bluuebunny/crossref_metadata_2025 huggingface dataset:
A Mammalian Host-Vector System That Regulates Expression and Amplification of Transfected Genes by Temperature Induction
Authors: Rio Donald C. , Clark Scott G. , Tjian Robert
Published: October 2006

SV40-transformed simian cells that permit temperature-dependent regulation of vector DNA replication were isolated and characterized. These cell lines (ts COS cells) produce high levels of thermolabile large T antigen under the transcriptional control of the Rous sarcoma virus long terminal repeat. The ts COS cell lines can complement SV40 A gene mutants and support replication of SV40-origin containing vectors at 33°C but not at 40°C. It should now be possible to regulate the copy number of transfected plasmid DNA's and also maintain selectable vector sequences either as integrated DNA or as autonomously replicating episomes by modulating T antigen activity in ts COS cells.
Bovine Leukemia Virus Long Terminal Repeat: A Cell Type-Specific Promoter
Authors: Derse David , Caradonna Salvatore J. , Casey James W.
Published: October 2006

The functional activity of the promoter unit contained within the long terminal repeat (LTR) of bovine leukemia virus (BLV) was examined by monitoring transient expression of a heterologous gene placed under its control. Various cell lines were transfected with recombinant plasmids carrying the bacterial chloramphenicol acetyltransferase (CAT) gene coupled to the BLV LTR (pBL-cat). Transient expression of CAT activity directed by the BLV LTR was observed only in the established BLV-producer cell lines derived from fetal lamb kidney (FLK) cells and bat lung cells. The amount of CAT activity transiently expressed in FLK-BLV cells was decreased approximately tenfold by deletion of LTR sequences located within a region 100 to 170 nucleotides upstream of the RNA start site. Surprisingly, removal of the region 50 base pairs downstream of the RNA initiation site to the 3′-end of the LTR reduced the expression of CAT activity by 87 percent. The BLV LTR thus appears to be an unusual promoter unit, functioning in a cell type-specific manner and possessing sequences on both the 5′ and 3′ sides of the RNA start site that influence gene expression.
Induction of DNA Synthesis in Cultured Rat Hepatocytes Through Stimulation of α
1
Adrenoreceptor by Norepinephrine
Authors: Cruise Jennifer L. , Houck Keith A. , Michalopoulos George K.
Published: October 2006

Addition of norepinephrine to primary cultures of adult rat hepatocytes stimulates the incorporation of [
3
H]thymidine in a dose-dependent manner. This effect has been observed in serum-free medium containing epidermal growth factor and insulin. Stimulation of DNA synthesis by norepinephrine was strongly antagonized by the α
1
-adrenergic antagonist prazosin but not by an α
2
antagonist or by a β-adrenergic blocker. The β agonist isoproterenol did not stimulate significant DNA synthesis. These results indicate that catecholamines interact with the α
1
adrenoreceptor to stimulate DNA synthesis in hepatocytes. Since α
1
receptors are present in most cells, this receptor may be important in cell growth regulation.
Characterization of Envelope and Core Structural Gene Products of HTLV-III with Sera from AIDS Patients
Authors: Robey W. Gerard , Safai Bijan , Oroszlan Stephen , Arthur Larry O. , Gonda Matthew A. , Gallo Robert C. , Fischinger Peter J.
Published: October 2006

The envelope (
env
) and structural (
gag
) gene products of human T-cell leukemia (lymphotropic) virus type III were identified by immunoaffinity chromatography, immunoprecipitation, and two-dimensional oligopeptide mapping methods. The
env
gene specifies a glycosylated polypeptide with a molecular weight of 160,000 (gp160) that is processed to gp120 and smaller gene products. The
gag
gene specifies two polypeptides of 70,000 and 55,000 molecular weight (p70 and p55), both of which contain p24, the major structural protein of the mature virion. The techniques in this study can be used to define the extent of variability of the
env
gene product among different virus isolates and may identify the nature and patterns of the humoral immune response that lead to an immunologically protected state.
Human Apolipoprotein B: Structure of Carboxyl-Terminal Domains, Sites of Gene Expression, and Chromosomal Localization
Authors: Knott Timothy J. , Rall Stanley C. , Innerarity Thomas L. , Jacobson Shellie F. , Urdea Mickey S. , Levy-Wilson Beatriz , Powell Lyn M. , Pease Richard J. , Eddy Roger , Nakai Hiroshi , Byers Mary , Priestley Linda M. , Robertson Elaine , Rall Leslie B. , Betsholtz Christer , Shows Thomas B. , Mahley Robert W. , Scott James
Published: October 2006

Apolipoprotein (apo-) B is the ligand responsible for the receptor-mediated catabolism of low density lipoproteins, the principal cholesterol-transporting lipoproteins in plasma. The primary structure of the carboxyl-terminal 30 percent (1455 amino acids) of human apo-B (apo-B100) has been deduced from the nucleotide sequence of complementary DNA. Portions of the protein structure that may relate to its receptor binding function and lipid binding properties have been identified. The apo-B100 messenger RNA is about 19 kilobases in length. The apo-B100 gene is expressed primarily in liver and, to a lesser extent, in small intestine, but in no other tissues. The gene for apo-B100 is located in the p24 region (near the tip of the short arm) of chromosome 2.
A new HTLV-III/LAV Encoded Antigen Detected by Antibodies from AIDS Patients
Authors: Allan Jonathan S. , Coligan John E. , Lee Tun-Hou , McLane Mary Frances , Kanki Phyllis J. , Groopman Jerome E. , Essex Myron
Published: October 2006

