A simple rapid photometric estimation of the growth response of immobilized cells to fusaric acid and gamma radiation

A simple and rapid photometric method was developed in order to evaluate the growth responses of cells to various factors in vitro. Cells of Asparagus officinalis L. were mixed with autoclaved agar at 40°C and 90 l drops were dispensed into several Petri dishes. After the drops solidified, they were covered with a liquid growth medium and incubated on a gyratory shaker. Growth was measured every 2 or 3 days by two methods. In the first, the agar drop was placed under a stereomicroscope with substage illumination and the light passing through the embedded cells was measured by a light-meter. Growth, expressed by the increase in cell density, was inversely proportional to the intensity of transmitted light. In the second method, the agar drop was melted in a microwave oven and the packed cell volume was measured. The correlation between the two methods showed that the photometric method can be used to assess growth response of immobilized cells, during the first two weeks of culture. This method was used to evaluate growth responses to the toxin fusaric acid and to gamma radiation. The photometric method requires a small amount of inoculum, standard microscopic equipment and can be used to determine the effect of various factors on the growth of intact plant cells in vitro without disruption.Abbreviations FA fusaric acid - NAA naphthyl-1-acetic acid - CH casein hydrolysate - 2-i,P N⁶-(2-isopentyl) adenine - 2,4-D 2,4-dichloro-phenoxy acetic acid - PCV packed cell volume - gy grey     

Reduction of neutrophil influx diminishes lung injury and mortality following phosgene inhalation.

Phosgene inhalation causes a severe noncardiogenic pulmonary edema characterized by an influx of neutrophils into the lung. To study the role of neutrophils in lung injury and mortality after phosgene, we investigated the effects of leukocyte depletion with cyclophosphamide, inhibiting the generation of the chemotaxin leukotriene B4 with the 5-lipoxygenase inhibitor AA861 and impairing neutrophil migration with the microtubular poison colchicine. Cyclophosphamide, AA861, and colchicine injected before exposure significantly reduced percent neutrophils, protein, and thiobarbituric acid-reactive products in bronchoalveolar lavage fluid of rats exposed to phosgene (0.5 ppm X 60 min). Cyclophosphamide, AA861, and colchicine also significantly decreased mortality from phosgene (2.0 ppm X 90 min) in mice. Colchicine significantly reduced neutrophil influx, lung injury, and mortality even when given 30 min after phosgene exposure. We conclude that lung injury and mortality after phosgene exposure are associated with an influx of neutrophils into the lung. Prevention of neutrophil migration with colchicine may hold therapeutic potential in phosgene poisoning.     

Murine interleukin-4 displays potent anti-tumor activity in vivo

We have devised a sensitive means to assess the anti-tumor effect of cytokines that act via the mobilization of host-mediated defenses. This assay involves transfecting malignant cells to produce a specific cytokine (in this case, IL-4) and measuring the ability of transfectants to form tumors alone and when mixed with a variety of nontransfected tumor cells. In this way, we have identified a potent, non-cell autonomous, anti-tumor effect of IL-4 which is effective against a wide range of tumor cell types in vivo. The effect is reversed by anti-IL-4 antibody, correlates closely with levels of IL-4 production, and is evident in nu/nu mice. The anti-tumor effect seems to be mediated by an inflammatory infiltrate composed of eosinophils and macrophages.     

