Digestive Strategies Research Articles

Adaptive trade-offs in fish energetics and physiology: insights from adaptive differentiation among juvenile salmonids

Juveniles of different salmonid species often co-exist along environmental gradients, making them a useful model for identifying dominant trade-off axes and their stability within a biological hierarchy (e.g., from individuals to populations to species). In this perspective, we use multivariate trade-offs among juvenile coho salmon (Oncorhynchus kisutch) and rainbow trout (Oncorhynchus mykiss) as a case study to explore broader-scale patterns of trait association. Multivariate ordination identified a dominant trade-off axis between high growth, consumption, and growth efficiency versus high aerobic scope and active metabolism among individual juvenile rainbow trout and three ecologically divergent rainbow trout populations. This pattern suggests a dominant trade-off between growth and active metabolism among individuals and populations, facilitated by simple developmental controls on increased energy intake (larger digestive tract, potentially more risky foraging behavior). In contrast, the adaptive trade-off differentiating species appears to have shifted to maximizing growth and consumption (rainbow trout) versus maximizing growth efficiency (coho), based on evolved differences in foraging strategy and digestive physiology. The generality of these patterns remains uncertain, but trade-offs related to growth efficiency may be an underappreciated dimension of adaptive differentiation in fishes, and their relationship to digestive strategy and active metabolism warrants further investigation.

Review on anaerobic digestion of rice straw for biogas production.

India is an agrarian country producing a large amount of rice straw as an agricultural residue. These residues are burnt openly leading to severe environmental pollution and health hazards. Among several options available, anaerobic digestion of rice straw into biomethane gas and digestate is a promising technology. The current paper reviews the characteristics, principles of rice straw and the process variables (temperature, volatile fatty acids, and pH, carbon to nitrogen ratio, metal elements and organic loading rate) that affect the performance of the rice straw digestion and process strategies which may alleviate the barriers and may improve the biomethane yield. Co-digestion of rice straw with nitrogen-rich substrates is proven to be an effective way to balance the carbon to nitrogen ratio, in turn, leads to nutrient balance and enhance the biomethane yields of anaerobic co-digestion system. Moreover, pretreatment is another effective strategy; physical, chemical and biological pretreatments are reviewed in the article which improved the performance of digester. The utilisation of rice straw along with other co-substrates and appropriate pretreatment may be a recommended sustainable solution for preventing environmental and health hazards.

Importance of methodology in the evaluation of renal mononuclear phagocytes and analysis of a model of experimental nephritis with Shp1 conditional knockout mice

Tissue resident mononuclear phagocytes (Mophs), comprising monocytes, macrophages, and dendritic cells (DCs), play important roles under physiological and pathological conditions. The presence of these cells in the kidney has been known for decades, and studies of renal Mophs (rMophs) are currently underway. Since no unified procedure has been identified to isolate rMophs, results of flow cytometric analysis of rMophs have been inconsistent among studies. We therefore first evaluated a preparative method for rMophs using collagenous digestion. The yield of rMophs greatly increased after the collagenase digestion. In particular, F4/80high rMophs, which were positive for CD11c, a specific marker of DCs, dramatically increased. In addition, since neutrophils are sometimes mixed among rMophs in the analysis of flow cytometry, we established a gating strategy for eliminating neutrophils. To determine the contribution of rMophs to the development of autoimmune nephritis, we analyzed an experimental model of autoimmune nephritis that was applied to Shp1 conditional knockout mice (Shp1 CKO). This knockout strain is generated by crossing a mouse line carrying floxed Shp1 allele to mice expressing Cre recombinase under the control of the CD11c promoter. Shp1 CKO therefore specifically lack Shp1 in cells expressing CD11c. As a result, Shp1 CKO were susceptible to that experimental glomerulonephritis and F4/80high rMophs of Shp1 CKO increased dramatically. In conclusion, our preparative methods for collagenase digestion and gating strategy for neutrophils are necessary for the analysis of rMophs, and Shp1 suppresses the development of autoimmune nephritis through the control of rMophs.

