bluuebunny/crossref_metadata_2025 huggingface dataset:
Skin disorders in pregnancy
Authors: Vaughan Jones SA , Black MM
Published: July 2002

During pregnancy there are profound metabolic, endocrine and vascular changes which are tolerated for a short period of time. As the skin represents the largest organ of the body, these changes are also reflected in the appearance of the skin both by the improvement or exacerbation of pre-existing skin disease and by the development of new dermatoses. The specific dermatoses of pregnancy are a group of disorders which only occur in the pregnant state.

This review will discuss the physiological effects of pregnancy on the appearance and function of normal skin, and other cutaneous diseases affected by pregnancy (including intrahepatic cholestasis). The latter part of the review will discuss important aspects of the specific dermatoses of pregnancy.
Effects of sex steroid hormones and their antagonists on mast cell number in the testis of the frog, Rana esculenta
Authors: Matteo L. Di , Vitiello I. Izzo , Minucci S.
Published: July 2002

This study confirms our previous data on the effects of sex hormones on mast cell number (MCN) in the testis of frog Rana esculenta. After 15 days of treatment with oestradiol (E2) MCN strongly increases, while testosterone has no effect. After 30 days only a small increase in MCN is observed. These differences could be due to the non-physiological effect of E2 over a prolonged period. We also confirmed a massive increase in MCN after 15 or 30 days of treatment with cyproterone acetate (CPA). This increase in MCN is also observed after administration of CPA with tamoxifen. Ultrastructural analysis of testis shows empty spaces with degenerating Leydig cells in the interstitial compartment and numerous germinal cells completely degenerated, probably apoptotic, in the adjacent germinal compartment. The same effects were observed in testes after treatment with only CPA. Chronic E2 treatment provokes an increase in MCN on day 2. From day 4 to 12 of the treatment, MCN decreases dramatically and many germinal tubules appear strongly disorganised. In conclusion, the present results confirm that E2 treatment induces changes in MCN and chronic E2 treatment modifies the morphology of the frog testes. In addition, blocking androgen receptors with CPA, alone or in combination with tamoxifen, causes a significant increase in MCN, confirming the involvement of androgens in mast cell proliferation and/or differentiation.
Mesoscale analyses and diagnostic parameters for deep convection nowcasting
Authors: Calas C , Ducrocq V , Sénési S
Published: July 2002

We study the contribution of surface data to convection nowcasting over regions of modest orography and under weak synoptic forcing. Hourly mesoscale analyses are performed using the CANARI optimal interpolation analysis scheme, which combines first‐guess fields from the fine mesh (10 km) ALADIN model with hourly routine observations arising from a mesonet of automated ground stations. These analyses then allow the computation of diagnostic parameters that quantify convective instability, low‐level lifting processes and moisture supply: these are the convective available potential energy (CAPE) and the moisture convergence (MOCON). A tuning of the analysis scheme is needed first for it to fit the meso‐β‐scale. Then, the skill of the computed diagnostics for convection nowcasting is evaluated by comparing their fields with radar reflectivities observed between one and four hours after the analysis time. This is done for four selected convective situations. With regard to thunderstorm triggering, results show that this usually happens over areas of persistently high values of CAPE which undergo convergence continuously from four to one hour before the event; on the other hand, areas of persistent divergence are never associated with convective developments. In addition, the proposed criteria allow a significant reduction in the areal extent of predicted thunderstorms (i.e. decreasing the false‐alarm rate) compared with what can be currently done on an operational basis, while maintaining a low non‐detection rate. As to convection monitoring, we find that the organization of convective systems into a reflectivity line is preceded by a similar organization in the MOCON field from one to three hours ahead. Copyright © 2000 Royal Meteorological Society
Point and areal PMP estimates for durations of two and three days in India
Authors: Rakhecha P R , Clark C
Published: July 2002

The risk of dam failure in India, coupled with better analysis of extreme storm events, has led to the estimation of revised one‐day probable maximum precipitation (PMP). For some water conservation projects where the catchment area is very large, there is a need to have estimates of PMP for durations of both two and three days. These are provided in this paper. It was found that the two‐day PMP over the Indian region varied from 100 cm over the central peninsula to over 290 cm in eastern India. For a duration of three days the corresponding values are 120 cm and 370 cm. For water management projects which include impounding reservoirs, an estimate has been made of the probable maximum flood (PMF) based on the new PMP estimates. The results of the design flood estimates were compared with existing estimates at the same sites and in most cases were found to be considerably higher. A comparison of the revised estimates of PMF and recorded floods in India shows that the trend of the rates of runoff in relation to catchment area differ by an average of 38% for an area of 1000 km2 and 46% for an area of 10 000 km2. These results show that some dams in India may be unsafe in the event of the probable maximum flood. Copyright © 2000 Royal Meteorological Society
Neural network retrieval of wind velocity profiles from satellite data
Authors: Cogan J , Gutman W , Measure E , Bustamante D , Vaucher G
Published: July 2002

