bluuebunny/crossref_metadata_2025 huggingface dataset:
Parasitic Protozoa and Helminths: Biological and Immunological Challenges
Authors: Mahmoud Adel A. F.
Published: October 2006

Parasitic protozoans and helminths pose considerable medical as well as scientific challenges. Investigations of the complex and very different life cycles of these organisms, their adaptation to the obligate parasitic mode of life, and their ability to face the hostile host environment have resulted in many exciting discoveries. Invasion of host erythrocytes by plasmodial sporozoites and intact skin by schistosomal cercariae are outlined as examples of the elaborate mechanisms of parasitism. Isolation and characterization of single protective antigens or subunit vaccines from these two organisms are examined as models for vaccine development. Finally, developments in exploring gene regulation in protozoans and free and parasitic nematodes are briefly outlined.
Immunofluorescent Detection of Nuclear Double-Stranded RNA in Situ in Vero and Mosquito Cells
Authors: Stollar B. D. , Koo R. , Stollar V.
Published: October 2006

Double-stranded RNA (dsRNA) was detected in situ by indirect immunofluorescence with antibodies to dsRNA. It was seen in nuclei of Vero and
Aedes albopictus
cells, but not in BHK cells, KB cells, chick embryo fibroblasts, or HeLa cells. Reactive dsRNA was present in the nucleoplasm, but not in nucleoli or cytoplasm. Extracted RNA from the whole cell contained from 0.08 percent (BHK) to 0.46 percent (HeLa) dsRNA, as estimated by serological methods. This dsRNA, found in molecules having the size distribution of heterogeneous nuclear RNA, did not renature rapidly after denaturation. The quantity of dsRNA in total extracted RNA did not correlate with the presence or absence of nuclear staining in situ.
Synaptic Connections in Vitro: Modulation of Number and Efficacy by Electrical Activity
Authors: Nelson Phillip G. , Yu Chang , Fields R. Douglas , Neale Elaine A.
Published: October 2006

The functional architecture of synaptic circuits is determined to a crucial degree by the patterns of electrical activity that occur during development. Studies with an in vitro preparation of mammalian sensory neurons projecting to ventral spinal cord neurons show that electrical activity induces competitive processes that regulate synaptic efficacy so as to favor activated pathways over inactive convergent pathways. At the same time, electrical activity initiates noncompetitive processes that increase the number of axonal connections between these sensory and spinal cord neurons.
Water-Inserted α-Helical Segments Implicate Reverse Turns as Folding Intermediates
Authors: Sundaralingam M. , Sekharudu Y. C.
Published: October 2006

Information relevant to the folding and unfolding of α helices has been extracted from an analysis of protein structures. The α helices in protein crystal structures have been found to be hydrated, either externally by a water molecule hydrogen bonding to the backbone carbonyl oxygen atom, or internally by inserting into the helix hydrogen bond and forming a hydrogen-bonded bridge between the backbone carbonyl oxygen and the amide nitrogen atoms. The water-inserted α-helical segments display a variety of reverse-turn conformations, such as type III, type II, type I, and opened out, that can be considered as folding intermediates that are trapped in the folding-unfolding process of α helices. Since the α helix, most turns, and the extended β strand occupy contiguous regions in the conformational space of φ, ψ dihedral angles, a plausible pathway can be proposed for the folding-unfolding process of α helices in aqueous solution.
A Test of Clathrin Function in Protein Secretion and Cell Growth
Authors: Payne Gregory S. , Schekman Randy
Published: October 2006

Clathrin-coated membranes are intimately associated with a variety of protein transport processes in eukaryotic cells, yet no direct test of clathrin function has been possible. The data presented demonstrate that Saccharomyces cerevisiae does not require clathrin for either cell growth or protein secretion. Antiserum to the yeast clathrin heavy chain has been used to isolate a molecular clone of the heavy chain gene (CHC1) from a library of yeast DNA in λgt11. Clathrin-deficient mutant yeast have been obtained by replacing the single chromosomal CHC1 gene with a disrupted version of the cloned DNA. Cells harboring a nonfunctional chc1 allele produce no immunoreactive heavy chain polypeptide, and vesicles prepared from mutant cells are devoid of clathrin heavy and light chains. Although clathrin-deficient cells grow two to three times more slowly than normal, secretion of invertase occurs at a nearly normal rate. Therefore protein transport through the secretory pathway is not obligately coupled to the formation of clathrin-coated vesicles.
Absence of Duplication of Chromosome 21 Genes in Familial and Sporadic Alzheimer's Disease
Authors: St George-Hyslop Peter H. , Tanzi Rudolph E. , Polinsky Ronald J. , Neve Rachael L. , Pollen Daniel , Drachman David , Growdon John , Cupples L. Adrienne , Nee Linda , Myers Richard H. , O'Sullivan Dianne , Watkins Paul C. , Amos Jean A. , Deutsch Curtis K. , Bodfish James W. , Kinsbourne Marcel , Feldman Robert G. , Bruni Amalia , Amaducci Luigi , Foncin Jean-Francois , Gusella James F.
Published: October 2006

