bluuebunny/crossref_metadata_2025 huggingface dataset:
Creation of monosomic derivatives of human cultured cell lines
Authors: Clarke Duncan J. , Giménez-Abián Juan F. , Tönnies Holger , Neitzel Heidemarie , Sperling Karl , Downes C. Stephen , Johnson Robert T.
Published: July 2002

Monosomic mammalian cell lines would be ideal for studying gene dosage effects, including gene imprinting, and for systematic isolation of recessive somatic mutants parallel to the invaluable mutants derived from haploid yeast. But autosomal monosomies are lethal in early development; although monosomies appear in tumors, deriving cell lines from these tumors is difficult and cannot provide several syngenic lines. We have developed a strategy for generating stable monosomic human cells, based on random autosomal integration of thegptplasmid, partial inhibition of DNA topoisomerase II during mitosis to promote chromatid nondisjunction, and selection against retention ofgpt. These are likely to be valuable as a source of otherwise inaccessible mutants. The strategy can also be used to generate partial mammalian monosomies, which are desirable as a source of information on recessive genes and gene imprinting.
Farnesyltransferase inhibitors induce dramatic morphological changes of KNRK cells that are blocked by microtubule interfering agents
Authors: Suzuki Nobutaka , Del Villar Keith , Tamanoi Fuyuhiko
Published: July 2002

Farnesyltransferase inhibitors (FTIs) exhibit the remarkable ability to inhibit transformed phenotypes of a variety of human cancer cell lines and to block the growth of cancer cells in a number of animal model systems. In this paper, we report that the addition of FTI to
v-K-ras-
transformed NRK cells (KNRK) results in dramatic morphological changes. Within 24 h after the addition of FTI, the round morphology of KNRK cells was changed to an elongated (flattened and spread out) morphology resembling those of untransformed NRK cells. No morphological effects were seen when similar concentrations of FTI were added to NRK cells. Phalloidin staining showed that FTI treatment did not restore the disrupted actin cytoskeleton in KNRK cells. In contrast, FTI addition resulted in the appearance of extensive microtubule networks in KNRK cells. The addition of a low concentration (1.2 nM) of vincristine or vinblastine, agents that interfere with microtubule dynamics, blocked the FTI-induced morphological changes in KNRK cells. In contrast, cytochalasin B, which interferes with actin polymerization, did not block the morphological changes. The FTI-induced morphological changes were associated with a decrease in the percentage of cells in S-phase, and the addition of 1.2 nM vincristine did not have additional effects on cell cycle progression. A higher concentration (12 nM) of vincristine caused synergistic effect with FTI to enrich dramatically KNRK cells in G
2
/M phase. These results suggest that FTI affects cell morphology and that microtubule dynamics are involved in these processes.
Attractin (DPPT-L), a member of the CUB family of cell adhesion and guidance proteins, is secreted by activated human T lymphocytes and modulates immune cell interactions
Authors: Duke-Cohan Jonathan S. , Gu Jijie , McLaughlin Daniel F. , Xu Yuhui , Freeman Gordon J. , Schlossman Stuart F.
Published: July 2002

Attractin is a normal human serum glycoprotein of 175 kDa that is rapidly expressed on activated T cells and released extracellularly after 48–72 hr. We have cloned attractin and find that, as in its natural serum form, it mediates the spreading of monocytes that become the focus for the clustering of nonproliferating T lymphocytes. There are two mRNA species with hematopoietic tissue-specific expression that code for a 134-kDa protein with a putative serine protease catalytic serine, four EGF-like motifs, a CUB domain, a C type lectin domain, and a domain homologous with the ligand-binding region of the common γ cytokine chain. Except for the latter two domains, the overall structure shares high homology with theCaenorhabditis elegansF33C8.1 protein, suggesting that attractin has evolved new domains and functions in parallel with the development of cell-mediated immunity.
The orientation of the AP-1 heterodimer on DNA strongly affects transcriptional potency
Authors: Chytil Milan , Peterson Blake R. , Erlanson Daniel A. , Verdine Gregory L.
Published: July 2002

Activation of gene transcription in eukaryotes requires the cooperative assembly of an initiation complex containing many protein subunits. The necessity that these components contact each other and the promoter/enhancer in defined ways suggests that their spatial arrangement might influence the activation response. Indeed, growing evidence indicates that DNA architecture can profoundly affect transcriptional potency. Much less is known about the influence of protein architecture on transcriptional activation. Here, we examine the architectural dependence of activator function through the analysis of matched pairs of AP-1•DNA complexes differing only in their orientation. Mutation of a critical Arg residue in the basic-leucine zipper domain of either Fos or Jun yielded single point-mutant heterodimers that bind DNA in a single defined orientation, as determined directly by native chemical ligation/affinity cleavage; by contrast, the corresponding wild-type protein binds DNA as a roughly equal mixture of two isomeric orientations, which are related by subunit interchange. The stereochemistry of the point-mutant heterodimers could be switched by inversion of a C•G base pair in the center of the AP-1 site, thus providing access to both fixed orientational isomers. Yeast reporter gene assays consistently revealed that one orientational isomer activates transcription at least 10-fold more strongly than the other. These results suggest that protein architecture, especially the spatial relationship of the activation domain to the promoter, can exert a powerful influence on activator potency.
Bax interacts with the permeability transition pore to induce permeability transition and cytochromecrelease in isolated mitochondria
Authors: Narita Masashi , Shimizu Shigeomi , Ito Toshinori , Chittenden Thomas , Lutz Robert J. , Matsuda Hikaru , Tsujimoto Yoshihide
Published: July 2002

