New germacrolide- and heliangolide-type sesquiterpene lactones from Melampodium linearilobum

Chemical analysis of Melampodium linearilobum yielded, besides coumarin, seven germacrolide-type sesquiterpene lactones, linearilobin A to G and two heliangolides, linearilobin H and I. All new sesquiterpene lactones are oxygenated at C-14 and C-15 and differ by the number and types of ester moieties at C-8, C-14 and C-15. M. linearilobum represents the first species within the genus known to produce germacrolides and heliangolides instead of the more common melampolides.     

Serine-inserting UAA suppression mediated by yeast tRNASer

The number of loci that give rise to serine-inserting UAA suppressors in the yeast Saccharomyces cerevisiae was determined by examining over 100 of the revertants that suppressed the two UAA markers his4-1176 and leu2-1: the his4-1176 marker is suppressed by serine-inserting but not by tyrosine- or leueine-inserting suppressors and the leu2-1 marker is suppressed by all UAA suppressors. The suppressors could be assigned to one or other of the four loci: SUP16 and SUP17. which were previously known to yield serine-inserting suppressors, and SUP19 and SUP22. The chromosomal map position of SUP19 suggested that it may be allelic to the previously reported suppressor SUP20, while the SUP22 suppressor has not been described. Representatives of all of the four suppressors were found to insert serine at the UAA site in iso-1-cytochrome c from suppressed cyc1-72 strains. The degree of suppression by the serine-inserting suppressors was SUP16 > SUP17 > SUP19 > SUP22. The efficiency of suppression of each of the four serine suppressors was increased by the chromosomal mutation sal and by the cytoplasmic determinant ψ⁺. Read-through of the synthetase gene of the RNA bacteriophage Qβ in a cell-free system was used to demonstrate that tRNA^Ser from SUP16, SUP17 and SUP19 strains can translate UAA codons. In contrast, tRNA^Ser or total tRNA from SUP22 strains had no suppressing activity. The results suggest that the three loci SUP16, SUP17 and SUP19 encode iso-accepting species of tRNA^Ser, and that the UAA suppression is mediated by mutationally altered tRNA molecules. The mechanism of SUP22 suppression remains unknown.     

Behavioral profile of ψ-MSH: Relationship with acta and β-endorphin action

In view of the close structural similarity of the pro-opiocortin fragment γ-MSH and of ACTH/MSH type peptides, the behavioral profile of γ-MSH was explored. Attention was first focussed on behavioral procedures in which ACTH/MSH related neuropeptides have been found effective. Using different procedures to test avoidance behavior, it was found that γ-MSH and ACTH-like neuropeptides had opposite effects. In this respect the activity of γ-MSH resembles that of opiate antagonists rather than that of β-endorphin. Accordingly, ACTH_1–24-induced excessive grooming which is blocked by opiate antagonists, is attenuated by γ-MSH. In addition, γ-MSH injected into the periaqueductal gray matter of the brainstem of opiate naive rats elicited symptoms reminiscent of those seen after opiate withdrawal. γ-MSH attenuated more or less several effects of intracerebroventricularly administered β-endorphin (e.g. antinociception, hypothermia, α-MSH release) and decreased acquisition of heroin self-administration. Although γ-MSH at rather high doses displaced naloxone from its specific binding sites in brain homogenates, it did not interfere with β-endorphin-induced effects on in vitro muscle preparations (guinea pig ileum, rat rectum). Interestingly, γ-MSH induced relaxation of the rat rectum in vitro. It is postulated that γ-MSH may attenuate β-endorphin-induced effects by acting via γ-MSH receptor sites (functional antagonism), although a pharmacological antagonism cannot be excluded as yet.     

A series of murine interleukin molecules which stimulate both murine and human lymphocytes: I. Production by Phytolacca americana (pokeweed) lectin 2 (Pa-2)-stimulated thymus and thymus-derived cells

