Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Yield stability”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed1996

Heterologous expression and characterization of the bifunctional dihydrofolate reductase-thymidylate synthase enzyme of Toxoplasma gondii.

We have expressed catalytically active Toxoplasma gondii dihydrofolate-thymidylate synthase (DHFR-TS) and the individual TS and DHFR domains in Escherichia coli using the T7 promoter of pET-15b. DHFR-TS constituted approximately 10% of the total soluble cell protein and was purified using methotrexate-Sepharose chromatography to yield 10 mg of homogeneous DHFR-TS per liter of culture. The DHFR domain was recovered as insoluble inclusion bodies which could be unfolded and refolded to recover soluble, active enzyme. The TS domain was overexpressed as a soluble protein by growing the cells at 24 degrees C; this is the first report of the expression of an active TS domain from a bifunctional enzyme. The kcat and K(m) values for DHFR-TS are similar to those of other previously characterized protozoan DHFRs and TSs. The antimicrobial antifolates, TMP and Pyr, inhibit DHFR activity of the bifunctional protein in accord with their effects in crude enzyme preparations and in vivo systems. Kinetic parameters and Ki values for TMP and Pyr with the isolated DHFR domain were identical to the values for DHFR in the bifunctional enzyme. Evidence of kinetic channeling of the dihydrofolate product of TS to the DHFR domain in the bifunctional enzyme was obtained by kinetic and inhibition studies. Properties such as yield, stability, and activities of the recombinant T. gondii DHFR-TS provide clear advantages over other bifunctional DHFR-TSs as a model for future studies.

Animals↗
PubMed1997

Chemistry in Environmentally Benign Media. 7.(1) Chelating Hydroxymethyl-Functionalized Bisphosphines as Building Blocks to Water-Soluble and in-Vitro-Stable Gold(I) Complexes. Synthesis, Characterization, and X-ray Crystal Structures of [Au{(HOH(2)C)(2)PC(6)H(4)P(CH(2)OH)(2)}(2)]Cl and [Au(2){(HOH(2)C)(2)PCH(2)CH(2)P(CH(2)OH)(2)}(2)]Cl(2).

The reactions of water-soluble bisphosphines (HOH(2)C)(2)PC(6)H(4)P(CH(2)OH)(2) (1) and (HOH(2)C)(2)PCH(2)CH(2)P(CH(2)OH)(2) (2) with NaAuCl(4), in aqueous media, or AuClPPh(3), in biphasic media (aqueous/organic), produced the water/alcoholic-soluble Au(I) complexes [Au{(HOH(2)C)(2)PC(6)H(4)P(CH(2)OH)(2)}(2)]Cl (3), [Au{(HOH(2)C)(2)PCH(2)CH(2)P(CH(2)OH)(2)}(2)]Cl (4), and [Au(2){(HOH(2)C)(2)PCH(2)CH(2)P(CH(2)OH)(2)}(2)]Cl(2) (5) in near quantitative yields. Stability and cysteine-challenge studies of 3 indicate the kinetic inertness of these new complexes. Complex 5 is luminescent in the solid state at room temperature. When excited at 280 nm in non-degassed water at room temperature, the emission spectrum shows a high-energy band at 310 nm and a low-energy band at 560 nm. The large Stokes shift for the low-energy band implies that the emission is phosphorescence. The X-ray structures of 3 and 5, reported in this paper, confirm the gold(I) structures of this new generation of water-soluble transition metal complexes. All compounds were characterized by (31)P and (1)H NMR spectroscopy and mass spectroscopy. X-ray data for 3: monoclinic, P2(1)/m, a = 9.8715(5) Å, b = 9.9465(5) Å, c = 14.5621(8) Å, beta = 106.5930(10) degrees, Z = 2, R = 0.032 (R(w) = 0.050). X-ray data for 5: monoclinic, C2/c, a = 29.7128(14) Å, b = 16.7062(8) Å, c = 22.3762 (11) Å, beta = 117.6970(10) degrees, Z = 16, R = 0.051 (R(w) = 0.072).

Journal Article↗
PubMed2003

A theoretical study on the mechanism of the cyclopolymerization of diallyl monomers.