Adapting Methodology Used on Captive Subjects for Estimating Gut Passage Time in Wild Monkeys

Gut passage time of food has consequences for primate digestive strategies, which subsequently affect seed dispersal. Seed dispersal models are critical in understanding plant population and community dynamics through estimation of seed dispersal distances, combining movement data with gut passage times. Thus, developing methods to collect in situ data on gut passage time are of great importance. Here we present a first attempt to develop an in situ study of gut passage time in an arboreal forest guenon, the samango monkey (Cercopithecus albogularis schwarzi) in the Soutpansberg Mountains, South Africa. Cercopithecus spp. consume large proportions of fruit and are important seed dispersers. However, previous studies on gut passage times have been conducted only on captive Cercopithecusspp. subjects, where movement is restricted, and diets are generally dissimilar to those observed in the wild. Using artificial digestive markers, we targeted provisioning of a male and a female samango monkey 4 times over 3 and 4 days, respectively. We followed the focal subjects from dawn until dusk following each feeding event, collecting faecal samples and recording the date and time of deposition and the number of markers found in each faecal sample. We recovered 6.61 ± 4 and 13 ± 9% of markers from the male and the female, respectively, and were able to estimate a gut passage window of 16.63–25.12 h from 3 of the 8 trials. We discuss methodological issues to help future researchers to develop in situ studies on gut passage times.

Start-Up Strategy and Process Performance of Semi-Continuous Anaerobic Digestion of Raw Sugarcane Vinasse

The sugarcane distillery waste water is generated throughout the sugarcane molasses fermentation and distillation. In Reunion Island, a part of the vinasse production is treated by methanisation process. However, the remaining part is diluted then discharged into the sea. The aim of this work is to study the anaerobic treatment of sugar cane vinasse, with energy recovery. Nonetheless, vinasse pollutant load is difficult to treat. Regarding the experimentations, the biochemical potential (BMP) test is used for the determination of the methanogen potential. The BMP is then modelled with the modified Gompertz and the first order kinetic models. Furthermore, a laboratory study is carried out for studying the methane production of vinasse in semi-industrial scale over a period of 130 days. The start-up strategy of the 16 L pilot is proposed, in particular the gradual increase of organic load. The physico-chemical analysis of the medium is needed to prevent and explain the failure of the process. Indeed, the biogas production and physico-chemical measurements during the digestion are presented and discussed. The maximum methane yield of the BMP is 185 $${\text{NL}}_{{{\text{CH}}_{4} }} \,{\text{kg}}_{{{\text{COD}}}}^{ - 1} ,$$ obtained with I/S ratio in terms of volatile solids of 0.7. The outcomes showed that the first-order kinetic and modified Gompertz models fit well with the BMP test curves. Concerning the pilot, the start-up period lasted 45 days the maximum specific production was 151.00 $${\text{NL}}_{{{\text{CH}}_{4} }} \,{\text{kg}}_{{{\text{COD}}}}^{ - 1}$$ (232.31 $${\text{NL}}_{{{\text{biogas}}}} \,{\text{kg}}_{{{\text{COD}}}}^{ - 1}$$ ). In further studies, different mixing strategies will be studied.

Accurate determination of drug-to-antibody ratio of interchain cysteine-linked antibody-drug conjugates by LC-HRMS.

Accurate determination of the drug-to-antibody ratio (DAR) of interchain cysteine-linked antibody-drug conjugates (ADCs) is challenging. High-resolution mass spectrometry (HRMS) analysis of the ADCs at the intact or subunit level provides a feasible way to measure the DAR. However, the measured DAR is usually lower than the true DAR because of the variation in ionization efficiency between different DAR species. In this work, we developed a novel standard-free HRMS method involving isotope-labeled payload conjugation, protease digestion, and liquid chromatography-HRMS (LC-HRMS) analysis for accurate determination of the DAR of the interchain cysteine-linked ADCs with cleavable or non-cleavable linkers. Isotope-labeled payload conjugations eliminated the structural and chemical differences between different DAR species and ensured that the drugs or payload-containing peptides could be separated from each other in the mass spectrometer. A papain digestion strategy for ADCs with cleavable linkers showed a DAR of 3.79, with a relative standard deviation (RSD) of 0.48 (n = 3). Similarly, the trypsin and chymotrypsin digestion strategy that is applicable to ADCs with non-cleavable linkers showed a DAR of 3.77 and an RSD of 0.86 (n = 3). The DAR determined by this method was consistent with the DAR of the ADCs that was measured by the UV/Vis method. This method will be very useful to researchers working in the field of ADC discovery and development. Graphical abstract.