Cell-free supernatant fluid, from cultures of Phytolacca americana (pokeweed) lectin 2 (Pa-2)-pulsed murine spleen or thymus cells, contains factors which induce cultured lymphocytes to differentiate into IgM-secreting cells (assayed by a reverse plaque technique) and to proliferate (measured by the incorporation of tritiated thymidine) without the addition of mitogen. The factors in this supernatant fluid responsible for these activities have been designated as lymphocyte stimulating factors (LSF). LSF showed no genetic restrictions related to the major histocompatability complex; LSF made in one strain of mice worked in other strains. Indeed, LSF is not restricted by species barriers; human peripheral blood mononuclear cells were also stimulated by murine LSF to proliferate and differentiate into immunoglobulin-secreting cells without further addition of antigen or mitogen. Maximum production of LSF was achieved within 12 hr of culture and was independent of cell division. In contrast to TRF, no further production of LSF was detectable after 24 hr of culture. Unlike T-cell growth factor, this material stimulated increased mitosis of thymic, T, and B lymphocytes without the addition of mitogen or antigen. LSF also stimulated polyclonal B-cell differentiation into IgM-secreting cells. Maximal numbers of immunoglobulin-secreting cells were generated when LSF was added at the initiation of the culture. Indeed, unlike TRF, LSF needed to be present only during the first 6 hr of culture to achieve maximum stimulation, and did not require the presence of antigen. The production of LSF by a T-cell population in the spleen was shown by two independent methods. Spleen cells treated with anti-Thy 1 plus complement failed to produce detectable levels of LSF. On the other hand, purified populations of surface immunoglobulin-negative spleen cells produced LSF. Furthermore, the subset of thymocytes responsible for LSF production was the small population (approximately 10%) of cells in the thymus, which are not agglutinated by peanut agglutinin.     

Cellular differentiation and morphogenesis in Cordylophora

Summary The interstitial cells ofCordylophora were destroyed by treating animals with 4,500 Roentgens of x-irradiation. Within 5–6 days after treatment no interstitial cells were detected in the treated animals and they were never seen in later stages. Some cell divisions were noted in the epidermal epithelio-muscular cells of the x-rayed animals which survived for four weeks. This was ample time to perform reaggregation-reconstitution experiments.Isolated, untreated coenosarc formed a mass from which hydranths and stolons arose. X-rayed coenosarc also formed these structures, although regenerative capacity was less than that of normal coenosarc. The number of stolons and hydranths produced decreased with length of time after irradiation. Both normal and x-rayed coenosarc masses exhibited a tendency to form a greater number of hydranths than stolons when the ratio of epidermis to gastrodermis was low and a greater number of stolons when the ratio of epidermis to gastrodermis was high. Masses prepared from the amounts of epidermis and gastrodermis normally found in intact animals produced intermediate numbers of hydranths and stolons.Isolated, untreated epidermis produced a gastrodermal layer from interstitial cells. They migrated to the inner surface of the epidermal epithelio-muscular cells, enlarged and differentiated into typical gastrodermal-digestive cells. These preparations formed hydranths and developed into colonies. X-irradiated epidermis did not form an inner gastrodermal layer but did secrete perisarc on the periphery. In some ases a second layer of epidermal epithelio-muscular cells was noted on the interior of the x-rayed masses. However, none of the irradiated epidermal masses produced hydranths or stolons or survived to form colonies.Gastrodermis was isolated from normal animals and although the cells rounded up into a spherical mass no morphogenesis occurred and the masses disintegrated within 12–24 hours. Irradiated gastrodermis behaved in the same manner.Normal epidermis was applied to x-rayed gastrodermis and from these preparations normal animals were produced.Normal, untreated gastrodermis combined with x-rayed epidermis yielded viable animals. Interstitial cells appeared to be produced by dedifferentiation of gland cells. The interstitial cells thus formed were able to divide and differentiate into cnidoblasts typical of epidermis.Thus, inCordylophora both epidermal and gastrodermal cells have the capacity to form cell types characteristic of the reciprocal layer.

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Zusammenfassung Die Interstitialzellen vonCordylophora wurden durch Röntgenbestrahlung (4,500 r) zerstört. 5–6 Tage nach der Bestrahlung waren keine Interstitialzellen mehr feststellbar, und auch in späteren Stadien traten nie mehr solche auf. Einige Zellteilungen wurden in den Epithel-Muskelzellen der bestrahlten Tiere beobachtet. Die Tiere blieben 4 Wochen am Leben, so daß Reaggregations- und Rekonstitutionsexperimente durchgeführt werden konnten.Isoliertes, unbehandeltes Coenosark bildete eine Zellmasse, aus der heraus Hydranthen und Stolonen wuchsen. Dieselben Strukturen entstanden aus bestrahltem Coenosark, wenn auch die Regenerationsfähigkeit des bestrahlten Cornosarks vermindert war. Die Zahl der gebildeten Hydranthen und Stolonen nahm mit zunehmender Zeit nach der Bestrahlung ab. Normale und auch bestrahlte Coenosark-Massen bildeten im allgemeinen mehr Hydranthen als Stolonen, wenn das Verhältnis Epidermis: Gastrodermis niedrig war, aber mehr Stolonen, wenn dag Verhältnis hoch war. Coenosark-Massen, die Epidermis und Gastrodermis im normalerweise vorhandenen Verhältnis enthielten, bildeten intermediäre Zahlen von Hydranten und Stolonen aus.Isolierte, unbehandelte Epidermis bildete aus Interstitialzellen eine Gastrodermisschicht. Dabei wanderten die Interstitialzellen auf die innere Oberfläche der epidermalen Epithelmuskelzellen, wurden größer, und bildeten typische gastrodermale Verdauungszellen. Solche Präparate bildeten Hydranthen und entwickelten sich in Kolonien. Bestrahlte Epidermis bildete keine Gastrodermis aus, sezernierte aber Perisark auf der Peripherie. In einigen Fällen wurde eine zweite Schicht von epidermalen Epithelmuskelzellen beobachtet im Innern der bestrahlten Massen. Me aber bildete eine bestrahlte Epidermismasse Hydranthen oder Stolonen, und nie Kolonien.Wenn Gastrodermis aus normalen Tieren isoliert wurde, rundeten sich die Zellen sich zu einer kugeligen Masse ab, aber es kam nie zu einer Morphogenese, und die Massen desintegrierten innerhalb 12–24 Std. Bestrahlte Gastrodermis verhielt sich ebenso.Wenn normale Epidermis auf bestrahlte Gastrodermis gepflanzt wurde, entstanden normale Tiere.Wenn normale Gastrodermis mit bestrahlter Epidermis kombiniert wurde, entstanden ebenfalls normale Tiere. Interstitialzellen entstanden durch Dedifferenzierung von Drüsenzellen. Die dabei gebildeten Interstitialzellen teilten sich und bildeten für Epidermis typische Cnidoblasten. Bei Cordylophora haben demzufolge epidermale, als auch gastrodermale Zellen die Fähigkeit, Zellen der reziproken Zellschicht auszubilden.

