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Flowering time determines potential plant mates, and it is related to gene flow within and among plant populations arising from different selective forces and interspecific interactions between plants with similar pollination niches. However, these effects on the flowering phenology of plants with generalist pollination systems have received little attention and hence our knowledge of the contribution of generalised pollination systems on the evolution of adaptative traits, such as the flowering time containing lacunae. To verify the effective contribution of interspecific plant interactions in a generalised pollination system to the structuring of flowering phenology. We recorded the reproductive phenophases of four Baccharis species in a subtropical grassland. We evaluated their flowering patterns by a niche overlap index and compared it with a null model. We used ecological network metrics from insect visitors recorded to determine the pollinator network structure. A staggered flowering pattern and distinctiveness of insect pollinators with non-signalling modularity and a variation in the Baccharis-pollinators network structure throughout the year were observed. The distinctiveness on pollinators with a strong bee-dependence added to temporal divergence on flowering among the species leads to no negative effects on fruit set. The temporal segregation on flowering peaks and low pollinator similarity appear to underlie to coexistence of Baccharis species studied in southern Brazil. [ABSTRACT FROM AUTHOR]

Abstract Purpose. To evaluate the intraocular distribution and metabolism of the lipid prodrug of foscarnet, 1-O-octadecyl-sn-glycerol-3-phosphonoformate (ODG-PFA), following intravitreal administration. Methods. Twenty rabbits received ODG-[[sup 14]C]PFA intravitreal injection, yielding 0.632 mM resultant intravitreal concentration. Two animals per group were sacrificed at different intervals post-injection. The drug levels in ocular tissues were determined with counting the radioactivity by Tracor Mark III Liquid Scintillation Counter. Four rabbits were used for analysis of the drug metabolism in vitreous by lipid extraction technique. Results. The drug level in vitreous was 526 micro M at day one and 227 micro M at the fifth week. The vitreous half life was approximately four to five weeks. The retinal level of the drug was 292 micro M at day one, 75 micro M at the fifth week and 32 micro M at the tenth week, which was still more than ten times higher than the IC[sub 90] against HCMV. Lipid extraction analysis showed that, in vivo, both ODG-PFA and PFA were present in vitreous, but in in vitro incubations with vitreous, ODG-PFA conversion to PFA was negligible. Conclusion. ODG-PFA possesses a long vitreous half life and sustained high drug level in retina. The vitreous did not metabolize drug but acted as a drug reservoir. Intravitreal liposomal ODG-PFA may be expected to be a long acting potent local therapy for CMV retinitis. [ABSTRACT FROM AUTHOR]