Insights into the alleviation of cadmium toxicity in rice by nano-zinc and Serendipita indica: Modulation of stress-responsive gene expression and antioxidant defense system activation.

The adversities of cadmium (Cd) contamination are quite distinguished among other heavy metals (HMs), and so is the efficacy of zinc (Zn) nutrition in mitigating Cd toxicity. Rice (Oryza sativa) crop, known for its ability to absorb HMs, inadvertently facilitates the bioaccumulation of Cd, posing a significant risk to both the plant itself and to humans consuming its edible parts, and damaging the environment as well. The use of nanoparticles, such as nano-zinc oxide (nZnO), to improve the nutritional quality of crops and combat the harmful effects of HMs, have gained substantial attention among scientists and farmers. While previous studies have explored the individual effects of nZnO or Serendipita indica (referred to as S.i) on Cd toxicity, the synergistic action of these two agents has not been thoroughly investigated. Therefore, the gift of nature, i.e., S. indica, was incorporated alongside nZnO (50 mg L-1) against Cd stress (15 µM L-1) and their alliance manifested as phenotypic level modifications in two rice genotypes (Heizhan43; Hz43 and Yinni801; Yi801). Antioxidant activities were enhanced, specifically peroxidase (61.5 and 122.5% in Yi801 and Hz43 roots, respectively), leading to a significant decrease in oxidative burst; moreover, Cd translocation was reduced (85% for Yi801 and 65.5% for Hz43 compared to Cd alone treatment). Microstructural study showed a decrease in number of vacuoles and starch granules with ameliorative treatments. Overall, plants treated with nZnO displayed gene expression pattern (particularly of ZIP genes), different from the ones with alone or combined S.i and Cd. Inferentially, the integration of nZnO and S.i holds great promise as an effective strategy for alleviating Cd toxicity in rice plants. By immobilizing Cd ions in the soil and promoting their detoxification, this novel approach contributes to environmental restoration and ensures food safety worldwide.

A hydrogel gripper enabling fine movement based on spatiotemporal mineralization.

Fine tailoring of the subtle movements of a hydrogel actuator through simple methods has widespread application prospects in wearable electronics, bionic robots and biomedical engineering. However, to the best of our knowledge, this challenge is not yet completed. Inspired by the diffusion-reaction process in nature, a hydrogel gripper with the capability of fine movement was successfully prepared based on the spatiotemporal fabrication of the polypyrrole (PPY) pattern in a poly (N-isopropylacrylamide) (PNIPAM) hydrogel. The hydrogel was given gradient porous structures using a one-step UV irradiation method. Moreover, photothermal PPY patterns on the hydrogel were obtained through spatiotemporal mineralization of ferric hydroxide followed by the polymerization of pyrrole in a controllable manner. Taking advantage of the unique structures, the hydrogel gripper can not only achieve reversible grasping-releasing of substrates with the tuning of temperature (similar to that of hands), but also generate delicate movement under the irradiation of light (resembling that of finger joints). The strategy reported here is easily accessible and there is no need for sophisticated templates, therefore making it superior to other existing methods. We believe this work will provide references for the design and application of more advanced soft actuators.

Phosphorus and Serendipita indica synergism augments arsenic stress tolerance in rice by regulating secondary metabolism related enzymatic activity and root metabolic patterns.