The cyclization and intermolecular propagation steps of the cyclopolymerization mechanism are studied with density functional theory. In addition to standard cyclization and intermolecular propagation reactions of cyclopolymerization, competing reactions that lead to chain transfer and termination are also discussed. The mechanistic study of the cyclopolymerization reaction of two representative monomers, N,N-diallylamine (1) and N,N-dimethyl-N,N-diallylamonium (2), was carried out with B3LYP/6-31G computations. Monomer 1 has almost the same activation barriers for homopolymerization and cyclization. In monomer 2, cyclization is much more facile than homopolymerization, leading to the higher cyclopolymerization efficiency. In the case of 2, methyl substituents on nitrogen inhibit hydrogen abstraction, whereas in 1, hydrogen abstraction reactions from the neutral monomer yield stabilized products leading to chain transfer. Calculations show that facile competing reactions of monomer 1 lower the polymerization efficiency. Monomer 2 displays a stronger preference for cyclization relative to other processes.

Allyl Compounds↗
PubMed1978

Modulation of the formation of the amplification convertase of complement, C3b, Bb, by native and commercial heparin.

Native rat mast cell macromolecular heparin proteoglycan and commercial hog heparin glycosaminoglycan chains inhibit generation of the amplification convertase, C3b, Bb. The inhibitory action of heparin is not due to chelation of magnesium. Heparin is most active in inhibiting convertase formation on cellular intermediates formed with the lowest C3b input and developed with the highest B concentration, thereby suggesting the receptor site for B on C3b as the point of heparin action. This interpretation is consistent with the demonstration that heparin prevents B utilization during the fluid phase interaction of C3b, B, and D. Inhibition is observed also when C3b,Bb generation takes place on cellular intermediates in the presence of P or C3NeF, which yield stabilized forms of the convertase. 50 times the concentration of heparin required to inhibit convertase generation does not accelerate the decay of the unstabilized or the C3NeF-stabilized convertases and has only a modest effect on the P-stabilized convertase. An additional effect of heparin is to impair beta1H-mediated decay-dissociation of C3b,Bb. The concentration of native or commercial heparin which prevents convertase formation is in the same range as that required for the demonstration of its anti-coagulant and anti-thrombin III cofactor activities. The additional finding that this inhibitory action of heparin can be expressed by the isolated mast cell granule suggests that native heparin may contribute to the modulation of the amplification pathway of complement.

Animals↗
PubMed1989

Malignant conversion of UV radiation and chemically induced mouse skin benign tumors by free-radical-generating compounds.

It is known that the free-radical-generating compound, benzoyl peroxide (BPO) enhances malignant conversion of murine skin benign papillomas into carcinomas. To further define the role of free radicals in malignant conversion, we studied the effect of various free-radical-generating compounds on the conversion of benign papillomas into carcinomas in murine skin. Papillomas were induced in Sencar mice by 7,12-dimethylbenz[a]anthracene (DMBA) initiation and 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion and in SKH-1 hairless mice by biweekly exposure to UVB radiation. After 20 and 27 weeks respectively, papilloma yield stabilized and no new tumors developed. Skin application of acetone, TPA, BPO, 2,2-azobis(2-amidino-propane) (ABP) and tert-butyl hydroperoxybenzoic acid (BPB) increased the rate of malignant conversion in both Sencar and SKH-1 mice. In general, the rate of malignant conversion was faster in UVB-induced tumors compared with DMBA-induced tumors. The relative efficacy of each agent was similar in both groups and was in the order: acetone less than TPA less than BPB less than BPO less than ABP. Our data suggest that free-radical-generating compounds may accelerate the malignant conversion of benign papillomas into carcinoma, indicating that epigenetic mechanism(s) may also be involved in this process.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1991

All-trans retinoic acid protects against conversion of chemically induced and ultraviolet B radiation-induced skin papillomas to carcinomas.

