Segregation Distortion of Marker Nuclear Genes in Alloplasmic and Isoplasmic Lines of Barley

Inheritance of barley nuclear genes responsible for various morphological marker traits was studied in hybrid populations F₂ and F_a. Nine marker genes showed deviation from Mendelian monogenic inheritance depending on the cross direction and maternal cytoplasm. Segregation biases to both recessive mutant and dominant normal phenotypes were observed. Mechanisms of the segregation bias related to cytoplasm substitution in iso- and alloplasmic lines are discussed.     

Uniparental Genetic Heritage of Belarusians: Encounter of Rare Middle Eastern Matrilineages with a Central European Mitochondrial DNA Pool

Ethnic Belarusians make up more than 80% of the nine and half million people inhabiting the Republic of Belarus. Belarusians together with Ukrainians and Russians represent the East Slavic linguistic group, largest both in numbers and territory, inhabiting East Europe alongside Baltic-, Finno-Permic- and Turkic-speaking people. Till date, only a limited number of low resolution genetic studies have been performed on this population. Therefore, with the phylogeographic analysis of 565 Y-chromosomes and 267 mitochondrial DNAs from six well covered geographic sub-regions of Belarus we strove to complement the existing genetic profile of eastern Europeans. Our results reveal that around 80% of the paternal Belarusian gene pool is composed of R1a, I2a and N1c Y-chromosome haplogroups – a profile which is very similar to the two other eastern European populations – Ukrainians and Russians. The maternal Belarusian gene pool encompasses a full range of West Eurasian haplogroups and agrees well with the genetic structure of central-east European populations. Our data attest that latitudinal gradients characterize the variation of the uniparentally transmitted gene pools of modern Belarusians. In particular, the Y-chromosome reflects movements of people in central-east Europe, starting probably as early as the beginning of the Holocene. Furthermore, the matrilineal legacy of Belarusians retains two rare mitochondrial DNA haplogroups, N1a3 and N3, whose phylogeographies were explored in detail after de novo sequencing of 20 and 13 complete mitogenomes, respectively, from all over Eurasia. Our phylogeographic analyses reveal that two mitochondrial DNA lineages, N3 and N1a3, both of Middle Eastern origin, might mark distinct events of matrilineal gene flow to Europe: during the mid-Holocene period and around the Pleistocene-Holocene transition, respectively.     

C-terminal domain of saccharomyces cerevisiae protein ChI4 binds to centromere DNA fragment of yeast chromosome III

We have expressed in Escherichia coli a recombinant protein consisting of N-terminal peptide omega 10s10 (11 aa) fused with part (aa 135-458) of yeast protein Chl4 involved in the chromosome segregation in Saccharomyces cerevisiae. Mice were immunized with the antigen purified from inclusion bodies, and a polyclonal serum against yeast protein Chl4 was raised. MW of the detected yeast protein Chl4 was approximately 54 kDa, corresponding to the full length ORF translation. C-terminal portion of Chl4 (aa 376-458), containing Helin-Turn-Helix (HTH) motif of DNA-binding, was fused in frame after E. coli maltose binding protein MalE. The soluble fusion was affinity purified using an alternative procedure on the preswollen amylose column. This protein and a 32P labelled 620 bp fragment of yeast CEN3 DNA were used in the DNA-mobility shift assay in polyacrylamide and agarose gels. The binding was detected in the presence and absence of Zn2+ ions. The data obtained could support participation of Chl4 in a direct binding to the yeast centromere in the CBF complex. The result is in a certain agreement with the data on photocrosslinking proteins of the CBF3 complex with the centromere DNA, where the minor protein with a molecular weight of 55-55 kDa was also detected (Espelin C. W. et al., 1997. J. Cell Biol. 139: 1383-1396).     

A Method for Isolation of Chloroplast DNA and Mitochondrial DNA from Sunflower

We present a method for isolation of chloroplast and mitochondrial DNA from sunflower seedlings. The protocol includes: organelle isolation, deoxyribonuclease treatment, lysis, deproteinisation and a final DNA purification with sodium dodecyl sulphate and potassium acetate. The organelle DNA yield is 5–10 micrograms per gram of tissue and the DNA is fully restrictable. The technique is inexpensive and appropriate for the isolation of multiple samples of organelle DNA from a small amount of tissue.     

Analysis of the segregation and recombination rates at morphological and SSR loci in hybrid combinations of barley substitution lines

The inheritance of nuclear morphological and molecular markers was studied in hybrid reciprocal populations of barley alloplasmic lines. A number of loci displayed a distortion of the Mendelian inheritance and a decrease in recombination rate depending on the cross direction and cytoplasm of parental forms. The segregations shifted towards both the mutant recessive and normal dominant phenotypes. The effect of cytoplasm on transmission and recombination of nuclear loci was shown.     

