Mating Systems and Seed Reproduction in Gynodioecious Geranium asiaticum (Geraniaceae).

Mating systems and seed reproduction in gynodioecious Geranium asiaticum Serg. (G. bifolium Patrin.) were studied in four coenopopulations of Western Siberia (Novosibirsk region). The bisexual flower of hermaphrodite individuals of G. asiaticum is characterized by a longer flowering (2.5-3.5 days) than the pistillate flower of female individuals (2-2.5 days), due to the passage of the male (staminate) phase at the beginning of morphogenesis: G. asiaticum is characterized by strict protandry. Mating of individuals of G. asiaticum occurs according to the type of xenogamy, autogamy is completely excluded. In an experiment to isolate individual flowers, 100% of isolated pistillate and bisexual flowers dried up without fertilization. In an experiment on artificial pollination of flowers, 85% (17 out of 20 flowers) of pistillate flowers formed fruits, whereas only 10% (3 out of 30 flowers) of bisexual flowers formed fruits. There were no significant differences in the number of flowers on the generative shoot in female and hermaphrodite individuals. Significant differences were found between heterosexual individuals in terms of the number of fruits and the number of seeds per generative shoot: female individuals formed 16.1-22.1 times more fruits and 13.8-28.3 times more seeds than hermaphrodites. Pistillate flowers formed an average of 1.85 ± 0.08 seeds per flower, and bisexual flowers 0.07 ± 0.02 seeds per flower, i.e., on average, female plants form 26.4 times more seeds than hermaphrodites. It was found that the fruits and seeds were formed mainly by female individuals, but hermaphrodite individuals produced the pollen necessary for fertilization. The different degree of sexual differentiation of G. asiaticum and Geranium sylvaticum L. suggests that in genus Geranium there are transformations in direction of the formation of dioecy.

[Mechanism of the mutagenic action of the tick-borne encephalitis virus]. / O mekhanizme mutagennogo deistviia virusa kleshchevogo éntsefalita.

The results of cytogenetic analysis of pig embryo kidney cells infected at a high multiplicity (5-10 PFU/cell) with tick-borne encephalitis virus. The dynamics of formations of virus-induced chromosome aberrations differed markedly from that observed at lower multiplicities of infection. No increase of the mutagenic effect with increasing infective dose of the virus was found, however. The assumption that TBE virus mutagenic properties are associated with structural virus proteins is discussed. Attenuated variants of TBE virus were shown to have no mutagenic properties.

[Effect of the tick-borne encephalitis virus on the chromosomes and cell division in different cell cultures]. / Vliianie virusa kleshchevogo éntsefalita na khromosomy i delenie kletok v razlichnykh kletochnykh kul'turakh.

The mutagenic effect of tick-borne encephalitis virus (the Pan strain) was studied in chick embryo cells, Syrian hamster kidney cells and pig embryo kidney (SPEV) cell cultures showing different sensitivities to this virus. The dynamics of formation and types of chromosome damages were shown to be different in latent, subacute and acute forms of infection. Virus-induced chromosome aberrations appeared in the period of termination of the virus reproduction cycle. Differences in the effect of tick-borne encephalitis virus on the synthesis of nuclear DNA in chick embryo and SPEV cells were demonstrated. The experimental results suggest that a temporary increase of the mitotic activity observed in the inoculated cultures was due both to a delay of cells in one of the stages of the mitotic cycle (chick embryo and SPEV cells) and to a temporary stimulation of DNA synthesis (SPEV cells).