Digestion Of Meal Research Articles

Investigating effects of dietary protein manipulation and Ulva lactuca supplementation on the postprandial metabolism and nitrogen excretion of Australian hybrid abalone

Abalone diets continue to be refined to suit the physiological and macronutrient requirements of different aged abalone under various seasonal conditions, primarily through dietary protein manipulation. Recently, dietary macro-algae supplementation has gained interest as an promoter of health and growth in abalone. In this study, the effects of three graded levels of dietary protein (35, 41 and 47 %) and 15 % dietary supplementation of dried and ground Ulva lactuca on the digestion and excretion processes in juvenile Australian hybrid abalone (Haliotis rubra x H. laevigata) were investigated through analysis of metabolic oxygen consumption (ṀO2) and nitrogen excretion (ṀNH4+−N) during meal digestion and assimilation. Trials were conducted at three farm-relevant acclimation temperatures (12, 17 and 22 °C), and abalone acclimated to the highest temperature were additionally subjected to a simulated heatwave. Within the ranges of 35 and 47 % dietary crude protein, no differences were observed in total postprandial energy use, however, significant differences were observed between the three temperatures. Similarly, differences in nitrogen excretion were observed across temperatures but not across dietary protein treatments. Dietary supplementation of U. lactuca led to significantly higher peak and total ṀO2 throughout the postprandial period at 22 °C. Additionally, total NH4+−N excretion was higher at 17 °C when abalone were fed the U. lactuca supplemented diet. No differences in survival were observed between any of the dietary treatments when juvenile abalone underwent the simulated heatwave, however, the 15 % U. lactuca treatment did exhibit consistently higher ṀO2. This information is useful for abalone farmers and feed formulators in developing season-specific diet formulations, particularly regarding macro-algae supplementation.

Influence of Various Methods of Processing Soybeans on Protein Digestibility and Reduction of Nitrogen Deposits in the Natural Environment – A Review

Abstract Soybean meal (SBM) is a significant source of protein for poultry due to its high concentration of protein and amino acids profile. The primary objective of SBM processing is the reduction and deactivation of anti-nutritional factors (ANFs) to enhance nutrient digestibility. However, eliminating ANFs does not necessarily correlate with increased protein and amino acid content. Several processing methods, such as soaking, cooking, and commercial techniques, improve SBM protein digestibility. To sustain feeding qualities, soybeans must undergo heating to remove inherent chemicals that interfere with poultry digestion. However, both under and over-processing can impair meal digestibility. Extrusion heating significantly contributes to protein and starch digestibility while reducing certain ANFs. Thermomechanical and enzyme-assisted procedures reduce heat-resistant proteins more efficiently than extraction methods, producing soy protein concentrate (SPC) and fermentation. These techniques reduce ANFs in SBM, activating digestive enzymes and alleviating digestive tract pressure, leading to decreased endogenous protein deficits. Exogenous enzyme supplementation is a biotechnological approach for enhancing the nutritional content of SBM and certain other protein-rich products. However, different processing methods not only affect protein digestibility but also impact poultry production, gastrointestinal health, and the environment due to higher nitrogen excrement. Ammonia (NH3) emissions are a significant environmental concern in chicken farming, resulting from uric acid production during protein consumption. It has a negative impact on the environment and the health of birds/humans. This review investigates the impact of several processing techniques on the digestibility of SBM protein and the reduction of N2 regarding one health concept. Future research should focus on identifying optimal processing methods maximizing protein digestibility while minimizing environmental nitrogen impacts.

A cell atlas of the adult female Aedes aegypti midgut revealed by single-cell RNA sequencing

Aedes aegypti is a primary vector for transmitting various arboviruses, including Yellow fever, dengue and Zika virus. The mosquito midgut is the principal organ for blood meal digestion, nutrient absorption and the initial site of arbovirus infection. Although a previous study delineated midgut’s transcriptome of Ae. aegypti at the single-nucleus resolution, there still lacks an established protocol for isolating and RNA sequencing of single cells of Ae. aegypti midgut, which is required for investigating arbovirus-midgut interaction at the single-cell level. Here, we established an atlas of the midgut cells for Ae. aegypti by single-cell RNA sequencing. We annotated the cell clusters including intestinal stem cells/enteroblasts (ISC/EB), cardia cells (Cardia), enterocytes (EC, EC-like), enteroendocrine cells (EE), visceral muscle (VM), fat body cells (FBC) and hemocyte cells (HC). This study will provide a foundation for further studies of arbovirus infection in mosquito midgut at the single-cell level.

