bluuebunny/crossref_metadata_2025 huggingface dataset:
Menstrual effects on asymmetrical olfactory acuity
Authors: PURDON SCOT E. , KLEIN SUZANNE , FLOR-HENRY PIERRE
Published: July 2002

Gender specific discrepancies on psychometric examination are
often interpreted to reflect static differences in cerebral
hemisphere specialization, but dynamic alterations relating
to circulating gonadal hormones may also be relevant after puberty.
The often cited inference of a right hemisphere advantage in
males and left hemisphere advantage in females derived from
small but reliable differences on spatial tasks and verbal tasks,
for example, may to some extent relate to gender-specific
differences in circulating gonadal hormones. Performance
fluctuations on other higher order cognitive tasks through the
menstrual cycle tend to support a temporal association between
alterations in cerebral laterality and hormone fluctuations.
A potential left hemisphere advantage after menstruation when
estrogen and progesterone levels are high in contrast to a right
hemisphere advantage at menstruation when estrogen and progesterone
levels are low has also received support from shifts in visual
field perception. The present investigation continues this line
of work by measurement of prospective changes in unirhinal
olfactory acuity in the menstrual, ovulatory, and midluteal
phases of the menstrual cycle in 11 healthy women who agreed
to blood assays of estradiol and progesterone prior to completing
a modified version of the Connecticut Chemosensory Perception
Exam (CCPE). The CCPE detection of n-butanol showed a clear
pattern of changes over the menstrual cycle marked by an asymmetry
favoring the right nostril during menstruation when estradiol
and progesterone levels were low, an asymmetry favoring the
left nostril during ovulation when estradiol levels were high
and progresterone levels were low, and an absence of asymmetry
during the midluteal phase when estradiol levels decreased and
progesterone levels increased. Preliminary correlation analyses
revealed a potential competitive influence of estradiol and
progesterone on this apparent shift in cerebral laterality.
There is thus sufficient evidence to conclude that dynamic changes
in relative cerebral hemisphere advantages have a temporal relation
to fluctuations in circulating gonadal hormones and to suggest
the value of additional investigation of more specific causal
relations. (JINS, 2001, 7, 703–709.)
Schizophrenia and the frontal brain: A quantitative review
Authors: ZAKZANIS KONSTANTINE K. , HEINRICHS R. WALTER
Published: July 2002

Structural and physiological frontal brain system
deficits in patients with schizophrenia are reviewed quantitatively.
We report effect sizes from studies since 1980 that used
structural (CT, MRI), and functional (PET) neuroimaging
methods. We found both literatures to be distinguished
by heterogeneity whereby most patients show normative frontal
function and structure, a minority shows diminished values
and some patients demonstrate augmented function and structure
rather than deficit. The average magnitude of difference
between patients and controls is generally too modest to
support the idea that frontal brain dysfunction is a necessary
component of schizophrenia. This modesty is most apparent
in average effects obtained for frontal brain volume (M
= −.36), left frontal brain volume (M =
−.16), frontal resting metabolism, and blood flow
(M = −.64). Effect sizes of this magnitude
imply that schizophrenia and control distributions overlap
by as much as 88% and no less than about 60% on frontal
brain measures. It is only when behavioral measures are
employed as activation tasks during frontal blood flow
and metabolism studies, that average effect sizes rise
in magnitude to indicate patient–control distribution
overlaps that are less than 50%. Overall, the findings
are hard to incorporate within single disease models that
propose major involvement of the frontal system, at least
at the degree of resolution obtained with current imaging
technology. (JINS, 1999, 5, 556–566.)
The influence of mineral exports on the variability of tropical deforestation
Authors: SUNDERLIN WILLIAM D. , WUNDER SVEN
Published: July 2002

Previous studies of deforestation have focused on agriculture, population and migration, timber exploitation, macroeconomic policies and geographic factors to explain the variability of deforestation rates among countries. This study tests the hypothesis that countries with a high proportion of petroleum or non-petroleum mineral exports in total exports experience a relatively low deforestation rate because of macroeconomic ‘Dutch disease’ effects. Bivariate and multivariate analyses provide preliminary support for the hypothesis, although they give little insight on how precisely mineral exports might exert their influence on forest cover. One reason for the limited utility of these methodologies is that they do not adequately explain the various effects of mineral windfalls that go beyond the Dutch disease's ‘core model’. Future research must attempt to understand these effects, which include: levels of funding for agriculture, roads, and directed settlement; agricultural protectionism; levels of rural poverty, urbanization, and consumer demand; the site-level effects of mineral extraction; and the variability of state autonomy.
Transgenic crops and the environment: missing markets and public roles
Authors: Batie Sandra S. , Ervin David E.
Published: July 2002

The rapidity of change has left scant opportunity for investigation of the consequences of adoption of transgenic crops on long-term ecosystem or economic system functioning. Economic theory suggests that, if the “Biotechnology Revolution” is left to market forces alone, there will be neglected public goods. Theory and limited empirical evidence suggests that there are significant incentives for private firms to discount and neglect certain environmental impacts and to develop products that meet mainly the needs of those able and willing to pay. Negative distributional impacts on rural societies and economies will not normally enter the private calculus nor will the long-term problems of insect and plant resistance. Thus, there is a strong case for enhanced public roles with respect to the use of transgenic crops. The adoption of the precautionary approach in public policies addressing transgenic crops is one alternative to better reflect public concerns.
Defining Dyslexia
Authors: Coltheart Max , Jackson Nancy Ewald
Published: July 2002

