bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of Fucose-Containing Xyloglucans in Cell Walls of the mur1 Mutant of Arabidopsis
Authors: Freshour Glenn , Bonin Christopher P. , Reiter Wolf-Dieter , Albersheim Peter , Darvill Alan G. , Hahn Michael G. 
Published: April 2003

Abstract
The monoclonal antibody, CCRC-M1, which recognizes a fucose (Fuc)-containing epitope found principally in the cell wall polysaccharide xyloglucan, was used to determine the distribution of this epitope throughout the mur1 mutant of Arabidopsis. Immunofluorescent labeling of whole seedlings revealed that mur1 root hairs are stained heavily by CCRC-M1, whereas the body of the root remains unstained or only lightly stained. Immunogold labeling showed that CCRC-M1 labeling within themur1 root is specific to particular cell walls and cell types. CCRC-M1 labels all cell walls at the apex of primary roots 2 d and older and the apices of mature lateral roots, but does not bind to cell walls in lateral root initials. Labeling with CCRC-M1 decreases in mur1 root cells that are undergoing rapid elongation growth such that, in the mature portions of primary and lateral roots, only the walls of pericycle cells and the outer walls of epidermal cells are labeled. Growth of the mutant on Fuc-containing media restores wild-type labeling, where all cell walls are labeled by the CCRC-M1 antibody. No labeling was observed in mur1hypocotyls, shoots, or leaves; stipules are labeled. CCRC-M1 does label pollen grains within anthers and pollen tube walls. These results suggest the Fuc destined for incorporation into xyloglucan is synthesized using one or the other or both isoforms of GDP-d-mannose 4,6-dehydratase, depending on the cell type and/or developmental state of the cell.
Cloning, Expression, and Characterization of Sorbitol Transporters from Developing Sour Cherry Fruit and Leaf Sink Tissues
Authors: Gao Zhifang , Maurousset Laurence , Lemoine Remi , Yoo Sang-Dong , van Nocker Steven , Loescher Wayne 
Published: April 2003

AbstractThe acyclic polyol sorbitol is a primary photosynthetic product and the principal photosynthetic transport substance in many economically important members of the family Rosaceace (e.g. almond [Prunus dulcis (P. Mill.) D.A. Webber], apple [Malus pumila P. Mill.], cherry [Prunus spp.], peach [Prunus persicaL. Batsch], and pear [Pyrus communis]). To understand key steps in long-distance transport and particularly partitioning and accumulation of sorbitol in sink tissues, we have cloned two sorbitol transporter genes (PcSOT1 andPcSOT2) from sour cherry (Prunus cerasus) fruit tissues that accumulate large quantities of sorbitol. Sorbitol uptake activities and other characteristics were measured by heterologous expression of PcSOT1 andPcSOT2 in yeast (Saccharomyces cerevisiae). Both genes encode proton-dependent, sorbitol-specific transporters with similar affinities (K m sorbitol of 0.81 mm for PcSOT1 and 0.64 mm for PcSOT2). Analyses of gene expression of these transporters, however, suggest different roles during leaf and fruit development. PcSOT1 is expressed throughout fruit development, but especially when growth and sorbitol accumulation rates are highest. In leaves, PcSOT1 expression is highest in young, expanding tissues, but substantially less in mature leaves. In contrast, PcSOT2 is mainly expressed only early in fruit development and not in leaves. Compositional analyses suggest that transport mediated by PcSOT1 and PcSOT2 plays a major role in sorbitol and dry matter accumulation in sour cherry fruits. Presence of these transporters and the high fruit sorbitol concentrations suggest that there is an apoplastic step during phloem unloading and accumulation in these sink tissues. Expression of PcSOT1 in young leaves before completion of the transition from sink to source is further evidence for a role in determining sink activity.
Breakdown of Self-Incompatibility in a Natural Population ofPetunia axillaris Caused by Loss of Pollen Function
Authors: Tsukamoto Tatsuya , Ando Toshio , Takahashi Koichi , Omori Takahiro , Watanabe Hitoshi , Kokubun Hisashi , Marchesi Eduardo , Kao Teh-hui 
Published: April 2003

