Search

A laboratory technique for measuring the mobility of solutions on filter paper has been presented. Various exudates exhibited different mobilities on filter paper; this also applied to exudates of the same origin (pleura punctates). When diluted, the exudates exhibited increased mobility, indicating that the concentrations of various exudate components were of importance. The addition of cells (5 × 106 and 25 × 106 P 388 D cells/ml exudate) did not significantly change the mobility, whereas the mobility of protein fractions (human albumin and gamma globulin) was inversely related to the concentration of the solutions. These findings may he of significance to the reliability of present methods used for the quantitation of gingival exudation. [ABSTRACT FROM AUTHOR]

Earlier investigations have shown that potassium emerges from the yeast cell when the latter is shaken in a NaF solution. The potassium emergence seems to be caused by changed electrostatic conditions in the cell. Fluoride penetrates into the cell in the form of undissociated hydrogen fluoride. In the cell HF dissociates to a large extent into fluoride and hydrogen ions. The more acid the solution surrounding the cells is the more hydrogen ions can be carried into the cells in this way. In an earlier paper, calculations showed that the pH in the cell can hereby be decreased considerably. The changed pH in the cell will surely influence the activity of the enzymes. As a result, non diffusible anions could be transformed to diffusible ones. In this way potassium, originally electrostatically attracted to non-diffusible anions, is set free and can leave the cell. If the hydrogen ions were responsible for the potassium emergence, one would expect that other weak acids would also cause a potassium loss from the cell, that is, acids which are able to penetrate into the cell and which are not attacked by the enzymes of the cell. The aim of the present work was to examine the influence of a number of weak acids on the potassium management of the cell. The following weak acids were examined: formic, acetic, propionic. butyric. isobutyric, lactic, β-hydroxy-butyric, succinic, tartaric and citric acid. The experiments showed that the permeation ability alone of the weak acids is not decisive for a potassium emergence. It was considered if the dissociation constant of the weak acids was decisive for the potassium emergence. It appeared that only those acids, whose dissociation constant are about 10-4 cause a distinct potassium emergence. Acids with a dissociation constant about 10-5 seem already to be too weak. An increase in the concentration of these can, nevertheless, promote a potassium emergence. Independent of each other dr. H. Ussing and later professor E. J. Conway drew the author's attention to the possibility that potassium could perhaps leave the cell together with fluoride or formate ions as an ion pair. The size of the anions of the other acids, on the contrary, does not permit a permeation, and therefore causes no potassium emergence. Investigations on this subject will be presented in a coming paper. [ABSTRACT FROM AUTHOR]

Describes a device for preparing cell spreads. Steps involved in preparing a suitable cell suspension; Features of the apparatus used in the process; Instrument's use of centrifugal force to speed up the sedimentation of the cells.

It was shown previously that cell elongation in the roots of certain calcifuge grasses was inhibited by concentrations of bicarbonate and malate which promoted cell elongation in relate calcicole species. The present paper reports experiments in which [2-[sup14]C]-acetate was supplied to excised roots of a calcifuge Deschampsia flexuosa and a calcicole species Arrhenatherum elatius. Time course studies of the pattern of [sup14]C incorporation into the organic and amino acids of th roots indicates an active tricarboxylic acid cycle in both species but differing in that in Deschampsia the respiratory malate pool was more completely compartmented from other malate pool in the cells, whereas in Arrhenatherum a progressive mixing of the malate pools occurred Treatment of roots with a pulse of [2-[sup14]C]-acetate followed by exposure to 10 m-equiv./I HCO[sup-,sub3] for 3 hours resulted in a substantial modification in the pattern of [sup14[C incorporation from acetate in Deschampsia but not in Arrhenatherum. The results are discussed in relation to the differential effects of bicarbonate on root growth in the two species. [ABSTRACT FROM AUTHOR]

We have further characterized the polynucleotide ligase purified from cultures of the human heteroploid line EUE [Spadari, Ciarrocchi and Falaschi, Eur. J. Biochem. 22, 75 (1971)]. The 350-fold purified enzyme gives positive response with four different assays; the rates with the different substrates are different, but the variations are identical to those observed with the purified ligase induced by T4-phage. The enzyme can reconstitute the transforming activity of Bacillus subtilis DNA inactivated by pancreatic DNAase. The human cell enzyme is unable to use a hybrid substrate where an interrupted polydeoxynucleotide is annealed to a polyribonucleotide, whereas in the same conditions the T4 enzyme gives appreciable activity. The partial dependence of the purified enzyme on proteins present in a boiled crude extract, reported in the previous paper, seems due to an aspecific protective effect of the soluble proteins of cell extracts. The enzyme does not show any appreciable sequence specificity in the phosphodiester bond it can form. The purified enzyme can be fractionated into two molecular forms, one having a molecular weight of 190000, the other 95000; fresh extracts of EUE cells contain almost exclusively the high molecular-weight form; ageing of the extract or purification lead to the appearance of the second peak, without variations in the total activity. This could correspond to the conversion of a dimer structure into a monomer. The “dimer” has a pH optimum close to 8.1, whereas the “monomer” has its optimum at 7.5; this explains the bimodal pH curve previously described in the purified enzyme. [ABSTRACT FROM AUTHOR]

