20-Hydroxyecdysone induced aggregation of Drosophila S3 cells is inhibited by antibodies to a hormone-dependent extracellular glycoprotein

Summary The S3 cell line of Drosophila exhibits numerous responses to the molting hormone 20-hydroxyecdysone, including mitotic arrest, cell aggregation and extensive changes in cell surface and extracellular glycoproteins. We have produced polyclonal antibodies to a major hormone induced extracellular glycoprotein to investigate the role of this molecule in cell aggregation. This glycoprotein with a molecular weight of 110 kD (P110) is found primarily in the culture medium of hormone-induced cells. Upon reduction, the electrophoretic mobility of P110 is decreased, indicating the presence of internal disulfide bonds. Results from treatment of medium proteins with a cross-linking reagent indicate that the molecule is part of a higher molecular weight oligomer (300–400 kD). Fab fragments of anti P110 effectively inhibit the reaggregation of hormone-treated S3 cells, while preimmune Fab fragments have no effect. On the basis of these results, we propose that the P110 glycoprotein complex in the medium of hormone-treated cells functions in hormone-dependent cell-cell adhesion.     

Social cues can play a role in timing onset of the breeding season of the ewe

Female Suffolk sheep were pinealectomized around the vernal equinox to eliminate the major environmental input to the reproductive system (photoperiod) and then either isolated from, or maintained with, pineal-intact gonad-intact sheep. The ewes were ovariectomized and treated with constant-release oestradiol implants and reproductive state was monitored by measuring serum LH concentrations. Pinealectomized ewes that were isolated from the normal flock showed a 2 1/2-month delay in onset of the seasonal rise in LH values compared with that of pineal-intact controls (18 November vs 5 September). On the other hand, pinealectomized ewes that were maintained with the flock showed an onset of the seasonal rise in LH that was not delayed. These results suggest a timekeeping role for social cues for timing onset of the breeding season in an animal that normally relies on photoperiodic signals for temporal regulation of the seasonal reproductive cycle.     

A programmable turbidistat for suspended particles in laboratory aquaria

A system for precise control of suspended particle concentrations in laboratory aquaria is described. It comprises an air-lift dosing system, a transmissometer to measure particle concentration, and a microcomputer which calculates the dose required to achieve a programmed turbidity.     

Observations on estuarine microfouling using the scanning electron microscope

Scanning electron microscopy was used to observe microbiological primary fouling of glass surfaces exposed in estuarine waters. Observations on clean glass, and glass treated with water-repellent coatings, showed that bacterial slimes adhered less strongly to the waterrepellent glass. An experiment using pure cultures of bacteria and latex particles showed that attached bacteria promoted the settlement of latex particles on the glass.     

Analysis by two-dimensional polyacrylamide gel electrophoresis of the in vivo phosphorylation of ribosomal proteins derived from free and membrane-bound polysomes

Analysis of in vivo phosphorylation of mouse liver ribosomal proteins was performed by two-dimensional polyacrylamide gel electrophoresis following 32P-injection. Our method is special and differs from other eukaryotic systems reported in that all proteins separated on the first dimension gel are completely solubilized, moving quantitatively to the second dimension gel. Only ribosomes from polysomes were used, ensuring analysis of ribosomes actively engaged in protein synthesis. We resolved sixty-five distinct proteins from ribosomes from membrane bound or free polysomes. In both cases radioautography revealed similar labeled patterns with one highly phosphorylated ribosomal protein and five marginally labeled spots.     

Evidence for common binding sites for ferrichrome compounds and bacteriophage phi 80 in the cell envelope of Escherichia coli.

Mutants ton A and ton B of Escherichia coli K12, known to be resistant to bacteriophage phi80, were found to be insensitive as well to albomycin, an analogue of the specific siderochrome ferrichrome. Ferrichrome at micromolar concentrations strongly inhibited plaque production by phi80. Preincubation with ferrichrome did not inactivate the phage. At a concentration at which ferrichrome allowed 90% inhibition of plaque formation, the chromium analogue of ferrichrome showed no detectable activity. Similarly, ethylenediaminetetraacetic acid, ferrichrome A, and certain siderochromes structurally distinct from ferrichrome, such as ferrioxamine B, schizokinen, citrate, and enterobactin, did not show detectable inhibitory activity. However, rhodotorulic acid showed moderate activity. A host range mutant of phi80, phi80h, was also inhibited by ferrichrome, as was a hybrid of phage lambda possessing the host range of phi80. However, phage lambdacI- and a hybrid of phi80 possessing the host range of lambda were not affected by ferrichrome. Finally, ferrichrome and chromic deferriferrichrome were shown to inhibit adsorption of phi80 to sensitive cells, ferrichrome giving 50% inhibition of adsorption at a minimal concentration of 8 nM. It is suggested that a component of the ferrichrome uptake system may reside in the outer membrane of E. coli K12 and may also function as a component of the receptor site for bacteriophage phi80, and that ferrichrome inhibition of the phage represents a competition for this common site.     

Characterization of Clostridia by Gas Chromatography: Differentiation of Species by Trimethylsilyl Derivatives of Whole-Cell Hydrolysates

Trimethylsilyl (TMS) derivatives prepared from whole-cell hydrolysates of 36 strains, representing 10 species of Clostridium were examined by gas-liquid chromatography (GLC). The TMS profile of each species contained a group of peaks which characterized the species. Variation among strains within a species was much lower than variation between species. Some of the closely related clostridia could be differentiated by comparing their TMS profiles. Strains of Clostridium botulinum were distinguished from C. sporogenes on the basis of the ratio of two GLC peaks which corresponded to arabinose and glucose. A peak with a retention time identical to that of mannose was present in all C. bifermentans strains but was absent in those of C. sordellii.     

A NEW BANGIOPHYCIDEAN ALGA FROM ALABAMA1

A new species of red algae, Boldia angustata sp. nov., was discovered near Tuscaloosa, Alabama, during the spring of 1968. It differs significantly from the only previously described species, Boldia erythrosiphon Herndon, in length and width of young and mature thalli, cell size, shape of nuclei in first-order cells, shape of intercalary filaments, morphology of filaments derived from monospores, ontogenetic development of erect plants, morphology of the basal system, and regularity of first-order cells.     

ISOLATION OF A GOLGI APPARATUS-RICH FRACTION FROM RAT LIVER : II. Enzymatic Characterization and Comparison with Other Cell Fractions

Enzymatic activities associated with Golgi apparatus-, endoplasmic reticulum-, plasma membrane-, mitochondria-, and microbody-rich cell fractions isolated from rat liver were determined and used as a basis for estimating fraction purity. Succinic dehydrogenase and cytochrome oxidase (mitochondria) activities were low in the Golgi apparatus-rich fraction. On the basis of glucose-6-phosphatase (endoplasmic reticulum) and 5'-nucleotidase (plasma membrane) activities, the Golgi apparatus-rich fraction obtained directly from sucrose gradients was estimated to contain no more than 10% endoplasmic reticulum- and 11% plasma membrane-derived material. Total protein contribution of endoplasmic reticulum, mitochondria, plasma membrane, microbodies (uric acid oxidase), and lysosomes (acid phosphatase) to the Golgi apparatus-rich fraction was estimated to be no more than 20–30% and decreased to less than 10% with further washing. The results show that purified Golgi apparatus fractions isolated routinely may exceed 80% Golgi apparatus-derived material. Nucleoside di- and triphosphatase activities were enriched 2–3-fold in the Golgi apparatus fraction relative to the total homogenate, and of a total of more than 25 enzyme-substrate combinations reported, only thiamine pyrophosphatase showed a significantly greater enrichment.