The chianti zebrafish mutant provides a model for erythroid-specific disruption of transferrin receptor 1

Iron is a crucial metal for normal development, being required for the production of heme, which is incorporated into cytochromes and hemoglobin. The zebrafish chianti (cia) mutant manifests a hypochromic, microcytic anemia after the onset of embryonic circulation, indicative of a perturbation in red blood cell hemoglobin production. We show that cia encodes tfr1a, which is specifically expressed in the developing blood and requisite only for iron uptake in erythroid precursors. In the process of isolating zebrafish tfr1, we discovered two tfr1-like genes (tfr1a and tfr1b) and a single tfr2 ortholog. Abrogation of tfr1b function using antisense morpholinos revealed that this paralog was dispensable for hemoglobin production in red cells. tfr1b morphants exhibited growth retardation and brain necrosis, similar to the central nervous system defects observed in the Tfr1 null mouse, indicating that tfr1b is probably used by non-erythroid tissues for iron acquisition. Overexpression of mouse Tfr1, mouse Tfr2, and zebrafish tfr1b partially rescued hypochromia in cia embryos, establishing that each of these transferrin receptors are capable of supporting iron uptake for hemoglobin production in vivo. Taken together, these data show that zebrafish tfr1a and tfr1b share biochemical function but have restricted domains of tissue expression, and establish a genetic model to study the specific function of Tfr1 in erythroid cells.     

Qualitative and quantitative composition of intestinal microflora in healthy young children

The results of the qualitative and quantitative analysis of the microflora of the large intestine in 45 healthy children aged 6, 8, 10 months and 1 year, living in Moscow, are presented. During the first year of life high concentrations and detection rate of not only bifidobacteria, enterococci, nonpathogenic Escherichia, but also bacteria, commonly regarded as opportunistic were typical. The latter include lecithinase positive Clostridium, citrate assimilating enterobacteria, as well as Escherichia with low biochemical activity and capacity for hemolysin production. In addition, this group also includes coagulase-positive staphylococci. Later on, as these children become older, opportunistic bacteria are partially or completely eliminated under normal conditions. Suggestion is made that the composition of intestinal microflora depends on protective and other systems of the host at different periods of life, as well as on the character of nutrition and the microbial contamination of the environment.     

Strategy of production and utilization of immortal cells

The current methods of production of conditionally immortal cells in vivo and in vitro have been considered, including the method based on transgenesis of animals. Examples are given for utilization of conditionally immortal cells obtained in vivo from tissues of transgenic mice and rats carrying the gene of mutant T-antigen tsA58 SV40. The recent studies were analyzed, which concern the investigation and utilization of embryonic and regional stem cells, as well as immortal cells obtained through transfection of the recombinant construct of telomerase gene into human cells. The main problems of cell biotechnology are discussed.     

ATPase and phosphatase activity of drone brood

Most researches on insect enzymes concern carbohydrate and nitrogenous exchange. Data on ATPase activity for larval material of drone brood are absent in the available literature. The drone brood is one of the least investigated apiproducts. Allowing for the important role of ATPase in the vital functions of the insect cells our work was aimed at the study of ATPase of the drone blood activity and that of alkaline and acid phosphatases. When studying liophylised preparations of the drone brood homogenate we have found out high activity of Mg2+, Na+, K+-, Ca2+- and Mg2+-ATPase and of alkaline and acid phosphatase, that is the possible explanation of the high-intensity power and plastic processes proceeding during growth and development of larvae.