The possibility that Alzheimer's disease (AD) is caused by overexpression or duplication of one or more genes on chromosome 21 has been raised by the observation of AD-like neuropathologic changes in individuals with Down syndrome and by the mapping of both the defect for familial AD and the amyloid β protein gene to this autosome. Possible duplication on chromosome 21 was investigated in both familial and sporadic AD by means of restriction fragment length polymorphisms for the amyloid and
SOD
I loci, as well as for DNA markers in the vicinity of the familial AD defect and in the critical Down syndrome region of chromosome 21. No evidence of increased DNA dosage was observed in either brain or leukocytes of patients with inherited or sporadic forms of AD. Duplication of these regions is therefore not a frequent event in either form of AD. Furthermore, no significant allelic association was detected between AD and any of the loci, including the amyloid and
SOD
I genes, providing no support for the hypothesis that defects in these specific genes are the primary cause of AD.
The Amyloid β Protein Gene Is Not Duplicated in Brains from Patients with Alzheimer's Disease
Authors: Tanzi Rudolph E. , Bird Edward D. , Latt Samuel A. , Neve Rachael L.
Published: October 2006

Complementary DNAs (cDNAs) encoding portions of the amyloid β protein were used to investigate possible amyloid gene duplication in sporadic Alzheimer's disease. A strategy employing two Eco RI restriction fragment length polymorphisms (RFLPs) detected by the amyloid cDNAs was used. RFLPs allow the detection of a 2:1 gene dosage in the DNA of any individual who is heterozygous for a particular RFLP. The amyloid gene regions homologous to the cDNAs used were not duplicated in the DNA from brains of individuals with sporadic Alzheimer's disease. Similar results were also obtained with a strategy employing a test for 3:2 gene dosage.
Long-Term Facilitation in
Aplysia
Involves Increase in Transmitter Release
Authors: Dale N. , Schacher S. , Kandel E. R.
Published: October 2006

In a variety of vertebrates and invertebrates, long-lasting enhancement of synaptic transmission contributes to the storage of memory lasting one or more days. However, it has not been demonstrated directly whether this increase in synaptic transmission is caused by an enhancement of transmitter release or an increase in the sensitivity of the postsynaptic receptors. These possibilities can be distinguished by a quantal analysis in which the size of the miniature excitatory postsynaptic potential released spontaneously from the presynaptic terminal is used as a reference. By means of microcultures, in which single sensory and motor neurons of
Aplysia
were plated together, miniature excitatory postsynaptic potentials attributable to the spontaneous release of single transmitter quanta from individual presynaptic neurons were recorded and used to analyze long-term facilitation induced by repeated applications of 5-hydroxytryptamine. The results indicate that the facilitation is caused by an increase in the number of transmitter quanta released by the presynaptic neuron.
Purification and Characterization of Mouse Hematopoietic Stem Cells
Authors: Spangrude Gerald J. , Heimfeld Shelly , Weissman Irving L.
Published: October 2006

Mouse bone marrow hematopoietic stem cells were isolated with the use of a variety of phenotypic markers. These cells can proliferate and differentiate with approximately unit efficiency into myelomonocytic cells, B cells, or T cells. Thirty of these cells are sufficient to save 50 percent of lethally irradiated mice, and to reconstitute all blood cell types in the survivors.
Hormonal Control of Behavior: Amines and the Biasing of Behavioral Output in Lobsters
Authors: Kravitz Edward A.
Published: October 2006

Hormones and neurohormones act on the nervous system to produce important changes in behavior. Amine actions in the lobster nervous system and their possible relations to aggressive behavior in lobsters were studied in order to explore how such changes might come about.
The Manganese Site of the Photosynthetic Water-Splitting Enzyme
Authors: George Graham N. , Prince Roger C. , Cramer Stephen P.
Published: October 2006

As the originator of the oxygen in our atmosphere, the photosynthetic water-splitting enzyme of chloroplasts is vital for aerobic life on the earth. It has a manganese cluster at its active site, but it is poorly understood at the molecular level. Polarized synchrotron radiation was used to examine the x-ray absorption of manganese in oriented chloroplasts. The manganese site, in the "resting" (S
1
) state, is an asymmetric cluster, which probably contains four manganese atoms, with interatomic separations of 2.7 and 3.3 angstroms; the vector formed by the 3.3-angstrom manganese pair is oriented perpendicular to the membrane plane. Comparisons with model compounds suggest that the cluster contains bridging oxide or hydroxide ligands connecting the manganese atoms, perhaps with carboxylate bridges connecting the 3.3-angstrom manganese pair.
High Titers of Autoantibodies to Topoisomerase I (Scl-70) in Sera from Scleroderma Patients
Authors: Shero J. H. , Bordwell B. , Rothfield N. F. , Earnshaw W. C.
Published: October 2006

Patients with rheumatic diseases often have circulating autoantibodies to nuclear components. The clinical significance of the antibodies is controversial, although in some cases they are valuable in the diagnosis of the disease. This report presents results of a study of Scl-70, an autoantigen recognized by sera of many patients with the most severe form of progressive systemic sclerosis. It was possible to show, by three independent criteria, that Scl-70 is the abundant nuclear enzyme DNA topoisomerase I. Therefore, antibody probes of high titer and high affinity are now available for the study of this important nuclear enzyme.
Cell Surface Molecule Associated with Lymphocyte Homing Is a Ubiquitinated Branched-Chain Glycoprotein
Authors: Siegelman Mark , Bond Martha W. , Gallatin W. Michael , St John Tom , Smith Harry T. , Fried Victor A. , Weissman Irving L.
Published: October 2006