Digestibility and Retention Time of Coastal Bermudagrass (Cynodon dactylon) Hay by Horses.

Simple SummaryLonger retention of forages with increased fiber concentrations may be a compensatory digestive strategy in horses. We investigated the digestive characteristics of bermudagrass hay, a prominent warm-season grass in the southeast United States that has greater fiber concentrations than other common forages fed to horses. The morphological structure and photosynthetic pathway of warm-season grasses differ from cool-season grasses and legumes which may have important impacts on equine digestion and digesta transit through the gastrointestinal tract. The retention time of Coastal bermudagrass was longer than alfalfa or orchardgrass hay. The digestibility of Coastal bermudagrass decreased with increasing maturity, but the fiber digestibility of alfalfa and orchardgrass was similar to the earliest maturity of Coastal bermudagrass hay. The chemical composition of the plant cell wall influences diet digestibility and is a major difference between warm-season and cool-season forages. The increased retention time of Coastal bermudagrass allows for microbial fermentation to occur longer, adapting to more difficult-to-digest plant cell walls in warm-season forages. The decrease in diet digestibility when horses consume warm-season forages can be reduced by feeding early maturity forage, by harvesting hay at an earlier stage of growth or managing pastures in a vegetative state.Bermudagrass (Cynodon dactylon) and other warm-season grasses are known for their increased fiber concentrations and reduced digestibility relative to cool-season grasses and legumes. This study investigated the digestive characteristics and passage kinetics of three maturities of Coastal bermudagrass hay. A 5 × 5 Latin square design experiment was used to compare the digestion of five hays: alfalfa (Medicago sativa, ALF), orchardgrass (Dactylis glomerata, ORCH), and Coastal bermudagrass harvested at 4 (CB 4), 6 (CB 6), and 8 weeks of regrowth (CB 8). Horses were fed cobalt-ethylenediaminetetraacetic acid (Co-EDTA) and ytterbium (Yb) labeled neutral detergent fiber (NDF) before an 84-h total fecal collection to determine digesta retention time. Dry matter digestibility was greatest for ALF (62.1%) and least for CB 6 (36.0%) and CB 8 diets (36.8%, SEM = 2.1; p < 0.05). Mean retention time was longer (p < 0.05) for Coastal bermudagrass (particulate 31.3 h, liquid 25.3 h) compared with ORCH and ALF (28.0 h, SEM = 0.88 h; 20.7 h, SEM = 0.70 h). Further evaluation of digesta passage kinetics through mathematical modeling indicated ALF had distinct parameters compared to the other diets. Differences in digestive variables between forage types are likely a consequence of fiber physiochemical properties, warranting further investigation on forage fiber and digestive health.

Smart Cutter: An Efficient Strategy for Increasing the Coverage of Chemical Cross-Linking Analysis.

