Cloning and functional characterization of a folate transporter from the nematode Caenorhabditis elegans

A specific folate activates serotonergic neurons to control C. elegans behavior

Folates are B-group vitamins that function in one-carbon metabolism. Here we show that a specific folate can activate serotonergic neurons in C. elegans to modulate behavior through a pathway that requires the folate receptor FOLR-1 and the GON-2 calcium channel. FOLR-1 and GON-2 physically interact in a heterologous system, and both are expressed in the HSN and NSM serotonergic neurons. Both the folate 10-formyl-THF and a non-metabolic pteroate induce increases in the number of Ca2+ transients in the HSN neurons and egg laying in an FOLR-1- and GON-2-dependent manner. FOLR-1 and GON-2 are required for the activation of the NSM neurons in response to 10-formyl-THF, and for full NSM-mediated stoppage of movement when starved animals encounter bacteria. Our results demonstrate that FOLR-1 acts independently of one-carbon metabolism and suggest that 10-formyl-THF acts as a dietary signal that activates serotonergic neurons to impact behavior through a pathway that involves calcium entry.

Loss of the histone chaperone UNC-85/ASF1 inhibits the epigenome-mediated longevity and modulates the activity of one-carbon metabolism

Histone H3/H4 chaperone anti-silencing function 1 (ASF1) is a conserved factor mediating nucleosomal assembly and disassembly, playing crucial roles in processes such as replication, transcription, and DNA repair. Nevertheless, its involvement in aging has remained unclear. Here, we utilized the model organism Caenorhabditis elegans to demonstrate that the loss of UNC-85, the homolog of ASF1, leads to a shortened lifespan in a multicellular organism. Furthermore, we show that UNC-85 is required for epigenome-mediated longevity, as knockdown of the histone H3 lysine K4 methyltransferase ash-2 does not extend the lifespan of unc-85 mutants. In this context, we found that the longevity-promoting ash-2 RNA interference enhances UNC-85 activity by increasing its nuclear localization. Finally, our data indicate that the loss of UNC-85 increases the activity of one-carbon metabolism, and that downregulation of the one-carbon metabolism component dao-3/MTHFD2 partially rescues the short lifespan of unc-85 mutants. Together, these findings reveal UNC-85/ASF1 as a modulator of the central metabolic pathway and a factor regulating a pro-longevity response, thus shedding light on a mechanism of how nucleosomal maintenance associates with aging.

Folate receptor overexpression induces toxicity in a diet-dependent manner in C. elegans

Folate receptor (FR) alpha (FOLR1) and beta (FOLR2) are membrane-anchored folate transporters that are expressed at low levels in normal tissues, while their expression is strongly increased in several cancers. Intriguingly, although the function of these receptors in, for example, development and cancer has been studied intensively, their role in aging is still unknown. To address this, we utilized Caenorhabditis elegans, in which FOLR-1 is the sole ortholog of folate receptors. We found that the loss of FOLR-1 does not affect reproduction, physical condition, proteostasis or lifespan, indicating that it is not required for folate transport to maintain health. Interestingly, we found that FOLR-1 is detectably expressed only in uterine-vulval cells, and that the histone-binding protein LIN-53 inhibits its expression in other tissues. Furthermore, whereas knockdown of lin-53 is known to shorten lifespan, we found that the loss of FOLR-1 partially rescues this phenotype, suggesting that elevated folr-1 expression is detrimental for health. Indeed, our data demonstrate that overexpression of folr-1 is toxic, and that this phenotype is dependent on diet. Altogether, this work could serve as a basis for further studies to elucidate the organismal effects of abnormal FR expression in diseases such as cancer.

Anti-retroviral treatment with zidovudine alters pyrimidine metabolism, reduces translation, and extends healthy longevity via ATF-4

The human population is aging, and the need for interventions to slow progression of age-related diseases (geroprotective interventions) is growing. Repurposing compounds already used clinically, usually at modified doses, allows rapid implementation of geroprotective pharmaceuticals. Here we find the anti-retroviral nucleoside reverse transcriptase inhibitor (NRTI) zidovudine robustly extends lifespan and health span in C. elegans, independent of electron transport chain impairment or ROS accumulation. Rather, zidovudine treatment modifies pyrimidine metabolism and transcripts related to proteostasis. Testing regulators of mitochondrial stress and proteostasis shows that lifespan extension is dependent on activating transcription factor 4 (ATF-4). ATF-4 regulates longevity induced by mitochondrial stress, specifically communication between mitochondrial and cytosolic translation. Translation is reduced in zidovudine-treated worms, also dependent on ATF-4. Finally, we show ATF-4-dependent lifespan extension induced by didanosine, another NRTI. Altogether, our work elucidates the geroprotective effects of NRTIs such as zidovudine in vivo, via reduction of translation and ATF-4.

