bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of human population size in raising bird and mammal threat among nations
Authors: McKinney Michael L. 
Published: July 2002

AbstractIt is commonly held that species loss is linked to human population size but there are surprisingly few quantitative studies that measure the strength and nature of this linkage. In a study of about 150 nations, a highly significant positive relationship (P << 0.01) was found between population size and threat levels of birds and mammals. For continental nations, log population explains 16‐33% of the variation in threat level among nations. The pattern of the continental population‐threat correlation indicates that per capita human impacts are initially very high and asymptotically diminish with increasing population size. No population‐threat correlation was found for island nations, since human impacts are apparently so catastrophic that human population size is largely irrelevant. Surprisingly, for both islands and continents, area does not affect the level of threat after human population size is accounted for. Thus, even on continents the harmful impacts of humans, for a given population size, are evidently so profound that no amount of added area provides compensatory refugia for native species. Major regional differences in levels of threat are shown, with nations in Asia and the Middle East having generally higher proportions of threatened species than nations in Africa. The causes of these differences are only partly related to population size. Other factors not related to population size are that Asian nations tend to have much higher rates of mammal over‐harvesting and Middle Eastern nations tend to have statistically lower percentages of area set aside as preserves. Threat proportions are correlated between birds and mammals among nations implying that one group may be a proxy indicator of impacts on the other. The slope of this relationship indicates that mammals suffer more losses during initial human impacts but proportions of threatened birds increase more rapidly than mammals as human impacts become more widespread.
Identification of Human Epidermal Differentiation Complex (EDC)-Encoded Genes by Subtractive Hybridization of Entire YACs to a Gridded Keratinocyte cDNA Library
Authors: Marenholz Ingo , Zirra Maja , Fischer David F. , Backendorf Claude , Ziegler Andreas , Mischke Dietmar 
Published: July 2002

The epidermal differentiation complex (EDC) comprises a large number of genes that are of crucial importance for the maturation of the human epidermis. So far, 27 genes of 3 related families encoding structural as well as regulatory proteins have been mapped within a 2-Mb region on chromosome 1q21. Here we report on the identification of 10 additional EDC genes by a powerful subtractive hybridization method using entire YACs (950_e_2 and 986_e_10) to screen a gridded human keratinocyte cDNA library. Localization of the detected cDNA clones has been established on a long-range restriction map covering more than 5 Mb of this genomic region. The genes encode cytoskeletal tropomyosin TM30nm (TPM3), HS1-binding protein Hax-1 (HAX1), RNA-specific adenosine deaminase (ADAR1), the 34/67-kD laminin receptor (LAMRL6), and the 26S proteasome subunit p31 (PSMD8L), as well as five hitherto uncharacterized proteins (NICE-1, NICE-2, NICE-3, NICE-4,andNICE-5). The nucleotide sequences and putative ORFs of the EDC genes identified here revealed no homology with any of the established EDC gene families. Whereas database searches revealed thatNICE-3, NICE-4,andNICE-5were expressed in many tissues, no EST or gene-specific sequence was found forNICE-2.Expression ofNICE-1was up-regulated in differentiated keratinocytes, pointing to its relevance for the terminal differentiation of the epidermis. The newly identified EDC genes are likely to provide further insights into epidermal differentiation and they are potential candidates to be involved in skin diseases and carcinogenesis that are associated with this region of chromosome 1. Moreover, the extended integrated map of the EDC, including the polymorphic sequence tag site (STS) markers D1S1664, D1S2346, and D1S305, will serve as a valuable tool for linkage analyses.[The sequence data reported in this paper have been submitted to EMBL under the accession nos.AJ243659–AJ243673.]
A Genetic Linkage Map of the Apicomplexan Protozoan Parasite Eimeria tenella
Authors: Shirley Martin W. , Harvey Dora A. 
Published: July 2002

