Diosgenin intervention: targeting lipophagy to counter high glucose diet-induced lipid accumulation and lifespan reduction.

Diosgenin (DG), a well-known steroidal sapogenin, is abundantly found in the plants of the Dioscoreaceae family and exhibits diverse pharmacological properties. In our previous study, we demonstrated that DG supplementation protected Caenorhabditis elegans from high glucose-induced lipid deposition, oxidative damage, and lifespan reduction. Nevertheless, the precise biological mechanisms underlying the beneficial effects of DG have not yet been described. In this context, the present study aims to elucidate how DG reduces molecular and cellular declines induced by high glucose, using the powerful genetics of the C. elegans model. Treatment with DG significantly (p < 0.01) prevented fat accumulation and extended lifespan under high-glucose conditions without affecting physiological functions. DG-induced lifespan extension was found to rely on longevity genes daf-2, daf-16, skn-1, glp-1, eat-2, let-363, and pha-4. Specifically, DG regulates lipophagy, the autophagy-mediated degradation of lipid droplets, in C. elegans, thereby inhibiting fat accumulation. Furthermore, DG treatment did not alter the triglyceride levels in the fat-6 and fat-7 single mutants and fat-6;fat-7 double mutants, indicating the significant role of stearoyl-CoA desaturase genes in mediating the reduction of fat deposition by DG. Our results provide new insight into the fat-reducing mechanisms of DG, which might develop into a multitarget drug for preventing obesity and associated health complications; however, preclinical studies are required to investigate the effect of DG on higher models. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-024-04017-3.

Development of a new broad-spectrum microencapsulation-based spray drying formulation of Bacillus thuringiensis subsp. kurstaki IMBL-B9 for the control of moths.

Certain Bacillus thuringiensis (Bt) strains such as Bt subsp. kurstaki and Bt subsp. aizawai have been widely used for pest management in agricultural practices. However, each strain only shows high specificity for pest control against a narrow range of lepidopteran species, and numerous lepidopteran pests have developed resistance to commercialized Bt strains. Therefore, there is a need for the development of novel Bt bioinsecticides which allow for potent and broad-spectrum insecticidal activity against lepidopteran species, including Spodoptera spp. (Noctuidae) and Plutella xylostealla (Plutellidae). In order to develop a novel bioinsecticide using Bt subsp. kurstaki IMBL-B9 (Btk IMBL-B9) that exhibits excellent insecticidal activity against three different lepidopteran species, we have developed a viable microencapsulation-based spray drying Btk IMBL-B9 formulation. The spore-crystal complex of Btk IMBL-B9 was microencapsulated using coating materials such as gum arabic, maltodextrin, and corn starch via spray drying. The encapsulated formulation of Btk IMBL-B9 presented an increased survival rate and storage stability at 54 ± 2°C for up to 6 weeks. The formulation showed similar insecticidal activity as the commercial bioinsecticide XenTari® against P. xylostella. Under controlled greenhouse conditions, the Btk IMBL-B9 formulation was more effective against Lepidoptera spp. S. frugiperda and P. xylostella, than XenTari®. These results suggest that the microencapsulation-based spray drying formulation of Btk IMBL-B9 can be used effectively for the control of a wide range of moths.

Fermented cereal-origin gerobiotic cocktails promote healthy longevity in Caenorhabditis elegans.