Transcriptomics of ivermectin response in Caenorhabditis elegans: Integrating abamectin quantitative trait loci and comparison to the Ivermectin-exposed DA1316 strain

Parasitic nematodes pose a significant threat to human and animal health, as well as cause economic losses in the agricultural sector. The use of anthelmintic drugs, such as Ivermectin (IVM), to control these parasites has led to widespread drug resistance. Identifying genetic markers of resistance in parasitic nematodes can be challenging, but the free-living nematode Caenorhabditis elegans provides a suitable model. In this study, we aimed to analyze the transcriptomes of adult C. elegans worms of the N2 strain exposed to the anthelmintic drug Ivermectin (IVM), and compare them to those of the resistant strain DA1316 and the recently identified Abamectin Quantitative Trait Loci (QTL) on chromosome V. We exposed pools of 300 adult N2 worms to IVM (10-7 and 10-8 M) for 4 hours at 20°C, extracted total RNA and sequenced it on the Illumina NovaSeq6000 platform. Differentially expressed genes (DEGs) were determined using an in-house pipeline. The DEGs were compared to genes from a previous microarray study on IVM-resistant C. elegans and Abamectin-QTL. Our results revealed 615 DEGs (183 up-regulated and 432 down-regulated genes) from diverse gene families in the N2 C. elegans strain. Of these DEGs, 31 overlapped with genes from IVM-exposed adult worms of the DA1316 strain. We identified 19 genes, including the folate transporter (folt-2) and the transmembrane transporter (T22F3.11), which exhibited an opposite expression in N2 and the DA1316 strain and were deemed potential candidates. Additionally, we compiled a list of potential candidates for further research including T-type calcium channel (cca-1), potassium chloride cotransporter (kcc-2), as well as other genes such as glutamate-gated channel (glc-1) that mapped to the Abamectin-QTL.

Bacteria increase host micronutrient availability: mechanisms revealed by studies in C. elegans

Micronutrients cannot be synthesized by humans and are obtained from three different sources: diet, gut microbiota, and oral supplements. The microbiota generates significant quantities of micronutrients, but the contribution of these compounds to total uptake is unclear. The role of bacteria in the synthesis and uptake of micronutrients and supplements is widely unexplored and may have important implications for human health. The efficacy and safety of several micronutrient supplements, including folic acid, have been questioned due to some evidence of adverse effects on health. The use of the simplified animal-microbe model, Caenorhabditis elegans, and its bacterial food source, Escherichia coli, provides a controllable system to explore the underlying mechanisms by which bacterial metabolism impacts host micronutrient status. These studies have revealed mechanisms by which bacteria may increase the bioavailability of folic acid, B12, and iron. These routes of uptake interact with bacterial metabolism, with the potential to increase bacterial pathogenesis, and thus may be both beneficial and detrimental to host health.

The nutritional requirements of Caenorhabditis elegans

Animals require sufficient intake of a variety of nutrients to support their development, somatic maintenance and reproduction. An adequate diet provides cell building blocks, chemical energy to drive cellular processes and essential nutrients that cannot be synthesised by the animal, or at least not in the required amounts. Dietary requirements of nematodes, including Caenorhabditis elegans have been extensively studied with the major aim to develop a chemically defined axenic medium that would support their growth and reproduction. At the same time, these studies helped elucidating important aspects of nutrition-related biochemistry and metabolism as well as the establishment of C. elegans as a powerful model in studying evolutionarily conserved pathways, and the influence of the diet on health.