A method has been developed for retrieval of wind velocity profiles from satellite sounder radiances using a neural network technique. Each wind velocity represents a mean value for a layer approximately centred at that standard height or pressure level. The neural network input vector includes sounder radiances from the Geostationary Operational Environmental Satellite (GOES), plus ancillary information such as latitude and longitude. A set of ‘co‐incident’ rawinsonde soundings provide the ‘truth’ data set. In the initial results root mean square errors for the standard levels from 850 to 300 hPa have about the same magnitude as those for current methods such as tracking of moisture features in GOES imagery. As with more traditional methods, the largest root mean square error occurs near the tropopause. Although the results to date appear highly promising, considerable further work is needed before we have an operationally capable technique. Copyright © 2000 Royal Meteorological Society
The Met Office upper air winds: Prediction and verification in the context of commercial aviation data
Authors: Rickard G J , Lunnon R W , Tenenbaum J
Published: July 2002

The properties of the upper air winds used by the commercial aviation community are investigated. Analysis of the spectra shows that the forecasts have errors in both power and phase. However, the constant multiplier presently applied at The Met Office to the forecast winds before they are sent to the airlines remains best for remedying the speed underestimates characteristic of the forecast winds relative to those observed. We provide evidence for the success of this multiplier including the existence of a systematic negative speed bias as a function of the forecast wind speed. A constant multiplier greater than one (presently set at 1.04) always produces reductions in the traditional speed and vector wind rms scores, as well as an aviation specific rms relative flight time error. The investigations reveal that the constant multiplier is also optimal given the verification measures used; it must therefore remain integral to the operational processing of the forecast winds before transmission to the aviation community, at least for the foreseeable future. Copyright © 2001 Royal Meteorological Society
Air quality modelling: a technical review of mathematical approaches
Authors: Collett Richard S , Oduyemi Kehinde
Published: July 2002

A short review paper is presented for the subject area of air quality modelling. The paper is geared towards equipping new researchers and workers with a basic appreciation for the technical aspects of their field, providing a staging point for further investigation, and highlighting useful source materials. The paper is introduced through a discussion of the philosophical and practical implications regarding mathematical air quality modelling. A critique of relevant mathematical modelling techniques is presented and includes a treatment of Box, Gaussian, Eulerian, Lagrangian and Particle modelling approaches. Conclusions on the future of mathematical air quality modelling are drawn. Copyright © 1997 Royal Meteorological Society
Different predictions by two NWP models of the surface pressure field east of Iceland
Authors: Ólafsson Haraldur
Published: July 2002

In February and March 1996, the French NWP model Arpège was run to give operational forecasts five days ahead. These forecasts were a part of preparations for FASTEX (Fronts and Atlantic Storm‐Track Experiment), whose field phase took place in 1997. The extensive collection and availability of model output during this period gave an excellent opportunity to study in real time the behaviour of different NWP models during the period of the year when strong winds and rapid changes in weather conditions are frequent. In this paper, we study a case where the ECMWF model predicted an incorrect pressure gradient at Northeast Iceland, while Arpège correctly simulated the gradient. The model errors are connected to anomalies in the mid‐tropospheric vorticity field, which is in general quite different in the two models. The differences in the vorticity fields are discussed in relation to orographic effects. Copyright © 1998 Royal Meteorological Society
The CyberCruiser: An investigation of development of prospective
memory in children
Authors: KERNS KIMBERLY A.
Published: July 2002

Prospective memory can be defined as the timely
execution of a previously formed intention, and is critical
in daily life because of its inherent involvement in goal-directed
behavior. Cognitive systems involved in prospective memory
have been hypothesized as involving the frontal cortex,
and in adults, associated with working memory and executive
functions. This study introduces a new computerized measure
of prospective memory designed for children. In this study
prospective memory is examined in a driving game task called
the CyberCruiser. In a sample of 80 children ages 6–12
years, variables from this task demonstrated a significant
age effect and were significantly correlated with other
well known measures of executive function, even after controlling
for chronological age. Performance on this task also demonstrated
the anticipated pattern of strategic monitoring that has
been demonstrated in other studies of prospective memory.
(JINS, 2000, 6, 62–70.)
Determinants and impact of local institutions for common resource management
Authors: Heltberg Rasmus
Published: July 2002

In this article, local institutions for forest conservation and management are analysed. The discussion is based on data from 37 villages and 180 households randomly sampled from a protected area in Rajasthan, India. Local management institutions are described, factors affecting inter-village differences in management institutions and collective action are analysed in a logit model, and the impact of institutions and other variables on common resource dependency and forest outcomes is tested using instrumental variable regression. Village population size has a positive effect and prior institutional experience a negative effect on the probability of collective action. It is concluded that efforts at improving forest management should not be confined to the poorest farmers. Large landowners are heavily involved in degrading use practises, especially when resources have good market potential. Local management institutions play a positive role in the area, but their impact appears insufficient to safeguard forests and commons from continued degradation. Conservation policies should target win–win options through interventions aimed at improving technologies for private and common lands as well as institutional changes.
Coping Strategies of Secondary School Children in Response to Being Bullied
Authors: Naylor Paul , Cowie Helen , del Rey Rosario
Published: July 2002

Through a questionnaire survey, the present study investigated the coping strategies of Year 7 (11–12 years old) and Year 9 (13–14 years old) pupils (N = 324) to find out what strategies they have used to overcome the difficulties of being bullied by peers. Fifty-one UK secondary schools, in each of which an anti-bullying peer support system had been in place for at least a year, participated. The coping strategies of those pupils who said that they had told someone (N = 279) about being bullied were compared with those who said that they had not (N = 45). These coping strategies differ, not only according to whether or not they report the bullying, but also according to their age and gender. Implications of the findings for professionals who work with children and adolescents are suggested.
Anula Nikapota
Authors: Graham Philip
Published: July 2002

