bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic instability in
Drosophila melanogaster: De novo
induction of putative insertion mutations
Authors: Green M. M.
Published: May 2006

The capacity of a so-called male recombination (MR) chromosome in
Drosophila melanogaster
to generate mutations at 14 X-chromosome loci specifying visible phenotypes was investigated. Appreciable increases in mutation were found at three loci
y, sn
, and
ras
. Tests of represnetative mutants generated at each locus establish all to be putative insertion mutants, as judged by their spontaneous mutability. These facts suggest that insertion mutation production may be a general function of MR chromosomes. The relationship of the MR chromosomes to established insertion elements (IS and Mu) is discussed.
Gene regulation in
Drosophila mulleri, D. arizonensis
, and their hybrids: The nucleolar organizer
Authors: Bicudo Hermione E. M. C. , Richardson R. H.
Published: May 2006

Typically,
Drosophila
have nucleolar organizer regions (NORs) confined to the sex chromosomes. Salivary gland cells of hybrids between
Drosophila mulleri
females and
D. arizonensis
males exhibit features in nucleolar organizer regulation that differentiate the species on one hand, and which show an interplay between the X and the microchromosome on the other hand.

In the hybrid females only the X chromosome from
D. arizonensis
appears to be attached to the nucleolus. In the hybrid males the X chromosome, from
D. mulleri
, also does not seem to contain a functional NOR. However, in hybrid males the microchromosome from
D. arizonensis
increases greatly in size and appears to be associated with the nucleolus. The increase in size of the microchromosome involves a 4-fold increase in DNA content. In
D. arizonensis
and in hybrid females the NOR of the microchromosome appears to be suppressed. In the absence of an
arizonensis
X chromosome, the NOR of the microchromosome typically is active, while the NOR on the
mulleri
X chromosome remains suppressed. Therefore, the ribosomal cistrons and interchromosomal regulator element appears to be duplicated on both the X chromosome and microchromosome of
D. arizonensis
, but with epistatic suppression of the microchromosomal NOR by the
arizonensis
X-linked NOR. Either
arizonensis
NOR, X linked or microchromosomal, suppresses the
mulleri
NOR.
Zinc-binding ligands in milk and intestine: a role in neonatal nutrition?
Authors: Hurley L S , Duncan J R , Sloan M V , Eckhert C D
Published: May 2006

The hypothesis that a zinc-binding ligand (ZBL) recently discovered in human milk but absent from cow's milk might be related to zinc nutrition in the neonate was investigated. The zinc-binding characteristics of rat milk were examined to determine if the rat was a suitable model. By gel filtration, rat milk was found to contain a ZBL with characteristics similar to those of the ZBL found in human milk. A similar ZBL was identified in the intestinal mucosa of rats 16 days of age and older but was absent in rats from birth to 16 days. These results support the hypothesis that the ZBL of maternal milk may enhance zinc transport in the neonatal period before the development of intestinal mechanisms for zinc absorption.
Occurrence of somatostatin-like immunoreactivity in some peripheral sympathetic noradrenergic neurons
Authors: Hökfelt T. , Elfvin L. G. , Elde R. , Schultzberg M. , Goldstein M. , Luft R.
Published: May 2006

By means of the indirect immunofluorescence technique of Coons and collaborators, somatostatin-like immunoreactivity has been demonstrated in principal ganglion cells of some sympathetic ganglia. The noradrenergic nature of these cells was established by “staining” of the same or consecutive sections with antiserum to dopamine β-hydroxylase [dopamine β-monooxygenase; 3,4-dihydroxyphenylethylamine, ascorbate:oxygen oxidoreductase (β-hydroxylating), EC 1.14.17.1], the enzyme converting dopamine to noradrenaline (norepinephrine). In guinea pigs the somatostatin immunoreactive material was found in almost two-thirds of all principal ganglion cells of the coeliac-superior mesenteric ganglion complex (anterior inferior part) and of the inferior mesenteric ganglion, but only in a few cells of the superior cervical ganglion. It appeared to be localized close to the Golgi complex. The present findings may represent a concomitant storage of a biogenic amine and a small peptide in a neuron. Because both noradrenaline and somatostatin may fulfill a role as a neurotransmitter or modulator, the sympathetic neurons described in this study may represent an example of mammalian nerve cells not conforming to Dale's hypothesis, i.e., the one neuronone transmitter concept.
31P nuclear magnetic resonance kinetic measurements on adenylatekinase.
Authors: Brown T R , Ogawa S
Published: May 2006

By using 31P double-resonance nucelar magnetic resonance, preliminary kinetic measurements were made on the equilibrium reaction 2ADP in equilibrium ATP +AMP catalyzed by adenylate kinase. The double-resonance method used consisted of selectively inverting the spin population in a particular chemical environment and observing the transfer of the inverted spin to another chemical environment. The chemical transfer time between AMP and ADP, free in solution, was proportional to the substrate-to-enzyme ratio, and a transfer rate of 95 mol of AMP/see per mol of enzyme was obtained. In the same series of experiments, the life-time of AMP in solution was determined from the extra broadening of its resonance line due to the active enzyme. This gave a rate 3.2 times faster than the overall transfer rate given above. From these rates and other nuclear magnetic resonance measurements wehave calculated the individual rate constants between the ternary complexes, AMP-enzyme-ATP and ADP-enzyme-ADP. In addition, we obtained one of the ADP off-rates from this latter complex. The rates on the enzyme are approximately 1250 and 500mol/sec per mol of enzyme for the forward and reverse directions, respectively. The ADP has an off-rate of 450 sec (-1).
Role of ribothymidine in mammalian tRNAPhe.
Authors: Roe B A , Tsen H Y
Published: May 2006

