Differentiation--a consequence of idiotype-environment interaction.

The present paper deals with a model of idiotype-environment interaction and its application to a tissue culture experiment with birch (Betula pendula ROTH.). The data of the experiment are characterized with respect to the physiological reactions and are discussed in the light of the model. The main results of the paper are: With respect to the environmental action one has to discriminate between the environment inside and outside the cell (external and internal environment). The environmental influences cause a differential gene activity which lead to transient differentiation states and to final states of differentiatedness. During mitosis two types of information transmission take place: transmission of genetic material (the "blueprint") and transmission of the milieu (the "experience" of previous events). They together give rise to differentiation. The data of the experiment show that differentiation is no one-way street: Because of the transmitted milieu it is sometimes easier to regain an earlier differentiation state than to reach a new one. Only the interaction of idiotype (sum of genetic information) and the milieu state (internal environment) causes parallel as well as divergent development of cell lines. The model is also used to reinterpret some selected papers in the literature.

[Caruncle removal in cattle--subsequent treatment and use of a new cervix dilator]. / Die Karunkelexstirpation beim Rind--Nachbehandlung und Anwendung eines neuen Zervixdilatators.

Retention of the fetal membranes in bovines is frequently accompanied by necrosis of the caruncles. This is dependent on the kind of bacterial contamination and seems to be of regional variety. Necrosis of the caruncles requires extirpation which is the only treatment to save life, fertility and economic benefit of the animal. Following extirpation after-treatment over a period of eight to nine days essentially influences the success. Antibiotic therapy is not the main principle of treatment but to handle the atony of the uterus and its fatal consequences caused by the inflammatory contents. Since the cervix necessarily has to remain open for the period of treatment the use of a recently developed cervix dilatator (Ludwig Bertram GmbH, Hannover) is described and recommended.

Genotype - environment interaction in tissue cultures of birch.

In vitro culture experiments were carried out with three birch genotypes characterized by certain genealogical relationships which serve as indicators of genetic similarity or dissimilarity. Each genotype was grown in each of six different environments (medium types), and callus growth and colour were observed. The aim was to improve our understanding of the operation of genetic and environmental effects at the early stages of regeneration in vitro. For this purpose we tried to answer the question as to whether genetic differences exert effects that are consistently distinguishable under different environments or whether environmental differences exert effects that are consistently distinguishable between different genotypes. Since conventional analytical methods, such as the analysis of variance, are inappropriate for providing satisfactory answers to this question, we applied a new concept of interpretation. With the help of this concept we obtained the following results which appear to be unique among their kind. 1) For both characters, callus growth and callus colour, genetic differences are masked only slightly by the environments while environmental differences are almost completely masked by the genotypes. Thus, in the present experiment, interaction is one-sided in the sense that environmental effects interact strongly with genotypic effects but genotypic effects interact only slightly with the environmental ones. 2) Nuclear effects seem to be responsible for the differences observed in callus growth, while the differences in callus colour can be explained by the joint action of nuclear and extranuclear effects.

Photoregulation of transfer and 5S ribosomal RNA synthesis in Chlorella.

The effect of blue and red light on the synthesis of transfer and 5S ribosomal RNA in autotrophic cultures of Chlorella pyrenoidosa was studied by pulse labeling experiments with tritiated guanosine. Compared with darkness or red light (679 nm), blue light (457 nm) of low intensities (quantum flux: 0.5-5×10(-10) mol photons cm(-2) s(-1)) stimulated incorporation of guanosine into transfer and 5S ribosomal RNA within the first 5 min of illumination. This blue light effect was abolished by cycloheximide, an inhibitor of protein synthesis on 80S ribosomes, but not by rifampicin, an inhibitor of chloroplastic transcription, nor by lincomycin, an inhibitor of chloroplastic translation. The rifampicin-insensitive synthesis of transfer and 5S ribosomal RNA was nuclear transcription as shown by RNA-DNA hybridization. The blue light effect on nuclear RNA synthesis was not inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethyl-urea, an inhibitor of photosynthesis electron transport. Further evidence for a photosynthesis-independent photocontrol of RNA synthesis was provided by experiments with the colorless mutant 125a of Chlorella vulgaris. Blue light stimulated incorporation of guanosine into cytoplasmic 25S and 18S ribosomal RNA as well as into transfer and 5S ribosomal RNA, whereas incorporation in red light was the same as that of the dark control.