bluuebunny/crossref_metadata_2025 huggingface dataset:
Krox-20 patterns the hindbrain through both cell-autonomous and non cell-autonomous mechanisms
Authors: Giudicelli François , Taillebourg Emmanuel , Charnay Patrick , Gilardi-Hebenstreit Pascale
Published: July 2002

The Krox-20 gene encodes a zinc finger transcription factor, which has been shown previously, by targeted inactivation in the mouse, to be required for the development of rhombomeres (r) 3 and 5 in the segmented embryonic hindbrain. In the present work, Krox-20 was expressed ectopically in the developing chick hindbrain by use of electroporation. We demonstrate that Krox-20 expression is sufficient to confer odd-numbered rhombomere characteristics to r2, r4, and r6 cells, presumably in a cell-autonomous manner. Therefore, Krox-20, appears as the major determinant of odd-numbered identity within the hindbrain. In addition, we provide evidence for the existence of a non cell-autonomous autoactivation mechanism allowing recruitment of Krox-20-positive cells from even-numbered territories by neighboring Krox-20-expressing cells. On the basis of these observations, we propose that Krox-20 regulates multiple, intertwined steps in segmental patterning: Initial activation of Krox-20 in a few cells leads to the segregation, homogenization, and possibly expansion of territories to which Krox-20 in addition confers an odd-numbered identity.
SWITCH1 (SWI1): a novel protein required for the establishment of sister chromatid cohesion and for bivalent formation at meiosis
Authors: Mercier Raphaël , Vezon Daniel , Bullier Erika , Motamayor Juan C. , Sellier Aurélie , Lefèvre François , Pelletier Georges , Horlow Christine
Published: July 2002

We have characterized a new gene, SWI1, involved in sister chromatid cohesion during both male and female meiosis inArabidopsis thaliana. A first allele, swi1.1, was obtained as a T-DNA tagged mutant and was described previously as abnormal exclusively in female meiosis. We have isolated a new allele,swi1.2, which is defective for both male and female meiosis. Inswi1.2 male meiosis, the classical steps of prophase were not observed, especially because homologs do not synapse. Chromatid arms and centromeres lost their cohesion in a stepwise manner before metaphase I, and 20 chromatids instead of five bivalents were seen at the metaphase plate, which was followed by an aberrant segregation. In contrast, swi1.2 female meiocytes performed a mitotic-like division instead of meiosis, indicating a distinct role for SWI1 or a different effect of the loss of SWI1 function in both processes. TheSWI1 gene was cloned; the putative SWI1 protein did not show strong similarity to any known protein. Plants transformed with a SWI1–GFP fusion indicated that SWI1 protein is present in meiocyte nuclei, before meiosis and at a very early stage of prophase. Thus, SWI1 appears to be a novel protein involved in chromatid cohesion establishment and in chromosome structure during meiosis, but with clear differences between male and female meiosis.
Role of LXRs in control of lipogenesis
Authors: Schultz Joshua R. , Tu Hua , Luk Alvin , Repa Joyce J. , Medina Julio C. , Li Leping , Schwendner Susan , Wang Shelley , Thoolen Martin , Mangelsdorf David J. , Lustig Kevin D. , Shan Bei
Published: July 2002

The discovery of oxysterols as the endogenous liver X receptor (LXR) ligands and subsequent gene targeting studies in mice provided strong evidence that LXR plays a central role in cholesterol metabolism. The identification here of a synthetic, nonsteroidal LXR-selective agonist series represented by T0314407 and T0901317 revealed a novel physiological role of LXR. Oral administration of T0901317 to mice and hamsters showed that LXR activated the coordinate expression of major fatty acid biosynthetic genes (lipogenesis) and increased plasma triglyceride and phospholipid levels in both species. Complementary studies in cell culture and animals suggested that the increase in plasma lipids occurs via LXR-mediated induction of the sterol regulatory element-binding protein 1 (SREBP-1) lipogenic program.
The retinoic acid-inactivating enzyme CYP26 is essential for establishing an uneven distribution of retinoic acid along the anterio-posterior axis within the mouse embryo
Authors: Sakai Yasuo , Meno Chikara , Fujii Hideta , Nishino Jinsuke , Shiratori Hidetaka , Saijoh Yukio , Rossant Janet , Hamada Hiroshi
Published: July 2002

Retinoic acid (RA), a derivative of vitamin A, plays a pivotal role in vertebrate development. The level of RA may be determined by the balance between its synthesis and degradation. We have examined the role of CYP26, a P450 enzyme that may degrade RA, by generating mutant mice that lack CYP26. CYP26−/− mice exhibited anomalies, including caudal agenesis, similar to those induced by administration of excess RA. The concentration of endogenous RA, as revealed by marker gene activity, was markedly increased in the tailbud of the mutant animals, in which CYP26 is normally expressed. Expression of T (Brachyury) andWnt3a in the tailbud was down-regulated inCYP26−/− mice, which may underlie the caudal truncation. The lack of CYP26 also resulted in homeotic transformation of vertebrae as well as in misspecification of the rostral hindbrain associated with anterior expansion of RA-positive domains. These results suggest that local degradation of RA by CYP26 is required for establishing an uneven distribution of RA along the anterio-posterior axis, which is essential for patterning the hindbrain, vertebrae, and tailbud.
Roles of yeast DNA polymerases δ and ζ and of Rev1 in the bypass of abasic sites
Authors: Haracska Lajos , Unk Ildiko , Johnson Robert E. , Johansson Erik , Burgers Peter M.J. , Prakash Satya , Prakash Louise
Published: July 2002

