109 research outputs found
The Origin of the Electromagnetic Interaction in Einstein's Unified Field Theory with Sources
Einstein's unified field theory is extended by the addition of matter terms
in the form of a symmetric energy tensor and of two conserved currents. From
the field equations and from the conservation identities emerges the picture of
a gravoelectrodynamics in a dynamically polarizable Riemannian continuum.
Through an approximate calculation exploiting this dynamical polarizability it
is argued that ordinary electromagnetism may be contained in the theory.Comment: 8 pages. Misprint in eq. 15 correcte
Mycoplasma Diversity in Arctic Permafrost
© 2016, Springer Science+Business Media New York.Viable bacterial cells and its genetic material can be stably maintained in Arctic permafrost for a long geological time. Because of the seasonal melting of permafrost strata, it cannot be excluded an access to the surface of ancient highly invasive species with increased pathogenicity. Mycoplasmas are very successful pathogens in humans, mammals, birds, insects, and plants, with high genome plasticity and ability to avoid immune response of host organism. The metagenomic approach allowed us to predict mycoplasma diversity in the Arctic permafrost. The number of mycoplasma DNA fragments in soil deposits of comparable age (∼30,000 years) and origin (the late Pleistocene Ice Complexes) is not so abundant compared with other microorganisms, but it is enough for a chance in the presence of living mycoplasmal cells in permafrost. DNA fragments of human, animal, insect, and plant pathogens were identified. The “ubiquitous” mycoplasma Acholeplasma laidlawii is the undisputed leader in the number of identified sequences in all three metagenomes. It may indicate a higher adaptive capacity and more powerful metabolic potential of A. laidlawii among Mollicutes
The Temperature-Dependent Selectivity of Potential Interaction Partners for the Small Heat Shock Protein IbpA from Acholeplasma laidlawii
© 2016, Springer Science+Business Media New York.Small heat shock proteins (sHsps) of α-crystalline type play a key role in the cell survival under stress conditions by preventing irreversible denaturation and aggregation of proteins. In contrast to most Mollicutes (mycoplasmas) where no sHsps were found, recently, some sHsp homologs were identified in the Acholeplasmataceae family, including Acholeplasma laidlawii, the only representative of Mollicutes that is known to survive in a host-free environment. Using pull-down followed by LC-MS, we identified the potential target proteins co-eluting with IbpA from the A. laidlawii cell extracts after exposition to low- and high temperatures. 308 and 464 proteins were co-eluted with IbpA from the cold- and heat-treated extracts, respectively, while only 240 of them were co-eluted with sHsp independently of the temperature. Most of potential IbpA targets were identified as enzymes involved in biosynthetic cycles and energy metabolism. We show IbpA specificity for target proteins on the incubation temperature. Significant differences between protein pools co-eluting specifically with IbpA at either 4 or 46 °C could be observed in terms of their aliphatic index, charge, molecular weight, and isoelectric point. Interestingly, only the isoelectric point distribution significantly differed between the protein pool co-eluting with IbpA under cooling (4 °C) and the entire proteome. In contrast, significant discrepancies in the distributions of aliphatic index, charge, hydropathy, molecular weight, and isoelectric point could be observed between the pool of proteins co-eluting with IbpA under heating (46 °C) and the entire proteome, indicating that there is likely a complex selective mechanism for proteins interaction with IbpA under heat shock conditions
The Electrostatics of Einstein's Unified Field Theory
When sources are added at their right-hand sides, and g_{(ik)} is a priori
assumed to be the metric, the equations of Einstein's Hermitian theory of
relativity were shown to allow for an exact solution that describes the general
electrostatic field of n point charges. Moreover, the injunction of spherical
symmetry of g_{(ik)} in the infinitesimal neighbourhood of each of the charges
was proved to yield the equilibrium conditions of the n charges in keeping with
ordinary electrostatics. The tensor g_{(ik)}, however, cannot be the metric of
the theory, since it enters neither the eikonal equation nor the equation of
motion of uncharged test particles. A physically correct metric that rules both
the behaviour of wave fronts and of uncharged matter is the one indicated by
H\'ely. In the present paper it is shown how the electrostatic solution
predicts the structure of the n charged particles and their mutual positions of
electrostatic equilibrium when H\'ely's physically correct metric is adopted.Comment: 15 pages. Misprints corrected. To appear in General Relativity and
Gravitatio
Recombinant small heat shock protein from Acholeplasma laidlawii increases the Escherichia coli viability in thermal stress by selective protein rescue
© 2017, Pleiades Publishing, Inc.In both prokaryotes and eukaryotes, the survival at temperatures considerably exceeding the optimum is supported by intense synthesis of the so-called heat shock proteins (HSPs), which act to overcome the adverse effects of heat stress. Among mycoplasmas (class Mollicutes), which have significantly reduced genomes, only some members of the Acholeplasmataceae family possess small HSPs of the α-crystallin type. Overproduction of a recombinant HSP IbpA (Hsp20) from the free-living mycoplasma Acholeplasma laidlawii was shown to increase the resistance of Escherichia coli to short-term heat shock. It has been long assumed that IbpA prevents protein aggregation and precipitation thereby increasing viability of E. coli cells. Several potential target proteins interacting with IbpA under heat stress were identified, including biosynthetic enzymes, enzymes of energy metabolism, and components of the protein synthesis machinery. Statistical analysis of physicochemical properties indicated that IbpA interaction partners significantly differ in molecular weight, charge, and isoelectric point from other members of the E. coli proteome. Upon shortterm exposure to increased temperature, IbpA was found to preferentially interact with high-molecularweight proteins having a pI of about 5.1, significantly lower than the typical values of E. coli proteins