We have previously reported that mammalian tRNAsPhe from variation tissues contain different amounts of ribothymidine and that a uridine methylase from Escherichia coli can quantitatively convert these tRNAs to species that contain their full complement ofribothymidine at position 23 from the 3' terminus. The role of ribothymidine in mammalian tRNAs has now been investigated by studying the ability of several highly purified mammalian tRNAsPhe, differing only in their ribothymidine content, to support poly(U)-directed poly(Phe) synthesis under various conditions. Our results indicate that the ribothymidine content of mammalian tRNAPhe can be correlated with the ability of these tRNAs to functionin vitro in a low-magnesium (6 mM), ribosome wash factor-dependent, poly(U)-directed poly(Phe) synthesis system from rat liver. Specifically, the effect of increasing the ribothymidine content in a class C mammalian tRNA becomes manifest in an increased apparent maximum velocity for the overall synthesis of poly(Phe), while the apparent Michaelis constant (Km) remains essentially unchanged. It is postulated that the modifiednucleoside ribothymidine might be involved in the regulation of protein synthesis at the level of translation in mammalian liver.
Cell cycle of Saccharomycescerevisiae in populations growing at different rates.
Authors: Slater M L , Sharrow S O , Gart J J
Published: May 2006

The cell cycle of Saccharomyces cerevisiae in populations growing at different rates was analyzed by flow microflourometry. The results demonstrate that (i) variation in growth rate of the population depends mainly on variation in the G1 phase of the cell cycle, and (ii) atall growth rates initiation of DNA synthesis occurs concomitantly with initiation of budding.
Pure and mixed erythroid colony formation in vitro stimulated by spleen conditioned medium with no detectable erythropoietin.
Authors: Johnson G R , Metcalf D
Published: May 2006

Cells from CBA fetal mouse liver formed pure or mixed erythroid colonies in semisolid agarculture after stimulation by medium conditioned by pokeweed mitogen-stimulated mouse spleen cells. In general shape, the erythroid colonies resembled typical 7-day single or multiple (burst) colonies. However one-third to one-half contained, in addition to erythroid cells, macrophages and neutrophils and, less commonly, megakaryocytes or eosinophils. Culture of micro manipulated single colony-forming cells showed these erythroid colonies to be clones. Colony-forming cells declined in frequency with advancing fetal age, but low numbers were detectable in adult bone marrow. Assays of spleen conditioned medium in polycythemic mice failed to detect erythropoietin; the cloning system may detect a fetal type of erythropoietin-independent, erythropoietic cell since few were detected in adult marrow.
Dissociation of tumor promoter-stimulated ornithine decarboxylase activity and DNA synthesis in mouse epidermis in vivo and in vitro by fluocinolone acetonide, a tumor-promotion inhibitor.
Authors: Lichti U , Slaga T J , Ben T , Patterson E , Hennings H , Yuspa S H
Published: May 2006

12-O-Tetradecanoyl phorbol-13-acetate (TPA), a tumor promoter, stimulates DNA synthesis in mouse epidermal cells in vivo and in vitro. This response appears to be mediated through polyamine metabolism because ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17)activity is markedly increased shortly after promoter exposure and this induction varies in magnitude according to dose and promoter potency of a series of phorbol esters. In vitro, exogenous putrescine (0.01-10 mM) results in a dose-related increase and prolongation of promoter-stimulated DNA DNA synthesis, a phenomenon noted in other systems of polyamine-mediated growth stimulation. The anti-inflammatory steroid fluocinolone acetonide (FA), an inhibitor of tumor promotion, prevents TPA stimulation of epidermal proliferation in vivo and in vitro. In vitro, FA most effectively prevents stimulation of DNA synthesis when applied is not required. Paradoxially, FA potentiates the increase in ornithine decarboxylase activity after TPA administeration both in vivo and in vitro. Furthermore, the inhibition of TPA-stimulated DNA synthesis by FA in vitro can be reversed by exogenous putrescine. These results suggestthat FA exerts its antipromotion effect by reducing the sensitivity of the cell to polyamines or by reducing intracellular polyamine levels.
Synthesis of prostaglandin I2 (prostacyclin) by cultured human and bovine endothelial cells.
Authors: Weksler B B , Marcus A J , Jaffe E A
Published: May 2006

Cultured endothelial cells derived from human umbilical veins or bovine aorta produce a potent inhibitor of platelet aggregation. The inhibitor is synthesized from sodium arachidonate or or prostaglandin endoperoxides by a microsomal enzyme system. Tranylcypromine, a specific antagonist of prostacyclin synthetase, suppresses production of the inhibitor by endothelial cells. The inhibitor, which is ether extractable, has been identified using a two-step thin-layer radiochromatographic procedure and a synthetic prostaglandin I2 standard.With this procedure, we have shown that human and bovine endothelial cells convert sodium [3H]arachidonate to radiolabeled prostaglandin I2 and 6-keto-prostaglandin F1alpha, as wellas prostaglandin E2. Thus, endothelial cells may be non-thrombogenic in vivo because they synthesize and release prostaglandin I2, a potent inhibitor of platelet aggregation.
Further structural studies of the heavy chain of HLA antigens and its similarity to immunoglobulins.
Authors: Terhorst C , Robb R , Jones C , Strominger J L
Published: May 2006