After administration of 14C-labelled 2-deoxy-D-glucose or ³H-labelled nucleosides to cells in tissue culture the following activated intermediates of the deoxysugar have been isolated and characterized: the 6-phosphate derivative, the 1-phosphate derivative, the 1,6-bisphosphate derivative. UDP-2-deoxy-D-glucose, GDP-2-deoxy-D-glucose and 2-deoxy-D-gluconic acid 6-phosphate. After extraction with acid and organic solvents. 2-deoxy-D-glucose could be recovered by acid hydrolysis from the cells. Labelled 2-deoxy-D-galactose was not found either bound to UDP or to the cells, indicating that no significant epimerisation of 2-deoxy-D-glucose at the UDP level occurred in these cells. [ABSTRACT FROM AUTHOR]

The results presented in this paper establish relationships between structural morphological and functional properties of cytoplasmic membrane vesicles isolated from an Escherichia coli unsaturated fatty acid auxotroph. The membranes were isolated from cells grown in the presence of either oleic, linoleic, linolenic or elaidic acids. High-angle X-ray diffraction studies show that the order-disorder transitions induced by temperature variations and associated with the paraffin chains of the lipids are a function of the fatty acid composition of the membranes. In some cases "cocrystallization" of various lipid species takes place within a single type of ordered domains. In other cases there is segregation of various lipid species into more than one distinct type of ordered domain. The various order-disorder transitions observed induce morphological changes in the hydrophobic core of the membranes which can be detected by freeze-etch electron microscopy. A random distribution of particles on the fracture faces is observed when the paraffin chains of the lipids are disordered. Upon ordering of the paraffin chains, particles are excluded from the ordered domains and as a consequence, smooth areas and areas with densely packed particles are observed. The ratio of the smooth surface to particulated surface is proportional to the amount of ordered paraffin chains present. Moreover, the size of the smooth domains is a function of the fatty acid composition of the membranes. Discontinuities in the rate of D-lactate-dependent proline uptake as a function of temperature correlate with the order-disorder transitions observed. The high energies of activation at low temperatures are attributed to decreased mobility of the carrier proteins upon aggregation. In contrast, phosphoenolpyruvate-dependent vectorial phosphorylation does not respond to the ordering of the paraffin chains. [ABSTRACT FROM AUTHOR]

This paper describes further confirmation of the successful application of the macrophage electrophoretic mobility (MEM) test to the detection of malignant disease. Results from fifty-one patients and eighteen controls are presented. The apparatus and technique used for the measurement of macrophage elctrophoretic mobility differed from those previously used in other investigations. Further information is presented on the nature and behaviour of macrophage slowing factor(s), and experiments concerning the possible use of cells other than guinea-pig macrophages as indicators of slowing factor production are also described. [ABSTRACT FROM AUTHOR]

This is a transmission and scanning electron microscopic study of stratum corneum in psoriasis vulgaris. In transmission electron microscopy numerous granules and vacuoles are observed. They display the same variations in size and shape and the same arrangement and distribution in the cytoplasm. They are also observed in the intercellular space. Both single and confluent granules and vacuoles occur. The granules contain either a rather opaque homogeneous or heterogeneous substance. Usually the vacuoles appear to be electron-optically empty, but many vacuoles containing substances similar to those in the granules are also found. The cell surfaces may be smooth, or they may show areas with numerous single excavations and excavations in rows, areas with distinct cytoplasmic protrusions and areas with a more regularly wavy shape. In scanning electron microscopy the cell surfaces may be predominantly smooth; they may display pores and areas with villi. Well-developed and low villi occur. In this paper it is suggested that the excavations along the cell surfaces are the result of an excretion of single and confluent granules and vacuoles into the intercellular space, and that the excavations may correspond to the poles and the distinct cytoplasmic protrusions to the well-developed villi. [ABSTRACT FROM AUTHOR]

This section presents technical abstracts on police science. In the article, Multiple Thickness Cell Assemblies--Application to Ultraviolet Spectrophotometry, D. D. Tunnicliff has devised multiple cell assemblies with cells of varying thicknesses to take advantage of varying cell length rather than concentrations in ultraviolet absorption spectrophotometry. The article, Plastic Vessel for pH Measurements of Small Samples, by Kenneth M. Richter, furnished dimensions and sketches of an adapter shaped to the Beckman standard electrodes for samples as small as 0.25 ml. A shoulder in one well of the adapter serves to prevent damage to the calomel electrode. The paper, Control of Fine Chemicals and Pharmaceuticals--Report for Analysts by W. B. Fortune, was presented at the Symposium on Analysis of Fine Chemicals and Pharmaceuticals at the American Chemical Society meeting in Atlantic City, New Jersey in September, 1956. The paper points out the increasingly difficult problems of identification and analysis of the many new drugs and chemicals being produced. Classical methods are inadequate, and new methods are hardly keeping pace with development and production of new products. Of particular interest to the Forensic Chemist or Criminalist are the comments about the need of applying confirmatory tests and not relying on single or inadequate identification tests.

