bluuebunny/crossref_metadata_2025 huggingface dataset:
Pertussis Toxin Inhibition of B Cell and Macrophage Responses to Bacterial Lipopolysaccharide
Authors: Jakway James P. , DeFranco Anthony L.
Published: October 2006

Lipopolysaccharide, a component of the outer membrane of Gram-negative bacteria, activates B lymphocytes and macrophages. Pertussis toxin, which inactivates several members of the G protein family of signaling components, including G
i
and transducin, was found to inhibit the lipopolysaccharide-induced responses of the WEHI-231 B lymphoma cell line and the P388D
1
macrophage cell line. These results, combined with the demonstration that lipopolysaccharide inhibits adenylate cyclase activity in P388D
1
cells, strongly argues that lipopolysaccharide activation of cells is mediated by a G
i
-like receptor-effector coupling protein.
Bacterial Resistance to β-Lactam Antibiotics: Crystal Structure of β-Lactamase from
Staphylococcus aureus
PC1 at 2.5 Å Resolution
Authors: Herzberg Osnat , Moult John
Published: October 2006

β-lactamases are enzymes that protect bacteria from the lethal effects of β-lactam antibiotics, and are therefore of considerable clinical importance. The crystal structure of β-lactamase from the Gram-positive bacterium
Staphylococcus aureus
PC1 has been determined at 2.5 angstrom resolution. It reveals a molecule of novel topology, made up of two closely associated domains. The active site is located at the interface between the domains, with the key catalytic residue Ser
70
at the amino terminus of a buried helix. Examination of the disposition of the functionally important residues within the active site depression leads to a model for the binding of a substrate and a functional analogy to the serine proteases. The unusual topology of the secondary structure units is relevant to questions concerning the evolutionary relation to the β-lactam target enzymes of the bacterial cell wall.
Dynamic Changes in Inhibin Messenger RNAs in Rat Ovarian Follicles During the Reproductive Cycle
Authors: Woodruff Teresa K. , D'Agostino JoBeth , Schwartz Neena B. , Mayo Kelly E.
Published: October 2006

The alterations in morphology and function of the ovarian follicle as it matures, ovulates, and becomes a corpus luteum are dramatic. A variety of steroid and polypeptide hormones influence these processes, and the ovary in turn produces specific hormonal signals for endocrine regulation. One such signal is inhibin, a heterodimeric protein that suppresses the secretion of follicle-stimulating hormone from pituitary gonadotrophs. Rat inhibin complementary DNA probes have been used to examine the levels and distribution of inhibin α- and β
A
-subunit messenger RNAs in the ovaries of cycling animals. Striking, dynamic changes have been found in inhibin messenger RNA accumulation during the developmental maturation of the ovarian follicle.
Drosophila melanogaster
as an Experimental Organism
Authors: Rubin Gerald M.
Published: October 2006

The fruit fly
Drosophila melanogaster
has been used as an experimental organism in studies of genetics since the early 1900s. It is now widely used not only in classical and molecular genetics but also, with many new biochemical, cell biological, and physiological techniques, to research problems requiring a multidisciplinary approach, such as those of developmental biology and neurobiology.
Cells Process Exogenous Proteins for Recognition by Cytotoxic T Lymphocytes
Authors: Yewdell Jonathan W. , Bennink Jack R. , Hosaka Yasuhiro
Published: October 2006

Cells exposed to intact, noninfectious influenza virus were shown to be recognized by class I-restricted anti-influenza cytotoxic T lymphocytes (CTLs). Both internal and external proteins derived from virions were processed by cells for CTL recognition. Sensitization required the inactivation of viral neuraminidase activity and could be inhibited by preventing fusion of viral and cellular membranes. These findings are important in designing vaccines to elicit CTL responses, since they demonstrate that cells can process intact, exogenous proteins for recognition by CTLs and suggest that such processing depends on introduction of exogenous proteins into the cytoplasm.
Immune Response in the Sea Urchin
Lytechinus pictus
Authors: Coffaro Katherine A. , Hinegardner Ralph T.
Published: October 2006

The sea urchin shows an immune response to grafted tissue similar to that found in vertebrates. Unrelated animals rejected allografts in about 30 days. Acceptance of allografts was observed for tissue exchanged between some F
2
and F
3
inbred animals. The percentage of acceptances reflected the degree of inbreeding. Accelerated second set rejection was also found. These grafts were rejected in one-third of the time compared to first sets.
Evolutionary and Somatic Selection of the Antibody Repertoire in the Mouse
Authors: Rajewsky Klaus , Förster Irmgard , Cumano Ana
Published: October 2006

The repertoire of antibody variable (V) regions has been subject to evolutionary selection, affecting both the diversity of V region genes in the germline and their expression in the B lymphocyte population and its subsets. In ontogeny, contact with an antigen leads to the expansion of B cells expressing antibodies complementary to it. In a defined phase of B cell differentiation, new sets of V regions are generated from the existing repertoire through somatic hypermutation. Cells carrying advantageous antibody mutants are selected into the memory compartment and produce a stable secondary response upon reexposure to the antigen.
Human Immunodeficiency Virus May Encode a Novel Protein on the Genomic DNA Plus Strand
Authors: Miller Roger H.
Published: October 2006