Partial amino acid sequence analysis of a purified lymphocyte homing receptor demonstrates the presence of two amino termini, one of which corresponds precisely to the amino terminus of ubiquitin. This observation extends the province of this conserved polypeptide to the cell surface and leads to a proposed model of the receptor complex as a core polypeptide modified by glycosylation and ubiquitination. Independent antibodies to ubiquitin serve to identify additional cell surface species, an indication that ubiquitination of cell surface proteins may be more general. It is proposed that functional binding of lymphocytes to lymph node high endothelial venules might involve the ubiquitinated region of the receptor; if true, cell surface ubiquitin could play a more general role in cell-cell interaction and adhesion.
Crystal Structure Analysis of Deamino-Oxytocin: Conformational Flexibility and Receptor Binding
Authors: Wood S. P. , Tickle I. J. , Treharne A. M. , Pitts J. E. , Mascarenhas Y. , Li J. Y. , Husain J. , Cooper S. , Blundell T. L. , Hruby V. J. , Buku A. , Fischman A. J. , Wyssbrod H. R.
Published: October 2006

Two crystal structures of deamino-oxytocin have been determined at better than 1.1 Å resolution from isomorphous replacement and anomalous scattering x-ray measurements. In each of two crystal forms there are two closely related conformers with disulfide bridges of different chirality, which may be important in receptor recognition and activation.
Binding of the Sp1 Transcription Factor by the Human Harvey
ras
1 Proto-Oncogene Promoter
Authors: Ishii Shunsuke , Kadonaga James T. , Tjian Robert , Brady John N. , Merlino Glenn T. , Pastan Ira
Published: October 2006

Members of the
ras
gene family encode proteins that when overproduced or mutated can transform immortalized mammalian cells. It is therefore important to understand the mechanisms by which the
ras
genes are regulated. The promoter region of the human Harvey
ras
proto-oncogene c-Ha-
ras
1 initiates RNA transcription at multiple sites and contains repeated copies of the hexanucleotide GGGCGG and its inverted complement CCGCCC, referred to as GC boxes. These GC boxes consist of sequences identical to those found in the SV40 early promoter, where the human cellular transcriptional factor Sp1 binds. Footprinting analysis with deoxyribonuclease I was used to show that Sp1 binds to six GC box sequences within the c-Ha-
ras
1 promoter. An in vivo transfection assay showed competition between the 21-base pair repeats of the SV40 promoter and the c-Ha-
ras
1 promoter for common regulatory factors. In this system the presence of Sp1 is apparently required for c-Ha-
ras
1 transcription. Analysis of deletions of the c-Ha-
ras
1 promoter region by means of a transient expression assay revealed that the three Sp1 binding sites closest to the RNA start sites were sufficient for full transcriptional activity.
Selectivity of the Parkinsonian Neurotoxin MPTP: Toxic Metabolite MPP
+
Binds to Neuromelanin
Authors: D'Amato Robert J. , Lipman Zoe P. , Snyder Solomon H.
Published: October 2006

Methylphenyltetrahydropyridine (MPTP) selectively destroys neuronal cell bodies in the melanin-containing substantia nigra of humans and other primates. We show that methylphenylpyridine (MPP
+
), an active metabolite of MPTP which is accumulated intraneuronally by the catecholamine uptake system, binds with high affinity to melanin and neuromelanin. MPP
+
bound intracellularly to neuromelanin may be released gradually, resulting in subsequent damage to the neurons of the substantia nigra.
In Situ Detection of β-Galactosidase in Lenses of Transgenic Mice with a γ-Crystallin/
lacZ
Gene
Authors: Goring D. R. , Rossant J. , Clapoff S. , Breitman M. L. , Tsui L.-C.
Published: October 2006

Transgenic mice carrying the γ2-crystallin promoter fused to the coding region of the bacterial
lacZ
gene were generated. The offspring of three founder mice expressed high levels of the enzyme solely in the central nuclear fiber cells of the lens as measured by an in situ assay for the detection of β-galactosidase activity. These results suggest that γ2-crystallin sequences between -759 to +45 contain essential information required for appropriate tissue-specific and temporal regulation of the mouse γ2-crystallin gene. In a broader context, this study also demonstrates the utility of β-galactosidase hybrid gene constructs for monitoring the activity of gene regulatory elements in transgenic mice.
Isolation and Structure of a Covalent Cross-Link Adduct Between Mitomycin C and DNA
Authors: Tomasz Maria , Lipman Roselyn , Chowdary Dondapati , Pawlak Jan , Verdine Gregory L. , Nakanishi Koji
Published: October 2006

A DNA cross-link adduct of the antitumor agent mitomycin C (MC) to DNA has been isolated and characterized; the results provide direct proof for bifunctional alkylation of DNA by MC. Exposure of MC to
Micrococcus luteus
DNA under reductive conditions and subsequent nuclease digestion yielded adducts formed between MC and deoxyguanosine residues. In addition to the two known monoadducts, a bisadduct was obtained. Reductive MC activation with Na
2
S
2
O
4
(sodium dithionite) leads to exclusive bifunctional alkylation. The structure of the bisadduct was determined by spectroscopic methods that included proton magnetic resonance, differential Fourier transform infrared spectroscopy, and circular dichroism. Formation of the same bisadduct in vivo was demonstrated upon injection of rats with MC. Computer-generated models of the bisadduct that was incorporated into the center of the duplex B-DNA decamer d(CGTACGTACG)
2
indicated that the bisadduct fit snugly into the minor groove with minimal distortion of DNA structure. A mechanistic analysis of the factors that govern monofunctional and bifunctional adduct formation is presented.
The IL-2 Receptor β Chain (p70): Role in Mediating Signals for LAK, NK, and Proliferative Activities
Authors: Siegel Jay P. , Sharon Michael , Smith Paula L. , Leonard Warren J.
Published: October 2006

