bluuebunny/crossref_metadata_2025 huggingface dataset:
A Chemoattractant Receptor Controls Development in
Dictyostelium discoideum
Authors: Klein Peter S. , Sun Tzeli J. , Saxe Charles L. , Kimmel Alan R. , Johnson Ronald L. , Devreotes Peter N.
Published: October 2006

During the early stages of its developmental program,
Dictyostelium discoideum
expresses cell surface cyclic adenosine monophosphate (cyclic AMP) receptors. It has been suggested that these receptors coordinate the aggregation of individual cells into a multicellular organism and regulate the expression of a large number of developmentally regulated genes. The complementary DNA (cDNA) for the cyclic AMP receptor has now been cloned from λgt-11 libraries by screening with specific antiserum. The 2-kilobase messenger RNA (mRNA) that encodes the receptor is undetectable in growing cells, rises to a maximum at 3 to 4 hours of development, and then declines. In vitro transcribed complementary RNA, when hybridized to cellular mRNA, specifically arrests in vitro translation of the receptor polypeptide. When the cDNA is expressed in
Dictyostelium
cells, the undifferentiated cells specifically bind cyclic AMP. Cell lines transformed with a vector that expresses complementary mRNA (antisense) do not express the cyclic AMP receptor protein. These cells fail to enter the aggregation stage of development during starvation, whereas control and wild-type cells aggregate and complete the developmental program within 24 hours. The phenotype of the antisense transformants suggests that the cyclic AMP receptor is essential for development. The deduced amino acid sequence of the receptor reveals a high percentage of hydrophobic residues grouped in seven domains, similar to the rhodopsins and other receptors believed to interact with G proteins. It shares amino acid sequence identity and is immunologically cross-reactive with bovine rhodopsin. A model is proposed in which the cyclic AMP receptor crosses the bilayer seven times with a serine-rich cytoplasmic carboxyl terminus, the proposed site of ligand-induced receptor phosphorylation.
Virus-Specific Splicing Inhibitor in Extracts from Cells Infected with HIV-1
Authors: Gutman Della , Goldenberg Carlos J.
Published: October 2006

Human immunodeficiency virus type 1 (HIV-1), in contrast with most other retroviruses, encodes trans-regulatory proteins for virus gene expression. It is shown in this study, by means of an in vitro splicing system, that nuclear extracts obtained from cells infected with HIV-1 contain a factor (or factors) that specifically inhibits splicing of a synthetic SP6/HIV pre-messenger RNA (pre-mRNA)-containing donor and acceptor splice sites in the coding region for the envelope protein. It is also shown that the SP6/HIV pre-mRNA is not capable of assembly in a ribonucleoprotein complex, spliceosome, in extracts from infected cells. These findings raise the possibility that specific inhibition of pre-mRNA splicing in the envelope protein coding region by HIV-1 trans-regulatory factors might be one control mechanism for efficient production of structural viral proteins and virion assembly.
Anticodon Switching Changes the Identity of Methionine and Valine Transfer RNAs
Authors: Schulman LaDonne H. , Pelka Heike
Published: October 2006

The anticodon has previously been shown to play a role in recognition of certain transfer RNAs by aminoacyl-tRNA synthetases; however, the extent to which this sequence dictates tRNA identity is generally unknown. To investigate the contribution of the anticodon to the identity of
Escherichia coli
methionine and valine tRNAs, in vitro transcripts of these tRNAs were prepared that contained normal and interchanged anticodon sequences. Transcripts containing wild-type tRNA sequences were excellent substrates for their respective cognate aminoacyl-tRNA synthetases and were effectively discriminated against by a variety of noncognate enzymes. The mutant tRNAs produced by switching the anticodon sequences lost their original tRNA identity and assumed an identity corresponding to the acquired anticodon sequence. These results indicate that the anticodon contains sufficient information to distinguish methionine and valine tRNAs with high fidelity.
Detection of α-Transducin in Retinal Rods But Not Cones
Authors: Grunwald Gerald B. , Gierschik Peter , Nirenberg Marshall , Spiegel Allen
Published: October 2006

The distribution in chicken retina of the α subunit of transducin, the guanine nucleotide-binding protein that couples light-dependent activation of rhodopsin with activation of guanosine 3′,5′-monophosphate phosphodiesterase, was determined with the aid of a specific antiserum. α-Transducin was found in rod photoreceptor cells but was not detected in cones. These results show that rods and cones differ with respect to α-transducin content and suggest that the processes of phototransduction may differ correspondingly in rods and cones.
Role of Platelet-Activating Factor-Acether in Mediating Guinea Pig Anaphylaxis
Authors: Darius Harald , Lefer David J. , Smith J. Bryan , Lefer Allan M.
Published: October 2006

The pathophysiology of anaphylaxis is very complex, and the sequelae of events are not fully explained in terms of the effects of histamine and peptide leukotrienes alone. Platelet-activating factor (1-
O
-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine, PAF-acether) has been detected in animals undergoing anaphylaxis. Injection of synthetic PAF-acether induces similar effects, including bronchoconstriction, respiratory arrest, systemic hypotension, neutropenia, and thrombocytopenia. The results reported here demonstrate that the histamine- and leukotriene-independent component of guinea pig anaphylaxis in vivo and in isolated lung parenchymal strips in vitro is mediated by PAF-acether. However, PAF-acether is not responsible for the anaphylaxis-induced thrombocytopenia.
Stimulation of Gonadotropin Release by a Non-GnRH Peptide Sequence of the GnRH Precursor
Authors: Millar Robert P. , Wormald Patricia J. , Milton Raymond C. de L.
Published: October 2006