A fluorescently-tagged tick kinin neuropeptide triggers peristalsis and labels tick midgut muscles

Ticks are blood-feeding arthropods that require heme for their successful reproduction. During feeding they also acquire pathogens that are subsequently transmitted to humans, wildlife and/or livestock. Understanding the regulation of tick midgut is important for blood meal digestion, heme and nutrient absorption processes and for aspects of pathogen biology in the host. We previously demonstrated the activity of tick kinins on the cognate G protein-coupled receptor. Herein we uncovered the physiological role of the kinin receptor in the tick midgut. A fluorescently-labeled kinin peptide with the endogenous kinin 8 sequence (TMR-RK8), identical in the ticks Rhipicephalus microplus and R. sanguineus, activated and labeled the recombinant R. microplus receptor expressed in CHO-K1 cells. When applied to the live midgut the TMR-RK8 labeled the kinin receptor in muscles while the labeled peptide with the scrambled-sequence of kinin 8 (TMR-Scrambled) did not. The unlabeled kinin 8 peptide competed TMR-RK8, decreasing confocal microscopy signal intensity, indicating TMR-RK8 specificity to muscles. TMR-RK8 was active, inducing significant midgut peristalsis that was video-recorded and evaluated with video tracking software. The TMR-Scrambled peptide used as a negative control did not elicit peristalsis. The myotropic function of kinins in eliciting tick midgut peristalsis was established.

Searching for new molecules involved in Anopheles mosquitoes' response to Plasmodium infection.

Plasmodium parasites within mosquitoes are exposed to various physiological processes, such as blood meal digestion activity, the gonotrophic cycle, and host responses preventing the entry of parasites into the midgut wall. However, when in vitro-cultured ookinetes are injected into the hemocoel of mosquitoes, Plasmodium parasites are not affected by the vertebrate host's blood contents and do not pass through the midgut epithelial cells. This infection method might aid in identifying mosquito-derived factors affecting Plasmodium development within mosquitoes. This study investigated novel mosquito-derived molecules related to parasite development in Anopheles mosquitoes. We injected in vitro-cultured Plasmodium berghei (ANKA strain) ookinetes into female and male Anopheles stephensi (STE2 strain) mosquitoes and found that the oocyst number was significantly higher in males than in females, suggesting that male mosquitoes better support the development of parasites. Next, RNA-seq analysis was performed on the injected female and male mosquitoes to identify genes exhibiting changes in expression. Five genes with different expression patterns between sexes and greatest expression changes were identified as being potentially associated with Plasmodium infection. Two of the five genes also showed expression changes with infection by blood-feeding, indicating that these genes could affect the development of Plasmodium parasites in mosquitoes.

In vitro bioaccessibility and intestinal transport of retinoic acid in ethyl cellulose-based microparticles and impact of meal co-ingestion

The development of carrier-based delivery systems for oral administration of retinoic acid (RA), that provides its release and absorption at intestinal level, is of major relevance in the treatment of acute promyelocytic leukemia. The aim of this work was to evaluate RA bioaccessibility and intestinal transport on ethyl cellulose (EC)- and EC + polyethylene glycol (ECP)-based microparticles and to understand the impact of meal co-ingestion by applying in vitro assays. RA-loaded microparticles were produced by spray-drying with an encapsulation efficiency higher than 90 % for both formulations. The gastric bioaccessibility of RA (after in vitro static digestion of RA-loaded particles) was lower than 3 % for both types of microparticles, with and without meal co-ingestion. Whereas after intestinal digestion, RA bioaccessibility was significantly higher and affected by the type of microparticles and the presence of meal. The digestion of EC- and ECP-based microparticles without diet enabled a significantly higher bioaccessibility of RA when compared to the one recorded for the co-digestion of these microparticles with diet. Herein, RA bioaccessibility decreased from 84 ± 1 to 24 ± 6 % (p < 0.0001) for microparticles EC and 54 ± 4 to 25 ± 5 % (p < 0.001) for microparticles ECP. Moreover, comparing both types of microparticles, RA bioaccessibility was significantly higher for EC-based microparticles digested without diet (p < 0.0001). At last, the bioaccessibility of RA was similar among EC- and ECP-based microparticles when co-digested with diet. Intestinal transport experiments performed in Caco-2 monolayers evidenced that after 2 h of transport the amount of RA retained in the apical compartment was higher than the amount that reached the basolateral compartment evidencing a slow transport at intestinal level that was higher when RA is spiked in the blank of digestion and the meal digestion samples compared to RA dissolved in HBSS (44 ± 6 (p < 0.01) and 38 ± 1 (p < 0.05) vs 26 ± 2 %, respectively).

