bluuebunny/crossref_metadata_2025 huggingface dataset:
Green national accounting: the case of Chile's mining sector
Authors: Figueroa Eugenio , Calfucura Enrique , Nuñez Javier
Published: July 2002

This article uses the welfare foundations for the usual net domestic product (NDP) income measure of the traditional National Accounts System (NAS) provided by Weitzman (1976, 2000), and the propositions of Hartwick (1993) and Hamilton (1994a) to correct this measure in order to obtain a green (sustainable) measure of economic income. It estimates green measures of the economic income of Chile's mining sector for the period 1977–1996. Different methodologies regarding the valuation of mining resources are employed, and exploration expenditures in the mining sector are included to empirically estimate the green measures of income. The results clearly show that the usual income measures of the traditional NAS overestimated the economic income generated by the Chilean mining sector during the period by 20–40 per cent, and its rate of growth by 3–20 per cent. Moreover, this overestimation has increased in recent years. These empirical results are remarkably similar when different methodologies are used to calculate green measures of the mining sector's economic income. The empirical evidence produced in this work, together with the one provided by other studies, leads to the conclusion that Chile's outstanding recent economic growth has not delivered the amount of economic income recorded by its NAS, since a significant part of it corresponded to depreciation of the country's natural capital.
Graphical GROOVE: memorial for the VAMPIRE, a visual music system
Authors: Spiegel Laurie
Published: July 2002

Once upon a time there was a computer music system called GROOVE (Generating

Realtime Operations On Voltage-controlled Equipment, Bell Telephone

Laboratories, Murray Hill, New Jersey) which outputted in the realm of

sound, and was a wonderful and still-unique tool for the composition

thereof. At that time a then-young composer who was using GROOVE for music

got the harebrained idea that if she made a few minor changes here and there

she could use it to compose images as well. This she did in 1974-6, and

though the untimely demise of the system prevented creation of much

documentation in the form of aesthetic works of its output, the system did

function sufficiently to make some description worthwhile. While it is true

that the mid-1960s DDP-224 computer on which GROOVE became a VAMPIRE (Video

And Music Program for Interactive Realtime Exploration/Experimentation) was

a massive room-sized computer, it has by now long been eclipsed in power by

the constantly improving home computer. It is worth describing the concepts

involved in part because there are by now many small computers capable of

emulating its musical methods. Besides, I had a deep personal relationship

with that computer, and wish to commemorate it. Here then follows the tale

of Graphical GROOVE, aka the VAMPIRE.
HoNOSCA: Uses and Limitations
Authors: Garralda Elena , Yates Peter
Published: July 2002

HoNOSCA is a timely newcomer to the field of Child and
Adolescent Mental Health Services (CAMHS) research.
In its short life it has already been thoroughly and
successfully evaluated. Its user-friendliness has made it
acceptable and even popular in routine clinical practice. It
was central to clinical data gathering for the recent
national survey of CAMH provision in the UK (Audit
Commission, 1999). What are the reasons for its popularity? What are its limitations? And what about possible
future uses?
Multisystemic Therapy:
An Overview of Clinical
Procedures, Outcomes,
and Policy Implications
Authors: Henggeler Scott W.
Published: July 2002

Multisystemic therapy (MST) is a family- and community-based treatment

that has successfully served as a clinical and cost-effective alternative
to
out-of-home placements (e.g. incarceration, psychiatric hospitalisation)

for youths presenting serious clinical problems. MST clinical procedures

and findings from MST outcome studies are reviewed. Several key features

differentiate MST from prevailing mental health and juvenile justice
practices and probably account for its relative success. These features

include interventions that comprehensively address the known
determinants of clinical problems, the provision of services in home and

community settings to promote service access and ecological validity, and

a philosophy that emphasises provider accountability for family
engagement and outcomes.
The architecture of the bilingual language faculty: evidence from intrasentential code switching
Authors: MacSwan Jeff
Published: July 2002

In this article, the author addresses the question of how the mind represents two languages in simultaneous bilingualism. Some linguistic theories of intrasentential code switching are reviewed, with a focus on the Minimalist approach of MacSwan (1999b); the author concludes that evidence from code switching suggests that bilinguals have discrete and separate Lexicons for the languages they speak, each with its own internal principles of word formation, as well as separate phonological systems. However, the author argues that computational resources common to the two languages generate monolingual and bilingual syntactic derivations alike. Advantages of the Minimalist Program for the analysis of code switching data are discussed at some length.
Temperature and food quality effects on growth, consumption and post-ingestive utilization ef.ciencies of the forest tent caterpillar Malacosoma disstria (Lepidoptera: Lasiocampidae)
Authors: Levesque K.R. , Fortin M. , Mauffette Y.
Published: July 2002

