RESUMO
Many behaviors require the coordinated actions of somatic and autonomic functions. However, the underlying mechanisms remain elusive. By opto-stimulating different populations of descending spinal projecting neurons (SPNs) in anesthetized mice, we show that stimulation of excitatory SPNs in the rostral ventromedial medulla (rVMM) resulted in a simultaneous increase in somatomotor and sympathetic activities. Conversely, opto-stimulation of rVMM inhibitory SPNs decreased both activities. Anatomically, these SPNs innervate both sympathetic preganglionic neurons and motor-related regions in the spinal cord. Fiber-photometry recording indicated that the activities of rVMM SPNs correlate with different levels of muscle and sympathetic tone during distinct arousal states. Inhibiting rVMM excitatory SPNs reduced basal muscle and sympathetic tone, impairing locomotion initiation and high-speed performance. In contrast, silencing the inhibitory population abolished muscle atonia and sympathetic hypoactivity during rapid eye movement (REM) sleep. Together, these results identify rVMM SPNs as descending spinal projecting pathways controlling the tone of both the somatomotor and sympathetic systems.
Assuntos
Bulbo , Medula Espinal , Sistema Nervoso Simpático , Animais , Masculino , Camundongos , Locomoção/fisiologia , Bulbo/fisiologia , Camundongos Endogâmicos C57BL , Neurônios Motores/fisiologia , Neurônios/fisiologia , Sono REM/fisiologia , Medula Espinal/fisiologia , Sistema Nervoso Simpático/fisiologia , Comportamento Animal , Contagem de Células , Músculo EsqueléticoRESUMO
Remyelination failure in diseases like multiple sclerosis (MS) was thought to involve suppressed maturation of oligodendrocyte precursors; however, oligodendrocytes are present in MS lesions yet lack myelin production. We found that oligodendrocytes in the lesions are epigenetically silenced. Developing a transgenic reporter labeling differentiated oligodendrocytes for phenotypic screening, we identified a small-molecule epigenetic-silencing-inhibitor (ESI1) that enhances myelin production and ensheathment. ESI1 promotes remyelination in animal models of demyelination and enables de novo myelinogenesis on regenerated CNS axons. ESI1 treatment lengthened myelin sheaths in human iPSC-derived organoids and augmented (re)myelination in aged mice while reversing age-related cognitive decline. Multi-omics revealed that ESI1 induces an active chromatin landscape that activates myelinogenic pathways and reprograms metabolism. Notably, ESI1 triggered nuclear condensate formation of master lipid-metabolic regulators SREBP1/2, concentrating transcriptional co-activators to drive lipid/cholesterol biosynthesis. Our study highlights the potential of targeting epigenetic silencing to enable CNS myelin regeneration in demyelinating diseases and aging.
Assuntos
Epigênese Genética , Bainha de Mielina , Oligodendroglia , Remielinização , Animais , Bainha de Mielina/metabolismo , Humanos , Camundongos , Remielinização/efeitos dos fármacos , Oligodendroglia/metabolismo , Sistema Nervoso Central/metabolismo , Camundongos Endogâmicos C57BL , Rejuvenescimento , Células-Tronco Pluripotentes Induzidas/metabolismo , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Organoides/metabolismo , Organoides/efeitos dos fármacos , Doenças Desmielinizantes/metabolismo , Doenças Desmielinizantes/genética , Diferenciação Celular/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/farmacologia , Masculino , Regeneração/efeitos dos fármacos , Esclerose Múltipla/metabolismo , Esclerose Múltipla/genética , Esclerose Múltipla/tratamento farmacológico , Esclerose Múltipla/patologiaRESUMO
Non-neuronal cells are key to the complex cellular interplay that follows central nervous system insult. To understand this interplay, we generated a single-cell atlas of immune, glial and retinal pigment epithelial cells from adult mouse retina before and at multiple time points after axonal transection. We identified rare subsets in naive retina, including interferon (IFN)-response glia and border-associated macrophages, and delineated injury-induced changes in cell composition, expression programs and interactions. Computational analysis charted a three-phase multicellular inflammatory cascade after injury. In the early phase, retinal macroglia and microglia were reactivated, providing chemotactic signals concurrent with infiltration of CCR2+ monocytes from the circulation. These cells differentiated into macrophages in the intermediate phase, while an IFN-response program, likely driven by microglia-derived type I IFN, was activated across resident glia. The late phase indicated inflammatory resolution. Our findings provide a framework to decipher cellular circuitry, spatial relationships and molecular interactions following tissue injury.
