bluuebunny/crossref_metadata_2025 huggingface dataset:
Requirement for the Yeast Gene
LON
in Intramitochondrial Proteolysis and Maintenance of Respiration
Authors: Suzuki Carolyn K. , Suda Kitaru , Wang Nan , Schatz Gottfried
Published: October 2006

The role of protein degradation in mitochondrial homeostasis was explored by cloning of a gene from
Saccharomyces cerevisiae
that encodes a protein resembling the adenosine triphosphate (ATP)-dependent bacterial protease Lon. The predicted yeast protein has a typical mitochondrial matrix-targeting sequence at its amino terminus. Yeast cells lacking a functional
LON
gene contained a nonfunctional mitochondrial genome, were respiratory-deficient, and lacked an ATP-dependent proteolytic activity present in the mitochondria of
Lon
+
cells.
Lon
-
cells were also impaired in their ability to catalyze the energy-dependent degradation of several mitochondrial matrix proteins and they accumulated electron-dense inclusions in their mitochondrial matrix.
Differential Complementation of Bcr-Abl Point Mutants with c-Myc
Authors: Afar Daniel E. H. , Goga Andrei , McLaughlin Jami , Witte Owen N. , Sawyers Charles L.
Published: October 2006

A complementation strategy was developed to define the signaling pathways activated by the Bcr-Abl tyrosine kinase. Transformation inactive point mutants of Bcr-Abl were tested for complementation with c-Myc. Single point mutations in the Src-homology 2 (SH2) domain, the major tyrosine autophosphorylation site of the kinase domain, and the Grb-2 binding site in the Bcr region impaired the transformation of fibroblasts by Bcr-Abl. Hyperexpression of c-Myc efficiently restored transformation activity only to the Bcr-Abl SH2 mutant. These data support a model in which Bcr-Abl activates at least two independent pathways for transformation. This strategy may be useful for discerning signaling pathways activated by other oncogenes.
A Dual Embryonic Origin for Vertebrate Mechanoreceptors
Authors: Collazo Andres , Fraser Scott E. , Mabee Paula M.
Published: October 2006

Neuromasts, the mechanoreceptors of the lateral line system of fishes and aquatic amphibians, have previously been thought to develop exclusively from embryonic epidermal placodes. Use of fate mapping techniques shows that neuromasts of the head and body of zebrafish, Siamese fighting fish, and
Xenopus
are also derived from neural crest. Neural crest migrates away from the neural tube in developing vertebrates to form much of the peripheral nervous system, pigment cells, and skeletal elements of the head. The data presented here demonstrate that neuromasts are derived from both neural crest and epidermal placodes.
A Cell Cycle Regulator Potentially Involved in Genesis of Many Tumor Types
Authors: Kamb Alexander , Gruis Nelleke A. , Weaver-Feldhaus Jane , Liu Qingyun , Harshman Keith , Tavtigian Sean V. , Stockert Elisabeth , Day Rufus S. , Johnson Bruce E. , Skolnick Mark H.
Published: October 2006

A putative tumor suppressor locus on the short arm of human chromosome 9 has been localized to a region of less than 40 kilobases by means of homozygous deletions in melanoma cell lines. This region contained a gene, Multiple Tumor Suppressor 1 (
MTS1
), that encodes a previously identified inhibitor (p16) of cyclin-dependent kinase 4.
MTS1
was homozygously deleted at high frequency in cell lines derived from tumors of lung, breast, brain, bone, skin, bladder, kidney, ovary, and lymphocyte. Melanoma cell lines that carried at least one copy of
MTS1
frequently carried nonsense, missense, or frameshift mutations in the gene. These findings suggest that
MTS1
mutations are involved in tumor formation in a wide range of tissues.
Gating Current Noise Produced by Elementary Transitions in
Shaker
Potassium Channels
Authors: Sigg Daniel , Stefani Enrico , Bezanilla Francisco
Published: October 2006

Gating currents provide a direct record of the spatial rearrangement of charges occurring within the protein of voltage-sensitive ion channels. If the elementary charges move as very brief discrete pulses of current, they will produce fluctuations in the macroscopic gating current. The variance of such fluctuations in gating currents was measured in
Shaker
potassium channels expressed in
Xenopus
oocytes with a sufficiently high recording bandwidth to estimate the magnitude and time distribution of the elementary transition charge movements. Channel activation occurred in two sequential stages. The first stage consisted of numerous, fast transitions, each moving small amounts of charge that contributed little to the fluctuation in gating current, whereas the second stage, which contributed the bulk of the fluctuation, was represented by a number of discrete, correlated transitions, one or more of which carried a charge of at least 2.4 elementary charges across the membrane field.
Enhanced Myocardial Function in Transgenic Mice Overexpressing the β
2
-Adrenergic Receptor
Authors: Milano C. A. , Allen L. F. , Rockman H. A. , Dolber P. C. , McMinn T. R. , Chien K. R. , Johnson T. D. , Bond R. A. , Lefkowitz R. J.
Published: October 2006

Transgenic mice were created with cardiac-specific overexpression of the β
2
-adrenergic receptor. This resulted in increased basal myocardial adenylyl cyclase activity, enhanced atrial contractility, and increased left ventricular function in vivo; these parameters at baseline in the transgenic animals were equal to those observed in control animals maximally stimulated with isoproterenol. These results illustrate a useful approach for studying the effect of gene expression on cardiac contractility. Because chronic heart failure in humans is accompanied by a reduction in the number of myocardial β-adrenergic receptors and in inotropic responsiveness, these results suggest a potential gene therapy approach to this disease state.
Engineering Cell Shape and Function
Authors: Singhvi Rahul , Kumar Amit , Lopez Gabriel P. , Stephanopoulos Gregory N. , Wang Daniel I. C. , Whitesides George M. , Ingber Donald E.
Published: October 2006