Temperature and food quality can both influence growth rates, consumption rates, utilization efficiencies and developmental time of herbivorous insects. Gravimetric analyses were conducted during two consecutive years to assess the effects of temperature and food quality on fourth instar larvae of the forest tent caterpillar Malacosoma disstria Hübner. Larvae were reared in the laboratory at three different temperatures (18, 24 and 30°C) and on two types of diet; leaves of sugar maple trees Acer saccharum Marsh. located at the forest edge (sun-exposed leaves) or within the forest interior (shade-exposed leaves). In general, larvae reared at 18°C had lower growth rates and lower consumption rates than larvae reared at the warmer temperatures (24 and 30°C). Moreover, the duration of the instar decreased significantly with increasing temperatures. Type of diet also affected the growth rates and amount of food ingested by larvae but did not affect the duration of the instar. Larvae fed sun-exposed leaves consumed more food and gained higher biomasses. Values of approximate digestibility and efficiency of conversion of ingested food were also higher when larvae were fed sun-exposed leaves. Higher growth rates with increasing temperatures were primarily the result of the shorter stadium duration. The higher growth rates of larvae fed sun-exposed leaves were possibly the result of stimulatory feeding and consequently greater food intake and also a more efficient use of food ingested. This study suggests that the performance of M. disstria caterpillars could be enhanced by warmer temperatures and higher leaf quality.
KOJAK encodes a cellulose synthase-like protein required for root hair cell morphogenesis in Arabidopsis
Authors: Favery Bruno , Ryan Eoin , Foreman Julia , Linstead Paul , Boudonck Kurt , Steer Martin , Shaw Peter , Dolan Liam
Published: July 2002

The cell wall is an important determinant of plant cell form. Here we define a class of Arabidopsis root hair mutants with defective cell walls. Plants homozygous for kojak (kjk) mutations initiate root hairs that rupture at their tip soon after initiation. The KJK gene was isolated by positional cloning, and its identity was confirmed by the molecular complementation of the Kjk− phenotype and the sequence of three kjkmutant alleles. KOJAK encodes a cellulose synthase-like protein, AtCSLD3. KOJAK/AtCSLD3 is the first member of this subfamily of proteins to be shown to have a function in cell growth. Subcellular localization of the KOJAK/AtCSLD3 protein using a GFP fusion shows that KOJAK/AtCSLD3 is located on the endoplasmic reticulum, indicating that KOJAK/AtCSLD3 is required for the synthesis of a noncellulosic wall polysaccharide. Consistent with the cell specific defect in the roots of kjk mutants, KOJAK/AtCSDL3 is preferentially expressed in hair cells of the epidermis. The Kjk−phenotype and the pattern of KOJAK/AtCSLD3 expression suggest that this gene acts early in the process of root hair outgrowth. These results suggest that KOJAK/AtCSLD3 is involved in the biosynthesis of β-glucan-containing polysaccharides that are required during root hair elongation.
Dual utilization of an acceptor/donor splice site governs the alternative splicing of the IRF-3 gene
Authors: Karpova Alla Y. , Howley Peter M. , Ronco Lucienne V.
Published: July 2002

Interferon regulatory factors constitute a family of transcriptional activators and repressors involved in a large number of vital cellular processes. Interferon regulatory factor-3 (IRF-3) has been implicated in virus and double-stranded RNA mediated induction of IFNβ and RANTES, in DNA damage signaling, and in virus-induced apoptosis. With its critical role in these pathways, the activity of IRF-3 is tightly regulated in myriad ways. Here we describe novel regulation of IRF-3 at the level of RNA splicing. We show that an unprecedented dual utilization of a splice acceptor/donor site within the IRF-3 mRNA governs the production of two alternative splice isoforms.
A model for the abrogation of the SOS response by an SOS protein: a negatively charged helix in DinI mimics DNA in its interaction with RecA
Authors: Voloshin Oleg N. , Ramirez Benjamin E. , Bax Ad , Camerini-Otero R. Daniel
Published: July 2002

DinI is a recently described negative regulator of the SOS response in Escherichia coli. Here we show that it physically interacts with RecA and prevents the binding of single-stranded DNA to RecA, which is required for the activation of the latter. DinI also displaces ssDNA from a stable RecA–DNA cofilament, thus eliminating the SOS signal. In addition, DinI inhibits RecA-mediated homologous DNA pairing, but has no effect on actively proceeding strand exchange. Biochemical data, together with the molecular structure, define the C-terminal α-helix in DinI as the active site of the protein. In an unusual example of molecular mimicry, a negatively charged surface on this α-helix, by imitating single-stranded DNA, interacts with the loop L2 homologous pairing region of RecA and interferes with the activation of RecA.
Sharp, an inducible cofactor that integrates nuclear receptor repression and activation
Authors: Shi Yanhong , Downes Michael , Xie Wen , Kao Hung-Ying , Ordentlich Peter , Tsai Chih-Cheng , Hon Michelle , Evans Ronald M.
Published: July 2002

A yeast two-hybrid screen using the conserved carboxyl terminus of the nuclear receptor corepressor SMRT as a bait led to the isolation of a novel human gene termed SHARP (SMRT/HDAC1 Associated Repressor Protein). SHARP is a potent transcriptional repressor whose repression domain (RD) interacts directly with SMRT and at least five members of the NuRD complex including HDAC1 and HDAC2. In addition, SHARP binds to the steroid receptor RNA coactivator SRA via an intrinsic RNA binding domain and suppresses SRA-potentiated steroid receptor transcription activity. Accordingly, SHARP has the capacity to modulate both liganded and nonliganded nuclear receptors. Surprisingly, the expression of SHARP is itself steroid inducible, suggesting a simple feedback mechanism for attenuation of the hormonal response.
Capping, splicing, and 3′ processing are independently stimulated by RNA polymerase II: different functions for different segments of the CTD
Authors: Fong Nova , Bentley David L.
Published: July 2002