It is becoming increasingly clear that cutaneous carcinogenesis in murine skin is a stepwise process comprising of initiation, promotion and progression. Most of the papillomas induced by an initiation-promotion protocol regress, while a few of them progress to malignant carcinomas. Progression of benign tumors into malignant cancer is critical since the latter lesions are capable of metastatic spread and eventual death. Inhibitors of the conversion process are therefore likely to be useful as cancer chemopreventive agents. All-trans retinoic acid (RA) is a known regulator of cellular proliferation and differentiation, and a known inhibitor of tumor promotion in murine skin. In this study we assessed the effect of topical application of RA on conversion of benign skin papillomas to malignant carcinomas. Papillomas were induced in SENCAR mice by topical application of 7,12-dimethylbenz[a]anthracene (DMBA) as tumor initiator followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) as tumor promoter. In SKH-1 hairless mice papillomas were induced by thrice weekly exposure to ultraviolet B (UVB) radiation. At 18 (DMBA/TPA group) and 25 (UVB group) weeks papilloma yield stabilized and no new tumors developed. Beginning at the 20th week (DMBA/TPA group) and at the 27th week (UVB group), malignant conversion was achieved by twice weekly topical application of TPA or free radical-generating compounds benzoyl peroxide (BPO), 2,2-azobis(2-amidinopropane) (ABP) and tert-butyl peroxybenzoate (BPB). Application of RA (10 micrograms/animal) 1 h prior to skin application of TPA, BPO, ABP or BPB afforded significant protection (up to 70%) only against malignant conversion mediated by free radical-generating compounds in both chemically induced and UVB-induced benign skin papillomas. On the other hand, preapplication of RA was less effective in the suppression of spontaneous malignant conversion in vehicle-treated animals. These results suggest that, in addition to their anti-tumor promoting effects, retinoids may also act as anti-carcinogens by inhibiting the process of malignant conversion induced by free radical-generating compounds.

Animals↗
PubMed2000

Phenotypic responses of wild barley to experimentally imposed water stress.

Responses to water stress within a population of wild barley from Tabigha, Israel, were examined. The population's distribution spans two soil types: Terra Rossa (TR) and Basalt (B). Seeds were collected from plants along a 100 m transect; 24 genotypes were sampled from TR and 28 from B. Due to different soil water-holding capacities, plants growing on TR naturally experience more intense drought than plants growing on B. In a glasshouse experiment, water was withheld from plants for two periods (10 d and 14 d) after flag leaf emergence. A total of 15 agronomic, morphological, developmental, and fertility related traits were examined by analysis of variance (ANOVA). Ten of these traits were significantly affected by the treatment. A high degree of phenotypic variation was found in the population with significant genotypextreatment and soil typextreatment interactions. Principal component analysis (PCA) was performed using combined control and stress treatment data sets. The first three principal components (pc) explained 88.8% of the variation existing in the population with pc1 (47.9%) comprising yield-related and morphological traits, pc2 (22.9%) developmental characteristics and pc3 (18.0%) fertility-related traits. The relative performance of individual genotypes was determined and water stress tolerant genotypes identified. TR genotypes were significantly less affected by the imposed water stress than B genotypes. Moreover, TR genotypes showed accelerated development under water deficit conditions. Data indicate that specific genotypes demonstrating differential responses may be useful for comparative physiological studies, and that TR genotypes exhibiting yield stability may have value for breeding barley better adapted to drought.

Adaptation, Physiological↗
PubMed2005

Nonequilibrium statistical mechanical models for cytoskeletal assembly: towards understanding tensegrity in cells.

The cytoskeleton is not an equilibrium structure. To develop theoretical tools to investigate such nonequilibrium assemblies, we study a statistical physical model of motorized spherical particles. Though simple, it captures some of the key nonequilibrium features of the cytoskeletal networks. Variational solutions of the many-body master equation for a set of motorized particles accounts for their thermally induced Brownian motion as well as for the motorized kicking of the structural elements. These approximations yield stability limits for crystalline phases and for frozen amorphous structures. The methods allow one to compute the effects of nonequilibrium behavior and adhesion (effective cross-linking) on the mechanical stability of localized phases as a function of density, adhesion strength, and temperature. We find that nonequilibrium noise does not necessarily destabilize mechanically organized structures. The nonequilibrium forces strongly modulate the phase behavior and have comparable effect as the adhesion due to cross-linking. Modeling transitions such as these allows the mechanical properties of cytoskeleton to rapidly and adaptively change. The present model provides a statistical mechanical underpinning for a tensegrity picture of the cytoskeleton.

