Stromal NADH supplied by PHOSPHOGLYCERATE DEHYDROGENASE3 is crucial for photosynthetic performance

During photosynthesis, electrons travel from light-excited chlorophyll molecules along the electron transport chain to the final electron acceptor nicotinamide adenine dinucleotide phosphate (NADP) to form NADPH, which fuels the Calvin–Benson–Bassham cycle (CBBC). To allow photosynthetic reactions to occur flawlessly, a constant resupply of the acceptor NADP is mandatory. Several known stromal mechanisms aid in balancing the redox poise, but none of them utilizes the structurally highly similar coenzyme NAD(H). Using Arabidopsis (Arabidopsis thaliana) as a C₃-model, we describe a pathway that employs the stromal enzyme PHOSPHOGLYCERATE DEHYDROGENASE 3 (PGDH3). We showed that PGDH3 exerts high NAD(H)-specificity and is active in photosynthesizing chloroplasts. PGDH3 withdrew its substrate 3-PGA directly from the CBBC. As a result, electrons become diverted from NADPH via the CBBC into the separate NADH redox pool. pgdh3 loss-of-function mutants revealed an overreduced NADP(H) redox pool but a more oxidized plastid NAD(H) pool compared to wild-type plants. As a result, photosystem I acceptor side limitation increased in pgdh3. Furthermore, pgdh3 plants displayed delayed CBBC activation, changes in nonphotochemical quenching, and altered proton motive force partitioning. Our fluctuating light-stress phenotyping data showed progressing photosystem II damage in pgdh3 mutants, emphasizing the significance of PGDH3 for plant performance under natural light environments. In summary, this study reveals an NAD(H)-specific mechanism in the stroma that aids in balancing the chloroplast redox poise. Consequently, the stromal NAD(H) pool may provide a promising target to manipulate plant photosynthesis.

PHOSPHOGLYCERATE DEHYDROGENASE 3, an oxidoreductase in leaf chloroplasts with strong preference to reduce the stromal NAD(H) instead of the NADP(H) pool, is required for full photosynthetic capacity.     

Economic evaluation of the development of a phage therapy product for the control of Salmonella in poultry

Poultry products are one of the major transmission media of Salmonella enteritidis to humans. A promising alternative to reduce the load of Salmonella in poultry are bacteriophages. Elsewhere, a mixture of six bacteriophages has been used successfully, but large-scale production would be necessary to supply potential poultry market and costs analyses have not been calculated yet. For this, a powerful tool to predict production costs is bioprocess modeling coupled with economic analyses. This work aims to model the scaled-up production of a six bacteriophages mixture based on a laboratory/pilot-scale production using Biosolve Process. For the model construction, a combination of experimental and reported data was applied, in which different production alternatives and the range of 1–100% of the Colombian poultry market (at broiler's farm and slaughterhouse) were analyzed. Results indicate that the best cost-effective process configuration/scale is to use one bioreactor (156 L) for the six bacteriophages, then a 0.45 μm filtration for removal of biomass, and a 0.22 μm filtration for sterility; this to supply the 35% of the market size for broiler farms (equivalent to 210 million chickens). This configuration gives a production cost per chicken of US$ 0.02. Additionally, a sensitivity analysis and a theoretical contrast for understanding the impact that titer and recovery have on production scale determined that titer affects the most the cost and requires optimization. The present works serves as a first, and required, approach for the development of phage therapy products that are alternatives to present-day pathogens control strategies.     

Legume–rhizobium dance: an agricultural tool that could be improved?

The specific interaction between rhizobia and legume roots leads to the development of a highly regulated process called nodulation, by which the atmospheric nitrogen is converted into an assimilable plant nutrient. This capacity is the basis for the use of bacterial inoculants for field crop cultivation. Legume plants have acquired tools that allow the entry of compatible bacteria. Likewise, plants can impose sanctions against the maintenance of nodules occupied by rhizobia with low nitrogen-fixing capacity. At the same time, bacteria must overcome different obstacles posed first by the environment and then by the legume. The present review describes the mechanisms involved in the regulation of the entire legume–rhizobium symbiotic process and the strategies and tools of bacteria for reaching the nitrogen-fixing state inside the nodule. Also, we revised different approaches to improve the nodulation process for a better crop yield.     