Cytochromecrelease and the mitochondrial permeability transition (PT), including loss of the transmembrane potential (Δψ), play an important role in apoptosis. Using isolated mitochondria, we found that recombinant Bax and Bak, proapoptotic members of the Bcl-2 family, induced mitochondrial Δψ loss, swelling, and cytochromecrelease. All of these changes were dependent on Ca2+and were prevented by cyclosporin A (CsA) and bongkrekic acid, both of which close the PT pores (megachannels), indicating that Bax- and Bak-induced mitochondrial changes were mediated through the opening of these pores. Bax-induced mitochondrial changes were inhibited by recombinant Bcl-xLand transgene-derived Bcl-2, antiapoptotic members of the Bcl-2 family, as well as by oligomycin, suggesting a possible regulatory effect of F0F1-ATPase on Bax-induced mitochondrial changes. Proapoptotic Bax- and Bak-BH3 (Bcl-2 homology) peptides, but not a mutant BH3 peptide nor a mutant Bak lacking BH3, induced the mitochondrial changes, indicating an essential role of the BH3 region. A coimmunoprecipitation study revealed that Bax and Bak interacted with the voltage-dependent anion channel, which is a component of PT pores. Taken together, these findings suggest that proapoptotic Bcl-2 family proteins, including Bax and Bak, induce the mitochondrial PT and cytochromecrelease by interacting with the PT pores.
Differences in the level of expression of class I major histocompatibility complex proteins on thymic epithelial and dendritic cells influence the decision of immature thymocytes between positive and negative selection
Authors: Delaney Joseph R. , Sykulev Yuri , Eisen Herman N. , Tonegawa Susumu
Published: July 2002

Both positive and negative selection of immature T cells rely on engagement of their antigen-specific receptors (TCR) by peptide in association with proteins encoded in the major histocompatibility complex (MHC) protein. The decision made between these two outcomes seems to be determined by the number of TCR engaged by peptide–MHC complexes. It has been unclear how such a mechanism can be reconciled with evidence that positive and negative selection occur in different thymic compartments and are mediated by different antigen-presenting cells (APCs). In this study we demonstrate that the level of class I MHC protein is 10-fold higher on thymic dendritic cells, which mediate the negative selection of immature T cells, than on thymic epithelial cells, which mediate for positive selection. We also demonstrate that as little as a 3-fold increase in the level of a particular cognate peptide–MHC ligand is sufficient to result in negative rather than positive selection. The results suggest that quantitative differences in the level of expression of class I MHC proteins on thymic epithelial and dendritic cells contribute to the opposing roles these cells play in forming the repertoire of mature class I MHC restricted (CD8+) T cells.
Formation of coding joints in V(D)J recombination-inducible severe combined immune deficient pre-B cell lines
Authors: Chang Yung , Brown Matthew L.
Published: July 2002

Characterization of the severe combined immune deficient (scid) defect in the recombination process has provided many insights into the underlying mechanisms of variable (diversity) joining recombination. By using recombination-inducible scid pre-B cell lines transformed with the temperature-sensitive Abelson-murine leukemia virus, we show that large quantities of recombination intermediates can be generated, and their resolution can be followed during further cell culture. In this study, we demonstrate that the ability of these scid pre-B cell lines to resolve coding ends depends on the cell culture temperature. At the nonpermissive temperature of 39°C, scid pre-B cell lines fail to form coding joints and contain mostly unresolved hairpin-coding ends. Once the cell culture is returned to the permissive temperature of 33°C, these same cells make a significant amount of coding joints concomitant with the disappearance of hairpin-coding ends. Thus, the scid cells are capable of resolving coding ends under certain culture conditions. However, the majority of the recovered coding joints contains extensive deletions, indicating that the temperature-dependent resolution of coding ends is still scid-like. Our results suggest that the inability of scid cells to promptly nick hairpin-coding ends may lead to aberrant joining in these cells.
The importin/karyopherin Kap114 mediates the nuclear import of TATA-binding protein
Authors: Morehouse Heather , Buratowski Robin M. , Silver Pamela A. , Buratowski Stephen
Published: July 2002

Two high copy suppressors of temperature-sensitive TATA-binding protein (TBP) mutants were isolated. One suppressor was
TIF51A
, which encodes eukaryotic translation initiation factor 5A. The other high copy suppressor,
YGL241W
, also known as
KAP114
, is one of 14 importin/karyopherin proteins in yeast. These proteins mediate the transport of specific macromolecules into and out of the nucleus. Cells lacking Kap114 partially mislocalize TBP to the cytoplasm. Kap114 binds TBP
in vitro
, and binding is disrupted in the presence of GTPγS. Therefore, Kap114 is an importer of TBP into the nucleus, but alternative import pathways must also exist.
Effect of cellular filamentation on adventurous and social gliding motility of
Myxococcus xanthus
Authors: Sun Hong , Yang Zhaomin , Shi Wenyuan
Published: July 2002

