The bidirectional polar and unidirectional lateral flagellar motors of Vibrio alginolyticus are controlled by a single CheY species

The bacterial flagellar motor is an elaborate molecular machine that converts ion-motive force into mechanical force (rotation). One of its remarkable features is its swift switching of the rotational direction or speed upon binding of the response regulator phospho-CheY, which causes the changes in swimming that achieve chemotaxis. Vibrio alginolyticus has dual flagellar systems: the Na(+)-driven polar flagellum (Pof) and the H(+)-driven lateral flagella (Laf), which are used for swimming in liquid and swarming over surfaces respectively. Here we show that both swimming and surface-swarming of V. alginolyticus involve chemotaxis and are regulated by a single CheY species. Some of the substitutions of CheY residues conserved in various bacteria have different effects on the Pof and Laf motors, implying that CheY interacts with the two motors differently. Furthermore, analyses of tethered cells revealed that their switching modes are different: the Laf motor rotates exclusively counterclockwise and is slowed down by CheY, whereas the Pof motor turns both counterclockwise and clockwise, and CheY controls its rotational direction.     

A phylogeographical perspective on the ex situ conservation of Aylacostoma (Thiaridae,Gastropoda) from the High Paraná River (Argentina–Paraguay)

Aylacostoma Spix, 1827, contains species that are the subject of focused conservation efforts under the auspices of the ‘Aylacostoma Project’, the only ex situ conservation programme for freshwater gastropods in South America. Two species from the High Paraná River (Argentina–Paraguay) are included in this programme (Aylacostoma chloroticum Hylton Scott, 1954 and Aylacostoma brunneum Vogler & Peso, 2014), as their habitats have disappeared as a consequence of the filling of the Yacyretá Reservoir in the 1990s. At present, A. chloroticum is restricted to only one known wild population in a small and fragile habitat, and wild populations of A. brunneum are presumed to have gone extinct. We used partial sequences of the cytochrome oxidase subunit I gene to provide the first phylogeographical perspective on these species from a limited dataset containing representatives of several wild populations that are successfully being bred in captivity. We found low genetic diversity and two haplotypes in A. chloroticum, and absence of variation with one haplotype in A. brunneum. The reservoir's entry zone was identified to be of great interest for conservation, and is where we suggest re‐introductions and translocations should be targeted, to preserve the future evolutionary potential of the extant diversity. © 2015 The Linnean Society of London     

The sustainability of communicative packaging concepts in the food supply chain. A case study: part 2. Life cycle costing and sustainability assessment

Purpose  

This paper is the second part of a two-paper series dealing with the sustainability evaluation of a new communicative packaging concept. The communicative packaging concept includes a device that allows changing the expiry date of the product as function of temperature during transport and storage: a flexible best-before-date (FBBD). Such device was analysed in a consumer unit consisting of a nanoclay-based polylactic acid tray filled with pork chops.     

Unusual viral ligand with alternative interactions is presented by HLA-Cw4 in human respiratory syncytial virus-infected cells

Short viral antigens bound to human major histocompatibility complex (HLA) class I molecules are presented on infected cells. Vaccine development frequently relies on synthetic peptides to identify optimal HLA class I ligands. However, when natural peptides are analyzed, more complex mixtures are found. By immunoproteomics analysis, we identify in this study a physiologically processed HLA ligand derived from the human respiratory syncytial virus matrix protein that is very different from what was expected from studies with synthetic peptides. This natural HLA-Cw4 class I ligand uses alternative interactions to the anchor motifs previously described for its presenting HLA-Cw4 class I molecule. Finally, this octameric peptide shares its C-terminal core with the H-2D(b) nonamer ligand previously identified in the mouse model. These data have implications for the identification of antiviral cytotoxic T lymphocyte responses and for vaccine development.     

Synthesis, structure, theoretical and experimental in vitro antioxidant/pharmacological properties of α-aryl, N-alkyl nitrones, as potential agents for the treatment of cerebral ischemia

The synthesis, structure, theoretical and experimental in vitro antioxidant properties using the DPPH, ORAC, and benzoic acid, as well as preliminary in vitro pharmacological activities of (Z)-??-aryl and heteroaryl N-alkyl-nitrones 6-15, 18, 19, 21, and 23, is reported. In the in vitro antioxidant activity, for the DPPH radical test, only nitrones bearing free phenol groups gave the best RSA (%) values, nitrones 13 and 14 showing the highest values in this assay. In the ORAC analysis, the most potent radical scavenger was nitrone indole 21, followed by the N-benzyl benzene-type nitrones 10 and 15. Interestingly enough, the archetypal nitrone 7 (PBN) gave a low RSA value (1.4%) in the DPPH test, or was inactive in the ORAC assay. Concerning the ability to scavenge the hydroxyl radical, all the nitrones studied proved active in this experiment, showing high values in the 94-97% range, the most potent being nitrone 14. The theoretical calculations for the prediction of the antioxidant power, and the potential of ionization confirm that nitrones 9 and 10 are among the best compounds in electron transfer processes, a result that is also in good agreement with the experimental values in the DPPH assay. The calculated energy values for the reaction of ROS (hydroxyl, peroxyl) with the nitrones predict that the most favourable adduct-spin will take place between nitrones 9, 10, and 21, a fact that would be in agreement with their experimentally observed scavenger ability. The in vitro pharmacological analysis showed that the neuroprotective profile of the target molecules was in general low, with values ranging from 0% to 18.7%, in human neuroblastoma cells stressed with a mixture of rotenone/oligomycin-A, being nitrones 18, and 6-8 the most potent, as they show values in the range 24-18.4%.     

Testing the suitability of insect orders as indicators for olive farming systems

• 1 A previous study suggested the use of certain insects groups as indicators for detecting organic olive farming in Southern Spain. To validate the use of these groups, insects were collected from olive orchards in Cordoba and Granada, comprising two Andalusian provinces with different surrounding landscapes.
• 2 Canopies were sampled using the branch‐beating technique during pre‐blooming and post‐blooming periods over 3 years in Granada (1999, 2000 and 2003) and 1 year in Cordoba (2003).
• 3 Using a nonparametric linear discriminant analysis method, based on the k‐nearest neighbour algorithm, two discriminant functions were constructed. A first discriminant model took into account interannual variability in Granada Province and the second model focused on environmental heterogeneity between the two provinces. Cross‐validation techniques, such as leave‐one‐out and split‐sample, were applied to the associated discriminant functions for each model to check their performance.
• 4 Even though differences existed with respect to the insect composition of the regions, the second model correctly classified 78.1% of the sampled blocks under the non‐organic and organic farming systems at the same time as taking into account two orders: Coleoptera and Hemiptera [excluding Euphyllura olivina olivina (Psyllidae) and the Heteroptera suborder]. The results suggest that the relative abundance of these groups in the post‐blooming period could constitute a potential bio‐indicator of organic olive farming system.