bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interactions among PIN-FORMED and P-Glycoprotein Auxin Transporters in Arabidopsis
Authors: Blakeslee Joshua J. , Bandyopadhyay Anindita , Lee Ok Ran , Mravec Jozef , Titapiwatanakun Boosaree , Sauer Michael , Makam Srinivas N. , Cheng Yan , Bouchard Rodolphe , Adamec Jiří , Geisler Markus , Nagashima Akitomo , Sakai Tatsuya , Martinoia Enrico , Friml Jiří , Peer Wendy Ann , Murphy Angus S. 
Published: January 2007

Abstract
Directional transport of the phytohormone auxin is established primarily at the point of cellular efflux and is required for the establishment and maintenance of plant polarity. Studies in whole plants and heterologous systems indicate that PIN-FORMED (PIN) and P-glycoprotein (PGP) transport proteins mediate the cellular efflux of natural and synthetic auxins. However, aromatic anion transport resulting from PGP and PIN expression in nonplant systems was also found to lack the high level of substrate specificity seen in planta. Furthermore, previous reports that PGP19 stabilizes PIN1 on the plasma membrane suggested that PIN–PGP interactions might regulate polar auxin efflux. Here, we show that PGP1 and PGP19 colocalized with PIN1 in the shoot apex in Arabidopsis thaliana and with PIN1 and PIN2 in root tissues. Specific PGP–PIN interactions were seen in yeast two-hybrid and coimmunoprecipitation assays. PIN–PGP interactions appeared to enhance transport activity and, to a greater extent, substrate/inhibitor specificities when coexpressed in heterologous systems. By contrast, no interactions between PGPs and the AUXIN1 influx carrier were observed. Phenotypes of pin and pgp mutants suggest discrete functional roles in auxin transport, but pin pgp mutants exhibited phenotypes that are both additive and synergistic. These results suggest that PINs and PGPs characterize coordinated, independent auxin transport mechanisms but also function interactively in a tissue-specific manner.
In Vivo Participation of Red Chlorophyll Catabolite Reductase in Chlorophyll Breakdown
Authors: Pružinská Adriana , Anders Iwona , Aubry Sylvain , Schenk Nicole , Tapernoux-Lüthi Esther , Müller Thomas , Kräutler Bernhard , Hörtensteiner Stefan 
Published: January 2007

Abstract
A central reaction of chlorophyll breakdown, porphyrin ring opening of pheophorbide a to the primary fluorescent chlorophyll catabolite (pFCC), requires pheophorbide a oxygenase (PAO) and red chlorophyll catabolite reductase (RCCR), with red chlorophyll catabolite (RCC) as a presumably PAO-bound intermediate. In subsequent steps, pFCC is converted to different fluorescent chlorophyll catabolites (FCCs) and nonfluorescent chlorophyll catabolites (NCCs). Here, we show that RCCR-deficient Arabidopsis thaliana accumulates RCC and three RCC-like pigments during senescence, as well as FCCs and NCCs. We also show that the stereospecificity of Arabidopsis RCCR is defined by a small protein domain and can be reversed by a single Phe-to-Val exchange. Exploiting this feature, we prove the in vivo participation of RCCR in chlorophyll breakdown. After complementation of RCCR mutants with RCCRs exhibiting alternative specificities, patterns of chlorophyll catabolites followed the specificity of complementing RCCRs. Light-dependent leaf cell death observed in different RCCR-deficient lines strictly correlated with the accumulation of RCCs and the release of singlet oxygen, and PAO induction preceded lesion formation. These findings suggest that RCCR absence causes leaf cell death as a result of the accumulation of photodynamic RCC. We conclude that RCCR (together with PAO) is required for the detoxification of chlorophyll catabolites and discuss the biochemical role(s) for this enzyme.
NAC Transcription Factors, NST1 and NST3, Are Key Regulators of the Formation of Secondary Walls in Woody Tissues ofArabidopsis
Authors: Mitsuda Nobutaka , Iwase Akira , Yamamoto Hiroyuki , Yoshida Masato , Seki Motoaki , Shinozaki Kazuo , Ohme-Takagi Masaru 
Published: January 2007

