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PubMed1997

Reverse action of ribonuclease T1 in frozen aqueous systems.

We have studied ribonuclease T1 (EC 3.1-27.3)-catalysed synthesis of guanylyl-(3'-->5')cytidine in frozen aqueous reaction mixtures at -10 degrees C and in solution at 0 degree C in order to investigate whether ribonuclease-catalysed synthetic reactions can take advantage of the yield-increasing effect of freezing as was reported for protease-catalysed peptide synthesis. Under frozen state conditions, substantially increased yields of GpC were obtained compared to the reactions in solution. From the fact that no irreversible hydrolysis of the 2'3'-cyclic donor was observed it can be concluded that transesterification of the newly formed phosphodiester bond is the most important yield-limiting factor in ribonuclease T1-catalysed dinucleoside phosphate synthesis.

Dinucleoside Phosphates↗

PubMed1991

Influence of the size of indigenous rhizobial populations on establishment and symbiotic performance of introduced rhizobia on field-grown legumes.

Indigenous rhizobia in soil present a competition barrier to the establishment of inoculant strains, possibly leading to inoculation failure. In this study, we used the natural diversity of rhizobial species and numbers in our fields to define, in quantitative terms, the relationship between indigenous rhizobial populations and inoculation response. Eight standardized inoculation trials were conducted at five well-characterized field sites on the island of Maui, Hawaii. Soil rhizobial populations ranged from 0 to over 3.5 x 10 g of soil for the different legumes used. At each site, no less than four but as many as seven legume species were planted from among the following: soybean (Glycine max), lima bean (Phaseolus lunatus), cowpea (Vigna unguiculata), bush bean (Phaseolus vulgaris), peanut (Arachis hypogaea), Leucaena leucocephala, tinga pea (Lathyrus tingeatus), alfalfa (Medicago sativa), and clover (Trifolium repens). Each legume was (i) inoculated with an equal mixture of three effective strains of homologous rhizobia, (ii) fertilized at high rates with urea, or (iii) left uninoculated. For soybeans, a nonnodulating isoline was used in all trials as the rhizobia-negative control. Inoculation increased economic yield for 22 of the 29 (76%) legume species-site combinations. While the yield increase was greater than 100 kg ha in all cases, in only 11 (38%) of the species-site combinations was the increase statistically significant (P </= 0.05). On average, inoculation increased yield by 62%. Soybean (G. max) responded to inoculation most frequently, while cowpea (V. unguiculata) failed to respond in all trials. Inoculation responses in the other legumes were site dependent. The response to inoculation and the competitive success of inoculant rhizobia were inversely related to numbers of indigenous rhizobia. As few as 50 rhizobia g of soil eliminated inoculation response. When fewer than 10 indigenous rhizobia g of soil were present, economic yield was significantly increased 85% of the time. Yield was significantly increased in only 6% of the observations when numbers of indigenous rhizobia were greater than 10 cells g of soil. A significant response to N application, significant increases in nodule parameters, and greater than 50% nodule occupancy by inoculant rhizobia did not necessarily coincide with significant inoculation responses. No less than a doubling of nodule mass and 66% nodule occupancy by inoculant rhizobia were required to significantly increase the yield of inoculated crops over that of uninoculated crops. However, lack of an inoculation response was common even when inoculum strains occupied the majority of nodules. In these trials, the symbiotic yield of crops was, on average, only 88% of the maximum yield potential, as defined by the fertilizer N treatment. The difference between the yield of N-fertilized crops and that of N(2)-fixing crops indicates a potential for improving inoculation technology, the N(2) fixation capacity of rhizobial strains, and the efficiency of symbiosis. In this study, we show that the probability of enhancing yield with existing inoculation technology decreases dramatically with increasing numbers of indigenous rhizobia.

Journal Article↗

PubMed1999

'Green revolution' genes encode mutant gibberellin response modulators.

