[Inheritance of awn absence in tetraploid wheat species]. / Nasledovanie bezostosti u tetraploidnykh vidov pshenits.

Awn absence was shown to be inherited as a dominant character in the tetraploid wheat species Triticum dicoccum (Schrank) Schuebl. and T. durum Desf. but as a recessive one in T. aethiopicum Jakubz. The monogenic control of the character was demonstrated for all studied species. In accessions of emmer and durum wheat, the character is controlled by the dominant gene B1, located on chromosome 5A, and in Ethiopian wheat, by a recessive gene, which we designated as awn. The recessive awn gene was localized on chromosome 3B of T. aethiopicum with the use of D-genome disomic substitution lines of cultivar Langdon.

Retroviral transfer of MRP1 and gamma-glutamyl cysteine synthetase modulates cell sensitivity to L-buthionine-S,R-sulphoximine (BSO): new rationale for the use of BSO in cancer therapy.

MRP1 (multidrug resistance protein 1) co-exports glutathione (GSH) and drug(s) and exports GSH, glucuronide, and sulphate-conjugated drugs. Human Fly-eco fibrosarcoma cells producing the MRP1-expressing retrovirus SF91MRP (Fly-eco MRP1), as well as 3T3 cells transduced with SF91MRP (3T3/MRP1), presented a decrease in intracellular GSH levels, as measured by two different methods. The enhanced export of GSH caused by the overexpression of MRP1 was partially counterbalanced by an increased rate of GSH synthesis. Fly-eco MRP1 and 3T3/MRP1 were hypersensitive to the GSH-depleting and cytotoxic activities of L-buthionine-S,R-sulphoximine (BSO), compared with their parental counterparts. In addition, the potentiation by BSO of the cytotoxic activity of chlorambucil and doxorubicin in Fly-eco MRP1 cells was greater than in parental Fly-eco cells. Although the turnover time of GSH, i.e. the theoretical time in which the entire GSH pool is resynthesised, was approximately 50% faster in Fly-eco MRP1 cells than in parental cells, this was not sufficient to fully restore the intracellular GSH level. In addition, mrp1 (-/-) mice were resistant to the GSH-depleting activity of intraperitoneally (i.p.) injected BSO, compared with mrp1 (+/+) mice. Co-transfer of the cDNAs for MRP1 and the heavy subunit of gamma-glutamyl cysteine synthetase (GCS) resulted in increased intracellular GSH levels and in high-level resistance to the GSH-depleting and cytotoxic activities of BSO. These data, and in particular the elevated single-agent cytotoxicity of BSO, provide a new rationale for the use of BSO in the treatment of MRP1-overexpressing tumours.

Human immunodeficiency virus type 1 reverse transcriptase. Affinity labeling of the primer binding site.

Affinity modification of the primer site of HIV1-RT was performed with an oligonucleotide derivative containing a photoreactive azido group at the 5' end of d(pT)10. The affinity of HIV1-RT for d(pT)10 and for its derivative was first estimated by measuring the Michaelis constants of these two oligonucleotides acting as primers in the retrotranscription of poly(rA). The enzyme was then inactivated under UV-irradiation at 303-365 nm in the presence of ArN3-d(U*T9); the dependence of the rate of inactivation on primer concentration was found to be consistent with the Km value. Last, selectivity of affinity modification was demonstrated through elongation of the covalently bound primer and selective protection of inactivation by d(pT)10 or tRNA(Lys).

Highly selective affinity labeling of the primer-binding site of E. coli DNA polymerase I.

Highly selective affinity labeling of the primer site of E. coli DNA polymerase I was performed with the 5'-reactive derivatives of oligothymidylate in the presence of poly(dA) template. Subtilysine cleavage proved that the site of affinity modification belonged to the 'Klenow' part of DNA polymerase I. If taken separately, Klenow fragment was not labeled by these oligonucleotide derivatives. The site of affinity labeling were tested in the structure of DNA polymerase I by hydroxylamine cleavage. At least two sites of labeling were revealed. The main one was localized between Gly-833 and His-928.

[Covalent labelling of the Klenow fragment of DNA-polymerase I from E. coli]. / Kovalentnoe mechenie fragmenta Klenova DNK-polimerazy I E. coli.

Incubation of the Klenow fragment of E. coli DNA polymerase I with [alpha-32P] dNTP (or NTP) results in the covalent radiolabelling of the enzyme, the bond being stable in acid (pH 2) and alkaline (pH 12) conditions and nucleophiles, such as beta-mercaptoethylamine, efficiently inhibiting the labelling. It is suggested that radiolabelling of the enzyme is the result of formation of chemically active products of the radiolysis of [alpha-32P]NTP (which are likely to be radicals). Non-radioactive NTP hinder the labelling, whereas Mg2+ and polynucleotide do not affect it. Cleavage of the enzyme by hydroxylamine and cyanogen bromide and analysis of gel-electrophoretic patterns of the cleavage products led to conclusion that 32P-label is located between Gly-544 and Met-647.

