Random recirculation of small T lymphocytes from thoracic duct lymph in the mouse

The migration of ⁵¹Cr-labeled nylon-wool separated mouse thoracic duct T cells has been followed in order to determine whether there is a circulation of small (nondividing) T cells through the small intestine. Approximately 6% of the injected dose of T-TDL localized in the small intestine (minus Peyer's patches). Experiments revealed that this gut-localizing cell population consisted almost entirely, if not exclusively, of lymphoblasts present in mouse T-TDL. When lymphoblasts and small lymphocytes from mouse T-TDL were separated by velocity sedimentation, and the migration of separated fractions was studied, we found large cells (66% blasts) migrated well to the gut but poorly to the lymph nodes, whereas small cells (2% blasts) showed minimal migration to the gut but localized randomly in lymph nodes and spleen. The in vivo distribution of small cells from T-TDL was similar to that of T-PLN. Furthermore, the recirculatory patterns of both ⁵¹Cr-labeled T-TDL and T-PLN were found to be identical as accessed by their rate of recovery in the thoracic duct lymph of recipient mice. These results support the notion that the vast majority of T-TDL and T-PLN are part of a common pool of recirculating T cells which recirculate randomly through lymph nodes and spleen and not the small intestine.     

Thermotropic behavior of monoglucocerebroside--dipalmitoylphosphatidylcholine multilamellar liposomes

The thermotropic behavior of multilamellar liposomes prepared from mixtures of glucocerebroside and dipalmitoylphosphatidylcholine has been studied by high-sensitivity scanning calorimetry. It is shown that glucocerebroside has a marked effect on the gel--liquid crystalline transition of dipalmitoylphosphatidylcholine. The pretransition seen in pure samples of dipalmitoylphosphatidylcholine is undetectable at small mode fractions of glucocerebrosides (less than 10%). The main transition is shifted to higher temperatures and becomes broader and less cooperative in the presence of glucocerebroside. The enthalpy change of the main transition decreases with increasing the glucocerebroside content. However, this decrease is not linear with the glucocerebroside/phospholipid mole ratio. Glucocerebroside itself does not show a separate transition in the temperature range of these studies (10--75 degree C). The origin of these effects and their dependence on the glucocerebroside content suggest that the in-plane distribution of glucocerebroside molecules is affected by the physical state of the lipid bilayer and by the glucocerebroside/phospholipid mole ratio.     

Thermodynamics of transfer ribonucleic acids: the effect of sodium on the thermal unfolding of yeast tRNAPhe.

The thermal unfolding of yeast phenylalanine-specific tRNA (tRNA^Phe) has been calorimetrically investigated at several salt concentrations in the absence of magnesium. Application of the deconvolution theory of macromolecular conformational transitions allows calculation of the thermodynamic parameters of unfolding. It is demonstrated that the unfolding of tRNA^Phe occurs in a sequential fashion and that four separate transitions or five macromolecular thermodynamic states exist in the temperature range 8–72°C under the experimental conditions of these studies (0.067–0.52M Na⁺). The enthalpy and entropy changes between states and the relative population of each state as a function of temperature and salt concentration have been obtained. Sodium stabilizes the low-temperature conformations of tRNA^Phe. The increase in the melting temperatures of each transition is shown to be linearly dependent on the logarithm of sodium concentration. These results allow calculation of the “phase” diagram for the transitions as a function of salt concentration.     

A bead and spring model for the stiffness of DNA.

The chain stiffness of linear native DNA is represented by a generalized bead and spring model recently proposed. It incorporates molecular rigidity by means of springs between beads, which are second neighbors along the contour of the chain. These springs are equivalent to elastic forces having longitudinal and transversal contributions. The model is compared with existing experimental data of sedimentation and low-angle light scattering to obtain the statistical parameters of DNA. The value of the statistical length obtained with this model is 1300 Å. The same value is obtained with the wormlike chain. Throughout this analysis, excluded volume is left out as a simplifying assumption.     

