Effect of deafferentation of the forelimb on the postnatal development of the synaptic plasticity in the hippocampus

The postnatal development of LTP in CA1 area of hippocampus was studied in hippocampal slices from 13-20-day-old intact rats, after unilateral resection of n. medianus on the 13th day, and sham-operated animals. In slices from the intact rats prepared on the 15th-16th-day of postnatal development, the LTP magnitude and duration were significantly larger than in adult animals. Partial deafferentation eliminated this overshoot. However, a less pronounced increase in synaptic plasticity was observed in operated animals on the 17th day. The LTP suppression in the experimental animals may be explained by a decrease in the NMDA receptor activity due to enhanced synaptic activity in the hippocampus. We think that the limited sensory inflow from the partially deafferented forelimb to the hippocampus via the entorhinal cortex may be compensated by activation of other inputs from specific or/and nonspecific pathways. In contrast, the LTP magnitude and duration were significantly increased in slices from the sham-operated rats. This increase may be explained by a decline of synaptic activation of the hippocampus under anesthesia.     

Cells of origin of the branches of the facial nerve: a retrograde HRP study in the rabbit

The origin of different branches of the facial nerve in the rabbit was determined by using retrograde transport of HRP. Either the proximal stump of specific nerves was exposed to HRP after transection, or an injection of the tracer was made into particular muscles innervated by a branch of the facial nerve. A clear somatotopic pattern was observed. Those branches which innervate the rostral facial musculature arise from cells located in the lateral and intermediate portions of the nuclear complex. Orbital musculature is supplied by neurons in the dorsal portion of the complex, with the more rostral orbital muscles receiving input from more laterally located cells while the caudal orbital region receives innervation from more medial regions of the dorsal facial nucleus. The rostral portion of the ear also receives innervation from cells located in the dorsomedial part of the nucleus, but the caudal aspect of the ear is supplied exclusively by cells located in medial regions. The cervical platysma, the platysma of the lower jaw, and the deep muscles (i.e., digastric and stylohyoid) receive input from cells topographically arranged in the middle and ventral portions of the nuclear complex. It is proposed that the topographic relationship between the facial nucleus and branches of the facial nerve reflects the embryological derivation of the facial muscles. Those muscles that develop from the embryonic sphincter colli profundus layer are innervated by lateral and dorsomedial portions of the nuclear complex. The muscles derived from the embryonic platysma layer, including the deep musculature, receive their input from mid to ventral regions of the nuclear complex.     

Genetic demography of Ukrainian urban populations in the 1990s: the ethnic composition of the migration flow in the Kharkov population

Marriage records were used to study the dynamics of the migration flow into the population of Kharkov in 1960-1993. The decrease in the migration rate was accompanied by changes in the ethnic composition of the migrants. The entire migration flow from the republics of the Baltic region consisted of Russians and Ukrainians. The increase in the migration flow from Transcaucasia was mainly accounted for by the migration activity of indigenous populations. Most migrants from Moldova, Central Asia, Kazakhstan, and Kyrgyzstan were also representatives of the respective indigenous populations. Malecot's coefficient of isolation by distance (b) decreased from 0.00123 to 0.0081.     

Potential importance of the subsoil for the P and Mg nutrition of wheat

A method is described which allowed the quantification of the potential uptake of P and Mg from the subsoil (>30cm) by spring wheat. Wheat was grown on an artificial topsoil (sand with no plant available P or Mg) which was superimposed on loess subsoils in N. Germany. The supply of P and Mg in the topsoil was varied by application of different quantities of P and Mg fertilizer. Uptake of P and Mg from the subsoil was calculated as the difference between total plant uptake (determined by plant analysis) and the quantities of P and Mg removed from the topsoil (determined by soil analysis). P uptake from the subsoil increased from 37% to 85% of total P uptake, with decreasing P supply in the topsoil. Calculations of potential supply by diffusion showed that, with a CAL-extractable P₂O₅ content in the subsoil of 9 mg 100g^-1, supply from the subsoil was only possible if the influence of root hairs was considered. The method also showed that the total demand for Mg by spring wheat could be satisfield from the supply of Mg from the subsoil of typical loess soils. Mg uptake from the subsoil decreased to 33% of total uptake with increasing Mg supply in the topsoil.     

