Band 3 protein of the red cell membrane of the llama: crosslinking and cleavage of the cytoplasmic domain

Comparative studies were done on the cytoplasmic domain of the band 3 protein in the red cell membranes of the the human and the llama. Two approaches were used: crosslinking with o-phenanthroline/CuSO4, and cleavage with 2-nitro-5-thiocyanobenzoate. o-Phenanthroline/CuSO4 crosslinks the band 3 polypeptide chains in the human; in contrast band 3 in the llama is minimally crosslinked by this agent. 2-Nitro-5-thiocyanobenzoate cleaves band 3 in the human into a 23,000-dalton fragment; a similar fragment is not generated from the llama band 3. These studies show that the cysteine residue located 23,000 daltons from the N-terminus of band 3 in the human involved in these reactions is unavailable for crosslinking and cleavage in the llama. Species differences in the cytoplasmic domain of band 3 may contribute to the unusual resistance of llama red cells to osmotic, chemical and physically-induced deformation.     

Remodeling the shape of the skeleton in the intact red cell.

The role of the membrane skeleton in determining the shape of the human red cell was probed by weakening it in situ with urea, a membrane-permeable perturbant of spectrin. Urea by itself did not alter the biconcave disk shape of the red cell; however, above threshold conditions (1.5 M, 37 degrees C, 10 min), it caused an 18% reduction in the membrane elastic shear modulus. It also potentiated the spiculation of cells by lysophosphatidylcholine. These findings suggest that the contour of the resting cell is not normally dependent on the elasticity of or tension in the membrane skeleton. Rather, the elasticity of the skeleton stabilizes membranes against deformation. Urea treatment also caused the projections induced both by micropipette aspiration and by lysophosphatidylcholine to become irreversible. Furthermore, urea converted the axisymmetric conical spicules induced by lysophosphatidylcholine into irregular, curved and knobby spicules; i.e., echinocytosis became acanthocytosis. Unlike controls, the ghosts and membrane skeletons obtained from urea-generated acanthocytes were imprinted with spicules. These data suggest that perturbing interprotein associations with urea in situ allowed the skeleton to evolve plastically to accommodate the contours imposed upon it by the overlying membrane.     

Application of nanomaterials in three-dimensional stem cell culture

Petri dish cultured cells have for long provided scientists an aperture to understanding cell's behavior both in normal and disease states as well as in vitro and in vivo. But recent advances have brought to light how the architecture and composite nature of the immediate environment within which the cell is proliferated can profoundly influence its phenotypic features and functions, thus making obvious, limitations of the conventional two-dimensional cell culture despite it cost effectiveness. Fortunately, the transition to three-dimensional (3D) cell culture has occurred concurrently with expanded knowledge of nanoscience and materials, thereby lending significant impetus for innovative research. This review is focused on the application of nanoparticles in 3D stem cell breeding, recent trends and developments in medical sciences for improved drug delivery, and treatment approaches to some human diseases. We also reviewed prevailing challenges and concerns of nanotoxicity as it continues to impede and delay clinical applications as well the ongoing concerted and multidisciplinary efforts to overcome them.     

Metabolic potential of lithifying cyanobacteria-dominated thrombolitic mats

Thrombolites are unlaminated carbonate deposits formed by the metabolic activities of microbial mats and can serve as potential models for understanding the molecular mechanisms underlying the formation of lithifying communities. To assess the metabolic complexity of these ecosystems, high throughput DNA sequencing of a thrombolitic mat metagenome was coupled with phenotypic microarray analysis. Functional protein analysis of the thrombolite community metagenome delineated several of the major metabolic pathways that influence carbonate mineralization including cyanobacterial photosynthesis, sulfate reduction, sulfide oxidation, and aerobic heterotrophy. Spatial profiling of metabolite utilization within the thrombolite-forming microbial mats suggested that the top 5 mm contained a more metabolically diverse and active community than the deeper within the mat. This study provides evidence that despite the lack of mineral layering within the clotted thrombolite structure there is a vertical gradient of metabolic activity within the thrombolitic mat community. This metagenomic profiling also serves as a foundation for examining the active role individual functional groups of microbes play in coordinating metabolisms that lead to mineralization.     