An elastomeric stamp, containing defined features on the micrometer scale, was used to imprint gold surfaces with specific patterns of self-assembled monolayers of alkanethiols and, thereby, to create islands of defined shape and size that support extracellular matrix protein adsorption and cell attachment. Through this technique, it was possible to place cells in predetermined locations and arrays, separated by defined distances, and to dictate their shape. Limiting the degree of cell extension provided control over cell growth and protein secretion. This method is experimentally simple and highly adaptable. It should be useful for applications in biotechnology that require analysis of individual cells cultured at high density or repeated access to cells placed in specified locations.
Abnormal Development of Peripheral Lymphoid Organs in Mice Deficient in Lymphotoxin
Authors: De Togni Pietro , Goellner Joseph , Ruddle Nancy H. , Streeter Philip R. , Fick Andrea , Mariathasan Sanjeev , Smith Stacy C. , Carlson Rebecca , Shornick Laurie P. , Strauss-Schoenberger Jena , Russell John H. , Karr Robert , Chaplin David D.
Published: October 2006

Mice rendered deficient in lymphotoxin (LT) by gene targeting in embryonic stem cells have no morphologically detectable lymph nodes or Peyer's patches, although development of the thymus appears normal. Within the white pulp of the spleen, there is failure of normal segregation of B and T cells. Spleen and peripheral blood contain CD4
+
CD8
-
and CD4
-
CD8
+
T cells in a normal ratio, and both T cell subsets have an apparently normal lytic function. Lymphocytes positive for immunoglobulin M are present in increased numbers in both the spleen and peripheral blood. These data suggest an essential role for LT in the normal development of peripheral lymphoid organs.
A Lymphotoxin-β-Specific Receptor
Authors: Crowe Paul D. , VanArsdale Todd L. , Walter Barbara N. , Ware Carl F. , Hession Catherine , Ehrenfels Barbara , Browning Jeffrey L. , Din Wenie S. , Goodwin Raymond G. , Smith Craig A.
Published: October 2006

Tumor necrosis factor (TNF) and lymphotoxin-α (LT-α) are members of a family of secreted and cell surface cytokines that participate in the regulation of immune and inflammatory responses. The cell surface form of LT-α is assembled during biosynthesis as a heteromeric complex with lymphotoxin-β (LT-β), a type II transmembrane protein that is another member of the TNF ligand family. Secreted LT-α is a homotrimer that binds to distinct TNF receptors of 60 and 80 kilodaltons; however, these receptors do not recognize the major cell surface LT-α-LT-β complex. A receptor specific for human LT-β was identified, which suggests that cell surface LT may have functions that are distinct from those of secreted LT-α.
Mutagenesis and Mapping of a Mouse Gene,
Clock
, Essential for Circadian Behavior
Authors: Vitaterna Martha Hotz , King David P. , Chang Anne-Marie , Kornhauser Jon M. , Lowrey Phillip L. , McDonald J. David , Dove William F. , Pinto Lawrence H. , Turek Fred W. , Takahashi Joseph S.
Published: October 2006

In a search for genes that regulate circadian rhythms in mammals, the progeny of mice treated with
N
-ethyl-
N
-nitrosourea (ENU) were screened for circadian clock mutations. A semidominant mutation,
Clock
, that lengthens circadian period and abolishes persistence of rhythmicity was identified.
Clock
segregated as a single gene that mapped to the midportion of mouse chromosome 5, a region syntenic to human chromosome 4. The power of ENU mutagenesis combined with the ability to clone murine genes by map position provides a generally applicable approach to study complex behavior in mammals.
Relaxation of a Single DNA Molecule Observed by Optical Microscopy
Authors: Perkins Thomas T. , Quake Stephen R. , Smith Douglas E. , Chu Steven
Published: October 2006

Single molecules of DNA, visualized in video fluorescence microscopy, were stretched to full extension in a flow, and their relaxation was measured when the flow stopped. The molecules, attached by one end to a 1-micrometer bead, were manipulated in an aqueous solution with optical tweezers. Inverse Laplace transformations of the relaxation data yielded spectra of decaying exponentials with distinct peaks, and the longest time component (τ) increased with length (L) as τ ∼
L
1.66 ± 0.10
. A rescaling analysis showed that most of the relaxation curves had a universal shape and their characteristic times (λ
t
) increased as λ
t
∼
L
1.65 ± 0.13
. These results are in qualitative agreement with the theoretical prediction of dynamical scaling.
Cure of Xenografted Human Tumors by Bispecific Monoclonal Antibodies and Human T Cells
Authors: Renner Christoph , Jung Wolfram , Sahin Ugur , Denfeld Ralf , Pohl Christoph , Trumper Lorenz , Hartmann Frank , Diehl Volker , van Lier René , Pfreundschuh Michael
Published: October 2006

Tumor immunotherapy should increase both the number of T cells that kill the tumor and the likelihood that those cells are activated at the tumor site. Bispecific monoclonal antibodies (Bi-mAbs) were designed that bound to a Hodgkin's tumor-associated antigen (CD30) on the tumor and to either CD3 or CD28 on the T cell. Immunodeficient mice were cured of established human tumors when mice were treated with both the CD3-CD30 and the CD28-CD30 Bi-mAbs and then given human peripheral blood lymphocytes that had been incubated with the CD3-CD30 Bi-mAb and cells that expressed CD30. The enrichment of human T cells within the tumor and the fact that established tumors can be cured may indicate in situ activation of both the T cell receptor and the costimulatory pathway.
Neural Tuning for Sound Duration: Role of Inhibitory Mechanisms in the Inferior Colliculus
Authors: Casseday J. H. , Ehrlich D. , Covey E.
Published: October 2006