Abasic (AP) sites are one of the most frequently formed lesions in DNA, and they present a strong block to continued synthesis by the replicative DNA machinery. Here we show efficient bypass of an AP site by the combined action of yeast DNA polymerases δ and ζ. In this reaction, Polδ inserts an A nucleotide opposite the AP site, and Polζ subsequently extends from the inserted nucleotide. Consistent with these observations, sequence analyses of mutations in the yeastCAN1s gene indicate that A is the nucleotide inserted most often opposite AP sites. The nucleotides C, G, and T are also incorporated, but much less frequently. Enzymes such as Rev1 and Polη may contribute to the insertion of these other nucleotides; the predominant role of Rev1 in AP bypass, however, is likely to be structural. Steady-state kinetic analyses show that Polζ is highly inefficient in incorporating nucleotides opposite the AP site, but it efficiently extends from nucleotides, particularly an A, inserted opposite this lesion. Thus, in eukaryotes, bypass of an AP site requires the sequential action of two DNA polymerases, wherein the extension step depends solely upon Polζ, but the insertion step can be quite varied, involving not only the predominant action of the replicative DNA polymerase, Polδ, but also the less prominent role of various translesion synthesis polymerases.
Reading between the LINEs: Human Genomic Variation Induced by LINE-1 Retrotransposition
Authors: Sheen Fang-miin , Sherry Stephen T. , Risch Gregory M. , Robichaux Myles , Nasidze Ivane , Stoneking Mark , Batzer Mark A. , Swergold Gary D.
Published: July 2002

The insertion of mobile elements into the genome represents a new class of genetic markers for the study of human evolution. Long interspersed elements (LINEs) have amplified to a copy number of about 100,000 over the last 100 million years of mammalian evolution and comprise ∼15% of the human genome. The majority of LINE-1 (L1) elements within the human genome are 5′ truncated copies of a few active L1 elements that are capable of retrotransposition. Some of the young L1 elements have inserted into the human genome so recently that populations are polymorphic for the presence of an L1 element at a particular chromosomal location. L1 insertion polymorphisms offer several advantages over other types of polymorphisms for human evolution studies. First, they are typed by rapid, simple, polymerase chain reaction (PCR)-based assays. Second, they are stable polymorphisms that rarely undergo deletion. Third, the presence of an L1 element represents identity by descent, because the probability is negligible that two different young L1 repeats would integrate independently between the exact same two nucleotides. Fourth, the ancestral state of L1 insertion polymorphisms is known to be the absence of the L1 element, which can be used to root plots/trees of population relationships. Here we report the development of a PCR-based display for the direct identification of dimorphic L1 elements from the human genome. We have also developed PCR-based assays for the characterization of six polymorphic L1 elements within the human genome. PCR analysis of human/rodent hybrid cell line DNA samples showed that the polymorphic L1 elements were located on several different chromosomes. Phylogenetic analysis of nonhuman primate DNA samples showed that all of the recently integrated “young” L1 elements were restricted to the human genome and absent from the genomes of nonhuman primates. Analysis of a diverse array of human populations showed that the allele frequencies and level of heterozygosity for each of the L1 elements was variable. Polymorphic L1 elements represent a new source of identical–by-descent variation for the study of human evolution.

[The sequence data described in this paper have been submitted to the GenBank data library under accession nos. AF242435–AF242451.]
A Resource of Mapped Human Bacterial Artificial Chromosome Clones
Authors: Cheung Vivian G. , Dalrymple Heather L. , Narasimhan Sandya , Watts Jason , Schuler Gregory , Raap Anton K. , Morley Michael , Bruzel Alan
Published: July 2002

To date, despite the increasing number of genomic tools, there is no repository of ordered human BAC clones that covers entire chromosomes. This project presents a resource of mapped large DNA fragments that span eight human chromosomes at ∼1-Mb resolution. These DNA fragments are bacterial artificial chromosome (BAC) clones anchored to sequence tagged site (STS) markers. This clone collection, which currently contains 759 mapped clones, is useful in a wide range of applications from microarray-based gene mapping to identification of chromosomal mutations. In addition to the clones themselves, we describe a database, GenMapDB (http://genomics.med.upenn.edu/genmapdb), that contains information about each clone in our collection.
Assessment of Polymorphism in Zebrafish Mapping Strains
Authors: Nechiporuk Alex , Finney Janet E. , Keating Mark T. , Johnson Stephen L.
Published: July 2002