A newly identified protein from HTLV-III/LAV, the virus implicated as the etiologic agent of the acquired immune deficiency syndrome, was studied. This protein, which has a molecular weight of 27,000 (p27), was shown by amino acid sequencing to have a coding origin 3′ to the env gene on the HTLV-III genome. The presence of antibodies to p27 in virus-exposed individuals indicated that this gene is functional in the natural host.
Isolation of T-Lymphotropic Retrovirus Related to HTLV-III/LAV from Wild-Caught African Green Monkeys
Authors: Kanki P. J. , Alroy J. , Essex M.
Published: October 2006

Present evidence suggests that the acquired immune deficiency syndrome (AIDS) emerged in Central Africa as a new disease in recent decades. This disease has recently approached epidemic proportions in many parts of the world. The etiologic agent of AIDS is believed to be the virus HTLV-III/LAV, which has been proposed as having originated from a recent simian-human transmission in Africa. This report describes the isolation of a designated STLV-III
AGM
retrovirus closely related to HTLV-III/LAV from seven healthy wild-caught African Green monkeys (
Cercopithecus aethiops
) that showed the presence of antibodies designated STLV-III
AGM
. In vitro growth characteristics, ultrastructural morphology, and major proteins of 160,000 kilodaltons (kD), 120 kD, 55 kD, and 24 kD are similar to and cross-reactive with the analogous antigens of HTLV-III/LAV. The use of these serologic markers in the detection of STLV-III
AGM
-infected monkeys may be important in assuring the continued safety of a variety of biologic reagents that are derived from these primate species. The existence of a retrovirus closely related to HTLV-III/LAV that naturally infects an African nonhuman primate in the apparent absence of disease may provide a unique model for the study of human AIDS and the development of an effective vaccine.
Prostacyclin Stimulation of the Activation of Blood Coagulation Factor X by Platelets
Authors: Dutta-Roy Asim K. , Ray Tarun K. , Sinha Asru K.
Published: October 2006

When platelets were incubated with prostacyclin, prostaglandin E
1
, or prostaglandin D
2
at concentrations insufficient to increase the level of adenosine 3′,5′-monophosphate (cyclic AMP), coagulation factor X was activated by a platelet cysteine protease. Prostacyclin or prostaglandin E
1
at higher concentrations increased the cyclic AMP level and inhibited the activation of factor X by platelets. Inhibition of platelet adenylate cyclase by 2′,5′-dideoxyadenosine allowed the activation of the protease at higher concentrations of the autocoids. Prostaglandins A
1
, A
2
, B
1
, B
2
, E
2
, F
2α
, 6-keto-prostaglandin F
1α
, and thromboxane B
2
, which do not affect platelet cyclic AMP level, did not stimulate the protease.
Irreversible Block of the Mycelial-to-Yeast Phase Transition of
Histoplasma capsulatum
Authors: Medoff Gerald , Sacco Margherita , Maresca Bruno , Schlessinger David , Painter Audrey , Kobayashi George S. , Carratu Luisella
Published: October 2006

p
-Chloromercuriphenylsulfonic acid (PCMS), a sulfhydryl inhibitor, prevented the mycelial-to-yeast transition of the dimorphic fungal pathogen,
Histoplasma capsulatum
. The effect of PCMS was specific for the mycelial-to-yeast transformation; it had no effect on growth of either the yeast or mycelial forms or on the yeast-to-mycelial transition. The failure of PCMS-treated mycelia to transform to yeast was permanent and irreversible. PCMS-treated mycelia could not infect mice but could stimulate resistance to infection by a pathogenic strain of
Histoplasma capsulatum
. These results suggest a new general strategy for vaccine development in diseases caused by dimorphic pathogens.
Nucleotide Sequence of SRV-1, a Type D Simian Acquired Immune Deficiency Syndrome Retrovirus
Authors: Power Michael D. , Marx Preston A. , Bryant Martin L. , Gardner Murray B. , Barr Philip J. , Luciw Paul A.
Published: October 2006

Simian acquired immune deficiency syndrome (SAIDS) in the macaque genus of monkeys at the California Primate Research Center is apparently caused by infection by a type D retrovirus. The complete nucleotide sequence (8173 base pairs) of a molecular clone of the prototype SAIDS virus isolate, SRV-1, reveals a typical retrovirus structure with long terminal repeats (346 base pairs) and open reading frames for the
gag
(663 codons),
pol
(867 codons), and
env
(605 codons) genes. SRV-1 also has a separate open reading frame of 314 codons between the
gag
and
pol
genes that defines the viral protease gene (
prt
) and a short open reading frame of unknown significance downstream from the
env
gene. The SRV-1 protease region shows a high degree of homology to its counterpart in the hamster intracisternal A-type particle genome; both these protease genes are about twice as long as the analogous region of other retroviruses. SRV-1 has no notable similarity in either genetic organization or sequence to the human AIDS retroviruses.
Regulation of Class III Major Histocompatibility Complex Gene Products by Interleukin-1
Authors: Perlmutter David H. , Goldberger Gabriel , Dinarello Charles A. , Mizel Steven B. , Colten Harvey R.
Published: October 2006