Developmental Control of the Cell Cycle: Insights from Caenorhabditis elegans

During animal development, a single fertilized egg forms a complete organism with tens to trillions of cells that encompass a large variety of cell types. Cell cycle regulation is therefore at the center of development and needs to be carried out in close coordination with cell differentiation, migration, and death, as well as tissue formation, morphogenesis, and homeostasis. The timing and frequency of cell divisions are controlled by complex combinations of external and cell-intrinsic signals that vary throughout development. Insight into how such controls determine in vivo cell division patterns has come from studies in various genetic model systems. The nematode Caenorhabditis elegans has only about 1000 somatic cells and approximately twice as many germ cells in the adult hermaphrodite. Despite the relatively small number of cells, C. elegans has diverse tissues, including intestine, nerves, striated and smooth muscle, and skin. C. elegans is unique as a model organism for studies of the cell cycle because the somatic cell lineage is invariant. Somatic cells divide at set times during development to produce daughter cells that adopt reproducible developmental fates. Studies in C. elegans have allowed the identification of conserved cell cycle regulators and provided insights into how cell cycle regulation varies between tissues. In this review, we focus on the regulation of the cell cycle in the context of C. elegans development, with reference to other systems, with the goal of better understanding how cell cycle regulation is linked to animal development in general.

A bacterial route for folic acid supplementation

Background

To prevent folate deficiencies, many countries supplement various foodstuffs with folic acid. This compound is a synthetic oxidised folate that differs from naturally occurring reduced folates in its metabolism and uptake. Notably, safety reviews of folic acid supplementation have not considered interactions with gut bacteria. Here, we use the Caenorhabditis elegans – Escherichia coli animal– microbe model to examine a possible bacterial route for folic acid uptake. It has been assumed that supplements are taken up directly by the worm, especially because E. coli is unable to take up folates. However, E. coli, like many other bacteria, can transport the folate breakdown product, para-aminobenzoate-glutamate (PABA-glu), via AbgT and use it for bacterial folate synthesis. This pathway may impact host health because inhibition of bacterial folate synthesis increases C. elegans lifespan.

Results

Folic acid supplementation was found to rescue a C. elegans developmental folate-deficient mutant; however, a much higher concentration was required compared to folinic acid, a reduced folate. Unlike folinic acid, the effectiveness of folic acid supplementation was dependent on the E. coli gene, abgT, suggesting a bacterial route with PABA-glu uptake by E. coli as a first step. Surprisingly, we found up to 4% PABA-glu in folic acid preparations, including in a commercial supplement. Via breakdown to PABA-glu, folic acid increases E. coli folate synthesis. This pathway restores folate synthesis in a bacterial mutant defective in PABA synthesis, reversing the ability of this mutant to increase C. elegans lifespan.

Conclusions

Folic acid supplementation in C. elegans occurs chiefly indirectly via bacterial uptake of breakdown products via E. coli AbgT, and can impact C. elegans development and longevity. Examining how folic acid supplementation affects bacterial folate synthesis in the human gut may help us to better understand the safety of folic acid supplementation.

Electronic supplementary material

The online version of this article (10.1186/s12915-018-0534-3) contains supplementary material, which is available to authorized users.

Bacterial Folates Provide an Exogenous Signal for C. elegans Germline Stem Cell Proliferation

Here we describe an in vitro primary culture system for Caenorhabditis elegans germline stem cells. This culture system was used to identify a bacterial folate as a positive regulator of germ cell proliferation. Folates are a family of B-complex vitamins that function in one-carbon metabolism to allow the de novo synthesis of amino acids and nucleosides. We show that germ cell proliferation is stimulated by the folate 10-formyl-tetrahydrofolate-Glun both in vitro and in animals. Other folates that can act as vitamins to rescue folate deficiency lack this germ cell stimulatory activity. The bacterial folate precursor dihydropteroate also promotes germ cell proliferation in vitro and in vivo, despite its inability to promote one-carbon metabolism. The folate receptor homolog FOLR-1 is required for the stimulation of germ cells by 10-formyl-tetrahydrofolate-Glun and dihydropteroate. This work defines a folate and folate-related compound as exogenous signals to modulate germ cell proliferation.

The Adverse Effects of Triptolide on the Reproductive System of Caenorhabditis elegans: Oogenesis Impairment and Decreased Oocyte Quality

Previous studies have revealed that Triptolide damages female reproductive capacity, but the mechanism is unclear. In this study, we used Caenorhabditis elegans to investigate the effects of Triptolide on the germline and explore its possible mechanisms. Our data show that exposure for 4 h to 50 and 100 mg/L Triptolide reduced C. elegans fertility, led to depletion and inactivation of spermatids with the changes in the expression levels of related genes, and increased the number of unfertilized oocytes through damaging chromosomes and DNA damage repair mechanisms. After 24 and 48 h of the 4 h exposure to 50 and 100 mg/L Triptolide, we observed shrink in distal tip cells, an increase in the number of apoptotic cells, a decrease in the number of mitotic germ cells and oocytes in diakinesis stage, and chromatin aggregates in -1 oocytes. Moreover, expression patterns of the genes associated with mitotic germ cell proliferation, apoptosis, and oocyte quality were altered after Triptolide exposure. Therefore, Triptolide may damage fertility of nematodes by hampering the development of oocytes at different developmental stages. Alterations in the expression patterns of genes involved in oocyte development may explain the corresponding changes in oocyte development in nematodes exposed to Triptolide.