To assess the level of heterozygosity within two commonly used inbred mapping zebrafish strains, C32 and SJD, we genotyped polymorphic CA-repeat markers randomly dispersed throughout the zebrafish genome. (For clarity purposes we will primarily use the term polymorphic to define polymorphism between strains, and the term heterozygous to address heterogeneity within a strain.) Eight male individuals each from C32 and SJD stocks were typed for 235 and 183 markers, respectively. Over 90% of the markers typed were polymorphic between these two strains. We found a limited number of heterozygous markers persisting in clusters within each inbred line. In the SJD strain, these were mainly limited to a few telomeric regions or regions otherwise distant from centromeres. As expected, centromeric regions were homozygous in the SJD strain, consistent with its derivation from a single half-tetrad individual. In contrast, heterozygous clusters were distributed randomly throughout the genome in the C32 strain, and these clusters could be detected with linked polymorphic markers. Nevertheless, most regions of the C32 strain are homozygous for CA-repeat markers in current stocks. This identification of the heterozygous regions within C32 and SJD lines should permit rapid fixation of these remaining regions in future generations of inbreeding. In addition, we established levels of polymorphism between the inbred, C32 and SJD, strains and three other commonly used strains, the *AB, WIK, and Florida wild type (hereafter referred as EKK), with CA-repeat markers as well as SSCP polymorphisms. These data will maximize the use of these strains in mapping experiments.
pCREB in the Neonate Rat Olfactory Bulb Is Selectively and Transiently Increased by Odor Preference–Conditioned Training
Authors: McLean John H. , Harley Carolyn W. , Darby-King Andrea , Yuan Qi
Published: July 2002

Early olfactory preference learning in rat pups occurs when novel odors are paired with tactile stimulation, for example stroking. cAMP-triggered phosphorylation of cAMP response element binding protein (pCREB) has been implicated as a mediator of learning and memory changes in various animals (Frank and Greenberg 1994). In the present study we investigate whether CREB is phosphorylated in response to conditioned olfactory training as might be predicted given the proposed role of the phosphorylated protein in learning.

On postnatal day 6, pups were trained for 10 min using a standard conditioned olfactory learning paradigm in which a conditioned stimulus, Odor, was either used alone or paired with an unconditioned stimulus, Stroking (using a fine brush to stroke the pup). In some instances stroking only was used. The pups were sacrificed at 0, 10, 30, or 60 min after the training. Using Western blot analysis, we observed that the majority of olfactory bulbs in conditioned pups (Odor + Stroking) had a greater increase in pCREB activation at 10 min after training than pups given nonlearning training (Odor only or Stroking only). The phosphorylated protein levels were low at 0 min and at 60 min after training. This is in keeping with the slightly delayed and short-lived activation period for this protein.

The localization of pCREB increases within the olfactory bulb as seen by immunocytochemistry. Naive pups were not exposed to odor or training. There was a significantly higher level of label in mitral cell nuclei within the dorsolateral quadrant of the bulb of pups undergoing odor-stroke pairing. No significant differences were observed among nonlearning groups (Naive, Odor only, or Stroking only) or among any training groups in the granule or periglomerular cells of the dorsolateral region. The localized changes in the nuclear protein are consistent with studies showing localized changes in the bulb in response to a learned familiar odor. The present study demonstrates that selective increases in pCREB occur as an early step following pairing procedures that normally lead to the development of long-term olfactory memories in rat pups. These results support the hypothesized link between pCREB and memory formation.
Arabidopsis Contains Ancient Classes of Differentially Expressed Actin-Related Protein Genes
Authors: McKinney Elizabeth Cohen , Kandasamy Muthugapatti K. , Meagher Richard B.
Published: July 2002

Actin-related proteins (ARPs) share less than 60% amino acid sequence homology with conventional actins and have roles in diverse cytoskeletal processes in the cytoplasm and nucleus. The genome of Arabidopsis was explored for possible ARP gene family members. Eight potential ARP gene sequences were found dispersed on three of the five Arabidopsis chromosomes. AtARP2 and AtARP3 are protein orthologs of their similarly named counterparts in other kingdoms. AtARP4, AtARP5, and AtARP6 are orthologs of two classes of nuclear ARPs previously characterized in animals and fungi, BAF53s and ARP6s. AtARP7 and AtARP8 appear to be novel proteins that are not closely related to any known animal or fungal ARPs, and may be plant specific. The complex Arabidopsis ARP gene structures each contain from five to 20 exons. Expressed transcripts were identified and characterized for AtARP2 through AtARP8, but not for AtARP9, and transcripts representing two splice variants were found for AtARP8. The seven expressed genes are predicted to encode proteins ranging from 146 to 471 amino acids in length. Relative to conventional actin and the other ARPs, AtARP2 and AtARP3 transcripts are expressed at very low levels in all organs. AtARP5,AtARP6, and AtARP8 each have distinct transcript expression patterns in seedlings, roots, leaves, flowers, and siliques. Using isovariant-specific monoclonal antibodies, AtARP4 and AtARP7 proteins were shown to be most highly expressed in flowers. The likely involvement of plant ARPs in actin nucleation, branching of actin filaments, chromatin restructuring, and transcription are briefly discussed.
Direct Interference with Rhamnogalacturonan I Biosynthesis in Golgi Vesicles
Authors: Skjøt Michael , Pauly Markus , Bush Maxwell S. , Borkhardt Bernhard , McCann Maureen C. , Ulvskov Peter
Published: July 2002

