Evidence for African origins of founders of the asiatic lion species survival plan

The Asiatic lion (Panthera leo persica) exists in the wild as a single relict population of approximately 250 individuals in the protected Gir Forest Sanctuary in western India. In 1981, a species survival plan (SSP) for the Asiatic lion was established by the American Association of Zoological Parks and Aquariums to manage the 200 + descendants of Asiatic lions in captivity in western zoological facilities. This captive population was derived from seven founders. In order to compare the genetic structure of the Gir Forest population with that of the captive SSP population, a genetic survey of 46 electrophoretic allozyme systems resolved from extracts of lion blood was undertaken by using 29 SSP Asiatic lions and 28 wild-caught or captive-bred lions maintained at the Sakkarbaug Zoo in India but originally derived from the Gir Forest. The Gir lion population was found to be genetically monomorphic at each of 46 allozyme loci. This was in contrast to several African lion (Panthera leo leo) populations, which show moderate levels of allozyme variation at the same loci. The SSP lion population was polymorphic at three allozyme loci (IDHI, TF, and PTI) for alleles that were previously found only in African lion populations. Pedigree analysis of the genetic transmission of these three biochemical loci demonstrated that two of the five primary founder animals of the SSP Asiatic lion population (a breeding pair originally imported from the Trivandrum Zoo in southern India) were descendants of the African subspecies. Three other founder animals were pure Asian. A retrospective SSP pedigree analysis of two morphologic characters (prominent abdominal fold and pairing of infraorbital foramen) that are partially diagnostic for persica vs leo was consistent with this conclusion as well. The implications for the management of small captive populations of threatened species and of the Asiatic lion SSP population are discussed.     

Effect of phosphate supplementation on oxygen delivery at high altitude

In the present communication, effect of low doses of phosphate supplementation on short-term high altitude adaptation has been examined. Studies were carried out in 36 healthy, male, sea-level residents divided in a double blind fashion into drug and placebo treated groups. 3.2 mmol of phosphate were given orally to each subject of the drug treated group once a day for 4 days on arrival at an altitude of 3,500 m. Sequential studies were done in the subjects in both groups on the 3rd, 7th, 14th and 21st day of their altitude stay. Haemoglobin, haematocrit, erythrocyte and reticulocyte counts increased to the similar extent in both groups. Blood pH, pO₂ and adenosine tri-phosphate (ATP) did not differ between the two groups. On 3rd day of the altitude stay, inorganic phosphate and 2,3-diphosphoglycerate (2,3 DPG) levels in the drug treated group increased significantly as compared to the placebo group. No significant difference in inorganic phosphate and 2,3 DPG was observed later on in the two groups. Psychological and clinical tests also indicated that the drug treated subjects felt better as compared to the placebo treated subjects. The present study suggests that low doses of phosphate increases circulating 2,3-DPG concentration which in turn brings about beneficial effect towards short term high altitude adaptation.     

Phylogenetic distribution in the genus Mus of t-complex-specific DNA and protein markers: inferences on the origin of t-haplotypes

We have examined the phylogenetic distribution of two t-specific markers among representatives of various taxa belonging to the genus Mus. The centromeric TCP-1a marker (a testicular protein variant specific for all t-haplotypes so far studied) has also been apparently detected in several non-t representatives of the Mus IVA, Mus IVB, and probably M. cervicolor species. By contrast, a t-specific restriction- fragment-length polymorphism allele (RFLP) of the telomeric alpha- globin pseudogene DNA marker alpha-psi-4 was found only in animals belonging to the M. musculus-complex species either bearing genuine t- haplotypes or, like the M. m. bactrianus specimen studied here, likely to do so. This t-specific alpha-psi-4 RFLP allele was found to be as divergent from the RFLP alleles of the latter, non-t, taxonomical groups as it is from Mus 4A, Mus 4B, or M. spretus ones. These results suggest the presence of t-haplotypes and of t-specific markers in populations other than those belonging to the M. m. domesticus and M. m. musculus subspecies, implying a possible origin for t-haplotypes prior to the radiation of the most recent offshoot of the Mus genus (i.e., the spretus/domesticus divergence), some 1-3 Myr ago.      