World wheat grain yields increased substantially in the 1960s and 1970s because farmers rapidly adopted the new varieties and cultivation methods of the so-called 'green revolution'. The new varieties are shorter, increase grain yield at the expense of straw biomass, and are more resistant to damage by wind and rain. These wheats are short because they respond abnormally to the plant growth hormone gibberellin. This reduced response to gibberellin is conferred by mutant dwarfing alleles at one of two Reduced height-1 (Rht-B1 and Rht-D1) loci. Here we show that Rht-B1/Rht-D1 and maize dwarf-8 (d8) are orthologues of the Arabidopsis Gibberellin Insensitive (GAI) gene. These genes encode proteins that resemble nuclear transcription factors and contain an SH2-like domain, indicating that phosphotyrosine may participate in gibberellin signalling. Six different orthologous dwarfing mutant alleles encode proteins that are altered in a conserved amino-terminal gibberellin signalling domain. Transgenic rice plants containing a mutant GAI allele give reduced responses to gibberellin and are dwarfed, indicating that mutant GAI orthologues could be used to increase yield in a wide range of crop species.

Alleles↗

PubMed2005

Computer simulation of the last support phase of the long jump.

PURPOSE: The purpose was to examine the interacting roles played by the approach velocity, the explosive strength (represented by vertical ground reaction force [VGRF]), and the change in angular momentum about a transverse axis through the jumper's center of mass (deltaHzz) during the last support phase of the long jump, using a computer simulation technique. METHODS: A two-dimensional inverted-pendulum-plus-foot segment model was developed to simulate the last support phase. Using a reference jump derived from a jump performance reported in the literature, the effects of varying individual parameters were studied using sensitivity analyses. In each sensitivity analysis, the kinematic characteristics of the longest jumps with the deltaHzz considered and not considered when the parameter of interest was altered were noted. A sensitivity analysis examining the influence of altering both approach velocity and VGRF at the same time was also conducted. RESULTS AND CONCLUSION: The major findings were that 1) the jump distance was more sensitive to changes in approach velocity (e.g., a 10% increase yielded a 10.0% increase in jump distance) than to changes in the VGRF (e.g., a 10% increase yielded a 7.2% increase in jump distance); 2) the relatively large change in jump distance when both the approach velocity and VGRF were altered (e.g., a 10% increase in both parameters yielded a 20.4% increase in jump distance), suggesting that these two parameters are not independent factors in determining the jump distance; and 3) the jump distance was overestimated if the deltaHzz was not considered in the analysis.

Algorithms↗

PubMed1976

Selection for increased semen yield in the turkey.

Selection was effective in greatly increasing semen yield in the turkey. After five generations of selection semen yield in the selected line was more than double that of the randombred control line from which the semen line was developed. The realized heritability of semen yield was .35 +/- .20. There was no consistent change in sperm concentration or frequency of bent sperm associated with the increased yield. Egg production was increased in the semen line. The increase occurred in the first generation of selection and was maintained throughout the remaining generations of selection. Body weight during the growing period exhibited an initial increase in the semen line but declined to randombred control levels in later generations. There was no consistent change in percent fertility, percent hatchability of fertile eggs or number of poults produced per hen which was associated with the genetic increases in semen yield.

Animals↗

PubMedDate not supplied

A laser-induced scar at the cardia increases the yield pressure of the lower esophageal sphincter.

Low yield pressure of the lower esophageal sphincter is associated with esophageal reflux, and fundoplication must increase yield pressure if it is to prevent reflux. We attempted to increase yield pressure endoscopically in the dog by using the Nd:YAG laser to produce a fibrous scar at the cardia in the approximate line of the gastric sling fibers. Ten beagle dogs were studied. In a pilot study with two dogs, 15 watts for 4.2 sec were found to produce a scar deep into the muscle coat of the stomach. Three configurations of scar were used. One produced significant rises in yield pressure in all four of the dogs treated, the second produced a significant rise in one of the two dogs treated, and the third caused a significant drop in yield pressure in the one dog treated. One dog died of gastric perforation 10 days after lasering, but no other animal experienced any ill effects. These findings may have therapeutic implications for the management of esophageal reflux.

Animals↗

PubMed2004

Engineering plants for elevated CO(2): a relationship between starch degradation and sugar sensing.

