Persistence of arctic-alpine flora during 24,000 years of environmental change in the Polar Urals.

Plants adapted to extreme conditions can be at high risk from climate change; arctic-alpine plants, in particular, could "run out of space" as they are out-competed by expansion of woody vegetation. Mountain regions could potentially provide safe sites for arctic-alpine plants in a warmer climate, but empirical evidence is fragmentary. Here we present a 24,000-year record of species persistence based on sedimentary ancient DNA (sedaDNA) from Lake Bolshoye Shchuchye (Polar Urals). We provide robust evidence of long-term persistence of arctic-alpine plants through large-magnitude climate changes but document a decline in their diversity during a past expansion of woody vegetation. Nevertheless, most of the plants that were present during the last glacial interval, including all of the arctic-alpines, are still found in the region today. This underlines the conservation significance of mountain landscapes via their provision of a range of habitats that confer resilience to climate change, particularly for arctic-alpine taxa.

The role of the nucleocytoplasmic ratio in development regulation of the early mouse embryo.

The hypothesis suggesting that the blastocoele is able to form only at a definite nucleocytoplasmic ratio was tested. We compared the development of preimplantation mouse embryos under different conditions. The results demonstrated that the start of cavitation is not dependent on the number of cell divisions. Thus, a definite nucleocytoplasmic ratio is not required for blastocoele formation to start. Our studies on embryos with microsurgically altered cytoplasm content provided evidence for the following biological clock mechanism: a change in the cell program of morphogenesis needs definite concentration of the products of a previous genetic program.

Platelet aggregation and prostaglandin metabolites in the blood of patients with ischaemic heart disease during antiarrhythmic treatment.

The influence of antiarrhythmic drugs (oral lidocaine, palpitine, Etacizine) on blood platelet aggregation and prostaglandin metabolites was studied in 91 patients with ischaemic heart disease. Lidocaine showed a positive, Etacizine a negative, and palpitine no effect on platelet aggregation. There was no uniform effect of lidocaine on prostaglandin metabolites; it increased the prostacycline and decreased the thromboxane levels. Palpitine increased both prostacyclin and thromboxane levels, whereas Etacizine decreased both metabolites, especially prostacyclin.

[Effect of anti-arrhythmia preparations on thrombocytic and vascular hemostasis]. / Vliianie nekotorykh antiaritmicheskikh preparatov na trombotsitarnyi i sosudistyi gemostaz.

Platelet aggregation, prostacyclin and thromboxane were studied in 35 individuals: 20 coronary patients with angina of effort and 15 high-risk patients before and after treatment with lidocaine and pyromecaine. Oral administration of lidocaine and pyromecaine pills considerably depresses platelet aggregation and even causes platelet disaggregation. However, lidocaine disaggregating effect is greater than that of pyromecaine. Both agents affect vascular hemostasis by reducing thrombaxane and raising prostacyclin levels. Hence, the anti-aggregant effect of anti-arrhythmic proocaines may be attributed to changes in vascular hemostasis. The results obtained are expanding the range of indications for the use of these drugs.

[Development and survival of mouse embryos in intra- and interstrain transplants]. / Razvitie i vyzhivaemost' zarodyshei myshei pri vnutri- i mezhlineinykh transplantatsiiakh.

Survival rate and weight of embryos were studied in the Balb/c, CBA//ac and C57BL/6j mice, developed from several combinations of transplantation. The weight of allogenic fetus as well as syngenic fetus which developed together with allogenic ones was detected to increase. This increased weight does not result from survival of certain genotype embryos, but seems to be due to genetical differences in the mother-embryo system.

[Morphometric study of the spleen in C57BL strain mice during pregnancy with syngeneic or allogeneic embryos]. / Morfometricheskoe issledovanie selezenki myshei linii C57BL pri beremennosti singennymi ili allogennymi émbrionami.

A morphological study of the spleen in the C57BL line female mice on the 16th day of pregnancy showed a significant increase in the relative area of generative centres and red pulp and a decrease in the white pulp relative area as well as a rise in the amount of plasmatic cells and blast forms in red pulp during allogenic pregnancy (BALB embryos). Such changes are supposed to favour both the preservation of the intact mother-extrafetal organs-fetus system and the improvement of allogenic embryos trophics.

[Role of the genetic-physiological interrelationships of mother-progeny in establishing the viability and fertility of mammals. II. The weight of the embryos of BALB, CBA and DBA strain mice developing from transplanted blastocysts]. / Rol' genetiko-fiziologicheskikh vzaimootnoshenii mat'-potomok v stanovlenii zhiznesposobnosti i plodovitosti mlekopitaiushchikh. Soobshchenie II. Ves zarodyshei myshei linii BALB, CBA i DBA, razvivaiushchikhsia iz peresazhennykh blastotsist.

The weights of embryos and their placentas obtained by blastocysts of CBA/LacY and DBA/2 mouse strains transfer in recipient females of BALB/c strain and also by blastocysts of BALB/c mouse strain transfer in recipient females of CBA/LacY strain were analysed on the 16th gestation day. It is shown that placental weights are determined by genotypic peculiarities of embryos, although comparative placental weights of different strain embryos could also depend on females fertility. The weight of allogenic embryos (developed from transferred blastocysts) significantly excessed the weight of singenic embryos, and most significant differences were noted in females with small number of embryos. The possibilities to solve some applied and fundamental problems of mammalian reproduction given by the method of interstrain and interbreed early stage embryos transfer are discussed.

[Embryo survival rate of BALB and C57BL line mice in reciprocal transplantations at early stages of development]. / Vyzhivaemost' émbrionov myshei linii BALB i C57BL pri ikh retsiproknykh peresadkakh na rannikh stadiiakh razvitiia.

Survival rate and weight were studied for the BALB/c and C57Bl/6J mice embryos developed from transplanted 2- and 3-day-old blastocysts. The greatest number of implantations was observed when 3-day-old blastocysts were transplanted to recipient females with two-day pregnancy. The number of implantations and successfully developing transplanted embryos was increased in recipient female with a higher number of corpora lutea.