bluuebunny/crossref_metadata_2025_split huggingface dataset:
The generalized linear model for spatial data: assessing the effects of environmental covariates on population density in the field
Authors: Dalthorp D. 
Published: April 2004

AbstractWith interest in spatial ecology growing, correlational field studies are likely to become increasingly important. Unfortunately, ecological field data often do not follow the assumptions of classical statistics, so techniques like the popular and powerful multiple linear regression and its variants are often unreliable, and results can be misleading. The generalized linear model (GLM) is a flexible extension of linear regression that has proved especially useful for discrete data. In this paper, the technique is adapted to accommodate spatially correlated, discrete data. Specifically, to demonstrate the approach, Japanese beetle grub [Popillia japonica Newman (Coleoptera, Scarabaeidae)] population density in the field is modeled as a function of soil organic matter content. The response variable (grub counts in small soil samples) was a spatially autocorrelated, discrete random variable. Three classes of GLMs of the association between soil organic matter content and grub density were compared: (i) regression (assuming normally distributed response variable), (ii) GLM assuming negative binomial counts, and (iii) GLM based on the assumption that the counts conformed to Taylor's power law (TPL). Because the grubs were distributed in patches rather than at random, models that explicitly accounted for the spatial autocorrelation of grub counts were constructed, and compared with models that assumed independent observations. The fitted values for the discrete GLMs [viz., (ii) and (iii)] differed noticeably from the fitted values from multiple regression; but fitted values among the negative binomial and TPL GLMs were virtually identical, regardless of whether the spatial covariance was incorporated into a model, whether a spherical or exponential variogram model was used, or whether variance function parameters were estimated over a large or small scale. However, P‐values for the overall significance of the models depended heavily on whether the GLM assumed a discrete or continuous response variable, and whether or not spatial autocorrelation in the response variable was accounted for. On average, P‐values were 45‐fold higher in the spatial GLMs than in the non‐spatial and 23‐fold higher in the discrete GLMs than in the continuous.
Internationalization and the Dynamics of Product Adaptation—An Empirical Investigation
Authors: Calantone Roger J. , Tamer Cavusgil S. , Schmidt Jeffrey B. , Shin Geon‐Cheol 
Published: April 2004

Firms competing in foreign markets can choose to make no changes to the physical product and packaging, called a product standardization policy, which keeps costs low. The main drawback of such a policy is that the product might not satisfy customers. Conversely, firms may choose to modify, or to adapt, the physical characteristics or attributes of a product and its packaging to fit the needs and desires of consumers in different countries better, but this increases development, manufacturing, marketing, packaging, and distribution costs. Though product adaptation is a core aspect of customizing an export market offering, little research has investigated modifying the physical product and packaging. To be successful, an adapted product must add sufficient incremental revenue (through increased sales due to better satisfying customer needs and wants relative to competitive product offerings) such that the additional manufacturing and marketing costs that result from adapting the product are recovered.In this article, a model of the product adaptation process is developed. Using mail surveys, information is gathered from managers in 239 U.S. organizations and 302 South Korean organizations, all of which export products. The goal was to understand better the motivation of firms to adapt their products for export markets as well as the performance implications of adapting products. Furthermore, the model was tested in these two countries to determine if the model is robust and to uncover differences between the United States and South Korea.Using structural equation modeling to analyze the data, a positive association was found between the level of product adaptation and profitability at the project level. Second, U.S. firms appear to be more reactive when adapting products for export markets, doing so when laws and regulations in the export market mandate changes relative to the U.S. market. Conversely, South Korean firms appear to be more proactive and to adapt products even when not required by the governments of export markets. Third, greater international product adaptation is linked to a more responsive marketing organization with customer‐focused practices. Fourth, while a positive link was expected between business unit experience and the extent of international product adaptation, inconsistent results were found between the two country samples. For U.S. firms, it was found that greater experience in international business and product design capability is linked to a higher level of international product adaptation. For South Korean firms, however, a negative relationship was found. Greater international product adaptation occurred with less international business and product design experience. These findings are discussed, and areas for future research are noted.
Book Reviews
Authors: Smith Preston G. 
Published: April 2004

Books reviewed in this issue:

