Home About us Contact
|
Home About us Contact | ||
|
|
||
Spatial Separation (spatial + separation)
Selected AbstractsSpatial separation of endothelial small- and intermediate-conductance calcium-activated potassium channels (KCa) and connexins: possible relationship to vasodilator function?JOURNAL OF ANATOMY, Issue 5 2006Shaun L. Sandow Abstract Activation of endothelial cell small- (S) and intermediate- (I) conductance calcium-activated potassium channels (KCa) and current or molecular transfer via myoendothelial gap junctions underlies endothelium-derived hyperpolarization leading to vasodilation. The mechanism underlying the KCa component of vasodilator activity and the characteristics of gap junctions are targets for the selective control of vascular function. In the rat mesenteric artery, where myoendothelial gap junctions and connexin (Cx) 40 are critical for the transmission of the endothelial cell hyperpolarization to the smooth muscle, SKCa and IKCa provide different facets of the endothelium-derived hyperpolarization response, being critical for the hyperpolarization and repolarization phases, respectively. The present study addressed the question of whether this functional separation of responses may be related to the spatial localization of the associated channels? The distribution of endothelial SKCa and IKCa and Cx subtype(s) were examined in the rat mesenteric artery using conventional confocal and high-resolution ultrastructural immunohistochemistry. At the internal elastic lamina,smooth muscle cell interface at internal elastic lamina holes (as potential myoendothelial gap junction sites), strong punctate IKCa, Cx37 and Cx40 expression was present. SKCa, Cx37, Cx40 and Cx43 were localized to adjacent endothelial cell gap junctions. High-resolution immunohistochemistry demonstrated IKCa and Cx37-conjugated gold to myoendothelial gap junction-associated endothelial cell projections. Clear co-localization of KCa and Cxs suggests a causal relationship between their activity and the previously described differential functional activation of SKCa and IKCa. Such precise localizations may represent a selective target for control of vasodilator function and vascular tone. [source] Spatial separation of litter decomposition and mycorrhizal nitrogen uptake in a boreal forestNEW PHYTOLOGIST, Issue 3 2007Björn D. Lindahl Summary ,,Our understanding of how saprotrophic and mycorrhizal fungi interact to re-circulate carbon and nutrients from plant litter and soil organic matter is limited by poor understanding of their spatiotemporal dynamics. ,,In order to investigate how different functional groups of fungi contribute to carbon and nitrogen cycling at different stages of decomposition, we studied changes in fungal community composition along vertical profiles through a Pinus sylvestris forest soil. We combined molecular identification methods with 14C dating of the organic matter, analyses of carbon:nitrogen (C:N) ratios and 15N natural abundance measurements. ,,Saprotrophic fungi were primarily confined to relatively recently (< 4 yr) shed litter components on the surface of the forest floor, where organic carbon was mineralized while nitrogen was retained. Mycorrhizal fungi dominated in the underlying, more decomposed litter and humus, where they apparently mobilized N and made it available to their host plants. ,,Our observations show that the degrading and nutrient-mobilizing components of the fungal community are spatially separated. This has important implications for biogeochemical studies of boreal forest ecosystems. [source] Spatial separation of light perception and growth response in maize root phototropismPLANT CELL & ENVIRONMENT, Issue 9 2002J. L. Mullen Abstract Although the effects of gravity on root growth are well known and interactions between light and gravity have been reported, details of root phototropic responses are less documented. We used high-resolution image analysis to study phototropism in primary roots of Zea mays L. Similar to the location of perception in gravitropism, the perception of light was localized in the root cap. Phototropic curvature away from the light, on the other hand, developed in the central elongation zone, more basal than the site of initiation of gravitropic curvature. The phototropic curvature saturated at approximately 10 µmol m,2 s,1 blue light with a peak curvature of 29 ± 4°, in part due to induction of positive gravitropism following displacement of the root tip from vertical during negative phototropism. However, at higher fluence rates, development of phototropic curvature is arrested even if gravitropism is avoided by maintaining the root cap vertically using a rotating feedback system. Thus continuous illumination can cause adaptation in the signalling pathway of the phototropic response in roots. [source] Dissociating hippocampal subregions: A double dissociation between dentate gyrus and CA1HIPPOCAMPUS, Issue 6 2001Paul E. Gilbert Abstract This study presents a double dissociation between the dentate gyrus (DG) and CA1. Rats