Alteration of the hydrogen-bond (H-bond) network by trehalose is acknowledged as a bioprotective agent. However, most studies exploring the hydration superiority of the trehalose structure are ...limited structure are limited by the computational cost or a narrow-range spectrum. In the present study, the structural and dynamical behaviors of the H-bond network of trehalose and maltose solutions were observed and compared with a broadband dielectric spectrum (100 MHz–18 THz) to investigate the influence of the trehalose structure on the bioprotective function. From the relaxation time, the reorientation cooperativity, resonant frequency, and damping constant of water–water vibration, the symmetric structure of trehalose allowed a more significant H-bond strengthening effect and homogeneous aqueous environment. In contrast, the difference in the hydration number between trehalose and maltose was negligible. Thus, the enhanced H-bond strengthening effect and homogeneous aqueous environment owing to the symmetric structure are the essential factors that contribute to the remarkable bioprotective effect of trehalose.
Electron microscopy (EM) offers unparalleled power to study cell substructures at the nanoscale. Cryofixation by high-pressure freezing offers optimal morphological preservation, as it captures ...cellular structures instantaneously in their near-native state. However, the applicability of cryofixation is limited by its incompatibility with diaminobenzidine labeling using genetic EM tags and the high-contrast
staining required for serial block-face scanning electron microscopy (SBEM). In addition, it is challenging to perform correlated light and electron microscopy (CLEM) with cryofixed samples. Consequently, these powerful methods cannot be applied to address questions requiring optimal morphological preservation. Here, we developed an approach that overcomes these limitations; it enables genetically labeled, cryofixed samples to be characterized with SBEM and 3D CLEM. Our approach is broadly applicable, as demonstrated in cultured cells,
olfactory organ and mouse brain. This optimization exploits the potential of cryofixation, allowing for quality ultrastructural preservation for diverse EM applications.
The yellow catfish (
P. fulvidraco
), as one of the economically-relevant freshwater fish found in China, cannot tolerate cold stress. Understanding the physiological and biochemical mechanisms under ...cold stress may provide insights for improving yellow catfish management in the cold. Therefore, we investigated the metabolic and intestinal microbiota changes in cold stress in response to induced cold stress. We found that cold stress in yellow catfish lead to a significant increase in the consumption of glucose and triglycerides, as well as increased use of cholesterol as an alternate energy source. Moreover, cold stress also activated several significant biological processes in the fish such as thermogenesis, oxidative phosphorylation, the spliceosome machinery, RNA transport, protein processing that occurs in the ER, and purine and pyrimidine metabolism pathways involved in energy production. On the other hand, many other mechanisms like insulin resistance, starch and sucrose metabolism, and the glyoxylate and dicarboxylate metabolic pathways that also served as energy production pathways were weakened. Furthermore, organic acids and their derivatives as well as the lipids and lipid-like molecules were mainly altered in cold stress; prenol lipids, steroids, and their derivatives were significantly upregulated, while fatty acyls and glycerophospholipids were significantly downregulated. Transcriptomic and metabolomic integrated analysis data revealed that carbohydrate metabolism, lipid metabolism, amino acid metabolism, and nucleotide metabolism were involved in cold stress resistance. In addition, the intestinal microbiota abundance was also reduce and the pathogenic bacteria of plesiomonas was rapidly appreciation, which suggesting that cold stress also impaired intestinal health. This research study could offer insights into winter management or the development of feed to promote cold resistance in yellow catfish.
The binding and interaction of proteins with nucleic acids such as DNA and RNA constitutes a fundamental biochemical and biophysical process in all living organisms. Identifying and visualizing such ...temporal interactions in cells is key to understanding their function. To image sites of these events in cells across scales, we developed a method, named PROMPT for PROximal Molecular Probe Transfer, which is applicable to both light and correlative electron microscopy. This method relies on the transfer of a bound photosensitizer from a protein known to associate with specific nucleic acid sequence, allowing the marking of the binding site on DNA or RNA in fixed cells. The method produces a fluorescent mark at the site of their interaction, that can be made electron dense and reimaged at high resolution in the electron microscope. As proof of principle, we labeled in situ the interaction sites between the histone H2B and nuclear DNA. As an example of application for specific RNA localizations we labeled different nuclear and nucleolar fractions of the protein Fibrillarin to mark and locate where it associates with RNAs, also using electron tomography. While the current PROMPT method is designed for microscopy, with minimal variations, it can be potentially expanded to analytical techniques.
