bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ceric(IV) Ammonium Nitrate: A Novel Reagent for the Synthesis of Homoallyl Alcohols
Authors: Yadav J S , Reddy B V S , Krishna A D , Sadasiv K , Chary Ch Janardhana 
Published: February 2003

Abstract
A rapid and highly efficient method has been developed for the allylation of aldehydes with allyltributylstannane using a catalytic amount of ceric ammonium nitrate in acetonitrile under mild and neutral conditions to afford the corresponding homoallyl alcohols in excellent yields with high chemoselectivity. Allylation of ketones has also been achieved with tetraallytin under similar reaction conditions.
Studies on Synthesis of MMH and Rheological Properties of Concentrated MMH Dispersions
Authors: Guo Peizhi , Sun Dejun , Zhang Jie , Zhang Chunguang 
Published: February 2003

Abstract
A positively charged mixed metal hydroxides (MMH) was synthesized by a non-steady method. The chemical composition and morphology of the positive MMH nanoparticles were studied by ICP, Mastersizer and TEM. Preliminary rheological measurements indicated that when adding NaCl to exhaustively deionized MMH dispersion, the yield stress, G′ and G″ first decreased to a minimum, and then rose again.
Electropolymerization of Bithienyl-appended Cerium(III) Triple Decker Porphyrin Complex
Authors: Yamashita Kousei , Ikeda Masato , Takeuchi Masayuki , Shinkai Seiji 
Published: February 2003

Abstract
A cerium(III) triple decker porphyrin complex bearing bithienyl substituents (1) at the peripheral meso-positions was synthesized. Electrochemical polymerization of the triple decker porphyrin gave a unique polymer film on the ITO electrode surface without decomposition.
The refining influence of ethics committees on animal experimentation in Sweden
Authors: Hagelin Joakim , Hau Jann , Carlsson Hans-Erik 
Published: February 2003

Mandatory scrutiny of projects by animal ethics committees was introduced in Sweden in 1979. The present study investigated the minutes of meetings held between 1989 and 2000 at which consideration of applications for experimental work in animals resulted in requests for modification ( n = 3607). 18.1% of the applications received were approved only after modifications. The majority of the changes requested may be classified as 'Refinement'. The most common requests were for improvement of project design, euthanasia method and housing and husbandry. There was a relative increase in modifications requested by the committees related to anaesthesia, choice of licensed supervisor and the need for licenses or informed consent from animal owners during the period investigated. There was a relative decrease in modifications related to euthanasia, housing and husbandry, and general endpoint assertions. The results suggest that the work of the committees may be perceived as an ongoing process, since several of the applications for which modification was requested were projects that had been approved on a previous occasion but were now up for renewal. In order to have maximal influence on the refinement of scientific protocols it is important that the scientists in the committees are continuously updated on developments in laboratory animal science.
Cilia‐lacking respiratory cells in ciliary aplasia
Authors: de SANTI Maria Margherita , GARDI Concetta , BARLOCCO Gabriele , CANCIANI Mario , MASTELLA Gianni , LUNGARELLA Giuseppe 
Published: February 2003

This report describes the ultrastructural alterations observed in the nasal and bronchial mucosa of an 11‐yr‐old male suffering from immotile cilia syndrome (ICS).The morphological features observed in this patient are consistent with a ciliary aplasia. In fact, ciliated cells appeared to be replaced by columnar cells lacking cilia and basal bodies, and bearing on their surface cilium‐like projections without any internal axonemal structure.In spite of the absence of basal bodies, centrioles, and kinocilia, these cells unexpectedly showed mature striated roots and centriolar precursor material scattered throughout the apical cytoplasm.These data suggest that control over basal body assembly is distinct from control over striated root formation. The presence of the above‐reported structures in cells otherwise presenting many morphological features of normal ciliated cells is discussed on the basis of current knowledge of respiratory cilia biogenesis.
Evidence for seed dispersal by the catfish Auchenipterichthys longimanus in an Amazonian lake
Authors: Mannheimer Simone , Bevilacqua Gabriela , Caramaschi Érica P. , Rubio Scarano Fábio 
Published: February 2003

