Tjurina and Milnor numbers of matrix singularities

To gain understanding of the deformations of determinants and Pfaffians resulting from deformations of matrices, the deformation theory of composites f ◦ F with isolated singularities is studied, where f : Y −→C is a function with (possibly non-isolated) singularity and F : X −→Y is a map into the domain of f, and F only is deformed. The corresponding T1(F) is identified as (something like) the cohomology of a derived functor, and a canonical long exact sequence is constructed from which it follows that τ = μ(f ◦ F) − β0 + β1, where τ is the length of T1(F) and βi is the length of ToriOY(OY/Jf, OX). This explains numerical coincidences observed in lists of simple matrix singularities due to Bruce, Tari, Goryunov, Zakalyukin and Haslinger. When f has Cohen–Macaulay singular locus (for example when f is the determinant function), relations between τ and the rank of the vanishing homology of the zero locus of f ◦ F are obtained

The Effect of Surfactants on Equilibrium Wetting

Contact angles B0 of aqueous solutions contacting with hydrophilic and hydrophobic surfaces were studied as affected by various surfactants (alcohols, fatty acids, soaps) under conditions close to thermodynamic equilibrium (in the atmosphere saturated with the solution vapour). The conditions of transitions from limited wetting (Bo > 0) to complete wetting, i.e. spontaneous spreading were also studied. The effect of surfactants adsorption at the solid gas interface was estimated from the isotherms of wetting tension W = cr1g Cos B0 (cr1g is the surface tension of the solution) on the basis of equation describing W as a function of concentration. It is shown that adsorption of surfactants at the solid-gas interface markedly affects wetting of hydrophilic materials. For hydrophobic materials the effect is primarily due to adsorption of surfactants at the solid- solution and solution-gas interfaces. It was found that equilibrium wetting is affected by the type of adsorption at the solid surface (physical or chemical adsorption). The influence of hydrocarbon chain length in homological series of alcohols and fatty acids on equilibrium contact angles and on transition to spontaneous spreading was studied as well

Original Russian Text ©

In eukaryotes, rRNA genes form multigenic families consisting of tandemly located repeated units strongly varying in number (from several hundreds to several thousands). A repeated unit includes the genes of 18S, 5.8S, and 26S rRNAs separated by transcribed spacers (ITS) 1 and 2 and by the intergenic spacer (IGS). Depending on localization of the 5S rRNA genes, two types of ribosomal operon organization are described In the present work, we studied specific features of the IGS1 structure of the ribosomal operon from acrocarpous mosses of the Schistidium genus for which we studied earlier the ITS1 structure, as well as the phylogeny of the genus based on the ITS1-2 sequences and regions of the chloroplast genome MATERIALS AND METHODS Thirty-three sequences of IGS1 from 12 species of Schistidium were determined. Below the species are listed, ISSN 0006-2979, Biochemistry (Moscow), 2015, Vol. 80, No. 11, pp. 1485-1491. © Pleiades Publishing, Ltd., 2015. Original Russian Text © I. A. Milyutina, E. A. Ignatova, M. S. Ignatov, D. V. Goryunov, A. V. Troitsky, 2015, published in Biokhimiya, 2015, Vol. 80, No. 11, pp. 1707-1714 On-Line Papers in Press, as Manuscript BM15-232, September 27, 2015. 1485 Abbreviations: bp, nucleotide base pair; IGS1, intergenic spacer 1. * To whom correspondence should be addressed. Sciences, 127276 Moscow, Russia; E-mail: [email protected] Received July 8, 2015 Structure of Intergenic Abstract-The structure of the intergenic spacer 1 (IGS1) of the ribosomal operon from 12 species of Schistidium mosses was studied. In the IGS1 sequences of these species, three conserved regions and two areas of GC-and A-enriched repeats were identified. All of the studied mosses have a conserved pyrimidine-enriched motif at the 5′-end of IGS1. Species-specific nucleotide substitutions and insertions were found in the conserved areas. The repeated units contain single nucleotide substitutions that make unique the majority of repeated units. The positions of such repeats in IGS1 are species-specific, but their number can vary within the species and among operons of the same specimen. The comparison of IGS1 sequences from the Schistidium species and from representatives of ten other moss genera revealed the presence of common conserved motifs with similar localization. Presumably, these motifs are elements of termination of the pre-rRNA transcription and processing of rRNA

