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At least 523 records · Page 29Linked to original sources
PubMed1993

Toxicological potential of malathion residues in stored soybean seeds.

Succinate-14C-malathion penetrates readily into soybean seeds. The total internal residues inside the seeds amounted to 58-65% of the applied dose after 30 weeks, of which 8-9% were in the form of bound residues. The major part of the internal methanol extractables are chloroform soluble metabolites which include malathion (about 60%), monocarboxylic acid (15%) and its decarboxylation product (8%). The water soluble metabolites contained only one radioactive substance, namely malathion dicarboxylic acid. The toxicological potential of the total internal residues was studied by feeding mice with the washed seeds for about 2.5 months. Treated mice suffered from deterioration of hepatic and renal function as indicated by the observed increased level of blood serum esterases and blood urea nitrogen. The results of blood biochemistry are supported by the histopathological changes observed in the liver, kidney, stomach and intestine. The organs showed degenerative changes including leucocytic aggregation, congestion and dilatation of blood vessels. Other adverse effects caused by malathion residues are indicated from cytogenetic studies on bone marrow of treated mice. Studies showed an initial bone marrow toxicity as indicated by increase in percentage of polychromatic erythrocytes over controls. This effect diminished upon prolongation of feeding period over one month. Feeding with malathion residues affected a gradual increase, with feeding period, in the percentage of polychromatic erythrocytes with micronuclei, a parameter recommended for detecting chemical mutagenes in animal test systems.

Acetylcholinesterase↗
PubMed2002

Flocculent activity of a recombinant protein from Moringa oleifera Lam. seeds.

Seeds of the tropical tree Moringa oleifera contain small storage proteins able to flocculate particles in suspension in water. The cDNA encoding one of these flocculent proteins, MO(2.1), was cloned and the recombinant protein was expressed in Escherichia coli. The flocculent activity of the purified recombinant MO(2.1)was assayed on clays and bacteria using light and confocal microscopy and GFP-overexpressing bacteria. We show that MO(2.1)is able to aggregate montmorillonite clay particles as well as gram-positive and gram-negative bacteria. We discuss the use of recombinant proteins to study flocculating properties and improve water purification processes.

Amino Acid Sequence↗
PubMed1983

Characterization of a glycoprotein alpha-galactosidase from lentil seeds (Lens culinaris).

alpha-Galactosidase (alpha-D-galactoside galactohydrolase, EC 3.2.1.22), an enzyme responsible for mobilizing the raffinose family of oligosaccharides in legume seeds, has been isolated from lentils (Lens culinaris) and purified about 4,000-fold. The Sephadex gel filtration profile showed the presence of two forms of the enzyme, alpha-galactosidase I with an apparent Mr = 160,000 and alpha-galactosidase II of Mr = 40,000. Enzyme II readily aggregates to form I when any attempt is made to concentrate the solution. Thus, only enzyme I was purified and its properties studied. The multistep purification procedure included affinity binding of the enzyme to concanavalin A-Sepharose, indicating its glycoprotein nature with glucose/mannose termini of the carbohydrate moieties. The amino acid and carbohydrate compositions of the native enzyme and that of the glycopeptide obtained from pronase-digested, denatured enzyme have been determined. Asparagine seems to be involved in forming the linkage with the carbohydrate moiety. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of enzyme I shows a single protein band with Mr = 40,000 which also stains with periodic acid-Schiff reagent. Thus, the enzyme consists of four identical glycoprotein subunits. The isoelectric point of the enzyme is 8.0. The pH optima of enzyme I and II are 6.1 and 4.7, respectively. The substrate specificity and the mode of substrate inhibition of enzyme I is discussed. The effect of temperature on Vmax and Km of the enzyme is presented; at pH 6.1 the energy of activation is 62.1 kJ/mol and the delta H value is -34.3 kJ/mol in the temperature range 20-50 degrees C. Preliminary studies show that enzyme I possesses hemagglutinating properties with glucose/mannose specificity.

Fabaceae↗
PubMed2005

Hybrid nanogels with physical and chemical cross-linking structures as nanocarriers.

