Dusenbery DB (1975) J Exp Zool "The avoidance of D-tryptophan by the nematode Caenorhabditis elegans."

Dusenbery DB

[J Exp Zool, 1975]

In chemotactic studies employing countercurrent separation the nematode Caenorhabditis elegans was found to avoid D-tryptophan with a threshold in the range 10(-4) to 10(-3) M. There was no response to L-tryptophan up to 10(-2) M although it appeared to partially inhibit the response to D-tryptophan.

Dabbish N S et al. (2010) Neuronal Development, Synaptic Function and Behavior, Madison, WI "Reduced GABAergic synaptic transmission during lethargus"

Dabbish N S, Raizen D M

[Neuronal Development, Synaptic Function and Behavior, Madison, WI, 2010]

There is increasing evidence that sleep may play a synaptic function, yet little is known about the mechanisms of synaptic alterations during sleep. We used pharmacologic and optogenetic studies of synaptic transmission at the neuromuscular junction during lethargus, a sleep-like state in C. elegans. Our observations suggest a surprising decrease in GABAergic signaling during lethargus. Worms in lethargus demonstrate hyper-sensitivity to aldicarb. During adult satiety, another quiescent behavioral state, worms were also aldicarb-hypersensitive, demonstrating another similarity between lethargus quiescence and adult quiescence. The aldicarb hypersensitive unc-25 mutants, which lack GABA, demonstrate a wild-type time-course to paralysis during L4 lethargus. This suggests that the mechanism of hypersensitivity involves reduced GABAergic neurotransmission. In support of this mechanism, we found a reduced behavioral response (body elongation) to optogenetic stimulation of GABAergic motor neurons during lethargus. We observed that worms in lethargus are resistant to muscimol a GABA agonist, suggesting that a post-synaptic mechanism is responsible for the decreased GABAergic signaling. In a pilot genetic screen, we obtained one mutant with resistance to aldicarb during lethargus yet normal sensitivity as an adult. This shows that hypersensitivity to aldicarb during lethargus is genetically regulated.

Davis, K. C. et al. (2019) International Worm Meeting "Beauty sleep: Skin collagens regulate sleep in response to cell stress."

Davis, K. C., Raizen, D. M.

[International Worm Meeting, 2019]

When animals are sick or injured from an exposure that results in cell stress, they respond by sleeping; such behavior is called sickness or stress induced sleep (SIS). The pathway regulating SIS may be conserved from nematodes to vertebrates, and is relevant to fatigue behavior in humans during sickness. Cellular stress leads to activation of the epidermal growth factor (EGF) receptor on the ALA neuron, which releases neuropeptides. ALA neuropeptides induce SIS behavior, which consists of movment and feeding quiescence, elevated arousal threshold, and rapid reversibility. While much is known about ALA activation and its down stream mechanisms, the SIS pathway upstream of EGF remains poorly understood. This is the focus of our work. Mutants disrupting the cuticular collagens DPY-5, DPY-10, or DPY-13 showed impaired feeding and movement quiescence following exposures to ultraviolet (UV) irradiation, heat shock, or viral infection. Each of the three dpy mutants showed normal or enhanced SIS following EGF overexpression, suggesting that these genes act upstream of or in parallel to EGF. To determine if mutants with a Dpy phenotype due to mutations other than collagen genes are important for SIS, we tested mutants in dpy-19, which encodes a C-mannosyltransferase. dpy-19 mutants had normal SIS following both UV and heat shock, suggesting that specifically collagen gene disruption and not the Dpy phenotype explains the impairment in SIS in the dpy-5, -10, and -13 mutants. To determine whether disruption of the cuticle without disrupting collagens affects SIS, we tested bus-8 mutants, which encodes a glycosyltransferase that is important for cuticle integrity. bus-8 mutants are not Dpy. bus-8 mutants were not defective in SIS, suggesting that disrupting the cuticle is not sufficient to impair SIS, but that collagen disruption specifically is important. We propose that effects of skin collagen disruption on sleepiness are relevant to commmon complaint of fatigue in patients with connective tissue disorders.