with either DG or CA1 lesions were tested on tasks requiring either spatial or spatial temporal order pattern separation. To assess spatial pattern separation, rats were trained to displace an object which covered a baited food-well. The rats were then allowed to choose between two identical objects: one covered the same well as the sample phase object (correct choice), and a second object covered a different unbaited well (incorrect choice). Spatial separations of 15,105 cm were used to separate the correct object from the incorrect object. To assess spatial temporal order pattern separation, rats were allowed to visit each arm of a radial eight-arm maze once in a randomly determined sequence. The rats were then presented with two arms and were required to choose the arm which occurred earliest in the sequence. The choice arms varied according to temporal separation (0, 2, 4, or 6) or the number of arms that occurred between the two choice arms in the sample phase sequence. On each task, once a preoperative criterion was reached, each rat was given either a DG, CA1, or control lesion and then retested. The results demonstrated that DG lesions resulted in a deficit on the spatial task but not the temporal task. In contrast, CA1 lesions resulted in a deficit on the temporal task but not the spatial task. Results suggest that the DG supports spatial pattern separation, whereas CA1 supports temporal pattern separation. Hippocampus 2001;11:626,636. © 2001 Wiley-Liss, Inc. [source] Food or sex; pollinator,prey conflict in carnivorous plantsECOLOGY LETTERS, Issue 6 2001B. Anderson Carnivorous plants potentially trap their own pollinators and it has been argued that considerable spatial separation of flowers and traps has evolved to protect pollinators. We investigated flower-trap separation of Drosera and Utricularia. Short Drosera had a greater element of floral,trap separation than tall Drosera. Such a relationship is unexpected for plants whose peduncles were evolved to protect their pollinators. Utricularia can not trap pollinators but this genus still produces exceptionally long peduncles. We propose that flower-trap separation evolved because carnivorous plants are often short and need to project their flowers well above ground level to make them more attractive to pollinators. [source] Variation in gene content among geographically diverse Sulfolobus isolatesENVIRONMENTAL MICROBIOLOGY, Issue 1 2008Dennis W. Grogan Summary The ability of competitive (i.e., comparative) genomic hybridization (CGH) to assess similarity across entire microbial genomes suggests that it should reveal diversification within and between natural populations of free-living prokaryotes. We used CGH to measure relatedness of genomes drawn from Sulfolobus populations that had been shown in a previous study to be diversified along geographical lines. Eight isolates representing a wide range of spatial separation were compared with respect to gene-specific tags based on a closely related reference strain (Sulfolobus solfataricus P2). For the purpose of assessing genetic divergence, 232 loci identified as polymorphic were assigned one of two alleles based on the corresponding fluorescence intensities from the arrays. Clustering of these binary genotypes was stable with respect to changes in the threshold and similarity criteria, and most of the groupings were consistent with an isolation-by-distance model of diversification. These results indicate that increasing spatial separation of geothermal sites correlates not only with minor sequence polymorphisms in conserved genes of Sulfolobus (demonstrated in the previous study), but also with the regions of difference (RDs) that occur between genomes of conspecifics. In view of the abundance of RDs in prokaryotic genomes and the relevance that some RDs may have for ecological adaptation, the results further suggest that CGH on microarrays may have advantages for investigating patterns of diversification in other free-living archaea and bacteria. [source] A review of research to address carrot fly (Psila rosae) control in the UK,EPPO BULLETIN, Issue 2 2009R. Collier Carrot fly (Psila rosae) is a serious pest of umbelliferous crops such as carrot, parsnip, celery and parsley. Carrot fly has been studied in the UK for more than 60 years. Whilst some of these studies have been focused on insecticides, others have demonstrated the potential for non-insecticidal methods of control that might contribute to an integrated pest management strategy. These include rotation and spatial separation of susceptible crops; carrot varieties with partial resistance to carrot fly; and crop management strategies to avoid oviposition or the development of severe damage. This paper outlines some of the approaches that have been taken and indicates how these are, or might be, used in practice. [source] Tuning the Optoelectronic Properties of Carbazole/Oxadiazole Hybrids through Linkage Modes: Hosts for Highly Efficient Green ElectrophosphorescenceADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Youtian