The annual flood pulses of central Amazonian rivers
inundate marginal forests to 10 m depth or more (Furch &
Otto 1987, Junk et al. 1989). The regularity of this
flooding seems to have promoted the development of a
complex relationship between forest plants and fishes that
consume their seeds (Goulding 1980). Several fish species
migrate into the flooded forests to feed on buoyant fruits
and seeds, and many plant species reach their fruiting
peak during the flood season. Fruits and seeds have been
reported to have adaptive features related to water
(hydrochory) and/or fish (ichthyochory) dispersal
(Araújo-Lima & Goulding 1998, Gottsberger 1978,
Goulding 1980, Kubitzki & Ziburski 1994, Scarano 1998,
Williamson 1999, Williamson & Costa 2000). Strong
multicuspidate teeth in frugivorous fishes, fruit/seed buoyancy
(Goulding 1980) and chemical signs released by
fallen fruit to attract fish (Araújo-Lima & Goulding 1998)
are mechanisms for the seed dispersal of the flooded forest community.
Impacts of varying habitat quality on the physiological stress of spotted salamanders (Ambystoma maculatum)
Authors: Newcomb Homan Rebecca , Regosin Jonathan V. , Rodrigues Daniel M. , Reed J. Michael , Windmiller Bryan S. , Romero L. Michael 
Published: February 2003

AbstractWe sampled blood from free‐living spotted salamanders (Ambystoma maculatum) to test whether differences in the concentrations of a stress hormone (corticosterone) were associated with different qualities of breeding and migration habitat. Spotted salamanders are forest specialists that migrate to vernal pools to breed, and upland habitat degradation may have sub‐lethal effects on animals that lead to population declines. An individual's level of physiological stress may function as a biomonitor for sub‐lethal effects, and thus as a biomonitor for ecosystem quality. We compared unstressed (baseline) and stress‐induced corticosterone concentrations in spotted salamanders: (1) at sites that differed in amount of forest loss; (2) during breeding migration across forest habitat versus pavement; (3) in microhabitats that varied in soil drainage and canopy cover. Removal of large amounts of terrestrial habitat surrounding a breeding pond was correlated with lower baseline (in males) and stress‐induced corticosterone concentrations, which may indicate healthy individuals with a reduced ability to respond to additional stress or individuals experiencing chronic stress. Male salamanders migrating across pavement had elevated baseline corticosterone concentrations compared to animals migrating through a forest, consistent with an acute stress response. However, concentrations of corticosterone did not differ between individuals in microhabitats with canopy cover and well‐drained soil versus those in microhabitats with no canopy cover and/or swampy soil. This endocrinological technique may be one useful measure of a population's health, helping to identify populations where further ecological study is recommended to evaluate conservation concerns.
Why sparrow distributions do not match model predictions
Authors: Jenkins Clinton N. , Powell Robert D. , Bass Oron L. , Pimm Stuart L. 
Published: February 2003

AbstractA companion paper in this issue describes the mapping of Cape Sable seaside sparrow (Ammodramus maritimus mirabilis) habitat using satellite imagery. In general, those maps are correct. However, testing against an independent survey of the sparrow population does identify errors. Those errors fall into two categories, model errors and bird errors. The model errors result from genuine problems with the model. More interesting for conservation are the bird errors, which are more numerous. They are of two types. (1) Commission errors: some suitable habitat does not contain birds. These are areas where prior events have depleted sparrow numbers, but because the sparrows do not disperse long distances, they cannot occupy it quickly. (2) Omission errors: some birds remain in unsuitable habitat that was formerly suitable. This results from the sparrow's very high site fidelity. Often, they will not leave an area even when it is no longer suitable. The consequences of these bird errors are that some habitat and some birds are not contributing to the species' survival. Thus, an estimate of only the amount of habitat or only the sparrow population may present an overly optimistic view of the sparrow's plight.
Biological determinants of extinction risk: why are smaller species less vulnerable?
Authors: Cardillo Marcel 
Published: February 2003