The papain-solubilized fragment of the heavy chain of HLA-B7, which is the NH2-terminal part of the whole polypeptide chain, can be divided into three regions by mild acid and cyanogen bromide cleavages. The first 100 amino acids terminating in a methionine residue contain the carbohydrate moiety; this segment is followed by two others of molecular weights 9,999 and 13,000, each containing an intrachain disulfide bridge. The two intrachain disulfide bridges are separated by a stretch of amino acids containing an acid-labile aspartyl-prolHLA-2, A28, and AW25 contain this acid-labile peptide bond in their larger subunit. Sequencing from the acid cleavage site of HLA-7 through the third half-cystine revealed consideralbe homology with amino acid sequences around a half-cystine in immunoglobulin variable regions.
beta-Endorphin: development of tolerance and its reversal by 5-hydroxytryptophan in cats.
Authors: Hosobuchi Y , Meglio M , Adams J E , Li C H
Published: May 2006

Tolerance to beta-endorphin developed acutely in cats if the administration of the peptide was repeated within the first 24 hr. The tolerance was reversed immediately by systemic administration of the serotonin precursor, 5-hydroxytryptophan. It was further shown that 5-hydroxytryptophan potentiates the analgesic effect of the subliminal dose of beta-endorphin.
Specific receptors for des-Asp1-angiotensin II (("angiotensin III") in rat adrenals.
Authors: Devynck M A , Pernollet M G , Matthews P G , Khosla M C , Bumpus F M , Meyer P
Published: May 2006

The specific binding of angiotensin II and des-Asp1-angiotensin II ("angiotensin III") III") to rat adrenals was studied with the use of the tritiated peptides. The binding sites having maximal affinity for angiotensin II were characterized by an equilibrium dissociation constant of 3.3 to 5.2 X 10(-9) M. Angiotensin III was able to interact with these sites, and also with a class of sites with very high affinity, characterized by an equilibrium dissociation constant of 1 to 2 X 10(-10) M. These sites exhibited a greater affinity for the heptapeptide angiotensin III than for the octapeptide angiotensin II. These findings, together with the known potent aldosterone stimulating effect of angiotensin III and its presence in rat plasma, suggest that this heptapeptide could be the physiologically important steroidogenic angiotensin in this species.
Active touch exploration of extrapersonal space elicits specific electrogenesis in the right cerebral hemisphere of intact right-handed man.
Authors: Desmedt J E
Published: May 2006

Language and analytic processing are currently thought to be represented in the left hemisphere, whereas spatial and holistic processing would involve primarily the right hemisphere in man. An experimental paradigm for engaging the nonlanguage hemisphere (generally the right) is described. This involves active touch exploration with the index finger to identify the orientation of a ridge with respect to the subject's body. The task is compatible with the electronic averaging of transient event-related cerebral potentials recorded from the intact scalp. A consistent positive electrogenesis of 1-5 muV and about 0.5-1.5 sec in duration was recorded over the nonlanguage hemisphere, regardless of whether the left or the right index finger performed the tactile scanning. The lateralized specific electrogenesis did not extend to the midline, and it is to be differentiated from the decision P300 component. These findings provide a new procedure for analyzing, in intact man, measurable focal potentials associated with unique processor subsystems during cognitive behavior. The method will make it possible to investigate the dynamic distribution of processing tasks between the two hemispheres in normal man in whom the commissural integration is normal, thereby adding to the data collected on patients with unilateral brain lesions or with surgical transection of the corpus callosum.
Ultrastructural identification of substance P cells and their processes in rat sensory ganglia and their terminals in the spinal cord by immunocytochemistry
Authors: Chan-Palay Victoria , Palay Sanford L.
Published: May 2006

The unlabeled substance P (SP) antibody-peroxidase-antiperoxidase reaction was used on tissue prior to embedding in epoxy reins for ultrastructural identification of the SP cell and its immunoreactive granules. The SP cell is 10-20 μm in diameter and has sparse cytoplasm with numerous intensely reactive SP granules 100-300 nm across, large clear vacuoles, elaborate smooth endoplasmic reticulum, fragmentary rough endoplasmic reticulum, dispersed ribosomes, few mitochondria, and a modest Glogi apparatus. The large SP-reactive granules are discharged into the extracellular space, either with cell membrane intact or as unbound dense material. The membrane-bound dense granucles are transported intact through endothelial cells into the blood or are picked up by Schwann cells and fibroblasts. Other SP-reactive granules lose their limiting membranes, fragment, and then disperse into fine immunoreactive grains that bind to the extracellular matrix and to collagen. Dispersed SP-reactive granules are transported within myriad pinocytotic vesicles across endothelial cells with numerous luminal plications and are discharged into the blood. Pinocytosis of dispersed SP-reactive material, that can be detected intracellularly, also occurs in Schwann cells and fibroblasts. The SP axons to the substantia gleatinosa are unmyelinated or finely myelinated. Their synaptic varicosities display a generalized axoplasmic immunoreactivity, which also occurs in and around small vesicles. The larger SP synaptic vesicles are intensely reactive.
Alteration of cellular adhesion by nerve growth factor.
Authors: Schubert D , Whitlock C
Published: May 2006