Tao Abstract A series of bipolar transport host materials: 2,5-bis(2-(9H -carbazol-9-yl)phenyl)-1,3,4-oxadiazole (o -CzOXD) (1), 2,5-bis(4-(9H -carbazol-9-yl)phenyl)-1,3,4-oxadiazole (p -CzOXD) (2), 2,5-bis(3-(9H -carbazol-9-yl)phenyl)-1,3,4-oxadiazole (m -CzOXD) (3) and 2-(2-(9H -carbazol-9-yl)phenyl)-5-(4-(9H-carbazol-9-yl)phenyl)-1,3,4-oxadiazole (op -CzOXD) (4) are synthesized through simple aromatic nucleophilic substitution reactions. The incorporation of the oxadiazole moiety greatly improves their morphological stability, with Td and Tg in the range of 428,464,°C and 97,133,°C, respectively. The ortho and meta positions of the 2,5-diphenyl-1,3,4-oxadiazole linked hybrids (1 and 3) show less intramolecular charge transfer and a higher triplet energy compared to the para-position linked analogue (2). The four compounds exhibit similar LUMO levels (2.55,2.59,eV) to other oxadiazole derivatives, whereas the HOMO levels vary in a range from 5.55,eV to 5.69,eV, depending on the linkage modes. DFT-calculation results indicate that 1, 3, and 4 have almost complete separation of their HOMO and LUMO levels at the hole- and electron-transporting moieties, while 2 exhibits only partial separation of the HOMO and LUMO levels possibly due to intramolecular charge transfer. Phosphorescent organic light-emitting devices fabricated using 1,4 as hosts and a green emitter, Ir(ppy)3 or (ppy)2Ir(acac), as the guest exhibit good to excellent performance. Devices hosted by o -CzOXD (1) achieve maximum current efficiencies (,c) as high as 77.9,cd A,1 for Ir(ppy)3 and 64.2,cd A,1 for (ppy)2Ir(acac). The excellent device performance may be attributed to the well-matched energy levels between the host and hole-transport layers, the high triplet energy of the host and the complete spatial separation of HOMO and LUMO energy levels. [source] Behavior and physiology of mechanoreception: separating signal and noiseINTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 1 2009John C. MONTGOMERY Abstract The mechanosensory lateral line is found in all aquatic fish and amphibians. It provides a highly sensitive and versatile hydrodynamic sense that is used in a wide range of behavior. Hydrodynamic stimuli of biological interest originate from both abiotic and biotic sources, and include water currents, turbulence and the water disturbances caused by other animals, such as prey, predators and conspecifics. However, the detection of biologically important stimuli often has to occur against a background of noise generated by water movement, or movement of the fish itself. As such, separating signal and noise is "of the essence" in understanding the behavior and physiology of mechanoreception. Here we discuss general issues of signal and noise in the lateral-line system and the behavioral and physiological strategies that are used by fish to enhance signal detection in a noisy environment. In order for signal and noise to be separated, they need to differ, and we will consider those differences under the headings of: frequency and temporal pattern; intensity discrimination; spatial separation; and mechanisms for the reduction of self-generated noise. We systematically cover the issues of signal and noise in lateral-line systems, but emphasize recent work on self-generated noise, and signal and noise issues related to prey search strategies and collision avoidance. [source] Day-Night Vertical Distribution and Feeding Patterns of Fourth Instar ofChaoborus Larvae in a Neotropical Reservoir (Socuy Reservoir, Venezuela)INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2005Carlos López Abstract The day-night vertical distribution, diel feeding activity and diet of fourth instar of Chaoborus larvae were analyzed in lacustrine zone of a neotropical reservoir which shows seasonally contrasting hypolimnetic oxygen conditions. Larvae stayed in sediment and water bottom during day and ascended to surface during night. Results indicate that feeding activity is limited mainly to the plankton population. Phytoplankton, rotifers or remains of Chaoborus larvae were not found in crops. With the exception of ostracods, all crustacean prey available in the zooplankton occurred in the guts. Ceriodaphnia cornuta and Moina micrura were the most frequent food items (about 75% of occurrence frequency) and were positively selected. The remainder crustacean zooplankton taxa were negatively selected by larvae. The most intense feeding activity in larvae occurred near midnight and sunrise, in dates when the hypolimnion was anoxic. When oxygen was available on the bottom, a higher and not changing diel feeding activity was detected. Our results indicate that vertical migration may promote a spatial separation between larvae and zooplankton, and feeding activity of larvae occurred only when both overlapped. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Rise of the sub-Doppler spectroscopy resolution in thin gas cells by the spatial separation of pumping and probe radiationsLASER PHYSICS LETTERS, Issue 3 2006A. Ch. Abstract The present theoretical work shows the possible essential rise of the resolution of the well tested sub-Doppler laser spectroscopy method, based on the optical pumping and transit of atoms (molecules) in a thin gas cell, by means of the definite spatial separation of pumping and probe light beams. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Comparative analysis of denaturing gradient gel electrophoresis and temporal temperature gradient gel electrophoresis in separating Escherichia coli uidA amplicons differing in single base substitutionsLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2000A.H. Farnleitner A set of Escherichia coli freshwater isolates was chosen to compare the effectiveness of denaturing gradient gel electrophoresis (DGGE) vs temporal temperature gradient gel electrophoresis (TTGE) for separating homologous amplicons from the respective uidA region differing in one to seven single base substitutions. Both methods revealed congruent results but DGGE showed a five to eight times higher spatial separation of the uidA amplicons as compared with TTGE, although the experiments were performed at comparable denaturing gradients. In contrast to TTGE, DGGE displayed clear and focused bands. The results strongly indicated a significantly higher discrimination efficiency of the spatial chemical denaturing gradient as compared with the temporal temperature denaturing gradient for separating the uidA amplicons. Denaturing gradient gel electrophoresis proved to be highly efficient in the differentiation of E. coli uidA sequence types. [source] Population genetic structure, gene flow and sex-biased dispersal in frillneck lizards (Chlamydosaurus kingii)MOLECULAR ECOLOGY, Issue 15 2008BEATA UJVARI Abstract By using both mitochondrial and nuclear multiloci markers, we explored population genetic structure, gene flow and sex-specific dispersal of frillneck lizards (Chlamydosaurus kingii) sampled at three locations, separated by 10 to 50 km, in a homogenous savannah woodland in tropical Australia. Apart from a recombinant lizard, the mitochondrial analyses revealed two nonoverlapping haplotypes/populations, while the nuclear markers showed that the frillneck lizards represented three separate clusters/populations. Due to the small population size of the mtDNA, fixation may occur via founder effects and/or drift. We therefore suggest that either of these two processes, or a combination of the two, are the most likely causes of the discordant results obtained from the mitochondrial and the nuclear markers. In contrast to the nonoverlapping mitochondrial haplotypes, in 12 out of 74 lizards, mixed nuclear genotypes were observed, hence revealing a limited nuclear gene flow. Although gene flow should ultimately result in a blending of the populations, we propose that the distinct nuclear population structure is maintained by frequent fires resulting in local bottlenecks, and concomitant spatial separation of the frillneck lizard populations. Limited mark,recapture data and the difference in distribution of the mitochondrial and nuclear markers suggest that the mixed nuclear genotypes were caused by juvenile male-biased dispersal. [source] Spatial Govemmentality and the New Urban Social Order: Controlling Gender Violence through LawAMERICAN ANTHROPOLOGIST, Issue 1 2001Sally Engle Merry The new urban social order depends on a complex combination of systems of punishment, discipline, and security. Scholars drawing on Foucault's analysis of the art and rationality of governance, or govemmentality, have explored how urban social orders are increasingly based on the governance of space rather than on the discipline of offenders or the punishment of offenses. The new urban social order is characterized by privatized security systems and consumer-policed spaces such as malls. Gender violence interventions represent another deployment of spatial forms of govemmentality. Over the last two decades, punishment of batterers has been augmented by disciplinary systems that teach batterers new forms of masculinity and by security systems for women based on spatial separation. In the postmodern city, spatial govemmentality is integrally connected with punishment and discipline. These new forms of governance circulate globally along with neoliberal ideas of the diminished state, [gender violence, govemmentality, urban society, globalization, law] [source] The performance of AlGaN solar blind UV photodetectors: responsivity and decay timePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2006G. Cherkashinin Abstract The responsivity and the decay time of AlGaN solar blind UV-detectors have been studied. The photodetectors have shown a good spectral responsivity in a narrow spectral range (220 < , < 300 nm) and a short time response with the best estimated characteristic time constant of , , 30 ms measured at room temperature. Possible mechanisms responsible for the persistent photoconductivity (PPC) effect in AlxGa1,xN (x = 0.51) are analyzed. A shape of the spectral response as a function of the applied voltage is