Biology subjects

Ayana, R.

Publications and source records attributed to Ayana, R..

6 recordsLinked to original sources

bioRxiv2025

From injury to recovery: Functional neuronal regeneration after traumatic brain injury in the telencephalon of the young adult African turquoise killifish

Neuronal loss caused by neurodegenerative diseases and traumatic brain injuries (TBI) often results in long-term disabilities, highlighting the urgent need for further research and effective regenerative strategies. In mammals, neurogenic capacity is inherently limited and declines further with age. In contrast, the young adult killifish demonstrates a remarkable ability to regenerate neurons in the telencephalon following TBI. However, it remains unknown whether and when these newly generated neurons functionally integrate into existing circuits, as traditional histological analysis of fixed tissue offers only static insights into this dynamic process. To this end, we optimized a retroviral vector strategy to label dividing stem cells and their progeny, including newborn neurons. By introducing a combination of novel approaches i.e., retroviral vector labeling, electrophysiology and a conditioned place avoidance test, we investigated the generation, morphology, and synaptic integration of newborn neurons following TBI in the dorsomedial (Dm) zone of the telencephalon, a region homologous to the mammalian amygdala in other teleost fish. Our results show that injury-induced adult-born neurons functionally integrate into existing circuits, and that killifish can achieve functional behavioral recovery after TBI. While previous histological assessments using a stab-wound injury suggested a 30-day recovery period, our functional data reveal that full behavioral recovery requires approximately 50 days. At this point, fish successfully relearn to avoid a conditioned place, and the new neurons exhibit mature morpho-electric characteristics, including abundant dendritic spines. Electrophysiological analysis revealed that newborn neurons in an injured environment take longer to mature when compared to neurons in naive killifish. Together, our findings demonstrate that structural regeneration aligns with functional recovery, and establish retroviral vectors as a powerful tool for birth dating injury-induced neurogenesis in teleosts. Killifish thus represent a promising model for studying interventions aimed at enhancing neuronal maturation and integration after brain injury. Key pointsO_LIA retroviral vector strategy allows specific and sparse labeling of adult-born neurons in the killifish brain. C_LIO_LIThe Dm zone in the telencephalon of the killifish is responsible for avoidance learning and memory and thus homologous to the mammalian amygdala. C_LIO_LIIn young adult killifish, upon Dm injury, adult-born neurons mature morphologically and functionally in 50 days, which is slower than in constitutive neurogenesis. C_LIO_LIThe timing and extent of behavioral recovery from such injury aligns with morpho-electric observations. C_LI

neuroscience↗

bioRxiv2024

Early life growth and cellular heterogeneity in the short-lived African turquoise killifish telencephalon

The African turquoise killifish (Nothobranchius furzeri) is becoming a favorable model for neurobiological research. The combination of a short lifespan and a declining neuroregenerative capacity upon aging makes the killifish ideally suited for research on brain aging and regeneration. A remarkable cellular diversity makes up the young-adult killifish telencephalon, characterized by highly proliferative non-glial progenitors and four spatially distinct radial glia subtypes. In contrast to a relatively slow embryonic development, hatching is followed by a period of accelerated growth in the short-lived N. furzeri strain; GRZ. Accordingly, the brain of this teleost experiences a period of rapid expansion and maturation. In this study, we charted the growth progression of the killifish telencephalon during early post-embryonic development. We identified a dynamic cellular buildup of the neurogenic niches sustaining this explosive growth. Spatial data revealed specific differences between pallial and subpallial regions in terms of growth pace and cellular output. Spatial signatures comparable to zebrafish were identified for excitatory and inhibitory neuronal lineages, already present at hatching. Summary statementThis study charts the progenitor and neural diversity of the telencephalon from post-embryonic development, identifying the cellular building blocks during accelerated brain growth of the short-lived African Turquoise killifish.

neuroscience↗

bioRxiv2024

Age-related dysregulation of the retinal transcriptome in African turquoise killifish

