Home About us Contact
|
Home About us Contact | ||
|
|
||
Level Reveal (level + reveal)
Selected AbstractsPlant profilin isovariants are distinctly regulated in vegetative and reproductive tissuesCYTOSKELETON, Issue 1 2002Muthugapatti K. Kandasamy Abstract Profilin is a low-molecular weight, actin monomer-binding protein that regulates the organization of actin cytoskeleton in eukaryotes, including higher plants. Unlike the simple human or yeast systems, the model plant Arabidopsis has an ancient and highly divergent multi-gene family encoding five distinct profilin isovariants. Here we compare and characterize the regulation of these profilins in different organs and during microspore development using isovariant-specific monoclonal antibodies. We show that PRF1, PRF2, and PRF3 are constitutive, being strongly expressed in all vegetative tissues at various stages of development. These profilin isovariants are also predominant in ovules and microspores at the early stages of microsporogenesis. In contrast, PRF4 and PRF5 are late pollen-specific and are not detectable in other cell types of the plant body including microspores and root hairs. Immunocytochemical studies at the subcellular level reveal that both the constitutive and pollen-specific profilins are abundant in the cytoplasm. In vegetative cell types, such as root apical cells, profilins showed localization to nuclei in addition to the cytoplasmic staining. The functional diversity of profilin isovariants is discussed in light of their spatio-temporal regulation during vegetative development, pollen maturation, and pollen tube growth. Cell Motil. Cytoskeleton 52:22,32, 2002. © 2002 Wiley-Liss, Inc. [source] ,Nothing is permanent but change', , antigenic variation in persistent bacterial pathogensCELLULAR MICROBIOLOGY, Issue 12 2009Guy H. Palmer Summary Pathogens persist in immunocompetent mammalian hosts using various strategies, including evasion of immune effectors by antigenic variation. Among highly antigenically variant bacteria, gene conversion is used to generate novel expressed variants from otherwise silent donor sequences. Recombination using oligonucleotide segments from multiple donors is a combinatorial mechanism that tremendously expands the variant repertoire, allowing thousands of variants to be generated from a relatively small donor pool. Three bacterial pathogens, each encoded by a small genome (< 1.2 Mb), illustrate this variant generating capacity and its role in persistent infection. Borrelia burgdorferi VlsE diversity is encoded and expressed on a linear plasmid required for persistence and recent experiments have demonstrated that VlsE recombination is necessary for persistence in the immunocompetent host. In contrast, both Treponema pallidum TprK and Anaplasma marginale Msp2 expression sites and donors are chromosomally encoded. Both T. pallidum and A. marginale generate antigenic variants in vivo in individual hosts and studies at the population level reveal marked strain diversity in the variant repertoire that may underlie pathogen strain structure and the capacity for re-infection and heterologous strain superinfection. Here, we review gene conversion in bacterial antigenic variation and discuss the short- and long-term selective pressures that shape the variant repertoire. [source] Comparison of effects of in vivo nitrogen dioxide exposure starting from different periods on alveolar macrophage activity, assessed by a chemiluminescence technique in Brown-Norway ratsLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 4 2006Takashi Kumae Abstract Nitrogen dioxide (NO2) has been extensively studied for its immune modulating effects on pulmonary cells. Alveolar macrophages (AMs) play an important role in pulmonary immunity. The Brown-Norway (BN) rat has been studied as a high-risk model of allergic diseases. In this study, BN rats were exposed to NO2 from the embryonic or weanling period (EP or WP, respectively). To evaluate the effects of NO2 exposure on pulmonary immunity, the activity levels of rat AMs were assessed as reactive oxygen species-generating capacity, measured by a chemiluminescence (CL) technique, and as cytokine-producing ability. Except for 0.2 ppm of NO2 exposure, the CL responses of AMs obtained from the WP group at 12 weeks old were suppressed significantly. Changes of the cytokine-producing levels suggest that inflammatory reactions are terminated at 12 weeks in the EP group. Correlations between the CL responses and the cytokine levels reveal that NO2 exposure may modulate the direction of AM activation. The CL technique is thought to be useful to evaluate changes in AM activity. In this study, the results suggest that, using the high-risk model of allergic diseases, NO2 exposure from the weanling period has stronger effects on AM activity.Copyright © 2006 John Wiley & Sons, Ltd. [source] Cloning of MMP-26FEBS JOURNAL, Issue 11 2000A novel matrilysin-like proteinase A cDNA encoding a novel human matrix metalloproteinase (MMP), named MMP-26, was cloned from fetal cDNA. The deduced 261-amino-acid sequence is homologous to macrophage metalloelastase (51.8% identity). It includes only the minimal characteristic features of the MMP family: a signal peptide, a prodomain and a catalytic domain. As with MMP-7, this new MMP does not comprise the hemopexin domain, which is believed to be involved in substrate recognition. A study of MMP-26 mRNA steady states levels reveals, among the tissue examined, a specific expression in placenta. MMP-26 mRNA could also be detected in several human cell lines such as HEK 293 kidney cells and HFB1 lymphoma cells. Recombinant MMP-26 was produced in mammalian cells and used to demonstrate a proteolytic activity of the enzyme on gelatin and ,-casein. [source] | |||||||||||||