Crescendo, diminuendo and subito of the trumpets: winds of change in the concerted evolution between flowers and pollinators in Salpichroa (Solanaceae).

'Gradual' vs 'punctuated' and 'unidirectional' (only lengthening) vs. 'bidirectional'(lengthenings and shortenings) modes of evolution are explanations that compete to explain adaptive changes of flower tube length in angiosperm. The nightshade genus Salpichroa Miers, with 21 species mostly growing in the tropical Andes of southern South America, has the opportune qualities of including nearly 15-fold inter-specific variation in corolla tube length, as well as one species that is a candidate for participating in evolutionary escalation with the longest-billed hummingbird, Ensifera ensifera. We reconstructed the phylogenetic relationships using five molecular markers, the two plastid markers trnD-trnT and trnL, and three nuclear markers, ITS and two COSII, and estimated divergence times of the genus in order to reconstruct the history of both corolla tube length and pollination mode (i.e. hummingbirds, moths or multiple). We used comparative methods to determine whether corolla tube elongation/shortening is associated with shifts in pollination mode and to test, modes and rates of corolla tube change. We found evidence of both lengthening and shortening of corolla tubes. Evolutionary rates are consistent with rapid corolla tube length transitions that are only partly associated with shifts in pollination mode. Though 'punctuated' evolution (i.e. large changes predominantly at speciation events) explained corolla changes in the whole genus, 'gradual' evolution (i.e. gradual changes during a coevolutionary race with the same pollinator) was a better explanation for the change in the long-flowered clade, mostly pollinated by hummingbirds.

Flower morphology evolution in Jaborosa (Solanaceae): shape and size variation associated with contrasting pollination modes.

Flower morphology is considered an important factor in species diversification because it may influence the efficiency of pollination in different ways (e.g. attraction and mechanical fit with different groups of pollinators). In the present study, we quantified the variation in flower morphology (i.e. shape and size) of the diverse South American genus Jaborosa Juss. (Solanaceae) in relation to contrasting pollination modes: rewarding pollination either by moths or by generalist small insects versus brood-site deceptive pollination by saprophilous flies. We examined variations of flower morphology in frontal (pollinator attraction) and sagittal (functional fit with pollinators) views in 12 Jaborosa species using geometric morphometric methods and comparative approaches to infer whether flower shape evolution, not attributable to flower allometry or phylogenetic relationship, is associated with shifts in pollination modes. We found remarkable variation in flower morphology among both Jaborosa species and pollination modes, largely in sagittal view. Evolutionary trends in shape of fly-pollinated flowers were mainly attributable to changes in developmental trajectories. Variation in flower architecture facilitated differential pollen placement - on the proboscis of moths, and either on the back or ventral region of saprophilous flies - promoting diversification of the genus. Diversification of shape, independent of size, in most of the studied Jaborosa species would indicate adaptation to contrasting pollination modes.

An ultrastructural study of the subependymal plate in the hamster.

The subependymal plate of the hypothalamus of the hamster has been studied in this work. Our observations with the electron microscope show that the basal surface of the ependymal cells in this area are situated directly over the astrocytic elements. Ultrastructural studies which indicate two types of glial cells in the subependymal plate contradicted by the results of the present investigation demonstrating one type of glial cells in the hypothalamic subependymal plate. This fact is interpreted as the final result of a glial differentiation in adult hamsters.

The fine structure of ependyma in the hypothalamus of the hamster (Cricetus cricetus).

The ciliated ependyma of the hypothalamus of the hanster (Cricetus cricetus) consists of a sheet of cells, the luminal surface of which is reflected over cilia and numerous microvilli. The lateral portions of the plasmalemma of contiguous cells are fused at some sites to from junctions of five layers, the zonula occludens. These fusions occur usually in continuity with other intercellular junctions, the zonula adhaerens. In the apical regions of the ependyma these fusions are almost spiralled. The nucleus is regularly oval and lying close to the basal plasmalemma. The cytoplasm contains a finely granular matrix, filamentous components close to the junctions. The endoplasmic reticulum is sparse. The Golgicomplex is confined to the supranuclear cytoplasm, and mitochondria, are more numerous in the apical than in the basal regions of ependymal cells; the mitochondria are generally rounded and have transverse cristae and granules. The apical regions of the cytoplasm contain the basal bodies of cilia; they form non-striated rootlets and the rootlet filaments tend to diverge, ending in a granular zone.