Cooperative Interactions in Photosensitized Modification of DNA with Oligonucleotide-derived Binary Reagents

Quantitative characteristics of thermodynamic and kinetic cooperativity arising in the process of photomodification of a single-stranded DNA fragment with binary systems of oligonucleotide conjugates forming an active site on the target were studied. Oligonucleotides of the binary system were complementary to adjacent segments of the DNA target, and contained arylazide (X) and perylene (S) residues covalently attached to their terminal phosphates. Upon irradiation at the perylene absorption wavelength, the target was modified by the arylazide residue, which was activated owing to the contiguity with the sensitizing perylene group in the tandem complex. Basing on the kinetic data, the constants of association of both derivatives of oligonucleotides with the target were determined: K _x = 1.13 · 10⁶ M^–1, K _s = 1.49 · 10⁴ M^–1. It was determined that association of both oligonucleotides with the target proceeded with a positive cooperativity characterized by parameter = 45. The kinetic cooperativity parameter was found to be approximately equal to 200; this characterized the acceleration of target modification in complex with the binary reagent versus that in the absence of sensitizer.     

The circadian dynamics of the attacks of the synanthropic population of Culex pipiens molestus mosquitoes at the Staraia Russa Health Resort

The diurnal biting activity of Culex pipiens molestus in rooms of populated houses was studied in August 1998. The highest activity was recorded at 3.00-4.00 a. m., when 25-30 females attacked one volunteer rer 10 minutes.     

The synthesis of a cobalt(II) tetracarboxyphthalocyanine- deoxyribooligonucleotide conjugate as a reagent for the directed DNA modification

The cobalt(II) tetracarboxyphthalocyanine-deoxyribonucleotide pd(TCTTCCCA) conjugate was synthesized. The phthalocyanine N-succinimide ester prepared from phthalocyanine using DCC was mixed in DMF with an aqueous solution of the oligonucleotide bearing a 1,3-diaminopropane linker at the 5'-phosphate. The resulting conjugate was tested in the intraduplex reaction with target 14-mer and 22-mer oligonucleotides containing conjugate-complementary sequences. In the presence of O2 and a thiol (2-mercaptoethanol or DTT) as a coupled reducer or H2O2, sequence-specific DNA modification was observed that caused the cleavage of the target upon treatment with piperidine.     

Influence of Exon Duplication on Intron and Exon Phase Distribution

Nonrandomness in the intron and exon phase distributions in a sample of 305 human genes has been found and analyzed. It was shown that exon duplications had a significant effect on the exon phase nonrandomness. All of the nonrandomness is probably due to both the processes of exon duplication and shuffling. A quantitative estimation of exon duplications in the human genome and their influence on the intron and exon phase distributions has been analyzed. According to our estimation, the proportion of duplicated exons in the human genome constitutes at least 6% of the total. Generalizing the particular case of exon duplication to the more common event of exon shuffling, we modeled and analyzed the influence of exon shuffling on intron phase distribution. Received: 28 March 1997 / Accepted: 9 July 1997     

Hippocampus morphology in tissue culture]

Explants of the hippocampus of newborn rats were studied neurohistologically and with electron microscope within 5--35 days of explantation. Two zones are found in the culture of the hippocampus: a zone of explant, and a zone of outgrowth. Neurons, glial cells and a network of their fibres are compactly arranged in the center of the former, whereas, the latter involves a layer of migrated glial cells. The explant is surrounded by glia limiting cells. Three types of neurons are identified in the long living culture of the hippocampus: pyramidal, polymorphic and granule cells. Numerous nerve endings observed in the hippocampic explant can be recognized as axodendritic, axosomatic and glomerular synapses. The availability of several types of neurons, a variety of synapses and their complication during outgrowth of the culture are suggestive of a formation in the hippocampic explant of a functional reflex activity.     

