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PubMed2005

Controlling optical properties and interchain interactions in semiconducting polymers by encapsulation in periodic nanoporous silicas with different pore sizes.

The photophysics of MEH-PPV incorporated into the pores of periodic silica hosts has been investigated in an effort to understand the role played by interchain aggregation and chain morphology in polaron production. In this work, guest/host interactions were used to incorporate MEH-PPV into the straight, homogeneous pores of hexagonal surfactant- or polymer-templated mesoporous silicas of varying pore diameters. Polarized photoluminescence and photoluminescence excitation spectroscopy were then used to investigate the polymers' environment within the silica pores. Experiments exploiting luminescence peak shifts and depolarization indicate that depending on the pore size and preparation conditions, the alignment and packing of the polymer chains within the pores could be controlled. Samples could be produced with isolated chains, interacting straight chains, and coiled interacting chains. The sub-bandgap absorption by polarons was then measured with photoinduced absorption as a function of pore size. Small-diameter pores that allowed single polymer chains to reside within the pore showed little evidence of interchain contact and had a low polaron yield. Increasing the number of polymer chains within the pore increased the polaron yield. Finally, when the pores were large enough that the chains could coil, strong polaron absorption was observed, indicative of a further increase in polaron yield or an increase in polaron lifetime. The polaron absorption spectra also sharpen and red shift with increasing pore diameter, suggesting that excitons may migrate to lower energy polymer segments in samples where polymer chains are both coiled and interacting.

Journal Article↗

PubMedDate not supplied

Increasing the yield of Eimeria tenella oocysts in primary chicken kidney cells.

The present study was undertaken to increase the yield of Eimeria tenella oocysts in primary chicken kidney cells (PCKCs) using a comparatively inexpensive cell-culture system. PCKCs growing on coverslips positioned on the bottoms of individual wells in 24-well tissue-culture plates were infected with sporozoites of E. tenella. The effects of changing the culture medium (RPMI 1640), medium pH, serum type, and serum concentration in the wells were determined by counting newly produced oocysts at 7 days postinoculation. There were significantly more (P < 0.01) oocysts produced when the medium was supplemented with 10% fetal bovine serum (FBS) and changed either daily or every other day compared with not changing the medium. When the same medium was changed daily, significantly more (P < 0.05) oocysts were produced at pH 7.4 than at pH 8.0 but not at pH 6.0. If the medium was changed daily, significantly more (P < 0.05) oocysts were produced when medium was supplemented with 10% FBS only rather than 5% and 10% chicken serum. The cell-culture system described in this study offers a convenient and efficient method for investigating the biological, biochemical, and immunological relationships between E. tenella and the host cell.

Animals↗

PubMed1989

Fluorescent molecular rotors: a new class of probes for tubulin structure and assembly.

9-(Dicyanovinyl)julolidine (DCVJ) is a fluorescent dye whose intramolecular rotational relaxation is solvent dependent. Since its quantum yield increases with decreasing free volume, this molecule has been very useful in monitoring synthetic polymer reactions and measuring local microviscosity changes in phospholipid bilayers [Loutfy, R. O. (1986) Pure Appl. Chem. 58, 1239-1248; Kung, C. E., & Reed, J. K. (1986) Biochemistry 25, 6114-6121]. We have used DCVJ to follow the polymerization of tubulin, a protein that can assemble into a variety of polymorphic microstructures. DCVJ binding to free tubulin is accompanied by an increase in quantum yield, indicating that DCVJ has become partially immobilized. At 4 degrees C, DCVJ binds to a single population of high-affinity hydrophobic sites (Kd = 1.12 +/- 0.26 microM) with a stoichiometry that is protein concentration dependent. n, the number of moles of DCVJ bound per mole of alpha beta dimer, approaches 1 at concentrations less than or equal to 0.5 mg/mL but decreases to a lower limit of approximately 0.3 at concentrations greater than or equal to 2.0 mg/mL. The quantum yield also increases with increasing protein concentration. This trend is unaltered by the presence of microtubule-associated proteins. These results are analyzed in terms of a concentration-dependent oligomerization of tubulin at 4 degrees C. When tubulin is polymerized at 37 degrees C to microtubules or to sheets in the presence of Zn2+, the fluorescence intensity of DCVJ increases although the magnitude of this increase differs significantly. We are able to use the distinct fluorescent and binding characteristics of the bound dye to distinguish between these two polymorphs on a molecular level.