Duration is a biologically important feature of sound. Some neurons in the inferior colliculus of the big brown bat,
Eptesicus fuscus
, are tuned to sound duration, but it is unclear at what level the tuning originates or what neural mechanisms are responsible for it. The application of antagonists of the inhibitory neurotransmitters γ-aminobutyric acid or glycine to neurons in the inferior colliculus eliminated duration tuning. Whole-cell patch-clamp recordings of synaptic currents suggested that inhibition produces a temporal frame within which excitation can occur. A model is proposed in which duration tuning arises when an early, sustained inhibitory input interacts with a delayed, transient excitatory input.
Differential Effects of Apolipoproteins E3 and E4 on Neuronal Growth in Vitro
Authors: Nathan B. P. , Bellosta S. , Sanan D. A. , Weisgraber K. H. , Mahley R. W. , Pitas R. E.
Published: October 2006

Apolipoprotein E4 (apoE4), one of the three common isoforms of apoE, has been implicated in Alzheimer's disease. The effects of apoE on neuronal growth were determined in cultures of dorsal root ganglion neurons. In the presence of β-migrating very low density lipoproteins (β-VLDL), apoE3 increased neurite outgrowth, whereas apoE4 decreased outgrowth. The effects of apoE3 or apoE4 in the presence of β-VLDL were prevented by incubation with a monoclonal antibody to apoE or by reductive methylation of apoE, both of which block the ability of apoE to interact with lipoprotein receptors. The data suggest that receptor-mediated binding or internalization (or both) of apoE-enriched β-VLDL leads to isoform-specific differences in interactions with cellular proteins that affect neurite outgrowth.
Drosophila
TAF
II
150: Similarity to Yeast Gene TSM-1 and Specific Binding to Core Promoter DNA
Authors: Verrijzer C. Peter , Yokomori Kyoko , Chen Jin-Long , Tjian Robert
Published: October 2006

In
Drosophila
and human cells, the TATA binding protein (TBP) of the transcription factor IID (TFIID) complex is tightly associated with multiple subunits termed TBP-associated factors (TAFs) that are essential for mediating regulation of RNA polymerase II transcription. The
Drosophila
TAF
II
150 has now been molecularly cloned and biochemically characterized. The deduced primary amino acid sequence of dTAF
II
150 reveals a striking similarity to the essential yeast gene, TSM-1. Furthermore, like dTAF
II
150, the TSM-1 protein is found associated with the TBP in vivo, thus identifying the first yeast homolog of a TAF associated with TFIID. Both the product of TSM-1 and dTAF
II
150 bind directly to TBP and dTAF
II
250, demonstrating a functional similarity between human and yeast TAFs. Surprisingly, DNA binding studies indicate that purified recombinant dTAF
II
150 binds specifically to DNA sequences overlapping the start site of transcription. The data demonstrate that at least one of the TAFs is a sequence-specific DNA binding protein and that dTAF
II
150 together with TBP are responsible for TFIID interactions with an extended region of the core promoter.
The Return of Phineas Gage: Clues About the Brain from the Skull of a Famous Patient
Authors: Damasio Hanna , Grabowski Thomas , Frank Randall , Galaburda Albert M. , Damasio Antonio R.
Published: October 2006

When the landmark patient Phineas Gage died in 1861, no autopsy was performed, but his skull was later recovered. The brain lesion that caused the profound personality changes for which his case became famous has been presumed to have involved the left frontal region, but questions have been raised about the involvement of other regions and about the exact placement of the lesion within the vast frontal territory. Measurements from Gage's skull and modern neuroimaging techniques were used to reconstitute the accident and determine the probable location of the lesion. The damage involved both left and right prefrontal cortices in a pattern that, as confirmed by Gage's modern counterparts, causes a defect in rational decision making and the processing of emotion.
Gene for Familial Psoriasis Susceptibility Mapped to the Distal End of Human Chromosome 17q
Authors: Tomfohrde James , Silverman Alan , Barnes Robert , Fernandez-Vina Marcelo A. , Young Melodie , Lory Detra , Morris Laura , Wuepper Kirk D. , Stastny Peter , Menter Alan , Bowcock Anne
Published: October 2006

A gene involved in psoriasis susceptibility was localized to the distal region of human chromosome 17q as a result of a genome-wide linkage analysis with polymorphic microsatellites and eight multiply affected psoriasis kindreds. In the family which showed the strongest evidence for linkage, the recombination fraction between a psoriasis susceptibility locus and
D17S784
was 0.04 with a maximum two-point lod score of 5.33. There was also evidence for genetic heterogeneity and although none of the linked families showed any association with
HLA-Cw6
, two unlinked families showed weak levels of association. This study demonstrates that in some families, psoriasis susceptibility is due to variation at a single major genetic locus other than the human lymphocyte antigen locus.
Long-Distance Neuronal Migration in the Adult Mammalian Brain
Authors: Lois Carlos , Alvarez-Buylla Arturo
Published: October 2006

