Solvent tuning of electrochemical potentials in the active sites of HiPIP versus ferredoxin     

Dey A  Jenney FE  Adams MW  Babini E  Takahashi Y  Fukuyama K  Hodgson KO  Hedman B  Solomon EI 《Science (New York, N.Y.)》2007,318(5855):1464-1468

A persistent puzzle in the field of biological electron transfer is the conserved iron-sulfur cluster motif in both high potential iron-sulfur protein (HiPIP) and ferredoxin (Fd) active sites. Despite this structural similarity, HiPIPs react oxidatively at physiological potentials, whereas Fds are reduced. Sulfur K-edge x-ray absorption spectroscopy uncovers the substantial influence of hydration on this variation in reactivity. Fe-S covalency is much lower in natively hydrated Fd active sites than in HiPIPs but increases upon water removal; similarly, HiPIP covalency decreases when unfolding exposes an otherwise hydrophobically shielded active site to water. Studies on model compounds and accompanying density functional theory calculations support a correlation of Fe-S covalency with ease of oxidation and therefore suggest that hydration accounts for most of the difference between Fd and HiPIP reduction potentials.  相似文献   

Deciphering the cross-talk of implantation: advances and challenges     

Paria BC  Reese J  Das SK  Dey SK 《Science (New York, N.Y.)》2002,296(5576):2185-2188

Implantation involves a series of steps leading to an effective reciprocal signaling between the blastocyst and the uterus. Except for a restricted period when ovarian hormones induce a uterine receptive phase, the uterus is an unfavorable environment for blastocyst implantation. Because species-specific variations in implantation strategies exist, these differences preclude the formulation of a unifying theme for the molecular basis of this event. However, an increased understanding of mammalian implantation has been gained through the use of the mouse model. This review summarizes recognized signaling cascades and new research in mammalian implantation, based primarily on available genetic and molecular evidence from implantation studies in the mouse. Although the identification of new molecules associated with implantation in various species provides valuable insight, important questions remain regarding the common molecular mechanisms that govern this process. Understanding the mechanisms of implantation promises to help alleviate infertility, enhance fetal health, and improve contraceptive design. The success of any species depends on its reproductive efficiency. For sexual reproduction, an egg and sperm must overcome many obstacles to fuse and co-mingle their genetic material at fertilization. The zygote develops into a blastocyst with two cell lineages (the inner cell mass and the trophectoderm), migrates within the reproductive tract, and ultimately implants into a transiently permissive host tissue, the uterus. However, the molecular basis of the road map connecting the blastocyst with the endometrium across species is diverse (1) and not fully understood. Recent advances have identified numerous molecules involved in implantation (1-4), yet new discoveries have not yielded a unifying scheme for the mechanisms of implantation.  相似文献   

Hydrous Ferric Oxide (HFO)—a Scavenger for Fluoride from Contaminated Water     

Dey  Soumen  Goswami  Saswati  Ghosh  Uday Chand 《Water, air, and soil pollution》2004,158(1):311-323

Groundwaters contaminated with excess fluoride (above 1.5 mg/L) posed some risks to the public health in India. Methods available for fluoride contaminated water treatment are cogaulation–filtration using alum + lime + bleaching powder (Nalgonda technique) and adsorption using activated alumina. Use of aluminium compounds for water treatment purpose needs replacement on neurological health problem. Objective to this, the synthesis and fluoride adsorption behavior of hydrous ferric oxide (HFO) are reported here. It is seen that fluoride adsorption density varies as a function of pH, contact time, aging time, drying temperature and particle size of HFO. Highest adsorption density for fluoride is found to be at pH 4.0. Effects of competing anions in removing fluoride from solution were tested. Arsenite, arsenate, phosphate and sulfate show strong interfering effect at high anions to fluoride molar ratio in solution. Adsorption of fluoride on HFO follows the Freundlich isotherm and the Lagergren first-order kinetic model. It was also determined that HFO is a better adsorbent in removing fluoride from high fluoride groundwater than some other adsorbents. Regeneration of fluoride-rich HFO results showed that 1.0 M NaOH solution could be used up to a maximum of 75% regeneration.  相似文献   

Observations on feeding of young grass carp on mosquito larvae     

S.B. Singh  R.K. Dey  P.V.G.K. Reddy 《Aquaculture (Amsterdam, Netherlands)》1977,12(4):361-363

