Solid-state 15N NMR of oriented lipid bilayer bound gramicidin A'

Highly oriented samples of lipid and gramicidin A' (8:1 molar ratio) have been prepared with the samples extensively hydrated (approximately 70% water v/w). These preparations have been shown to be completely in a bilayer phase with a transition temperature of 28 degrees C, and evidence is presented indicating that the gramicidin is in the channel conformation. An estimate of the disorder in the alignment of the bilayers parallel with the glass plates used to align the bilayers can be made from the asymmetry of the nuclear magnetic resonances (NMR). Such an analysis indicates a maximal range of disorder of +/- 3 degrees. Uniformly 15N-labeled gramicidin has been biosynthesized by Bacillus brevis grown in a media containing 15N-labeled Escherichia coli cells as the only nitrogen source. When prepared with labeled gramicidin, the oriented samples result in high-resolution 15N NMR spectra showing 12 resonances for the 20 nitrogen sites of the polypeptide. The frequency of the three major multiple resonance peaks has been interpreted to yield the approximate orientation of the N-H bonds in the peptide linkages with respect to the magnetic field. These bond orientations are only partially consistent with the extant structural models of gramicidin.     

Retention of low-fitness genotypes over six decades of admixture between native and introduced tiger salamanders

Background  

Introductions of non-native tiger salamanders into the range of California tiger salamanders have provided a rare opportunity to study the early stages of secondary contact and hybridization. We produced first- and second-generation hybrid salamanders in the lab and measured viability among these early-generation hybrid crosses to determine the strength of the initial barrier to gene exchange. We also created contemporary-generation hybrids in the lab and evaluated the extent to which selection has affected fitness over approximately 20 generations of admixture. Additionally, we examined the inheritance of quantitative phenotypic variation to better understand how evolution has progressed since secondary contact.     

Seed Germination and Seedling Growth in Sopubia delphinifolia - a Hemi-root Parasite: Germination Requirements

Requirements for seed germination (emergence of radicle) andseedling formation (emergence of both radicle and cotyledons)of a hemi-root parasite Sopubia delphinifolia were studied inthe absence of any host stimulus, in Petri dish and asepticcultures. Both water washing in trickling tap water as wellas cold treatment were effective in inducing/stimulating germinationand seedling formation in the light. Although ethrel, an ethylenereleasing compound, stimulated radicle emergence it inhibitedthe emergence of the cotyledons. Light was found to be essentialfor germination; none of the growth substances could replacethe light requirement. Light responses seem to be mediated throughthe phytochrome system. The results indicate that the emergenceof the radicle, its further growth into the root and the emergenceof cotyledons are controlled by different factors. Sopubia delphinifolia, hemi-root parasite, seed germination requirements, pretreatment, seedling formation     

Inhibitory effect of the flavonoid silymarin on the erythrocyte hemolysis induced by phenylhydrazine

The flavonoid silymarin, which is used as a therapeutical agent in the treatment of liver diseases, can inhibit the hemolysis and lipid peroxidation induced by phenylhydrazine on erythrocytes obtained from rats treated with the flavonoid. This effect is ascribed to the antioxidant properties as a free radical scavenger exhibited by the flavonoid. Silymarin failed to inhibit the glutathione depletion induced by phenylhydrazine on erythrocytes. It is proposed that the flavonoid acts at the membrane level of the cell avoiding the lipid peroxidative and fluidizing effect of phenylhydrazine.     

ATP synthase from bovine mitochondria: sequences of imported precursors of oligomycin sensitivity conferral protein, factor 6, and adenosinetriphosphatase inhibitor protein

Oligomycin sensitivity conferral protein (OSCP), factor 6 (F6), and ATPase inhibitor protein are all components of the ATP synthase complex of bovine mitochondria. They are encoded in nuclear DNA. Complementary DNA clones encoding the precursors of these proteins have been isolated from a bovine library by using mixtures of synthetic oligonucleotides as hybridization probes, and their DNA sequences have been determined. The deduced protein sequences show that the OSCP, F6, and inhibitor proteins have N-terminal presequences of 23, 32, and 25 amino acids, respectively. These presequences are not present in the mature proteins. It is assumed that they serve to direct the proteins into the mitochondrial matrix. The cDNA clones have also been employed as hybridization probes to investigate the genetic complexity of the three proteins in cows and humans. These experiments indicate that the bovine and human inhibitor and bovine F6 proteins are encoded by single genes but suggest the possibility of the presence in both species of more than one gene (or pseudogenes) for the OSCP.     