[Mechanism of the stimulating effect of estradiol on protein kinase C in plasma membranes of target cells]. / Mekhanizmy stimuliruiushchego deistviia éstradiola na proteinkinazu C v plazmaticheskikh membranakh kletok-mishenei.

Using inhibitors and activators of protein kinase C, it was demonstrated that in isolated plasma membranes of target cells estradiol-17 beta selectively stimulates protein phosphorylation by endogenous protein kinase C. In estradiol-dependent tissues, estradiol effectuates the translocation of protein kinase C from the cytosol to the membrane fraction within 10-12 minutes. Estradiol activates protein kinase C in cellular membranes of target tissues via a mechanism which is different from that of phorbol ester (TPA): 3H-estradiol, in contrast with 3H-TPA, it is not bound by protein kinase C and, in contrast with TPA, estradiol-17 beta does not activate purified protein kinase C in vitro. In this case, the specific stimulation of protein kinase C translocation to membranes and the estradiol-induced increase in the phosphorylation of plasma membrane proteins seem to be due to the estradiol-induced activation of the transmembrane system of polyphosphoinositide degradation, eventually resulting in the formation of diacylglycerol, a protein kinase C activator.

[Activation of tyrosine kinases during induction of mammary gland tumors in GR mice by ovarian hormones]. / Aktivatsiia tirozinkinaz pri unduktsii rosta opukholei molochnykh zhelez myshei linii GR ovarial'nymi gormonami.

In GR mice, the induction of proliferative processes in mammary tumours with ovarian hormones (estrone and progesterone) is accompanied by the activation of phosphorylation of plasma membrane, cytosolic and nuclear proteins by endogenous protein kinases. The hormones stimulate tyrosine kinases of tumour cells whose activity is as high as 14.9-17.9% of the total phosphorylation in plasma membranes and 9.5-10.4% in cell nuclei. The ovarian hormones stimulate tyrosine kinases of tumour cells which phosphorylate proteins with Mr of 110-230 and 15 kD (plasma membranes), 170, 52 and 13 kD (cytosol) and 32 kD (nuclei) which are resistant to alkaline hydrolysis. Apart from tyrosine kinases, the ovarian hormones also stimulate serine and threonine protein kinases which seems to be due to the activation of protein kinase C and other protein kinases.

The biochemical mechanisms of the stimulating action of estradiol on the growth of mammary tumours.

The mechanisms of stimulating effect of estradiol on the growth of hormone-dependent mammary tumours in experimental animals were studied. Estradiol receptors were detected in plasmatic membranes of estradiol-dependent tumour cells. Estradiol-independence of tumours was found to be a result of the impairment of the estradiol receptors in the plasmatic membranes, intracellular receptors, or of their ability to interact with the chromatin of the target cells. It was shown that the interaction of receptors of plasmatic membranes of hormone-dependent tumour cells with estradiol results in activation of the membrane adenylate cyclase and in a short-term rise of a cAMP content. A treatment of the hormone-dependent tumours with ovarian hormones brings about an increase in the activity of the cAMP-dependent protein kinases in cell nuclei, which points to their translocation from cytosol. Under effect of estradiol the phosphorylation of nuclear proteins at the serine, threonine and tyrosine residues increases.

[Activation of protein kinase C and cAMP-dependent protein kinase in hormone-dependent mammary gland tumors during stimulation of their growth with progesterone and estrone]. / Aktivatsiia proteinkinazy C i cAMP-zavisimykh proteinkinaz v gormonzavisimykh opukholiakh molochnykh zhelez pri stimuliatsii ikh rosta progesteronom i éstronom.

GR mouse mammary tumour growth is stimulated by simultaneous administration of progesterone and estrone. These hormones strongly activate cAMP-dependent protein kinases both in the cytosol and in humour cell nuclei by causing the elevation of PK-1 and PK-2 activities. Ovarian hormone action on the proliferation is similar to that of growth factors, i.e., the hormones significantly stimulate the calcium-activated, phospholipid-dependent protein kinase C. Protein kinase C has been discovered is growing tumour cell nuclei. In early periods after ovarian hormone administration protein kinase C is activated in a greater degree as compared to cAMP-dependent protein kinases. A hypothesis on the feasibility of simultaneous activation by steroid hormones of both second messenger systems, namely the cAMP system and the system of production of diacylglycerol from phosphtidylinositol diphosphate is proposed.

[DNA reduplication cycle during chromosome polytenization in the salivary gland cells of Chironomus thummi larvae. III. The determination of the duration of the DNA synthesis period]. / Tsikl reduplikatsii DNK pri politenizatsii khromosom v kletkakh sliunnykh zhelez lichinok Chironomus thummi. III. Opredelenie prodolzhitel'nosti perioda sinteza DNK.

The duration of DNA synthesis in the salivary gland cells of Chironomus thummi larvae of the IV instar was determined by means of autoradiography and cytophotometry. Cells of different levels of ploidy differ in the duration of their DNA synthesis period. The tS of 2(10)c and 2(11)c cells was equal to 17 and 22 hours, respectively. The doubling of DNA content of the chironomid salivary gland cells leads to a 1.3 time increase in the duration of S-phase.