[Chromosomal structure of the hybrids between Allium cepa L. and Allium fistulosum L. with relative resistance to downy mildew based on in situ hybridization].

Genomic in situ hybridization (GISH) was used for a chromosomal composition study of the later generations of interspecific hybrids between A. cepa L. and A. fistulosum L., which are relatively resistant to downy mildew (peronosporosis). GISH revealed that F2 hybrids, which did not produce seeds, were triploids (2n = 3x = 24) with 24 chromosomes and possessed in their compliments 16 chromosomes of A. fistulosum L. and eight chromosomes of A. cepa L. or eight chromosomes of A. fistulosum L. and 16 chromosomes of A. cepa L. The advanced F5 hybrid, which produced few seeds, was amphidiploid with 32 chromosomes. BC1F5 hybrid was triploid with eight chromosomes of A. fistulosum L. and 16 chromosomes of A. cepa L., which did not produce seeds. BC2 (BC1F5) plant was amphidiploid that possessed 4 recombinant chromosomes and produced few seeds. GISH results point to 2n-gametes formation in macro- and microsporogenesis of the hybrids. The mechanism of 2n-gametes formation and the possibility of apomixes events in the backcrossing progeny are discussed.

Cyclin-dependent kinase inhibitor p21(Waf1): contemporary view on its role in senescence and oncogenesis.

p21(Waf1) was identified as a protein suppressing cyclin E/A-CDK2 activity and was originally considered as a negative regulator of the cell cycle and a tumor suppressor. It is now considered that p21(Waf1) has alternative functions, and the view of its role in cellular processes has begun to change. At present, p21(Waf1) is known to be involved in regulation of fundamental cellular programs: cell proliferation, differentiation, migration, senescence, and apoptosis. In fact, it not only exhibits antioncogenic, but also oncogenic properties. This review provides a contemporary understanding of the functions of p21(Waf1) depending on its intracellular localization. On one hand, when in the nucleus, it serves as a negative cell cycle regulator and tumor suppressor, in particular by participating in the launch of a senescence program. On the other hand, when p21(Waf1) is localized in the cytoplasm, it acts as an oncogene by regulating migration, apoptosis, and proliferation.

p21(Waf1) is required for cellular senescence but not for cell cycle arrest induced by the HDAC inhibitor sodium butyrate.

Cell senescence is characterized by senescent morphology and permanent loss of proliferative potential. HDAC inhibitors (HDACI) induce senescence and/or apoptosis in many types of tumor cells. Here, we studied the role of cyclin-kinase inhibitor p21(waf1) (Cdkn1n gene) in cell cycle arrest, senescence markers (cell hypertrophy, SA-ßGal staining and accumulation of γH2AX foci) in p21(Waf1+/+) versus p21(Waf1-/-) mouse embryonic fibroblast cells transformed with E1A and cHa-Ras oncogenes (mERas). While short treatment with the HDACI sodium butyrate (NaB) induced a reversible G(1) cell cycle arrest in both parental and p21(Waf1-/-) cells, long-term treatment led to dramatic changes in p21(Waf1+/+) cells only: cell cycle arrest became irreversible and cells become hypertrophic, SA-ßGal-positive and accumulated γH2AX foci associated with mTORC1 activation. The p21(Waf1+/+) cells lost their ability to migrate into the wound and through a porous membrane. Suppression of migration was accompanied by accumulation of vinculin-staining focal adhesions and Ser3-phosphorylation of cofilin, incapable for F-actin depolymerization. In contrast, the knockout of the p21(Waf1) abolished most of the features of NaB-induced senescence, including irreversibility of cell cycle arrest, hypertrophy, additional focal adhesions and block of migration, γH2AX foci accumulation and SA-ßGal staining. Rapamycin, a specific inhibitor of mTORC1 kinase, decreased cellular hypertrophy, canceled coffilin phosphorylation and partially restored cell migration in p21(Waf1+/+) cells. Taken together, our data indicate a new role of p21(Waf1) in cell senescence, which may be connected not only with execution of cell cycle arrest, but also with the development of mTOR-dependent markers of cellular senescence.

[Sodium butyrate do not induce the program of premature senescence in transformants with JNK1,2 knockout].

We studied the role of JNK1,2 stress-kinases in the regulation of premature senescence program, stimulated by the inhibitor of histone deacetylase, sodium butyrate (NaB). It was found, that the transformants EIA + cHa-ras selected from embryonic mouse fibroblasts with knockout jnk1,2 stress-kinase genes did not block the cell cycle after sodium butyrate treatment. The data on the cell cycle distribution and cell growth curves showed that even long term (during five days) NaB influence did not suppress proliferation. We did not also reveal any cellular hypertrophy and increase in SA-beta-galactosidase activity after NaB treatment. The data presented suggest that JNK stress-kinases are involved in sodium butyrate-induced senescence in E1A + cHa-Ras mouse transformants, and they are indicative of that JNK1,2 have tumor suppressor properties.

[Role of p38alpha kinase in activation of premature senescence program in transformed mouse fibroblasts].

We investigated the role of p38alpha stress-kinase in regulation of premature senescence program, stimulated by histone deacetylase inhibitor--sodium butyrate (NaB)--after application to rodent transformed cell lines. Investigation was performed on the E1A + cHa-ras transformants selected from mice embryonic fibroblasts null at the p38alpha kinase gene or null fibroblasts at the PPM1D gene, which encoded phosphatase Wip1. Absence of Wip1 led to constitutive activation of p38alpha kinase. It was revealed that after NaB treatment both cell lines completely stopped proliferation due to irreversible cell cycle arrest in G1/S phase. In both cell lines sodium butyrate induced sustained block of prolifaration due to irreversible cell cycle arrest in G1/S phase. Following sodium butyrate treatment cells expressed marker of senescence--beta-galactosidase activity (SA-beta-Gal). Long-term (during several days) NaB treatment of cells led to partial restoration of actin cytoskeleton, focal adhesion contacts and heterochromatin focus formation (SAHF) in the nucleus of senescent cells. Obtained data allow us to suppose that irreversible process of cellular senescence activated by sodium butyrate can occur in the absence of functionally active p38 kinase by means of other ways of cell cycle suppression.