We argue against defining dyslexia as requiring by definition the
presence
of demonstrable phonological difficulty, and also against defining it in

relation to exclusion criteria. Instead, we suggest that what matters is

evaluating any child's set of reading subskills against age-related
norms
for those subskills. We also argue that in considering the causes of reading

difficulty it is essential to distinguish between proximal cause (some

abnormality in the information-processing system that the child is using
to
read) and distal cause (the reason for this system being abnormal).
The same proximal cause (e.g. poor phonic knowledge) can be the
product of different distal causes in different children (e.g. the distal
cause
might be constitutional, environmental, or educational).
MINIMUM CONSUMPTION REQUIREMENTS: THEORETICAL AND QUANTITATIVE
IMPLICATIONS FOR GROWTH AND DISTRIBUTION
Authors: Chatterjee Satyajit , Ravikumar B.
Published: July 2002

We study the impact of a minimum consumption requirement on the rate of
economic growth and the evolution of wealth distribution. The requirement
introduces a positive dependence between the intertemporal elasticity of
substitution and household wealth. This dependence implies a transition
phase during which the growth rate of per-capita quantities rise toward
their steady-state values and the distributions of wealth, consumption, and
permanent income become more unequal. We calibrate the minimum consumption
requirement to match estimates available for a sample of Indian villagers
and find that these transitional effects are quantitatively significant and
depend importantly on the economy's steady-state growth rate.
Functional imaging in the study of recovery patterns in bilingual aphasia
Authors: Green David W. , Price Cathy J.
Published: July 2002

There is no causal account of recovery patterns in bilingual aphasia. We propose that the causal mechanisms can be partially revealed by combining neuropsychological and neuroimaging methods. We briefly review the potentials and limitations associated with functional neuroimaging experiments on normal and neurologically impaired patients and then focus on the different levels of description required to reveal the causal basis of recovery patterns in bilingual aphasics. Finally, we suggest how functional imaging investigations might be meaningfully undertaken with bilingual aphasic patients. We illustrate our argument with respect to five different patterns of recovery and consider the theoretical and practical implications of such research.
Effect of anthropogenic low‐frequency noise on the foraging ecology of Balaenoptera whales
Authors: Croll Donald A. , Clark Christopher W. , Calambokidis John , Ellison William T. , Tershy Bernie R.
Published: July 2002

The human contribution to ambient noise in the ocean has increased over the past 50 years, and is dominated by low‐frequency (LF) sound (frequencies <1000 Hz) from shipping, oil and gas development, defence‐related and research activities. Mysticete whales, including six endangered species, may be at risk from this noise pollution because all species produce and probably perceive low‐frequency sound. We conducted a manipulative field experiment to test the effects of loud, LF noise on foraging fin blue (B. musculus) and (Balaenoptera physalus) whales off San Nicolas Island, California. Naive observers used a combination of attached tracking devices, ship‐based surveys, aerial surveys, photo‐identification and passive monitoring of vocal behaviour to examine the behaviour and distribution of whales when a loud LF source (US Navy SURTASS LFA) was and was not transmitting. During transmission, 12‐30% of the estimated received levels of LFA of whales in the study area exceeded 140 dB re 1 μPa. However, whales continued to be seen foraging in the region. Overall, whale encounter rates and diving behaviour appeared to be more strongly linked to changes in prey abundance associated with ceanographic parameters than to LF sound transmissions. In some cases, whale vocal behaviour was significantly different between experimental and non‐experimental periods. However, these differences were not consistent and did not appear to be related to LF sound transmissions. At the spatial and temporal scales examined, we found no obvious responses of whales to a loud, anthropogenic, LF sound. We suggest that the cumulative effects of anthropogenic LF noise over larger temporal and spatial scales than examined here may be a more important consideration for management agencies.
Aggregation and habitat use by Lucilia blowflies (Diptera: Calliphoridae) in pasture
Authors: Cruickshank I. , Wall R.
Published: July 2002

The spatial distribution of blowflies of the genus Lucilia within fields in south west England was examined in 1999 and 2000. Blowflies are economically important agents of sheep myiasis in the UK and understanding local aggregation is an essential step in the development of appropriate sampling and fly control regimes. Fifty, 20 × 20 cm, non-odour-baited, sticky traps were used to catch flies, at randomized, 10 × 10 m grid co-ordinates in fields of permanent pasture. Clear aggregations were evident in all Lucilia distributions. All values of the σ2:mean ratio were greater than 1. The catches were shown to be highly aggregated using Morisita’s index of aggregation. Generalized linear modelling of binary presence/absence catch data was used to relate aggregation to microclimate and habitat. Deletion testing was used to identify significant terms in the models. In general, Lucilia blowflies were predominantly caught around the edges, in warmer and more humid areas of the field. The relationship between microhabitat and the distribution of Lucilia collected in 1999 was used as predictive model to explain the catches made in two fields in 2000. This gave a highly significant fit in one field (P = 0.001) and a relationship which approached significance in the second (P = 0.08). However, these regressions suggest that the relationships between abundance and microhabitat are complex and that ‘hot spots’ of blowfly catches were not necessarily found in the most extreme microclimate conditions. Nevertheless, microhabitat features do give a relatively good guide to presence or absence of Lucilia in the trap catches, thereby providing important information about the most appropriate location of traps to maximize and standardize sampling and control regimes.
Methods for rearing Syngaster lepidus and Jarra phoracantha (Hymenoptera: Braconidae), larval parasitoids of the phloem-colonizing longhorned beetles Phoracantha semipunctata and P. recurva (Coleoptera: Cerambycidae)
Authors: Millar J.G. , Paine T.D. , Campbell C.D. , Hanks L.M.
Published: July 2002