The human gonadotropin-releasing hormone (GnRH) precursor comprises the GnRH sequence followed by an extension of 59 amino acids. Basic amino acid residues in the carboxyl terminal extension may represent sites of processing to biologically active peptides. A synthetic peptide comprising the first 13 amino acids (H ⋅ Asp-Ala-Glu-Asn-Leu-Ile-Asp-Ser-Phe-Gln-Glu-Ile-Val ⋅ OH) of the 59-amino acid peptide was found to stimulate the release of gonadotropic hormones from human and baboon anterior pituitary cells in culture. The peptide did not affect thyrotropin or prolactin secretion. A GnRH antagonist did not inhibit gonadotropin stimulation by the peptide, and the peptide did not compete with GnRH for GnRH pituitary receptors, indicating that the action of the peptide is independent of the GnRH receptor. The GnRH precursor contains two distinct peptide sequences capable of stimulating gonadotropin release from human and baboon pituitary cells.
Impulse Blockade in Frog Cardiac Ganglion Does Not Resemble Partial Denervation in Changing Synaptic Organization
Authors: Roper S. , Ko C.-P.
Published: October 2006

Partial denervation of parasympathetic neurons in the frog heart by surgical section of one vagus nerve results in a marked reorganization of functional synaptic connections made by the remaining vagus nerve. These changes are not simply due to a lack of impulse activity per se in the sectioned nerve because blockage of impulses in one vagus with tetrodotoxin-impregnated cuffs did not cause similar changes in the innervation pattern of the ganglion. Furthermore, tetrodotoxin-blocked vagal fibers retain their ability to sprout and can form new synapses on denervated neurons.
Tumor-Promoting Phorbol Esters Inhibit Binding of Epidermal Growth Factor to Cellular Receptors
Authors: Lee Lih-Syng , Weinstein I. Bernard
Published: October 2006

Tumor-promoting phorbol esters and related plant macrocyclic diterpenes inhibit the binding of epidermal growth factor to its receptors on HeLa cells. This effect shows marked structural specificity and correlates with other biological effects of these compounds on mouse skin and in cell culture systems. The active compounds inhibited binding of
125
I-labeled epidermal growth factor with a 50 percent effective dose in the range of 10
-8
to 10
-9
M
. Inhibition appears to be due to a decrease in the number of available epidermal growth factor receptors rather than a change in receptor affinity. These results suggest that certain biologic effects of tumor promoters may result from alterations in the function of cell surface receptors involved in growth regulation.
Lysosphingolipids Inhibit Protein Kinase C: Implications for the Sphingolipidoses
Authors: Hannun Yusuf A. , Bell Robert M.
Published: October 2006

Lysosphingolipids potently and reversibly inhibited protein kinase C activity and binding of phorbol dibutyrate in vitro and in human platelets. As with activation of protein kinase C by phosphatidylserine and
sn
-1,2-diacylglycerol, inhibition was subject to surface dilution. Accordingly, inhibition in mixed micelle assays was dependent on the molar percentage of lysosphingolipids rather than the bulk concentration. Lysosphingolipids inhibited protein kinase C activity at molar percentages similar to those required for activation by phosphatidylserine and
sn
-1,2-diacylglycerol. Since lysosphingolipids accumulate in Krabbe's disease, Gaucher's disease, and other sphingolipidoses, the hypothesis that lysosphingolipid inhibition of protein kinase C represents the missing functional link between the accumulation of sphingolipids and the pathogenesis of these disorders appears to unify existing data. The accumulation of lysosphingolipids would cause progressive dysfunction of signal transduction mechanisms vital for neural transmission, differentiation, development, and proliferation and would eventually lead to cell death.
Primary Structure and Biochemical Properties of an M
2
Muscarinic Receptor
Authors: Peralta Ernest G. , Winslow John W. , Peterson Gary L. , Smith Douglas H. , Ashkenazi Avi , Ramachandran J. , Schimerlik Michael I. , Capon Daniel J.
Published: October 2006

A partial amino acid sequence obtained for porcine atrial muscarinic acetylcholine receptor was used to isolate complementary DNA clones containing the complete receptor coding region. The deduced 466-amino acid polypeptide exhibits extensive structural and sequence homology with other receptors coupled to guanine nucleotide binding (G) proteins (for example, the β-adrenergic receptor and rhodopsins); this similarity predicts a structure of seven membrane-spanning regions distinguished by the disposition of a large cytoplasmic domain. Stable transfection of the Chinese hamster ovary cell line with the atrial receptor complementary DNA leads to the binding of muscarinic antagonists in these cells with affinities characteristic of the M
2
receptor subtype. The atrial muscarinic receptor is encoded by a unique gene consisting of a single coding exon and multiple, alternatively spliced 5′ noncoding regions. The atrial receptor is distinct from the cerebral muscarinic receptor gene product, sharing only 38% overall amino acid homology and possessing a completely nonhomologous large cytoplasmic domain, suggesting a role for the latter region in differential effector coupling.
Juvenile Hormone Action Mediated in Male Accessory Glands of
Drosophila
by Calcium and Kinase C
Authors: Yamamoto Karen , Chadarevian Aline , Pellegrini Maria
Published: October 2006