Pectin is a class of complex cell wall polysaccharides with multiple roles during cell development. Assigning specific functions to particular polysaccharides is in its infancy, in part, because of the limited number of mutants and transformants available with modified pectic polymers in their walls. Pectins are also important polymers with diverse applications in the food and pharmaceutical industries, which would benefit from technology for producing pectins with specific functional properties. In this report, we describe the generation of potato (Solanum tuberosum L. cv Posmo) tuber transformants producing pectic rhamnogalacturonan I (RGI) with a low level of arabinosylation. This was achieved by the expression of a Golgi membrane-anchored endo-α-1,5-arabinanase. Sugar composition analysis of RGI isolated from transformed and wild-type tubers showed that the arabinose content was decreased by approximately 70% in transformed cell walls compared with wild type. The modification of the RGI was confirmed by immunolabeling with an antibody recognizing α-1,5-arabinan. This is the first time, to our knowledge, that the biosynthesis of a plant cell wall polysaccharide has been manipulated through the action of a glycosyl hydrolase targeted to the Golgi compartment.
Nearest-Neighbor Analysis of Higher-Plant Photosystem I Holocomplex
Authors: Jansson S. , Andersen B. , Scheller H. V.
Published: July 2002

Photosystem I (PSI) preparations from barley (Hordeum vulgare) and spinach (Spinacia oleracea) were subjected to chemical cross-linking using the cleavable homobifunctional cross-linkers dithiobis(succinimidylpropionate) and 3,3[prime]-dithiobis(sulfosuccinimidyl-propionate). The overall pattern of cross-linked products was analyzed by the simple but powerful technique of diagonal electrophoresis, in which the disulfide bond in the cross-linker was cleaved between the first and second dimensions of the gel, and immunoblotting. A large number of cross-linked products were identified. Together with preexisting data on the structure of PSI, it was deduced that the subunits PSI-D, PSI-H, PSI-I, and PSI-L occupy one side of the complex, whereas PSI-E, PSI-F, and PSI-J occupy the other. PSI-K and PSI-G appear to be adjacent to Lhca3 and Lhca2, respectively, and not close to the other small subunits. Experiments with isolated light-harvesting complex I preparations indicate that the subunits are organized as dimers, which seem to associate to the PSI-A/PSI-B proteins independent of each other. We suggest which PSI subunit corresponds to each membrane-spanning helix in the cyanobacterial PSI structure, and present a model for higher-plant PSI.
Ethylene-Mediated Phospholipid Catabolic Pathway in Glucose-Starved Carrot Suspension Cells1
Authors: Hyun Lee Soo , Sook Chae Hyun , Kyun Lee Taek , Hee Kim Se , Ho Shin Sung , Huey Cho Bong , Ho Cho Sung , Kang Bin G. , Sung Lee Woo
Published: July 2002

Glucose (Glc) starvation of suspension-cultured carrot (Daucus carotaL.) cells resulted in sequential activation of phospholipid catabolic enzymes. Among the assayed enzymes involved in the degradation, phospholipase D (PLD) and lipolytic acyl hydrolase were activated at the early part of starvation, and these activities were followed by β-oxidation and the glyoxylate cycle enzymes in order. The activity of PLD and lipolytic acyl hydrolase was further confirmed by in vivo-labeling experiments. It was demonstrated that Glc added to a medium containing starving cells inhibited the phospholipid catabolic activities, indicating that phospholipid catabolism is negatively regulated by Glc. There was a burst of ethylene production 6 h after starvation. Ethylene added exogeneously to a Glc-sufficient medium activated PLD, indicating that ethylene acts as an element in the signal transduction pathway leading from Glc depletion to PLD activation. Activation of lipid peroxidation, suggestive of cell death, occurred immediately after the decrease of the phospholipid degradation, suggesting that the observed phospholipid catabolic pathway is part of the metabolic strategies by which cells effectively survive under Glc starvation.
Differential Expression of the Arabidopsis Nia1 andNia2 Genes1
Authors: Yu Xiaodan , Sukumaran Sujatha , Márton László
Published: July 2002

Nitrate reductase (NR) activity increased up to 14-fold in response to treatment of Arabidopsis thaliana seedlings with the cytokinin benzyladenine. NR induction was observed in seedlings germinated directly on cytokinin-containing medium, seedlings transferred to cytokinin medium, and seedlings grown in soil in which cytokinin was applied directly to the leaves. About the same level of induction was seen in both wild-type and Nia2-deletion mutants, indicating that increased NR activity is related to the expression of the minor NR gene, Nia1. The steady-stateNia1 mRNA level was increased severalfold in both wild-type and mutant seedlings after benzyladenine treatment. Transcript levels of the Nia2 gene, which is responsible for 90% of the NR activity in developing wild-type seedlings, did not show any changes upon cytokinin treatment. Nuclear run-on assays demonstrated that Nia1 gene transcription increased dramatically after cytokinin treatment.
Quantitative Intercellular Localization of NADH-Dependent Glutamate Synthase Protein in Different Types of Root Cells in Rice Plants1
Authors: Hayakawa Toshihiko , Hopkins Laura , Peat Lucy J. , Yamaya Tomoyuki , Tobin Alyson K.
Published: July 2002