Assuntos
Macrófagos , Retina , Animais , Camundongos , Retina/lesões , Retina/metabolismo , Microglia , Sistema Nervoso Central , MonócitosRESUMO
Many human spinal cord injuries are anatomically incomplete but exhibit complete paralysis. It is unknown why spared axons fail to mediate functional recovery in these cases. To investigate this, we undertook a small-molecule screen in mice with staggered bilateral hemisections in which the lumbar spinal cord is deprived of all direct brain-derived innervation, but dormant relay circuits remain. We discovered that a KCC2 agonist restored stepping ability, which could be mimicked by selective expression of KCC2, or hyperpolarizing DREADDs, in the inhibitory interneurons between and around the staggered spinal lesions. Mechanistically, these treatments transformed this injury-induced dysfunctional spinal circuit to a functional state, facilitating the relay of brain-derived commands toward the lumbar spinal cord. Thus, our results identify spinal inhibitory interneurons as a roadblock limiting the integration of descending inputs into relay circuits after injury and suggest KCC2 agonists as promising treatments for promoting functional recovery after spinal cord injury.
Assuntos
Traumatismos da Medula Espinal/tratamento farmacológico , Simportadores/agonistas , Simportadores/metabolismo , Animais , Axônios , Regulação da Expressão Gênica/genética , Interneurônios/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Regeneração Nervosa/fisiologia , Plasticidade Neuronal/genética , Neurônios/metabolismo , Recuperação de Função Fisiológica/genética , Recuperação de Função Fisiológica/fisiologia , Medula Espinal , Simportadores/uso terapêutico , Cotransportadores de K e Cl-RESUMO
Corticospinal neurons (CSNs) represent the direct cortical outputs to the spinal cord and play important roles in motor control across different species. However, their organizational principle remains unclear. By using a retrograde labeling system, we defined the requirement of CSNs in the execution of a skilled forelimb food-pellet retrieval task in mice. In vivo imaging of CSN activity during performance revealed the sequential activation of topographically ordered functional ensembles with moderate local mixing. Region-specific manipulations indicate that CSNs from caudal or rostral forelimb area control reaching or grasping, respectively, and both are required in the transitional pronation step. These region-specific CSNs terminate in different spinal levels and locations, therefore preferentially connecting with the premotor neurons of muscles engaged in different steps of the task. Together, our findings suggest that spatially defined groups of CSNs encode different movement modules, providing a logic for parallel-ordered corticospinal circuits to orchestrate multistep motor skills.
Assuntos
Medula Cervical/fisiologia , Destreza Motora , Vias Neurais , Animais , Cálcio/análise , Córtex Cerebral/citologia , Córtex Cerebral/fisiologia , Medula Cervical/citologia , Membro Anterior/fisiologia , Articulações/fisiologia , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Although a number of repair strategies have been shown to promote axon outgrowth following neuronal injury in the mammalian CNS, it remains unclear whether regenerated axons establish functional synapses and support behavior. Here, in both juvenile and adult mice, we show that either PTEN and SOCS3 co-deletion, or co-overexpression of osteopontin (OPN)/insulin-like growth factor 1 (IGF1)/ciliary neurotrophic factor (CNTF), induces regrowth of retinal axons and formation of functional synapses in the superior colliculus (SC) but not significant recovery of visual function. Further analyses suggest that regenerated axons fail to conduct action potentials from the eye to the SC due to lack of myelination. Consistent with this idea, administration of voltage-gated potassium channel blockers restores conduction and results in increased visual acuity. Thus, enhancing both regeneration and conduction effectively improves function after retinal axon injury.