The contractile basis of amoeboid movement: V. The control of gelation, solation, and contraction in extracts from dictyostelium discoideum

Motile extracts have been prepared from Dictyostelium discoideum by homogenization and differential centrifugation at 4 degrees C in a stabilization solution (60). These extracts gelled on warming to 25 degrees Celsius and contracted in response to micromolar Ca++ or a pH in excess of 7.0. Optimal gelation occurred in a solution containing 2.5 mM ethylene glycol-bis (β-aminoethyl ether)N,N,N',N'-tetraacetate (EGTA), 2.5 mM piperazine-N-N'-bis [2-ethane sulfonic acid] (PIPES), 1 mM MgC1(2), 1 mM ATP, and 20 mM KCI at ph 7.0 (relaxation solution), while micromolar levels of Ca++ inhibited gelation. Conditions that solated the gel elicited contraction of extracts containing myosin. This was true regardless of whether chemical (micromolar Ca++, pH >7.0, cytochalasin B, elevated concentrations of KCI, MgC1(2), and sucrose) or physical (pressure, mechanical stress, and cold) means were used to induce solation. Myosin was definitely required for contraction. During Ca++-or pH-elicited contraction: (a) actin, myosin, and a 95,000-dalton polypeptide were concentrated in the contracted extract; (b) the gelation activity was recovered in the material sqeezed out the contracting extract;(c) electron microscopy demonstrated that the number of free, recognizable F-actin filaments increased; (d) the actomyosin MgATPase activity was stimulated by 4- to 10-fold. In the absense of myosin the Dictyostelium extract did not contract, while gelation proceeded normally. During solation of the gel in the absense of myosin: (a) electron microscopy demonstrated that the number of free, recognizable F- actin filaments increased; (b) solation-dependent contraction of the extract and the Ca++-stimulated MgATPase activity were reconstituted by adding puried Dictyostelium myosin. Actin purified from the Dictyostelium extract did not gel (at 2 mg/ml), while low concentrations of actin (0.7-2 mg/ml) that contained several contaminating components underwent rapid Ca++ regulated gelation. These results indicated : (a) gelation in Dictyostelium extracts involves a specific Ca++-sensitive interaction between actin and several other components; (b) myosin is an absolute requirement for contraction of the extract; (c) actin-myosin interactions capable of producing force for movement are prevented in the gel, while solation of the gel by either physical or chemical means results in the release of F-actin capable of interaction with myosin and subsequent contraction. The effectiveness of physical agents in producting contraction suggests that the regulation of contraction by the gel is structural in nature.     

Glucagon-stimulated adenylate cyclase detects a selective perturbation of the inner half of the liver plasma-membrane bilayer achieved by the local anaesthetic prilocaine.

Prilocaine can increase the fluidity of rat liver plasma membranes, as indicated by a fatty acid spin-probe. This led to the activation of the membrane-bound fluoride-stimulated adenylate cyclase activity, but not the Lubrol-solubilized activity, suggesting that increased lipid fluidity can activate the enzyme. With increasing prilocaine concentrations above 10 mM, the membrane-bound fluoride-stimulated activity was progressively inhibited, even though bilayer fluidity continued to increase and the activity of the solubilized enzyme remained unaffected. Glucagon-stimulated adenylate cyclase was progressively inhibited by increasing prilocaine concentrations. Prilocaine (10 mM) had no effect on the lipid phase separation occurring at 28 degrees C and attributed to those lipids in the external half of the bilayer, as indicated by Arrhenius plots of both glucagon-stimulated adenylate cyclase activity and the order parameter of a fatty acid spin-probe. However, 10 mM-prilocaine induced a lipid phase separation at around 11 degrees C that was attributed to the lipids of the internal (cytosol-facing) half of the bilayer. It is suggested that prilocaine (10 mM) can selectively perturb the inner half of the bilayer of rat liver plasma membranes owing to its preferential interaction with the acidic phospholipids residing there.     