Apicomplexan protozoan parasites have complex life cycles that involve phases of asexual and sexual reproduction. Some genera have intermediate insect hosts, for example, Plasmodium spp. (the cause of malaria), but related genera such as Eimeria spp. (causative agents of coccidiosis in poultry) have a direct life cycle occurring in only a single host. Mechanisms that regulate the life cycles of apicomplexan parasites are unknown, but the intracellular growth of avian Eimeria spp. is easily shortened by serial selection for the first parasites to complete the transition from asexual to sexual reproduction (to yield so-called precocious lines). To investigate the genetic basis of such an abbreviated life cycle, we have used the species E. tenella and analyzed the inheritance of 443 polymorphic DNA markers in 22 recombinant cloned progeny derived from a cross between parents that had selectable phenotypes of precocious development or resistance to an anticoccidial drug. The markers were placed in 16 linkage groups (which defined 12 chromosomes) and a further 57 unlinked groups. Two linkage groups showed an association (P = .0105) with the traits of precocious development or drug-resistance and were mapped to chromosome 2 (ca 1.2 Mbp) and chromosome 1 (ca 1.0 Mbp), respectively. The map provides a framework for further studies on the identification of genetic loci implicated in the regulation of the life cycle of an important protozoan parasite and a representative of a major taxonomic group.[A table with the segregation data is available as an online supplement at http://www.genome.org.]
Genomic Anatomy of a Premier Major Histocompatibility Complex Paralogous Region on Chromosome 1q21–q22
Authors: Shiina Takashi , Ando Asako , Suto Yumiko , Kasai Fumio , Shigenari Atsuko , Takishima Nobusada , Kikkawa Eri , Iwata Kyoko , Kuwano Yuko , Kitamura Yuka , Matsuzawa Yumiko , Sano Kazumi , Nogami Masahiro , Kawata Hisako , Li Suyun , Fukuzumi Yasuhito , Yamazaki Masaaki , Tashiro Hiroyuki , Tamiya Gen , Kohda Atsushi , Okumura Katsuzumi , Ikemura Toshimichi , Soeda Eiichi , Mizuki Nobuhisa , Kimura Minoru , Bahram Seiamak , Inoko Hidetoshi 
Published: July 2002

Human chromosomes 1q21–q25, 6p21.3–22.2, 9q33–q34, and 19p13.1–p13.4 carry clusters of paralogous loci, to date best defined by the flagship 6p MHC region. They have presumably been created by two rounds of large-scale genomic duplications around the time of vertebrate emergence. Phylogenetically, the 1q21–25 region seems most closely related to the 6p21.3 MHC region, as it is only the MHC paralogous region that includes bona fideMHCclass I genes, theCD1andMR1loci. Here, to clarify the genomic structure of this model MHC paralogous region as well as to gain insight into the evolutionary dynamics of the entire quadriplication process, a detailed analysis of a critical 1.7 megabase (Mb) region was performed. To this end, a composite, deep, YAC, BAC, and PAC contig encompassing all fiveCD1genes and linking the centromeric +P5 locus to the telomericKRTC7locus was constructed. Within this contig a 1.1-Mb BAC and PAC core segment joiningCD1DtoFCER1Awas fully sequenced and thoroughly analyzed. This led to the mapping of a total of 41 genes (12 expressed genes, 12 possibly expressed genes, and 17 pseudogenes), among which 31 were novel. The latter include 20 olfactory receptor (OR) genes, 9 of which are potentially expressed. Importantly,CD1, SPTA1, OR, andFCERIAbelong to multigene families, which have paralogues in the other three regions. Furthermore, it is noteworthy that 12 of the 13 expressed genes in the 1q21–q22 region around theCD1loci are immunologically relevant. In addition toCD1A-E,these includeSPTA1, MNDA, IFI-16, AIM2, BL1A, FYandFCERIA. This functional convergence of structurally unrelated genes is reminiscent of the 6p MHC region, and perhaps represents the emergence of yet another antigen presentation gene cluster, in this case dedicated to lipid/glycolipid antigens rather than antigen-derived peptides.[The nucleotide sequence data reported in this paper have been submitted to the DDBJ, EMBL, and GenBank databases under accession nos.AB045357–AB045365.]
Purification and Characterization of Pyrophosphate-Dependent Phosphofructokinase from Phosphate-Starved Brassica nigra Suspension Cells
Authors: Theodorou M. E. , Plaxton W. C. 
Published: July 2002