Filamentous bacterial cells often provide biological information that is not readily evident in normal-size cells. In this study, the effect of cellular filamentation on gliding motility of
Myxococcus xanthus
, a Gram-negative social bacterium, was investigated. Elongation of the cell body had different effects on
a
dventurous and
s
ocial motility of
M. xanthus.
The rate of A-motility was insensitive to cell-body elongation whereas the rate of S-motility was reduced dramatically as the cell body got longer, indicating that these two motility systems work in different ways. The study also showed that filamentous wild-type cells glide smoothly with relatively straight, long cell bodies. However, filamentous cells of certain social motility mutants showed zigzag, tangled cell bodies on a solid surface, apparently a result of a lack of coordination between different fragments within the filaments. Further genetic and biochemical analyses indicated that the uncoordinated movements of these mutant filaments were correlated with the absence of cell surface fibril materials, indicating a possible new function for fibrils.
Interaction between water and polar groups of the helix backbone: An important determinant of helix propensities
Authors: Luo Peizhi , Baldwin Robert L.
Published: July 2002

We report an enthalpic factor involved in determining helix propensities of nonpolar amino acids. Thermal unfolding curves of the five 13-residue peptides, Ac-KA
4
XA
4
KGY-NH
2
(X = Ala, Leu, Ile, Val, Gly), have been measured by using CD in water/trifluoroethanol (TFE) mixtures. The peptide helix contents show that the rank order of helix propensities changes with temperature: although Ala has the highest helix propensity at 0°C in all TFE concentrations, it is lower than Leu, Ile, and Val at 50°C in 20% TFE. This change is attributed to shielding by nonpolar side chains of the interaction between water and polar groups in the helix backbone for the following reasons. (
i
) Helix content is directly related to helix propensity for these designed peptides because side-chain–side-chain interactions are absent. (
ii
) The change in rank order with temperature is enthalpic in origin: in water, the apparent enthalpy of helix formation calculated from the thermal unfolding curves varies widely among the five peptides and has the same rank order as the helix propensities at 0°C. The rank order does not result from burial of nonpolar surface area because the calculated heat capacity change (ΔCp) on helix formation is opposite in sign from the expected ΔCp. (
iii
) A nonpolar side chain can exclude water from interacting with helix polar groups, according to calculations of water-accessible surface area, and the polar interaction between water and peptide polar groups is entirely enthalpic, as shown by amide transfer data.
Configurations for a proof of principle stellarator experiment
Authors: Garabedian P. R.
Published: July 2002

One of the serious limitations of tokamaks as reactors is the occurrence of disruptions. Stellarators designed by advanced computational methods provide an attractive alternative for a major experiment in magnetic fusion research. Configurations with approximate two-dimensional magnetic symmetry have been found with high β limits and good transport. Specifications are given for a compact stellarator with three field periods and 18 moderately twisted modular coils that has equilibrium with robust flux surfaces, a deep magnetic well assuring favorable stability, and adequate confinement of hot particles at reactor conditions. Fast computer codes with sufficient accuracy to resolve the mathematical problems of equilibrium, stability and transport that arise in the more complicated geometry of the stellarator have produced this breakthrough. The mathematical analysis of the methods used is presented.
Peer Acceptance and Friendship Patterns among Italian Schoolchildren within a Cross-cultural Perspective
Authors: Attili Grazia , Vermigli Patrizia , Schneider Barry H.
Published: July 2002

Sociometric choice nominations, as well as peer nominations for friendship, aggression, isolation, and prosocial behaviour, were administered to middle class Italian primary school youngsters. Socially rejected children were found to be more aggressive, more withdrawn, and less prosocial than members of the other social status categories, and to have fewer friends. The proportions of subjects in the neglected and controversial categories were very low, although the proportions of rejected and popular children were similar to those found in North American studies. These findings are discussed within the framework of cross-cultural differences in children’s peer relations.
In Pursuit of the Just Wage: A Comparison of Reformation and Counter-Reformation Economic Thought
Authors: Noell Edd S.
Published: July 2002

Students of economic thought have long associated with the fifteenth and sixteenth centuries the spread of attitudes in Europe more tolerant of market processes. New economic attitudes appear in a variety of literary forms during the fifteenth century (McGovern 1970). As compared to the pronouncements of a number of Patristic figures, relatively greater tolerance of commerce is expressed by medieval theologians. In fact, recent scholarly efforts suggest that by the late thirteenth century, suspicions of economic activity remained, but Scholastic thinkers increasingly recognized the importance of an impersonal market process in everyday life and sought to find ways to understand it in light of their concern with natural order (Kaye 1998a). While condemning avarice, Scholastic writers such as San Antonino of Florence and San Bernadino of Sienna explicitly endorsed trade as legitimate when practiced for the common good and when associated with modest profit (Origo 1962; De Roover 1967). Recognition of this movement in thought, especially as it applied the concerns of economic justice to trade in commodities, is explicit in the literature of preclassical economics. But until recently, less attention has been paid to more specific developments in scholastic thinking on justice in the labor market.
Ethyl glucuronide—a biological marker for recent alcohol consumption
Authors: Seidl Stephan , Wurst Friedrich M. , Alt Andreas
Published: July 2002

