Fibronectin enhances transfection of Staphylococcus aureus.

The factor in normal sera primarily responsible for the enhancement of transfection (and transformation) of Staphylococcus aureus was identified as fibronectin. Serum samples which were depleted of fibronectin by affinity chromatography showed a marked decrease in enhancing activity. Fibronectin isolated from sera of several animal species demonstrated enhancing activity.     

Temperature-Sensitive Osmotically Fragile Mutants of Staphylococcus aureus

Temperature-sensitive fragile mutants of Staphylococcus aureus which grow at the restrictive temperature only in the presence of osmotic stabilizers and appear to have conditionally defective cell wall integrity were isolated and partially characterized.     

Transfer of the conjugal tetracycline resistance transposon Tn916 from Streptococcus faecalis to Staphylococcus aureus and identification of some insertion sites in the staphylococcal chromosome.

The Streptococcus faecalis pheromone-dependent conjugative plasmid pAD1::Tn916 and the membrane filter-dependent conjugative plasmid pPD5::Tn916 were used to introduce Tn916 into Staphylococcus aureus by intergeneric protoplast fusions and intergeneric membrane-filter matings. In recombinants obtained by protoplast fusion where no plasmid DNA could be detected, tetracycline resistance resulted from transposition of Tn916 from pAD1 to the S. aureus chromosome. Transformation analyses showed that S. aureus Tn916 chromosomal insertions occurred near pig, ilv, uraA, tyrB, fus, ala, and the trp operon. DNA hybridization analyses of EcoRI- and HindIII-digested chromosomal DNAs confirmed the diversity of chromosomal sites involved and demonstrated that the inserts were Tn916 insertions rather than integrations of all or part of pAD1::Tn916. Both pAD1::Tn916 and pPD5::Tn916 were transferred to S. aureus by membrane-filter matings. These plasmids remained intact and expressed tetracycline resistance in S. aureus. S. aureus strains carrying pAD1::Tn916, but not a chromosomal insert of Tn916, and any one of several conjugal gentamicin-resistance plasmids lost their ability to serve as conjugal donors of the gentamicin-resistance plasmids.     

Relation entre poids frais et poids sec chez quelques invertébrés d'eau douce

Resume La relation entre le poids frais et le poids sec, établie pour 10 espèces différentes, varie nettement de l'une à l'autre. Le premier représente 6 à 9 fois le second chez les Mollusques, 3 à 5 fois chez les Arthropodes, et 4 à 7 fois chez les Planaires étudiés.

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Summary The relation between live weight and dry weight, which was investigated for 10 different species, often differs significantly from one species to another. The values determined for the ratio of the live weight to the dry weight were of the magnitude 6 – 9 : 1 for the Molluscs, 3 – 5 : 1 for the Arthropods, and 4 – 7 : 1 for the Planarians.

     

Epistemic, Evolutionary, and Physical Conditions for Biological Information

The necessary but not sufficient conditions for biological informational concepts like signs, symbols, memories, instructions, and messages are (1) an object or referent that the information is about, (2) a physical embodiment or vehicle that stands for what the information is about (the object), and (3) an interpreter or agent that separates the referent information from the vehicle’s material structure, and that establishes the stands-for relation. This separation is named the epistemic cut, and explaining clearly how the stands-for relation is realized is named the symbol-matter problem. (4) A necessary physical condition is that all informational vehicles are material boundary conditions or constraints acting on the lawful dynamics of local systems. It is useful to define a dependency hierarchy of information types: (1) syntactic information (i.e., communication theory), (2) heritable information acquired by variation and natural selection, (3) non-heritable learned or creative information, and (4) measured physical information in the context of natural laws. High information storage capacity is most reliably implemented by discrete linear sequences of non-dynamic vehicles, while the execution of information for control and construction is a non-holonomic dynamic process. The first epistemic cut occurs in self-replication. The first interpretation of base sequence information is by protein folding; the last interpretation of base sequence information is by natural selection. Evolution has evolved senses and nervous systems that acquire non-heritable information, and only very recently after billions of years, the competence for human language. Genetic and human languages are the only known complete general purpose languages. They have fundamental properties in common, but are entirely different in their acquisition, storage and interpretation.