Assuntos
Axônios/fisiologia , Colículos Superiores/fisiologia , 4-Aminopiridina/farmacologia , Animais , Axônios/efeitos dos fármacos , Fator Neurotrófico Ciliar/metabolismo , Fenômenos Eletrofisiológicos , Olho/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Camundongos , Bainha de Mielina/metabolismo , Nervo Óptico , Osteopontina/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Bloqueadores dos Canais de Potássio/farmacologia , Regeneração/efeitos dos fármacos , Proteína 3 Supressora da Sinalização de Citocinas , Proteínas Supressoras da Sinalização de Citocina/metabolismo , SinapsesRESUMO
The brain controls nearly all bodily functions via spinal projecting neurons (SPNs) that carry command signals from the brain to the spinal cord. However, a comprehensive molecular characterization of brain-wide SPNs is still lacking. Here we transcriptionally profiled a total of 65,002 SPNs, identified 76 region-specific SPN types, and mapped these types into a companion atlas of the whole mouse brain1. This taxonomy reveals a three-component organization of SPNs: (1) molecularly homogeneous excitatory SPNs from the cortex, red nucleus and cerebellum with somatotopic spinal terminations suitable for point-to-point communication; (2) heterogeneous populations in the reticular formation with broad spinal termination patterns, suitable for relaying commands related to the activities of the entire spinal cord; and (3) modulatory neurons expressing slow-acting neurotransmitters and/or neuropeptides in the hypothalamus, midbrain and reticular formation for 'gain setting' of brain-spinal signals. In addition, this atlas revealed a LIM homeobox transcription factor code that parcellates the reticulospinal neurons into five molecularly distinct and spatially segregated populations. Finally, we found transcriptional signatures of a subset of SPNs with large soma size and correlated these with fast-firing electrophysiological properties. Together, this study establishes a comprehensive taxonomy of brain-wide SPNs and provides insight into the functional organization of SPNs in mediating brain control of bodily functions.
Assuntos
Encéfalo , Perfilação da Expressão Gênica , Vias Neurais , Neurônios , Medula Espinal , Animais , Camundongos , Hipotálamo , Neurônios/metabolismo , Neuropeptídeos , Medula Espinal/citologia , Medula Espinal/metabolismo , Encéfalo/citologia , Encéfalo/metabolismo , Neurotransmissores , Mesencéfalo/citologia , Formação Reticular/citologia , Eletrofisiologia , Cerebelo/citologia , Córtex Cerebral/citologiaRESUMO
Central oscillators are primordial neural circuits that generate and control rhythmic movements1,2. Mechanistic understanding of these circuits requires genetic identification of the oscillator neurons and their synaptic connections to enable targeted electrophysiological recording and causal manipulation during behaviours. However, such targeting remains a challenge with mammalian systems. Here we delimit the oscillator circuit that drives rhythmic whisking-a motor action that is central to foraging and active sensing in rodents3,4. We found that the whisking oscillator consists of parvalbumin-expressing inhibitory neurons located in the vibrissa intermediate reticular nucleus (vIRtPV) in the brainstem. vIRtPV neurons receive descending excitatory inputs and form recurrent inhibitory connections among themselves. Silencing vIRtPV neurons eliminated rhythmic whisking and resulted in sustained vibrissae protraction. In vivo recording of opto-tagged vIRtPV neurons in awake mice showed that these cells spike tonically when animals are at rest, and transition to rhythmic bursting at the onset of whisking, suggesting that rhythm generation is probably the result of network dynamics, as opposed to intrinsic cellular properties. Notably, ablating inhibitory synaptic inputs to vIRtPV neurons quenched their rhythmic bursting, impaired the tonic-to-bursting transition and abolished regular whisking. Thus, the whisking oscillator is an all-inhibitory network and recurrent synaptic inhibition has a key role in its rhythmogenesis.
Assuntos
Movimento , Vias Neurais , Neurônios , Periodicidade , Vibrissas , Animais , Tronco Encefálico/citologia , Tronco Encefálico/fisiologia , Camundongos , Movimento/fisiologia , Inibição Neural , Neurônios/fisiologia , Parvalbuminas/metabolismo , Descanso , Sinapses , Vibrissas/fisiologia , VigíliaRESUMO
We develop soft and stretchable fatigue-resistant hydrogel optical fibers that enable optogenetic modulation of peripheral nerves in naturally behaving animals during persistent locomotion. The formation of polymeric nanocrystalline domains within the hydrogels yields fibers with low optical losses of 1.07 dB cm-1, Young's modulus of 1.6 MPa, stretchability of 200% and fatigue strength of 1.4 MPa against 30,000 stretch cycles. The hydrogel fibers permitted light delivery to the sciatic nerve, optogenetically activating hindlimb muscles in Thy1::ChR2 mice during 6-week voluntary wheel running assays while experiencing repeated deformation. The fibers additionally enabled optical inhibition of pain hypersensitivity in an inflammatory model in TRPV1::NpHR mice over an 8-week period. Our hydrogel fibers offer a motion-adaptable and robust solution to peripheral nerve optogenetics, facilitating the investigation of somatosensation.
