T cell activation potently stimulates cellular metabolism to support the elevated energetic and biosynthetic demands of growth, proliferation, and effector function. We show that glucose uptake is limiting in T cell activation and that CD28 costimulation is required to allow maximal glucose uptake following TCR stimulation by up-regulating expression and promoting the cell surface trafficking of the glucose transporter Glut1. Regulation of T cell glucose uptake and Glut1 was critical, as low glucose prevented appropriate T cell responses. Additionally, transgenic expression of Glut1 augmented T cell activation, and led to accumulation of readily activated memory-phenotype T cells with signs of autoimmunity in aged mice. To further examine the regulation of glucose uptake, we analyzed CD28 activation of Akt, which appeared necessary for maximal glucose uptake of stimulated cells and which we have shown can promote Glut1 cell surface trafficking. Consistent with a role for Akt in Glut1 trafficking, transgenic expression of constitutively active myristoylated Akt increased glucose uptake of resting T cells, but did not alter Glut1 protein levels. Therefore, CD28 appeared to promote Akt-independent up-regulation of Glut1 and Akt-dependent Glut1 cell surface trafficking. In support of this model, coexpression of Glut1 and myristoylated Akt transgenes resulted in a synergistic increase in glucose uptake and accumulation of activated T cells in vivo that were largely independent of CD28. Induction of Glut1 protein and Akt regulation of Glut1 trafficking are therefore separable functions of CD28 costimulation that cooperate to promote glucose metabolism for T cell activation and proliferation.

Capture–recapture methods are commonly used to estimate population parameters when the necessary assumptions are met. One of the broadest assumptions of capture–recapture models is that tags are not lost. Therefore, one must understand tag retention to be able to adjust estimates if tag loss occurs. Our objectives were to (1) determine retention rates of T‐bar anchor tags and passive integrated transponder (PIT) tags injected into the dorsal musculature of shovelnose sturgeon Scaphirhynchus platorynchus and (2) determine whether using an alternative PIT‐tagging location (the operculum) and a new tagging procedure (cyanoacrylate [i.e., superglue] to seal the tag insertion point) provided higher retention. The T‐bar tags had a retention rate of 100%; PIT tag retention, however, was more variable. Injection of PIT tags along the dorsal fin resulted in a retention rate of 73%, and tag loss was observed throughout the 98‐d experiment. The application of cyanoacrylate did not appear to deter PIT tag loss; retention rates before and after cyanoacrylate was applied were 73% and 77%, respectively. Further, we observed a similar trend of continual PIT tag loss throughout the experiment. The operculum location resulted in a 92% PIT tag retention rate and showed no trend in cumulative loss through time. The high retention rate of PIT tags placed in the operculum suggests that this location is a reliable alternative to inserting PIT tags along the dorsal fin of adult Scaphirhynchus species. In addition, the excellent retention of T‐bar tags makes them a viable option for use in Scaphirhynchus studies. Received October 8, 2011; accepted March 1, 2012

Goto, Daisuke; Hamel, Martin J.; Hammen, Jeremy J.; Rugg, Mathew L.; Pegg, Mark A.; and Forbes, Valery E., "Spatiotemporal variation in flow-dependent recruitment of long-lived riverine fish: Model development and evaluation" (2014). Faculty Publications in the Biological Sciences. 369.