In the future, plants will have additional CO(2) for photosynthesis. However, plants do not take maximal advantage of this additional CO(2) and it has been hypothesized that end product synthesis limitations and sugar sensing mechanisms are important in regulating plant responses to increasing CO(2). Attempts to increase end product synthesis capacity by engineering increased sucrose-phosphate synthase activity have been generally, but not universally, successful. It was found that plants benefited from a two- to three-fold increase in SPS activity but a 10-fold increase did not increase yield. Despite the success in increasing yield, increasing SPS did not increase photosynthesis. However, carbon export from chloroplasts was increased during the day and reduced at night (when starch provides carbon for sucrose synthesis. We develop here a hypothesis that starch degradation is closely sensed by hexokinase because a newly discovered pathway required for starch to sucrose conversion that involves maltose is one of few metabolic pathways that requires hexokinase activity.

Biological Transport↗

PubMed2005

Proactive spraying against boll weevils (Coleoptera: Curculionidae) reduces insecticide applications and increases cotton yield and economic return.

The current standard practice of two to three preemptive insecticide applications at the start of pinhead (1-2-mm-diameter) squaring followed by threshold-triggered (whenever 10% of randomly selected squares have oviposition punctures) insecticide applications for boll weevil, Anthonomus grandis grandis Boheman, control does not provide a reliably positive impact on cotton, Gossypium hirsutum L., yields in subtropical conditions. This study showed that four fewer spray applications in a "proactive" approach, where spraying began at the start of large (5.5- 8-mm-diameter) square formation and continued at 7- to 8-d intervals while large squares were abundant, resulted in fewer infested squares and 46-56% more yield than the standard treatment at two locations during 2004. The combination of fewer sprays and increased yield made the proactive approach 115-130% more profitable than the standard. The proactive approach entails protection only at the crop's most vulnerable stage (large squares) that, as a source of food, accelerates boll weevil reproduction. In contrast, the standard approach protects early season small squares and later season bolls, both of which contribute less to boll weevil reproduction than large squares. Proaction is an in-season crop protection approach that can be used to increase yield in individual fields during the same season and that could be incorporated into boll weevil eradication strategy that involves later diapause sprays. Because proaction is based on an important relationship between the cotton plant and boll weevil reproduction, the tactic will probably be effective regardless of climate or region.

Animals↗

PubMed2003

Identification of a locus increasing rice yield and physiological analysis of its function.

I identified a new locus responsible for increased yield potential and evaluated its physiological function to understand how to improve potential yield in rice (Oryza sativa) plants. Quantitative trait loci (QTLs) for 1,000-grain weight (TGW) were analyzed under different environments over 3 years in backcross inbred lines of rice japonica cv Nipponbare x indica cv Kasalath. Four QTLs for this trait were detected across environments; rice cv Kasalath had a positive allele only at one QTL on chromosome 6 (tgw6). A near-isogenic line (NILtgw6) that carried a rice cv Kasalath chromosomal segment corresponding to tgw6 in the rice cv Nipponbare genetic background was selected and analyzed to clarify the physiological function of this locus. The carbohydrate storage capacity before heading in NILtgw6 was superior to that in rice cv Nipponbare (control), but other characters (e.g. photosynthetic ability in flag leaf and traits related to plant type) were the same in both plants. In the leaf sheath, the main organ that accumulates carbohydrate before heading in rice, higher contents of carbohydrate and transcripts of genes related to starch synthesis were found in NILtgw6 than in rice cv Nipponbare. Compared with those in rice cv Nipponbare, a high-yield modern cultivar, TGW and yield per plant were significantly higher in NILtgw6, by 10% and 15%, respectively (P[f] < 0.01). These results suggest that tgw6 improves the carbohydrate storage capacity and consequently increases the yield potential in NILtgw6.

Amylopectin↗

PubMed1993

Feeding practices and income over feed cost on pasture-oriented dairy farms in Louisiana.