In an in vitro system for the
Drosophila melanogaster
male accessory gland, it was found that 10
-9
M
juvenile hormone III could accurately mimic the copulation-induced response of increased protein synthesis in glands from virgin flies. Stimulation by this hormone required calcium in the medium. Experiments with tumor-promoting phorbol esters indicated that activation of protein kinase C can also cause the glands to increase protein synthesis. Stimulation of protein synthesis by juvenile hormone did not occur in mutants deficient in kinase C activity. These results suggest a membrane-protein-mediated effect of juvenile hormone that involves calcium and kinase C.
Hand of
Paranthropus robustus
from Member 1, Swartkrans: Fossil Evidence for Tool Behavior
Authors: Susman Randall L.
Published: October 2006

New hand fossils from Swartkrans (dated at about 1.8 million years ago) indicate that the hand of
Paranthropus robustus
was adapted for precision grasping. Functional morphology suggests that
Paranthropus
could have used tools, possibly for plant procurement and processing. The new fossils further suggest that absence of tool behavior was not responsible for the demise of the "robust" lineage. Conversely, these new fossils indicate that the acquisition of tool behavior does not account for the emergence and success of early
Homo
.
Subattomole Amino Acid Analysis by Capillary Zone Electrophoresis and Laser-Induced Fluorescence
Authors: Cheng Yung-Fong , Dovichi Norman J.
Published: October 2006

Subattomole analysis of fluorescein isothiocyanate (FITC) derivatives of amino acids is accomplished by combining capillary zone electrophoresis for high-efficiency separation with laser-induced fluorescence for high-sensitivity detection. Concentration detection limits range from 5 × 10
-12
molar for alanine to 9 × 10
-11
molar for lysine, injected in the column; 9 × 10
-21
mole of alanine is contained within the ∼1-nanoliter injection volume at the detection limit. The alanine detection limit corresponds to fewer than 6000 molecules injected onto the column and represents an improvement of four orders of magnitude in the state of the art for fluorescent detection of amino acids and an improvement of six orders of magnitude in the state of the art for the detection limit for isothiocyanate derivatives of amino acids.
Influences of Dietary Sodium on Functional Taste Receptor Development: A Sensitive Period
Authors: Hill David L. , Przekop Peter R.
Published: October 2006

Restriction of maternal dietary sodium on or before embryonic day 8 reduced taste responses of the chorda tympani nerve to sodium chloride in the offspring. The response attenuation was substantial; responses to sodium chloride in the offspring of deprived rats were approximately 40 percent of those in control animals. Instituting the low sodium diet at embryonic day 10 or later did not produce functional changes. Thus, a sensitive period for the gustatory system exists, and the abrupt transition from maximal environmental susceptibility to no susceptibility occurs during a 2-day prenatal period. Moreover, events important in determining the developmental fate of taste membrane components occur before the initial formation of taste buds.
Cloning of a Membrane Protein That Induces a Slow Voltage-Gated Potassium Current
Authors: Takumi Toru , Ohkubo Hiroaki , Nakanishi Shigetada
Published: October 2006

A rat kidney messenger RNA that induces a slowly activating, voltage-dependent potassium current on its expression in
Xenopus
oocytes was identified by combining molecular cloning with an electrophysiological assay. The cloned complementary DNA encodes a novel membrane protein that consists of 130 amino acids with a single putative transmembrane domain. This protein differs from the known ion channel proteins but is involved in the induction of selective permeation of potassium ions by membrane depolarization.
Many Transcription Factors Interact Synergistically with Steroid Receptors
Authors: Schüle Roland , Muller Marc , Kaltschmidt Christian , Renkawitz Rainer
Published: October 2006

Progesterone (PRE) or glucocorticoid receptor (GRE) DNA binding sites are often found clustered with binding sites for other transcription factors. Individual protein binding sites were tested without the influence of adjacent factors by analyzing isolated combinations of several transcription factor binding sites with PREs or GREs. All show strong synergistic effects on steroid induction. The degree of synergism is inversely related to the strength of the GRE. Thus, a steroid responsive unit can be composed of several modules that, if positioned correctly, act synergistically.
Interleukin-1 Immunoreactive Innervation of the Human Hypothalamus
Authors: Breder Christopher D. , Dinarello Charles A. , Saper Clifford B.
Published: October 2006

Interleukin-1 (IL-1) is a cytokine that mediates the acute phase reaction. Many of the actions of IL-1 involve direct effects on the central nervous system. However, IL-1 has not previously been identified as an intrinsic component within the brain, except in glial cells. An antiserum directed against human IL-1β was used to stain the human brain immunohistochemically for IL-1β-like immunoreactive neural elements. IL-1β-immunoreactive fibers were found innervating the key endocrine and autonomic cell groups that control the central components of the acute phase reaction. These results indicate that IL-1 may be an intrinsic neuromodulator in central nervous system pathways that mediate various metabolic functions of the acute phase reaction, including the body temperature changes that produce the febrile response.
Early Signal Transduction by the Antigen Receptor Without Commitment to T Cell Activation
Authors: Goldsmith Mark A. , Weiss Arthur
Published: October 2006