Ethyl glucuronide (EtG) is a non‐volatile, water‐soluble metabolite of ethanol, with a high storage stability. It can be detected in body fluids, tissues, sweat and hair for an extended time period after the elimination of ethanol from the body. EtG closes the gap between short‐term markers for alcohol consumption such as ethanol or methanol and long‐term markers for alcohol misuse such as GGT, MCV and CDT. Due to its specific time‐frame of detection and its high sensitivity and specificity, EtG is a promising marker for alcohol consumption and for relapse control that enables the therapist to intervene at an early stage of relapsing behaviour. The aim of this review is to give an overview of analytical techniques for the detection of EtG, its clinical use and remaining questions.
Concurrent chronic administration of a CCKB antagonist can decrease tolerance to the ataxic effects of ethanol
Authors: WILSON J. , WOODRUFF G. N. , LITTLE H. J.
Published: July 2002

The effects of chronic administration of a CCKB antagonist, CAM1028, were examined on the development of tolerance to ethanol and the appearance of withdrawal signs. Ethanol was given chronically by liquid diet, and none of the dose schedules of CAM1028 affected the amount of ethanol taken in during the chronic treatment. Brain ethanol concentrations were not altered by the administration of CAM1028.The ataxic effects of ethanol were tested on a rotorod, 3 hours after cessation of the ethanol administration, and the last injections of CAM1028 were given 8 hours before withdrawal from the ethanol treatment. When administered at 0.03, 0.1 or 0.3 mg/kg, CAM1028 decreased the extent of tolerance development. Higher doses, 1 and 3 mg/kg, did not alter the tolerance development. Chronic administration of CAM1028 had a small effect in protecting against the effects of ethanol withdrawal that, in contrast to the effects on the tolerance, was seen only at the highest dose, 10 mg/kg, of CAM1028.
A Novel Dynamin-like Protein Associates with Cytoplasmic Vesicles and Tubules of the Endoplasmic Reticulum in Mammalian Cells
Authors: Yoon Yisang , Pitts Kelly R. , Dahan Sophie , McNiven Mark A.
Published: July 2002

Abstract. Dynamins are 100-kilodalton guanosine triphosphatases that participate in the formation of nascent vesicles during endocytosis. Here, we have tested if novel dynamin-like proteins are expressed in mammalian cells to support vesicle trafficking processes at cytoplasmic sites distinct from the plasma membrane. Immunological and molecular biological methods were used to isolate a cDNA clone encoding an 80-kilodalton novel dynamin-like protein, DLP1, that shares up to 42% homology with other dynamin-related proteins. DLP1 is expressed in all tissues examined and contains two alternatively spliced regions that are differentially expressed in a tissue-specific manner. DLP1 is enriched in subcellular membrane fractions of cytoplasmic vesicles and endoplasmic reticulum. Morphological studies of DLP1 in cultured cells using either a specific antibody or an expressed green fluorescent protein (GFP)- DLP1 fusion protein revealed that DLP1 associates with punctate cytoplasmic vesicles that do not colocalize with conventional dynamin, clathrin, or endocytic ligands. Remarkably, DLP1-positive structures coalign with microtubules and, most strikingly, with endoplasmic reticulum tubules as verified by double labeling with antibodies to calnexin and Rab1 as well as by immunoelectron microscopy. These observations provide the first evidence that a novel dynamin-like protein is expressed in mammalian cells where it associates with a secretory, rather than endocytic membrane compartment.
Evidence That Atypical Protein Kinase C-λ and Atypical Protein Kinase C-ζ Participate in Ras-mediated Reorganization of the F-actin Cytoskeleton
Authors: Überall Florian , Hellbert Karina , Kampfer Sonja , Maly Karl , Villunger Andreas , Spitaler Martin , Mwanjewe James , Baier-Bitterlich Gabriele , Baier Gottfried , Grunicke Hans H.
Published: July 2002

Expression of transforming Ha-Ras L61 in NIH3T3 cells causes profound morphological alterations which include a disassembly of actin stress fibers. The Ras-induced dissolution of actin stress fibers is blocked by the specific PKC inhibitor GF109203X at concentrations which inhibit the activity of the atypical aPKC isotypes λ and ζ, whereas lower concentrations of the inhibitor which block conventional and novel PKC isotypes are ineffective. Coexpression of transforming Ha-Ras L61 with kinase-defective, dominant-negative (DN) mutants of aPKC-λ and aPKC-ζ, as well as antisense constructs encoding RNA-directed against isotype-specific 5′ sequences of the corresponding mRNA, abrogates the Ha-Ras–induced reorganization of the actin cytoskeleton. Expression of a kinase-defective, DN mutant of cPKC-α was unable to counteract Ras with regard to the dissolution of actin stress fibers. Transfection of cells with constructs encoding constitutively active (CA) mutants of atypical aPKC-λ and aPKC-ζ lead to a disassembly of stress fibers independent of oncogenic Ha-Ras. Coexpression of (DN) Rac-1 N17 and addition of the phosphatidylinositol 3′-kinase (PI3K) inhibitors wortmannin and LY294002 are in agreement with a tentative model suggesting that, in the signaling pathway from Ha-Ras to the cytoskeleton aPKC-λ acts upstream of PI3K and Rac-1, whereas aPKC-ζ functions downstream of PI3K and Rac-1.

