The induction of the CO2 concentrating mechanism in a starch-less mutant of Chlamydomonas reinhardtii

In Chlamydomonas reinhardtii the formation of a starch sheath surrounding the pyrenoid is observed when cells grown under high CO₂ (5% CO₂ in air) are transferred to low CO₂ (0.03%) conditions. Formation of the starch sheath occurs coincidentally with induction of the CO₂ concentrating mechanism and with de novo synthesis of 5 polypeptides with molecular masses of 21, 36, 37, 42–44 kDa. We studied the effect of CO₂ concentrations on photosynthesis, ultrastructure and protein synthesis in Chlamydomonas reinhardtii cw-15 (wild phenotype for photosynthesis) and in the starch-less mutant BAFJ -6, with the aim to clarify the role of the pyrenoid starch sheath in the operation of the CO₂ concentrating mechanism and whether these low CO₂-inducible polypeptides are involved in the formation of starch sheath. When wild type and starch-less mutant cells were transferred from high to low CO₂, the CO₂ requirement for half-maximal rates of photosynthesis decreased from 40 μM to 2 μM CO₂. ³⁵SO₄^2- labeling analyses showed that the starch-less mutant induced the 5 low CO₂-inducible polypeptides. These observations suggest that the starch-less mutant was able to induce a fully active CO₂ concentrating mechanism. Since the starch-less mutant did not form a pyrenoid starch sheath, we suggest that the starch sheath is not involved in the operation of the CO₂ concentrating mechanism and that none of these 5 low CO₂-inducible proteins is involved in the formation of the starch sheath in Chlamydomonas .     

Purification of a phi-type glutathione S-transferase from pumpkin flowers,and molecular cloning of its cDNA

A major species of glutathione S-transferase (GST), Pugf, was highly purified from pumpkin flowers. Two-dimensional electrophoresis of the purified enzyme gave two adjacent protein spots. The specific activity of the purified enzyme was 2.4 micromol min(-1) mg(-1) protein for 1-chloro-2,4-dinitrobenzene. This value is one to two orders of magnitude lower than that of pumpkin tau-type GSTs. The expression pattern of Pugf in healthy pumpkin plants and responses to various stresses were examined by western blotting. Pugf was found in high concentrations in petioles, stems, and roots as well as flowers, and was more abundant in expanding young organs than in fully expanded mature organs. Dehydration caused a slight increase in its concentration, but high and low temperatures, salty stress, and 2,4-dichlorophenoxyacetic acid seemed to have no effects. A cDNA encoding Pugf was cloned and sequenced. Sequence comparison with other plant GSTs suggested that it should be classified as a phi-type GST.     

Effect of external CO2 concentrations on protein synthesis in the green algae Scenedesmus obliquus (Turp.) Kütz and Chlorella vulgaris (Kosikov)

Unicellular algae grown under low-CO₂ conditions (0.03% CO₂) have developed a means of concentrating CO₂ at the site of ribulose-1,5-bisphosphate carboxylase/oxygenase. Cells with the CO₂-concentrating mechanism (CCM) acquire the ability to accumulate inorganic carbon to a level higher than that obtained by simple diffusion. To identify proteins which are involved in the organization of the CCM, cells of Scenedesumus obliquus and Chlorella vulgaris grown in high CO₂ (5% CO₂ in air) were transferred to low-CO₂ (0.03%) conditions in the presence of ³⁵SO _inf4 ^sup2? and, thereafter, polypeptides labeled with ³⁵S were detected. Under low-CO₂ conditions the inducton of 36-, 39-, 94- and 110- to 116kDa polypeptides were particularly observed in S. obliquus and 16-, 19-, 27-, 36-, 38- and 45-kDa polypeptides were induced in C. vulgaris. Western blots with antibodies raised against 37-kDa subunits of the periplasmic carbonic anhydrase (CA) of Chlamydomonas reinhardtii showed immunoreactive bands with the 39-kDa polypeptide in the whole-cell homogenates from S. obliquus and with 36 and 38-kDa polypeptides in both high- and low-CO₂grown cells of C. vulgaris. Anti-pea-chloroplast CA antibodies cross-reacted with a single polypeptide of 30 kDa in the whole-cell homogenates but not with thylakoid membranes. The CA activity was associated with soluble and membrane-bound fractions, except thylakoid membranes.     