The Himalayan ground-beetle genus Aparupa (Carabidae) with three new species

Abstract. A key is provided for the determination of the seven species of Aparupa Andrewes including three new species, nepalensis and lateromarginalis from Nepal, and andrewesi from northern India.     

Magnetic resonance imaging and electromyography as indexes of muscle function.

Electromyography (EMG) is commonly used to determine the electrical activity of skeletal muscle during contraction. To date, independent verification of the relationship between muscle use and EMG has not been provided. It has recently been shown that relaxation- (e.g., T2) weighted magnetic resonance images (MRI) of skeletal muscle demonstrate exercise-induced contrast enhancement that is graded with exercise intensity. This study was conducted to test the hypothesis that exercise-induced magnetic resonance (MR) contrast shifts would relate to EMG amplitude if both measures reflect muscle use during exercise. Both MRI and EMG data were collected for separate eccentric (ECC) and concentric (CON) exercise of increasing intensity to take advantage of the fact that the rate of increase and amplitude of EMG activity are markedly greater for CON muscle actions. Seven subjects 30 +/- 2 (SE) yr old performed five sets of 10 CON or ECC arm curls with each of four resistances representing 40, 60, 80, and 100% of their 10 repetition maximum for CON curls. There was 1.5 min between sets and 30 min between bouts (5 sets of 10 actions at each relative resistance). Multiple echo, transaxial T2-weighted MR images (1.5 T, TR/TE 2,000/30) were collected from a 7-cm region in the middle of the arm before exercise and immediately after each bout. Surface EMG signals were collected from both heads of the biceps brachii and the long head of the triceps brachii muscles. CON and ECC actions resulted in increased integrated EMG (IEMG) and T2 values that were strongly related (r = 0.99, P < 0.05) with relative resistance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Therapeutic Efficacy of an ω-3-Fatty Acid-Containing 17-β Estradiol Nano-Delivery System against Experimental Atherosclerosis

Atherosclerosis and its consequences remain prevalent clinical challenges throughout the world. Initiation and progression of atherosclerosis involves a complex, dynamic interplay among inflammation, hyperlipidemia, and endothelial dysfunction. A multicomponent treatment approach targeted for delivery within diseased vessels could prove beneficial in treating atherosclerosis. This study was undertaken to evaluate the multimodal effects of a novel ω-3-fatty acid-rich, 17-β-estradiol (17-βE)-loaded, CREKA-peptide-modified nanoemulsion system on experimental atherosclerosis. In vitro treatment of cultured human aortic endothelial cells (ECs) with the 17-βE-loaded, CREKA-peptide-modified nanoemulsion system increased cellular nitrate/nitrite, indicating improved nitric oxide formation. In vivo, systemic administration of this nanoemulsion system to apolipoprotein-E knock out (ApoE^-/-) mice fed a high-fat diet significantly improved multiple parameters related to the etiology and development of occlusive atherosclerotic vasculopathy: lesion area, circulating plasma lipid levels, and expression of aortic-wall inflammatory markers. These salutary effects were attributed selectively to the 17-βE and/or ω-3 polyunsaturated fatty acid components of the nano-delivery system. At therapeutic doses, the 17-βE-loaded, CREKA-peptide modified nanoemulsion system appeared to be biocompatible in that it elicited no apparent adverse/toxic effects, as indexed by body weight, plasma alanine aminotransferase/aspartate aminotransferase levels, and liver and kidney histopathology. The study demonstrates the therapeutic potential of a novel, 17-βE-loaded, CREKA-peptide-modified nanoemulsion system against atherosclerosis in a multimodal fashion by reducing lesion size, lowering the levels of circulating plasma lipids and decreasing the gene expression of inflammatory markers associated with the disease.