analyzed in the frameworks of the space-charge limited current model. It has been shown that the main source of PPC is traps above the Fermi level. PPC occurs when the density of free carriers equals the density of the traps. The model attributing PPC to the spatial separation of the photoexcited electrons and holes by the macroscopic potential barrier is not supported by our photocurrent studies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Formation of luminescence centres under excitation with electron beams in PbWO4 and ZnWO4 crystalsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005S. Chernov Abstract The leading edge of intrinsic luminescence pulse in PbWO4 and ZnWO4 single crystals is studied. The rise of luminescence intensity is observed after excitation with electron beam pulse. The luminescence rise is shown to be a result of luminescence center formation via electron-hole recombination within spatially correlated pairs. An electron of a geminate electron-hole pair of PbWO4 crystal self-traps and stimulates self-trapping of a hole at a close distance. In the ZnWO4 crystal a hole of a geminate electron-hole pair self-traps and stimulates self-trapping of the electron producing a W5+ center at a short distance. The rise-time of luminescence depends on spatial separation of recombining components. It is short even at 80 K (100 ns in PbWO4 and 10 ns in ZnWO4). The reasons for different rise time and different spatial distribution of electron and hole self-trapped centers are discussed. [source] Effects of human,carnivore conflict on tiger (Panthera tigris) and prey populations in Lao PDRANIMAL CONSERVATION, Issue 4 2006A. Johnson Abstract Unique to South-east Asia, Lao People's Democratic Republic contains extensive habitat for tigers and their prey within a multiple-use protected area system covering 13% of the country. Although human population density is the lowest in the region, the impact of human occurrence in protected areas on tiger Panthera tigris and prey populations was unknown. We examined the effects of human,carnivore conflict on tiger and prey abundance and distribution in the Nam Et-Phou Louey National Protected Area on the Lao,Vietnam border. We conducted intensive camera-trap sampling of large carnivores and prey at varying levels of human population and monitored carnivore depredation of livestock across the protected area. The relative abundance of large ungulates was low throughout whereas that of small prey was significantly higher where human density was lower. The estimated tiger density for the sample area ranged from 0.2 to 0.7 per 100 km2. Tiger abundance was significantly lower where human population and disturbance were greater. Three factors, commercial poaching associated with livestock grazing followed by prey depletion and competition between large carnivores, are likely responsible for tiger abundance and distribution. Maintaining tigers in the country's protected areas will be dependent on the spatial separation of large carnivores and humans by modifying livestock husbandry practices and enforcing zoning. [source] Effects of spatial aggregation on competition, complementarity and resource useAUSTRAL ECOLOGY, Issue 3 2008KAREL MOKANY Abstract The spatial distributions of most species are aggregated to varying degrees. A limited number of studies have examined the effects of spatial aggregation on interspecific and intraspecific interactions, generally finding that spatial aggregation can enhance coexistence between species by reducing the capacity for interspecific competition. Less well studied are the effects of spatial aggregation on complementarity (i.e. differences in resource use strategies) and resource use. Our primary hypothesis was that spatial aggregation reduces the complementarity between species owing to: (i) less interspecific interactions as a result of spatial separation; and (ii) less differences between species as a result of phenotypic plasticity. We further postulate that these negative effects of spatial aggregation on complementarity will reduce resource use by the community. Here we test these hypotheses in a pot experiment in which we applied three levels of spatial aggregation to three sets of two-species mixtures of herbaceous perennial plant species from native grasslands of south-eastern Australia. Both root and shoot biomass were significantly affected by spatial aggregation, although the nature of these affects depended upon the species involved, and the relative strengths of interspecific versus intraspecific competition. Complementarity between species in the distribution of their green leaves decreased significantly as spatial aggregation increased for one of the species mixtures, providing some evidence in support of our hypothesis that aggregation reduces complementarity through phenotypic plasticity. Spatial aggregation also altered light interception and use of soil moisture resources, although these effects were dependent on the species involved. We suggest that clear effects of spatial aggregation on complementarity and resource use may be obscured by the idiosyncratic way in which neighbour identity influences plant growth and hence plant size, limiting the ability to generalize, at the community level, any underlying effects of spatial pattern on ecological process. [source] Genetic and morphological divergence reveals local subdivision of perch (Perca fluviatilis L.)