The genome-wide role of HSF-1 in the regulation of gene expression in Caenorhabditis elegans

BACKGROUND

The heat shock response, induced by cytoplasmic proteotoxic stress, is one of the most highly conserved transcriptional responses. This response, driven by the heat shock transcription factor HSF1, restores proteostasis through the induction of molecular chaperones and other genes. In addition to stress-dependent functions, HSF1 has also been implicated in various stress-independent functions. In C. elegans, the HSF1 homolog HSF-1 is an essential protein that is required to mount a stress-dependent response, as well as to coordinate various stress-independent processes including development, metabolism, and the regulation of lifespan. In this work, we have performed RNA-sequencing for C. elegans cultured in the presence and absence of hsf-1 RNAi followed by treatment with or without heat shock. This experimental design thus allows for the determination of both heat shock-dependent and -independent biological targets of HSF-1 on a genome-wide level.

RESULTS

Our results confirm that C. elegans HSF-1 can regulate gene expression in both a stress-dependent and -independent fashion. Almost all genes regulated by HS require HSF-1, reinforcing the central role of this transcription factor in the response to heat stress. As expected, major categories of HSF-1-regulated genes include cytoprotection, development, metabolism, and aging. Within both the heat stress-dependent and -independent gene groups, significant numbers of genes are upregulated as well as downregulated, demonstrating that HSF-1 can both activate and repress gene expression either directly or indirectly. Surprisingly, the cellular process most highly regulated by HSF-1, both with and without heat stress, is cuticle structure. Via network analyses, we identify a nuclear hormone receptor as a common link between genes that are regulated by HSF-1 in a HS-dependent manner, and an epidermal growth factor receptor as a common link between genes that are regulated by HSF-1 in a HS-independent manner. HSF-1 therefore coordinates various physiological processes in C. elegans, and HSF-1 activity may be coordinated across tissues by nuclear hormone receptor and epidermal growth factor receptor signaling.

CONCLUSION

This work provides genome-wide HSF-1 regulatory networks in C. elegans that are both heat stress-dependent and -independent. We show that HSF-1 is responsible for regulating many genes outside of classical heat stress-responsive genes, including genes involved in development, metabolism, and aging. The findings that a nuclear hormone receptor may coordinate the HS-induced HSF-1 transcriptional response, while an epidermal growth factor receptor may coordinate the HS-independent response, indicate that these factors could promote cell non-autonomous signaling that occurs through HSF-1. Finally, this work highlights the genes involved in cuticle structure as important HSF-1 targets that may play roles in promoting both cytoprotection as well as longevity.

Riboflavin transporter-2 (rft-2) of Caenorhabditis elegans: Adaptive and developmental regulation

Riboflavin transporters (rft-1 and rft-2), orthologous to human riboflavin transporter-3 (hRVFT-3), are identified and characterized in Caenorhabditis elegans. However, studies pertaining to functional contribution of rft-2 in maintaining body homeostatic riboflavin levels and its regulation are very limited. In this study, the expression pattern of rft-2 at different life stages of C. elegans was studied through real-time PCR, and found to be consistent from larval to adult stages that demonstrate its involvement in maintaining the body homeostatic riboflavin levels at whole animal level all through its life. A possible regulation of rft-2 expression at mRNA levels at whole animal was studied after adaptation to low and high concentrations of riboflavin. Abundance of rft-2 transcript was upregulated in riboflavin-deficient conditions (10 nM), while it was downregulated with riboflavin-supplemented conditions (2 mM) as compared with control (10 meu M). Further, the 5'-regulatory region of the rft-2 gene was cloned, and transgenic nematodes expressing transcriptional rft-2 promoter::GFP fusion constructs were generated. The expression of rft-2 was found to be adaptively regulated in vivo when transgenic worms were maintained under different extracellular riboflavin levels, which was also mediated partly via changes in the rft-2 levels that directs towards the possible involvement of transcriptional regulatory events.