Polymerizable nanogels were prepared by self-assembly of cholesteryl group-bearing pullulan (CHP) with methacryloyl groups (CHPMA). The CHPMA nanogel was polymerized with 2-methacryloyloxyethyl phosphorylcholine (MPC) by radical polymerization in dilute aqueous solution. The solution properties of the polymers in water were investigated by TEM, SEC-MALS, and fluorescence quenching technique. Monodispersed hybrid nanogels of CHPMA-MPC (CM nanogels) (25-30 nm in radius of gyration) were obtained by using CHPMA nanogel as a seed-nanogel. CM nanogels have a dual cross-linking structure that is physically cross-linked with the cholesteryl groups and chemically cross-linked with the MPC polymer chains. CM nanogels trap heat-denatured carbonic anhydrase B (CAB) and prevent their aggregations. The nanogels maintained the ability of trapping and releasing enzymes by host-guest interaction of cholesteryl group and cyclodextrin.

Cholesterol↗
PubMed2004

Insulin microcrystal suspension as a long-acting formulation for pulmonary delivery.

Pulmonary delivery provides the most promising non-parenteral route of insulin administration. Insulin was used as a model protein to demonstrate the feasibility of using protein crystals for the pulmonary delivery of a sustained-release protein drug formulation. Insulin microcrystals with a mean diameter of 3 microm were prepared using a seed zone method. The yield of crystallization was very high (95.8 +/- 0.97%), and the microcrystals were recovered with high efficiency (>98%) by centrifugation. Morphological examination using scanning electron microphotography showed the microcrystals to be of a homogeneous rhombohedral shape, with some rhombus forms, without aggregates. After the administration of 32 U/kg of the microcrystal suspension to STZ-induced diabetic SD rats by intratracheal instillation, the blood glucose levels were reduced and hypoglycemia was prolonged over 13 h, as compared to the insulin solution. The percent minimum reductions of the blood glucose concentration (% MRBG) produced by the microcrystal suspension and insulin solution reached 36.5 and 37.2%, respectively, of the initial level, and the percent total reductions in blood glucose (% TRBG(13 h)) were 34.4 and 25.0%, respectively. In the case of inhalation using a sieve-type ultrasonic nebulizer, the % MRBG produced by the microcrystal suspension and insulin solution were 21.7 and 26.3%, respectively, of the initial level, and the % TRBG(13 h) were 66.7 and 58.4%, respectively. However, the hypoglycemic effects of the microcrystal suspension were prolonged over 7 h, which compares favorably with the insulin solution (P<0.5 by unpaired t-test). These results could be attributed to the sustained-release of insulin from the microcrystals, which were deposited widely throughout the entire lung.

Administration, Inhalation↗
PubMed2002

Small intestinal submucosa versus salt-extracted polyglycolic acid-poly-L-lactic acid: a comparison of neocartilage formed in two scaffold materials.

This study sought to compare differences in neocartilage produced over time from two types of resorbable scaffold materials. One material was entirely synthetic and contained a polyglycolic acid-poly-L-lactic acid matrix (PGA-PLLA). The second scaffold material was bioactive and consisted of a four-layered construct of porcine small intestinal submucosa (SIS). Disk-shaped scaffolds were seeded with canine chondrocytes and implanted into athymic mice for periods of 5, 8, 12, and 24 weeks. Constructs were examined microscopically, assayed for hydroxyproline (HP) and glycosaminoglycan (GAG) content, and collagen typed (I or II) at each time period. Creep indentation tests determined aggregate and shear modulus, permeability, and thickness. Results indicated that SIS maintained its thickness through the first 12 weeks, and then doubled by week 24. The 24-week tissue appeared chondroid-like and possessed high GAG content. Tissues derived from PGA-PLLA scaffolds were lower in HP content than SIS-derived tissues, but type II collagen was demonstrated only in PGA-PLLA-derived tissues at 24 weeks. Mechanical properties were not significantly different for any tissue over time (p > 0.05), but aggregate and shear modulus mean values were consistently higher for PGA-PLLA-derived tissues at nearly every time interval. This, coupled with the presence of collagen types I and II, suggested a more congruent solid phase may be forming within the extracellular matrix of tissues derived from PGA-PLLA scaffolds. Future study is necessary to compare these materials under simulated loading conditions.