At her suggestion, I arranged to meet
Anula in the late afternoon, in a pub above
John Menzies at Euston Station. As she
moved gently towards my table, scholarly-looking and draped in her sari, making her
way between chrome furniture, pints of
lager, and urgent football and shopping
chat, she seemed a character from one of
those novels about the Raj, recently displaced from an ancient civilisation
to a
crass, modern world.
Virginia Bottomley
Authors: Graham Philip
Published: July 2002

If you got into a train at Euston, and
started travelling northwards towards
Liverpool, it would be a great surprise if
you finished up in Tunbridge Wells. I had
the same sense of an impossible change of
direction when I learned about Virginia
Bottomley's early life and subsequent career. Her mother was a Conservative

Education councillor, elected after Virginia
Bottomley became an MP, but her uncle
was a Labour Cabinet minister and she
herself was the Labour candidate in her
school's mock election. Then, in the hippy,
radical, mid to late Sixties, she went on to
read sociology at the University of Essex,
surely the most radical of all the university
campuses. After graduation, she went to
work for Frank Field at the Child Poverty
Action Group. Then on to the London
School of Economics to train as a social
worker, before employment as a full-time
social worker for 10 years, first at Brixton
and then at the Camberwell Child Guidance Unit. How on earth could all
that lead
to a safe Conservative seat in Surrey and
then to two Cabinet posts in a Tory
government, first as Secretary of State for
Health and then as Secretary of State for National Heritage?
LIQUIDITY CONSTRAINTS AND INCENTIVE CONTRACTS
Authors: Lehnert Andreas , Ligon Ethan , Townsend Robert M.
Published: July 2002

Are firms and households constrained in the use of a
productive input? Theoretical approaches to this question range from
exogenously imposed credit allocation rules to endogenous market failures
stemming from some sort of limited-commitment or moral-hazard problem.
However, when testing for constraints, researchers often simply ask firms
or households if they would wish to borrow more at the current interest
rate and/or test for suboptimal use of inputs in production functions
relative to a full-information, full-commitment benchmark. We demonstrate
that if credit is part of a much larger information-constrained (or
limited-commitment) incentive scheme, then input use may very well be
distorted away from the first-best. Further, households and firms, in
certain well-defined circumstances, may, at the true interest rate or
opportunity cost of credit, desire to borrow more (or less) than the
assigned level of credit. In other, more constrained, contractual regimes,
firms and households would say that they do not want to borrow more (or
less), but these regimes are decidedly suboptimal, although the magnitude
of the loss does depend on parameter values. We conclude with empirical
methods that, in principle, could allow researchers armed with enough data
to estimate parameters and distinguish regimes. Researchers then could see
if firms and households are truly constrained and, if so, what the welfare
loss might be.
Seeds in space
Authors: Musgrave Mary E.
Published: July 2002

Since experimentation with plants began in space, a wide range of information has been gained regarding how this unique environment affects the biology of seeds. Seed biology experiments in this milieu have addressed aspects of seed storage, seed germination and metabolism, seedling orientation and seed production by flowering plants. Construction of hardware that provides a suitable growth environment in microgravity has been especially challenging because of the consequences posed by microgravity for fluid and gas distribution around the plant. Fluid shifting causes seed hydration kinetics to occur at a faster rate in microgravity than in 1 g; however, it also induces hypoxic metabolism during the seed germination process. In the absence of a detectable gravitational force, seedling roots grow according to their embryonic orientation and then initiate random walk movements. Light and oxygen gradients are the primary stimuli that orient root growth in this environment. For seed development to occur in spaceflight, well-ventilated growth chambers are necessary to support the carbohydrate supply needs of the developing embryos, and to provide the necessary humidity gradient for anthers to successfully dehisce and release pollen. The dry weight of seeds formed in space is lower than that in ground controls, and seed storage reserves are altered. Seed storage phenomena in spaceflight depend on whether or not oxygen and moisture are present – if not, viability exceeds that of seeds stored under comparable conditions on the ground. Because of the key role to be played by seeds in future advanced life support scenarios in space, more research is needed on the implications of this unique environment for seed biology.
CPEB proteins control two key steps in spermatogenesis in C. elegans
Authors: Luitjens Cameron , Gallegos Maria , Kraemer Brian , Kimble Judith , Wickens Marvin
Published: July 2002

Cytoplasmic polyadenylation element binding (CPEB) proteins bind to and regulate the translation of specific mRNAs. CPEBs fromXenopus, Drosophila, and Spisula participate in oogenesis. In this report, we examine the biological roles of all identifiable CPEB homologs in a single organism, Caenorhabditis elegans. We find four homologs in the C. elegans genome:cbp-1, cpb-2, cpb-3, and fog-1.Surprisingly, two homologs, CPB-1 and FOG-1, have key functions in spermatogenesis and are dispensable for oogenesis. CPB-2 and CPB-3 also appear not to be required for oogenesis. CPB-1 is essential for progression through meiosis: cpb-1(RNAi) spermatocytes fail to undergo the meiotic cell divisions. CPB-1 protein is present in the germ line just prior to overt spermatogenesis; once sperm differentiation begins, CPB-1 disappears. CPB-1 physically interacts with FBF, another RNA-binding protein and 3′ UTR regulator. In addition to its role in controlling the sperm/oocyte switch, we find that FBF also appears to be required for spermatogenesis, consistent with its interaction with CPEB. A second CPEB homolog, FOG-1, is required for specification of the sperm fate. The fog-1 gene produces fog-1(L) and fog-1(S) transcripts. Thefog-1(L) RNA is enriched in animals making sperm and is predicted to encode a larger protein; fog-1(S) RNA is enriched in animals making oocytes and is predicted to encode a smaller protein. The relative abundance of the two mRNAs is controlled temporally during germ-line development and by the sex determination pathway in a fashion that suggests that the fog-1(L) species encodes the active form. In sum, our results demonstrate that, in C. elegans, two CPEB proteins have distinct functions in the germ line, both in spermatogenesis: FOG-1 specifies the sperm cell fate and CPB-1 executes that decision.
MAD2B is an inhibitor of the anaphase-promoting complex
Authors: Chen James , Fang Guowei
Published: July 2002