Assuntos
Fibras Ópticas , Optogenética , Camundongos , Animais , Hidrogéis , Atividade Motora , Nervo Isquiático/fisiologia , LocomoçãoRESUMO
Spinal cord injury in mammals is thought to trigger scar formation with little regeneration of axons1-4. Here we show that a crush injury to the spinal cord in neonatal mice leads to scar-free healing that permits the growth of long projecting axons through the lesion. Depletion of microglia in neonatal mice disrupts this healing process and stalls the regrowth of axons, suggesting that microglia are critical for orchestrating the injury response. Using single-cell RNA sequencing and functional analyses, we find that neonatal microglia are transiently activated and have at least two key roles in scar-free healing. First, they transiently secrete fibronectin and its binding proteins to form bridges of extracellular matrix that ligate the severed ends of the spinal cord. Second, neonatal-but not adult-microglia express several extracellular and intracellular peptidase inhibitors, as well as other molecules that are involved in resolving inflammation. We transplanted either neonatal microglia or adult microglia treated with peptidase inhibitors into spinal cord lesions of adult mice, and found that both types of microglia significantly improved healing and axon regrowth. Together, our results reveal the cellular and molecular basis of the nearly complete recovery of neonatal mice after spinal cord injury, and suggest strategies that could be used to facilitate scar-free healing in the adult mammalian nervous system.
Assuntos
Microglia/fisiologia , Traumatismos da Medula Espinal/terapia , Regeneração da Medula Espinal , Medula Espinal/citologia , Medula Espinal/fisiologia , Animais , Animais Recém-Nascidos , Axônios/efeitos dos fármacos , Axônios/fisiologia , Cicatriz , Fibronectinas/metabolismo , Homeostase , Camundongos , Microglia/efeitos dos fármacos , Inibidores de Proteases/farmacologia , RNA-Seq , Análise de Célula Única , Medula Espinal/patologia , Traumatismos da Medula Espinal/patologia , Regeneração da Medula Espinal/efeitos dos fármacos , Cicatrização/efeitos dos fármacosRESUMO
Ageing is a degenerative process that leads to tissue dysfunction and death. A proposed cause of ageing is the accumulation of epigenetic noise that disrupts gene expression patterns, leading to decreases in tissue function and regenerative capacity1-3. Changes to DNA methylation patterns over time form the basis of ageing clocks4, but whether older individuals retain the information needed to restore these patterns-and, if so, whether this could improve tissue function-is not known. Over time, the central nervous system (CNS) loses function and regenerative capacity5-7. Using the eye as a model CNS tissue, here we show that ectopic expression of Oct4 (also known as Pou5f1), Sox2 and Klf4 genes (OSK) in mouse retinal ganglion cells restores youthful DNA methylation patterns and transcriptomes, promotes axon regeneration after injury, and reverses vision loss in a mouse model of glaucoma and in aged mice. The beneficial effects of OSK-induced reprogramming in axon regeneration and vision require the DNA demethylases TET1 and TET2. These data indicate that mammalian tissues retain a record of youthful epigenetic information-encoded in part by DNA methylation-that can be accessed to improve tissue function and promote regeneration in vivo.
