Organ growth and fermentation profiles of broilers differing in body growth rate.

This study sought to determine the relationship among broiler performance, organ development, and indicators of microbiota colonization. A total of 1,200 two-day-old male Ross 308 broiler chicks, divided among 3 cohorts of equal size, were housed in battery cages, and allotted based on body weight. On study d 11, birds were weighed, and birds with BW gain within the 10th and 90th percentiles were assigned to the Slow and Fast groups, respectively. Birds (n = 30 for each group) selected on d 11 were provided water and a corn-soybean meal-based diet ad libitum while maintained individually through study d 25 (i.e., a 14-d growth period). Parameters regarding growth performance, organ and intestine weights and lengths, and intestinal volatile fatty acid concentrations were measured. All data were analyzed by one-way ANOVA using the Mixed procedure of SAS. Fast birds exhibited greater (P < 0.001) BW gain and feed intake than slow birds, but feed conversion ratio (FCR) did not differ (P = 0.19). Additionally, Slow birds had higher (P < 0.05) relative weights (% of BW) for nearly all organs on d 11 and 25, most notably the gizzard, proventriculus, pancreas, and liver. Conversely, intestinal sections were longer (P < 0.05) in the Fast birds. Measurement of gut histomorphology did not show any notable differences between growth rate groups in terms of villi height, crypt depth, or their ratio for either time-point (P > 0.05). In terms of volatile fatty acid concentrations of luminal contents, acetate concentrations were 10.2% higher (P < 0.001) in the ileum of the Slow birds compared with Fast birds on d 25. Overall, the findings suggest that total BW gain is influenced by the development of metabolically active organs, as supported by lower weight gain in Slow birds with relatively larger organ weights and shorter intestinal lengths than their Fast counterparts. The general lack of differences in fermentation end-product concentrations in luminal contents does not rule out influence of the microbiota on growth rate of broilers, which warrants further investigation.

Temporal and spatial development of intestinal smooth muscle layers of human embryos and fetuses.

The sequential occurrence of three layers of smooth muscle layers (SML) in human embryos and fetus is not known. Here, we investigated the process of gut SML development in human embryos and fetuses and compared the morphology of SML in fetuses and neonates. The H&E, Masson trichrome staining, and Immunohistochemistry were conducted on 6-12 gestation week human embryos and fetuses and on normal neonatal intestine. We showed that no lumen was seen in 6-7th gestation week embryonic gut, neither gut wall nor SML was developed in this period. In 8-9th gestation week embryonic and fetal gut, primitive inner circular SML (IC-SML) was identified in a narrow and discontinuous gut lumen with some vacuoles. In 10th gestation week fetal gut, the outer longitudinal SML (OL-SML) in gut wall was clearly identifiable, both the inner and outer SML expressed α-SMA. In 11-12th gestation week fetal gut, in addition to the IC-SML and OL-SML, the muscularis mucosae started to develop as revealed by α-SMA immune-reactivity beneath the developing mucosal epithelial layer. Comparing with the gut of fetuses of 11-12th week of gestation, the muscularis mucosae, IC-SML, and OL-SML of neonatal intestine displayed different morphology, including branching into glands of lamina propria in mucosa and increased thickness. In conclusions, in the human developing gut between week-8 to week-12 of gestation, the IC-SML develops and forms at week-8, followed by the formation of OL-SML at week-10, and the muscularis mucosae develops and forms last at week-12.

Suspension culture promotes serosal mesothelial development in human intestinal organoids.

Pluripotent-stem-cell-derived human intestinal organoids (HIOs) model some aspects of intestinal development and disease, but current culture methods do not fully recapitulate the diverse cell types and complex organization of the human intestine and are reliant on 3D extracellular matrix or hydrogel systems, which limit experimental control and translational potential for regenerative medicine. We describe suspension culture as a simple, low-maintenance method for culturing HIOs and for promoting in vitro differentiation of an organized serosal mesothelial layer that is similar to primary human intestinal serosal mesothelium based on single-cell RNA sequencing and histological analysis. Functionally, HIO serosal mesothelium has the capacity to differentiate into smooth-muscle-like cells and exhibits fibrinolytic activity. An inhibitor screen identifies Hedgehog and WNT signaling as regulators of human serosal mesothelial differentiation. Collectively, suspension HIOs represent a three-dimensional model to study the human serosal mesothelium.

Dietary recombinant human lysozyme improves the growth, intestinal health, immunity and disease resistance of Pacific white shrimp Litopenaeus vannamei.

