Selective effect of inhibitors on inner mitochondrial membrane channels.

The effect of amphiphilic cationic drugs on the channel activity of the mitochondrial inner membrane was examined with patch-clamp techniques. The therapeutic drugs amiodarone, propranolol and quinine reduced the probability of being open for the multiconductance channel (MCC) activity (levels from 30 pS to over 1 nS). While amiodarone decreased the probability of being open for the voltage dependent approximately 100 pS channel, it increased the conductance 42 +/- 20% (mean +/- SD, n = 6) with no significant change in mean open time. Similar results were obtained with propranolol. These data indicate that the approximately 100 pS channel is distinct from MCC activity.     

Calcium modulation of mitochondrial inner membrane channel activity.

Protocols were defined that enable patch-clamp studies of the approximately 107 pS voltage dependent channel and a class of activity we refer to as MCC (multiconductance channel) which is characterized by multiple levels and transitions as high as 1 to 1.5 nS. If free calcium was kept at 10(-7) M or lower during mitochondrial isolation, no activity was observed at low voltage (+/- 60 mV). If free calcium levels were higher, MCC activity was observed in about 96% of the patches. The observation of approximately 107 pS channel was enhanced from 2% to 68% of patches by washing isolated mitoplasts (mitochondria stripped of outer membrane) with EGTA. Increasing matrix calcium from 10(-9) to 10(-5) M decreased the probability of opening for the MCC and approximately 107 pS activities.     

Generation of potential in lipid bilayer membranes as a result of proton-transfer reactions in the unstirred layers

The addition of an uncoupler in the presence of a concentration gradient of weak acids or bases (sodium acetate and ammonium chloride) leads to the generation of a potential on lipid bilayer membranes (LBM) which is positive in sign on the side of the membrane with a high concentration of sodium acetate and negative on the side with a high concentration of ammonium chloride. It is shown that the potential was caused by the pH gradient in the unstirred layers. These effects can be understood in terms of the previously described [Science,182, 1258 (1973)] model for the transfer of weak acids and bases through LBM. This system described may be useful for quantitation of permeabilities for weak acids and bases through bilayer membranes.     

Effect of lipids with different spontaneous curvature on the channel activity of colicin E1: evidence in favor of a toroidal pore

The channel activity of colicin E1 was studied in planar lipid bilayers and liposomes. Colicin E1 pore-forming activity was found to depend on the curvature of the lipid bilayer, as judged by the effect on channel activity of curvature-modulating agents. In particular, the colicin-induced trans-membrane current was augmented by lysophosphatidylcholine and reduced by oleic acid, agents promoting positive and negative membrane curvature, respectively. The data obtained imply direct involvement of lipids in the formation of colicin E1-induced pore walls. It is inferred that the toroidal pore model previously validated for small antimicrobial peptides is applicable to colicin E1, a large protein that contains ten alpha-helices in its pore-forming domain.     

Isolation and characteristics of antibodies against synthetic fragments of oncoproteins. I. Antiserum against the transforming protein p28sis of simian sarcoma virus

To generate the antibodies to the transforming protein (p28sis) of simian sarcoma virus (SSV), the rabbits were immunized with peptides, corresponding to 200-206 and 201-210 sequences of p28sis, conjugated with protein carriers by different ways. The synthesis of peptides was carried out by the classical techniques in solution by using the benzyl type side protecting groups. Antibody titres against peptides were determined by ELISA and protein specificity by radioimmunoprecipitation and immunoblotting. It was shown that the antibodies to 201-210 peptide recognize p28sis and its dimer p56sis in marmoset and rat cells transformed by simian sarcoma virus.     

The use of phospholipid-impregnated millipore filters for recording nonelectrogenic cation flows in the presence of Men+/nH+ exchangers

It has been shown that with a cation (K+, Na+, Ca2+) concentration gradient on a Millipore filter impregnated with a decane solution of phospholipid, in the presence of a Men+/nH+ exchanger (nigericin, monensin, A23187), addition of a protonophore induces the formation of an electric potential positively charged on the side where the concentration of the cation is lower. The formation of the potential is induced by the hydrogen ion concentration gradient in the filter and in the unstirred layers as a result of the Men+/nH+ exchange. In such a system, with a pH gradient on the filter in the presence of monensin and valinomycin, a potential is generated with the plus on the side of the lower concentration of hydrogen. The effect is the result of the formation of a potassium ion concentration gradient in the unstirred layers in the course of the K+/H+ exchange. It is concluded that phospholipid-impregnated filters can be used for search and identification of electroneutral membrane ionophores of the Men+/nH+ exchanger type.     

Long-term dynamics of species composition and abundance of flatfish in waters off Primorye (the Sea of Japan)

Based on the data of trawl surveys, changes in the structure of species composition and flatfish abundance (Pleuronectidae) in waters off Primorye are shown in the period embracing over 20 years (1983 to 2004). In waters off Primorye, 14 flatfish species were recorded in catches. At the present time, the structure of the flatfish part of the fish community in waters off Primorye has undergone considerable changes in comparison with the 1980s: the proportion of deepwater flatfish has considerably increased against the background of a decrease in the abundance of coastal species. A general decrease in the numbers and biomass of flatfish in waters off Primorye is recorded, which is caused by natural reasons against the background of an inconsiderable fishery intensity.     

Interaction of recombinant analogs of spider silk proteins 1F9 and 2E12 with phospholipid membranes

Recombinant analogs of spider dragline silk proteins 1F9 and 2E12 are characterized by numerous repeats consisting of hydrophobic poly-Ala blocks and Gly-rich sequences with a substantial number of positively charged amino acid residues which suggest a pronounced ability to interact with negatively charged phospholipid membranes. Actually both proteins displayed substantial binding affinity towards lipid vesicles formed of acidic lipids as measured by fluorescence correlation spectroscopy (FCS) using rhodamine-labeled conjugates of the proteins. Both proteins did not induce liposome leakage, fusion or breakdown, but were able to bring about liposome aggregation. 1F9 was more active in the induction of liposome aggregation compared to 2E12. Interestingly, 2E12 markedly decreased the rate of calcium-induced liposome fusion. Circular dichroism data showed that binding of the proteins to negatively charged phosphatidylserine liposomes provoked transition from the left-handed helix of polyproline II (PPII) type to β-structures and α-helices. The data suggested predominantly surface location of membrane bound proteins without significant perturbation of their hydrophobic core.