Nerve growth factor increases the initial rates of cell-substratum and cell-cell adhesion of sympathetic nerve cell clone PC12. It also stimulates adenosine 3':5'-cyclic monophosphate accumulation in the cells, and exogenous adenosine 3':5'-cyclic monophosphate increases cell-substratum adhesion. NGH-stimulated adhesion is energy dependent and cold-sensitive and does not require de novo protein synthesis. It is probably mediated by an effect of adenosine 3':5'-cyclic monophosphate on the plasma membrane. Stimulation of cellular adhesion may be the first step in NGF-initiated neurite outgrowth by sympathetic nerve cells.
Neurotensin: immunohistochemical localization in rat central nervous system.
Authors: Uhl G R , Kuhar M J , Snyder S H
Published: May 2006

Neurotensin immunofluorescence was examined in the rat central nervous system using a well-characterized antiserum directed against this tridecapeptide. Morphological characteristics of the fluorescence indicate its association with neuronal cell bodies and processes in the brain and with cells of the anterior pituitary. Fluorescence is seen in many brain areas, with notable densities in the substantia gelatinosa zones of the spinal cord and trigeminal nucleus, central amygdaloid nucleus, anterior pituitary, median eminence, and preoptic and basal hypothalamic areas.
On the evolution of beta-galactosidase.
Authors: Hood J M , Fowler A V , Zabin I
Published: May 2006

The amino acid sequence of beta-galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23) has been compared to itself and to other proteins. Two segments, each of about 380 amino acids, comprising the first three-fourths of the polypeptide chain, were found to be very similar to each other. It is concluded that they are homologous. The carboxyl-terminal fourth has a high percentage of amino acid identities with dihydrofolate reductase of Escherichia coli, suggesting these sequences also are homologous. A model for the origin of beta-galactosidase is presented. The overall similarity of beta-galactosidase to lac repressor does not appear to be significant.
Structure of yeast phenylalanine-tRNA genes: an intervening DNA segment within the region coding for the tRNA.
Authors: Valenzuela P , Venegas A , Weinberg F , Bishop R , Rutter W J
Published: May 2006

Sixteen bacterial clones containing sequences complementary to yeast PhetRNA were isolated from a collection of hybrid plasmids containing BamHI restriction endonuclease-generated yeast DNA fragments inserted in the plasmid vector pBR315. Ten of these clones contained hybrid plasmids with distinct BamHI fragments. The sequence of the Phe-tRNA structural genes and adjacent regions of three of these clones is reported here. In the region flanking the tRNA gene, the sequence of two of the cloned DNAs is similar; the sequence of the third varies considerably. All three of the tRNA genes are bordered by A,T-rich regions. In particular, near the region coding for the 3' end of the tRNA there is a long sequence of As in the coding strand. This is reminiscent of the region of termination of transcription of the yeast 5S rRNA gene. The sequences coding for the Phe-tRNA contain an additional segment of 18 or 19 base pairs (depending upon the clone) not predicted by the yeast Phe-tRNA sequence. These intervening segments are nearly identical in the three clones and are located within the structural gene, two base pairs from the nucleotides coding for the tRNA anticodon.
DNA intermediates at the Escherichia coli replication fork: effect of dUTP.
Authors: Olivera B M
Published: May 2006

We have directly tested the hypothesis that elevated levels of dUTP cause the formation of small DNA fragments at the replication fork of Escherichia coli. Addition of increasing levels of dUTP to lysates on cellophane discs results in an increasing number of strand scissions in the newly replicated DNA. Lysates of strains defective in dUTPase produce many more scissions at the same level of dUTP. The size distribution of Okazaki pieces obtained in vivo can be reconstituted in vitro on cellophane discs if appropriate levels of dUTP are present. Although uracil excision leads to the apparent production of Okazaki pieces from both daughter strands, DNA synthesis is actually asymmetric under these conditions. De novo chain initiation events occur on only one strand. It is suggested that asymmetry of synthesis in vivo may be masked by uracil excision and other postreplication processing mechanisms.
Self-association of hemoglobin β
SH
chains is linked to oxygenation
Authors: Valdes Roland , Ackers Gary K.
Published: May 2006

Self-association of unliganded β
SH
chains into tetramers (4 β
1
[unk] β
4
) is experimentally found to be energetically less favorable (Δ
G
0
= -19.05 ± 0.30 kcal) than the corresponding oligomerization of fully oxygenated chains (4 β
1
X [unk] β
4
X
4
; Δ
G
0
= -22.45 ± 0.35 kcal). Hence the tetramers must bind oxygen with a higher affinity than that of dissociated chains. Calculations are presented showing why this affinity difference is not easily detected. The linkage is in a direction opposite to that exhibited by normal hemoglobin A, in which oligomerization of high-affinity unliganded dimers (2 αβ [unk] α
2
β
2
) leads to tetramers with decreased oxygen affinity. In contrast, the oligomerization of high-affinity, unliganded β
SH
chains leads to tetramers with even higher affinity. The results imply the existence of at least two conformational states for β chains.

Effects of inositol hexaphosphate on β chain association were investigated. Inositol hexaphosphate was found to have no measurable effect at pH 7.4, in contrast to pH 7 where very pronounced effects have been observed. Some theoretical aspects of the linkages are presented and the relationship of the findings to concepts of structural transition and allosteric regulation is discussed.

