Coding properties of 7-methylguanine

The abnormal base, 7-methylguanine, has been introduced into copolymers of uridylic and guanylic acids by methylation under controlled conditions. The resulting methylated copolymers have a markedly decreased template activity for polypeptide synthesis in vitro due to steric effects of the 7-methyl groups. Contrary to expectation, these polymers do not permit incorporation of amino acids whose codons contain the bases uracil and adenine.     

Plasma homocysteine and glycine are sensitive indices of folate status in a rodent model of folate depletion and repletion

The objectives of the current studies included the characterization of the temporal changes in indices of folate status and amino acid concentrations during both folate depletion and repletion phases. In trial 1, a 6 week folate depletion protocol was employed, using 60 weanling rats assigned to receive an amino acid-defined diet with or without 1 mg/kg folic acid. A 4 week folate depletion period was judged to be optimal on the basis of the development of nadirs in both plasma and hepatic folate stores and elevated (>6-fold relative to folate-adequate controls) concentrations of plasma homocysteine and glycine. In trial 2, 54 weanling rats, previously maintained on a folate-devoid diet for 4 weeks, were assigned to receive 0.25 mg/kg folate as either crystalline folic acid or folate from a folate-enriched egg yolk powder. Both forms of folate supported similar rates of gain, increases in plasma and hepatic folate stores, and reductions in plasma glycine concentrations, whereas the folate in egg yolk powder lowered plasma homocysteine concentrations further than the crystalline folic acid (P < 0.05). These data support the use of both plasma glycine and homocysteine as sensitive response criteria for folate status in a rat bioassay of folate depletion and repletion and establish appropriate temporal end-points for such studies.     

Evaluating SHOOTGRO 4.0 as a potential winter wheat management tool in the Czech Republic

Improving current cultural practices often involves more precise timing of the management activity based on crop development. Using crop simulation models to predict crop development and phenology has several problems. First, most existing models do not simulate sufficient developmental and phenological detail required to optimize selected management practices. Second, crop models normally emphasize the cultivars and conditions for the region in which they were developed, and may not generate satisfactory results when applied in new regions. Lastly, when users apply these models to new regions they often lack the specific data and knowledge of the model to adequately determine the crop parameters. Our objective was to assess whether the simulation model SHOOTGRO 4.0, which had the necessary level of developmental and phenological detail required for use as a management decision aid, could be easily and adequately parameterized to simulate winter wheat phenology and grain yield in the Czech Republic. We found that only a few parameters from the generic winter wheat cultivar used for the Central Great Plains in the USA needed to be changed, and the information needed to determine these few parameters were readily obtainable. The result was that the dates of anthesis and physiological maturity and final grain yield were predicted well at sites within the three major crop production regions of the Czech Republic. Sensitivity analysis also showed that the most sensitive management practices and initial conditions in SHOOTGRO are relatively easy to determine (e.g. sowing date, N fertilizer rate and timing, daily temperature), while it is not overly sensitive to those variables more difficult to determine (e.g. initial soil water in the profile). Based on this study, farmers and scientists needing wheat development information to increase the efficacy of their management practices can use SHOOTGRO 4.0 as a tool.     

Characterization and agricultural utilization of swine waste lagoon effluents

This investigation was conducted to determine the elemental composition of effluents from three anaerobic swine waste lagoons and one aerobic swine waste lagoon and to evaluate effects of effluent application on growth of corn (Zea mays L.) Wide variation occurred in the elemental composition of effluents among the four lagoons and among four sampling dates from each lagoon. Use of these effluents as irrigation water would lead to application of a wide range in amounts of nutrients to soil. Effluent application increased corn grain yield on a Woodstown loamy fine sand. This yield increase was attributed to alleviation of moisture stress and to correction of N deficiency.     

Zur Gliederung der forstwirtschaftslehre in Produktions lehre und Vetriebslehre

Ohne Zusammenfassung