The genome of the human immunodeficiency virus (HIV) is known to contain eight open reading frames (ORFs) on the minus strand of the double-stranded DNA replicative intermediate. Data presented here indicate that the DNA plus strand of HIV contains a previously unidentified ORF in a region complementary to the envelope gene sequence. This ORF could encode a protein of approximately 190 amino acid residues with a relative molecular mass of 20 kilodaltons if translation began from the first initiation codon. The predicted protein is highly hydrophobic and thus could be membrane associated. It is possible, therefore, that the HIV genome encodes a protein on antisense messenger RNA.
Helical Repeat and Linking Number of Surface-Wrapped DNA
Authors: White James H. , Cozzarelli Nicholas R. , Bauer William R.
Published: October 2006

The geometric properties of duplex DNA are systematically altered when the DNA is wrapped on a protein surface. The linking number of surface-wrapped closed circular DNA is the sum of two integers: the winding number, φ, a function of the helical repeat; and the surface linking number, SLk, a newly defined geometric constant that accounts for the effects of surface geometry on the twist and writhe of DNA. Changes in the helical repeat, h, and in the winding number can be deduced solely from surface geometry and superhelix density, σ. This treatment relates the theoretically important properties twist and writhe to the more experimentally accessible quantities φ,
h
, SLk, and σ. The analysis is applied to three biologically important cases: interwinding of DNA in a plectonemic superhelix, catenated DNA, and minichromosomes.
Modification of the Active Site of Alkaline Phosphatase by Site-Directed Mutagenesis
Authors: Ghosh Soumitra S. , Bock Susan Clark , Rokita Steven E. , Kaiser Emil Thomas
Published: October 2006

The catalytically essential amino acid in the active site of bacterial alkaline phosphatase (Ser-102) has been replaced with a cysteine by site-directed mutagenesis. The resulting thiol enzyme catalyzes the hydrolysis of a variety of phosphate monoesters. The rate-determining step of hydrolysis, however, is no longer the same for catalysis when the active protein nucleophile is changed from the hydroxyl of serine to the thiol of cysteine. Unlike the steady-state kinetics of native alkaline phosphatase, those of the mutant show sensitivity to the leaving group of the phosphate ester.
Irreversible Gene Repression Model for Control of Development
Authors: Caplan Arnold I. , Ordahl Charles P.
Published: October 2006

As the pluripotent cells of early embryos differentiate, each progressively loses the potency to develop into several phenotypes. Ultimately, each cell becomes irreversibly restricted to the expression of a single phenotype. Although in many instances details regarding those restriction events are well known, there is little information concerning the nature of the gene transcription changes involved. A model that accounts for the diminution of developmental potential as resulting from progressive, irreversible repression of previously active genes is presented. A scheme of progressive gene repression, rather than selective gene activation, is most consistent with observations from experimental embryology as well as from more recent biochemical experimentation.
Expression of Bovine 17α-Hydroxylase Cytochrome P-450 cDNA in Nonsteroidogenic (COS 1) Cells
Authors: Zuber Mauricio X. , Simpson Evan R. , Waterman Michael R.
Published: October 2006

Cortisol production requires the activity of only 17α-hydroxylase, whereas the formation of sex steroids requires both 17α-hydroxylase and 17,20-lyase activities. Studies in reconstituted enzyme systems have suggested that a single steroid hydroxylase, 17α-hydroxylase cytochrome P-450 (P-450
17α
), catalyzes both activities. By expression of bovine adrenocortical P-450
17α
in COS 1 (transformed monkey kidney) cells, which normally contain no detectable P-450
17α
, it has now been established in situ that a single polypeptide chain does catalyze both the 17α-hydroxylase and the 17,20-lyase reactions. This heterologous system supports 17α-hydroxylation of pregnenolone and progesterone with equal efficiency, but catalyzes about five times as much 17,20-lyase activity when 17α-hydroxypregnenolone is the substrate than when 17α-hydroxyprogesterone is the substrate. For these activities to be observed in COS 1 cells, newly synthesized apocytochrome P-450
17α
must bind heme and insert into the endoplasmic reticulum such that endogenous cytochrome P-450 reductase can support hydroxylation. Thus, COS 1 cells are a useful system for expression and study of various forms of cytochrome P-450.
Molecular Cloning and Expression of a Human B-Cell Growth Factor Gene in
Escherichia coli
Authors: Sharma Surendra , Mehta Shashi , Morgan John , Maizel Abby
Published: October 2006

A human B-cell growth factor (BCGF) (12 kilodaltons) supports the clonal proliferation of B lymphocytes. A clone was isolated that contained the proper structural sequence to encode biologically active, 12-kilodalton BCGF in
Escherichia coli
and to hybridize to a specific messenger RNA, identified by in vitro translation in
Xenopus laevis
oocytes. A relatively hydrophobic region of 18 amino acids was found at the amino terminal of the 124-amino acid-long polypeptide. The carboxyl terminal is composed of at least 32 amino acids that are derived from nucleotide sequences bearing significant homology to the Alu repeat family.
Antiarthritic Gold Compounds Effectively Quench Electronically Excited Singlet Oxygen
Authors: Corey E. J. , Mehrotra Mukund M. , Khan Ahsan U.
Published: October 2006