Assuntos
Envelhecimento/genética , Reprogramação Celular/genética , Metilação de DNA , Epigênese Genética , Olho , Regeneração Nervosa/genética , Visão Ocular/genética , Visão Ocular/fisiologia , Envelhecimento/fisiologia , Animais , Axônios/fisiologia , Linhagem Celular Tumoral , Sobrevivência Celular , Proteínas de Ligação a DNA/genética , Dependovirus/genética , Dioxigenases , Modelos Animais de Doenças , Olho/citologia , Olho/inervação , Olho/patologia , Feminino , Vetores Genéticos/genética , Glaucoma/genética , Glaucoma/patologia , Humanos , Fator 4 Semelhante a Kruppel , Fatores de Transcrição Kruppel-Like/genética , Camundongos , Camundongos Endogâmicos C57BL , Fator 3 de Transcrição de Octâmero/genética , Traumatismos do Nervo Óptico/genética , Proteínas Proto-Oncogênicas/genética , Células Ganglionares da Retina/citologia , Fatores de Transcrição SOXB1/genética , Transcriptoma/genéticaRESUMO
Although the visual system extends through the brain, most vision loss originates from defects in the eye. Its central element is the neural retina, which senses light, processes visual signals, and transmits them to the rest of the brain through the optic nerve (ON). Surrounding the retina are numerous other structures, conventionally divided into anterior and posterior segments. Here, we used high-throughput single-nucleus RNA sequencing (snRNA-seq) to classify and characterize cells in six extraretinal components of the posterior segment: ON, optic nerve head (ONH), peripheral sclera, peripapillary sclera (PPS), choroid, and retinal pigment epithelium (RPE). Defects in each of these tissues are associated with blinding diseases-for example, glaucoma (ONH and PPS), optic neuritis (ON), retinitis pigmentosa (RPE), and age-related macular degeneration (RPE and choroid). From ~151,000 single nuclei, we identified 37 transcriptomically distinct cell types, including multiple types of astrocytes, oligodendrocytes, fibroblasts, and vascular endothelial cells. Our analyses revealed a differential distribution of many cell types among distinct structures. Together with our previous analyses of the anterior segment and retina, the data presented here complete a "Version 1" cell atlas of the human eye. We used this atlas to map the expression of >180 genes associated with the risk of developing glaucoma, which is known to involve ocular tissues in both anterior and posterior segments as well as the neural retina. Similar methods can be used to investigate numerous additional ocular diseases, many of which are currently untreatable.
Assuntos
Glaucoma , Disco Óptico , Humanos , Transcriptoma , Células Endoteliais , Glaucoma/genética , Nervo Óptico , EscleraRESUMO
Regulating the gut microbiota alleviates hepatic encephalopathy (HE). It remains unclear whether it is imperative to withhold treatment for microbial imbalance after liver functional recovery. This work aims to elucidate the alterations in cognitive behavior, liver function, synaptic transmission, and brain metabolites in acute liver failure(ALF) mice before and after hepatic function recovery. Here, thioacetamide was injected intraperitoneally to establish an ALF mouse model, which induced HE. By performing hierarchical clustering analysis, we found that the liver functions normalized, but cognitive dysfunction and intestinal dysbacteriosis were found in the ALF mice 14 days after thioacetamide injection. Additionally, fecal microbiota transplant from the ALF mice with liver function recovery could induce liver injury and cognitive impairment. Moreover, we found alterations in synaptic transmission in the ALF mice with liver function improvement, and the correlations between the gut bacteria and synaptic transmission in the cortex were significant. Finally, we detected apparent alterations in the brain metabolic profiles of the ALF mice after liver function improvement by performing 1H nuclear magnetic resonance spectroscopy, suggesting a risk of HE. These results showed that intestinal dysbacteriosis in ALF mice with liver function recovery is sufficient to induce liver injury and cognitive impairment. These results indicated continuous care may be necessary for monitoring microbial imbalance even in ALF-induced HE patients whose liver function has recovered significantly.
RESUMO
The structure of solvated Li+ has a significant influence on the electrolyte/electrode interphase (EEI) components and desolvation energy barrier, which are two key factors in determining the Li+ diffusion kinetics in lithium metal batteries. Herein, the "solvent activity" concept is proposed to quantitatively describe the correlation between the electrolyte elements and the structure of solvated Li+. Through fitting the correlation of the electrode potential and solvent concentration, we suggest a "low-activity-solvent" electrolyte (LASE) system for deriving a stable inorganic-rich EEI. Nano LiF particles, as a model, were used to capture free solvent molecules for the formation of a LASE system. This advanced LASE not only exhibits outstanding antidendrite growth behavior but also delivers an impressive performance in Li/LiNi0.8Co0.1Mn0.1O2 cells (a capacity of 169 mAh g-1 after 250 cycles at 0.5 C).