Code Name Ginger: The Story behind Segway and Dean Kamen's Quest to Invent a New World
Open Innovation: The New Imperative for Creating and Profiting from Technology

Editor's note: The former section, “Books received for possible review in a future issue,” has been replaced by a more dynamic list available to reviewers. If you are interested in reviewing books for JPIM, please contact Preston Smith at preston@NewProductDynamics.com.
Rv1818c‐encoded PE_PGRS protein of Mycobacterium tuberculosis is surface exposed and influences bacterial cell structure
Authors: Delogu Giovanni , Pusceddu Cinzia , Bua Alessandra , Fadda Giovanni , Brennan Michael J. , Zanetti Stefania 
Published: April 2004

SummaryIdentification of the novel PE multigene family was an unexpected finding of the genomic sequencing of Mycobacterium tuberculosis. Presently, the biological role of the PE and PE_PGRS proteins encoded by this unique family of mycobacterial genes remains unknown. In this report, a representative PE_PGRS gene (Rv1818c/PE_PGRS33) was selected to investigate the role of these proteins. Cell fractionation studies and fluorescence analysis of recombinant strains of Mycobacterium smegmatis and M. tuberculosis expressing green fluorescent protein (GFP)‐tagged proteins indicated that the Rv1818c gene product localized in the mycobacterial cell wall, mostly at the bacterial cell poles, where it is exposed to the extracellular milieu. Further analysis of this PE_PGRS protein showed that the PE domain is necessary for subcellular localization. In addition, the PGRS domain, but not PE, affects bacterial shape and colony morphology when Rv1818c is overexpressed in M. smegmatis and M. tuberculosis. Taken together, the results indicate that PE_PGRS and PE proteins can be associated with the mycobacterial cell wall and influence cellular structure as well as the formation of mycobacterial colonies. Regulated expression of PE genes could have implications for the survival and pathogenesis of mycobacteria within the human host and in other environmental niches.
Cell envelope components contributing to biofilm growth and survival of Pseudomonas putida in low‐water‐content habitats
Authors: Van De Mortel Martijn , Halverson Larry J. 
Published: April 2004

SummaryBacteria in terrestrial habitats frequently reside as biofilm communities on surfaces that are unsaturated, i.e. biofilms are covered in water films varying in thickness depending on the environmental conditions. Water availability in these habitats is influenced by the osmolarity of the water (solute stress) and by cellular dehydration imposed by matric stress, which increases as water content decreases. Unfortunately, we understand relatively little about the molecular mechanisms required for bacterial growth in low‐water‐content habitats. Here, we describe the use of mini‐Tn5‐′phoA to identify genes in Pseudomonas putida that are matric water stress controlled and to generate mutants defective in desiccation tolerance. We identified 20 genes that were induced by a matric stress but not by a thermodynamically equivalent solute stress, 11 genes were induced by both a matric and a solute stress, three genes were induced by a solute stress and three genes were repressed by a matric stress. Their patterns of expression were analysed in laboratory media, and their contribution to desiccation tolerance was evaluated. Twenty‐six genes were homologous to sequences present in the completed P. putida KT2440 genome sequence or plasmid pWWO sequence that are involved in protein fate, nutrient or solute acquisition, energy generation, motility, alginate biosynthesis or cell envelope structure, and the function of five could not be predicted from the sequence. Together, these genes and their importance to desiccation tolerance provide a view of the environment perceived by bacteria in low‐water‐content habitats, and suggest that the mechanisms for adaptation for growth in low‐water‐content habitats are different from those for growth in high‐osmolarity habitats.
A novel enzyme, citryl‐CoA lyase, catalysing the second step of the citrate cleavage reaction in Hydrogenobacter thermophilus TK‐6
Authors: Aoshima Miho , Ishii Masaharu , Igarashi Yasuo 
Published: April 2004