The quantitative analysis with immunogold-electron microscopy using a single-affinity-purified anti-NADH-glutamate synthase (GOGAT) immunoglobulin G (IgG) as the primary antibody showed that the NADH-GOGAT protein was present in various forms of plastids in the cells of the epidermis and exodermis, in the cortex parenchyma, and in the vascular parenchyma of root tips (<10 mm) of rice (Oryza sativa) seedlings supplied with 1 mm NH4+ for 24 h. The values of the mean immunolabeling density of plastids were almost equal among these different cell types in the roots. However, the number of plastids per individual cell type was not identical, and some parts of the cells in the epidermis and exodermis contained large numbers of plastids that were heavily immunolabeled. Although there was an indication of labeling in the mitochondria using the single-affinity-purified anti-NADH-GOGAT IgG, this was not confirmed when a twice-affinity-purified IgG was used, indicating an exclusively plastidial location of the NADH-GOGAT protein in rice roots. These results, together with previous work from our laboratory (K. Ishiyama, T. Hayakawa, and T. Yamaya [1998] Planta 204: 288–294), suggest that the assimilation of exogeneously supplied NH4+ions is primarily via the cytosolic glutamine synthetase/plastidial NADH-GOGAT cycle in specific regions of the epidermis and exodermis in rice roots. We also discuss the role of the NADH-GOGAT protein in vascular parenchyma cells.
Iron Superoxide Dismutase Protects against Chilling Damage in the Cyanobacterium Synechococcus species PCC79421
Authors: Thomas David J. , Thomas Jannette B. , Prier Shane D. , Nasso Nicole E. , Herbert Stephen K.
Published: July 2002

A strain ofSynechococcus sp. PCC7942 lacking functional Fe superoxide dismutase (SOD), designatedsodB−, was characterized by its growth rate, photosynthetic pigments, inhibition of photosynthetic electron transport activity, and total SOD activity at 0°C, 10°C, 17°C, and 27°C in moderate light. At 27°C, thesodB− and wild-type strains had similar growth rates, chlorophyll and carotenoid contents, and cyclic photosynthetic electron transport activity. ThesodB− strain was more sensitive to chilling stress at 17°C than the wild type, indicating a role for FeSOD in protection against photooxidative damage during moderate chilling in light. However, both the wild-type andsodB− strains exhibited similar chilling damage at 0°C and 10°C, indicating that the FeSOD does not provide protection against severe chilling stress in light. Total SOD activity was lower in the sodB− strain than in the wild type at 17°C and 27°C. Total SOD activity decreased with decreasing temperature in both strains but more so in the wild type. Total SOD activity was equal in the two strains when assayed at 0°C.
The Delivery of Salts to the Xylem. Three Types of Anion Conductance in the Plasmalemma of the Xylem Parenchyma of Roots of Barley
Authors: Köhler Barbara , Raschke Klaus
Published: July 2002

To explore possible pathways for anions to enter the xylem in the root during the transport of salts to the shoot, we used the patch-clamp method on protoplasts prepared from the xylem parenchyma of barley (Hordeum vulgare L.) plants. K+ currents were suppressed by tetraethylammonium orN-methylglucamine in the solutions in the pipette and the bath, and the permeating anions were Cl− or NO3  −. We recorded the activities of three distinct anion conductances: (a) an inwardly rectifying anion channel (X-IRAC), characterized by activation at hyperpolarization and open times of up to several seconds; (b) a quickly activating anion conductance (X-QUAC), important for anion efflux at voltages between −50 mV and the equilibrium potential of the prevailing anion; and (c) a slowly activating anion conductance (X-SLAC), activating above −100 mV. Both X-IRAC and X-QUAC were permeable for Cl− and NO3  −; X-QUAC was also permeable for malate. The occurrence of X-IRAC became more frequent with an increase in cytoplasmic Ca2+, while the occurrence of X-QUAC decreased. Anion currents through X-SLAC, and particularly through X-QUAC, were estimated to be large enough to account for reported rates of xylem loading, which is in accordance with the notion that xylem loading is a passive process.
Calcium-Independent Activation of Salicylic Acid-Induced Protein Kinase and a 40-Kilodalton Protein Kinase by Hyperosmotic Stress
Authors: Hoyos Mary Elizabeth , Zhang Shuqun
Published: July 2002

Reversible protein phosphorylation/dephosphorylation plays important roles in signaling the plant adaptive responses to salinity/drought stresses. Two protein kinases with molecular masses of 48 and 40 kD are activated in tobacco cells exposed to NaCl. The 48-kD protein kinase was identified as SIPK (salicylic acid-induced protein kinase), a member of the tobacco MAPK (mitogen-activated protein kinase) family that is activated by various other stress stimuli. The activation of the 40-kD protein kinase is rapid and dose-dependent. Other osmolytes such as Pro and sorbitol activate these two kinases with similar kinetics. The activation of 40-kD protein kinase is specific for hyperosmotic stress, as hypotonic stress does not activate it. Therefore, this 40-kD kinase was named HOSAK (high osmotic stress-activated kinase). HOSAK is a Ca2+-independent kinase and uses myelin basic protein (MBP) and histone equally well as substrates. The kinase inhibitor K252a rapidly activates HOSAK in tobacco cells, implicating a dephosphorylation mechanism for HOSAK activation. Activation of both SIPK and HOSAK by high osmotic stress is Ca2+ and abscisic acid (ABA) independent. Furthermore, mutation in SOS3locus does not affect the activation of either kinase in Arabidopsis seedlings. These results suggest that SIPK and 40-kD HOSAK are two new components in a Ca2+- and ABA-independent pathway that may lead to plant adaptation to hyperosmotic stress.
fhy3-1 Retains Inductive Responses of Phytochrome A
Authors: Yanovsky Marcelo J. , Whitelam Garry C. , Casal Jorge J.
Published: July 2002