Animals↗
PubMed1988

Production of stable rabbit-mouse hybridomas that secrete rabbit mAb of defined specificity.

Inclusion of normal rabbit serum (NRS) in culture medium after interspecific fusion of hyperimmunized rabbit spleen cells with murine SP2/0 myeloma cells produced 271 rabbit-mouse hybridomas (RMHs) that secreted rabbit immunoglobulin against group A Streptococcus (GAS). Continued use of NRS-supplemented medium during cloning yielded stabilized monoclonal RMH lines that have secreted GAS-specific rabbit antibody at concentrations similar to murine hybridomas (3 to 8 micrograms per 10(6) cells per 24 hours), for over 4 months of culture in vitro. The use of NRS as a medium supplement during initial culture, cloning, and stabilization of RMHs enables production of considerably more specific rabbit monoclonal antibody (mAb)-secreting RMHs than have previously been reported.

Animals↗
PubMed2026

Branching plasticity and candidate gene-hormone networks associated with shade responses in soybean under relay strip intercropping.

BACKGROUND: Branching is a key determinant of high-yield plant architecture in soybean, particularly in maize- soybean relay strip intercropping where plants experience an "initially shaded-then fully illuminated" light regime. However, the genetic regulation of branching responses to shading remains poorly understood. METHODS: We evaluated 11 branching-related traits across 202 soybean accessions grown under monoculture (SS) and relay strip intercropping (RI). Branch number (BN), branching incidence (BI), and total branch length (TBL) were assessed together with stress tolerance indices (STI) and relative distance plasticity index (RDPI). Genome-wide association studies (GWAS) using mixed linear model (MLM) and three-variance-component MLM (3VmrMLM) were combined with haplotype and protein structural analyses to refine candidate genes. RESULTS: Based on Pearson correlation analysis of all 11 traits, BN, BI, and TBL measured before maize harvest showed the strongest and most consistent associations with branch seed weight within the corresponding cropping system (BSW_SS under SS and BSW_RI under RI), whereas other traits showed weaker or environment-dependent associations. Higher STI values calculated from these traits during the co-growth phase were negatively associated with BSW_RI, suggesting weaker compensatory recovery after light restoration in genotypes with more stable early branching patterns between SS and RI. In contrast, mediation analysis indicated that RDPI was positively associated with BSW_RI mainly through improved mature branching architecture (MB_index), which accounted for approximately 70% of the total positive effect. GWAS identified 57 and 74 significant QTNs using MLM and 3VmrMLM, respectively, and LD-window genes were filtered for exonic nonsynonymous or premature stop-codon variants, yielding 883 genes with putative functional variants. Two high-confidence genes emerged: Glyma.02G058600 (PP2C55), exhibiting shading-specific haplotype effects likely linked to GA-mediated branch-stem balance, and Glyma.02G059900 (DA1-related protein), showing stable effects across environments and implicated in ABA-mediated suppression of axillary meristems. CONCLUSIONS: These results provide insight into the genetic and physiological basis of soybean branching responses under relay strip intercropping, clarify that branching plasticity and relative shade tolerance represent distinct response dimensions in this system, and identify putative loci that may be useful for breeding soybean cultivars with improved shade adaptation and yield stability.

Glycine max↗
PubMed1983

On nitroaryl reductase activities in several Clostridia.

