Biology subjects

Saar, M.

Publications and source records attributed to Saar, M..

3 recordsLinked to original sources

bioRxiv2023

Systematics of harvester ants (Messor) in Israel based on integrated morphological, genetic, and ecological data

Harvester ants of the genus Messor are considered ecosystem engineers, whose distribution is broadly influenced by a variety of environmental factors. Although distinct Messor species have been reported to inhabit different habitats, their taxonomy in Israel remains largely ambiguous, hampering the proper ecological characterization of these species. Here, we applied an integrative species delimitation approach combining morphology-based identification, phylogenetic analyses of nuclear and mitochondrial genes, and ecological niche modelling to investigate the phylogenetic relationships among Messor species in the small but ecologically diverse region of Israel. Our analyses of mitochondrial genes revealed the presence of at least 13 well-defined lineages, whereas only seven were supported by the analysis of the nuclear genes. However, the concatenated tree that included all the three markers supported 11 lineages. Among two of the lineages-in M. semirufus and in a group of ants closest in resemblance to M. grandinidus- we identified 3-4 clades that were well established on most trees, inviting further study. In addition, we reveal three undescribed species and raise two subspecies to species rank, highlighting the high diversity of harvester ants in Israel. Ecological niche modelling consistently supported the observed distribution of species, with soil type and average annual temperature being the most influential factors. These results demonstrate that species distribution modelling can serve as a valuable component of integrative species delimitation. We call for future studies to investigate these fascinating lineages of one of the most prominent and ecologically important genera of ants in the Mediterranean Basin.

ecology↗

bioRxiv2023

Seasonality effects and field-estimation of colony size in desert ants

The colony level of eusocial insects is considered the reproductive unit on which natural selection operates. Therefore, seasonal demographic movements and estimations of colony size are crucial variables. Excavating colonies of ants to extract their size is daunting, unhealthy to the surrounding environment, and it may prevent long-term research, including testing seasonal effects on colony size. Previous capture-recapture methods that avoid excavating colonies have been proven inefficient when sampling mostly underground dwellers as ants. To address this issue, we offer a simple method to estimate the colony size of desert ants (Cataglyphis niger) in a field setting- based on a field experiment, a literature review, and four laboratory experiments. First, we find that between 10-15% of the colony size are outgoing foragers. Second, we find seasonal effects on colony size and foraging activity: colony size varies and is larger in winter than in summer, and in contrast - the proportion of foragers out of colony size is higher in summer than in winter. This suggests that the energetic requirements of the colonies are higher in summer than in winter. Based on uniquely large sample size, our proposed field method may be useful for other co-occurring Cataglyphis species. Moreover, extracting ant colony sizes and evaluating ant biomass is advantageous for future studies to evaluate the carrying capacity of semi sand-dunes habitats.

ecology↗

bioRxiv2021

Aplp1 and the Aplp1-Lag3 Complex facilitates transmission of pathologic alpha-synuclein

Pathologic -synuclein (-syn) spreads from cell-to-cell, in part, through binding to the lymphocyte-activation gene 3 (Lag3). Here we report that amyloid {beta} precursor-like protein 1 (Aplp1) forms a complex with Lag3 that facilitates the binding, internalization, transmission, and toxicity of pathologic -syn. Deletion of both Aplp1 and Lag3 eliminates the loss of dopaminergic neurons and the accompanying behavioral deficits induced by -syn preformed fibrils (PFF). Anti-Lag3 prevents the internalization of -syn PFF by disrupting the interaction of Aplp1 and Lag3, and blocks the neurodegeneration induced by -syn PFF in vivo. The identification of Aplp1 and the interplay with Lag3 for -syn PFF induced pathology advances our understanding of the molecular mechanism of cell-to-cell transmission of pathologic -syn and provides additional targets for therapeutic strategies aimed at preventing neurodegeneration in Parkinsons disease and related -synucleinopathies. One Sentence SummaryAplp1 forms a complex with Lag3 that facilitates the binding, internalization, transmission, and toxicity of pathologic -synuclein. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=94 SRC="FIGDIR/small/442157v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@1d746bforg.highwire.dtl.DTLVardef@65acb2org.highwire.dtl.DTLVardef@12cf2f0org.highwire.dtl.DTLVardef@19d6e_HPS_FORMAT_FIGEXP M_FIG Aplp1 and the Aplp1-Lag3 complex facilitates transmission of pathologic -synuclein. Aplp1 is a receptor that drives pathologic -syn transmission, and genetic depletion of Aplp1 can significantly reduce the -synuclein pathogenesis. Aplp1 and Lag3 forms an Aplp1-Lag3 complex that accounts for substantial binding of pathologic -syn to cortical neurons. Together Aplp1 and Lag3 play a major role in pathologic -syn internalization, transmission and toxicity. Double knockout of Aplp1 and Lag3 and or a Lag3 antibody that disrupts the Aplp1 and Lag3 complex almost completely blocks -syn PFF-induced neurodegeneration. C_FIG

neuroscience↗