bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cation loading of red blood cells
Authors: Garrahan P. J. , Rega A. F. 
Published: December 2014

1. p‐Chloromercuribenzenesulphonate induces an increase in the permeability of red cell membranes to monovalent cations. Under suitable conditions the increase in permeability is large enough to allow cell cation concentration to approach equilibrium with that in the suspending media in 24 hr at 5° C.2. The effect of the mercurial on permeability is fully reversed by cysteine.3. These effects provide the basis for a simple procedure for preparing red blood cells of almost any desired sodium or potassium content.4. If hypertonic media are used, cells can be obtained with normal volume but in osmotic equilibrium with the hypertonic solutions.
Physical and chemical reactions of phosphates in red cell membranes in relation to active transport
Authors: Blake A. , Leader D. P. , Whittam R. 
Published: December 2014

1. A study has been made of the chemical reactions associated with the active transport of sodium and potassium in human red cells, with special reference to the action of oligomycin and the labelling of cell membranes by radioactive ATP.2. Oligomycin had the same effects as ouabain on the various aspects of active transport in red cells. It inhibited sodium and potassium transport, the transport ATPase, and the lactate production that is controlled by the sodium pump.3. When cell membranes were incubated with radioactive ATP they became labelled. The labelling, however, was unrelated to the activity of the transport ATPase. Incubation of membranes and intact cells showed that the labelling was a result of physical adsorption of inorganic phosphate to the membranes.4. The results show that if there is a phosphate intermediate in the reaction of the transport ATPase in human red cell membranes, then it is present in amounts too small to be detectable by the methods that have been successfully used with organs such as brain and kidney.
Cross‐innervated mammalian skeletal muscle: histochemical, physiological and biochemical observations
Authors: Dubowitz Victor 
Published: December 2014

1. Cross‐innervation of the slow soleus and fast flexor hallucis longus or flexor digitorum longus muscles has been performed in new‐born kittens and rabbits and in adult cats.2. The effects on the histochemical and structural properties of the muscle have been studied and compared with the changes in the contractile properties.3. Cross‐innervation has produced a dramatic change in histochemical pattern in the fast muscles, with the development of areas of muscle fibres indistinguishable from normal soleus muscle. The converse change from the histochemical pattern of slow soleus to that of fast muscle has also occurred, but has been less consistent.4. It is concluded that the neural influence determining the contractile properties of fast and slow muscle also has a profound controlling influence on the structure and metabolic activity of the muscle fibres.5. No significant changes could be demonstrated biochemically in the ATPase activities of the fast and slow muscles following cross‐innervation.
Effects of physalaemin on some exocrine secretions of dogs and rats
Authors: Bertaccini G. , de Caro G. , Impicciatore M. 
Published: December 2014

1. Physalaemin, an endecapeptide recently found in the skin of the South American amphibian Physalaemus fuscumaculatus, possesses, besides a marked hypotensive action and a powerful sialogogic activity, also a stimulant activity on other exocrine secretions.2. Exocrine structures which were more potently stimulated by the peptide were lacrimal glands and exocrine pancreas. In the anaesthetized dog the threshold lacrimatory dose was 0·05‐0·3 μg/kg; in the rat the threshold dose was 2·5‐5 μg/kg. The minimum active dose on exocrine pancreas of the dog was 0·05‐0·5 μg/kg.3. Physalaemin did not influence the gastric acid secretion of the dog at the maximum tolerated dose (40 μg/kg). Gastric acid secretion of the rat was stimulated very little if at all.4. In the dog the peptide caused some changes in the bile flow which were connected more with contracture of the gall‐bladder than with a true secretory stimulant activity. In the rat the peptide was completely ineffective.5. The results obtained after administration of sympatholytic and parasympatholytic agents suggest that the action of the peptide is at least partly independent from the autonomic nervous system.
A comparison of the nerve impulses of mammalian non‐medullated nerve fibres with those of the smallest diameter medullated fibres
Authors: Paintal A. S. 
Published: December 2014