Animals↗

PubMed2005

Identification and physiological analyses of a locus for rice yield potential across the genetic background.

A new locus responsible for increased yield potential across the genetic background in rice (Oryza sativa L.) was identified and evaluated. Quantitative trait loci (QTLs) were analysed for the ratio of filled grains, a yield component, in backcrossed inbred lines of a japonica 'Nipponbare'xindica 'Kasalath' cross for 3 years. Only one QTL (rg5), with a positive Kasalath allele, was detected across environments (years). The physiological functions of rg5 were clarified in a near-isogenic line (NILrg5) with a Kasalath chromosome segment containing rg5 in a Nipponbare genetic background. In NILrg5, carbohydrate storage capacity before heading or sink activity in the first or last stages of the reproductive phase was significantly higher than in Nipponbare (control). The ratio of filled grains and yield per plant were significantly higher in NILrg5 than in Nipponbare, by 5% (P <0.01) and 15% (P <0.05), respectively. These results suggest that rg5 improves carbohydrate storage capacity and keeps sink activity higher in the reproductive stage, and consequently increases yield potential. Greater capacity to accumulate carbohydrate is the main target for increasing rice yield potential; therefore, rg5 might function under other genetic backgrounds. Substitution of the rice cv. Kasalath chromosome segment containing rg5 gave higher yield potential in the top premium rice cv. Koshihikari. These results suggest that rg5 might be able to affect yield under different genetic backgrounds, and physiological analyses of the targeted locus might reveal these effects.

Carbohydrate Metabolism↗

PubMed1996

Eukaryotic protein disulfide isomerase complements Escherichia coli dsbA mutants and increases the yield of a heterologous secreted protein with disulfide bonds.

Eukaryotic protein disulfide isomerase (PDI) is a 55-kDa enzyme with cysteine oxidoreductase, chaperone, and antichaperone activities that catalyzes disulfide formation and rearrangement in the eukaryotic endoplasmic reticulum. In Gram-negative bacteria, the formation of disulfide bonds in the periplasm is mediated by DsbA, a strong cysteine oxidase but an inefficient catalyst of disulfide bond isomerization with no known chaperone activity. We show that rat PDI (rPDI) secreted in the periplasmic space of Escherichia coli can catalyze the formation of disulfide bonds and complement several of the phenotypes of dsbA mutants. The function of rPDI was dependent on the dsbB gene, suggesting that the reoxidation of this eukaryotic enzyme involves direct interactions with bacterial redox proteins. Co-expression of rPDI increased the yield of bovine pancreatic trypsin inhibitor (BPTI) severalfold, an effect that was enhanced when reduced glutathione was added to the growth medium. Whereas PDI is thought to function primarily as an isomerase in the eukaryotic endoplasmic reticulum, rPDI failed to decrease the accumulation of two-disulfide folding intermediates of BPTI and thus did not appear to appreciably catalyze the rate-limiting step in the oxidative folding pathway of BPTI. These results demonstrate that expression of eukaryotic foldases in E. coli can be exploited to better understand their function in vivo and also to increase the yield of biotechnologically valuable proteins.

Animals↗

PubMed1999

Applied studies of the plant meridian system: II. Agri-wave technology increases the yield and quality of spinach and lettuce and enhances the disease resistant properties of spinach.