Interleukin-2 (IL-2) induces cytolytic activity and proliferation of human blood lymphocytes. Yet, prior to activation, these cells do not express IL-2 receptors recognized by monoclonal antibodies to the Tac antigen. A novel glycoprotein (IL-2Rβ), identified on several lymphocytoid cell lines, has the ability to bind IL-2 alone and to associate with Tac antigen (IL-2Rα) to form high-affinity IL-2 receptors. It is now reported that IL-2Rβ is expressed on both circulating T lymphocytes and large granular lymphocytes in quantities approximately proportional to their responsiveness to IL-2. Studies of the responses of these cells to IL-2 suggest that IL-2Rβ mediates the initial phase of induction of lymphokine activated killer (LAK), natural killer (NK), and proliferative activities. Subsequently, IL-2Rα is induced and functional high-affinity IL-2 receptors are expressed.
Interferon-γ: the Major Mediator of Resistance Against
Toxoplasma gondii
Authors: Suzuki Yasuhiro , Orellana Manuel A. , Schreiber Robert D. , Remington Jack S.
Published: October 2006

Mice were injected with a monoclonal antibody to interferon-γ to examine the importance of endogenous production of this lymphokine in resistance against infection with the sporozoan parasite
Toxoplasma gondii
. Mice with intraperitoneal infections of
T. gondii
that received no antibody survived and developed chronic
T. gondii
infection, whereas the infected mice that received the monoclonal antibody died of toxoplasmosis. The activation of macrophages, which kill
T. gondii
in vivo, was inhibited by administration of the monoclonal antibody, but the production of antibodies to
T. gondii
was not suppressed. The fact that an antibody to interferon-γ can eliminate resistance to acute
Toxoplasma
infection in mice suggests that this lymphokine is an important mediator of host resistance to this parasite.
Atrotoxin: A Specific Agonist for Calcium Currents in Heart
Authors: Hamilton Susan L. , Yatani Atsuko , Hawkes Mary Jane , Redding Kevin , Brown Arthur M.
Published: October 2006

A specific label for voltage-dependent calcium channels is essential for the isolation and purification of the membrane protein that constitutes the calcium channel and for a better understanding of its function. A fraction of
Crotalus atrox
that increases voltage-dependent calcium currents in single, dispersed guinea pig ventricular cells was isolated. In the doses used, neither sodium nor potassium currents were changed. The fraction was active in the absence of detectable phospholipase or protease activity, and the active component, designated atrotoxin, produced its effect rapidly and reversibly. The effect was produced by extracellular but not intracellular application of the agent. The increase in Ca
2+
current was blocked by the Ca
2+
channel blockers cobalt and nitrendipine. The active fraction completely blocked specific [
3
H]nitrendipine binding to guinea pig ventricular membrane preparations. The inhibition of nitrendipine binding by atrotoxin was apparently via an allosteric mechanism. Thus atrotoxin was shown to bind to the Ca
2+
channel and to act as a specific Ca
2+
channel agonist.
Movement of the X Chromosome in Epilepsy
Authors: Borden Jonathan , Manuelidis Laura
Published: October 2006

The position of selected chromosomes was assessed in samples of normal and epileptic human cortex with biotinylated probes specific for individual chromosome domains. Optical sectioning provided a rapid method for three-dimensional resolution of in situ hybridization signals in interphase cells, and solid models were reconstructed from digitized images for detailed rotational studies. There was a dramatic repositioning of the X chromosome in neurons of both males and females in electrophysiologically defined seizure foci. Other chromosomes (1, 9, and Y) showed more subtle positional changes. Specifically altered nuclear patterns involving the X chromosome may become established and create the genetic memory for intractable seizure activity.
Essential Fatty Acid Depletion of Renal Allografts and Prevention of Rejection
Authors: Schreiner George F. , Flye Wayne , Brunt Elizabeth , Korber Ken , Lefkowith James B.
Published: October 2006

A central hypothesis in transplantation biology is that resident leukocytes expressing class II histocompatibility antigens may determine the immunogenicity of an organ. By means of a novel method to deplete the kidney of resident leukocytes, essential fatty acid deficiency (EFAD), this hypothesis was tested in an intact, vascular organ. Kidneys subjected to EFAD and thus depleted of resident Ia-positive macrophages survived and functioned when transplanted across a major histocompatibility antigen barrier in the absence of immunosuppression of the recipient. Control allografts were rejected promptly. Allografts from donors subjected to EFAD normalized their lipid composition and were repopulated with host macrophages by 5 days. Administration of Ia-positive cells at the time of transplantation established that the resident leukocyte depletion induced by EFAD was responsible for the protective effect. These observations may provide insights into the mechanisms underlying tissue immunogenicity and the population of normal tissues with resident leukocytes.
Naturally Acquired Antibodies to Sporozoites Do Not Prevent Malaria: Vaccine Development Implications
Authors: Hoffman Stephen L. , Oster Charles N. , Plowe Christopher V. , Woollett Gillian R. , Beier John C. , Chulay Jeffrey D. , Wirtz Robert A. , Hollingdale Michael R. , Mugambi Mutuma
Published: October 2006