Animals↗
PubMed2003

Components of reproductive isolation between the monkeyflowers Mimulus lewisii and M. cardinalis (Phrymaceae).

Evolutionists have long recognized the role of reproductive isolation in speciation, but the relative contributions of different reproductive barriers are poorly understood. We examined the nature of isolation between Mimulus lewisii and M. cardinalis, sister species of monkeyflowers. Studied reproductive barriers include: ecogeographic isolation; pollinator isolation (pollinator fidelity in a natural mixed population); pollen competition (seed set and hybrid production from experimental interspecific, intraspecific, and mixed pollinations in the greenhouse); and relative hybrid fitness (germination, survivorship, percent flowering, biomass, pollen viability, and seed mass in the greenhouse). Additionally, the rate of hybridization in nature was estimated from seed collections in a sympatric population. We found substantial reproductive barriers at multiple stages in the life history of M. lewisii and M. cardinalis. Using range maps constructed from herbarium collections, we estimated that the different ecogeographic distributions of the species result in 58.7% reproductive isolation. Mimulus lewisii and M. cardinalis are visited by different pollinators, and in a region of sympatry 97.6% of pollinator foraging bouts were specific to one species or the other. In the greenhouse, interspecific pollinations generated nearly 50% fewer seeds than intraspecific controls. Mixed pollinations of M. cardinalis flowers yielded >75% parentals even when only one-quarter of the pollen treatment consisted of M. cardinalis pollen. In contrast, both species had similar siring success on M. lewisii flowers. The observed 99.915% occurrence of parental M. lewisii and M. cardinalis in seeds collected from a sympatric population is nearly identical to that expected, based upon our field observations of pollinator behavior and our laboratory experiments of pollen competition. F1 hybrids exhibited reduced germination rates, high survivorship and reproduction, and low pollen and ovule fertility. In aggregate, the studied reproductive barriers prevent, on average, 99.87% of gene flow, with most reproductive isolation occurring prior to hybrid formation. Our results suggest that ecological factors resulting from adaptive divergence are the primary isolating barriers in this system. Additional studies of taxa at varying degrees of evolutionary divergence are needed to identify the relative importance of pre- and postzygotic isolating mechanisms in speciation.

Adaptation, Biological↗
PubMed2000

Oligomeric proanthocyanidin complexes: history, structure, and phytopharmaceutical applications.

Considerable recent research has explored therapeutic applications of oligomeric proanthocyanidin complexes (OPCs), naturally occurring plant metabolites widely available in fruits, vegetables, nuts, seeds, flowers, and bark. OPCs are primarily known for their antioxidant activity. However, these compounds have also been reported to demonstrate antibacterial, antiviral, anticarcinogenic, anti-inflammatory, anti-allergic, and vasodilatory actions. In addition, they have been found to inhibit lipid peroxidation, platelet aggregation, capillary permeability and fragility, and to affect enzyme systems including phospholipase A2, cyclooxygenase, and lipoxygenase. Based on these reported findings, OPCs may be a useful component in the treatment of a number of conditions.

Anthocyanins↗
PubMed2005

Developing macroporous bicontinuous materials as scaffolds for tissue engineering.

Calcareous skeletal elements (ossicles) isolated from the seastar, Pisaster giganteus, were characterized and tested as potential biocompatible substrates for cellular attachment. These ossicles have a remarkably robust open-framework architecture with an interconnected network of ca. 10 microm diameter pores. Scanning electron and confocal microscopy was used to characterize the cell-substrate interaction. Cell culturing experiments revealed that the cells firmly attach to the ossicle surface, forming cell aggregates of several layers thick. The anchored cells extended to form 'bridges' between the openings in the bicontinuous framework and the degree of coverage increased as culture time progressed. Osteoblasts grown on the ossicles were found to be viable up to 32 days after initial seeding, as proven by assaying with AlamarBlue and FDA/PI staining indicating the ossicle's potential as an alternative highly effective tissue scaffold. Given the limitation in availability of this natural material, the results presented here should be seen as offering guidelines for future development of synthetic materials with physical and chemical properties strongly conducive to bone repair and restoration.

Animals↗
PubMed2005

Effect of inorganic fertilizer and farmyard manure on soil physical properties, root distribution, and water-use efficiency of soybean in Vertisols of central India.