Two species of cerambycid beetles that attack eucalypts, Phoracantha semipunctata(Fabricius) and P. recurva Newman, have been accidentally introduced from Australia into most regions of the world in which their hosts have been planted. The beetles cause extensive mortality in plantations and landscape plantings of the trees. Management programmes have focused on integration of silvicultural practices, host plant resistance and biological control. To rear and release natural enemies of the larval stages of the beetles in California, mass rearing protocols for continuous production of two species of parasitoids have been developed. The methods described represent the first long-term and large-scale techniques for mass rearing parasitoids of any wood-boring cerambycid species. In addition to providing large numbers of parasitoids for releases, the mass rearing effort has also provided large numbers of parasitoids for fundamental studies of their biology and behaviour.
Outbreaks of forest defoliating insects in Japan, 1950–2000
Authors: Kamata N.
Published: July 2002

In Japan, several forest-defoliating insects reach outbreak levels and cause serious defoliation. Stand mortality sometimes occurs after severe defoliation. However, in general, tree mortality caused by insect defoliation is low because of the prevailing moist climate in Japan. Evergreen conifers are more susceptible to tree mortality as a result of insect defoliation whereas deciduous broad-leaved trees are seldom killed. Insect defoliation occurs more frequently in man-made environments such as among shade trees, orchards, and plantations than in natural habitats. Outbreaks of some defoliators tend to occur in stands of a particular age: e.g. outbreaks of the pine caterpillar, Dendrolimus spectabilis Butler (Lepidoptera: Lasiocampidae) occur more frequently in young pine plantations. In contrast, defoliation caused by outbreaks of lepidopterous and hymenopterous pests in larch plantations is more frequent with stand maturation. There is a relationship between outbreaks of some defoliators and altitude above sea level. Most outbreaks of forest defoliators were terminated by insect pathogens that operated in a density-dependent fashion. Since the 1970s, Japan has been prosperous and can afford to buy timber from abroad. More recently, there has been an increasing demand for timber in Japan, that coincides with a huge demand internationally, so that the country will need to produce more timber locally in the future. The increasing pressure on the forestry industry to meet this demand will require more sophisticated methods of pest control coupled with more sustainable methods of silviculture.
How Malleable is the Eukaryotic Genome? Extreme Rate of Chromosomal Rearrangement in the GenusDrosophila
Authors: Ranz José Marı́a , Casals Ferran , Ruiz Alfredo
Published: July 2002

During the evolution of the genusDrosophila, the molecular organization of the major chromosomal elements has been repeatedly rearranged via the fixation of paracentric inversions. Little detailed information is available, however, on the extent and effect of these changes at the molecular level. In principle, a full description of the rate and pattern of change could reveal the limits, if any, to which the eukaryotic genome can accommodate reorganizations. We have constructed a high-density physical map of the largest chromosomal element inDrosophila repleta(chromosome 2) and compared the order and distances between the markers with those on the homologous chromosomal element (3R) inDrosophila melanogaster. The two species belong to different subgenera (DrosophilaandSophophora, respectively), which diverged 40–62 million years (Myr) ago and represent, thus, the farthest lineages within theDrosophilagenus. The comparison reveals extensive reshuffling of gene order from centromere to telomere. Using a maximum likelihood method, we estimate that 114 ± 14 paracentric inversions have been fixed in this chromosomal element since the divergence of the two species, that is, 0.9–1.4 inversions fixed per Myr. Comparison with available rates of chromosomal evolution, taking into account genome size, indicates that theDrosophilagenome shows the highest rate found so far in any eukaryote. Twenty-one small segments (23–599 kb) comprising at least two independent (nonoverlapping) markers appear to be conserved betweenD. melanogasterandD. repleta. These results are consistent with the random breakage model and do not provide significant evidence of functional constraint of any kind. They support the notion that theDrosophilagenome is extraordinarily malleable and has a modular organization. The high rate of chromosomal change also suggests a very limited transferability of the positional information from theDrosophilagenome to other insects.

[The sequence data described in this paper have been submitted to the GenBank data library under accession no,AF319441.]
A Marker-Dense Physical Map of the Bradyrhizobium japonicum Genome
Authors: Tomkins Jeffrey P. , Wood Todd C. , Stacey Minviluz G. , Loh John T. , Judd Adam , Goicoechea Jose L. , Stacey Gary , Sadowsky Michael J. , Wing Rod A.
Published: July 2002

Bacterial artificial chromosome (BAC) clones are effective mapping and sequencing reagents for use with a wide variety of small and large genomes. This report describes the development of a physical framework for the genome of Bradyrhizobium japonicum, the nitrogen-fixing symbiont of soybean. A BAC library for B. japonicum was constructed that provides a 77-fold genome coverage based on an estimated genome size of 8.7 Mb. The library contains 4608 clones with an average insert size of 146 kb. To generate a physical map, the entire library was fingerprinted with HindIII, and the fingerprinted clones were assembled into contigs using theFingerprint Contig software (FPC; Sanger Centre, UK). The FPC analysis placed 3410 clones in six large contigs. The ends of 1152 BAC inserts were sequenced to generate a sequence-tagged connector (STC) framework. To join and orient the contigs, high-density BAC colony filters were probed with 41 known gene probes and 17 end sequences from contig boundaries. STC sequences were searched against the public databases using FASTA andBLASTX algorithms. Query results allowed the identification of 113 high probability matches with putative functional identities that were placed on the physical map. Combined with the hybridization data, a high-resolution physical map with 194 positioned markers represented in two large contigs was developed, providing a marker every 45 kb. Of these markers, 177 are known or putative B. japonicum genes. Additionally, 1338 significant BLASTXresults (E < 10−4) were manually sorted by function to produce a functionally categorized database of relevantB. japonicum STC sequences that can also be traced to specific locations in the physical map.
Parallel Working Memory for Spatial Location and Food-Related Object Cues in Foraging Pigeons: Binocular and Lateralized Monocular Performance
Authors: Prior Helmut , Güntürkün Onur
Published: July 2002