The present study was conducted to investigate the effects of dietary recombinant human lysozyme (RHL) on the growth, immune response, anti-oxidative activity, intestinal morphology, intestinal microflora and disease resistance of shrimp Litopenaeus vannamei. Shrimps with an initial body weight of 2.36 ± 0.02 g were fed diets supplemented with 0 (control group, R0), 0.0025% (R1), 0.005% (R2), 0.01% (R3), 0.02% (R4) and 0.04% (R5) of RHL, respectively. After a 10-week feeding trial, the final body weight, survival rate, weight gain ratio and protein efficiency rate of the shrimps in dietary RHL supplemented groups were significantly higher than that in the control group, while feed conversion ratio was significantly lower (P < 0.05). The total haemocyte count, total anti-oxidative capacity, respiratory burst, activities of phagocytosis, nitric oxide synthase, phenol oxidase and lysozyme in serum were significantly higher in dietary RHL supplemented groups than those in the control group (P < 0.05). Meanwhile, the intestinal pile height and wall thickness were significantly higher in dietary RHL supplemented groups than those in the control group (P < 0.05). Dietary RHL significantly improved the expressions of immune-related genes in gill, such as lipopolysaccharide-ß-glucan binding protein, Toll, immune deficiency, heat shock protein 70 and Crustin (P < 0.05). The abundance of proteobacteria and bacteroidetes in intestine was higher, while the abundance of firmicutes and cyanobacteria was lower than those in the control group at the phylum level. In addition, dietary RHL supplementation significantly improved the protective ability of shrimp against V. parahaemolyticus infection (P < 0.05). Based on the broken-line model analysis for weight gain ratio after the feeding trial, the optimal level of dietary RHL supplementation for shrimp was estimated to be 0.006375%.

Systematic expression profiling of neuropathy-related aminoacyl-tRNA synthetases in zebrafish during development.

Aminoacyl tRNA synthetases (ARSs) are a group of proteins, acting as transporters to transfer and attach the appropriate amino acids onto their cognate tRNAs for translation. So far, 18 out of 20 cytoplasmic ARSs are reported to be connected to different neuropathy disorders with multi-organ defects that are often accompanied with developmental delays. Thus, it is important to understand functions and impacts of ARSs at the whole organism level. Here, we systematically analyzed the spatiotemporal expression of 14 ars and 2 aimp genes during development in zebrafish that have not be previously reported. Not only in the brain, their dynamic expression patterns in several tissues such as in the muscles, liver and intestine suggest diverse roles in a wide range of development processes in addition to neuronal function, which is consistent with potential involvement in multiple syndrome diseases associated with ARS mutations. In particular, hinted by its robust expression pattern in the brain, we confirmed that aimp1 is required for the formation of cerebrovasculature by a loss-of-function approach. Overall, our systematic profiling data provides a useful basis for studying roles of ARSs during development and understanding their potential functions in the etiology of related diseases.

Intestinal upregulation and specific dynamic action in snakes - Implications for the 'pay before pumping' hypothesis.

Animals which feed infrequently and on large prey, like many snake species, are characterized by a high magnitude of gut upregulation upon ingesting a meal. The intensity of intestinal upregulation was hypothesized to be proportional to the time and energy required for food processing (Specific-Dynamic-Action; SDA); hence, a positive correlation between the scope of intestinal growth and SDA response can be deduced. Such a correlation would support the so far not well established link between the intestinal and metabolic consequences of digestion. In this study I tested this prediction using an interspecific dataset on snakes gleaned from published sources. I found that SDAduration and SDAscope were positively correlated with post-feeding factorial increase in small intestine mass, but not with microvillar elongation. This indicates that a wide range of whole intestine remodelling (up- but potentially also downregulation) may temporarily prolong meal processing and that a greater magnitude of intestinal growth requires a stronger metabolic elevation. However, these effects do not seem large enough to drive the variation in the entire energetic costs of digestion, because SDAexpenditure was not affected either by intestinal or microvillar growth. I therefore propose that intestinal upregulation elicits non-negligible costs, but that these costs are a fairly small component of the whole SDAexpenditure.

Term Infant Formulas Influencing Gut Microbiota: An Overview.

