Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

Extramedullary hematopoiesis in a case of benign mixed mammary tumor in a female dog: cytological and histopathological assessment

Backgroud  

Extramedullary hematopoiesis (EMH) is defined as the presence of hematopoietic stem cells such as erythroid and myeloid lineage plus megakaryocytes in extramedullary sites like liver, spleen and lymph nodes and is usually associated with either bone marrow or hematological disorders. Mammary EMH is a rare condition either in human and veterinary medicine and can be associated with benign mixed mammary tumors, similarly to that described in this case.     

Vibrio cholerae persistence in aquatic environments and colonization of intestinal cells: involvement of a common adhesion mechanism

Forty-one Tnpho A mutants of Vibrio cholerae O1 classical strain CD81 were analyzed for their ability to interact with chitin particles, Tigriopus fulvus copepods and the Intestine 407 cell line compared to the parent strain. Thirteen mutants were less adhesive than CD81; in particular, T21, T33 and T87 were less adhesive towards all substrates and insensitive to inhibition by N-acetyl glucosamine (GlcNAc). By SDS-PAGE analysis of sarkosyl-insoluble membrane proteins (siMPs) isolated from mutants and parent, it was found that a 53 kDa siMP is missing in T21, T33 and T87 mutants. It is hypothesized that this protein might have the function to mediate adherence to GlcNAc-containing substrates both in the aquatic environment and in human intestine.     

Structural characterization of the filamentous bacteriophage PH75 from Thermus thermophilus by Raman and UV-resonance Raman spectroscopy

The filamentous bacteriophage PH75, which infects the thermophile T. thermophilus, assembles in vivo at 70 degrees C and is stable to at least 90 degrees C. Although a high-resolution structure of PH75 is not available, the virion is known to comprise a closed single-stranded (ss) DNA circle of 6500 nucleotides sheathed by a capsid comprising 2700 copies of a 46-residue subunit (pVIII). Here, we employ Raman and UV-resonance Raman (UVRR) spectroscopy to identify structural details of the pVIII and DNA constituents of PH75 that may be related to the high thermostability of the native virion assembly. Analysis of the Raman amide I and amide III signatures reveals that the capsid subunit secondary structure is predominantly (87%) alpha-helical but contains a significant number of residues (6 +/- 1 or 13 +/- 3%) differing from the canonical alpha-helix. This minor structural component is not apparent in capsid subunits of the mesophilic filamentous phages, fd, Pf1, and Pf3, previously examined at similar spectral resolution. The Raman signature of PH75 also differs from those of fd, Pf1, and Pf3 by virtue of an unusual alanine marker (898 cm(-)(1) band), which is attributed to C(alpha)-H hydrogen-bond donation by subunit Ala residues. Because alanines of the PH75 subunit occur primarily within sXXXs motifs (where s is a small side chain, e.g. Gly, Ala, Ser), and because the occurrence of such motifs in alpha-helices is believed to thermostabilize interhelix associations via C(alpha)-H...O interactions [G. Kleiger et al. (2002) Biochemistry 41, 5990-5997], we propose that such hydrogen bonding may explain both the alanyl and amide I/III markers of PH75 capsid subunits and that C(alpha)-H...O interactions may serve as a significant source of virion thermostabilization. Raman and UVRR signatures of PH75 are also distinguished from those of fd, Pf1, and Pf3 by several marker bands that are indicative of hydrophilic Trp and Tyr environments, including hydrogen bonding interactions of aromatic ring substituents. These interactions are likewise proposed as contributors to the high thermostability of PH75 vis-a-vis fd, Pf1, and Pf3. Finally, PH75 is the only filamentous phage exhibiting UVRR markers diagnostic of a highly base-stacked ssDNA genome incorporating the low energy C2'-endo/anti deoxynucleoside conformation. The present results suggest that both intersubunit interactions and genome organization contribute to the enhanced thermostability of PH75 relative to mesophilic filamentous bacteriophages.     