Dual effects of dietary carnosine during in vitro digestion of a Western meal model with added ascorbic acid.

The beneficial role of carnosine during in vitro digestion of meat was previously demonstrated, and it was hypothesized that such benefits could also be obtained in a meal system. The current study, therefore, assessed carnosine effects on markers of lipid and protein oxidation and of advanced glycation end products (AGEs) during gastric and duodenal in vitro digestion of a burger meal model. The model included intrinsic (low) and enhanced (medium and high) carnosine levels in a mix of pork mince and bread, with or without ascorbic acid (AA) and/or fructose as anti- and prooxidants, respectively. In the presence of either AA or fructose, a carnosine prooxidative potential during digestion was observed at the medium carnosine level depending on markers and digestive phases. However, free carnosine found at the high carnosine level exerted a protective effect reducing the formation of 4-hydroxynonenal in the gastric phase and glyoxal in both the gastric and duodenal phases. Dual effects of carnosine are likely concentration related, whereby at the medium level, free radical production increases through carnosine's ferric-reducing capacity, but there is insufficient quantity to reduce the resulting oxidation, while at the higher carnosine level some decreases in oxidation are observed. In order to obtain carnosine benefits during meal digestion, these findings demonstrate that consideration must be given to the amount and nature of other anti- and prooxidants present and any potential interactions. PRACTICAL APPLICATION: Carnosine, a natural compound in meat, is a multifunctional and beneficial molecule for health. However, both pro- and antioxidative effects of carnosine were observed during digestion of a model burger meal when ascorbic acid was included at a supplemental level. Therefore, to obtain benefits of dietary carnosine during digestion of a meal, consideration needs to be given to the amount and nature of all anti- and prooxidants present and any potential interactions.

The Elusive Hypertrophy of the Python Heart.

The Burmese python, one of the world's largest snakes, has reached celebrity status for its dramatic physiological responses associated with digestion of enormous meals. The meals elicit a rapid gain of mass and function of most visceral organs, particularly the small intestine. There is also a manyfold elevation of oxygen consumption that demands the heart to deliver more oxygen. It therefore made intuitive sense when it was reported that the postprandial response entailed a 40% growth of heart mass that could accommodate a rise in stroke volume. Many studies, however, have not been able to reproduce the 40% growth of the heart. We collated published values on postprandial heart mass in pythons, which include several instances of no change in heart mass. On average, the heart mass is only 15% greater. The changes in heart mass did not correlate to the mass gain of the small intestine or peak oxygen consumption. Hemodynamic studies show that the rise in cardiac output does not require increased heart mass but can be fully explained by augmented cardiac filling and postprandial tachycardia. Under the assumption that hypertrophy is a contingent phenomenon, more recent experiments have employed two interventions such as feeding with a concomitant reduction in hematocrit. The results suggest that the postprandial response of the heart can be enhanced, but the 40% hypertrophy of the python heart remains elusive.

Forensic analysis of mosquito blood meal digestion process and the impact of heroin opiate: determination of the post-feeding interval as a PMI estimation.

Females of some mosquito species are anthropophilic, as they feed on human blood to support egg production and, hence, are forensically valuable if found at a crime scene. The present study investigated the blood meal digestion process in Culex pipiens L. both with and without heroin and proposed a method for estimating the post-feeding interval (PFI). Mosquitoes were fed on a control mouse, a heroin-injected mouse, or in vitro heroin-treated mouse blood. The blood meal digestion was then investigated at different hours post-feeding. Data showed that the blood meal size ingested by control mosquitoes was 0.681 ± 0.04 mg/mosquito and was completely digested within 45 h post-feeding. An estimation of the PFI was proposed in terms of the rate of hemoglobin (Hb) digestion. The blood meal size of the mosquitoes fed on the in vitro heroin-treated blood and the heroin-injected mouse was 0.96 ± 0.06 and 0.79 ± 0.01 mg/mosquito and was completely digested within 50 and 55 h post-feeding, respectively. The digestion of Hb started similarly in all experimental mosquitoes until 10 h post-feeding, after which it significantly decreased in heroin-treated blood meals compared with the control ones. This may suggest that heroin impacted the digestion process, as it took an extra 5-10 h to complete. These findings could be valuable in the forensic context since an estimation of PFI is proposed as a potential estimation of the postmortem interval (PMI). However, care should be taken as heroin in the host blood has significantly impacted the overall digestion process and, hence, may bias the PFI/PMI estimation.

