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At least 73 records · Page 4Linked to original sources
PubMed2000

Effect of kinetin concentration and methods of application on seed germination, yield components, yield and fiber properties of the Egyptian cotton (Gossypium barbadense).

Two field experiments in 1993 and 1994 as well as a laboratory germination experiment were conducted on the Egyptian cotton cultivar Giza 75 (Gossypium barbadense) to determine the effect of six concentrations of kinetin (6-furfurylaminopurine) ranging from 0 to 10.0 mg l(-1) and three different methods of application: (A) seeds were soaked for 24 h before germination (laboratory experiment) or sowing (field experiment) in solutions of different kinetin concentration, (B) cotton plants were sprayed twice with different kinetin concentrations at 60 and 75 days after sowing (DAS) during the square initiation and the beginning of bolling stages, at volume solution of 480 l ha(-1). (C) Seeds were soaked in kinetin solutions before sowing as method A. In addition cotton plants were sprayed twice as method B with the same kinetin concentrations. Kinetin application improved seed viability and seedling vigour as shown by lengths of the hypocotyl, radicle and the entire seedling, as well as seedling fresh weight. Moreover, significant increases were recorded in the number of open bolls/plant, boll weight, lint and seed indices, seed cotton yield/plant, and seed cotton and lint yields/plot. The highest means were obtained at 5 mg kinetin l(-1) concentration and under method C of application. Treatments generally, had no significant effects on lint percentage, yield earliness and fiber properties. These results show that, the use of kinetin at 5 mg l(-1) for pre-soaking seeds before planting and spraying cotton plants at 60 and 75 DAS with the same concentration could improve cotton germination, seed cotton and lint yields.

Journal Article↗
PubMed2003

The low-light reduction in the quantum yield of photosynthesis: potential errors and biases when calculating the maximum quantum yield.

Photosynthesis-irradiance (P-E) curves are widely used to describe photosynthetic efficiency and potential. Contemporary models assume maximal photosynthetic quantum yield (phi) at low irradiances. But P-E observations made with both oxygen evolution and carbon uptake techniques show that this is not always the case. Using new and published data in conjunction with modeling exercises, we demonstrate that regardless of the mechanism there can be reductions in phi at low irradiances that are not readily observable using conventional P-E analyses. We also show that analytical errors, such as inaccurate estimation of dark oxygen consumption or carbon uptake, can markedly affect the structure of phi-E curves with negligible effect on P-E curve structure. Whether from respiration ;corrections' or other mechanisms, these deviations in phi at low light levels from the maximum quantum yield of photosynthesis (phi(max)) can lead to significant errors (> 50%) in the estimation of the linear portion of the P-E curve and ultimately phi(max). Non-linear models of P-E, such as the rectangular hyperbola, quadratic, exponential and hyperbolic tangent that are commonly used to estimate the initial slope (alpha) of the P-E curve assume that phi is maximal at low light levels and therefore can err in the estimation of phi(max) when phi is reduced at low light levels. Using a diverse data set of 622 P-E curves with a total of 7623 points, we show that although model skills are high (r (2) = 0.96 +/- 0.05, 0.97 +/- 0.04, 0.97 +/- 0.04 and 0.97 +/- 0.04, respectively), a large fraction of the model-predicted phi(max) differ by greater than 10% from true phi(max) values (91%, 50%, 82% and 46%, respectively). Data from these observations and modeling exercises lead us to suggest that phi(max) be determined by directly estimating the true maximum of a phi-E curve rather than using the more conventional methodology employing the initial slope of the P-E curve.

Journal Article↗
PubMed1988

Hand-held computer program for field-capture and analysis of herbage yield and composition data using a modified dry-weight-rank and yield estimate method.