Structural details of the thermophilic filamentous bacteriophage PH75 determined by polarized Raman microspectroscopy

The filamentous virus PH75, which infects the thermophile Thermus thermophilus, consists of a closed DNA strand of 6500 nucleotides encapsidated by 2700 copies of a 46-residue coat subunit (pVIII). The PH75 virion is similar in composition to filamentous viruses infecting mesophilic bacteria but is distinguished by in vivo assembly at 70 degrees C and thermostability to at least 90 degrees C. Structural details of the PH75 assembly are not known, although a fiber X-ray diffraction based model suggests that capsid subunits are highly alpha-helical and organized with the same symmetry (class II) as in the mesophilic filamentous phages Pf1 and Pf3 [Pederson et al. (2001) J. Mol. Biol. 309, 401-421]. This is distinct from the symmetry (class I) of phages fd and M13. We have employed polarized Raman microspectroscopy to obtain further details of PH75 architecture. The spectra are interpreted in combination with known Raman tensors for modes of the pVIII main chain (amide I) and Trp and Tyr side chains to reveal the following structural features of PH75: (i) The average pVIII peptide group is oriented with greater displacement from the virion axis than peptide groups of fd, Pf1, or Pf3. The data correspond to an average helix tilt angle of 25 degrees in PH75 vs 16 degrees in fd, Pf1, and Pf3. (ii) The indolyl ring of Trp 37 in PH75 projects nearly equatorially from the subunit alpha-helix axis, in contrast to the more axial orientations for Trp 26 of fd and Trp 38 of Pf3. (iii) The phenolic rings of Tyr 15 and Tyr 39 project along the subunit helix axis, and one phenoxyl engages in hydrogen-bonding interaction that has no counterpart in either fd or Pf1 tyrosines. Also, in contrast to fd, Pf1, and Pf3, the packaged DNA genome of PH75 exhibits no Raman anisotropy, suggesting that DNA bases are not oriented unidirectionally within the nucleocapsid assembly. The structural findings are discussed in relation to intrasubunit and intersubunit interactions that may confer hyperthermostability to the PH75 virion. A refined molecular model is proposed for the PH75 capsid subunit.     

Effects of virion and salt concentrations on the Raman signatures of filamentous phages fd, Pf1, Pf3, and PH75

Filamentous phages consist of a single-stranded DNA genome encapsidated by several thousand copies of a small alpha-helical coat protein subunit plus several copies of four minor proteins at the filament ends. The filamentous phages are important as cloning vectors, vehicles for peptide display, and substrates for macromolecular alignment. Effective use of a filamentous phage in such applications requires an understanding of experimental factors that may influence the propensity of viral filaments to laterally aggregate in solution. Because the Raman spectrum of a filamentous phage is strongly dependent on the relative orientation of the virion with respect to the polarization direction of the electromagnetic radiation employed to excite the spectrum, we have applied Raman spectroscopy to investigate lateral aggregation of phages fd, Pf1, Pf3, and PH75 in solution. The results show that lateral aggregation of the virions and anisotropic orientation of the aggregates are both disfavored by high concentrations of salt (>200 mM NaCl) in solutions containing a relatively low virion concentration (<10 mg/mL). Conversely, the formation of lateral aggregates and their anisotropic orientation are strongly favored by a low salt concentration (<0.1 mM NaCl), irrespective of the virion concentration over a wide range. The use of Raman polarization effects to distinguish isotropic and anisotropic solutions of filamentous phages is consistent with previously reported Raman analyses of virion structures in both solutions and fibers. The Raman data are supported by electron micrographs of negatively stained specimens of phage fd, which permit an independent assessment of salt effects on lateral aggregation. The present results also identify new Raman bands that serve as potential markers of subunit side-chain orientations in filamentous virus assemblies.     

