate the transcription of the lactose operon in the absence of the cAMP-CRP complex both in vivo and in vitro.