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81.
Mahdavi A Sajedi RH Asghari SM Taghdir M Rassa M 《International journal of biological macromolecules》2011,49(5):1038-1045
A comparative biochemical and structural study was performed on a cold active α-amylase from Bacillus cereus (BCA) and two well-known homologous mesophilic and thermophilic α-amylases from Bacillus amyloliquefaciens (BAA) and Bacillus licheniformis (BLA). In spite of a high degree of sequence and structural similarity, drastic variations were found for Topt as 50, 70 and 90 °C for BCA, BAA and BLA, respectively. The half-lives of thermoinactivation were 1 and 9 min for BCA and BAA at 80 °C respectively, whilst there was no inactivation for BLA at this temperature. Thermodynamic studies on inactivation process suggested that lower thermostability of BCA is due to lower inactivation slope of the Arrhenius plots and subsequently, lower Ea and ΔH#. Increased Km and accessible surface area for catalytic residues along with a decreased number of internal interactions in this region in BCA compared to BLA suggest that BCA substrate-binding site might be temperature sensitive and is probably more flexible. On the other hand, fewer ion pairs, destructive substitutions and disruption of aromatic interaction networks in structurally critical regions of Bacillus α-amylases result in a severe decrease in BCA thermostability compared to its mesophilic and thermophilic homologues. 相似文献
82.
83.
Moeini MM Kiani A Mikaeili E Shabankareh HK 《Biological trace element research》2011,144(1-3):529-537
Forty heifers at the late stage of gestation were randomly assigned into five groups. Heifers were balanced for age, weight, and time of calving in each group. Four and 2?weeks before expected time of calving, the heifers were injected with 0?ml (C), 10?ml (T1), 20?ml (T2), 30?ml (T3), and 40?ml (T4) Se and VE supplements, respectively. Each milliliter of the supplement contained of 0.5?mg Se as sodium selenite and 50?IU of dl-alpha-tocopheryl acetate. Blood samples were collected from the heifers 4?weeks before expected calving and at calving day and from the calves at birth and 7?days of age. The serum Se and immunoglobulin G (IgG) concentrations, white blood cell and differential leukocyte counts were measured. The Se concentrations in the sera of the heifers before the injections of Se and VE supplements were the same among the groups (P?>?0.05), but after calving were significantly increased in the treated heifers (P?0.05). Similarly, the serum Se levels of calves of the treated heifers were higher (P?0.05). The Se concentrations in the colostrums of the heifers were affected by treatments (P?0.05). Colostrum and daily milk productions at 8-week lactation were increased in treated heifers compared with the controls (P?0.05). Likewise, the milk somatic cell counts decreased in the treated heifers compared with the controls. The changes of the mean serum IgG levels did not differ among calves (P?>?0.05). The white blood cell counts were higher in calves of heifers in groups T3 and T4 compared with the control group at 7?days of age (P?0.05). 相似文献
84.
Nageshwar YV Sheelu G Shambhu RR Muluka H Mehdi N Malik MS Kamal A 《Bioprocess and biosystems engineering》2011,34(5):515-523
Microbial nitrilases are biocatalysts of interest and the enzyme produced using various inducers exhibits altered substrate
specificity, which is of great interest in bioprocess development. The aim of the present study is to investigate the nitrilase-producing
Alcaligenes faecalis MTCC 10757 (IICT-A3) for its ability to transform various nitriles in the presence of different inducers after optimization
of various parameters for maximum enzyme production and activity. The production of A. faecalis MTCC 10757 (IICT-A3) nitrilase was optimum with glucose (1.0%), acrylonitrile (0.1%) at pH 7.0. The nitrilase activity of
A. faecalis MTCC 10757 (IICT-A3) was optimum at 35 °C, pH 8.0 and the enzyme was stable up to 6 h at 50 °C. The nitrilase enzyme produced
using different inducers was investigated for substrate specificity. The enzyme hydrolyzed aliphatic, heterocyclic and aromatic
nitriles with different substitutions. Acrylonitrile was the most preferred substrate (~40 U) as well as inducer. Benzonitrile
was hydrolyzed with almost twofold higher relative activity than acrylonitrile when it was used as an inducer. The versatile
nitrilase-producing A. faecalis MTCC 10757 (IICT-A3) exhibits efficient conversion of both aliphatic and aromatic nitriles. The aromatic nitriles, which
show not much or no affinity towards nitrilase from A. faecalis, are hydrolyzed effectively with this nitrilase-producing organism. Studies are in progress to exploit this organism for
synthesis of industrially important compounds. 相似文献
85.
A total of 250 broilers in a completely randomized design selected to evaluate the effect of different levels of chromium (Cr) supplementation on performance, carcass traits and some blood parameters of heat-stressed broiler chicks. All birds were kept under heat stress temperature (33?±?3°C) and divided into five treatments groups. Each treatment consisted of five pens with 10 birds in each pen. The basal diets were supplemented with 0?ppb (control), 800?ppb Cr-L-Met (T(1)), 1,200?ppb Cr-L-Met (T(2)) or 800?ppb CrCl(3) (T(3)), and 1,200?ppb CrCl(3) (T(4)). The feed intake and body mass were measured at 10, 21, and 42?days of age. Blood samples were collected from two birds in each replicates to determine biological and hematological values at 28 and 42?days of age. There were no significant difference in mass gain and feed conversion of broilers that received Cr supplementations compared with controls. The serum glucose concentration decreased in broilers received organic chromium methionine supplements compared with other treatments groups. Slight but not significant increases were observed in serum high-density lipoprotein (HDL) concentration of treated groups than controls while the mean serum HDL concentration was significantly higher in T(2) group compared with control group. Serum low-density lipoprotein level decreased in broiler received organic Cr supplements (p?0.05). 相似文献
86.