During the development of the mammalian brain, neuronal precursors migrate to their final destination from their site of birth in the ventricular and subventricular zones (VZ and SVZ, respectively). SVZ cells in the walls of the lateral ventricle continue to proliferate in the brain of adult mice and can generate neurons in vitro, but their fate in vivo is unknown. Here SVZ cells from adult mice that carry a neuronal-specific transgene were grafted into the brain of adult recipients. In addition, the fate of endogenous SVZ cells was examined by microinjection of tritiated thymidine or a vital dye that labeled a discrete population of SVZ cells. Grafted and endogenous SVZ cells in the lateral ventricle of adult mice migrate long distances and differentiate into neurons in the olfactory bulb.
Linkage Analysis of
IL4
and Other Chromosome 5q31.1 Markers and Total Serum Immunoglobulin E Concentrations
Authors: Marsh David G. , Neely John D. , Breazeale Daniel R. , Ghosh Balaram , Freidhoff Linda R. , Ehrlich-Kautzky Eva , Schou Carsten , Krishnaswamy Guha , Beaty Terri H.
Published: October 2006

Sib-pair analysis of 170 individuals from 11 Amish families revealed evidence for linkage of five markers in chromosome 5q31.1 with a gene controlling total serum immunoglobulin E (IgE) concentration. No linkage was found between these markers and specific IgE antibody concentrations. Analysis of total IgE within a subset of 128 IgE antibody-negative sib pairs confirmed evidence for linkage to 5q31.1, especially to the interleukin-4 gene (
IL4
). A combination of segregation and maximum likelihood analyses provided further evidence for this linkage. These analyses suggest that
IL4
or a nearby gene in 5q31.1 regulates IgE production in a nonantigen-specific (noncognate) fashion.
Geographic Variation of
p53
Mutational Profile in Nonmalignant Human Liver
Authors: Aguilar F. , Harris C. C. , Sun T. , Hollstein M. , Cerutti P.
Published: October 2006

Fifty-eight percent of hepatocellular carcinomas (HCCs) from Qidong, China, contain an AGG to AGT mutation at codon 249 of the
p53
tumor suppressor gene, a mutation that is rarely seen in HCCs from Western countries. The population of Qidong is exposed to high levels of aflatoxin B
1
(AFB
1
), a fungal toxin that has been shown to induce the same mutation in cultured human HCC cells. To investigate the role of AFB
1
and of these
p53
mutations in hepatocarcinogenesis, normal liver samples from the United States, Thailand, and Qidong (where AFB
1
exposures are negligible, low, and high, respectively) were examined for
p53
mutations. The frequency of the AGG to AGT mutation at codon 249 paralleled the level of AFB
1
exposure, which supports the hypothesis that this toxin has a causative—and probably early—role in hepatocarcinogenesis.
The TATA-Binding Protein: a General Transcription Factor in Eukaryotes and Archaebacteria
Authors: Rowlands Tracey , Baumann Peter , Jackson Stephen P.
Published: October 2006

The TATA-binding protein TBP appears to be essential for all transcription in eukaryotic cell nuclei, which suggests that its function was established early in evolution. Archaebacteria constitute a kingdom of organisms distinct from eukaryotes and eubacteria. Archaebacterial gene regulatory sequences often map to TATA box-like motifs. Here it is shown that the archaebacterium
Pyrococcus woesei
expresses a protein with structural and functional similarity to eukaryotic TBP molecules. This suggests that TBP's role in transcription was established before the archaebacterial and eukaryotic lineages diverged and that the transcription systems of archaebacteria and eukaryotes are fundamentally homologous.
Summation and Division by Neurons in Primate Visual Cortex
Authors: Carandini Matteo , Heeger David J.
Published: October 2006

Recordings from monkey primary visual cortex (V1) were used to test a model for the visually driven responses of simple cells. According to the model, simple cells compute a linear sum of the responses of lateral geniculate nucleus (LGN) neurons. In addition, each simple cell's linear response is divided by the pooled activity of a large number of other simple cells. The cell membrane performs both operations; synaptic currents are summed and then divided by the total membrane conductance. Current and conductance are decoupled (by a complementary arrangement of excitation and inhibition) so that current depends only on the LGN inputs and conductance depends only on the cortical inputs. Closed form expressions were derived for fitting and interpreting physiological data. The model accurately predicted responses to drifting grating stimuli of various contrasts, orientations, and spatiotemporal frequencies.
Jak-STAT Pathways and Transcriptional Activation in Response to IFNs and Other Extracellular Signaling Proteins
Authors: Darnell James E. , Kerr lan M. , Stark George R.
Published: October 2006

Through the study of transcriptional activation in response to interferon α (IFN-α) and interferon γ (IFN-γ), a previously unrecognized direct signal transduction pathway to the nucleus has been uncovered: IFN-receptor interaction at the cell surface leads to the activation of kinases of the Jak family that then phosphorylate substrate proteins called STATs (signal transducers and activators of transcription). The phosphorylated STAT proteins move to the nucleus, bind specific DNA elements, and direct transcription. Recognition of the molecules involved in the IFN-α and IFN-γ pathway has led to discoveries that a number of STAT family members exist and that other polypeptide ligands also use the Jak-STAT molecules in signal transduction.
Tetrad Analysis Possible in
Arabidopsis
with Mutation of the
QUARTET
(
QRT
) Genes
Authors: Preuss Daphne , Rhee Seung Y. , Davis Ronald W.
Published: October 2006

Two
Arabidopsis thaliana
genes,
QRT1
and
QRT2
, are required for pollen separation during normal development. In
qrt
mutants, the outer walls of the four meiotic products of the pollen mother cell are fused, and pollen grains are released in tetrads. Pollen is viable and fertile, and the cytoplasmic pollen contents are discrete. Pollination with a single tetrad usually yields four seeds, and genetic analysis confirmed that marker loci segregate in a 2:2 ratio within these tetrads. These mutations allow tetrad analysis to be performed in
Arabidopsis
and define steps in pollen cell wall development.
Reversal of Terminal Differentiation Mediated by p107 in Rb
-/-
Muscle Cells
Authors: Schneider Jay W. , Gu Wei , Zhu Liang , Mahdavi Vijak , Nadal-Ginard Bernardo
Published: October 2006