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The author wishes to acknowledge the financial aid received for this project from the National Institutes of Health, Bethesda, Md. through their University Biomedical Sciences Support Program.     

Monoribosomal attachment to messenger ribonucleic acid in sodium fluoride-treated rabbit reticulocytes (Short Communication)

Mild proteolysis with Pronase selectively dissociates ribosomes not attached to mRNA into subunits; ribosomes attached to mRNA remain intact. A portion of monoribosomes from reticulocytes incubated with NaF resisted proteolytic dissociation. Recovery of mRNA from monoribosomes of NaF-treated reticulocytes therefore may be explained by persistent attachment of some monoribosomes to mRNA.     

Abolition of Swarming of Proteus by p-Nitrophenyl Glycerin: General Properties

Para-nitrophenyl glycerin (PNPG) was shown to be an effective agent to abolish the swarming of Proteus mirabilis and Proteus vulgaris on predried solid culture media. The level required to abolish swarming varied with the strain of Proteus, the components of the medium, and also with the conditions of incubation. Generally 0.1 to 0.2 mM PNPG effectively abolished swarming for at least 24 h with aerobic incubation. Levels of PNPG that abolished swarming showed no effect upon the growth of the cells, little or no effect upon the motility characteristics of the organisms, and no effect upon the cellular morphology. PNPG was found to be freely water soluble, stable to autoclaving, and to retain biological activity for at least one month in prepared culture media stored under refrigeration.     

THE AFFINITY OF ONION CELL WALLS FOR CALCIUM IONS

Cell walls prepared from onion bulbs were found to exhibit an affinity for Ca⁺⁺. The adsorption of this ion was enhanced by the action of pectin methylesterase. It was confirmed that Ca⁺⁺ reacts with two COO“ groups and the corresponding affinity constant, K, was found to be: log K = 4.25. The action of pectin methylesterase had no effect upon K. The cell walls, as prepared, had 25 % of the total COO⁻ groups occupied by Ca⁺⁺, 14 % by Mg⁺⁺, and 39 % by H⁺. Treatment with acidified ethanol removed all of the metallic cations. K⁺ and Mg⁺⁺ could displace Ca⁺⁺ from the cell walls. At concentrations from 10⁻³ to 3 times 10⁻³ m it required from 4.9 to 13.2 moles of Mg⁺⁺ to displace one mole of Ca⁺⁺. For K⁺ it required 80 moles to displace 1 mole of Ca⁺⁺ at K⁺ concentrations from 0.65 × 10⁻² to 1.6 × 10⁻² M.     

Properties of Ribulose-1,5-Diphosphate Carboxylase (Carboxydismutase) From Chinese Cabbage and Photosynthetic Microorganisms

Ribulose-1,5-diphosphate carboxylase (carboxydismutase) was prepared from Chinese Cabbage [Brassica petsai (Parl)] and the K(m) values and molecular weight were determined. These parameters were found to be in good agreement with values reported for this enzyme from other higher plants. Investigation of carboxydismutase activity from the photosynthetic micro-organisms Chlamydomonas reinhardi (IU 89+), Plectonema boryanum (IU 594), and Chromatium strain D showed striking similarity to the higher plant enzyme, when the sedimentation coefficients were compared.