Intestinal colonization of the neonate is highly dependent on the term of pregnancy, the mode of delivery, the type of feeding [breast feeding or formula feeding]. Postnatal immune maturation is dependent on the intestinal microbiome implementation and composition and type of feeding is a key issue in the human gut development, the diversity of microbiome, and the intestinal function. It is well established that exclusive breastfeeding for 6 months or more has several benefits with respect to formula feeding. The composition of the new generation of infant formulas aims in mimicking HM by reproducing its beneficial effects on intestinal microbiome and on the gut associated immune system (GAIS). Several approaches have been developed currently for designing new infant formulas by the addition of bioactive ingredients such as human milk oligosaccharides (HMOs), probiotics, prebiotics [fructo-oligosaccharides (FOSs) and galacto-oligosaccharides (GOSs)], or by obtaining the so-called post-biotics also known as milk fermentation products. The aim of this article is to guide the practitioner in the understanding of these different types of Microbiota Influencing Formulas by listing and summarizing the main concepts and characteristics of these different models of enriched IFs with bioactive ingredients.

Endoderm development requires centrioles to restrain p53-mediated apoptosis in the absence of ERK activity.

Centrioles comprise the heart of centrosomes, microtubule-organizing centers. To study the function of centrioles in lung and gut development, we genetically disrupted centrioles throughout the mouse endoderm. Surprisingly, removing centrioles from the endoderm did not disrupt intestinal growth or development but blocked lung branching. In the lung, acentriolar SOX2-expressing airway epithelial cells apoptosed. Loss of centrioles activated p53, and removing p53 restored survival of SOX2-expressing cells, lung branching, and mouse viability. To investigate how endodermal p53 activation specifically killed acentriolar SOX2-expressing cells, we assessed ERK, a prosurvival cue. ERK was active throughout the intestine and in the distal lung buds, correlating with tolerance to centriole loss. Pharmacologically inhibiting ERK activated apoptosis in acentriolar cells, revealing that ERK activity protects acentriolar cells from apoptosis. Therefore, centrioles are largely dispensable for endodermal growth and the spatial distribution of ERK activity in the endoderm shapes the developmental consequences of centriolar defects and p53 activation.

Development and Functional Properties of Intestinal Mucus Layer in Poultry.

Intestinal mucus plays important roles in protecting the epithelial surfaces against pathogens, supporting the colonization with commensal bacteria, maintaining an appropriate environment for digestion, as well as facilitating nutrient transport from the lumen to the underlying epithelium. The mucus layer in the poultry gut is produced and preserved by mucin-secreting goblet cells that rapidly develop and mature after hatch as a response to external stimuli including environmental factors, intestinal microbiota as well as dietary factors. The ontogenetic development of goblet cells affects the mucin composition and secretion, causing an alteration in the physicochemical properties of the mucus layer. The intestinal mucus prevents the invasion of pathogens to the epithelium by its antibacterial properties (e.g. ß-defensin, lysozyme, avidin and IgA) and creates a physical barrier with the ability to protect the epithelium from pathogens. Mucosal barrier is the first line of innate defense in the gastrointestinal tract. This barrier has a selective permeability that allows small particles and nutrients passing through. The structural components and functional properties of mucins have been reviewed extensively in humans and rodents, but it seems to be neglected in poultry. This review discusses the impact of age on development of goblet cells and their mucus production with relevance for the functional characteristics of mucus layer and its protective mechanism in the chicken's intestine. Dietary factors directly and indirectly (through modification of the gut bacteria and their metabolic activities) affect goblet cell proliferation and differentiation and can be used to manipulate mucosal integrity and dynamic. However, the mode of action and mechanisms behind these effects need to be studied further. As mucins resist to digestion processes, the sloughed mucins can be utilized by bacteria in the lower part of the gut and are considered as endogenous loss of protein and energy to animal. Hydrothermal processing of poultry feed may reduce this loss by reduction in mucus shedding into the lumen. Given the significance of this loss and the lack of precise data, this matter needs to be carefully investigated in the future and the nutritional strategies reducing this loss have to be defined better.

Wnt/ß-catenin signaling pathway regulates cell proliferation but not muscle dedifferentiation nor apoptosis during sea cucumber intestinal regeneration.