SummaryA novel enzyme catalysing citryl‐CoA cleavage to acetyl‐CoA and oxaloacetate was purified from Hydrogenobacter thermophilus TK‐6, and designated citryl‐CoA lyase (CCL). The citrate cleavage reaction in this organism proceeded by a unique set of two consecutive reactions: (i) citryl‐CoA formation by citryl‐CoA synthetase (CCS) and (ii) citryl‐CoA cleavage by CCL. Purified CCL gave a single 30 kDa band in SDS–PAGE and gel filtration chromatography indicated that the native state of the enzyme exists as a trimer (α3). Citryl‐CoA lyase showed low citrate synthase (CS) activity. Using an oligonucleotide probe, the corresponding gene was cloned and sequenced. The gene was expressed in Escherichia coli and recombinant CCL was also purified. The CCL protein sequence showed similarity to the C‐terminal regions of ATP citrate lyase (ACL) and CS sequences in the database. By further sequence comparisons, the phylogenetic relationship between CCS, CCL, ACL and CS was investigated.
The Aspergillus fumigatus transcriptional activator CpcA contributes significantly to the virulence of this fungal pathogen
Authors: Krappmann Sven , Bignell Elaine M. , Reichard Utz , Rogers Tom , Haynes Ken , Braus Gerhard H. 
Published: April 2004

SummaryWe have cloned and characterized the Aspergillus fumigatus cpcA gene encoding the transcriptional activator of the cross‐pathway control system of amino acid biosynthesis. cpcA encodes a functional orthologue of Saccharomyces cerevisiae Gcn4p. The coding sequence of the 2.2 kb transcript is preceded by two short upstream open reading frames, the larger one being well conserved among Aspergilli. Deletion strains in which either the coding sequence or the entire locus are replaced by a bifunctional dominant marker are impaired in their cross‐pathway control response upon amino acid starvation, as demonstrated by analyses of selected reporter genes and specific enzymatic activities. In a murine model of pulmonary aspergillosis, cpcAΔ strains display attenuated virulence. Pathogenicity is restored to wild‐type levels in strains with reconstitution of the genomic locus. Competitive mixed infection experiments additionally demonstrate that cpcAΔ strains are less able to survive in vivo than their wild‐type progenitor. Our data suggest that specific stress conditions are encountered by A. fumigatus within the mammalian host and that the fungal cross‐pathway control system plays a significant role in pulmonary aspergillosis.
Lipid‐induced filamentous growth in Ustilago maydis
Authors: Klose Jana , De Sá Mário Moniz , Kronstad James W. 
Published: April 2004

SummaryThe phytopathogenic fungus Ustilago maydis is obligately dependent on infection of maize to complete the sexual phase of its life cycle. Mating interactions between haploid, budding cells establish an infectious filamentous cell type that invades the host, induces large tumours and eventually forms large masses of black spores. The ability to switch from budding to filamentous growth is therefore critical for infection and completion of the life cycle, although the signals that influence the transition have not been identified from the host or the environment. We have found that growth in the presence of lipids promotes a filamentous phenotype that resembles the infectious cell type found in planta. In addition, the ability of the fungus to respond to lipids is dependent on both the cAMP signalling pathway and a Ras/MAPK pathway; these pathways are known to regulate mating, filamentous growth and pathogenesis in U. maydis. Overall, these results lead us to hypothesize that lipids may represent one of the signals that promote and maintain the filamentous growth of the fungus in the host environment.
Roles of CmpR, a LysR family transcriptional regulator, in acclimation of the cyanobacterium Synechococcus sp. strain PCC 7942 to low‐CO2 and high‐light conditions
Authors: Takahashi Yukari , Yamaguchi Osamu , Omata Tatsuo 
Published: April 2004

SummaryThe cmp operon of Synechococcus sp. strain PCC 7942, encoding a high‐affinity bicarbonate transporter, is induced under low CO2 conditions by a LysR family protein CmpR. CmpR was found to be required also for induction of the operon by transfer of the cells from low‐light to high‐light conditions, indicating involvement of a common mechanism in the high‐light‐ and low‐CO2‐responsive regulation. Expression of the high‐light inducible genes psbAII and psbAIII, on the other hand, was found to be induced also by low‐CO2 conditions. A single promoter was responsible for the high‐light and low‐CO2 induction of each of psbAII and psbAIII, suggesting involvement of a common regulatory mechanism in the light and CO2 responses of the psbA genes. CmpR was, however, not required for the induction of psbAII and psbAIII, indicating the presence of multiple mechanisms for induction of genes under high‐light and low‐CO2 conditions. The CmpR‐deficient mutant nevertheless showed lower levels of the psbAII and psbAIII transcripts than the wild‐type strain under all the light and CO2 conditions examined. Gel shift assays showed that CmpR binds to the enhancer elements of psbAII and psbAIII, through specific interaction with a sequence signature conforming to the binding motif of similar LysR family proteins. These findings showed that CmpR acts as a trans‐acting factor that enhances transcription of the photosystem II genes involved in acclimation to high light, revealing a complex network of gene regulation in the cyanobacterium.
Identification of the Entner–Doudoroff pathway in an antibiotic‐producing actinomycete species
Authors: Gunnarsson Nina , Mortensen Uffe H. , Sosio Margherita , Nielsen Jens 
Published: April 2004