Interleukin-1 (IL-1) is a product of mononuclear phagocytes that mediates changes characteristic of the response to inflammation or tissue injury (the acute-phase response). One of two structurally and functionally homologous major histocompatibility complex (MHC) class III genes encodes a positive acute-phase protein, complement factor B. The closely linked complement C2 gene is not affected during the acute-phase response. Purified human IL-1,
p
H 7.0, and recombinant-generated murine IL-1,
p
H 5.0, increased the expression of factor B and other positive acute-phase proteins in human hepatoma cells but decreased the expression of albumin, a negative acute-phase reactant. Furthermore, in a murine fibroblast L-cell line transfected with cosmid DNA bearing the human C2 and factor B genes, IL-1 mediated a reversible dose- and time-dependent increase in factor B expression in the transfected cells. Expression of the C2 gene was not affected by IL-1. The effect of IL-1 on factor B expression involves a mechanism acting at a pre-translational level as demonstrated by an increase in specific messenger RNA content and a corresponding increase in biosynthesis and secretion of factor B. The structural basis and mechanism for selective and independent regulation of these genes provides insight into the molecular control of the inflammatory response.
A Selective Imidazobenzodiazepine Antagonist of Ethanol in the Rat
Authors: Suzdak Peter D. , Glowa John R. , Crawley Jacqueline N. , Schwartz Rochelle D. , Skolnick Phil , Paul Steven M.
Published: October 2006

Ethanol, at pharmacologically relevant concentrations of 20 to 100 mM, stimulates γ-aminobutyric (GABA) receptor-mediated uptake of
36
Cl-labeled chlorine into isolated brain vesicles. One drug that acts at GABA-benzodiazepine receptors, the imidazobenzodiazepine Ro15-4513, has been found to be a potent antagonist of ethanol-stimulated
36
Cl
-
uptake into brain vesicles, but it fails to antagonize either pentobarbital- or muscimol-stimulated
36
Cl
-
uptake. Pretreatment of rats with Ro15-4513 blocks the anticonflict activity of low doses of ethanol (but not pentobarbital) as well as the behavioral intoxication observed with higher doses of ethanol. The effects of Ro15-4513 in antagonizing ethanol-stimulated
36
Cl
-
uptake and behavior are completely blocked by benzodiazepine receptor antagonists. However, other benzodiazepine receptor inverse agonists fail to antagonize the actions of ethanol in vitro or in vivo, suggesting a novel interaction of Ro15-4513 with the GABA receptor-coupled chloride ion channel complex. The identification of a selective benzodiazepine antagonist of ethanol-stimulated
36
Cl
-
uptake in vitro that blocks the anxiolytic and intoxicating actions of ethanol suggests that many of the neuropharmacologic actions of ethanol may be mediated via central GABA receptors.
Retroviruses and Mouse Embryos: A Rapid Model for Neurovirulence and Transplacental Antiviral Therapy
Authors: Sharpe Arlene H. , Jaenisch Rudolf , Ruprecht Ruth M.
Published: October 2006

A murine model in which neurotropic retroviral infection can be studied over short periods of time was developed. Microinjection of Cas-Br-E virus into midgestation mouse embryos caused paralysis and death within 25 days after birth, in contrast to virus-infected neonates which develop disease only after 4 months. To evaluate whether antiviral drugs could cross the placental barrier and influence the course of the disease, the drug 3′-azido-3′-deoxythymidine (AZT) was administered to infected embryos through the drinking water of pregnant females. AZT treatment markedly retarded the onset and course of virus-induced central nervous system disease, permitting animals to survive beyond 4 months of age. These results are evidence for effective antiviral treatment during gestation and in the perinatal period and are of potential significance for the management of maternal transmission of the acquired immune deficiency syndrome (AIDS) virus.
Cell-Autonomous Determination of Cell-Type Choice in
Dictyostelium
Development by Cell-Cycle Phase
Authors: Gomer Richard H. , Firtel Richard A.
Published: October 2006

The developmental fate of individual cells has been examined in a system that allows
Dictyostelium discoideum
cells to differentiate in the absence of aggregation. The results show that the propensity of single amoebae to differentiate into either prespore or prestalk cells occurs by a cell-autonomous mechanism dependent on the cell's position in the cell cycle at the initiation of development. Cells that divide between ∼1 1/2 hours before and ∼40 minutes after the differentiation-inducing starvation become prestalk, whereas cells dividing at other times become prespore cells. These results suggest mechanisms by which an initial proportioning of the two cell types within the aggregate is achieved.
Breast Cancer-Associated pS2 Protein: Synthesis and Secretion by Normal Stomach Mucosa
Authors: Rio M. C. , Bellocq J. P. , Daniel J. Y. , Tomasetto C. , Lathe R. , Chenard M. P. , Batzenschlager A. , Chambon P.
Published: October 2006

The human pS2 gene is specifically expressed under estrogen transcriptional control in a subclass of estrogen receptor-containing human breast cancer cells. The pS2 gene encodes an 84-amino acid protein that is secreted after signal peptide cleavage. The distribution of pS2 protein in normal human tissues was studied with antibodies to pS2; pS2 was specifically expressed and secreted by mucosa cells of the normal stomach antrum and body of both female and male individuals. Moreover, no estrogen receptor could be detected in these cells, indicating that pS2 gene expression is estrogen-independent in the stomach. The function of the pS2 protein in the gastrointestinal tract is unknown. However, the pS2 protein is similar in sequence to a porcine pancreatic protein that has been shown to inhibit gastrointestinal motility and gastric secretion.
Cytokines Alter Production of HIV-1 from Primary Mononuclear Phagocytes
Authors: Koyanagi Yoshio , O'Brien William A. , Zhao Jia Qi , Golde David W. , Gasson Judith C. , Chen Irvin S. Y.
Published: October 2006

Some strains of human immunodeficiency virus type 1 (HIV-1) can infect primary monocytes and monocyte-derived macrophages in vitro. In this report, the effect of cytokines on the production of one of these strains that shows a tropism for mononuclear phagocytes, designated HIV-1
JR-FL
, was studied. Primary peripheral blood mononuclear phagocytes infected with HIV-1
JR-FL
were treated with the hematopoietic factors: granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), macrophage colony-stimulating factor (M-CSF), and γ-interferon (γ-IFN). The M-CSF, GM-CSF, IL-3, and γ-IFN were able to alter HIV-1 production under different conditions.
DNA Diagnostics—Molecular Techniques and Automation
Authors: Landegren Ulf , Kaiser Robert , Caskey C. Thomas , Hood Leroy
Published: October 2006