Regeneration is a key developmental process by which organisms recover vital tissue and organ components following injury or disease. A growing interest is focused on the elucidation and characterization of the molecular mechanisms involved in these regenerative processes. We have now analyzed the possible role of the Wnt/ß-catenin pathway on the regeneration of the intestine in the sea cucumber Holothuria glaberrima. For this we have studied the expression in vivo of Wnt-associated genes and have implemented the use of Dicer-substrate interference RNA (DsiRNA) to knockdown the expression of ß-catenin transcript on gut rudiment explants. Neither cell dedifferentiation nor apoptosis were affected by the reduction of ß-catenin transcripts in the gut rudiment explants. Yet, the number of proliferating cells decreased significantly following the interference, suggesting that the Wnt/ß-catenin signaling pathway plays a significant role in cell proliferation, but not in cell dedifferentiation nor apoptosis during the regeneration of the intestine. The development of the in vitro RNAi protocol is a significant step in analyzing specific gene functions involved in echinoderm regeneration.

Cells of the human intestinal tract mapped across space and time.

The cellular landscape of the human intestinal tract is dynamic throughout life, developing in utero and changing in response to functional requirements and environmental exposures. Here, to comprehensively map cell lineages, we use single-cell RNA sequencing and antigen receptor analysis of almost half a million cells from up to 5 anatomical regions in the developing and up to 11 distinct anatomical regions in the healthy paediatric and adult human gut. This reveals the existence of transcriptionally distinct BEST4 epithelial cells throughout the human intestinal tract. Furthermore, we implicate IgG sensing as a function of intestinal tuft cells. We describe neural cell populations in the developing enteric nervous system, and predict cell-type-specific expression of genes associated with Hirschsprung's disease. Finally, using a systems approach, we identify key cell players that drive the formation of secondary lymphoid tissue in early human development. We show that these programs are adopted in inflammatory bowel disease to recruit and retain immune cells at the site of inflammation. This catalogue of intestinal cells will provide new insights into cellular programs in development, homeostasis and disease.

Enteric neuronal development in canine small intestine - an immunohistochemical study.

The development of the enteric nervous system (ENS) is still a valid and intensely studied issue. However, literature in the field has no data on this topic in the dog. The present investigations were performed in three groups of fetuses from mongrel dogs - from the third, sixth- -seventh, and ninth week of pregnancy - and in 3-5-day-old puppies (3 specimens for each age group). The tissues (the medial parts of the duodenum, jejunum, and ileum with the cecum and a small portion of the adjacent ascending colon) were cut using a cryostat and the sections were processed for single- and double-labeling immunohistochemistry using antisera against acetylated tubulin (AcTub), vesicular acetylcholine transporter (VAChT), nitric oxide synthase (NOS), vasoactive intestinal polypeptide (VIP), galanin (GAL), neuropeptide Y (NPY), substance P (SP), and calcitonin gene-related peptide (CGRP). In the 3-week-old fetuses, some oval cells invading the gut wall were found. From the seventh week of pregnancy onwards, two different enteric ganglia were present: submucosal and myenteric. The estimated number of nerve elements in the 9-week-old fetuses was much higher than that observed in the 6-7-week-old individuals. There was no significant difference in the estimated number of nerve structures between the 9-week-old fetuses and the 3-5-day-old puppies. The colonization pattern and the development of the ENS in the canine small intestine are very similar to those observed in other mam- mals. However, a few exceptions have been confirmed, regarding the time of appearance of the VIP-, GAL-, and CGRP-immunoreactive neurons, and their distribution in different portions of the canine bowel during development.

Acceleration of Small Intestine Development and Remodeling of the Microbiome Following Hyaluronan 35 kDa Treatment in Neonatal Mice.

The beneficial effects of human milk suppressing the development of intestinal pathologies such as necrotizing enterocolitis in preterm infants are widely known. Human milk (HM) is rich in a multitude of bioactive factors that play major roles in promoting postnatal maturation, differentiation, and the development of the microbiome. Previous studies showed that HM is rich in hyaluronan (HA) especially in colostrum and early milk. This study aims to determine the role of HA 35 KDa, a HM HA mimic, on intestinal proliferation, differentiation, and the development of the intestinal microbiome. We show that oral HA 35 KDa supplementation for 7 days in mouse pups leads to increased villus length and crypt depth, and increased goblet and Paneth cells, compared to controls. We also show that HA 35 KDa leads to an increased predominance of Clostridiales Ruminococcaceae, Lactobacillales Lactobacillaceae, and Clostridiales Lachnospiraceae. In seeking the mechanisms involved in the changes, bulk RNA seq was performed on samples from the terminal ileum and identified upregulation in several genes essential for cellular growth, proliferation, and survival. Taken together, this study shows that HA 35 KDa supplemented to mouse pups promotes intestinal epithelial cell proliferation, as well as the development of Paneth cells and goblet cell subsets. HA 35 KDa also impacted the intestinal microbiota; the implications of these responses need to be determined.