Anaphase-promoting complex (APC), a ubiquitin ligase, controls both sister chromatid separation and mitotic exit. The APC is activated in mitosis and G1 by CDC20 and CDH1, and inhibited by the checkpoint protein MAD2, a specific inhibitor of CDC20. We show here that a MAD2 homolog MAD2B also inhibits APC. In contrast to MAD2, MAD2B inhibits both CDH1-APC and CDC20-APC. This inhibition is targeted to CDH1 and CDC20, but not directly to APC. Unlike MAD2, whose interaction with MAD1 is required for mitotic checkpoint control, MAD2B does not interact with MAD1, suggesting that MAD2B may relay a different cellular signal to APC.
Regulation of the Neurospora circadian clock by casein kinase II
Authors: Yang Yuhong , Cheng Ping , Liu Yi
Published: July 2002

Phosphorylation of clock proteins represents an important mechanism regulating circadian clocks. In Neurospora, clock protein FREQUENCY (FRQ) is progressively phosphorylated over time, and its level decreases when it is extensively phosphorylated. To identify the kinase phosphorylating FRQ and to understand the function of FRQ phosphorylation, a FRQ-phosphorylating kinase was purified and identified as casein kinase II (CKII). Disruption of the catalytic subunit gene of CKII in Neurospora resulted in hypophosphorylation and increased levels of FRQ protein. In addition, the circadian rhythms of frq RNA, FRQ protein, and clock-controlled genes are abolished in the CKII mutant. Our data suggest that the phosphorylation of FRQ by CKII may have at least three functions; it decreases the stability of FRQ, reduces the protein complex formation between FRQ and the WHITE COLLAR proteins, and is important for the closing of the Neurospora circadian negative feedback loop. Taken together, our results suggest that CKII is an important component of the Neurospora circadian clock.
Sequence and Analysis of Chromosome I of the Amitochondriate Intracellular Parasite Encephalitozoon cuniculi (Microspora)
Authors: Peyret Pierre , Katinka Michael D. , Duprat Simone , Duffieux Francis , Barbe Valérie , Barbazanges Martin , Weissenbach Jean , Saurin William , Vivarès Christian P.
Published: July 2002

A DNA sequencing program was applied to the small (<3 Mb) genome of the microsporidian Encephalitozoon cuniculi, an amitochondriate eukaryotic parasite of mammals, and the sequence of the smallest chromosome was determined. The ∼224-kb E. cuniculichromosome I exhibits a dyad symmetry characterized by two identical 37-kb subtelomeric regions which are divergently oriented and extend just downstream of the inverted copies of an 8-kb duplicated cluster of six genes. Each subtelomeric region comprises a single 16S–23S rDNA transcription unit, flanked by various tandemly repeated sequences, and ends with ∼1 kb of heterogeneous telomeric repeats. The central (or core) region of the chromosome harbors a highly compact arrangement of 132 potential protein-coding genes plus two tRNA genes (one gene per 1.14 kb). Most genes occur as single copies with no identified introns. Of these putative genes, only 53 could be assigned to known functions. A number of genes from the transcription and translation machineries as well as from other cellular processes display characteristic eukaryotic signatures or are clearly eukaryote-specific.

[The sequence data described in this paper have been submitted to the EMBL data library under accession no. AL 391737.]
Synaptic Plasticity in Hippocampal CA1 Neurons of Mice Lacking Type 1 Inositol-1,4,5-Trisphosphate Receptors
Authors: Fujii Satoshi , Matsumoto Mineo , Igarashi Kotaro , Kato Hiroshi , Mikoshiba Katsuhiko
Published: July 2002

In hippocampal CA1 neurons of wild-type mice, delivery of a standard tetanus (100 pulses at 100 Hz) or a train of low-frequency stimuli (LFS; 1000 pulses at 1 Hz) to a naive input pathway induces, respectively, long-term potentiation (LTP) or long-term depression (LTD) of responses, and delivery of LFS 60 min after tetanus results in reversal of LTP (depotentiation, DP), while LFS applied 60 min before tetanus suppresses LTP induction (LTP suppression). To evaluate the role of the type 1 inositol-1,4,5-trisphosphate receptor (IP3R1) in hippocampal synaptic plasticity, we studied LTP, LTD, DP, and LTP suppression of the field excitatory postsynaptic potentials (EPSPs) in the CA1 neurons of mice lacking the IP3R1. No differences were seen between mutant and wild-type mice in terms of the mean magnitude of the LTP or LTD induced by a standard tetanus or LFS. However, the mean magnitude of the LTP induced by a short tetanus (10 pulses at 100 Hz) was significantly greater in mutant mice than in wild-type mice. In addition, DP or LTP suppression was attenuated in the mutant mice, the mean magnitude of the responses after delivery of LFS or tetanus being significantly greater than in wild-type mice. These results suggest that, in hippocampal CA1 neurons, the IP3R1 is involved in LTP, DP, and LTP suppression but is not essential for LTD. The facilitation of LTP induction and attenuation of DP and LTP suppression seen in mice lacking the IP3R1 indicates that this receptor plays an important role in blocking synaptic potentiation in hippocampal CA1 neurons.
Input-Specific Immunolocalization of Differentially Phosphorylated Kv4.2 in the Mouse Brain
Authors: Varga Andrew W. , Anderson Anne E. , Adams J. Paige , Vogel Hannes , Sweatt J. David
Published: July 2002