AbstractIt is becoming increasingly clear that species of smaller body size tend to be less vulnerable to contemporary extinction threats than larger species, but few studies have examined the mechanisms underlying this pattern. In this paper, data for the Australian terrestrial mammal fauna are used to ask whether higher reproductive output or smaller home ranges can explain the reduced extinction risk of smaller species. Extinct and endangered species do indeed have smaller litters and larger home ranges for their body size than expected under a null model. In multiple regressions, however, only litter size is a significant predictor of extinction risk once body size and phylogeny are controlled for. Larger litters contribute to fast population growth, and are probably part of the reason that smaller species are less extinction‐prone. The effect of litter size varies between the mesic coastal regions and the arid interior of Australia, indicating that the environment a species inhabits mediates the effect of biology on extinction risk. These results suggest that predicting extinction risk from biological traits is likely to be a complex task which must consider explicitly interactions between biology and environment.
Expression of a Bifunctional Fusion of the Escherichia coli Genes for Trehalose-6-Phosphate Synthase and Trehalose-6-Phosphate Phosphatase in Transgenic Rice Plants Increases Trehalose Accumulation and Abiotic Stress Tolerance without Stunting Growth
Authors: Jang In-Cheol , Oh Se-Jun , Seo Ju-Seok , Choi Won-Bin , Song Sang Ik , Kim Chung Ho , Kim Youn Shic , Seo Hak-Soo , Choi Yang Do , Nahm Baek Hie , Kim Ju-Kon 
Published: February 2003

Abstract
Trehalose plays an important role in stress tolerance in plants. Trehalose-producing, transgenic rice (Oryza sativa) plants were generated by the introduction of a gene encoding a bifunctional fusion (TPSP) of the trehalose-6-phosphate (T-6-P) synthase (TPS) and T-6-P phosphatase (TPP) ofEscherichia coli, under the control of the maize (Zea mays) ubiquitin promoter (Ubi1). The high catalytic efficiency (Seo et al., 2000) of the fusion enzyme and the single-gene engineering strategy make this an attractive candidate for high-level production of trehalose; it has the added advantage of reducing the accumulation of potentially deleterious T-6-P. The trehalose levels in leaf and seed extracts from Ubi1::TPSP plants were increased up to 1.076 mg g fresh weight−1. This level was 200-fold higher than that of transgenic tobacco (Nicotiana tabacum) plants transformed independently with eitherTPS or TPP expression cassettes. The carbohydrate profiles were significantly altered in the seeds, but not in the leaves, of Ubi1::TPSP plants. It has been reported that transgenic plants with E. coli TPSand/or TPP were severely stunted and root morphology was altered. Interestingly, our Ubi1::TPSP plants showed no growth inhibition or visible phenotypic alterations despite the high-level production of trehalose. Moreover, trehalose accumulation in Ubi1::TPSP plants resulted in increased tolerance to drought, salt, and cold, as shown by chlorophyll fluorescence and growth inhibition analyses. Thus, our results suggest that trehalose acts as a global protectant against abiotic stress, and that rice is more tolerant to trehalose synthesis than dicots.
Subcellular Targeting of Methylmercury Lyase Enhances Its Specific Activity for Organic Mercury Detoxification in Plants
Authors: Bizily Scott P. , Kim Tehryung , Kandasamy Muthugapatti K. , Meagher Richard B. 
Published: February 2003

Abstract
Methylmercury is an environmental pollutant that biomagnifies in the aquatic food chain with severe consequences for humans and other animals. In an effort to remove this toxin in situ, we have been engineering plants that express the bacterial mercury resistance enzymes organomercurial lyase MerB and mercuric ion reductase MerA. In vivo kinetics experiments suggest that the diffusion of hydrophobic organic mercury to MerB limits the rate of the coupled reaction with MerA (Bizily et al., 2000). To optimize reaction kinetics for organic mercury compounds, themerB gene was engineered to target MerB for accumulation in the endoplasmic reticulum and for secretion to the cell wall. Plants expressing the targeted MerB proteins and cytoplasmic MerA are highly resistant to organic mercury and degrade organic mercury at 10 to 70 times higher specific activity than plants with the cytoplasmically distributed wild-type MerB enzyme. MerB protein in endoplasmic reticulum-targeted plants appears to accumulate in large vesicular structures that can be visualized in immunolabeled plant cells. These results suggest that the toxic effects of organic mercury are focused in microenvironments of the secretory pathway, that these hydrophobic compartments provide more favorable reaction conditions for MerB activity, and that moderate increases in targeted MerB expression will lead to significant gains in detoxification. In summary, to maximize phytoremediation efficiency of hydrophobic pollutants in plants, it may be beneficial to target enzymes to specific subcellular environments.
A New Type of a Multifunctional β-Oxidation Enzyme in Euglena
Authors: Winkler Uwe , Säftel Werner , Stabenau Helmut 
Published: February 2003