Microenvironmental innate immune signaling and cell mechanical responses promote tumor growth.

Tissue homeostasis is achieved by balancing stem cell maintenance, cell proliferation and differentiation, as well as the purging of damaged cells. Elimination of unfit cells maintains tissue health; however, the underlying mechanisms driving competitive growth when homeostasis fails, for example, during tumorigenesis, remain largely unresolved. Here, using a Drosophila intestinal model, we find that tumor cells outcompete nearby enterocytes (ECs) by influencing cell adhesion and contractility. This process relies on activating the immune-responsive Relish/NF-κB pathway to induce EC delamination and requires a JNK-dependent transcriptional upregulation of the peptidoglycan recognition protein PGRP-LA. Consequently, in organisms with impaired PGRP-LA function, tumor growth is delayed and lifespan extended. Our study identifies a non-cell-autonomous role for a JNK/PGRP-LA/Relish signaling axis in mediating death of neighboring normal cells to facilitate tumor growth. We propose that intestinal tumors "hijack" innate immune signaling to eliminate enterocytes in order to support their own growth.

Apical PAR complex proteins protect against programmed epithelial assaults to create a continuous and functional intestinal lumen.

Sustained polarity and adhesion of epithelial cells is essential for the protection of our organs and bodies, and this epithelial integrity emerges during organ development amidst numerous programmed morphogenetic assaults. Using the developing Caenorhabditis elegans intestine as an in vivo model, we investigated how epithelia maintain their integrity through cell division and elongation to build a functional tube. Live imaging revealed that apical PAR complex proteins PAR-6/Par6 and PKC-3/aPkc remained apical during mitosis while apical microtubules and microtubule-organizing center (MTOC) proteins were transiently removed. Intestine-specific depletion of PAR-6, PKC-3, and the aPkc regulator CDC-42/Cdc42 caused persistent gaps in the apical MTOC as well as in other apical and junctional proteins after cell division and in non-dividing cells that elongated. Upon hatching, gaps coincided with luminal constrictions that blocked food, and larvae arrested and died. Thus, the apical PAR complex maintains apical and junctional continuity to construct a functional intestinal tube.

Maternal galactooligosaccharides supplementation programmed immune defense, microbial colonization and intestinal development in piglets.

The benefits of galactooligosaccharides (GOS) in neonates have been confirmed. However, the effects of nutritional programming by maternal GOS intervention on microbial colonization and intestinal development in the offspring remain unclear. In the present study, late gestational sows were fed with GOS (10 g d-1 added into the diet) or not until parturition, and the performances, immune status, microbiota composition and intestinal barriers in their piglets on day 21 were compared. GOS supplementation in pregnant sows improved their litter characteristics and the growth performance of their piglets during the neonatal stage (day 21), and elevated the plasma IgA levels in both sows and their piglets (P < 0.05). GOS intervention enriched fecal Alloprevotella and Ruminoclostridium_1 in gestational sows and vertically increased fecal Alloprevotella and Ruminococcaceae in their piglets (P < 0.05). Moreover, maternal GOS intervention increased fecal acetate (P < 0.05) and improved the intestinal barriers of their piglets by upregulating intestinal tight junctions (Occludin, Claudin-1, ZO-1), the goblet cell number and Mucin-2 (P < 0.05), which correlated positively with the colonized microbiota (P < 0.05). In summary, GOS supplementation for sows during late gestation nutritionally programmed maternal specific microbes and IgA of their offspring. This neonatal programming showed positive potential in promoting the intestinal barriers, immune defense, and growth performance of the piglets. Our findings provide evidence for maternal nutritional programming in neonates and insights for future application of GOS in maternal-neonatal nutrition.

The Interplay between Immune System and Microbiota in Inflammatory Bowel Disease: A Narrative Review.

The importance of the gut microbiota in human health is currently well established. It contributes to many vital functions such as development of the host immune system, digestion and metabolism, barrier against pathogens or brain-gut communication. Microbial colonization occurs during infancy in parallel with maturation of the host immune system; therefore, an adequate cross-talk between these processes is essential to generating tolerance to gut microbiota early in life, which is crucial to prevent allergic and immune-mediated diseases. Inflammatory bowel disease (IBD) is characterized by an exacerbated immune reaction against intestinal microbiota. Changes in abundance in the gut of certain microorganisms such as bacteria, fungi, viruses, and archaea have been associated with IBD. Microbes that are commonly found in high abundance in healthy gut microbiomes, such as F. prausnitzii or R. hominis, are reduced in IBD patients. E. coli, which is usually present in a healthy gut in very low concentrations, is increased in the gut of IBD patients. Microbial taxa influence the immune system, hence affecting the inflammatory status of the host. This review examines the IBD microbiome profile and presents IBD as a model of dysbiosis.

