Dynamics of antibiotic resistance genes and the association with bacterial community during pig manure composting with chitin and glucosamine addition.

In modern ecological systems, the overuse and misuse of antibiotics have escalated the prevalence of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs), positioning them as emerging environmental contaminants. Notably, composting serves as a sustainable method to recycle agricultural waste into nutrient-rich fertilizer while potentially reducing ARGs and MGEs. This study conducted a 47-day composting experiment using pig manure and corn straw, supplemented with chitin and N-Acetyl-D-glucosamine, to explore the impact of these additives on the dynamics of ARGs and MGEs, and to unravel the interplay between these genetic elements and microbial communities in pig manure composting. Results showed that adding 5% chitin into composting significantly postponed thermophilic phase, yet enhanced the removal efficiency of total ARGs and MGEs by over 20% compared to the control. Additionally, the addition of N-Acetyl-D-glucosamine significantly increased the abundance of tetracycline-resistant and sulfonamide-resistant genes, as well as MGEs. High-throughput sequencing revealed that N-Acetyl-D-glucosamine enhanced bacterial α-diversity, providing diverse hosts for ARGs and MGEs. Resistance mechanisms, predominantly efflux pumps and antibiotic deactivation, played a pivotal role in shaping the resistome of composting process. Co-occurrence network analysis identified the key bacterial phyla Proteobacteria, Firmicutes, Gemmatimonadota, and Myxococcota in ARGs and MGEs transformation and dissemination. Redundancy analysis indicated that physicochemical factors, particularly the carbon-to-nitrogen ratio emerged as critical variables influencing ARGs and MGEs. The findings lay a foundation for the developing microbial regulation method to reduce the risks of ARGs in animal manure composts.

Serotonin regulates maternal calcium homeostasis during the perinatal period of sheep.

The goal of this experiment was to demonstrate the ability of an infusion of serotonin (5-HT; 5-hydroxytryptamine) precursors to increase 5-HT production during the transition from pregnancy to lactation and its effects on gene expression related to calcium (Ca) transporters in the mammary gland and bone resorption markers in the femur. Thirty pregnant Bamei mutton sheep were randomly assigned to 3 experimental groups. All groups received a daily intravenous infusion of saline (control group; n = 10), saline containing 0.178 mg of L-tryptophan/kg body weight (BW) (TRP group, n = 10) or 0.178 mg of 5-hydroxytryptophan/kg BW (5-HTP group, n = 10), beginning on day 7 of prepartum and continuing until delivery. Serum (pre- and postpartum), milk (postpartum), and femur and mammary gland tissue (day 9) were collected. Sheep infused with 5-HTP had a larger total serum Ca concentration on days 3, 6, 15, and 30 of lactation and total milk Ca concentration on days 3, 6, 12, and 15 of lactation compared with that of the control group. Sheep infused with 5-HTP and TRP increased blood and milk concentrations of 5-HT on days 3, 6, 9, and 30 of lactation and parathyroid hormone-related protein (PTHrP) on day 3 of prepartum and on days 3, 6, and 15 of lactation (P < 0.05). In addition, compared to that of the control group, the TRP or 5-HTP infusion upregulated PTHrP, a sodium/calcium exchanger, plasma membrane Ca2+ ATPase 2, secretory pathway Ca2+ ATPase 1, and calcium sensing receptor mRNA expression in mammary gland and receptor-activated nuclear factor kappa-B ligand mRNA expression in the femur, but had no effect on receptor-activated nuclear factor kappa-B and osteoprotegerin mRNA expression in the femur (P < 0.05). This suggests that 5-HT and PTHrP may be involved in regulating maternal Ca homeostasis during the transition from pregnancy to lactation in the sheep.

In vitro and in vivo radiosensitization of colorectal cancer HT-29 cells by the smac mimetic JP-1201.