Monthly summary reports (n = 15,568) of Holstein herds enrolled in the Louisiana DHIA program from February 1984 through April 1990 were analyzed using multiple regression techniques to determine the relationships between feeding practices and income over feed cost on predominantly pasture-oriented dairy farms. Income over feed cost increased as silage and pasture quality score increased and decreased as hay and concentrate increased. Milk yield increased as silage and concentrate increased. Increased hay was associated with lower milk yield, but the overall difference was small. Comparison of feeding practices overall with the top 10% of herds based on income over feed cost indicated that most dairy farmers were not adjusting amount of concentrate to nutritional needs. Additional silage fed during late summer and fall, when permanent pastures were at lowest quality and winter pastures were not productive, improved income over feed cost and herd reproductive performance. Better utilization of concentrate by adjustment of amounts fed for milk yield, stage of lactation, and forage component of ration would increase milk yield and income over feed cost. Increased utilization of silage is suggested for better financial and productive performance of the pasture-oriented dairy farms studied.

Animal Feed↗

PubMed1990

Adaptation to non-ammoniagenic medium and selective substrate feeding lead to enhanced yields in animal cell cultures.

Methods for the adaptation of three animal cell lines to media in which glutamine is replaced with either glutamate or 2-oxoglutarate are described. The cell lines differ in their rate of adaptation. The consequences of the adaptation of the McCoy cell line to a glutamate-based medium was measured in terms of: cell yield (increased by 17%), ammonia accumulation (reduced by 70%), glucose consumption (decreased by greater than 70%) and lactate accumulation (decreased by greater than 75%). The value of such adaptation and concomitant changes in energy metabolism lies in the potential for increased cell yields. Batch feeding of adapted cells in a microcarrier culture with a cocktail of glucose and amino acids resulted in increases in cell yields of 80% compared to unfed controls.

Adaptation, Physiological↗

PubMed2002

Osmolyte accumulation: can it really help increase crop yield under drought conditions?

Osmolyte accumulation (OA) is frequently cited as a key putative mechanism for increasing yields of crops subjected to drought conditions. The hypothesis is that OA results in a number of benefits that sustain cell and tissue activity under water-deficit conditions. It has been proposed as an effective tolerance mechanism for water deficits, which could be enhanced in crops by traditional plant breeding, marker-assisted selection or genetic engineering, to generate drought-tolerant crops. However, field studies examining the association between OA and crop yield have tended to show no consistent benefit. The few, often-cited, investigations with positive associations were obtained under severe water deficits with extremely low yields or conditions with special water-supply scenarios when much of the benefit is plant survival. Under conditions where water deficits threaten crop survival, yields are so low that even large fractional yield gains offer little practical benefit to growers. Indeed, the often-cited benefit of turgor maintenance in cells is likely to result in crop behaviour that is exactly opposite to what is beneficial to crops. The one clear mechanism identified in this review for beneficial yield responses to OA is in the maintenance of root development in order to reach water that may be available deeper in the soil profile.

Journal Article↗

PubMed1992

Kinetics of Maize Leaf Elongation : III. Silver Thiosulfate Increases the Yield Threshold of Salt-Stressed Plants, but Ethylene Is Not Involved.

The involvement of ethylene in the short-term responses of maize (Zea mays L.) leaf elongation to salinity was investigated. Leaf elongation rates (LER) were monitored with linear variable differential transformers. Salinity (80 mm NaCl) rapidly inhibited LER. Pretreatment with 4 mm silver thiosulfate (STS), an inhibitor of ethylene action, decreased LER of salt-stressed plants, but not that of controls. Investigation of the growth parameters affected by the interaction of STS and salinity indicated that the yield threshold was increased and the cell wall extensibility was decreased. All other growth parameters controlling cell elongation were unaffected. Further investigation indicated that ethylene production may not be involved in this reponse because treatments with 10 mum aminoethoxyvinylglycine, an ethylene biosynthesis inhibitor, did not affect the growth of salt-stressed plants, and no increase in ethylene production was detected in salt-stressed plants compared with controls. No changes in sensitivity to ethylene were evident because LER of both control and salt-stressed plants were inhibited to the same extent with exposure to 1.2 ppm ethylene. The above evidence indicated that ethylene was not involved in the short-term LER responses of salt-stressed maize.

Journal Article↗

PubMed1990

DNA polymerase alpha does not mediate G0-G1 increase in yield of X-ray-induced exchange aberrations in human peripheral blood lymphocytes.