Crude extracts of Clostridium kluyveri, Clostridium spec. La 1, Clostridium sporogenes and Clostridium pasteurianum catalyse the NADH-dependent reduction of the nitro group of p-nitrobenzoate. The former three Clostridia also use pyruvate as electron donor for this reduction. The NADH-dependent reductases have been partially purified and characterized from Clostridium kluyveri. Nitroalkyl compounds as well as nitrite, sulfite, sulfate and hydroxylamine are no substrates. Based on chromatographic behavior, separation pattern, yields, stability, pH optima, molecular masses and EPR studies the three NADH-dependent nitroaryl group reducing enzymes in Clostridium kluyveri (three activities in Clostridium spec. La 1 and two activities in Clostridium sporogenes) are different from alcohol dehydrogenase, aldehyde dehydrogenase, 3-hydroxy-butyryl-CoA dehydrogenase, butyryrl-CoA dehydrogenase, 2-enoate reductase, ferredoxin-NAD and ferredoxin-NADP reductase. The physiological roles of the nitroaryl reductases are not known. The reductase activities show losses of 80-90% during classical protein purification procedures. One of the three nitroaryl reductases exhibits a pH optimum of 10.5. The crude extract reveals a pH optimum at 11.5. The first step of the reduction reaction leads to the nitroradical anion (1 electron transfer). The electron transfer to p-nitrobenzoate is also catalysed by ferrodoxin-NAD reductase from NADH and by ferredoxin-NADP reductase from NADP. Partially purified 2-oxo-acid synthases from Clostridium sporogenes catalyse with low rates the reduction of p-nitrobenzoate as well as 2-nitroethanol in the presence and absence of ferredoxin using pyruvate or 2-oxo-4-methylpentanoate as electron donors, respectively. The NADH-dependent reduction of p-nitro-benzoate accounts for at least 70% and the 2-oxo acid-dependent reduction for about 5% of the total nitroaryl reductase activity in the Clostridia. It seems that the pyridine nucleotide-dependent nitroaryl reductases are enzymes so far unknown in Clostridia.

Clostridium↗
PubMedDate not supplied

Standardization of dot-ELISA for the serological diagnosis of toxocariasis and comparison of the assay with ELISA.

The dot-enzyme-linked immunosorbent assay (dot-ELISA) was standardized using somatic (S) and excretory-secretory (ES) antigens of Toxocara-canis for the detection of specific antibodies in 22 serum samples from children aged 1 to 15 years, with clinical signs of toxocariasis. Fourteen serum samples from apparently normal individuals and 28 sera from patients with other pathologies were used as controls. All samples were used before and after absorption with Ascaris suum extract. When the results were evaluated in comparison with ELISA, the two tests were found to have similar sensitivity, but dot-ELISA was found to be more specific in the presence of two antigens studied. Dot-ELISA proved to be effective for the diagnosis of human toxocariasis, presenting advantages in terms of yield, stability, time and ease of execution and low cost.

Adolescent↗
PubMed2026

Hormone priming and metabolic engineering of phytohormone crosstalk in rice under combined biotic and abiotic stresses: a multi-omics perspective for climate-resilient crop development.

Rice (Oryza sativa L.) is the caloric backbone for more than half of humanity, yet it remains one of the most vulnerable crops to the simultaneous biotic and abiotic stresses exacerbated by climate change. Phytohormone priming and the complex crosstalk networks governed by transcription factor hubs like WRKY, MYB, and NAC serve as the central adaptive mechanism for stress resilience. This review synthesizes how multi-omics integration, including spatial and single-cell transcriptomics, is resolving the molecular architecture of hormonal priming and epigenetic stress memory. We critically evaluate advanced metabolic engineering and genome-editing strategies such as CRISPR-Cas9, base/prime editing, and synthetic gene circuits that enable precision modifications to decouple stress tolerance from historical yield penalties. Furthermore, we discuss the emerging roles of microbiome-assisted priming via synthetic consortia and the application of artificial intelligence and digital twins (continuously updated computational models of crop physiology) for predictive stress management. By integrating these diverse technological pillars, we propose a systems-level roadmap for developing climate-resilient rice cultivars capable of maintaining yield stability across a volatile combinatorial stress landscape. This synthesis provides a framework for translating mechanistic hormonal insights into field-applicable cultivars to ensure global food security.

CRISPR↗
PubMed2000

Quantitative trait loci for root-penetration ability and root thickness in rice: comparison of genetic backgrounds.