Mechanism of the toxic effects of tetracycline on blood meal digestion in Haemaphysalis longicornis.

The extensive utilization of antibiotics in the field of animal husbandry gives rise to various concerns pertaining to the environment and human health. Here, we demonstrate that the administration of tetracycline impedes blood meal digestion in the tick Haemaphysalis longicornis. Tissue sectioning, 16S rRNA high-throughput sequencing, and transcriptome sequencing of the midgut were employed to elucidate the mechanism underlying tetracycline toxicity. The treatment group consisted of engorged female ticks that were subjected to tetracycline microinjections (75µg per tick), whereas the control group received sterile water injections. On days 2 and 4 following the injections, the tick body weight changes were assessed and the midguts were dissected and processed. Change in tick body weight in tetracycline-treated group was less than in the control group. In tetracycline-treated ticks, midgut epithelial cells were loosely connected and blood meal digestion was impaired compared to the control group. There was no significant change in midgut bacterial diversity after tetracycline treatment. On day 2 following treatment, the relative abundance of Escherichia-Shigella was significantly decreased, whereas the relative abundance of Allorhizobium was significantly increased compared to the control group. On day 4 following treatment, the relative abundance of Escherichia-Shigella, Allorhizobium, Ochrobactrum, and Acidibacter decreased significantly, whereas the relative abundance of Paraburkholderia and Pelomonas increased significantly. Tetracycline treatment also affected midgut gene expression, producing a cumulative effect wherein the differentially expressed genes (DEGs) were mostly down-regulated. KEGG enrichment pathway analysis revealed that on day 2 the up-regulated DEGs were significantly enriched in 21 pathways, including apoptosis and phagosome. Comparatively, the down-regulated DEGs were significantly enriched in 26 pathways, including N-glycan biosynthesis, lysosome, and autophagy. In contrast, on day 4 the up-regulated DEGs were significantly enriched in 10 pathways including aminoacyl-tRNA biosynthesis, ribosome biogenesis, RNA transport, and DNA replication, whereas the down-regulated differential genes were significantly enriched in 11 pathways including lysosome, peroxisome, N-glycan biosynthesis, and fatty acid synthesis. This indicates that tetracycline injection inhibited blood meal digestion by affecting midgut digestive cells, gut flora diversity, and gene expression. These findings could contribute to tick control by inhibiting blood meal digestion.

Gastroprotective Effect of Samudradya Churna wsr of Parinama Shula: A Classical Review

According to several researches on the number of cases of duodenal ulcers, these conditions are believed to affect 5 to 15% of the general population. While dyspepsia is among the most common accompanying symptom of duodenal ulcers, the presentation can range in severity, including gastrointestinal bleeding, gastric outlet obstruction, perforation, or fistula development. This whole entity compared as Parinama Shoola is an Avaranjanya Tridoshaja Vyadhi caused by Vata vitiation, which causes avarana in Kapha and Pitta. It worsens during meal digestion and 3-4 hours after food intake when it gets to the intestines. In modern science, there are drugs for symptomatic relief in the treatment of ulcers (Parinama Shula) that have severe adverse consequences over time. In the Current era, there is a critical need to protect the microbiota of the gut as well as digestive health through the use of Ayurvedic formulations both for preventive and therapeutic purposes. Finally, it is discussed the use of one of the Ayurveda Formulation “Samudradya Churna” with respect to its role in health and disease. This article reviews the indications, contraindications, pharmaceutical action, adverse events, and other key elements in the clinical setting as relates to the essential points.

