The establishment of cell lines from imaginal wing discs of Spodoptera frugiperda and Plodia interpunctella

Continuous cell cultures were established from imaginal wing discs of 2 Lepidoptera, Spodoptera frugiperda and Plodia interpunctella. The S. frugiperda line (IAL-SFD1) grows as multicellular vesicles and responds morphologically and biochemically to the insect hormone, 20-hydroxyecdysone. In contrast, the P. interpunctella cells (IAL-PID2) grow as attached monolayers of small spindle-shaped cells and do not appear to have specific responses to 20-hydroxyecdysone, although growth rates are slowed in these cells upon exposure to the hormone.     

Action of two juvenile hormone antagonists on lepidopteran epidermis

The juvenile hormone antagonist ETB (ethyl-4-2(t-butylcarbonyloxy)-butoxybenzoate) caused formation of precocious larval-pupal intermediates after the 4th (penultimate)-larval instar of the tobacco hornworm, Manduca sexta, when 50 μg were applied to any 3rd stage larvae or to 4th stage larvae within 12 hr after ecdysis. This dose was most effective within 12 hr after ecdysis to the 3rd stage. In the black mutant larval assay for juvenile hormone, ETB had activity, 0.75 μg per larva giving half-maximal score. In vitro ETB acted as a juvenile hormone to prevent the ecdysteroid-induced change in commitment at concentrations above 0.1 μg/ml with an ED₅₀ at 2.8 μg/ml and as a partial juvenile hormone antagonist to 0.1 μg/ml juvenile hormone I at concentrations between 10^?3 and 10^?2 μg/ml. By contrast, EMD (ethyl-E-3-methyl-2-dodecenoate) had little juvenile hormone-like activity in vitro up to its limits of solubility (100 μg/ml) and exhibited sporadic partial juvenile hormone antagonistic activity in vitro at concentrations between 1 and 100 μg/ml. Since these concentrations were 10–1000 times that of juvenile hormone I in the medium, EMD apparently is not an efficient competitor.     

Characterization of a glycoprotein isolated from a continuous tumor-cell line of human lung carcinoma

A glycoprotein with a molecular weight of 62 000 has been isolated from a tumor-cell line, A549, and purified to homogeneity by gel chromatography. The glycoprotein contained sialic acid, galactose, mannose, N-acetylglucosamine and a relatively high amount of glutamic acid and proline. The data indicated that the overall composition of this glycoprotein was different from that of the glycoprotein of Mr 62 000 isolated from lung lavage of patients with alveolar proteinosis. The glycoprotein did not react with the antiserum raised against glycoprotein of Mr 62 000 isolated from lung lavage of patients with alveolar proteinosis.     

Rapid Test for Urease and Phenylalanine Deaminase Production

A rapid urea-phenylalanine medium was effective for the identification of Proteus and, with one exception, Providencia. Most Klebsiella and a few Enterobacter were urease-positive with this method.     

Antibiotic Susceptibilities of Serratia marcescens and Enterobacter liquefaciens

Production of 5'-nucleotides by Serratia marcescens and Enterobacter liquefaciens correlates with deoxyribonuclease production, indicating the close relationship between these two organisms. To determine further relationships, susceptibilities of 279 strains of the tribe Klebsielleae were determined by the high-potency disc method, agar-dilution method, or both, by using 14 antibiotics. Ninety-seven per cent of S. marcescens (201 of 207 strains) and 100% of E. liquefaciens (17 strains) had minimum inhibitory concentration (MIC) of 100 mug/ml or greater with colistin and polymyxin B. With these two antibiotics, 93% of other Enterobacter species (28 strains) had MIC values of less than 1.6 mug/ml, and 100% of Klebsiella (27 strains) had MIC values less than 1.6 mug/ml. Consistent patterns were not noted with the other antibiotics tested, but the results with colistin and polymyxin B provide additional evidence of the close relationship of S. marcescens and E. liquefaciens.     

DIVISION IN THE DINOFLAGELLATE GYRODINIUM COHNII (SCHILLER) : A New Type of Nuclear Reproduction

Dinoflagellates are of interest because their chromosomes resemble the nucleoplasm of prokaryotes both chemically and ultrastructurally. We have studied nuclear division in the dinoflagellate Gyrodinium cohnii (Schiller), using cells obtained from cultures undergoing phasic growth. Electron micrographs of serial sections were used to prepare three-dimensional reconstructions of nuclei and chromosomes at various stages of nuclear division. During division, a complex process of invagination of the intact nuclear envelope takes place at one side of the nucleus and results in the formation of parallel cylindrical cytoplasmic channels through the nucleus. These invaginations contain bundles of microtubules, and each of the bundles comes to lie in the cytoplasm of a cylindrical channel. Nuclear constriction occurs perpendicular to these channels without displacement of the microtubules. There are no associations between chromosomes and the cytoplasmic microtubules. In dividing cells most chromosomes become V-shaped, and the apices of the V's make contact with the membrane surrounding cytoplasmic channels. It is proposed that the membrane surrounding cytoplasmic channels in the dividing nucleus may be involved in the separation of daughter chromosomes. Thus, dinoflagellates may resemble prokaryotes in the manner of genophore separation as well as in genophore chemistry and ultrastructure.     

NOTES ON THE ECOLOGY OF A SPECIES OF ZYGOGONIUM (KÜTZ.) IN YELLOWSTONE NATIONAL PARK

A species of Zygogonium forms extensive dark purple mats in Yellowstone National Park in acidic habitats adjacent to thermal areas. These mats range up to 6 cm in thickness and up to 3000 m² in areal extent. Temperatures in the mats varied from 20–31 C and pH varied from 2.4–3.1. These mats form on soil in areas where a moist surface is created by the presence of small acidic springs or seeps. The effect of light, temperature, and pH on photosynthesis was studied in the field by use of ¹⁴CO₂. Photosynthesis increased in rate up to full sunlight; light inhibition was not observed. Temperature optimum for photo-synthesis was 25 C. A broad pH optimum was found between 1.0 and 5.0. The Zygogonium mats have a high water holding capacity and create a moist habitat in which Euglena and Chlamydomonas develop. The mats also serve as repositories for the eggs of the brine fly Ephydra bruesi and both larvae and adults of this fly probably consume Zygogonium filaments as their main food source.