Augmentation of mouse natural killer cell activity by LS 2616, a new immunomodulator

The quinoline-3-carboxamide LS 2616 administered to mice in drinking water increased spontaneous cytotoxicity against YAC-1 cells in a dose-dependent manner. The enhancement of spontaneous cytotoxicity was found to be mediated by NK cells, as judged by their lack of adherence to nylon wool columns, relative resistance to treatment with antibodies to Thy-1.2 and complement, and almost total abrogation after depletion of asialo-GM1+ cells. Enhancement of NK activity was evident after 2 days of treatment, was maximal after 4 days, and remained elevated during the 14-day exposure period studied. NK activity returned to control levels 4 days after cessation of treatment. NK activity was significantly increased in spleen, peripheral blood, lymph nodes, and bone marrow of LS 2616-treated mice, while activity in peritoneal exudate cells and thymus remained low. LS 2616 was able to elevate NK activity in several mouse strains studied, including mice homozygous for the beige gene. Serum interferon levels were not increased during treatment with LS 2616. Combined injection of the interferon inducer Poly I:C and LS 2616 did not increase NK activity above that of animals injected with Poly I:C alone. However, Poly I:C, in contrast to LS 2616, increased NK activity in peritoneal exudate cells. Studies at the single cell level revealed that LS 2616 increased NK activity by increasing the number of lytically active cells via recruitment of new target-binding cells and not by increasing the lytic activity of pre-existing binders.     

Late enzymes of vindoline biosynthesis

From differentiated plants of Catharanthus roseus (L.) G. Don we have isolated a specific enzyme of the vindoline biosynthetic pathway catalysing the S-adenosylmethionine-dependent methylation of 11-O-demethyl-17-O-deacetyl-vindoline. The enzyme we named S-adenosyl-L-methionine : 11-O-demethyl-17-O-deacetylvindoline 11-O-methyltransferase. This transferase exhibits a high substrate specificity. Obviously the O-methylation at C-11 precedes the O-acetylation at the C-17 position during the biosynthesis of vindoline.A second enzyme was detected which hydrolyses the acetyl function of vindoline. The distribution of this acetylesterase in C. roseus plants demonstrates that the enzyme is not specifically associated with the vindoline distribution in the plant material. Most probably this enzyme plays no essential role in the biosynthesis of vindoline.     

Late enzymes of vindoline biosynthesis. Acetyl-CoA: 17-O-deacetylvindoline 17-O-acetyl-transferase

From differentiated plants of Catharanthus roseus (L.) G. Don, a specific enzyme was isolated and named acetyl-CoA : 17-O-deacetylvindoline 17-O-acetyltransferase, acting on the biosynthetic formation of the Aspidosperma type alkaloid vindoline.The enzyme shows a high selectivity towards different substrates. The acetyl-CoA-dependent transferase also catalyses the reverse reaction by hydrolysis of the 17-O-acetyl group of vindoline in the presence of free CoA. This enzyme is localized only in vindoline-containing plant parts, but was so far not detectable in cell suspension cultures of C. roseus. The enzyme allows the synthesis of labelled vindoline with high specific activity, applicable for instance as tracer for radioimmunoassays of vindoline.     

Impaired natural killer cell function in hemophiliacs with or without continuous substitution

In the present study, 28 hemophiliacs substituted continuously and 5 hemophiliacs who had received almost no blood products were investigated. Cells of OKT 3+, OKT 4+, and OKT 8+ subsets were counted. Percoll separated fractions of peripheral blood mononuclear cells were examined by morphological criteria and were tested for NK cell activity. We found that the NK cell activity of both groups of hemophiliacs was decreased on testing Ficoll separated cells or low density Percoll separated cells. Normal NK cell activity was found in medium density cells of hemophiliacs. Two possible explanations are discussed: first, the NK cell activity may be suppressed in hemophiliacs and secondly, there may be a block in maturation of NK cell activity. It is unlikely that chronic substitution by blood products counts for these alterations. The possible role of chronic infections is discussed.     

Statistical treatment of VAM infection data

Summary The amount of vesicular-arbuscular mycorrhizal (VAM) infection, when expressed as length of infected roots, is commonly quite variable among replicate pots within an experimental treatment. In this paper we show that frequency distributions of VAM infection parameters are often non-normal in form and may follow the negative binomial, a distribution commonly associated with aggregated organisms in nature. The lack of normality means that statistical procedures should either be non-parametric or should include data transformations.     

