Expression of Shigella sonnei lipopolysaccharide in Vibrio cholerae

Making use of a newly designed mobilizable suicide vector, the genetic determinants encoding Shigella sonnei lipopolysaccharide (LPS) were stably integrated into the chromosome of the live attenuated Vibrio cholerae vaccine strain CVD103-HgR. Expression studies showed that the production of complete S. sonnei O-polysaccharide (O-PS)-bearing LPS was limited in bivalent recombinant strains that were also proficient in the synthesis of the host-encoded Inaba O-PS. Conversely, high amounts of LPS carrying S. sonnei O-PS are produced in monovalent Inaba-deficient derivatives, even in those strains which do not co-express the compatible R1 LPS core. Thus, the non-enterobacterial V. cholerae LPS core efficiently acts as a receptor for covalent binding of S. sonnei O-PS provided that competition with the host O-PS is avoided. Expression of the R1 core interferes with cell division in recombinant V. cholerae without affecting other physiological properties of vaccine strain CVD103-HgR. Both monovalent and bivalent strains stimulated high serum-antibody titres specific for their respective O-serotype(s) when administered to rabbits. The potential of V. cholerae as an expression carrier for heterologous O-serotypes is discussed.     

Turnover of plant lineages shapes herbivore phylogenetic beta diversity along ecological gradients

Understanding drivers of biodiversity patterns is of prime importance in this era of severe environmental crisis. More diverse plant communities have been postulated to represent a larger functional trait‐space, more likely to sustain a diverse assembly of herbivore species. Here, we expand this hypothesis to integrate environmental, functional and phylogenetic variation of plant communities as factors explaining the diversity of lepidopteran assemblages along elevation gradients in the Swiss Western Alps. According to expectations, we found that the association between butterflies and their host plants is highly phylogenetically structured. Multiple regression analyses showed the combined effect of climate, functional traits and phylogenetic diversity in structuring butterfly communities. Furthermore, we provide the first evidence that plant phylogenetic beta diversity is the major driver explaining butterfly phylogenetic beta diversity. Along ecological gradients, the bottom up control of herbivore diversity is thus driven by phylogenetically structured turnover of plant traits as well as environmental variables.     

Where ichthyofaunal provinces meet: the fish fauna of the Lake Edward system,East Africa

Based on literature, museum collections and three recent expeditions, an annotated species list of the Lake Edward, East Africa, drainage system is presented, excluding the endemic haplochromines. A total of 34 non-Haplochromis species belonging to 10 families and 21 genera are recorded from the system. Three of these are endemic and two others have been introduced in the region. Six species are new records for the Lake Edward system. A species accumulation curve indicates that we probably covered most of the non-Haplochromis species in the area sampled during the recent expeditions, but undetected species might still be present in the Congolese part of the system, which is poorly sampled. A comparison of the species list with those of neighbouring basins confirmed the placement of the Lake Edward system within the east-coast ichthyofaunal province.     

Multiple molecular forms of rat superior cervical ganglion acetylcholinesterase: Developmental aspects in primary cell culture and during postnatal maturation in vivo

Four main molecular forms of acetylcholinesterase (AChE) can be solubilized from newborn rat superior cervical ganglia (SCG), homogenized in the presence of a high-ionic-strength, detergent-containing medium. These forms, respectively referred to as 16, 10, 6.5, and 4 S, are characterized by their sedimentation coefficients. Their relative proportions in SCG are notably different in vivo during postnatal maturation, and in culture. The 16-S AChE appears to be mainly neuronal in origin, is maintained in culture independently of original presynaptic in vivo elements, and its cellular pool is not depleted in the presence of tetrodotoxin (TTX).