The terminal differentiation of mammalian muscle cells requires the tumor suppressor retinoblastoma protein (Rb). Unlike their wild-type counterparts, multinucleated myotubes from mouse cells deficient in Rb (Rb
-/-
) were induced by serum to reenter the cell cycle. Development of the myogenic phenotype in Rb
-/-
cells correlated with increased expression of p107, which interacted with myogenic transcription factors. Serum-induced cell cycle reentry, on the other hand, correlated with decreased p107 expression. Thus, although p107 could substitute for Rb as a cofactor for differentiation, it could not maintain the terminally differentiated state in Rb
-/-
myotubes.
Digenic Retinitis Pigmentosa Due to Mutations at the Unlinked Peripherin/
RDS
and
ROM1
Loci
Authors: Kajiwara Kazuto , Berson Eliot L. , Dryja Thaddeus P.
Published: October 2006

In spite of recent advances in identifying genes causing monogenic human disease, very little is known about the genes involved in polygenic disease. Three families were identified with mutations in the unlinked photoreceptor-specific genes
ROM1
and peripherin/
RDS
, in which only double heterozygotes develop retinitis pigmentosa (RP). These findings indicate that the allelic and nonallelic heterogeneity known to be a feature of monogenic RP is complicated further by interactions between unlinked mutations causing digenic RP. Recognition of the inheritance pattern exemplified by these three families might facilitate the identification of other examples of digenic inheritance in human disease.
Genetic Animal Models of Alcohol and Drug Abuse
Authors: Crabbe John C. , Belknap John K. , Buck Kari J.
Published: October 2006

Behavioral and pharmacological responses of selectively bred and inbred rodent lines have been analyzed to elucidate many features of drug sensitivity and the adverse effects of drugs, the underlying mechanisms of drug tolerance and dependence, and the motivational states underlying drug reward and aversion. Genetic mapping of quantitative trait loci (QTLs) has been used to identify provisional chromosomal locations of genes influencing such pharmacological responses. Recent advances in transgenic technology, representational difference analysis, and other molecular methods now make feasible the positional cloning of QTLs that influence sensitivity to drugs of abuse. This marks a new period of synthesis in pharmacogenetic research, in which networks of drug-related behaviors, their underlying pharmacological, physiological, and biochemical mechanisms, and particular genomic regions of interest are being identified.
The Genetic Basis of Complex Human Behaviors
Authors: Plomin Robert , Owen Michael J. , McGuffin Peter
Published: October 2006

Quantitative genetic research has built a strong case for the importance of genetic factors in many complex behavioral disorders and dimensions in the domains of psychopathology, personality, and cognitive abilities. Quantitative genetics can also provide an empirical guide and a conceptual framework for the application of molecular genetics. The success of molecular genetics in elucidating the genetic basis of behavioral disorders has largely relied on a reductionistic one gene, one disorder (OGOD) approach in which a single gene is necessary and sufficient to develop a disorder. In contrast, a quantitative trait loci (QTL) approach involves the search for multiple genes, each of which is neither necessary nor sufficient for the development of a trait. The OGOD and QTL approaches have both advantages and disadvantages for identifying genes that affect complex human behaviors.
Higher Order Self-Assembly of Vesicles by Site-Specific Binding
Authors: Chiruvolu Shivkumar , Walker Scott , Israelachvili Jacob , Schmitt Franz-Josef , Leckband Deborah , Zasadzinski Joseph A.
Published: October 2006

The association of lipid molecules into spherical vesicles in solution as a result of nonspecific intermolecular forces constitutes a primary self-assembly process. Such vesicles can undergo a secondary self-assembly into higher order structures in a controlled and reversible manner by means of site-specific ligand-receptor (biotin-streptavidin) coupling. Cryoelectron microscopy shows these structures to be composed of tethered, rather than adhering, vesicles in their original, unstressed state. In contrast, vesicles aggregated by nonspecific, such as van der Waals, forces are deformed and stressed, producing unstable structures. Vesicle association by site-specific binding provides a practical mechanism for the production of stable, yet controllable, microstructured biomaterials.
Motor Neuron Degeneration in Mice that Express a Human Cu,Zn Superoxide Dismutase Mutation
Authors: Gurney Mark E. , Pu Haifeng , Chiu Arlene Y. , Dal Canto Mauro C. , Polchow Cynthia Y. , Alexander Denise D. , Caliendo Jan , Hentati Afif , Kwon Young W. , Deng Han-Xiang , Chen Wenje , Zhai Ping , Sufit Robert L. , Siddique Teepu
Published: October 2006

Mutations of human Cu,Zn superoxide dismutase (SOD) are found in about 20 percent of patients with familial amyotrophic lateral sclerosis (ALS). Expression of high levels of human SOD containing a substitution of glycine to alanine at position 93—a change that has little effect on enzyme activity—caused motor neuron disease in transgenic mice. The mice became paralyzed in one or more limbs as a result of motor neuron loss from the spinal cord and died by 5 to 6 months of age. The results show that dominant, gain-of-function mutations in SOD contribute to the pathogenesis of familial ALS.
Fluorescent X-Ray Interference From a Protein Monolayer
Authors: Sasaki Yuji , Suzuki Yoshio , Ishibashi Tadashi
Published: October 2006

