Phosphoinositides of sheep platelets plasma membranes.

Phospholipid composition of sheep blood platelets and its various plasma membrane fractions have been analyzed. Based on their flotation rates in discontinuous sucrose density gradient centrifugation, three membrane fractions were isolated. 5'-Nucelotidase and alkaline phosphatase were distributed nearly equally in all the three membrane fractions. However these membrane fractions showed differences in the distribution of phosphatidyl ethanolamine, phosphatidyl choline and phosphoinositides. Phosphatidyl ethanolamine was predominant in fraction I (11.05 micrograms PLP/mg protein) while phosphatidyl choline was predominant in fractions II and III (110.10 and 68.30 micrograms PLP/mg protein respectively). Phosphatidyl inositol (Ptd-InsP) was equally distributed in all three membrane fractions. However, both Ptd-InsP and phosphatidyl inositol 4,5-bisphosphate were about 4-fold higher in fraction II (73.55 and 89.89 micrograms PLP/mg protein respectively).     

Synthesis and properties of (6,7-dimethoxy-4-coumaryl)alanine: a fluorescent peptide label.

The synthesis of racemic and l-(6,7-dimethoxy-4-coumaryl)alanine (Dmca) is described and some spectral and physicochemical properties are reported. The utility of Dmca as a highly sensitive and specific label for the quantitative detection of synthetic peptides in HPLC and in minimal essential media (MEM) is also described.     

Electron-Acoustic Shock Waves in Cylindrical and Spherical Geometry with Non-Extensive Electrons

Plasma Physics Reports - We consider nonplanar electron acoustic shock waves composed of stationary ions, cold and non-extensive hot electrons under multiple temperature electrons model in...     

SO2‐catalyzed steam explosion: The effects of different severity on digestibility,accessibility, and crystallinity of lignocellulosic biomass

Lignocellulosic biomass is the most promising feedstock for biofuels production. To enhance the efficiency of enzymatic hydrolysis, lignocellulosics needs to be pretreated to lower their recalcitrance. SO₂‐catalyzed steam explosion is an efficient and relatively cost‐efficient pretreatment method for softwood. This work investigates the effects of steam explosion severity on the digestibility, accessibility, and crystallinity of Loblolly pine. Higher severity was found to increase the accessibility of the feedstock while also promoting nonselective degradation of carbohydrates. The adsorption behavior of Celluclast® enzymes on steam‐exploded Loblolly pine (SELP) can be described by a Langmuir isotherm. Cellulose crystallinity was found to first increase and then decrease with increasing pretreatment severity. A linear relationship between initial hydrolysis rates and crystallinity index (CrI) of pretreated Loblolly pine was found; moreover, a strong correlation between X‐ray diffraction intensities and initial rates was confirmed. The findings demonstrate the significance of CrI in enzymatic hydrolysis of pretreated lignocellulosic biomass. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:909–916, 2013     

Effect of Sodium Alginate Addition on Physical Properties of Rennet Milk Gels

Effect of addition of sodium alginate (alginate) to milk on the storage modulus (G′), water holding capacity (WHC) and hardness of rennet gels was evaluated as a function of alginate (0–0.25 g/100 g) and fat (0.5–3.0 g/100 g) concentrations. There was a significant effect of alginate addition on ionic calcium in milk and whey (Ca²⁺), and particle size distribution in alginate added milk. Results showed a positive correlation of alginate with WHC; negative correlation of alginate and positive correlation of fat with G′; and negative correlation of interaction of fat and alginate with gel hardness of rennet gels. Hence, the rennet gels with lower fat content and higher added alginate tended to be softer due to the high water holding capacity of the alginate particles.     

Metabolism of cyclophosphamide by purified cytochrome P-450 from microsomes of phenobarbital-treated rats

Incubation of [³H]-sidechain-labeled and [¹⁴C]-C(4)-ring-labeled cyclophosphamide (CPA) with purified cytochrome P-450 from liver microsomes of rats treated with phenobarbital resulted in the production of a major metabolite that contained both labels, was unaffected by diazomethane, possessed high polarity, was identical in TLC and HPLC behavior to a synthetic standard, didechlorodihydroxy-CPA, and was converted to CPA and bis(2-chloroethyl)amine by thionyl choloride. These results indicate that phenobarbital-inducible cytochrome P-450 is able to dechlorinate CPA and may account, in part, for the inability of phenobarbital to enhance the therapeutic activity and toxicity of this important anticancer and immunosuppressive agent.     

Prion metal interaction: Is prion pathogenesis a cause or a consequence of metal imbalance?

Functional role of cellular prion protein (PrPc) has been hypothesized to be in metal homeostasis and providing cells with a superoxide dismutase (SOD)-like activity to escape damage by reactive oxygen species (ROS). PrPc interacts with a range of divalent metal ions and undergoes Cu²⁺ as well as Zn²⁺-associated endocytosis, thereby maintaining homeostasis of these and other metal ions. Conformational change to a β-sheet rich, protease resistant entity, reminiscent of the disease-associated scrapie form called PrPsc, has been found to be induced by interaction of PrPc with metal ions like Cu²⁺, Zn²⁺, Mn²⁺ and Fe²⁺. This review compiles data from various experimental studies of the interaction of metals with PrPc. The effect of metal ions on the expression and conformation of the prion protein is described in detail with emphasis on their possible physiological and pathogenic role. Further, a hypothesis is presented where attainment of altered conformation by metal-bound PrPc has been viewed as a deleterious consequence of efforts made by cells to maintain metal homeostasis. Thus, PrPc presumably sacrifices itself by converting into PrPsc form in an attempt to protect cells from the toxicity of metal imbalance. Finally, possible reasons for contradictions reported in the literature on the subject are explored and experimental approaches to resolve the same are suggested.     

Evolutionary origins and diversification of proteobacterial mutualists

Mutualistic bacteria infect most eukaryotic species in nearly every biome. Nonetheless, two dilemmas remain unresolved about bacterial–eukaryote mutualisms: how do mutualist phenotypes originate in bacterial lineages and to what degree do mutualists traits drive or hinder bacterial diversification? Here, we reconstructed the phylogeny of the hyperdiverse phylum Proteobacteria to investigate the origins and evolutionary diversification of mutualistic bacterial phenotypes. Our ancestral state reconstructions (ASRs) inferred a range of 34–39 independent origins of mutualist phenotypes in Proteobacteria, revealing the surprising frequency with which host-beneficial traits have evolved in this phylum. We found proteobacterial mutualists to be more often derived from parasitic than from free-living ancestors, consistent with the untested paradigm that bacterial mutualists most often evolve from pathogens. Strikingly, we inferred that mutualists exhibit a negative net diversification rate (speciation minus extinction), which suggests that mutualism evolves primarily via transitions from other states rather than diversification within mutualist taxa. Moreover, our ASRs infer that proteobacterial mutualist lineages exhibit a paucity of reversals to parasitism or to free-living status. This evolutionary conservatism of mutualism is contrary to long-standing theory, which predicts that selection should often favour mutants in microbial mutualist populations that exploit or abandon more slowly evolving eukaryotic hosts.