RESUMO
A solid-state approach for quantum networks is advantageous, as it allows the integration of nanophotonics to enhance the photon emission and the utilization of weakly coupled nuclear spins for long-lived storage. Silicon carbide, specifically point defects within it, shows great promise in this regard due to the easy of availability and well-established nanofabrication techniques. Despite of remarkable progresses made, achieving spin-photon entanglement remains a crucial aspect to be realized. In this Letter, we experimentally generate entanglement between a silicon vacancy defect in silicon carbide and a scattered single photon in the zero-phonon line. The spin state is measured by detecting photons scattered in the phonon sideband. The photonic qubit is encoded in the time-bin degree of freedom and measured using an unbalanced Mach-Zehnder interferometer. Photonic correlations not only reveal the quality of the entanglement but also verify the deterministic nature of the entanglement creation process. By harnessing two pairs of such spin-photon entanglement, it becomes straightforward to entangle remote quantum nodes at long distance.
RESUMO
Patients suffering from hepatic ischemia-reperfusion injury (HIRI) frequently exhibit postoperative cognitive deficits. Our previous observations have emphasized the diurnal variation in hepatic ischemia-reperfusion injury-induced cognitive impairment, in which gut microbiota-associated hippocampal lipid metabolism plays an important role. Herein, we further investigated the molecular mechanisms involved in the process. Hepatic ischemia-reperfusion surgery was performed under morning (ZT0, 08:00) and evening (ZT12, 20:00). Fecal microbiota transplantation was used to associate HIRI model with pseudo-germ-free mice. The novel object recognition test and Y-maze test were used to assess cognitive function. 16S rRNA gene sequencing and analysis were used for microbial analysis. Western blotting was used for hippocampal protein analysis. Compared with the ZT0-HIRI group, ZT12-HIRI mice showed learning and short term memory impairment, accompanied by down-regulated expression of hippocampal CB1R, but not CB2R. Both gut microbiota composition and microbiota metabolites were significantly different in ZT12-HIRI mice compared with ZT0-HIRI. Fecal microbiota transplantation from the ZT12-HIRI was demonstrated to induce cognitive impairment behavior and down-regulated hippocampal CB1R and ß-arrestin1. Intraperitoneal administration of CB1R inhibitor AM251 (1 mg/kg) down-regulated hippocampal CB1R and caused cognitive impairment in ZT0-HIRI mice. And intraperitoneal administration of CB1R agonist WIN 55,212-2 (1 mg/kg) up-regulated hippocampal CB1R and improved cognitive impairment in ZT12-HIRI mice. In summary, the results suggest that gut microbiota may regulate the diurnal variation of HIRI-induced cognitive function by interfering with hippocampal CB1R.
Assuntos
Disfunção Cognitiva , Microbioma Gastrointestinal , Hipocampo , Receptor CB1 de Canabinoide , Traumatismo por Reperfusão , Animais , Masculino , Camundongos , Ritmo Circadiano/fisiologia , Disfunção Cognitiva/metabolismo , Disfunção Cognitiva/etiologia , Transplante de Microbiota Fecal , Microbioma Gastrointestinal/fisiologia , Hipocampo/metabolismo , Fígado/metabolismo , Aprendizagem em Labirinto/fisiologia , Camundongos Endogâmicos C57BL , Receptor CB1 de Canabinoide/metabolismo , Traumatismo por Reperfusão/metabolismoRESUMO
Excess utilization of plant protein sources in animal feed has been found to adversely affect the antioxidant properties and immunity of animals. While the role of gut microbes in plant protein-induced inflammation has been identified in various models, the specific mechanisms regulating gut microbes in crustaceans remain unclear. Accordingly, this study was designed to investigate the effects of replacing fishmeal with soybean meal (SM) on the hepatopancreas antioxidant and immune capacities, and gut microbial functions of crayfish, as well as the potential microbial regulatory mechanisms. 750 crayfish (4.00 g) were randomly divided into five groups: SS0, SS25, SS50, SS75, and SS100, and fed diets with different levels of soybean meal substituted for fishmeal for six weeks. High SM supplementation proved detrimental to maintaining hepatopancreas health, as indicated by an increase in hemolymph MDA content, GPT, and GOT activities, the observed rupture of hepatopancreas cell basement membranes, along with the decreased number of hepatopancreatic F cells. Moreover, crayfish subjected to high SM diets experienced obvious inflammation in hepatopancreas, together with up-regulated mRNA expression levels of nfkb, alf, and tlr (p<0.05), whereas the lzm mRNA expression level exhibited the highest value in the SS25 group. Furthermore, hepatopancreas antioxidant properties highly attenuated by the level of dietary SM substitution levels, as evidenced by the observed increase in MDA content (p<0.05), decrease in GSH content (p<0.05), and inhabitation of SOD, CAT, GPx, and GST activities (p<0.05), along with down-regulated hepatopancreas cat, gpx, gst, and mmnsod mRNA expression levels via inhibiting nrf2/keap1 pathway. Functional genes contributing to metabolism identified that high SM diets feeding significantly activated lipopolysaccharide biosynthesis, revealing gut dysfunction acted as the cause of inflammation. The global microbial co-occurrence network further indicated that the microbes contributing more to serum indicators and immunity were in module eigengene 17 (ME17). A structural equation model revealed that the genes related to alf directly drove the serum enzyme activities through microbes in ME17, with OTU399 and OTU533 identified as major biomarkers and classified into Proteobacteria that secrete endotoxins. To conclude, SM could replace 25 % of fishmeal in crayfish diets without negatively affecting immunity, and antioxidant capacity. Excessive SM levels contributed to gut dysfunction and weakened the innate immune system of crayfish.