In contrast to the β chains, self-association of α chains into dimers was found to occur with the same free energy in both unliganded and fully oxygenated states. Thus, the self-association of α chains is not linked to oxygenation.
Relationship between dibutyryl cyclic AMP and microtubule organization in contracting heart muscle cells.
Authors: Nath K , Shay J W , Bollon A P
Published: May 2006

Rhythmic and synchronous contractions of interconnecting myocyte cultures prepared from fetal rat hearts are arrested upon the addition of 0.2--2.0 mM N6, O2'-dibuturyladenosine 3':5'-cyclic monophosphate (Bt2cAMP). The contractions arrested by Bt2cAMP are restored either by diluting the Bt2cAMP from the media or by adding colchicine. While colchicine restores Bt2cAMP-arrested myocyte contractions at concentrations as low as 1.0 micron, the inactive isomer lumicolchicine shows no effect. Morphologically, Bt2cAMP treatment of myocyte cultures results in the appearance of numerous elongated cellular processes not present in control cultures. Ultrastructural examination indicates that in Bt2cAMP-treated cells the intracellular distribution of microtubules is altered such that these organelles appear to accumulate in parallel arrays. In cells not treated with Bt2cAMP, the microtubules appear randomly oriented, while in cells treated with only colchicine, intact microtubules are not observed. The relationship between microtubules an heart cell contraction is discussed.
Altruism: Its characteristics and evolution
Authors: Darlington P. J.
Published: May 2006

Altruism is a group phenomenon in which some genes or individuals, which must be presumed to be selfish, benefit others at cost to themselves. The presumption of selfishness and the fact of altruism are reconciled by kin-group selection and by reciprocal altruism. Kin-group selection is clearly visible only in special cases; its role even among social insects may be overestimated; it is probably usually inhibited by competition. However, reciprocal altruism is ubiquitous. All altruism is: (
i
) potentially reciprocal; (
ii
) potentially profitable to altruists as well as to recipients; (
iii
) environmentally determined, usually by position of individuals in group or environmental situations; and (
iv
) a net-gain lottery. These generalizations are illustrated by four idealized cases; the difficulty of applying them to real cases is illustrated by alarm-calling in groups of birds. Although altruism is a group phenomenon, it evolves by individual selection, by processes equivalent to co-evolutions. Its evolution is: (
i
) opposed by competition; (
ii
) costly, complex, and slow, and tending to produce an imprecise flexible altruism rather than a precisely detailed one; and (
iii
) supplemented by group selection (differential extinction of groups). That altruism in human beings conforms to these generalizations is a good working hypothesis. However, analysis does not “take the altruism out of (human) altruism.” Humans do not calculate it, but behave altruistically because they have human altruistic emotions.
A model of kin selection for an altruistic trait considered as a quantitative character.
Authors: Yokoyama S , Felsenstein J
Published: May 2006

Conditions for natural selection to favor increase of a quantitative character are derived for a model in which individuals associate in groups of size n. It is assumed that the logarithm of the fitness of an individual is the sum of two parts, one proportional to the individual's own phenotype, and the other to the mean phenotype in its group. The resulting conditions for the trait to increase under natural selection are analogous to the results found previously in single-locus kin selection models.
Periodic loss of reactivity of a myeloma tumor with cytotoxic thymus-derived lymphocytes.
Authors: Russell J H , Hale A H , Ginns L C , Eisen H N
Published: May 2006

During each transplantation passage of a line of mouse myeloma tumor MOPC-315 through syngeneic (BALB/c) hosts, the tumor cells lose reactivity with cytotoxic thymus-derived lymphocytes directed against products of the BALB/c major histocompatibility complex (H-2d) and regain reactivity on transfer to fresh hosts. In contrast to this cyclical change, the tumor cells remain uniformly reactive with anti-H-2d alloantisera throughout the transplantation cycle.
Anti-epidermal-cell-surface pemphigus antibody detaches viable epidermal cells from culture plates by activation of proteinase.
Authors: Farb R M , Dykes R , Lazarus G S
Published: May 2006

Immunoglobulin from pemphigus patients binds to the surface of mouse epidermal cells in culture. Cells incubated with the pemphigus antibody are easily detached from culture plates whereas cells incubated with serum from normal patients remain on the plate. Pemphigus antibody-mediated cell detachment is blocked by the addition of the proteinase inhibitors soybean trypsin inhibitor and alpha2-macroglobulin to the culture media. Detachable cells are viable, and activation of the complement cascade is not necessary for cell detachment. The anti-cell-surface antibody of pemphigus appears to disrupt adhesion between viable epidermal cells by activation of proteinase.
[
18
F]Fluoro-dopa, an analogue of dopa, and its use in direct external measurements of storage, degradation, and turnover of intracerebral dopamine
Authors: Garnett E. S. , Firnau G. , Chan P. K. H. , Sood S. , Belbeck L. W.
Published: May 2006

3,4-Dihydroxy-5-fluorophenylalanine, fluorodopa, was injected into rats in which unilateral lesions of the nigrostriatal pathway had been made. The rats rotated towards the side with the lesions, thus providing further evidence that fluoro-dopa is an analogue of dopa. [
18
F]Fluoro-dopa was then injected intravenously into fully conscious baboons. A well-collimated scintillation detector, aligned along the occipitomental axis, recorded the accumulation of
18
F in the brain. Control animals accumulated
18
F continuously for 100 min. This accumulation represents net transport of [
18
F]fluoro-dopa from blood to brain, decarboxylation to [
18
F]fluoro-dopamine, storage, and degradation of [
18
F]fluoro-dopamine. α-Methyl-dopa, a competitive inhibitor of dopa transport and decarboxylation, prevented the accumulation of
18
F; reserpine, known to release stored intracerebral dopamine, discharged
18
F; pargyline, a monoamine oxidase inhibitor, and haloperidol, a known augmentor of intracerebral dopamine turnover, increased the rate of accumulation of
18
F. These changes in the accumulation of intracerebral
18
F, after [
18
F]fluoro-dopa, were commensurate with the known action of the drugs used to induce them and demonstrate the use of a γ-emitting precursor of a neurotransmitter to monitor simply, atraumatically, and externally the intracerebral metabolism of the transmitter in fully conscious primates. When applied to man, the same technique should be able to provide more conclusive evidence than is presently available for the role of catecholamines in schizophrenia and depression. It should also provide further insight into the natural history of nigrostriatal diseases and the action of drugs used in their treatment.
An enzymatic defect in the obese (
ob/ob
) mouse: Loss of thyroid-induced sodium- and potassium-dependent adenosinetriphosphatase
Authors: York David A. , Bray George A. , Yukimura Yaichiro
Published: May 2006