Abstract
Previously, we reported that inorganic phosphate (Pi) deprivation of Brassica nigra suspension cells or seedlings leads to a progressive increase in the α-:β-subunit ratio of the inorganic pyrophosphate (PPi)-dependent phosphofructokinase (PFP) and that this coincides with a marked enhancement in the enzyme's activity and sensitivity to its allosteric activator, fructose-2,6-bisphosphate (Fru-2,6-P2). To further investigate the effect of Pi nutrition on B. nigra PFP, the enzyme was purified and characterized from Pi-starved B. nigra suspension cell cultures. Polyacrylamide gel electrophoresis, immunoblot, and gel-filtration analyses of the final preparation indicated that this enzyme exists as a heterooctamer of approximately 500 kD and is composed of a 1:1 ratio of immunologically distinct α- (66 kD) and [beta] (60 kD) subunits. The enzyme's α- subunit was susceptible to partial proteolysis during purification, but this was prevented by the presence of chymostatin and leupeptin. In the presence and absence of 5 [mu]M Fru-2,6-P2, the forward activity of PFP displayed pH optima of pH 6.8 and 7.6, respectively. Maximal activation of the forward and reverse reactions by Fru-2,6-P2 occurred at pH 6.8. The potent inhibition of the forward activity by Pi (concentration of inhibitor producing 50% inhibition of enzyme activity [I50] = 1.3 mM) was attributed to a marked Pi-dependent reduction in Fru-2,6-P2 binding. The reverse reaction was substrate-inhibited by Pi (I50 = 13 mM) and product-inhibited by PPi (I50 = 0.9 mM). The kinetic data are consistent with the hypothesis that PFP may function to bypass the ATP-dependent PFP in Pi-starved B. nigra. The importance of the Pi nutritional status to the regulation and predicted physiological function of PFP is emphasized.
Differential Expression and Properties of Starch Branching Enzyme Isoforms in Developing Wheat Endosperm
Authors: Morell M. K. , Blennow A. , Kosar-Hashemi B. , Samuel M. S. 
Published: July 2002

Abstract
Three forms of starch branching enzyme (BE) from developing hexaploid wheat (Triticum aestivum) endosperm have been partially purified and characterized. Immunological cross-reactivities indicate that two forms (WBE-IAD, 88 kD, and WBE-IB, 87 kD) are related to the maize BE I class and that WBE-II (88 kD) is related to maize BE II. Comparison of the N-terminal sequences from WBE-IAD and WBE-II with maize and rice BEs confirms these relationships. Evidence is presented from the analysis of nullisomic-tetrasomic wheat lines demonstrating that WBE-IB is located on chromosome 7B and that the WBE-IAD fraction contains polypeptides that are encoded on chromosomes 7A and 7D. The wheat endosperm BE classes are differentially expressed during endosperm development. WBE-II is expressed at a constant level throughout mid and late endosperm development. In contrast, WBE-IAD and WBE-IB are preferentially expressed in late endosperm development. Differences are also observed in the kinetic characteristics of the enzymes. The WBE-I isoforms have a 2- to 5-fold higher affinity for amylose than does WBE-II, and the WBE-I isoforms are activated up to 5-fold by phosphorylated intermediates and inorganic phosphate, whereas WBE-II is activated only 50%. The potential implications of this activation of BE I for starch biosynthesis are discussed.
Growth and Photosynthesis under High and Low Irradiance of Arabidopsis thaliana Antisense Mutants with Reduced Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase Content
Authors: Eckardt N. A. , Snyder G. W. , Portis Jr A. R. , Ogren W. L. 
Published: July 2002

Abstract
Photosynthesis and growth to maturity of antisense ribulose-1,5- bisphosphate carboxylase/oxygenase (Rubisco) activase Arabidopsis thaliana with reduced concentrations of activase relative to wild-type (Wt) plants were measured under low (200 [mu]mol m-2 s-1) and high (600 [mu]mol m-2 s-1) photosynthetic photon flux density growing conditions. Both growth and photosynthesis were significantly reduced in an Arabidopsis clone (R100) with 30 to 40% Wt activase, an effect that was more pronounced in high light. The aboveground biomass of the antisense clone R100 reached 80% of Wt under low light and 65% of Wt under high light. Decreased growth in the antisense plants was attributed to reduced relative rates of growth and leaf area expansion early in development; all plants attained similar values of relative rates of growth and leaf elongation by 21 d after planting. Reductions in photosynthesis were attributed to decreased Rubisco activation in the antisense plants. Rubisco constituted about 40% of total soluble protein in both Wt and clone R100 under both light regimes. Activase content was 5% and 1.4% of total soluble protein in Wt and clone R100, respectively, and also was unaffected by growth irradiance. The stoichiometry of Rubisco to activase was estimated at 20 Rubisco active sites per activase tetramer in Wt Arabidopsis and 60 to 80 in the transgenic clone R100. We conclude that Wt Arabidopsis does not contain Rubisco activase in great excess of the amount required for optimal growth.
Abundant Accumulation of the Calcium-Binding Molecular Chaperone Calreticulin in Specific Floral Tissues of Arabidopsis thaliana
Authors: Nelson D. E. , Glaunsinger B. , Bohnert H. J. 
Published: July 2002

