Unsuitability of Cnesterodon decemmaculatus (Jenyns, 1842) for mosquito control in Uruguay: evidence from food‐preference experiments

We analyzed the feeding preference of Cnesterodon decemmaculatus, a small‐bodied poecilid native from the Rio de la Plata and proximate Atlantic Basins in South America. This species has a wide distribution in Uruguayan water bodies but its effectiveness as a predator of mosquito larvae has not been tested. In laboratory trials, five aquatic invertebrates were offered simultaneously as potential prey to fish: Daphnia pulex (Cladocera), copepods, two different instars of mosquito larvae (Culex pipiens), and the 4^th instar of Chironomidae larvae. Preference was measured by the Chesson's electivity index (α). In order to determine differences in prey preference according to fish size, individuals ranging from 9.5 mm to 35.3 mm were classified in three different body size classes: small, medium, and large. Small fish showed preference for copepods, while medium‐sized fish preferred the smallest mosquito larvae instars and Chironomidae larvae. We conclude that C. decemmaculatus is a zooplankton facultative‐feeder fish that prefers large‐bodied zooplankton but is a weak predator of mosquito larvae. Thus, the introduction of C. decemmaculatus as a biological‐control agent in natural environments is not an effective strategy.     

Direct antioxidant and protective effect of estradiol on isolated mitochondria

Estrogens have antioxidant properties which are due to their ability to bind to estrogen receptors and to up-regulate the expression of antioxidant enzymes via intracellular signalling pathways. Mitochondria are key organelles in the development of age-associated cellular damage. Recently, estrogen receptors were identified in mitochondria. The aim of this paper was to test whether estradiol directly affects mitochondria by preventing oxidative stress and protecting frail mitochondria. Incubation with estradiol at normal intracellular concentrations prevents the formation of reactive oxygen species by mitochondria in a saturable manner. Moreover, estradiol protects mitochondrial integrity as indicated by an increase in mitochondrial membrane potential. It also prevents the apoptogenic leakage of cytochrome c from mitochondria and as a result the mitochondrial content of this cytochrome c is maintained high. Thus, estradiol prevents the onset of the mitochondrial pathway of apoptosis by a direct effect on the organelle. Genistein, a phytoestrogen present at high concentration in soy, mimics the protective effect of estradiol by both decreasing the rate of formation of reactive oxygen species and preventing the release of cytochrome c from mitochondria.     

Advances in molecular tools for the use of Zygosaccharomyces bailii as host for biotechnological productions and construction of the first auxotrophic mutant

The nonconventional yeast Zygosaccharomyces bailii has been proposed as a new host for biotechnological processes due to convenient properties such as its resistance to high sugar concentrations, relatively high temperatures and especially to acidic environments. We describe a series of new expression vectors specific for Z. bailii and the resulting improvements in production levels. By exploiting the sequences of the endogenous plasmid pSB2, 2microm-like multicopy vectors were obtained, giving a fivefold increase in production. A specific integrative vector was developed which led to 100% stability in the absence of selective pressure; a multiple-integration vector was constructed, based on an rRNA gene unit portion cloned and sequenced for this purpose, driving the insertion of up to 80 copies of the foreign construct. Moreover, we show the construction of the first stable auxotrophic mutant of Z. bailii, obtained by targeted gene deletion applied to ZbLEU2. The development of molecular tools for the Z. bailii manipulation has now reached a level that may be compatible with its industrial exploitation; the production of organic acids is a prominent field of application.     

New enantiornithine bird (Aves, Ornithothoraces) from the Late Cretaceous of NW Argentina

A new enantiornithine bird, Intiornis inexpectatus gen. et sp. nov, is described here. It is based on a partial hind limb found in beds of the Upper Cretaceous Las Curtiembres Formation (Campanian), North-West Argentina. The new taxon is referred to the family Avisauridae on the basis of its cranially convex third metatarsal. Several features suggest close relationships between Intiornis and the avisaurid Soroavisaurus, from the Lecho Formation (Maastrichtian; North-West Argentina). Intiornis was the size of a sparrow, thus representing the smallest Enantiornithes known from South America. The new species shows adaptations for a perching mode of life. Moreover, the hypothesis suggesting that the flying pterosaur reptiles decrease in taxonomic diversity due to competitive interaction with birds is discussed. The new species shows adaptations for a perching mode of life. Moreover, the hypothesis suggesting that the flying pterosaur reptiles decrease in taxonomic diversity due to competitive interaction with birds is discussed.     

Higher accumulation of F1-V fusion recombinant protein in plants after induction of protein body formation

Improving foreign protein accumulation is crucial for enhancing the commercial success of plant-based production systems since product yields have a major influence on process economics. Cereal grain evolved to store large amounts of proteins in tightly organized aggregates. In maize, γ-Zein is the major storage protein synthesized by the rough endoplasmic reticulum (ER) and stored in specialized organelles called protein bodies (PB). Zera^® (γ-Zein ER-accumulating domain) is the N-terminal proline-rich domain of γ-zein that is sufficient to induce the assembly of PB formation. Fusion of the Zera^® domain to proteins of interest results in assembly of dense PB-like, ER-derived organelles, containing high concentration of recombinant protein. Our main goal was to increase recombinant protein accumulation in plants in order to enhance the efficiency of orally-delivered plant-made vaccines. It is well known that oral vaccination requires substantially higher doses than parental formulations. As a part of a project to develop a plant-made plague vaccine, we expressed our model antigen, the Yersinia pestis F1-V antigen fusion protein, with and without a fused Zera^® domain. We demonstrated that Zera^®-F1-V protein accumulation was at least 3× higher than F1-V alone when expressed in three different host plant systems: Ncotiana benthamiana, Medicago sativa (alfalfa) and Nicotiana tabacum NT1 cells. We confirmed the feasibility of using Zera^® technology to induce protein body formation in non-seed tissues. Zera^® expression and accumulation did not affect plant development and growth. These results confirmed the potential exploitation of Zera^® technology to substantially increase the accumulation of value-added proteins in plants.