Biology subjects

Schatz, B.

Publications and source records attributed to Schatz, B..

4 recordsLinked to original sources

bioRxiv2024

Multisensory gamma stimulation enhances adult neurogenesis and improves cognitive function in a mouse model of Down syndrome

Down syndrome (DS) has been linked with deficits in hippocampal dependent cognitive tasks and adult neurogenesis, yet treatment options are still very limited. We and others previously showed that a non-invasive multisensory gamma stimulation using light and sound at 40 Hz ameliorated Alzheimers disease pathology and symptoms in mouse models. In this study, we tested the effects of 40 Hz multisensory stimulation in the Ts65Dn mice, a mouse model of DS. For three weeks, mice were exposed daily to one hour of stimulation or one hour of ambient light and sound. Mice receiving the stimulation showed improved object recognition and spatial working memory. Using single nuclei RNA-seq and experimental validations in mouse hippocampal samples, we identified underlying expression changes in gene regulatory networks and demonstrated increased adult neurogenesis and reorganization of synapses as potential mechanisms for these improved cognitive phenotypes. Together, our data reveal a novel effect of multisensory gamma stimulation on adult neurogenesis and beneficial effects of 40 Hz treatment on cognitive function in DS model mice. Significance StatementWe present strong evidence, using a well-characterized mouse model, that the cognitive and neurogenesis deficits in Down syndrome can be improved through non-invasive multi-sensory gamma stimulation. Employing a systems biology approach, we provide extensive hippocampal single-cell resolution gene expression signatures and changes in gene regulatory networks in response to sensory gamma stimulation.

neuroscience↗

bioRxiv2024

Contrasting patterns of differentiation among three taxa of the rapidly diversifying orchid genus Ophrys sect. Insectifera (Orchidaceae) where their range overlap

In rapidly diversifying groups, taxa defined on the basis of typological criteria can be difficult to support with genetic data. The diversity observed in the insect-mimicking orchid genus Ophrys perfectly illustrates this situation; among 400 described species only 9-10 lineages are detectable by genetic markers such as nrITS. The three taxa described in the Ophrys insectifera group: O. insectifera, O. subinsectifera and O. aymoninii, can be clearly distinguished by their flowers, which have evolved different phenotypes as a result of adaptation to specific pollinator insect species from three different families. However, genetic differentiation between these three taxa has never been really supported by population genetic data and their taxonomic status is still debated. Using population genomic approaches, we found a clustering consistent with the existence of three genetic entities where the geographic distributions of the three taxa overlap. Two of these clusters correspond to France populations of the widespread O. insectifera and the micro-endemic O. aymoninii. However, the last cluster grouped together all the Iberian individuals, suggesting that individuals phenotypically identified as either O. insectifera or O. subinsectifera are genetically weakly differentiated there. Populations of the two pairs of taxa thus may have experienced different patterns of inter-specific gene flow.

evolutionary biology↗

bioRxiv2024

Floral phenotypic divergence and genomic insights in an Ophrys orchid: Unraveling early speciation processes

SummaryO_LIAdaptive radiation in Ophrys orchids leads to complex floral phenotypes that vary in scent, color and shape. C_LIO_LIUsing a novel pipeline to quantify these phenotypes, we investigated trait divergence at early stages of speciation in six populations of Ophrys aveyronensis experiencing recent allopatry. By integrating different genetic/genomic techniques, we investigated: (i) variation and integration of floral components (scent, color and shape), (ii) phenotypes and genomic regions under divergent selection, and (iii) the genomic bases of trait variation. C_LIO_LIWe identified a large genomic island of divergence, associated with phenotypic variation in particular in floral odor. We detected potential divergent selection on macular color, while convergent selection was suspected on floral morphology and for several volatile olfactive compounds. We also identify candidate genes involved in anthocyanin and in steroid biosynthesis pathways associated with standing genetic variation in color and odor. C_LIO_LIThis study sheds light on early differentiation in Ophrys, revealing patterns that often become invisible over time, i.e., the geographic mosaic of traits under selection and the early appearance of strong genomic divergence. It also supports a crucial genomic region for future investigation and highlights the value of a multifaceted approach in unraveling speciation within taxa with large genomes. C_LI

evolutionary biology↗

bioRxiv2023

Climate change promoted allopatric divergence and explains the current disjunct geographic distribution of the Ophrys aveyronensis species complex (Orchidaceae)

AimSpecies with disjunct geographic distributions provide natural opportunities to investigate incipient or recent allopatric divergence. The combination of both genetic and ecological data may be fruitful to decipher the causes of such pattern: i) actual vicariance, ii) successful colonization from one source range to a new range (dispersal, biological introduction) or iii) parallel convergent evolution. LocationSouthern France and Northern Spain. TaxonThe bee orchid Ophrys aveyronensis (and its two recognized subspecies O. a. subsp. aveyronensis and O. a. subsp. vitorica) displays a disjunct geographic distribution with two subranges separated by 600 km on both sides of the Pyrenees Mountains. MethodsThrough a combination of population genomics and Ecological Niche Modelling (ENM), we investigated the causes of this intriguing biogeographic pattern. ResultsThe population genomic data demonstrate that all the studied populations exhibit similar patterns of genetic diversity and dramatic decrease in effective size compared to the ancestral population. Significant genetic differentiation and reciprocal monophyly exist between populations of the two subranges of O. aveyronensis, despite a very recent divergence time as young as ca. 1500 generations ago. Moreover, (paleo-)ecological Niche Modelling analyses support that the disjunct geographic distribution of the O. aveyronensis is consistent with a range split of a broad ancestral range, contraction and distinct longitudinal and latitudinal shifts in response to climate warming during the Holocene. Main ConclusionThe congruence of the results obtained from both population genomics and ENM approaches documents how very recent continental allopatric divergence initiated speciation in this system. Ophrys aveyronensis provides a promising opportunity to study the onset of reproductive isolation and parallel evolution following an initial stage of geographic separation in a group with high diversification rate.

evolutionary biology↗