Voltage-gated A-type potassium channels such as Kv4.2 regulate generation of action potentials and are localized abundantly in the hippocampus and striatum. Phosphorylation consensus sites for various kinases exist within the sequence of the potassium channel subunit Kv4.2, including consensus sites for extracellular signal-regulated kinase/mitogen activated protein kinase (ERK/MAPK), protein kinase A (PKA), protein kinase C (PKC), and calcium/calmodulin-dependent kinase II (CaMKII), and kinase assays have shown that particular amino acids of the consensus sites are bonafide phosphorylation sites in vitro. We have developed antibodies recognizing Kv4.2 triply phosphorylated at the three ERK sites as well as two antibodies recognizing singly phosphorylated Kv4.2 channels at the PKA sites (one amino-terminal and one carboxy-terminal). In the present study, we report the development of reliable immunohistochemistry protocols to study the localization of these phosphorylated versions of Kv4.2, as well as total Kv4.2 in the mouse brain. A general description of the areas highlighted by these antibodies includes the hippocampus, amygdala, cortex, and cerebellum. Such areas display robust synaptic plasticity and have been implicated in spatial, associative, and motor learning. Interestingly, in the hippocampus, the antibodies to differentially phosphorylated Kv4.2 channels localize to specific afferent pathways, indicating that the Kv4.2 phosphorylation state may be input specific. For example, the stratum lacunosum moleculare, which receives inputs from the entorhinal cortex via the perforant pathway, displays relatively little ERK-phosphorylated Kv4.2 or PKA carboxy-terminal-phosphorylated Kv4.2. However, this same layer is highlighted by antibodies that recognize Kv4.2 that has been phosphorylated by PKA at the amino terminus. Similarly, of the three antibodies tested, the soma of CA3 neurons are primarily recognized by the ERK triply phosphorylated Kv4.2 antibody, and the mossy fiber inputs to CA3 are primarily recognized by the carboxy-terminal PKA-phosphorylated Kv4.2. This differential phosphorylation is particularly interesting in two contexts. First, phosphorylation may be serving as a mechanism for targeting. For example, the amino-terminal PKA phosphorylation may be acting as a tag for a discrete pool of Kv4.2 to enter stratum lacunosum moleculare. Second, as phosphorylation may regulate channel biophysical properties, differential phosphorylation of Kv4.2 in the dendrites of pyramidal neurons may confer unique biophysical properties upon particular dendritic input layers.
A Plant Gene Up-Regulated at Rust Infection Sites
Authors: Ayliffe Michael A. , Roberts James K. , Mitchell Heidi J. , Zhang Ren , Lawrence Gregory J. , Ellis Jeffrey G. , Pryor Tony J.
Published: July 2002

Expression of the fis1 gene from flax (Linum usitatissimum) is induced by a compatible rust (Melampsora lini) infection. Infection of transgenic plants containing a β-glucuronidase (GUS) reporter gene under the control of the fis1 promoter showed that induction is highly localized to those leaf mesophyll cells within and immediately surrounding rust infection sites. The level of induction reflects the extent of fungal growth. In a strong resistance reaction, such as the hypersensitive fleck mediated by the L6resistance gene, there is very little fungal growth and a microscopic level of GUS expression. Partially resistant flax leaves show levels of GUS expression that were intermediate to the level observed in the fully susceptible infection. Sequence and deletion analysis using both transient Agrobacterium tumefaciens expression and stable transformation assays have shown that the rust-induciblefis1 promoter is contained within a 580-bp fragment. Homologs of fis1 were identified in expressed sequence tag databases of a range of plant species including dicots, monocots, and a gymnosperm. Homologous genes isolated from maize (Zea mays; mis1), barley (Hordeum vulgare; bis1), wheat (Triticum aestivum; wis1), and Arabidopsis encode proteins that are highly similar (76%–82%) to the FIS1 protein. The Arabidopsis homologue has been reported to encode a Δ1-pyrroline-5-carboxylate dehydrogenase that is involved in the catabolism of proline to glutamate. RNA-blot analysis showed that mis1 in maize and the bis1homolog in barley are both up-regulated by a compatible infection with the corresponding species-specific rust. The rust-induced genes homologous to fis1 are present in many plants. The promoters of these genes have potential roles for the engineering of synthetic rust resistance genes by targeting transgene expression to the sites of rust infection.
Characterization of Chloroplast Division Using the Arabidopsis Mutant arc5
Authors: Robertson E. J. , Rutherford S. M. , Leech R. M.
Published: July 2002

