Radically different maxicircle classes within the same kinetoplast: an artefact or a novel feature of the kinetoplast genome?

We discuss here some results which suggest that radically different maxicircle classes coexist within the same kinetoplast. These data, although tentative and incomplete, may provide a new outlook on the kinetoplast genome structure and expression.     

Structure of a beheaded 30 S ribosomal subunit from Thermus thermophilus.

The 22 S ribonucleoproten particles containing the 5' (body) and the central (platform) domains of the Thermus thermophilus 30 S subunit has been studied by sedimentation, neutron scattering and electron microscopy. The RNP particles have been obtained by oligonucleotide-directed cleavage of 16 S RNA with ribonulease H in the region of the 900th nucleotide of the protein-deficient derivatives of the 30 S subunits. It is shown that these RNP particles are very compact, though their form and dimensions differ slightly from those expected from the electron microscopy model of the 30 S subunit beheaded by computer simulation. The particles are subdivided into two structural domains whose mutual arrangement differs from that of the corresponding morphological parts of the native 30 S subunit. Electron microscopy demonstrates that the mutual arrangement of domains in the RNP particles is not strictly fixed suggesting that interaction with the third domain of the 30 S subunit is a requisite for their correct fitting.     

The composition of a population of cloned cultures of revertant Vibrio cholerae L forms

The process of L-transformation and L-transformed state duration have been studied for their effect on variability of main characters of revertant cultures of choleric vibrions L-forms at the population level with the use of cloned cultures of the choleric vibrions. The study was conducted on two strains of the choleric vibrion of the eltor biovar in different periods of storage in the L-transformed state (1, 3, 6 months). It has been revealed that characters of the species and biovar remained stable despite the influence of L-transforming agents. The characters of clone cultures characterizing virulence (sensitivity to KhDF phages, hemolytic activity, toxin production and virulence for sucking rabbits proved to be subjected to variability to the greatest extent with simultaneous preservation of the toxin-production gene. A resistant change of the serovar (from Inaba to Ogava) is observed only in one revertant-subculture of the virulent strain.     

The activity of exogenous genetic constructs introduced into cells by the technique of ballistic transfection in mouse ontogenesis

We used the method of particle bombardment (ballistic transfection) to introduce β-galactosidase and human dystrophin genes into mouse embryos and skeletal muscles of adult mice. We examined the mechanisms of DNA transfer into skeletal muscle cells, the biological processes accompanying and following this transfer, the susceptibility of various types of muscle cells to transfection, and the duration of expression of and conditions affecting the introduced genes. We have also developed an effective, convenient, and practical methods of skeletal muscle transfection.     

Labeled histochemical localization of carbohydrate components of glycoproteins: glucose-6-phosphate and phosphoenolpyruvate]

In the present work methods for the localization of glucose-6-phosphate and phosphoenolpyruvate residues on tissue sections by means of labeled with colloidal gold specific enzymes (glucose 6-phosphate dehydrogenase and pyruvate kinase) are described. In order to get sufficient amount of labeled enzyme to the protein salts, used to stabilize colloidal gold salts, albumin was added. Residues of glucose-6-phosphoenolpyruvate were scattered equally through the villi of human placenta. In rat liver centrolobular localized hepatocytes had high content of specific staining. There were a lot of glucose-6-phosphate residues in hepatocytes nuclei.     

MEC: A transposable element from Chironomus thummi (Diptera)

Summary Two genomic clones, pC1.2 and p20D (containing inserts of 2.0 and 1.6 kb, respectively) were isolated from the A2b region to polytene chromosome IV of Chironomus thummi thummi salivary gland cells. Upon in situ hybridization to polytene chromosomes of C. thummi thummi and C. thummi piger, p20D DNA hybridized mainly over the A2b region of chromosome IV, whereas pC1.2 DNA hybridized to at least 90 sites distributed over all the chromosomes. A partial nucleotide sequence analysis showed that these clones were very similar and allowed the detection of a 596 by insert in the pC1.2 clone. This insert possesses all of the essential features of a Class II transposable element and was called MEC. It carries a nearly perfect 107 by terminal inverted repeat containing one mismatch and is flanked by a 5 by direct repeat. The 372 by central region contains a short open reading frame with a coding capacity of 58 amino acids.