Fluorescent x-ray interference patterns have been observed from monolayers of both a metal-containing protein (ferritin) and a nonmetal-containing protein [bovine serum albumin (BSA)] bound on a gold substrate. These interference patterns have been used to determine structure data. The nonmetal-containing protein was first reacted with metal ions by means of a chelate compound to place the necessary chromophore in the molecule. The size of the ferritin core measured by a scanning electron microscope agrees with the value obtained from the x-ray interference experiments. In the BSA molecule, the measured interference fringe is consistent with the model in which the short axes of BSA molecules are perpendicular to the surface substrate.
A Transforming Growth Factor β Type I Receptor that Signals to Activate Gene Expression
Authors: Bassing Craig H. , Yingling Jonathan M. , Howe David J. , Wang Tongwen , He Wei Wu , Gustafson Michael L. , Shah Paresh , Donahoe Patricia K. , Wang Xiao-Fan
Published: October 2006

Transforming growth factor beta (TGF-β) is a multifunctional factor that regulates many aspects of cellular functions. TGF-β signals through a heteromeric complex of the type I and type II TGF-β receptors. However, the molecular mechanism of signal transduction by this receptor complex remains unresolved. The type II receptor belongs to a transmembrane receptor serine-threonine kinase family. A new member of this receptor family (R4) was identified and shown to be a functional TGF-β type I receptor on the basis of its ability to restore a TGF-β-induced gene response in mutant cell lines lacking endogenous type I receptor. Both ligand binding and signaling of the R4 protein were dependent on the presence of a functional type II receptor. The type I receptor has an intrinsic serine-threonine kinase activity, which was essential for signal transduction.
Association of Transcription Factor APRF and Protein Kinase Jak1 with the Interleukin-6 Signal Transducer gp130
Authors: Lütticken Claudia , Wegenka Ursula M. , Yuan Juping , Buschmann Jan , Schindler Chris , Ziemiecki Andrew , Harpur Ailsa G. , Wilks Andrew F. , Yasukawa Kiyoshi , Taga Tetsuya , Kishimoto Tadamitsu , Barbieri Giovanna , Pellegrini Sandra , Sendtner Michael , Heinrich Peter C. , Horn Friedemann
Published: October 2006

Interleukin-6 (IL-6), leukemia inhibitory factor, oncostatin M, interleukin-11, and ciliary neurotrophic factor bind to receptor complexes that share the signal transducer gp130. Upon binding, the ligands rapidly activate DNA binding of acute-phase response factor (APRF), a protein antigenically related to the p91 subunit of the interferon-stimulated gene factor-3α (ISGF-3α). These cytokines caused tyrosine phosphorylation of APRF and ISGF-3α p91. Protein kinases of the Jak family were also rapidly tyrosine phosphorylated, and both APRF and Jak1 associated with gp130. These data indicate that Jak family protein kinases may participate in IL-6 signaling and that APRF may be activated in a complex with gp130.
Association and Activation of Jak-Tyk Kinases by CNTF-LIF-OSM-IL-6 β Receptor Components
Authors: Stahl Neil , Boulton Teri G. , Farruggella Thomas , Ip Nancy Y. , Davis Sam , Witthuhn Bruce A. , Quelle Frederick W. , Silvennoinen Olli , Barbieri Giovanna , Pellegrini Sandra , Ihle James N. , Yancopoulos George D.
Published: October 2006

A recently defined family of cytokines, consisting of ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), oncostatin M (OSM), and interleukin-6 (IL-6), utilize the Jak-Tyk family of cytoplasmic tyrosine kinases. The β receptor components for this cytokine family, gp130 and LIF receptor β, constitutively associate with Jak-Tyk kinases. Activation of these kinases occurs as a result of ligand-induced dimerization of the receptor β components. Unlike other cytokine receptors studied to date, the receptors for the CNTF cytokine family utilize all known members of the Jak-Tyk family, but induce distinct patterns of Jak-Tyk phosphorylation in different cell lines.
Targeting of Gα
i2
to the Golgi by Alternative Spliced Carboxyl-Terminal Region
Authors: Montmayeur Jean-Pierre , Borrelli Emiliana
Published: October 2006

Heterotrimeric guanosine triphosphate (GTP)-binding proteins (G proteins) may participate in membrane traffic events. A complementary DNA (cDNA) was isolated from a mouse pituitary cDNA library that corresponded to an alternatively spliced form of the gene encoding the G protein alpha subunit Gα
i2
. The cDNA was identical to that encoding Gα
i2
except that the region encoding for the carboxyl-terminal 24 amino acids was replaced by a longer region encoding 35 amino acids that have no sequence similarity with Gα
i2
or other members of the G protein family. This alternative spliced product and the corresponding protein (sG
i2
) were present in several tissues. Specific antibodies revealed that sG
i2
was localized in the Golgi apparatus, suggesting a role in membrane transport. Thus, alternative splicing may generate from a single gene two G protein alpha subunits with differential cellular localization and function.
Structure of the Catalytic Domain of Fibroblast Collagenase Complexed with an Inhibitor
Authors: Lovejoy Brett , Cleasby Anne , Hassell Anne M. , Longley Kelly , Luther Michael A. , Weigl Debra , McGeehan Gerard , McElroy Andrew B. , Drewry David , Lambert Millard H. , Jordan Steven R.
Published: October 2006

