Anti-TRAP alpha monoclonal antibody, clone 2.W.70

Auxin polar transport mediated by a group of Pin-formed (PIN) transporters plays important roles in plant root development. However, the mechanism underlying the PIN expression and targeting in response to different developmental and environmental stimuli is still not fully understood. Here, we report a previously uncharacterized gene SSR1, which encodes a mitochondrial protein with tetratricopeptide repeat (TPR) domains, and show its function in root development in Arabidopsis thaliana. In ssr1-2, a SSR1 knock-out mutant, the primary root growth was dramatically inhibited due to severely impaired cell proliferation and cell elongation. Significantly lowered level of auxin was found in ssr1-2 roots by auxin measurement and was further supported by reduced expression of DR5-driven reporter gene. As a result, the maintenance of the root stem cell niche is compromised in ssr1-2. It is further revealed that the expression level of several PIN proteins, namely, PIN1, PIN2, PIN3, PIN4 and PIN7, were markedly reduced in ssr1-2 roots. In particular, we showed that the reduced protein level of PIN2 on cell membrane in ssr1-2 is due to impaired retrograde trafficking, possibly resulting from a defect in retromer sorting system, which destines PIN2 for degradation in vacuoles. In conclusion, our results indicated that SSR1 is functioning in root development in Arabidopsis, possibly by affecting PIN protein expression and subcellular targeting. Significance StatementSSR1, a previous uncharacterized mitochondrial protein, is involved in Arabidopsis root development, possibly by affecting proper PIN protein expression and subcellular targeting.

Originally the spoke test cavity cryostat was designed to test exclusively SSR1 cavities. The goal of this upgrade is to extend this capability to SSR2 cavities, and to the low and high beta 650 MHz cavities. These cavities are the last elements of the superconducting linac architecture which is the main component of the Proton Improvement Plan-II (PIP-II) at Fermilab. The size of SSR2 and 650 MHz cavities being much bigger than SSR1, extensions of the vacuum vessel and of all the cryogenic lines have been necessary. Mechanical, thermal and cryogenic analyses have been performed to ensure proper operation. This paper summarizes the design choices which have been made by describing the main elements of this upgrade and the interface between cryogenic lines and cavities.