Capping, splicing, and cleavage/polyadenylation of pre-mRNAs are interdependent events that are all stimulated in vivo by the carboxy-terminal domain (CTD) of RNA Pol II. We show that the CTD independently enhances splicing and 3′ processing and that stimulation of splicing by enhancers is facilitated by the CTD. We provide evidence that stimulation of 3′ processing by the CTD requires contact with the 50-kD subunit of the cleavage stimulation factor, CstF. Overexpression of the CTD-binding domain of CstF p50 had a dominant-negative effect on 3′ processing without disrupting the CstF complex. The CTD comprises 52 heptad repeats. The CTD carboxyl terminus including heptads 27–52 supported capping, splicing, and 3′ processing but the amino terminus supported only capping. We conclude that the CTD independently stimulates all three major pre-mRNA processing steps and that different regions of the CTD can serve distinct functions in pre-mRNA processing.
Saccharomyces Rrm3p, a 5′ to 3′ DNA helicase that promotes replication fork progression through telomeric and subtelomeric DNA
Authors: Ivessa Andreas S. , Zhou Jin-Qiu , Schulz Vince P. , Monson Ellen K. , Zakian Virginia A.
Published: July 2002

In wild-type Saccharomyces cerevisiae, replication forks slowed during their passage through telomeric C1–3A/TG1–3 tracts. This slowing was greatly exacerbated in the absence of RRM3, shown here to encode a 5′ to 3′ DNA helicase. Rrm3p-dependent fork progression was seen at a modified Chromosome VII-L telomere, at the natural X-bearing Chromosome III-L telomere, and at Y‘-bearing telomeres. Loss of Rrm3p also resulted in replication fork pausing at specific sites in subtelomeric DNA, such as at inactive replication origins, and at internal tracts of C1–3A/TG1–3 DNA. The ATPase/helicase activity of Rrm3p was required for its role in telomeric and subtelomeric DNA replication. Because Rrm3p was telomere-associated in vivo, it likely has a direct role in telomere replication.
Hox11 paralogous genes are essential for metanephric kidney induction
Authors: Wellik Deneen M. , Hawkes Patrick J. , Capecchi Mario R.
Published: July 2002

The mammalian Hox complex is divided into four linkage groups containing 13 sets of paralogous genes. These paralogous genes have retained functional redundancy during evolution. For this reason, loss of only one or two Hox genes within a paralogous group often results in incompletely penetrant phenotypes which are difficult to interpret by molecular analysis. For example, mice individually mutant for Hoxa11 or Hoxd11 show no discernible kidney abnormalities. Hoxa11/Hoxd11 double mutants, however, demonstrate hypoplasia of the kidneys. As described in this study, removal of the last Hox11 paralogous member, Hoxc11, results in the complete loss of metanephric kidney induction. In these triple mutants, the metanephric blastema condenses, and expression of early patterning genes, Pax2 and Wt1, is unperturbed.Eya1 expression is also intact. Six2 expression, however, is absent, as is expression of the inducing growth factor,Gdnf. In the absence of Gdnf, ureteric bud formation is not initiated. Molecular analysis of this phenotype demonstrates thatHox11 control of early metanephric induction is accomplished by the interaction of Hox11 genes with the pax-eya-sixregulatory cascade, a pathway that may be used by Hox genes more generally for the induction of multiple structures along the anteroposterior axis.
Frequent Human Genomic DNA Transduction Driven by LINE-1 Retrotransposition
Authors: Pickeral Oxana K. , Makałowski Wojciech , Boguski Mark S. , Boeke Jef D.
Published: July 2002

Human L1 retrotransposons can produce DNA transduction events in which unique DNA segments downstream of L1 elements are mobilized as part of aberrant retrotransposition events. That L1s are capable of carrying out such a reaction in tissue culture cells was elegantly demonstrated. Using bioinformatic approaches to analyze the structures of L1 element target site duplications and flanking sequence features, we provide evidence suggesting that ∼15% of full-length L1 elements bear evidence of flanking DNA segment transduction. Extrapolating these findings to the 600,000 copies of L1 in the genome, we predict that the amount of DNA transduced by L1 represents ∼1% of the genome, a fraction comparable with that occupied by exons.
Comparative Maps of Human 19p13.3 and Mouse Chromosome 10 Allow Identification of Sequences at Evolutionary Breakpoints
Authors: Puttagunta Radhika , Gordon Laurie A. , Meyer Gary E. , Kapfhamer David , Lamerdin Jane E. , Kantheti Prameela , Portman Kathleen M. , Chung Wendy K. , Jenne Dieter E. , Olsen Anne S. , Burmeister Margit
Published: July 2002

A cosmid/bacterial artificial chromosome (BAC) contiguous (contig) map of human chromosome (HSA) 19p13.3 has been constructed, and over 50 genes have been localized to the contig. Genes and anonymous ESTs from ≈4000 kb of human 19p13.3 were placed on the central mouse chromosome 10 map by genetic mapping and pulsed-field gel electrophoresis (PFGE) analysis. A region of ∼2500 kb of HSA 19p13.3 is collinear to mouse chromosome (MMU) 10. In contrast, the adjacent ≈1200 kb are inverted. Two genes are located in a 50-kb region after the inversion on MMU 10, followed by a region of homology to mouse chromosome 17. The synteny breakpoint and one of the inversion breakpoints has been localized to sequenced regions in human <5 kb in size. Both breakpoints are rich in simple tandem repeats, including (TCTG)n, (CT)n, and (GTCTCT)n, suggesting that simple repeat sequences may be involved in chromosome breaks during evolution. The overall size of the region in mouse is smaller, although no large regions are missing. Comparing the physical maps to the genetic maps showed that in contrast to the higher-than-average rate of genetic recombination in gene-rich telomeric region on HSA 19p13.3, the average rate of recombination is lower than expected in the homologous mouse region. This might indicate that a hot spot of recombination may have been lost in mouse or gained in human during evolution, or that the position of sequences along the chromosome (telomeric compared to the middle of a chromosome) is important for recombination rates.
Sequence Diversity and Large-Scale Typing of SNPs in the Human Apolipoprotein E Gene
Authors: Nickerson Deborah A. , Taylor Scott L. , Fullerton Stephanie M. , Weiss Kenneth M. , Clark Andrew G. , Stengård Jari H. , Salomaa Veikko , Boerwinkle Eric , Sing Charles F.
Published: July 2002