Folate Acts in E. coli to Accelerate C. elegans Aging Independently of Bacterial Biosynthesis

Folates are cofactors for biosynthetic enzymes in all eukaryotic and prokaryotic cells. Animals cannot synthesize folate and must acquire it from their diet or microbiota. Previously, we showed that inhibiting E. coli folate synthesis increases C. elegans lifespan. Here, we show that restriction or supplementation of C. elegans folate does not influence lifespan. Thus, folate is required in E. coli to shorten worm lifespan. Bacterial proliferation in the intestine has been proposed as a mechanism for the life-shortening influence of E. coli. However, we found no correlation between C. elegans survival and bacterial growth in a screen of 1,000+ E. coli deletion mutants. Nine mutants increased worm lifespan robustly, suggesting specific gene regulation is required for the life-shortening activity of E. coli. Disrupting the biosynthetic folate cycle did not increase lifespan. Thus, folate acts through a growth-independent route in E. coli to accelerate animal aging.

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Limiting folate in E. coli, not in C. elegans, increases worm lifespan

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An E. coli screen for worm longevity identifies folate synthesis as a target

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Folate synthesis influences E. coli physiology independently of growth

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Bacterial folate synthesis may be a sustainable target for chronic disease

Folate deficiency and over-supplementation causes impaired folate metabolism: Regulation and adaptation mechanisms in Caenorhabditis elegans

SCOPE

Impaired folate metabolism increases the risk of birth defects, neurodegenerative and cardiovascular disease, osteoporosis and cancer. We used Caenorhabditis elegans to investigate impaired folate metabolism by RNA interference of key enzymes in the methionine synthase (MS) and thymidylate synthase (TS) cycle and by folate deficiency and over-supplementation feeding studies.

METHODS AND RESULTS

Folate status is influenced by genetic variations (polymorphisms), folate deficiency and supplementation. Single RNAi of dihydrofolate reductase (DHFR), methylenetetrahydrofolate reductase (MTHFR) and MS revealed that gene regulation is largely affected in both folate cycles. Adaptation requires a close transcriptional connection between TS and MS cycle. Coupled DHFR and MS expression is required to balance both cycles, but seems to reduce the overall rate of folate conversion. Feeding studies showed that folate over-supplementation to functioning metabolism inactivates MS and MTHFR expression and enhances TS activity, which favors DNA synthesis over methylation reactions. Folate deficiency disrupted homeostasis by favoring TS cycle and led to malformation in C. elegans offspring. Embryos show aneuploidy and are nonviable lacking DNA repair during meiotic stage of diakinesis.

CONCLUSION

Single gene silencing alters gene expression in both cycles and disrupts folate homeostasis. Folate over-supplementation and deficiency favors TS over MS cycle and causes prophase DNA damage.

Folic acid supplementation at lower doses increases oxidative stress resistance and longevity in Caenorhabditis elegans

Folic acid (FA) is an essential nutrient that the human body needs but cannot be synthesized on its own. Fortified foods and plant food sources such as green leafy vegetables, beans, fruits, and juices are good sources of FA to meet the daily requirements of the body. The aim was to evaluate the effect of dietary FA levels on the longevity of well-known experimental aging model Caenorhabditis elegans. Here, we show for first time that FA extends organism life span and causes a delay in aging. We observed that FA inhibits mechanistic target of rapamycin (mTOR) and insulin/insulin growth factor 1 (IGF-1) signaling pathways to control both oxidative stress levels and life span. The expression levels of stress- and life span-relevant gerontogenes, viz. daf-16, skn-1, and sir. 2.1, and oxidative enzymes, such as glutathione S-transferase 4 (GST-4) and superoxide dismutase 3 (SOD-3), were also found to be highly enhanced to attenuate the intracellular reactive oxygen species (ROS) damage and to delay the aging process. Our study promotes the use of FA to mitigate abiotic stresses and other aging-related ailments.

