Search results for " meta"

Regional metacommunities in two coastal systems: spatial structure and drivers of plant assemblages

2014

Aim Biogeographical patterns in metacommunities are still poorly understood, and different processes are expected to occur in different habitats. We analysed the regional plant metacommunities of coastal habitats to test whether (1) the influence of space and climate differs between two habitats differentiated along the seashore–inland gradient, and (2) regional variation in species composition of these habitats can be ascribed to different metacommunity paradigms. Location The entire coast of the Iberian Peninsula, south-western Europe. Methods We collected data on the plant species composition of coastal sites on sand dunes across 3000 km of coastline. The sites were classified into two h…

Impegno motivato. Esercizio di decision making "Facciamo la valigia"

2009

La vida imaginaria del científico. El caso del cómic 'The Manhattan Projects'

2014

Aquest article analitza The Manhattan Projects, serie de comics que explica una historia alternativa sobre el fi nal de la Segona Guerra Mundial en que el Projecte Manhattan amaga altres activitats mes relacionades amb la ciencia-fi ccio. Aquest treball analitza la translacio del concepte de vida imaginaria encunyat per Marcel Schwob a la historia de la ciencia en el segle XX.

Rab33B and its autophagic Atg5/12/16L1 effector assist in hepatitis B virus naked capsid formation and release

2015

Hepatitis B virus morphogenesis is accompanied by the production and release of non-enveloped capsids/nucleocapsids. Capsid particles are formed inside the cell cytosol by multimerization of core protein subunits and ultimately exported in an uncommon coatless state. Here, we investigated potential roles of Rab GTPases in capsid formation and trafficking by using RNA interference and overexpression studies. Naked capsid release does not require functions of the endosome-associated Rab5, Rab7 and Rab27 proteins, but depends on functional Rab33B, a GTPase participating in autophagosome formation via interaction with the Atg5-Atg12/Atg16L1 complex. During capsid formation, Rab33B acts in conju…

Infection-induced chromatin modifications facilitate translocation of herpes simplex virus capsids to the inner nuclear membrane

2021

Herpes simplex virus capsids are assembled and packaged in the nucleus and move by diffusion through the nucleoplasm to the nuclear envelope for egress. Analyzing their motion provides conclusions not only on capsid transport but also on the properties of the nuclear environment during infection. We utilized live-cell imaging and single-particle tracking to characterize capsid motion relative to the host chromatin. The data indicate that as the chromatin was marginalized toward the nuclear envelope it presented a restrictive barrier to the capsids. However, later in infection this barrier became more permissive and the probability of capsids to enter the chromatin increased. Thus, although …

Modulation of Hepatitis C Virus NS5A Hyperphosphorylation by Nonstructural Proteins NS3, NS4A, and NS4B

1999

NS5A of the hepatitis C virus (HCV) is a highly phosphorylated protein involved in resistance against interferon and required most likely for replication of the viral genome. Phosphorylation of this protein is mediated by a cellular kinase(s) generating multiple proteins with different electrophoretic mobilities. In the case of the genotype 1b isolate HCV-J, in addition to the basal phosphorylated NS5A (designated pp56), a hyperphosphorylated form (pp58) was found on coexpression of NS4A (T. Kaneko, Y. Tanji, S. Satoh, M. Hijikata, S. Asabe, K. Kimura, and K. Shimotohno, Biochem. Biophys. Res. Commun. 205:320‐326, 1994). Using a comparative analysis of two full-length genomes of genotype 1b…

Binding and internalization of human papillomavirus type 33 virus-like particles by eukaryotic cells

1995

Infection of cells by human papillomaviruses (HPVs) associated with malignant genital lesions has not been studied because of the lack of an in vitro system and the unavailability of virions. We have now used virus-like particles (VLPs) of HPV type 33 to analyze the initial events in the interaction of the HPV capsid with cell lines. Binding of VLPs to HeLa cells was observed in biochemical assays and by immunofluorescence. VLP binding was inhibited by antisera raised against VLPs but not by monoclonal antibodies recognizing either L1 or L2 epitopes accessible on VLPs. Under saturating conditions, approximately 2 x 10(4) VLPs were bound per cell, with a dissociation constant of about 100 pM…

Assembly and Translocation of Papillomavirus Capsid Proteins

2002

ABSTRACT The major and minor capsid proteins of polyomavirus are preassembled in the cytoplasm and translocated to the nucleus only as a VP1-VP2/VP3 complex. In this study, we describe independent nuclear translocation of the L1 major protein and the L2 minor capsid protein of human papillomavirus type 33 by several approaches. First, we observed that expression and nuclear translocation of L2 in natural lesions precede expression of L1. Second, using a cell culture system for coexpression, we found that accumulation of L2 in nuclear domain 10 (ND10) subnuclear structures precedes L1 by several hours. In contrast, complexes of L2 and mutants of L1 forced to assemble in the cytoplasm are tra…

Nuclear localization but not PML protein is required for incorporation of the papillomavirus minor capsid protein L2 into virus-like particles.

2004

ABSTRACT Recent reports suggest that nuclear domain(s) 10 (ND10) is the site of papillomavirus morphogenesis. The viral genome replicates in or close to ND10. In addition, the minor capsid protein, L2, accumulates in these subnuclear structures and recruits the major capsid protein, L1. We have now used cell lines deficient for promyelocytic leukemia (PML) protein, the main structural component of ND10, to study the role of this nuclear protein for L2 incorporation into virus-like particles (VLPs). L2 expressed in PML protein knockout (PML −/− ) cells accumulated in nuclear dots, which resemble L2 aggregates forming at ND10 in PML protein-containing cells. These L2 assemblies also attracted…

DNA-induced structural changes in the papillomavirus capsid.

2001

ABSTRACT Human papillomavirus capsid assembly requires intercapsomeric disulfide bonds between molecules of the major capsid protein L1. Virions isolated from naturally occurring lesions have a higher degree of cross-linking than virus-like particles (VLPs), which have been generated in eukaryotic expression systems. Here we show that DNA encapsidation into VLPs leads to increased cross-linking between L1 molecules comparable to that seen in virions. A higher trypsin resistance, indicating a tighter association of capsomeres through DNA interaction, accompanies this structural change.