The multifarious problems created by arsenic (As), for collective environment and human health, serve a cogent case for searching integrative agricultural approaches to attain food security. Rice (Oryza sativa L.) acts as a sponge for heavy metal(loid)s accretion, specifically As, due to anaerobic flooded growth conditions facilitating its uptake. Acclaimed for their positive impact on plant growth, development and phosphorus (P) nutrition, 'mycorrhizas' are able to promote stress tolerance. Albeit, the metabolic alterations underlying Serendipita indica (S. indica; S.i) symbiosis-mediated amelioration of As stress along with nutritional management of P are still understudied. By using biochemical, RT-qPCR and LC-MS/MS based untargeted metabolomics approach, rice roots of ZZY-1 and GD-6 colonized by S. indica, which were later treated with As (10 µM) and P (50 µM), were compared with non-colonized roots under the same treatments with a set of control plants. The responses of secondary metabolism related enzymes, especially polyphenol oxidase (PPO) activities in the foliage of ZZY-1 and GD-6 were enhanced 8.5 and 12-fold, respectively, compared to their respective control counterparts. The current study identified 360 cationic and 287 anionic metabolites in rice roots, and the commonly enriched pathway annotated by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was biosynthesis of phenylalanine, tyrosine and tryptophan, which validated the results of biochemical and gene expression analyses associated with secondary metabolic enzymes. Particularly under As+S.i+P comparison, both genotypes exhibited an upregulation of key detoxification and defense related metabolites, including fumaric acid, L-malic acid, choline, 3,4-dihydroxybenzoic acid, to name a few. The results of this study provided the novel insights into the promising role of exogenous P and S. indica in alleviating As stress.

Study on the inhibition mechanism of eucalyptus tannins against Microcystis aeruginosa.

Microcystis aeruginosa is the competitively dominant algal species in eutrophic waters and poses a serious threat to the aquatic ecological environment. To investigate the effects of eucalyptus tannins (TFL) and black water in eucalyptus plantations on M. aeruginosa, this study exposed M. aeruginosa to different concentrations (0 (control), 20, 50, 80, 110, and 140 mg L-1) of tannic acid (TA; hydrolyzed tannins, HT; reagent tannin), epigallocatechin gallate (EGCG; condensed tannins, CT; reagent tannin), eucalyptus tannins (TFL, complex tannin) and mixed TFL + Fe3+ solution (tannin: Fe3+ molar ratio = 1:10). The cell density, chlorophyll-a (Chl-a) content, superoxide dismutase (SOD) activity, malondialdehyde (MDA) and soluble protein (SP) contents of algae under tannin stress were determined, and the algal cell density treated with under the combination of TFL and Fe3+ was determined. The results showed a reduction in the Chl-a content of algal cells, which inhibited photosynthesis; leading to membrane lipid peroxidation; and the complexation of soluble proteins resulting in blocked protein synthesis were the main mechanisms by which tannins inhibited the growth of M. aeruginosa. TFL achieved the same inhibition of algal cells as the tannin reagent at the same concentration. At 4 d, TFL at 80 mg L-1 and above could achieve more than 54.87 % algal density inhibition. The inhibition rate of 80 mg L-1 and above TFL + Fe3+ on algal density was more than 75 %, indicating that TFL + Fe3+ had a stronger inhibitory effect on algal density. The results may facilitate the resource utilization of eucalyptus harvesting residues, explorations of the potential application of eucalyptus tannins in the control of M. aeruginosa, and provide new ideas for ecological algal inhibition in eucalyptus plantations.

Uterine infection alters the transcriptome of the bovine reproductive tract three months later.

Infection of the postpartum uterus with pathogenic bacteria is associated with infertility months later in dairy cattle. However, it is unclear whether these bacterial infections lead to long-term changes in the reproductive tract that might help explain this infertility. Here we tested the hypothesis that infusion of pathogenic bacteria into the uterus leads to changes in the transcriptome of the reproductive tract 3 months later. We used virgin Holstein heifers to avoid potential confounding effects of periparturient problems, lactation, and negative energy balance. Animals were infused intrauterine with endometrial pathogenic bacteria Escherichia coli and Trueperella pyogenes (n = 4) and compared with control animals (n = 6). Three months after infusion, caruncular and intercaruncular endometrium, isthmus and ampulla of the oviduct, and granulosa cells from ovarian follicles >8 mm diameter were profiled by RNA sequencing. Bacterial infusion altered the transcriptome of all the tissues when compared with control. Most differentially expressed genes were tissue specific, with 109 differentially expressed genes unique to caruncular endometrium, 57 in intercaruncular endometrium, 65 in isthmus, 298 in ampulla, and 83 in granulosa cells. Surprisingly, despite infusing bacteria into the uterus, granulosa cells had more predicted upstream regulators of differentially expressed genes than all the other tissues combined. In conclusion, there were changes in the transcriptome of the endometrium, oviduct and even granulosa cells, 3 months after intrauterine infusion of pathogenic bacteria. These findings imply that long-term changes throughout the reproductive tract could contribute to infertility after bacterial infections of the uterus.