The first human vaccines against the malaria parasite have been designed to elicit antibodies to the circumsporozoite protein of
Plasmodium falciparum
. However, it is not known whether any level of naturally acquired antibodies to the circumsporozoite protein can predict resistance to
Plasmodium falciparum
malaria. In this study, 83 adults in a malaria-endemic region of Kenya were tested for circumsporozoite antibodies and then treated for malaria. They were monitored for the development of new malaria infections for 98 days. Antibody levels, as determined by four assays in vitro, were indistinguishable between the 60 individuals who did and the 23 who did not develop parasitemia during follow-up, and there was no apparent relation between day of onset of parasitemia and level of antibodies to circumsporozoite protein. Unless immunization with sporozoite vaccines induces antibodies that are quantitatively or qualitatively superior to the circumsporozoite antibodies in these adults, it is unlikely that such antibodies will prevent infection in areas with as intense malaria transmission as western Kenya.
Multiplex DNA Sequencing
Authors: Church George M. , Kieffer-Higgins Stephen
Published: October 2006

The increasing demand for DNA sequences can be met by replacement of each DNA sample in a device with a mixture of
N
samples so that the normal throughput is increased by a factor of
N
. Such a method is described. In order to separate the sequence information at the end of the processing, the DNA molecules of interest are ligated to a set of oligonucleotide "tags" at the beginning. The tagged DNA molecules are pooled, amplified, and chemically fragmented in 96-well plates. The resulting reaction products are fractionated by size on sequencing gels and transferred to nylon membranes. These membranes are then probed as many times as there are types of tags in the original pools, producing, in each cycle of probing, autoradiographs similar to those from standard DNA sequencing methods. Thus, each reaction and gel yields a quantity of data equivalent to that obtained from conventional reactions and gels multiplied by the number of probes used. To date, even after 50 successive probings, the original signal strength and the image quality are retained, an indication that the upper limit for the number of reprobings may be considerably higher.
Posttranslational Covalent Modification of Proteins
Authors: Uy Rosa , Wold Finn
Published: October 2006

A search for derivatized amino acids in proteins has shown that the extent of posttranslational modification of proteins is quite substantial. While only 20 primary amino acids are specified in the genetic code and are involved as monomer building blocks in the assembly of the polypeptide chain, about 140 amino acids and amino acid derivatives have been identified as constituents of different proteins in different organisms. A brief consideration of the questions about where and when the derivatization reactions occur, how the specificity of the reactions is established, and how the posttranslational modifications can facilitate biological processes, reveal a need for more information on all these points. Answers to these questions should represent significant contributions to our understanding of biochemistry and cell biology.
Light-Addressable Potentiometric Sensor for Biochemical Systems
Authors: Hafeman Dean G. , Parce J. Wallace , McConnell Harden M.
Published: October 2006

Numerous biochemical reactions can be measured potentiometrically through changes in
p
H, redox potential, or transmembrane potential. An alternating photocurrent through an electrolyte-insulator-semiconductor interface provides a highly sensitive means to measure such potential changes. A spatially selectable photoresponse permits the determination of a multiplicity of chemical events with a single semiconductor device.
Blockage of Ovulation by an Angiotensin Antagonist
Authors: Pellicer Antonio , Palumbo Angela , DeCherney Alan H. , Naftolin Frederick
Published: October 2006

Angiotensin II (Ang II) is present in high concentrations in preovulatory follicular fluid, and ovarian follicular cells have specific Ang II receptors. To investigate the possible direct involvement of Ang II in ovulation the specific receptor antagonist of Ang II, saralasin, was administered by intraperitoneal injection to immature rats in which follicle development and ovulation had been induced with pregnant mare serum gonadotrophin (PMSG) and human chorionic gonadotrophin (hCG), respectively. Saralasin halved the number of oocytes found in the fallopian tubes 17 to 20 hours after administration of hCG. The antiovulatory effect was observed when saralasin was given 1 hour before hCG or 1 or 3 hours after hCG but not when given 5 hours after hCG. Simultaneous administration of Ang II reversed the saralasin blockage of ovulation. These results indicate a direct, obligate role for Ang II in ovulation and raise the possibility of contraceptive and profertility applications for agonists or antagonists of the renin-angiotensin system that are aimed at the ovulatory process.
Transcription Factor OTF-1 Is Functionally Identical to the DNA Replication Factor NF-III
Authors: O'Neill Edward A. , Fletcher Colin , Burrow Christopher R. , Heintz Nathaniel , Roeder Robert G. , Kelly Thomas J.
Published: October 2006

Octamer transcription factor-1 (OTF-1) and nuclear factor III (NF-III) are sequence-specific DNA binding proteins that activate transcription and DNA replication, respectively. It is shown here that OTF-1 is physically and biologically indistinguishable from NF-III. This conclusion is based on the following observations. First, the two proteins have identical mobilities by SDS-polyacrylamide gel electrophoresis. Second, OTF-1 binds to the adenovirus origin of DNA replication at the same site and with the same affinity as NF-III. Third, OTF-1 can substitute for NF-III in activating the initiation of adenovirus DNA replication in vitro. Fourth, the ability of OTF-1 to stimulate viral DNA replication is dependent on the presence of an intact NF-III binding site within the origin of replication. Fifth, NF-III can substitute for OTF-1 in activating in vitro transcription from the human histone H2b promoter. These data suggest the possibility that NF-III/OTF-1 is a protein that functions in both cellular DNA replication and transcription.
The Role of Biogenic Hydrocarbons in Urban Photochemical Smog: Atlanta as a Case Study
Authors: Chameides W. L. , Lindsay R. W. , Richardson J. , Kiang C. S.
Published: October 2006