During foraging, animals can increase their success by both remembering feeding sites and remembering food-related object cues. Because earlier studies have tested either the site or object memory in isolation, the aim of the present study was to evaluate how efficiently birds can utilize both memories simultaneously. Furthermore, the idea was tested that lateralization might be the principle of brain organization that allows for efficient parallel processing. Pigeons learned to search for food in a complex maze with 16 baited sites. To obtain the maximum reward they had to perform two tasks in parallel, a spatial working memory task and an object-specific working memory task. Birds performed well on this dual task but, compared with spatial working memory alone, they were impaired during the first choices of a trial (Experiment 1). When the left and the right brain hemispheres were tested separately by means of monocular occlusion (Experiment 2), object discrimination was better when birds used their right eye/left hemisphere. This was most pronounced during the first choices of a trial. On the spatial component of the task, performance on binocular trials was better than on monocular trials, but monocularly both hemispheres performed at the same level. Results show that on this dual task, discrimination of food-related object cues predominantly involved the left brain hemisphere whereas both hemispheres contributed equally to spatial performance.
Uncoupled Defense Gene Expression and Antimicrobial Alkaloid Accumulation in Elicited Opium Poppy Cell Cultures
Authors: Facchini P. J. , Johnson A. G. , Poupart J. , De Luca V.
Published: July 2002

Treatment of opium poppy (Papaver somniferum L.) cell cultures with autoclaved mycelial homogenates of Botrytis sp. resulted in the accumulation of sanguinarine. Elicitor treatment also caused a rapid and transient induction in the activity of tyrosine/dopa decarboxylase (TYDC, EC 4.1.1.25), which catalyzes the conversion of L-tyrosine and L-dopa to tyramine and dopamine, respectively, the first steps in sanguinarine biosynthesis. TYDC genes were differentially expressed in response to elicitor treatment. TYDC1-like mRNA levels were induced rapidly but declined to near baseline levels within 5 h. In contrast, TYDC2-like transcript levels increased more slowly but were sustained for an extended period. Induction of TYDC mRNAs preceded that of phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) mRNAs. An elicitor preparation from Pythium aphanidermatum was less effective in the induction of TYDC mRNA levels and alkaloid accumulation; however, both elicitors equally induced accumulation of PAL transcripts. In contrast, treatment with methyl jasmonate resulted in an induction of TYDC but not PAL mRNAs. The calmodulin antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide and the protein kinase inhibitor staurosporine partially blocked the fungal elicitor-induced accumulation of sanguinarine. However, only staurosporine and okadaic acid, an inhibitor of protein phosphatases 1 and 2A, blocked the induction of TYDC1-like transcript levels, but they did not block the induction of TYDC2-like or PAL tanscript levels. These data suggest that activation mechanisms for PAL, TYDC, and some later sanguinarine biosynthetic enzymes are uncoupled.
Cold-Shock Regulation of the Arabidopsis TCH Genes and the Effects of Modulating Intracellular Calcium Levels
Authors: Polisensky D. H. , Braam J.
Published: July 2002

The Arabidopsis TCH genes, which encode calmodulin-related proteins and a xyloglucan endotransglycosylase, are shown to be up-regulated in expression following cold shock. We investigated a possible role of fluctuations in intracellular calcium ion concentra- tions ([Ca2+]) in the cold-shock-induced TCH gene expression. Transgenic plants harboring the apoaequorin gene were generated to monitor [Ca2+] and to test the necessity of cold-induced [Ca2+] increases for TCH expression. Cold-shock-induced [Ca2+] increases can be blocked by La3+ and Gd3+, putative plasma membrane Ca2+ channel blockers, and 1,2-bis(o-aminophenoxy)ethane-N,N,N[prime],N[prime]- tetraacetic acid, an extracellular Ca2+ chelator. Cold-shock-induced expression of the TCH genes is inhibited by levels of La3+, Gd3+, and 1,2-bis(o-aminophenoxy)ethane-N,N,N[prime],N[prime]-tetraacetic acid, that have been shown to block [Ca2+] increases. These data support the hypotheses that (a) intracellular [Ca2+] increases following cold shock require extracellular Ca2+ and may derive from a Ca2+ influx mediated by plasmalemma Ca2+ channels, and (b) cold up-regulation of expression of at least a subset of the TCH genes requires an intracellular [Ca2+] increase. The inhibitors are also shown to have stimulus-independent effects on gene expression, providing strong evidence that these commonly used chemicals have more complex effects than generally reported.
Expression and RNA Splicing of the Maize Glutathione S-Transferase Bronze2 Gene Is Regulated by Cadmium and Other Stresses
Authors: Marrs K. A. , Walbot V.
Published: July 2002