Abstract
Although Petunia axillaris subsp.axillaris is described as a self-incompatible taxon, some of the natural populations we have identified in Uruguay are composed of both self-incompatible and self-compatible plants. Here, we studied the self-incompatibility (SI) behavior of 50 plants derived from such a mixed population, designated U83, and examined the cause of the breakdown of SI. Thirteen plants were found to be self-incompatible, and the other 37 were found to be self-compatible. A total of 14 S-haplotypes were represented in these 50 plants, including two that we had previously identified from another mixed population, designated U1. All the 37 self-compatible plants carried either an SC1- or anSC2-haplotype.SC1SC1andSC2SC2homozygotes were generated by self-pollination of two of the self-compatible plants, and they were reciprocally crossed with 40 self-incompatible S-homozygotes (S1S1throughS40S40) generated from plants identified from three mixed populations, including U83. TheSC1SC1homozygote was reciprocally compatible with all the genotypes examined. The SC2SC2homozygote accepted pollen from all but theS17S17homozygote (identified from the U1 population), but theS17S17homozygote accepted pollen from theSC2SC2homozygote. cDNAs encoding SC2- and S17-RNases were cloned and sequenced, and their nucleotide sequences were completely identical. Analysis of bud-selfed progeny of heterozygotes carrying SC1 orSC2 showed that the SI behavior of S C1 and S C2 was identical to that of S C1 andS C2 homozygotes, respectively. All these results taken together suggested that the S C2-haplotype was a mutant form of the S 17-haplotype, with the defect lying in the pollen function. The possible nature of the mutation is discussed.
Arabidopsis haiku Mutants Reveal New Controls of Seed Size by Endosperm
Authors: Garcia Damien , Saingery Virginie , Chambrier Pierre , Mayer Ulrike , Jürgens Gerd , Berger Frédéric 
Published: April 2003

Abstract
In flowering plants, maternal seed integument encloses the embryo and the endosperm, which are both derived from double fertilization. Although the development of these three components must be coordinated, we have limited knowledge of mechanisms involved in such coordination. The endosperm may play a central role in these mechanisms as epigenetic modifications of endosperm development, via imbalance of dosage between maternal and paternal genomes, affecting both the embryo and the integument. To identify targets of such epigenetic controls, we designed a genetic screen in Arabidopsis for mutants that phenocopy the effects of dosage imbalance in the endosperm. The two mutants haiku 1 andhaiku 2 produce seed of reduced size that resemble seed with maternal excess in the maternal/paternal dosage. Homozygoushaiku seed develop into plants indistinguishable from wild type. Each mutation is sporophytic recessive, and double-mutant analysis suggests that both mutations affect the same genetic pathway. The endosperm of haiku mutants shows a premature arrest of increase in size that causes precocious cellularization of the syncytial endosperm. Reduction of seed size in haikuresults from coordinated reduction of endosperm size, embryo proliferation, and cell elongation of the maternally derived integument. We present further evidence for a control of integument development mediated by endosperm-derived signals.
Insertional Inactivation of the Methionine S-Methyltransferase Gene Eliminates the S-Methylmethionine Cycle and Increases the Methylation Ratio
Authors: Kocsis Michael G. , Ranocha Philippe , Gage Douglas A. , Simon Eric S. , Rhodes David , Peel Gregory J. , Mellema Stefan , Saito Kazuki , Awazuhara Motoko , Li Changjiang , Meeley Robert B. , Tarczynski Mitchell C. , Wagner Conrad , Hanson Andrew D. 
Published: April 2003

Abstract
Methionine (Met) S-methyltransferase (MMT) catalyzes the synthesis of S-methyl-Met (SMM) from Met andS-adenosyl-Met (Ado-Met). SMM can be reconverted to Met by donating a methyl group to homocysteine (homo-Cys), and concurrent operation of this reaction and that mediated by MMT sets up the SMM cycle. SMM has been hypothesized to be essential as a methyl donor or as a transport form of sulfur, and the SMM cycle has been hypothesized to guard against depletion of the free Met pool by excess Ado-Met synthesis or to regulate Ado-Met level and hence the Ado-Met toS-adenosylhomo-Cys ratio (the methylation ratio). To test these hypotheses, we isolated insertional mmtmutants of Arabidopsis and maize (Zea mays). Both mutants lacked the capacity to produce SMM and thus had no SMM cycle. They nevertheless grew and reproduced normally, and the seeds of the Arabidopsis mutant had normal sulfur contents. These findings rule out an indispensable role for SMM as a methyl donor or in sulfur transport. The Arabidopsis mutant had significantly higher Ado-Met and lowerS-adenosylhomo-Cys levels than the wild type and consequently had a higher methylation ratio (13.8 versus 9.5). Free Met and thiol pools were unaltered in this mutant, although there were moderate decreases (of 30%–60%) in free serine, threonine, proline, and other amino acids. These data indicate that the SMM cycle contributes to regulation of Ado-Met levels rather than preventing depletion of free Met.
Antimicrobial Growth Promoters Used in Animal Feed: Effects of Less Well Known Antibiotics on Gram-Positive Bacteria
Authors: Butaye Patrick , Devriese Luc A. , Haesebrouck Freddy 
Published: April 2003

