Kinases and protein motifs required for AZI1 plastid localization and trafficking during plant defense induction

The proper subcellular localization of defense factors is an important part of the plant immune system. A key component for systemic resistance, lipid transfer protein (LTP)-like AZI1, is needed for the systemic movement of the priming signal azelaic acid (AZA) and a pool of AZI1 exists at the site of AZA production, the plastid envelope. Moreover, after systemic defense-triggering infections, the proportion of AZI1 localized to plastids increases. However, AZI1 does not possess a classical plastid transit peptide that can explain its localization. Instead, AZI1 uses a bipartite N-terminal signature that allows for its plastid targeting. Furthermore, the kinases MPK3 and MPK6, associated with systemic immunity, promote the accumulation of AZI1 at plastids during priming induction. Our results indicate the existence of a mode of plastid targeting possibly related to defense responses.     

Body shape variation in the Characid Psalidodon rivularis from São Francisco river,Southeast Brazil (Characiformes: Stethaprioninae)

Psalidodon rivularis is a species of tetra endemic to the São Francisco River basin and, based on cytogenetic and molecular studies, represents a complex of species. The objective of the present work was to identify morphological differences in the body shape of seven populations of P. rivularis from the Upper and Middle São Francisco River basin through geometric morphometry. In all, we photographed 174 individuals on the right side of the body and 17 landmarks were digitized on each image. To study the effects of allometry on the shape, we performed regression analysis and, to study shape modulation at different collection points and sub-basins, the canonical variation analyses. We found differences in shape between collection points and sub-basins associated with relative body height and sub-orbital plate recoil, in addition to a significant influence of size on specimen shape (allometry) associated with the ventral skull, orbits and sub-orbital plate. We do not envision differences in body shape between males and females. Several works with fish relate body height with water velocity, while the sub-orbital plate recoil shows a taxonomic or ecological potential, marking the main difference between the populations of the Upper and Middle São Francisco River.     

A new species of <Emphasis Type="Italic">Chamaecrista</Emphasis> sect. <Emphasis Type="Italic">Chamaecrista</Emphasis> ser. <Emphasis Type="Italic">Flexuosae</Emphasis> (Leguminosae,Caesalpinioideae) from Serra do Cipó, Minas Gerais,Brazil

A new species, Chamaecrista truncata, from southeastern Brazil, is described, illustrated and compared to its putative closest relative, C. parvistipula. The new species belongs to Chamaecrista sect. Chamaecrista ser. Flexuosae which is characterized by asymmetrical leaflets with palmate venation, quadrangular stems and axillary peduncles. Additionally, the venation pattern of the leaflets and the different types of stipules observed within this series are shown.     

Dynamic modeling of syngas fermentation in a continuous stirred-tank reactor: Multi-response parameter estimation and process optimization

Syngas fermentation is one of the bets for the future sustainable biobased economies due to its potential as an intermediate step in the conversion of waste carbon to ethanol fuel and other chemicals. Integrated with gasification and suitable downstream processing, it may constitute an efficient and competitive route for the valorization of various waste materials, especially if systems engineering principles are employed targeting process optimization. In this study, a dynamic multi-response model is presented for syngas fermentation with acetogenic bacteria in a continuous stirred-tank reactor, accounting for gas–liquid mass transfer, substrate (CO, H₂) uptake, biomass growth and death, acetic acid reassimilation, and product selectivity. The unknown parameters were estimated from literature data using the maximum likelihood principle with a multi-response nonlinear modeling framework and metaheuristic optimization, and model adequacy was verified with statistical analysis via generation of confidence intervals as well as parameter significance tests. The model was then used to study the effects of process conditions (gas composition, dilution rate, gas flow rates, and cell recycle) as well as the sensitivity of kinetic parameters, and multiobjective genetic algorithm was used to maximize ethanol productivity and CO conversion. It was observed that these two objectives were clearly conflicting when CO-rich gas was used, but increasing the content of H₂ favored higher productivities while maintaining 100% CO conversion. The maximum productivity predicted with full conversion was 2 g·L⁻¹·hr⁻¹ with a feed gas composition of 54% CO and 46% H₂ and a dilution rate of 0.06 hr⁻¹ with roughly 90% of cell recycle.     

Biochemical evidence for chemical and/or topographic differences in the lipoperoxidative processes induced by CCl4 and iron

Isolated rat hepatocytes, treated with CCl4 or ADP-Fe3+ complex show an enhanced lipid peroxidation and a decreased glucose 6-phosphatase activity. Lipid peroxidation is much more stimulated by ADP-Fe3+ or Fe3+ than by CCl4, when the metal and the haloalkane are used at a similar concentration. Increasing rates of lipid peroxidation in the different experimental conditions do not correlate with the degree of glucose 6-phosphatase inactivation, which is produced by CCl4 and not by a similar amount of ferric iron. In the case of iron, its intracellular concentration must be higher to give the enzyme inactivation exerted by CCl4. Higher intracellular levels of iron are reached when the metal is added to the cell suspension together with ADP. Under these conditions there is inactivation of glucose 6-phosphatase. Possible mechanisms accounting for a different enzyme sensitivity to iron and CCl4 are discussed.     

New active site oriented glyoxyl-agarose derivatives of <Emphasis Type="Italic">Escherichia coli</Emphasis>penicillin G acylase

Background  

Immobilized Penicillin G Acylase (PGA) derivatives are biocatalysts that are industrially used for the hydrolysis of Penicillin G by fermentation and for the kinetically controlled synthesis of semi-synthetic β-lactam antibiotics. One of the most used supports for immobilization is glyoxyl-activated agarose, which binds the protein by reacting through its superficial Lys residues. Since in E. coli PGA Lys are also present near the active site, an immobilization that occurs through these residues may negatively affect the performance of the biocatalyst due to the difficult diffusion of the substrate into the active site. A preferential orientation of the enzyme with the active site far from the support surface would be desirable to avoid this problem.