The objective of this study was to investigate the effects of selenium yeast on the growth, histomorphology, antioxidant capacity and apoptosis of largemouth bass (Micropterus salmoide). The five ...iso-nitrogen and iso-lipid feeds were supplemented with selenium yeast levels of 0, 0.5, 1.0, 1.5 and 2.0 mg/kg, respectively. The 525 largemouth bass (initial body weight: 11.48 ± 0.43 g) were equally divided into 15 buckets (three buckets per feed treatment) for a 67-day feeding experiment. The results showed that the addition of 1.5 and 2.0 mg/kg of selenium yeast significantly reduced weight gain rate, and specific growth rate (P < 0.05), disorganized the structure of liver cells and exacerbated the vacuolation of liver tissue in largemouth bass. The activities of glutathione peroxidase and superoxide dismutase in serum were significantly increased by 1.0 mg/kg selenium yeast (P < 0.05). After selenium yeast was supplemented, villus length and villus width were significantly increased (P < 0.05), NO contents and respiratory burst activities in hematocyte were not significantly changed (P > 0.05). With the addition of 1.5 mg/kg of selenium yeast, the relative expression of growth hormone 1, insulin-like growth factor-1, superoxide dismutase, catalase, Kelch-like ECH-associating protein 1, and nuclear factor erythroid 2 related factor 2 in hematocyte was significantly increased (P < 0.05). The significantly lowest percentage of apoptotic hematocyte was also seen in the 1.5 mg/kg selenium yeast addition group (P < 0.05). Overall, the supplementation of 1.5 mg/kg selenium yeast was not conducive to the growth and liver development of largemouth bass, but it could improve the antioxidant capacity of hematocyte and inhibit the apoptosis. It provided a theoretical basis for the enhancement of immune capacity during the farming of largemouth bass.
•The addition of 1.5 and 2.0 mg/kg selenium yeast significantly reduced the growth of largemouth bass.•Addition of 1.0 mg/kg selenium yeast significantly improved the antioxidant capacity of serum.•The supplementation of 1.5 mg/kg selenium yeast improved the antioxidant capacity of hematocyte.•Supplementation with 1.5 mg/kg selenium yeast inhibited apoptosis of hematocyte.
Dominant missense mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common genetic causes of Parkinson disease (PD) and genome-wide association studies identify LRRK2 sequence variants ...as risk factors for sporadic PD. Intact kinase function appears critical for the toxicity of LRRK2 PD mutants, yet our understanding of how LRRK2 causes neurodegeneration remains limited. We find that most LRRK2 PD mutants abnormally enhance LRRK2 oligomerization, causing it to form filamentous structures in transfections of cell lines or primary neuronal cultures. Strikingly, ultrastructural analyses, including immuno-electron microscopy and electron microscopic tomography, demonstrate that these filaments consist of LRRK2 recruited onto part of the cellular microtubule network in a well-ordered, periodic fashion. Like LRRK2-related neurodegeneration, microtubule association requires intact kinase function and the WD40 domain, potentially linking microtubule binding and neurodegeneration. Our observations identify a novel effect of LRRK2 PD mutations and highlight a potential role for microtubules in the pathogenesis of LRRK2-related neurodegeneration.
A protein-fragment complementation assay (PCA) for detecting and localizing intracellular protein-protein interactions (PPIs) was built by bisection of miniSOG, a fluorescent flavoprotein derived ...from the light, oxygen, voltage (LOV)-2 domain of
Arabidopsis
phototropin. When brought together by interacting proteins, the fragments reconstitute a functional reporter that permits tagged protein complexes to be visualized by fluorescence light microscopy (LM), and then by standard as well as “multicolor” electron microscopy (EM) via the photooxidation of 3–3’-diaminobenzidine (DAB) and its derivatives.
Boassa et al. describe the use of split-miniSOG for the visualization of protein aggregates associated with neurodegenerative diseases. This study shows the general utility of this reversible system for detection of spatial organization of molecular complexes in mammalian cells at nanometer resolution.