A field experiment was conducted on a Vertisol for three consecutive years (1998-2000) to study the effects of combined use of inorganic fertilizer (NPK) and organic manure (farmyard manure) on soil physical properties, water-use efficiency, root growth and yield of soybean [Glycine max (L.) Merr.] in a soybean-mustard cropping system. Application of 10 Mg farmyard manure and recommended NPK (NPK+FYM) to soybean for three consecutive years improved the organic carbon content of the surface (0-15 cm) soil from an initial value of 4.4 g kg(-1) to 6.2 g kg(-1) and also increased seed yield and water-use efficiency by 103% and 76%, respectively, over the control. The surface (0-15 cm) soil of the plots receiving both farmyard manure and recommended NPK had larger mean weight diameter (0.50 mm) and a higher percentage of water stable aggregates (55%) than both the inorganically fertilized (NPK) (0.44 mm and 49%) and unfertilized control plots (0.41 mm and 45.4%). The saturated hydraulic conductivity (13.32 x 10(-6) m s(-1)) of the NPK+FYM treatment of the 0-7.5 cm depth was also significantly greater than that of the NPK (10.53 x 10(-6) m s(-1)) and control (8.61 x 10(-6) m s(-1)) treatments. The lowest bulk density (1.18 Mg m(-3)) in the 0-7.5 cm layer was recorded in NPK+FYM whereas it was highest in the control plots (1.30 Mg m(-3)). However, at sub-surface (22.5-30 cm) layer, fertilizer and manure application had little effect on bulk density and saturated hydraulic conductivity. Root length density (RLD) up to the 30 cm depth was highest in the NPK+FYM plots and it was 31.9% and 70.5% more than NPK and control plots. The RLD showed a significant and negative correlation (r=-0.88( * *)) with the penetration resistance.

Agriculture↗
PubMed2002

Tailoring the pore architecture in 3-D alginate scaffolds by controlling the freezing regime during fabrication.

The pore architecture in 3-D polymeric scaffoldings plays a critical role in tissue engineering as it provides the framework for the seeded cells to organize into a functioning tissue. In the present paper, we investigate the effect of freezing regime on the pore microstructure in 3-D alginate scaffolds, fabricated by the freeze-dry method. The scaffolds have shown isotropic pore structure, when the calcium crosslinked alginate solutions were slowly frozen at -20 degrees C, in a nearly homogenous cold atmosphere; the pores were spherical and interconnected. In contrast, when the cooling process was performed in liquid nitrogen or oil bath, where a temperature gradient was formed along the freezing solution, two main regions of pore structure were noted; at the interface with the cooling medium, small spherical pores were seen and above them a region with elongated pores. The different pore shape affected the compressibility of the scaffolds, while it had no effect on albumin diffusion. Rat hepatocytes seeded within the scaffolds were arranged according to the their pore shape. In scaffolds with elongated pores, the cells were lining along the pores, thus forming lines of interacting cells. In the scaffolds with the isotropic spherical pores, the hepatocytes clustered into spheroid-like aggregates. Thus, it appears that pore shape can modulate hepatocyte morphogenesis.

Albumins↗
PubMed2003

Identification of minimal peptide sequences in the (8-20) domain of human islet amyloid polypeptide involved in fibrillogenesis.

We have examined a series of overlapping peptide fragments from the 8-20 region of human islet amyloid polypeptide (IAPP) with the objective of defining the smallest fibril-forming domain. Peptide fragments corresponding to LANFLV (residues 12-17) and FLVHSS (residues 15-20) were strong enhancers of beta-sheet transition and fibril formation. Negative stain electron microscopy illustrated the ability of these peptide fragments to form fibrils independently when incubated alone in solution. Circular dichroism analysis revealed that when full-length human IAPP was incubated in the presence of these two fragments, fibrillogenesis was accelerated. While the two fragments, LANFLV and FLVHSS, were able to enhance the recruitment of additional IAPP molecules during fibril formation, the "seeding" activity of these peptides had no effect on altering IAPP-induced cytotoxcity as determined by cell culture studies. Therefore, this study has identified two internal IAPP peptide fragments within the 8-20 domain that may have a role in enhancing the folding and aggregation of human IAPP. These fragments are the smallest sequences identified, within the 8-20 region of hIAPP, that can independently form fibrils, and that can interact with IAPP to assemble into fibrils with characteristics similar as those formed by human IAPP alone.