SUMMARYThere are not many data available on antibiotics used solely in animals and almost exclusively for growth promotion. These products include bambermycin, avilamycin, efrotomycin, and the ionophore antibiotics (monensin, salinomycin, narasin, and lasalocid). Information is also scarce for bacitracin used only marginally in human and veterinary medicine and for streptogramin antibiotics. The mechanisms of action of and resistance mechanisms against these antibiotics are described. Special emphasis is given to the prevalence of resistance among gram-positive bacteria isolated from animals and humans. Since no susceptibility breakpoints are available for most of the antibiotics discussed, an alternative approach to the interpretation of MICs is presented. Also, some pharmacokinetic data and information on the influence of these products on the intestinal flora are presented.
Microbial Infections, Immunomodulation, and Drugs of Abuse
Authors: Friedman Herman , Newton Catherine , Klein Thomas W. 
Published: April 2003

SUMMARYThe use of recreational drugs of abuse has generated serious health concerns. There is a long-recognized relationship between addictive drugs and increased levels of infections. Studies of the mechanisms of actions of these drugs became more urgent with the advent of AIDS and its correlation with abused substances. The nature and mechanisms of immunomodulation by marijuana, opiates, cocaine, nicotine, and alcohol are described in this review. Recent studies of the effects of opiates or marijuana on the immune system have demonstrated that they are receptor mediated, occurring both directly via specific receptors on immune cells and indirectly through similar receptors on cells of the nervous system. Findings are also discussed that demonstrate that cocaine and nicotine have similar immunomodulatory effects, which are also apparently receptor mediated. Finally, the nature and mechanisms of immunomodulation by alcohol are described. Although no specific alcohol receptors have been identified, it is widely recognized that alcohol enhances susceptibility to opportunistic microbes. The review covers recent studies of the effects of these drugs on immunity and on increased susceptibility to infectious diseases, including AIDS.
Low Occurrence of Pathogenic
Yersinia enterocolitica
in Clinical, Food, and Environmental Samples: a Methodological Problem
Authors: Fredriksson-Ahomaa Maria , Korkeala Hannu 
Published: April 2003

SUMMARY
While Yersinia enterocolitica is an important pathogen, which can cause yersiniosis in humans and animals, its epidemiology remains obscure. The pig is the major reservoir of pathogenic Y. enterocolitica of bioserotype 4/O:3, the most common type found in humans. Y. enterocolitica is thought to be a significant food-borne pathogen, although pathogenic isolates have seldom been recovered from foods. The low isolation rate of this pathogenic bacterium in natural samples, including clinical, food, and environmental samples, may be due to the limited sensitivity of culture methods. During the last decade, numerous DNA-based methods, such as PCR and colony hybridization assays, have been designed to detect pathogenic Y. enterocolitica in natural samples more rapidly and with better sensitivity than can be achieved by culture methods. In addition, the occurrence of pathogenic Y. enterocolitica in natural samples is clearly higher with PCR than with culture methods. The methods available for detection of pathogenic Y. enterocolitica in natural samples are reviewed in this article.
Importance of Respiratory Viruses in Acute Otitis Media
Authors: Heikkinen Terho , Chonmaitree Tasnee 
Published: April 2003

SUMMARYAcute otitis media is usually considered a simple bacterial infection that is treated with antibiotics. However, ample evidence derived from studies ranging from animal experiments to extensive clinical trials supports a crucial role for respiratory viruses in the etiology and pathogenesis of acute otitis media. Viral infection of the upper respiratory mucosa initiates the whole cascade of events that finally leads to the development of acute otitis media as a complication. The pathogenesis of acute otitis media involves a complex interplay between viruses, bacteria, and the host’s inflammatory response. In a substantial number of children, viruses can be found in the middle-ear fluid either alone or together with bacteria, and recent studies indicate that at least some viruses actively invade the middle ear. Viruses appear to enhance the inflammatory process in the middle ear, and they may significantly impair the resolution of otitis media. Prevention of the predisposing viral infection by vaccination against the major viruses would probably be the most effective way to prevent acute otitis media. Alternatively, early treatment of the viral infection with specific antiviral agents would also be effective in reducing the occurrence of acute otitis media.
Toxocariasis: Clinical Aspects, Epidemiology, Medical Ecology, and Molecular Aspects
Authors: Despommier Dickson 
Published: April 2003