Structural variability of sunflower gene for methionine-rich albumin SFA8

Background. The 2S albumins of sunflower and other oilseed plants possess a high nutritional quality, the defense activity against fungi diseases casual gents and also valuable functional properties. The major component of albumin fraction, the SFA8 protein consists of 103 amino acid residues among which methionine constitutes 15 Mole %. In the cultivated sunflower gene pool the SFA8 structural gene is represented by the two alleles the products of which have different isoelectric points and differ by the electrophoretic mobility, however molecular mechanisms of the polymorphism are still unknown. Results. The amplified sequences of the SFA8 gene from seven Helianthus annuus L. accessions and three accessions of wild Helianthus L. species from VIR collection were sequences. The intron of 258-303 bp length depending on the genotype was firstly found in the central part of the gene. The length of the first exon constitutes 99 bp, the second exon is of 210 bp length. The nucleotide and translated amino acid sequences are polymorphic among different genotypes. The line VIR 130 in which the two expressing SFA8 proteins, the normal polypeptide with isoelectric point (pI) approximately 6.0 (normal SFA8) and its allelic variant with pI 6.5 (variant SFA8) have been earlier revealed possesses two types of the SFA8 encoding sequence. In one sequence the substitution 108С—G is present that results in the substitution of the polar uncharged amino acid serine for the positively charged arginine and respectively in alteration of the protein charge and isoelectric point. The intron sequence is also polymorphic and characterized by the presence of indels of approximately 45 bp. The intron sequences of all accessions contain dinucleotides GT at the 5΄ end and AG at the 3΄ end which are characteristic for consensus sequences of splicing sites in the U2-type introns. The variants of the secondary structure of the SFA8 intron sequences of H. argophyllus Torr. & A. Gray and all the analyzed H. annuus genotypes are similar and differ from those of H. petiolaris Nutt. and H. giganteus L. Conclusions. The data on the SFA8 gene sequence polymorphism are important understanding the molecular mechanisms of genotypic differences in biochemical and functional properties of the protein, and he revealed differences in the intron secondary structure can be important for understanding expression patterns of the protein

Heavy residue excitation functions for the collisions 6, 7Li + 64Zn near the Coulomb barrier

Excitation functions for the production of heavy residues have been measured for the collisions 6, 7Li+64Zn at energies around and below the Coulomb barrier. The cross sections for heavy residue production have been measured using an activation technique, detecting off-line the characteristic atomic x-rays emitted in the electron capture decay of the reaction products. The experimental relative yields of the residues have been compared with statistical model calculations performed by using the code cascade. Such a comparison suggests that heavy residue production is dominated by complete fusion at above-barrier energies, whereas different processes like incomplete fusion and/or transfer become dominant in the sub-barrier energy region. The heavy residue excitation function ratio between the 6Li- and 7Li-induced collisions shows an increasing trend as the energy decreases below the barrier

BPAG1a and b Associate with EB1 and EB3 and Modulate Vesicular Transport, Golgi Apparatus Structure, and Cell Migration in C2.7 Myoblasts