A quantitative estimation of nitrogen in baker's yeast (suspensions of 1 g. yeast in 50 and 500 ml. distilled water) by the Kjeldahl method shows that 80 per cent of the total N are incorporated in the insoluble protein fraction and 20 per cent are found in the fraction of free amino acids. &frac910; of the latter are remaining within the cells, and &frac110; appears in the surrounding medium. After killing the cells the major part of free amino acids is released into the fluid, while the protein, however, remains unaltered. After a 12 hour's treatment of the cell suspensions with the fluorescing dye acridine-orange (10-1 g./l.), the protein fraction contains only 69 per cent (suspension 1: 50) and 30 per cent (suspension 1 : 500) of the total N. The fraction of free amino acids has increased to 31 and 70 per cent, respectively. The distribution of the amino acid N between the cells and the surrounding medium ist 28 % : 3 % (suspension 1 : 50) and 37 % : 33% (suspension 1 : 500). This indicates that the acridine-dye causes a breakdown of more than 60 per cent of the total protein and in increase of permeability, especially in the suspension I : 500 where each cell may accumulate greater amounts of the dye, in consequence of which the stained cells are killed. Protein breakdown is complete already after 1/2 hour, while exosmosis of the newly formed amino acids into the medium continues for many hours. Methyl green (10-4 g./l.) shows similar but weaker effects concerning the breakdown of proteins but does not increase the permeability. Combination of the two dyes shows additive effects concerning the break- down of proteins, while, on the other hand, methyl green protects the semi- permeability against the alteration by acridine. A qualitative study by means of paper chromatography on the amino acid content of living, killed, and stained cells shows no significant differences in the composition of the three fractions. Only the methionine content is altered: the protein of living and heat-killed yeast cells contains methionine, while the fraction of free amino acids is free of methionine. In acridine- treated cells; however, methionine disappears from the protein and is found in the fraction of free amino acids, thus indicating that there may exist several protein fractions in the cells which are differently affected by the dyes. It seems probable that, since acridine does not directly hydrolyze the proteins, it may act by blocking the protein turnover on the side of synthesis, while the normal breakdown continues, resulting in an accumulation of free amino acids. The first step of its action may consist in an adsorption on RNS-templates, as it is known for methyl green. Furthermore, acridine-orange, on account of `its toxicity, seems inadequate as an indicator for the discrimination between living and dead cells, as Strugger formerly has proposed. [ABSTRACT FROM AUTHOR]

The article discusses the study regarding the distribution of the Bacillariophyceae algae living on the sediments of some lakes of the English Lake District. The author mentions that the study measures the seasonal change in total diatom population and in certain genera by obtaining the summation of the counts of cell numbers of all species and other individual genera. The study confirms the reports of earlier papers that the benthic epipelic diatom community goes through distinct seasonal changes including low winter growth, high spring growth, and moderate autumn growth.

The paper briefly discusses the action of the ototoxic antibiotics on the human labyrinth, reviews their pharmacologic properties and summarizes their clinical indications. The ototoxic antibiotics are a group of drugs with remarkable pharmacological similarities. Most ototoxic antibiotics cause severe damage and destruction, primarily of the sensory cells of the inner ear. The available data indicate that these cells depend mainly on glucose for energy, and that ototoxic antibiotics damage the apparatus for glucose breakdown. A good understanding of the absorption, distribution and excretion of the drugs is essential for safe therapeutic application. Unfortunately, administration to patients with renal insufficiency is at present the main cause of iatrogenic deafness. The necessary precautions and the changing indications for the drugs are outlined.