A BASIC program is described which is used to collect, check and analyse rank estimates of plant yield in the field. The program operates in a portable, battery-powered Sharp PC1500A hand-held computer than can be used in a field environment. Data are collected using a modified dry-weight-rank method and comparative yield estimates. Much of the software is designed to trap incorrect data entry. Raw data or summary data may be printed, displayed, and stored on cassette tape or transferred to another computer through a communications interface. The program can be easily modified to run on other models of the Sharp PC series or other portable computers that use a similar BASIC interpreter.

Algorithms↗
PubMed2004

The use of SSRs for predicting the hybrid yield and yield heterosis in 15 key inbred lines of Chinese maize.

A challenge to maize breeders is to predict and identify inbred lines that can produce highly heterotic hybrids precisely. In the present study we surveyed the genetic diversity among 15 elite inbred lines of maize in China with SSR markers and assessed the relationship between SSR marker and hybrid yield/yield heterosis in a diallel set of 105 crosses. Forty-three SSR primers selected from all sixty-three primers gave stable profiles amplified in the sample of 15 inbred lines, which could clearly resolve on 4% metaphor agarose gel. The average number of alleles per SSR locus was 4.44 with a range from 2 to 9. The polymorphism information content (PIC) for the SSR loci varied from 0.28 to 0.81 with a mean of 0.6281. Genetic similarity (GS) among 15 lines was estimated with 191 alleles identified as raw data, the Nei's coefficient of GS ranged from 0.492 for 478 vs HZ4 up to 0.745 for E28 to ZH64 with a mean of 0.619. The cluster diagram based upon the SSR data grouped the 15 lines into families consistent with the yield heterotic response of these. Genetic distance (GD) based on SSR data was significantly correlated with hybrid yield/yield heterosis, the correlation coefficient (r) being 0.5432 and 0.4271 in 1999 and 0.4305 and 0.3614 in 1998 field test, respectively, whereas the determination coefficient (r2) was lower. The correlation between GD based on SSR data and hybrid yield/yield heterosis changed alone with the difference of number and pedigree relationship among parents that were used in this study. SSR makers showed high polymorphism and could be used to assess the relationship between inbred lines of maize, but it was difficult to predict the yield heterosis of maize.

DNA, Plant↗
PubMed1983

Genetic correlations among progeny groups for type traits, milk yield, yield persistency, and culling rates.

Associations among six primipara type traits and first and second lactation milk yield, yield persistency, and culling rates were estimated by means of 100 progeny groups with first and 76 with second lactations. Correlations of second lactation culling rate with dairy character and with rear udder were approximately -.4. Persistency, measured in either first or second lactation, was negatively associated with all type traits.

Animals↗
PubMed1994

The influence of hydration on the absolute yields of primary free radicals in gamma-irradiated DNA at 77 K. II. Individual radical yields.

In this report we present an electron spin resonance (ESR) investigation of the yields of the individual free radicals formed in gamma-irradiated frozen DNA as a function of hydration and dose at 77 K. Analysis of the ESR spectra taken at low hydration shows that the ion radical composition remains nearly constant with dose and that few secondary radicals are formed even at high doses (above about 50 kGy). For fully hydrated samples, the radical composition changes dramatically with dose. Thymine anion radical (T-.) is found in abundance at low doses but nearly disappears at higher doses, with a corresponding increase in the N-3 deuterated cytosine anion radical (CD.). Guanine cation radical (G+.) decreases at high doses, with a concomitant increase in secondary radical species (S.). Analysis of the dose-response data for G values (the yields in microM/J), k values (the destruction constants) and k' values (a new constant that characterizes the change in G with dose) was performed for each of the DNA base free radicals present at 77 K. The G value for each of the base radicals increases with the hydration level. The k values for CD. and G+. increase slightly with hydration; however, that of T-. increases substantially. Destruction constants for neutral radicals such as TH. and CD. are found to be substantially smaller than those for ion radicals and provide an indication of the radical charge state. A negative k' value for T-. and a positive k' value for CD. are explained in terms of radiation effects that result in the formation of a deuterated cytosine base, i.e., C(N3)D+, which greatly increases cytosine's electron affinity. The ratio of anion radical to cation radical concentrations is found to be about 1.6 and is invariant with hydration. A speculation on the imbalance based on hole-hole combinations in spurs is presented.