[Squamous cell esophageal cancer with metastases to the myocardium].

An autopsy case is reported. The patient died of esophageal cancer. At autopsy a massive metastasis to the myocardium was revealed.

[E1A oncogene effect on the ability of p21(Waf1) to regulate G1/S arrest in E1A-expressing transformants following irradiation].

P21(Waf1) cyclin-dependent kinase inhibitor blocks cell cycle transition from G1 phase into DNA replication after DNA damage. The main targets of p21(Waf1) are Cyc 1E--Cdk2 and Cyc 1A--Cdk2 complexes, PCNA (proliferating cell nuclear antigen), a subunit of DNA polymerase delta, and E2F-1 transcription factor. The universal mechanism of cell cycle arrest in normal cells is determined as p21(Waf1) interaction with positive regulators of G1 phase. As a rule, DNA integrity control mechanisms are destroyed in the process of oncogenic transformation, which results in proliferation of genetically defective cells. The purpose of our study was to investigate molecular mechanisms of cell cycle regulation in transformants that are able (E1A + E1B-19kDa) or unable (E1A(+) + cHa-ras) to be arrested at G1/S checkpoint. We have shown that p21(Waf1) is able to form complexes with cyclins and Cdks, PCNA and E2F-1 transcryption factor, although it interacts with E1A oncoproducts in both transformants. The presence of E1A bound p21(Waf1) in cyclin-kinase complexes seems to be the cause of activating phosphorilation of Cdk2 at Thr-160 in cyclin A/E--Cdk2 complexes in both control and X-ray irradiated cells. Thus, the absence of G1/S arrest following irradiation in E1A + cHa-ras transformants and its presence in E1A(+) + E1B-19kDa transformants is not connected with differences in interaction of p21(waf1) with the main regulators of G1-to-S transition, but is realized through other not yet identified ways.

[Specificity of ultrastructural changes in the myocardium of rats after hypokinesia and irradiation]. / Spetsifichnost' ul'trastrukturnykh izmenenii v miokarde krys pri gipokinezii i luchevom porazhenii.

By electron microscopy and morphometry cardiomyocytes of 20 rats gamma-irradiated with a single dose of 180.6 microCi/kg and those of 20 rats exposed to hypokinesia for 10 days were examined. Visually the ultrastructural changes of cardiomyocytes were nonspecific. The morphometric examination revealed specific features of ultrastructural rearrangements in the nuclei and mitochondria of cardiomyocytes of rats on day 10 of hypokinesia and irradiation.

[Ultrastructural changes in the hepatocytes of dogs continuously exposed to chronic low-dose gamma irradiation]. / Ul'trastrukturnye izmeneniia gepatotsitov sobak v usloviiakh postoiannogo khronicheskogo gamma-oblucheniia v malykh dozakh.

Electron microscopy of the liver of dogs exposed to chronic 6-year gamma-irradiation from the CO60 source demonstrated early changes in the hepatocyte structure at a relatively low dosage of 63 rad for 3 years. A comparative study of the submicroscopic reaction of hepatocytes of 3 groups of test dogs showed pronounced changes in the endoplasmatic reticulum: vacuolar transformation balloon dystrophy. The heterogeneity of ultrastructural changes of different hepatocytes was probably associated with a simultaneous development of processes of injury, reparation and adaptation of intracellular structures during the long-term gamma-irradiation exposure. Parallel development of these processes assured reparative biosynthesis to maintain the normal hepatic function.

[Ultrastructure of the lymph nodes of dogs under prolonged external gamma irradiation]. / Ul'trastruktura limfaticheskikh uzlov u sobak pri dlitel'nom vneshnem gamma-obluchenii.

The purpose of the present investigation was electron microscopy study of lymph nodes of dogs exposed to chronic gamma-irradiation during 6 years (with a total dose of 125 rad/year). The exposure induced changes in the cell composition of the paracortical regions due to a decrease of the count of small lymphocytes and a predominant increase of young blast cells with an altered ultrastructure. Chronic gamma-irradiation led to an increase of the number of plasma cells and emergence of intermediate cell forms due to "plasmatization" of lymphocytes and reticular cells.

[Quantitative evaluation of ultrastructural changes in the rat myocardium during prolonged hypokinesia]. / Kolichestvennaia otsenka ul'trastrukturnykh izmenenii v miokarde krys pri dlitel'noi gipokinezii

It was morphometrically shown that during 120-day hypokinesia chromatin redistribution was similar in nuclei of myocardial cells of the ventricles of the rat heart. Quantitative rearrangements in the mitochondrial apparatus of cells were of different pattern. On the 14th hypokinetic day the number of mitochondria increased and their size decreased; on the 30th day their size increased and their number decreased; on the 45 and 60th day the number and size of mitochondria returned to the normal; on the 120th hypokinetic day the number and size of mitochondria were higher than the control. Throughout the 120-day experimental the ratio of the total area of mitochondria to the total area of myofibers varied periodically and by the end of the experimental the mitochondrial area increased. Thus, it is obvious that by the 120th hypokinetic day myocardial changes increased indicating a new level of cardiac activity during prolonged hypokinesia. Quantitative changes in the organelles of the myocardium of the left ventricle were more significant than those of the right ventricle during the exposure.