Biology subjects

Palominos, M. F.

Publications and source records attributed to Palominos, M. F..

3 recordsLinked to original sources

bioRxiv2022

The assembly of wild natural isolates define neuronal integrity and life history traits of co-inhabiting C. elegans.

Bacterivore nematodes are the most abundant animals in the biosphere, largely contributing to global biogeochemistry. The effect of environmental microbes as source of associated microbiota and natural diet on their life history traits of nematodes is likely to impact the general health of the biosphere. Caenorhabditis elegans is a unique model to study the behavioral and physiological outputs of different available microbial diets. Nonetheless, most studies are on monoaxenic cultures of laboratory bacteria while the effect of natural microbiota isolates has only recently started to be reported. Here, we quantified physiological, phenotypical and behavioral traits of worms feeding on two bacteria that co-isolated with wild nematodes and tested how combinations of these isolates with other bacteria affected the traits measured. These bacteria were identified as a putative novel species of Stenotrophomonas denominated Stenotrophomonas sp. Iso1 and a strain of Bacillus pumilus designated Iso2. The isolates induced distinctive behaviors and development patterns that changed in mixes of the two bacteria and/or the pathogen Salmonella enterica. Focusing on the degeneration rate of the touch circuit of C. elegans we show that B. pumilus alone is protective while the mix with Stenotrophomonas sp. is degenerative. The analysis of the metabolite content of each isolate and their combination identified NAD+ as potentially neuroprotective. In vivo supplementation shows that NAD+ restores neuroprotection to the mixes and also to individual non-protective bacteria. The results highlight the need to study the physiological effects of bacteria resembling native diets in a multicomponent scenario rather than using single isolates. ImportanceThe behavioral decisions of animals depend on their microbiota. In nature it is unknown how this interaction affects the health of the biosphere. To study how the nematode-bacteria relationship impacts the life history traits of these animals, we isolated bacteria found in association with wild nematodes and tested their influence as single species and consortia, in the life history traits of the model C. elegans. We identify metabolites from wild bacteria that change these traits. The bacteria isolated were identified a Stenotrophomonas sp and a B. pumilus. We find that all traits depend on the biota composition. For example, B. pumilus is neuroprotective to degenerating neurons of the touch circuit of C. elegans needed to sense and escape from predators in the wild. The co-culture with Stenotrophomonas sp. eliminates the protection. We identified NAD+ as the metabolite lost in the mix, and show that NAD+ by itself is neuroprotective.

microbiology↗

bioRxiv2021

The olfactory organ is a unique site for resident neutrophils in the brain

For decades we have known that the brain "drains" through the subarachnoid space following a route that crosses the cribriform plate to the nasal mucosa and cervical lymph nodes. Yet little is known about the potential role of the olfactory epithelia and associated lymphatic vasculature in the immune response. To better understand the immune response in the olfactory organs we used cell-specific fluorescent reporter lines in dissected, intact adult brains to visualize blood-lymphatic vasculature and neutrophils in the olfactory sensory system. Here we show that the extensive blood vasculature of the olfactory organs is associated with a lymphatic cell type resembling high endothelial venules (HEVs) of the lymph nodes in mammals and a second resembling Mural Lymphatic Endothelial Cells (muLECs) that extended from the brain to the peripheral olfactory epithelia. Surprisingly, the olfactory organs contained the only neutrophil populations observed in the brain. Damage to the olfactory epithelia resulted in a rapid increase of neutrophils within the olfactory organs as well as the appearance of neutrophils in the brain suggesting that neutrophils enter the brain in response to damage. Analysis of cell division during and after damage showed an increase in BrdU labeling in the olfactory epithelia and a subset of the neutrophils. Our results reveal a unique population of neutrophils in the olfactory organs that are associated with an extensive lymphatic vasculature suggesting a dual olfactory-immune function for this unique sensory system. HighlightsO_LIThe olfactory organ is the only region of the brain that contains resident neutrophils in the adult animal. C_LIO_LIDamage to olfactory sensory neurons triggers a rapid mobilization of neutrophils within the olfactory organ and in the central nervous system. C_LIO_LITwo types of lymphatic vasculature resembling Mural Lymphatic Endothelial Cells (muLEC) and High Endothelial Venules (HEV) are present in the olfactory sensory system. C_LIO_LILymphatic vasculature resembling Mural Lymphatic Endothelial Cells (muLEC) wrap the olfactory bulbs and extend across the cribriform plate to olfactory epithelia. C_LI

neuroscience↗

bioRxiv2020

Intergenerational pathogen-induced diapause in C. elegans is modulated by mir-243.

The interaction and communication between bacteria and their hosts modulate many aspects of animal physiology and behavior. Dauer entry as a response to chronic exposure to pathogenic bacteria in Caenorhabditis elegans is an example of a dramatic survival response. This response is dependent on the RNAi machinery, suggesting the involvement of sRNAs as effectors. Interestingly, dauer formation occurs after two generations of interaction with two unrelated moderately pathogenic bacteria. Therefore, we sought to discover the identity of C. elegans RNAs involved in pathogen-induced diapause. Using transcriptomics and differential expression analysis of coding and long and small non-coding RNAs, we found that mir-243-3p is the only transcript continuously upregulated in animals exposed to both, P. aeruginosa or S. enterica for two generations. Phenotypic analysis of mutants showed that mir-243 is required for dauer formation under pathogenesis but not under starvation. Moreover, DAF-16, a master regulator of defensive responses in the animal and required for dauer formation was found to be necessary for mir-243 expression. This work highlights the role of a small non-coding RNA in the intergenerational defensive response against pathogenic bacteria and inter-kingdom communication. ImportancePersistent infection of the bacterivore nematode C. elegans with bacteria such as P. aeruginosa and S. enterica makes the worm diapause or hibernate. By doing this, the worm closes its mouth avoiding infection. This response takes two generations to be implemented. In this work, we looked for genes expressed upon infection that could mediate the worm diapause triggered by pathogens. We identify mir-243-3p as the only transcript commonly upregulated when animals feed on P. aeruginosa and S. enterica for two consecutive generations. Moreover, we demonstrate that mir-243-3p is required for pathogen-induced dauer formation, a new function that has not been previously described for this miRNA. We also find that the transcriptional activators DAF-16, PQM-1 and CRH-2 are necessary for the expression of mir-243 under pathogenesis. Here we establish a relationship between a small RNA and a developmental change that ensures the survival of a percentage of the progeny.

microbiology↗