The Grizzly, September 15, 1989

Greek Golden Age Growing Dark • U.C. Slasher Case Finally Closed • Letters: Physics Major Majorly Miffed; Wismer Eggs on Disgusted Diner • SAO Makes Room for Zimmer • Go Abroad: It\u27s Worth It • Mann\u27s Soda Can Hit with Crowd • Bears Upset Hoyas in Season Opener • Grizzlies Take Tourney with Defense • V-ball: Victors! • Endurance is Key • Athletes of the Week • Pledging: Git! • Myrin Booking • Lucas Heads Frosh Seminar • Dumas: Cook of Monte Cristo • Smith Donation • Freshmen Make Necessary Adjustmentshttps://digitalcommons.ursinus.edu/grizzlynews/1240/thumbnail.jp

Life in the dark: far‐red absorbing cyanobacteria extend photic zones deep into terrestrial caves

Chlorophyll (Chl) f and d are the most recently discovered chlorophylls, enabling cyanobacteria to harvest near‐infrared radiation (NIR) at 700–780 nm for oxygenic photosynthesis. Little is known about the occurrence of these pigments in terrestrial habitats. Here, we provide first details on spectral photon irradiance within the photic zones of four terrestrial cave systems in concert with a detailed investigation of photopigmentation, light reflectance and microbial community composition. We frequently found Chl f and d along the photic zones of caves characterized by low light enriched in NIR and inhabited by cyanobacteria producing NIR‐absorbing pigments. Surprisingly, deeper parts of caves still contained NIR, an effect likely attributable to the reflectance of specific wavelengths by the surface materials of cave walls. We argue that the stratification of microbial communities across the photic zones of cave entrances resembles the light‐driven species distributions in forests and aquatic environments

Phosphorylation of eucaryotic translation initiation factor 4B Ser422 is modulated by S6 kinases

The eucaryotic translation initiation factor 4B (eIF4B) stimulates the helicase activity of the DEAD box protein eIF4A to unwind inhibitory secondary structure in the 5′ untranslated region of eucaryotic mRNAs. Here, using phosphopeptide mapping and a phosphospecific antiserum, we identify a serum-responsive eIF4B phosphorylation site, Ser422, located in an RNA-binding region required for eIF4A helicase-promoting activity. Ser422 phosphorylation appears to be regulated by the S6Ks: (a) Ser422 phosphorylation is sensitive to pharmacological inhibitors of phosphoinositide-3 kinase and the mammalian target of rapamycin; (b) S6K1/S6K2 specifically phosphorylate Ser422 in vitro; and (c) rapamycin-resistant S6Ks confer rapamycin resistance upon Ser422 phosphorylation in vivo. Substitution of Ser422 with Ala results in a loss of activity in an in vivo translation assay, indicating that phosphorylation of this site plays an important role in eIF4B function. We therefore propose that eIF4B may mediate some of the effects of the S6Ks on translation