BACKGROUND: The response to neoadjuvant chemoradiation in rectal cancer is variable and unpredictable. Resistance to chemoradiation has been directly correlated with the levels of the inhibitors of apoptosis (IAPs) in several malignancies. Because smac-DIABLO is a pro-apoptotic gene product that directly inhibits the activity of the IAPs, molecules with similar activity might radiosensitize rectal tumors with phenotypes that express high levels of IAPs. This study was undertaken to assess the radiosensitizing properties of the smac mimetic JP-1201 in radioresistant HT-29 colorectal cancer cells in vitro and established xenografts in SCID mice. METHODS: Survival was determined by clonogenic assays. PARP-1, caspase-8 cleavage, and IAP levels were assessed by Western blot analysis. SCID mice bearing HT-29 xenografts were treated with ionizing radiation: 2.0 Gy x 5; (n = 6), JP-1201 (5.0 mg/Kg i.p., n = 5) or combination treatment (n = 7) and compared to control (n = 8). DNA repair mechanisms were interrogated by gammaH2AX positive foci. RESULTS: Pretreatment of HT-29 cells with JP-1201 (5.0 microM) prior to ionizing radiation (IR) significantly decreased the survival of these cells. SCID mice bearing HT-29 xenografts demonstrated no difference in tumor load in the group receiving exclusively JP-1201 versus control. At the end of the treatment (day 40), a 46% reduction of tumor load was observed in the IR+JP-1201-treated group compared to the IR-only treated group. Radiosensitization was achieved with a substantial elevation of cleaved PARP-1 in JP-1201- treated HT-29 cells versus control cells with a concomitant decrease of XIAP, but not of survivin or cIAP1/2. JP-1201-treated HT-29 cells had a reduced ability to repair double-stranded DNA breaks (DSBs). CONCLUSION: The smac mimetic JP-1201 decreased the survival of HT-29 cells and tumor growth by an additive effect in apoptosis and a reduction in the level of XIAP and an impairment of DNA repair mechanisms. The pathways leading to this response need to be further investigated.

Smac mimetic increases chemotherapy response and improves survival in mice with pancreatic cancer.

Failure of chemotherapy in the treatment of pancreatic cancer is often due to resistance to therapy-induced apoptosis. A major mechanism for such resistance is the expression and activity of inhibitors of apoptosis proteins (IAP). Smac (second mitochondria-derived activator of caspase) is a mitochondrial protein that inhibits IAPs. We show that JP1201, a Smac mimetic, is a potent enhancer of chemotherapy in robust mouse models of pancreatic cancer. Combination of JP1201 with gemcitabine reduced primary and metastatic tumor burden in orthotopic xenograft and syngenic tumor models, induced regression of established tumors, and prolonged survival in xenograft and transgenic models of pancreatic cancer. The effect of JP1201 was phenocopied by XIAP small interfering RNA in vitro and correlated with elevated levels of tumor necrosis factor alpha protein in vivo. The continued development of JP1201 and other strategies designed to enhance therapy-induced apoptosis in pancreatic cancer is warranted.

Building functionalized peptidomimetics: use of electroauxiliaries for introducing N-acyliminium ions into peptides.

A series of silyl-substituted amino acids have been synthesized, inserted into peptides, and then employed as precursors for oxidatively generating reactive N-acyliminium ions. Both electrochemical and chemical oxidation procedures have been employed. N-Acyliminium ion generation in a solid-phase substrate as well as application to a small library of functionalized dipeptides has been demonstrated. Limitations in terms of how electron-rich the silyl groups can be as well as the compatibility of multiple silyl groups within a longer peptide are defined.

Building functionalized peptidomimetics: new electroauxiliaries and the use of a chemical oxidant for introducing N-acyliminium ions into peptides.

[reaction: see text] The removal of electroauxiliaries from peptide substrates with chemical oxidants has been examined as a method for inserting N-acyliminium ions into the peptides. To this end, it was found that both 4-methoxyphenyldimethylsilyl and 2,4-dimethoxyphenyldimethylsilyl electroauxiliaries were readily cleaved with the use of ceric ammonium nitrate. Of the two groups, the 2,4-dimethoxyphenyldimethylsilyl electroauxiliary was the most labile under the oxidative conditions. The oxidation reactions were shown to be compatible with the use of a solid-phase substrate.

Silyl-substituted amino acids: new routes to the construction of selectively functionalized peptidomimetics.

[reaction: see text]. Silylated amino acids have been incorporated into peptides and then converted into N-acyliminium ions with the use of an anodic oxidation reaction. The result is a method for selectively incorporating conformational constraints or external nucleophiles within the peptide.