The Bronze2 (Bz2) gene in maize (Zea mays) encodes a glutathione S-transferase that performs the last genetically defined step in anthocyanin biosynthesis[mdash]tagging anthocyanin precursors with glutathione, allowing for recognition and entry of anthocyanins into the vacuole. Here we show that Bz2 gene expression is highly induced by heavy metals such as cadmium. Treatment of maize seedlings with cadmium results in a 20-fold increase in Bz2 message accumulation and a 50-fold increase in the presence of the unspliced, intron-containing transcript. The increase in message levels during cadmium stress appears to result, at least in part, from activation of an alternative mRNA start site approximately 200 nucleotides upstream of the normal start site; this site is not used in unstressed or heat-stressed tissues. The effect of cadmium on the RNA splicing of Bz2 seems to be specific: splicing of other intron-containing maize genes, including a maize actin gene under the control of the cadmium-inducible Bz2 promoter, is unaffected by cadmium stress. Conversely, Bz2 intron splicing is not affected by other stress conditions that induce Bz2 gene expression, such as abscisic acid, auxin, or cold stress. Surprisingly, the increase in Bz2 mRNA during cadmium stress does not result in an increase in Bz2 glutathione S-transferase activity. We propose that an alternative protein may be encoded by Bz2 that has a role during responses to heavy metals.
Complementary DNAs Encoding Eukaryotic-Type Cytidine-5[prime]-Diphosphate-Diacylglycerol Synthases of Two Plant Species
Authors: Kopka J. , Ludewig M. , Muller-Rober B.
Published: July 2002

Cytidine diphosphate (CDP)-diacylglycerol synthase (cytidine triphosphate:phosphatidate cytidyltransferase, EC 2.7.7.41) catalyzes the formation of CDP-diacylglycerol, which is the precursor of phosphatidylinositol, phosphatidylglycerol, and cardiolipin. We report the first cloning, to our knowledge, of two plant cDNAs, StCDS1 and AtCDS1, coding for CDP-diacylglycerol synthases from potato (Solanum tuberosum) and Arabidopsis thaliana, respectively. The two proteins belong to the eukaryotic type of CDP-diacylglycerol synthases and contain eight predicted transmembrane-spanning domains. We analyzed gene expression in shoot and root tissues of potato plants and demonstrated enzyme activity by expression of N-terminally truncated, recombinant StCDS1 in Escherichia coli.
Xyloglucan Galactosyl- and Fucosyltransferase Activities from Pea Epicotyl Microsomes
Authors: Faik A. , Chileshe C. , Sterling J. , Maclachlan G.
Published: July 2002

Microsomal membranes from growing tissue of pea (Pisum sativum L.) epicotyls were incubated with the substrate UDP-[14C]galactose (Gal) with or without tamarind seed xyloglucan (XG) as a potential galactosyl acceptor. Added tamarind seed XG enhanced incorporation of [14C]Gal into high-molecular-weight products (eluted from columns of Sepharose CL-6B in the void volume) that were trichloroacetic acid-soluble but insoluble in 67% ethanol. These products were hydrolyzed by cellulase to fragments comparable in size to XG subunit oligosaccharides. XG-dependent galactosyltransferase activity could be solubilized, along with XG fucosyltransferase, by the detergent 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate. When this enzyme was incubated with tamarind (Tamarindus indica L.) seed XG or nasturtium (Tropaeolum majus L.) seed XG that had been partially degalactosylated with an XG-specific β-galactosidase, the rates of Gal transfer increased and fucose transfer decreased compared with controls with native XG. The reaction products were hydrolyzed by cellulase to 14C fragments that were analyzed by gel-filtration and high-performance liquid chromatography fractionation with pulsed amperometric detection. The major components were XG subunits, namely one of the two possible monogalactosyl octasaccharides (-XXLG-) and digalactosyl nonasaccharide (-XLLG-), whether the predominant octasaccharide in the acceptor was XXLG (as in tamarind seed XG) or XLXG (as in nasturtium seed XG). It is concluded that the first xylosylglucose from the reducing end of the subunits was the Gal acceptor locus preferred by the solubilized pea transferase. These observations are incorporated into a model for the biosynthesis of cell wall XGs.
Heat Treatment Results in a Loss of Transgene-Encoded Activities in Several Tobacco Lines
Authors: Neumann K. , Droge-Laser W. , Kohne S. , Broer I.
Published: July 2002

Heat treatment (37[deg]C) of transgenic tobacco (Nicotiana tabacum) plants led to a reversible reduction or complete loss of transgene-encoded activities in about 40% of 10 independent transformants carrying the luciferase-coding region fused to the 35S cauliflower mosaic virus or the soybean small subunit promoter and the nopaline synthase promoter driving the neomycin phosphotransferase gene, whereas the other lines had temperature-tolerant activities. Temperature sensitivity or tolerance of transgene-encoded activities was heritable. In some of the lines, temperature sensitivity of the transgene-encoded activities depended on the stage of development, occurring in either seedlings (40% luciferase and 50% neomycin phosphotransferase) or adult plants (both 40%). The phenomenon did not correlate with copy numbers or the homo- or hemizygous state of the transgenes. In lines harboring a temperature-sensitive luciferase activity, reduction of bioluminescence was observed after 2 to 3 h at 37[deg]C. Activity was regained after 2 h of subsequent cultivation at 25[deg]C. Irrespective of the reaction to the heat treatment, the level of luciferase RNA was slightly increased at 37[deg]C. Only in lines showing temperature sensitivity of transgene-encoded activities was the amount of luciferase and neomycin phosphotransferase strongly reduced. In sterile culture, heat treatment for 15 d did not cause visible damage or changes in plant morphology. In all plants tested a slight induction of the heat-shock response was observed at 37[deg]C.
Evidence That Heat and Ultraviolet Radiation Activate a Common Stress-Response Program in Plants That Is Alterd in the uvh6 Mutant of Arabidopsis thaliana
Authors: Jenkins M. E. , Suzuki T. C. , Mount D. W.
Published: July 2002