The effects of natural hydrocarbons must be considered in order to develop a reliable plan for reducing ozone in the urban atmosphere. Trees can emit significant quantities of hydrocarbons to metropolitan areas such as Atlanta, and model calculations indicate that these natural emissions can significantly affect urban ozone levels. By neglecting these compounds, previous investigators may have overestimated the effectiveness of an ozone abatement strategy based on reducing anthropogenic hydrocarbons.
Fragile Sites at 16q22 Are Not at the Breakpoint of the Chromosomal Rearrangement in AMMoL
Authors: Simmers R. N. , Sutherland G. R. , West A. , Richards R. I.
Published: October 2006

There is much speculation about fragile sites on human chromosomes predisposing to specific chromosome rearrangements seen in cancer. Acute myelomonocytic leukemia is characterized by neoplastic chromosome rearrangements involving band 16q22 in patients who carry the rare fragile site at 16q22. This specific leukemic breakpoint is within the metallothionein gene cluster, which is here shown to be proximal to the rare fragile site (
FRA16B
) and to a common fragile site (
FRA16C
) in this region. Hence neither of these fragile sites are at the breakpoint in this leukemic chromosomal rearrangement.
Isolation of an Olfactory cDNA: Similarity to Retinol-Binding Protein Suggests a Role in Olfaction
Authors: Lee Kyu-Ho , Wells Rebecca G. , Reed Randall R.
Published: October 2006

Molecular cloning techniques were used to isolate and characterize a protein possibly involved in the signal transducing system in olfactory tissue of the frog
Rana pipiens
. A complementary DNA library was constructed with messenger RNA obtained from frog olfactory neuroepithelium. A 700-base pair complementary DNA clone encoding a protein with a molecular weight of 20,300 was identified by differential hybridization analysis with polyadenylated RNA from olfactory epithelium and nonsensory respiratory epithelium. The messenger RNA corresponding to this clone was abundant in the cells of Bowman's glands in olfactory tissue but not in respiratory epithelium nor in several other tissues. The predicted sequence of this protein is homologous to members of a family of proteins that bind and transport small molecules in serum, suggesting that this protein may also bind and transport odorants in the mucus secreted by Bowman's glands.
Prorenin in High Concentrations in Human Ovarian Follicular Fluid
Authors: Glorioso Nicola , Atlas Steven A. , Laragh John H. , Jewelewicz Raphael , Sealey Jean E.
Published: October 2006

Although the kidney is a major source of prorenin, the precursor of renin, there are extrarenal sources for plasma prorenin that have not been identified. The selective increase in plasma prorenin at the time of ovulation suggested that one of these sources might be the ovary. Prorenin was therefore measured in fluid aspirated from 18 ovarian follicles and in plasma collected from three women who were undergoing in vitro fertilization. The follicular fluid contained high concentrations of prorenin that were approximately 12 times higher than plasma prorenin. The prorenin from follicular fluid was immunochemically identical to kidney and plasma prorenin. Thus, the ovary is a likely source for the ovulatory peak of plasma prorenin.
Programmed Gene Rearrangements Altering Gene Expression
Authors: Borst P. , Greaves D. R.
Published: October 2006

Programmed gene rearrangements are used in nature to alter gene copy number (gene amplification and deletion), to create diversity by reassorting gene segments (as in the formation of mammalian immunoglobulin genes), or to control the expression of a set of genes that code for the same function (such as surface antigens). Two major mechanisms for expression control are DNA inversion and DNA transposition. In DNA inversion a DNA segment flips around and is rejoined by site-specific recombination, disconnecting or connecting a gene to sequences required for its expression. In DNA transposition a gene moves into an expression site where it displaces its predecessor by gene conversion. Gene rearrangements altering gene expression have mainly been found in some unicellular organisms. They allow a fraction of the organisms to preadapt to sudden changes in environment, that is, to alter properties such as surface antigens in the absence of an inducing stimulus. The antigenic variation that helps the causative agents of African trypanosomiasis, gonorrhea, and relapsing fever to elude host defense is controlled in this way.
Distribution of Cones in Human and Monkey Retina: Individual Variability and Radial Asymmetry
Authors: Curcio Christine A. , Sloan Kenneth R. , Packer Orin , Hendrickson Anita E. , Kalina Robert E.
Published: October 2006

The distribution of photoreceptors is known for only one complete human retina and for the cardinal meridians only in the macaque monkey retina. Cones can be mapped in computer-reconstructed whole mounts of human and monkey retina. A 2.9-fold range in maximum cone density in the foveas of young adult human eyes may contribute to individual differences in acuity. Cone distribution is radially asymmetrical about the fovea in both species, as previously described for the distribution of retinal ganglion cells and for lines of visual isosensitivity. Cone density was greater in the nasal than in the temporal peripheral retina, and this nasotemporal asymmetry was more pronounced in monkey than in human retina.
Human Cerebral Hemispheres Develop at Different Rates and Ages
Authors: Thatcher R. W. , Walker R. A. , Giudice S.
Published: October 2006

The development of the cerebral hemispheres was assessed by using measures of electroencephalographic coherence and phase in 577 children ranging in age from 2 months to early adulthood. Two categories of age-dependent change in electroencephalographic coherence and phase were noted: continuous growth processes that were described best by an exponential growth function, and discrete growth spurts that appeared in specific anatomical locations at specific postnatal periods. The left and right hemispheres developed at different rates and with different postnatal onset times with the timing of growth spurts overlapping the timing of the major developmental stages described by Piaget.
A Defined Medium for a Fastidious Spiroplasma
Authors: Hackett Kevin J. , Ginsberg Annette S. , Rottem Shlomo , Henegar Roberta B. , Whitcomb Robert F.
Published: October 2006