Genetically obese (
ob/ob
) mice, mice that became obese after treatment with gold thioglucose, and lean animals were studied in the euthyroid state, after induction of hypothyroidism, and after treatment with triiodothyronine. The activity of glycerol 3-phosphate dehydrogenase (
sn
-glycerol-3-phosphate:(acceptor) oxidoreductase; EC 1.1.99.5] was reduced in the livers from hypothyroid animals and was increased by treatment with triiodothyronine in all groups. The activity of the ouabain-suppressible sodium- and potassium-dependent ATPase (ATP phosphohydrolase; EC 3.6.1.3) was increased by triiodothyronine and reduced by hypothyroidism in the lean and gold thioglucose-treated obese animals. In the obese (
ob/ob
) mice, on the other hand, treatment with triiodothyronine did not increase the activity of this enzyme, which remained at the level found in hypothyroid animals. This enzymatic activity was reduced in both liver and kidney. Adenylate cyclase [ATP pyrophosphate-lyase (cyclizing); EC 4.6.1.1] activity in liver membranes, however, was similar in all three groups of mice. This enzyme complex was activated by glucagon and was unaffected by treatment with thyroid hormones. The lack of a thyroid-dependent ouabain-suppressible (Na
+
+ K
+
)-ATPase in the tissues of the obese (
ob/ob
) mouse could explain most, if not all, of the abnormalities that have been described in this animal.
Erythro-9-(2-hydroxy-3-nonyl)adenine as a specific inhibitor of herpes simplex virus replication in the presence and absence of adenosine analogues.
Authors: North T W , Cohen S S
Published: May 2006

Erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA; erythro-9-[3-(hydroxynonyl)]adenine), a reversible inhibitor of adenosine deaminase, significantly inhibits replication of herpes simplex virus (HSV), whereas the more active inhibitor of the deaminase, 2'-deoxycoformycin, does not. At 10 micron EHNA, which does not affect viability, growth, or DNA synthesis of uninfected HeLa cells, production of HSV and HSV-specific DNA is inhibited 75-90% and 60%, respectively. HSV multiplies normally in cells pretreated with EHNA and washed to remove this inhibitor. EHNA (10 micron) also markedly potentiates the toxicity of adenine arabinonucleoside and of cordycepin (3'-deoxyadenosine) against HeLa cells and against the production of HSV in those cells. Cordycepin alone (10 micron) does not inhibit HSV replication whereas in combination with 10 micron EHNA there is a greater than 99% inhibition of virus production. Under these conditions, RNA synthesis is inhibited by more than 80% whereas protein and DNA synthesis are inhibited to a lesser extent; in this system, virtually all of the DNA synthesis in infected cells is that of host DNA. Thus, EHNA appears to affect the synthesis of HSV DNA specifically in two different ways, depending on whether it is used alone or in the presence of cordycepin.
Symmetry mismatch and DNA packaging in large bacteriophages.
Authors: Hendrix R W
Published: May 2006

A model is presented for the mechanism of packaging double-stranded DNA into phage heads. The model is based on, and rationalizes, the mismatch in symmetry between the heads and tails of large bacteriophages. DNA movement is postulated to be mediated by a rotating protein structure at the tail-proximal vertex of the head.
Interferoids:
In vitro
and
in vivo
conversion of native interferons to lower molecular weight forms
Authors: Stewart William E. , Chudzio Tadeusz , Lin Leo S. , Wiranowska-Stewart Marzenna
Published: May 2006

Mouse interferons appear as two distinct molecular forms, one migrating at 38,000 daltons in sodium dodecyl sulfate/polyacrylamide gels and one migrating at 22,000 daltons; these interferons comprise about 80% and 20% of total activities, respectively. When such interferon preparations are briefly exposed to acidic periodate buffer, the larger interferon species is apparently converted to the smaller form since the activity at 38,000 daltons is completely eliminated while the activity at 22,000 daltons increases significantly; upon further oxidative cleavage, antiviral activity becomes detectable migrating at 15,000 daltons. Because no native mouse interferon has been reported as such small molecules, this antiviral activity is designated mouse “interferoid” to distinguish it from the native, naturally occurring interferon forms. Prolonged acidperiodate treatment fails to quantitatively convert the 22,000-dalton interferon to the 15,000-dalton interferoid since both are inactivated. When L cells are induced to make interferon in the presence of glycosylation inhibitors, either D-glucosamine or 2-deoxy-D-glucose, they produce approximately normal levels of antiviral activity. However, when such preparations are analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis, little activity (<10%) migrates as either the 38,000-dalton or 22,000-dalton native interferons. The interferons and interferoid are antigenically and hydrophobically indistinguishable. These data suggest that induced mouse cells normally synthesize the interferoid as a precursor polypeptide that is either partially or extensively modified by carbohydrate additions to produce, respectively, the 22,000- and 38,000-dalton mouse interferons. Because interferoid is apparently fully biologically active without these moieties, chemical synthesis of such unmodified polypeptides or active fragments from them appears feasible.
beta-Galactosidase chimeras: primary structure of a lac repressor-beta-galactosidase protein.
Authors: Brake A J , Fowler A V , Zabin I , Kania J , Müller-Hill B
Published: May 2006

