Hemagglutination Inhibition of Passively Sensitized Red Blood Cells

It has been shown that sheep red blood cells sensitized with the polysaccharides of Haemophilus influenzae type B and pneumococcal types I, III, IV, VII, VIII, XII, and XIV respond readily in hemagglutination-inhibition testing and exhibit antigen inhibition at levels of 0.09 to 4.0 ng.     

Systematic implications of sesquiterpene lactones in the subtribe melampodiinae

Within the tribe Heliantheae of the Asteraceae, the genetic boundaries of the subtribe Melampodinae have recently been drastically revised by Stuessy. The number of genera within the subtribe has been reduced and new generic groupings have been established. The present study correlates the distribution of sesquiterpene lactones found in these genera with the newly revised subtribal boundaries. The genera Acanthospermum, Melampodium, Polymnia and Sigesbeckia produce predominantly melampolide-type sequiterpene lactones. Limited chemical data support Stuessy's removal of the genera Desmanthodium, Clibadium and Ichthyothere from the subtribe Melampodiinae. The occurrence of melampolide-type sesquiterpene lactones in members of the genera Tetragonotheca (Helianthinae) and Enhydra (Ecliptinae) indicate a possible position of these genera in the Melampodiinae.     

In vivo fate analysis reveals the multipotent and self-renewal capacities of Sox2+ neural stem cells in the adult hippocampus

To characterize the properties of adult neural stem cells (NSCs), we generated and analyzed Sox2-GFP transgenic mice. Sox2-GFP cells in the subgranular zone (SGZ) express markers specific for progenitors, but they represent two morphologically distinct populations that differ in proliferation levels. Lentivirus- and retrovirus-mediated fate-tracing studies showed that Sox2+ cells in the SGZ have potential to give rise to neurons and astrocytes, revealing their multipotency at the population as well as at a single-cell level. A subpopulation of Sox2+ cells gives rise to cells that retain Sox2, highlighting Sox2+ cells as a primary source for adult NSCs. In response to mitotic signals, increased proliferation of Sox2+ cells is coupled with the generation of Sox2+ NSCs as well as neuronal precursors. An asymmetric contribution of Sox2+ NSCs may play an important role in maintaining the constant size of the NSC pool and producing newly born neurons during adult neurogenesis.     

The anatomy, physics, and physiology of gas exchange surfaces: is there a universal function for pulmonary surfactant in animal respiratory structures?

(Orgeig and Daniels) This surfactant symposium reflects theintegrative and multidisciplinary aims of the 1st ICRB, by encompassingin vitro and in vivo research, studies of vertebrates and invertebrates,and research across multiple disciplines. We explore the physicaland structural challenges that face gas exchange surfaces invertebrates and insects, by focusing on the role of the surfactantsystem. Pulmonary surfactant is a complex mixture of lipidsand proteins that lines the air–liquid interface of thelungs of all air-breathing vertebrates, where it functions tovary surface tension with changing lung volume. We begin witha discussion of the extraordinary conservation of the blood–gasbarrier among vertebrate respiratory organs, which has evolvedto be extremely thin, thereby maximizing gas exchange, but simultaneouslystrong enough to withstand significant distension forces. Theprincipal components of pulmonary surfactant are highly conserved,with a mixed phospholipid and neutral lipid interfacial filmthat is established, maintained and dynamically regulated bysurfactant proteins (SP). A wide variation in the concentrationsof individual components exists, however, and highlights lipidomicas well as proteomic adaptations to different physiologicalneeds. As SP-B deficiency in mammals is lethal, oxidative stressto SP-B is detrimental to the biophysical function of pulmonarysurfactant and SP-B is evolutionarily conserved across the vertebrates.It is likely that SP-B was essential for the evolutionary originof pulmonary surfactant. We discuss three specific issues ofthe surfactant system to illustrate the diversity of functionin animal respiratory structures. (1) Temperature: In vitroanalyses of the behavior of different model surfactant filmsunder dynamic conditions of surface tension and temperaturesuggest that, contrary to previous beliefs, the alveolar filmmay not have to be substantially enriched in the disaturatedphospholipid, dipalmitoylphosphatidylcholine (DPPC), but thatsimilar properties of rate of film formation can be achievedwith more fluid films. Using an in vivo model of temperaturechange, a mammal that enters torpor, we show that film structureand function varies between surfactants isolated from torpidand active animals. (2) Spheres versus tubes: Surfactant isessential for lung stabilization in vertebrates, but its functionis not restricted to the spherical alveolus. Instead, surfactantis also important in narrow tubular respiratory structures suchas the terminal airways of mammals and the air capillaries ofbirds. (3). Insect tracheoles: We investigate the structureand function of the insect tracheal system and ask whether pulmonarysurfactant also has a role in stabilizing these minute tubules.Our theoretical analysis suggests that a surfactant system maybe required, in order to cope with surface tension during processes,such as molting, when the tracheae collapse and fill with water.Hence, despite observations by Wigglesworth in the 1930s offluid-filled tracheoles, the challenge persists into the 21stcentury to determine whether this fluid is associated with apulmonary-type surfactant system. Finally, we summarize thecurrent status of the field and provide ideas for future research.