Characteristics of Cytophaga psychrophila (Borg) isolated during outbreaks of bacterial cold-water disease

Characteristics of 10 strains of Cytophaga psychrophila isolated during a number of epizootics of bacterial cold-water disease were compared. Morphological, cultural, biochemical, and serological data showed that the organisms were very closely related. The isolates exhibited gliding motility, formed neither fruiting bodies nor microcysts, were actively proteolytic, and grew only at low temperatures. Data presented extend the description of C. psychrophila.

Cell-free incorporation of amino acids by a trout-liver system. Heat-labile aminoacyl transferase activity

A cell-free system from trout liver that incorporates amino acids into protein has been isolated. The system requires both soluble and particulate fractions, and is similar to those isolated from other organisms.The incorporation of amino acids is extremely heat-labile, and this lability has been localized in the aminoacyl transferase activity of the cell sap. The heat lability of the microsomes may also be related to transferase activity.Ribosomal fractions from trout liver and rat liver incorporate amino acids when incubated with cell sap from rat liver and trout liver, respectively.

Alarm reaction of the top smelt, Atherinops affinis: reexamination

We did not observe the reported alarm reaction of the top smelt Atherinops affinis (Ayres) when presented with a methanol extract of whole top smelt; we interpret the reaction as an experimental artifact. Rather, a methanol extract of top smelt is an attractant, as is methanol extract of shrimp.

3-methylhistidine in actin and other muscle proteins

1. By the use of the extended elution system for basic amino acid analysis, 3-methylhistidine has been detected in hydrolysates of actin isolated from mammalian, fish and bird skeletal muscle. 2. Evidence is presented to indicate that 3-methylhistidine forms part of the primary structure and that in rabbit actin this residue is restricted to one peptide fraction obtained from the tryptic digest. 3. Rabbit skeletal-muscle actin has a 3-methylhistidine:histidine ratio 1:7.6, indicating a minimum molecular weight of 47600. 4. Adult rabbit myosin contains approximately 2 3-methylhistidine residues/mol. These residues are localized in the heavy meromyosin part of the molecule, and are restricted to the major component obtained after succinylation.

Analysis of an experimental model of DNA unwinding

Experiments are described, showing that DNA solutions with lithium chloride present a hypochromicity, which increases with the molarity of the salt. Different absorbancy versus temperature curves are obtained for different solutions, and it is found that the melting point (Tm) increases with the lithium chloride concentration. When cooling the samples, the absorbancy decreases in a symmetric way.

In accordance with this model, a theory of DNA unwinding is proposed, assuming that before the unwinding, it is necessary a stretching of the molecule which eases this process. An extension of these ideas are applied, to the transcription DNA-RNA operation.

Conversion of a dietary triglyceride into depot fat in fish and lobster

Cod, trout, and lobsters were fed a triglyceride that contained oleic-9,10-8H acid in the β and oleic-1-I4C acid in the α positions. The distribution of the labels in the α and β positions of the depot fat was then analyzed. The original distribution had been retained to a large extent in the lobster, indicating a retention of the β-monoglyceride structure of the dietary fat in this invertebrate. In the fish, there was an apparent partial retention of8H in the β position, but the14C of the originally α-bound acids was now almost randomly distributed. These results may be interpreted as supporting the hypothesis that the β-monoglyceride structure of dietary fat is partly retained by fish. It is clear, however, that in fish, though not in lobster, the larger part of the fat had been broken down completely before deposition.