1. Filaments were dissected from the aortic nerve of cats and impulses recorded monophasically in vivo.2. The temporal characteristics of impulses of non‐medullated fibres were compared with those of medullated fibres with conduction velocities between 4·5 and 12 m/sec. There were no obvious qualitative differences between the two types of fibres and they appeared to belong to a homogeneous sample.3. In non‐medullated fibres the rise time, fall time and absolute refractory period varied inversely with conduction velocity, the relation being similar to that in the medullated fibres. There was practically no difference between the temporal characteristics of the fastest non‐medullated fibres and those of the slowest medullated fibres, a result which might throw light on the question why fibres below 1 μ in diameter are not medullated.4. The mean blocking temperature of sixteen non‐medullated fibres was 4·3° C, a value that was significantly different from the mean blocking temperature of sixteen medullated fibres (6·5° C).
The gradient of electrical potential difference and of sodium and potassium of the gut contents along the caecum and colon of normal and sodium‐depleted rats
Authors: Edmonds C. J. 
Published: December 2014

1. The Na, K and water content of stools, and of gut contents removed from the terminal ileum, caecum and colon were determined in normal and Na‐depleted rats and the p.d. across the colon wall measured at the site of removal of each specimen.2. During passage through the caecum and colon, especially the ascending segment of colon, the faecal Na and water content fell considerably, K content being unchanged in the normal rats and falling in the Na‐depleted. Na concentration of the faecal water fell but K concentration rose owing to water absorption.3. Feeding normal rats with a sulphonated polystyrene resin caused a considerable Na loss in the stool, the ratio Na/(Na+K) being consistently greater than in rats not taking resin. Resin induced little Na but much K loss in Na‐depleted rats.4. The electrical p.d. across the colon wall varied little over the length of the caecum and colon in normal rats, rarely exceeding 20 mV, the serosa being +ve with respect to lumen. Potential difference measurements were greater in Na‐depleted rats, and those of the caecum and descending colon were consistently higher than those of the ascending colon. There was a similar pattern in resin‐fed rats but potentials tended to be higher.5. K concentration of the gut contents was always greater than could be accounted for if K were passively distributed across the colonic mucosa.6. It was concluded that: (i) active Na absorption was stimulated by Na depletion; (ii) K was probably actively transported into the colon lumen, and when unabsorbable anions were present in the gut K secretion was critically important in Na absorption; (iii) the elevation of p.d. associated with Na depletion was probably associated with the stimulated Na transport.
Transport of sodium and secretion of potassium and bicarbonate by the colon of normal and sodium‐depleted rats
Authors: Edmonds C. J. 
Published: December 2014

1. Ascending and descending colonic segments of normal and Na‐depleted rats were perfused in vivo with isotonic solutions of varying Na concentration and the unidirectional Na fluxes and secretion rate of K and bicarbonate and the transmucosal electrical p.d. were measured.2. Potential difference was greater in Na‐depleted rats, especially towards the distal end of the descending colon. With reduction of luminal Na concentration, p.d. was reduced.3. The ascending and descending segments were similar in regard to Na transport except that the latter had lower passive permeability. Na depletion caused an increase of Na influx rate, Na net flux rate and Na exchange diffusion whilst the mucosal passive Na permeability decreased. These changes resulted in a reduction in the critical luminal Na concentration, i.e. the concentration at which the unidirectional fluxes were equal.4. K secretion rate was similar in the ascending and descending colon and was increased by Na depletion. In all rats, it was reduced when the luminal Na concentration was low.5. Bicarbonate secretion rate was unaffected by the Na depletion and all solutions remained isotonic during perfusion.6. The results confirmed that active Na transport was stimulated by Na depletion but indicated that this was probably not the only factor in the elevation of transmucosal p.d.
The influence of the polar anastomotic vessels on autoregulation and the urinary excretion of water and sodium by perfused cat kidneys
Authors: Lockett Mary F. 
Published: December 2014

1. Cat kidneys have been perfused from pump‐oxygenator and from heart‐lung circuits.2. Kidneys perfused from the pump‐oxygenator circuit excreted more water and sodium and showed higher values for sodium: potassium in urine than kidneys perfused from heart—lung circuits. Renal plasma flow and the clearances of creatinine and p‐aminohippuric acid were similar for preparations perfused by the two different methods.3. Dorsal and ventral polar anastomotic vessels appeared to communicate directly with sheaves of vasa recta in the kidneys of young cats through interlobar vessels.4. Ligature of these polar anastomotic vessels impaired autoregulation of blood flow in perfused cat kidneys.5. Open drainage from these polar vessels during perfusion increased the rates of excretion of water and sodium.6. Histological preparations made from kidneys perfused from pump‐oxygenator and from heart—lung circuits for periods of 5‐6½ hr showed that the nephrons remain undamaged. The diameters of the tubules correlated with the rates of urine flow immediately before fixation.
Hormonal actions of the heart and of lungs on the isolated kidney
Authors: Lockett Mary F. 
Published: December 2014