Effects of Microcystin-LR Exposure on Spermiogenesis in Nematode Caenorhabditis elegans

Little is known about the effect on spermiogenesis induced by microcystin-leucine arginine (MC-LR), even though such data are very important to better elucidate reproductive health. In the current work, with the aid of nematode Caenorhabditis elegans (C. elegans) as an animal model, we investigated the defects on spermiogenesis induced by MC-LR. Our results showed that MC-LR exposure induced sperm morphology abnormality and caused severe defects of sperm activation, trans-activation, sperm behavior and competition. Additionally, the expression levels of spe-15 were significantly decreased in C. elegans exposed to MC-LR lower than 16.0 μg/L, while the expression levels of spe-10 and fer-1 could be significantly lowered in C. elegans even exposed to 1.0 μg/L of MC-LR. Therefore, the present study reveals that MC-LR can induce adverse effects on spermiogenesis, and those defects of sperm functions may be induced by the decreases of spe-10, spe-15 and fer-1 gene expressions in C. elegans.

Worms, bacteria, and micronutrients: an elegant model of our diet

Micronutrients are required in small proportions in a diet to carry out key metabolic roles for biomass and energy production. Humans receive micronutrients either directly from their diet or from gut microbiota that metabolize other nutrients. The nematode Caenorhabditis elegans and its bacterial diet provide a relatively simple and genetically tractable model to study both direct and microbe-mediated effects of micronutrients. Recently, this model has been used to gain insight into the relationship between micronutrients, physiology, and metabolism. In particular, two B-type vitamins, vitamin B12 and folate, have been studied in detail. Here we review how C. elegans and its bacterial diet provide a powerful interspecies systems biology model that facilitates the precise delineation of micronutrient effects and the mechanisms involved.

Identification and functional characterization of the Caenorhabditis elegans riboflavin transporters rft-1 and rft-2

Two potential orthologs of the human riboflavin transporter 3 (hRFVT3) were identified in the C. elegans genome, Y47D7A.16 and Y47D7A.14, which share 33.7 and 30.5% identity, respectively, with hRFVT3. The genes are tandemly arranged, and we assign them the names rft-1 (for Y47D7A.16) and rft-2 (for Y47D7A.14). Functional characterization of the coding sequences in a heterologous expression system demonstrated that both were specific riboflavin transporters, although the rft-1 encoded protein had greater transport activity. A more detailed examination of rft-1 showed its transport of riboflavin to have an acidic pH dependence, saturability (apparent Km = 1.4 ± 0.5 µM), inhibition by riboflavin analogues, and Na(+) independence. The expression of rft-1 mRNA was relatively higher in young larvae than in adults, and mRNA expression dropped in response to RF supplementation. Knocking down the two transporters individually via RNA interference resulted in a severe loss of fertility that was compounded in a double knockdown. Transcriptional fusions constructed with two fluorophores (rft-1::GFP, and rft-2::mCherry) indicated that rft-1 is expressed in the intestine and a small subset of neuronal support cells along the entire length of the animal. Expression of rft-2 is localized mainly to the intestine and pharynx. We also observed a drop in the expression of the two reporters in animals that were maintained in high riboflavin levels. These results report for the first time the identification of two riboflavin transporters in C. elegans and demonstrate their expression and importance to metabolic function in worms. Absence of transporter function renders worms sterile, making them useful in understanding human disease associated with mutations in hRFVT3.

Knockout of the folate transporter folt-1 causes germline and somatic defects in C. elegans

BACKGROUND

The C. elegans gene folt-1 is an ortholog of the human reduced folate carrier gene. The FOLT-1 protein has been shown to transport folate and to be involved in uptake of exogenous folate by worms. A knockout mutation of the gene, folt-1(ok1460), was shown to cause sterility, and here we investigate the source of the sterility and the effect of the folt-1 knockout on somatic function.

RESULTS

Our results show that folt-1(ok1460) knockout hermaphrodites have a substantially reduced germline, generate a small number of functional sperm, and only rarely produce a functional oocyte. We found no evidence of increased apoptosis in the germline of folt-1 knockout mutants, suggesting that germline proliferation is defective. While folt-1 knockout males are fertile, their rate of spermatogenesis was severely diminished, and the males were very poor maters. The mating defect is likely due to compromised metabolism and/or other somatic functions, as folt-1 knockout hermaphrodites displayed a shortened lifespan and elongated defecation intervals.

CONCLUSIONS

The FOLT-1 protein function affects both the soma and the germline. folt-1(ok1460) hermaphrodites suffer severely diminished lifespan and germline defects that result in sterility. Germline defects associated with folate deficiency appear widespread in animals, being found in humans, mice, fruit flies, and here, nematodes.