Although certain gold [Au(I)] compounds have been used effectively in the treatment of rheumatoid arthritis for some years, the molecular basis for such therapeutic action has been unclear. One possible mechanism of the action of Au(I) compounds is that they protect unsaturated membrane lipids and proteins against oxidative degradation caused by activated phagocytes that are not properly regulated. In this study it has been shown that superoxide ion (O
-
2
.), a product of activated phagocytes, can be oxidized to electronically excited singlet oxygen (O
1
2
Δ
g
), an agent that is capable of peroxidation of unsaturated fatty acid derivatives. It has also been shown that antiarthritic Au(I) compounds are effective deactivators of O
1
2
Δ
g
with quenching constants on the order of 10
7
M
-1
sec
-1
.
The Molecular Basis of the Sparse Fur Mouse Mutation
Authors: Veres Gabor , Gibbs Richard A. , Scherer Steven E. , Caskey C. Thomas
Published: October 2006

The ornithine transcarbamylase-deficient sparse fur mouse is an excellent model to study the most common human urea cycle disorder. The mutation has been well characterized by both biochemical and enzymological methods, but its exact nature has not been revealed. A single base substitution in the complementary DNA for ornithine transcarbamylase from the sparse fur mouse has been identified by means of a combination of two recently described techniques for rapid mutational analysis. This strategy is simpler than conventional complementary DNA library construction, screening, and sequencing, which has often been used to find a new mutation. The ornithine transcarbamylase gene in the sparse fur mouse contains a C to A transversion that alters a histidine residue to an asparagine residue at amino acid 117.
Developmental Stability of the Tonotopic Organization of the Chick's Basilar Papilla
Authors: Manley G. A. , Brix J. , Kaiser A.
Published: October 2006

In the past, the damage patterns produced on the papilla of the chick by loud pure tones of different frequencies have been used to study the development of sound analysis by the hair cells of the basilar papilla. One conclusion from these data was that the best response frequency of individual hair cells changes substantially with age. However, this method has been criticized as unreliable. Now experiments have been performed in which single characterized nerve fibers were stained with horseradish peroxidase to permit the unequivocal localization of specific frequency responses in the papillae of chicks of different ages (2 and 21 days after hatching). There was no statistically significant change in the tonotopic organization of the papilla between the two groups of animals.
Low Repetitive DNA Content in
Aspergillus nidulans
Authors: Timberlake William E.
Published: October 2006

DNA-DNA reassociation experiments show that the genome of
Aspergillus nidulans
consists of approximately 97 to 98 percent unique and 2 to 3 percent reiterated sequences. The reiterated DNA sequences have a complexity of about 11,000 base pairs and are repeated approximately 60 times per haploid genome. Ribosomal RNA-DNA hybridization experiments indicate that most of the repetitive DNA codes for ribosomal RNA.
Conformational Changes in 16
S
Ribosomal RNA Induced by 30
S
Ribosomal Subunit Proteins from
Escherichia coli
Authors: Bogdanov Alexei A. , Zimmermann Robert A. , Wang Chun-Chen , Ford Norman C.
Published: October 2006

Laser light scattering has been used to evaluate conformational differences between free 16S RNA and several specific protein-16S RNA complexes. Proteins that interact strongly with the 16S RNA early in subunit assembly stabilize the RNA chain against unfolding in 1 mM Mg
2+
and actually promote the formation of a more compact tertiary structure in 20 mM Mg
2+
. A vital function of these proteins may therefore consist in altering the configuration of the RNA so that further assembly reactions can take place.
Corresponding Spatial Gradients of TOP Molecules in the Developing Retina and Optic Tectum
Authors: Trisler David , Collins Frank
Published: October 2006

The topographic map of cell position in the avian retina is inverted in its projection to the optic tectum. Dorsal retinal ganglion cell axons project to ventral tectum, and ventral retinal ganglion cells project to dorsal tectum. Topographic gradients of toponymic (TOP) cell surface molecules along the dorsoventral axes of retina and tectum also are inverted. TOP molecules are most abundant in dorsal retina and ventral tectum and least abundant in ventral retina and dorsal tectum during the period of initial retinal-tectal interaction. Thus, TOP molecules may be involved in orienting the retinotectal map.
Transformation by Oncogenes Encoding Protein Kinases Induces the Metastatic Phenotype
Authors: Egan Sean E. , Wright Jim A. , Jarolim Lenka , Yanagihara Kazuyoshi , Bassin Robert H. , Greenberg Arnold H.
Published: October 2006

Oncogenes encoding serine/threonine or tyrosine kinases were introduced into the established rodent fibroblast cell line NIH 3T3 and tested for tumorigenic and metastatic behavior in T cell-deficient nude mice. Transforming oncogenes of the
ras
family were capable of converting fibroblast cell lines to fully metastatic tumors. Cell lines transformed by the kinase oncogenes
mos
,
ra
f,
src
,
fes
, and
fms
formed experimental metastases and (in some cases) these genes were more efficient at metastatic conversion than a mutant
ras
gene. In contrast, cells transformed by either of two nuclear oncogenes, myc or p53, were tumorigenic when injected subcutaneously but were virtually nonmetastatic after intravenous injection. These data demonstrate that, in addition to
ras
, a structurally divergent group of kinase oncogenes can induce the metastatic phenotype.
Intracellular Topography of Rhodopsin Bleaching
Authors: Makino Clint L. , Howard Louis N. , Williams Theodore P.
Published: October 2006

In a vertebrate eye, the photoreceptor cells are aligned so that most of the light passes through them lengthwise. At the light-transducing outer segment region of the photoreceptor, photons are absorbed in a time-varying, spatially dependent fashion. Because the transduction event is spatially localized around the site of photon absorption, the spatiotemporal patterns of light absorption in outer segments are an important receiver input characteristic. This aspect of receptor biophysics has now been measured; the results were consistent with a theoretical model proposed for bleaching of a pigment in an unstirred layer.
Structure of a Psoralen Cross-Linked DNA in Solution by Nuclear Magnetic Resonance
Authors: Tomic Milan T. , Wemmer David E. , Kim Sung-Hou
Published: October 2006