Assuntos
Ração Animal , Antioxidantes , Astacoidea , Dieta , Microbioma Gastrointestinal , Glycine max , Hepatopâncreas , Animais , Astacoidea/imunologia , Astacoidea/genética , Ração Animal/análise , Glycine max/química , Antioxidantes/metabolismo , Dieta/veterinária , Microbioma Gastrointestinal/efeitos dos fármacos , Hepatopâncreas/imunologia , Hepatopâncreas/metabolismo , Imunidade Inata/efeitos dos fármacos , Distribuição Aleatória , Intestinos/imunologia , Intestinos/efeitos dos fármacos , Suplementos Nutricionais/análiseRESUMO
The ultrafast decay dynamics of pyridine-N-oxide upon excitation in the near-ultraviolet range of 340.2-217.6 nm is investigated using the femtosecond time-resolved photoelectron imaging technique. The time-resolved photoelectron spectra and photoelectron angular distributions at all pump wavelengths are carefully analyzed and the following view is derived: at the longest pump wavelengths (340.2 and 325.6 nm), pyridine-N-oxide is excited to the S1(1ππ*) state with different vibrational levels. The depopulation rate of the S1 state shows a marked dependence on vibrational energy and mode, and the lifetime is in the range of 1.4-160 ps. At 289.8 and 280.5 nm, both the second 1ππ* state and the S1 state are initially prepared. The former has an extremely short lifetime of â¼60 fs, which indicates that the ultrafast deactivation pathway such as a rapid internal conversion to one close-lying state is its dominant decay channel, while the latter is at high levels of vibrational excitation and decays within the range of 380-520 fs. At the shortest pump wavelengths (227.3 and 217.6 nm), another excited state of Rydberg character is mostly excited. We assign this state to the 3s Rydberg state which has a lifetime of 0.55-2.2 ps. This study provides a comprehensive picture of the ultrafast excited-state decay dynamics of the photoexcited pyridine-N-oxide molecule.
RESUMO
The ultrafast decay dynamics of N-methyl-2-pyridone upon excitation in the near-ultraviolet range of 261.5-227.9 nm is investigated using the femtosecond time-resolved photoelectron spectroscopy method. Irradiation at 261.5 nm prepares N-methyl-2-pyridone molecules with high vibrational levels in the 11ππ* state. The radiation-less decay to the ground state via internal conversion is suggested to be the dominant channel for the 11ππ* state with large vibrational excess energy, which is revealed by a lifetime of 1.6 ± 0.2 ps. As the pump wavelength decreases, we found that irradiation at 238.5 and 227.9 nm results in the population of the 21ππ* state. This is in agreement with the assignment of the vapor-phase UV absorption bands of N-methyl-2-pyridone. On the basis of the detailed analysis of our measured time-resolved photoelectron spectra at all pump wavelengths, we conclude that the 21ππ* state has an ultrashort lifetime of 50 ± 10 fs. In addition, the S1(11ππ*) state is subsequently populated via internal conversion and decays over a lifetime of 680-620 fs. The most probable whole deactivation pathway of the 21ππ* state is discussed. This experimental study provides new insights into the excitation energy-dependent decay dynamics of electronically excited N-methyl-2-pyridone.