Agri-wave technology is composed of both a special frequency sound wave and a microelement fertilizer. In both components, the effect of sound waves on plants is more than that of fertilizers, but the best function is a combination of the two. Treatment by Agri-wave technology stimulated the growth rate and increased the yield of spinach. In small plot tests, the length and width of the treated spinach leaf was 50.8 cm and 20.3 cm, respectively, whereas the untreated leaves were 29.20 cm and 8.9 cm. The fresh weight of treated spinach was 0.42 kg. This was 5.5 times higher than that of the untreated spinach. In large area testing (17 hectares), the results of two tests show that the yields of the treated spinach were increased 22.7% and 22.2% over those of the control group. Sugar content of the treated spinach was increased by 37.5%, vitamin A, C, and B were increased 35.63%, 41.67% and 40.00%, respectively, above the levels of the control group. Niacin content was decreased by 7.69%. Of 33 elements analyzed in the spinach, 29 elements were increased by Agri-wave technology. The spinach was infected with "rot disease" in the control group while there was no disease present in the treated group. In greenhouse testing, the average weight of 3 species of lettuce treated by Agri-wave technology was increased 44.10% over that of the control group (P < 0.0001). The average weight of 3 species of lettuce by only sound and only fertilizer treated separately increased 29.92% and 16.19% above that of the control group (P < 0.0001). Sampling survey results in the field test were comparable to the above mentioned greenhouse test. The fresh weight of treated lettuce by Agri-wave technology was increased 41.67% over that of the control group (P < 0.0001). The fresh weight of treated lettuce by only sound and only fertilizer was increased 30.88% and 19.61%, respectively, over the control group (both P < 0.0001).

Agriculture↗

PubMed2006

Secondary organic carbon and aerosol yields from the irradiations of isoprene and alpha-pinene in the presence of NOx and SO2.

A laboratory study was carried out to investigate the secondary organic carbon (SOC) yields of alpha-pinene and isoprene in the presence of SO2, which produces acidic aerosol in the system. Experiments were based on irradiating each hydrocarbon (HC) with NOx in a 14.5 m3 smog chamber operated in the dynamic mode. The experimental design consisted of several multi-part experiments for each HC. In the first part of each experiment, an HC/NOx irradiation was conducted in the absence of SO2 and was followed by irradiations with the addition of SO2 in subsequent parts. Filter-based analyses for organic carbon were made using a thermal-optical approach either with an off-line instrument or in situ with an automated instrument. For isoprene in the absence of SO2, the SOC yield was approximately 0.001, a value consistent with earlier work from this laboratory. With the addition of up to 200 ppb SO2, the yield increased by a factor of 7. For alpha-pinene in the absence of SO2, the SOC yield of the irradiated mixture was found to average 0.096 from two experiments. With SO2 in the system, the SOC yield increased on average to 0.132. These results suggest that SO2, and by inference acidic aerosol, may play a role in increasing the yield of SOC from the photooxidation products of biogenic hydrocarbons or by the direct uptake of biogenic hydrocarbons onto acidic aerosol.

Aerosols↗

PubMed1981

Contrast effects in photoelectron microscopy; UV dose-dependent quantum yields of biological surface components.

The relative brightness of photoelectron microscopy images as a function of exposure to UV light has been determined from model systems representative of biological cell surface components. Quantitative data for amino acid homopolymers, yields. The photoelectron quantum yields, increase substantially over the initial values. For example, the quantum yields fo poly-L-tyrosine at 200 nm is initially about 5 X 10(-8) electron/incident photon. The quantum yield increases with 254 nm irradiation, leveling off at about 5 X 10(-4) electrons/incident photon after a dose of 3 X 10(21) quanta cm-2. Pre-irradiation of poly-L-tyrosine in the presence of certain chemical agents, for example, the Lewis base diborane (B2H6), results in a substantial reduction of the dose-dependent increase in quantum yield. Exposure to the reducing agent stannane (SnH4) essentially eliminates the effect. These chemical treatments provide methods of controlling the UV dose-dependent effects in the photoelectron images.

Amino Acids↗

PubMed2006

Can improvement in photosynthesis increase crop yields?

