Digestibility of extruded proteins and metabolic transit of N ε -carboxymethyllysine in rats

Milk proteins are frequently used as supplements in fortified foods. However, processing produces chemical changes which likely affect the nutritional advantage. This study was intended to explore the possible difference in digestibility between extruded and non-extruded caseins and how the dietary N ^ε -carboxymethyllysine (CML) is metabolised. Normal rats were randomized into either an extruded protein diet (EP) or the same with unextruded proteins (UEP), for two periods of 2 weeks at 7 to 9 and 11 to 13 weeks of age. However, no difference in protein digestibility was detected between the two diets, either in young or in adult animals, despite a 9.4-fold higher level of CML and an 8.5-fold higher level of lysinoalanine in the EP than in the UEP. No diet-related changes were observed in plasma CML, either protein bound or free. Amounts of 38 and 48 % of the orally absorbed CML were excreted in urine and faeces, respectively, in UEP-fed rats. Lower rates of excretion were found in the EP-fed rats (23 and 37 %, respectively). A second animal study using a single oral dose of free CML (400 μg/rat) was set up to measure the systemic concentration of CML every hour from 0 to 4 h. It revealed that protein-bound CML was not affected by the oral dose of CML, and the highest free CML level found in the circulation was 600 ng/mL. Extruded proteins, therefore, appear to be well digested, and CML rapidly eliminated. Since its elimination is, however, incomplete, the question of its biodistribution and metabolism remains open.     

Impact of spray-drying on the pili of Lactobacillus rhamnosus GG

The preservation of the viability of microorganisms in probiotic formulations is the most important parameter ensuring the adequate concentration of live microorganisms at the time of administration. The formulation and processing techniques used to produce these probiotic formulations can influence the preservation of the microbial viability. However, it is also required that the bacteria maintain their key probiotic capacities during processing, formulation and shelf life. In this study, we investigated the impact of spray-drying on different cell wall properties of the model probiotic strain Lactobacillus rhamnosus GG, including its adherence to intestinal epithelial cells. The dltD gene knock-out mutant, L. rhamnosus GG CMPG5540, displaying modified cell wall lipoteichoic acids, showed significantly increased colony-forming units after spray-drying and subsequent storage under standard conditions compared to wild-type L. rhamnosus GG. In contrast, disruption of the biosynthesis of exopolysaccharides or pili expression did not impact survival. However, spray-drying did significantly affect the adherence capacity of L. rhamnosus GG. Scanning electron microscopy confirmed that the pili, key surface factors for adherence to intestinal cells and mucus, were sheared off during the spray-drying process. These data thus highlight that both the functionality and viability of probiotics should be assessed during the spray-drying process and subsequent storage.     

LppM impact on the colonization of macrophages by Mycobacterium tuberculosis

Mycobacterium tuberculosis produces several bacterial effectors impacting the colonization of phagocytes. Here, we report that the putative lipoprotein LppM hinders phagocytosis by macrophages in a toll‐like receptor 2‐dependent manner. Moreover, recombinant LppM is able to functionally complement the phenotype of the mutant, when exogenously added during macrophage infection. LppM is also implicated in the phagosomal maturation, as a lppM deletion mutant is more easily addressed towards the acidified compartments of the macrophage than its isogenic parental strain. In addition, this mutant was affected in its ability to induce the secretion of pro‐inflammatory chemokines, interferon‐gamma‐inducible protein‐10, monocyte chemoattractant protein‐1 and macrophage inflammatory protein‐1α. Thus, our results describe a new mycobacterial protein involved in the early trafficking of the tubercle bacillus and its manipulation of the host immune response.     

Analysis of the local organization and dynamics of cellular actin networks

A ctin filaments, with the aid of multiple accessory proteins, self-assemble into a variety of network patterns. We studied the organization and dynamics of the actin network in nonadhesive regions of cells bridging fibronectin-coated adhesive strips. The network was formed by actin nodes associated with and linked by myosin II and containing the formin disheveled-associated activator of morphogenesis 1 (DAAM1) and the cross-linker filamin A (FlnA). After Latrunculin A (LatA) addition, actin nodes appeared to be more prominent and demonstrated drift-diffusion motion. Superresolution microscopy revealed that, in untreated cells, DAAM1 formed patches with a similar spatial arrangement to the actin nodes. Node movement (diffusion coefficient and velocity) in LatA-treated cells was dependent on the level and activity of myosin IIA, DAAM1, and FlnA. Based on our results, we developed a computational model of the dynamic formin-filamin-actin asters that can self-organize into a contractile actomyosin network. We suggest that such networks are critical for connecting distant parts of the cell to maintain the mechanical coherence of the cytoplasm.     

