The relationship between oxidative stress and longevity is a matter of concern in various organisms. We isolated mutants resistant to paraquat from nematode Caenorhabditis elegans. One mutant named mev-4 was longlived and showed cross-resistance to heat and Dyf phenotype (defective in dye filling). Genetic and sequence analysis revealed that mev-4 had a nonsense mutation on the che-11 gene, homologues of which are involved in formation of cilia and flagella in other organisms. The paraquat resistance was commonly observed in various Dyf mutants and did not depend on the daf-16 gene, whereas the extension of life span did depend on it. Expression of antioxidant enzyme genes seemed normal. These results suggest that chemosensory neurons are a target of oxidative stress and influence longevity dependent on the daf-16 signaling in C. elegans.The life spans of animals are determined by both environmental and genetic parameters. Accumulating evidence in model organisms demonstrates the importance of genetic approaches with the findings that single gene mutations affect the life span in nematode Caenorhabditis elegans, fruit fly Drosophila melanogaster, and laboratory mice. The key to understanding longevity seems to lie in the network of cell maintenance systems that reduce accumulation of deleterious stresses. The life span of nematodes is controlled by the insulin-like signals from the nervous system (1-3). Such signals also seem to control life span of the fruit fly and mice (4 -7). These results suggest that neuroendocrine pathways in the neurons constitute an important determinant of life span across phylogeny (8 -11).Various lines of evidence show that oxidative stress is a major damaging factor accelerating aging (12, 13). It is invoked by reactive oxygen species (ROS) 1 generated as chemical byproducts of normal cellular metabolisms. Caloric restriction is shown to be beneficial in decreasing the production of ROS in metabolic pathways such as the mitochondrial electron transport system (13). Animals have evolved defense mechanisms against ROS; antioxidant enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase work to eradicate ROS as a first aid (14). However, much remains to be understood as regards the defense mechanisms in diverse tissues of vertebrates. To facilitate understanding of the mechanisms, C. elegans and D. melanogaster are frequently used as a multi-cellular model organism because powerful genetic analysis is possible.In C. elegans, longevity is affected by particular genes involved in dauer larvae formation (15-17), stress resistance (18 -24), mitochondrial function (25-28), caloric restriction (29), reproduction (30 -32), sensory perception (33), neurosecretory function (34), and chromatin silencing (35). Although multiple factors seem to be involved in the longevity, there exist a positive relationship between the capacity to resist oxidative stress and the longevity (12). Nonetheless, the target of oxidative stress is yet to be understood even in this model organis...
Hematopoietic stem cells (HSCs) are the source of all blood cells over an individual’s lifetime. Diseased HSCs can be replaced with gene-engineered or healthy HSCs through HSC transplantation (HSCT). However, current protocols carry major side effects and have limited access. We developed CD117/LNP–messenger RNA (mRNA), a lipid nanoparticle (LNP) that encapsulates mRNA and is targeted to the stem cell factor receptor (CD117) on HSCs. Delivery of the anti–human CD117/LNP–based editing system yielded near-complete correction of hematopoietic sickle cells. Furthermore, in vivo delivery of pro-apoptotic PUMA (p53 up-regulated modulator of apoptosis) mRNA with CD117/LNP affected HSC function and permitted nongenotoxic conditioning for HSCT. The ability to target HSCs in vivo offers a nongenotoxic conditioning regimen for HSCT, and this platform could be the basis of in vivo genome editing to cure genetic disorders, which would abrogate the need for HSCT.
The entire and partial gag regions of human immunodeficiency virus type 1 (HIV-1) were overproduced in Escherichia coli and used for epitope mapping of antibodies against p17. We found that a mouse monoclonal antibody to p17, V17 recognizes the mature p17 but not the unprocessed Gag proteins containing the entire p17 moiety. Further analysis revealed that V 17 recognizes the C-terminal 12-amino-acid region of p17 having free C-terminus. This monoclonal antibody may be useful for monitoring the maturation of virus particles.
A simple method for the overproduction in Escherichia coli and purification of major core protein p24 of human immunodeficiency virus type 1 (HIV-1) was described. The gag-pol region encoding p24, p15, and protease was fused to 3' end of lacZ gene on plasmid. A LacZ-Gag fusion protein, the major primary product, is designed to be cleaved by the HIV-1 protease coexpressed through frameshifting. In fact, p24 and its immediate precursor, p25, were produced in the cells grown at 25 C, but not at 37 C. When the gag and pol frames were fused in-frame to express the protease without frameshifting, the main product, a LacZ-Gag-Pol fusion protein, was efficiently processed to give p24 exclusively both at 37 C and 25 C, suggesting more efficient expression of the protease. Recombinant p24 was purified to near homogeneity by a simple three-step procedure. The amino-terminal sequence of the recombinant p24 was the same as that of p24 deduced from nucleotide sequence, indicating that correct processing occurred in E. coli by the coexpressed protease. The method described here provides a means to obtain a large amount of highly pure p24, which is useful for crystallographic and functional studies, preparation of specific antibody, and diagnostic and prognostic uses.