Alpha-2-adrenoceptor hyporesponsiveness in isolated tissues of cholestatic animals: involvement of opioid and nitric oxide systems

In the present study, the status of alpha(2)-adrenoceptors during cholestasis was investigated by the inhibitory effect of clonidine on the electrically stimulated contractions of mice vas deferens (MVD) and guinea pig ileum (GPI). Clonidine inhibited the contractions in both tissues in a dose-dependent manner. Compared to unoperated animals, there was a significant right-shift in the clonidine concentration-curves of both tissues obtained from 5-day bile-duct ligated (BDL) animals (p < 0.01), implying the hyporesponsiveness of alpha(2)-adrenoceptors during cholestasis. Chronic treatment with naltrexone (3 mg/kg/day) reversed the right-shift induced by cholestasis in both tissues. Administration of N(omega)-nitro-L-arginine methyl ester (20 mg/kg/day) also partially reversed cholestasis-induced effect on IC(50) of clonidine. These two treatments had no effect on IC(50) of tissues from controls. Chronic yohimbine treatment (5 mg/kg/day) recovered the effect of cholestasis on MVD, but sensitized the ileum of unoperated and BDL guinea pigs to clonidine to a similar extent, providing evidence for the role of the augmented adrenergic state of cholestasis in the hyporesponsiveness of norepinephrine-releasing neurons of MVD. We concluded that cholestasis is associated with the decreased responsiveness of alpha(2)-adrenoceptors and the cholestasis-associated augmented opioidergic tone and increased NO production contribute to this process.     

Lavandula angustifolia essential oil as a novel and promising natural candidate for tick (Rhipicephalus (Boophilus) annulatus) control

Lavandula angustifolia is a well known herbal medicine with a variety of useful properties, including its acaricidal effect. This experiment was carried out to study the bioacaricidal activity of L. angustifolia essential oil (EO) against engorged Rhipicephalus (Boophilus) annulatus (Acari; Ixodidae) females. For this purpose six serial concentrations (0.5, 1.0, 2.0, 4.0, 6.0 and 8.0% w/v) of L. angustifolia EO were used. There was considerable mortality in concentrations more than 4.0% although there were no differences between 6.0 and 8.0% in all measured criteria. The mortality rate 24 h after inoculation was 73.26 and 100% in groups treated with 4.0 and 8.0% EO, respectively. Lavender EO also reduced tick egg weight in a concentration-dependent manner. The amount of eggs produced varied from 0.12 g (at 0.5% EO) to 0.00 g (at 8.0% EO) but did not differ statistically from the control. L. angustifolia EO caused 100% failure in egg laying at 6.0 and 8.0% whereas this value in the control group was zero. A positive correlation between L. angustifolia EO concentration and tick control, assessed by relative mortality rate and egg-laying weight, was observed by the EO LC/EC₅₀, which, when calculated using the Probit test, was 2.76-fold higher than the control. Lavender is a promising acaricidal against R. (B.) annulatusin vitro.     

Fine structure of the band 3 protein in human red cell membranes: Freeze-fracture studies

The major red cell membrane protein, band 3, is a glycoprotein which extends across the membrane from the extracellular space into the cytoplasmic compartment. It is widely held that band 3 is a component of the intramembrane particles (IMP) which can be demonstrated by freeze-fracture electron microscopy. In this study, we find that the outer surface poles of the IMP can be seen by freeze-etching after they are unmasked by proteolysis under conditions which excise the surrounding sialopeptides from the membrane. The poles appear as distinctive projections, 30–50 Å in diameter, the “ES particles.” The ES particles remain associated with the outer surface of the membrane following cleavage of the band 3 polypeptide by chymotrypsin or pronase. This is consistent with previous biochemical studies which have shown that the 38,000-dalton outer surface segment of band 3 is intercalated in the lipid bilayer. A granulofibrillar component at the inner surface of the membrane is provisonally identified as the 40,000-dalton inner-surface domain of band 3.