A model of clinical endometritis in Holstein heifers using pathogenic Escherichia coli and Trueperella pyogenes.

Bacterial infection of the uterus causes clinical endometritis in 15 to 20% of postpartum dairy cows and reduces fertility, even after the resolution of disease. However, it is difficult to disentangle the mechanisms linking reduced fertility with endometritis because cows have multiple confounding postpartum conditions. The aim of the present experiment was to develop an in vivo model of clinical endometritis in Holstein heifers using pathogenic Escherichia coli and Trueperella pyogenes. Estrous cycles of heifers were synchronized using a 5-d Co-Synch protocol, and subsequently received exogenous progesterone to elevate circulating progesterone at the time of uterine infusion. Endometrial scarification was performed before uterine infusion of live pathogenic Escherichia coli and Trueperella pyogenes, or sterile vehicle. Effects of infusion were evaluated by measuring rectal temperature, plasma haptoglobin, hematology, grading pus in the vaginal mucus, quantifying 16S rRNA in vaginal mucus, and transrectal ultrasonography. Bacterial infusion increased the median vaginal mucus to grade 2 by d 3 postinfusion, and to grade 3 from d 4 to 6 postinfusion. Control heifers maintained a median vaginal mucus grade ≤1 from d 1 to 6. Transrectal ultrasound revealed the accumulation of echogenic fluid in the uterus of heifers following bacterial infusion, which was absent in control heifers. Total 16S rRNA in vaginal mucus was elevated in bacteria-infused heifers compared with control heifers at d 5. Rectal temperature was increased in bacteria-infused heifers. Plasma haptoglobin, general health, and appetite did not differ between groups. As indicated by increased vaginal mucus grade after bacterial infusion and absence of systemic signs of illness, this model successfully induced symptoms resembling clinical endometritis in virgin Holstein heifers. The model allows the isolation of effects of uterine disease on fertility from confounding factors that can occur during the postpartum period in dairy cows.

Comprehensive in vitro and in vivo risk assessments of chitosan microparticles using human epithelial cells and Caenorhabditis elegans.

The safety of using nano- and microparticles is a developing concern. In this study, we conducted risk assessments of chitosan microparticles (CMs) using in vitro human epithelial cell lines and in vivo animal model, Caenorhabditis elegans. After engineering of various CMs, we screened four CMs based on antimicrobial activity, which is a potential usage for disease treatment caused by multidrug resistant bacteria, and evaluated for risk assessments. CMs, with strong antimicrobial activity, and inorganic nanoparticles (SiO2, TiO2, and ZnO) did not cause toxicity in human cells measured by cell membrane integrity, mitochondria activity, and reactive oxygen species concentration. However, when applied to C. elegans, only CMs generated with low molecular weight chitosan and tripolyphosphate at 0.1% did not affect the lifespan, while the other CMs and inorganic nanoparticles shortened the lifespan, suggesting that they may cause subtle toxicity. These results suggest that C. elegans could be a sensitive animal model to measure low level of toxicity of nano- and microparticles. Taken together, although CMs do not cause toxicity at working concentrations of antimicrobial activity in human epithelial cells, they may cause toxicity at high concentration, suggesting that nano- and microparicles should be thoroughly investigated before they are applied.