Phylogenomic study of Amorphophallus (Alismatales; Araceae): When plastid DNA gene sequences help to resolve the backbone subgeneric delineation

Encompassing ca. 200 species distributed in paleotropical Africa and Asia, Amorphophallus is one of the largest genera of Araceae. In spite of the great economic interest in its glucomannan production, only a few studies have attempted to grasp the evolutionary history of this genus. In the current state of knowledge, four main clades, mostly linked to biogeographical delineation, have been identified from phylogenies based on a few genes. However, relationships among and within these clades still remain unclear, due to the rapid radiation that occurred during the early evolutionary history of the genus. Here, we generated genome skimming libraries for 43 specimens from 36 species distributed across the 4 clades, which allowed us to produce a phylogenetic matrix for a set of 71 plastid genes. Our phylogenies confirm the monophyly of these clades but show a new and well-resolved arrangement among these clades. Our analyses therefore provide a new scenario and timeline for the evolution of the main Amorphophallus clades, consistent with the morphological characteristics of the clades. The inferred scenario is also in agreement with climate dynamics and the onset of long-distance dispersal by the earliest migratory birds near the Oligocene/Miocene transition around 23 million years ago. Our study provides an up-to-date baseline to understand biogeographic and ecological processes that shaped the current diversity and distribution of Amorphophallus, paving the way for larger-scale phylogenomic studies based on plastid and nuclear genomes.     

Mutation Rates for Enzyme and Morphological Loci in Barley ( HORDEUM VULGARE L.)

Spontaneous mutation rates were estimated by assaying 84,126 seedlings of a highly homozygous barley line (isogenic line 2025) for five enzyme loci. No mutants were observed in 841,260 allele replications. This result excludes, at probability level 0.95, a spontaneous mutation rate larger than 3.56 x 10^-6/locus/gamete/generation for these enzyme loci. Isogenic line 2025 also was scored for mutants at four loci governing morphological variants. No mutants were observed in 3,386,850 allele replications which indicates that the upper bound for the mutation rate for these loci is 8.85 x 10^-7. It was concluded that, even though spontaneous mutation has been important in creating variability in the barley species at the loci scored, the rate is too low to have much affect on the short-term dynamics of barley populations.     

Knowledge and beliefs of international travellers about the transmission and prevention of HIV infection.

OBJECTIVES: To measure the perceived risk of acquired immunodeficiency syndrome (AIDS) among international travellers, to measure their knowledge of the transmission and prevention of HIV infection abroad and to identify some of the determinants of this knowledge. DESIGN: Survey. SETTING: Travellers'' immunization clinic providing mostly primary preventive care to international travellers. PARTICIPANTS: All clients aged 18 to 50 years seen at the clinic between Oct. 2 and Dec. 21, 1989, before their departure. MAIN OUTCOME MEASURES: Sixteen statements measured knowledge of transmission and prevention of HIV infection. Standardized scales measured health beliefs. RESULTS: The response rate was 81% (331/409). Compared with other diseases AIDS was perceived to be associated with a low risk except by those travelling to countries with a high prevalence of AIDS. Most of the clients were found to have a good knowledge of HIV transmission to travellers, although some myths remained popular and some real routes of transmission, especially blood, remained underrated. In all, 70% of the subjects believed in the efficacy of condoms when used with local people, as compared with 79% when used with other tourists; this difference was greatest among travellers who perceived AIDS as being particularly severe but difficult to prevent. The determinants of the knowledge of HIV transmission and prevention were a high level of education, a mother tongue other than French, unmarried status, a high prevalence of AIDS at the destination, the duration of the trip and a high perceived risk of HIV infection. CONCLUSIONS: Counselling should teach travellers (a) not to underestimate their risk of HIV infection during their trip, (b) to decrease the risk of requiring health care in developing countries and (c) to rely on their own prudent sexual behaviour rather than on their assessment of the level of risk posed by the environment.     

Cytoplasmic Poly(ADP-Ribose) Polymerase Associated with Free Messenger Ribonucleoprotein Particles in Rat Brain

Poly(ADP-ribose) polymerase associated with free cytoplasmic messenger ribonucleoprotein particles (free mRNP particles) carrying messenger RNA has been characterized in rat brain. There were first-order kinetics for NAD with an apparent Km for NAD of 90.5 +/- 0.70 microM and Vmax of 19.7 +/- 2.8 pmol ADP-ribose incorporated min-1 mg protein-1. Five poly(ADP-ribose) protein acceptors were identified in the Mr 37,000-120,000 range. It is hypothesized that ADP-ribosylation of specific free mRNP proteins might play a role in the derepression and translation of the silent mRNAs of free mRNP particles.     

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.