[Ultrastructure of Candida utilis in continuous culture with various concentrations of the carbon source introduced by different technics]. / Ul'trastruktura drozhzhei Candida utilis pri nepreryvnom kul'tivirovanii s raznymi kontsentratsiiami istochnika ugleroda pri razlichnykh sposobakh ego vneseniia.

The object of the work was to study changes in the ultrastructure of Candida utilis cells induced by increasing concentrations of glucose during chemostat cultivation and continuous cultivation with glucose pulse feeding. The results indicate that the cell structure and metabolism change vectorially with an increase of glucose concentration regardless of how glucose was added. An increase of the input glucose concentration is followed by an increase in the periplasmic space, the content of glycogen, the length and diameter of mitochondria, and the size of the nucleus. However, in the case of glucose pulse feeding, the above changes in the cell structure occur at a considerably lower input concentration as compared to the chemostat culture. Under these conditions, microtubuli are assembled in the cytoplasm in response to the glucose stimulus.

Transposition of a DNA fragment flanked by two inverted Tn1 sequences.

The 32 Md fragment (derived from plasmid RP4::Tn1) carrying the Kmr gene and flanked by two inverted Tn1 elements is capable of recA-independent translocation to other plasmids. We designated this new transposon Tn1755. In various crosses, frequencies of Tn1755 transposition to plasmids Co1B-R3, R15 and F'Co1VBtrp varied from 2.5 to 90% of the frequencies of Tn1 transposition. Tn1755 can integrate into various sites of the recipient plasmids. We failed to observe transposition of another RP4::Tn1 fragment flanked by two opposingly oriented Tn1 transposons and harboring the Tcr gene. Presumably, to form a new transposable structure, other features must also be of importance.

[Effect of plasmid F'Col+trp+ on the transfer of plasmid RP4]. / Vliianie plazmidy F'Col+trp+ na perenos plazmidy RP4.

Interaction of conjugative plasmids F'colV colB trp and PR4 in Escherichia coli host was studied during the transfer of the plasmids from cell to cell. The plasmid F'colV colB trp is found to stimulate the transfer of RP4 from the diplasmid strain. This seems to be due to stabilization of the conjugating pairs which require normal pili coded by the plasmid F'colV colB trp.

[Transmission of plasmid Rldrd19 from E. coli to Hafnia]. / Peredacha plazmidy Rldrd19 ot E. coli v Hafnia.

Investigations carried out demonstrated a possibility of transmission of plasmid Rldrd19 from E. coli to Hafnia. The incidence of the plasmid transmission varied from 10(-7) to 10(-9) and depended on the properfies of Hafnia strains. Tra-operon of plasmid Rldrd19 in the Hafnia 614 strain functioned with the same efficacy as in E. coli. Plasmid Rldrd19 in Hafnia was unstable and was eliminated from the cells in case of storage at low temperatures. As shown, plasmid Rldrd19 was under strict replication control in Hafnia as in E. coli. Formation of the CCC-form of the plasmid Rldrd19 was suppressed in Hafnia at 29--30 degrees C and was not suppressed in E. coli.