The uvh6 mutant of Arabidopsis was previously isolated in a screen for increased sensitivity to ultraviolet (UV) radiation. uvh6 mutant plants were killed by incubation at 37[deg]C for 4 d, a treatment not lethal to wild-type plants. Furthermore, under permissive conditions, uvh6 plants were yellow-green with an approximately one-third lower chlorophyll content. Genetic analysis of the uvh6 mutant strongly suggested that all three mutant phenotypes were due to mutation at the same genetic locus. To understand UVH6 function more fully, the response of wild-type plants to growth at elevated temperatures and exposure to UV radiation was analyzed. Wild-type plants grown at 30[deg]C were as UV-hypersensitive and yellow-green as uvh6 mutant plants grown at 24[deg]C. Mutant uvh6 plants induced heat-shock protein HSP21 at a lower threshold temperature than wild-type plants, indicating that the uvh6 mutant was exhibiting signs of heat stress at a 4 to 5[deg]C lower temperature than wild-type plants. We propose that UV damage and heat induce a common stress response in plants that leads to tissue death and reduced chloroplast function, and that the UVH6 product is a negative regulator of this response.
Developmental and Hormonal Regulation of Genes Coding for Proline-Rich Proteins in Female Inflorescences and Kernels of Maize1
Authors: Josè-Estanyol Matilde , Puigdomènech Pere
Published: July 2002

The pattern of expression of two genes coding for proteins rich in proline, HyPRP(hybrid proline-rich protein) and HRGP(hydroxyproline-rich glycoprotein), has been studied in maize (Zea mays) embryos by RNA analysis and in situ hybridization. mRNA accumulation is high during the first 20 d after pollination, and disappears in the maturation stages of embryogenesis. The two genes are also expressed during the development of the pistillate spikelet and during the first stages of embryo development in adjacent but different tissues. HyPRPmRNA accumulates mainly in the scutellum and HRGP mRNA mainly in the embryo axis and the suspensor. The two genes appear to be under the control of different regulatory pathways during embryogenesis. We show that HyPRP is repressed by abscisic acid and stress treatments, with the exception of cold treatment. In contrast, HRGP is affected positively by specific stress treatments.
Temporal Regulation of Somatic Embryogenesis by Adjusting Cellular Polyamine Content in Eggplant1
Authors: Singh Yadav Jitender , Venkat Rajam Manchikatla
Published: July 2002

Four critical stages of embryogenesis, including callus induction, cellular acquisition of morphogenetic competence, expression of embryogenic program, and development and maturation of somatic embryos during somatic embryogenesis from leaf discs of eggplant (Solanum melongena L.), were identified by scanning electron microscopy. Temporal changes in arginine decarboxylase (ADC) activity and polyamines (PAs) during critical stages of embryogenesis revealed that high levels of PAs (especially putrescine [PUT]), due to higher ADC activity in discs from the apical region (with high embryogenic capacity) than from the basal region of the leaf (with poor embryogenic capacity), were correlated with differential embryogenesis response. Kinetic studies of the up- and down-regulation of embryogenesis revealed that PUT and difluoromethylarginine pretreatments were most effective before the onset of embryogenesis. Basal discs pretreated with PUT for 4 to 7 d showed improved embryogenesis that was comparable to apical discs. PA content at various critical steps in embryogenesis from basal discs were found to be comparable to that of apical discs following adjustments of cellular PA content by PUT. In contrast, pretreatment of apical discs with difluoromethylarginine for 3 d significantly reduced ADC activity, cellular PA content, and embryogenesis to levels that were comparable to basal discs. Discs from the basal region of leaves treated with PUT for 3 d during the identified stages of embryogenesis improved their embryogenic potential.
Soybean Lipoxygenase-1 Oxidizes 3Z-Nonenal
Authors: Gardner Harold W. , Grove Marilyn J.
Published: July 2002

In previous work with soybean (Glycine max), it was reported that the initial product of 3Z-nonenal (NON) oxidation is 4-hydroperoxy-2E-nonenal (4-HPNE). 4-HPNE can be converted to 4-hydroxy-2E-nonenal by a hydroperoxide-dependent peroxygenase. In the present work we have attempted to purify the 4-HPNE-producing oxygenase from soybean seed. Chromatography on various supports had shown that O2 uptake with NON substrate consistently coincided with lipoxygenase (LOX)-1 activity. Compared with oxidation of LOX's preferred substrate, linoleic acid, the activity with NON was about 400- to 1000-fold less. Rather than obtaining the expected 4-HPNE, 4-oxo-2E-nonenal was the principal product of NON oxidation, presumably arising from the enzyme-generated alkoxyl radical of 4-HPNE. In further work a precipitous drop in activity was noted upon dilution of LOX-1 concentration; however, activity could be enhanced by spiking the reaction with 13S-hydroperoxy-9Z,11E-octadecadienoic acid. Under these conditions the principal product of NON oxidation shifted to the expected 4-HPNE. 4-HPNE was demonstrated to be 83% of the 4S-hydroperoxy-stereoisomer. Therefore, LOX-1 is also a 3Z-alkenal oxygenase, and it exerts the same stereospecificity of oxidation as it does with polyunsaturated fatty acids. Two other LOX isozymes of soybean seed were also found to oxidize NON to 4-HPNE with an excess of 4S-hydroperoxy-stereoisomer.
ADP-Glucose Pyrophosphorylase from Potato Tubers. Site-Directed Mutagenesis Studies of the Regulatory Sites1
Authors: Ballicora Miguel A. , Fu Yingbin , Nesbitt Natasha M. , Preiss Jack
Published: July 2002

