The nuclease activity of the endogenous differentiation factor of the HL-60 cell line

A structural homology between the endogenous differentiation factor of the HL-60 cell line of promyelocyte leukemia (HLDF) and several DNA/RNA-binding and DNA/RNA-hydrolyzing proteins was revealed, and expression of thehldf gene in prokaryotic systems was studied. On the basis of these experiments, the amino acid sequence of an 8-membered fragment of HLDF with potential nuclease activity was identified. The synthetic octapeptide RRWHRLKE was shown to be capable of the cleavage of RNA, linear DNA from phage λ, and all forms of plasmid DNA. We established that treatment of the HL-60 cell culture with this peptide (10⁻⁶ M) results in an increase in the number of apoptotic cells and suggested that HLDF is involved in processes of apoptosis.     

The movement of melanosomes in melanophore fragments obtained by laser microbeam irradiation

The melanophores of the teleost Gymnocorymbus ternetzi are filled with pigment granules, melanosomes, which in response to appropriate treatments, can disperse throughout the cytoplasm or form an aggregate in the cell center. Melanophores with the dispersed pigment were irradiated by a laser microbeam, focused on the cell center by the microscope objective. If the average energy of the microbeam was 6-7 microJ, either the center of the melanophore was damaged and a single ring-shaped fragment was formed, or the cell was broken into several fragments of smaller size. The fragments retained their ability to move the pigment granules. In ring-shaped fragments, after adrenaline treatment, the melanosomes formed a ring-shaped aggregate moving away from both outer and inner (irradiation-produced) margins of the fragment. The smaller fragments treated with adrenaline moved the pigment to their centers. Both small and ring-shaped fragments could aggregate melanosomes as soon as 5 minutes after irradiation.     

Stimulation of the CLIP-170--dependent capture of membrane organelles by microtubules through fine tuning of microtubule assembly dynamics

Cytoplasmic microtubules (MTs) continuously grow and shorten at their free plus ends, a behavior that allows them to capture membrane organelles destined for MT minus end-directed transport. In Xenopus melanophores, the capture of pigment granules (melanosomes) involves the +TIP CLIP-170, which is enriched at growing MT plus ends. Here we used Xenopus melanophores to test whether signals that stimulate minus end MT transport also enhance CLIP-170-dependent binding of melanosomes to MT tips. We found that these signals significantly (>twofold) increased the number of growing MT plus ends and their density at the cell periphery, thereby enhancing the likelihood of interaction with dispersed melanosomes. Computational simulations showed that local and global increases in the density of CLIP-170-decorated MT plus ends could reduce the half-time of melanosome aggregation by ~50%. We conclude that pigment granule aggregation signals in melanophores stimulate MT minus end-directed transport by the increasing number of growing MT plus ends decorated with CLIP-170 and redistributing these ends to more efficiently capture melanosomes throughout the cytoplasm.     

Determination of the minimum size of Gallus gallus domesticus chicken microchromosome by a pulse electrophoresis method]

The karyotype of the chicken Gallus gallus domesticus was studied by means of pulsed-field electrophoresis. An electrokaryogram was obtained for the microchromosomal (MI) portion of the chicken genome. Chicken MIs were separated into two fractions. A fraction with a higher mobility included MIs sized 3.4-4.8 Mb; the lower size limit of a less mobile fraction corresponded to MIs of approximately 5 Mb. The smallest MI in the chicken karyotype was estimated at 3.4 +/- 0.25 Mb.     

Genome: Origins and evolution of the term

The appearance of a new scientific term is a significant event in the human cognitive process and the result of the realization of the separateness of an object or a phenomenon. Our article concentrates on the origins of basic genetic terms, such as genetics, gene, genotype, genome, gene pool, and genomics. We propose using the term karyogenomics for the special direction of genomics related to the study of the organization and evolution of eukaryotic genomes by means of modern chromosome analysis, as well as by full genome sequencing.     

Identification and expression of haponin, a new protein from HL-60 cells

We found a new protein haponin (an HLDF-like protein) in promyelocyte HL-60 cells that is immunoreactive to polyclonal antibodies against HLDFβ. Determination of the partial primary structure of the protein allowed us to reveal an immunogenic peptide of haponin and, on the basis of the amino acid sequence of this peptide, the degenerate primers were synthesized, which enabled us to clone the full-size cDNA of haponin. The stable heterologous expression of this cDNA in E. coli cells (Rosetta? strain) was obtained. Preparations of natural and recombinant proteins exhibited antigenic cross-reactivity to polyclonal antibodies against this peptide.     

Immunochemical properties of a protective cross-reacting antigen of meningococci

The study of protective cross-reacting antigenic preparations isolated from meningococci of groups A and C in the blot immunoassay has shown the presence of a group of proteins with a molecular weight ranging from 23 to 31 KD and common for 8 tested serological groups of meningococci, gonococci and 4 nonpathogenic Neisseria species. The possible role of these structures as common Neisseria antigen in the formation of natural resistance to meningococcal infection is discussed.