Amyloid↗
PubMed1998

Protein anatomy: C-tail region of human tau protein as a crucial structural element in Alzheimer's paired helical filament formation in vitro.

Tau is a microtubule-associated protein in mammalian brain. In Alzheimer's disease, this protein is present in the somatodendritic compartment of certain nerve cells, where it forms a portion of paired helical filament, the major constituent of the neurofibrillary tangle. For clarification of the mechanism of this formation, recombinant human tau and its fragments (N-terminal half, C-terminal half, and 4-repeats) expressed in Escherichia coli were prepared, eight peptide fragments (C-tails 1-8) of the C-tail region were synthesized, and the conformation and capacity for aggregation essential for filamentous structure formation in vitro were examined. Recombinant full-length tau, the N-terminal half, 4-repeats, and the C-terminal half did not form filamentous structures in aqueous solution after standing at 20 degrees C. Peptides corresponding to the C-tail region of tau, C-tail 5, C-tail 7, and C-tail 8, produced the paired filament or single straight filament in acidic solution. The rate of filament formation by each peptide was followed by circular dichroism, which showed the C-tails to have predominantly random coil structures immediately following dissolution in aqueous solution and be gradually converted to the beta-sheet structure. The kinetics of aggregation were characterized by a delay period during which the solution remained clear, followed by a nucleation event which led to a growth phase, whose negative peak intensity at 218 nm in circular dichroism increased due to filamentous structure formation. This delay was eliminated by seeding supersaturated solution of preformed filaments. C-tails interacted with recombinant full-length tau to form definite single straight filament. The C-tail region of tau is thus shown indispensable to the formation of paired helical filament and nucleation to reduce the rate of paired helical filament formation in amyloidogenesis in vitro. These findings may provide some clarification of the pathogenesis of Alzheimer's disease.

Alzheimer Disease↗
PubMed1996

Adenylyl cyclase G, an osmosensor controlling germination of Dictyostelium spores.

Dictyostelium cells express a G-protein-coupled adenylyl cyclase, ACA, during aggregation and an atypical adenylyl cyclase, ACG, in mature spores. The ACG gene was disrupted by homologous recombination. acg- cells developed into normal fruiting bodies with viable spores, but spore germination was no longer inhibited by high osmolarity, a fairly universal constraint for spore and seed germination. ACG activity, measured in aca-/ACG cells, was strongly stimulated by high osmolarity with optimal stimulation occurring at 200 milliosmolar. RdeC mutants, which display unrestrained protein kinase A (PKA) activity and a cell line, which overexpresses PKA under a prespore specific promoter, germinate very poorly, both at high and low osmolarity. These data indicate that ACG is an osmosensor controlling spore germination through activation of protein kinase A.

Adenylyl Cyclases↗
PubMed2005

Strong spatial genetic structure in peripheral but not core populations of Sitka spruce [Picea sitchensis (Bong.) Carr.].

We examined spatial genetic structure within eight populations of Sitka spruce classified as core or peripheral based on ecological niche, and continuous or disjunct based on species distribution. In each population, 200 trees were spatially mapped and genotyped for eight cDNA-based sequence tagged site (STS) codominant markers. Spatial autocorrelation was assessed by estimating p(ij), the average co-ancestry coefficient, between individuals within distance intervals. The distribution of alleles and genotypes within core populations was almost random, with nonsignificant co-ancestry values among trees as close as 50 m in core populations. In contrast, the distribution of alleles and genotypes within peripheral populations revealed an aggregation of similar multilocus genotypes, with co-ancestry values greater than 0.20 among trees up to 50 m apart and significant, positive values between trees up to 500 m. The relatively high density of reproductive adults in core populations may lead to highly overlapping seed shadows that limit development of spatial genetic structure. However, in peripheral populations with a lower density of adults, the distribution of alleles and genotypes was highly structured, likely due to offspring establishment near maternal trees and subsequent biparental inbreeding, as well as more recent population establishment at the leading edge of post-Pleistocene range expansion. Conserving genetic diversity in peripheral populations may require larger reserves for in situ conservation than required in core populations. These data on spatial genetic structure can be used to provide guidance for sampling strategies for both ex situ conservation and research collections.