There is growing interest in dietary interventions, particularly gerobiotics, that directly target aging. Several single-strain gerobiotics have proven to be beneficial in alleviating aging and age-related functional declines across species, but multistrain/multispecies gerobiotics have been proven even more advantageous due to the potential synergy and additive effects among individual isolates. However, there is very limited research on how multistrain/multispecies gerobiotic combinations or cocktails extend healthy longevity. This study comprehensively analyzed probiotic bacteria from traditionally fermented Barnyard millet and compared their efficacy in promoting healthy longevity under various combinations using Caenorhabditis elegans. We have shown that dramatic lifespan extension can be achieved by combining gerobiotics, and the effect was found to be strictly strain-specific. Among the 120 combinations tested, we identified two synergistic gerobiotic combinations, cocktail 55 (combination of B. licheniformis PS70, L. delbrueckii subsp. bulgaricus PS77, and L. amylovorus PS60) and cocktail 112 (combination of L. delbrueckii subsp. bulgaricus PS77, L. lactis PS10, and P. pentosaceus PS91), extending the mean lifespan of C. elegans by up to 46.2% and 53.1%, respectively. Our mechanistic study showed that the life-promoting effect of cocktail 55 relied on the p38 MAPK-SKN-1 pathway, while cocktail 112 acted on multiple signaling pathways, including IIS, ß-catenin, and TGF-ß pathways, to achieve its impact on the host. Moreover, feeding gerobiotic cocktails improved several healthspan markers reported to decline with age. These observations showed that the gerobiotic cocktails target different subsets of the gene regulatory network controlling the aging process in C. elegans, thereby extending healthy longevity.

Elucidation of the nematicidal mode of action of grammicin on Caenorhabditis elegans.

Grammicin (Gra) is derived from the endophytic fungus Xylaria grammica EL000614 and shows nematicidal activity against the devastating root-knot nematode Meloidogyne incognita in-vitro, in planta, and in-field experiments. However, the mechanism of the nematicidal action of Gra remains unclear. In this study, Gra exposure to the model genetic organism Caenorhabditis elegans affected its L1, L2/3, L4, and young adult stages. In addition, Gra treatment increased the intracellular reactive oxygen species (ROS) levels of C. elegans and M. incognita. Molecular docking interaction analysis indicated that Gra could bind and interact with GCS-1, GST-4, and DAF-16a in order of low binding energy, followed by SOD-3, SKN-1, and DAF-16b. This implies that the anthelmintic action of Gra is related to the oxidative stress response. To validate this mechanism, we examined the expression of the genes involved in the oxidative stress responses following treatment with Gra using transgenic C. elegans strains such as the TJ356 strain zIs356 [daf-16p::daf-16a/b::GFP + rol-6 (su1006)], LD1 ldIs7 [skn-1p::skn-1b/c::GFP + rol-6 (su1006)], LD1171 ldIs3 [gcs-1p::GFP + rol-6 (su1006)], CL2166 dvIs19 [(pAF15) gst-4p::GFP::NLS], and CF1553 strain muIs84 [(pAD76) sod-3p::GFP + rol-6 (su1006)]. Gra treatment caused nuclear translocation of DAF-16/FoxO and enhanced gst-4::GFP expression, but it had no change in sod-3::GFP expression. These results indicate that Gra induces oxidative stress response via phase II detoxification without reduced cellular redox machinery. Gra treatment also inhibited the nuclear localization of SKN-1::GFP in the intestine, which may lead to a condition in which oxidative stress tolerance is insufficient to protect C. elegans by the inactivation of SKN-1, thus inducing nematode lethality. Furthermore, Gra caused the mortality of two mutant strains of C. elegans, CB113 and DA1316, which are resistant to aldicarb and ivermectin, respectively. This indicates that the mode of action of Gra is different from the traditional nematicides currently in use, suggesting that it could help develop novel approaches to control plant-parasitic nematodes.

Enhancement of Disease Control Efficacy of Chemical Fungicides Combined with Plant Resistance Inducer 2,3-Butanediol against Turfgrass Fungal Diseases.

Turfgrass, the most widely grown ornamental crop, is severely affected by fungal pathogens including Sclerotinia homoeocarpa, Rhizoctonia solani, and Magnaporthe poae. At present, turfgrass fungal disease management predominantly relies on synthetic fungicide treatments. However, the extensive application of fungicides to the soil increases residual detection frequency, raising concerns for the environment and human health. The bacterial volatile compound, 2,3-butanediol (BDO), was found to induce plant resistance. In this study, we evaluated the disease control efficacy of a combination of stereoisomers of 2,3-BDO and commercial fungicides against turfgrass fungal diseases in both growth room and fields. In the growth room experiment, the combination of 0.9% 2R,3R-BDO (levo) soluble liquid (SL) formulation and 9% 2R,3S-BDO (meso) SL with half concentration of fungicides significantly increased the disease control efficacy against dollar spot and summer patch disease when compared to the half concentration of fungicide alone. In field experiments, the disease control efficiency of levo 0.9% and meso 9% SL, in combination with a fungicide, was confirmed against dollar spot and large patch disease. Additionally, the induction of defense-related genes involved in the salicylic acid and jasmonic acid/ethylene signaling pathways and reactive oxygen species detoxification-related genes under Clarireedia sp. infection was confirmed with levo 0.9% and meso 9% SL treatment in creeping bentgrass. Our findings suggest that 2,3-BDO isomer formulations can be combined with chemical fungicides as a new integrated tool to control Clarireedia sp. infection in turfgrass, thereby reducing the use of chemical fungicides.