The yield potential (Yp) of a grain crop is the seed mass per unit ground area obtained under optimum growing conditions without weeds, pests and diseases. It is determined by the product of the available light energy and by the genetically determined properties: efficiency of light capture (epsilon i), the efficiency of conversion of the intercepted light into biomass (epsilon c) and the proportion of biomass partitioned into grain (eta). Plant breeding brings eta7 and epsilon i close to their theoretical maxima, leaving epsilon c, primarily determined by photosynthesis, as the only remaining major prospect for improving Yp. Leaf photosynthetic rate, however, is poorly correlated with yield when different genotypes of a crop species are compared. This led to the viewpoint that improvement of leaf photosynthesis has little value for improving Yp. By contrast, the many recent experiments that compare the growth of a genotype in current and future projected elevated [CO2] environments show that increase in leaf photosynthesis is closely associated with similar increases in yield. Are there opportunities to achieve similar increases by genetic manipulation? Six potential routes of increasing epsilon c by improving photosynthetic efficiency were explored, ranging from altered canopy architecture to improved regeneration of the acceptor molecule for CO2. Collectively, these changes could improve epsilon c and, therefore, Y p by c. 50%. Because some changes could be achieved by transgenic technology, the time of the development of commercial cultivars could be considerably less than by conventional breeding and potentially, within 10-15 years.

Biomass↗

PubMed2005

Expression of an Arabidopsis vacuolar sodium/proton antiporter gene in cotton improves photosynthetic performance under salt conditions and increases fiber yield in the field.

Drought and salinity are two major limiting factors in crop productivity. One way to reduce crop loss caused by drought and salinity is to increase the solute concentration in the vacuoles of plant cells. The accumulation of sodium ions inside the vacuoles provides a 2-fold advantage: (i) reducing the toxic levels of sodium in cytosol; and (ii) increasing the vacuolar osmotic potential with the concomitant generation of a more negative water potential that favors water uptake by the cell and better tissue water retention under high soil salinity. The success of this approach was demonstrated in several plants, where the overexpression of the Arabidopsis gene AtNHX1 that encodes a vacuolar sodium/proton antiporter resulted in higher plant salt tolerance. Overexpression of AtNHX1 increases sodium uptake in vacuoles, which leads to increased vacuolar solute concentration and therefore higher salt tolerance in transgenic plants. In an effort to engineer cotton for higher drought and salt tolerance, we created transgenic cotton plants expressing AtNHX1. These AtNHX1-expressing cotton plants generated more biomass and produced more fibers when grown in the presence of 200 mM NaCl in greenhouse conditions. The increased fiber yield was probably due to better photosynthetic performance and higher nitrogen assimilation rates observed in the AtNHX1-expressing cotton plants as compared with wild-type cotton plants under saline conditions. Furthermore, the field-grown AtNHX1-expressing cotton plants produced more fibers with better quality, indicating that AtNHX1 can indeed be used for improving salt stress tolerance in cotton.

Adaptation, Physiological↗

PubMed2001

Combined effect of operational variables and enzyme activity on aqueous enzymatic extraction of oil and protein from soybean.

The individual effect of two different enzymes-protease and cellulase-on oil and protein extraction yields combined with other process parameters-enzyme concentration, time of hydrolysis, particle size and solid-to-liquid ratio-was evaluated by Response Surface Methodology. The selection of the enzymes for the study was based on preliminary experiments that showed higher increments in the extraction yield with the use of the two enzymes when compared to hemicellulase and pectinase. The levels of the quantitative parameters studied were: i) enzyme concentration: 0.1, 0.45, 2 w/w %; ii) liquid-to-solid ratio: 0.05, 0.125, 0.2; iii) mean particle size: 212.5, 449.5, 855 µm; iv) time of hydrolysis: 30; 60; 120 min. Experimental data for both oil and protein extraction yields obtained with and without enzymes correlated very well with process parameters (P < 0.0001), resulting in models with high coefficient of determination for oil and protein extraction yields (r(2) = 0.9570 and r(2) = 0.9807, respectively). The use of protease resulted in significantly higher yields over the control (protein yield increased from 27.8 to 66.2%, oil yield increased from 41.8 to 58.7%) only when heat treated flour was used, or when non-heat treated flour with large particle sizes was used in the extraction. The yields of protein and oil from non-heat treated material in general decreased slightly with the use of enzymes.

Journal Article↗

PubMed1996

Co-expression of human protein disulphide isomerase (PDI) can increase the yield of an antibody Fab' fragment expressed in Escherichia coli.

Secretion to the periplasm of Escherichia coli enables production of many eukaryotic extracellular proteins in a soluble form. The complex disulphide bond arrangement of such proteins is probably a major factor in determining the low yield of correctly folded product observed in many cases. Here we show that co-expression of human protein disulphide isomerase increased the yield of a monoclonal antibody Fab' fragment in the periplasm of E. coli.

