fimA-folD genes linkage in Salmonella identifies a putative junctional site of chromosomal rearrangement in the enterobacterial genome

Abstract Analysis of the Salmonella chromosomal region located upstream of the fimA gene (coding for the major type 1 fimbrial subunit) showed a close linkage of this gene to the folD gene (coding for the enzyme 5,10-methylenetetrahydrofolate dehydrogenase/5, 10-methenyltetrahydrofolate cyclohydrolase), indicating that the fim gene cluster of Salmonella , unlike that of Escherichia coli , has no regulatory genes located upstream of fimA and apparently terminates with this gene. The respective locations of the fim and folD genes in the E. coli and Salmonella genetic maps suggests that the fimA-folD intergenic region of Salmonella encompasses a junctional site of a genetic rearrangement that probably originated from the different chromosomal location of the fim genes in these species.     

The use of GMOs (genetically modified organisms): agricultural biotechnology or agricultural biopolitics?

Agricultural biotechnologies embrace a large array of conventional and modern technologies, spanning from composting organic by-products of agriculture to innovative improvement of quality traits of about twenty out of the mostly cultivated plants. In EU a rather restrictive legislative framework has been installed for GMOs, requiring a risk assessment disproportionate with respect to conventional agriculture and organic farming products. The latter are far from being proved safe for human and animal health, and for the environment.Biotechnology of GMOs has been overtaken by biopolitics. On one side there are biotechnological challenges to be tackled, on another side there is plenty of ground for biopolitical decisions about GMOs. Perhaps the era of harsh confrontation could be fruitfully replaced by sensible cooperation, in order to get a sustainable agricultural development.     

Hydrolysis and protection from hydrolysis of enkephalins in human plasma

Seven groups of enkephalin-degrading enzymes and three groups of inhibitors active on these enzymes were separated from human plasma. The activity of the enzymes in hydrolyzing enkephalins and of the inhibitors in protecting enkephalins from proteolysis was measured. Results obtained with the endogenous inhibitors were compared to those relative to synthetic inhibitors. Data obtained indicate that all enkephalin-degrading enzymes found in plasma are significantly inhibited by the endogenous substances present in this tissue. The inhibition of the different classes of plasma enzymes by two of the three groups of endogenous substances is quite uniform, while one group of inhibitors appears specific to dipeptidylpeptidases. Results obtained are discussed in terms of the functional role of the inhibitory substances and of the possible pharmacological implication of their presence in human plasma.     

Voltammetric studies on the electrochemical behaviour of membrane-entrapped hemes

Summary The electrochemical behaviour of Fe(III)-protoporphyrin IX entrapped into a cellulose triacetate membrane has been investigated by cyclic voltammetry. The physical entrapment into a solid matrix does not modify the redox properties of the entrapped berries, which also act as efficient promoters in the electrochemistry of cytochromec. Such a system represents a promising example of a simple solid-state promoter, and stimulates further investigations in order to obtain more complex systems that may be of significance for basic and applied bioelectrochemistry.     

Actin synthesis is not regulated by granulosa cells in mouse growing and preovulatory oocytes

The synthesis and intracellular distribution of actin were studied in isolated dictyate and metaphase II mouse oocytes by (1) sodium dodecyl sulfate-polyacrylamide gel electrophoresis of newly synthetized oocyte protein and (2) cytochemical F-actin labeling by fluorescent phalloidin. Unpermeabilized, fully grown oocytes bound phalloidin intensely at the level of the zona pellucida (ZP), such ZP-associated actin representing a significant portion of total actin found in these cells. In contrast, phalloidin binding to ZP was very low in growing oocytes and was undetectable in ovulated, metaphase II eggs. When ZP-associated actin of fully grown oocytes was removed by prolongedly exposing oocytes to α-chymotrypsin, the amount of newly synthesized actin displayed by cumulus-enclosed oocytes was reduced to a level comparable to that shown by oocytes isolated from granulosa cells. We demonstrate that ZP-associated actin belongs to granulosa cell processes that remain within the ZP as a consequence of oocyte isolation procedures. We conclude that actin synthesis of mouse oocytes is not regulated by granulosa cells.     

Antibiotic resistance in strains of Listeria spp. from meat products

The susceptibility or resistance to 26 antimicrobial agents was determined for 64 strains of Listeria monocytogenes and 102 strains of L. innocua isolated from Italian meat products. Some strains of L. monocytogenes were found to be resistant to tetracycline, erythromycin, co-trimoxazole and clindamycin. No plasmids were found in any L. monocytogenes strain. Five strains of L. innocua contained a 7.9 kbp plasmid, but these isolates were not resistant to any antibiotic in common and treatment with curing agents could not eliminate resistance to antibiotics. These results suggest that antibiotic resistance was not likely to be plasmid mediated in our strains.     

Characterization of amine oxidases from pisum, lens, Lathyrus and Cicer

Amine oxidases have been purified to homogeneity from Pisum sativum, Lens esculenta, Lathyrus sativus and Cicer arietinum. The enzymes have a M_r. of 150 000 and are composed of two identical subunits of 72 000. The amine oxidases showed an isoelectrophoretic heterogeneity.     

Synthesis of glycoconjugates in mouse primordial germ cells

The synthesis of protein-bound carbohydrates has been studied in primordial germ cells (PGCs) and in somatic cells of 12.5 to 13.5-days-postcoitum (dpc) fetal mouse gonads. Both cell types were shown to synthesize asparagine-linked glycopeptides and glycosaminoglycans (GAGs). In addition, PGCs also synthesize lactosaminoglycans (LAGs) although in different proportions in female and male germ cells. Female PGCs, which at 13.5 dpc are entering meiosis, synthesize mainly LAGs, and minor amounts of hyaluronic acid (HA) and chondroitin sulfate (CS). Male germ cells, on the other hand, synthesize mainly CS. Furthermore, somatic cells of fetal gonads synthesize HA as the major class of GAGs. It is suggested that the activation of LAG synthesis in developing germ cells might be related to the beginning of meiosis. Moreover, we propose that HA synthesis might be developmentally regulated in somatic cells of the gonad, in order to regulate the establishment of specific interactions with germ cells.     

Monolayer black membranes from bipolar lipids of archaebacteria and their temperature-induced structural changes

The membrane of Caldariella acidophila, an extreme thermophilic archaebacterium, is characterized by unusual bipolar complex lipids. They consist of two nonequivalent polar heads, linked by a C40 alkylic component. The molecular organization of these lipids in the plasma membrane is still a matter of study. In this paper, we present current-voltage measurements on artificial bipolar lipid membranes, indicating that molecules are indeed organized as a covalently bound bilayer, in which each molecule is completely stretched and spans its entire thickness. Furthermore, conformational transitions of these artificial membranes (which could be formed only above 70 degrees C from a lipid/squalene dispersion) are analyzed in the 80 to 15 degrees C temperature range. Abrupt variations in capacitance and valinomycin-induced conductance seem to indicate the occurrence of at least two structural changes. Measurements are also extended to different solvent systems. Results are consistent with the picture of a monolayer bipolar lipid membrane in which few solvent molecules align themselves parallel to the lipophilic chains. The amount of solvent as well as the temperature at which conformational transitions occur, depend on the solvent system in which the lipid is dispersed.