Roles of creatine in the regulation of cardiac protein synthesis

The observation that increased muscular activity leads to muscle hypertrophy is well known, but identification of the biochemical and physiological mechanisms by which this occurs remains an important problem. Experiments have been described (5, 6) which suggest that creatine, an end product of contraction, is involved in the control of contractile protein synthesis in differentiating skeletal muscle cells and may be the chemical signal coupling increased muscular activity and the increased muscular mass. During contraction, the creatine concentration in muscle transiently increases as creatine phosphate is hydrolyzed to regenerate ATP. In isometric contraction in skeletal muscle for example, Edwards and colleagues (3) have found that nearly all of the creatine phosphate is hydrolyzed. In this case, the creatine concentration is increased about twofold, and it is this transient change in creatine concentration which is postulated to lead to increased contractile protein synthesis. If creatine is found in several intracellular compartments, as suggested by Lee and Vissher (7), local changes in concentration may be greater then twofold. A specific effect on contractile protein synthesis seems reasonable in light of the work of Rabinowitz (13) and of Page et al. (11), among others, showing disproportionate accumulation of myofibrillar and mitochondrial proteins in response to work-induced hypertrophy and thyroxin-stimulated growth. Previous experiments (5, 6) have shown that skeletal muscles cells which have differentiated in vitro or in vivo synthesize myosin heavy-chain and actin, the major myofibrillar polypeptides, faster when supplied creatine in vitro. The stimulation is specific for contractile protein synthesis since neither the rate of myosin turnover nor the rates of synthesis of noncontractile protein and DNA are affected by creatine. The experiments reported in this communication were undertaken to test whether creatine selectively stimulates contractile protein synthesis in heart as it does in skeletal muscle.     

Transbilayer movement of Glc-P-dolichol and its function as a glucosyl donor: protein-mediated transport of a water-soluble analog into sealed ER vesicles from pig brain

The results described in the accompanying article support the model in which glucosylphosphoryldolichol (Glc-P-Dol) is synthesized on the cytoplasmic face of the ER, and functions as a glucosyl donor for three Glc-P-Dol:Glc0-2Man9-GlcNAc2-P-P-Dol glucosyltransferases (GlcTases) in the lumenal compartment. In this study, the enzymatic synthesis and structural characterization by NMR and electrospray-ionization tandem mass spectrometry of a series of water-soluble beta-Glc-P-Dol analogs containing 2-4 isoprene units with either the cis - or trans - stereoconfiguration in the beta-position are described. The water- soluble analogs were (1) used to examine the stereospecificity of the Glc-P-Dol:Glc0-2Man9GlcNAc2-P-P-Dol glucosyltransferases (GlcTases) and (2) tested as potential substrates for a membrane protein(s) mediating the transbilayer movement of Glc-P-Dol in sealed ER vesicles from rat liver and pig brain. The Glc-P-Dol-mediated GlcTases in pig brain microsomes utilized [3H]Glc-labeled Glc-P-Dol10, Glc-P-(omega, c )Dol15, Glc-P(omega, t,t )Dol20, and Glc-P-(omega, t,c )Dol20as glucosyl donors with [3H]Glc3Man9GlcNAc2-P-P-Dol the major product labeled in vitro. A preference was exhibited for C15-20 substrates containing an internal cis -isoprene unit in the beta-position. In addition, the water-soluble analog, Glc-P-Dol10, was shown to enter the lumenal compartment of sealed microsomal vesicles from rat liver and pig brain via a protein-mediated transport system enriched in the ER. The properties of the ER transport system have been characterized. Glc- P-Dol10was not transported into or adsorbed by synthetic PC-liposomes or bovine erythrocytes. The results of these studies indicate that (1) the internal cis -isoprene units are important for the utilization of Glc-P-Dol as a glucosyl donor and (2) the transport of the water- soluble analog may provide an experimental approach to assay the hypothetical "flippase" proposed to mediate the transbilayer movement of Glc-P-Dol from the cytoplasmic face of the ER to the lumenal monolayer.      

An amperometric biosensor based on laccase immobilized onto MnO2NPs/cMWCNT/PANI modified Au electrode

A method is described for construction of an amperometric biosensor for detection of phenolic compounds based on covalent immobilization of laccase (Lac) onto manganese dioxide nanoparticles (MnO(2)NPs) decorated carboxylated multiwalled carbon nanotubes (cMWCNTs)/PANI composite electrodeposited onto a gold (Au) electrode through N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) chemistry. The modified electrode was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The biosensor showed optimum response at pH 5.5 (0.1M sodium acetate buffer) and 35°C, when operated at 0.3 V vs. Ag/AgCl. Linear range, response time, detection limit were 0.1-10 μM (lower concentration range) and 10-500 μM (higher concentration range), 4s and 0.04 μM, respectively. Biosensor measured total phenolic content in tea leaves extract. The enzyme electrode was used 150 times over a period of 5 months.