Polo-like kinase-1 regulates kinetochore-microtubule dynamics and spindle checkpoint silencing

Polo-like kinase-1 (Plk1) is a highly conserved kinase with multiple mitotic functions. Plk1 localizes to prometaphase kinetochores and is reduced at metaphase kinetochores, similar to many checkpoint signaling proteins, but Plk1 is not required for spindle checkpoint function. Plk1 is also implicated in stabilizing kinetochore-microtubule attachments, but these attachments are most stable when kinetochore Plk1 levels are low at metaphase. Therefore, it is unclear how Plk1 function at kinetochores can be understood in the context of its dynamic localization. In this paper, we show that Plk1 activity suppresses kinetochore-microtubule dynamics to stabilize initial attachments in prometaphase, and Plk1 removal from kinetochores is necessary to maintain dynamic microtubules in metaphase. Constitutively targeting Plk1 to kinetochores maintained high activity at metaphase, leading to reduced interkinetochore tension and intrakinetochore stretch, a checkpoint-dependent mitotic arrest, and accumulation of microtubule attachment errors. Together, our data show that Plk1 dynamics at kinetochores control two critical mitotic processes: initially establishing correct kinetochore-microtubule attachments and subsequently silencing the spindle checkpoint.     

Cardiac Rhythm Variability: Approaches to Mechanisms

Physiological mechanisms of cardiac rhythm variability (CRV) are reviewed. The results of original experiments are discussed together with the history of the problem and data available from the literature. Special emphasis is placed on the spectral analysis of cardiac rhythm. Various mechanisms of the generation of periodic and aperiodic components of CRV are considered. Although the variability of cardiac rhythm has been studied for many years in many laboratories worldwide, fine mechanisms of CRV remain obscure. However, a number of specific features of CRV are presently widely recognized. Periodic CRV components isolated from short-term records in patients at rest are represented by high-frequency, low-frequency, and very low-frequency oscillations. Fourier-transform spectral analysis of cardiac rhythm is the most appropriate method of the detection of these oscillations. High-frequency components are associated with respiration and represent the effects of the parasympathetic nervous system on myocardium. Low-frequency components are due to the activity of the postganglionic sympathetic fibers and represent the processes of cardiac rhythm modulation by the sympathetic nervous system. Genesis of very low-frequency oscillations is still uncertain. Most probably, these oscillations are associated with the effects of suprasegmental (primarily, hypothalamic) centers of autonomic regulation. Aperiodic CRV components represent random events associated with the reflex regulation of the heart rate by external or internal factors. Because aperiodic components significantly modify the results of the CRV analysis, the effects of these factors should be eliminated. It is concluded that because many problems associated with cardiac rhythm variability remain to be solved, extensive research in this direction should be continued.     

ABCA1 mRNA and protein levels in M-CSF-activated macrophages from patients with arterial stenosis

ABCA1 transporter is one of the key factors defining the level of antiatherogenic HDL in plasma. It is involved in cholesterol removal from peripheral tissues by reverse cholesterol transport. However, the influence of ABCA1 mRNA and ABCA1 protein levels in macrophages on atherosclerosis remains unexplored. Using real-time PCR, we determined the ABCA1 mRNA level in macrophages cultured for 5 days with macrophage colony-stimulating factor (M-CSF). The ABCA1 mRNA level in macrophages from patients with arterial stenosis was increased compared to the control group, p = 0.04. Western-blot assayed ABCA1 protein content in macrophages from patients was significantly lower than in the control group, p = 0.01. Our results suggest that ABCA1 mRNA and ABCA1 protein levels in macrophages may be important factors in the development of atherosclerosis.     

Lysine overproduction mutations in the yeast Saccharomyces cerevisiae and its transfection into industrial Yeast strains ]

Yeast mutants resistant to a toxic lysine analog, thialysine were obtained by a method described in the literature. A strain excreting the maximum amount of lysine (0.45 g/l) was selected from these mutants. The intracellular content of lysine was also increased by 30%. The genetic nature of lysine overproduction was studied in this strain. An increase in the amount of excreted lysine was shown to be determined by at least two genes, one of which carries a mutation of thialysine resistance manifesting the pleiotropic effect of lysine overproduction (Th1R) and the other is involved in the regulation of lysine production (PRL). Linkage groups of these genes were determined: the first gene was mapped to the IV chromosome and the second, to the XV chromosome. Both genetic characters were introduced into industrial baker's yeast strains via a series of backcrosses. The stabilization of the genome in the newly derived strains was confirmed by electrokaryotyping.