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Biology subjects

Sharma, A. M.

Publications and source records attributed to Sharma, A. M..

2 recordsLinked to original sources

Developmental stage and level of submersion in water impact the viability of lone star and winter tick eggs during flooding

Female ticks deposit large egg clusters that range in size from hundreds to thousands eggs each. These clusters are immobile and restricted to a deposition site, usually under leaf litter and other debris. These sites can be exposed to periodic flooding, where the cluster of tick eggs can float to the surface or remain underneath organic debris entirely submerged underwater. Here, we examined the viability of egg clusters from winter ticks, Dermacentor albipictus, and lone star ticks, Amblyomma americanum, when partially or fully submerged in water and in relation to the developmental stages of the eggs. In general, egg clusters that were older and partially submerged had a higher viability than fully submerged, younger eggs. A. americanum was more resistant to water exposure between the two species. These studies highlight that egg clusters for certain tick species can remain viable when exposed to water for at least two weeks. These studies also suggest that distribution by flooding of egg clusters could occur for some species and flooding will differentially impact tick egg survival based on the specific developmental stage of exposure and species.

ecology↗

Tau monomer encodes strains

Tauopathies have diverse presentation, progression, and neuropathology. They are linked to tau prion strains, self-replicating assemblies of unique quaternary conformation. Strains can be propagated indefinitely in cultured cells, and induce unique patterns of transmissible neuropathology upon inoculation into mice. Aggregates from a single strain reproduce only that strain upon re-inoculation into cells or mice. DS9 and DS10 cell lines propagate distinct synthetic strains. Surprisingly, DS9 monomer inoculated into naive cells encoded an identical \"sub-strain,\" whereas DS10 monomer encoded multiple sub-strains. Sub-strains produced distinct pathology upon inoculation into a tauopathy mouse model (PS19). Brain-derived tau monomer from an Alzheimers brain encoded a single strain. Monomer from a corticobasal degeneration brain encoded three sub-strains in which monomer from each encoded all three upon re-inoculation into cells. Tau monomer thus adopts multiple, stable seed-competent conformations, each of which encodes a limited number of strains. This provides insights into the origins of distinct tauopathies.

biochemistry↗