One- and two-dimensional nuclear magnetic resonance (NMR) methods were used to determine a three-dimensional model of an eight-base-pair DNA fragment (d-GGGTACCC) cross-linked with psoralen in solution. Two-dimensional nuclear Overhauser effect experiments were used to assign the spectrum and estimate distances for 171 proton pairs in the cross-linked DNA. The NMR-derived model shows a 53° bend into the major groove that occurs primarily at the site of drug addition and a 56° unwinding that spans the eight-base-pair duplex.
Structure of Pressinoic Acid: The Cyclic Moiety of Vasopressin
Authors: Langs David A. , Smith G. David , Stezowski John J. , Hughes Robert E.
Published: October 2006

Arginine vasopressin consists of a 20-membered, disulfide-linked macrocyclic ring system called pressinoic acid to which is attached a COOH-terminal tripeptide. The molecular conformation of pressinoic acid has been determined from single crystal x-ray diffraction data. The 20-membered macrocyclic ring, stabilized by two intramolecular hydrogen bonds, has a type I β-bend centered on Gln
4
and Asn
5
and a highly distorted type II' bend centered on Phe
3
and Gln
4
. In vasopressin the Asn
5
side chain extends away from the macrocyclic ring system and hydrogen bonds to the terminal tripeptide, but in pressinoic acid the Asn
5
side chain lies over the molecule and forms a strong hydrogen bond to the nitrogen of Tyr
2
. The absence of pressor activity in pressinoic acid may be a result of both the loss of the COOH-terminal tripeptide and the incorrect orientation of the Asn
5
side chain. Whether this class of hormones has pressor or oxytocic activity is determined by the orientation of the Tyr
2
side chain, that is, whether it is extended away from or over the ring system, respectively. In pressinoic acid, the Tyr
2
side chain is in the expected "pressor conformation," that is, extended away from the ring system, and is stabilized through a hydrophobic interaction with the Phe
3
side chain. Thus, the conformation of the pressinoic acid molecule partly explains the activity of vasopressin-like hormones.
Human Macrophage Migration Inhibition Factor: Evidence for Subunit Structure
Authors: Possanza Genus , Cohen Marion C. , Yoshida Takeshi , Cohen Stanley
Published: October 2006

Macrophage migration inhibition factor (MIF) derived from human lymphoid cell lines was found to lose biologic activity on dialysis. Although activity was not recovered in the dialyzate, mixing experiments demonstrated that the components in the retentate and dialyzate could reassociate to restore activity. The fragment of larger molecular weight (< 10,000) could inhibit the activity of intact MIF, whereas the smaller molecular weight fragment (5,000 to 10,000) could not. These findings suggest that human MIF is composed of at least two noncovalently linked subunits. In analogy to the situation for certain bacterial toxins, one of these may represent an attachment piece for a target cell membrane receptor.
Polymorphism of Sickle Cell Hemoglobin Aggregates: Structural Basis for Limited Radial Growth
Authors: Makowski Lee , Magdoff-Fairchild Beatrice
Published: October 2006

Fibers composed of molecules of deoxygenated sickle cell hemoglobin are the basic cause of pathology in sickle cell disease. The hemoglobin molecules in these fibers are arranged in double strands that twist around one another with a long axial repeat. These fibrous aggregates exhibit a pattern of polymorphism in which the ratio of their helical pitch to their radius is approximately constant. The observed ratio agrees with an estimate of its value calculated from the geometric properties of helical assemblies and the degree of distortion that a protein-protein interface can undergo. This agreement indicates that the radius of an aggregate is limited by the maximum possible stretching of double strands. The geometric properties limiting the radial extent of sickle hemoglobin fibers are fundamental to all cables of protein filaments and could contribute to the control of diameter in other biological fibers such as collagen or fibrin.
Physical Theory of the Orientation of Astral Mitotic Spindles
Authors: Bjerknes Matthew
Published: October 2006

A physical theory was developed for mitotic spindle orientation. This is important because spindle position is known to determine the placement of the cleavage furrow separating the offspring of a mitosis. The theory is based on an equation for the force exerted on spindle poles by the interaction of astral microtubules with the cell surface. Expected spindle placements are positions of stable equilibrium where the net force and torque resulting from the action of the astral microtubules on the spindle poles is zero. The theory provides a novel physical explanation of cleavage patterns in the early embryo.
Pharmacologic Effects in Man of a Potent, Long-Acting Dopamine Receptor Agonist
Authors: Lemberger Louis , Crabtree Ross E.
Published: October 2006

Single-dose administration of pergolide mesylate (100 to 400 micrograms) results in a dose-related inhibition of prolactin secretion which persists for more than 24 hours. During multiple-dose administration of pergolide, plasma prolactin concentrations remain markedly reduced (greater than 80 percent) and gradually return to control levels several days after drug administration is discontinued.
Detection of Rift Valley Fever Viral Activity in Kenya by Satellite Remote Sensing Imagery
Authors: Linthicum Kenneth J. , Bailey Charles L. , Davies F. Glyn , Tucker Compton J.
Published: October 2006