Amino Acid Sequence↗

PubMed1995

Recombinant bovine somatotropin increases milk yield and calf gain in diverse breeds of beef cattle: associated changes in hormones and indices of metabolism.

In Exp. 1, Angus (A, n = 30), Charolais (C, n = 37), and Simmental (S, n = 30) multiparous cows received (s.c.) recombinantly derived bovine somatotropin (bST; sometribove, 500 mg) or vehicle (VEH) at 2-wk intervals from 124 to 228 d postpartum (DPP). Calves were weaned at 228 DPP. Bovine somatotropin increased (P < .01) milk yield and percentage of milk fat similarly in A, C, and S cows. Calf weaning weight was greater (P < .05) in cows treated with bST than in those given VEH. Administration of bST decreased deposition of fat and increased concentrations of IGF-I, insulin, glucose, and nonesterified fatty acids. In Exp. 2, we compared effects of bST initiated before or after the breeding season. Charolais (n = 33) and S (n = 40) cows were administered (at 2-wk intervals) VEH or bST beginning at 28 DPP (B-bST) or bST beginning at 105 DPP (A-bST). Calves were weaned at 243 DPP. Administration of bST before or after the breeding season increased milk yield on DPP 136 and 194; however, yields were greater in A-bST than in B-bST cows. Milk yields were similar in all cows at 236 DPP, corresponding to decreased forage availability. Calf body weight was greater (P < .05) in A-bST than VEH; B-bST calves were similar to VEH. Fat depth was greater in VEH than in bST-treated cows in C but not in S cows. Serum IGF-I was greater in A- and B-bST than in VEH cows. Mean days from calving to serum progesterone > 1 ng/mL and pregnancy rates were similar in VEH, A-, and B-bST cows. Administration of bST increased cow milk yield and subsequent calf weaning weight when initiated after 100 d postpartum. As anticipated, bST increased IGF-I, insulin, glucose, and nonesterified fatty acids. Administration of bST before and during the breeding season did not affect reproductive performance.

Animals↗

PubMed2003

Increasing the yield of soluble recombinant protein expressed in E. coli by induction during late log phase.

Recombinant mammalian proteins expressed in E. coli can be difficult to purify in high yield in a soluble and functional form. Various techniques have been described to prevent proteolysis of expressed proteins and/or their sequestering as insoluble aggregates within inclusion bodies. We report conditions for expressing recombinant proteins from E. coli that significantly enhanced the yield of soluble and functional protein. We demonstrate high-yield recovery of a native, high-molecular-weight RNA binding protein without the aid of fusion protein sequence. The principle factor that increased protein yield was the induction of protein expression in a late log phase culture, although reduced temperature during the induction and a low IPTG concentration also contributed to a higher yield.

Cell Culture Techniques↗

PubMed1989

Calcium, lanthanum, pyrophosphate, and hydroxyapatite: a comparative study in fibroblast mitogenicity.

Calcium-containing crystals and elevated levels of calcium chloride (CaCl2) and lanthanum chloride (LaCl3) have been previously reported to enhance the proliferative activity of cultured fibroblasts. We have investigated the relative mitogenicity of these agents, whether they function via precipitation on the cell surface and whether they interact with one another. Confluent cultures of newborn foreskin fibroblasts provided with fresh medium containing 10% fetal bovine serum (FBS) in the presence of hydroxyapatite (HA), pyrophosphate (PPi), LaCl3 (La), or additional CaCl2 (Ca) were all stimulated more than control cultures provided with fresh medium and 10% FBS alone as assessed by cell counts 5 days later. Increases in cell yield above the original confluent cell density were 316% for La, 271% for Ca, 189% for HA, 131% for PPi, and 45% for controls. Addition of fresh medium containing 10% FBS and epidermal growth factor or fresh medium containing 20% FBS as additional points of reference yielded increases of 204 and 107%, respectively, over original confluent density. Stimulation induced by La or Ca was significantly greater (P less than 0.001) than the stimulation induced by each of the other treatments. The same treatments added to confluent cultures without a change of medium also renewed mitotic activity, with La and Ca again the most mitogenic and approximately doubling the pretreatment cell yields. Cultures incubated in an inverted position to avoid cell contact with precipitates in the medium were also stimulated by La and Ca, but not by HA and PPi. When added to confluent cultures simultaneously supplemented with optimal additional Ca, La decreased Day 5 cell yields in a dose-dependent manner at low concentrations (0.03-0.2 mM) but increased cell yields over those obtained with 0.2 mM LaCl3 again in a dose-dependent manner at higher concentrations. Thus, while HA and PPi act via precipitation on the cell surface, the more mitogenic agents La and Ca function in solution and appear to stimulate cell division by different nonadditive mechanisms. These findings suggest multiple mechanisms of membrane participation in mitogen responsiveness and in density-dependent inhibition of growth.