SALT REGULATION AND LEAF SENESCENCE IN AGING LEAVES OF JAUMEA CARNOSA (LESS.) GRAY (ASTERACEAE), A SALT MARSH SPECIES EXPOSED TO NaCl STRESS

The effects of increasing salt stress on leaf senescence and salt regulation were investigated in the halophyte Jaumea carnosa in hydroponic culture experiments. The plants were grown in Hoagland's nutrient solution plus additional NaCl salt (0, 300, 400, 500 mm NaCl). Decreases in nucleic acids, protein, and chlorophyll were used as indicators of leaf senescence. The results indicated no definitive pattern of acceleration in leaf senescence with increasing salt stress. Salt regulation was also unaffected as leaves aged under increasing NaCl concentrations. The results are consistent with those of previous studies of the halophyte which indicated that the species was very tolerant of high NaCl concentrations.     

Une oasis aquatique à faune relique dans la Plaine du Danube inférieur

Résumé Etude d'un complexe de sources, situé dans la Plaine du Danube Inférieur (= Plaine Roumaine ou Plains de Valachie), à 100 m d'alt. environ. La station se caractérise par un complexe de facteurs uniques dans ce coin de (Europe: abondance de l'eau phréatique froide sortant à jour sur une surface restreinte, protection efficace grâce à une saulaie compacte, variété des substrats et abondance des sources trophiques. Ces éléments rendent possible l'existence d'une faune relique, comprenant rotifères, tardigrades, coléoptères, trichoptères, hydracariens, etc., espèces ayant ici leur seule station de la Plaine Roumaine. Les espèces qu'on signale dans le travail sont soit formes de montagne, soit à aréal septentrional ou septentrional-occidental, soit, enfin, caractéristiques pour les tourbières d'altitude, souvent même pour les tourbières acides à Sphagnum. On considère la faune du complexe de Corbii Ciungi comme un rests remarquable de la faune aquatique ayant peuplé la Plaine Roumaine antérieurement à la mise en friche sauvage des forêts et à l'extension impétueuse de l'agriculture, phénomènes ayant radicalement transformé ce territoire.     

Differing activities of medullary respiratory neurons in eupnea and gasping

Our purpose was to compare further eupneic ventilatory activity with that of gasping. Decerebrate, paralyzed, and ventilated cats were used; the vagi were sectioned within the thorax caudal to the laryngeal branches. Activities of the phrenic nerve and medullary respiratory neurons were recorded. Antidromic invasion was used to define bulbospinal, laryngeal, or not antidromically activated units. The ventilatory pattern was reversibly altered to gasping by exposure to 1% carbon monoxide in air. In eupnea, activities of inspiratory neurons commenced at various times during inspiration, and for most the discharge frequency gradually increased. In gasping, the peak discharge frequency of inspiratory neurons was unaltered. However, all commenced activities at the start of the phrenic burst and reached peak discharge almost immediately. The discharge frequencies of all groups of expiratory neurons fell in gasping, with many neurons ceasing activity entirely. These data are consistent with the hypothesis that brain stem mechanisms controlling eupnea and gasping differ fundamentally.     

Expression of phenolic and tyrosyl ring iodothyronine deiodinases in Xenopus laevis oocytes is dependent on the tissue source of injected poly(A)+ RNA

The phenolic (5' position) and tyrosyl (5 position) ring deiodinases which catalyze the peripheral metabolism of thyroid hormones have proven difficult to purify and characterize biochemically. The present studies used Xenopus laevis oocytes as an in vivo translational assay system for detecting and quantitating mRNA for these enzymes. The injection of poly(A)+ RNA prepared from a human term placenta induced 5-deiodinase activity in oocytes. The expressed activity increased for up to 96 h after injection, was proportional to the amount of RNA injected, and manifested a Michaelis-Menten constant (Km) for T3 of 1.6 nM. In oocytes injected with poly(A)+ RNA prepared from rat liver, anterior pituitary gland, or brown adipose tissue, 5-deiodinase activity could not be demonstrated. The injection of poly(A)+ RNA from 15-day-old chick embryonic liver induced both 5'- and 5-deiodinase activity, with the 5'-deiodinase activity being sensitive to inhibition by 6-n-propyl-2-thiouracil. X. laevis oocytes can thus be induced to express either phenolic or tyrosyl ring deiodinase activity, or both, by the microinjection of poly(A)+ RNA prepared from selected tissues. These findings demonstrate that the types of deiodinase activity present in different organs represent tissue specific patterns of mRNA expression and strongly suggest that the enzymes responsible for types I and III deiodinase activity are encoded by different mRNAs.