A defined medium (H-1) was developed for cultivation of the suckling mouse cataract agent,
Spiroplasma mirum
, a fastidious member of the class Mollicutes that causes cataracts and chronic brain infection in inoculated neonate mice. The H-1 medium was used to show the importance of sphingomyelin as a growth factor for the culture of the spiroplasma in vitro. The growth of
Spiroplasma mirum
and the pathology it induces in sphingomyelin-rich tissues in vivo may be related to this dependency.
New Routes to Early Memories
Authors: Kucharski David , Hall W. G.
Published: October 2006

Stimulation of one side of the olfactory system during training with odor-milk pairings in neonatal rats results in their ability to recall an odor memory by using the trained but not the untrained side of the brain. In 12-day-old rats, olfactory learning can be recalled by stimulation of either the trained or untrained side. The development of bilateral recall reflects the maturation of olfactory commissural pathways that provide access to the olfactory memory stored on the contralateral side. Furthermore, the commissural pathways need not be present at the time of memory formation but can establish new and specific access to already existing olfactory memories.
Reading Frame Selection and Transfer RNA Anticodon Loop Stacking
Authors: Curran James F. , Yarus Michael
Published: October 2006

Messenger RNA's are translated in successive three-nucleotide steps (a reading frame), therefore decoding must proceed in only one of three possible frames. A molecular model for correct propagation of the frame is presented based on (i) the measured translational properties of transfer RNA's (tRNA's) that contain an extra nucleotide in the anticodon loop and (ii) a straightforward concept about anticodon loop structure. The model explains the high accuracy of reading frame maintenance by normal tRNA's, as well as activities of all characterized frameshift suppressor tRNA's that have altered anticodon loops.
Induced Expression of the Glucocorticoid Receptor in the Rat Intermediate Pituitary Lobe
Authors: Antakly Tony , Sasaki Atsushi , Liotta Anthony S. , Palkovits Miklos , Krieger Dorothy T.
Published: October 2006

Synthesis and release of pro-opiomelanocortin-derived peptides are under differential regulation in the anterior and intermediate lobes of the pituitary. Glucocorticoids inhibit synthesis of pro-opiomelanocortin-related peptides in the anterior lobe but not in the intermediate lobe. These two lobes are also characterized by differences in neural innervation and blood flow, both of which may represent routes of access for regulatory factors (the intermediate lobe is avascular). Immunoreactive glucocorticoid receptor, which can be demonstrated in many tissues, is absent from the intermediate lobe. Immunocytochemistry was used to demonstrate the presence of immunoreactive glucocorticoid receptor in the intermediate lobe after pituitary stalk transection, neurointermediate lobe grafts to kidney capsule, or monolayer culture of neurointermediate pituitary cells. This appearance of the glucocorticoid receptor is presumably a consequence of removal of intermediate pituitary cells from neural influences that may be responsible for inhibiting their expression under normal conditions in vivo.
Immunoglobulin Heavy-Chain Enhancer Requires One or More Tissue-Specific Factors
Authors: Mercola Mark , Goverman Joan , Mirell Carol , Calame Kathryn
Published: October 2006

Enhancer sequences are regulatory regions that greatly increase transcription of certain eukaryotic genes. An immunoglobulin heavy-chain variable gene segment is moved from a region lacking enhancer activity to a position adjacent to the known heavy-chain enhancer early in B-cell maturation. In lymphoid cells, the heavy-chain and SV40 enhancers bind a common factor essential for enhancer function. In contrast, fibroblast cells contain a functionally distinct factor that is used by the SV40 but not by the heavy-chain enhancer. The existence of different factors in these cells may explain the previously described lymphoid cell specificity of the heavy-chain enhancer.
Reductions in Arterial Diameter Produced by Chronic Decreases in Blood Flow Are Endothelium-Dependent
Authors: Langille B. Lowell , O'Donnell Frank
Published: October 2006

A 70 percent reduction in the rate of blood flow through the common carotid artery in rabbits caused a 21 percent decrease in the diameter of this artery within 2 weeks. The smooth muscle relaxant papaverine did not attenuate the response; therefore, such reductions in diameter probably reflect a structural modification of the arterial wall rather than sustained contraction of smooth muscle. This arterial response to reduced blood flow was abolished when the endothelium was removed from the vessels. It appears that the endothelium is essential for the compensatory arterial response to long-term changes in luminal blood flow rates.
Location of Gene for β Subunit of Human T-Cell Receptor at Band 7q35, a Region Prone to Rearrangements in T Cells
Authors: Isobe Masaharu , Erikson Jan , Emanuel Beverly S. , Nowell Peter C. , Croce Carlo M.
Published: October 2006

The T-cell receptor is formed by two chains, α and β, for which specific clones were recently obtained. In this report the gene for the β chain of the human T-cell receptor was located on the long arm of chromosome 7, band q35, by means of in situ hybridization. This chromosome region in T cells is unusually prone to develop breaks in vivo, perhaps reflecting instability generated by somatic rearrangement of T-cell receptor genes during normal differentiation in this cell lineage.
Genes for β Chain of Human T-Cell Antigen Receptor Map to Regions of Chromosomal Rearrangement in T Cells
Authors: Morton Cynthia C. , Duby Allan D. , Eddy Roger L. , Shows Thomas B. , Seidman J. G.
Published: October 2006

