The fermentation of sugarcane molasses by Dekkera bruxellensis and the mobilization of reserve carbohydrates

The yeast Dekkera bruxellensis is considered to be very well adapted to industrial environments, in Brazil, USA, Canada and European Countries, when different substrates are used in alcoholic fermentations. Our previous study described its fermentative profile with a sugarcane juice substrate. In this study, we have extended its physiological evaluation to fermentation situations by using sugarcane molasses as a substrate to replicate industrial working conditions. The results have confirmed the previous reports of the low capacity of D. bruxellensis cells to assimilate sucrose, which seems to be the main factor that can cause a bottleneck in its use as fermentative yeast. Furthermore, the cells of D. bruxellensis showed a tendency to deviate most of sugar available for biomass and organic acids (lactic and acetic) compared with Saccharomyces cerevisiae, when calculated on the basis of their respective yields. As well as this, the acetate production from molasses medium by both yeasts was in marked contrast with the previous data on sugarcane juice. Glycerol and ethanol production by D. bruxellensis cells achieved levels of 33 and 53 % of the S. cerevisiae, respectively. However, the ethanol yield was similar for both yeasts. It is worth noting that this yeast did not accumulate trehalose when the intracellular glycogen content was 30 % lower than in S. cerevisiae. The lack of trehalose did not affect yeast viability under fermentation conditions. Thus, the adaptive success of D. bruxellensis under industrial fermentation conditions seems to be unrelated to the production of these reserve carbohydrates.     

From the saltpan to the plate: An evaluation of the use of the edible halophyte Salicornia ramosissima in catering

The halophyte species Salicornia ramosissima has long been consumed as food and is currently regarded as a high-value gourmet item. However, given that these plants grow in estuarine areas, often impacted by pollution, and are prone to the accumulation of ions, the risks associated with food borne pathogens or toxic metals has to be carefully considered. The objective of this work was to gather evidence that S. ramossissima harvested locally in an estuarine system (Ria de Aveiro, Portugal) can be safely consumed as a healthy and catering-amenable food. Fresh shoots, taken as green vegetables, and dried powdered shoots (green salt) intended as seasoning, were analysed for total aerobic bacteria, total coliforms, Escherichia coli, Bacillus cereus and fungi (yeasts and moulds). The nutritional profile and the concentration of macro and micro elements, including potential toxic elements, was also established. Fresh shoots and green salt were incorporated in catering meals (soup and a meat dish) and subjected to sensory analyses. The microbiological quality of fresh shoots and green salt was compliant with the guidelines for salad greens and herbs and spices, respectively. The nutritional and elemental profile revealed that fresh shoots have a high content in fibre and NaCl. From the concentration of Na determined in green salt, a daily dose of 7 g was estimated as corresponding to the recommended daily dietary intake Na. None of the other elements was present in concentrations that could exceed the dietary intake limits. In the sensory tests, fresh shoots were well accepted as salad greens but green salt, used as seasoning, was considered as insufficient in terms of saltiness and does not completely substitute cooking salt. The results confirm the nutritional and sensory value of S. ramossisima and represent a promising prospect for the incorporation of locally harvested or crop cultivated plants in catering meals.     

Effect of physiological integration in self/non-self genotype recognition on the clonal invader Carpobrotus edulis

Aims Biological invasions represent one of the most important threats to the conservation of biodiversity; however, the mechanisms underlying successful invaders remain unsolved. Many of the most aggressive invaders show clonal growth, and capacity for clonal integration has been pointed out recently as an important trait explaining the success of invasive plants. We aim to determine the role of physiological integration in the capacity for self/non-self genotype recognition in the clonal invader Carpobrotus edulis and the implications of this capacity for the expansion of this aggressive invader.Methods We used connected and severed ramets of identical or different genotype and we determined the capacity for self/non-self recognition by comparing changes in biomass partitioning to avoid competition for resources between pairs of ramets.Important findings Physiological integration allowed self/non-self genotype recognition in the invader C. edulis. Results showed a significant effect of physiological integration on the biomass allocated to roots by genetically identical ramets: older ramets specialize in acquisition of soil-based resources and younger ramets specialize in lateral expansion. This specialization could be considered a form of division of labour, which reduce intra-genotype competition. This is the first evidence that division of labour could be interpreted as a form of self/non-self recognition between genetically identical ramets. Capacity for self/non-self discrimination could contribute to increase the colonization capacity of the aggressive invader C. edulis. This is the first study showing an association between self/non-self recognition and invasiveness in a clonal plant.     

Probing a polar cluster in the retinal binding pocket of bacteriorhodopsin by a chemical design approach

Bacteriorhodopsin has a polar cluster of amino acids surrounding the retinal molecule, which is responsible for light harvesting to fuel proton pumping. From our previous studies, we have shown that threonine 90 is the pivotal amino acid in this polar cluster, both functionally and structurally. In an attempt to perform a phenotype rescue, we have chemically designed a retinal analogue molecule to compensate the drastic effects of the T90A mutation in bacteriorhodopsin. This analogue substitutes the methyl group at position C(13) of the retinal hydrocarbon chain by and ethyl group (20-methyl retinal). We have analyzed the effect of reconstituting the wild-type and the T90A mutant apoproteins with all-trans-retinal and its 20-methyl derivative (hereafter, 13-ethyl retinal). Biophysical characterization indicates that recovering the steric interaction between the residue 90 and retinal, eases the accommodation of the chromophore, however it is not enough for a complete phenotype rescue. The characterization of these chemically engineered chromoproteins provides further insight into the role of the hydrogen bond network and the steric interactions involving the retinal binding pocket in bacteriorhodopsin and other microbial sensory rhodopsins.     

