Lipid Composition of Whole Roots and of Ca2+, Mg2+-activated Adenosine Triphosphatases from Wheat and Oat as Related to Mineral Nutrition

Lipid composition of whole roots of wheat (Triticum vulgare Vill. cv. Svenno Spring Wheat) and oat (Avena sativa L. cv. Brighton) and of cell wall fractions, mitochondrial fractions and microsomal fractions of these roots were studied. Lipid composition depended upon the level of mineral nutrition. In wheat total phospholipids, phosphatidyl choline and sulfolipid content was highest in the roots grown at the higher salt concentration, while the reverse was true for oat roots. In both species glycolipid and sterol content was lower in the high salt roots, at the same time as higher proportions of them were built into the microsomal fraction. Phosphatidyl choline content of the wheat root membrane fractions increased with the salt level, while the opposite occurred in the oat roots. The phosphatidyl choline content may be correlated with the (Ca²⁺, Mg²⁺)-stimulated ATPase activity.     

Mitochondrial gene segregation in mammals: is the bottleneck always narrow?

Summary The segregation of a heteroplasmic silent polymorphism in the mitochondrial ND6 gene has been followed in a human maternal lineage comprising eight individuals and spanning three generations. Heteroplasmy persisted in all eight maternally related family members. More importantly, the frequencies of the two alleles showed relatively little variation among individuals or between generations. In contrast to the findings in other mammalian lineages, the present results indicate relatively slow mitochondrial gene segregation. A narrow bottleneck in the number of mitochondrial DNA (mtDNA) molecules, which occurs at some stage of oogenesis, has been advanced to explain rapid mammalian mitochondrial gene segregation. It is suggested here that the segregation of mitochondrial genes may be more complex than initially envisaged, and that models need to be developed that account for both rapid and slow segregation. One possibility, which reconciles both physical and genetic studies of mammalian mtDNA, is that the unit of mitochondrial segregation is the organelle itself, each containing multiple mtDNA molecules.     

Age-related peculiarities of ratio of parameters of functioning of hemo- and liquorodynamics systems

For the last decade, owing to methods of computerized neuroradiology, it has been established that the process of the human organism natural aging is accompanied by a gradual atrophic reduction of the brain tissue volume and a decrease of the cerebral blood flow level, while the intracranial cerebrospinal fluid volume increases. The goal of the present study was to elucidate functional significance of the above changes in terms of interaction of intracranial hemo- and liquorocirculation systems at various stages of ontogenesis of practically healthy people. The total of 122 people aged from 6 to 100 years were examined at rest and during performance of goal-oriented functional physiological tests with simultaneous continuous recording of parameters of cerebral blood flow and liquorodynamics by methods of transcranial dopplerography and rheoencephalography. The obtained data are processed by means of the pattern and phasic two-dimensional analysis with use of special computer programs. In the same age groups, the brain neurophysiological activity was evaluated by applying special psychological tests. It has been shown that with age, on the background of a decrease of hemodynamic parameters of cerebral blood supply, there is observed an enhancement of the liquorodynamic factor of cerebral blood circulation due to an increase of the liquor volume and facilitation of its translocation in the single craniospinal cavity. The enhancement of the liquor-dependent mechanism of compensation of intracranial pulse oscillations of the blood volume is particularly expressed both in children and in elderly people due to a relatively high liquor volume. Owing to the improvement of intracranial liquorodynamic processes, the change of the cerebral blood circulation is compensated, which is confirmed by results of performed psychophysiological studies.     

Pathogenic Role of SEF14, SEF17, and SEF21 Fimbriae in Salmonella enterica Serovar Enteritidis Infection of Chickens

Very little is known about the contribution of surface appendages of Salmonella enterica serovar Enteritidis to pathogenesis in chickens. This study was designed to clarify the role of SEF14, SEF17, and SEF21 fimbriae in serovar Enteritidis pathogenesis. Stable, single, defined sefA (SEF14), agfA (SEF17), and fimA (SEF21) insertionally inactivated fimbrial gene mutants of serovar Enteritidis were constructed. All mutant strains invaded Caco-2 and HT-29 enterocytes at levels similar to that of the wild type. Both mutant and wild-type strains were ingested equally well by chicken macrophage cell lines HD11 and MQ-NCSU. There were no significant differences in the abilities of these strains to colonize chicken ceca. The SEF14⁻ strain was isolated in lower numbers from the livers of infected chickens and was cleared from the spleens faster than other strains. No significant differences in fecal shedding of these strains were observed.     

Cell Cycle Dependency of Sporulation in Saccharomyces cerevisiae

The study of sporulation in Saccharomyces cerevisiae is complicated by the fact that not all cells in the population complete sporulation and that the kinetics of development of those which do are not synchronous. By separating vegetative cells by zonal rotor centrifugation into fractions of increasing cell volume and hence progressive stages of the vegetative cell cycle, it was possible to observe sporulation of more homogeneous, synchronous populations. The capacity of S. cerevisiae to complete sporulation is low for small single cells at the beginning of the cell cycle and is greatest for large budded cells about to divide. The capacity of a cell to complete sporulation thus appears to be directly related to the stage in the vegetative cell cycle from which it was taken. The use of synchronously sporulating cultures made it possible to examine very early decision events leading to the commitment of a cell to sporulation. In addition, differences in the capacity of a mother and daughter cell produced by cell scission were examined.