The T lymphocyte antigen-receptor complex mediates antigen-specific cell activation, at least in part, through the production of inositolphospholipid-derived second messengers. Little is known about how second messenger events, typically measured within minutes of ligand binding, eventually lead to distal biologic responses such as expression of lymphokine genes. Several monoclonal antibodies directed against the receptor complex were tested for their ability to elicit transmembrane signaling in the parental Jurkat line and in a somatic mutant (J.CaM1) with a deficient receptor function. One antibody elicited substantial early Ca
2+
mobilization responses in both cells but was unable to promote expression of the interleukin-2 gene in J.CaM1. In J.CaM1 there was a diminished production of phosphatidylinositol second messengers, and the elevation in intracellular free Ca
2+
was transient. Thus, short-term Ca
2+
mobilization does not always indicate complete signal transmission and lead to a full cellular response.
Mitogen-Induced Replication of Woodchuck Hepatitis Virus in Cultured Peripheral Blood Lymphocytes
Authors: Korba Brent E. , Cote Paul J. , Gerin John L.
Published: October 2006

Peripheral blood lymphocytes (PBLs) isolated from woodchucks chronically infected with the woodchuck hepatitis virus (WHV) carry low levels of nonreplicating WHV DNA. When PBLs from chronic carrier woodchucks were activated in culture with the generalized mitogen lipopolysaccharide (LPS), WHV DNA replication was initiated in cells obtained from one of three animals examined. Intracellular WHV core particles, containing WHV DNA replication intermediates, RNA/DNA hybrid molecules, and an active endogenous DNA polymerase, appeared 3 days after the start of LPS stimulation. After 5 to 7 days of LPS stimulation, WHV DNA-containing particles, which displayed the properties of intact, mature virions, were released into the culture medium. These studies provide evidence for reactivation of a latent WHV infection of circulating lymphoid cells and indicate that the presence of nonreplicating hepadnaviral DNA in lymphoid cells represents a potentially active infection following cellular activation.
Segregation of Form, Color, Movement, and Depth: Anatomy, Physiology, and Perception
Authors: Livingstone Margaret , Hubel David
Published: October 2006

Anatomical and physiological observations in monkeys indicate that the primate visual system consists of several separate and independent subdivisions that analyze different aspects of the same retinal image: cells in cortical visual areas 1 and 2 and higher visual areas are segregated into three interdigitating subdivisions that differ in their selectivity for color, stereopsis, movement, and orientation. The pathways selective for form and color seem to be derived mainly from the parvocellular geniculate subdivisions, the depth- and movement-selective components from the magnocellular. At lower levels, in the retina and in the geniculate, cells in these two subdivisions differ in their color selectivity, contrast sensitivity, temporal properties, and spatial resolution. These major differences in the properties of cells at lower levels in each of the subdivisions led to the prediction that different visual functions, such as color, depth, movement, and form perception, should exhibit corresponding differences. Human perceptual experiments are remarkably consistent with these predictions. Moreover, perceptual experiments can be designed to ask which subdivisions of the system are responsible for particular visual abilities, such as figure/ground discrimination or perception of depth from perspective or relative movement—functions that might be difficult to deduce from single-cell response properties.
Disease Diagnosis by Recombinant DNA Methods
Authors: Caskey C. Thomas
Published: October 2006

Recombinant DNA procedures have now been applied to the problem of the identification of molecular defects in man that account for heritable diseases, somatic mutations associated with neoplasia, and acquired infectious disease. Thus recombinant DNA technology has rapidly expanded our ability to diagnose disease. Substantial advances in the simplification of procedures for diagnostic purposes have been made, and the informed physician has gained in diagnostic accuracy as a consequence of these developments. The wide application of recombinant DNA diagnostics will depend on simplicity, speed of results, and cost containment.
The Human Hematopoietic Colony-Stimulating Factors
Authors: Clark Steven C. , Kamen Robert
Published: October 2006

The complementary DNAs and genes encoding the four major human myeloid growth factors—granulocyte colony-stimulating factor, macrophage colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and interleukin-3—have all been molecularly cloned. These DNA clones have proved valuable for studying the molecular biology of these important regulatory molecules as well as for the large-scale production of the recombinant growth factor proteins. These advances have led to a much better understanding of the role of the myeloid growth factors in regulating hematopoiesis in vivo that should soon find practical application in clinical medicine.
Cell Wall Is Required for Fixation of the Embryonic Axis in
Fucus
Zygotes
Authors: Kropf Darryl L. , Kloareg Bernard , Quatrano Ralph S.
Published: October 2006

Establishment of a primary developmental axis generally is thought to involve rearrangements in the plasma membrane or cytoplasm of the egg. In this report the additional requirement for cell wall in polarization of
Fucus
zygotes was investigated. Protoplasts of fertilized eggs were tested for their ability to establish an axis in accordance with an orienting vector of unilateral light. The results demonstrate that cell wall is not required for axis formation. However, the orientation of the axis remains labile until new cell wall is synthesized. The presence of a cell wall is an absolute requirement for axis fixation.
Synthesizing a Color Algorithm from Examples
Authors: Hurlbert Anya C. , Poggio Tomaso A.
Published: October 2006

