An efficient method for isolation of plasmid DNA from methylotrophic bacteria

A method, suitable for the isolation of closed circular plasmid DNA from methylotrophic bacteria is described. Improvement of cell lysis was achieved by butanol extraction of cells before application of the lytic agent. Using this method, cryptic plasmids of 7.8, 14, 36 and 200 kb were purified from soil-isolated methylotrophs.     

Effect of actinomycin D on viability,sporulation and nucleotide pool ofBacillus megaterium

A transient 7-fold rise of ppGpp concentration, 2-3-fold increase of pppGpp concentration and 50 % drop of the concentration of GTP inBacillus megaterium cells immediately after their transfer to the sporulation medium were observed. Actinomycin D, in concentrations inhibiting RNA synthesis by 95%, blocked the rise of the (p)ppGpp pool and caused an instant several-fold increase of the GTP level. When the cells were exposed to actinomycin D in the sporulation medium for a 1-h period (time 0–1 h, 1–2 h or 2.20–3.20-h), they were able to form colonies on nutrient agar after being kept, in addition for 1–2 h in the sporulation medium free of the antibiotic. The ability of sporulation was, however, markedly limited. The share of cells that could sporulate increased when the irreversible sporulation phase was reached.     

Elastogenesis in the wall of the human thoracic aorta

The results of this study dealing with the human thoracic foetal aorta testify that even in the middle of the fifth month of development the internal elastic membrane is not yet completely continuous. Furthermore they show that elastogenesis in the tunica media of the human thoracic aorta does not begin directly below the internal elastic membrane, as it does in the foetal aorta of the laboratory rat, but, as it can be seen in our material, somewhat deeper in the developing tunica media. A thin layer of less differentiated tunica media cells persists for a long time in the vicinity of the internal elastic membrane. In the middle of the fifth month, the fusing elastic membrane segments in the tunica media still consist of very immature elastic tissue with a large proportion of the microfibrillar component. The collagen fibrils in the intercellular spaces in the whole depth of the wall of the developing aorta do not become a part of the elastic membranes. Their bundles merely accompany all the elastic membranes in the wall of the thoracic aorta, including the internal elastic membrane.     

Enzyme polymorphism and clinical variability of diseases: study of acid phosphatase locus 1 (ACP1) in obese subjects

The ACP1*A allele of erythrocyte acid phosphatase (ACP1) has a lower enzymatic activity when compared to other ACP1 alleles and is associated with maximal rate of body growth during intrauterine life. In three different samples of obese subjects (total number = 218). ACP1*A was associated with extreme body mass deviations. No difference in ACP1 allele distribution was observed between obese and nonobese subjects. These data suggest that a genetically determined variability of ACP1 influences the degree of obesity, but only when obesity itself has been triggered by some other factors.     

First record of Crustacea Malacostraca from fresh waters in the Canary Islands

Crustacea Malacostraca were hitherto unknown from fresh waters of the Canary Islands. A new species of Amphipoda, Rhipidogammarus rheophilus, has recently been discovered in springs and spring brooks in Tenerife.

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Resumen Crustacea Malacostraca era hasta ahora desconocida de las aguas dulces de las Islas Canarias. Una nueva especie de anfípodo, Rhipidogammarus rheophilus, ha sido recientemente descubierto de fuentes y manantiales de Tenerife.

     

Survival strategy of Escherichia coli and Enterococcus faecalis in illuminated fresh and marine systems

Some effects of visible light on Escherichia coli and Enterococcus faecalis in natural freshwater and seawater were studied by plate counts, colony area measurements, and direct counts. A large number of somnicells (non-culturable cells) were noted in illuminated systems as compared with non-illuminated ones. Colony areas were significantly smaller in illuminated systems. Indirect activity measurements were used to test the effects of visible light on the ability of E. coli and Ent. faecalis to metabolize substrates ([14C]glucose) in natural waters. In illuminated systems, a decrease of glucose uptake was observed. When percentages of assimilation and respiration with respect to the total glucose uptake were analysed a decrease of assimilation percentages and an increase of respiration percentages were observed. In addition, differences in glucose uptake, assimilation and respiration by enteric bacteria were detected for E. coli at the beginning of the experiments between fresh- and seawater and these were interpreted as a toxic effect exerted by seawater on E. coli cells. Differences between species, natural waters and parameters studied (excepting glucose assimilation) were detected in the illuminated systems. We concluded, however, that enteric bacteria under visible light illumination show a general survival strategy characterized by reaching progressively a somnicell stage which can be defined in terms of their (1) inability to form colonies on standard bacteriological media, (2) inability to incorporate substrates, and (3) inactivation of biosynthetic processes.     