BPAG1a and BPAG1b (BPAG1a/b) constitute two major isoforms encoded by the dystonin (Dst) gene and show homology with MACF1a and MACF1b. These proteins are members of the plakin family, giant multi-modular proteins able to connect the intermediate filament, microtubule and microfilament cytoskeletal networks with each other and to distinct cell membrane sites. They also serve as scaffolds for signaling proteins that modulate cytoskeletal dynamics. To gain better insights into the functions of BPAG1a/b, we further characterized their C-terminal region important for their interaction with microtubules and assessed the role of these isoforms in the cytoskeletal organization of C2.7 myoblast cells. Our results show that alternative splicing does not only occur at the 5′ end of Dst and Macf1 pre-mRNAs, as previously reported, but also at their 3′ end, resulting in expression of additional four mRNA variants of BPAG1 and MACF1. These isoform-specific C-tails were able to bundle microtubules and bound to both EB1 and EB3, two microtubule plus end proteins. In the C2.7 cell line, knockdown of BPAG1a/b had no major effect on the organization of the microtubule and microfilament networks, but negatively affected endocytosis and maintenance of the Golgi apparatus structure, which became dispersed. Finally, knockdown of BPAG1a/b caused a specific decrease in the directness of cell migration, but did not impair initial cell adhesion. These data provide novel insights into the complexity of alternative splicing of Dst pre-mRNAs and into the role of BPAG1a/b in vesicular transport, Golgi apparatus structure as well as in migration in C2.7 myoblasts

Microtubule Actin Crosslinking Factor 1 Regulates the Balbiani Body and Animal-Vegetal Polarity of the Zebrafish Oocyte

Although of fundamental importance in developmental biology, the genetic basis for the symmetry breaking events that polarize the vertebrate oocyte and egg are largely unknown. In vertebrates, the first morphological asymmetry in the oocyte is the Balbiani body, a highly conserved, transient structure found in vertebrates and invertebrates including Drosophila, Xenopus, human, and mouse. We report the identification of the zebrafish magellan (mgn) mutant, which exhibits a novel enlarged Balbiani body phenotype and a disruption of oocyte polarity. To determine the molecular identity of the mgn gene, we positionally cloned the gene, employing a novel DNA capture method to target region-specific genomic DNA of 600 kb for massively parallel sequencing. Using this technique, we were able to enrich for the genomic region linked to our mutation within one week and then identify the mutation in mgn using massively parallel sequencing. This is one of the first successful uses of genomic DNA enrichment combined with massively parallel sequencing to determine the molecular identity of a gene associated with a mutant phenotype. We anticipate that the combination of these technologies will have wide applicability for the efficient identification of mutant genes in all organisms. We identified the mutation in mgn as a deletion in the coding sequence of the zebrafish microtubule actin crosslinking factor 1 (macf1) gene. macf1 is a member of the highly conserved spectraplakin family of cytoskeletal linker proteins, which play diverse roles in polarized cells such as neurons, muscle cells, and epithelial cells. In mgn mutants, the oocyte nucleus is mislocalized; and the Balbiani body, localized mRNAs, and organelles are absent from the periphery of the oocyte, consistent with a function for macf1 in nuclear anchoring and cortical localization. These data provide the first evidence for a role for spectraplakins in polarization of the vertebrate oocyte and egg

Hippocampal pyramidal cells: the reemergence of cortical lamination

The increasing resolution of tract-tracing studies has led to the definition of segments along the transverse axis of the hippocampal pyramidal cell layer, which may represent functionally defined elements. This review will summarize evidence for a morphological and functional differentiation of pyramidal cells along the radial (deep to superficial) axis of the cell layer. In many species, deep and superficial sublayers can be identified histologically throughout large parts of the septotemporal extent of the hippocampus. Neurons in these sublayers are generated during different periods of development. During development, deep and superficial cells express genes (Sox5, SatB2) that also specify the phenotypes of superficial and deep cells in the neocortex. Deep and superficial cells differ neurochemically (e.g. calbindin and zinc) and in their adult gene expression patterns. These markers also distinguish sublayers in the septal hippocampus, where they are not readily apparent histologically in rat or mouse. Deep and superficial pyramidal cells differ in septal, striatal, and neocortical efferent connections. Distributions of deep and superficial pyramidal cell dendrites and studies in reeler or sparsely GFP-expressing mice indicate that this also applies to afferent pathways. Histological, neurochemical, and connective differences between deep and superficial neurons may correlate with (patho-) physiological phenomena specific to pyramidal cells at different radial locations. We feel that an appreciation of radial subdivisions in the pyramidal cell layer reminiscent of lamination in other cortical areas may be critical in the interpretation of studies of hippocampal anatomy and function