This model is supported by studies demonstrating that cotransfection with plasmids encoding L61Ras and either aPKC-λ or aPKC-ζ results in a stimulation of the kinase activity of both enzymes. Furthermore, the Ras-mediated activation of PKC-ζ was abrogated by coexpression of DN Rac-1 N17.
Differential Function of N-Cadherin and Cadherin-7 in the Control of Embryonic Cell Motility
Authors: Dufour Sylvie , Beauvais-Jouneau Alice , Delouvée Annie , Thiery Jean Paul
Published: July 2002

Similar amounts of N-cadherin and cadherin-7, the prototypes of type I and type II cadherin, induced cell-cell adhesion in murine sarcoma 180 transfectants, Ncad-1 and cad7-29, respectively. However, in the initial phase of aggregation, Ncad-1 cells aggregated more rapidly than cad7-29 cells. Isolated Ncad-1 and cad7-29 cells adhered and spread in a similar manner on fibronectin (FN), whereas aggregated cad7-29 cells were more motile and dispersed than aggregated Ncad-1 cells. cad7-29 cells established transient contacts with their neighbors which were stabilized if FN-cell interactions were perturbed. In contrast, Ncad-1 cells remained in close contact when they migrated on FN. Both β-catenin and cadherin were more rapidly down-regulated in cad7-29 than in Ncad-1 cells treated with cycloheximide, suggesting a higher turnover rate for cadherin-7–mediated cell-cell contacts than for those mediated by N-cadherin. The extent of FN-dependent focal adhesion kinase phosphorylation was much lower if the cells had initiated N-cadherin–mediated rather than cadherin-7–mediated cell adhesion before plating. On grafting into the embryo, Ncad-1 cells did not migrate and remained at or close to the graft site, even after 48 h, whereas grafted cad7-29 cells dispersed efficiently into embryonic structures. Thus, the adhesive phenotype of cadherin-7–expressing cells is regulated by the nature of the extracellular matrix environment which also controls the migratory behavior of the cells. In addition, adhesions mediated by different cadherins differentially regulate FN-dependent signaling. The transient contacts specifically observed in cadherin-7–expressing cells may also be important in the control of cell motility.
Replication of Tobacco Mosaic Virus on Endoplasmic Reticulum and Role of the Cytoskeleton and Virus Movement Protein in Intracellular Distribution of Viral RNA
Authors: Más Paloma , Beachy Roger N.
Published: July 2002

Little is known about the mechanisms of intracellular targeting of viral nucleic acids within infected cells. We used in situ hybridization to visualize the distribution of tobacco mosaic virus (TMV) viral RNA (vRNA) in infected tobacco protoplasts. Immunostaining of the ER lumenal binding protein (BiP) concurrent with in situ hybridization revealed that vRNA colocalized with the ER, including perinuclear ER. At midstages of infection, vRNA accumulated in large irregular bodies associated with cytoplasmic filaments while at late stages, vRNA was dispersed throughout the cytoplasm and was associated with hair-like protrusions from the plasma membrane containing ER. TMV movement protein (MP) and replicase colocalized with vRNA, suggesting that viral replication and translation occur in the same subcellular sites. Immunostaining with tubulin provided evidence of colocalization of vRNA with microtubules, while disruption of the cytoskeleton with pharmacological agents produced severe changes in vRNA localization. Mutants of TMV lacking functional MP accumulated vRNA, but the distribution of vRNA was different from that observed in wild-type infection. MP was not required for association of vRNA with perinuclear ER, but was required for the formation of the large irregular bodies and association of vRNA with the hair-like protrusions.
Role of the Pi3k Regulatory Subunit in the Control of Actin Organization and Cell Migration
Authors: Jiménez Concepción , Portela Rosario Armas , Mellado Mario , Rodríguez-Frade Jose Miguel , Collard John , Serrano Antonio , Martínez-A Carlos , Avila Jesus , Carrera Ana C.
Published: July 2002

Cell migration represents an important cellular response that utilizes cytoskeletal reorganization as its driving force. Here, we describe a new signaling cascade linking PDGF receptor stimulation to actin rearrangements and cell migration. We demonstrate that PDGF activates Cdc42 and its downstream effector N-WASP to mediate filopodia formation, actin stress fiber disassembly, and a reduction in focal adhesion complexes. Induction of the Cdc42 pathway is independent of phosphoinositide 3-kinase (PI3K) enzymatic activity, but it is dependent on the p85α regulatory subunit of PI3K. Finally, data are provided showing that activation of this pathway is required for PDGF-induced cell migration on collagen. These observations show the essential role of the PI3K regulatory subunit p85α in controlling PDGF receptor–induced cytoskeletal changes and cell migration, illustrating a novel signaling pathway that links receptor stimulation at the cell membrane with actin dynamics.
Immunoglobulin E–dependent Active Fatal Anaphylaxis in Mast Cell–deficient Mice
Authors: Choi Il Hwan , Shin Young Min , Park Jae Seung , Lee Moo Sam , Han Eue Hyeog , Chai Ok Hee , Im Shun Young , Ha Tai  You , Lee Hern-Ku
Published: July 2002