British Columbia↗
PubMed2002

Sludge bed development in denitrifying reactors using different inocula-performance and microbiological aspects.

Aerobic and methanogenic consortia were evaluated as inocula for laboratory scale denitrifying reactors, fed with a synthetic wastewater with acetate as the main electron donor. The denitrifying microflora of inocula and reactors was evaluated by specific denitrifying activity, enumeration and isolation of denitrifiers, which were screened by amplified ribosomal DNA restriction analysis. Reactor performance was monitored by COD and nitrate removal efficiencies and granule size. The aerobic sludge failed to form granules, probably due to the development of a filamentous, nitrate-reducing organism which was characterised by 16SrDNA sequencing as Bacillus cereus. The methanogenic sludge showed denitrifying activity and adapted very rapidly to denitrifying conditions in the two reactors seeded with granules of different sizes. Denitrifiers grew around the granules, increasing the specific denitrifying activity of the sludge over 10-fold. Exopolymer-forming organisms, belonging to the same species, were isolated from both reactors. Granule size increased during operation, but flotation of the aggregates, related to gas retention was observed.

Acetates↗
PubMed1996

Characterization of seed oil bodies and their surface oleosin isoforms from rice embryos.

Plant seeds store triacylglycerols in discrete organelles called oil bodies. An oil body stores a matrix of triacylglycerols surrounded by phospholipids and alkaline proteins termed oleosins. Oil bodies in rice seeds are present in embryos and aleurone layers. They do not coalesce in crowded environments, as observed on electron microscopy. The detected isoelectric point of purified rice oil bodies is pH 6.2. This implies that rice oil bodies possess a negatively charged surface at neutral pH. The suspension of rice oil bodies in pH 6.5 buffer induces aggregation. Presumably, the negatively charged surface causes electrostatic repulsion that maintains rice oil bodies as discrete organelles. Rice oil bodies lose their integrity on trypsin treatment. Undoubtedly, oleosins play an important role in the stability of oil bodies. There are two oleosin isoforms in rice oil bodies. Antibodies raised against these two homologous isoforms do not cross-recognize each other. Both isoforms are restricted to oil bodies, as detected on immuno-assaying. Partial amino acid sequences of these two isoforms were obtained, and compared with the deduced sequences of two maize and two rice oleosin genes. The comparison confirmed that the two major proteins in rice oil bodies are the two oleosin isoforms.

Amino Acid Sequence↗
PubMed2006

Biochemical and functional analysis of the assembly of full-length Sup35p and its prion-forming domain.

The protein Sup35 has prion properties. Its aggregation is at the origin of the [PSI(+)] trait in Saccharomyces cerevisiae. In vitro, the N-terminal domain of Sup35p alone or with the middle domain assembles into fibrils that exhibit the characteristics of amyloids. The vast majority of in vitro studies on the assembly of Sup35p have been performed using Sup35pNM, as fibrils made of Sup35pNM assembled in vitro propagate [PSI(+)] when reintroduced into yeast cells. Little is known about the assembly of full-length Sup35p and the role of the functional C-terminal domain of the protein. Here we report a systematic comparison of the biochemical and assembly properties of full-length Sup35p and Sup35pNM. We show that the native structure of the C-terminal domain is retained within the fibrils. We determined the size of Sup35p nuclei and the critical concentration for assembly that both differ from that of Sup35pNM. We demonstrate that Sup35pNM co-assembles with the full-length protein and that fibrils made of Sup35p or Sup35pNM seed the assembly of soluble Sup35pNM and Sup35p with different efficiencies. Finally, we show that fibrils made of full-length Sup35p induce with higher efficiency [PSI(+)] appearance as compared with those made of Sup35pNM. Our findings reveal differences and similarities in the assembly of Sup35p and its NM fragment and validate the use of Sup35pNM in studying some aspects of Sup35p aggregation but also underline the importance of using full-length Sup35p in studying prion propagation both in vivo and in vitro.

Cell Nucleus↗