Role of the fly in the transport of Yersinia enterocolitica

Yersinia enterocolitica were isolated from flies collected from a piggery and a kitchen of farm and from ham hung in a piggery. The cultures were identified as Y. enterocolitica biovar 4 and serovar 3 by biochemical and serological characteristics. From these results it is suggested that flies may play an important role in food contamination by Y. enterocolitica. In this study, the probable donors of Y. enterocolitica to the flies were swine.     

Phagocytosis of cells in the gastric surface epithelium of the rat

Summary Gastric surface epithelial cells (SEC) from fed rats, from rats fasted for 16 h and from mucosae exposed in an ex-vivo chamber to 16 mM aspirin for 5 min were examined by transmission electron microscopy. SEC have the capability to phagocytose adjacent epithelial cells and parietal cells. Phagocytosis is rare in mucosae from fasted animals but common in fed animals or after brief exposure to aspirin. Phagocytic capabilities are not restricted to the progenitor zone but exist throughout the surface epithelium. Phagocytosis may provide a mechanism for the removal of damaged or senescent cells from the surface epithelium.Suported by the Medical Research Council of Canada     

Characterization of the sulfated glycosaminoglycan on the surface and in the storage granules of rabbit platelets.

Rabbit platelets were labeled in vivo with 35S for characterization of platelet sulfated glycosaminoglycan. When rabbit platelets were aggregated by ADP, sulfated proteoglycan was lost from the platelet surface although no release of granule contents occurred. The sulfated proteoglycan contained in the granules of platelets pretreated with ADP was subsequently released by treatment with thrombin. The 35S-labeled proteoglycan from both sources was isolated by gel filtration and the glycosaminoglycan portion of the proteoglycan was characterized as chondroitin 4-sulfate by examining the products of digestion with hyaluronidase, chondroitinase AC and ABC, and chondro-4- and 6-sulfatases; by identification of the hexosamine as N-acetylgalactosamine; by determination of a 1 : 1 : 1 molar ratio of N-acetylgalactosamine, uronic acid and inorganic sulfate; and by cetylpyridinium chloride cellulose chromatography. In these studies, the use of 35S-labeled proteoglycan made possible detection and quantification of much smaller amounts of material than would be possible with unlabeled material. Chondroitin 4-sulfate was the only sulfated glycosaminoglycan identified in the proteoglycan lost from the platelet surface during ADP-induced aggregation and in the proteoglycan released from the granules when the platelets were exposed to thrombin.     

Studies on the biosynthesis of mitochondrial malate dehydrogenase and the location of its synthesis in the liver cell of the rat

A method is described for the isolation of mitochondrial malate dehydrogenase from either the whole tissue homogenate or from the microsomal fraction of rat liver. The procedure involves the treatment of the tissue extract with detergent followed by gel filtration and chromatography on Amberlite CG-50 and DEAE-cellulose. The resulting enzyme was homogeneous by the criterion of gel electrophoresis. Incubation of the microsomal fraction from rat liver under the usual conditions for protein synthesis in the presence of [(3)H]leucine resulted in the incorporation of (3)H into the mitochondrial malate dehydrogenase when purified as described. The results are taken to indicate that the mitochondrial enzyme is synthesized by the cytoplasmic ribosomes. Possible ways in which the cytoplasmic and mitochondrial forms of malate dehydrogenase reach their final locations in the cell are discussed.     

On the role of calcium in the mechanism of ADH action

With an increased influx of Ca2+ in the cytoplasm, the response of cells to ADH in the urinary bladder of the frog was lowered by addition of ionophore A23187 from the side of the basolateral cell membrane, but inhibited when it was added from the apical cell membrane. The removal of calcium by EGTA from the serosal surface was accompanied by a sharp increase of osmotic permeability not only to water, but also to inulin; while when calcium was removed from the mucosal surface of the urinary bladder, osmotic permeability was not changed. After being added to the Ringer solution from the outer surface of the apical cell membrane, the inhibitors of Ca2+ channels (verapamil, Ni2+, Mn2+, Co2+) decreased the effect of ADH. These data indicate that Ca2+ applied onto the outer surface of apical plasma membrane plays an important role in the action of ADH.     