The fhy3 mutation of Arabidopsis impairs phytochrome A (phyA)-mediated inhibition of hypocotyl growth without affecting the levels of phyA measured spectrophotometrically or immunochemically. We investigated whether the fhy3-1 mutation has similar effects on very low fluence responses (VLFR) and high irradiance responses (HIR) of phyA. When exposed to hourly pulses of far-red light, etiolated seedlings of the wild type or of thefhy3-1 mutant showed similar inhibition of hypocotyl growth, unfolding of the cotyledons, anthocyanin synthesis, and greening upon transfer to white light. In the wild type, continuous far-red light was significantly more effective than hourly far-red pulses (at equal total fluence). In the fhy3-1 mutant, hourly pulses were as effective as continuous far-red light, i.e. the failure of reciprocity typical of HIR was not observed. Germination was similarly promoted by continuous or pulsed far-red in wild-type andfhy3-1 seeds. Thus, for hypocotyl growth, cotyledon unfolding, greening, and seed germination, the fhy3-1mutant retains VLFR but is severely impaired in HIR. These data are consistent with the idea that VLFR and HIR involve divergent signaling pathways of phyA.
Induction of a C4-Like Mechanism of CO2Fixation in Egeria densa, a Submersed Aquatic Species
Authors: Casati Paula , Lara Marı́a V. , Andreo Carlos S.
Published: July 2002

The expression of phosphoenolpyruvate carboxylase (PEPC) and NADP-malic enzyme (NADP-ME) in Egeria densaleaves was studied under low temperature and light (LTL) following incubation under high temperature and light (HTL), conditions previously shown to induce high and low CO2 compensation points, respectively. Transfer from LTL to HTL conditions induced increases in the activities and amounts of both enzymes. One NADP-ME isoform was observed in induced and uninduced samples. Two isoforms of PEPC were expressed, with the lower M  risoform being induced by HTL. NADP-ME showed properties similar to those of the isoform in C3 species. The inducible PEPC isoform has a low K  m for both substrates. PEPC kinetic and regulatory properties (V  maxand K  m for phosphoenolpyruvate, and I  50for l-malate) are different in samples taken in the dark from those in the light, indicating that some modification of PEPC may be occurring during the day. Finally, abscisic acid induced the expression of PEPC and NADP-ME in a manner similar to temperature induction, except that the activities of both PEPC isoforms were increased. A different signaling system may exist in this species in response to high temperature or abscisic acid, both of which induce changes in photosynthetic metabolism.
Phosphate Availability Regulates Root System Architecture in Arabidopsis
Authors: Williamson Lisa C. , Ribrioux Sebastien P.C.P. , Fitter Alastair H. , Leyser H.M. Ottoline
Published: July 2002

Plant root systems are highly plastic in their development and can adapt their architecture in response to the prevailing environmental conditions. One important parameter is the availability of phosphate, which is highly immobile in soil such that the arrangement of roots within the soil will profoundly affect the ability of the plant to acquire this essential nutrient. Consistent with this, the availability of phosphate was found to have a marked effect on the root system architecture of Arabidopsis. Low phosphate availability favored lateral root growth over primary root growth, through increased lateral root density and length, and reduced primary root growth mediated by reduced cell elongation. The ability of the root system to respond to phosphate availability was found to be independent of sucrose supply and auxin signaling. In contrast, shoot phosphate status was found to influence the root system architecture response to phosphate availability.
Plant‐based alkaloids inhibit corrosion of marine alloys
Authors: Mukherjee D. , Berchman J. , Rajsekkar A. , Sundarsanan N. , Mahalingam R. , Maruthamuthu S. , Thiruchelvam T. , Karaikudi Degri
Published: July 2002

The term microbiologically induced corrosion (MIC) appears to be very closely related to the composition of the bio‐film which harbours the micro‐organism. Formation of an initial slimy layer on immersed metallic substrates is the rate‐controlling parameter of bio‐fouling, as uninterrupted undesirable growth of bio‐films occurs over this layer. To contain this bio‐film problem, formation of an adherent layer of toxic and inhibited corrosion product, that interacts with biofilm, could be exploited. Deals with the preliminary interactions of a few copper‐based alloys, with mildly toxic alkaloid class‐inhibitive compounds, in a simulated marine environment. It is assumed that the toxic and inhibited corrosion product and bio‐film interaction layer will interfere with the formation of the initial slimy cover on the immersed surface, responsible for bio‐fouling. It is seen that these alkaloid compounds exert a limited response on the inhibition of copper‐based alloys like monel. Brucine appears to be a more effective inhibitor for the monel surface. Pre‐oxidation of the uninhibited brass surface and also post‐oxidation of the inhibited surface appear to consolidate the corrosion product bio‐film‐inhibitor interaction layers, indicating the compatibility of these alkaloid compounds to the probable thermal strains to be encountered in engineering services. This indicates the possibility of using these compounds in heat transfer devices, like heat exchangers, where seawater is used as coolant.
Women in part time management in the retail sector
Authors: McIntyre Jacqueline
Published: July 2002

