Group velocity study in hot Rb vapor with buffer gas

We study the behavior of the group velocity of light under conditions of electromagnetically induced transparency (EIT) in a Doppler broadened medium. Specifically, we show how the group delay (or group velocity) of probe and generated Stokes fields depends on the one-photon detuning of drive and probe fields. We find that for atoms in a buffer gas the group velocity decreases with positive one-photon detuning of the drive fields, and increases when the fields are red detuned. This dependence is counter-intuitive to what would be expected if the one-photon detuning resulted in an interaction of the light with the resonant velocity subgroup.Comment: 6 pages, 7 figure

Investigating the trafficking of Golgi-resident glycosylation enzymes

The Golgi is a major site of glycan processing mediated by a large number of Golgi-resident glycosylation enzymes. These enzymes are largely type II transmembrane domain (TMD) proteins consisting of a short N-terminal cytosolic tail, a short TMD and a lumenal ‘stem’ region which separates the catalytic domain and the lipid bilayer. The cytosolic tail, TMD, and stem together make the CTS domain which is responsible for the Golgi-targeting of these enzymes via multiple COPI-dependent mechanisms. What is not clear is the relative contribution of each mechanism to Golgi retention or how they work to fine tune the sub-Golgi localisation of these enzymes. To explore these nuances of intra-Golgi traffic, a MitoID proteomic screen was applied to the intra-Golgi golgin tethers GMAP-210 and golgin-84 to identify novel intra-Golgi vesicle-resident factors. The screen identified the Rab2 effector of unknown function FAM114A2. FAM114A2 and paralogous protein FAM114A1 were shown to specifically associate with early-Golgi membranes. A predicted ALPS motif was necessary for membrane association, presumably through non-specifically absorbing onto highly-curved membranes. Other regions of the proteins were required to mediate a specific association with membranes of the early-Golgi. GST affinity chromatography and mass spectrometry revealed that FAM114A1 pulled down Rab2A and Rab2B while FAM114A2 pulled down several COPI cargo proteins including many glycosylation enzymes. FAM114A2 interacted directly with the cytoplasmic tails of cargo which had a membrane-proximal polybasic motif. Similar binding studies revealed that the COPI adaptors GOLPH3+3L pulled down the COPI coat and over a hundred novel clients. GOLPH3+3L were shown to interact promiscuously with the cytoplasmic tails of clients with a total predicted charge of ≥4+. An in vivo Golgi retention assay revealed that tails which satisfy the GOLPH3+3L charge threshold are sufficient to impart Golgi-retention in a GOLPH3+3L-dependent manner. The deletion of FAM114A genes had no impact on retention in this assay. The assay also showed that the TMD of ST6GAL1 was sufficient to impart Golgi retention in a GOLPH3+3L-independent manner. The deletion of GOLPH3+3L, but not FAM114A genes, triggered the lysosomal degradation of COPI cargo and caused a global defect in glycosylation in U2OS cells. In contrast, deletion of the D. melanogaster FAM114A ortholog CG9590 caused a defect in mucin-type glycosylation in adult flies. CG9590 interacted directly with the COPI coat and pulled-down a host of COPI cargo proteins including mucin-type glycosylation enzymes. It is likely that FAM114A is an evolutionary-conserved COPI adaptor which acts to recycle a specific subset of COPI cargo from the early-Golgi. In contrast, GOLPH3 proteins are promiscuous COPI adaptors which function as master gatekeepers at the late-Golgi to recycle and retain a broad array of Golgi-residents

Third Annual Report of the Farm Management Service for Farmers in Soil Conservation Demonstration Areas for the year 1937 (April 1937 to March 1938)

Farm Management,

Crop Fertilization on East Texas Soils.

4 p

Experimental Analysis of Rotation in a Vertical Plane of Shallow Pier Foundations Subjected to a Couple

Agricultural Engineerin