Abstract
The biochemical and molecular properties of the β-oxidation enzymes from algae have not been investigated yet. The present study provides such data for the phylogenetically old alga Euglena (Euglena gracilis). A novel multifunctional β-oxidation complex was purified to homogeneity by ammonium sulfate precipitation, density gradient centrifugation, and ion-exchange chromatography. Monospecific antibodies used in immunocytochemical experiments revealed that the enzyme is located in mitochondria. The enzyme complex is composed of 3-hydroxyacyl-coenzyme A (-CoA) dehydrogenase, 2-enoyl-CoA hydratase, thiolase, and epimerase activities. The purified enzyme exhibits a native molecular mass of about 460 kD, consisting of 45.5-, 44.5-, 34-, and 32-kD subunits. Subunits dissociated from the complete complex revealed that the hydratase and the thiolase functions are located on the large subunits, whereas two dehydrogenase functions are located on the two smaller subunits. Epimerase activity was only measurable in the complete enzyme complex. From the use of stereoisomers and sequence data, it was concluded that the 2-enoyl-CoA hydratase catalyzes the formation ofl-hydroxyacyl CoA isomers and that both of the different 3-hydroxyacyl-CoA dehydrogenase functions on the 32- and 34-kD subunits are specific to l-isomers as substrates, respectively. All of these data suggest that the Euglena enzyme belongs to the family of β-oxidation enzymes that degrade acyl-CoAs via l-isomers and that it is composed of subunits comparable with subunits of monofunctional β-oxidation enzymes. It is concluded that the Euglena enzyme phylogenetically developed from monospecific enzymes in archeons by non-covalent combination of subunits and presents an additional line for the evolutionary development of multifunctional β-oxidation enzymes.
Functional Divergence of a Syntenic Invertase Gene Family in Tomato, Potato, and Arabidopsis
Authors: Fridman Eyal , Zamir Dani 
Published: February 2003

Abstract
Comparative analysis of complex developmental pathways depends on our ability to resolve the function of members of gene families across taxonomic groups. LIN5, which belongs to a small gene family of apoplastic invertases in tomato (Lycopersicon esculentum), is a quantitative trait locus that modifies fruit sugar composition. We have compared the genomic organization and expression of this gene family in the two distantly related species: tomato and Arabidopsis. Invertase family members reside on segmental duplications in the near-colinear genomes of tomato and potato (Solanum tuberosum). These chromosomal segments are syntenically duplicated in the model plant Arabidopsis. On the basis of phylogenetic analysis of genes in the microsyntenic region, we conclude that these segmental duplications arose independently after the separation of the tomato/potato clade from Arabidopsis. Rapid regulatory divergence is characteristic of the invertase family. Interestingly, although the processes of gene duplication and specialization of expression occurred separately in the two species, synteny-based orthologs from both clades acquired similar organ-specific expression. This similar expression pattern of the genes is evidence of comparable evolutionary constraints (parallel evolution) rather than of functional orthology. The observation that functional orthology cannot be identified through analysis of expression similarity highlights the caution that needs to be exercised in extrapolating developmental networks from a model organism.
AtCSLA7, a Cellulose Synthase-Like Putative Glycosyltransferase, Is Important for Pollen Tube Growth and Embryogenesis in Arabidopsis
Authors: Goubet Florence , Misrahi Audrey , Park Soon Ki , Zhang Zhinong , Twell David , Dupree Paul 
Published: February 2003