1. An hormonal influence of the heart on the isolated kidney has been demonstrated by insertion of hearts into pump‐oxygenator circuits during renal perfusions.2. This hormone is a steroid which is secreted from the heart into the cardiac venous blood in response to reduction in venous input. The steroid is extractable from heart muscle.3. The actions of the cardiac steroid resemble those of aldosterone but are of shorter latency. Renal blood flow (R.B.F.) and glomerular filtration rate (G.F.R.) rise; urine flow, Na‐concentration and Na/K decrease.4. An hormonal influence of lungs on the isolated kidney is also demonstrated. This hormone is not a steroid. It is antidiuretic and Na‐retaining: the concentration of urinary Na rises: Na/K remains unchanged.
An analysis of facilitation of transmitter release at the neuromuscular junction of the frog
Authors: Mallart A. , Martin A. R. 
Published: December 2014

1. Experiments were done on Mg‐blocked neuromuscular junctions of the frog to study in detail the magnitude and time course of facilitation of the end‐plate potential (e.p.p.).2. When two shocks were applied to the motor nerve with an interval of 5 msec or less between them, the amplitude of the second e.p.p. was facilitated by approximately 100%. This facilitation decreased as the interval was lengthened.3. The facilitation could be separated into two components on the basis of the time course of its decay as the interval between the two shocks was increased. The first component decayed exponentially after the conditioning shock with a time constant of about 35 msec. The second became apparent 60‐80 msec after the conditioning shock, rose to a maximum of approximately 15% at about 120 msec and decayed thereafter with a time constant of the order of 250 msec.4. The growth of e.p.p. amplitude during short trains of repetitive stimulation at frequencies up to 100/sec and its subsequent decay could be predicted by assuming that the magnitude and time course of both components of facilitation were the same for every shock in the train and that these individual facilitatory effects summed linearly.
A quantitative study of cutaneous receptors and afferent fibres in the cat and rabbit
Authors: Brown A. G. , Iggo A. 
Published: December 2014

1. The discharge in myelinated afferent fibres innervating hairs in anaesthetized cats and rabbits, dissected from the saphenous nerve, was recorded during controlled movements of the hairs.2. Three types of rapidly adapting afferent unit were found and they innervated three kinds of hair follicle—down hair, guard hair and tylotrich.3. The down hair units had low thresholds (critical slopes) and some of the guard hairs had the highest thresholds and least sensitivity to displacement.4. There was a good fit to a power function for the relation between velocity of displacement of a hair and the frequency of discharge in the corresponding afferent fibre.5. It is concluded that the rapidly adapting hair follicle receptors can function as efficient exact movement detectors.6. Tylotrich follicles were often associated with touch corpuscles, but there was independent innervation of the rapidly adapting tylotrich follicle receptors and the slowly adapting touch corpuscle receptors.7. The conduction velocities of large populations of myelinated cutaneous axons innervating cutaneous mechanoreceptors were measured in cats and rabbits.
Phaeobacter sp. Strain Y4I Utilizes Two Separate Cell-to-Cell Communication Systems To Regulate Production of the Antimicrobial Indigoidine
Authors: Cude W. Nathan , Prevatte Carson W. , Hadden Mary K. , May Amanda L. , Smith Russell T. , Swain Caleb L. , Campagna Shawn R. , Buchan Alison 
Published: December 2014

