The Reports of the Russian Empire Officials on the Semirechye Region: A Historiographic Analysis

The paper describes the process of scientific substantiation of the Russian Empire's preliminary preparation for the colonisation of the Kazakh steppes in the second half of the 19th century. The purpose of the paper is to analyse the political, as well as the economic situation (development of animal husbandry and agriculture) in the Semirechye region based on sources compiled with the help of the works of military officials of 19th century tsarist Russia. The paper also provides an assessment and comparative analysis of the subjective characteristics of historical sources on the region development. Considering the study of the region until the end of the 19th century, the authors have found that Semirechye was of interest for the Russian Empire in terms of the presence of important natural resources. Based on the methods of scientific research, we also identified the relationship between the ethnographic, political and economic development of the region. In general, the paper shows the importance of the reports of military officials as valuable primary sources of information

Bacteriophage-Resistant Mutants in Yersinia pestis: Identification of Phage Receptors and Attenuation for Mice

Background: Bacteriophages specific for Yersinia pestis are routinely used for plague diagnostics and could be an alternative to antibiotics in case of drug-resistant plague. A major concern of bacteriophage therapy is the emergence of phageresistant mutants. The use of phage cocktails can overcome this problem but only if the phages exploit different receptors. Some phage-resistant mutants lose virulence and therefore should not complicate bacteriophage therapy. Methodology/Principal Findings: The purpose of this work was to identify Y. pestis phage receptors using site-directed mutagenesis and trans-complementation and to determine potential attenuation of phage-resistant mutants for mice. Six receptors for eight phages were found in different parts of the lipopolysaccharide (LPS) inner and outer core. The receptor for R phage was localized beyond the LPS core. Most spontaneous and defined phage-resistant mutants of Y. pestis were attenuated, showing increase in LD 50 and time to death. The loss of different LPS core biosynthesis enzymes resulted in the reduction of Y. pestis virulence and there was a correlation between the degree of core truncation and the impact on virulence. The yrbH and waaA mutants completely lost their virulence. Conclusions/Significance: We identified Y. pestis receptors for eight bacteriophages. Nine phages together use at least seven different Y. pestis receptors that makes some of them promising for formulation of plague therapeutic cocktails. Most phage-resistant Y. pestis mutants become attenuated and thus should not pose a serious problem for bacteriophag