A lightness algorithm that separates surface reflectance from illumination in a Mondrian world is synthesized automatically from a set of examples, which consist of pairs of input (intensity signal) and desired output (surface reflectance) images. The algorithm, which resembles a new lightness algorithm recently proposed by Land, is approximately equivalent to filtering the image through a center-surround receptive field in individual chromatic channels. The synthesizing technique, optimal linear estimation, requires only one assumption, that the operator that transforms input into output is linear. This assumption is true for a certain class of early vision algorithms that may therefore be synthesized in a similar way from examples. Other methods of synthesizing algorithms from examples, or "learning," such as back-propagation, do not yield a significantly better lightness algorithm.
West African HIV-2-Related Human Retrovirus with Attenuated Cytopathicity
Authors: Kong Lilly I. , Lee Shei-Wen , Kappes John C. , Parkin Jeffrey S. , Decker Don , Hoxie James A. , Hahn Beatrice H. , Shaw George M.
Published: October 2006

Clinical and seroepidemiological studies in West Africa indicate that human immunodeficiency virus type 2 (HIV-2) is widespread and associated with immunodeficiency states of variable degree. In this study, an isolate of HIV-2 from a patient in Senegal was molecularly cloned and characterized. This isolate (HIV-2
ST
) was shown by hybridization and restriction enzyme analysis to be more related to the prototype HIV-2
ROD
than to other human or primate retroviruses. Cultures of HIV-2
ST
showed genotypic polymorphism, and clones of the virus had transmembrane envelope glycoproteins of 30 and 42 kilodaltons. Unlike other immunodeficiency viruses, HIV-2
ST
did not cause cell death or induce cell fusion in peripheral blood lymphocytes or in any of four CD4
+
cell lines tested. Although HIV-2
ST
entered cells by a CD4-dependent mechanism and replicated actively, cell-free transmission of the virus was retarded at the level of cell entry. These findings suggest that immunodeficiency viruses prevalent in West African populations are members of the HIV-2 virus group and that certain strains of this virus have attenuated virulence.
Cloning of a Lymphoid-Specific cDNA Encoding a Protein Binding the Regulatory Octamer DNA Motif
Authors: Staudt Louis M. , Clerc Roger G. , Singh Harinder , LeBowitz Jonathan H. , Sharp Phillip A. , Baltimore David
Published: October 2006

An octamer DNA sequence plays a critical role in directing transcription of immunoglobulin genes in B lymphocytes. A new technique of direct binding of radioactive DNA was used to screen a complementary DNA expression library from the BJAB cell line in λgt11 phage to derive molecular cDNA clones representing a putative B lymphocyte-specific octamer binding protein. The plaques were screened with DNA containing four copies of the octamer sequence and positive phage recombinants were identified. The fusion protein produced on inducing a lysogen of one phage bound to a monomeric octamer probe. The cDNA insert from this phage hybridized to messenger RNA found in B lymphocytes, but not in most other cells. Thus, this cDNA derives from a gene (
oct-2
) that specifies an octamer binding protein expressed preferentially in B lymphocytes, proving that, for at least one gene, a cell-specific transcription factor exists and its amount is controlled through messenger RNA availability.
Application of the Quail-Chick Chimera System to the Study of Brain Development and Behavior
Authors: Balaban Evan , Teillet Marie-Aimée , Le Douarin Nicole
Published: October 2006

Hatched chicks with chimeric brains containing cells from both the domestic chicken (
Gallus gallus domesticus
) and the Japanese quail (
Coturnix coturnix japonica
) have been produced by transplantation of various regions of the neural tube at the 8- to 15- somite stage. The positions of host and donor cells relative to graft boundaries observed throughout embryonic development and after hatching implicated both radial and tangential cell movements in brain morphogenesis. In addition, transplants containing the entire quail mesencephalon and diencephalon resulted in the transfer of certain aspects of species-typical crowing behavior.
Delay of Disease Development in Transgenic Plants That Express the Tobacco Mosaic Virus Coat Protein Gene
Authors: Abel Patricia Powell , Nelson Richard S. , De Barun , Hoffmann Nancy , Rogers Stephen G. , Fraley Robert T. , Beachy Roger N.
Published: October 2006

A chimeric gene containing a cloned cDNA of the coat protein (CP) gene of tobacco mosaic virus (TMV) was introduced into tobacco cells on a Ti plasmid of
Agrobacterium tumefaciens
from which tumor inducing genes had been removed. Plants regenerated from transformed cells expressed TMV mRNA and CP as a nuclear trait. Seedlings from self-fertilized transgenic plants were inoculated with TMV and observed for development of disease symptoms. The seedlings that expressed the CP gene were delayed in symptom development and 10 to 60 percent of the transgenic plants failed to develop symptoms for the duration of the experiments. Increasing the concentration of TMV in the inoculum shortened the delay in appearance of symptoms. The results of these experiments indicate that plants can be genetically transformed for resistance to virus disease development.
The Chronic Myelogenous Leukemia-Specific P210 Protein Is the Product of the
bcr
/
abl
Hybrid Gene
Authors: Ben-Neriah Yinon , Daley George Q. , Mes-Masson Anne-Marie , Witte Owen N. , Baltimore David
Published: October 2006