Molecular biology has revolutionized the understanding of many aspects of human disease. Ongoing developments in DNA diagnostics—the analysis of disease at the nucleic acid level—will soon provide automated, rapid, and inexpensive analyses for DNA or RNA sequences associated with genetic, malignant, and infectious diseases. DNA diagnostics will also facilitate the identification of disease-associated genes at birth, thus creating new opportunities for preventive medicine.
Antibodies to Asp-Asp-Glu-Asp Can Inhibit Transport of Nuclear Proteins into the Nucleus
Authors: Yoneda Yoshihiro , Imamoto-Sonobe Naoko , Matsuoka Yosuke , Iwamoto Ryo , Kiho Yukio , Uchida Tsuyoshi
Published: October 2006

The signal sequence of simian virus 40 (SV40) large T-antigen for translocation into the nucleus is composed of positively charged amino acids Lys-Lys-Lys-Arg-Lys. Rabbit antibodies to a synthetic peptide containing the negatively charged amino acid sequence Asp-Asp-Asp-Glu-Asp were obtained. Indirect immunofluorescence of the antigens recognized by the antibody was punctate at the nuclear rim or the nuclear surface, depending on the plane of focus. The antibody blocked transport of nuclear proteins into the nucleus. The antigens recognized by the antibody were predominantly localized to the nuclear pores.
The Neural Basis for Learning of Simple Motor Skills
Authors: Lisberger Stephen G.
Published: October 2006

The vestibulo-ocular reflex (VOR) is a simple movement that has been used to investigate the neural basis for motor learning in monkeys. The function of the VOR is to stabilize retinal images by generating smooth eye movements that are equal and opposite to each head movement. Learning occurs whenever image motion occurs persistently during head turns; as a result image stability is gradually restored. A hypothesis is proposed in which the output from the cerebellar cortex of the flocculus guides learning; the locus of learning is in the brain stem, in VOR pathways that are under inhibitory control from the flocculus. Other, parallel VOR pathways do not receive inputs from the flocculus and are not subject to learning. Similarities among the VOR and other motor systems suggest some organizing principles that may apply in many forms of motor learning.
Scientific Standards in Epidemiologic Studies of the Menace of Daily Life
Authors: Feinstein Alvan R.
Published: October 2006

Many substances used in daily life, such as coffee, alcohol, and pharmaceutical treatment for hypertension, have been accused of "menace" in causing cancer or other major diseases. Although some of the accusations have subsequently been refuted or withdrawn, they have usually been based on statistical associations in epidemiologic studies that could not be done with the customary experimental methods of science. With these epidemiologic methods, however, the fundamental scientific standards used to specify hypotheses and groups, get high-quality data, analyze attributable actions, and avoid detection bias may also be omitted. Despite peer-review approval, the current methods need substantial improvement to produce trustworthy scientific evidence.
Cloned Gene of
Rickettsia rickettsii
Surface Antigen: Candidate Vaccine for Rocky Mountain Spotted Fever
Authors: McDonald Gregory A. , Anacker Robert L. , Garjian Kareen
Published: October 2006

Two major protective antigens of
Rickettsia rickettsii
have been previously described. In this study, we cloned the gene encoding one of these antigens into
Escherichia coli
and tested the effectiveness of the recombinant-made product as a vaccine for Rocky Mountain spotted fever. A clone bank of R strain
R. rickettsii
DNA was made in
E. coli
K-12 by using the plasmid vector pBR322. Transformants were screened for their ability to make rickettsial antigens by reactivity with rabbit antibodies to
R. rickettsii
. One of the transformants, EM24(pGAM21), made a product reactive with two monoclonal antibodies that recognize a 155-kilodalton protein of
R. rickettsii
. One of the monoclonal antibodies was a member of a class of antibodies that react to heat-sensitive epitopes and protect mice injected with a potentially lethal dose of viable
R. rickettsii
. The cloned product contained this protective heat-sensitive epitope. In order to obtain enhanced expression, the gene was subcloned downstream of the lactose promoter on the plasmid vector pUC8. A sonic lysate of
E. coli
harboring the pUC8 subclone was used successfully as a vaccine to protect mice injected with a lethal dose of the viable
R. rickettsii
.
Allelic Exclusion in Transgenic Mice That Express the Membrane form of Immunoglobulin μ
Authors: Nussenzweig Michel C. , Shaw Albert C. , Sinn Eric , Danner David B. , Holmes Kevin L. , Morse Herbert C , Leder Philip
Published: October 2006

Antibody-producing cells display a special form of regulation whereby each cell produces immunoglobulin from only one of its two sets of antibody genes. This phenomenon, called allelic exclusion, is thought to be mediated by the product of one heavy chain allele restricting the expression of the other. Heavy chains are synthesized in two molecular forms, secreted and membrane bound. In order to determine whether it is specifically the membrane-bound form of the immunoglobulin M (IgM) heavy chain (μ) that mediates this regulation, transgenic mice were created that carry a human μ chain gene altered so that it can only direct the synthesis of the membrane-bound protein. The membrane-bound form of the human μ chain was made by most of the B cells in these animals as measured by assays of messenger RNA and surface immunoglobulins. Further, the many B cells that express the human gene do not express endogenous mouse IgM, and the few B cells that express endogenous mouse μ do not express the transgene. Thus, the membrane-bound form of the μ chain is sufficient to mediate allelic exclusion. In addition, the molecular structures recognized for this purpose are conserved between human and mouse systems.
The Primary Structure and Heterogeneity of Tau Protein from Mouse Brain
Authors: Lee Gloria , Cowan Nicholas , Kirschner Marc
Published: October 2006