Calcium Chloride↗

PubMed1984

Responses of Sorghum and Pennisetum Species to the N(2)-Fixing Bacterium Azospirillum brasilense.

Three field inoculation experiments, two in Florida and one in New Mexico, were conducted with Azospirillum brasilense Cd. Each of the Florida experiments evaluated two crop species. One species in each of the Florida experiments responded to inoculation with a significant dry matter yield increases of 11 to 24% and nitrogen yield increases of 9 to 39%. No inoculation response was noted in the New Mexico experiment. The responding species were Sorghum bicolor (L.) Moench (sorghum) and the interspecific hybrid between Pennisetum americanum (L.) K. Schum. (pearl millet) and P. purpureum Schumach. (napiergrass). Nonresponding species were pearl millet (Florida) and Sorghum sudanense (Piper) Staph. (New Mexico). Acetylene reduction activity of inoculated plots in Florida was low, showing no increase over the natural uninoculated background rates and, in one case, was negatively correlated with yield. Acetylene reduction activity was not measured in New Mexico. In Florida, A. brasilense populations were found to decline from 5 x 10 to 5 x 10 bacteria g of soil in about 3 weeks (quadratic regressions). Continued decline to less than 10 by week 5 indicated that the inoculated bacteria did not become established in the soil in high numbers. The A. brasilense population declined at about the same rate in the New Mexico experiment. The erractic inoculation responses in these experiments are similar to those observed in earlier work at the University of Florida. The lack of acetylene reduction activity response to inoculation and the rapid population decline of the inoculated bacteria suggest that N(2) fixation is not the major mechanism causing yield responses after inoculation.

Journal Article↗

PubMedDate not supplied

[Effect of humus and microbial inoculates on yield and nitrogen uptake by agricultural plants].

The application of humus had a positive effect on grain and straw yield of paddy and the yield increased with the increasing concentration of humus. The highest dose ((0,05%) corresponding to 1120 kg humus/ha significantly increased the grain and straw yield by 85 and 30 per cent over control. The efficiency of algal inoculation was enhanced in the presence of humus and recorded 41 per cent increase in yield over algae. The nitrogen uptake was also appreciably increased by grain and straw due to humus application. Humus at 0,05 per cent along with algae significantly increased the nitrogen uptake by paddy over algae alone. Root nodulation, growth and yield of gram crop were appreciably increased due to humus application. The grain and straw yield were increased due to humus (0,05%) application showing 32 and 41 per cent increase over control. The efficiency of Rhizobium inoculation was also improved in the presence of humus and the grain and straw yield was significantly increased.

Eukaryota↗

PubMed1987

Mammary growth during lactation: implications for increasing milk yield.

Milk yield is greatly influenced by the size of the mammary secretory cell population. In rats, proliferation of cells during early lactation may account for as much as three-quarters of the increase in daily milk yield between parturition and peak lactation; the remainder is due to increased activity of existing cells. Conversely, in goats, all the initial decline in milk yield after peak lactation can be attributed to loss of secretory cells. Increased frequency of milking enhances milk yield and reduces secretory cell loss, whereas goats hemimastectomized at peak lactation undergo compensatory changes in the remaining gland, which include a complete maintenance of cell number for at least 18 wk. Cell proliferation is increased in both cases, showing that mammary growth can occur during established lactation. The significance of this observation is discussed in relation to ways in which the milk yield of dairy animals might be increased.

Animals↗