ABSTRACT

The marine roseobacter
Phaeobacter
sp. strain Y4I synthesizes the blue antimicrobial secondary metabolite indigoidine when grown in a biofilm or on agar plates. Prior studies suggested that indigoidine production may be, in part, regulated by cell-to-cell communication systems.
Phaeobacter
sp. strain Y4I possesses two
luxR
and
luxI
homologous
N
-acyl-
l
-homoserine lactone (AHL)-mediated cell-to-cell communication systems, designated
pgaRI
and
phaRI
. We show here that Y4I produces two dominant AHLs, the novel monounsaturated
N
-(3-hydroxydodecenoyl)-
l
-homoserine lactone (3OHC
12:1
-HSL) and the relatively common
N
-octanoyl-
l
-homoserine lactone (C
8
-HSL), and provide evidence that they are synthesized by PhaI and PgaI, respectively. A Tn
5
insertional mutation in either genetic locus results in the abolishment (
pgaR
::Tn
5
) or reduction (
phaR
::Tn
5
) of pigment production. Motility defects and denser biofilms were also observed in these mutant backgrounds, suggesting an overlap in the functional roles of these systems. Production of the AHLs occurs at distinct points during growth on an agar surface and was determined by isotope dilution high-performance liquid chromatography–tandem mass spectrometry (ID-HPLC-MS/MS) analysis. Within 2 h of surface inoculation, only 3OHC
12:1
-HSL was detected in agar extracts. As surface-attached cells became established (at ∼10 h), the concentration of 3OHC
12:1
-HSL decreased, and the concentration of C
8
-HSL increased rapidly over 14 h. After longer (>24-h) establishment periods, the concentrations of the two AHLs increased to and stabilized at ∼15 nM and ∼600 nM for 3OHC
12:1
-HSL and C
8
-HSL, respectively. In contrast, the total amount of indigoidine increased steadily from undetectable to 642 μM by 48 h. Gene expression profiles of the AHL and indigoidine synthases (
pgaI
,
phaI
, and
igiD
) were consistent with their metabolite profiles. These data provide evidence that
pgaRI
and
phaRI
play overlapping roles in the regulation of indigoidine biosynthesis, and it is postulated that this allows
Phaeobacter
sp. strain Y4I to coordinate production of indigoidine with different growth-phase-dependent physiologies.
Organic Substances Interfere with Reverse Transcription-Quantitative PCR-Based Virus Detection in Water Samples
Authors: Hata Akihiko , Katayama Hiroyuki , Furumai Hiroaki 
Published: December 2014

ABSTRACT

Reverse transcription (RT)-PCR-based virus detection from water samples is occasionally hampered by organic substances that are coconcentrated during virus concentration procedures. To characterize these organic substances, samples containing commercially available humic acid, which is known to inhibit RT-PCR, and river water samples were subjected to adsorption-elution-based virus concentration using an electronegative membrane. In this study, the samples before, during, and after the concentration were analyzed in terms of organic properties and virus detection efficiencies. Two out of the three humic acid solutions resulted in RT-quantitative PCR (qPCR) inhibition that caused >3-log
10
-unit underestimation of spiked poliovirus. Over 60% of the organics contained in the two solutions were recovered in the concentrate, while over 60% of the organics in the uninhibited solution were lost during the concentration process. River water concentrates also caused inhibition of RT-qPCR. Organic concentrations in the river water samples increased by 2.3 to 3.9 times after the virus concentration procedure. The inhibitory samples contained organic fractions in the 10- to 100-kDa size range, which are suspected to be RT-PCR inhibitors. According to excitation-emission matrices, humic acid-like and protein-like fractions were also recovered from river water concentrates, but these fractions did not seem to affect virus detection. Our findings reveal that detailed organic analyses are effective in characterizing inhibitory substances.
Gut Symbionts from Distinct Hosts Exhibit Genotoxic Activity via Divergent Colibactin Biosynthesis Pathways
Authors: Engel Philipp , Vizcaino Maria I. , Crawford Jason M. 
Published: December 2014

ABSTRACT

Secondary metabolites produced by nonribosomal peptide synthetase (NRPS) or polyketide synthase (PKS) pathways are chemical mediators of microbial interactions in diverse environments. However, little is known about their distribution, evolution, and functional roles in bacterial symbionts associated with animals. A prominent example is colibactin, a largely unknown family of secondary metabolites produced by
Escherichia coli
via a hybrid NRPS-PKS biosynthetic pathway that inflicts DNA damage upon eukaryotic cells and contributes to colorectal cancer and tumor formation in the mammalian gut. Thus far, homologs of this pathway have only been found in closely related
Enterobacteriaceae
, while a divergent variant of this gene cluster was recently discovered in a marine alphaproteobacterial
Pseudovibrio
strain. Herein, we sequenced the genome of
Frischella perrara
PEB0191, a bacterial gut symbiont of honey bees and identified a homologous colibactin biosynthetic pathway related to those found in
Enterobacteriaceae
. We show that the colibactin genomic island (GI) has conserved gene synteny and biosynthetic module architecture across
F. perrara
,
Enterobacteriaceae
, and the
Pseudovibrio
strain. Comparative metabolomics analyses of
F. perrara
and
E. coli
further reveal that these two bacteria produce related colibactin pathway-dependent metabolites. Finally, we demonstrate that
F. perrara
, like
E. coli
, causes DNA damage in eukaryotic cells
in vitro
in a colibactin pathway-dependent manner. Together, these results support that divergent variants of the colibactin biosynthetic pathway are widely distributed among bacterial symbionts, producing related secondary metabolites and likely endowing its producer with functional capabilities important for diverse symbiotic associations.
Novel Reporter for Identification of Interference with Acyl Homoserine Lactone and Autoinducer-2 Quorum Sensing
Authors: Weiland-Bräuer Nancy , Pinnow Nicole , Schmitz Ruth A. 
Published: December 2014