Data from the advanced very high resolution radiometer on board the National Oceanic and Atmospheric Administration's polar-orbiting meteorological satellites have been used to infer ecological parameters associated with Rift Valley fever (RVF) viral activity in Kenya. An indicator of potential viral activity was produced from satellite data for two different ecological regions in Kenya, where RVF is enzootic. The correlation between the satellite-derived green vegetation index and the ecological parameters associated with RVF virus suggested that satellite data may become a forecasting tool for RVF in Kenya and, perhaps, in other areas of sub-Saharan Africa.
Human Dioxin-Inducible Cytochrome P
1
-450: Complementary DNA and Amino Acid Sequence
Authors: Jaiswal Anil K. , Gonzalez Frank J. , Nebert Daniel W.
Published: October 2006

Induction of cytochrome P
1
-450 has been linked to susceptibility to certain chemically induced cancers in mouse and man. Treatment of the human cell line MCF-7 with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) results in high levels of aryl hydrocarbon (benzo[
a
]pyrene) hydroxylase (P
1
-450) activity. This cell line was used to isolate a human P
1
-450 full-length complementary DNA (cDNA) clone. The cDNA is 2566 nucleotides in length, encodes a polyadenylated messenger RNA (2.8 kilobases in length), and has a continuous reading frame producing a protein with 512 residues (molecular weight, 58,151). The human P
1
-450 cDNA and protein are 63 percent and 80 percent similar to mouse P
1
-450 cDNA and protein, respectively. Whereas the mouse TCDD-inducible P-450 gene subfamily has two members (P
1
-450 and P
3
-450), the human TCDD-inducible gene subfamily appears to have only one gene (P
1
-450).
A Novel Mechanism of Somatic Rearrangement Predicted by a Human T-Cell Antigen Receptor β-Chain Complementary DNA
Authors: Duby Allan D. , Klein Karen A. , Murre Cornelis , Seidman J. G.
Published: October 2006

The T-cell antigen receptor is a cell surface molecule vital in mediating the cellular immune response. The arrangement and rearrangement of the gene segments encoding the β-chain polypeptide of the receptor are similar to those of immunoglobulin gene segments. The two constant region genes of the human T-cell antigen receptor are 8 kilobases apart with a cluster of joining segments located 5′ of each constant region gene. Although most β-chain gene rearrangements involve the variable, diversity, and joining segments, analysis of a β-chain complementary DNA clone suggests the occasional occurrence of another type of rearrangement.
Chromosomal Locations of Human Tissue Plasminogen Activator and Urokinase Genes
Authors: Rajput B. , Degen S. F. , Reich E. , Waller E. K. , Axelrod J. , Eddy R. L. , Shows T. B.
Published: October 2006

A panel of human-mouse somatic cell hybrids and specific complementary DNA probes were used to map the human tissue plasminogen activator and urokinase genes to human chromosomes 8 and 10, respectively. This result is in contrast to a previous assignment of a plasminogen activator gene to chromosome 6. As neoplastic cells produce high levels of plasminogen activator, it is of interest that aberrations of chromosome 8 have been linked to various leukemias and lymphomas and that two human oncogenes, c-
mos
and c-
myc
, have also been mapped to chromosome 8.
Hernandulcin: An Intensely Sweet Compound Discovered by Review of Ancient Literature
Authors: Compadre Cesar M. , Pezzuto John M. , Kinghorn A. Douglas , Kamath Savitri K.
Published: October 2006

Ancient Mexican botanical literature was systematically searched for new plant sources of intensely sweet substances.
Lippia dulcis
Trev., a sweet plant, emerged as a candidate for fractionation studies, and hernandulcin, a sesquiterpene, was isolated and judged by a human taste panel as more than 1000 times sweeter than sucrose. The structure of the sesquiterpene was determined spectroscopically and confirmed by chemical synthesis. Hernandulcin was nontoxic when administered orally to mice, and it did not induce bacterial mutation.
Expression of a Microinjected Porcine Class I Major Histocompatibility Complex Gene in Transgenic Mice
Authors: Frels William I. , Bluestone Jeffrey A. , Hodes Richard J. , Capecchi Mario R. , Singer Dinah S.
Published: October 2006

A porcine class I major histocompatibility complex (SLA) gene has been introduced into the genome of a C57BL/10 mouse. This transgenic mouse expressed SLA antigen on its cell surfaces and transmitted the gene to offspring, in which the gene is also expressed. Skin grafts of such transgenic mice were rejected by normal C57BL/10 mice, suggesting that the foreign SLA antigen expressed in the transgenic mice is recognized as a functional transplantation antigen.
Hematopoietic Histoincompatibility Reactions by NK Cells in Vitro: Model for Genetic Resistance to Marrow Grafts
Authors: Bordignon Claudio , Daley John P. , Nakamura Ichiro
Published: October 2006

In certain strains of mice, bone marrow grafts from parental donors fail to grow in first-generation hybrid mice. This "hybrid resistance" of nonsensitized F
1
hybrid mice to the engraftment of parental hematopoietic transplants contradicts the classical laws of transplantation and is dependent on a radioresistant but immunogenetically specific effector mechanism. Studies in a new in vitro model reveal that committed hematopoietic precursors of parental origin can be inactivated by direct contact with natural killer-like splenic effectors from F
1
mice. The reaction requires genetically restricted recognition, since only parental competitors syngeneic to the target bone marrow cells partially reversed this inactivation. Models of this type may be useful in studying the possible role of natural resistance in bone marrow transplantation in humans.
Abnormal Visual Pathways in Normally Pigmented Cats That Are Heterozygous for Albinism
Authors: Leventhal Audie G. , Vitek Dagmar J. , Creel Donnell J.
Published: October 2006