The retail sector faces a major challenge to its store management strategies as a result of changing trading conditions and recent legislation allowing extended opening hours. Previous work by the author has considered the possibility of utilising part time female managers to help provide a solution to these problems. This paper, using one major retailer as the base for the research, examines the extent to which women themselves are ready and willing to play such a role.
Contextual factors of psychological empowerment
Authors: Siegall Marc , Gardner Susan
Published: July 2002

This paper examines the relationships between four contextual factors related to empowerment (communication with supervisor, general relations with company, teamwork, and concern for performance) and the four components of psychological empowerment (meaning, impact, self‐determination, and competence) identified by Spreitzer and her colleagues. We surveyed 203 employees of a manufacturing firm, using new and established measures of contextual factors and Spreitzer’s measures of empowerment components. The contextual factors were found to be differentially associated with the elements of psychological empowerment. Communication with supervisor and general relations with company were significantly related to the empowerment facets of meaning, self‐determination, and impact, but were not related to the facet of competence. Teamwork was related to meaning and impact. Concern for performance was related to meaning and self‐determination. These associations also varied by type of job. We conclude with implications for research and practice.
Managing work‐family diversity for parents of disabled children – Beyond policy to practice and partnership
Authors: Lewis Suzan , Kagan Carolyn , Heaton Patricia
Published: July 2002

An area of diversity currently receiving attention is the large proportion of the workforce with commitments to care for a family. Many organisations have introduced “family friendly” policies including parental leave, childcare assistance and reduced hours of work. But this tends to focus on mothers of healthy, young children. The intense, long‐term needs of disabled children can severely stretch the provision organisations make for parents. This article presents an interview survey of parents with disabled children. It argues that, while many of the parents experience problems establishing a work‐home balance, these are partly caused by blocks within the wider community. Organisations can certainly reap benefits from making special arrangements for employees with disabled children but there are limits to corporate responsibility in relation to non‐work barriers. The article highlights the need for diversity initiatives to look beyond the workplace and incorporate aspects of the wider context in which organisations operate.
The failure of competence‐based management education in the public sector – A problem of generic transfer or implementation?
Authors: Boyett Inger , Currie Graeme
Published: July 2002

This paper presents a case study of a management development programme, which adopts a competence‐based approach aimed at middle managers in a further education college. The programme takes place in a context that promotes the concept of general management. However, the programme, in which the general management approach is embedded, is resisted by the participating middle managers, to the extent that the programme “collapses” half way through and is never revived. As the paper suggests, there may be two reasons for this. First, in considering any potential relationship between public and private sectors, a key question is whether generic transfer of managerial ideas and practices from private to the public sector is appropriate. Second, it may be a question of the way in which the programme was implemented and delivered.
Testing the SMT and Belbin inventories in top management teams
Authors: Lessem Ronnie , Baruch Yehuda
Published: July 2002

This article focuses on, examines and contrasts two managerial inventories: the Spectral management theory (SMT) and the Belbin team roles inventory. The SMT inventory is one of the only approaches that involves not only a management typology, but also learning roles as well as team assessment. The theory leads to eight such types of managerial style, measured through an analytical instrument designed to enable people to identify their personal orientations. Belbin’s inventory is focused on team roles, prescribing nine options. Both were used to analyse members of top management teams in leading UK management buy‐outs. The analysis undertaken serves to enhance self awareness in the individual as well as team and organisational effectiveness. At the team level, it highlights the antecedents of successful teams, how and why they work together in harmony or dissonance, and what other teams may learn from the exercise.
The multi‐dimensional nature of organisational commitment in a non‐western context
Authors: Suliman Abubakr M. , Iles Paul A.
Published: July 2002

Examines the validity and reliability of affective, continuance and normative commitment in the Jordanian context. Using a self‐administered questionnaire, 1,000 employees were surveyed. The study questionnaire was piloted in three industrial firms before being used in the main study. The results from the pilot and main studies reveal that of the three dimensions mentioned above, two are prevalent in the Jordanian work environment, namely: the affective and continuance commitments. The existence of normative commitment in the Jordanian work setting is not supported by the findings of the study. Implications for our understanding of commitment’s role in Jordan and other Arab countries are also discussed in the paper.
Performance measurement systems ‐ a case study of customer satisfaction
Authors: Walters Megan
Published: July 2002

This paper discusses the problems for facilities managers in measuring the contribution of property towards the primary task, taking into account the different goals of the various stakeholders within the organisation. It suggests that the types of performance measures used to measure the property resource should reflect the culture of the primary task, rather than reflecting traditional property measures found in investment property management. A case study of a project undertaken for the Estates Management Department of the Mass Transit Railway Corporation of Hong Kong is reviewed, where measures of customer satisfaction were devised to measure property performance, in accordance with the culture of the primary task of the organisation.
The time bounded glass ceiling and young women managers: career progress and career success – evidence from the UK
Authors: Simpson Ruth , Altman Yochanan
Published: July 2002

This article presents evidence on the career success of young women managers and suggests an interaction between age and seniority as young women managers outpace their male counterparts in career progression. Hence the glass ceiling may be seen as “time bounded”. Three alternative explanations are presented: a sea change in women’s careers; that young women’s careers are fundamentally different from older women’s; that the glass ceiling moved up the hierarchy and affects only senior positions.
The under‐representation of women in senior management in UK independent secondary schools
Authors: McLay Margaret , Brown Marie
Published: July 2002