Collagenase is a zinc-dependent endoproteinase and is a member of the matrix metalloproteinase (MMP) family of enzymes. The MMPs participate in connective tissue remodeling events and aberrant regulation has been associated with several pathologies. The 2.4 angstrom resolution structure of the inhibited enzyme revealed that, in addition to the catalytic zinc, there is a second zinc ion and a calcium ion which play a major role in stabilizing the tertiary structure of collagenase. Despite scant sequence homology, collagenase shares structural homology with two other endoproteinases, bacterial thermolysin and crayfish astacin. The detailed description of protein-inhibitor interactions present in the structure will aid in the design of compounds that selectively inhibit individual members of the MMP family. Such inhibitors will be useful in examining the function of MMPs in pathological processes.
Innervation of the Heart and Its Central Medullary Origin Defined by Viral Tracing
Authors: Standish Amelia , Enquist Lynn W. , Schwaber James S.
Published: October 2006

The vagus nerve exerts a profound influence on the heart, regulating the heart rate and rhythm. An extensive vagal innervation of the cardiac ventricles and the central origin and extent of this innervation was demonstrated by transynaptic transport of pseudorabies virus with a virulent and two attenuated pseudorabies viral strains. The neurons that innervate the ventricles are numerous, and their distribution within the nucleus ambiguus and dorsal motor nucleus of the vagus is similar to that of neurons innervating other cardiac targets, such as the sino-atrial node. These data provide a neuroanatomical correlate to the physiological influence of the vagus nerve on ventricular function.
Levels of Peripheral T Cell Tolerance Induced by Different Doses of Tolerogen
Authors: Ferber Iris , Schönrich Günter , Schenkel Johannes , Mellor Andrew L. , Hämmerling Günter J. , Arnold Bernd
Published: October 2006

Antigen-specific immunosuppression requires an understanding of the parameters that control peripheral T cell tolerance. A liver-specific inducible promoter was used to drive the expression of the major histocompatibility complex antigen K
b
in transgenic mice. Minute amounts of K
b
, expressed exclusively on hepatocytes, induced tolerance by partial down-regulation of the T cell receptor (TCR) on the self-reactive CD8
+
cells. Contact of these tolerant T cells with high concentrations of K
b
after induction led to complete down-regulation of TCR. Thus, tolerant T cells are susceptible to further tolerogenic signals and reach different levels of tolerance depending on antigen dose.
Natural Vertical Transmission of Western Equine Encephalomyelitis Virus in Mosquitoes
Authors: Fulhorst C. F. , Hardy J. L. , Eldridge B. F. , Presser S. B. , Reeves W. C.
Published: October 2006

The mechanism by which western equine encephalomyelitis (WEE) virus and other mosquito-borne alphaviruses (Togaviridae) survive during periods of vector inactivity is unknown. Recently, three strains of WEE virus were isolated from adult
Aedes dorsalis
collected as larvae from a salt marsh in a coastal region of California. This provides evidence of vertical transmission of WEE virus in mosquitoes in nature. Vertical transmission in
Ae. dorsalis
and closely related mosquito species may be an important mechanism for the maintenance of WEE virus in temperate regions in North America where horizontal transmission of the virus is seasonal.
Associative Odor Learning in
Drosophila
Abolished by Chemical Ablation of Mushroom Bodies
Authors: de Belle J. Steven , Heisenberg Martin
Published: October 2006

The corpora pedunculata, or mushroom bodies (MBs), in the brain of
Drosophila melanogaster
adults consist of ∼2500 parallel Kenyon cell fibers derived from four MB neuroblasts. Hydroxyurea fed to newly hatched larvae selectively deletes these cells, resulting in complete, precise MB ablation. Adult flies developing without MBs behave normally in most respects, but are unable to perform in a classical conditioning paradigm that tests associative learning of odor cues and electric shock. This deficit cannot be attributed to reductions in olfactory sensitivity, shock reactivity, or locomotor behavior. The results demonstrate that MBs mediate associative odor learning in flies.
Coupling of Local Folding to Site-Specific Binding of Proteins to DNA
Authors: Spolar Ruth S. , Record M. Thomas
Published: October 2006

Thermodynamic studies have demonstrated the central importance of a large negative heat capacity change (Δ
C
°
assoc
) in site-specific protein-DNA recognition. Dissection of the large negative Δ
C
°
assoc
and the entropy change of protein-ligand and protein-DNA complexation provide a thermodynamic signature identifying processes in which local folding is coupled to binding. Estimates of the number of residues that fold on binding obtained from this analysis agree with structural data. Structural comparisons indicate that these local folding transitions create key parts of the protein-DNA interface. The energetic implications of this "induced fit" model for DNA site recognition are considered.
RNA Polymerase II Initiation Factor Interactions and Transcription Start Site Selection
Authors: Li Yang , Flanagan Peter M. , Tschochner Herbert , Kornberg Roger D.
Published: October 2006

An RNA polymerase II transcription system was resolved and reconstituted from extracts of
Schizosaccharomyces pombe
. Exchange with components of a
Saccharomyces cerevisiae
system was undertaken to reveal the factor or factors responsible for the difference in location of the transcription start site, about 30 base pairs and 40 to 120 base pairs downstream of the TATA box in
S. pombe
and
S. cerevisiae
, respectively. Two components, counterparts of human transcription factor IIF (TFIIF) and TFIIH, could be exchanged individually between systems without effect on the start site. Three components, counterparts of human TFIIB, TFIIE, and RNA polymerase II, could not be exchanged individually but could be swapped in the pairs TFIIE-TFIIH and TFIIB-RNA polymerase II, which demonstrates that there are functional interactions between these components. Moreover, exchange of the latter pair shifted the starting position, which shows that TFIIB and RNA polymerase II are solely responsible for determining the start site of transcription.
Transcriptional Activation Modulated by Homopolymeric Glutamine and Proline Stretches
Authors: Gerber Hans-Peter , Seipel Katja , Georgiev Oleg , Höfferer Manuela , Hug Martin , Rusconi Sandro , Schaffner Walter
Published: October 2006