Fate of Amadori compounds in processing and digestion of multi-ingredients tomato based sauces and their effect on other microconstituents

Amadori compounds (ACs), the first stable products of Maillard reaction, are detected in various products of fruits and vegetables, and show an antioxidant activity which can be related to beneficial effects in human health. In order to optimize the nutritional quality of a multi-ingredient tomato sauce (tomato puree – onion – olive oil – dried pepper), the fate of ACs during processing (drying, heating) and gastrointestinal digestion of a model meal was assessed as well as that of other microconstituents, i.e. carotenoids, phenolic compounds and capsaicinoids. The drying at 50 °C of fresh pepper induced the formation and accumulation of ACs after 6 days. During the heat treatment by microwave of multi-ingredient tomato sauce, Maillard reaction occurs in presence of dried pepper and the content in ACs in the tomato-based sauces increased (+33% to + 53%) depending of quantities of dried pepper added. The bioaccessibility of total ACs was 24–31% in duodenal phase and 18–22% in jejunal phase. Individual ACs have shown variable bioaccessibility, e.g. very high for Fru-Arg (50.8% to 71.3%), and very low for Fru-Met (1.8% to 2.2%). The kinetic monitoring of ACs in digestion medium showed that ACs are not stable (-46% in gastric phase, −49 % in intestinal phase) which indicated their potential degradation in the digestive tract. The presence of ACs in the multi-ingredients tomato sauces had no effect on the content of the other bioactive compounds monitored in the study and even promoted the bioaccessibility of total lycopene (+30%) but decreased the bioaccessibility of total phenolic compounds.

Host Associations of Culicoides Biting Midges in Northeastern Kansas, USA.

Culicoides biting midges (Diptera: Ceratopogonidae) are hematophagous flies that transmit several viruses of veterinary concern to livestock. Understanding blood feeding behaviors is integral towards identification of putative vector species and preventing the transmission of these pathogens. PCR-based blood meal analysis was conducted on 440 blood-engorged Culicoides midges collected in northeastern Kansas, with 316 (71.8%) returning non-human vertebrate identifications at the ≥95% identity match level. Broadly, Culicoides sonorensis, Culicoides stellifer, and Culicoides variipennis were found to feed heavily on mammalian hosts, while Culicoides crepuscularis and Culicoides haematopotus fed on avian hosts. The blood meals in all specimens were graded prior to DNA extraction to determine whether blood meal size or digestion status significantly impacted the likelihood of a quality host match. Size had a significant impact on the likelihood of a quality match at grades 3-5, whereas digestion only significantly impacted outcomes at the most extreme grade. These vector-host dynamics have not previously been studied in Culicoides collected in Kansas, which represents a unique tallgrass prairie biome within the United States that is heavily interspersed with livestock operations. Based on these data, the highly abundant species C. crepuscularis and C. haematopotus are unlikely to be major vectors of mammalian viruses.

Gene identification and RNAi-silencing of p62/SQSTM1 in the vector Rhodnius prolixus reveals a high degree of sequence conservation but no apparent deficiency-related phenotypes in vitellogenic females.

Autophagy and the ubiquitin-proteasome system (UPS) are important cellular mechanisms that coordinate protein degradation essential for proteostasis. P62/SQSTM1 is a receptor cargo protein able to deliver ubiquitinated targets to the proteasome proteolytic complex and/or to the autophagosome. In the insect vector of Chagas disease, Rhodnius prolixus, previous works have shown that the knockdown of different autophagy-related genes (ATGs) and ubiquitin-conjugating enzymes resulted in abnormal oogenesis phenotypes and embryo lethality. Here, we investigate the role of the autophagy/UPS adaptor protein p62 during the oogenesis and reproduction of this vector. We found that R. prolixus presents one isoform of p62 encoded by a non-annotated gene. The predicted protein presents the domain architecture anticipated for p62: PB1 (N-term), ZZ-finger, and UBA (C-term) domains, and phylogenetic analysis showed that this pattern is highly conserved within insects. Using parental RNAi, we found that although p62 is expressed in the ovary, midgut, and fat body of adult females, systemic silencing of this gene did not result in any apparent phenotypes under in-house conditions. The insects' overall levels of blood meal digestion, lifespan, yolk protein production, oviposition, and embryo viability were not altered when compared to controls. Because it is known that autophagy and UPS can undergo compensatory mechanisms, we asked whether the silencing of p62 was triggering adaptative changes in the expression of genes of the autophagy, UPS, and the unfolded protein response (UPR) and found that only ATG1 was slightly up regulated in the ovaries of silenced females. In addition, experiments to further investigate the role of p62 in insects previously silenced for the E1-conjugating enzyme (a condition known to trigger the upregulation of p62), also did not result in any apparent phenotypes in vitellogenic females.