Grass carp (Ctenopharyngodon idella Val.) is well known for its efficacy as a biological weed control agent. The young of the species were observed to feed avidly on mosquito larvae in the present set of experiments. The fish 98–185 mm in length appeared to be comparatively more voracious in feeding than the larger ones (220 mm). The larger grass carp (252 mm), common carp (95–105 mm) and silver carp (97–115 mm) did not feed on the larvae at all. Thus, the small grass carp are expected to exercise some control over the population of mosquitoes in a water body. The propensity of the fish to feed on vegetation is likely to ensure better access to the shallow areas where mosquitoes generally breed. The grass carp can be listed among the larvivorous fishes along with other cyprinids.  相似文献   

Trace elemental characterization of some food crustacean tissue samples by EDXRF technique     

Anil Mohapatra  T.R. Rautray  V. Vijayan  Rajeeb K. Mohanty  S.K. Dey 《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):552-558

The trace elemental analysis of two species of mud crab and three species of prawn samples from Chilika lagoon, Orissa, India has been carried out by using Energy Dispersive X-ray Fluorescence (EDXRF) technique available at Institute of Physics, Bhubaneswar. Elements namely K, Ca, Mn, Fe, Cu, Zn, Se, Br, Sr and Pb have been measured in the present investigation. The study indicates the effectiveness of the technique in analyzing biological materials like tissue samples and opens a door for easy analysis of seafood items with a easy, fast, sensitive, simultaneous multi-elemental technique with a simple sample preparation procedure without any chemical treatment. Though all the specimens were collected from the same environment of the lagoon the elemental variation might be due to the differential migration pattern and metabolism or other biological factors.  相似文献   

Disturbance of oxidant/antioxidant equilibrium in horses naturally infected with Trypanosoma evansi     

Ranjithkumar M  Kamili NM  Saxena A  Dan A  Dey S  Raut SS 《Veterinary parasitology》2011,180(3-4):349-353

Oxidant/antioxidant equilibrium disturbance has already been reported in trypanosome infections by several authors. The present study was aimed to explore the possible oxidant/antioxidant disturbance in surra of naturally infected horses before and after treatment. Fifteen naturally infected horses were chosen to analyse erythrocytic indices, platelet counts, lipid peroxides (LPO), nitric oxide (NO), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) while six healthy animals acted as control. There was a highly significant (P<0.001) reduction in red blood cell (RBC) count, haemoglobin (Hb), packed cell volume (PCV) and platelet levels and a significant reduction in mean corpuscular haemoglobin concentration (MCHC) (P<0.05) was noticed. A highly significant increase in NO (P<0.001), a significant increase in LPO (P<0.05) and a significant decrease in GSH, SOD and CAT (P<0.05) were found. A negative correlation of RBC count with LPO (r=-0.844) and nitrate (r=-0.702) while a positive correlation with GSH (r=0.489), SOD (r=0.580) and CAT (r=0.689) was observed. All the animals were treated with Quinapyramine sulphate (3mg/kg s.c.) only once. Nine animals recovered completely without any side effects. The recovered animals were monitored and samples were collected every seven days for up to 21 days and parameters were analysed. After treatment, a significant increase in haematological parameters was noticed whereas the oxidative indices varied without any statistical significance. To conclude, the increase in oxidant parameters and decrease in antioxidant enzymes in infected horses indicates the disturbance of oxidant/antioxidant indices. There was a significant increase in post therapy haematological values, while the oxidant/antioxidant indices changed insignificantly indicating that antioxidants might be supplemented in the therapeutic regimen.  相似文献   

Spatial pattern corrections and sample sizes for forest density estimates of historical tree surveys     

Brice B. Hanberry  Shawn Fraver  Hong S. He  Jian Yang  Dan C. Dey  Brian J. Palik 《Landscape Ecology》2011,26(1):59-68

The U.S. General Land Office land surveys document trees present during European settlement. However, use of these surveys for calculating historical forest density and other derived metrics is limited by uncertainty about the performance of plotless density estimators under a range of conditions. Therefore, we tested two plotless density estimators, developed by Morisita and Pollard, for two, three, and four trees per survey point under simulated ranges of tree densities, non-uniform densities, and different tree spatial distributions. Based on these results, we developed estimator corrections and determined number of survey points needed for reliable density estimates. The Morisita estimator was accurate for densities ranging from 5 to 1,000 trees per unit area, non-uniform densities, random and regular spatial distribution, and outperformed the Pollard estimator. Estimators using points with two or three trees did need a simple correction to account for overestimation. Likewise, for clustered distributions, depending on the number of trees per survey point and the amount of clustering, there should be adjustment for a range of under and overestimation. Sample sizes for survey points with three or four trees should be at least 200 survey points, and 1,000 survey points will have density estimates within ±10% tolerance range of actual density. For survey points with two trees, the minimum sample size should be 600 survey points, and 2,000 survey points should be the target value. These results provide guidelines for researchers to improve density estimates of historical forests.  相似文献   

