Maternal transmission of a ring chromosome 15.

A 5-year-old boy with Silver-Russell-like phenotype and developmental delay was found to have a ring chromosome 15. The same r(15) was found in his slightly mentally retarded mother with mild dysmorphism. Analysis of the literature showed 34 families with direct vertical transmission of a ring autosome. In 30 of these families abnormal chromosomes were inherited from the mothers; both maternal and paternal transmission was shown in different generations of one family; and only in 3 families ring chromosomes were inherited from the fathers. The possible explanations of preponderance of maternal transmission are briefly discussed.

[Effect of low molecular weight regulators on the biosynthesis of rifamycin B by Amycolatopsis mediterranei strains]. / Vliianie nizkomolekuliarnykh reguliatorov na biosintez rifamitsina B shtammami Amycolatopsis mediterranei.

Formation of differentiation regulators of the A-factor group in representatives of Nocardia and Nocardia-like actinomyces: N. asteroides, N. brasiliensis, Amycolatopsis mediterranei and "Streptomyces listeri" was observed. The effect of the regulators of different nature (barbital, A-factor and B-factor) on biosynthesis of rifamycin B by A. mediterranei strains was studied. It was shown that the A-factor stimulated rifamycin B production in the adifferentiated low active variant isolated from a natural population of the active strain VNIIA 1713 of the rifamycin B-producing culture. B-Factor insignificantly inhibited biosynthesis of rifamycin B in the studied strains of A. mediterranei.

[A method for developing a controlled process. Development and execution of a program supplying culture medium components for rifamycin B biosynthesis]. / Metod razrabotki upravliaemogo protsessa. Raschet i realizatsiia programmy podpitok komponentami sredy pri biosinteze rifamitsina B.

The study provided data on the rate of consumption of the main nutrients by the rifamycin-producing culture in relation to their content in the initial medium. A program for feeding ammonium sulfate and cornsteep liquor and joint control of both the nutrients was developed and tested. The results of the testing confirmed the practicable precision of the feeding. The control of cornsteep liquor and ammonium sulfate concentrations with the program allowed to increase the yield of rifamycin B by 15 and 20%, respectively. The joint control increased the level of the required product by 25%.

[Experience with long-term preservation of international-standard cultures of Actinomycetes]. / Opyt dlitel'nogo khraneniia kul'tur mezhdunarodnykh vidovykh étalonov aktinomitsetov.

The results of the study on long-term maintenance (1-12 years) of 453 reference cultures of actinomycetes are presented. The cultures were maintained with the following methods: lyophilization, soil cultures and periodical passages on agarized nutrient media. Lyophilization was most efficient for storage of the majority of the cultures: 346 strains (77.4 per cent) preserved high viability over the observation period of 11-12 years. Lyophilization appeared less favourable for the cultures with low sporulation. The efficacy of the method of soil cultures on long-term storage of the whorl actinomycetes was low: 88 per cent of Streptoverticillium lost their viability within 1-2 years. However, this method was valuable for stabilization of the taxonomic features of streptomycetes. The maintenance of the actinomycetes by regular passages on agarized media every 6 months resulted in the changing of the cultural and morphological features in a number of the strains.

[Effect of lyophilization methods on the formation of free radicals, the survivability and makeup of a population of the lincomycin producer]. / Vliianie sposobov liofilizatsii na obrazovanie svobodnykh radikalov, vyzhivaemost' i sostav populiatsii produtsenta linkomitsina

It was shown that a short-time exposure of the spores of Act. roseolus 981 to air (oxygen) on their lyophilization by the chamber method resulted in formation of increased numbers of the free radicals in the lyophilized spores suspension and decreased the survival of the spores on their further storage under vacuum. The phenomena were less pronounced when the exposure of the spores to the air was excluded by using the collector method of lyophilization. This testified to the advantages of the latter method as compared to the chamber one. No effect of the lyophilization methods on the population composition of the spontaneous variants of Act. roseolus 981 was observed.

[Study of the population makeup and antibiotic and transamidinase activity of Actinomyces streptomycini 773 stored for a long period in a lyophilized, dried state]. / Izuchenie sostava populiatsii, antibioticheskoi i transmidinaznoi aktivnosti Actinomyces streptomycini 773 pri dlitel'nom khranenii v liofil'no vysushennom sostoianii

Studies on variation of the streptomycin-producing organism Act. streptomycini 773 on its storage in lyophilized state showed that prolonged maintenance (for 8 years) resulted in increased percentage of "oligospore" (up to 6.9 per cent) and asporogenic (up to 6.0 per cent) variants in the population. The variants had lower transamidinase and antibiotic activity.