ABSTRACT

Two reporter strains were established to identify novel biomolecules interfering with bacterial communication (quorum sensing [QS]). The basic design of these
Escherichia coli
-based systems comprises a gene encoding a lethal protein fused to promoters induced in the presence of QS signal molecules. Consequently, these
E. coli
strains are unable to grow in the presence of the respective QS signal molecules unless a nontoxic QS-interfering compound is present. The first reporter strain designed to detect autoinducer-2 (AI-2)-interfering activities (AI2-QQ.1) contained the
E. coli
ccdB
lethal gene under the control of the
E. coli
lsrA
promoter. The second reporter strain (AI1-QQ.1) contained the
Vibrio fischeri
luxI
promoter fused to the
ccdB
gene to detect interference with acyl-homoserine lactones. Bacteria isolated from the surfaces of several marine eukarya were screened for quorum-quenching (QQ) activities using the established reporter systems AI1-QQ.1 and AI2-QQ.1. Out of 34 isolates, two interfered with acylated homoserine lactone (AHL) signaling, five interfered with AI-2 QS signaling, and 10 were demonstrated to interfere with both signal molecules. Open reading frames (ORFs) conferring QQ activity were identified for three selected isolates (
Photobacterium
sp.,
Pseudoalteromonas
sp., and
Vibrio parahaemolyticus
). Evaluation of the respective heterologously expressed and purified QQ proteins confirmed their ability to interfere with the AHL and AI-2 signaling processes.
Phosphoryl Transfer from α-d-Glucose 1-Phosphate Catalyzed by Escherichia coli Sugar-Phosphate Phosphatases of Two Protein Superfamily Types
Authors: Wildberger Patricia , Pfeiffer Martin , Brecker Lothar , Rechberger Gerald N. , Birner-Gruenberger Ruth , Nidetzky Bernd 
Published: December 2014

ABSTRACTThe Cori ester α-d-glucose 1-phosphate (αGlc 1-P) is a high-energy intermediate of cellular carbohydrate metabolism. Its glycosidic phosphomonoester moiety primes αGlc 1-Pfor flexible exploitation in glucosyl and phosphoryl transfer reactions. Two structurally and mechanistically distinct sugar-phosphate phosphatases fromEscherichia coliwere characterized in this study for utilization of αGlc 1-Pas a phosphoryl donor substrate. Theagpgene encodes a periplasmic αGlc 1-Pphosphatase (Agp) belonging to the histidine acid phosphatase family. Had13 is from the haloacid dehydrogenase-like phosphatase family. Cytoplasmic expression of Agp (inE. coliOrigami B) gave a functional enzyme preparation (kcatfor phosphoryl transfer from αGlc 1-Pto water, 40 s−1) that was shown by mass spectrometry to exhibit no free cysteines and the native intramolecular disulfide bond between Cys189and Cys195. Enzymatic phosphoryl transfer from αGlc 1-Pto water in H218O solvent proceeded with complete18O label incorporation into the phosphate released, consistent with catalytic reaction through O-1–P, but not C-1–O, bond cleavage. Hydrolase activity of both enzymes was not restricted to a glycosidic phosphomonoester substrate, andd-glucose 6-phosphate was converted with akcatsimilar to that of αGlc 1-P. By examining phosphoryl transfer from αGlc 1-Pto an acceptor substrate other than water (d-fructose ord-glucose), we discovered that Agp exhibited pronounced synthetic activity, unlike Had13, which utilized αGlc 1-Pmainly for phosphoryl transfer to water. By applyingd-fructose in 10-fold molar excess over αGlc 1-P(20 mM), enzymatic conversion furnishedd-fructose 1-phosphate as the main product in a 55% overall yield. Agp is a promising biocatalyst for use in transphosphorylation from αGlc 1-P.