Mast cells have long been believed to be the central effector cells in the development of immunoglobulin (Ig)E-dependent anaphylaxis. In this study, we investigated the role of mast cells in IgE-dependent hapten-induced active fatal anaphylaxis using mast cell–deficient WBB6F1- W/Wv (W/Wv) and congenic normal (+/+) mice. Although a 5-min delay in shock signs and death were observed in W/Wv mice, 100% fatal reactions to penicillin V (Pen V) occurred in both +/+ and W/Wv mice. Administration of monoclonal anti–IL-4 antibody completely prevented the fatal reactions, and the effect of anti–IL-4 was associated with its suppressive activity on Pen V–specific serum levels of IgE, but not IgG. The platelet-activating factor (PAF) antagonist, BN 50739, completely prevented the fatal reactions in both strains of mice. Our kinetic study revealed, in contrast to no elevation of plasma histamine level in W/Wv mice, high levels of PAF in the circulation after challenge in both +/+ and W/Wv mice, albeit to a lesser degree in the latter case. These data indicate that cells other than mast cells are sufficient to induce an IgE-dependent active fatal anaphylaxis by elaborating PAF, which is the critical mediator for fatal murine anaphylaxis.
Invariant Chain Controls H2-M Proteolysis in Mouse Splenocytes and Dendritic Cells
Authors: Pierre Philippe , Shachar Idit , Matza Didi , Gatti Evelina , Flavell Richard A. , Mellman Ira
Published: July 2002

The association of invariant (Ii) chain with major histocompatibility complex (MHC) class II dimers is required for proper antigen presentation to T cells by antigen-presenting cells. Mice lacking Ii chain have severe abnormalities in class II transport, T cell selection, and B cell maturation. We demonstrate here that H2-M, which is required for efficient class II antigenic peptide loading, is unexpectedly downregulated in splenocytes and mature dendritic cells (DCs) from Ii−/− mice. Downregulation reflects an increased rate of degradation in Ii−/− cells. Degradation apparently occurs within lysosomes, as it is prevented by cysteine protease inhibitors such as E64, but not by the proteasome inhibitor lactacystin. Thus, Ii chain may act as a lysosomal protease inhibitor in B cells and DCs, with its deletion contributing indirectly to the loss of H2-M.
Immunoglobulin β Signaling Regulates Locus Accessibility for Ordered Immunoglobulin Gene Rearrangements
Authors: Maki Kazushige , Nagata Kisaburo , Kitamura Fujiko , Takemori Toshitada , Karasuyama Hajime
Published: July 2002

The antigen receptor gene rearrangement at a given locus is tightly regulated with respect to cell lineage and developmental stage by an ill-defined mechanism. To study the possible role of precursor B cell antigen receptor (pre-BCR) signaling in the regulation of the ordered immunoglobulin (Ig) gene rearrangement during B cell differentiation, a newly developed system using μ heavy (H) chain membrane exon (μm)-deficient mice was employed. In this system, the antibody-mediated cross-linking of Igβ on developmentally arrested progenitor B (pro-B) cells mimicked pre-BCR signaling to induce early B cell differentiation in vivo. Analyses with ligation-mediated polymerase chain reaction revealed that the Igβ cross-linking induced the redirection of Ig gene rearrangements, namely, the suppression of ongoing rearrangements at the H chain locus and the activation of rearrangements at the light (L) chain locus. Upon the cross-linking, the κL chain germline transcription was found to be upregulated whereas the VH germline transcription was promptly downregulated. Notably, this alteration of the accessibility at the H and L chain loci was detected even before the induction of cellular differentiation became detectable by the change of surface phenotype. Thus, the pre-BCR signaling through Igβ appears to regulate the ordered Ig gene rearrangement by altering the Ig locus accessibility.
An Endoplasmic Reticulum Retention Function for the Cytoplasmic Tail of the Human Pre–T Cell Receptor (Tcr) α Chain
Authors: Carrasco Yolanda R. , Ramiro Almudena R. , Trigueros César , de Yébenes Virginia G. , García-Peydró Marina , Toribio María L.
Published: July 2002

The pre-T cell receptor (TCR), which consists of a TCR-β chain paired with pre–TCR-α (pTα) and associated with CD3/ζ components, is a critical regulator of T cell development. For unknown reasons, extremely low pre-TCR levels reach the plasma membrane of pre-T cells. By transfecting chimeric TCR-α–pTα proteins into pre-T and mature T cell lines, we show here that the low surface expression of the human pre-TCR is pTα chain dependent. Particularly, the cytoplasmic domain of pTα is sufficient to reduce surface expression of a conventional TCR-α/β to pre-TCR expression levels. Such reduced expression cannot be attributed to qualitative differences in the biochemical composition of the CD3/ζ modules associated with pre-TCR and TCR surface complexes. Rather, evidence is provided that the pTα cytoplasmic tail also causes a reduced surface expression of individual membrane molecules such as CD25 and CD4, which are shown to be retained in the endoplasmic reticulum (ER). Native pTα is also observed to be predominantly ER localized. Finally, sequential truncations along the pTα cytoplasmic domain revealed that removal of the COOH-terminal 48 residues is sufficient to release a CD4-pTα chimera from ER retention, and to restore native CD4 surface expression levels. As such a truncation in pTα also correlates with enhanced pre-TCR expression, the observed pTα ER retention function may contribute to the regulation of surface pre-TCR expression on pre-T cells.
Nonconforming finite element approximation of crystalline microstructure
Authors: Li Bo , Luskin Mitchell
Published: July 2002