Ficoll, a polymer of sucrose, and bovine serum albumin have been compared as media for preparation of density gradients for separation of lymphoid cells. Direct vapour pressure osmometer measurements demonstrated that Ficoll at high concentrations has a marked effect on the osmolarity of the medium in which it is dissolved. Albumin, prepared in the manner we have described in earlier papers of this series, has no effect, and density gradients prepared with this albumin do not contain gradients of osmolarity. Antibody forming calls give basically similar density distributions after separation in both media, apart from a slight overall shift to the dense end due to shrinkage in Ficoll. Heterogeneous, multiple peak distribution profiles, or relatively simple, homogeneous profiles may be obtained in both media, depending on the source of antibody-forming cells, the stage of differentiation of the population, and the degree of resolution of the gradient. Antibody-forming cell density heterogeneity is a property of the cell population, rather than an artifact of the separation system. Different animal species have a wide variation in the osmolarity of their sera. Albumin-gradients of osmolarity which were not iso-osmotic for the mouse caused a general shift in the density of mouse cell populations but no marked change in the relative distribution of cells. However, a change from iso-osmotic conditions did affect the ability of cells to reband on a second gradient. The use of gradients iso-osmotic for the particular species under study is recommended as a general procedure. [ABSTRACT FROM AUTHOR]

The present paper deals with some of the quantitative aspects of immunoglobulin formation in vitro. The results of this study show that isolated spleen cells synthesize about 1.25 μg IgG per 108 lymphoid cells during the first 6 hours of incubation. The initial rate of synthesis was not maintained throughout the 48 hours of incubation, but decreased markedly after 6 hours. Comparison of the intensity of the autoradiographic line with the amount of radioactive immunoglobulin in the precipitation line revealed that a very distinct line (gradation + + +) corresponds to about 0.0125 μg IgG. The limit of visibility (+) is reached at approximately 0.0002/μg radioactive IgG. [ABSTRACT FROM AUTHOR]

There is considerable evidence that electrolytes can penetrate the stratum corneum but there is no evidence on whether this penetration occurs through or between the corneum cells. In this paper evidence is presented which shows that the equilibrium water content of intact corneum immersed in electrolyte solutions depends upon the electrolyte concentration and obeys the laws of osmosis. Removal of lipid by solvent extraction destroys the osmotic properties. This evidence indicates that the osmotic properties of corneum depend upon the presence of a lipid-containing semipermeable membrane system. Other evidence indicates that this membrane system is the cell walls of the corneum cells themselves. If electrolytes cannot enter the corneum cells in these osmotic experiments it follows that they cannot enter the corneum cells during penetration through the stratum corneum and that they must therefore pass between the cells. [ABSTRACT FROM AUTHOR]

In a case of pyoderma gangrenosum without associated disease, clumping of cells was noted during routine leucocyte counts. It was probably due to a cryoglobulin in the patient's plasma. [ABSTRACT FROM AUTHOR]

The Mie theory of scattering is used to provide new information on how changes in particle volume, with no change in dry weight, should influence light scattering for various scattering angles and particle sizes. Many biological cells (e.g., algal cells, erythrocytes) and large subcellular structures (e.g., chloroplasts, mitochondria) in suspension undergo this type of reversible volume change, a change which is related to changes in the rates of cellular processes. A previous study examined the effects of such volume changes on total scattering. In this paper scattering at 10 degrees is found to follow total scattering closely, but scattering at 45 degrees , 90 degrees , 135 degrees , and 170 degrees behaves differently. Small volume changes can cause very large observable changes in large angle scattering if the sample particles are uniform in size; however, the natural particle size heterogeneity of most samples would mask this effect. For heterogeneous samples of most particle size ranges, particle shrink-age is found to increase large angle scattering.

1. Nuclei were prepared from frozen rat liver by a modification of the technique of Behrens, and were studied with regard to the content of free amino acids and nucleic acid. 2. Under rigorously controlled conditions, preparations of nuclei are obtained by the Behrens' method which form a gel in the presence of 5 or 10 per cent NaCl or of water plus a small amount of dilute alkali; whereas when conditions are less rigorously controlled, nuclei are obtained which form no such gel. The property of forming gels with alkali is probably characteristic of all cell nuclei which have not undergone autolysis. 3. Nuclei prepared by the Behrens' technique contain the enzymes arginase, catalase, and esterase in very appreciable concentrations. 4. The free amino acids of the isolated cell nuclei, as well as of other liver cell fractions, have been investigated using the technique of paper chromatography. 5. The chromatographic patterns of the free amino acids of whole cells, ground cytoplasm, and isolated cell nuclei were very similar or identical. A feature of interest in these chromatograms was the faintness or absence of the spots due to a number of the essential amino acids, as compared to the intensities of the spots due to glycine, alanine, and glutamic acid. Glutathione was present in the isolated nuclei as well as in the whole cells. 6. Chromatograms made from hydrolysates of nuclei showed high concentrations of the essential amino acids and were similar to chromatograms of hydrolysates of typical proteins.