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009SARA BERGEK The level of gene flow is an important factor influencing genetic differentiation between populations. Typically, geographic distance is considered to be the major factor limiting dispersal and should thus only influence the degree of genetic divergence at larger spatial scales. However, recent studies have revealed the possibility for small-scale genetic differentiation, suggesting that the spatial scale considered is pivotal for finding patterns of isolation by distance. To address this question, genetic and morphological differentiation were studied at two spatial scales (range 2,13 km and range 300 m to 2 km) in the perch (Perca fluviatilis L.) from the east coast archipelago of Sweden, using seven microsatellite loci and geometric morphometrics. We found highly significant genetic differentiation between sampled locations at both scales. At the larger spatial scale, the distance per se was not affecting the level of divergence. At the small scale, however, we found subtle patterns of isolation by distance. In addition, we also found morphological divergence between locations, congruent with a spatial separation at a microgeographic scale, most likely due to phenotypic plasticity. The present study highlights the importance of geographical scale and indicates that there might be a disparity between the dispersal capacity of a species and the actual movement of genes. Thus, how we view the environment and possible barriers to dispersal might have great implications for our ability to fully understand the evolution of genetic differentiation, local adaptation, and, in the end, speciation. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 746,758. [source] Confocal Raman Microscopy as a Tool to Investigate Concentration Profiles of Melt Crystallized Ibuprofen/Carnauba WaxCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2009H. Qu Abstract Coatings are of great significance for pharmaceutical solid dosage forms. They fulfil a number of functions and are often necessary to control drug delivery, to mask bitter taste, or to protect the active pharmaceutical ingredient from detrimental environmental factors. The process of self-coating by melt crystallization of a suitable binary mixture eliminates the need for an additional process step in the manufacture of a solid drug. Self-coating relies upon the physical and spatial separation of individual components in a melt during solidification. This paper focuses on the use of confocal Raman microscopy as a nondestructive technique for quantifying the spatial distribution of the components in self-coated pastilles manufactured from the binary system ibuprofen/carnauba wax. Pastilles are produced from the melt. Raman spectroscopy allows the direct analysis of concentration profiles across the surface of the pastille. Here, the samples are cleaved and the cleaved surface is investigated in order to establish the distribution of the components in the interior of the solid. A univariate calibration model was developed and statistically validated with standard mixtures of ibuprofen and carnauba wax. Different regression models (linear or polynomial, using different significant peaks for the respective compounds) were assessed and a linear model was found to be adequate to determine the concentration gradient in the pastilles. [source] Comparative analysis of the widespread and conserved PB1-like viruses infecting Pseudomonas aeruginosaENVIRONMENTAL MICROBIOLOGY, Issue 11 2009Pieter-Jan Ceyssens Summary We examined the genetic diversity of lytic Pseudomonas aeruginosa bacteriophage PB1 and four closely related phages (LBL3, LMA2, 14-1 and SN) isolated throughout Europe. They all encapsulate linear, non-permuted genomes between 64 427 and 66 530 bp within a solid, acid-resistant isometric capsid (diameter: 74 nm) and carry non-flexible, contractile tails of approximately 140 nm. The genomes are organized into at least seven transcriptional blocks, alternating on both strands, and encode between 88 (LBL3) and 95 (LMA2) proteins. Their virion particles are composed of at least 22 different proteins, which were identified using mass spectrometry. Post-translational modifications were suggested for two proteins, and a frameshift hotspot was identified within ORF42, encoding a structural protein. Despite large temporal and spatial separations between phage isolations, very high sequence similarity and limited horizontal gene transfer were found between the individual viruses. These PB1-like viruses constitute a new genus of environmentally very widespread phages within the Myoviridae. [source] | ||||||||||||||||||||||||||||