The various forms of albinism affect about one in 10,000 births in the United States. An additional 1 to 2 percent of the population has normal pigmentation but is heterozygous and carries a recessive allele for albinism. The retinogeniculocortical pathways were studied in normally pigmented cats that carry a recessive allele for albinism. The cats exhibited abnormalities in their visual pathways similar to those present in homozygous albinos. These results imply that visual anomalies like those found in albinos may be present in 1 to 2 percent of the human population.
Immunization with an Isolate-Common Surface Protein Protects Cattle Against Anaplasmosis
Authors: Palmer Guy H. , Barbet Anthony F. , Davis William C. , McGuire Travis C.
Published: October 2006

Hemoparasitic diseases are endemic in half the world's livestock production areas and are the greatest obstacle to improved meat, milk, and fiber production in the Third World. The most prevalent of these diseases, anaplasmosis, occurs throughout tropical and subtropical regions and is responsible for 50,000 to 100,000 cattle deaths annually in the United States alone. Despite its prevalence and the severity of the losses, an effective immunoprophylaxis for anaplasmosis has not been developed. A neutralization-sensitive epitope on a surface protein with a molecular weight of 105,000 (Am 105) of the causative rickettsia
Anaplasma marginale
was identified by monoclonal antibody inhibition of infectivity. This epitope was determined to be common to eight isolates with antigenic, morphologic, and protein structural differences. Cattle immunized with Am 105 purified by immunoaffinity chromatography were protected against challenge with virulent
Anaplasma marginale
. The identification of Am 105 as bearing isolate-common epitopes capable of inducing protection in immunized cattle provides the basis for the development of an effective subunit vaccine for bovine anaplasmosis.
Characterization of the Supernumerary Chromosome in Cat Eye Syndrome
Authors: McDermid Heather E. , Duncan Alessandra M. V. , Brasch Klaus R. , Holden Jeannette J. A. , Magenis Ellen , Sheehy Robert , Burn John , Kardon Nataline , Noel Bernard , Schinzel Albert , Teshima Ikuko , White Bradley N.
Published: October 2006

Most individuals with cat eye syndrome (CES) have a supernumerary bisatellited chromosome which, on the basis of cytogenetic evidence, has been reported to originate from either chromosome 13 or 22. To resolve this question, a single-copy DNA probe, D22S9, was isolated and localized to 22q11 by in situ hybridization to metaphase chromosomes. The number of copies of this sequence was determined in CES patients by means of Southern blots and densitometry analysis of autoradiographs. In patients with the supernumerary chromosome, four copies were found, whereas in one patient with a duplication of part of chromosome 22, there were three copies. Therefore, the syndrome results from the presence of either three or four copies of DNA sequences from 22q11; there is no evidence that sequences from other chromosomes are involved. This work demonstrates how DNA sequence dosage analysis can be used to study genetic disorders that are not readily amenable to standard cytogenetic analysis.
Microorganism Mediated Reproductive Isolation in Flour Beetles (Genus
Tribolium
)
Authors: Wade Michael J. , Stevens Lori
Published: October 2006

Reproductive isolation is induced by microorganisms in diverse geographic strains of the flour beetle
Tribolium confusum
(Coleoptera:Tenebrionidae). The incompatibility between populations is due to nongenetic cytoplasmically inherited factors. Males of infected strains produce no progeny when crossed with females of noninfected strains; however, they produce "normal" numbers of progeny when crossed with infected females. Males from noninfected strains show no reproductive isolation. Infected strains of
T. confusum
can be cured when tetracycline or other antibiotics are added to the flour medium. "Cured" strains become partially reproductively isolated from all noncured strains including the source strain.
Intracellular Stimulation of an Identified Neuron Evokes Cardioacceleratory Peptide Release
Authors: Tublitz Nathan J. , Truman James W.
Published: October 2006

The central nervous system of the tobacco hawkmoth,
Manduca sexta
, is known to contain two cardioacceleratory peptides (CAP's), both of which function in vivo as cardioregulatory neurohormones. Intracellular electrical stimulation of a single abdominal ganglion neuron evokes the release of CAP-like bioactivity. This stimulation-evoked bioactivity is destroyed by prior treatment with protease. The possibility that intracellular stimulation of a CAP-containing neuron synaptically activated additional spiking neurons is eliminated.
Dominance in Physiological Phenotypes and Fitness at an Enzyme Locus
Authors: Hilbish Thomas J. , Koehn Richard K.
Published: October 2006

Aminopeptidase-I allozymes, which are products of the
Lap
locus in the marine mussel,
Mytilus edulis
, differ in their catalytic efficiencies. These biochemical differences result in genotype-specific rates of change in the free amino acid pool, that is, in cell volume regulation, when mussels are subjected to changes in salinity. A high degree of dominance was found among genotypes for these biochemical and physiological phenotypes. Selection models that incorporate dominance adequately predict observed genotypic properties at the
Lap
locus among natural populations that exhibit clinal allele frequency. This suggests that a high degree of dominance for fitness must also occur at this locus in natural populations. These results provide additional evidence that the maintenance of an allele frequency cline is operating by natural selection at the
Lap
locus.
Picosecond Time-Resolved Resonance Raman Studies of Hemoglobin: Implications for Reactivity
Authors: Findsen E. W. , Friedman J. M. , Ondrias M. R. , Simon S. R.
Published: October 2006