Tau protein is a family of microtubule binding proteins, heterogeneous in molecular weight, that are induced during neurite outgrowth and are found prominently in neurofibrillary tangles in Alzheimer's disease. The predicted amino acid sequences of two forms of tau protein from mouse brain were determined from complementary DNA clones. These forms are identical in their amino-terminal sequences but differ in their carboxyl-terminal domains. Both proteins contain repeated sequences that may be tubulin binding sites. The sequence suggests that tau is an elongated molecule with no extensive α-helical or β-sheet domains. These complementary DNAs should enable the study of various functional domains of tau and the study of tau expression in normal and pathological states.
Germline Transformation Used to Define Key Features of Heat-Shock Response Elements
Authors: Xiao Hua , Lis John T.
Published: October 2006

The heat-shock consensus element (HSE), CTNGAANNTTCNAG, is found in multiple copies upstream of all heat-shock genes. Here, the sequence requirements for heat-shock induction are tested by
Drosophila
germline transformation with an
hsp
70-
lacZ
gene fused to a pair of synthetic HSEs. Certain single-base substitutions in either HSE cause a dramatic reduction (fortyfold) in expression. Surprisingly, variations in sequences immediately flanking the HSEs also reduced levels of induction. One such variant that contains two perfect 14-base pair HSEs, which are correctly spaced relative to each other and the TATA box, retained only 7% of wild type-induced expression. These and additional analyses indicate that the heat-shock regulatory element includes sequences beyond the 14-base pair HSE and may be better described as a dimer of a 10-base pair sequence, NTTCNNGAAN.
Hawaiian Courtship Songs: Evolutionary Innovation in Communication Signals of
Drosophila
Authors: Hoy Ronald R. , Hoikkala Anneli , Kaneshiro Kenneth
Published: October 2006

In Hawaii, flies of the genus
Drosophila
have undergone spectacular adaptive radiation, resulting in the evolution of more than 500 species of
Drosophila
that are found nowhere else on earth. This taxonomic uniqueness is reflected in behavior and morphology. Hawaiian Drosophila sing songs, as do continental
Drosophila
; however, the Hawaiian songs have diverged strongly in form and mechanism of production. The click-song of
D. fasciculisetae
(Maui) has a carrier frequency an order of magnitude higher than those reported in familiar continental species, such as
D. melanogaster
(170 hertz).
Drosophila fasciculisetae
's song resembles a cicada's more than a fly's song. The song of
D. cyrtoloma
(Maui) has a complex pulse rhythm more typical of crickets than flies. The pulse song of
D. silvestris
(Hawaii) closely resembles that of
D. melanogaster
in both pulse rhythm and carrier frequency, but D. melanogaster sings by vibrating its wings, whereas
D. silvestris
sings through abdominal vibrations. These mechanisms are radical departures from the continental wing song mechanism and are further examples of the remarkable behavioral innovation that has occurred in the
Drosophila
of Hawaii during their evolutionary transit through these islands.
Site of G Protein Binding to Rhodopsin Mapped with Synthetic Peptides from the α Subunit
Authors: Hamm Heidi E. , Deretic Dusanka , Arendt Anatol , Hargrave Paul A. , Koenig Bernd , Hofmann Klaus P.
Published: October 2006

The interaction between receptors and guanine nucleotide binding (G) proteins leads to G protein activation and subsequent regulation of effector enzymes. The molecular basis of receptor-G protein interaction has been examined by using the ability of the G protein from rods (transducin) to cause a conformational change in rhodopsin as an assay. Synthetic peptides corresponding to two regions near the carboxyl terminus of the G protein α subunit, Glu
311
-Val
328
and Ile
340
-Phe
350
, compete with G protein for interaction with rhodopsin. Amino acid substitution studies show that Cys
321
is required for this effect. Ile
340
-Phe
350
and a modified peptide, acetyl-Glu
311
-Lys
329
-amide, mimic G protein effects on rhodopsin conformation, showing that these peptides bind to and stabilize the activated conformation of rhodopsin.
IκB: a Specific Inhibitor of the NF-κB Transcription Factor
Authors: Baeuerle Patrick A. , Baltimore David
Published: October 2006

In cells that do not express immunoglobulin kappa light chain genes, the kappa enhancer binding protein NF-κB is found in cytosolic fractions and exhibits DNA binding activity only in the presence of a dissociating agent such as sodium deoxycholate. The dependence on deoxycholate is shown to result from association of NF-κB with a 60- to 70-kilodalton inhibitory protein (IκB). The fractionated inhibitor can inactivate NF-κB from various sources—including the nuclei of phorbol ester-treated cells—in a specific, saturable, and reversible manner. The cytoplasmic localization of the complex of NF-κB and IκB was supported by enucleation experiments. An active phorbol ester must therefore, presumably by activation of protein kinase C, cause dissociation of a cytoplasmic complex of NF-κB and IκB by modifying IκB. This releases active NF-κB which can translocate into the nucleus to activate target enhancers. The data show the existence of a phorbol ester-responsive regulatory protein that acts by controlling the DNA binding activity and subcellular localization of a transcription factor.
Alignment of Rat Cardionatrin Sequences with the Preprocardionatrin Sequence from Complementary DNA
Authors: Flynn T. G. , Davies P. L. , Kennedy B. P. , de Bold M. L. , de Bold A. J.
Published: October 2006