AbstractWood is formed by the successive addition of secondary xylem, which consists of cells with a conspicuously thickened secondary wall composed mainly of lignin and cellulose. Several genes involved in lignin and cellulose biosynthesis have been characterized, but the factors that regulate the formation of secondary walls in woody tissues remain to be identified. In this study, we show that plant-specific transcription factors, designated NAC SECONDARY WALL THICKENING PROMOTING FACTOR1 (NST1) and NST3, are key regulators of the formation of secondary walls in woody tissues of Arabidopsis thaliana. In nst1-1 nst3-1 double knockout plants, the secondary wall thickenings in interfascicular fibers and secondary xylem, except for vascular vessels, were completely suppressed without affecting formation of cells destined to be woody tissues. Conversely, as shown previously for NST1, overexpression of NST3 induced ectopic secondary wall thickenings in various aboveground tissues. Furthermore, the expression of chimeric repressors derived from NST1 and NST3 suppressed secondary wall thickenings in the presumptive interfascicular fibers. Because putative orthologs of NST1 and NST3 are present in the genome of poplar, our results suggest that they are also key regulators of the formation of secondary walls in woody plants and could be used as a tool for the genetic engineering of wood and its derivatives.
TheArabidopsis irregular xylem8Mutant Is Deficient in Glucuronoxylan and Homogalacturonan, Which Are Essential for Secondary Cell Wall Integrity
Authors: Persson Staffan , Caffall Kerry Hosmer , Freshour Glenn , Hilley Matthew T. , Bauer Stefan , Poindexter Patricia , Hahn Michael G. , Mohnen Debra , Somerville Chris 
Published: January 2007

AbstractThe secondary cell wall in higher plants consists mainly of cellulose, lignin, and xylan and is the major component of biomass in many species. The Arabidopsis thaliana irregular xylem8 (irx8) mutant is dwarfed and has a significant reduction in secondary cell wall thickness. IRX8 belongs to a subgroup of glycosyltransferase family 8 called the GAUT1-related gene family, whose members include GAUT1, a homogalacturonan galacturonosyltransferase, and GAUT12 (IRX8). Here, we use comparative cell wall analyses to show that the irx8 mutant contains significantly reduced levels of xylan and homogalacturonan. Immunohistochemical analyses confirmed that the level of xylan was significantly reduced in the mutant. Structural fingerprinting of the cell wall polymers further revealed that irx8 is deficient in glucuronoxylan. To explore the biological function of IRX8, we crossed irx8 with irx1 (affecting cellulose synthase 8). The homozygous irx1 irx8 exhibited severely dwarfed phenotypes, suggesting that IRX8 is essential for cell wall integrity during cellulose deficiency. Taken together, the data presented show that IRX8 affects the level of glucuronoxylan and homogalacturonan in higher plants and that IRX8 provides an important link between the xylan polymer and the secondary cell wall matrix and directly affects secondary cell wall integrity.
SLocus Genes and the Evolution of Self-Fertility inArabidopsis thaliana
Authors: Sherman-Broyles Sue , Boggs Nathan , Farkas Agnes , Liu Pei , Vrebalov Julia , Nasrallah Mikhail E. , Nasrallah June B. 
Published: January 2007

AbstractLoss of self-incompatibility (SI) in Arabidopsis thaliana was accompanied by inactivation of genes required for SI, including S-LOCUS RECEPTOR KINASE (SRK) and S-LOCUS CYSTEINE-RICH PROTEIN (SCR), coadapted genes that constitute the SI specificity-determining S haplotype. Arabidopsis accessions are polymorphic for ΨSRK and ΨSCR, but it is unknown if the species harbors structurally different S haplotypes, either representing relics of ancestral functional and structurally heteromorphic S haplotypes or resulting from decay concomitant with or subsequent to the switch to self-fertility. We cloned and sequenced the S haplotype from C24, in which self-fertility is due solely to S locus inactivation, and show that this haplotype was produced by interhaplotypic recombination. The highly divergent organization and sequence of the C24 and Columbia-0 (Col-0) S haplotypes demonstrate that the A. thaliana S locus underwent extensive structural remodeling in conjunction with a relaxation of selective pressures that once preserved the integrity and linkage of coadapted SRK and SCR alleles. Additional evidence for this process was obtained by assaying 70 accessions for the presence of C24- or Col-0–specific sequences. Furthermore, analysis of SRK and SCR polymorphisms in these accessions argues against the occurrence of a selective sweep of a particular allele of SCR, as previously proposed.
EFFECTS OF EVENING ACTIVITY ON EARLY NIGHT SLEEP
Authors: Hauri Peter 
Published: February 2007