Hydrogen (H2) gas is recognized for its anti-oxidative, anti-apoptotic, and anti-inflammatory properties in multiple plant and animal models. Nevertheless, there is a lack of research on the effects ...of H2 administration on fish. This research seeks to investigate how H2 administration affects the growth performance, mammalian target of rapamycin (mTOR) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways, and intestinal microbiota of juvenile largemouth bass under normal feeding conditions. The research randomly allocated 240 fish (3.55 ± 0.01 g) into two treatment groups, each comprising 4 replicate tanks with 30 fish per tank. The control group was maintained in regular water, while the experimental group (referred to as H2 group) was treated with H2-dissolved water for 1 h per day for 6 weeks. Upon analysis of both groups, it was revealed that the weight gain, final weight, feed intake, specific growth rate, and survival rate were significantly improved by H2 treatment (P < 0.05). In addition, administration of H2 significantly reduced the triglyceride content and increased the high-density lipoprotein-cholesterol content in the serum (P < 0.05). Moreover, administration of H2 led to a significant increase in the expression of genes associated with mTOR (PI3K, AKT, TOR, S6K1, and 4EBP1) and Nrf2 (Nrf2, SOD, and GPX) signaling pathways (P < 0.05). Furthermore, H2 significantly increased the expression of growth hormone receptor (GHR) and neuropeptide Y (NPY) genes in the brain of juvenile largemouth bass. H2 did not significantly affect intestinal histology. However, it significantly increased the relative abundance of Sulfuritalea, Bradyrhizobium, and norank_f__Beggiatoaceae (P < 0.05) and reduced the relative abundance of Brevundimonas, unclassified_o__Chlamydiales, and Delftia in the intestinal microbiota (P < 0.05). Thus, these results suggested that providing juvenile largemouth bass with H2-dissolved water for 1 h per day can lead to a significantly increasing in growth performance, stimulating feed intake, activating mTOR and Nrf2 signaling pathways, and augmenting the abundance of beneficial bacteria in the intestines of juvenile largemouth bass. These findings provided a valuable support for the H2 application in the largemouth bass healthy culture.
•Hydrogen (H2) can lead to a significantly increase in growth performance, stimulate feed intake and improve the related genes expression.•H2 significantly reduced the triglyceride content and increased the high-density lipoprotein-cholesterol content in the serum.•H2 led to a significant increase in the expression of genes associated with mTOR and Nrf2 signaling pathways.•H2 augment the abundance of beneficial bacteria in the intestines of juvenile largemouth bass.
Hydrogen-rich water (HRW) is widely recognized for its growth promoting, antioxidant, and anti-inflammatory properties. However, little is known about the role of HRW in aquaculture. This study aims ...to investigate how different concentrations of HRW affect the growth performance, digestive ability, antioxidant capacity, mTOR signaling pathway, and gut microbiota of juvenile largemouth bass. We randomly assigned 360 fish (13.73 ± 0.1 g) to three treatments. The control group was maintained in regular water, while the treatment groups were treated with different concentrations of H2 dissolved in water, which were H1 (179.65 ± 31.95 ppb) and H2 (280.65 ± 64.43 ppb), respectively. Through an analysis of the three treatments, it was found that H1 significantly increased the final body weight, weight gain rate, specific growth rate, and survival rate, and reduced the feed conversion ratio (p < 0.05). In addition, the trypsin activity was significantly increased in the intestine (p < 0.05), and the expression of genes related to the glucose metabolism (pk and pepck) and mTOR (tor, akt, s6k1, 4ebp1, and ampka) signaling pathways were significantly increased in the liver in H1 (p < 0.05). The relative abundance of Blautia in the gut microbiota (p < 0.05) was significantly increased in H1. Therefore, these results indicated that H1 can significantly improve growth performance, promote intestinal digestion, activate the glucose metabolism pathway and mTOR signaling pathway, and increase the abundance of beneficial bacteria in the gut of largemouth bass. These findings provided valuable support for the application of HRW to support the healthy aquaculture of largemouth bass.
The effects of selenium supplementation in Tachysurus fulvidraco (T. fulvidraco) on low-temperature stress are not known. In this study, 280 healthy T. fulvidraco were divided into two groups, the G0 ...group (a control group) and the T0 group (a selenium treatment group on a 0.22 mg/kg diet), for a 6-week feeding time. Then, low-temperature stress (water temperature dropped from 26 to 13 °C, with a rate of 1 °C/h) was administered after that. The feeding results showed that selenium increased the percent weight gain (PWG), specific growth rate (SGR), and survival rate (SR) of T. fulvidraco and decreased the feed conversion rate (FCR), but these differences were not significant (p > 0.05). Under low temperatures, selenium still has no significant effects on antioxidant indexes such as glutathione peroxidase (GSH-Px) activity, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content in serum (p > 0.05). However, metabolomic analysis revealed that selenium caused changes in lipids and lipid-like molles, organic acids and their derivatives, and fatty acyls. Choline, linoleic acid, and glycerophospholipid metabolism pathways; d-arginine and d-ornithine metabolism; valine, leucine, and isoleucine degradation; and biosynthesis pathways, as well as pyrimidine metabolism pathways, were activated to produce these metabolites to combat against this stress. In addition, selenium increased the diversity of intestinal microbes in T. fulvidraco and decreased the relative abundance of Plesiomonas. However, the combined analysis showed the intestinal microbe changes did not affect metabolite production. In summary, selenium activated lipid, carbohydrate, and amino acid metabolism for energy substance provision, reduced the oxidation and production of other harmful substances, and increased the intestinal microbe diversity of T. fulvidraco to improve resistance to low-temperature stress.
PDF