arc5 is a chloroplast division mutant of Arabidopsis thaliana. To identify the role of ARC5 in the chloroplast replication process we have followed the changes in arc5 chloroplasts during their perturbed division. ARC5 does not affect proplastid division but functions at a later stage in chloroplast development. Chloroplasts in developing mesophyll cells of arc5 leaves do not increase in number and all of the chloroplasts in mature leaf cells show a central constriction. Young arc5 chloroplasts are capable of initiating the division process but fail to complete daughter-plastid separation. Wild-type plastids increase in number to a mean of 121 after completing the division process, but in the mutant arc5 the approximately 13 plastids per cell are still centrally constricted but much enlarged. As the arc5 chloroplasts expand and elongate without dividing, the internal thylakoid membrane structure becomes flexed into an undulating ribbon. We conclude that the ARC5 gene is necessary for the completion of the last stage of chloroplast division when the narrow isthmus breaks, causing the separation of the daughter plastids.
Sequences Necessary for Nitrate-Dependent Transcription of Arabidopsis Nitrate Reductase Genes
Authors: Hwang C. F. , Lin Y. , D'Souza T. , Cheng C. L.
Published: July 2002

Nitrate increases the transcription of the two Arabidopsis thaliana nitrate reductase genes. We demonstrated previously that 238 and 330 bp of the 5[prime] flanking regions, designated as NP1 and NP2, of the two nitrate reductase genes NR1 and NR2, respectively, are sufficient for nitrate-dependent transcription (Y. Lin, C.-F. Hwang, J.B. Brown, C.-L. Cheng [1994] Plant Physiol 106: 477–484). Here we identify the cis-acting elements of NP1 and NP2 that are necessary for nitrate-dependent transcription by linker-scanning (LS) analysis. In transgenic plants one LS mutant of NP1 and two LS mutants of NP2 exhibited significantly lower nitrate-induced reporter gene chloramphenicol acetyltransferase activity. To distinguish which of these three mutants lost nitrate inducibility, competitive reverse-transcriptase polymerase chain reaction was used to measure the chloramphenicol acetyltransferase mRNA levels before and after nitrate induction. The single LS mutant in NP1 lost its response to nitrate, whereas the two LS mutants in NP2 partially lost their response to nitrate. A 12-bp sequence is conserved between the NP1 site and the two NP2 sites. This sequence motif is also conserved in the 5[prime] flanking regions of other nitrate-inducible plant genes. Gel mobility shift experiments indicate that these three regions bind to similar proteins. The binding is constitutive with respect to nitrate treatment and was observed in both nonphotosynthetic suspension cells and green leaves.
Purification and in Vitro Chaperone Activity of a Class I Small Heat-Shock Protein Abundant in Recalcitrant Chestnut Seeds
Authors: Collada C. , Gomez L. , Casado R. , Aragoncillo C.
Published: July 2002

A 20-kD protein has been purified from cotyledons of recalcitrant (desiccation-sensitive) chestnut (Castanea sativa) seeds, where it accumulates at levels comparable to those of major seed storage proteins. This protein, termed Cs smHSP 1, forms homododecameric complexes under nondenaturing conditions and appears to be homologous to cytosolic class I small heat-shock proteins (smHSPs) from plant sources. In vitro evidence has been obtained that the isolated protein can function as a molecular chaperone: it increases, at stoichiometric levels, the renaturation yields of chemically denatured citrate synthase and also prevents the irreversible thermal inactivation of this enzyme. Although a role in desiccation tolerance has been hypothesized for seed smHSPs, this does not seem to be the case for Cs smHSP 1. We have investigated the presence of immunologically related proteins in orthodox and recalcitrant seeds of 13 woody species. Our results indicate that the presence of Cs smHSP 1-like proteins, even at high levels, is not enough to confer desiccation tolerance, and that the amount of these proteins does not furnish a reliable criterion to identify desiccation-sensitive seeds. Additional proteins or mechanisms appear necessary to keep the viability of orthodox seeds upon shedding.
Biochemical Characterization of Stromal and Thylakoid-Bound Isoforms of Isoprene Synthase in Willow Leaves1
Authors: Wildermuth Mary C. , Fall Ray
Published: July 2002

Isoprene synthase is the enzyme responsible for the foliar emission of the hydrocarbon isoprene (2-methyl-1,3-butadiene) from many C3 plants. Previously, thylakoid-bound and soluble forms of isoprene synthase had been isolated separately, each from different plant species using different procedures. Here we describe the isolation of thylakoid-bound and soluble isoprene synthases from a single willow (Salix discolor L.) leaf-fractionation protocol. Willow leaf isoprene synthase appears to be plastidic, with whole-leaf and intact chloroplast fractionations yielding approximately equal soluble (i.e. stromal) and thylakoid-bound isoprene synthase activities. Although thylakoid-bound isoprene synthase is tightly bound to the thylakoid membrane (M.C. Wildermuth, R. Fall [1996] Plant Physiol 112: 171–182), it can be solubilized by pH 10.0 treatment. The solubilized thylakoid-bound and stromal isoprene synthases exhibit similar catalytic properties, and contain essential cysteine, histidine, and arginine residues, as do other isoprenoid synthases. In addition, two regulators of foliar isoprene emission, leaf age and light, do not alter the percentage of isoprene synthase activity in the bound or soluble form. The relationship between the isoprene synthase isoforms and the implications for function and regulation of isoprene production are discussed.
Activation of the Maize Anthocyanin Gene a2 Is Mediated by an Element Conserved in Many Anthocyanin Promoters1
Authors: Lesnick Marc Louis , Chandler Vicki Lynn
Published: July 2002