A protein possessing both lac repressor and beta-galactosidase activities in a single polypeptide of about 155,000 daltons was purified from a deletion mutant of Escherichia coli in which the lacI and Z genes are fused. A 77-residue cyanogen bromide peptide containing the fusion joint was isolated. A radioimmunoassay with an antibody prepared against CNBr2 (residues 3-92) of beta-galactosidase was used to monitor its purification. The sequence of the joining peptide was determined by analysis of tryptic peptides and by automatic sequencer analysis. The site of joining is from residue 355 of lac repressor to residue 24 of beta-galactosidase (or 356 to 25), indicating that the last 4 residues at the carboxyl terminus of lac repressor and the first 23 residues at the amino terminus of beta-galactosidase are not essential for the activities of these two proteins. The exact site of the fusion is not known because lac repressor residue 356 and beta-galactosidase residue 24 are both leucine residues. Examination of the nucleotide sequences around the two end points of the deletion revealed a homology of 9 identities in a stretch of 11 base pairs.
Room-temperature magnetic properties of oxy- and carbonmonoxyhemoglobin
Authors: Cerdonio M. , Congiu-Castellano A. , Calabrese L. , Morante S. , Pispisa B. , Vitale S.
Published: May 2006

The magnetic susceptibility and the density of human oxy-(HbO
2
) and carbonmonoxyhemoglobin (HbCO) solutions of various concentrations have been measured at room temperature, with pure water used as a calibrant. Solutions of unstripped and stripped HbO
2
at pH 7.2 in unbuffered water solvent were always found to be
less
diamagnetic than pure water, whereas solutions of HbCO in identical conditions were always found to be
more
diamagnetic than pure water. After correcting for concentration-dependent density changes and assuming the HbCO samples to be fully diamagnetic, the paramagnetic reduction of the diamagnetic susceptibility of HbO
2
corresponds to a molar susceptibility per heme (χ

M

heme
) of 2460 ± 600 × 10
-6
cgs/mol.
Bacteriophage lambda carrying the Escherichia coli chromosomal region of the replication origin.
Authors: Miki T , Hiraga S , Nagata T , Yura T
Published: May 2006

A transducing phage lambdaasn was isolated. The late gene region of its genome was found to have been substituted by an Escherichia coli chromosomal segment containing the genes bgIR, bgIC, glmS, uncA, and asn. Restriction endonuclease cleavage mapping and electron microscopic analysis of the lambdaasn DNA revealed that the size of the bacterial segment is approximately 1.75 X 10(7) daltons, corresponding to about 26.4 kilobases. The circular DNA of lambdaasn was digested with restriction endonuclease EcoRI, diluted, and sealed with DNA ligase. When the reaction mixture was used to transform a recipient E. coli strain, a small plasmid of about 1 X 10(7) daltons (named pMCR115) was obtained. Restriction endonuclease cleavage mapping of pMCR115 and other evidence suggested that it contained the replication origin (oriC) of the E. coli chromosome.
Systemic bacillus Calmette-Guérin (BCG) activates natural suppressor cells.
Authors: Bennett J A , Rao V S , Mitchell M S
Published: May 2006

Addition of normal C57BL/6 mouse bone marrow cells to an in vitro culture of normal C57BL/6 spleen cells and allogeneic P815-Y tumor cells inhibited the development of cell-mediated immunity. Bacillus Calmette-Guérin (BCG) enhanced the suppressive activity of these bone marrow cells as early as 2 days after its intravenous administration to donor mice and elicited similar activity in the spleen by 7 days. Concomitant with the appearance of suppressor cells in the spleen there was a decrease in bone cell number and an increase in spleen cell number. While normal spleen cells failed to inhibit immunization, spleen cells from thymectomized, irradiated, bone marrow-reconstituted mice were inhibitory. Administration of BCG further increased the suppressive activity of spleen cells in these T cell-deprived mice. From this evidence it appears that systemic administration of BCG activates natural suppressor cells in the bone marrow and elicits suppressor cells in the spleen through the migration and colonization of the spleen by bone marrow elements.
Epstein-Barr virus and human chromosomes: close association of the resident viral genome and the expression of the virus-determined nuclear antigen (EBNA) with the presence of chromosome 14 in human-mouse hybrid cells.
Authors: Yamamoto K , Mizuno F , Matsuo T , Tanaka A , Nonoyama M , Osato T
Published: May 2006