DNA↗
PubMed2005

Correlation of free radical yields with strand break yields produced in plasmid DNA by the direct effect of ionizing radiation.

The purpose of this study was to determine how free radical formation (fr) correlates with single strand break (ssb) and double strand break (dsb) formation in DNA exposed to the direct effects of ionizing radiation. Chemical yields have been determined of (i) total radicals trapped on DNA at 4 K, G(Sigmafr), (ii) radicals trapped on the DNA sugar, Gsugar(fr), (iii) prompt single strand breaks, Gprompt(ssb), (iv) total single strand breaks, Gtotal(ssb), and (v) double strand breaks, G(dsb). These measurements make it possible, for the first time, to quantitatively test the premise that free radicals are the primary precursors to strand breaks. G(fr) were measured by EPR applied to films of pEC (10,810 bp) and pUC18 (2686 bp) plasmids hydrated to Gamma = 22 mol of water/nucleotide and X-irradiated at 4 K. Using these same samples warmed to room temperature, strand breaks were measured by gel electrophoresis. The respective values for pEC and pUC18 were G(fr) = 0.71 +/- 0.02 and 0.61 +/- 0.01 micromol/J, Gtotal(ssb) = 0.09 +/- 0.01 and 0.14 +/- 0.01 micromol/J, G(dsb) = 0.010 +/- 0.001 and 0.006 +/- 0.001 micromol/J, and Gtota)(ssb)/G(dsb) approximately 9 and approximately 20. Surprisingly, Gsugar(fr) approximately 0.06 mumol/J for pUC18 films, less than half of Gtotal(ssb). This indicates that a significant fraction of strand breaks are derived from precursors other than trapped DNA radicals. To explain this disparity, various mechanisms were considered, including one that entails two one-electron oxidations of a single deoxyribose carbon.

DNA↗
PubMed1981

[Effect of the copper status on the reproduction performance and the milk yield of cows in 2 copper-deficient locations. 2. Effect of copper deficiency on the reproduction performance and the milk yield of cows].

The influence of copper deficiency on the reproduction performance of cows has not often been investigated. In two habitats feeding cows with mineral mixtures rich in copper resulted in a significant reduction of the aperiodically extended sexual cycles. The beginning of the first visible symptoms of heat, the period between gravidities, the duration of gravidity, the birth weight of the calves and the Cu-content of the colostrum remained uninfluenced by Cu-supply. The liver weight increase of the calves from cows without Cu-supplement during gravidity was by 5% lower during the first 90 days of life than that of the offspring of cows with additional intrauterine Cu-supply (p greater than 0.05). The mineral mixture increased the milk yield by 0.4 resp. 0.5 kg and the milk fat content by 0.10 resp. 0.13%. This resulted in an excess production of 32 resp. 62 g milk fat per cow and day of the experiment (p greater than 0,05).

Animals↗
PubMed1989

Quantum yields for laser photocyclization of bilirubin in the presence of human serum albumin. Dependence of quantum yield on excitation wavelength.

