The migration stage of Dictyostelium: Behavior without muscles or nerves

Abstract Glycoproteins are providing to be quite common in prokaryotes. Those is S-layers are the best understood in terms of structure. Numerous eubacteria produce non-S-layer glycoproteins about which relatively little is known. The glycans on such protein and the nature and sites of their linkages to protein are novel in those glycoproteins which have been examined in any detail. The possible functions of the glycans are mostly not understood. Eubacterial non-S-layer glycoproteins and the glycosylation systems producing them observe more attention.     

Revealing hidden interval graph structure in STS-content data.

MOTIVATION: STS-content data for genomic mapping contain numerous errors and anomalies resulting in cross-links among distant regions of the genome. Identification of contigs within the data is an important and difficult problem. RESULTS: This paper introduces a graph algorithm which creates a simplified view of STS-content data. The shape of the resulting structure graph provides a quality check - coherent data produce a straight line, while anomalous data produce branches and loops. In the latter case, it is sometimes possible to disentangle the various paths into subsets of the data covering contiguous regions of the genome, i.e. contigs. These straight subgraphs can then be analyzed in standard ways to construct a physical map. A theoretical basis for the method is presented along with examples of its application to current STS data from human genome centers. AVAILABILITY: Freely available on request.     

Phytochrome Regulation of the Response to Exogenous Gibberellins by Epicotyls of Vigna sinensis

The elongation rate of cowpea epicotyls from whole cowpea (Vigna sinensis) seedlings and derooted and debladed plants (explants) increased after the main light period (8-hour duration) was extended with either continuous low intensity tungsten light or brief (5 minutes) far-red (FR) irradiation. This end-of-day FR effect was reversed by red (R) irradiation suggesting the involvement of phytochrome. These results confirm and extend those obtained previously with other species. Localization studies indicate the epicotyl to be the site of the photoreceptor. Treatment of cowpea seedlings with paclobutrazol, a gibberellin (GA) biosynthetic inhibitor, abolished the FR promoted epicotyl elongation, indicating a role for GAs in this process. There was no significant difference in epicotyl elongation rates of R plus FR irradiated explants treated with GA₁ or GA₂₀ and R irradiated explants treated with GA₁. However, R irradiation inhibited subsequent epicotyl elongation of GA₂₀ treated explants. Moreover, the observation, using GC-MS, that GA₁ and GA₂₀ are native GAs in cowpea lends support to the concept that phytochrome may control the conversion of endogenous GA₂₀ to GA₁ in cowpea.     

Evaluation of Reductive Release as a Mechanism for Iron Uptake from Ferrioxamine B by Chlorella vulgaris

The involvement of ferric reduction in the iron uptake mechanism of iron-stressed Chlorella vulgaris from ferrioxamine B was investigated. Some comparative data for ferric-citrate was also obtained. EPR and a spectrophotometric assay were used to measure Fe³⁺ reduction. These two methods differed in the absolute quantity but not in effectors of ferric reduction. The mechanism governing ferric reduction was investigated by use of respiratory inhibitors, uncouplers, alternative electron acceptors, and ATPase inhibitors. Reduction appears to play a role in iron uptake from both Fe³⁺-deferrioxamine B and Fe³⁺-citrate; however, the involvement of photoreduction in Fe³⁺-citrate uptake implies multiple reductive mechanisms could be involved.     

Response of aromatic-pathway enzymes to changing physiological states of growth in suspension cultures of Nicotiana silvestris