Differential accessibility of the tail domain of nuclear lamin A in interphase and mitotic cells

Human autoantibodies reactive against the tail domain exclusive to lamin A and absent from lamin C have been used for immunofluorescence studies on human fibroblast and epithelial cells. These autoantibodies were seen to react on mitotic cells where lamin A is present in a soluble depolymerized form and to react against lamin A in assembled interphase nuclear lamina after in situ extraction of chromatin. Taken together, these results support the suggestion that the tail domain of lamin A may be involved in the putative interaction of lamin A with chromatin.     

Phospholipid metabolism modulates cyclic nucleotide phosphodiesterase activity in rat heart microsomes

Cyclic nucleotide phosphodiesterase activity in rat heart microsomes is attributable to several isoenzymatic forms: a cyclic AMP-specific, a cyclic GMP-specific, and a cyclic GMP-stimulated enzyme. Incubation of microsomes with an exogenous phospholipase C (C. welchii) induced a marked stimulation (+126%) of cyclic AMP phosphodiesterase and a moderate stimulation (+49%) of cyclic GMP-phosphodiesterase in the membrane-bound fraction. Besides, a notable fraction of activity was solubilized by the treatment. A parallel decrease in the activating effect of cyclic GMP on the hydrolysis of cyclic AMP was observed in the membranes (down to 18% of the control effect). It resulted from a marked stimulation of the basal activity, while the activated level was unaffected. The treatment by an exogenous phospholipase D induced more moderate modifications. The addition to microsomes of oleyl,acetyl-glycerol, but not of long chain-diacylglycerols, partly reproduced the phospholipase C effect. Phosphatidate also induced variations in phosphodiesterase activity, and could thus participate in the phospholipase effects. These results suggest that endogenous phospholipases, the activity of which is modulated by hormonal stimuli, might influence phosphodiesterase activity in cardiac membranes by producing phospholipid metabolites, with potential consequences on heart contractility.     

Involvement of the phosphoinositol (PI) system in the mechanism of hormonal imprinting

Certain components of the phosphoinositol (PI) system are present in the unicellular Tetrahymena. Treatment of Tetrahymena with insulin did not alter the relative proportions of the examined six phospholipid components (PIP2, PIP, phosphatidylcholine, phosphatidylethanolamine, PI, PA), but the primary interaction (imprinting) with insulin accounted for an about 75% decrease in the PIP2-level and an about 20% increase in the phosphatidylethanolamine level. The experimental results strongly suggest that hormonal imprinting accounted for adjustment of the second messenger systems of Tetrahymena to an energy saving level.     

Mycobacteria glycolipids as potential pathogenicity effectors: alteration of model and natural membranes

Four mycobacterial wall glycolipids were tested for their effects on phospholipidic liposome organization and passive permeability and on oxidative phosphorylation of isolated mitochondria. From fluorescence polarization of diphenylhexatriene performed on liposomes it was concluded that the two trehalose derivatives (dimycoloyltrehalose and polyphthienoyltrehalose) rigidified the fluid state of liposomes, the triglycosyl phenolphthiocerol slightly fluidized the gel state, while the peptidoglycolipid ("apolar" mycoside C) just shifted the phase transition temperature upward. Dimycoloyltrehalose was without effect on liposome passive permeability, as estimated from dicarboxyfluorescein leak rates, and polyphthienoyltrehalose and triglycosyl phenolphthiocerol slightly decreased leaks, while mycoside C dramatically increased leaks. Activity of these lipids on mitochondrial oxidative phosphorylation was examined. The two trehalose derivatives have been tested previously: both had the same type of inhibitory activity, dimycoloyltrehalose being the most active. Triglycosyl phenolphthiocerol was inactive. Mycoside C was very active, with effects resembling those of classical uncouplers: this suggested that its activity on mitochondria was related to its effect on permeability. All these membrane alterations were called nonspecific because it is likely that they result from nonspecific lipid-lipid interactions, and not from recognition between specific molecular structures. Such nonspecific interactions could be at the origin of some of the effects of mycobacteria glycolipids on cells of the immune system observed in the last few years.