SummaryThe metabolic network of the central carbon metabolism represents the backbone of cellular metabolism and provides the precursors and cofactors required for synthesis of secondary metabolites. It is therefore pivotal to map the operating metabolic network in the central carbon metabolism in order to design metabolic engineering strategies towards construction of more efficient producers of specific metabolites. In this context, methods that allow rapid and reliable mapping of the central carbon metabolism are valuable. In the present study, a 13C labelling‐based method was used to identify the primary metabolic pathways of the poorly characterized antibiotic‐producing actinomycete Nonomuraea sp. ATCC 39727. Surprisingly, it was found that Nonomuraea sp. ATCC 39272 predominantly metabolizes glucose via the Entner–Doudoroff (ED) pathway. This represents the first time that the ED pathway has been recognized as the main catabolic pathway in an actinomycete. The Nonomuraea genes encoding the key enzymes of the ED pathway were subsequently identified, sequenced and functionally described.
Population trends and damage patterns of Hypsipyla grandella (Lepidoptera: Pyralidae) in a mahogany stand, in Turrialba, Costa Rica
Authors: Taveras Rosina , Hilje Luko , Hanson Paul , Mexzón Ramón , Carballo Manuel , Navarro Carlos 
Published: April 2004

Abstract  1 Population trends of Hypsipyla grandella and their relationship with abiotic (humidity, precipitation and temperature) and biotic factors (availability of mahogany shoots and natural mortality agents), as well as damage patterns, were studied for 16 months in Turrialba, Costa Rica.2 Hypsipyla grandella was active in the field all year round, and its population density was influenced by temperature, availability of new shoots and natural mortality agents.3 It was possible to predict four population peaks, which appeared approximately every 1881 degree‐days.4 Even though H. grandella larvae mainly attack shoots, they also fed on the bark of the bole, especially when green shoots were scarce.5 Four parasitoid species were recorded (Bracon c. chontalensis, Brachymeria c. conica, Apanteles sp. and Dolichogenidea sp.) but their impact on H. grandella abundance was negligible.
Characterization of western corn rootworm (Coleoptera: Chrysomelidae) population dynamics in relation to landscape attributes
Authors: Beckler Amber A. , French B. Wade , Chandler Laurence D. 
Published: April 2004

Abstract  1 The western corn rootworm (WCR), Diabrotica virgifera virgifera Leconte (Coleoptera: Chrysomelidae), creates economic and environmental concerns in the Corn Belt region of the U.S.A. To supplement the population control tactics of the Areawide Pest Management Program in Brookings, South Dakota, Geographical Information Systems (GIS) were used to examine the spatial relationships from 1997 to 2001 between WCR population dynamics, habitat structure, soil texture and elevation.2 Using the inverse distance weighted interpolation technique, WCR population density maps were created from georeferenced emergence and post‐emergence traps placed in maize fields. For each year, these maps were overlaid with vegetation, soil and elevation maps to search for quantitative relationships.3 Through visual interpretation and correlation analysis, shifts in landscape structure, such as size, number and arrangement of patches, were shown to associate with WCR population abundance and distribution in varying degrees. Contingency analysis showed that WCR population abundance is associated with soil texture and elevation.4 An understanding of the interactions between WCR population dynamics and landscape variables provides information to pest managers, and this can be used to identify patterns in the landscape that promote high insect population density patches to improve pest management strategies.
‘Beetle banks’ as refuges for beneficial arthropods in farmland: long‐term changes in predator communities and habitat
Authors: MacLeod A. , Wratten S. D. , Sotherton N. W. , Thomas M. B. 
Published: April 2004

