Intra- and inter-specific effects of mast seeding on seed fates of two sympatric <Emphasis Type="Italic">Corylus</Emphasis> species

We released seeds of two sympatric tree species, Corylus mandshurica (seed with thinner seed hull, higher nutrition) and C. heterophylla (seeds with thicker seed hull, lower nutrition) in the masting year of C. mandshurica in 2008, and C. heterophylla in 2009, respectively, to investigate how seed masting of the two sympatric Corylus species affects seed removal and dispersal fitness of the two species differently at both intra- and inter-specific levels. At intra-specific level, the authors found mast seeding of both C. mandshurica and C. heterophylla significantly reduced seed removal, seed consumption, but increased seed dispersal distance and seed dispersal fitness of the released seeds. Mast seeding of C. mandshurica increased seed caching of C. mandshurica. At inter-specific level, the authors found mast seeding of C. mandshurica reduced seed removal of C. heterophylla, but mast seeding of C. heterophylla did not significantly reduce seed removal of C. mandshurica. Mast seeding of C. mandshurica reduced seed consumption of C. heterophylla, while mast seeding of C. heterophylla reduced seed consumption of C. mandshurica. We found mast seeding of C. mandshurica significantly reduced seed dispersal distance of C. heterophylla, while mast seeding of C. heterophylla significantly increased seed dispersal distance of C. mandshurica. We found that mast seeding of C. mandshurica significantly increased seed dispersal fitness of C. heterophylla, while mast seeding of C. heterophylla did not significantly increase seed dispersal fitness of C. mandshurica. More studies are needed to reveal the ecological consequences of mast seeding at inter-specific or community-level. Seed traits may attribute the differences of mast seeding at inter-specific level. Because seeds with thinner seed hull and higher nutrition were more harvested and eaten by rodents, mast seeding of C. mandshurica might have reduced seed removal and seed consumption, but increased dispersal fitness of C. heterophylla (seeds with thicker seed hull, lower nutrition). Therefore, synchrony among species is, or is not, selectively beneficial to the focus species depends on seed traits which determine gains from mast seeding at inter-specific level.     

Interferon-γ effect on growth regulation of cells with different levels of EGF receptor expression

Interferon gamma (IFNγ) is known to inhibit the proliferation of some transformed cell lines. Recently, we demonstrated the transactivation of the epidermal growth factor receptor (EGFR) in response to IFNγ (Burova et al., 2007) and provided direct evidence for the dependence of IFNγ-induced EGFR transactivation on the EGFR expression level in epithelial cells (Gonchar et al., 2008). This study examines an antiproliferative effect of IFNγ on human epithelial cell lines—A431 and HeLa that express high levels of EGFR, as well as HEK293 that expresses low levels of EGFR. To characterize the IFNγ-induced changes in these cells, we studied cell growth, the cell cycle, and induction of apoptosis. The response to IFNγ differed in the compared cell lines; cell growth was inhibited in both A431 and HeLa cells, but not in HEK293 cells, as was shown by the cell count and MTT. The cell-cycle phases analyzed by flow cytometry were disturbed in A431 and HeLa cells in response to IFNγ. On the contrary, in HEK293 cells, the IFNγ treatment did not alter distribution by cell cycle phases. Our results indicate that IFNγ produces an antiproliferative effect that depends on the increased expression of EGFR in A431 and HeLa cells. Furthermore, it was demonstrated that IFNγ induced the caspase 3 activation in A431 cells, which suggests the involvement of active caspase 3 in the IFNγ-induced apoptosis.     

Immune relations between mother and foetus in the viviparous poeciliid fish Xiphophorus hellerii Haeckel

Advanced embryos of the viviparous poeciliid fish Xiphophorus hellerii (swordtail) were removed from the site of gestation within the ovary and re-implanted into the peritoneal cavities of unrelated immunologically competent adults of the same species. Most of those transplanted with intact fertilization membranes were normal in appearance, and many were clearly still alive. Those transplanted without a fertilization membrane were all dead, with lymphocyte infiltration and other evidence of rejection as allografts. The integrity of the membrane in late pregnancy was indicated by swelling of follicles in hypoosmotic liquid. It was concluded that the fertilization membrane is capable of protecting an antigenically foreign embryo in an immunologically hostile environment, and that it probably serves this function during normal pregnancy.     

Preliminary clinical experience with the antiarrhythmic effect of PGF2a

A total dosage up to 1 mg PGF_2a as i.v. infusions of 10–40 μg/min. was investigated on patients with arrhythmias of several kinds. We found therapeutic effects in 5 of 6 patients with constant extrasystoles and in one patient with digitalis - induced partial AV-block respectively. In 3 of 4 patients with acute tachyarrhythmias the results were not convincing, probably due to a dosage not high enough. An increase of the diastolic stimulation threshold usually seen with other antiarrhythmics was not to be observed in 3 patients. The mechanism of action of PGF_2a has not yet been clarified.