Abstract
Calreticulin (CRT) is a calcium-binding protein in the endoplasmic reticulum (ER) with an established role as a molecular chaperone. An additional function in signal transduction, specifically in calcium distribution, is suggested but not proven. We have analyzed the expression pattern of Arabidopsis thaliana CRTs for a comparison with these proposed roles. Three CRT genes were expressed, with identities of the encoded proteins ranging from 54 to 86%. Protein motifs with established functions found in CRTs of other species were conserved. CRT was found in all of the cells in low amounts, whereas three distinct floral tissues showed abundant expression: secreting nectaries, ovules early in development, and a set of subepidermal cells near the abaxial surface of the anther. Localization in the developing endosperm, which is characterized by high protein synthesis rates, can be reconciled with a specific chaperone function. Equally, nectar production and secretion, a developmental stage marked by abundant ER, may require abundant CRT to accommodate the traffic of secretory proteins through the ER. Localization of CRT in the anthers, which are degenerating at the time of maximum expression of CRT, cannot easily be reconciled with a chaperone function but may indicate a role for CRT in anther maturation or dehiscence.
Adenylosuccinate Synthetase from Maize (Purification, Properties, and Mechanism of Inhibition by 5[prime]-Phosphohydantocidin)
Authors: Walters E. W. , Lee S. F. , Niderman T. , Bernasconi P. , Subramanian M. V. , Siehl D. L. 
Published: July 2002

Abstract
Adenylosuccinate synthetase (AdSS) is the site of action of hydantocidin, a potent microbial phytotoxin. A kinetic analysis of the mode of inhibition of a plant adenylosuccinate synthetase by the active metabolite 5[prime]-phosphohydantocidin (5[prime]-PH) was the objective of the present study. AdSS was purified 5800-fold from maize (Zea mays), to our knowledge the first purification of the enzyme from a plant source. N-terminal sequencing established the cleavage site of the previously published deduced sequence of the initial transcript. The subunit molecular mass was determined to be 48 kD and the isoelectric point was at pH 6.1. Values of the Michaelis constant for the three substrates IMP, GTP, and aspartate were 21, 16, and 335 [mu]M, respectively. Inhibition of AdSS by 5[prime]-PH was measurably time-dependent. The trace of the inactivation curve could not be altered by preincubating the enzyme and inhibitor in the absence of substrates but could be linearized by preincubating the enzyme with inhibitor, aspartate, GTP (or GDP), and inorganic phosphate. Inhibition of AdSS by 5[prime]-PH was competitive with IMP, with an apparent Ki of 22 nM. Apparently, 5[prime]-PH inhibits the enzyme by binding to the IMP site and forming a tight, dead-end complex.
Partial Characterization of Glutathione S-Transferases from Wheat (Triticum spp.) and Purification of a Safener-Induced Glutathione S-Transferase from Triticum tauschii
Authors: Riechers D. E. , Irzyk G. P. , Jones S. S. , Fuerst E. P. 
Published: July 2002

Abstract
Hexaploid wheat (Triticum aestivum L.) has very low constitutive glutathione S-transferase (GST) activity when assayed with the chloroacetamide herbicide dimethenamid as a substrate, which may account for its low tolerance to dimethenamid in the field. Treatment of seeds with the herbicide safener fluxofenim increased the total GST activity extracted from T. aestivum shoots 9-fold when assayed with dimethenamid as a substrate, but had no effect on glutathione levels. Total GST activity in crude protein extracts from T. aestivum, Triticum durum, and Triticum tauschii was separated into several component GST activities by anion-exchange fast-protein liquid chromatography. These activities (isozymes) differed with respect to their activities toward dimethenamid or 1-chloro-2,4-dinitrobenzene as substrates and in their levels of induction by safener treatment. A safener-induced GST isozyme was subsequently purified by anion-exchange and affinity chromatography from etiolated shoots of the diploid wheat species T. tauschii (a progenitor of hexaploid wheat) treated with the herbicide safener cloquintocet-mexyl. The isozyme bound to a dimethenamid-affinity column and had a subunit molecular mass of 26 kD based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified enzyme (designated GST TSI-1) was recognized by an antiserum raised against a mixture of maize (Zea mays) GSTs. Amino acid sequences obtained from protease-digested GST TSI-1 had significant homology with the safener-inducible maize GST V and two auxin-regulated tobacco (Nicotiana tabacum) GST isozymes.
Epigenetic Transcriptional Silencing and 5-Azacytidine-Mediated Reactivation of a Complex Transgene in Rice
Authors: Kumpatla S. P. , Teng W. , Buchholz W. G. , Hall T. C. 
Published: July 2002