A longitudinal transcriptomic analysis from unfed to post-engorgement midguts of adult female Ixodes scapularis

The hematophagy behavior has evolved independently several times within the Arthropoda phylum. Interestingly, the process of acquiring a blood meal in ticks is considerably distinct from that observed in other blood-feeding arthropods. Instead of taking seconds to minutes to complete a blood meal, an adult female Ixodes scapularis tick can remain attached to its host for numerous days. During this extended feeding period, the tick undergoes drastic morphological changes. It is well established that the tick midgut plays a pivotal role not only in blood meal digestion but also in pathogen acquisition and transmission. However, our understanding of the underlying molecular mechanisms involved in these events remains limited. To expedite tick research, we conducted a comprehensive longitudinal RNA-sequencing of the tick midgut before, during, and after feeding. By collecting ticks in different feeding stages (unfed, slow feeding, rapid feeding, and early post-detached), we obtained a comprehensive overview of the transcripts present in each stage and the dynamic transcriptional changes that occur between them. This provides valuable insights into tick physiology. Additionally, through unsupervised clustering, we identified transcripts with similar patterns and stage-specific sequences. These findings serve as a foundation for selecting targets in the development of anti-tick control strategies and facilitate a better understanding of how blood feeding and pathogen infection impact tick physiology.

Why do some fish grow faster than others?

AbstractAll animals must acquire food to grow, but there is a vast diversity in how different species and even different individuals approach and achieve this task. Individuals within a species appear to fall along a bold‐shy continuum, whereby some fish acquire food aggressively and with seemingly high risk, while others appear more submissive and opportunistic. Greater food consumption generally results in faster growth, but only if the energy acquired through food is more than enough to compensate for heightened metabolism associated with a more active lifestyle. Fast‐growing phenotypes also tend to have elevated baseline metabolism – at least when food is plentiful – which may be linked with gut morphology and digestive efficiency. The net energy gained from a meal (as calculated from the specific dynamic action (SDA) coefficient) is optimised with larger meal sizes, but the digestion of large meals can erode the aerobic metabolic scope available for other critical activities such as predator avoidance, perhaps at an interindividual level. Thus, complex interactions between an individual's genes and environment are likely to regulate the growth phenotype. This review compiles available knowledge to shed light on the question: Why do some fish grow faster than others? We discuss the elaborate interrelationships between behaviour, physiology and the gut microbiome with a goal to better understand what drives interindividual differences in growth performance.

Contaminated meal intake (Aeromonas hydrophila) does not elicit hormonal or immune modulation in bullfrogs (Lithobates catesbeianus).

The gastrointestinal tract (GIT) is colonized by resident microbiota but contact with foreign microbiota during feeding can impair GIT functions. During meal digestion, several vertebrates modulate the systemic immune function and immunoregulatory hormones concentration. However, in ectothermic animals, it is not known if this hormonal and immune modulation during the postprandial period is affected by the presence of pathogenic microbiota in the food. This study aimed to investigate the effects of contaminated meal ingestion on hormonal and innate immune responses in bullfrogs (Lithobates catesbeianus). Bullfrogs were divided into three treatments: fed three times with sterilized fish feed (control group), fed twice with sterilized fish feed and once with fish feed containing live bacteria (Aeromonas hydrophila, 109 UFC/mL), and fed three times with fish feed containing live bacteria. Blood and GIT tissues were collected 24 h after treatments to measure plasma and tissue corticosterone levels, NL ratio, and plasma bacterial killing ability. The ingestion of contaminated meal did not affect the hormonal and immune parameters. In conclusion, ingestion of contaminated food was not capable of intensifying the hypothalamic-pituitary-interrenal axis activation and the consequent hormonal and immune responses observed after feeding in bullfrogs. However, our results suggest that the ingestion of three contaminated meals tended to decrease stomach corticosterone levels (nonstatistically significant), possibly contributing to preventing the transmigration of the bacteria to organs outside the GIT.

Microbial inulinase promotes fructan hydrolysis under simulated gastric conditions.

Fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) have emerged as key contributors to digestive discomfort and intolerance to certain vegetables, fruits, and plant-based foods. Although strategies exist to minimize FODMAP consumption and exposure, exogenous enzyme supplementation targeting the fructan-type FODMAPs has been underexploited. The objective of this study was to test the hydrolytic efficacy of a food-grade, non-genetically engineered microbial inulinase preparation toward inulin-type fructans in the INFOGEST in vitro static simulation of gastrointestinal (GI) digestion. Purified inulin was shown to undergo acid-mediated hydrolysis at high gastric acidity as well as predominantly inulinase-mediated hydrolysis at lower gastric acidity. Inulinase dose-response simulations of inulin, garlic, and high-fructan meal digestion in the gastric phase suggest that as little as 50 inulinase units (INU) and up to 800 INU per serving promote fructan hydrolysis better than the control simulations without inulinase. Liquid chromatography-mass spectrometry (LC-MS) profiling of fructo-oligosaccharides (FOS) in the gastric digestas following inulinase treatment confirms the fructolytic activity of inulinase under simulated digestive conditions. Altogether, these in vitro digestion data support the use of microbial inulinase as an exogenous enzyme supplement for reducing dietary fructan-type FODMAP exposure.

Blood meal digestion and changes in lipid reserves are associated with the post-ecdysis development of the flight muscle and ovary in young adults of Rhodnius prolixus

Rhodnius prolixus is a hemimetabolous, hematophagous insect, and both nymphs and adults feed exclusively on blood. The blood feeding triggers the molting process and, after five nymphal instar stages, the insect reaches the winged adult form. After the final ecdysis, the young adult still has a lot of blood in the midgut and, thus, we have investigated the changes in protein and lipid contents that are observed in the insect organs as digestion continues after molting. Total midgut protein content decreased during the days after the ecdysis, and digestion was finished fifteen days later. Simultaneously, proteins and triacylglycerols present in the fat body were mobilized, and their contents decreased, whereas they increased in both the ovary and the flight muscle. In order to evaluate the activity of de novo lipogenesis of each organ, the fat body, ovary and flight muscle were incubated in the presence of radiolabeled acetate, and the fat body showed the highest efficiency rate (around 47%) to convert the taken up acetate into lipids. The levels of de novo lipid synthesis in the flight muscle and ovary were very low. When 3H-palmitate was injected into the young females, its incorporation by the flight muscle was higher than by the ovary or the fat body. In the flight muscle, the 3H-palmitate was similarly distributed amongst triacylglycerols, phospholipids, diacylglycerols and free fatty acids, while in the ovary and fat body it was mostly found in triacylglycerols and phospholipids. The flight muscle was not fully developed after the molt, and at day two no lipid droplets were observed. At day five, very small lipid droplets were present, and they increased in size up to day fifteen. The diameter of the muscle fibers also increased from day two to fifteen, as well as the internuclear distance, indicating that muscle hypertrophy occurred along these days. The lipid droplets from the fat body showed a different pattern, and their diameter decreased after day two, but started to increase again at day ten. The data presented herein describes the development of the flight muscle after the final ecdysis, and modifications that occur regarding lipid stores. We show that, after molting, substrates that are present in the midgut and fat body are mobilized and directed to the ovary and flight muscle, for the adults of R. prolixus to be ready to feed and reproduce.

EIF3 subunit M regulates blood meal digestion in Rhodnius prolixus affecting ecdysis, reproduction, and survival.

In triatomines, blood-feeding triggers many physiological processes including post embryonic development and reproduction. Different feeding habits, such as hematophagy, can shape gene functions to meet the challenges of each type of diet. The gut of blood-sucking insects faces particular challenges after feeding due to the quantity and the quality of the food ingested. A comparison of transcriptomic and proteomic data indicates that post transcriptional regulation of gene expression is crucial in the triatomine gut. It was proposed that eukaryotic translation initiation factor 3 subunit m (eIF3m) and eIF3e define 2 different eIF3 complexes with a distinct affinity for the different mRNAs, thus selecting the set of mRNAs to be translated and constituting a post transcriptional mode of regulation of gene expression. Because the eIF3m is mainly expressed in the gut, we evaluated its relevance in Rhodnius prolixus physiology through RNA interference-mediated gene silencing. The knockdown of eIF3m reduced the digestion rate, affecting the processes triggered by a blood meal. Its silencing inhibited molting and caused premature death in nymphs while impaired ovary development, oviposition and increased resistance to starvation in adult females. The survival of males after feeding (resistance to starvation) was not affected by eIF3m knockdown. The information regarding the eIF3m function in insects is scarce and the phenotypes observed in R. prolixus upon eIF3m silencing are different and more severe than those previously described in Drosophila melanogaster, indicating a pleiotropic role of this gene in triatomines.