ABSTRACTThis study was designed to determine the effects of presleep activity on a variety of physiological variables during 3½ hrs of subsequent sleep. Three presleep conditions were investigated for each of 15 Ss:6 hrs of strenuous physical exercise, 6 hrs of concentrated studying, and 6 hrs of relaxation, i.e. watching TV, listening to records, and reading magazines. The following variables were recorded during a 3½ hr sleep period: EEG, EOG, body movements, heart rate, respiratory rate, peripheral pulse voltime, phasic vasoconstrictions, rectal temperature, and rapid variations in skin potential.None of the experimental presleep activities influenced the EEG cycle during the 3½ hrs of sleep. In particular, there were no significant differences in the following measurements as a result of presleep condition: amount of REMP time, time to first REMP, amount of delta sleep, time to first delta sleep, amount of stage 2 sleep, or number of sleep stage changes. These findings indicate a surprising stability of the sleep stage cycle vis a vis the markedly different evening activities.Physiological arousal after exercise decreased rapidly until it was no longer distinguishable from the base levels following studying or relaxation. A tendency to approach these base levels was observed even in heart rate, a variable which remained elevated after exercise throughout the 3½ hrs of sleep. For none of the physiological variables was the level of physiological arousal during sleep inversely related to the level of physiological arousal during wakefulness.Relating EEG sleep stages to the other variables of this study, it was observed that on nights when respiratory rate was high there was more delta sleep and less stage 2 sleep. Also, respiratory minima were most often found during stage 2 sleep immediately following a REMP, and respiratory maxima during NREM sleep were significantly associated with delta sleep. These results support Bülow's (1963) proposal that a close coupling exists between respiratory centers and those neural structures that regulate EEG arousal.
Cumulative Effects of Sleep Restriction on Daytime Sleepiness
Authors: Carskadon Mary A. , Dement William C. 
Published: February 2007

ABSTRACTSleep and daytime sleepiness were evaluated in 10 young adult subjects to determine whether restricting nocturnal step by a constant amount produces cumulative impairment. Subjects were studied for 12 consecutive days, including 3 baseline days with a 10‐hr time in bed, 7 days with sleep restricted to 5 hrs, and 2 recovery days. In 5 subjects, recovery included a 10‐hr time in bed; in the remaining subject, recovery induced a 5‐hr time in bed with a 1‐hr daytime nap. Sleepiness was measured using two self‐rating scales and the multiple sleep latency test. During sleep restriction, nocturnal stage 2 and REM sleep were reduced and slow wave sleep was unaffected. Stanford Sleepiness Scales showed an immediate increase in daytime sleepiness that reached a plateau after 4 days. An analog sleepiness rating scale showed increased sleepiness after 2 restricted nights and leveled off after the fourth restricted night. The multiple sleep latency tests showed no effect of sleep restriction until the second day, followed by a progressive increase in sleepiness that persisted through the seventh sleep restriction day. During the recovery period, daytime sleepiness returned to basal values on all three measures following one full night of sleep; with a daytime nap, no further cumulative effects of sleep restriction were seen.
Hemispheric Asymmetry and Human Electrodermal Conditioning: The Dichotic Extinction Paradigm
Authors: Hugdahl Kenneth , Brobeck Claes‐Goran 
Published: February 2007