Mammalian atria contain peptides that promote the excretion of salt and water from the kidney. When rat atrial tissue is extracted under conditions known to inhibit proteolysis, four natriuretic peptides, cardionatrins I to IV, are consistently isolated. These peptides derive from a common precursor, preprocardionatrin, of 152 amino acids, whose sequence was determined by DNA sequencing of a complementary DNA clone. Amino acid sequencing located the start points of cardionatrins I, III, and IV in the overall sequence. Cardionatrin IV most closely resembles procardionatrin because it begins immediately after the signal sequence at residue 25. Cardionatrin III begins at residue 73, and cardionatrin I, sequenced previously, begins at residue 123. Compositional analysis indicated that each of these cardionatrins extends up to tyrosine at position 150 but lacks the terminal two arginine residues.
Phosphate Release and Force Generation in Skeletal Muscle Fibers
Authors: Hibberd Mark G. , Dantzig Jody A. , Trentham David R. , Goldman Yale E.
Published: October 2006

Rapid laser pulse-induced photolysis of an adenosine triphosphate precursor in muscle fibers abruptly initiated cycling of the cross-bridges. The accompanying changes in tension and stiffness were related to elementary mechanochemical events of the energy-transducing mechanism. When inorganic phosphate was present at millimolar concentrations during liberation of adenosine triphosphate in the absence of calcium, relaxation was accelerated. Steady active tension in the presence of calcium was decreased but the approach to final tension was more rapid. These results suggest that, during energy transduction, formation of the dominant force-generating cross-bridge state is coupled to release of inorganic phosphate in a reaction that is readily reversible.
Presence of Laminin Receptors in
Staphylococcus aureus
Authors: Lopes J. D. , dos Reis M. , Brentani R. R.
Published: October 2006

A characteristic feature of infection by
Staphylococcus aureus
is bloodstream invasion and widespread metastatic abscess formation. The ability to extravasate, which entails crossing the vascular basement membrane, appears to be critical for the organism's pathogenicity. Extravasation by normal and neoplastic mammalian cells has been correlated with the presence of specific cell surface receptors for the basement membrane glycoprotein laminin. Similar laminin receptors were found in
Staphylococcus aureus
but not in
Staphylococcus epidermidis
, a noninvasive pathogen. There were about 100 binding sites per cell, with an apparent binding affinity of 2.9 nanomolar. The molecular weight of the receptor was 50,000 and
p
I was 4.2. Eukaryotic laminin receptors were visualized by means of the binding of
S. aureus
in the presence of laminin. Prokaryotic and eukaryotic invasive cells might utilize similar, if not identical, mechanisms for invasion.
A Model-Based Estimate of the Mean Incubation Period for AIDS in Homosexual Men
Authors: Lui Kung-Jong , Darrow William W. , Rutherford George W.
Published: October 2006

Because of the difficulty in identifying the date of exposure to type 1 of the human immunodeficiency virus (HIV-1) infection in persons other than transfusion recipients, studies of the incubation periods for acquired immunodeficiency syndrome (AIDS) have been limited. When data from a cohort of 84 homosexual and bisexual men that provided the information to determine the years of conversion of sera infected with HIV-1 were analyzed, a model for the proportion likely to develop AIDS and the incubation period for AIDS in homosexual men could be derived. The maximum likelihood estimate for the proportion of infected homosexual men developing AIDS is 0.99 (90% confidence interval ranging from 0.38 to 1). Furthermore, the maximum likelihood estimate for the mean incubation period for AIDS in homosexual men is 7.8 years (90% confidence interval ranging from 4.2 years to 15.0 years), which is close to the estimate of 8.2 years for adults developing transfusion-associated AIDS.
Overexpression of Metallothionein Confers Resistance to Anticancer Drugs
Authors: Kelley Susan L. , Basu Alakananda , Teicher Beverly A. , Hacker Miles P. , Hamer Dean H. , Lazo John S
Published: October 2006

Resistance to antineoplastic agents is the major obstacle to curative therapy of cancer. Tumor cell lines with acquired resistance to the antineoplastic agent
cis
-diamminedichloroplatinum(II) overexpressed metallothionein and demonstrated cross-resistance to alkylating agents such as chlorambucil and melphalan. Human carcinoma cells that maintained high levels of metallothionein because of chronic exposure to heavy metals were resistant to
cis
-diamminedichloroplatinum(II), melphalan, and chlorambucil. Furthermore, cells transfected with bovine papilloma virus expression vectors containing DNA encoding human metallothionein-II
A
were resistant to
cis
-diamminedichloroplatinum(II), melphalan, and chlorambucil but not to 5-fluorouracil or vincristine. Thus, overexpression of metallothionein represents one mechanism of resistance to a subset of clinically important anticancer drugs.
Spontaneous Impulse Activity of Rat Retinal Ganglion Cells in Prenatal Life
Authors: Galli Lucia , Maffei Lamberto
Published: October 2006

The existence of spontaneous neural activity in mammalian retinal ganglion cells during prenatal life has long been suspected. This activity could play a key role in the refinement of retinal projections during development. Recordings in vivo from the retinas of rat fetuses between embryonic day 17 and 21 found action potentials in spontaneously active ganglion cells at all the ages studied.
Acetaldehyde Production and Transfer by the Perfused Human Placental Cotyledon
Authors: Karl Peter I. , Gordon Barbara H. J. , Lieber Charles S. , Fisher Stanley E.
Published: October 2006

