A repetitive DNA element,associated with telomeric sequences in Drosophila melanogaster,contains open reading frames

He-T sequences are a complex repetitive family of DNA sequences in Drosophila that are associated with telomeric regions, pericentromeric heterochromatin, and the Y chromosome. A component of the He-T family containing open reading frames (ORFs) is described. These ORF-containing elements within the He-T family are designated T-elements, since hybridization in situ with the polytene salivary gland chromosomes results in detectable signal exclusively at the chromosome tips. One T-element that has been sequenced includes ORFs of 1,428 and 1,614 bp. The ORFs are overlapping but one nucleotide out of frame with respect to each other. The longer ORF contains cysteine-histidine motifs strongly resembling nucleic acid binding domains of gag-like proteins, and the overall organization of the T-element ORFs is reminiscent of LINE elements. The T-elements are transcribed and appear to be conserved in Drosophila species related to D. melanogaster. The results suggest that T-elements may play a role in the structure and/or function of telomeres.by W. Hennig     

Kinetics of formation of 8-oxy-2'-deoxyguanosine-5'-monophosphate under the effect of heat: determination of rate constants and activation energy]

Rate constants of 8-oxy-dGMP (8-hydroxy-dGMP) formation upon incubating dGMP in H2O solutions at different temperatures were determined with differential UV-spectroscopy. Extrapolation of rate constant values obtained at elevated temperatures to 37 degrees C gives k = 5.8 x 10(-10) s-1.M-1. The activation energy for the process was estimated to be 24 kcal/mole. In D2O solutions essential lowering of the activation energy (13 kcal/mole) and rising of rate constant (k = 3.7 x 10(-9) s-1.M-1 at 37 degrees C) were observed. The strong influence of D2O on the process points to the possible participation of singlet oxygen in a heat-induced formation of 8-oxy-dGMP. The obtained values of rate constants and activation energy induced by heat show that of all types of DNA damages currently known such as single strand scission, depurination, cytosine deamination and oxidation of guanyl residues to the 8-oxo-derivatives- the last process seems to be the strongest damage of DNA resulting in such biological consequences as mutagenesis, carcinogenesis and aging.     

Interaction of alkaline metal ions with Ca(2+)-binding sites of Ca(2+)-ATPase of sarcoplasmic reticulum: 23Na-NMR studies.

The analysis of the 23Na-NMR signal shape variations in the presence of vesicles of light sarcoplasmic reticulum (SR) shows the existence of sodium sites on the membranes with Kd values of about 10 mM. Other monovalent cations displace Na+ from SR fragments in a competitive manner according to the row K+ greater than Rb+ greater than Cs+ greater than Li+. Calcium ions also reduce Na+ binding, the Na+ desorption curve being of a two-stage nature, which, as suggested, indicates the existence of two types of Ca(2+)-sensitive Na+ binding sites (I and II). Sites of type I and II are modified by Ca2+ in submicromolar and millimolar concentrations, respectively. Analysis of sodium (calcium) desorption produced by calcium (sodium) allowed us to postulate the competition of these two cations for sites I and identity of these sites to high-affinity Ca(2+)-binding ones on the Ca(2+)-ATPase. Sites I weakly interact with Mg2+ (KappMg approximately 30 mM). Reciprocal effects of sodium and calcium on binding of each other to sites II cannot be described by a simple competition model, which indicates nonhomogeneity of these sites. A portion of sites I (approximately 70%) interacts with Mg2+ (KappMg = 3-4 mM). The pKa value of sites II is nearly 6.0. The number of sites II is three times greater than that of sites I. In addition, sites with intermediate affinity for Ca2+ were found with Kd values of 2-5 microM. These sites were revealed due to the reducing of the sites II affinity for Na+ upon Ca2+ binding to SR membranes. It can thus be concluded that in nonenergized SR there are binding sites for monovalent cations of at least three types: (1) sites I (which also bind Ca2+ at low concentrations), (2) magnesium-sensitive sites II and (3) magnesium-insensitive sites II.     

Factors that control the differentiation of stem cells. I. The change in direction of hematopoietic stem cell differentiation under the effect of differentiating T-lymphocytes]

A mixed transplantation of bone marrow cells, and lymph nodes or thymic cells of mice CBA strain into lethally irradiated hybrid recipients (CBAXC57B1)F1 is accompanied with changes in the differentiation pattern from a mainly erythroid to a mainly granuloid way. Thymectomy of either donor of bone marrow cells or recipients, or both, destroys the stem cell differentiation in the direction of granulopoieseis. Intact syngeneic lymphocytes normalize differentiation of the stem cells, but in the presence of tissue antigens these provide for the stem cell differentiation mainly in the direction of granulopoiesis. The differentiation of stem haemopoietic cells is accomplished under the thymic and lymphocyte control. T-differentiating lymphocytes (Td) are the lymphocytes controlling the stem cell differentiation.     

Development and investigation of recombinant immunotoxin protein 4D5scFv-mCherry-PE(40)

Development of agents for theranostics implies combining the targeting module, the effector module, and the detection module within the same complex or recombinant protein. We have constructed, isolated, and characterized the 4D5scFv-mCherry-PE(40) protein, which exhibits fluorescent properties and specifically binds to cancer cells expressing the HER2 receptor and reduces their viability. The ability of the obtained targeted antitumor agent 4D5scFv-mCherry-PE(40) to selectively stain the HER2-positive cells and its highly selective cytotoxicity against these cells make the obtained targeted recombinant protein 4D5scFv-mCherry-PE(40) a promising theranostic agent for the diagnostics and therapy of HER2-positive human tumors.     

Full-Wave Modeling of Doppler Backscattering from Filaments

Plasma Physics Reports - It is recognized that the filaments have a significant effect on the anomalous energy and particle transport in the tokamak periphery. They are actively investigated using...     

A Highlights from MBoC Selection: Fast and parallel nanoscale three-dimensional tracking of heterogeneous mammalian chromatin dynamics

Chromatin organization and dynamics are critical for gene regulation. In this work we present a methodology for fast and parallel three-dimensional (3D) tracking of multiple chromosomal loci of choice over many thousands of frames on various timescales. We achieved this by developing and combining fluorogenic and replenishable nanobody arrays, engineered point spread functions, and light sheet illumination. The result is gentle live-cell 3D tracking with excellent spatiotemporal resolution throughout the mammalian cell nucleus. Correction for both sample drift and nuclear translation facilitated accurate long-term tracking of the chromatin dynamics. We demonstrate tracking both of fast dynamics (50 Hz) and over timescales extending to several hours, and we find both large heterogeneity between cells and apparent anisotropy in the dynamics in the axial direction. We further quantify the effect of inhibiting actin polymerization on the dynamics and find an overall increase in both the apparent diffusion coefficient D* and anomalous diffusion exponent α and a transition to more-isotropic dynamics in 3D after such treatment. We think that in the future our methodology will allow researchers to obtain a better fundamental understanding of chromatin dynamics and how it is altered during disease progression and after perturbations of cellular function.