Doubly Uniparental Inheritance of Mitochondria As a Model System for Studying Germ Line Formation

BACKGROUND: Doubly Uniparental Inheritance (DUI) of mitochondria occurs when both mothers and fathers are capable of transmitting mitochondria to their offspring, in contrast to the typical Strictly Maternal Inheritance (SMI). DUI was found in some bivalve molluscs, in which two mitochondrial genomes are inherited, one through eggs, the other through sperm. During male embryo development, spermatozoon mitochondria aggregate in proximity of the first cleavage furrow and end up in the primordial germ cells, while they are dispersed in female embryos. METHODOLOGY/PRINCIPAL FINDINGS: We used MitoTracker, microtubule staining and transmission electron microscopy to examine the mechanisms of this unusual distribution of sperm mitochondria in the DUI species Ruditapes philippinarum. Our results suggest that in male embryos the midbody deriving from the mitotic spindle of the first division concurs in positioning the aggregate of sperm mitochondria. Furthermore, an immunocytochemical analysis showed that the germ line determinant Vasa segregates close to the first cleavage furrow. CONCLUSIONS/SIGNIFICANCE: In DUI male embryos, spermatozoon mitochondria aggregate in a stable area on the animal-vegetal axis: in organisms with spiral segmentation this zone is not involved in cleavage, so the aggregation is maintained. Moreover, sperm mitochondria reach the same embryonic area in which also germ plasm is transferred. In 2-blastomere embryos, the segregation of sperm mitochondria in the same region with Vasa suggests their contribution in male germ line formation. In DUI male embryos, M-type mitochondria must be recognized by egg factors to be actively transferred in the germ line, where they become dominant replacing the Balbiani body mitochondria. The typical features of germ line assembly point to a common biological mechanism shared by DUI and SMI organisms. Although the molecular dynamics of the segregation of sperm mitochondria in DUI species are unknown, they could be a variation of the mechanism regulating the mitochondrial bottleneck in all metazoans

FREQUENCY OF DETECTION OF ANTIBODIES TO HEPATITIS C VIRUS AMONG CONVENTIONALLY HEALTHY POPULATION OF RUSSIAN FEDERATION

Aim. Determine the prevalence of antibodies to hepatitis C virus (anti-HCV) among conditionally healthy population of Russian Federation. Materials and methods. Sera samples obtained from conditionally healthy population of the Russian Federation from 5 geographically distant regions with different levels of morbidity for hepatitis C were studied: Sverdlovsk, Rostov, Moscow regions, Tyva and Sakha (Yakutia) Republics. 4764 samples were studied in total obtained from individuals of 10 age groups: younger than 1, 1 - 4, 5 - 9, 10 - 14,15 - 19, 20 - 29, 30 - 39, 40 - 49,50 - 59, olderthan 60 years. Anti-HCV were determined by commercial ELISA. Results. The total prevalence of anti-HCV in 5 regions of Russian Federation was 2.6% (126/4764). The highest frequency of detection of anti-HCV was detected in Tyva and Yakutia Republics and was 3.3%, in other regions this parameter varied from 1,7 (Moscow region) to 3% in Sverdlovsk region. Peak parameters of anti-HCV detection among population in various regions were connected with various age groups: olderthan 60 years in Tyva and Yakutia Republics (11 and 9.9%, respectively), 40 - 49 in Moscow region (6.2%), 1 - 4 and 30 - 39 years in Sverdlovsk region (5.9 and 4.9%, respectively) and 20 - 39 in Rostov region (3.9%). Conclusion. Results of anti-HCV detection in various age cohorts of conditionally healthy population of Russian Federation give evidence regarding high morbidity with HCV of almost all the age groups in the interval from 20 to older than 60 years. Age cohorts were detected in each of the studied regions for which inclusion into regional screening programs is feasible