The activity levels of enzymes of aromatic amino acid biosynthesis respond to changing physiological states of growth, as illustrated by results obtained from suspension-cultured cells of Nicotiana silvestris Speg. et Comes line ANS 1 (2N=24). The experimental system provides a foundation for interpretations about overall regulation of enzyme levels in relationship to growth physiology. Levels of activity for shikimate dehydrogenase (EC 1.1.1.25), prephenate aminotransferase and arogenate dehydrogenase were followed throughout a growth cycle obtained by a conventional subculture protocol. Enzyme date were also obtained from cell cultures maintained in continuous exponential growth for greater than 10 generations (EE cells). Both shikimate dehydrogenase and prephenate aminotransferase exhibited elevated stationary-phase levels of enzyme, much of which was carried over into a subsequent subculture. At least 4 generations of exponential growth were required before diminution of the latter two enzymes to the levels characteristic of truly exponential-phase growth (EE cells) occurred. This is reminiscent of the overall behavior of 3-deoxy-D- arabino -heptulosonate 7-phosphate (DAHP) synthase (EC 4.1.2.15), specifically attributed to the properties of the cytosolic isozyme species (DAHP synthase-Co). Elevation of arogenate dehydrogenase also occurred in stationary-phase cells, but diminished rapidly during lag phase to reach the level characteristic of EE cells.     

Cytofluorometric analysis of anti-lymphocyte antibodies in AIDS

Abstract Anti-lymphocyte antibodies (ALA) have been detected in the plasma of 53.8% of HIV-positive patients tested (CD4/CD8 ratios: mean 0.265; range 0.01 to 0.5) using analytical continuous-flow cytofluorometry. IgG from the AIDS plasma was seen to bind to normal PBL in 53.8% of cases (14/26). In double labelling experiments CD4 + lymphocytes, CD8 + lymphocytes, and B lymphocytes were all bound by the ALA, but monocytes were not bound. Pre-adsorption of the diluted AIDS plasma onto an excess of mouse spleen cells did not remove lymphocyte binding activity. No evidence was found for preferential binding to phytohaemagglutinin-stimulated lymphocytes.
ALA could not be detected in the plasma of normal subjects, patients with acute renal failure undergoing renal dialysis, or patients with high levels of circulating immune complexes.     

Genetic Analysis of Chromosomal Region 67a-D of Drosophila Melanogaster

In an effort to (1) characterize the 67 interval of chromosome 3 of Drosophila melanogaster genetically and (2) isolate mutations of the 67B1 small heat shock protein (hsp) gene cluster specifically, we undertook a mutational analysis of the 67A-D subinterval. Using a deficiency of the 67A2 to 67D11-13 region, Df(3L)AC1, we screened 8700 diepoxybutane-treated chromosomes and 7800 ethyl methanesulfonate-treated chromosomes for visible and lethal mutations throughout this interval and recovered 74 independent recessive lethal mutations, but no visible mutations. One of the lethal mutations, d29A6, was identified as an overlapping deficiency extending from 66F3 to 67B1. An additional 6000 diepoxybutane-treated chromosomes were screened for lethality over d29A6, yielding another four lethal mutations within the 67A2-B1 subinterval. These 78 lethal mutations, along with two others isolated in other laboratories, define 23 essential loci--6 within the 67A2-B1 subinterval and 17 within the 67A2 to D11-13 subinterval. Many of these loci appear to be required for imaginal development only, exhibiting late larval to pharate adult lethal phases. Examination of the 67A2-B1 lethal complementation groups for (1) earlier onset of lethality following a heat shock, (2) missing or altered small hsps on two-dimensional protein gels, and (3) restoration of viability by transformed wild-type copies of the small hsp genes indicates that none of these mutations affect the small hsps. On the basis of this analysis and the known homology of the genes, we conclude that the small hsps are functionally equivalent.     

Population Dynamics of Heterodera glycines Life Stages on Soybean

Population fluctuations of Heterodera glycines differ in fields with high and low initial population densities. In a field with low initial numbers of nematodes, the numbers of cysts and eggs in soil remained low through 100 days from planting then increased during the remainder of the growing season. In a field with high initial nematode populations, numbers increased at 30 days, decreased to low numbers at 100 days, and then resurged to maximum populations at harvest. Numbers of juveniles were greatest at 100 days in the low initial population density field and at planting in the high initial population density field. The initial numbers of eggs in the soil gave the best correlation to soil and root nematode populations 15 and 30 days later. Juveniles in the soil at planting gave the largest correlation coefficients with nematode populations in the roots at 15 days in the field with the low initial population density. Eggs and juveniles in the soil at harvest were poorly related to numbers that overwintered.