SUMMARYToxocariasis is caused by a series of related nematode species (ascarids) that routinely infect dogs and cats throughout the world. The eggs from these ascarids are common environmental contaminants of human habitation, due largely to the fact that many kinds of dogs and cats serve as pets, while countless others run wild throughout the streets of most urban centers. The eggs, present in dog and cat feces, become infectious within weeks after they are deposited in the local environment (e.g., sandboxes, city parks, and public beaches, etc.). Humans, particularly children, frequently ingest these eggs by accident and become infected. Infection in humans, in contrast to their definitive hosts, remains occult, often resulting in disease caused by the migrating larval stages. Visceral larva migrans (VLM) and ocular larva migrans (OLM) are two clinical manifestations that result in definable syndromes and present as serious health problems wherever they occur. Diagnosis and treatment of VLM and OLM are difficult. These issues are summarized in this review, with emphasis on the ecology of transmission and control of spread to both humans and animals through public health initiatives employing treatment of pets and environmental intervention strategies that limit the areas that dogs and cats are allowed within the confines of urban centers.
Acanthamoebaspp. as Agents of Disease in Humans
Authors: Marciano-Cabral Francine , Cabral Guy 
Published: April 2003

SUMMARYAcanthamoeba spp. are free-living amebae that inhabit a variety of air, soil, and water environments. However, these amebae can also act as opportunistic as well as nonopportunistic pathogens. They are the causative agents of granulomatous amebic encephalitis and amebic keratitis and have been associated with cutaneous lesions and sinusitis. Immuno compromised individuals, including AIDS patients, are particularly susceptible to infections with Acanthamoeba. The immune defense mechanisms that operate against Acanthamoeba have not been well characterized, but it has been proposed that both innate and acquired immunity play a role. The ameba's life cycle includes an active feeding trophozoite stage and a dormant cyst stage. Trophozoites feed on bacteria, yeast, and algae. However, both trophozoites and cysts can retain viable bacteria and may serve as reservoirs for bacteria with human pathogenic potential. Diagnosis of infection includes direct microscopy of wet mounts of cerebrospinal fluid or stained smears of cerebrospinal fluid sediment, light or electron microscopy of tissues, in vitro cultivation of Acanthamoeba, and histological assessment of frozen or paraffin-embedded sections of brain or cutaneous lesion biopsy material. Immunocytochemistry, chemifluorescent dye staining, PCR, and analysis of DNA sequence variation also have been employed for laboratory diagnosis. Treatment of Acanthamoeba infections has met with mixed results. However, chlorhexidine gluconate, alone or in combination with propamidene isethionate, is effective in some patients. Furthermore, effective treatment is complicated since patients may present with underlying disease and Acanthamoeba infection may not be recognized. Since an increase in the number of cases of Acanthamoeba infections has occurred worldwide, these protozoa have become increasingly important as agents of human disease.
Nuclear Import of Zinc Binuclear Cluster Proteins Proceeds through Multiple, Overlapping Transport Pathways
Authors: Nikolaev Igor , Cochet Marie-Françoise , Felenbok Béatrice 
Published: April 2003

ABSTRACT

In
Aspergillus nidulans
, the high transcriptional level of the ethanol utilization pathway genes (
alc
) is regulated by the specific activator AlcR. Here we have analyzed the mechanism of the nuclear import of AlcR, as well as that of other proteins belonging to the Zn
2
Cys
6
binuclear cluster family. The nuclear localization signal of AlcR maps within the N-terminal 75 amino acid residues and overlaps with its DNA-binding domain. It consists of five clusters rich in basic residues. Four of them are necessary and sufficient for nuclear targeting. The first two basic regions are crucial for both nuclear localization and recognition of AlcR-specific DNA targets. This nuclear localization signal (NLS) motif is recognized by the nuclear transport machinery of
Saccharomyces cerevisiae
and requires both Ran/Gsp1p activity and specific transport receptors. AlcR can be imported into nuclei via multiple transport pathways mediated by a distinct set of karyopherins composed of Kap104p, Sxm1p, and Nmd5p transport receptors. The two former karyopherins interact with the NLS of AlcR directly. Other Zn binuclear cluster proteins from
S. cerevisiae
, such as Gal4p and Pdr3p, also appear to be transported to the nuclei in a nonclassical, importin-α-independent manner and can share common importin β receptors.
Exportin 1 Mediates Nuclear Export of the Kinetoplastid Spliced Leader RNA
Authors: Zeiner Gusti M. , Sturm Nancy R. , Campbell David A. 
Published: April 2003