Chemical cross-linking combined with mass spectrometry (CXMS) has emerged as a powerful tool to study protein structure, conformation, and protein-protein interactions (PPIs). Until now, most cross-linked peptides were generated by using commercial cross-linkers, such as DSS, BS3, and DSSO, which react with the primary amino groups of the lysine residues of proteins. However, trypsin, the most commonly used proteolytic enzyme, cannot cleave the C-terminus of a linked lysine, making the obtained cross-linked peptides longer than common peptides and unfavorable for MS identification and data searching. Herein, we propose an in situ sequential digestion strategy using enzymes with distinct cleavage specificity, named as smart cutter, to generate cross-linked peptides with suitable length so that the identification coverage could improve. Through the application of such a strategy to DSS cross-linked E. coli lysates, additional cross-linked sites (1.3-fold increase) obtained in comparison with those obtained by trypsin-trypsin digestion (2879 vs 1255). Among the different digestion combinations, AspN-trypsin performed the best, with 64% (673/1059) of the cross-linked sites complementary to trypsin-trypsin digestion, which is beneficial to ensure the depth for studying protein structure and PPIs. Taking the 60 kDa chaperonin protein as an example, more than twice the cross-linked sites (30 vs 14) were identified to enrich the protein structure information. In addition, compared to the published protein interaction network for E. coli ( http://www.bacteriome.org ), 91 potential PPIs were discovered with our strategy, of which 65 have not covered by trypsin-trypsin digestion. Therefore, these results illustrate the great significance of smart-cutter-based CXMS for the revelation of protein structure as well as finding new PPIs.

Repeated Evolution of Divergent Modes of Herbivory in Non-avian Dinosaurs

The importance of adaptation [1-4] versus organizational constraints [5-7] in shaping common macroevolutionary trends remains unclear [8]. The fossil record is key to this problem, as it provides data on repetitive trait evolution between lineages [4,8]. However, quantitative analyses investigating these dynamics with fossil data are rare [8]. Herbivory evolved multiple times within Mesozoic dinosaurs [9, 10], allowing analysis of common phenotypic responses to dietary evolution. Whereas repeated patterns of character acquisition [9] and functional changes [11-13] are observed between some herbivorous dinosaur clades, biomechanical studies resolve significant differences between morphologically similar taxa [12-14]. However, previous biomechanical analyses have not accounted for phylogenetic non-independence (e.g., [13-16]) or been restricted to individual clades (e.g., [11,12, 16]). Here, we use multivariate analysis of biomechanical characters, within a robust phylogenetic context, toinvestigate functional pathways to herbivory inalarge sample of non-avian dinosaurs. Results demonstrate multiple solutions to herbivory. Notably, two fundamentally different modes are observed to evolve independently multiple times, with morphofunctional changes in the skull co-varying with digestive strategy. These modes distinguish between gut-processing sauropodomorphs and theropods tending toward gracile crania and low bite forces and ornithischian taxa exhibiting character complexes associated with extensive oral processing. Although convergence within thesesubsets of taxa is common, it is not observed between them due to functional constraints imposed during the early evolution of each group. This highlights the hierarchical nature of evolution, withadaptation driving convergence within regionsof morphospace delimited by phylogenetic contingency.

Recovery of Treated Sludge

This paper presents the methods for recovery of treated sludge: technological valorisation, agricultural valorization, energy recovery, gasification, pyrolysis, supercritical oxidation of water, obtaining the material for plastering, obtaining bricks. These technologies are biology-based technologies (advanced anaerobic digestion strategies and bio-drying) and heat-based technologies (gasification, pyrolysis and supercritical water processing).

Recovery of Treated Sludge

This paper presents the methods for recovery of treated sludge: technological valorisation, agricultural valorization, energy recovery, gasification, pyrolysis, supercritical oxidation of water, obtaining the material for plastering, obtaining bricks. These technologies are biology-based technologies (advanced anaerobic digestion strategies and bio-drying) and heat-based technologies (gasification, pyrolysis and supercritical water processing). Keywords: treated sludge, agricultural recovery, energy recovery

Proteomic Analysis of the Xanthan-Degrading Pathway of Microbacterium sp. XT11.

