The influence of the different members of a crop-rotation system on the biodynamics of soil

Summary The thought that a soil under prevailing climatic conditions receives the most significant impulse from its vegetational cover together with the biochemical activity of micro-organisms living in it, has suggested the study of soil biodynamics under the different members of a crop-rotation system.Whereas formazan formation served as index for the biological activity of soil, changes in amount and composition of humic compounds isolated from the same soil were followed by their acriflavine adsorption capacity and optical-density behaviour, both disclosing the fluctuating residual power in such a soil. Moreover, pH measurements and slaking experiments gave additional information on the effects of vegetation on soil.It became evident that a continued and close-growing crop is of primary importance for the establishment and maintenance of an optimal humus level in a loamy sand of the summer-rainfall region of a semiarid country. The ploughing-up of the grassley for seedbed preparations resulted in an immediate drop of the humus content, built-up during the previous years in such a soil. Natural veldt, not undergoing any management, and which may be regarded therefore as completely undisturbed, accumulated the highest amount of humus in its environment.A crop-rotation system with grass and other suitable plant associations included may well be in the position to make the best use out of the soil by mobilizing and, at the same time, renewing continuously its biotic potential.On the other hand, monoculture with row crops as maize, leaving large spaces of soil unprotected against drastic climatic influences, and undergoing major mechanical treatments, for instance, frequent mechanical weeding, will open the soil for wind and water erosion through deterioration of its biological resistance unless management procedures are better adapted to environment.It seems that the study of the physiology of soil, which coincides in part with the interactions between plant and soil, is a very useful tool in the offensive strategy to improve agriculture in extreme climatic zones.     

On the informational content of viral DNA

This paper is concerned primarily with how information is stored in viral DNA. The general problem of defining information content is discussed and a procedure for analysis extended from that of Gatlin (1972) is developed. Long range correlations in base sequences are analyzed for several viral genomes. The relationship of these correlations to the existence of strong codon biases is examined and the consequences discussed.     

On the information content of the genetic code

In living organisms 20 amino acids along with the terminator value(s) are encoded by 64 codons giving a degeneracy of the codons as described by the genetic code. A basic theoretical problem of genetic codes is to explain the particular distribution of degeneracies of partitions involved in the codes. In this work the degeneracy problem is considered in the framework of information theory. It is shown by direct numerical evaluation of a certain degeneracy information function associated with the genetic code that the degeneracy of the codes is observed to be related to the optimization of this function.     

CO2 biodynamics : A new concept of cellular control

CO₂ biodynamics is a new concept of the molecular control in the cell by the direct action of dissolved unhydrated CO₂ It offers a new dimension—that of dynamics to the molecular mechanism of action. Local CO₂ pulses are directly related to temporary reversible biochemical and biophysical changes in cell constituents, which control certain dynamic functions of the cell. A series of experimental models is developed which have broad implications for understanding of the cell and how it functions. Evidence drawn from the literature is presented to support the models.     

On the information content of discrete phylogenetic characters

Journal of Mathematical Biology - Phylogenetic inference aims to reconstruct the evolutionary relationships of different species based on genetic (or other) data. Discrete characters are a...     

On the cysteine and cystine content of proteins

Summary Analysis of published data on the cysteine and half-cystine content of proteins indicates that most intracellular proteins may be classified as sulfhydryl proteins (those containing cysteine but little or no half-cystine) and that such sulf-hydryl proteins have a low cysteine content. The mean cysteine content found for 32 intracellular mammalian proteins was 1.6 % and intracellular proteins of many bacteria have similar or lower values. Extracellular mammalian proteins are primarily disulfide proteins (those containing half-cystine but little or no cysteine) and have a high half-cystine content, the mean value found for some 34 extracellular mammalian proteins being 4.1 %. This is contrasted with many of the extracellular proteins from facultative bacteria which are cyst(e)ine-free proteins, being lacking in both cysteine and half-cystine. These and related observations are interpreted in terms of the evolution of life in a reducing atmosphere and the subsequent transition to an oxidizing environment. It is suggested that disulfide proteins evolved primarily after the accumulation of oxygen in the atmosphere.