Two transcription factors, C1 (a Myb-domain protein) and B (a basic-helix-loop-helix protein), mediate transcriptional activation of the anthocyanin-biosynthetic genes of maize (Zea mays). To begin to assess the mechanism of activation, the sequences required for C1- and B-mediated induction have been determined for thea2 promoter, which encodes an anthocyanin-biosynthetic enzyme. Analysis of a series of 7- to 13-base-pair substitutions revealed two regions crucial for activation. One region, centered at −99, contained a C1-binding site that abolished C1 binding. The other crucial region was adjacent, centered at −91. C1 binding was not detected at this site, and mutation of this site did not prevent C1 binding at −99. An oligonucleotide dimer containing these two crucial elements was sufficient for C1 and B activation of a heterologous promoter. These data suggest that activation of the anthocyanin genes involves C1 and another factor binding at closely adjacent sites. Mutating a previously postulated anthocyanin consensus sequence withina2 did not significantly reduce activation by C1 and B. However, sequence comparisons of the crucial a2 regions with sequences important for C1- and B-mediated activation in two other anthocyanin promoters led to a revised consensus element shared by these promoters.
A Fruit-Specific Putative Dihydroflavonol 4-Reductase Gene Is Differentially Expressed in Strawberry during the Ripening Process1
Authors: Moyano Enriqueta , Portero-Robles Ignacio , Medina-Escobar Nieves , Valpuesta Victoriano , Muñoz-Blanco Juan , Luis Caballero José
Published: July 2002

A cDNA clone encoding a putative dihydroflavonol 4-reductase gene has been isolated from a strawberry (Fragaria × ananassa cv Chandler) DNA subtractive library. Northern analysis showed that the corresponding gene is predominantly expressed in fruit, where it is first detected during elongation (green stages) and then declines and sharply increases when the initial fruit ripening events occur, at the time of initiation of anthocyanin accumulation. The transcript can be induced in unripe green fruit by removing the achenes, and this induction can be partially inhibited by treatment of de-achened fruit with naphthylacetic acid, indicating that the expression of this gene is under hormonal control. We propose that the putative dihydroflavonol 4-reductase gene in strawberry plays a main role in the biosynthesis of anthocyanin during color development at the late stages of fruit ripening; during the first stages the expression of this gene could be related to the accumulation of condensed tannins.
Evolution of C4 Photosynthesis inFlaveria Species1
Authors: Drincovich Maria F. , Casati Paula , Andreo Carlos S. , Chessin Saul J. , Franceschi Vincent R. , Edwards Gerald E. , Ku Maurice S.B.
Published: July 2002

NADP-malic enzyme (NADP-ME, EC 1.1.1.40), a key enzyme in C4 photosynthesis, provides CO2 to the bundle-sheath chloroplasts, where it is fixed by ribulose-1,5-bisphosphate carboxylase/oxygenase. We characterized the isoform pattern of NADP-ME in different photosynthetic species ofFlaveria (C3, C3-C4intermediate, C4-like, C4) based on sucrose density gradient centrifugation and isoelectric focusing of the native protein, western-blot analysis of the denatured protein, and in situ immunolocalization with antibody against the 62-kD C4 isoform of maize. A 72-kD isoform, present to varying degrees in all species examined, is predominant in leaves of C3Flaveria spp. and is also present in stem and root tissue. By immunolabeling, NADP-ME was found to be mostly localized in the upper palisade mesophyll chloroplasts of C3 photosynthetic tissue. Two other isoforms of the enzyme, with molecular masses of 62 and 64 kD, occur in leaves of certain intermediates having C4 cycle activity. The 62-kD isoform, which is the predominant highly active form in the C4species, is localized in bundle-sheath chloroplasts. AmongFlaveria spp. there is a 72-kD constitutive form, a 64-kD form that may have appeared during evolution of C4metabolism, and a 62-kD form that is necessary for the complete functioning of C4 photosynthesis.
Cloning of Nicotianamine Synthase Genes, Novel Genes Involved in the Biosynthesis of Phytosiderophores
Authors: Higuchi Kyoko , Suzuki Kazuya , Nakanishi Hiromi , Yamaguchi Hirotaka , Nishizawa Naoko-Kishi , Mori Satoshi
Published: July 2002

Nicotianamine synthase (NAS), the key enzyme in the biosynthetic pathway for the mugineic acid family of phytosiderophores, catalyzes the trimerization ofS-adenosylmethionine to form one molecule of nicotianamine. We purified NAS protein and isolated the genesnas1, nas2, nas3,nas4, nas5-1, nas5-2, andnas6, which encode NAS and NAS-like proteins from Fe-deficient barley (Hordeum vulgare L. cv Ehimehadaka no. 1) roots. Escherichia coli expressingnas1 showed NAS activity, confirming that this gene encodes a functional NAS. Expression of nas genes as determined by northern-blot analysis was induced by Fe deficiency and was root specific. The NAS genes form a multigene family in the barley and rice genomes.
Molecular Cloning and Expression Analysis of the Mitochondrial Pyruvate Dehydrogenase from Maize1
Authors: Thelen Jay J. , Miernyk Jan A. , Randall Douglas D.
Published: July 2002

