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1.
Porphyromonas gingivalis is a peptide-fermenting asaccharolytic periodontal pathogen. Its genome contains several genes encoding cysteine peptidases other than gingipains. One of these genes (PG1055) encodes a protein called Tpr (thiol protease) that has sequence similarity to cysteine peptidases of the papain and calpain families. In this study we biochemically characterize Tpr. We found that the 55-kDa Tpr inactive zymogen proteolytically processes itself into active forms of 48, 37, and 33 kDa via sequential truncations at the N terminus. These processed molecular forms of Tpr are associated with the bacterial outer membrane where they are likely responsible for the generation of metabolic peptides required for survival of the pathogen. Both autoprocessing and activity were dependent on calcium concentrations >1 mm, consistent with the protein''s activity within the intestinal and inflammatory milieus. Calcium also stabilized the Tpr structure and rendered the protein fully resistant to proteolytic degradation by gingipains. Together, our findings suggest that Tpr is an example of a bacterial calpain, a calcium-responsive peptidase that may generate substrates required for the peptide-fermenting metabolism of P. gingivalis. Aside from nutrient generation, Tpr may also be involved in evasion of host immune response through degradation of the antimicrobial peptide LL-37 and complement proteins C3, C4, and C5. Taken together, these results indicate that Tpr likely represents an important pathogenesis factor for P. gingivalis.  相似文献   
2.
Connecdenn 1/2 are DENN (differentially expressed in normal and neoplastic cells) domain-bearing proteins that function as GEFs (guanine nucleotide exchange factors) for the small GTPase Rab35. Disruption of connecdenn/Rab35 function leads to defects in the recycling of multiple cargo proteins from endosomes with altered cell function, yet the regulation of connecdenn GEF activity is unexplored. We now demonstrate that connecdenn 1/2 are autoinhibited such that the purified, full-length proteins have significantly less Rab35 binding and GEF activity than the isolated DENN domain. Both proteins are phosphorylated with prominent phosphorylation sites between residues 500 and 600 of connecdenn 1. A large scale proteomics screen revealed that connecdenn 1 is phosphorylated at residues Ser-536 and Ser-538 in an Akt-dependent manner in response to insulin stimulation of adipocytes. Interestingly, we find that an Akt inhibitor reduces connecdenn 1 interaction with Rab35 after insulin treatment of adipocytes. Remarkably, a peptide flanking Ser-536/Ser-538 binds the DENN domain of connecdenn 1, whereas a phosphomimetic peptide does not. Moreover, connecdenn 1 interacts with 14-3-3 proteins, and this interaction is also disrupted by Akt inhibition and by mutation of Ser-536/Ser-538. We propose that Akt phosphorylation of connecdenn 1 downstream of insulin activation regulates connecdenn 1 function through an intramolecular interaction.  相似文献   
3.
There is a diverse range of microbiological challenges facing the food, healthcare and clinical sectors. The increasing and pervasive resistance to broad‐spectrum antibiotics and health‐related concerns with many biocidal agents drives research for novel and complementary antimicrobial approaches. Biofilms display increased mechanical and antimicrobial stability and are the subject of extensive research. Cold plasmas (CP) have rapidly evolved as a technology for microbial decontamination, wound healing and cancer treatment, owing to the chemical and bio‐active radicals generated known collectively as reactive oxygen and nitrogen species. This review outlines the basics of CP technology and discusses the interactions with a range of microbiological targets. Advances in mechanistic insights are presented and applications to food and clinical issues are discussed. The possibility of tailoring CP to control specific microbiological challenges is apparent. This review focuses on microbiological issues in relation to food‐ and healthcare‐associated human infections, the role of CP in their elimination and the current status of plasma mechanisms of action.  相似文献   
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Faced with the decline of pollinators, it is relevant to strengthen our understanding of the whole plant-pollinator web in semi-natural grasslands that serve as refuges for pollinator populations. The aim of this study was to explore the diversity of flower-foraging insects involved in pollen transfer in mountain semi-natural grasslands. Insects actively collecting pollen and/or nectar were caught in spring in six mountain semi-natural grasslands displaying a floristic richness gradient. Individual determinations of insects were made at the finest possible taxonomic scale and pollen loads were removed from the insect body. Using next-generation DNA sequencing, pollens were identified through the ribosomal DNA cistron using the ITS2 database and the ITS plant rDNA cistron sequences from Genbank. A total of 236 flower-foraging insects were collected. Diptera represented 82% of the total catches distantly followed by Hymenoptera (15%) and Apoidea (bees) (11%). Visual observations revealed that Diptera foraged on 16 of the 21 flower species visited by insects. DNA metabarcoding showed that 82% (191) of all of the collected insects were carrying pollen and 44% (104) were carrying two genera of plants or more. Our results demonstrate that Diptera are potential key-pollinators in mountain semi-natural grasslands that cannot be overlooked by the scientific community. However difficulties of taxonomic determination due to severe shortage of experts for Diptera have to be urgently overcome. Further studies on the link between pollen transfer and actual pollination in a global change context are also required. Moreover, our results support the idea that DNA metabarcoding provides accurate information about the plants-insects networks but it also pointed out sensitive issues, especially the necessity to build reliable national barcode databases.  相似文献   
6.