ONTOGENETIC AND HISTOCHEMICAL CHANGES IN THE VEGETATIVE SHOOT TIP OF CHENOPODIUM ALBUM

Gifford , Ernest M., Jr ., and Herbert B. Tepper . (U. California, Davis.) Ontogenetic and histochemical changes in the vegetative shoot tip of Chenopodium album. Amer. Jour. Bot. 49(8): 902–911. Illus. 1962.—A distinct central zone is present in apices of young, rapidly growing seedlings of Chenopodium album. This zone is clearly evident when the plane of section includes developing leaf buttresses and/or newly formed leaf primordia, but is not visible if the cells associated with these developing foliar organs are not in the plane of section. Cells in the central zone contain markedly lower concentrations of RNA than those of the peripheral zone. Differences in DNA, SH-protein, total protein, and histone concentration of cells in the apex parallel the zonal distribution of RNA, but are much less obvious. As the plant ages and the rate of leaf production decreases, the zonal distribution of the above-mentioned compounds becomes less and less obvious. Cells at sites of leaf initiation in older seedlings still have slightly higher RNA concentrations, but a central zone such as is visible in the young seedlings is no longer evident. The axial tunica cells do, however, contain noticeably lower DNA and histone concentrations than the remaining cells of the shoot apex. Changes occur in the size of nucleoli during ontogeny and the possible relationship between nucleolar size and modifying factors is discussed.     

Further studies on the oscillatory rate of hemoglobin synthesis in rabbit reticulocytes

The rate of hemoglobin synthesis in rabbit reticulocytes was found to be oscillatory after synchronization of the reticulocytes by precooling at 0 °C. Both α and β chains are synthesized in an oscillatory manner and in phase after synchronization. Experiments designed to study the effect of cooling on the polyribosomes showed a slowly proceeding shift in the polyribosome profile in favor of monosome formation. This shift proved to be reversible. After rapidly warming cooled reticulocytes, the original polyribosome profile was restored within 40–120 sec.     

Signs from a green desert: a preliminary examination of the archaeobotanical remains from a Byzantine dovecote near Shivta, Israel

This paper presents a preliminary examination of archaeobotanical material from pigeon dung samples obtained from Byzantine period destruction levels of a dovecote near the site of Shivta, Israel. Such pigeon dung was a valuable fertilizer in antiquity and would not have been abandoned without a reason. The plant remains from the dung provide direct evidence of pigeon diet and the local environment during the Byzantine period. Eleven plant taxa, represented by either seeds and/or plant parts (cereal chaff material), including five wild taxa, one legume, four fruit/nut taxa and several unidentified seed fragments were recovered. The most common seeds found were from weeds of the genus Thymelaea sp., and Ficus (fig). The finds indicate that the birds in the dovecote consumed a mixed diet of wild seeds including Thymelaea sp. and Fumaria sp. (fumitory), and small fruits of Vitis (grape), Ficus (fig), Olea (olive) and Phoenix (date). The sample analyzed also included Rumex (dock), Carex (sedge) and Androsace which may not have come from the feed. Apparently the pigeons were free to forage in the desert, the fallowed fields and refuse piles or/and were intentionally fed agricultural by-products including wild plants.     

Structural basis and mechanism of the inhibition of the type-3 copper protein tyrosinase from Streptomyces antibioticus by halide ions

The inhibition of the type-3 copper enzyme tyrosinase by halide ions was studied by kinetic and paramagnetic (1)H NMR methods. All halides are inhibitors in the conversion of l-3,4-dihydroxyphenylalanine (l-DOPA) with apparent inhibition constants that follow the order I(-) < F(-) < Cl(-) < Br(-) at pH 6.80. The results show that the inhibition arises from the interaction of halide with both the oxidized (affinity F(-) > Cl(-) > Br(-) > I(-)) and reduced (affinity I(-) > Br(-) > Cl(-) > F(-)) enzyme. The paramagnetic (1)H NMR of the oxidized enzyme complexed with the halides is consistent with a direct interaction of halide with the type-3 site and shows that the (Cu-His(3))(2) coordination occurs in all halide-bound species. It is surmised that halides bridge both of the copper ions in the active site. Fluoride and chloride are shown to bind only to the low pH form of oxidized tyrosinase, explaining the strong pH dependence of the inhibition by these ions. We further show that p-toluic acid and the bidentate transition state analogue, Kojic acid, displace chloride from the oxidized active site, whereas the monodentate substrate analogue, p-nitrophenol, forms a ternary complex with the enzyme and the chloride ion. On the basis of the experimental results, a model is formulated for the inhibitor action and for the reaction of diphenols with the oxidized enzyme.