Atrophic cardiac remodeling induced by taurine deficiency in wistar rats

Introduction

Micronutrient deficiency is observed in heart failure patients. Taurine, for example, represents 50% of total free amino acids in the heart, and in vivo studies have linked taurine deficiency with cardiomyopathy.

Methods

Thirty-four male Wistar rats (body weight = 100 g) were weighed and randomly assigned to one of two groups: Control (C) or taurine-deficient (T (-)). Beta-alanine at a concentration of 3% was added to the animals’ water to induce taurine deficiency in the T (-) group. On day 30, the rats were individually submitted to echocardiography; morphometrical and histopathological evaluation and metalloproteinase activity, oxidative stress and inflammation evaluation were performed. Tissue samples were collected to determine the taurine concentration in the heart.

Results

Taurine deficiency led to decreases in: ventricular wall thickness, left ventricle dry weight, myocyte sectional area, left ventricle posterior wall thickness and ventricular geometry. With regard to heart function, the velocity of the A wave, the ratio between the E and A wave, the ejection fraction, fractional shortening and cardiac output values were decreased in T (-) rats, suggesting abnormal diastolic and systolic function. Increased fibrosis, inflammation and increased activation of metalloproteinases were not observed. Oxidative stress was increased in deficient animals.

Conclusions

These data suggest that taurine deficiency promotes structural and functional cardiac alterations with unique characteristics.     

Lactobacillus salivarius A3iob Reduces the Incidence of Varroa destructor and Nosema Spp. in Commercial Apiaries Located in the Northwest of Argentina

Lactobacillus salivarius A3iob was administered to productive colonies belonging to commercial apiaries of small beekeepers (around 30–50 hives each one), from four departments of the province of Jujuy (Argentina): Yala, Tilquiza, El Carmen, and Los Alisos. The incidence of Varroa destructor and Nosema spp., before and after winter, was monitored during 2 years of study (2014–2015). Depending on the geographical location of each apiary and the application time, a monthly dose of the bacteria (10⁵ CFU/mL) reduced the levels of varroasis between 50 and 80%. Interestingly, L. salivarius A3iob cells remitted the percentage of the mites to undetectable values in an apiary treated with flumethrin (at Yala, Yungas region).

On the other hand, the spore levels of Nosema spp. in the lactobacilli-treated colonies also depended on the apiary and the year of application, but a significant decrease was mainly observed in the post-winter period. However, at Rivera (El Carmen’s department), no significant changes were detected in both parameters.

These results obtained after 2 years of work suggest that delivering L. salivarius A3iob cells to the bee colonies can become a new eco-friendly tool to cooperate with the control of these bees’ pests.

     

Variable actin dynamics requirement for the exit of different cargo from the trans-Golgi network

Efficient post-Golgi trafficking depends on microtubules, but actin filaments and actin-associated proteins are also postulated. Here we examined, by inverse fluorescence recovery after photobleaching, the role of actin dynamics in the exit from the TGN of fluorescent-tagged apical or basolateral and raft or non-raft-associated cargoes. Either the actin-stabilizing jasplakinolide or the actin-depolymerising latrunculin B variably but significantly inhibited post-Golgi traffic of non-raft associated apical p75NTR and basolateral VSV-G cargoes. The TGN-exit of the apical-destined VSV-G mutant was impaired only by latrunculin B. Strikingly, the raft-associated GPI-anchor protein was not affected by either actin toxin. Results indicate that actin dynamics participates in the TGN egress of both apical- and basolateral-targeted proteins but is not needed for apical raft-associated cargo.     

Contribution of planktonic and detritic fractions to the natural diet of mesozooplankton in Bahía Blanca Estuary

The pike, Esox lucius Linnaeus, is a predatory fish that supports important fisheries and could substantially impact prey populations around the temperate northern hemisphere. Consumption of prey by pike is most readily estimated using the energy budget to calculate food intake indirectly using estimates of growth rate and metabolism. Resting metabolic rate, R _s, is a particularly important component of such calculations. Here, the available estimates of R _s are reviewed and compared. Scaling coefficients for variation with body mass are consistent between the two studies in which they have been derived (0.81, 0.82). However, the effect of temperature on R _s markedly varies among studies (Q ₁₀ from 1.73 to 4.80). There is substantial variation in R _s (twofold to fourfold) among studies when temperature and fish size are accounted for. This variation is shown to have a large effect on energy budget calculations of energy intake and to be sufficient to account for imbalances in published budgets. These effects depend on age of pike and season; in one energy budget model, a 50% reduction in R _s resulted in decrease of 19–42% in estimated energy intake of pike. Potential causes of among-study variation in R _s are discussed and it is recommended that standard techniques by applied in the future to differentiate between genuine biological variation among populations and experimental factors. Guest editors: J. M. Farrell, C. Skov, M. Mingelbier, T. Margenau & J. E. Cooper International Pike Symposium: Merging Knowledge of Ecology, Biology, and Management for a Circumpolar Species