Several lysines (Lys) were determined to be involved in the regulation of the ADP-glucose (Glc) pyrophosphorylase from spinach leaf and the cyanobacteriumAnabaena sp. PCC 7120 (K. Ball, J. Preiss [1994] J Biol Chem 269: 24706–24711; Y. Charng, A.A. Iglesias, J. Preiss [1994] J Biol Chem 269: 24107–24113). Site-directed mutagenesis was used to investigate the relative roles of the conserved Lys in the heterotetrameric enzyme from potato (Solanum tuberosumL.) tubers. Mutations to alanine of Lys-404 and Lys-441 on the small subunit decreased the apparent affinity for the activator, 3-phosphoglycerate, by 3090- and 54-fold, respectively. The apparent affinity for the inhibitor, phosphate, decreased greater than 400-fold. Mutation of Lys-441 to glutamic acid showed even larger effects. When Lys-417 and Lys-455 on the large subunit were mutated to alanine, the phosphate inhibition was not altered and the apparent affinity for the activator decreased only 9- and 3-fold, respectively. Mutations of these residues to glutamic acid only decreased the affinity for the activator 12- and 5-fold, respectively. No significant changes were observed on other kinetic constants for the substrates ADP-Glc, pyrophosphate, and Mg2+. These data indicate that Lys-404 and Lys-441 on the small subunit are more important for the regulation of the ADP-Glc pyrophosphorylase than their homologous residues in the large subunit.
Acclimation of Photosynthesis to Elevated CO2under Low-Nitrogen Nutrition Is Affected by the Capacity for Assimilate Utilization. Perennial Ryegrass under Free-Air CO2 Enrichment
Authors: Rogers Alistair , Fischer Bernt U. , Bryant Jonathan , Frehner Marco , Blum Herbert , Raines Christine A. , Long Stephen P.
Published: July 2002

Acclimation of photosynthesis to elevated CO2 has previously been shown to be more pronounced when N supply is poor. Is this a direct effect of N or an indirect effect of N by limiting the development of sinks for photoassimilate? This question was tested by growing a perennial ryegrass (Lolium perenne) in the field under elevated (60 Pa) and current (36 Pa) partial pressures of CO2(pCO2) at low and high levels of N fertilization. Cutting of this herbage crop at 4- to 8-week intervals removed about 80% of the canopy, therefore decreasing the ratio of photosynthetic area to sinks for photoassimilate. Leaf photosynthesis, in vivo carboxylation capacity, carbohydrate, N, ribulose-1,5-bisphosphate carboxylase/oxygenase, sedoheptulose-1,7-bisphosphatase, and chloroplastic fructose-1,6-bisphosphatase levels were determined for mature lamina during two consecutive summers. Just before the cut, when the canopy was relatively large, growth at elevatedpCO2 and low N resulted in significant decreases in carboxylation capacity and the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase protein. In high N there were no significant decreases in carboxylation capacity or proteins, but chloroplastic fructose-1,6-bisphosphatase protein levels increased significantly. Elevated pCO2resulted in a marked and significant increase in leaf carbohydrate content at low N, but had no effect at high N. This acclimation at low N was absent after the harvest, when the canopy size was small. These results suggest that acclimation under low N is caused by limitation of sink development rather than being a direct effect of N supply on photosynthesis.
Embryo-Specific Gene Expression in Microspore-Derived Embryos ofBrassica napus.An Interaction between Abscisic Acid and Jasmonic Acid1,2
Authors: Hays Dirk B. , Wilen Ronald W. , Sheng Chuxing , Moloney Maurice M. , Pharis Richard P.
Published: July 2002

The induction of napin and oleosin gene expression in Brassica napus microspore-derived embryos (MDEs) was studied to assess the possible interaction between abscisic acid (ABA) and jasmonic acid (JA). Napin and oleosin transcripts were detected sooner following treatment with ABA than JA. Treatment of MDEs with ABA plus JA gave an additive accumulation of both napin and oleosin mRNA, the absolute amount being dependent on the concentration of each hormone. Endogenous ABA levels were reduced by 10-fold after treatment with JA, negating the possibility that the observed additive interaction was due to JA-induced ABA biosynthesis. Also, JA did not significantly increase the uptake of [3H-ABA] from the medium into MDEs. This suggests that the additive interaction was not due to an enhanced carrier-mediated ABA uptake by JA. Finally, when JA was added to MDEs that had been treated with the ABA biosynthesis inhibitor fluridone, napin mRNA did not increase. Based on these results with the MDE system, it is possible that embryos of B. napus use endogenous JA to modulate ABA effects on expression of both napin and oleosin. In addition, JA could play a causal role in the reduction of ABA that occurs during late stages of seed development.
Gene-Specific Changes in α-Tubulin Transcript Accumulation in Developing Cotton Fibers
Authors: Whittaker David J. , Triplett Barbara A.
Published: July 2002