Origin of glutamate dehydrogenase from the mucosa of the sheep rumen

Glutamate dehydrogenase [GDH] from the mucosa of sheep rumen was partly purified and characterized. In chromatography on DEAE cellulose, GDH activity separated into two fractions. Fraction I, isolated at a low NaCl gradient concentration, was not affected by Zn2+ or by the purine nucleotides GTP and AMP. The chromatographic behaviour of fraction II was the same as the parallel fraction isolated from the liver by the same technique. The activity of fraction II and the liver fraction was strongly inhibited by Zn2+ in 10(-6) to 3.10(-5) mol/1 concentration and by GTP in 10(-5) to 2.10(-5) mol/1 concentration. It was activated by AMP in 5.10(-6) to 6.10(-5) mol/1 concentration and by leucine in 3.10(-3) to 10(-2) mol/1 concentration. The coenzyme specificity of fraction I was greater for NADPH than for NADH. In the case of fraction II, like the fraction isolated from sleep liver, it was greater for NADH than for NADPH. It is concluded from the different effect of Zn2+ and of purine nucleotides on the enzyme activity of the fractions isolated from rumen mucosa that the mucosa of the sheep rumen contains two enzymes with GDH activity, one of which [probably adsorbed] is of bacterial origin and the other is a constitutive tissue enzyme of the rumen wall.     

Studies by electron-paramagnetic-resonance spectroscopy of the environment of the metal in the molybdenum cofactor of molybdenum-containing enzymes.

The molybdenum cofactor prepared by denaturing xanthine oxidase by heat treatment or other methods was partially purified by anaerobic gel filtration in the presence of sodium dithionite, with little loss of activity. A range of products with different elution volumes was obtained. This behaviour is apparently related to association of the molybdenum cofactor with various residual peptides. E.p.r. signals from molybdenum (V) in the active cofactor, present either in crude preparations or in purified fractions, may be generated in dimethyl sulphoxide solution by controlled oxidation carried out on the molybdenum cofactor alone or in the presence of added thiols. The g-values of the spectra suggest that in the oxidized cofactor molybdenum has one terminal oxygen ligand and four ligands from thiolate groups. It is proposed that two of these are from the organic part of the cofactor and two from cysteine residues in the protein or in residual peptides. A signal generated in high yield with little loss of cofactor activity in the presence of thiophenol has g parallel = 2.0258 and g = 1.9793. It is suggested that in this species two cysteine residues have been replaced by two thiophenol molecules. The possible usefulness of the thiophenol complex in further purification of the molybdenum cofactor is discussed.     

Verification of the protein in the outer membrane of Bdellovibrio bacteriovorus as the OmpF protein of its Escherichia coli prey.

Two research groups showed that several Bdellovibrio strains incorporated into their outer membranes intact OmpF porin proteins derived from their Escherichia coli prey. These results could not be reproduced by another group using Bdellovibrio bacteriovorus 109J. They showed that a major protein appearing in the Bdellovibrio Triton X-100-insoluble outer membrane was coded for by the bdellovibrios. We reconciled these results by examining the strain used by this group and by reviving a freeze-dried culture of strain 109J which had been stored for almost 9 years. B. bacteriovorus 109J failed to acquire substantial amounts of the OmpF protein from E. coli ML35, and a protein coded for by the bdellovibrios was expressed in its place. However, B. bacteriovorus 109J incorporated the OmpF protein from rough K-12 strains of E. coli, and the revived 9-year-old culture of B. bacteriovorus 109J incorporated more of the OmpF protein from the smooth E. coli ML35 than did its contemporary counterpart. The protein isolated from the outer membrane of the bdellovibrios was identified as the OmpF protein of E. coli by its protease peptide profile on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by Western blot analysis. This confirmed that bdellovibrios relocalize outer membrane proteins from their prey, but relocalization may be an unstable trait which can be influenced by the prey.     