To analyze the relationship between resistance to oxidative stress and longevity, we isolated three novel paraquat-resistant mutants, mev-5, mev-6, and mev-7, from the nematode Caenorhabditis elegans. They all showed the Dyf (defective in dye filling) phenotype, but not always resistance to heat or UV. Life-span extension was observed only in the mev-5 mutant at 26 C. These results indicate that longevity is uncoupled with the phenotype of paraquat resistance.Key words: Caenorhabditis elegans; oxidative stress; paraquat; aging; Dyf A number of hypotheses have been presented to account for the mechanism of aging. The free radical hypothesis of aging was first mentioned by Harman in the mid-1950s, 1) and since then has drawn much attention. Among the free radicals, reactive oxygen species (ROS) are most notable because they are generated in normal metabolic processes and damage cellular components such as proteins, DNA, and lipids. The resulting damage is thought to cause cellular dysfunction and eventually to lead to senescence. Animals have evolved various defense mechanisms against ROS, 2) but they appear to be far from perfect. Accumulating genetic evidence from model organisms such as the nematode, fruit fly, and mouse indicates a positive relationship between the longevity of mutant individuals and their capacity to resist oxidative stress. 3)But, much remains to be elucidated as regards defense mechanisms against ROS even in model organisms.To assess the above relationship, we employed genetic analysis using the nematode C. elegans as a model system, because it has been proved to be extremely useful for identifying responsible genes in mutants. We used paraquat (methyl viologen), which generates superoxide anions in cells, as an agent to isolate mutants with resistance to oxidative stress. 4) We mutagenized wild-type N2 worms with ethyl-methansulfonate and screened them by resistance to paraquat.We isolated three novel mutants, designated mev-5 (qa5005), mev-6 (qa5006), and mev-7 (qa5007). Their paraquat-resistant traits were all recessive and inherited by progeny in a Mendelian fashion. Their mutations were cleaned by back-crossing to N2 worms five times for subsequent analysis. Genetic analysis revealed that mev-5, mev-6, and mev-7 were concordant with the genetic markers dpy-11, dpy-1, and dpy-5 located on LG V, III, and I respectively. To map the genes regionally, three-factor-cross experiments were carried out, and the following results were obtained: mev-5 (4/4) (rol-4 unc-76), unc-42 (3/6) mev-5 (3/6) lon-3, (unc-45 dpy-1) (9/ 9) mev-6, dpy-1 (3/9) mev-6 (6/9) unc-32, dpy-1 (3/14) mev-6 (11/14) unc-93, (dpy-5 unc-37) (5/5) mev-7, dpy-14 (8/12) mev-7 (4/12) unc-29, mev-7 (7/7) (unc-29 dpy-24), (unc-40 bli-4) (2/2) mev-7 (Fig. 1A).Sensitivity to paraquat in the mev-mutants was determined as described previously.5) In brief, eggs were placed and incubated on plates containing various concentration of paraquat for 5 d, and the percentage of worms that reached adulthood was determined. Wildtype N2 worms h...
Rabies is a zoonotic disease caused by the rabies virus. While the salivary glands are important as exit and propagation sites for the rabies virus, the mechanisms of rabies excretion remain unclear. Here, we investigated the histopathology of the salivary glands of rabid dogs and analyzed the mechanism of excretion into the oral cavity. Mandibular and parotid glands of 22 rabid dogs and three control dogs were used. Mild to moderate non-suppurative sialadenitis was observed in the mandibular glands of 19 of the 22 dogs, characterized by loss of acinar epithelium and infiltration by lymphoplasmacytic cells. Viral antigens were detected in the mucous acinar epithelium, ganglion neurons and myoepithelium. Acinar epithelium and lymphocytes were positive for anti-caspase-3 antibodies and TUNEL staining. In contrast, no notable findings were observed in the ductal epithelial cells and serous demilune. In the parotid gland, the acinar cells, myoepithelium and ductal epithelium all tested negative. These findings confirmed the path through which the rabies virus descends along the facial nerve after proliferation in the brain to reach the ganglion neurons of the mandibular gland, subsequently traveling to the acinar epithelium via the salivary gland myoepithelium. Furthermore, the observation that nerve endings passing through the myoepithelium were absent from the ductal system suggested that viral proliferation and cytotoxicity could not occur there, ensuring that secretions containing the virus are efficiently excreted into the oral cavity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.