The fibers of cotton (Gossypium hirsutum) are single-cell trichomes that undergo rapid and synchronous elongation. Cortical microtubules provide spatial information necessary for the alignment of cellulose microfibrils that confine and regulate cell elongation. We used gene-specific probes to investigate α-tubulin transcript levels in elongating cotton fibers. Two discrete patterns of transcript accumulation were observed. Whereas transcripts of α-tubulin genes GhTua2/3 and GhTua4 increased in abundance from 10 to 20 d post anthesis (DPA), GhTua1 and GhTua5 transcripts were abundant only through to 14 DPA, and dropped significantly at 16 DPA with the onset of secondary wall synthesis. This is the first report, to our knowledge, of gene-specific changes in tubulin transcript levels during the development of a terminally differentiated plant cell. The decrease in abundance of GhTua1 and GhTua5 transcripts was correlated with pronounced changes in cell wall structure, suggesting that α-tubulin isoforms may be functionally distinct in elongating fiber cells. Although total α-tubulin transcript levels were much higher in fiber than several other tissues, including the hypocotyl and pollen, none of the α-tubulins was specific to fiber cells.
Differences in Spatial Expression between 14-3-3 Isoforms in Germinating Barley Embryos
Authors: Testerink Christa , van der Meulen René M. , Oppedijk Berry J. , de Boer Albertus H. , Heimovaara-Dijkstra Sjoukje , Kijne Jan W. , Wang Mei
Published: July 2002

The family of 14-3-3 proteins is ubiquitous in eukaryotes and has been shown to exert an array of functions. We were interested in the possible role of 14-3-3 proteins in seed germination. Therefore, we studied the expression of 14-3-3 mRNA and protein in barley (Hordeum distichum L.) embryos during germination. With the use of specific cDNA probes and antibodies, we could detect individual expression of three 14-3-3 isoforms, 14-3-3A, 14-3-3B, and 14-3-3C. Each homolog was found to be expressed in barley embryos. Whereas protein levels of all three isoforms were constant during germination, mRNA expression was found to be induced upon imbibition of the grains. The induction of14-3-3A gene expression during germination was different from that of14-3-3B and14-3-3C. In situ immunolocalization analysis showed similar spatial expression for 14-3-3A and 14-3-3B, while 14-3-3C expression was markedly different. Whereas 14-3-3A and 14-3-3B were expressed throughout the embryo, 14-3-3C expression was tissue specific, with the strongest expression observed in the scutellum and the L2 layer of the shoot apical meristem. These results show that 14-3-3 homologs are differently regulated in barley embryos, and provide a first step in acquiring more knowledge about the role of 14-3-3 proteins in the germination process.
The Role of Photosynthetic Electron Transport in the Oxidative Degradation of Chloroplastic Glutamine Synthetase
Authors: Palatnik Javier F. , Carrillo Néstor , Valle Estela M.
Published: July 2002

The stability of chloroplastic glutamine synthetase (GS; EC 6.3.1.2) was investigated under photooxidative stress using wheat (Triticum aestivum L.) leaves, chloroplasts, and chloroplast lysates. Illuminated seedlings sprayed with the superoxide radical (O⨪2) propagator methyl viologen showed rapid GS decline dependent on MV concentration and exposure time. Degradation products of approximately 39 and 31 kD were detected when chloroplast lysates containing both stroma and thylakoids were illuminated in the presence of MV or H2O2. In all cases, GS cleavage was prevented by the addition of the electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Full protection against degradation could also be obtained by the incorporation of chelators or antioxidant enzymes. Maximal rates of degradation required the presence of transition metals and reducing compounds such as NADPH or dithiothreitol. Similar patterns of GS cleavage were obtained when seedlings were exposed to high doses of irradiation. The results indicate that chloroplastic GS is extremely prone to oxidative cleavage, and that reduced transition metals, presumably resulting from the destruction of iron-sulfur clusters by light-generated O⨪2, play a crucial role in the degradation process. The physiological implications of GS lability to oxidative stress are discussed.
Induced Resistance to Pathogenic Fungi in Norway Spruce
Authors: Krokene Paal , Christiansen Erik , Solheim Halvor , Franceschi Vincent Ray , Berryman Alan Andrew
Published: July 2002

Norway spruce (Picea abies) trees (approximately 16 m high) of a single clone were used to study the effects of fungal infection and wounding on induction of resistance to the bark beetle-associated bluestain fungusCeratocystis polonica. A dose-response experiment was designed involving three different dosages of fungal (fungus and wound) and sterile agar (wound) pretreatment inoculations (10, 50, or 100 inoculations/m2 on the stem between 0.8 and 2.0 m high). Three weeks after pretreatment, trees were challenged with a massive C. polonica inoculation (400 inoculations/m2). Control trees that received no pretreatment were heavily colonized and killed by the challenge inoculation. The high and medium fungal pretreatments reduced subsequent fungal colonization success by 76% to 97% relative to the control, and fungal pretreatments protected the trees much more efficiently than sterile agar pretreatments. The protection was demonstrated to be local and not systemic in a subsequent experiment, where trees were pretreated with the medium fungal dosage on the lower bole and challenge inoculated further up the stem. Protection was also demonstrated to be pathogen nonspecific, as trees that had been pretreated with a medium dosage of the root rot fungusHeterobasidion annosum showed enhanced resistance to challenge inoculation with C. polonica.