A common strategy for genotyping large samples begins with the characterization of human single nucleotide polymorphisms (SNPs) by sequencing candidate regions in a small sample for SNP discovery. This is usually followed by typing in a large sample those sites observed to vary in a smaller sample. We present results from a systematic investigation of variation at the human apolipoprotein E locus (APOE), as well as the evaluation of the two-tiered sampling strategy based on these data. We sequenced 5.5 kb spanning the entireAPOE genomic region in a core sample of 72 individuals, including 24 each of African-Americans from Jackson, Mississippi; European-Americans from Rochester, Minnesota; and Europeans from North Karelia, Finland. This sequence survey detected 21 SNPs and 1 multiallelic indel, 14 of which had not been previously reported. Alleles varied in relative frequency among the populations, and 10 sites were polymorphic in only a single population sample. Oligonucleotide ligation assays (OLA) were developed for 20 of these sites (omitting the indel and a closely-linked SNP). These were then scored in 2179 individuals sampled from the same three populations (n = 843, 884, and 452, respectively). Relative allele frequencies were generally consistent with estimates from the core sample, although variation was found in some populations in the larger sample at SNPs that were monomorphic in the corresponding smaller core sample. Site variation in the larger samples showed no systematic deviation from Hardy-Weinberg expectation. The large OLA sample clearly showed that variation in many, but not all, of OLA-typed SNPs is significantly correlated with the classical protein-coding variants, implying that there may be important substructure within the classical ɛ2, ɛ3, and ɛ4 alleles. Comparison of the levels and patterns of polymorphism in the core samples with those estimated for the OLA-typed samples shows how nucleotide diversity is underestimated when only a subset of sites are typed and underscores the importance of adequate population sampling at the polymorphism discovery stage.

[The sequence data described in this paper have been submitted to the GenBank data library under accession no. AF261279.]
Cytokine Responses to LTP Induction in the Rat Hippocampus: A Comparison of In Vitro and In Vivo Techniques
Authors: Jankowsky Joanna L. , Derrick Brian E. , Patterson Paul H.
Published: July 2002

Because exogenous application of a number of cytokines and growth factors can alter synaptic properties, we sought to determine if endogenous cytokine expression is affected by neuronal activity. In addition, we examined whether cytokine expression is altered by the techniques used to stimulate and record from hippocampal neurons. Using semi-quantitative RNase protection and RT-PCR assays, we studied the expression of 18 cytokine, growth factor, and receptor genes in the hippocampus following the induction of Schaffer collateral-CA1 long-term potentiation (LTP). We found that various cytokines are dramatically induced following preparation of slices for in vitro recording and as a result of injury following acute electrode placement in vivo. These increases can be overcome in vivo, however, using permanent electrodes implanted three weeks prior to testing. Using this chronic preparation, we found that interleukin-6 (IL-6) mRNA was upregulated nearly 20-fold by LTP induction in vivo, marking the first demonstration of endogenous regulation of this cytokine in response to LTP. In situ hybridization for IL-6 revealed that upregulation is tightly localized near the site of stimulation and is detected only in non-neuronal cells, identified as GFAP+ astrocytes and GFAP− cells within proximal blood vessels. Coupled with previous results showing that exogenously applied IL-6 can prevent the induction of LTP, this finding suggests a mechanism by which the local release of a cytokine could regulate LTP at nearby sites.
Plasma Membrane Ordering Agent Pluronic F-68 (PF-68) Reduces Neurotransmitter Uptake and Release and Produces Learning and Memory Deficits in Rats
Authors: Clarke Mark S.F. , Prendergast Mark A. , Terry Alvin V.
Published: July 2002