ABSTRACTIt was hypothesized that classically conditioned responses to an auditory verbal CS initially presented only to the left cerebral hemisphere would be greater than when the same CS was presented to the right hemisphere. The experiment consisted of three different phases in a dichotic extinction paradigm. During the habituation phase the CS+ and CS− were presented binaurally, and separated. All subjects were treated alike. During the acquisition phase the conditioning subjects had the CS+ but not the CS− followed by the UCS. The CS+ and CS− were presented binaurally and separated. The control subjects received no UCS presentations. During the dichotic extinction phase, half of the conditioned subjects had the CS+ presented in the right ear (i.e., with initial left hemisphere input), with the CS− simultaneously presented in the left ear (i.e., with initial right hemisphere input). The other half had the earphones reversed. The control group was similar to the two conditioning groups. During the acquisition phase, significantly larger electrodermal responses were observed to the CS+ compared to the CS− in the conditioning groups, but not in the control group. During the dichotic extinction phase, significantly more resistance to extinction was observed in the CS+ Right‐Ear group compared to the CS+ Left‐Ear group, with the control group revealing virtually no responding at all. It was concluded that the present results have demonstrated effects of cerebral asymmetry on rate of extinction of the classically conditioned response.
Identification of Prebiotic Fructooligosaccharide Metabolism in
Lactobacillus plantarum
WCFS1 through Microarrays
Authors: Saulnier Delphine M. A. , Molenaar Douwe , de Vos Willem M. , Gibson Glenn R. , Kolida Sofia 
Published: January 2007

ABSTRACT

Short-chain fructooligosaccharides (scFOS) and other prebiotics are used to selectively stimulate the growth and activity of lactobacilli and bifidobacteria in the colon. However, there is little information on the mechanisms whereby prebiotics exert their specific effects upon such microorganisms. To study the genomic basis of scFOS metabolism in
Lactobacillus plantarum
WCFS1, two-color microarrays were used to screen for differentially expressed genes when grown on scFOS compared to glucose (control). A significant up-regulation (8- to 60-fold) was observed with a set of only five genes located in a single locus and predicted to encode a sucrose phosphoenolpyruvate transport system (PTS), a β-fructofuranosidase, a fructokinase, an α-glucosidase, and a sucrose operon repressor. Several other genes were slightly overexpressed, including pyruvate dehydrogenase. For the latter, no detectable activity in
L. plantarum
under various growth conditions has been previously reported. A mannose-PTS likely to encode glucose uptake was 50-fold down-regulated as well as, to a lower extent, other PTSs. Chemical analysis of the different moieties of scFOS that were depleted in the growth medium revealed that the trisaccharide 1-kestose present in scFOS was preferentially utilized, in comparison with the tetrasaccharide nystose and the pentasaccharide fructofuranosylnystose. The main end products of scFOS fermentation were lactate and acetate. This is the first example in lactobacilli of the association of a sucrose PTS and a β-fructofuranosidase that could be used for scFOS degradation.
Use of Transposon Promoter-Probe Vectors in the Metabolic Engineering of the Obligate Methanotroph
Methylomonas
sp. Strain 16a for Enhanced C
40
Carotenoid Synthesis
Authors: Sharpe Pamela L. , DiCosimo Deana , Bosak Melissa D. , Knoke Kyle , Tao Luan , Cheng Qiong , Ye Rick W. 
Published: January 2007

ABSTRACT

The recent expansion of genetic and genomic tools for metabolic engineering has accelerated the development of microorganisms for the industrial production of desired compounds. We have used transposable elements to identify chromosomal locations in the obligate methanotroph
Methylomonas
sp. strain 16a that support high-level expression of genes involved in the synthesis of the C
40
carotenoids canthaxanthin and astaxanthin. with three promoterless carotenoid transposons, five chromosomal locations—the
fliCS
,
hsdM
,
ccp-3
,
cysH
, and
nirS
regions—were identified. Total carotenoid synthesis increased 10- to 20-fold when the carotenoid gene clusters were inserted at these chromosomal locations compared to when the same carotenoid gene clusters were integrated at neutral locations under the control of the promoter for the gene conferring resistance to chloramphenicol. A chromosomal integration system based on sucrose lethality was used to make targeted gene deletions or site-specific integration of the carotenoid gene cluster into the
Methylomonas
genome without leaving genetic scars in the chromosome from the antibiotic resistance genes that are present on the integration vector. The genetic approaches described in this work demonstrate how metabolic engineering of microorganisms, including the less-studied environmental isolates, can be greatly enhanced by identifying integration sites within the chromosome of the host that permit optimal expression of the target genes.
Phylogenetic Diversity of Archaea and Bacteria in the Anoxic Zone of a Meromictic Lake (Lake Pavin, France)
Authors: Lehours Anne-Catherine , Evans Paul , Bardot Corinne , Joblin Keith , Gérard Fonty 
Published: January 2007

