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.     

Presence of haemocyte-like cells in coccinellid reflex blood

Abstract.  Contrary to current assumptions, the reflex blood of two-spot ladybirds, Adalia bipunctata , and seven-spot ladybirds, Coccinella septempunctata , contains haemocyte-like cells. Furthermore, DNA can be extracted and amplified from coccinellid reflex blood, confirming the presence of haemocyte-like cells and demonstrating a nondestructive method of DNA extraction.     

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.     

Evidence for carrier-mediated,energy-dependent uptake of urea in some bacteria

Evidence for the existence of an energy-dependent urea permease was found for Alcaligenes eutrophus H16 and Klebsiella pneumoniae M5a1 by studying uptake of ¹⁴C-urea. Since intracellular urea was metabolized immediately, uptake did not result in formation of an urea pool. Evidence is based on observations that the in vivo urea uptake and in vitro urease activity differ significantly with respect to kinetic parameters, temperature optimum, pH optimum, response towards inhibitors and regulation. The K _m for urea uptake was 15–20 times lower (38 M and 13 M urea for A. eutrophus and K. pneumoniae, respectively) than the K _m of urease for urea (650 M and 280 M urea), the activity optimum for A. eutrophus was at pH 6.0 and 35°C for the uptake and pH 9.0 and 65°C for urease. Uptake but not urease activity in both organisms strongly decreased upon addition of inhibitors of energy metabolism, while in K. pneumoniae, potent inhibitors of urease (thiourea and hydroxyurea) did not affect the uptake process. Significant differences in the uptake rates were observed during growth with different nitrogen sources (ammonia, nitrate, urea) or in the absence of a nitrogen source; this suggested that a carrier is involved which is subject to nitrogen control. Some evidence for the presence of an energy-dependent uptake of urea was also obtained in Pseudomonas aeruginosa DSM 50071 and Providencia rettgeri DSM 1131, but not in Proteus vulgaris DSM 30118 and Bacillus pasteurii DSM 33.Non-standard abbreviations CCCP Carbonylcyanide-m-chlorphenylhydrazone - DCCD dicyclohexylcarbodiimide - DNP 2,4-dinitrophenole