2.4 "The Strange Disappearance of Lloyd Gaines"

The May 1951 Ebony Magazine Article "The Strange Disappearance of Lloyd Gaines"

Expression of Ornithine Decarboxylase Is Transiently Increased by Pollination, 2,4-Dichlorophenoxyacetic Acid, and Gibberellic Acid in Tomato Ovaries1

A cDNA encoding for a functional ornithine decarboxylase has been isolated from a cDNA library of carpels of tomato (Lycopersicon esculentum Mill.). Ornithine decarboxylase in tomato is represented by a single-copy gene that we show to be up-regulated during early fruit growth induced by 2,4-dichlorophenoxyacetic acid and gibberellic acid.

Characterization of Recombinant Rhamnogalacturonan α-l-Rhamnopyranosyl-(1,4)-α-d-Galactopyranosyluronide Lyase from Aspergillus aculeatus1 : An Enzyme That Fragments Rhamnogalacturonan I Regions of Pectin

The four major oligomeric reaction products from saponified modified hairy regions (MHR-S) from apple, produced by recombinant rhamnogalacturonan (RG) α-l-rhamnopyranosyl-(1,4)-α-d-galactopyranosyluronide lyase (rRG-lyase) from Aspergillus aculeatus, were isolated and characterized by 1H-nuclear magnetic resonance spectroscopy. They contain an alternating RG backbone with a degree of polymerization of 4, 6, 8, and 10 and with an α-Δ-(4,5)-unsaturated d-galactopyranosyluronic acid at the nonreducing end and an l-rhamnopyranose at the reducing end. l-Rhamnopyranose units are substituted at C-4 with β-galactose. The maximum reaction rate of rRG-lyase toward MHR-S at pH 6.0 and 31°C was 28 units mg−1. rRG-lyase and RG-hydrolase cleave the same alternating RG I subunit in MHR. Both of these enzymes fragment MHR by a multiple attack mechanism. The catalytic efficiency of rRG-lyase for MHR increases with decreasing degree of acetylation. Removal of arabinose side chains improves the action of rRG-lyase toward MHR-S. In contrast, removal of galactose side chains decreased the catalytic efficiency of rRG-lyase. Native RG-lyase was purified from A. aculeatus, characterized, and found to be similar to the rRG-lyase expressed in Aspergillus oryzae.

Blockade of T- and B-lymphocyte development by antibody to the gamma c subunit of the receptors for interleukins 2, 4, and 7.

Cytokines are important regulators of hematopoesis. Mutations in gamma c, which is a subunit shared by the receptors for interleukin (IL) 2, IL-4, and IL-7, have been causally associated with human X chromosome-linked severe combined immunodeficiency disease. This finding indicates a mandatory role for cytokine receptor signaling at one or more stages of lymphocyte development. To evaluate the cellular level at which gamma c is critical for lymphopoiesis, the effect of monoclonal antibodies to gamma c on the capacity of syngeneic bone marrow cells to reconstitute the hematopoietic compartment of lethally irradiated recipient mice was examined. We show that monoclonal antibody to gamma c blocked lymphocyte development at or before the appearance of pro-B cells and prior to or at the seeding of the thymus by precursor cells while erythromyeloid cell development was normal. These results suggest that one level of lymphocyte development that requires gamma c is a point in hematopoietic cell differentiation near the divergence of lymphopoiesis and erythromyelopoesis.