The application of pectinases in industrial olive-oil processes is restricted by its production cost. Consequently, new fungal strains able to produce higher pectinase titers are required. The aim of this work was to study the capability of Aspergillus giganteus NRRL10 to produce pectinolytic enzymes by SSF and evaluate the application of these in olive-oil extraction. A. giganteus was selected among 12 strains on the basis of high pectinolytic activity and stability. A mixture composed by wheat bran, orange, and lemon peels was selected as the best substrate for enzyme production. Statistical analyses of the experimental design indicated that pH, temperature, and CaCl2 are the main factors that affect the production. Subsequently, different aeration flows were tested in a tray reactor; the highest activity was achieved at 20 L min?1 per kilogram of dry substrate (kgds). Finally, the pectinolytic enzymes from A. giganteus improved the oil yield and rheological characteristics without affecting oil chemical properties.  相似文献   
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Palmitic acid (PA) is associated with higher blood concentrations of medium-chain acylcarnitines (MCACs), and we hypothesized that PA may inhibit progression of FA β-oxidation. Using a cross-over design, 17 adults were fed high PA (HPA) and low PA/high oleic acid (HOA) diets, each for 3 weeks. The [1-13C]PA and [13-13C]PA tracers were administered with food in random order with each diet, and we assessed PA oxidation (PA OX) and serum AC concentration to determine whether a higher PA intake promoted incomplete PA OX. Dietary PA was completely oxidized during the HOA diet, but only about 40% was oxidized during the HPA diet. The [13-13C]PA/[1-13C]PA ratio of PA OX had an approximate value of 1.0 for either diet, but the ratio of the serum concentrations of MCACs to long-chain ACs (LCACs) was significantly higher during the HPA diet. Thus, direct measurement of PA OX did not confirm that the HPA diet caused incomplete PA OX, despite the modest, but statistically significant, increase in the ratio of MCACs to LCACs in blood.  相似文献   
9.
Identifying which introduced species have the greatest potential for establishment, spread and impact is critical for prioritizing pre‐ and post‐border control. Using species distribution modelling and existing species locations we assessed the establishment risk based on the climatic suitability areas of 25 plant species listed as eradication targets under South African regulations. To improve confidence, three bioclimatic models were used to predict the potential distribution of each species. This information was combined with the number of localities and the “eradication feasibility syndromes” in a scoring‐categorical system to rank the species. Three management groups were identified. Group “A” includes species with medium‐high establishment risk and higher likelihood to be eradicated, these species should be a priority for eradication. Group “B” includes species with a medium‐low establishment risk but given the low number of known population and the species characteristics, eradication is likely to be feasible. Finally species in group “C” scored a medium‐high establishment risk but the eradication would be difficult due to the high number of known localities. This ranking provides a rapid method to prioritize the management towards the eradication of new potential invasive plant species in the country combining the establishment risk, known number of localities and the inferred eradication success.  相似文献   
10.
Recruitment of new individuals, through germination and seedling survival, is a key process for short-lived plants. Here, we analyzed intraspecific variation in recruitment across the latitudinal range of Plantago coronopus, a widespread herb that produces both large basal seeds with a mucilaginous coat and small apical seeds without coat. We experimentally tested the effects of seed traits and water availability on recruitment, by using seeds from a wide environmental stress gradient from N Africa to N Europe. Our experiments were carried out in controlled environmental conditions and in dunes where the species naturally occurs. Water shortage decreased seed germination and seedling survival for all populations, showing the importance of water supply for P. coronopus. Basal seeds showed higher and faster germination rates than apical seeds. Since among-population variation in seed mass was not related to potential germination rate, it is the mucilaginous coat rather than size difference that likely drives the differential success between seed morphs. Seed mass positively affected seedling survival instead, but only in controlled conditions with regular water supply. An experiment in a dune showed indeed that the highest survival corresponded to the local population and not the one with the largest seeds. Our results demonstrate that both intrinsic and extrinsic factors drive inter-population variation in the early life stages of this short-lived plant, allowing it to adapt across the environmentally heterogeneous distribution range. Gathering information on intraspecific variation in recruitment-related traits will help us to understand and predict plant responses in a context of climatic change.  相似文献   
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