An RNA ligase which is dependent on ATP and Mg2+ for maximal activity with 5'-32P-labeled poly(I) · poly(C) as substrate has been purified from Escherichia coli infected with phage T4. Ligase activity was demonstrated by the transfer of alkaline phosphatase sensitive 5'-32P termini into an alkaline phosphatase resistant form. The formation of phosphodiester bond was verified by hydrolysis of the reaction product and determining the transfer of 32p from the 5' position to the 2'(3') position by electrophoresis. An increase in sedimentation rate of poly(I) · poly(C) was also observed after reaction with RNA ligase. The enzyme also showed an ATP-PP1 exchange activity. The activity on the synthetic polyribonueleotides poly(A), poly(U), poly(A) · poly(U) and poly(I) · poly(C) was examined and an increased efficiency of the substrate was obtained when [5'-32P]poly(U) formed a complex with poly(A). [5'-32P]Poly(A) was a good substrate both with and without the complementary strand. With 5'-32P-labeled poly(I) · poly(C) as substrate RNA-ligase activity was detected in mammalian cells such as KB, HeLa and L-cells. The activity seems to increase after infection with encephalomyelocarditis (EMC) virus or poliovirus, but not aider infection with adenovirus type 2. The RNA ligase activity was confined to the cytoplasmic fraction of the cells. [ABSTRACT FROM AUTHOR]

HeLa cells, prelabeled with [³H[leucine for several generations, were pulse-labeled with [14c]-leucine. The 14C/³H ratio of the leucine in the medium, in the total amino acid pool and bound to transfer RNA was determined.It was found that the 14C/³H ratio of the leucyl-tRNA was identical with that of the extracellular medium while that of the amino acid pool was much lower. These results confirm previous reports that selection of amino acids for protein synthesis takes place before the amino acids are released intracellularly.Further, it is concluded that amino acids resulting from intracellular proteolysis are not reutilized directly under the conditions of our experiments.A possible model of intracellular amino acid pathways is discussed. [ABSTRACT FROM AUTHOR]

Lymph node cells from immunized rabbits were cultured with varying concentrations of antigen in preheated (56°, 30 minutes) autologous serum which had been collected before immunization. [3H]Thymidine was present for the last 6 hours of the 24-hour culture period and the radioactive labelling of acid-precipitable material was then determined. Changes in labelling due to variations of culture conditions were interpreted according to whether they were specific for control or antigen-treated cultures or non-specific. Cell concentration and serum concentration were predominantly non-specific variables influencing the labelling in control and antigen-treated cultures to a proportionate extent. However, at serum concentrations below 5 per cent labelling was disproportionately inhibited in antigen-treated cultures; there were further minor disproportionate inhibitions at higher serum concentrations. Labelling was inhibited by increasing the concentration of serum from 25 to 50 per cent, mainly due to a non-diffusible competitive inhibitory activity. Isotope-dilution analysis of the effects of serum on labelling over a wide range of serum concentrations indicated that the relationship was a complex one with at least three step-wise stimulations of the maximum labelling rate being produced by increasing the serum concentrations from 0 to 25 per cent. Labelling in antigentreated cultures containing post-immunization serum was less than labelling in cultures containing an equal volume of preimmunization serum, but labelling in control cultures was enhanced by post-immunization serum. These results are shown to be compatible with the proposals (i) that labelling in control cultures reflects the response of cells to low concentrations of endogenous antigens, and (ii) that preimmunization serum and post-immunization serum contain ‘natural’ and ‘acquired’ antibodies respectively, which normally buffer cell-borne receptor sites against reaction with endogenous and exogenous antigens. [ABSTRACT FROM AUTHOR]

Immediately after plucking the hairs from a mouse, with its skin in the resting phase of the hair growth cycle, both the labeling index and incorporation levels of ³HTdR are lowered. This depression persists until stimulated cells enter S, usually about 10 hours after plucking. These observations are confirmed using a combination of liquid scintillation and autoradiographic procedures. The dpm per punch of fixed skin, the labeling index of the basal layer, the grains per labeled basal layer cell and the proportion of labeled DNA are all reduced following plucking. The dpm per punch of fresh skin is concomitantly enlarged by plucking through an increase in the fixative-soluble pool, which may be due to the induction of vascular changes. Anesthesia apparently reduces slightly the incorporation levels into fixed unplucked skin. The vascular changes and anesthesia depression of incorporation cannot account for the depression in incorporation into fixed tissue which must be due to a more direct effect on DNA synthesis. The data could be explained on the basis of a reduction in the rate of synthesis combined with a block to entry into S or to progression through S. Using the autoradiographic and liquid scintillation techniques presented in this paper and published previously, a number of calculations were made regarding the proliferative population size in the epidermis and hair follicle. The cycle time for basal layer cells in unplucked skin is estimated to be 141 hours with an upper limit on the growth fraction of 0.92. [ABSTRACT FROM AUTHOR]

