Impact on energy metabolism of quantitative and functional cyclosporine-induced damage of kidney mitochondria

In this study we have measured, under experimental conditions which maintained efficient coupling, respiratory intensity, respiratory control, oxidative phosphorylation capacity and protonmotive force. Succinate cytochrome-c reductase and cytochrome-c oxidase activities were also studied. These investigations were carried out using kidney mitochondria from cyclosporine-treated rats (in vivo studies) and from untreated rats in the presence of cyclosporine (in vitro studies). Inhibition of respiratory intensity by cyclosporine did not exceed 21.1% in vitro and 15.9% in vivo. Since there was no in vitro inhibition of succinate cytochrome-c reductase and cytochrome-c oxidase activities, the slowing of electron flow observed can be interpreted as a consequence of an effect produced by cyclosporine between cytochromes b and c₁. Cyclosporine had no effect on respiratory control either in vitro or in vivo. Statistically significant inhibition of the oxidative phosphorylation was observed both in vitro (6.6%) and in vivo (12.1%). Moreover, cyclosporine did not induce any change of membrane potential either in vivo or in vitro. Our findings show that cyclosporine is neither a protonophore, nor a potassium ionophore. In cyclosporine-treated rats we noticed a decrease of protein in subcellular fraction, including the mitochondrial fraction. The role of the inhibition respiratory characteristics by cyclosporine in nephrotoxicity in vivo must take account of these two parameters: inhibition of the respiratory characteristics measured in vitro and diminution of mitochondrial protein in cyclosporine-treated rats.     

Characterization of the unusual basic proteins of cricket spermatid nuclei on the basis of their molecular weights and amino acid compositions

Typical somatic cell type histones are lost from the nucleus during late spermiogenesis in the house cricket; they are replaced by unusual basic proteins specific to the spermatid. We wish to characterize these proteins because they appear to determine the unusual chromatin structures of the spermatid. Molecular weights of the unusual basic proteins were estimated by chromatographing them on Bio-Gel A 0.5 M agarose columns eluted with 6 M guanidine hydrochloride. Two proteins named TH1 and TH2 have molecular weights in the range spanned by the somatic histones. The molecular weight of TH1 is 17 500 and that of TH2 is 15 500. Three additional spermatid proteins were also analyzed by molecular weight determination. They are called here protamines A, B and C, and they have molecular weights in the range typical of protamines. That of A is 6200, of B is 5500 and of C is 3800. They span the range from the large protamines typical of mammalian sperm to the small protamines of salmonid fish. The molecular weights of the TH proteins were also examined by electrophoresis on SDS-polyacrylamide gels. Amino acid compositions determined for TH1 and TH2 show that both are basic proteins rich in arginine relative to lysine. Their compositions are histone-like, but they appear to be distinct histone types rather than variant forms of the somatic histones.     

The lifetime of molecular (Davydov) solitons

The lifetime of Davydov solitons in a one-dimensional system is studied theoretically. The process of thermalization and the properties of solitons at finite temperature are investigated and the processes of soliton creation and disintegration are discussed.     

Structure of the abdominal receptor responsive to internally applied pressure in the blood-feeding insect,Rhodnius prolixus

Summary The sensory receptor responsive to pressure applied internally to the ventral abdominal body wall of the blood-feeding insects, Rhodnius prolixus, is a single sense cell containing, at its distal end, a cilium enclosed within a scolopale, a densely staining structure characteristic of insect scolopidial sensilla. A small spherical structure lies within a dilation near the midregion of the cilium, and contains nine heavily staining bodies, the position of each corresponding to a pair of microtubules in the cilium. Proximal to the dilation, the microtubules are organized in a ring of nine pairs with one microtubule of each pair associated with dyneinlike arms. Dastal to the dilation a central pair of microtubules is present, but dyneinlike arms are absent. The scolopale cell, which gives risc to the scolopale, has cytoplasmic invaginations that form an elaborate array of extracellular compartments surrounding the body wall of the sense cell. These compartments may serve to dampen high frequency vibrations permitting the receptor to respond to pressure exerted by touch, an attribute in keeping with the receptor's proposed function of detecting abdominal distension related to the size and movement of the stomach.     

A recombinant foot-and-mouth disease virus antigen inhibits DNA replication and triggers the SOS response in Escherichia coli

Abstract The 3D gene of foot-and-mouth disease virus encodes the viral RNA dependent RNA polymerase, also called virus infection associated (VIA) antigen, which is the most important serological marker of virus infection. This 3D gene from a serotype Cl virus has been cloned and overexpressed in Escherichia coli under the control of the strong lambda lytic promoters. The resulting 51 kDa recombinant protein has been shown to be immunoreactive with sera from infected animals. After induction of gene expression, an immediate and dramatic arrest of cell DNA synthesis occurs, similar to that produced by genotoxic doses of the drug mitomycin C. This effect does not occur during the production of either a truncated VIA antigen or other related and non-related viral proteins. The inhibition of DNA replication results in a subsequent induction of the host SOS DNA-repair response and in an increase of the mutation frequency in the surviving cells.     

Multiple mechanisms contribute to myenteric plexus ablation induced by benzalkonium chloride in the guinea-pig ileum

Ablation of rat myenteric plexus with benzalkonium chloride has provided a model of intestinal aganglionosis, but the degenerative responses are not well understood. We examined the effects of this detergent on neurons and glia, including expression of c-Myc, c-Jun, JunB, and c-Fos, and on immunocytes in the guinea-pig ileum. Benzalkonium chloride (0.1%) or saline was applied to the serosal surface of distal ileum. Tissues were analyzed 2, 3, or 7 days later and compared with cyclosporine-treated and untreated animals. More than 90% of myenteric neurons were destroyed in ileal segments 3–7 days after benzalkonium-chloride treatment. Glia withdrew processes from around neurons after 2 days and were mostly gone after 3 days. Neuronal c-Myc began to disappear while c-Fos, c-Jun, and JunB were evident in some neuronal nuclei after 2 or 3 days. After 3 days, widespread apoptosis was evident in the myenteric plexus. Populations of T cells, B cells, and macrophage-like cells in untreated and saline-treated myenteric plexuses were substantially increased 3 and 7 days after benzalkonium-chloride treatment. Cyclosporine delayed significant neuronal loss. We conclude that a variety of degenerative mechanisms may be active in this model, including an immune response which may actively contribute to tissue destruction. Received: 13 September 1996 / Accepted: 20 January 1997     

A multiple chemostat system for consortia studies on microbially influenced corrosion

A multiple chemostat system has been developed in which metal specimens can be exposed to a consortium of bacteria. The system comprises a single test chemostat containing the test specimen operated at a high dilution rate to facilitate the wash out of planktonic bacteria, selecting for attached or biofilm growth. This chemostat is fed at a steady low rate by a number of separate chemostats each of which contains a pure axenic culture of one member of the consortium being tested. This system has the advantage of providing a continual inoculum of the test species to the test specimen allowing both aerobic and anaerobic bacteria to be grown in the same system. Constant levels of three bacterial types were maintained in the system: Pseudomonas aeruginosa, Thiobacillus ferrooxidans and Desulfovibrio vulgaris. Exposure of 316L stainless steel electrodes to this system resulted in increased corrosion of coupons exposed biotically, as compared to those exposed abiotically. A current monitoring technique and electrochemical impedance spectroscopy were used to evaluate effects of bacteria on metallic corrosion.