In vitro antiviral activity of fullerene amino acid derivatives in cytomegalovirus infection]

The in vitro effect of 5 water soluble fullerene C60 amino acid derivatives (FAD) on the development of cytomegalovirus infection was studied in the schemes of the therapeutic, prophylactic and virucidal action. The following compounds as FAD were used: fullerene conjugated with Na salt of gamma-aminobutyric acid (C60-ABA-Na), 2 derivatives based on Na salts of fullerene-gamma-aminobutyric acid and fullerene-omega-caproic acid (C60-ABA-OH-Na and C60-ACA-OH-Na respectively) and 2 derivatives based on methyl ethers of the above mentioned fullerene amino acids (C60-ABA-OH-CH3 and C60-ACA-OH-CH3). All the FAD were able to inhibit the development of the virus cytopathogenic action in the cell culture. However, the compounds had different antiviral properties. C60-ABA-OH-Na, C60-ABA-CH3 and C60-ACA-CH3 showed marked antiviral activity in the prophylactic scheme. 50-Percent inhibition of the virus cytopathogenic action (ID50) was observed when concentrations of the compounds were 0.31, 5 and 25 mcg/ml respectively. C60-ACA-OH-Na inhibited the development of cytomegalovirus infection in the cell culture only in the scheme of the therapeutic action (ID50 4 mcg/ml). C60-ABA-Na had the highest antiviral effect. In a concentration of 0.22 mcg/ml it inhibited the cytomegalovirus plague-forming capacity by 50% in both the prophylactic and the virucidal schemes. The chemotherapeutic index of the compound was within the limits of 2500 to 5450.     

Alterations in mitochondrial dynamics with age‐related Sirtuin1/Sirtuin3 deficiency impair cardiomyocyte contractility

Sirtuin1 (SIRT1) and Sirtuin3 (SIRT3) protects cardiac function against ischemia/reperfusion (I/R) injury. Mitochondria are critical in response to myocardial I/R injury as disturbance of mitochondrial dynamics contributes to cardiac dysfunction. It is hypothesized that SIRT1 and SIRT3 are critical components to maintaining mitochondria homeostasis especially mitochondrial dynamics to exert cardioprotective actions under I/R stress. The results demonstrated that deficiency of SIRT1 and SIRT3 in aged (24–26 months) mice hearts led to the exacerbated cardiac dysfunction in terms of cardiac systolic dysfunction, cardiomyocytes contractile defection, and abnormal cardiomyocyte calcium flux during I/R stress. Moreover, the deletion of SIRT1 or SIRT3 in young (4–6 months) mice hearts impair cardiomyocyte contractility and shows aging‐like cardiac dysfunction upon I/R stress, indicating the crucial role of SIRT1 and SIRT3 in protecting myocardial contractility from I/R injury. The biochemical and seahorse analysis showed that the deficiency of SIRT1/SIRT3 leads to the inactivation of AMPK and alterations in mitochondrial oxidative phosphorylation (OXPHOS) that causes impaired mitochondrial respiration in response to I/R stress. Furthermore, the remodeling of the mitochondria network goes together with hypoxic stress, and mitochondria undergo the processes of fusion with the increasing elongated branches during hypoxia. The transmission electron microscope data showed that cardiac SIRT1/SIRT3 deficiency in aging alters mitochondrial morphology characterized by the impairment of mitochondria fusion under I/R stress. Thus, the age‐related deficiency of SIRT1/SIRT3 in the heart affects mitochondrial dynamics and respiration function that resulting in the impaired contractile function of cardiomyocytes in response to I/R.     

Gene pool of peoples from the Republic Sakha (Yakutia): Structure,origin, genetic relationships

The article presents the results of investigating the gene pool structure and genetic history of the population of the Republic Sakha (Yakutia), using two mutually supplementing genetic systems: mitochondrial DNA and the Y chromosome.     

Hydrolysis of filter-paper cellulose to glucose by two recombinant endogenous glycosyl hydrolases of Coptotermes formosanus

Abstract Genes encoding for glycosyl hydrolases (GH) in multiple families were recovered from an expression sequence tag library of Coptotermes formosanus, a xylophagous lower termite species. Functional analyses of these genes not only shed light on the mechanisms the insect employs to successfully use cellulosic materials as energy sources, which may serve as strategic targets for designing molecular-based bio-pesticides, but also enrich discoveries of new cellulolytic enzymes for conversion of biomass into biofuel. Our study demonstrated that cellulose could be converted to glucose by two recombinant endogenous glycosyl hydrolases (endo-β-1,4 glucanase in GH9 and β-glucosidase in GH1). While the former cleaved cellulose to cellobiose and cellotriose, the resulting simple cellodextrins were digested to glucose. Both of the Escherichia coli-expressed recombinant proteins showed properties that could be incorporated in a glucose-based ethanol production program.