Magyar, D. | bioRxiv Science

bioRxiv2024

Metagenomic peek into a corn mummy

Numerous studies have shown that metagenomics has opened a dimension in reading the contents of archaeological remains as time capsules. Corn mummies are ritual objects from ancient Egypt, created by forming human-shaped figures from cereal grains grown in a mixture of water and earth. The aim of our study was to determine whether ancient DNA could be preserved in the mummy, and if so, which organisms it might have originated from. To find answers, we performed metagenomic analyses on samples taken from a corn mummy dating to the second half of the third century BC. Alongside a number of clearly modern contaminants, we identified organisms that cannot be excluded as being of historical origin. Besides considerable amounts of bacterial sequences belonging to the genus Bacillus, Mesobacillus, Metabacillus, Neobacillus, Niallia, Peribacillus and Paenibacillus, we also found traces of plants, animals, and humans. Sequences assigned to the genus Triticum showed the highest similarity to ancient T. turgidum ssp. dicoccum specimens from Egypt and the southern Levant. The fragments identified as of Lepidopteran origin showed the greatest similarity to Sphingidae genomes. Analysis of the human-derived sequences revealed L3 (mtDNA), E, and J (Y chromosome) haplotypes, which are common lineages in Africa today.

bioinformatics↗

bioRxiv2023

Diversity and connectivity of principal neurons in the lateral and basal nuclei of the mouse amygdala

The basolateral amygdala is a non-layered cortical structure playing a role in various cognitive processes. Despite many studies focusing on local information processing within the circuits of the basolateral amygdala, the characteristics of excitatory principal neurons (PNs) are still not fully revealed. Here, we combined neuroanatomical, electrophysiological, and tracing techniques to determine the single-cell features, dendritic and axonal projections of PNs within the lateral (LA) and basal amygdala (BA). Using a mouse reporter line, we found that cholecystokinin (CCK) expression defines two spatially and functionally segregated groups of PNs both in the LA and BA. PNs in CCK-positive (CCK+) areas of the LA (LAa) had small somata and short dendrites which matched their single-cell electrophysiological properties. PNs in CCK-negative (CCK-) areas of the LA (LAp) and all BA had similarly ramified dendrites and single-cell features with some differences. Importantly, the dendritic arbors of PNs were restricted to the subnuclei defined by CCK expression, which corresponded to various extra-amygdalar afferents indicating specific inputs on distinct PN groups. Axonal arborization patterns of PNs within the basolateral amygdala and surrounding areas showed consistency to their soma location. For instance, BA PNs that projected to the medial prefrontal cortex but not to the lateral nucleus of the central amygdala were present in CCK+ areas. In contrast, those BA PNs that projected to the lateral part of the central nucleus were found in the subnucleus lacking CCK. Our study revealed that the basolateral amygdala is composed of functionally different subnuclei with specific inputs and outputs. This structural arrangement may empower the LA and BA to flexibly channel processed information toward their downstream regions, which can be a key requirement for diverse amygdala functions in cognitive operation.

neuroscience↗