Chronic myelogenous leukemia (CML) is a human disease associated with a consistent chromosomal translocation that results in sequences from the c-
abl
locus on chromosome 9 being fused to sequences in a breakpoint cluster region (
bcr
) on chromosome 22. CML cells have two novel products: an 8.5-kilobase RNA transcript containing both
abl
and
bcr
and a 210-kilodalton phosphoprotein (P210) recognized by v-
abl
-specific antisera. To test whether the P210 is the product of the novel 8.5-kilobase
bcr
/
abl
fusion transcript, antibodies were prepared against c-
abl
and
bcr
determinants. By using these reagents and v-
abl
-specific antisera, it was demonstrated that the P210 in CML cells is indeed the protein product of the 8.5-kilobase transcript. By analogy to the
gag
/
abl
fusion protein of Abelson murine leukemia virus, the replacement of amino terminal c-
abl
sequences by
bcr
sequences in P210 may create a transforming protein involved in CML. A 190-kilodalton phosphoprotein that is a candidate for the normal
bcr
protein was identified in both HeLa and K562 cells.
Inhibition of Endothelial Regeneration by Type-Beta Transforming Growth Factor from Platelets
Authors: Heimark Ronald L. , Twardzik Daniel R. , Schwartz Stephen M.
Published: October 2006

Damage to the vessel wall is a signal for endothelial migration and replication and for platelet release at the site of injury. Addition of transforming growth factor-beta (TGF-β) purified from platelets to growing aortic endothelial cells inhibited [
3
H]thymidine incorporation in a concentration-dependent manner. A transient inhibition of DNA synthesis was also observed in response to wounding; cell migration and replication are inhibited during the first 24 hours after wounding. By 48 hours after wounding both TGF-β-treated and -untreated cultures showed similar responses. Flow microfluorimetric analysis of cell cycle distribution indicated that after 24 hours of exposure to TGF-β the cells were blocked from entering S phase, and the fraction of cells in G
1
was increased. The inhibition of the initiation of regeneration by TGF-β could allow time for recruitment of smooth muscle cells into the site of injury by other platelet components.
Implantation of Genetically Engineered Fibroblasts into Mice: Implications for Gene Therapy
Authors: Selden Richard F. , Skoskiewicz Marek J. , Howie Kathleen Burke , Russell Paul S. , Goodman Howard M.
Published: October 2006

In a variety of human genetic diseases, replacement of the absent or defective protein provides significant therapeutic benefits. As a model for a somatic cell gene therapy system, cultured murine fibroblasts were transfected with a human growth hormone (hGH) fusion gene and cells from one of the resulting clonal lines were subsequently implanted into various locations in mice. Such implants synthesized and secreted hGH, which was detectable in the serum. The function of the implants depended on their location and size, and on the histocompatibility of the donor cells with their recipients. The expression of hGH could be modified by addition of regulatory effectors, and, with appropriate immunosuppression, the implants survived for more than 3 months. This approach to gene therapy, here termed "transkaryotic implantation," is potentially applicable to many genetic diseases in that (i) the transfected cell line can be extensively characterized prior to implantation, (ii) several anatomical sites are suitable for implantation, and (iii) regulated expression of the gene of therapeutic interest can be obtained.
The Nucleocapsid of Hepatitis B Virus Is Both a T-Cell-Independent and a T-Cell-Dependent Antigen
Authors: Milich David R. , McLachlan Alan
Published: October 2006

One characteristic of the immune response during hepatitis B virus (HBV) infection in humans is the vigorous production and subsequent persistence of antibodies of immunoglobulin (Ig) classes M and G to the nucleocapsid antigen (HBcAg). In this study HBcAg was shown to be similarly immunogenic in mice. When injected into athymic (nude) B10.BR and athymic BALB/c mice, HBcAg induced IgM and IgG class antibodies to HBc in spite of the absence of T cells in nude mice. In euthymic mice, HBcAg efficiently stimulated T-cell proliferation in vitro and helper T-cell function in vivo. The dual functions of HBcAg as a T-cell-independent and a T-cell-dependent antigen may explain its enhanced immunogenicity. Denaturation of HBcAg yields a nonparticulate antigen designated HBeAg; when HBeAg was used as the immunogen, antibody production required helper T-cell function. Although HBcAg and HBeAg are serologically distinct, they are structurally related, and in these experiments were highly cross-reactive at the T-cell level. These results suggest that the elevated levels of IgM antibodies to HBc and the enhanced immunogenicity of HBcAg during HBV infection in humans reflect the ability of HBcAg to directly activate B cells to produce antibodies to HBc in the presence or absence of HBcAg- or HBeAg-sensitized T cells.
Human Monoclonal Antibodies to Pf 155, a Major Antigen of Malaria Parasite
Plasmodium falciparum
Authors: Udomsangpetch Rachanee , Lundgren Katarina , Berzins Klavs , Wåhlin Birgitta , Perlmann Hedvig , Troye-Blomberg Marita , Carlsson Jan , Wahlgren Mats , Perlmann Peter , Björkman Anders
Published: October 2006

Pf 155, a protein of the human malaria parasite
Plasmodium falciparum
, is strongly immunogenic in humans and is believed to be a prime candidate for the preparation of a vaccine. Human monoclonal antibodies to Pf 155 were obtained by cloning B cells that had been prepared from an immune donor and transformed with Epstein-Barr virus. When examined by indirect immunofluorescence, these antibodies stained the surface of infected erythrocytes, free merozoites, segmented schizonts, and gametocytes. They bound to a major polypeptide with a relative molecular weight of 155K and to two minor ones (135K and 120K), all having high affinity for human glycophorin. The antibodies strongly inhibited merozoite reinvasion in vitro, suggesting that they might be appropriate reagents for therapeutic administration in vivo.
The Application of Bone Marrow Transplantation to the Treatment of Genetic Diseases
Authors: Parkman Robertson
Published: October 2006