Xanthan, a highly stable polysaccharide which is not easily degraded by most microorganisms, contains a cellulosic backbone with trisaccharide side chains composed of mannosyl-glucuronyl-mannose attached α-1,3 to alternating glucosyl residues. Different digestion strategies were first applied to demonstrate the complexity about the proteomes of Microbacterium sp. XT11 in xanthan medium and glucose medium. Significantly up-regulated proteins induced by xanthan were screened out by the label-free quantitation of the proteomes of Microbacterium sp. XT11 in xanthan medium and glucose medium. Consequently, 2746 and 2878 proteins were identified in proteomes of Microbacterium sp. XT11 in xanthan medium and glucose medium individually, which represent 80.6 and 84.4% of total protein dataset predicted to be expressed by the gene. In the list of 430 induced proteins containing the proteins specifically expressed or up-regulated in xanthan medium, 19 proteins involved in carbohydrate-active enzymes database and 38 proteins annotated with transporter activity were critical in the degrading pathway of xanthan. Four CAZymes (GH3, GH38, GH9, and PL8) and one ABC transporter (LX1-1GL001097) were verified with quantitative real-time polymerase chain reaction. Four CAZymes (GH3, GH38, GH9, and PL8) were further verified with the enzyme assay. This study suggests a xanthan-degrading pathway in Microbacterium sp. XT11, and other potential xanthan degradation-related proteins still need further investigation.

Covariation of diet and gut microbiome in African megafauna

A major challenge in biology is to understand how phylogeny, diet, and environment shape the mammalian gut microbiome. Yet most studies of nonhuman microbiomes have relied on relatively coarse dietary categorizations and have focused either on individual wild populations or on captive animals that are sheltered from environmental pressures, which may obscure the effects of dietary and environmental variation on microbiome composition in diverse natural communities. We analyzed plant and bacterial DNA in fecal samples from an assemblage of 33 sympatric large-herbivore species (27 native, 6 domesticated) in a semiarid East African savanna, which enabled high-resolution assessment of seasonal variation in both diet and microbiome composition. Phylogenetic relatedness strongly predicted microbiome composition (r = 0.91) and was weakly but significantly correlated with diet composition (r = 0.20). Dietary diversity did not significantly predict microbiome diversity across species or within any species except kudu; however, diet composition was significantly correlated with microbiome composition both across and within most species. We found a spectrum of seasonal sensitivity at the diet-microbiome nexus: Seasonal changes in diet composition explained 25% of seasonal variation in microbiome composition across species. Species' positions on (and deviations from) this spectrum were not obviously driven by phylogeny, body size, digestive strategy, or diet composition; however, domesticated species tended to exhibit greater diet-microbiome turnover than wildlife. Our results reveal marked differences in the influence of environment on the degree of diet-microbiome covariation in free-ranging African megafauna, and this variation is not well explained by canonical predictors of nutritional ecology.

Proteomic and N-Terminomic TAILS Analyses of Human Alveolar Bone Proteins: Improved Protein Extraction Methodology and LysargiNase Digestion Strategies Increase Proteome Coverage and Missing Protein Identification.

With 2129 proteins still classified by the Human Proteome Organisation Human Proteome Project (HPP) as "missing" without compelling evidence of protein existence (PE) in humans, we hypothesized that in-depth proteomic characterization of tissues that are technically challenging to access and extract would yield evidence for tissue-specific missing proteins. Paradoxically, although the skeleton is the most massive tissue system in humans, as one of the poorest characterized by proteomics, bone falls under the HPP umbrella term as a "rare tissue". Therefore, we aimed to optimize mineralized tissue protein extraction methodology and workflows for proteomic and data analyses of small quantities of healthy young adult human alveolar bone. Osteoid was solubilized by GuHCl extraction, with hydroxyapatite-bound proteins then released by ethylenediaminetetraacetic acid demineralization. A subsequent GuHCl solubilization extraction was followed by solid-phase digestion of the remaining insoluble cross-linked protein using trypsin and then 6 M urea dissolution incorporating LysC digestion. Bone extracts were digested in parallel using trypsin, LysargiNase, AspN, or GluC prior to liquid chromatography-mass spectrometry analysis. Terminal Amine Isotopic Labeling of Substrates was used to purify semitryptic peptides, identifying natural and proteolytic-cleaved neo N-termini of bone proteins. Our strategy enabled complete solubilization of the organic bone matrix leading to extensive categorization of bone proteins in different bone matrix extracts, and hence matrix compartments, for the first time. Moreover, this led to the high confidence identification of pannexin-3, a "missing protein", found only in the insoluble collagenous matrix and revealed for the first time by trypsin solid-phase digestion. We also found a singleton proteotypic peptide of another missing protein, meiosis inhibitor protein 1. We also identified 17 proteins classified in neXtprot as PE1 based on evidence other than from MS, termed non-MS PE1 proteins, including ≥9-mer proteotypic peptides of four proteins.

