Isolation and purification of proteins from the symbiosome membrane of yellow lupine root nodules

A unique feature of the symbiotic association between legume plants and rhizobia is the plant-derived membrane which separates the symbionts within root nodule; this membrane is termed the peribacteroid membrane (PBM). Although this membrane plays a vital role in facilitating transport and other processes in nodules, little is known about the proteins that are associated with and are an integral part of it. The objective of this work was to apply modern methods of protein purification to the characterisation of proteins of peribacteroid membrane from nodules of yellow lupine (Lupines luteus). The 17-kDa protein was isolated from purified peribacteroid membrane using size exclusion and ion exchange chromatography (FPLC). The N-terminal amino acid sequence of this protein was determined; the sequence does not match any of the previously reported lupine and other legume sequences. Following detergent solubilisation of purified peribacteroid membrane, integral proteins of 15 to 20 kDa were purified by size exclusion chromatography.     

Activities of a Mechanosensitive Ion Channel in anE. Coli Mutant Lacking the Major Lipoprotein

Summary The activity of the mechanosensitive (MS) ion channels in membrane patches, excised fromE. coli spheroplasts, was analyzed using the patch-clamp technique. Outer membranes from a mutant lacking the major lipoprotein (Lpp) and its wildtype parent were examined. The MS-channel activities in the wild-type membrane rarely revealed substates at the time resolution used. These channels showed a stretch sensitivity indicated by the IISP (the suction for ane-fold increase in channel open probability) of 4.9 mm Hg suction. The MS-channel activities oflpp included a prominent substate and showed a weaker mechano-sensitivity with an 1/S _p of 10.0 mm Hg. Whereas small amphipaths (chlorpromazine, trinitrophenol) or a larger amphipath (lysolecithin) all activated the MS channel in the wild-type membrane under minimal suction, only the larger lysolecithin could activate the MS channel in thelpp membranes. After lysolecithin addition, thelpp membrane became more effective in transmitting the stretch force to the MS channel, as indicated by a steepening of the Boltzmann curve. We discuss one interpretation of these results, in which the major lipoprotein serves as a natural amphipath inserted in the inner monolayer and the loss of this natural amphipath makes the bilayer less able to transmit the gating force.     

Anther culture and Hordeum bulbosum-derived barley doubled haploids mutations and methylation

Anther culture and Hordeum bulbosum-derived doubled haploid (DH) lines of barley (Hordeum vulgare L.) were analyzed for RFLP and RAPD polymorphisms. Polymorphisms were not detected in the anther culture-or H. bulbosum-derived DH lines among 273 RFLP and 89 polymerase chain reaction (PCR)-amplified DNA fragments assayed. It was calculated that base substitution or small deletion/insertion mutations had not been induced among 401 640 by screened. Large deletion/insertion mutations were not observed among 33 Mb screened. Polymorphisms were observed when DNA was digested with the methylation-sensitive restriction enzymes HpaII and MspI: these RFLPs originated primarily from the anther culture-derived doubled haploids. The data indicate that heritable DNA methylation changes had occurred during DH production, particularly with the anther culture method.     

Analysis of mRNA for class I HLA on human gametogenic cells

We have studied mRNA expression for Class I HLA (human leukocyte antigen) on male germ cells by amplification of gene fragments in PCR techique and by Northern hybridization. RNA was extracted from fractionated gametogenic cells (isolated from testis) and reversely transcribed. Then, cDNA was amplified for specific HLA sequence (1151 bp) representing whole-length coding sequence (HLA, -A, -B, -C). The specificity of this product was confirmed in “nested” PCR of 400 bp gene fragment coding for alpha 2 domain, alpha 3 domain, and the transmembrane portion of Class I HLA. The results indicate minimal expression of classical Class I HLA on gametogenic cells. Northern hybridization with 669 bp cDNA fragment (spanning for alpha 3 domain, transmembrane, cytoplasmic, and 3′ untraslated region) resulted in a low intensity signal from gametogenic cell fractions and confirmed our findings obtained by PCR. The minimal expression of classical HLA antigens may create a neutral cover for the male reproductive system, thereby preventing an immunological response during germ cell differentiation. © 1994 Wiley-Liss, Inc.     

Hypertriglyceridemic serum from magnesium-deficient rats induces proliferation and lipid accumulation in cultured vascular smooth muscle cells

An important characteristic of hyperlipemia associated with magnesium deficiency in rats is the postprandial accumulation of triglyceride-rich lipoproteins. The present investigation was performed to determine the effect of serum from magnesium-deficient animals on cultured vascular smooth muscle cells (VSMC). Sera were obtained from control and magnesium-deficient rats fed adequate or deficient diets for 8 days. Magnesium-deficient animals were hypertriglyceridemic compared with control rats, but their total cholesterolemia was not significantly modified. Pooled sera from control and magnesium-deficient animals were added to the culture medium at various concentrations. The maximum of proliferation for both control and magnesium-deficient sera was reached when they were added at 6% to the culture medium and on day 4 after the begining of incubation. Medium containing serum from magnesium-deficient rats stimulated the cell proliferation as monitored by cell count and [³H]thymidine incorporation. Staining of VSMC with Oil red O and measuring lipids have shown a marked lipid accumulation (triglycerides) in cells incubated with serum obtained from magnesium-deficient animals compared with serum from control rats. These results indicate that serum from magnesium-deficient rats contains factors that stimulate proliferation of arterial medial cells and that hyperlipemia associated with magnesium-deficiency may cause lipid accumulation in vascular cells.     

Relationships between food and cellulase activity in freshwater fishes

The food and cellulase activity of five cyprinid and one salmonid species were examined. All Cyprinidae species showed cellulase activity. No activity was found in pelagic Coregonus albula (Salmonidae). Cellulase activity showed a positive correlation with the amount of highly processed plant detritus in the gut. No correlation was found between the activity level and the amount of fresh fragments of macrophytes and filamentous algae.     

On the taste of stereoisomeric cyclic dipeptides containing a proline residue

An investigation of the taste character and intensity of sixproline-containing cylic dipeptides demonstrates that thesecompounds are differentiated largley on the basis of their chemicalconfiguration. ^x/ Permanent address: Technical University, 80–952 Gdask,Poland     

The synthesis of racemic purpurosamine B

Starting from methyl 4,6-dichloro-4,6-dideoxy-α-D-galactopyranoside (1), D-chalcose (4,6-dideoxy-3-O-methyl-D-xcylo-hexopyranose) (5) was prepared by dechlorination with tributyltin hydride, selective benzoylation with benzoyl cyanide at O-2, methylation at O-3, and acid hydrolysis. D-Chalcose (5) was obtained as well by direct methylation of 1 with diazomethane at O-3, reduction with tin hydride, and hydrolysis. Chalcosyl bromide prepared from 5 was not very suitable for β-glycoside synthesis under Koenigs-Knorr conditions, and better results were obtained with 2- O-acetyl-4,6-dichloro-4,6-dideoxy-3-O-methyl-α-D-galactopyranosyl bromide, which gave β-glycosides with methanol, cyclohexanol, benzyl alcohol, 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose, and methyl 2,3-di-O-benzyl-6-deoxy-α-D-glucopyranoside. After dechlorination with tributyltin hydride, the corresponding β-glycosides of D-chalcose were obtained in good yield.     

Chronobiological Aspects of Jejunum Function in Humans

This review is intended to present our knowledge on both chronomorphology and chronophysiology of jejunum mainly in humans, as well as on implications of chronobiologic principles in the practice of gastroenterology.