ABSTRACT
The compositions of archaeal and bacterial populations at different depths (60 m [mixolimnion-chemocline interface], 70 m [chemocline-subchemocline interface], 90 m, and 92 m [the water-sediment interface]) in the anoxic zone of the water column in Lake Pavin, a freshwater permanently stratified mountain lake in France, were determined. Phylogenetic trees were constructed from sequences to assess archaeal and bacterial diversity at the four sites.
Improved Experimental and Computational Methodology for Determining the Kinetic Equation and the Extant Kinetic Constants of Fe(II) Oxidation byAcidithiobacillus ferrooxidans
Authors: Molchanov Sharon , Gendel Yuri , Ioslvich Ilya , Lahav Ori 
Published: January 2007

ABSTRACTThe variety of kinetics expressions encountered in the literature and the unreasonably broad range of values reported for the kinetics constants ofAcidithiobacillus ferrooxidansunderscore the need for a unifying experimental procedure and for the development of a reliable kinetics equation. Following an extensive and critical review of reported experimental techniques, a method based on batch pH-controlled kinetics experiments lasting less than one doubling time was developed for the determination of extant kinetics constants. The Fe(II) concentration in the experiments was measured by a method insensitive to Fe(III) interference. Kinetics parameters were determined by nonlinear fitting of the integrated form of the Monod equation to yield aKSof 31 ± 4 mg Fe2+liter−1(mean ± standard deviation), aKPof 139 ± 20 mg Fe3+liter−1, and a μmaxof 0.082 ± 0.002 h−1. The corresponding kinetics equation was as follows:\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[\frac{dS}{dt}{=}\left({-}\frac{0.082}{2.3{\cdot}10^{7}}\right)\frac{S{\cdot}X}{31(1{+}\frac{P_{0}{+}S_{0}{-}S}{139}){+}S}\] \end{document}whereSrepresents the Fe(II) concentration in mg liter−1,P0represents the initial Fe(III) concentration in mg liter−1,Xrepresents the suspended bacterial cell concentration in cells ml−1, andtrepresents time in hours. The measured data fit this equation exceptionally well, with anR2of >0.99. Fe(III) inhibition was found to be of a competitive nature. Contrary to previous reports, the results show that the concentration ofAcidithiobacillus ferrooxidanscells has no affect on the kinetics constants. The kinetics equation can be considered applicable only toA. ferrooxidanscells grown under environmental conditions similar to those of the inoculum tested in the study. In contrast, the experimental and computational procedure is completely general and can be applied toA. ferrooxidansirrespective of the culture history.
A Five-Strain Probiotic Combination Reduces Pathogen Shedding and Alleviates Disease Signs in Pigs Challenged with
Salmonella enterica
Serovar Typhimurium
Authors: Casey Pat G. , Gardiner Gillian E. , Casey Garrett , Bradshaw Bernard , Lawlor Peadar G. , Lynch P. Brendan , Leonard Finola C. , Stanton Catherine , Ross R. Paul , Fitzgerald Gerald F. , Hill Colin 
Published: January 2007

ABSTRACT

Salmonella
spp. infection is a major cause of gastroenteritis, with many thousands of cases reported in the European Union every year. The use of probiotics offers the potential to improve this situation. Here, we investigate the effects of oral treatment of pigs with a defined lactic acid bacteria culture mixture on both clinical and microbiological signs of
Salmonella enterica
serovar Typhimurium infection. Fifteen weaned pigs blocked by sex and weight were administered control milk or a mixture of five probiotic strains as either a milk fermentate or milk suspension for a total of 30 days. The mixture consisted of two strains of
Lactobacillus murinus
and one strain each of
Lactobacillus salivarius
subsp.
salivarius
,
Lactobacillus pentosus
, and
Pediococcus pentosaceous
. Following probiotic administration for 6 days, animals were challenged orally with serovar Typhimurium; the health of the animals and the microbiological composition of their feces were monitored for 23 days postinfection. Animals treated with probiotic showed reduced incidence, severity, and duration of diarrhea. These animals also gained weight at a greater rate than control pigs administered skim milk. Mean fecal numbers of
Salmonella
were significantly reduced in probiotic-treated animals at 15 days postinfection (
P
= 0.01). The administered probiotic bacteria improved both the clinical and microbiological outcome of
Salmonella
infection. These strains offer significant benefit for use in the food industry and may have potential in human applications.