A substantial body of evidence indicates that aged-related changes in the fluidity and lipid composition of the plasma membrane contribute to cellular dysfunction in humans and other mammalian species. In the CNS, reductions in neuronal plasma membrane order (PMO) (i.e., increased plasma membrane fluidity) have been attributed to age as well as the presence of the β-amyloid peptide-25-35, known to play an important role in the neuropathology of Alzheimer's disease (AD). These PMO increases may influence neurotransmitter synthesis, receptor binding, and second messenger systems as well as signal transduction pathways. The effects of neuronal PMO on learning and memory processes have not been adequately investigated, however. Based on the hypothesis that an increase in PMO may alter a number of aspects of synaptic transmission, we investigated several neurochemical and behavioral effects of the membrane ordering agent, PF-68. In cell culture, PF-68 (nmoles/mg SDS extractable protein) reduced [3H]norepinephrine (NE) uptake into differentiated PC-12 cells as well as reduced nicotine stimulated [3H]NE release. The compound (800–2400 μg/kg, i.p., resulting in nmoles/mg SDS extractable protein in the brain) decreased step-through latencies and increased the frequencies of crossing into the unsafe side of the chamber in inhibitory avoidance training. In the Morris water maze, PF-68 increased the latencies and swim distances required to locate a hidden platform and reduced the time spent and distance swam in the previous target quadrant during transfer (probe) trials. PF-68 did not impair performance of a well-learned working memory task, the rat delayed stimulus discrimination task (DSDT), however. Studies with 14C-labeled PF-68 indicated that significant (pmoles/mg wet tissue) levels of the compound entered the brain from peripheral (i.p.) injection. No PF-68 related changes were observed in swim speeds or in visual acuity tests in water maze experiments, rotorod performance, or in tests of general locomotor activity. Furthermore, latencies to select a lever in the DSDT were not affected. These results suggest that PF-68 induced deficits in learning and memory without confounding peripheral motor, sensory, or motivational effects at the tested doses. Furthermore, none of the doses induced a conditioned taste aversion to a novel 0.1% saccharin solution indicating a lack of nausea or gastrointestinal malaise induced by the compound. The data indicate that increases in neuronal plasma membrane order may have significant effects on neurotransmitter function as well as learning and memory processes. Furthermore, compounds such as PF-68 may also offer novel tools for studying the role of neuronal PMO in mnemonic processes and changes in PMO resulting from age-related disorders such as AD.
Indole-3-Acetic Acid Metabolism in Lemna gibbaUndergoes Dynamic Changes in Response to Growth Temperature
Authors: Rapparini Francesca , Tam Yuen Yee , Cohen Jerry D. , Slovin Janet P.
Published: July 2002

Auxin is the mobile signal controlling the rate of growth and specific aspects of the development of plants. It has been known for over a century that auxins act as the messenger linking plant development to specific environmental changes. An often overlooked aspect of how this is accomplished is the effect of the environment on metabolism of the major plant auxin, indole-3-acetic acid (IAA). We have studied the metabolism of IAA in relation to one environmental variable, growth temperature. The model system used was an inbred line of the aquatic monocot Lemna gibba G-3, 3F7-11 grown at temperatures ranging from 5°C to 35°C. IAA levels, the rate of IAA turnover, and the patterns of label incorporation from IAA precursors were measured using stable isotope-mass spectrometric techniques and were evaluated relative to growth at the experimental temperatures. IAA levels exhibited unusually high variability in plants grown at 15°C and 20°C. Turnover rates were quite rapid throughout the range of experimental temperatures except at 25°C, where IAA turnover was notably slower. These results suggest that a transition occurred over these temperatures for some aspect of IAA metabolism. Analysis of [15N]anthranilate and [2H5]tryptophan (Trp) incorporation into IAA showed that Trp-dependent biosynthesis predominated at 15°C; however, Trp-independent biosynthesis of IAA was the major route to IAA at 30°C. The effects of growth temperature on auxin levels have been reported previously, but no prior studies correlated these effects with which pathway becomes the primary one for IAA production.
A Metal-Accumulator Mutant of Arabidopsis thaliana
Authors: Delhaize E.
Published: July 2002

A mutation designated man1 (for manganese accumulator) was found to cause Arabidopsis thaliana seedlings to accumulate a range of metals. The man1 mutation segregated as a single recessive locus located on chromosome 3. When grown on soil, mutant seedlings accumulated Mn (7.5 times greater than wild type), Cu (4.6 times greater than wild type), Zn (2.8 times greater than wild type), and Mg (1.8 times greater than wild type) in leaves. In addition to these metals, the man1 mutant accumulated 2.7-fold more S in leaves, primarily in the oxidized form, than wild-type seedlings. Analysis of seedlings grown by hydroponic culture showed a similar accumulation of metals in leaves of man1 mutants. Roots of man1 mutants also accumulated metals, but unlike leaves they accumulated 10-fold more total Fe (symplasmic and apoplasmic combined) than wild-type roots. Roots of man1 mutants possessed greater (from 1.8- to 20-fold) ferric-chelate reductase activity than wild-type seedlings, and this activity was not responsive to changes of Mn nutrition in either genotype. Taken together, these results suggest that the man1 mutation disrupts the regulation of metal-ion uptake or homeostasis in Arabidopsis.
Isolation and Characterization of Glutamine Synthetase from the Marine Diatom Skeletonema costatum
Authors: Robertson D. L. , Alberte R. S.
Published: July 2002

Two peaks of glutamine synthetase (GS) activity were resolved by anion-exchange chromatography from the marine diatom Skeletonema costatum Grev. The second peak of activity accounted for greater than 93% of total enzyme activity, and this isoform was purified over 200-fold. Results from denaturing gel electrophoresis and gel-filtration chromatography suggest that six 70-kD subunits constitute the 400-kD native enzyme. The structure of the diatom GS, therefore, appears more similar to that of a type found in bacteria than to the type common among other eukaryotes. Apparent Michaelis constant values were 0.7 mM for NH4+, 5.7 mM for glutamic acid, and 0.5 mM for ATP. Enzyme activity was inhibited by serine, alanine, glycine, phosphinothricin, and methionine sulfoximine. Polyclonal antiserum raised against the purified enzyme localized a single polypeptide on western blots of S. costatum cell lysates and recognized the denatured, native enzyme. Western analysis of the two peak fractions derived from anion-exchange chromatography demonstrated that the 70-kD protein was present only in the later-eluting peak of enzyme activity. This form of GS does not appear to be unique to S. costatum, since the antiserum recognized a similar-sized protein in cell lysates of other chromophytic algae.
Differential Regulation of Trichome Formation on the Adaxial and Abaxial Leaf Surfaces by Gibberellins and Photoperiod in Arabidopsis thaliana (L.) Heynh
Authors: Chien J. C. , Sussex I. M.
Published: July 2002