Fourteen hybrid clones derived from the fused cultures of human lymphoblastoid FV5 cells and 5-bromodeoxyuridine-resistant mouse fibroblastic MCB2 cells grown in hypoxanthine/aminopterin/thymidine selective medium were examined for the presence of Epstein-Barr virus (EBV) DNA, the expression of the virus-determined nuclear antigen (EBNA), and the presence of human chromosomes, in the course of serial passage in vitro. Among the hybrid clones tested, 3 were positive for EBV DNA and EBNA, whereas the remaining 11 were totally negative. The chromosome investigations showed that human chromosome 14 was consistently involved in all three EBV genome-positive and EBNA-positive hybrid clones, but not in any negative clones. In 10 subclones isolated from 1 of the 3 positive clones, all of which contained only chromosome 14 of the human chromosomes, a concordant segregation of EBNA, EBA DNA, and chromosome 14 was evident. These findings suggest that the resident EBV genome is closely associated with chromosome 14 and the presence of this particular chromosome alone is sufficient for the maintenance and the expression of EBV genetic information in human lymphoblastoid cells.
Appearance of beta-endorphin-like immunoreactivity in human ventricular cerebrospinal fluid upon analgesic electrical stimulation.
Authors: Akil H , Richardson D E , Barchas J D , Li C H
Published: May 2006

beta-Endorphin-like immunoreactivity in human ventricular cerebrospinal fluid was measured with a specific radioimmunoassay. The subjects were undergoing a surgical procedure for relief of chronic intractable pain. This procedure involved the focal stimulation of a medial thalamic site adjacent to the wall of the third ventricle. Samples were collected before and during the analgesic stimulation. No beta-endorphin-like immunoreactivity could be detected prior to stimulation, suggesting that baseline levels are below 25 fmol/ml of cerebrospinal fluid. Electrical stimulation led to substantial increases (13- to 20-fold) in immunoreactive material in every subject. These results suggest that beta-endorphin-like material can be released into the ventricular system and may contribute to the pain blockade that results from periventricular stimulation.
A major serine protease in rat skeletal muscle: Evidence for its mast cell origin
Authors: Woodbury Richard G. , Everitt Michael , Sanada Yukihiro , Katunuma Nobuhiko , Lagunoff David , Neurath Hans
Published: May 2006

The physical, chemical, and immunologic properties of a protease from rat skeletal muscle, proposed to function in the degradation of certain intracellular enzymes, are identical to those of a chymotrypsin-like serine protease isolated from peritoneal mast cells. The results of polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and 8 M urea indicate that the two rat proteases have identical mobilities corresponding to a molecular weight of 26,000. The relative amino acid compositions of the proteases are nearly identical. Immunodiffusion tests for crossreaction between the muscle protease and antisera directed toward mast cell protease indicate that the former is immunologically identical to mast cell protease. The first 35 amino-terminal residues of the two enzymes are identical and indicate homology of these proteins to other mammalian serine proteases. The sequence analysis of the protease from muscle was extended for an additional 16 positions, and comparison of this amino-terminal sequence with that of a similar enzyme from small intestine showed approximately 75% sequence identity. In contrast, only 40% of the residues in this region of bovine chymotrypsin A were found at corresponding loci in rat muscle protease. It is concluded that the protease from muscle or mast cells is closely related to the enzyme from small intestine which recently was localized in the “atypical” mast cells of gut mucosa [Woodbury, R. G., Gruzenski, G. M. & Lagunoff, D. (1978)
Proc. Natl. Acad. Sci. USA
75, 2785-2789].
Bomebesin: specific binding to rat brain membranes.
Authors: Moody T W , Pert C B , Rivier J , Brown M R
Published: May 2006

The binding of a radiolabeled bomebesin analogue to rat brain membranes was studied. [125I-Tyr4]Bombesin bound with high affinity (KD = 3 nM) to a single class of non-interacting sites. Binding was specific, saturable (3.8 pmol of sites/g of wet tissue), and reversible. Regional and subcellular distribution studies showed that the density of sites was 7-fold greater in the hippocampus than the medulla/pons and greater in synaptosomal fractions than in mitochondrial or nuclear fractions. The abilities of numerous bombesin analogues to induce hypothermia and to inhibit [125I-Tyr4]bombesin-binding activity correlate well. Numerous amino acid residues near the CONH2-terminal are required for high-affinity binding and biological potency.
Requirement of a plasmid-encoded protein for replication in vitro of plasmid R6K.
Authors: Inuzuka M , Helinski D R
Published: May 2006

Conditions are described for the replication of exogeneous R6K DNA in an in vitro system prepared from Escherichia coli cells. Replication of plasmid DNA in this system is semiconservative and sensitive to actinomycin D, novobiocin, arabinofuranosyl-CTP,N-ethylmaleimide, and inhibitors of DNA-dependent RNA polymerase. An ammonium sulfate fraction prepared from cells carrying the R6K plasmid is required for replication. A direct role in replication for a plasmid-encoded protein, designated pi, in this fraction is indicated by the inactivity of this fraction when prepared from cells carrying a temperature-sensitive mutant plasmid and the thermolability of this fraction when prepared from cells carrying a partial revertant of the mutant plasmid. This plasmid-encoded protein is necessary for the initiation of R6K DNA replication and functions before or during the formation of nascent RNA in the initiation process. The results of titration assays of this protein using various template DNAs suggest that the protein interacts with the plasmid DNA at the region essential for DNA replication.
Evidence for translocation of DNA sequences during sea urchin embryogenesis.
Authors: Dickinson D G , Baker R F
Published: May 2006

Hairpin-like DNA was prepared in vitro from the family of sequences that are inverted relative to each other and, as pairs, are relatively homologous and adjacent on the sea urchin genome. The majority of these hairpins are shown to have base pair mismatch positions distributed along their stems. Comparison of the hairpins derived from the DNA of morula, blastula, and gastrula stage embryos shows that during embryogenesis there are changes in the average number and position of S1 nuclease-sensitive base pair mismatch sites on the majority of the hairpin stems. Our data indicate that during early embryogenesis there are sequence changes in vivo within the majority of the adjacent inverted repeat sequences of the sea urchin genome. We have also found that there is higher specificity for the occurrence of sequence-change events within that fraction of the inverted repeat sequences that are methylated in vivo.