LC-HRMS Screening and Identification of Novel Peptide Markers of Ricin Based on Multiple Protease Digestion Strategies.

Both ricin and R. communis agglutinin (RCA120), belonging to the type II ribosome-inactivating proteins (RIPs-Ⅱ), are derived from the seeds of the castor bean plant. They share very similar amino acid sequences, but ricin is much more toxic than RCA120. It is urgently necessary to distinguish ricin and RCA120 in response to public safety. Currently, mass spectrometric assays are well established for unambiguous identification of ricin by accurate analysis of differentiated amino acid residues after trypsin digestion. However, diagnostic peptides are relatively limited for unambiguous identification of trace ricin, especially in complex matrices. Here, we demonstrate a digestion strategy of multiple proteinases to produce novel peptide markers for unambiguous identification of ricin. Liquid chromatography-high resolution MS (LC-HRMS) was used to verify the resulting peptides, among which only the peptides with uniqueness and good MS response were selected as peptide markers. Seven novel peptide markers were obtained from tandem digestion of trypsin and endoproteinase Glu-C in PBS buffer. From the chymotrypsin digestion under reduction and non-reduction conditions, eight and seven novel peptides were selected respectively. Using pepsin under pH 1~2 and proteinase K digestion, six and five peptides were selected as novel peptide markers. In conclusion, the obtained novel peptides from the established digestion methods can be recommended for the unambiguous identification of ricin during the investigation of illegal use of the toxin.

Future trends and strategies of recycling high-tech metals from urban mines in China: 2015–2050

High-tech metals are necessary materials for strategic emerging industries but their primary ores are generally difficult to be extracted because of economic and technical limitations. Urban mines have become a potential pool of secondary high-tech metals, called high-tech urban mines (HUMs). It is important and urgent to make a dynamic evaluation to understand the potential and technical feasibility for HUMs development. In this study, we construct the strategic development index (SDI) from three aspects - resource, technology, and environmental (R-T-E) to assess HUMs in China from 2015 to 2050. Furthermore, development strategies are proposed based on the dynamic evaluation results. Here we show that, there are four patterns of future trends of HUMs in China - sustainable growth, first increase and then decrease, continuous decline, and fading out. The distribution of HUMs in “R-T-E” shows a trend of polarization with continuously shrinks of the range along all the three indexes. According to the evaluation results, different strategies - key development strategy, digestion strategy, reserve strategy and transfer strategy - should be adopted to develop HUMs. Wind turbines, fluorescence lamps, smartphones, EVs, Li-ion batteries and computers will be main reservoirs of secondary high-tech metals for a long time, they should be the focus of technology, funds and policy from both the government and enterprises.

The rumen washes off abrasives before heavy-duty chewing in ruminants

Based on comparative mandibular anatomy, observations of chewing behaviour, chewing forces and dental microwear, it has been suggested that an additional effect of the ruminant digestive strategy could be a reduction of both the required chewing load and tooth wear ruminants are exposed to. This effect is hypothesized to be the result of digestion, mixing, and digesta sorting prior to regurgitation for rumination, which might both soften the material and wash off external abrasives such as sand, grit and dust. Putatively, these external abrasives would thus be trapped in the (fore)stomach and excreted via the faeces. We investigated the location of sand in the stomach of goats fed diets containing phytoliths and sand for several months. The contents of the stomach section from where rumination material is recruited were comparatively depleted of sand. Sand mainly accumulated in another stomach section, the abomasum, without causing clinical problems. A certain phytolith content should hence affect ruminants and non-ruminant herbivores somewhat alike; however, a certain external abrasives content should affect ruminants less than non-ruminants. Results from feeding experiments as well as tooth wear studies support this hypothesis, and caution against the default use of dental anatomy and wear as taxon-free environmental proxies in paleobiology.

