Ultrastructure of the Gill Rakers in American Shad, Alosa sapidissima (Clupeidae)

The American shad (Alosa sapidissima) is an anadromous fish that uses suspension feeding to obtain nutrients. The oral morphology of this species is scarcely understood or documented in scientific literature. Information on the specific cell types and structure of gill rakers on the gill arches could provide significant insight into the crossflow filtration mechanism of this species. Scanning electron microscopy (SEM) and literature comparison were used to identify cell types and microstructures of the raker. Using this comparison, mucous cells, pavement cells, and chloride cells were identified. Distinct patterning and density of mucous cells and pavement cells were measured using SEM imaging and ImageJ software. A significant cell density difference was identified in mucous cells medial and lateral to the denticle structures. These data provide insight into the function of these cell types in particle filtration, water flow, organismal defense, and pH regulation

The transcriptional landscape of αβ T cell differentiation.

The differentiation of αβT cells from thymic precursors is a complex process essential for adaptive immunity. Here we exploited the breadth of expression data sets from the Immunological Genome Project to analyze how the differentiation of thymic precursors gives rise to mature T cell transcriptomes. We found that early T cell commitment was driven by unexpectedly gradual changes. In contrast, transit through the CD4(+)CD8(+) stage involved a global shutdown of housekeeping genes that is rare among cells of the immune system and correlated tightly with expression of the transcription factor c-Myc. Selection driven by major histocompatibility complex (MHC) molecules promoted a large-scale transcriptional reactivation. We identified distinct signatures that marked cells destined for positive selection versus apoptotic deletion. Differences in the expression of unexpectedly few genes accompanied commitment to the CD4(+) or CD8(+) lineage, a similarity that carried through to peripheral T cells and their activation, demonstrated by mass cytometry phosphoproteomics. The transcripts newly identified as encoding candidate mediators of key transitions help define the known unknowns of thymocyte differentiation

The transcriptional landscape of αβ T cell differentiation.

The differentiation of αβT cells from thymic precursors is a complex process essential for adaptive immunity. Here we exploited the breadth of expression data sets from the Immunological Genome Project to analyze how the differentiation of thymic precursors gives rise to mature T cell transcriptomes. We found that early T cell commitment was driven by unexpectedly gradual changes. In contrast, transit through the CD4(+)CD8(+) stage involved a global shutdown of housekeeping genes that is rare among cells of the immune system and correlated tightly with expression of the transcription factor c-Myc. Selection driven by major histocompatibility complex (MHC) molecules promoted a large-scale transcriptional reactivation. We identified distinct signatures that marked cells destined for positive selection versus apoptotic deletion. Differences in the expression of unexpectedly few genes accompanied commitment to the CD4(+) or CD8(+) lineage, a similarity that carried through to peripheral T cells and their activation, demonstrated by mass cytometry phosphoproteomics. The transcripts newly identified as encoding candidate mediators of key transitions help define the 'known unknowns' of thymocyte differentiation