In wild-type (WT) Columbia and Landsberg erecta ecotypes of Arabidopsis thaliana (L.) Heynh., trichomes are present on the adaxial surfaces of all rosette leaves but are absent from the abaxial surfaces of the first-formed leaves. We have determined that both long-day (LD) photoperiod and gibberellin (GA) stimulate trichome formation. WT plants grown in LD conditions produce the first abaxial trichome on earlier leaves than plants grown in short-day (SD) conditions. Photoperiod sensitivity of abaxial trichome formation on WT plants develops gradually over time, reaching the maximum sensitivity about 24 d after germination. Application of gibberellic acid to WT plants growing in SD conditions accelerates the onset of abaxial trichomes. Conversely, application of 20 to 80 mg L-1 paclobutrazol, a GA biosynthesis inhibitor, to wild-type plants suppresses trichome initiation on the abaxial epidermis. The GA-deficient mutants ga1–5 and ga4–1 and the GA-insensitive mutant gai-1 exhibit delayed onset of abaxial trichomes when grown in LD conditions. The null mutant ga1–3 produces completely glabrous leaves when grown in SD conditions. Application of gibberellic acid to glabrous ga1–3 plants consistently induces earlier formation of trichomes on the adaxial epidermis than on the abaxial epidermis, demonstrating a difference between the adaxial and abaxial surfaces in their response to GA with regard to trichome formation.
Al Toxicity in Yeast (A Role for Mg?)
Authors: MacDiarmid C. W. , Gardner R. C.
Published: July 2002

We have established conditions in which soluble Al is toxic to the yeast Saccharomyces cerevisiae. The major modifications to a standard synthetic medium were lowering the pH and the concentration of Mg ions. Alterations to the PO4, Ca, or K concentration had little effect on toxicity. Organic acids known to chelate Al reduced its toxicity, suggesting that Al3+ is the toxic Al species. The unique ability of Mg ions to ameliorate Al toxicity led us to investigate the hypothesis that Al inhibits Mg uptake by yeast. Yeast cells accumulate Mg, Co, Zn, Ni, and Mn ions via the same transport system (G.F. Fuhrmann, A. Rothstein [1968] Biochim Biophys Acta 163: 325–330). Al3+ inhibited the accumulation of 57Co2+ by yeast cells more effectively than Ga, La, or Mg. In addition, a mutant yeast strain with a defect in divalent cation uptake proved to be more sensitive to Al than a wild-type strain. Taken together, these results suggest that Al may cause Mg deficiency in yeast by blocking Mg transport. We discuss the relevance of yeast as a model for the study of Al toxicity in plant systems.
Functional Analysis of a Brassica oleracea SLR1 Gene Promoter
Authors: Hackett R. M. , Cadwallader G. , Franklin FCH.
Published: July 2002

The Brassica oleracea S-locus-related gene 1 (SLR1) is expressed in the papillar cells of Brassica stigmas from a few days before anthesis. We have previously shown that a 1500-bp fragment of the SLR1 gene promoter is sufficient to direct high-level, temporally regulated expression of the β-glucuronidase reporter gene in the pistils of transgenic tobacco. We have carried out a deletion analysis of the SLR1 promoter and found that elements required for pistil expression are located between -258 and -327 bp (relative to the translation start site). Furthermore, specific binding of pistil nuclear factors to sequences within this region was demonstrated by gel retardation analysis. Sequences between -1350 and -1500 were found to be required for high-level expression.
Identification of a Receptor-Like Protein Kinase Gene Rapidly Induced by Abscisic Acid, Dehydration, High Salt, and Cold Treatments in Arabidopsis thaliana
Authors: Hong S. W. , Jon J. H. , Kwak J. M. , Nam H. G.
Published: July 2002

A cDNA clone for a receptor-like protein kinase gene (RPK1) was isolated from Arabidopsis thaliana. The clone is 1952 bp long with 1623 bp of an open reading frame encoding a peptide of 540 amino acids. The deduced peptide (RPK1) contains four distinctive domains characteristic of receptor kinases: (a) a putative amino-terminal signal sequence domain; (b) a domain with five extracellular leucine-rich repeat sequences; (c) a membrane-spanning domain; and (d) a cytoplasmic protein kinase domain that contains all of the 11 subdomains conserved among protein kinases. The RPK1 gene is expressed in flowers, stems, leaves, and roots. Expression of the RPK1 gene is induced within 1 h after treatment with abscisic acid (ABA). The gene is also rapidly induced by several environmental stresses such as dehydration, high salt, and low temperature, suggesting that the gene is involved in a general stress response. The dehydration-induced expression is not impaired in aba-1, abi1–1, abi2–1, and abi3–1 mutants, suggesting that the dehydration-induced expression of the RPK1 gene is ABA-independent. A possible role of this gene in the signal transduction pathway of ABA and the environmental stresses is discussed.
Importin α- from Arabidopsis thaliana Is a Nuclear Import Receptor That Recognizes Three Classes of Import Signals
Authors: Smith HMS. , Hicks G. R. , Raikhel N. V.
Published: July 2002