Extracellular membrane vesicles secreted by mycoplasma Acholeplasma laidlawii PG8 are enriched in virulence proteins
Mycoplasmas (class Mollicutes), the smallest prokaryotes capable of self-replication, as well as Archaea, Gram-positive and Gram-negative bacteria constitutively produce extracellular vesicles (EVs). However, little is known regarding the content and functions of mycoplasma vesicles. Here, we present for the first time a proteomics-based characterisation of extracellular membrane vesicles from Acholeplasma laidlawii PG8. The ubiquitous mycoplasma is widespread in nature, found in humans, animals and plants, and is the causative agent of phytomycoplasmoses and the predominant contaminant of cell cultures. Taking a proteomics approach using LC-ESI-MS/MS, we identified 97 proteins. Analysis of the identified proteins indicated that A. laidlawii-derived EVs are enriched in virulence proteins that may play critical roles in mycoplasma-induced pathogenesis. Our data will help to elucidate the functions of mycoplasma-derived EVs and to develop effective methods to control infections and contaminations of cell cultures by mycoplasmas.In the present study, we have documented for the first time the proteins in EVs secreted by mycoplasma vesicular proteins identified in this study are likely involved in the adaptation of bacteria to stressors, survival in microbial communities and pathogen-host interactions. These findings suggest that the secretion of EVs is an evolutionally conserved and universal process that occurs in organisms from the simplest wall-less bacteria to complex organisms and indicate the necessity of developing new approaches to control infects. © 2014
A Survey of Scale Insects (Sternorryncha: Coccoidea) Occurring on Table Grapes in South Africa
Increasing international trade and tourism have led to an increase in the introduction of exotic pests that pose a considerable economic threat to the agro-ecosystems of importing countries. Scale insects (Sternorryncha: Coccoidea) may be contaminants of export consignments from the South African deciduous fruit industry to the European Union, Israel, United Kingdom and the United States, for example. Infestations of immature scale insects found on South African fruit destined for export have resulted in increasing rates of rejection of such consignments. To identify the risk posed by scale insect species listed as phytosanitary pests on table grapes to the abovementioned importing countries, a field survey was undertaken in 2004–2005 in vineyards throughout all grape-producing regions in South Africa. Coccoidea species found during the current field survey were Planococcus ficus (Signoret), Pseudococcus longispinus (Targioni Tozzetti), Coccus hesperidum L. and Nipaecoccus viridis (Newstead). With the exception of Pl. ficus, which has only been collected from Vitis vinifera (Vitaceae) and Ficus carica (Moraceae) in South Africa, these species are polyphagous and have a wide host range. None of the scale insect species found to occur in vineyards in South Africa pose a phytosanitary risk to countries where fruit are exported except for Ferrisia malvastra (McDaniel) and N. viridis that have not been recorded in the USA. All scale insects previously found in vineyards in South Africa are listed and their phytosanitary status discussed. The results of the survey show that the risk of exporting scale insect pests of phytosanitary importance on table grapes from South Africa is limited
Quaternion-Octonion Analyticity for Abelian and Non-Abelian Gauge Theories of Dyons
Einstein- Schroedinger (ES) non-symmetric theory has been extended to
accommodate the Abelian and non-Abelian gauge theories of dyons in terms of the
quaternion-octonion metric realization. Corresponding covariant derivatives for
complex, quaternion and octonion spaces in internal gauge groups are shown to
describe the consistent field equations and generalized Dirac equation of
dyons. It is also shown that quaternion and octonion representations extend the
so-called unified theory of gravitation and electromagnetism to the Yang-Mill's
fields leading to two SU(2) gauge theories of internal spaces due to the
presence of electric and magnetic charges on dyons
Taxonomic revision of Myrosma (Marantaceae)
Myrosma is a genus of rosulate herbs characterized by a compact and strongly monosymmetric inflorescence with conspicuous, white to pale green, mostly membranous bracts, in the axil of which is a single flower pair. The genus is widely distributed throughout Central Brazil, northern South America, and the Caribbean region. It occurs mostly in savannah environments but can also be found in humid and shaded habitats. We present a taxonomic revision of Myrosma recognizing a single species, Myrosma cannifolia L.f. A complete description of that species is provided with notes on its ecology, distribution, and variation. Three species and one variety are reduced into synonymy and four names are lectotypified. A complete nomenclatural account for all combinations including the name Myrosma is given
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