Galactose Transport in Saccharomyces cerevisiae III. Characteristics of Galactose Uptake in Transferaseless Cells: Evidence Against Transport-Associated Phosphorylation

The characteristics of the inducible galactose transport system in bakers' yeast were studied in uridine diphosphate, galactose-1-phosphate uridylyl-transferaseless cells. Transferaseless cells transport galactose at the same initial rate as wild-type cells and accumulate a mixture of free galactose and galactose-1-phosphate. The addition of ¹⁴C-labeled galactose to cells preloaded with unlabeled galactose and galactose-1-phosphate results in a higher rate of labeling of the free-sugar pool than of the galactose-1-phosphate pool. These results support other evidence that galactose uptake in bakers' yeast is a carrier-mediated, facilitated diffusion and that phosphorylation is an intracellular event after uptake of the free sugar.     

Spongelike alginate nanoparticles as a new potential system for the delivery of antisense oligonucleotides.

The aim of this study was to design a new antisense oligonucleotide (ON) carrier system based on alginate nanoparticles and to investigate its ability to protect ON from degradation in the presence of serum. Pharmacokinetics and tissue distribution of ON-loaded nanoparticles have been determined after intravenous administration. An original and dynamic process for ON loading into polymeric nanoparticles has been applied. It is based on the diffusion of ON or ON/polylysine complex into the nanoparticle or the alginate gel, respectively. Indeed, the single coincubation of ON with nanoparticles led, within a few days, to an extremely efficient association. The diffusion kinetic of ON was shown to be dependent on several parameters, incubation temperature, ON concentration, presence or absence of polylysine, polylysine molecular weight, and nanoparticle preparation procedure. This new alginate-based system was found to be able to protect [33P]-radiolabeled ON from degradation in bovine serum medium and to modify their biodistribution, as an important accumulation of radioactivity was observed in the lungs, in the liver, and in the spleen after intravenous administration into mice. ON may be associated efficiently with calcium alginate in a colloidal state. Such nanosponges are promising carriers for specific delivery of ON to lungs, liver, and spleen.     

Ultrastructure of the epithelial cells of the ventral prostate from the hopping mouse Notomys alexis

The large ventral prostate of the hopping mouse has abundant secretory units whose epithelial cells vary in height and which often have nuclei in the apical region of the cell. TEM observations indicated two epithelial cell types in which some unusual features occurred. Type A cells had granular endoplasmetic reticulum (GER) whose membranes often formed intracytoplasmic confronting cisternae. Type B cells had more fragmented and vesiculated GER with sparse ribosomes and less frequently also intracytoplasmic confronting confronting cisternae. In the latter cells, two types of granules were found, one of which was derived from the Golgi and the other possibly directly from the GER. Type A cells only had one type of granule present. A highly convoluted membrane was also found at the basal region in many of the cells. The significance of these unusual ultrastructural features has yet to be ascertained.     

Plantlet regeneration via somatic embryogenesis in anther callus of Vitis latifolia L.

Anthers of Vitis latifolia L. (wild grape) cultured on Nitsch and Nitsch medium supplemented with 20 μM 2,4-D and 9 μM BAP produced callus after 4–6 weeks. Subculture of callus onto Nitsch and Nitsch medium containing 10 μM NAA produced somatic embryos within 6 weeks. On growth regulator-free Nitsch and Nitsch basal medium somatic embryos converted to plantlets in 6–8 weeks. One gram of callus produced more than 400 somatic embryos with 13.7% being converted to complete plantlets, which were subsequently established in soil. Regenerated plants were found to have mixoploid populations of cells, 2n = 38 and n = 19. Received: 23 May 1998 / Revision received: 21 September 1998 / Accepted: 10 October 1998     

Iron stress in open-ocean cyanobacteria (Synechococcus, Trichodesmium, and Crocosphaera spp.): identification of the IdiA protein.

Cyanobacteria are prominent constituents of the marine biosphere that account for a significant percentage of oceanic primary productivity. In an effort to resolve how open-ocean cyanobacteria persist in regions where the Fe concentration is thought to be limiting their productivity, we performed a number of Fe stress experiments on axenic cultures of marine Synechococcus spp., Crocosphaera sp., and Trichodesmium sp. Through this work, we determined that all of these marine cyanobacteria mount adaptive responses to Fe stress, which resulted in the induction and/or repression of several proteins. We have identified one of the Fe stress-induced proteins as an IdiA homologue. Genomic observations and laboratory data presented herein from open-ocean Synechococcus spp. are consistent with IdiA having a role in cellular Fe scavenging. Our data indicate that IdiA may make an excellent marker for Fe stress in open-ocean cyanobacterial field populations. By determining how these microorganisms respond to Fe stress, we will gain insight into how and when this important trace element can limit their growth in situ. This knowledge will greatly increase our understanding of how marine Fe cycling impacts oceanic processes, such as carbon and nitrogen fixation.     

Lymphocyte-mediated modulation of the functional activity of macrophages by individual antigenic complexes of Trichophyton cells

The capacity of antigenic complexes of the causative agent of zoo- and anthroponotic trichophytosis for inducing the factors, that modify the functional activity of macrophages, in mice and in spleen cell cultures has been studied. These complexes are capable of inducing the T-lymphocyte-mediated suppression and of stimulating the fungicidal activity (and oxygen-dependent metabolism) of phagocytes. The production of fungicidal activity suppressing lymphokines is linked with the presence of alkali-insoluble components of fungal cell walls and cytoplasmic antigens (the latter appear only in interactions of antigens with the lymphocytes of immunized animals) in the above-mentioned complexes.     

Routine smoking cessation intervention in health care systems.

Everyone agrees that insurance for long-term care is inadequate in the United States. Disagreement exists, however, on whether such insurance should be provided through the private or public sector. Private insurance generally uses the experience-rating principle that persons with higher risk of illness are charged higher premiums. For private insurance for long-term care, this principle creates a dilemma. Most policies will be purchased by the elderly; yet, because the elderly have a high risk of needing long-term care, only about 20% of them can afford the cost of premiums. A public-private partnership by which the government partially subsidizes private long-term-care insurance is unlikely to resolve this dilemma. Only a social insurance program for long-term care can provide universal, affordable, and equitable coverage.