Protein import into the nucleus is a two-step process. In vitro import systems from vertebrate cell extracts have shown that several soluble factors are required. One of these factors is the receptor importin α-, which binds to nuclear localization signals (NLS) in vitro. We previously cloned an importin α- homolog from Arabidopsis thaliana (At-IMPα-) and demonstrated that this protein was not depleted from tobacco (Nicotiana tabacum) protoplasts after permeabilization of the plasma membrane (Hicks et al., 1996). To determine if At-IMPα- is functional, we used an in vitro NLS-binding assay. We found that At-IMPα- binding is specific, and the receptor is able to recognize three classes of NLS identified in plants. Purified antibodies to At-IMPα- were used to determine the in vivo location of importin α- in tobacco protoplasts. Importin α- is found in the cytoplasm and nucleus, and it is most highly concentrated at the nuclear envelope. The biochemical properties of nuclear importin α- and localization studies using purified nuclei demonstrate that importin α- is tightly associated with the plant nucleus. Moreover, these results suggest that a fraction of nuclear importin α- interacts with the nuclear pore complex.
Overexpression of the FAD3 Desaturase Gene in a Mutant of Arabidopsis
Authors: Shah S. , Xin Z. , Browse J.
Published: July 2002

A mutant of Arabidopsis contained increased levels of 18:3 fatty acids and correspondingly decreased levels of 18:2. The fatty acid phenotype was strongly expressed in root and seed tissues and this observation, together with other data, suggested that the mutation leads to increased activity of the endoplasmic reticulum 18:2 desaturase encoded by the FAD3 gene. Gel-blot analysis of RNA from wild-type and mutant plants established that FAD3 transcript levels were increased 80% in the mutant relative to the wild type. Genetic analysis demonstrated a linkage between the new mutation and the fad3 locus. Linkage of the mutation to fad3 raises the possibility that the lesion is an alteration to the promoter or another regulatory region of the FAD3 gene, which results in increased transcription.
Two Homologous Low-Temperature-Inducible Genes from Arabidopsis Encode Highly Hydrophobic Proteins
Authors: Capel J. , Jarillo J. A. , Salinas J. , Martinez-Zapater J. M.
Published: July 2002

We have characterized two related cDNAs (RCI2A and RCI2B) corresponding to genes from Arabidopsis thaliana, the expression of which is transiently induced by low, nonfreezing temperatures. RCI2A and RCI2B encode small (54 amino acids), highly hydrophobic proteins that bear two potential transmembrane domains. They show similarity to proteins encoded by genes from barley (Hordeum vulgare L.) and wheatgrass (Lophophyrum elongatum) that are regulated by different stress conditions. Their high level of sequence homology (78%) and their genomic location in a single restriction fragment suggest that both genes originated as a result of a tandem duplication. However, their regulatory sequences have diverged enough to confer on them different expression patterns. Like most of the cold-inducible plant genes characterized, the expression of RCI2A and RCI2B is also promoted by abscisic acid (ABA) and dehydration but is not a general response to stress conditions, since it is not induced by salt stress or by anaerobiosis. Furthermore, low temperatures are able to induce RCI2A and RCI2B expression in ABA-deficient and -insensitive genetic backgrounds, indicating that both ABA-dependent and -independent pathways regulate the low-temperature responsiveness of these two genes.
bor1-1, an Arabidopsis thaliana Mutant That Requires a High Level of Boron
Authors: Noguchi K. , Yasumori M. , Imai T. , Naito S. , Matsunaga T. , Oda H. , Hayashi H. , Chino M. , Fujiwara T.
Published: July 2002

bor1–1 (high boron requiring), an Arabidopsis thaliana mutant that requires a high level of B, was isolated. When the B concentration in the medium was reduced to 3 [mu]M, the expansion of rosette leaves was severely affected in bor1–1 but not in wild-type plants. In a medium containing 30 [mu]M B the mutant grew normally but showed female sterility, whereas the wild type was able to set seeds. These defects of the bor1–1 mutant were not detected with supplementation of 100 [mu]M B. In vivo concentrations of B in bor1–1 mutants were lower than those of the wild type, especially in the inflorescence stems. Tracer experiments using 10B suggested that the mutant has defects in uptake and/or translocation of B. The mutation was mapped on the lower arm of chromosome 2.
Developmental and Hormonal Regulation of the Arabidopsis CER2 Gene That Codes for a Nuclear-Localized Protein Required for the Normal Accumulation of Cuticular Waxes
Authors: Xia Y. , Nikolau B. J. , Schnable P. S.
Published: July 2002

The previously cloned CER2 gene is required for the normal accumulation of cuticular waxes and encodes a novel protein. Earlier reports suggested that the CER2 protein is either a membrane-bound component of the fatty acid elongase complex or a regulatory protein. Cell fractionation and immunoblot analyses using polyclonal antibodies raised against a chemically synthesized peptide with a sequence based on the predicted CER2 protein sequence have demonstrated that the 47-kD CER2 protein is soluble and nuclear localized. These results are consistent with CER2 being a regulatory protein. Detailed studies of plants harboring a CER2 promoter/GUS transgene (CER2-GUS), in combination with immunoblot analyses, revealed that CER2 is expressed and the CER2 protein accumulates in a variety of organs and cell types. Expression is highest early in the development of these organs and is epidermis specific in most tissues. In agreement with the activity of the CER2 promoter in hypocotyls, cuticular wax accumulates on this organ in a CER2-dependent fashion. In leaves CER2 expression is confined to the guard cells, trichomes, and petioles. However, application of the cytokinin 6-benzylaminopurine induces ectopic expression of CER2-GUS in all cell types of leaves that emerge following treatment.
Sequencing, Genomic Organization, and Preliminary Promoter Analysis of a Black Cherry (R)-(+)-Mandelonitrile Lyase Gene
Authors: Hu Z. , Poulton J. E.
Published: July 2002