Nematicidal Activity of Grammicin Biosynthesis Pathway Intermediates in Xylaria grammica KCTC 13121BP against Meloidogyne incognita.

Grammicin, a polyketide metabolite produced by the endolichenic fungus Xylaria grammica KCTC 13121BP, shows strong nematicidal activity against Meloidogyne incognita. This study was performed to elucidate the grammicin biosynthesis pathway of X. grammica KCTC 13121BP and to examine the nematicidal activity of the biosynthesis intermediates and derivatives against M. incognita. Two grammicin biosynthesis intermediates were isolated from a T-DNA insertion transformant (strain TR-74) of X. grammica KCTC 13121BP and identified as 2-(hydroxymethyl)cyclohexa-2,5-diene-1,4-dione (compound 1) and 2,5-dihydroxybenzaldehyde (compound 2), which were also reported to be intermediates in the biosynthesis pathway of patulin, an isomer of grammicin. This indicates that the grammicin biosynthesis pathway overlaps almost with that of patulin, except for the last few steps. Among 13 grammicin biosynthesis intermediates and their derivatives (except grammicin), toluquinol caused the highest M. incognita J2 mortality, with an LC50/72 h value of 11.13 µg/mL, which is similar to grammicin with an LC50/72 h value of 15.95 µg/mL. In tomato pot experiments, the wettable powder type formulations (WP) of toluquinol (17.78 µg/mL) and grammicin (17.78 µg/mL) also effectively reduced gall formation on the roots of tomato plants with control values of 72.22% and 77.76%, respectively, which are much higher than abamectin (16.67%), but lower than fosthiazate (100%). The results suggest that toluquinol can be used directly as a biochemical nematicide or as a lead molecule for the development of new synthetic nematicides for the control of root-knot nematode diseases.

Phytochemicals-induced hormesis protects Caenorhabditis elegans against α-synuclein protein aggregation and stress through modulating HSF-1 and SKN-1/Nrf2 signaling pathways.

Mild stress activates the adaptive cellular response for the subsequent severe stress called hormesis. Hormetic stress plays a vital role to activate multiple stress-responsive genes for the benefit of an organism. In tropical regions of world, tubers of Dioscorea spp. has been extensively used in folk medicine and also consumed as food. In this study, we report that the phytochemicals of Dioscorea alata L., tubers extends the lifespan of nematode model Caenorhabditis elegans by hormetic mechanism. We showed that the low dose of tubers extract at 200 and 300 µg/mL extends the mean lifespan of wild-type worms, whereas higher doses are found to be toxic. Supplementation of tubers extract slightly increased the intracellular ROS in second-day adult worms and it might activate the adaptive stress response, which protects the worms from oxidative and thermal stress. Transgenic reporter gene expression assay showed that extract treatment enhanced the expression of stress protective genes such as hsp-16.2, hsp-6, hsp-60 and gst-4. Further studies proved that the transcription factors HSF-1 and SKN-1/Nrf2 were implicated in hormetic stress response of the worms. Moreover, pretreatment of extract reduced the high glucose-mediated lipid accumulation by enhancing the expression of glyoxalase-1. It was also found that the aggregation of Parkinson's related protein α-synuclein reduced in the transgenic strain NL5901 and extended its lifespan. Finally, our results concluded that the presences of hormetic dietary phytochemicals in tubers might drive the stress response in C. elegans via HSF-1 and SKN-1/Nrf2 signaling pathways.