A procedure to isolate Escherichia coli mutants defective in ribonucleotide reduction is described. Using a parental strain defective in dCTP deaminase (paxA) and thus unable to synthesize dUMP from deoxycytidine nucleotides, we selected for cells unable to reduce UDP at a rate sufficient to satisfy the cell's need for thymidine nucleotides. This was accomplished by selecting for cells resistant to 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine (trimethoprim) in the presence of thymidine and screening these cells for a thymidine requirement that could be satisfied by deoxyuridine. Genetic analysis as well as enzyme assays of four such mutants chosen for study indicated that three had a defective thymidylate synthetase. One, LD195, which had normal thymidylate synthetase activity, was found to have a conditional deoxyuridine requirement that is only expressed under favourable growth conditions. Since restoration of a functional dCTP deaminase to derivatives of LD195 eliminated the deoxyuridine requirement, it was concluded that a combination of two mutations is responsible for the expression of this phenotype. Analysis of nucleotide pools of LD195 grown exponentially under permissive conditions revealed that both the dTMP and dTTP pools were 6-fold lower than in the parent indicating a deficiency in the production of a thymidine nucleotide precursor. Enzyme assays of crude extracts of LD195 indicated that this deficiency was due to a defective ribonucleosidediphosphate reductase. This conclusion is proven by an extensive enzymatic analysis presented in an accompanying paper. [ABSTRACT FROM AUTHOR]

In this paper the metabolism of amino sugars in the retina and in the pigment epithelial cells has Been studied. Extracts obtained from the retina and from the pigment epithelial cells are capable, in the presence of suitable cofactors, of converting [1.14C]glucosamine into UDP-N-acetylhexosamines. Chromatographic investigations with the use of Dowex resin column have permitted the identitication of the principal intermediaries of amino sugar metabolism: GlcNAc, GIcN-6-P, Glc-NAc-6-P, UDP-GlcNAc, UDP-GalNAc. Both the retina and the pigment epithelial cells are, further, capable of synthesizing those amounts of acetyl coenzyme A necessary for the formation of acetylated amino sugars. The metabolism of amino sugars in the retina would appear to be much more active than in the pigment epithelial cells; this would indicate that the greater part of the synthesis of mucopolysaccharides of the interstitial matrix takes place in the retina. In the course of this research, furthermore, the presence of three compounds has been ascertained, the identification of which is still in progress. [ABSTRACT FROM AUTHOR]

1. IAA destruction by root cells extracts following three distinct phases: a lag period, an activation phase and an equilibrium state. 2. The induction phase and the natural tangent, which is measured on the curve giving the IAA inactivation at the middle of the steady phase, permit a characterisation of the kinetics of the auxin catabolism. 3. Results of the experiments were then analysed in terms of enzyme biokinetics. 4. Relations between enzyme activity and enzyme concentration and substrate level are examined. As an oxidating agent H2O2 was used and the action of 2,4-dichlorophenol and gibberellic acid on the IAA inactivation was studied. 5. Analyses of pH and temperature effects were then made. 6. Finally, the importance of the various oxidation products resulting from the IAA destruction by the root tip extracts is discussed. [ABSTRACT FROM AUTHOR]

Cellular constituents(chloroplasts,sap and mitochondrial), separated from spinach leaves, were allowed to photosynthesize in the presence of radio active bicarbonate. The radiocarbon fixed by the chloroplasts was distributed mainly in the phosphate ester while the radiocarbon fixed by the sap was located mostly in the amino acids. the mitochondrial fraction fixed very little radioactive carbon dioxide. the rate of carbon dioxide fixation by the recombined mixture of sap and chloroplasts was greater than the sum of the separate components. the distribution pattern of the fixed radiocarbon of the recombined mixture, however, was qualitatively similar to a combination of the radiocarbon distribution of the separated chloroplasts and sap. The results of experiments carried out with these cellular constituents in the dark and in the presence of other substrates, labelled and unlabelled, are discussed. [ABSTRACT FROM AUTHOR]

The rapid assimilation of small quantities of ammonium, nitrite and nitrate-N by nitrogen-starved cells of Chlorella vulgaris is accompanied by high rates of gas exchange. When all the added nitrogen has been assimilated the rates of gas exchange return to the control values. The total volume of oxygen taken up during the period of nitrogen assimilation is about the same whichever nitrogen source is added but the rate is highest with ammonium-N and lowest with nitrate-N. On the other hand, the rate of carbon dioxide production is much the same whichever salt is added but the total volume of carbon dioxide produced is greatest when nitrate-N is added and least with ammonium-N. The quantities of oxygen absorbed and carbon dioxide produced agree with those expected if ammonium, nitrite and nitrate-N are all assimilated to the same final products and if carbohydrate is the carbon source in the cells. A high respiration rate also follows the addition of hydroxylamine but the gas exchange differs markedly from that expected if hydroxylamine were assimilated to the same products as the other nitrogen sources. [ABSTRACT FROM AUTHOR]