Age-related vision loss caused by retinal neurodegenerative pathologies is becoming more prevalent in our ageing society. To understand the physiological and molecular impact of ageing on retinal homeostasis, we used the short-lived African turquoise killifish, a model known to naturally develop central nervous system (CNS) ageing hallmarks and vision loss. Bulk and single-cell RNA-sequencing (scRNA-seq) of three age groups (6-, 12-, and 18-week-old) identified transcriptional ageing fingerprints in the killifish retina, unveiling pathways also identified in the aged brain, including oxidative stress, gliosis, and inflammageing. These findings were comparable to observations in ageing mouse retina. Additionally, transcriptional changes in genes related to retinal diseases, such as glaucoma and age-related macular degeneration, were observed. The cellular heterogeneity in the killifish retina was characterised, confirming the presence of all typical vertebrate retinal cell types. Data integration from age-matched samples between the bulk and scRNA-seq experiments revealed a loss of cellular specificity in gene expression upon ageing, suggesting potential disruption in transcriptional homeostasis. Differential expression analysis within the identified cell types highlighted the role of glial/immune cells as important stress regulators during ageing. Our work emphasises the value of the fast-ageing killifish in elucidating molecular signatures in age-associated retinal disease and vision decline. This study contributes to the understanding of how age-related changes in molecular pathways may impact CNS health, providing insights that may inform future therapeutic strategies for age-related pathologies. HighlightsO_LIThe aged killifish retina displays several ageing hallmarks, such as oxidative stress, gliosis and inflammageing, at the transcriptome level. C_LIO_LIRisk genes for neurodegenerative disorders show dysregulation in the old killifish retina. C_LIO_LIAll vertebrate retinal cell types are present in the killifish retina. C_LIO_LITranscriptional dysregulation in the aged killifish retina is observed across cell types. C_LI

neuroscience↗

bioRxiv2021

Single-cell sequencing of the adult killifish (N. furzeri) brain identifies an atypical progenitor, glial and neuronal heterogeneity

The African turquoise killifish combines a short lifespan with spontaneous age-dependent loss of neuroregenerative capacity. The stem cell niches driving neuroregeneration and their molecular signatures remain elusive. To investigate this, we performed scRNA-seq of the adult telencephalon, combined with full-length transcriptomics using ISO-seq. Our results unveil about 25 cell types including neurons and progenitors of glial-and non-glial nature. Subclustering of progenitors identifies four radial glia (RG), and two non-glial progenitor (NGP) cell states. Combining the molecular profiles with spatial mapping of the RG clusters, reveals two spatially divergent astroglia, one ependymal, and one neuroepithelial-like subtype. We propose neuroepithelial-like RG and NGPs to be the start and intercessor populations of both neuro- and gliogenic lineages. Neuronal classification reveals distinct subtypes and lineages corresponding to excitatory and inhibitory neurons. This catalogue of telencephalon cell types is an extensive resource to understand the molecular basis of intrinsic plasticity shaping adult neuro- and gliogenesis. HighlightsO_LIScRNA-seq and ISO-seq identified a complete cell catalogue of the adult killifish telencephalon C_LIO_LIProgenitor diversity revealed the presence of spatially-defined (astro)glial subtypes C_LIO_LIA neuroepithelial radial glia population marks the start point of neurogenesis, accompanied by proliferative non-glial progenitors C_LIO_LIImmature neurons form transcriptional subgroups that correspond to excitatory and inhibitory mature neuronal cell types C_LIO_LIThis cellular atlas is a basis for studying neurogenesis and neuro-regeneration upon injury, disease and aging C_LI

neuroscience↗

bioRxiv2021

Aging impairs the essential contributions of non-glial progenitors to neurorepair in the dorsal telencephalon of the Killifish N. furzeri