ABSTRACTThe kinetoplastid protozoan spliced leader (SL) RNA is the common substrate pre-mRNA utilized in alltrans-splicing reactions. Here we show by fluorescence in situ hybridization that the SL RNA is present in the cytoplasm ofLeishmania tarentolaeandTrypanosoma brucei. Treatment with the karyopherin-specific inhibitor leptomycin B was toxic toT. bruceiand eliminated the cytoplasmic SL RNA, suggesting that cytoplasmic SL RNA was dependent on the nuclear exporter exportin 1 (XPO1). Ectopic expression of xpo1 with a C506S mutation inT. bruceiconferred resistance to leptomycin B. A reduction in SL RNA 3′ extension removal and 5′ methylation of nucleotide U4was observed in wild-typeT. bruceitreated with leptomycin B, suggesting that the cytoplasmic stage is necessary for SL RNA biogenesis. This study demonstrates spatial and mechanistic similarities between the posttranscriptional trafficking of the kinetoplastid protozoan SL RNA and the metazoancis-spliceosomal small nuclear RNAs.
A Circadian Oscillator in
Aspergillus
spp
.
Regulates Daily Development and Gene Expression
Authors: Greene Andrew V. , Keller Nancy , Haas Hubertus , Bell-Pedersen Deborah 
Published: April 2003

ABSTRACT

We have established the presence of a circadian clock in
Aspergillus flavus
and
Aspergillus nidulans
by morphological and molecular assays, respectively. In
A. flavus
, the clock regulates an easily assayable rhythm in the development of sclerotia, which are large survival structures produced by many fungi. This developmental rhythm exhibits all of the principal clock properties. The rhythm is maintained in constant environmental conditions with a period of 33 h at 30°C, it can be entrained by environmental signals, and it is temperature compensated. This endogenous 33-h period is one of the longest natural circadian rhythms reported for any organism, and this likely contributes to some unique responses of the clock to environmental signals. In
A. nidulans
, no obvious rhythms in development are apparent. However, a free running and entrainable rhythm in the accumulation of
gpdA
mRNA (encoding glyceraldehyde-3-phosphate dehydrogenase) is observed, suggesting the presence of a circadian clock in this species. We are unable to identify an
Aspergillus
ortholog of
frequency
, a gene required for normal circadian rhythmicity in
Neurospora crassa
. Together, our data indicate the existence of an
Aspergillus
circadian clock, which has properties that differ from that of the well-described clock of
N. crassa.
Rapamycin Mimics the Incompatibility Reaction in the FungusPodospora anserina
Authors: Dementhon Karine , Paoletti Mathieu , Pinan-Lucarré Bérangère , Loubradou-Bourges Nathalie , Sabourin Martine , Saupe Sven J. , Clavé Corinne 
Published: April 2003

ABSTRACTIn filamentous fungi, a programmed cell death (PCD) reaction occurs when cells of unlike genotype fuse. This reaction is caused by genetic differences at specific loci termedhetloci (for heterokaryon incompatibility). Although severalhetgenes have been characterized, the mechanism of this cell death reaction and its relation to PCD in higher eukaryotes remains largely unknown. InPodospora anserina, genes induced during the cell death reaction triggered by thehet-R het-Vinteraction have been identified and termedidigenes. Herein, we describe the functional characterization of oneidigene (idi-1) and explore the connection between incompatibility and the response to nutrient starvation. We show that IDI-1 is a cell wall protein which localizes at the septum during normal growth. We found that induction ofidi-1and of the other knownidigenes is not specific of the incompatibility reaction. Theidigenes are induced upon nitrogen and carbon starvation and by rapamycin, a specific inhibitor of the TOR kinase pathway. The cytological hallmarks ofhet-R het-Vincompatibility (increased septation, vacuolization, coalescence of lipid droplets, induction of autophagy, and cell death) are also observed during rapamycin treatment. Globally the cytological alterations and modifications in gene expression occurring during the incompatibility reaction are similar to those observed during starvation or rapamycin treatment.