Genetic diseases can be treated by transplantation of either normal allogeneic bone marrow or, potentially, autologous bone marrow into which the normal gene has been inserted in vitro (gene therapy). Histocompatible allogeneic bone marrow transplantation is used for the treatment of genetic diseases whose clinical expression is restricted to lymphoid or hematopoietic cells. The therapeutic role of bone marrow transplantation in the treatment of generalized genetic diseases, especially those affecting the central nervous system, is under investigation. The response of a generalized genetic disease to allogeneic bone marrow transplantation may be predicted by experiments in vitro. Gene therapy can be used only when the gene responsible for the disease has been characterized. Success of gene therapy for a specific genetic disease may be predicted by its clinical response to allogeneic bone marrow transplantation.
Many Random Sequences Functionally Replace the Secretion Signal Sequence of Yeast Invertase
Authors: Kaiser Chris A. , Preuss Daphne , Grisafi Paula , Botstein David
Published: October 2006

In the process of protein secretion, amino-terminal signal sequences are key recognition elements; however, the relation between the primary sequence of an amino-terminal peptide and its ability to function as an export signal remains obscure. The limits of variation permitted for functional signal sequences were determined by replacement of the normal signal sequence of
Saccharomyces cerevisiae
invertase with essentially random peptide sequences. Since about one-fifth of these sequences can function as an export signal the specificity with which signal sequences are recognized must be very low.
Prediction of Chemical Carcinogenicity in Rodents from in Vitro Genetic Toxicity Assays
Authors: Tennant Raymond W. , Margolin Barry H. , Shelby Michael D. , Zeiger Errol , Haseman Joseph K. , Spalding Judson , Caspary William , Resnick Michael , Stasiewicz Stanley , Anderson Beth , Minor Robert
Published: October 2006

Four widely used in vitro assays for genetic toxicity were evaluated for their ability to predict the carcinogenicity of selected chemicals in rodents. These assays were mutagenesis in
Salmonella
and mouse lymphoma cells and chromosome aberrations and sister chromatid exchanges in Chinese hamster ovary cells. Seventy-three chemicals recently tested in 2-year carcinogenicity studies conducted by the National Cancer Institute and the National Toxicology Program were used in this evaluation. Test results from the four in vitro assays did not show significant differences in individual concordance with the rodent carcinogenicity results; the concordance of each assay was approximately 60 percent. Within the limits of this study there was no evidence of complementarity among the four assays, and no battery of tests constructed from these assays improved substantially on the overall performance of the
Salmonella
assay. The in vitro assays which represented a range of three cell types and four end points did show substantial agreement among themselves, indicating that chemicals positive in one in vitro assay tended to be positive in the other in vitro assays.
Recruitment of Enzymes as Lens Structural Proteins
Authors: Wistow Graeme , Piatigorsky Joram
Published: October 2006

Crystallins, the principal components of the lens, have been regarded simply as soluble, structural proteins. It now appears that the major taxon-specific crystallins of vertebrates and invertebrates are either enzymes or closely related to enzymes. In terms of sequence similarity, size, and other physical characteristics δ-crystallin is closely related to argininosuccinate lyase, τ-crystallin to enolase, and S
III
-crystallin to glutathione S-transferase; moreover, it has recently been demonstrated that ε-crystallin is an active lactate dehydrogenase. Enzymes may have been recruited several times as lens proteins, perhaps because of the developmental history of the tissue or simply because of evolutionary pragmatism (the selection of existing stable structures for a new structural role).
Implications of RNA⋅RNA Splicing in Evolution of Eukaryotic Cells
Authors: Darnell James E.
Published: October 2006

The differences in the biochemistry of messenger RNA formation in eukaryotes compared to prokaryotes are so profound as to suggest that sequential prokaryotic to eukaryotic cell evolution seems unlikely. The recently discovered noncontiguous sequences in eukaryotic DNA that encode messenger RNA may reflect an ancient, rather than a new, distribution of information in DNA and that eukaryotes evolved independently of prokaryotes.
Heparin Promotes the Inactivation of Antithrombin by Neutrophil Elastase
Authors: Jordan Robert E. , Kilpatrick Jaleh , Nelson Richard M.
Published: October 2006

Heparin is an acceleratory cofactor for antithrombin, a circulating inhibitor of blood coagulation enzymes. The presence of heparin on blood vessel walls is believed to contribute to the nonthrombogenic properties of those surfaces. In apparent opposition to this function, heparin was found to greatly accelerate the in vitro inactivation of antithrombin by neutrophil elastase. Inactivation rates in solution were potentiated several hundredfold by specific heparin fractions with anticoagulant activity. Although the data suggest that a heparin-antithrombin complex is essential for the inactivation by elastase to occur, the enzyme itself interacts tightly with heparin. These results suggest a mechanism which, if operating in vivo, could lead to a localized neutralization of the anticoagulant function of heparin at the endothelial surface.
A Cell-Cycle Constraint on the Regulation of Gene Expression by Platelet-Derived Growth Factor
Authors: Rollins Barrett J. , Morrison Elizabeth D. , Stiles Charles D.
Published: October 2006