Lamb A L et al. (2010) Neuronal Development, Synaptic Function and Behavior, Madison, WI "A Role for daf-16 in the Response to Deprivation of Lethargus Quiescence"

Lamb A L, Raizen D M

[Neuronal Development, Synaptic Function and Behavior, Madison, WI, 2010]

Molting lethargus is a developmentally regulated period of quiescent behavior that has physiological and genetic similarities to sleep, including a homeostatic response to deprivation. We hypothesized that metabolic signaling by the insulin-like signaling pathway would be affected by deprivation of lethargus quiescence. A GFP::DAF-16 fusion protein was used to monitor the subcellular location of DAF-16 in response to forced swimming for 30 minutes. We found an increase in nuclear GFP::DAF-16 after deprivation compared to time-matched controls during L4 lethargus but not during the adult stage. To test in a different fashion whether deprivation causes reduced insulin signaling, we deprived daf-8 mutants of L1 lethargus quiescence. Daf-C mutants have a temperature sensitive period at the end of the L1 stage (Swanson and Riddle, 1981), suggesting that the dauer decision is made during L1 lethargus. Following quiescence deprivation during L1 lethargus but not earlier or later, there was an increase in dauer formation in comparison to control animals. Thus, insulin signaling is reduced by deprivation of lethargus quiescence. To test for a role for daf-16 in the behavioral response to deprivation of lethargus quiescence, we examined the behavior of daf-16 mutants following forced swimming during lethargus. Wild-type animals show elevated response latencies to octanol or to blue light stimulation following deprivation of lethargus quiescence. In contrast, four daf-16 alleles behaved the same after deprivation as they had in the absence of deprivation, indicating a defective homeostatic response to deprivation of lethargus quiescence. Introduction of daf-16 in several tissues rescues this defective homeostatic response, suggesting a non-cell autonomous role for daf-16 in this response. In contrast to daf-16 mutants, daf-2 mutants showed an exaggerated homeostatic response, which was partially daf-16 dependent, to deprivation of lethargus quiescence.

Rutherford TA et al. (1979) J Nematol "Wave Forms of Caenorhabditis elegans in a Chemical Attractant and Repellent and in Thermal Gradients."

Rutherford TA, Croll NA

[J Nematol, 1979]

The wave forms and activity patterns of Caenorhabditis elegans were examined on agar in the presence of known chemical attractants (NaCl) and repellents (D-tryptophan), and in thermal gradients. Total activity was reduced in both attractants and repellents. Different combinations of transfers between chemicals were investigated. Two thresholds were found for NaCl: 10(-3) M NaC1 caused reduced activity; 10 M NaCl increased reversals. D- or L-tryptophan influenced neither orientation nor the ability of thermally acclimatized individuals to remain at their eccritic temperature.

Sakoguchi H et al. (2016) Biosci Biotechnol Biochem "Screening of biologically active monosaccharides: growth inhibitory effects of d-allose, d-talose, and l-idose against the nematode Caenorhabditis elegans."

Izumori K, Yoshihara A, Sakoguchi H, Sato M

[Biosci Biotechnol Biochem, 2016]

We compared the growth inhibitory effects of all aldohexose stereoisomers against the model animal Caenorhabditis elegans. Among the tested compounds, the rare sugars d-allose (d-All), d-talose (d-Tal), and l-idose (l-Ido) showed considerable growth inhibition under both monoxenic and axenic culture conditions. 6-Deoxy-d-All had no effect on growth, which suggests that C6-phosphorylation by hexokinase is essential for inhibition by d-All.

Sakoguchi H et al. (2016) Bioorg Med Chem Lett "Growth inhibitory effect of d-arabinose against the nematode Caenorhabditis elegans: Discovery of a novel bioactive monosaccharide."

Shintani T, Izumori K, Sato M, Sakoguchi H, Okuma K, Yoshihara A

[Bioorg Med Chem Lett, 2016]

Biological activities of unusual monosaccharides (rare sugars) have largely remained unstudied until recently. We compared the growth inhibitory effects of aldohexose stereoisomers against the animal model Caenorhabditis elegans cultured in monoxenic conditions with Escherichia coli as food. Among these stereoisomers, the rare sugar d-arabinose (d-Ara) showed particularly strong growth inhibition. The IC50 value for d-Ara was estimated to be 7.5mM, which surpassed that of the potent glycolytic inhibitor 2-deoxy-d-glucose (19.5mM) used as a positive control. The inhibitory effect of d-Ara was also observed in animals cultured in axenic conditions using a chemically defined medium; this excluded the possible influence of E. coli. To our knowledge, this is the first report of biological activity of d-Ara. The d-Ara-induced inhibition was recovered by adding either d-ribose or d-fructose, but not d-glucose. These findings suggest that the inhibition could be induced by multiple mechanisms, for example, disturbance of d-ribose and d-fructose metabolism.

Yoshihara A et al. (2019) Bioorg Med Chem Lett "Growth inhibition by 1-deoxy-d-allulose, a novel bioactive deoxy sugar, screened using Caenorhabditis elegans assay."