Four cDNAs, one encoding an α-subunit and three encoding β-subunits of the mitochondrial pyruvate dehydrogenase, were isolated from maize (Zea mays L.) libraries. The deduced amino acid sequences of both α- and β-subunits are approximately 80% identical with Arabidopsis and pea (Pisum sativum L.) homologs. The mature N terminus was determined for the β-subunit by microsequencing the protein purified from etiolated maize shoot mitochondria and was resolved by two-dimensional gel electrophoresis. This single isoelectric species comprised multiple isoforms. Both α- and β-subunits are encoded by multigene families in maize, as determined by Southern-blot analyses. RNA transcripts for both α- and β-subunits were more abundant in roots than in young leaves or etiolated shoots. Pyruvate dehydrogenase activity was also higher in roots (5-fold) compared with etiolated shoots and leaves. Both subunits were present at similar levels in all tissues examined, indicating coordinated gene regulation. The protein levels were highest in heterotrophic organs and in pollen, which contained about 2-fold more protein than any other organ examined. The relative abundance of these proteins in nonphotosynthetic tissues may reflect a high cellular content of mitochondria, a high level of respiratory activity, or an extra plastidial requirement for acetate.
Genetic and Biochemical Evidence for the Involvement of α-1,4 Glucanotransferases in Amylopectin Synthesis1
Authors: Colleoni Christophe , Dauvillée David , Mouille Gregory , Buléon Alain , Gallant Daniel , Bouchet Brigitte , Morell Matthew , Samuel Michael , Delrue Brigitte , d'Hulst Christophe , Bliard Christophe , Nuzillard Jean-Marc , Ball Steven
Published: July 2002

We describe a novel mutation in theChlamydomonas reinhardtii STA11 gene, which results in significantly reduced granular starch deposition and major modifications in amylopectin structure and granule shape. This defect simultaneously leads to the accumulation of linear malto-oligosaccharides. The sta11-1mutation causes the absence of an α-1,4 glucanotransferase known as disproportionating enzyme (D-enzyme). D-enzyme activity was found to be correlated with the amount of wild-type allele doses in gene dosage experiments. All other enzymes involved in starch biosynthesis, including ADP-glucose pyrophosphorylase, debranching enzymes, soluble and granule-bound starch synthases, branching enzymes, phosphorylases, α-glucosidases (maltases), and amylases, were unaffected by the mutation. These data indicate that the D-enzyme is required for normal starch granule biogenesis in the monocellular alga C. reinhardtii.
Identification ofcis-Acting Elements Important for Expression of the Starch-Branching Enzyme I Gene in Maize Endosperm
Authors: Kim Kyung-Nam , Guiltinan Mark J.
Published: July 2002

The genes encoding the starch-branching enzymes (SBE) SBEI, SBEIIa, and SBEIIb in maize (Zea mays) are differentially regulated in tissue specificity and during kernel development. To gain insight into the regulatory mechanisms controlling their expression, we analyzed the 5′-flanking sequences of Sbe1 using a transient gene expression system. Although the 2.2-kb 5′-flanking sequence between −2,190 and +27 relative to the transcription initiation site was sufficient to promote transcription, the addition of the transcribed region between +28 and +228 containing the first exon and intron resulted in high-level expression in suspension-cultured maize endosperm cells. A series of 5′ deletion and linker-substitution mutants identified two critical positivecis elements, −314 to −295 and −284 to −255. An electrophoretic mobility-shift assay showed that nuclear proteins prepared from maize kernels interact with the 60-bp fragment containing these two elements. Expression of the Sbe1 gene is regulated by sugar concentration in suspension-cultured maize endosperm cells, and the region −314 to −145 is essential for this effect. Interestingly, the expression of mEmBP-1, a bZIP transcription activator, in suspension-cultured maize endosperm cells resulted in a 5-fold decrease in Sbe1 promoter activity, suggesting a possible regulatory role of the G-box present in theSbe1 promoter from −227 to −220.
Expression of a Polygalacturonase Associated with Tomato Seed Germination
Authors: Sitrit Yaron , Hadfield Kristen A. , Bennett Alan B. , Bradford Kent J. , Downie A. Bruce
Published: July 2002

Radicle protrusion from tomato (Lycopersicon esculentum Mill.) seeds to complete germination requires weakening of the endosperm tissue opposite the radicle tip. In common with other cell wall disassembly processes in plants, polygalacturonases (PGs) may be involved. Only calcium-dependent exo-PG activity was detected in tomato seed protein extracts. Chromatographic profiles of a partially acid-hydrolyzed fraction of polygalacturonic acid further digested with seed extract were consistent with the presence of only calcium-dependent exo-PG activity. In addition, a transcript encoding a previously unknown PG was detected prior to the completion of germination. The mRNA, produced from a gene (LeXPG1) estimated by Southern analysis to be represented once in the genome, was also present in flowers (anthers) and in lower amounts in roots and stems. LeXPG1 mRNA abundance was low during seed development, increased during imbibition, and was even greater in seeds that had completed germination. Expression of LeXPG1 during germination predominates in the endosperm cap and radicle tip, and in the radicle appears as a distinct band possibly associated with vascular tissue differentiation. We suggest that PG is involved in cell wall loosening of the endosperm necessary for radicle protrusion from tomato seeds and in subsequent embryo and seedling growth.