Quantitative Analysis of Protein Covalent Labeling Mass Spectrometry Data in the Mass Spec Studio.

Covalent labeling with mass spectrometry (CL-MS) provides a direct measure of the chemical and structural features of proteins with the potential for resolution at the amino-acid level. Unfortunately, most applications of CL-MS are limited to narrowly defined differential analyses, where small numbers of residues are compared between two or more protein states. Extending the utility of high-resolution CL-MS for structure-based applications requires more robust computational routines and the development of methodology capable of reporting of labeling yield accurately. Here, we provide a substantial improvement in the analysis of CL-MS data with the development of an extended plug-in built within the Mass Spec Studio development framework (MSS-CLEAN). All elements of data analysis-from database search to site-resolved and normalized labeling output-are accommodated, as illustrated through the nonselective labeling of the human kinesin Eg5 with photoconverted 3,3'-azibutan-1-ol. In developing the new features within the CL-MS plug-in, we identified additional complexities associated with the application of CL reagents, arising primarily from digestion-induced bias in yield measurements and ambiguities in site localization. A strategy is presented involving the use of redundant site labeling data from overlapping peptides, the imputation of missing data, and a normalization routine to determine relative protection factors. These elements together provide for a robust structural interpretation of CL-MS/MS data while minimizing the over-reporting of labeling site resolution. Finally, to minimize bias, we recommend that digestion strategies for the generation of useful overlapping peptides involve the application of complementary enzymes that drive digestion to completion.

Proteomics reveals the in vitro protein digestibility of seven transmembrane enzymes from the docosahexaenoic acid biosynthesis pathway

The measurement of protein digestibility is one of the key steps in determining the safety of a genetically modified crop that has been traditionally accomplished using antibodies. Membrane proteins are often extremely difficult to express with replicated authentic tertiary structure in heterologous systems. As a result raising antibodies for use in safety assessment may not be feasible. In this study, LC-MS based proteomics was used to characterise seven transmembrane enzymes from the docosahexaenoic acid biosynthetic pathway that had been introduced into canola. The application of a two-stage digestion strategy involving simulated gastric fluid followed by trypsin enabled the measurement of protein digestibility in vitro. Tryptic peptide markers that spanned the length of each desaturase protein were monitored and showed that these proteins were readily degraded (>95% within 5 min) and highlighted regions of the elongase enzymes that showed limited resistance to simulated gastric digestion. Traditional gel-based and Western blotting analysis of ω3-desaturase and Δ6-elongase revealed rapid hydrolysis of the intact proteins within seconds and no fragments (>3 kDa) remained after 60 min, complementing the novel approach described herein. The LC-MS approach was sensitive, selective and did not require the use of purified proteins.

Sustainable waste management through synergistic utilisation of commercial and domestic organic waste for efficient resource recovery and valorisation in the UK

The UK is facing tremendous challenges in tackling food waste diversion from landfill. Whilst much effort has been made to prevent food waste, there is still a lack of attention and strategic approach in dealing with resource recovery and valorisation of food waste. This paper presents a systematic framework for sustainable organic waste management and valorisation in the UK through (i) review of current policy framework; (ii) analysis of resource recovery potential from food waste at national, community and organisational levels; (iii) proposition of alternative waste management strategies; and (iv) examination of challenges and opportunities with respect to economic, environment and social dimensions of sustainability of waste management strategies. The paper explores valorisation of source-segregated food waste and mixed waste from the supermarket and households into electricity and transportation fuels, through partially and completely decentralised configurations using anaerobic digestion and gasification technologies. This study demonstrates a potential for reducing the cost of electricity and greenhouse gas emissions of one supermarket store by 12% when adopting partially decentralised food waste anaerobic digestion strategy, and full substitution of fossil fuel based electricity with net surplus renewable electricity generation through complete decentralisation of mixed waste gasification. Therefore, a more integrated, circular and advanced technological approach in waste management should be undertaken as it can lead to a wider range of socio-economic and environmental advantages to the local community, highly essential in the UK.