Sakoguchi H, Fleet GWJ, Izumori K, Shintani T, Sato M, Yoshihara A

[Bioorg Med Chem Lett, 2019]

The biological activities of deoxy sugars (deoxy monosaccharides) have remained largely unstudied until recently. We compared the growth inhibition by all 1-deoxyketohexoses using the animal model Caenorhabditis elegans. Among the eight stereoisomers, 1-deoxy-d-allulose (1d-d-Alu) showed particularly strong growth inhibition. The 50% inhibition of growth (GI₅₀) concentration by 1d-d-Alu was estimated to be 5.4mM, which is approximately 10 times lower than that of d-allulose (52.7mM), and even lower than that of the potent glycolytic inhibitor, 2-deoxy-d-glucose (19.5mM), implying that 1d-d-Alu has a strong growth inhibition. In contrast, 5-deoxy- and 6-deoxy-d-allulose showed no growth inhibition of C. elegans. The inhibition by 1d-d-Alu was alleviated by the addition of d-ribose or d-fructose. Our findings suggest that 1d-d-Alu-mediated growth inhibition could be induced by the imbalance in d-ribose metabolism. To our knowledge, this is the first report of biological activity of 1d-d-Alu which may be considered as an antimetabolite drug candidate.

Katane M et al. (2020) Biochim Biophys Acta Proteins Proteom "Biochemical characterization of d-aspartate oxidase from Caenorhabditis elegans: Its potential use in the determination of free D-glutamate in biological samples."

Katane M, Sekine M, Nakayama K, Homma H, Kuwabara H, Saitoh Y, Miyamoto T

[Biochim Biophys Acta Proteins Proteom, 2020]

d-Aspartate oxidase (DDO) is a flavin adenine dinucleotide (FAD)-containing flavoprotein that stereospecifically acts on acidic D-amino acids (i.e., free d-aspartate and D-glutamate). Mammalian DDO, which exhibits higher activity toward d-aspartate than D-glutamate, is presumed to regulate levels of d-aspartate in the body and is not thought to degrade D-glutamate in vivo. By contrast, three DDO isoforms are present in the nematode Caenorhabditis elegans, DDO-1, DDO-2, and DDO-3, all of which exhibit substantial activity toward D-glutamate as well as d-aspartate. In this study, we optimized the Escherichia coli culture conditions for production of recombinant C. elegans DDO-1, purified the protein, and showed that it is a flavoprotein with a noncovalently but tightly attached FAD. Furthermore, C. elegans DDO-1, but not mammalian (rat) DDO, efficiently and selectively degraded D-glutamate in addition to d-aspartate, even in the presence of various other amino acids. Thus, C. elegans DDO-1 might be a useful tool for determining these acidic D-amino acids in biological samples.

Margier M et al. (2018) FASEB J "ABCB1 (P-glycoprotein) regulates vitamin D absorption and contributes to its transintestinal efflux."

Borel P, Lebrun C, Desmarchelier C, Bluteau A, Reboul E, Lespine A, le May C, Margier M, Collet X, Defoort C, Andre F

[FASEB J, 2018]

Efficient intestinal absorption of dietary vitamin D is required in most people to ensure an adequate status. Thus, we investigated the involvement of ATP binding cassette subfamily B member 1 (ABCB1) in vitamin D intestinal efflux. Both cholecalciferol (D₃) and 25-hydroxycholecalciferol [25(OH)D₃] apical effluxes were decreased by chemical inhibition of ABCB1 in Caco-2 cells and increased by ABCB1 overexpression in Griptites or Madin-Darby canine kidney type II cells. Mice deficient for the 2 murine ABCB1s encoded by Abcb1a and Abcb1b genes ( Abcb1^-/-) displayed an accumulation of 25(OH)D₃ in plasma, intestine, brain, liver, and kidneys, together with an increased D₃ postprandial response after gavage compared with controls. 25(OH)D₃ efflux through Abcb1^-/- intestinal explants was markedly decreased compared with controls. This reduction of 25(OH)D₃ transfer from plasma to lumen was further confirmed in vivo in intestine-perfused mice. Docking experiments established that both D₃ and 25(OH)D₃ could bind with high affinity to Caenorhabditis elegans P-glycoprotein, used as an ABCB1 model. Finally, in a group of 39 healthy male adults, a single-nucleotide polymorphism (SNP) in ABCB1 (rs17064) was significantly associated with the fasting plasma 25(OH)D₃ concentration. Thus, we showed here for the first time that ABCB1 is involved in neo-absorbed vitamin D efflux by the enterocytes and that it also contributes to vitamin D transintestinal excretion and likely impacts vitamin D status.-Margier, M., Collet, X., le May, C., Desmarchelier, C., Andre, F., Lebrun, C., Defoort, C., Bluteau, A., Borel, P., Lespine, A., Reboul, E. ABCB1 (P-glycoprotein) regulates vitamin D absorption and contributes to its transintestinal efflux.