Structure, physical, chemical and photophysical properties of Pt(bph) (CO)2, where bph is the biphenyl dianion

The complex Pt(bph) (CO)₂ crystallizes in the space group Cmcm with a = 18.647(6), B = 9.566(2) and C = 6.4060(5) Å. The geometry of the molecule is slightly distorted from square planar with a Pt---C(CO) bond distance of 1.98(2) Å and a Pt---C(bph) bond distance of 2.04(2) Å. The Pt(bph)(CO)₂ complex serves as a precursor for the preparation of a wide variety of Pt(bph)X₂ complexes, where X = monodentate ligands such as acetonitrile, pyridine, etc., and X₂ = bidentate ligands such as bypyridine, 1,10-phenanthroline, etc. In the solid state, the complex exhibits a green color, but when ground with an alkali metal salt turns deep blue to purple. In CH₂Cl₂, the color disappears but optical transitions are observed at 271 nm (2.7 × 10⁴ M⁻¹ cm⁻¹), 303 nm (1.1 × 10⁴ M⁻¹ cm⁻¹) and 330 nm (5.5 × 10³ M⁻¹ cm⁻¹). The complex is a weak emitter exhibiting a structured spectrum in CH₂Cl₂ at r.t. with maxima located at 562 and 594 nm and an emission lifetime of 3.1 μs when excited at 337 nm.     

Is health status of elderly worsening in India? A comparison of successive rounds of national sample survey data

The increasing greying of India's population raises concerns about the welfare and health status of the aged. One important source of information of health status of the elderly is the National Sample Survey Rounds on Morbidity and Health Care Expenditure. Using unit-level data for 1995-96 and 2004, this paper examines changes in reported health status of the elderly in India and analyses their relationship with living arrangements and extent of economic dependency. It appears that even after controlling for factors like caste, education, age, economic status and place of residence, there has been a deterioration in self-perceived current health status of the elderly. The paper argues that, although there have been changes in the economic condition and traditional living arrangements--with a decline in co-residential arrangements--this is not enough to explain the decline in reported health status and calls for a closer look at narratives of neglect being voiced in developing countries.     

Synthesis and characterization of superparamagnetic nanoparticles coated with carboxymethyl starch (CMS) for magnetic resonance imaging technique

Magnetic nanoparticles have been proposed for use as biomedical purposes to a large extent for several years. The development of techniques that could selectively deliver drug molecules to the diseased site, without a concurrent increase in its level in healthy tissues, is currently one of the most active areas of cancer research. The conjugate carboxymethyl starch (CMS)/SPIO nanoparticles were prepared by chemical reaction. Several parameters including the drug/polymer ratios in range of 1:14 were examined to optimize formulation. The size distribution and morphology of nanoparticles and in vitro release profile in phosphate buffer medium (pH 7.4) during 12 h were then investigated. The magnetic NPs prepared in this study were spherical with a relatively mono-dispersed size distribution. The conjugate carboxymethyl starch (CMS)/SPIO nanoparticles were exhaustively studied as controlled-release systems for parenteral administration of a model drug 5-aminosalicyclic acid (mesalamine) and analyzed using various release kinetic studies.     

Cholesterol Forms and Traditional Lipid Profile for Projection of Atherogenic Dyslipidemia: Lipoprotein Subfractions and Erythrocyte Membrane Cholesterol

Atherogenic dyslipidemia characterized by abnormal changes in plasma lipid profile such as low high-density lipoprotein (HDL) and increased triglyceride (TG) levels is strongly associated with atherosclerotic diseases. We aimed to evaluate the levels of pro- and antiatherogenic lipids and erythrocyte membrane cholesterol (EMC) content in normo- and dyslipidemic subjects to investigate whether EMC content could be a useful marker for clinical presentation of atherogenic dyslipidemia. Low-density lipoprotein (LDL), HDL and their subfraction levels and erythrocyte lipid content were determined in 64 normolipidemic (NLs), 42 hypercholesterolemic (HCs) and 42 mixed-type dyslipidemic subjects (MTDs). Plasma atherogenic lipid indices [small–dense LDL (sdLDL)/less-dense HDL (LHDL), TC/HDL-C, TG/HDL-C and Apo B/AI] were higher in MTDs compared to NLs (p < 0.001). The highest sdLDL level was observed in HCs (p < 0.01). Despite a slight increase in EMC level in dyslipidemic subgroups, the difference was not statistically significant. A significant negative correlation, however, was observed between EMC and sdLDL/LHDL in HCs (p < 0.035, r = ?0.386). Receiver operating characteristic curves to predict sdLDL level showed that TG and EMC levels had higher area under curve values compared to other parameters in HCs. We showed that diameters of larger LDL and HDL particles tend to shift toward smaller values in MTDs. Our results suggest that EMC content and TG levels may be a useful predictor for sdLDL level in hypercholesterolemic patients.