Picosecond time-resolved Raman spectra of hemoglobin generated with blue pulses (20 to 30 picoseconds) that were resonant with the Soret band and of sufficient intensity to completely photodissociate the starting liganded sample are reported. For both R- and T-state liganded hemoglobins, the peak frequencies in the spectrum of the deoxy transient were the same at approximately 25 picoseconds as those observed at 10 nanoseconds subsequent to photodissociation. In particular, the large R-T differences in the frequency of the stretching mode for the iron-proximal histidine bond (ν
Fe-His
) detected in previously reported nanosecond-resolved spectra were also evident in the picosecond-resolved spectra. The implications of this finding with respect to the distribution of strain energy in the liganded protein and the origin of the time course for geminate recombination are discussed. On the basis of these results, a microscopic model is proposed in which delocalization of strain energy is strongly coupled to the coordinate of the iron. The model is used to explain the origin of the R-T differences in the rates of ligand dissociation.
Androgens Prevent Normally Occurring Cell Death in a Sexually Dimorphic Spinal Nucleus
Authors: Nordeen E. J. , Nordeen K. W. , Sengelaub D. R. , Arnold A. P.
Published: October 2006

The spinal nucleus of the bulbocavernosus (SNB) contains many more motoneurons in adult male rats than in females. Androgens establish this sex difference during a critical perinatal period, which coincides with normally occurring cell death in the SNB region. Sex differences in SNB motoneuron number arise primarily because motoneuron loss is greater in females than in males during the early postnatal period. Perinatal androgen treatment in females attenuates cell death in the SNB region, reducing motoneuron loss to levels typical of males. The results suggest that steroid hormones determine sex differences in neuron number by regulating normally occurring cell death and that the timing of this cell death may therefore define critical periods for steroid effects on neuron number.
Tissue Factor Gene Localized to Human Chromosome 1 (1pter→1p21)
Authors: Carson Steven D. , Henry W. Michael , Shows Thomas B.
Published: October 2006

Tissue factor (tissue thromboplastin, coagulation factor III), a protein component of cell membranes, is an essential cofactor for factor VII-dependent initiation of blood coagulation. Since no tissue factor-deficient condition has been described, it is one of only a few proteins of the coagulation system for which the pattern of inheritance has not been ascertained. Because of the species-specificity of tissue factor activity and the availability of a very sensitive chromogenic assay, it was possible in the present study to use somatic cell hybrids to assign the chromosomal location of the tissue factor structural gene (F3) to human chromosome 1 (1pter → 1p21).
Interbacterial Transfer of
Escherichia coli
—
Drosophila melanogaster
Recombinant plasmids
Authors: Hamer Dean H.
Published: October 2006

Recombinants were constructed between various
Escherichia coli
plasmids and fragments of
Drosophila melanogaster
DNA. These recombinant plasmids are nonconjugative, but can be mobilized from one cell to another by conjugative sex factors. Of 47 recombinants studied, 46 were mobilized at approximately the same or slightly lower frequencies than the parental plasmids, whereas one was mobilized 1000 times less efficiently.
In Vitro Growth of Imaginal Disks from
Drosophila melanogaster
Authors: Davis Katherine T. , Shearn Allen
Published: October 2006

Imaginal disks were cultured in a new medium in vitro. Optimal growth occurred when the medium was supplemented with insulin and a juvenile hormone analog and conditioned by larval fat body. The disks grow in vitro by normal cell division and maintain their capacity to differentiate into normal patterns of adult cuticular structures.
Latent form of Scrapie Virus: A New Factor in Slow-Virus Disease
Authors: Hotchin John , Buckley Ruth
Published: October 2006

Scrapie is an unusual slow-virus disease of sheep which is very much like kuru and Creutzfeldt-Jakob disease, both fatal, slow neurological diseases of man. In mice, scrapie usually has an incubation period of about 6 months. Intraperitoneal inoculation of virus particles into newborn mice caused no disease, and there was no detectable virus replication for 1 year, but high titers of scrapie were present in the spleen and brain at 18 months. Virus replication occurred in mice injected from 4 days after birth by all inoculation routes, whether or not they were injected with scrapie virus on day 0. The results suggest that scrapie virus replicates peripherally only in thymocytes, which are not present in mice until a few days after birth. The latent state suggests that the comparable human diseases could appear in later life as a result of perinatal infection. In some respects these diseases resemble premature senility.
Aldehyde Oxidase Compartmentalization in
Drosophila melanogaster
Wing Imaginal Disks
Authors: Kuhn David T. , Cunningham Glenn N.
Published: October 2006

Distribution of the enzyme aldehyde oxidase in mature
Drosophila melanogaster
wing disks may allow visualization of known developmental compartments comprising (i) presumptive dorsal and ventral wing surfaces, and (ii) the presumptive anterior wing and the presumptive posterior wing.
The Genetic Linkage Map of the Human X Chromosome
Authors: Drayna Dennis , White Ray
Published: October 2006