The aging central nervous system (CNS) of mammals displays progressive limited regenerative abilities. Recovery after loss of neurons is extremely restricted in the aged brain. Many research models fall short in recapitulating mammalian aging hallmarks or have an impractically long lifespan. We established a traumatic brain injury model in the African turquoise killifish (Nothobranchius furzeri), a regeneration-competent vertebrate model that evolved to naturally age extremely fast. Stab-wound injury of the aged killifish dorsal telencephalon unveils an impaired and incomplete regeneration response when compared to young individuals. Remarkably, killifish brain regeneration is mainly supported by atypical non-glial progenitors, yet their proliferation capacity appears declined with age. We identified a high inflammatory response and glial scarring to also underlie the hampered generation of new neurons in aged fish. These primary results will pave the way for further research to unravel the factor age in relation to neurorepair, and to improve therapeutic strategies to restore the injured and/or diseased aged mammalian CNS. HighlightsO_LIAging impairs neurorepair in the killifish pallium at multiple stages of the regeneration process C_LIO_LIAtypical non-glial progenitors support the production of new neurons in the naive and injured dorsal pallium C_LIO_LIThe impaired regeneration capacity of aged killifish is characterized by a reduced reactive proliferation of these progenitors followed by a decreased generation of newborn neurons that in addition, fail to reach the injury site C_LIO_LIExcessive inflammation and glial scarring surface as potential brakes on brain repair in the aged killifish pallium C_LI

neuroscience↗

bioRxiv2019

Supression of Perforin-like Protein pores inhibit Plasmodium multistage-growth, transmission and erythrocyte senescence

The pore forming Plasmodium perforin like proteins (PPLP), expressed in all stages of the parasite life cycle are central drivers for host interactions critical for completion of parasite life cycle and high transmission rates. The high sequence similarity in the central membrane attack complex/ perforin (MACPF) domain and consequent functional overlaps defines them as an attractive target for the development of multi-stage antimalarials. Herein we evaluated the mechanism of pan active function of central, highly conserved region of PPLPs, MACPF domain (PMD) and inhibitory potential of specifically designed anti-PMD chemo. The E. coli expressed rPMD interacts with erythrocyte membrane and form pores of ~10.5 nm height and ~24.3 nm diameter leading to haemoglobin release and dextran uptake. The treatment with PMD induced erythrocytes senescence at 48 hours which can account for the physiological effect of disseminated PLPs in loss of circulating erythrocytes inducing anemia during malaria infection. The anti-PMD inhibitors effectively blocked intraerythrocytic growth by suppressing invasion and egress of merozoites and protecting against erythrocyte senescence. Moreover, these inhibitors also blocked the hepatic stage and transmission stage parasite development suggesting multi-stage and transmission-blocking potential of these inhibitors. Additionally, the erythrocyte senescence protective potential of PMD inhibitors can be used to occlude PPLPs mediated severe malarial anemia. Further these inhibitors can be developed with a potential to protect against severity of the disease.\n\nAuthor SummaryMalaria continues to be a major global health threat despite of several exciting improvements in the treatment and prevention of the disease. One of the major concerns in the development of therapy is the emergence of the drug resistance. But for the efficient treatment regime, targeting multiple stages including host and vector would serve as an ideal therapy. Perforin like proteins (PLPs) are eukaryotic pore forming proteins that are highly conserved in the apicomplexan parasites. These play crucial roles in entry and exit of parasites from the host cells and establish infection at multiple stages of Plasmodium spp. life cycle. Understanding the mechanism of pore formation by smaller, functional, pan-active scaffold of PLPs can serve as a target for development of cross stage protection. Here, using various biochemical, biophysical and pharmacological evidences, we validate the activity and characterize the pore formation of PLPs on erythrocytes. Further, our specifically designed inhibitors could restrict this pore formation and impede the exit/entry of the parasites. Moreover, these inhibitors could also exert multiple stage inhibition and rescue the uninfected erythrocytes from death. Together, this study highlights the mechanism of pore formation by PPLPs and evaluates their potential for the development of pan-active inhibitors to provide both symptomatic and transmission blocking cure for malaria.

molecular biology↗