The T-cell antigen receptor is a cell-surface molecule that participates in the immune response. In the present experiments the genes encoding the β chain of the T-cell receptor were found to reside on the long arm of human chromosome 7 at or near band q32. Related sequences were found on the short arm of chromosome 7 in bands p15-21 in some experiments. Chromosomal rearrangements in T-cells from normal individuals and patients with ataxia telangiectasia have previously been observed at and near these map assignments for the β-chain genes.
Seal Lungs Collapse During Free Diving: Evidence from Arterial Nitrogen Tensions
Authors: Falke Konrad J. , Hill Roger D. , Qvist Jesper , Schneider Robert C. , Guppy Michael , Liggins Graham C. , Hochachka Peter W. , Elliott Richard E. , Zapol Warren M.
Published: October 2006

Arterial blood nitrogen tensions of free-diving Weddell seals (
Leptonychotes weddelli
) were measured by attaching a microprocessor-controlled blood pump and drawing samples at depth to determine how these marine mammals dive to great depths and ascend rapidly without developing decompression sickness. Forty-seven samples of arterial blood were obtained from four Weddell seals during free dives lasting up to 23 minutes to depths of 230 meters beneath the sea ice of McMurdo Sound, Antarctica. Peak arterial blood nitrogen tensions of between 2000 and 2500 millimeters of mercury were recorded at depths of 40 to 80 meters during descent, indicating that the seal's lung collapses by 25 to 50 meters. Then arterial blood nitrogen tensions slowly decreased to about 1500 millimeters of mercury at the surface. In a single dive, alveolar collapse and redistribution of blood nitrogen allow the seal to avoid nitrogen narcosis and decompression sickness.
Hydrophobicity of Amino Acid Residues in Globular Proteins
Authors: Rose George D. , Geselowitz Ari R. , Lesser Glenn J. , Lee Richard H. , Zehfus Micheal H.
Published: October 2006

During biosynthesis, a globular protein folds into a tight particle with an interior core that is shielded from the surrounding solvent. The hydrophobic effect is thought to play a key role in mediating this process: nonpolar residues expelled from water engender a molecular interior where they can be buried. Paradoxically, results of earlier quantitative analyses have suggested that the tendency for nonpolar residues to be buried within proteins is weak. However, such analyses merely classify residues as either "exposed" or "buried." In the experiment reported in this article proteins of known structure were used to measure the average area that each residue buries upon folding. This characteristic quantity, the average area buried, is correlated with residue hydrophobicity.
Attractive Forces Between Uncharged Hydrophobic Surfaces: Direct Measurements in Aqueous Solution
Authors: Pashley Richard M. , McGuiggan Patricia M. , Ninham Barry W. , Evans D. Fennell
Published: October 2006

Long, double-chained alkylammonium acetate surfactants are soluble in water and, under suitable conditions, adsorb onto sheets of muscovite mica, forming an electrically neutral, hydrophobic surface. Attractive forces measured between such surfaces are 10 to 100 times stronger than expected from van der Waals theory over distances
D
up to about 10 nanometers. The forces decay exponentially [with a force proportional to exp(-
D
/1.4)] instead of following the power-law behavior of continuum theory. The results of these and earlier experiments indicate that the strength of these attractive forces depends critically on the degree of hydrophobicity of the surface and is due to the long-range influence of the surface on the structure of water. In addition, for very hydrophobic surfaces, the cavitation effects on pulling the surfaces apart are described.
An Effective Immunization of Experimental Monkeys Against a Human Malaria Parasite,
Plasmodium falciparum
Authors: Siddiqui Wasim A.
Published: October 2006

This is the first report of successful immunization of experimental monkeys against a human malaria parasite,
Plasmodium falciparum
. Of the five owl monkeys (
Aotus trivirgatus
) used in this pilot study, two served as controls and the other three were immunized with
P. falciparum
antigen consisting primarily of mature segmenters containing fully developed merozoites. Two injections of antigen emulsified with Freund's complete adjuvant were administered intramuscularly 3 weeks apart. Three weeks after the second vaccination, all monkeys were challenged with the homologous strain of
P. falciparum
. The control monkeys died with high levels of parasitemia within 2 weeks of challenge. The three immunized monkeys survived and showed strong protection against
P. falciparum
. These results are encouraging for the possible future development of an effective vaccine against human malaria.
Magnification in Striate Cortex and Retinal Ganglion Cell Layer of Owl Monkey: A Quantitative Comparison
Authors: Myerson Joel , Manis Paul B. , Miezin Francis M. , Allman John M.
Published: October 2006

Magnification, the relative size of the neural representation of a portion of the visual field, decreases more rapidly with increasing visual field eccentricity in striate cortex than in the retinal ganglion cell layer of the owl monkey (
Aotus trivirgatus
); the proportion of the cells in striate cortex devoted to central vision is much larger than the comparable proportion of retinal ganglion cells. Magnification in striate cortex is a power function of magnification in the retinal ganglion cell layer. A formula for convergence (ganglion cells to cortical neurons) follows from this relationship.
Risk with Energy from Conventional and Nonconventional Sources
Authors: Inhaber Herbert
Published: October 2006

Risk to human health was compared for five conventional and six nonconventional energy systems. The entire cycle for producing energy was considered, not just part. The most important conclusion drawn is that the risk to human health from nonconventional sources can be as high as, or even higher than, that of conventional sources. This result is produced only when the risk per unit energy is considered, rather than the risk per solar panel or windmill. The risk from nonconventional energy sources derives from the large amount of material and labor needed, along with their backup and storage requirements. Risk evaluation is a relatively new discipline, and therefore the results presented here can be considered only a beginning. However, society should keep relative risk in mind when evaluating present and future energy sources.