The flavoprotein (R)-(+)-mandelonitrile lyase (MDL; EC 4.1.2.10) plays a key role in cyanogenesis in rosaceous stone fruits. An MDL gene (mdl3) and its corresponding cDNA (MDL3) were isolated from black cherry (Prunus serotina) and characterized. The mdl3 gene contains 2292 bp of the 5[prime] flanking region, the entire coding region, and 300 bp of the 3[prime] flanking region. The coding region is interrupted by three short introns, of which one possesses the unusual GC-AG splice junction dinucleotides. This gene encodes a polypeptide of 573 amino acids that includes a putative signal sequence, 13 potential N-glycosylation sites, and a presumptive flavin adenine dinucleotide-binding site. To determine whether the 5[prime] flanking region of the mdl3 gene is capable of driving MDL expression, it was fused to the β-glucuronidase reporter gene for Agrobacterium-mediated transformation into tobacco. Matching endogenous MDL expression patterns, β-glucuronidase staining was observed in maturing embryos and seeds; it also occurred in postembryonic tissues, especially in association with vascular tissues. After developing a homologous transient transformation system to facilitate identification of putative regulatory sequences, we demonstrated that 125 bp (-107 to +18) of the 5[prime] flanking sequence of the mdl3 gene is sufficient for MDL expression in protoplasts derived from immature black cherry embryos.
Molecular and Enzymatic Characterization of Three Phosphoinositide-Specific Phospholipase C Isoforms from Potato1
Authors: Kopka Joachim , Pical Christophe , Gray Julie E. , Müller-Röber Bernd
Published: July 2002

Many cellular responses to stimulation of cell-surface receptors by extracellular signals are transmitted across the plasma membrane by hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2), which is cleaved into diacylglycerol and inositol-1,4,5-tris-phosphate by phosphoinositide-specific phospholipase C (PI-PLC). We present structural, biochemical, and RNA expression data for three distinct PI-PLC isoforms, StPLC1, StPLC2, and StPLC3, which were cloned from a guard cell-enriched tissue preparation of potato (Solanum tuberosum) leaves. All three enzymes contain the catalytic X and Y domains, as well as C2-like domains also present in all PI-PLCs. Analysis of the reaction products obtained from PIP2 hydrolysis unequivocally identified these enzymes as genuine PI-PLC isoforms. Recombinant StPLCs showed an optimal PIP2-hydrolyzing activity at 10 μm Ca2+ and were inhibited by Al3+ in equimolar amounts. In contrast to PI-PLC activity in plant plasma membranes, however, recombinant enzymes could not be activated by Mg2+. All three stplc genes are expressed in various tissues of potato, including leaves, flowers, tubers, and roots, and are affected by drought stress in a gene-specific manner.
Synthesis and Phosphorylation of Maize Acidic Ribosomal Proteins1
Authors: Aguilar Raúl , Montoya Leonel , Sánchez de Jiménez Estela
Published: July 2002

The objective of this research was to determine the role of acidic ribosomal protein (ARP) phosphorylation in translation. Ribosomes (Rbs) from germinated maize (Zea mays L.) axes had four ARP bands within 4.2 to 4.5 isoelectric points when analyzed by isoelectric focusing. Two of these bands disappeared after alkaline phosphatase hydrolysis. During germination a progressive change from nonphosphorylated (0 h) to phosphorylated ARP (24 h) forms was observed in the Rbs; a free cytoplasmic pool of nonphosphorylated ARPs was also identified by immunoblot and isoelectric focusing experiments. De novo ARP synthesis initiated very slowly early in germination, whereas ARP phosphorylation occurred rapidly within this period. ARP-phosphorylated versus ARP-nonphosphorylated Rbs were tested in an in vitro reticulocyte lysate translation system. Greater in vitro mRNA translation rates were demonstrated for the ARP-phosphorylated Rbs than for the non-ARP-phosphorylated ones. Rapamycin application to maize axes strongly inhibited S6 ribosomal protein phosphorylation, but did not interfere with the ARP phosphorylation reaction. We conclude that ARP phosphorylation does not depend on ARP synthesis or on ARP assembly into Rbs. Rather, this process seems to be part of a translational regulation mechanism.
Structural Analysis and Molecular Model of a Self-Incompatibility RNase from Wild Tomato1
Authors: Parry Simon , Newbigin Ed , Craik David , Nakamura Kazuo T. , Bacic Antony , Oxley David
Published: July 2002

Self-incompatibility RNases (S-RNases) are an allelic series of style glycoproteins associated with rejection of self-pollen in solanaceous plants. The nucleotide sequences of S-RNase alleles from several genera have been determined, but the structure of the gene products has only been described for those from Nicotiana alata. We report on the N-glycan structures and the disulfide bonding of the S3-RNase from wild tomato (Lycopersicon peruvianum) and use this and other information to construct a model of this molecule. The S3-RNase has a singleN-glycosylation site (Asn-28) to which one of threeN-glycans is attached. S3-RNase has seven Cys residues; six are involved in disulfide linkages (Cys-16-Cys-21, Cys-46-Cys-91, and Cys-166-Cys-177), and one has a free thiol group (Cys-150). The disulfide-bonding pattern is consistent with that observed in RNase Rh, a related RNase for which radiographic-crystallographic information is available. A molecular model of the S3-RNase shows that four of the most variable regions of the S-RNases are clustered on one surface of the molecule. This is discussed in the context of recent experiments that set out to determine the regions of the S-RNase important for recognition during the self-incompatibility response.