Microzooplankton and tintinnid species-specific assemblage structures: patterns of distribution and year-to-year variations in the Weddell Sea (Antarctica)

Silicoflagellates, large heterotrophic dinoflagellates, radiolarians,tintinnids and micro-crustaceans were counted in 72 screened(15 µm) samples retrieved at 0–150 m from the WeddellSea in January 1989. Tintinnid species were identified and biomassestimates were carried out for all groups on the basis of measurementsof cell dimensions. Dinoflagellates dominated the micro-heterotrophiccommunity at all stations and depths (65% of overall microzooplanktoniccarbon in the 0–150 m interval), followed by the tintinnids(18%), microcrustaceans (16%) and radiolarians (1%). All groups,with the exception of silicoflagellates, peaked noticeably inthe vicinity of the southern end of the transect (76–77°S).Relationships between concentrations of chlorophyll a and microzooplanktonicbiomass were present, yet not altogether consistent, but bothphyto- and microzooplankton seemed to generally respond to regionalenhancements associated with the ice edge. Comparison with similarWeddell and Weddell-Scotia data retrieved in February-March1987 and November 1988-December 1989, respectively, are highlycoherent in terms of microplanktonic abundances, their geographicand vertical distribution patterns, and the specific make-upand distribution of tintinnid assemblages. Analyses of the oraldiameters of tintinnid morphotypes suggest that the latitudinaland vertical distribution of their five dominant taxa (whichaccount for >90% of all individuals) is structured so asto maximize resource partitioning.     

Ultrastructural and biological characterization of human choroid cell cultures transformed by Simian Virus 40

Summary A human diploid cell line of choroid origin was isolated from the retrouveal portion of an enucleated eye and designated HC. After 10 passages, when the proliferative capacity of HC cells decreased, they were infected and transformed by Simian Virus 40 (SV40). A proliferating long-term cultured cell line designated HC/SV40 was established and it has been maintained as monolayer for more than 100 passages so far. The two cell lines, HC and HC/SV40, were compared for growth characteristics, capacity to form colonies in soft agar, presence of nuclear T-antigen, and ultrastructure. Cytogenetic analysis was also performed to determine the presence of chromosomal aberrations due to the permanent viral transformation of the cell line. The results indicate that HC/SV40 should be considered the transformed counterparts of HC cells because they are morphologically similar to the latter but can grow in soft agar, possess T-antigen, and show a pattern of karyotypic changes similar to that induced by SV40 in human fibroblasts. The choroid origin of HC and HC/SV40 cell lines was confirmed by the presence, in their cytoplasm, of typical electron dense granules. Their neural origin will make these cell lines very useful for neuropharmacological and differentiation studies. This work was supported by Grant 82.00346.96 from the C.N.R. finalized project “Control of Neoplastic Growth”.     

Foliar application of wood distillate boosts plant yield and nutritional parameters of chickpea

In the quest for eco-friendly products with biostimulant properties, foliar application of wood distillate (WD) was tested on the growth and yield of chickpea (Cicer arietinum L.). WD (pyroligneous acid) is a by-product of plant biomass pyrolysis and is rich in biologically active substances like polyphenols, alcohols, acids and esters. In this work, chickpea plants were sprayed weekly with 100 ml 0.25% (v/v) chestnut (Castanea sativa Mill.) WD during the whole growing period, and at the end physiological and nutritional analyses were performed both on the whole plant and on seeds. While plant height and weight did not change significantly, seeds showed an increase in diameter (+11.2%) and weight (+33.3%), and in the content of starch (+45.9%), total soluble protein (+12.9%), total polyphenol (+16.4%) and antioxidant power (+28.4%). Overall, the content of essential free amino acids increased, except for lysine (−3.4%), phenylalanine (−10.5%) and methionine (−13.7%). Among all the mineral elements analysed, only potassium and magnesium decreased in WD-treated plants, although values were within the common range for chickpea seeds. These results are a clear demonstration of the effectiveness of the use of WD on increasing the nutritional qualities of the edible parts of crop species, thus representing a possible solution to counteract human malnutrition and famine as well as environmental concerns.