A database useful for mapping the human X chromosome has been established. The data consist of the genotypic characterizations obtained at more than 20 DNA marker loci from a set of 38 selected families. Multilocus linkage analysis has provided an initial genetic map completely spanning the distance from the distal short arm to the distal long arm of the chromosome, for a total genetic length of at least 185 recombination units. Analysis of the recombinational behavior of fully marked chromosomes suggests that the number of recombination events on the X chromosome may be nonrandom. Linkage studies of six families that carry the mutation which causes Duchenne muscular dystrophy were combined with linkage data from a large number of normal families. This permitted mapping of the locus for Duchenne muscular dystrophy with greater precision and statistical confidence than studies in which disease families alone provided the genotypic database. This observation suggests that the normal linkage map of this chromosome should be especially valuable in the mapping of rare X-linked diseases.
Orthogenesis of the Hominids: An Exploration Using Biorthogonal Grids
Authors: Bookstein Fred L.
Published: October 2006

In 1917, D'Arcy Thompson suggested that one should study the change from one biological form to another by examining the unique mathematical object that maps between them in accord with biological homologies. Biorthogonal grids provide a particular coordinate system for visualizing such a map and lead to a quantitative syntax in which a change in shape is reduced to differential changes in size. Application of the method to hominid skull phylogeny has demonstrated three principal axes of evolutionary change anatomically homologous over a fossil sequence.
Hominoid Enamel Prism Patterns
Authors: Gantt David G. , Pilbeam David , Steward Gregory P.
Published: October 2006

Analysis of enamel prism patterns in a selected series of extant hominoids reveals that pongids have a pattern distinctively different from that of Homo sapiens. The pattern for a Miocene hominoid,
Ramapithecus
, is very similar to that seen in
Homo sapiens
. The finding allows a new approach to the evaluation of isolated teeth.
National Health Insurance: Comments on Selected Issues
Authors: Ball Robert M.
Published: October 2006

The primary objective of national health insurance is to make sure that good medical care is available to everyone at a price he or she can afford. Any plan when first adopted will have a role for both private and government insurance but, regardless of the mix, the combined system should meet the following goals: (i) to the extent possible the needs of low-income people should be met through plans that cover others; (ii) the part of the plan to be operated by government should be built on the administrative structure of Medicare, but with changes in reimbursement to encourage more efficient delivery of care; (iii) direct capital and manpower controls should be included; and (iv) rather than acting primarily as an insurer protecting people against the cost of medical care, the plan should be an aggressive buyer of health services, defining the product it is willing to buy and the price it is willing to pay.
Hybrid Myelomas Producing Antibodies Against a Human Neuroblastoma Antigen Present on Fetal Brain
Authors: Kennett Roger H. , Gilbert Fred
Published: October 2006

Spleen cells from mice immunized with a cultured human neuroblastoma were hybridized with the mouse plasmacytoma P3X63Ag8. Hybrid myelomas were screened for production of antibodies that reacted with human neuroblastomas but not with cells from other tissues. One of these hybridoma antibodies reacted with an antigen present on the six human neuroblastomas tested, one of two retinoblastomas, a glioblastoma, and fetal brain, but did not react with other tumors or tissues including adult human brain.
Membrane Surface Potential Changes May Alter Drug Interactions: An Example, Acetylcholine and Curare
Authors: Van der Kloot William G. , Cohen Ira
Published: October 2006

Curare is known to be less effective as an acetylcholine antagonist when the divalent cation concentration of the extracellular solution is increased. This observation can be accounted for by the negative surface potential on the end plate; an increase in divalent cation concentration decreases the negativity of the surface potential and thereby lowers the concentrations of cations at the membrane-solution interface. The concentration of divalent cations, such as curare, will be reduced more than the concentration of univalent cations, such as acetylcholine. The observations can be accounted for by a surface potential of about -50 millivolts. The same principle can explain the reported actions of divalent cations on the affinity of receptors for acetylcholine. The effects of surface potential on concentrations at active sites may play an important role in drug interactions.
Chemical Evidence for Production of Hydroxyl Radicals During Microsomal Electron Transfer
Authors: Cohen Gerald , Cederbaum Arthur I.
Published: October 2006

Rat liver microsomes generate methane from dimethyl sulfoxide and ethylene from either methional or 2-keto-4-thiomethylbutyric acid during electron transfer initiated by reduced nicotinamide-adenine dinucleotide phosphate (NADPH). Hydrocarbon gas production is suppressed by hydroxyl radical scavenging agents. Azide, an inhibitor of catalase, augments the production of hydrocarbon gases. These observations constitute chemical evidence for the generation of hydroxyl radicals by microsomes.
Tectorial Membrane: A Possible Effect on Frequency Analysis in the Cochlea
Authors: Zwislocki J. J. , Kletsky E. J.
Published: October 2006

Mathematical analysis and computer and network simulations of the cochlea show that, given appropriate values of specific physical constants, radial shear motion between the tectorial membrane and the reticular lamina may provide the sharpening of frequency analysis observed in cochlear nerve fibers in comparison with the mechanical amplitude distribution on the basilar membrane. According to the analysis, the sharpening occurs through an interaction of the longitudinal mechanical propagation constant of the tectorial membrane with the wavelength on the basilar membrane.
Fluorescent Retrograde Double Labeling: Axonal Branching in the Ascending Raphe and Nigral Projections
Authors: van der Kooy Derek , Kuypers Henricus G. J. M.
Published: October 2006

Red fluorescent Evans blue and blue fluorescent DAPI-primuline were injected into the anterior-medial and lateral-caudal forebrains, respectively, of the same rats. Separate clusters of cells labeled by retrograde transport were observed in the substantia nigra, while in the dorsal raphe many cells were double-labeled. Thus, single raphe cells send divergent axon collaterals to widespread forebrain areas.