Soil boron status: impact of lime and fertilizers in an Indian long-term field experiment on a Typic Paleustalf     

Abir Dey  Brahma S. Dwivedi  Siba P. Datta  Mahesh C. Meena  Binay K. Agarwal 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(1):54-62

In Indian agriculture, nitrogen (N) and phosphorus (P) fertilizers are predominantly used by the farmers, often ignoring secondary and micronutrients. Significance of boron (B) in nutrient management studies has been increasingly underlined under intensive cropping systems particularly in acid soils. In order to understand the distribution of soil native B in different fractions and their contribution to plant B uptake as influenced by nutrient management, soil samples collected after wheat (2009–2010) from a long-term experiment (LTE) continuing since 1972–1973 on Typic Paleustalf of Ranchi were subjected to sequential fractionation of soil B. Treatments included N alone, NP, NPK, 150% of recommended NPK, NPK + farmyard manure (FYM), NPK + lime, and an unfertilized-control. Five soil B fractions were determined along with hot CaCl₂-extractable (available) B. Averaged across the treatments, the soil had low organic carbon (C), pH and cation exchange capacity (CEC), and high free sesquioxides. Total B content was 21.7 mg kg^?1. Among different B fractions, residual B was the major contributor to total B and other fractions collectively shared 7% of total B only. Application of N alone depleted readily soluble, specifically adsorbed and organically bound B bringing the contents even below unfertilized-control. Conjoint use of lime or FYM with NPK increased significantly these fractions, whereas a decrease in oxide bound B was noticed under these treatments. Available B was positively correlated with these fractions indicating their significance in controlling B availability in the soil. The study revealed that use of lime or FYM helped modifying the distribution of soil B in different fractions by way of changing soil pH and organic C content, resulting in enrichment of plant available pool. A drastically low available B content in different treatments receiving fertilizers alone, however, suggested the necessity of B fertilization at prescribed rates for maintaining soil B fertility as also high crop yields.  相似文献   

Forest structure and woody plant species composition after a wildfire in beech forests in the north of Iran     

Mohammad Naghi Adel  Hassan Pourbabaei  Ali Omidi  Daniel C Dey 《林业研究》2013,24(2):255-262

Beech (Fagus orientalis Lipsky) forest covers about 565,000 ha of land in Guilan province, north of Iran and forms a major carbon pool. It is an important economic, soil protection and recreation resource. We studied long-term effects of fire on the structure and composition 37 years after fire occurrence in these forests. To do this research, we selected 85 ha burned and 85 ha unburned beech forests). The results indicated that the fire had not changed the overall uneven-aged structure, but it changed forest composition from pure stands to mixed stands that now include species such as Carpinus betulus, Acer cappadocicum and Alnus subcordata. The density of trees and regeneration was significantly increased, while the density of shrubs significantly decreased. The main reasons for increased tree regeneration were attributed to (1) reduction of litter depth, and (2) increase in available light from opening of the canopy and reduction in shrub competition. It is apparent that the forest is on a path to return to its natural state before the fire after 37 years.  相似文献   

Nitrogen,Phosphorus, and Carbon Budgets in Polyculture Ponds of Indian Major Carps and Giant Freshwater Prawn in Orissa State,India     

Bharat Chandra Sahu  Abhijit S. Mahapatra  Lambodar Dey 《Journal Of Applied Aquaculture》2013,25(4):365-376

A nutrient budget was quantified for six polyculture ponds of giant freshwater prawn (Macrobrachium rosenbergii) and Indian major carps (Catla catla, Labeo rohita, and Cirrhinus mrigala). The initial stocking size of prawn postlarva was 16.50 ± 0.54 mm with a body weight of 0.05 ± 0.001 g. Body weight of major carps was 9.0 ± 0.89 g. The duration of culture was 280 days. Feed accounted for 82% of total nitrogen (N), 93% of total phosphorus (P), and 95% of organic carbon (OC) inputs. Harvest of prawn and carps recovered 44% N, 1% P, and 19% OC. N, P, and OC accumulated in sediment were 47%, 73%, and 69%, respectively. Nutrient load in the harvest water was 0.67 ± 0.21 kg inorganic N, 0.15 ± 0.01 kg P, and 7.72 ± 0.62 kg OC per ton of Indian major carps and prawn.  相似文献