The influence of calcium on the properties of growing roots has been investigated. Calcium exerts two actions not found with potassium, iron, or boron. It increases the elasticity of the cells walls but is dispensable for the plasticity, which appears during the first phase of the cell elongation. Furthermore, it is necessary for the absorption of nitrate from external medium. The relation between calcium, protein synthesis, and auxin conditions have been cursorily discussed. The concept of plasticity of the wall versus elasticity has been examined, and it is suggested that these cannot always be applied in their strict sense to growing cells walls. The results corroborate the assumption that growth starts with an of the cells walls, which is independent of calcium, and is followed by a calcium-induced increase in the tensibility formation of the elastic components of the final wall by intussusception. [ABSTRACT FROM AUTHOR]

(1) The uptake of ammonia by 'nitrogen-starved' cells of Chlorella vulgaris was studied. Rapid assimilation of NH3-N into soluble organic nitrogenous compounds, principally amide and free amino-acid nitrogen, occurred. (2) In the presence of glucose, the soluble organic nitrogen finally returned to the original nitrogen-starved level, the assimilated NH3-N being incorporated into insoluble (protein) nitrogen. When no glucose was added, a large proportion of the assimilated nitrogen remained in the form of soluble organic compounds. (3) In both cases basic amino-acids represented a high percentage of the free amino-acids formed during ammonia assimilation, and even after 24 hrs, this percentage remained at a higher level than that found initially or in 'normal' cells. [ABSTRACT FROM AUTHOR]

Using the labeled CO2 trapping method, tryptophan hydroxylase activity was detected in the nucleated thrombocytes of the domestic fowl, but not in the mammalian platelets. This enzyme activity was around a 5-hydroxytryptophan production of 60 pmol×mg protein-1××h-1. Certain properties such as optimal pH (7.0), Km value (12 μM), requirement for cofactor (2-amino-4-hydroxy-6,7-dimethyl-5,6,7,8-tetrahydroptetidine) and inhibition by p-chlorophenylalanine indicated a close resemblance to tryptophan hydroxylase from brain tissue. Solubilization of this enzyme was to some extent successful by digitonin treatment of the cells. [ABSTRACT FROM AUTHOR]

This work shows that Pseudomonas fluorescens can synthesize two different inducible enzymes which possess β-ketoadipate: succinyl-CoA transferase activity. Transferase I is operative in the activation of free β-ketoadipic acid and is specifically induced in cells grown either with this acid, or with an aromatic precursor (benzoate) oxidized through the β-ketoadipate pathway. Transferase II is specifically induced m cells grown with saturated dicarboxylic adds of chain length C6 through C10, and its physiological function is that of an adipate :succinyl-CoA transferase; its ability to activate β-ketoadipic acid reflects non-specificity with regard to the CoA acceptor. [ABSTRACT FROM AUTHOR]

This article describes a technique for growing algae and flagellata cultures. There are five biological groups of microorganisms that may be grown in soil-water cultures. Equipment needed include hard glass, tubes, and larger containers such as glass cylinders or milk bottles. Organic substances supplying food materials are placed at the bottom of the vessel and covered with soil in a bid to prevent excessive putrefaction. An appropriate source of nitrogen and carbon compounds are casein, gelatine and similar substances. An advantage of this technique is that the organisms to be cultivated are chosen and separated from other forms at the outset. The cells to be used for inoculation should be passed through a sterile fluid to avoid contamination of the cultures with small algae.

Lymph node cells from Black Hooded (BH) rats immunized with Freund's complete adjuvant (CFA) are only poorly cytotoxic to target cells treated with target cell specific antibody. Normal spleen cells are highly cytotoxic to antibody coated target cells. When 106 lymph node cells, from rats immunized with Chang cells in CFA, are mixed with 107 spleen cells from unimmunized rats, the mixture is 8.6 times more cytotoxic than the sum of the cytotoxicities of the two lymphoid cell populations alone. Immune lymph node cells were no more cytotoxic in the presence of 5 per cent fresh guinea-pig serum than in the presence of heat inactivated guinea-pig serum. Immune spleen cells are prevented from damaging target cells by antagonists of protein synthesis such as Puromycin. Puromycin, however, does not alter the cytotoxic effect of either immune or nonimmune spleen cells on antibody coated target cells. From these experiments it is tentatively suggested that lymphoid cells from immunized animals mediate target cell damage by a reaction involving firstly immunologically specific responder cells which synthesise antibody and secondly non-specific effector cells which damage the antibody coated target cells. Evidence is presented which suggests that stable soluble factors may not be responsible for mediating target cell damage in this system. [ABSTRACT FROM AUTHOR]

A number of serum protein fractions were tested for their ability to suppress the immune response of rats injected with washed sheep cells. Significant depression of the immune response was produced by human serum proteins, and by bovine α-globulin fractions. The mechanism of this effect is at present not clear.

