Search results for "B vitamin"
showing 10 items of 54 documents
The origin of Lecithodesmus (Digenea: Campulidae) based on ND3 gene comparison
2000
Species of Lecithodesmus (Campulidae) occur almost exclusively in baleen whales throughout a wide geographical distribution. Other campulids occur only in odontocetes and, secondarily, in pinnipeds and the sea otter. Therefore, the ancestor of Lecithodesmus might have either cospeciated with mysticetes during the early divergence of mysticete and odontocete cetaceans or originated later via host switching. We evaluate both possibilities based on a phylogenetic analysis. The ND3 mitochondrial gene sequence of a species of Lecithodesmus was included in a previous partial molecular phylogeny of the Campulidae. Fasciola hepatica and Dicrocoelium dendriticum were used as outgroups. Maximum parsi…
Single amino acids in the lumenal loop domain influence the stability of the major light-harvesting chlorophyll a/b complex.
2004
The major light-harvesting complex of photosystem II (LHCIIb) is one of the most abundant integral membrane proteins. It greatly enhances the efficiency of photosynthesis in green plants by binding a large number of accessory pigments that absorb light energy and conduct it toward the photosynthetic reaction centers. Most of these pigments are associated with the three transmembrane and one amphiphilic alpha helices of the protein. Less is known about the significance of the loop domains connecting the alpha helices for pigment binding. Therefore, we randomly exchanged single amino acids in the lumenal loop domain of the bacterially expressed apoprotein Lhcb1 and then reconstituted the muta…
Refolding of the integral membrane protein light-harvesting complex II monitored by pulse EPR
2009
The major light-harvesting chlorophyll a / b complex (LHCII) of the photosynthetic apparatus in plants self-organizes in vitro. The recombinant apoprotein, denatured in dodecyl sulfate, spontaneously folds when it is mixed with its pigments, chlorophylls, and carotenoids in detergent solution, and assembles into structurally authentic LHCII in the course of several minutes. Pulse EPR techniques, specifically double-electron-electron resonance (DEER), have been used to analyze protein folding during this process. Pairs of nitroxide labels were introduced site-specifically into recombinant LHCII and shown not to affect the stability and function of the pigment-protein complex. Interspin dist…
Changes associated with aging and replicative senescence in the regulation of transcription factor nuclear factor-kappa B.
1996
Both the aging of animals and the senescence of cultured cells involve an altered pattern of gene expression, suggesting changes in transcription factor regulation. We studied age-related changes in transcription factors nuclear factor (NF)-kappa B, activator protein factor-1 (AP-1) and Sp-1 by using electrophoretic mobility shift binding assays; we also analysed changes in the protein components of NF-kappa B complex with Western blot assays. Nuclear and cytoplasmic extracts were prepared from heart, liver, kidney and brain of young adult and old NMRI mice and Wistar rats as well as from presenescent, senescent and simian virus 40-immortalized human WI-38 fibroblasts. Aging of both mice an…
Age-related changes in the regulation of transcription factor NF-kappa B in rat brain.
1997
Aging process involves an increase in stress at cellular level. We studied whether aging affects the regulation of stress responsive transcription factor NF-kappa B in brain samples of Wistar rats. Hippocampus, cerebellum, and temporal and frontal lobes of cortex were studied. We observed a significant up-regulation in the constitutive, nucleus-located NF-kappa B binding activity in 30-month-old Wistar rats compared to young and 18-month-old rats. The increase was most prominent in cerebellum and in frontal cortex, but age-related changes did not occur in hippocampus. Inducible, cytoplasmic NF-kappa B binding activity was not affected by aging in any of the samples studied. Western blot ass…
Folate, related B vitamins, and homocysteine in childhood and adolescence: potential implications for disease risk in later life.
2009
OBJECTIVES. Folate and the metabolically related B vitamins are an important priority throughout life, but few studies have examined their status through childhood and adolescence. The aims of the current study were to investigate age, gender, and lifestyle factors as determinants of folate, related B-vitamin status, and homocysteine concentrations among British children and adolescents and to propose age-specific reference ranges for these biomarkers, which, at present, are unavailable. PARTICIPANTS AND METHODS. Data from the National Dietary and Nutritional Survey of 2127 young people aged 4 to 18 years were accessed to provide a representative sample of British children. All of the subje…
Contents of vitamins B1, B2, B6, and B12 in pork and meat products
2001
The concentration of B vitamins (B(1), B(2), B(6), and B(12)) was determined in three pork muscles (Longissimus dorsi, loin; Biceps femoris, ham; and Triceps brachii, shoulder) and in pork and other meat products (cooked, pickled, and cured), of importance because they are consumed in high quantities. The results were compared with values reported by other authors and their contribution to the daily intake of these vitamins estimated. This showed that pork provides, on average, 97, 25.8, 35/43.7 (men/women), and 37% of the RDA (Recommended Dietary Allowances) for vitamins B(1), B(2), B(6), and B(12), respectively.
Is At Least One Vitamin Helping Our Vasculature?
2014
See related article, pp 1290–1298 Cardiovascular risk factors such as diabetes mellitus, arterial hypertension, chronic smoking, and hypercholesterolemia are cardiovascular risk factors known to be associated with endothelial dysfunction, a condition that may predict long-term progression of atherosclerosis as well as cardiovascular event rates (for review, see Munzel et al1) Although the mechanisms underlying this phenomenon are complex and multifactorial, there is growing body of evidence that oxidative stress attributable to increased production of reactive oxygen–derived free radicals may play a pivotal role in this process.2 Increased superoxide production by enzyme systems such as the…
Volume and heat capacity studies to evidence interactions between cyclodextrins and nicotinic acid in water
2008
Density and heat capacity of the water+cyclodextrin (CD), water+nicotinic acid (NA) and water+CD+NA mixtures were determined at 298.15 K. CDs with different cavity size and alkylation were selected. From the experimental data the apparent molar properties were calculated. Assuming the formation of inclusion complexes of 1:1 stoichiometry, these properties were modeled and provided the stability constants of CD/NA inclusion complexes and the corresponding property change. The binding of NA with the smallest sized alpha-cyclodextrin (alpha-CD) generates more stable complexes accompanied by the lower volume and the heat capacity changes. These results are in agreement with earlier proposed bin…
Assembly of the Major Light-harvesting Chlorophyll-a/b Complex
2006
The major light-harvesting chlorophyll-a/b complex in most higher plants contains three carotenoids, lutein, neoxanthin, and violaxanthin. How these pigments are assembled into the complex during its biogenesis is largely unknown. Here we show that neoxanthin but not lutein can dissociate from the fully assembled complex. Its equilibrium binding constant in a detergent system (0.1% n-dodecyl-beta-D-maltoside) was determined to be > or = 10(6) m(-1). Neoxanthin insertion into light-harvesting chlorophyll-a/b complex prefolded from overexpressed apoprotein (Lhcb1*2 from Pisum sativum) in the presence of chlorophylls a, b, and lutein as the sole carotenoid is kinetically controlled by an activ…