Abstract
Despite a growing number of reports indicating non-Mendelian inheritance of transgene expression in monocots, no detailed description of the structure and stability of the transgene exists for transformants generated by direct DNA-transfer techniques, making the cause for these observations difficult to determine. In this paper we describe the complex organization of Btt cryIIIA and bar transgenes in rice (Oryza sativa L.) that displayed aberrant segregation in R1 progeny. Silencing rather than rearrangement of the bar gene was implicated because the herbicide-sensitive R1 plants had a DNA hybridization profile identical to that of the resistant R0 parent and R1 siblings. Genomic DNA analysis revealed substantial methylation of the Ubi1/bar sequences in silenced plants and, to a lesser degree, in herbicide-resistant plants, suggesting that the transgene locus was potentiated for silencing. Nuclease protection and nuclear run-on assays confirmed that silencing was due to transcriptional inactivation. Treatment of R2 progeny of silenced plants with 5-azacytidine resulted in demethylation of the Ubi1 promoter and reactivation of bar gene expression, demonstrating a functional relationship for methylation in gene silencing. These findings indicate that methylation-based silencing may be frequent in cereals transformed by direct DNA protocols that insert multiple, often rearranged sequences.
A Dynamin-Like Protein, ADL1, Is Present in Membranes as a High-Molecular-Mass Complex in Arabidopsis thaliana
Authors: Park J. M. , Kang S. G. , Pih K. T. , Jang H. J. , Piao H. L. , Yoon H. W. , Cho M. J. , Hwang I. 
Published: July 2002

Abstract
Dynamin, a GTP-binding protein, is involved in endocytosis in animal cells. We found that a dynamin-like protein, ADL1, is present in multiple forms in Arabidopsis leaf tissue. Subcellular fractionation experiments, together with gel-filtration and nondenaturing-gel electrophoresis revealed that most of ADL1 is present as a high-molecular-mass complex of 400 to 600 kD in the membrane or pellet fraction, whereas ADL1 is present in the soluble fraction as a monomer. The subcellular distribution of ADL1 is affected by various agents such as Ca2+, cyclosporin A, GTP, and ATP. Ca2+ increases the amount of ADL1 present in the membrane fraction, whereas cyclosporin A inhibits the membrane association. Furthermore, Ca2+ and GTP change the migration pattern of ADL1 in nondenaturing polyacrylamide gels, indicating that these chemicals influence either the complex formation and/or the conformation of the ADL1 complex. Our results demonstrate that ADL1 has characteristics that are similar to Dynamin I, which is found in animal cells. Therefore, it is possible that ADL1 is also involved in biological processes that require vesicle formation.
The Characterization of Plasma Membrane-Bound Tubulin of Cauliflower Using Triton X-114 Fractionation
Authors: Sonesson A. , Berglund M. , Staxen I. , Widell S. 
Published: July 2002

Abstract
The cortical microtubules determine how cellulose microfibrils are deposited in the plant cell wall and are thus important for the control of cell expansion. To understand how microtubules can control microfibril deposition, the components that link the microtubules to the plasma membrane (PM) of plant cells must be isolated. To obtain information on the properties of the tubulin-membrane associations, cauliflower (Brassica oleracea) PM was subjected to Triton X-114 fractionation, and the distribution of α-- and β-tubulin was analyzed using immunoblotting. Approximately one-half of the PM-associated tubulin was solubilized by Triton X-114 and 10 to 15% of both α-- and β-tubulin was recovered in the detergent phase (indicative of hydrophobic properties) and 30 to 40% was recovered in the aqueous phase. The hydrophobic tubulin could be released from the membrane by high pH extraction with preserved hydrophobicity. A large part of the PM-associated tubulin was found in the Triton-insoluble fraction. When this insoluble material was extracted a second time, a substantial amount of hydrophobic tubulin was released if the salt concentration was increased, suggesting that the hydrophobic tubulin was linked to a high-salt-sensitive protein aggregate that probably includes other components of the cytoskeleton. The hydrophobicity of a fraction of PM-associated tubulin could reflect a direct or indirect interaction of this tubulin with the lipid bilayer or with an integral membrane protein and may represent the anchoring of the cortical microtubules to the PM, a key element in the regulation of cell expansion.