We consider a class of nonconforming finite element approximations of a simply laminated microstructure which minimizes the nonconvex variational problem for the deformation of martensitic crystals which can undergo either an orthorhombic to monoclinic (double well) or a cubic to tetragonal (triple well) transformation. We first establish a series of error bounds in terms of elastic energies for the

L
2

L^2

approximation of derivatives of the deformation in the direction tangential to parallel layers of the laminate, for the

L
2

L^2

approximation of the deformation, for the weak approximation of the deformation gradient, for the approximation of volume fractions of deformation gradients, and for the approximation of nonlinear integrals of the deformation gradient. We then use these bounds to give corresponding convergence rates for quasi-optimal finite element approximations.
Combinatorics and spherical functions on the Heisenberg group
Authors: Benson Chal , Ratcliff Gail
Published: July 2002

LetVVbe a finite dimensional Hermitian vector space andKKbe a compact Lie subgroup ofU(V)U(V)for which the representation ofKKonC[V]\mathbb {C}[V]is multiplicity free. One obtains a canonical basis{pα}\{p_\alpha \}for the spaceC[VR]K\mathbb {C}[V_{\mathbb {R}}]^KofKK-invariant polynomials onVRV_{\mathbb {R}}and also a basis{qα}\{q_\alpha \}via orthogonalization of thepαp_\alpha’s. The polynomialpαp_\alphayields the homogeneous component of highest degree inqαq_\alpha. The coefficients that express theqαq_\alpha’s in terms of thepβp_\beta’s are thegeneralized binomial coefficientsof Z. Yan. We present some new combinatorial identities that involve these coefficients. These have applications to analysis on Heisenberg groups. Indeed, the polynomialsqαq_\alphacompletely determine the generic bounded spherical functions for a Gelfand pair obtained from the action ofKKon a Heisenberg groupH=V×RH=V\times \mathbb {R}.
Actin Dependence of Polarized Receptor Recycling in Madin-Darby Canine Kidney Cell Endosomes
Authors: Sheff David R. , Kroschewski Ruth , Mellman Ira
Published: July 2002

Mammalian epithelial cell plasma membrane domains are separated by junctional complexes supported by actin. The extent to which actin acts elsewhere to maintain cell polarity remains poorly understood. Using latrunculin B (Lat B) to depolymerize actin filaments, several basolateral plasma membrane proteins were found to lose their polarized distribution. This loss of polarity did not reflect lateral diffusion through junctional complexes because a low-density lipoprotein receptor mutant lacking a functional endocytosis signal remained basolateral after Lat B treatment. Furthermore, Lat B treatment did not facilitate membrane diffusion across the tight junction as observed with ethylenediaminetetraacetic acid or dimethyl sulfoxide treatment. Detailed analysis of transferrin recycling confirmed Lat B depolarized recycling of transferrin from endosomes to the basolateral surface. Kinetic analysis suggested sorting was compromised at both basolateral early endosomes and perinuclear recycling endosomes. Despite loss of function, these two endosome populations remained distinct from each other and from early endosomes labeled by apically internalized ligand. Furthermore, apical and basolateral early endosomes were functionally distinct populations that directed traffic to a single common recycling endosomal compartment even after Lat B treatment. Thus, filamentous actin may help to guide receptor traffic from endosomes to the basolateral plasma membrane.
Women in the Underground Business of Eighteenth-Century Lyon
Authors: Hafter Daryl M.
Published: July 2002

Women's work has often been portrayed as unskilled and lowpaid labor done for the benefit of others. But the role of female enterprise in eighteenth-century Lyon presents another dimension: non-guild women workers who secured control of raw materials, labor,and distribution networks within an underground economy. In an unusual twist of fortune,a small but significant number of women in the silk,hat-making, and button-making industries turned to their own benefit the advantages customarily provided to male entrepreneurs. These women workers stole materials from the guild workshops in which they were employed. Having learned the technology needed to manufacture silk,hats,and buttons from guild masters,they set up clandestine workshops and trained their own workers. Even in the face of official guild protest,their low prices and competent workmanship induced some masters to buy their goods to reduce the cost of their own products. The women used a set of capitalist practices to survive in a difficult transitional era of superficially regulated norms.
Acceleration of phosphatidylcholine synthesis and breakdown by inhibitors of mitochondrial function in neuronal cells: a model of the membrane defect of Alzheimer's disease
Authors: Farber Steven A. , Slack Barbara E. , Blusztajn Jan Krzysztof
Published: July 2002

Brain cells in Alzheimer's disease (AD) exhibit a membrane defect characterized by accelerated phospholipid turnover. The mechanism responsible for this defect remains unknown. Recent studies indicate that impairment of mitochondrial function is frequently observed in AD and may be responsible for certain aspects of its pathophysiology. We show that when PC12 cells are exposed to inhibitors of mitochondrial bioenergetics, the turnover of their major membrane phospholipid, phosphatidylcholine, is accelerated, producing a pattern of metabolic changes that mimics that observed in brains of AD patients. Abnormalities of mitochondrial function may therefore underlie the membrane defect in AD.—Farber, S. A., Slack, B. E., Blusztajn, J. K. Acceleration of phosphatidylcholine synthesis and breakdown by inhibitors of mitochondrial function in neuronal cells: a model of the membrane defect of Alzheimer's disease. FASEB J. 14, 2198–2206 (2000)
What can monotremes tell us about brain evolution?
Authors: Krubitzer Leah
Published: July 2002

The present review outlines studies of electrophsyiological organization, cortical architecture and thalmocortical and corticocortical connections in monotremes. Results of these studies indicate that the neocortex of monotremes has many features in common with other mammals. In particular, monotremes have at least two, and in some instances three, sensory fields for each modality, as well as regions of bimodal cortex. The internal organization of cortical fields and thalamocortical projection patterns are also similar to those described for other mammals. However, unlike most mammals investigated, the monotreme neocortex has cortical connections between primary sensory fields, such as SI and VI.