Drought is the major abiotic stress limiting rice (Oryza sativa) production and yield stability in rainfed lowland and upland ecosystems. Root systems play an important role in drought resistance. Incorporation of root selection criteria in drought resistance improvement is difficult due to lack of reliable and efficient screening techniques. Using a wax-petrolatum layer system simulated to compacted soil layers, root traits were evaluated in a doubled haploid (DH) population derived from the cross between 'IR64' and 'Azucena'. Twelve putative QTLs (quantitative trait loci) were detected by interval mapping comprising four QTLs for root-penetration ability, four QTLs for root thickness, two QTLs for penetrated root number, and two QTLs for total root number. These QTLs individually explained 8.4% to 16.4% of the phenotypic variation. No QTL was detected for maximum penetrated root length by interval mapping. One QTL located between RG104 and RG348 was found to influence both root-penetration ability and root thickness. QTLs for root-penetration ability and root thickness were compared across two populations, 'IR64'-'Azucena' and 'CO39'-'Moroberekan', and different testing conditions. The identified consistent QTLs could be used for marker-assisted selection for deep and thick roots with high root-penetration ability in rice.

Oryza↗
PubMed2004

Genetic dissection for leaf correlative traits of rice (Oryza sativa L.) under drought stress.

Water is becoming a restricted factor of agricultural development owing to the global shortage of water resources. Screening and improving drought tolerant rice cultivars would be helpful for increasing and stabilizing yield, economizing water and reducing environmental pollution. In this study, 127 rice lines of DII population derived from an indica variety Zhaiyeqing 8 (ZYQ8) and a japonica variety Jingxi 17 (JX17) were used to locate QTLs for leaf rolling, relative water content and rate of electric conductivity under drought stress. The results showed that significant differences between the parents were detected for all measured traits. The tremendous transgressive segregations for these traits were observed in the population. The frequency of all traits in the population was approximately normally distributed with slight skew. A total of six QTLs for the three traits were detected with molecular linkage map of 234 markers, including three QTLs (qLR-1, qLR-5 and qLR-11) for leaf rolling, two QTLs (qRWC-1 and qRWC-6) for relative water content and one QTL (qREC-6) for rate of electric conductivity. Visual measurement for leaf rolling can be used to screen a large number of rice germplasm resources or varieties, which is of importance to screening and utilization of drought tolerant rice varieties.

Alleles↗
PubMed1984

Purification of rat liver microsomal cytochrome P-450 by chromatography on immobilized adamantane with a new method of detergent removal.

A method for the isolation of liver microsomal cytochrome P-450 from phenobarbital-treated rats is described which is based on chromatography on 1-adamantane-carbonyl-aminohexyl-Sepharose 4B, subsequent ion exchange chromatography on DEAE-cellulose and detergent removal by adsorption on silica gel G. The method gives preparations with high electrophoretic homogeneity which correspond to a major phenobarbital-inducible form of rat liver microsomal cytochrome P-450. The advantages of the procedure described are high yields, stability of chromatographic material, effective and simple method of detergent removal.

Adamantane↗
PubMed1994

[Cassava evaluation as a non conventional resource for food industry].

Mean results of the chemical composition of cassava cultivated in the different regions of Mexico are presented and the most important ingredient is starch which permits that this natural resource is employed as a no-conventional ingredient in food industry, for dextrins, glucose and fructose syrups production. Cassava starch is used for baby foods, salsa and mayonnaise manufacture. Because of its physico-chemical properties, modified starches are employed in bakery for pies, refills and frozen foodstuffs production and have been considered as stabilizers, yielding a final product which is maintained fresh and of excellent texture.

Food Analysis↗
PubMed2005

Specimen charging in X-ray absorption spectroscopy: correction of total electron yield data from stabilized zirconia in the energy range 250-915 eV.

The effects of specimen charging on X-ray absorption spectroscopy using total electron yield have been investigated using powder samples of zirconia stabilized by a range of oxides. The stabilized zirconia powder was mixed with graphite to minimize the charging but significant modifications of the intensities of features in the X-ray absorption near-edge fine structure (XANES) still occurred. The time dependence of the charging was measured experimentally using a time scan, and an algorithm was developed to use this measured time dependence to correct the effects of the charging. The algorithm assumes that the system approaches the equilibrium state by an exponential decay. The corrected XANES show improved agreement with the electron energy-loss near-edge fine structure obtained from the same samples.

Journal Article↗