Manoj K. Pandey Subash C. Gupta Deepkamal Karelia Patrick J. Gilhooley Mehdi Shakibaei Bharat B. Aggarwal 《Biotechnology advances》2018,36(6):1633-1648
Bone loss or osteoporosis, is a slow-progressing disease that results from dysregulation of pro-inflammatory cytokines. The FDA has approved number of drugs for bone loss prevention, nonetheless all are expensive and have multiple side effects. The nutraceuticals identified from dietary agents such as butein, cardamonin, coronarin D curcumin, diosgenin, embelin, gambogic acid, genistein, plumbagin, quercetin, reseveratrol, zerumbone and more, can modulate cell signaling pathways and reverse/slow down osteoporosis. Most of these nutraceuticals are inexpensive; show no side effect while still possessing anti-inflammatory properties. This review provides various mechanisms of osteoporosis and how nutraceuticals can potentially prevent the bone loss. 相似文献
87.
Global change‐driven effects on dissolved organic matter composition: Implications for food webs of northern lakes 下载免费PDF全文
Irena F. Creed Ann‐Kristin Bergström Charles G. Trick Nancy B. Grimm Dag O. Hessen Jan Karlsson Karen A. Kidd Emma Kritzberg Diane M. McKnight Erika C. Freeman Oscar E. Senar Agneta Andersson Jenny Ask Martin Berggren Mehdi Cherif Reiner Giesler Erin R. Hotchkiss Pirkko Kortelainen Monica M. Palta Tobias Vrede Gesa A. Weyhenmeyer 《Global Change Biology》2018,24(8):3692-3714
Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial–aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)—the messenger between terrestrial and lake ecosystems—with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change‐driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice‐out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans. 相似文献
88.
Mehdi Rezaee Behzad Behnam Maciej Banach Amirhossein Sahebkar 《Biotechnology advances》2018,36(8):2232-2247
With unique characteristics such as high surface area, capacity of various functionalization, low weight, high conductivity, thermal and chemical stability, and free radical scavenging, carbon nanomaterials (CNMs) such as carbon nanotubes (CNTs), fullerene, graphene (oxide), carbon nanohorns (CNHs), and their derivatives have increasingly been utilized in nanomedicine and biomedicine. On the one hand, owing to ever-increasing applications of CNMs in technological and industrial fields as well as presence of combustion-derived CNMs in the ambient air, the skepticism has risen over the adverse effects of CNMs on human being. The influences of CNMs on cardiovascular system and cardiovascular diseases (CVDs) such as atherosclerosis, of which consequences are ischemic heart disease and ischemic stroke, as the main causes of death, is of paramount importance. In this regard, several studies have been devoted to specify the biomedical applications and cardiovascular toxicity of CNMs. Therefore, the aim of this review is to specify the roles and applications of various CNMs in atherosclerosis, and also identify the key role playing parameters in cardiovascular toxicity of CNMs so as to be a clue for prospective deployment of CNMs. 相似文献
89.
Abuzar Hashempour Mahmood Ghasemnezhad Reza Fotouhi Ghazvini Mohammad Mehdi Sohani 《Acta Physiologiae Plantarum》2014,36(12):3231-3241
The changes in the antioxidant enzymes activity, total protein and proline content and their correlations with freezing tolerance (FT) (expressed as LT50) were investigated at 11 different olive cultivars at cold-acclimation (CA, in February) and non-acclimation (NA, in August) stages. Leaf samples were collected from each cultivar and were divided into two groups. The first group was immediately frozen in liquid nitrogen for further biochemical analysis. The second ones was subjected to different freezing temperatures (?5, ?10, ?15 and ?20 °C) for 10 h, in order to determine their FT. The unfrozen control samples were kept at 4 °C. The results showed that Fishomi, Mission and Shengeh were the most freezing tolerant among other cultivars. In contrast, Zard, Manzanilla and Amigdalolia were the most sensitive ones. The cold acclimation enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), polyphenol oxidase (PPO) and total protein content. However, proline content and phenylalanine ammonia-lyase (PAL) activity did not change or even decreased slightly at CA stage, compare to those samples at NA stage. It was found that LT50 to be closely correlated to POD, CAT, and PPO activity at CA and NA stages. Overall, higher leaf POD, CAT, and PPO activity could be used as important selection criteria in screening tolerant olive cultivars for cold zone climatic. 相似文献
90.
Mark T. Gladwin Robyn J. Barst J. Simon R. Gibbs Mariana Hildesheim Vandana Sachdev Mehdi Nouraie Kathryn L. Hassell Jane A. Little Dean E. Schraufnagel Lakshmanan Krishnamurti Enrico Novelli Reda E. Girgis Claudia R. Morris Erika Berman Rosenzweig David B. Badesch Sophie Lanzkron Oswaldo L. Castro James G. Taylor VI Jonathan C. Goldsmith Gregory J. Kato Victor R. Gordeuk Roberto F. Machado 《PloS one》2014,9(7)