Fetal injury associated with maternal ethanol ingestion is a major cause of congenital anomalies and mental retardation. Studies with animals suggest that acetaldehyde, the primary hepatic oxidative metabolite of ethanol, may contribute to fetal damage. It is not known, however, whether acetaldehyde reaches the human fetus, either by placental production or transfer. Studies utilizing the perfused human placental cotyledon show that the human placenta oxidizes ethanol to acetaldehyde, releasing it into the fetal perfusate. Moreover, when acetaldehyde is present in the maternal perfusate, it is transferred to the fetal side, reaching approximately 50 percent of the maternal level. These findings suggest that the human placenta may play a pivotal role in the pathophysiology of ethanol-associated fetal injury.
Astrocytes Synthesize Angiotensinogen in Brain
Authors: Stornetta Ruth L. , Hawelu-Johnson Charlyn L. , Guyenet Patrice G. , Lynch Kevin R.
Published: October 2006

Cell types associated with angiotensinogen mRNA in rat brain were identified in individual brain sections by in situ hybridization with tritiated RNA probes or with a sulfur-35—labeled oligonucleotide combined with immunocytochemical detection of either glial fibrillary acidic protein (GFAP) for astrocytes or microtubule-associated protein (MAP-2) for neurons. Autoradiography revealed silver grains clustered primarily over GFAP-reactive soma and processes; most grain clusters were not associated with MAP-2—reactive cells. These results demonstrate that, in contrast to other known neuropeptide precursors, angiotensinogen is synthesized by glia.
Competitive Inhibition of
hsp70
Gene Expression Causes Thermosensitivity
Authors: Johnston Randal N. , Kucey B. L.
Published: October 2006

A novel method has been developed for modulating the expression of an endogenous chromosomal gene in a higher eukaryote, by competitive inhibition at the level of gene transcription. The gene studied was the
hsp70
gene, which encodes a 72-kilodalton (kD) heat shock protein that is synthesized after thermal stress. The 5′ control region of the
hsp70
gene was inserted on a plasmid containing the eukaryotic gene for dihydrofolate reductase. The hybrid plasmid was then introduced into a Chinese hamster ovary cell line and elevated in copy number approximately 20,000-fold by selection of cells with methotrexate. Heat-inducible expression from the intact
hsp70
gene was reduced by at least 90% in the modified cells when compared with the induction in control cells, and the modified cells also displayed elevated thermosensitivity. The change in heat shock protein synthesis is presumably caused by competition among the increased number of binding sites for the heat-shock transcription factor, leading to altered expression from the native heat shock gene. These results support a role for heat shock protein in the recovery of mammalian cells from acute thermal stress.
Induction of Manganous Superoxide Dismutase by Tumor Necrosis Factor: Possible Protective Mechanism
Authors: Wong Grace H. W. , Goeddel David V.
Published: October 2006

Manganous superoxide dismutase (MnSOD) scavenges potentially toxic superoxide radicals produced in the mitochondria. Tumor necrosis factor-α (TNF-α) was found to induce the messenger RNA for MnSOD, but not the mRNAs for other antioxidant or mitochondrial enzymes tested. The increase in MnSOD mRNA occurred rapidly and was blocked by actinomycin D, but not by cycloheximide. Induction of MnSOD mRNA was also observed with TNF-β, interleukin-1α (IL-1α), and IL-1β but not with other cytokines or agents tested. TNF-α induced MnSOD mRNA in all cell lines and normal cells examined in vitro and in various organs of mice in vivo. These effects of TNF-α and IL-1 on target cells may contribute to their reported protective activity against radiation as well as their ability to induce resistance to cell killing induced by the combination of TNF-α and cycloheximide.
Experimental Infarct Sizing Using Computer Processing and a Three-Dimensional Model
Authors: Lewis Margaret , Buja L. Maximilian , Saffer Shelley , Mishelevich David , Stokely Ernest , Lewis Samuel , Parkey Robert , Bonte Frederick , Willerson James
Published: October 2006

A method for noninvasive sizing of myocardial infarction, in which data from technetium-99m stannous pyrophosphate scintigrams and a three-dimensional model were used, was tested on experimental, acute anterior infarcts in dogs. The results indicate that the method does size experimental anterior infarcts accurately, but further testing will be necessary to assess the capabilities of the technique for sizing other types of infarcts.
A Bactericidal Effect for Human Lactoferrin
Authors: Arnold Roland R. , Cole Michael F. , McGhee Jerry R.
Published: October 2006

Streptococcus mutans
and
Vibrio cholerae
, but not
Escherichia coli
, were killed by incubation with purified human apolactoferrin. Concentrations of lactoferrin below that necessary for total inhibition resulted in a marked reduction in viable colony-forming units. This bactericidal effect was contingent upon the metal-chelating properties of the lactoferrin molecule.
The Economic Impact of AIDS in the United States
Authors: Bloom David E. , Carliner Geoffrey
Published: October 2006

This analysis of several previous studies of the cost of AIDS suggests that the lifetime cost of medical care per patient will not exceed $80,000, an amount similar to the cost of treating other serious illnesses. If current projections of future AIDS cases are accurate, the cumulative lifetime costs of 270,000 cases diagnosed between 1981 and the end of 1991 will not exceed $22 billion. This amount is small compared with total U.S. medical spending. The economic impact of AIDS on San Francisco, New York, and some other cities, however, is likely to be more serious. The AIDS epidemic will also highlight the financial problems of Americans who face large medical bills without adequate insurance.
Replacements of Pro
86
in Phage T4 Lysozyme Extend an α-Helix But Do Not Alter Protein Stability
Authors: Alber Tom , Bell Jeffrey A. , Dao-Pin Sun , Nicholson Hale , Wozniak Joan A. , Cook Sean , Matthews Brian W.
Published: October 2006