The quantum yield for laser photocyclization of bilirubin to lumirubin in the presence of human serum albumin (phi LR) was measured at five monochromatic excitation wavelengths in the range 450-530 nm. Solutions used were optically thin throughout the wavelength range and precautions were taken to exclude contributions from photocyclization of bilirubin XIII alpha impurities. The values obtained (7.2-18 x 10(-4] were lower than those previously reported and showed the following wavelength dependence: 457.9 less than 488.0 less than 501.7 less than 514.5 approximately equal to 528.7. However, the rate of lumirubin formation, normalized to constant fluence, decreased with wavelength over the same wavelength range and no evidence was found that photoisomerization of bilirubin to lumirubin is faster with green (514.5 or 528.7 nm) than with blue (457.9 or 488.0 nm) light. The stereoselectivity of the configurational isomerization of bilirubin to 4Z,15E and 4E,15Z isomers also was studied. This reaction became less regioselective for the 4Z,15E isomer with increasing wavelength. The observed wavelength dependence of phi LR and of the [4E,15Z]: [4Z,15E] ratio at photoequilibrium are consistent with an exciton coupling model in which intramolecular energy transfer can occur between the two pyrromethenone chromophores of the bilirubin molecule in the excited state. Relative rates of lumirubin formation in vivo at different excitation wavelengths and constant fluence were estimated for different optical thicknesses and for different skin thicknesses. These estimates suggest that the recently reported clinical equivalence of blue and green phototherapy lights probably reflects the marked variation of skin transmittance with wavelength more than wavelength-dependent photochemistry. The calculations also indicated that the optimal wavelength for phototherapy is probably on the long wavelength side of the bilirubin absorption maximum.

Bilirubin↗
PubMed1999

Accuracy of application of USDA beef quality and yield grades using the traditional system and the proposed seven-grade yield grade system.

Beef carcasses (n = 5,542) were evaluated by three USDA on-line graders and compared with the computed expert USDA quality (QG) and yield grades (YG) during 8-h shifts at a major beef-processing facility for a 2-wk period to evaluate the accuracy of applying USDA QG and YG within the traditional five-grade and the proposed seven-grade (segregating YG 2 and 3 into YG 2A, 2B, 3A, and 3B) YG systems. Quality grade distribution of the carcasses was 1.1% Prime, 50.0% Choice, 43.8% Select, and 5.1% No-Roll. Accuracy of applying QG was not affected (P>.05) by changing from the five-grade (91.5%) to either the seven-grade system, when determining only QG (94.3%), or the seven-grade system, when determining QG and YG (95.0%). Calculated expert YG successfully segregated carcasses into their respective YG, but on-line graders could not differentiate between YG 4 and 5 in the seven-grade systems. The application of YG in the five-grade system was more accurate (P<.05) than either of the seven-grade systems. A trend existed for on-line graders to undergrade carcasses as the numerical YG increased. Total accuracy of applying YG decreased by 19.4 to 21.8% when switching from the five-grade to the seven-grade system. The segmentation of USDA YG 2 and 3 into YG 2A, 2B, 3A, and 3B resulted in a decrease in the ability of on-line graders to accurately apply the YG.

Animals↗
PubMed1998

A high yield of translocations parallels the high yield of sister chromatid exchanges in the CHO mutant EM9.

The fluorescence plus Giemsa (FPG) and fluorescence in situ hybridization (FISH) techniques have been used to determine, respectively, the frequencies of sister chromatid exchanges (SCEs) and stable chromosome aberrations (translocations) induced by different concentrations of BrdU in the Chinese hamster ovary cell mutant EM9 and its parental line AA8. The results indicate that BrdU induced a high frequency of SCEs and translocations in EM9 as compared with AA8, and that the translocation/dicentric ratio was also higher in the mutant cell line than in the parental cell line in both untreated and BrdU-treated cultures. These observations may indicate a possible relationship between the molecular mechanisms involved in the formation of SCEs and translocations.

Animals↗
PubMed2002

[Fears of pregnant women if prenatal examination yields or does not yield any findings].