Thyroid Hormone Receptor Is Essential for Larval Epithelial Apoptosis and Adult Epithelial Stem Cell Development but Not Adult Intestinal Morphogenesis during Xenopus tropicalis Metamorphosis.

Vertebrate postembryonic development is regulated by thyroid hormone (T3). Of particular interest is anuran metamorphosis, which offers several unique advantages for studying the role of T3 and its two nuclear receptor genes, TRα and TRß, during postembryonic development. We have recently generated TR double knockout (TRDKO) Xenopus tropicalis animals and reported that TR is essential for the completion of metamorphosis. Furthermore, TRDKO tadpoles are stalled at the climax of metamorphosis before eventual death. Here we show that TRDKO intestine lacked larval epithelial cell death and adult stem cell formation/proliferation during natural metamorphosis. Interestingly, TRDKO tadpole intestine had premature formation of adult-like epithelial folds and muscle development. In addition, T3 treatment of premetamorphic TRDKO tadpoles failed to induce any metamorphic changes in the intestine. Furthermore, RNA-seq analysis revealed that TRDKO altered the expression of many genes in biological pathways such as Wnt signaling and the cell cycle that likely underlay the inhibition of larval epithelial cell death and adult stem cell development caused by removing both TR genes. Our data suggest that liganded TR is required for larval epithelial cell degeneration and adult stem cell formation, whereas unliganded TR prevents precocious adult tissue morphogenesis such as smooth-muscle development and epithelial folding.

Exosomal circRNAs contribute to intestinal development via the VEGF signalling pathway in human term and preterm colostrum.

Human breast milk (HBM) provides essential nutrients for newborn growth and development, and contains a variety of biologically active ingredients that can affect gastrointestinal tract and immune system development in breastfed infants. HBM also contains mRNAs, microRNAs and lncRNAs, most of which are encapsulated in milk-derived exosomes and exhibit various important infant development related biological functions. While previous studies have shown that exosomal circRNAs are involved in the intestinal epithelial cells' proliferation and repair. However, the effect of HBM exosomal circRNAs on intestinal development is not clear. In this study, we identified 6756 circRNAs both in preterm colostrum (PC) and term colostrum (TC), of which 66 were upregulated, and 42 were downregulated (|fold change>2|, p < 0.05) in PC. Pathway analysis showed that the VEGF signalling pathway was involved, and network analysis revealed that the differentially expressed circRNAs bound various miRNAs. Further analyses showed that has_circRNA_405708 and has_circRNA_104707 were involved in the VEGF signalling pathway, and that they all bound various mirRNAs. Exosomes found in preterm colostrum (PC) and term colostrum (TC) promoted VEGF protein expression and induced the proliferation and migration of small intestinal epithelial cells (FHCs). Exosomal circRNAs found in human colostrum (HC) binding to related miRNAs may regulate VEGF signalling, and intestinal development.

white regulates proliferative homeostasis of intestinal stem cells during ageing in Drosophila.

Tissue integrity is contingent on maintaining stem cells. Intestinal stem cells (ISCs) over-proliferate during ageing, leading to tissue dysplasia in Drosophila melanogaster. Here we describe a role for white, encoding the evolutionarily conserved ATP-binding cassette transporter subfamily G, with a particularly well-characterized role in eye colour pigmentation, in ageing-induced ISC proliferation in the midgut. ISCs increase expression of white during ageing. ISC-specific inhibition of white suppresses ageing-induced ISC dysregulation and prolongs lifespan. Of the proteins that form heterodimers with White, Brown mediates ISC dysregulation during ageing. Metabolomics analyses reveal previously unappreciated, profound metabolic impacts of white inhibition on organismal metabolism. Among the metabolites affected by White, tetrahydrofolate is transported by White, is accumulated in ISCs during ageing and is indispensable for ageing-induced ISC over-proliferation. Since Thomas Morgan's isolation of a white mutant as the first Drosophila mutant, white mutants have been used extensively as genetic systems and often as controls. Our findings provide insights into metabolic regulation of stem cells mediated by the classic gene white.