Domain structures and roles in bacteriophage HK97 capsid assembly and maturation

Head assembly in the double-stranded DNA coliphage HK97 involves initially the formation of the precursor shell Prohead I from approximately 420 copies of a 384-residue subunit. This is followed by proteolytic removal of residues 2-103 to create Prohead II, and then reorganization and expansion of the shell lattice and covalent cross-linking of subunits make Head II. Here, we report and structurally interpret solution Raman spectra of Prohead I, Prohead II, and Head II particles. The Raman signatures of Prohead I and Prohead II indicate a common alpha/beta fold for residues 104-385, and a strongly conserved tertiary structure. The Raman difference spectrum between Prohead I and Prohead II demonstrates that the N-terminal residues 2-103 (Delta-domain) form a predominantly alpha-helical fold devoid of beta-strand. The conformation of the Delta-domain in Prohead I thus resembles that of the previously characterized scaffolding proteins of Salmonellaphage P22 and Bacillus phage phi29 and suggests an analogous architectural role in mediating the assembly of a properly dimensioned precursor shell. The Prohead II --> Head II transition is accompanied by significant reordering of both the secondary and tertiary structures of 104-385, wherein a large increase occurs in the percentage of beta-strand (from 38 to 45%), and a marginal increase is observed in the percentage of alpha-helix (from 27 to 31%). Both are at the expense of unordered chain segments. Residue environments affected by HK97 shell maturation include the unique cysteine (Cys 362) and numerous tyrosines and tryptophans. The tertiary structural reorganization is reminiscent of that observed for the procapsid --> capsid transformation of P22. The Raman signatures of aqueous and crystalline Head II reveal no significant differences between the crystal and solution structures.     

Anatomic demarcation by positional variation in fibroblast gene expression programs

Fibroblasts are ubiquitous mesenchymal cells with many vital functions during development, tissue repair, and disease. Fibroblasts from different anatomic sites have distinct and characteristic gene expression patterns, but the principles that govern their molecular specialization are poorly understood. Spatial organization of cellular differentiation may be achieved by unique specification of each cell type; alternatively, organization may arise by cells interpreting their position along a coordinate system. Here we test these models by analyzing the genome-wide gene expression profiles of primary fibroblast populations from 43 unique anatomical sites spanning the human body. Large-scale differences in the gene expression programs were related to three anatomic divisions: anterior-posterior (rostral-caudal), proximal-distal, and dermal versus nondermal. A set of 337 genes that varied according to these positional divisions was able to group all 47 samples by their anatomic sites of origin. Genes involved in pattern formation, cell-cell signaling, and matrix remodeling were enriched among this minimal set of positional identifier genes. Many important features of the embryonic pattern of HOX gene expression were retained in fibroblasts and were confirmed both in vitro and in vivo. Together, these findings suggest that site-specific variations in fibroblast gene expression programs are not idiosyncratic but rather are systematically related to their positional identities relative to major anatomic axes.     

Studies on the partial characterization of extracted glycosaminoglycans from fish waste and its potentiality in modulating obesity through in-vitro and in-vivo

Glycoconjugate Journal - Glycosaminoglycans (GAGs) are bioactive polysaccharides or glycoconjugates found in the fish waste having significant health impacts. In the present study it has been...     

Yield and quality of forage maize (<i>Zea mays</i> L.) with different levels of subsurface drip irrigation and plant density

The scarcity of water in arid and semiarid regions of the world is a problem that every day increases by climate change. The subsurface drip irrigation (SDI) and changes in population density of plants are alternatives that can be used to make a sustainable use of water. Therefore, the objectives of this study were to determine the combination that allows for an increased corn performance and efficient use of water without losing the quality of forage. Three different irrigation levels were applied through a system of a SDI at three different densities of forage maize plants in an arid region. The results demonstrated that by applying different levels of water, either enough or lack of soil moisture is created, which is directly reflected in crop yield, and its determining variables such as green forage and dry matter yield, and nutritional quality. The irrigation level to a 100% of potential evapotranspiration (PET), at a density of 80000 plants/ha, increased yield of green forage to 57664 kg/ha; crude protein was 8.59%, while the rest of the quality parameters decreased. This study allowed to conclude that the irrigation level was the major factor in the response of the crop.