The chance seeing of a case of pili annulati provided an occasion for reviewing the salient features of this condition. Previous observation that the abnormal areas disappear after exposure to weak alkali on a glass microscopic slide was confirmed. Electron microscopic examination of hair samples from the young man and his elder sister suggests that there is a primary defect in the synthesis of the microfibril + matrix complex with possibly less of it being formed and thus creating a potential space. The process appears to be intracellular. The gas in the canals or spaces is likely to be air due to the fact that hair fibres are relatively permeable to most gases and liquids. [ABSTRACT FROM AUTHOR]

Investigations on the physiological function of both types of corpuscles are also wanting. Nearly all authors consider both of them as being tactile organs. Only two attempts can be mentioned to distinguish both kinds of corpuscles according to their physiological significance. The hypothesis are to be the present time devoid of any physiological proofs. In the present study, however, an anatoma-topographic base is brought forward for the opinion that both kinds of sense-corpuscles must be different in their function.

With the aid of a newly developed technique, a fibrillar component on the intracerebral vessels' wall is described. The origin and nature of these fibrils are discussed, reviewing the following possibilities: reticular, connective, glial, nervous and perivascular cell processes. [ABSTRACT FROM AUTHOR]

The article focuses on the physiological prerequisites required for the transition of autotrophic plants from water to terrestrial life. It is stated that the presence of cells with central vacuoles seems to be a prerequisite for invasion of land by plants. An inner aqueous medium is provided by their cell sap which determines the status of protoplasmic hydration. There is an reemphasis of the fact that the protoplasm is the site of all vital processes. Therefore, it is important to study the hydration of protoplasm.

In mechanically synchronized L-cells, the activity of thymidine kinase and dCMP deaminase shows a distinct periodicity during the mitotic cycle. The rise in enzyme activities occurs at about the onset of DNA synthesis, 6 hours after mitosis, and reaches a maximum 16 hours after mitosis. The maximum rate of thymidine incorporation into DNA is found at 10 hours. The increase of enzyme activity is 6 fold for thymidine kinase and 5 fold for dCMP deaminase. A rapid fall of both enzyme activities is observed between 18 and 22 hours, coinciding with the second synchronous mitosis. The increase in enzyme activities is probably due to de novo synthesis, as judged by the effect of actinomycin D and puromycin. It. is suggested that during the presynthetic phase of the cell cycle, messenger RNAs are synthesized for these enzymes. The enzymes in turn are required for the following DNA synthesis. [ABSTRACT FROM AUTHOR]

The article discusses the paper "The Problem of Cellular Naevi," by C. Voss. This paper concludes that the cellular naevus is a complex neurogenic malformation, of neuroectodermal and neuromesodermal origin. Dendritic chromatophores and dendritic cells belong to the same system.

Kinetic studies of the uptake of 63Ni by cultures of the diatom Phaeodactylum tricornutum Bohlin revealed that the uptake capacity of the cells depended strongly on their metabolic state. Phosphate-starved cells gave saturation-type uptake curves and had low nickel-binding capacity. This was increased markedly by the addition of phosphate to the cultures. When nickel ions were added before or together with the phosphate, the increase in nickel-binding capacity of phosphate-starved cells filed to appear more of less completely. Uptake of phosphate and formation of polyphosphate by the cells were not affected by the addition of nickel to the growth medium. The phosphate dependent synthesis of the principle involved in nickel binding was induced 15-20 h after the addition of phosphate to starved cells. Whether phosphate was directly or indirectly involved in this process could not be established. [ABSTRACT FROM AUTHOR]

Phenylalanine uptake in Chlorella fusca was measured, using the membrane filter technique. The cells were synchronized, and harvested at specific points of the life cycle. Experiments with autospores showed that the uptake followed saturation kinetics, with a Km= 5 μM. Vmax, was 0.1 nmol/min × 107 cells. The optimum temperature for the uptake was 40°C, and the activation energy was 1700 J/mol. The uptake showed a high specificity towards l‐phenylalanine; presence of the unlabelled stereoisomer did not inhibit the uptake. Uptake of l‐phenylalanine was inhibited in the presence of other analogues or other amino acids, but only if they were present in concentrations considerably higher than that of L‐phenylalanine. Variations in the ratio of Na4+ to K+ in the external solution during uptake experiments did not have any influence upon the uptake rate of l‐phenylalanine. The cells were able to take up the amino acid against a concentration gradient. At pool maximum the ratio between internal and external amino acid concentration was 1000/1. 2,4‐Dinitro‐phenol inhibited the uptake completely. Exchange between internal and external l‐phenylalanine could not be demonstrated. The Km value did not change during the life cycle of the cells. The uptake rate reached a maximum at the end of the light period, and fell to a minimum just before sporulation started. It is concluded that Chlorella fusca cells have a highly specific, active uptake system for l‐phenylalanine. The system is constitutive, independent on the K or Na concentration, and the mechanism of uptake does not change during the life cycle of the cells. [ABSTRACT FROM AUTHOR]