To investigate the relation between protein stability and the predicted stabilities of individual secondary structural elements, residue Pro
86
in an α-helix in phage T4 lysozyme was replaced by ten different amino acids. The x-ray crystal structures of seven of the mutant lysozymes were determined at high resolution. In each case, replacement of the proline resulted in the formation of an extended α-helix. This involves a large conformational change in residues 81 to 83 and smaller shifts that extend 20 angstroms across the protein surface. Unexpectedly, all ten amino acid substitutions marginally reduce protein thermostability. This insensitivity of stability to the amino acid at position 86 is not simply explained by statistical and thermodynamic criteria for helical propensity. The observed conformational changes illustrate a general mechanism by which proteins can tolerate mutations.
Dynamic Pattern Generation in Behavioral and Neural Systems
Authors: Schöner G. , Kelso J. A. S.
Published: October 2006

In the search for principles of pattern generation in complex biological systems, an operational approach is presented that embraces both theory and experiment. The central mathematical concepts of self-organization in nonequilibrium systems (including order parameter dynamics, stability, fluctuations, and time scales) are used to show how a large number of empirically observed features of temporal patterns can be mapped onto simple low-dimensional (stochastic, nonlinear) dynamical laws that are derivable from lower levels of description. The theoretical framework provides a language and a strategy, accompanied by new observables, that may afford an understanding of dynamic patterns at several scales of analysis (including behavioral patterns, neural networks, and individual neurons) and the linkage among them.
The Design of Molecular Hosts, Guests, and Their Complexes
Authors: Cram Donald J.
Published: October 2006

The origins, definitions, tools, and guiding principles of host-guest chemistry are developed. Perching, nesting, and capsular complexes are exemplified through molecular model and crystal structure comparisons. The degree of preorganization of a host for binding is a central determinant of its binding power. Complementarity of binding site placement in host and guest is a central determinant of structural recognition in complexation. Examples are given of chiral recognition in complexation, of partial transacylase mimics, of caviplexes, and of a synthetic molecular cell.
The Leucine Zipper: A Hypothetical Structure Common to a New Class of DNA Binding Proteins
Authors: Landschulz William H. , Johnson Peter F. , McKnight Steven L.
Published: October 2006

A 30-amino-acid segment of C/EBP, a newly discovered enhancer binding protein, shares notable sequence similarity with a segment of the cellular Myc transforming protein. Display of these respective amino acid sequences on an idealized α helix revealed a periodic repetition of leucine residues at every seventh position over a distance covering eight helical turns. The periodic array of at least four leucines was also noted in the sequences of the Fos and Jun transforming proteins, as well as that of the yeast gene regulatory protein, GCN4. The polypeptide segments containing these periodic arrays of leucine residues are proposed to exist in an α-helical conformation, and the leucine side chains extending from one α helix interdigitate with those displayed from a similar α helix of a second polypeptide, facilitating dimerization. This hypothetical structure is referred to as the "leucine zipper," and it may represent a characteristic property of a new category of DNA binding proteins.
Production of Stable Rabbit-Mouse Hybridomas That Secrete Rabbit mAb of Defined Specificity
Authors: Raybould T. J. G. , Takahashi Miyoko
Published: October 2006

Inclusion of normal rabbit serum (NRS) in culture medium after interspecific fusion of hyperimmunized rabbit spleen cells with murine SP2/0 myeloma cells produced 271 rabbit-mouse hybridomas (RMHs) that secreted rabbit immunoglobulin against group A
Streptococcus
(GAS). Continued use of NRS-supplemented medium during cloning yielded stabilized monoclonal RMH lines that have secreted GAS-specific rabbit antibody at concentrations similar to murine hybridomas (3 to 8 micrograms per 10
6
cells per 24 hours), for over 4 months of culture in vitro. The use of NRS as a medium supplement during initial culture, cloning, and stabilization of RMHs enables production of considerably more specific rabbit monoclonal antibody (mAb)-secreting RMHs than have previously been reported.
Specification of Cerebral Cortical Areas
Authors: Rakic Pasko
Published: October 2006

How the immense population of neurons that constitute the human cerebral neocortex is generated from progenitors lining the cerebral ventricle and then distributed to appropriate layers of distinctive cytoarchitectonic areas can be explained by the radial unit hypothesis. According to this hypothesis, the ependymal layer of the embryonic cerebral ventricle consists of proliferative units that provide a proto-map of prospective cytoarchitectonic areas. The output of the proliferative units is translated via glial guides to the expanding cortex in the form of ontogenetic columns, whose final number for each area can be modified through interaction with afferent input. Data obtained through various advanced neurobiological techniques, including electron microscopy, immunocytochemistry, [
3
H]thymidine and receptor autoradiography, retrovirus gene transfer, neural transplants, and surgical or genetic manipulation of cortical development, furnish new details about the kinetics of cell proliferation, their lineage relationships, and phenotypic expression that favor this hypothesis. The radial unit model provides a framework for understanding cerebral evolution, epigenetic regulation of the parcellation of cytoarchitectonic areas, and insight into the pathogenesis of certain cortical disorders in humans.
The Inheritance of Epigenetic Defects
Authors: Holliday Robin
Published: October 2006

Evidence from many sources shows that the control of gene expression in higher organisms is related to the methylation of cytosine in DNA, and that the pattern of methylation is inherited. Loss of methylation, which can result from DNA damage, will lead to heritable abnormalities in gene expression, and these may be important in oncogenesis and aging. Transformed permanent lines often lose gene activity through de novo methylation. It is proposed that epigenetic defects in germline cells due to loss of methylation can be repaired by recombination at meiosis but that some are transmitted to offspring.