Using anticipatory life cycle assessment to enable future sustainable construction

The built environment is the largest single emitter of CO₂ and an important consumer of energy. Much research has gone into the improved efficiency of building operation and construction products. Life Cycle Assessment (LCA) is commonly used to assess existing buildings or building products. Classic LCA, however, is not suited for evaluating the environmental performance of developing technologies. A new approach, anticipatory LCA (a‐LCA), promises various advantages and can be used as a design constraint during the product development stage. It helps overcome four challenges: (i) data availability, (ii) stakeholder inclusion, (iii) risk assessment, and (iv) multi‐criteria problems. This article's contribution to the line of research is twofold: first, it adapts the a‐LCA approach for construction‐specific purposes in theoretical terms for the four challenges. Second, it applies the method to an innovative prefabricated modular envelope system, the CleanTechBlock (CTB), focusing on challenge (i). Thirty‐six CTB designs are tested and compared to conventional walls. Inclusion of technology foresight is achieved through structured scenario analysis. Moreover, challenge (iv) is tackled through the analysis of different environmental impact categories, transport‐related impacts, and thickness of the wall assemblies of the CTB. The case study results show that optimized material choice and product design is needed to reach the lowest environmental impact. Methodological findings highlight the importance of context‐specific solutions and the need for benchmarking new products.     

Bioreactor production of 2,3-butanediol by Pantoea agglomerans using soybean hull acid hydrolysate as substrate

Production of 2,3-butanediol (2,3-BD) by Pantoea agglomerans strain BL1 was investigated using soybean hull hydrolysate as substrate in batch reactors. The cultivation media consisted of a mixture of xylose, arabinose, and glucose, obtained from the hemicellulosic fraction of the soybean hull biomass. We evaluated the influence of oxygen supply, pH control, and media supplementation on the growth kinetics of the microorganism and on 2,3-BD production. P. agglomerans BL1 was able to simultaneously metabolize all three monosaccharides present in the broth, with average conversions of 75% after 48 h of cultivation. The influence of aeration conditions employed demonstrated the mixed acid pathway of 2,3-BD formation by enterobacteria. Under fully aerated conditions (2 vvm of air), up to 14.02 g L⁻¹ of 2.3-BD in 12 h of cultivation were produced, corresponding to yields of 0.53 g g⁻¹ and a productivity of 1.17 g L⁻¹ h⁻¹, the best results achieved. These results suggest the production potential of 2,3-BD by P. agglomerans BL1, which has been recently isolated from an environmental consortium. The present work proposes a solution for the usage of the hemicellulosic fraction of agroindustry biomasses, carbohydrates whose utilization are not commonly addressed in bioprocess.

     

The Galactose-Binding Lectin Isolated from Vatairea macrocarpa Seeds Enhances the Effect of Antibiotics Against Staphylococcus aureus–Resistant Strain

Probiotics and Antimicrobial Proteins - The use of natural products together with standard antimicrobial drugs has recently received more attention as a strategy to combat infectious diseases...     

Evidence of doubly uniparental inheritance of the mitochondrial DNA in Polititapes rhomboides (Bivalvia,Veneridae): Evolutionary and population genetic analysis of F and M mitotypes

Doubly uniparental inheritance (DUI) is a particular mitochondrial DNA inheritance mode reported in a number of bivalves. DUI species show two types of mtDNA, one transmitted from females to daughters and sons (F mitotype) and another one from males to sons (M mitotype). In Veneridae, the existence of DUI has been investigated in several species but it was found in only two of them. In this study, we obtained partial sequences of rrnL, cytb and cox1 genes of males and females of Polititapes rhomboides from NW Spain and we demonstrated the existence of heteroplasmy in males, as expected under DUI. F and M mitotypes showed a taxon-specific phylogenetic pattern and similar evolutionary rates. We focused on cox1 for population genetic analysis, examining separately F and M mitotypes, but also F mitotypes from females (F_♀) and males (F_♂). In all cases, cox1 bears signs of strong purifying selection, with no apparent evidence of relaxed selection in the M genome, while the divergence between F and M genomes is in agreement with the neutral model of evolution. The cox1 polymorphism, higher at the M than at the F genome, also shows clear footprints of genetic hitchhiking with favourable mutations at other mtDNA loci, except for F_♂. In terms of population structure, results suggest that the pattern depends on the examined mitotype (F, F_♀, F_♂ or M).