Taste-responsive neurons in the nucleus of the solitary tract receive gustatory information from both sides of the tongue in the hamster

Taste receptors on the left and right sides of the anterior tongue are innervated by chorda tympani (CT) fibers, which carry taste information to the ipsilateral nucleus of the solitary tract (NST). Although the anterior tongue is essential for taste, patients with unilateral CT nerve damage often report no subjective change in their taste experience. The standing theory that explains the taste constancy is the "release of inhibition", which hypothesizes that within the NST there are inhibitory interactions between inputs from the CT and glossopharyngeal nerves and that the loss of taste information from the CT is compensated by a release of inhibition on the glossopharyngeal nerve input. However, the possibility of compensation by taste input from the other side of the tongue has never been investigated in rodents. We recorded from 95 taste-responsive neurons in the NST and examined their responsiveness to stimulation of the contralateral CT. Forty-six cells were activated, mostly with excitatory responses (42 cells). Activation of NST cells induced by contralateral CT stimulation was blocked by microinjection of lidocaine into the contralateral NST but was not affected by anesthetization of the contralateral parabrachial nuclei (PbN). In addition, the NST cells that were activated by contralateral CT stimulation showed reduced responsiveness to taste stimulation after microinjection of lidocaine into the contralateral NST. These results demonstrate that nearly half of the taste neurons in the NST receive gustatory information from both sides of the tongue. This "cross talk" between bilateral NST may also contribute to the "taste constancy".     

The complete amino acid sequence of the major alpha subunit of the lectin from the seeds of Dioclea grandiflora (Mart)

The complete amino acid sequence of the major alpha subunit of the lectin from seeds of Dioclea grandiflora was determined. The sequence was deduced from analysis of peptides derived from the native alpha subunit by digestion with trypsin, chymotrypsin, the Staphylococcus aureus V8 protease, and pepsin; and from larger peptides produced by digestion of the citraconylated protein with trypsin. The alpha subunit consists of a single polypeptide chain of 237 amino acids which differs from the sequence of concanavalin in 53 positions. Significant levels of heterogeneity were observed in five positions in the sequence.     

Differential lectin-mediated agglutinabilities of the embryonic and the first extraembryonic cell line of the early chick embryo

Summary The lectin-mediated agglutinability of cells dissociated from different areas of the gastrulating chick embryo was investigated. Differences in agglutinability were quantified by using a Coulter counter. Cells from the area pellucida (AP) and those from the endoderm of the area opaca (AOEn) are agglutinated by Concanavalin A (Con A), wheat germ agglutinin (WGA) andRicinus communis agglutinin (RCA). In cells from both areas the greatest agglutination response is obtained with RCA. Trypsinization of AOEn cells enhances their agglutinability with Con A, WGA and RCA. The lectin-induced agglutinability of cells from the area pellucida is similar in EDTA-dissociated and trypsinized cells.Cells from the AP are significantly more agglutinable with Con A than those of the AOEn regardless whether the former are obtained by trypsinization or dissociation with EDTA. The higher agglutinability of cells of the area pellucida with Con A, as well as the differential enhancement by trypsin of the agglutinability of AOEn cells with Con A, WGA, and RCA may reflect a difference in the cell surface glycoreceptors between the cells of the are pellucida (predominantly embryonic) and the first extraembryonic (AOEn) cell line. These cells have been shown to sort out from each other at the earliest stages of development.     

A Note on the Relevance of the Mesocotyl in the Systematics of the Gramineae

Seedlings of most of the Gramineae possess a mesocotyl, buta few tribes are characterized by its absence. Seedlings ofBromus resemble the Triticeae in having no mesocotyl and thisis further evidence for separating the Bromeae both from theFestuceae and from the Brachypodiae.     