In density-arrested monolayer cultures of Balb/c 3T3 cells, platelet-derived growth factor (PDGF) stimulates expression of the c-
myc
and c-
fos
proto-oncogenes, as well as the functionally uncharacterized genes, JE, KC, and JB. These genes are not coordinately regulated. Under ordinary conditions, c-
fos
, JE, KC, and JB respond to PDGF only when the cells are in a state of G
0
growth arrest at the time of PDGF addition. The c-
myc
gene is regulated in opposition to the other genes, responding best to PDGF in cycling cultures.
Protein Kinase C Contains a Pseudosubstrate Prototope in Its Regulatory Domain
Authors: House Colin , Kemp Bruce E.
Published: October 2006

The regulatory domain of protein kinase C contains an amino acid sequence between residues 19 and 36 that resembles a substrate phosphorylation site in its distribution of basic residue recognition determinants. The corresponding synthetic peptide (Arg
19
-Phe-Ala-Arg-Lys-Gly-
Ala
25
-Leu-Arg-Gln-Lys-Asn-Val-His-Glu-Val-Lys-Asn
36
) acts as a potent substrate antagonist with an inhibitory constant of 147 ± 9 n
M
. It is a specific inhibitor of protein kinase C and inhibits both autophosphorylation and protein substrate phosphorylation. Substitution of Ala
25
with serine transforms the pseudosubstrate into a potent substrate. These results demonstrate that the conserved region of the regulatory domain (residues 19 to 36) of protein kinase C has the secondary structural features of a pseudosubstrate and may be responsible for maintaining the enzyme in the inactive form in the absence of allosteric activators such as phospholipids.
High Resolution of Mouse Chromosomes: Banding Conservation Between Man and Mouse
Authors: Sawyer Jeffrey R. , Hozier John C.
Published: October 2006

A detailed schematic representation of high-resolution G-banding patterns was prepared from elongated and finely banded mitotic chromosomes of the mouse. Such chromosomes can be obtained from both animal tissue and cell lines by a simple protocol, facilitating precise demarcation of breakpoints in chromosome rearrangements and aiding in the sublocalization of genes. Regions of subbanding homology were observed between human and mouse chromosomal segments known to have conserved gene assignments, an indication that, at the cytogenetic level, extensive regions of the mammalian genome may remain intact after 60 million years of species divergence.
The Use of NMR Spectroscopy for the Understanding of Disease
Authors: Radda George K.
Published: October 2006

Nuclear magnetic resonance spectroscopy can now be used to investigate the biochemical energetics of human tissues and organs noninvasively. The method already has increased our understanding of some muscle diseases, has provided information from muscle metabolism about whole-body functions, control, and hormonal status, has helped in the elucidation of hitherto unrecognized causes of disease, and yielded new ideas about the control of bioenergetics in vivo. Studies on the biochemistry of human brain, liver, heart, and kidney are just beginning. Further investigations of well-selected patients are likely to bring biochemistry and clinical practice closer together.
Physical Factors Affecting the Mutagenicity of Fly Ash from a Coal-Fired Power Plant
Authors: Fisher G. L. , Chrisp C. E. , Raabe O. G.
Published: October 2006

The two finest, most respirable coal fly ash fractions collected from the smokestack of a power plant were more mutagenic than two coarser fractions. Mutagenicity was evaluated in the histidine-requiring bacterial strains TA 1538, TA 98, and TA 100 of
Salmonella typhimurium
. Ash samples collected from the hoppers of an electrostatic precipitator in the plant were not mutagenic. The mutagens in coal fly ash were resistant to x-ray or ultraviolet irradiation, possibly as a result of stabilization by fly ash surfaces. All mutagenic activity is lost with heating to 350°C.
Age and Infertility
Authors: Menken Jane , Trussell James , Larsen Ulla
Published: October 2006

Direct evidence on age patterns of infecundity and sterility cannot be obtained from contemporary populations because such large fractions of couples use contraception or have been sterilized. Instead, historical data are exploited to yield upper bounds applicable to contemporary populations on the proportions sterile at each age. Examination of recent changes in sexual behavior that may increase infecundity indicates that sexually transmitted infections, the prime candidate for hypothesized rises in infertility, are unlikely to have added to infecundity to any great extent. These results imply that a woman in a monogamous union faces only moderate increases in the probability of becoming sterile (or infecund) until her late thirties. Nevertheless, it appears that recent changes in reproductive behavior were guaranteed to result in the perception that infecundity is on the rise.
Distribution of Airborne Radon-222 Concentrations in U.S. Homes
Authors: Nero A. V. , Schwehr M. B. , Nazaroff W. W. , Revzan K. L.
Published: October 2006

Apparently large exposures of the general public to the radioactive decay products of radon-222 present in indoor air have led to systematical appraisal of monitoring data from U.S. single-family homes; several ways of aggregating data were used that take into account differences in sample selection and season of measurements. The resulting distribution of annual-average radon-222 concentrations can be characterized by an arithmetic mean of 1.5 picocurie per liter (55 becquerels per cubic meter) and a long tail with 1 to 3% of homes exceeding 8 picocuries per liter, or by a geometric mean of 0.9 picocurie per liter and a geometric standard deviation of about 2.8. The standard deviation in the means is 15%, estimated from the number and variability of the available data sets, but the total uncertainty is larger because these data may not be representative. Available dose-response data suggest that an average of 1.5 picocuries per liter contributes about 0.3% lifetime risk of lung cancer and that, in the million homes with the highest concentrations, where annual exposures approximate or exceed those received by underground uranium miners, long-term occupants suffer an added lifetime risk of at least 2%, reaching extraordinary values at the highest concentrations observed.