Abstract
The cellulose synthase-like proteins are a large family of proteins in plants thought to be processive polysaccharide β-glycosyltransferases. We have characterized an Arabidopsis mutant with a transposon insertion in the gene encoding AtCSLA7 of the CSLA subfamily. Analysis of the transmission efficiency of the insertion indicated that AtCSLA7 is important for pollen tube growth. Moreover, the homozygous insertion was embryo lethal. A detailed analysis of seed developmental progression revealed that mutant embryos developed more slowly than wild-type siblings. The mutant embryos also showed abnormal cell patterning and they arrested at a globular stage. The defective embryonic development was associated with reduced proliferation and failed cellularization of the endosperm. AtCSLA7 is widely expressed, and is likely to be required for synthesis of a cell wall polysaccharide found throughout the plant. Our results suggest that this polysaccharide is essential for cell wall structure or for signaling during plant embryo development.
Dictionary Learning Algorithms for Sparse Representation
Authors: Kreutz-Delgado Kenneth , Murray Joseph F. , Rao Bhaskar D. , Engan Kjersti , Lee Te-Won , Sejnowski Terrence J. 
Published: February 2003

Algorithms for data-driven learning of domain-specific overcomplete dictionaries are developed to obtain maximum likelihood and maximum a posteriori dictionary estimates based on the use of Bayesian models with concave/Schur-concave (CSC) negative log priors. Such priors are appropriate for obtaining sparse representations of environmental signals within an appropriately chosen (environmentally matched) dictionary. The elements of the dictionary can be interpreted as concepts, features, or words capable of succinct expression of events encountered in the environment (the source of the measured signals). This is a generalization of vector quantization in that one is interested in a description involving a few dictionary entries (the proverbial “25 words or less”), but not necessarily as succinct as one entry. To learn an environmentally adapted dictionary capable of concise expression of signals generated by the environment, we develop algorithms that iterate between a representative set of sparse representations found by variants of FOCUSS and an update of the dictionary using these sparse representations. Experiments were performed using synthetic data and natural images. For complete dictionaries, we demonstrate that our algorithms have improved performance over other independent component analysis (ICA) methods, measured in terms of signal-to-noise ratios of separated sources. In the overcomplete case, we show that the true underlying dictionary and sparse sources can be accurately recovered. In tests with natural images, learned overcomplete dictionaries are shown to have higher coding efficiency than complete dictionaries; that is, images encoded with an overcomplete dictionary have both higher compression (fewer bits per pixel) and higher accuracy (lower mean square error).
Postrelapse Survival in Osteosarcoma of the Extremities: Prognostic Factors for Long-Term Survival
Authors: Ferrari Stefano , Briccoli Antonio , Mercuri Mario , Bertoni Franco , Picci Piero , Tienghi Amelia , Del Prever Adalberto Brach , Fagioli Franca , Comandone Alessandro , Bacci Gaetano 
Published: February 2003

Purpose: To identify factors that influence postrelapse survival (PRS) in patients with nonmetastatic osteosarcoma of the extremity Patients and Methods: One hundred sixty-two patients with recurrent osteosarcoma of the extremity were retrospectively reviewed. The first-line treatment included surgery of the primary lesion and chemotherapy with methotrexate, doxorubicin, cisplatin, and ifosfamide. Results: The projected 5-year PRS rate was 28%. Patients who had complete surgery of recurrence had a 5-year PRS of 39%, whereas for those who did not have complete surgery, PRS was 0% at 3 years (P < .0001). In the latter group, PRS was not influenced by site of recurrence and relapse-free interval (RFI), although it was influenced (P = .006) by the use of second-line chemotherapy (PRS, 53% at 12 months for patients who received chemotherapy v 12% for those who did not). In patients who had complete surgery, PRS was influenced by site of relapse (5-year PRS, lung 44%, other 19%; P < .06), RFI (5-year PRS at ≤ 24 months, 20%; at > 24 months, 60%; P < .0001), and number of lung metastases (5-year PRS, two or fewer nodules, 59%; more than two nodules, 14%; P < .0001) but not by the use of a second-line chemotherapy treatment. Conclusion: RFI, site of metastases, and number of pulmonary nodules are the main prognostic factors for PRS in osteosarcoma. Complete surgery of recurrence is pivotal in the strategy of treatment. Patients with unresectable recurrence benefit from second-line chemotherapy, whereas our data do not support a generalized use of chemotherapy after complete surgery of first recurrence.