Clearing-factor lipase in adipose tissue. Distinction of different states of the enzyme and the possible role of the fat cell in the maintenance of tissue activity

1. Incubation of intact epididymal adipose tissue from fed rats at 37 degrees in an albumin solution at pH7.4 in vitro results in rapid loss of clearing-factor lipase activity until a low activity, stable to prolonged incubation, is attained. The clearing-factor lipase activity of intact tissue from starved rats, which is initially much less than that of tissue from fed rats, is mainly stable to incubation at 37 degrees . 2. Much of the clearing-factor lipase activity of intact epididymal adipose tissue from fed rats is inactivated by collagenase. The enzyme activity of intact tissue from starved rats is not inactivated by collagenase. 3. The clearing-factor lipase activity of fat cells isolated from the epididymal adipose tissue of fed rats is stable to prolonged incubation at 37 degrees . It represents only a small proportion of the total activity of the intact tissue. In starved rats, the isolated fat cells contain a much higher proportion of the activity of the intact tissue. Their activity is also stable at 37 degrees . 4. Incubation of isolated fat cells in a serum-based medium leads to a progressive rise in clearing-factor lipase activity. Actinomycin increases the extent of this rise in activity. No rise in clearing-factor lipase activity occurs when stromal-vascular cells isolated from epididymal adipose tissue are incubated in the medium. 5. The findings indicate that less than 20% of the activity of intact adipose tissue from fed rats is retained when fat cells are isolated from the tissue by collagenase treatment. The activity that is lost could be that which normally functions in the uptake of triglyceride fatty acids by the tissue.     

Modification of the Composition and Structure of the Yeast Cell Wall by Culture in the Presence of Sulfur Amino Acids

Growth of Candida utilis and Saccharomyces cerevisiae in a medium supplemented with sulfur amino acids led to synthesis and accumulation of S-adenosylmethionine, accompanied by a reduction in the cell yield, an increased sensitivity of the cell wall to snail gut enzymes (Helix pomatia), as judged by spheroplast formation, and by a modification of the chemical composition of both the intact cells and their isolated walls. Walls of supplemented cultures of C. utilis were three times as sensitive to enzymatic digestion as walls from nonsupplemented cultures. In contrast to C. utilis, walls isolated from supplemented cultures of S. cerevisiae were digested slightly more rapidly by the purified snail extract than those from nonsupplemented cultures. Chemical modifications of the cell wall are interpreted to explain the ease with which cells from sulfur amino acid-supplemented cultures are converted to spheroplasts.     

Positive inotropic action of acetylcholine on the heart ventricles of the chick embryo

Acetylcholine increased twitch tension in the whole ventricle or in ventricular strips from 2-10-day chick embryos. The effect of acetylcholine was mediated by muscarinic receptors, since it was prevented by atropine, but not by tubocurarine or propranolol. Prostigmine significantly increased the sensitivity to acetylcholine in the strips from 7-day embryos, being almost ineffective in the strips from 3-day embryos. The decrease in acetylcholine sensitivity in the developing chick embryo is presumably associated with the increase in cholinesterase activity of the myocardial tissue.     

The effect of closing the ductus arteriosus on the pulmonary circulation of the fetal sheep

In the mammalian fetus the ductus arteriosus allows right ventricular output to be shunted away from the lungs to the systemic circulation. This study was performed to determine how closing the ductus arteriosus of the fetal sheep would affect the pulmonary circulation. Under halothane anaesthesia 6 near-term fetal sheep were delivered with the umbilical circulation intact. Catheters were placed in the right atrium, the pulmonary artery, and the aorta. Pulmonary blood flow was measured by injecting radioactive microspheres into the right atrium while a reference sample was withdrawn from the pulmonary artery. Closing the ductus arteriosus increased pulmonary arterial pressure by 22% from 51 +/- 3 to 62 +/- 3 mmHg and increased pulmonary blood flow disproportionately by 198% from 232 +/- 74 to 692 +/- 80 ml/min per 100g. Thus, pulmonary vascular resistance decreased by 75% from 0.451 +/- 0.65 to 0.095 +/- 0.010 mmHg 100g min/ml. These findings extend the observation that pressure and flow in the pulmonary circulation of the air-breathing lung do not have a linear relationship passing through the origin to include a striking example in the fluid-filled lung of the intact fetus. They also raise questions about the nature of the elevated vascular resistance in the fetal lung.