Abstract  1 Significant differences in the overwintering densities of predatory carabid and staphylinid beetles and spiders occurred on an ‘island’ grassy bank habitat composed of blocks of Agrostis stolonifera, Dactylis glomerata, Holcus lanatus and Lolium perenne, within and between winters during a 7‐year study.2 Densities of the predators over the last three winters of the study were greater in the bank than in the boundary of the field in which the bank was situated.3 Succession occurred in plots of L. perenne, with D. glomerata fully replacing this species. Plots of D. glomerata and H. lanatus remained virtually mono‐specific.4 Over the period of study, the beetle bank maintained its role in providing overwintering habitat for polyphagous predators and carabid diversity has increased since the bank was first established. Beetle banks were therefore shown to contribute to conservation biodiversity in an agroecosystem.
Immunomodulation confers herbicide resistance in plants
Authors: Almquist Kurt C. , Niu Yongqing , McLean Michael D. , Mena Frank L. , Yau Kerrm Y. F. , Brown Kirk , Brandle Jim E. , Hall J. Christopher 
Published: April 2004

SummaryIn order to create a novel mechanism for herbicide resistance in plants, we expressed a single‐chain antibody fragment (scFv) in tobacco with specific affinity to the auxinic herbicide picloram. Transgenic tobacco plants and seedlings expressing this scFv against picloram were protected from its effect in a dose‐dependent manner. This is the first successful use of an antibody to confer in vivo resistance to a low molecular weight xenobiotic (i.e. < 1000 Da). Our results suggest the possibility for a generic antibody‐based approach to create crops resistant to low molecular weight xenobiotics for subsequent use in the bioremediation of contaminated soils, crop protection and as novel selectable markers.
Conformational analysis of hepatitis B surface antigen fusions in an Agrobacterium‐mediated transient expression system
Authors: Huang Zhong , Mason Hugh S. 
Published: April 2004

SummaryVaccine antigens have been successfully produced in transgenic plants for oral immunization. Recently, a fusion strategy has been adopted to produce multicomponent vaccines and to target antigens to mucosal sites for enhanced oral immunogenicity. However, antigen fusions may not be folded correctly due to steric hindrance and may thus lose their potency. Here, we describe an Agrobacterium‐mediated transient assay that provides enough antigen‐expressing material at 2 days post‐transfection to evaluate antigen conformation. Using the hepatitis B surface antigen (HBsAg) as a model antigen and the green fluorescent protein (GFP) as a model fusion partner, we showed that transiently expressed HBsAg and an HBsAg fusion with GFP at the N‐terminus (GFP:HBsAg), but not the HBsAg fusion with GFP at the C‐terminus (HBsAg:GFP), formed the ‘a’ determinant and virus‐like particles (VLPs), similar to yeast‐derived vaccine HBsAg. Thus, it is feasible to modify the HBsAg with an N‐terminal fusion of up to 239 amino acids without altering its major antigenic properties. Our results also demonstrate that the Agrobacterium‐mediated transient expression system can be used to evaluate the conformation of plant‐based vaccines or other pharmaceutical proteins in a high‐throughput manner.
Urea standard Kt/Vurea for assessing dialysis treatment adequacy
Authors: Leypoldt John K 
Published: April 2004

AbstractUrea standard Kt/Vurea (stdKt/Vurea) has been proposed as a dose measure to assess the adequacy of dialysis treatments of arbitrary length and frequency. It is based on two fundamental assumptions: 1) that clinical outcomes for hemodialysis and peritoneal dialysis patients are equivalent and 2) that the equivalency of such clinical outcomes is achieved when the mean predialysis blood urea nitrogen or urea concentration is identical for both therapies. The relationships among urea stdKt/Vurea, equilibrated Kt/Vurea, and single‐pool Kt/Vurea are reviewed, and the assumptions required for the validity of urea stdKt/Vurea as a universal dose measure to describe dialysis treatment adequacy are discussed. It is proposed that urea stdKt/Vurea is a dose measure for both water‐soluble and protein‐bound toxin clearances; therefore, this parameter may be a practical dose measure for assessing the adequacy of dialysis during treatments of arbitrary length and frequency.