OBJECTIVE: Besides a medical point of view, prenatal diagnosis also has psychological effects on the pregnant woman. We studied the state of anxiety before and after prenatal examination with unsuspicious and suspicious prenatal findings. MATERIAL AND METHODS: In a consecutive sample of 332 pregnant women presenting between the 12th and 21st week of gestation for prenatal malformation scan (level three reference centre, Unit for Prenatal Medicine, Department of Obstetrics and Gynaecology, Medical University of Lübeck) we ascertained state and trait anxiety (Spielberger) before prenatal examination and state anxiety after prenatal examination with unsuspicious and suspicious findings. RESULTS: In the sample of N = 332 pregnant women prenatal examination showed a suspicious finding in 37 fetuses (11.1 %) and an unsuspicious finding in 295 fetuses (88.9 %). Before prenatal examination there is no difference (Mann-Whitney-Test, P = 0.286) between the group with negative results and the pregnant women with a positive result for the trait anxiety scale; however, there is a significant difference (Mann-Whitney-Test, P = 0.014*) for the scale of state anxiety. After prenatal examination the evaluation of the state anxiety questionnaire shows a significant (Mann-Whitney-Test, P = 0.000*) difference between pregnant women with an unsuspicious finding and pregnant women with a suspicious finding. State-anxiety is significantly reduced after examination if the prenatal scan is unsuspicious (Wilcoxon-Test, P = 0.000*), but there is no significant difference between pre-and post-examination anxiety if there is a positive finding (Wilcoxon-Test, P = 0.399). Evaluating aspects of anxiety as regards content, it can be demonstrated that before prenatal examination the pregnant women are just as much afraid of a malformation being detected as of it being missed. CONCLUSIONS: Suspecting or knowing about a malformation of the unborn means a complex process of coping and an intense psychosocial strain for a pregnant woman. Besides the fear of a detected malformation the pregnant women state equal fear of a malformation being missed. In contrast to this the immediate feedback of a negative finding during ultrasound examination leads to a significant reduction of anxiety and to an emotional relief for the pregnant woman.

Adult↗
PubMed2003

Influence of diet on growth yields of rumen micro-organisms in vitro and in vivo: influence on growth yield of variable carbon fluxes to fermentation products.

The efficiency of rumen microbial production (EMP) in vitro and in vivo was examined for three roughages (lucerne (Medicago sativa L.) hay, oat (Avenia sativa L.)-berseem clover (Trifolium alexandrinum cultivar BigBee) hay and maize (Zea mays L.) crop residue (MCR)) and for five isonitrogenous (106 g crude protein (Nx6.25)/kg) diets formulated from lucerne hay, oat-berseem clover hay, MCR, soybean meal and maize grain to provide degradable intake protein for the production of 130 g microbial protein/kg total digestible nutrients. EMP in vivo was determined by intestinal purine recovery in sheep and ranged from 240 to 360 g microbial biomass/kg organic matter truly degraded in MCR and in one of the diets respectively (P<0.05). EMP in vitro was estimated by the substrate degraded : gas volume produced thereby (termed partitioning factor, PF (mg/ml)) at times of estimated peak microbial production and after 16.0 and 24.0 h of incubation. For the diets, PF values were significantly related to EMP in vivo at peak microbial production (P=0.04), but not after 16.0 (P=0.08) and 24.0 h (P=0.66). For roughages, PF values were significantly related to EMP in vivo only when measured after 16.0 h (P=0.04). For MCR and diets, a close non-linear relationship was found between PF values at peak microbial production and EMP in vivo (R(2) 0.99, P<0.0001) suggesting a maximum EMP in vivo of 0.39. Low gas production per unit substrate degraded (high PF) was associated with high EMP in vivo. The in vitro study of the products of fermentation, short-chain fatty acids, gases and microbial biomass (by purine analysis) after 16.0 h of incubation showed very strong relationships (R(2)> or =0.89, P<0.0001) between short-chain fatty acids, gases and gravimetrically measured apparent degradability. Except for maize grain, the true degradability of organic matter estimated by neutral-detergent solution treatment agreed with the sum of the products of fermentation (R(2) 0.81, P=0.0004). After 16.0 h of incubation, the synergistic effects of diet ingredient on diets were greater for microbial biomass (18 %) than for short-chain fatty acids and gas production (7 %). It is concluded that measurement of gas production only gives incomplete information about fodder quality; complementation of gas measurements by true degradability measurements is recommended.

Ammonia↗