We report experiments to test the hypothesis that the increased yield of dicentric chromosomes observed in human peripheral blood lymphocytes treated with X-rays during the G1 phase of their first cell cycle, as compared with the yield when the cells are treated in their G0 phase prior to phytohemagglutinin stimulation, is a manifestation of the recently-reported conversion of an inactive form of DNA polymerase alpha to its active form as the PHA-stimulated cells pass from G0 into G1 (Sylvia et al., 1988). The specific polymerase alpha inhibitor butylphenyl deoxyguanosine was used as an X-ray post-treatment. The results show that polymerase alpha is not involved.

Cell Cycle↗

PubMed1994

Effects of volume and periodicity on blood cultures.

Blood specimens collected for culture by using the high-volume resin-based BACTEC system over an 18-month period at the Seattle Veterans Administration Center were examined in this study. Of 7,783 cultures obtained, 624 were classified as true positives. Patients in this group had between 20 and 60 ml of blood drawn per culture and separated into 10-ml aliquots for incubation. Analysis of the results stratified by cultured volume and time interval between specimen collection accorded yield advantage to culture volume at the maximal amounts tested. No advantage was observed with any particular interval of collection. Increasing cultured volume from 20 to 40 ml increased yield by 19%. Increasing cultured volume from 40 to 60 ml increased yield by an additional 10%. The same effect was seen whether cultures were drawn simultaneously or serially within 24 h. These observations support other reports demonstrating increased yield with increased cultured blood volume. However, they demonstrate increases in yield at volumes much higher than previously considered. In conclusion, this study demonstrates that high-volume blood cultures drawn serially or simultaneously return the best yields.

Bacteremia↗

PubMed1997

Effect of lamp type and temperature on development, carbon partitioning and yield of soybean.

Soybeans grown in controlled environments are commonly taller than field-grown plants. In controlled environments, including liquid hydroponics, height of the dwarf cultivar "Hoyt" was reduced from 46 to 33 cm when plants were grown under metal halide lamps compared to high pressure sodium lamps at the same photosynthetic photon flux. Metal halide lamps reduced total biomass 14% but did not significantly reduce seed yield. Neither increasing temperature nor altering the difference between day/night temperature affected plant height. Increasing temperature from 21 to 27 degrees C increased yield 32%. High temperature significantly increased carbon partitioning to stems and increased harvest index.

Biomass↗

PubMed1977

Increased spore yields of Clostridium perfringens in the presence of methylxanthines.

The methylxanthines caffeine, theophylline, and isobutylmethylxanthine greatly increased spore yields of Clostridium perfringens strains FD-1, PS52, and PS49 when grown on Duncan-Strong medium or on a new casein-digest medium. Four other strains (KA3, and National Collection of Type Cultures strains 8798, 8238, and 10240) failed to show any significant increase when tested under similar conditions. The degree of sporulation increase was influenced by the carbohydrate energy source in some strains but not in others. Strain PS52 showed a large increase in spore yield when dextrin was the energy source but only a slight increase when raffinose served as the energy source. Strain FD-1 showed similar increases in spore yield with either dextrin or raffinose.

Caffeine↗

PubMedDate not supplied

Nutrients can enhance phytoremediation of copper-polluted soil by Indian mustard.

An orthogonally designed experiment was conducted to study the single and combined effects of N, P and K on phytoremediation of Cu-polluted soil by Indian mustard. Addition of fertilizer N and P significantly increased Indian mustard shoot yield. Two high treatments combined with N resulted in the highest yields, followed by low-P combined with N. In contrast, high P with no N gave no yield increase and K had no effect on yield of Indian mustard. Nitrogen and P increased the amount of chlorophyll in the leaves, indicating that the yield increases were due to enhanced photosynthesis. Nitrogen application had no effect on plant Cu concentrations but addition of P slightly decreased plant Cu concentrations, likely a dilution effect resulting from the increase in yield. Among the treatments, N and P applied at 100 and 200 mg kg(-1) respectively with no K application resulted in the highest Cu uptake. Thus, a combination of low N and high P produced a yield increase in Indian mustard that was more than adequate to compensate for a slight decrease in Cu concentration, resulting in the highest Cu removal from the contaminated soil.

Biodegradation, Environmental↗