Statistics show that women are under‐represented in senior management posts in UK independent schools, especially in the secondary sector. Reviews recent studies on women in senior roles in independent schools, concentrating on the secondary sector and comparing the situation with some studies from the maintained sector. Suggests that much needs to be done to improve the status of women in many independent schools, but that further research needs to be done across the whole independent secondary sector to assess how widespread negative attitudes are. Also suggests that training courses should be suited to women’s needs and that mentoring should be more widely available.
Management concerns in United Arab Emirates state schools
Authors: Shaw K.E. , Badri A.A.M.A. , Hukul A.
Published: July 2002

Examines the context for management studies of Gulf schooling,
indicates areas of concern, suggests topics for research and discusses
field research in Dubai. Most staff are Arabic‐speaking expatriates, and
reliable statistical information is not at present available. Education
is a free gift to citizens who are not taxed, and is thus unaccountable.
A public policy tradition hardly exists. Decision making is in the hands
of a heavily bureaucratic local ministry, and tends to lack coherence.
There is a pressing need for research in management, particularly in the
key area of reducing educational wastage rates. Management of contract
expatriate staff, policy at institutional level, staff development,
curricular issues and teacher training also merit study.
The role of intermetallic compounds in lead‐free soldering
Authors: Harris Paul G. , Chaggar Kaldev S.
Published: July 2002

The role of intermetallics in soldered joints is ambivalent. They are an essential part of joints to common basis materials and at low levels they have a strengthening effect on solder alloys. At higher levels, however, it is well known that they can cause joint embrittlement. In this paper three aspects of their role have been studied: the microstructure of intermetallic containing solder alloys, the effects of soldering parameters on the quantity of intermetallic formed and, finally, the rates of growth of intermetallic compounds in the solid state. The results suggest that alloys which are pre‐doped with copper tend to form slightly more interfacial intermetallic during soldering than those which are not. In the solid state the rates of growth appear to be a function of the melting point of the alloy, with the higher melting point lead‐free alloys exhibiting lower rates than lower melting point alloys such as 63Sn37Pb (183∞C) or 42Sn58Bi (138∞C).
Is equity always best?
Authors: Perry Eleanor A.
Published: July 2002

Notes that increased legislation promoting educational equity, court decisions favouring inclusion of special education students, and pressure to compete in a global economy provide a forum for intense debate among educational stakeholders such as administrators, special education parents, and parents of gifted children. Proposes to identify their attitudes regarding: the effectiveness of schools in providing intellectually challenging environments for a diverse population and the barriers equity might create in educating today’s students to become tomorrow’s high level, creative thinkers in a democratic society. Explores the macropolitical aspects of state‐mandated inclusion and the micropolitical barriers one superintendent faced when trying to establish equity for all students in a hostile environment where parents of special education and gifted children joined forces to campaign actively against inclusion. This unusual bonding propelled the study from a traditional research design to one which more closely resembled action research. Describes the tension existing among diverse educational stakeholders who viewed equity differently. Provides recommendations for improving educational leadership training to include strategies dealing with issues like those encountered during this research.
Conjugate natural convection of a power law fluid in a vertical finite thick channel with heat sources
Authors: Huu Chung Dang
Published: July 2002

Considers the conjugate natural convection motion of a power law fluid in a vertical finite channel, taking into account the heat transfer into channel walls as well as the effect of the existence of different heat sources distributed uniformly in the walls and in the fluid. Examines the results obtained in some test cases in more detail and shows that the influence of the wall becomes significant when the thermal conductivity of the wall is small enough. Also notes that the effect of the heat source distributed in the fluid is more considerable than in the wall.
Managing service quality in higher education: the role of the
student as primary consumer
Authors: Hill Frances M.
Published: July 2002

Discusses aspects of current service quality theory in the context
of British higher education (HE). Focuses on the role of the student as
primary consumer of HE services (a relatively recent conceptualization
in this country), and the implications of this for the management of
service quality in higher education organizations (HEOs). Briefly
discusses an exploratory study which has monitored a group of students′
expectations and perceptions of service quality over time. Because of
its limited scope, the findings of this study may not be generalized to
the student population as a whole. However, it does serve to highlight
the need for HEOs to gather information on students′ expectations, not
only during their time at university, but at the point of arrival and
before, to manage students′ expectations from enrolment through to
graduation, in order to align them as closely as possible with what can
be delivered by way of service quality, for the student evaluation
process, or upward appraisal to be dealt with in a much more detailed,
comprehensive and multi‐focused way than tends to be the case currently
at many British universities. Acknowledges the need for further research
to investigate all of these matters.
Educational accreditation through ISO 9000
Authors: Peters John
Published: July 2002

Argues a market‐orientation for the ISO 9000 quality assurance standards. Discusses the experiences of the International Management Centres (IMC) in seeking and gaining certification to ISO 9002. Argues that policing educational process delivery ‐ the keeping of promises ‐ would be a more useful activity for governmental policy‐makers than the policing of educational content ‐ the nature of the promise. Summarises in brief the clauses of ISO 9002 as they apply to IMC. Concludes with recommendations to educational institution administrators and policy‐makers.