The results of this analysis lead us to pose the question of what monotremes can tell us about brain evolution. Monotremes alone can tell us very little about the evolutionary process, or the construction of complex neural networks, as an individual species represents only a single example of what the process is capable of generating. Perhaps a better question is: what can comparative studies tell us about brain evolution? Monotreme brains, when compared with the brains of other animals, can provide some answers to questions about the evolution of the neocortex, the historical precedence of some features over others, and how basic circuits were modified in different lineages. This, in turn, allows us to appreciate how normal circuits function, and to pose very specific questions regarding the development of the neocortex.
Analysis of ancient DNA from a prehistoric Amerindian cemetery
Authors: Stone Anne C. , Stoneking Mark
Published: July 2002

The Norris Farms No. 36 cemetery in central Illinois has been the subject of considerable archaeological and genetic research. Both mitochondrial DNA (mtDNA) and nuclear DNA have been examined in this 700–year–old population. DNA preservation at the site was good, with about 70% of the samples producing mtDNA results and approximately 15% yielding nuclear DNA data. All four of the major Amerindian mtDNA haplogroups were found, in addition to a fifth haplogroup. Sequences of the first hypervariable region of the mtDNA control region revealed a high level of diversity in the Norris Farms population and confirmed that the fifth haplogroup associates with Mongolian sequences and hence is probably authentic. Other than a possible reduction in the number of rare mtDNA lineages in many populations, it does not appear as if European contact significantly altered patterns of Amerindian mtDNA variation, despite the large decrease in population size that occurred. For nuclear DNA analysis, a novel method for DNA–based sex identification that uses nucleotide differences between the X and Y copies of the amelogenin gene was developed and applied successfully in approximately 20 individuals. Despite the well–known problems of poor DNA preservation and the ever–present possibility of contamination with modern DNA, genetic analysis of the Norris Farms No. 36 population demonstrates that ancient DNA can be a fruitful source of new insights into prehistoric populations.
Tobacco mosaic virus and the virescence of biotechnology
Authors: Turpen Thomas H.
Published: July 2002

There is a growing realization that a modern combination of molecular biology and agriculture will provide a photosynthetic basis for the biosynthesis of an increasing variety of complex and valuable molecules. This ‘greening’ of biotechnology may impact on the global environment in many beneficial ways, but will perhaps have its most significant impact on human health. In the past decade, the capacity to use plants as an expanded source of therapeutics has grown through the accelerated development of effective viral transfection vectors for gene transfer to cultivated crops. Recombinant vectors based on tobacco mosaic virus (TMV) and other members of the Tobamovirus genus are now used to transfect commercially meaningful quantities of plant biomass cultivated in enclosed greenhouses and multiacre fields. Viral RNA promoters are effectively manipulated for the synthesis of recombinant messenger RNAs in whole plants. Chimeric plant virus and virus–like particles are designed for peptide production and display from recombinant structural protein–gene fusions. Gene functions are assessed and modified by either virus–mediated expression or cytosolic inhibition of expression at the RNA level. Recombinant virus populations, propagated by inoculating plants with infectious RNA transcripts or recombinant virions, have proved to be genetically stable over product–manufacturing cycles. Large volumes of highly purified protein products isolated from transfected foliage conform reproducibly to the specifications required for well–characterized biologics. In some cases, they exceed the specific activities of molecules purified from alternative recombinant and native sources. The resulting products are then formulated according to the developing national regulatory guidelines appropriate for agriculture–based manufacturing. Each of these innovations was first realized by researchers using clones of tobamovirus genes and recombinant genomes. This progress is founded on the heritage of a century of fundamental TMV research.
Light-adaptive role of nitric oxide in the outer retina of lower vertebrates: a brief review
Authors: Djamgoz Mustafa B. A. , Sekaran Sumathi , Angotzi A. Rita , Haamedi Sakineh , Vallerga Silvana , Hirano Joe , Yamada Masahiro
Published: July 2002

The role of nitric oxide (NO) as a novel neurochemical mechanism controlling light adaptation of the outer retina is discussed by considering mainly published results. The emphasis is on the retinae of fishes and amphibia, but some data from the mammalian (rabbit) retinae have also been included for completeness. In the fish retina, application of NO donors in the dark caused light–adaptive photomechanical movements of cones. The normal effect of light adaptation in inducing cone contractions was suppressed by pretreatment of retinae with an NO scavenger. NO donors modulated horizontal cell activity by uncoupling the cells' lateral gap junctional interconnections and enhancing negative feedback to cones, again consistent with a light–adaptive role of NO. Direct evidence for light adaptation–induced release of NO has been obtained in fish (carp) and rabbit retinae. The results strongly suggest that control of retinal light adaptation is under multiple neurochemical control, with NO and dopamine having an interactive role.