Development of a Monoclonal scFv against Cytotoxin to Neutralize Cytolytic Activity Induced by Naja atra Venom on Myoblast C2C12 Cells

The Taiwanese cobra, Naja atra, is a clinically significant species of snake observed in the wild in Taiwan. Victims bitten by N. atra usually experience severe pain and local tissue necrosis. Although antivenom is available for treatment of cobra envenomation, its neutralization potency against cobra-induced necrosis is weak, with more than 60% of cobra envenoming patients developing tissue necrosis after antivenom administration. The present study found that cytotoxin (CTX) is a key component of N. atra venom responsible for cytotoxicity against myoblast cells. Anti-CTX IgY was generated in hens, and the spleens of these hens were used to construct libraries for the development of single chain variable fragments (scFv). Two anti-CTX scFv, S1 and 2S7, were selected using phage display technology and biopanning. Both polyclonal IgY and monoclonal scFv S1 reacted specifically with CTX in cobra venom. In a cell model assay, the CTX-induced cytolytic effect was inhibited only by monoclonal scFv S1, not by polyclonal IgY. Moreover, the neutralization potency of scFv S1 was about 3.8 mg/mg, approximately three times higher than that of conventional freeze-dried neurotoxic antivenom (FNAV). Collectively, these results suggest that scFv S1 can effectively neutralize CTX-induced cytotoxicity and, when combined with currently available antivenom, can improve the potency of the latter, thereby preventing tissue damage induced by cobra envenoming.

Dissecting the Transcriptomes of Multiple Metronidazole-Resistant and Sensitive Trichomonas vaginalis Strains Identified Distinct Genes and Pathways Associated with Drug Resistance and Cell Death

Trichomonas vaginalis is the causative agent of trichomoniasis, the most prevalent non-viral sexually transmitted infection worldwide. Metronidazole (MTZ) is the mainstay of anti-trichomonal chemotherapy; however, drug resistance has become an increasingly worrying issue. Additionally, the molecular events of MTZ-induced cell death in T. vaginalis remain elusive. To gain insight into the differential expression of genes related to MTZ resistance and cell death, we conducted RNA-sequencing of three paired MTZ-resistant (MTZ-R) and MTZ-sensitive (MTZ-S) T. vaginalis strains treated with or without MTZ. Comparative transcriptomes analysis identified that several putative drug-resistant genes were exclusively upregulated in different MTZ-R strains, such as ATP-binding cassette (ABC) transporters and multidrug resistance pumps. Additionally, several shared upregulated genes among all the MTZ-R transcriptomes were not previously identified in T. vaginalis, such as 5′-nucleotidase surE and Na⁺-driven multidrug efflux pump, which are a potential stress response protein and a multidrug and toxic compound extrusion (MATE)-like protein, respectively. Functional enrichment analysis revealed that purine and pyrimidine metabolisms were suppressed in MTZ-S parasites upon drug treatment, whereas the endoplasmic reticulum-associated degradation (ERAD) pathway, proteasome, and ubiquitin-mediated proteolysis were strikingly activated, highlighting the novel pathways responsible for drug-induced stress. Our work presents the most detailed analysis of the transcriptional changes and the regulatory networks associated with MTZ resistance and MTZ-induced signaling, providing insights into MTZ resistance and cell death mechanisms in trichomonads.

Efficient spin-light emitting diodes based on InGaN/GaN quantum disks at room temperature: a new self-polarized paradigm

A well-behaved spin-light emitting diode (LED) composed of InGaN/GaN multiple quantum disks (MQDs), ferromagnetic contact, and Fe3O4 nanoparticles has been designed, fabricated, and characterized. The degree of circular polarization of electroluminescence (EL) can reach up to a high value of 10.9% at room temperature in a low magnetic field of 0.35 T, which overcomes a very low degree of spin polarization in nitride semiconductors due to the weak spin-orbit interaction. Several underlying mechanisms play significant roles simultaneously in this newly designed device for the achievement of such a high performance. Most of all, the vacancy between nanodisks can be filled by half-metal nanoparticles with suitable energy band alignment, which enables selective transfer of spin polarized electrons and holes and leads to the enhanced output spin polarization of LED. Unlike previously reported mechanisms, this new process leads to a weak dependence of spin relaxation on temperature. Additionally, the internal strain in planar InGaN/GaN multiple quantum wells can be relaxed in the nanodisk formation process, which leads to the disappearance of Rashba Hamiltonian and enhances the spin relaxation time. Our approach therefore opens up a new route for the further research and development of semiconductor spintronics.