Many transcription factors contain proline- or glutamine-rich activation domains. Here it is shown that simple homopolymeric stretches of these amino acids can activate transcription when fused to the DNA binding domain of GAL4 factor. In vitro, activity increased with polymer length, whereas in cell transfection assays maximal activity was achieved by 10 to 30 glutamines or about 10 prolines. Similar results were obtained when glutamine stretches were placed within a [GAL4]-VP16 chimeric protein. Because these stretches are encoded by rapidly evolving triplet repeats (microsatellites), they may be the main cause for modulation of transcription factor activity and thus result in subtle or overt genomic effects.
Prevention of Vertebrate Neuronal Death by the
crmA
Gene
Authors: Gagliardini Valeria , Fernandez Pierre-Alain , Lee Robert K. K. , Drexler Hannes C. A. , Rotello Rocco J. , Fishman Mark C. , Yuan Junying
Published: October 2006

Interleukin-1β converting enzyme (ICE) is a mammalian homolog of CED-3, a protein required for programmed cell death in the nematode
Caenorhabditis elegans
. The activity of ICE can be specifically inhibited by the product of
crmA
, a cytokine response modifier gene encoded by cowpox virus. Microinjection of the
crmA
gene into chicken dorsal root ganglion neurons was found to prevent cell death induced by deprivation of nerve growth factor. Thus, ICE is likely to participate in neuronal death in vertebrates.
Diverse Essential Functions Revealed by Complementing Yeast Calmodulin Mutants
Authors: Ohya Yoshikazu , Botstein David
Published: October 2006

Calmodulin, a cytoplasmic calcium-binding protein, is indispensable for eukaryotic cell growth. Examination of 14 temperature-sensitive yeast mutants bearing one or more phenylalanine to alanine substitutions in the single essential calmodulin gene of yeast (
CMD1
) revealed diverse essential functions. Mutations could be classified into four intragenic complementation groups. Each group showed different characteristic functional defects in actin organization, calmodulin localization, nuclear division, or bud emergence. Phenylalanine residues implicated in calmodulin localization and nuclear division are located in the amino-terminal half of the protein, whereas those implicated in actin organization and bud emergence are located in the carboxyl-terminal half.
Llama Single-Chain Antibody That Blocks Lipopolysaccharide Binding and Signaling: Prospects for Therapeutic Applications
Authors: El Khattabi Mohamed , Adams Hendrik , Heezius Erik , Hermans Pim , Detmers Frank , Maassen Bram , van der Ley Peter , Tommassen Jan , Verrips Theo , Stam Jord
Published: October 2006

Sepsis is a considerable health problem and a burden on the health care system. Endotoxin, or lipopolysaccharide (LPS), present in the outer membrane of gram-negative bacteria, is responsible for more than 50% of the sepsis cases and is, therefore, a legitimate target for therapeutic approaches against sepsis. In this study, we selected and characterized a llama single-chain antibody fragment (VHH) directed toNeisseria meningitidisLPS. The VHH, designated VHH 5G, showed affinity to purified LPS as well as to LPS on the surfaces of the bacteria. Epitope mapping using a panel ofN. meningitidismutants revealed that VHH 5G recognizes an epitope in the inner core of LPS, and as expected, the VHH proved to have broad specificity for LPS from different bacteria. Furthermore, this VHH blocked binding of LPS to target cells of the immune system, resulting in the inhibition of LPS signaling in whole blood. Moreover, it was found to remove LPS efficiently from aqueous solutions, including serum. The selected anti-LPS VHH is a leading candidate for therapies against LPS-mediated sepsis.
Specific and Randomly Derived Immunoactive Peptide Mimotopes of Mycobacterial Antigens
Authors: Sharma Archna , Saha Abhik , Bhattacharjee Surajit , Majumdar Subrata , Das Gupta Sujoy K.
Published: October 2006

The mycobacterial cell surface contains complex nonprotein antigens that are highly immunoactive in nature. However, these antigens are chemically heterogeneous and structurally complex, thereby limiting their applications. To identify their peptide mimotopes, phage-displayed peptide libraries Ph.D.-7 and Ph.D.-12 were panned on either defined template, monoclonal antibody (MAb) CS-35 against lipoarabinomannan (LAM), or a polyclonal rabbit immune serum reactive against whole cells ofMycobacterium bovisBCG. Panning on anti-LAM MAb CS-35 yielded two confirmed mimotopes of LAM, a 7-mer and a 12-mer, whereas panning on polyclonal serum yielded a large repertoire of mimotopes reactive against sera from BCG-immunized rabbits, one of which turned out to have the same sequence as the 7-mer LAM mimotope. The dissociation constant of the interaction between MAb CS-35 and a synthetic peptide corresponding to the 7-mer LAM mimotope was determined to be 7.55 μM. Dot blot assays were performed with peptides corresponding to the two LAM mimotopes to evaluate their diagnostic potential. Both peptides gave discernibly higher signals with a panel of tuberculosis (TB) patient sera than with sera from healthy controls. The peptides were also found to stimulate the release of tumor necrosis factor alpha and interleukin-12 cytokines in the J774A.1 cell line and primary bone marrow-derived macrophages, indicating that they may have immunomodulatory potential. The present study demonstrates that peptide mimotopes of known and unknown mycobacterial antigens could be isolated by using subtractive phage display techniques and that these peptides could have potential applications in areas such as TB diagnostics and immunotherapy.