ALBERT

Beschreibung: In nature, most organisms experience conditions that are suboptimal for growth. To survive, cells must fine-tune energy-demanding metabolic processes in response to nutrient availability. Here, we describe a novel mechanism by which protein synthesis in starved cells is down-regulated by phosphorylation of the universally conserved elongation factor Tu (EF-Tu). Phosphorylation impairs the essential GTPase activity of EF-Tu, thereby preventing its release from the ribosome. As a consequence, phosphorylated EF-Tu has a dominant-negative effect in elongation, resulting in the overall inhibition of protein synthesis. Importantly, this mechanism allows a quick and robust regulation of one of the most abundant cellular proteins. Given that the threonine that serves as the primary site of phosphorylation is conserved in all translational GTPases from bacteria to humans, this mechanism may have important implications for growth-rate control in phylogenetically diverse organisms.

Beschreibung: Sugars are essential molecules for all terrestrial biota working in many biological processes. Ribose is particularly essential as a building block of RNA, which could have both stored information and catalyzed reactions in primitive life on Earth. Meteorites contain a number of organic compounds including key building blocks of life, i.e., amino acids, nucleobases, and phosphate. An amino acid has also been identified in a cometary sample. However, the presence of extraterrestrial bioimportant sugars remains unclear. We analyzed sugars in 3 carbonaceous chondrites and show evidence of extraterrestrial ribose and other bioessential sugars in primitive meteorites. The 13C-enriched stable carbon isotope compositions (δ13C vs.VPDB) of the detected sugars show that the sugars are of extraterrestrial origin. We also conducted a laboratory simulation experiment of a potential sugar formation reaction in space. The compositions of pentoses in meteorites and the composition of the products of the laboratory simulation suggest that meteoritic sugars were formed by formose-like processes. The mineral compositions of these meteorites further suggest the formation of these sugars both before and after the accretion of their parent asteroids. Meteorites were carriers of prebiotic organic molecules to the early Earth; thus, the detection of extraterrestrial sugars in meteorites establishes the existence of natural geological routes to make and preserve them as well as raising the possibility that extraterrestrial sugars contributed to forming functional biopolymers like RNA on the early Earth or other primitive worlds.

Beschreibung: Discharge in mountain streams may be a mixture of snowmelt, water from surface runoff, and deep return flow through valley bottom alluvia. We used δ 18 O and δ 2 H, solute concentrations, and 222 Rn to determine water sources of a headwater stream located at the McDonald Creek watershed, Glacier National Park, USA during summer recession flow period. We analyzed minimal water isotope ranges of -17.6 to -16.5‰ and -133 to -121‰ for δ 18 O and δ 2 H, respectively, potentially due to dominance of snow-derived water in the stream. Likewise, solute concentrations measured in the stream through the watershed showed minimal variation with little indication of sub-surface water input into the stream. However, we observed 222 Rn activities in the stream that ranged from 39 to 2,646 Bq/m 3 with the highest value measured in middle of the watershed associated with channel constriction corresponding to changes in local orientation of underlying rocks. Downstream from this point, 222 Rn activity decreased from 581 to 117 Bq/m 3 in a series of punctuated steps associated with small rapids and waterfalls that we hypothesized to cause radon degassing with a maximum predicted loss of 427 Bq/m 3 along a 400 m distance. Based on mass balance calculations using 222 Rn activity values, streamflow, and channel characteristics, we estimated that groundwater contributed between 0.3 and 29% of total flow. Overall, we estimated a 5.9% of groundwater contribution integrated for stream reach measured at McDonald Creek during recession flow period. Finally, a lower mean hyporheic flux of 14 m 3 /day was estimated compared to the groundwater flux of 70,710 m 3 /day. These assessments highlight the potential for radon as a conservative tracer that can be used to estimate sub-surface water contribution in mountain streams within a complex geologic setting. This article is protected by copyright. All rights reserved.

Beschreibung: Kratom is a tree planted in Southeast Asia, including Thailand, Malaysia, Myanmar (Burma) and elsewhere in the region. A long history of usage and abuse of kratom has led to the classification of kratom as a controlled substance in its native Thailand and other Southeast Asian countries. However, kratom is not controlled in the United States, and the wide availability of kratom on the Internet and in the streets has led to its emergence as an herbal drug of misuse. With the increasing popularity of kratom, efficient protocols are needed to detect kratom use. In this study, a rapid method for the analysis of kratom compounds, mitragynine and 7-hydroxymitragynine, in human urine has been developed and validated using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The chromatographic system employed a 2.6-μm 100 mm × 2.1 mm phenyl-hexyl analytical column and gradient elution with a 0.4-mL/min flow rate of water and acetonitrile as mobile phases. A triple quadrupole mass spectrometer was used as the detector for data acquisition. The analyst was the quantification software. The established method demonstrated linearity of >0.99 for both analytes, and low detection limits were obtained down to 0.002581 ng/mL for mitragynine and 0.06910 ng/mL for 7-hydroxymitragynine. The validated method has been utilized for clinical analysis of urine for the purpose of mitragynine and 7-hydroxymitragynine detection.

Beschreibung: Genes in the sex determination pathway are important regulators of sexually dimorphic animal traits, including the elaborate and exaggerated male ornaments and weapons of sexual selection. In this study, we id...

Beschreibung: Many bacteria exist in a state of metabolic quiescence where energy consumption must be minimized so as to maximize available resources over a potentially extended period of time. As protein synthesis is the most energy intensive metabolic process in a bacterial cell, it would be an appropriate target for down-regulation during the transition from growth to quiescence. We observe that whenBacillus subtilisexits rapid growth, a subpopulation of cells emerges with very low protein synthetic activity. This phenotypic heterogeneity requires the production of the nucleotides (p)ppGpp, which we show are sufficient to inhibit protein synthesis in vivo. We then show that one of these molecules, ppGpp, inhibits protein synthesis by preventing the allosteric activation of the essential GTPase Initiation Factor 2 (IF2) during translation initiation. Finally, we demonstrate that the observed attenuation of protein synthesis during the entry into quiescence is a consequence of the direct interaction of (p)ppGpp and IF2.

Beschreibung: In nature, most organisms experience conditions that are suboptimal for growth. To survive, cells must fine-tune energy-demanding metabolic processes in response to nutrient availability. Here, we describe a novel mechanism by which protein synthesis in starved cells is down-regulated by phosphorylation of the universally conserved elongation factor Tu (EF-Tu). Phosphorylation...

Beschreibung: During the Late Triassic, western equatorial Pangea, in the present-day American Southwest, was unusually humid, as indicated by sedimentological evidence and inferred from general circulation models. These studies show that once equatorial Pangea was assembled, cross-equatorial summer air flow penetrated into western equatorial Pangea, bringing abundant megamonsoon rainfall and warm temperatures. However, many of these investigations indicate that gradual aridification began sometime during the Late Triassic to Jurassic. We show from field properties, geochemical transfer functions, and isotopic analysis of paleosols in the Chinle Formation of Petrified Forest National Park, Arizona, that the western equatorial Pangea megamonsoon collapsed by 214.7 Ma during the "middle Norian climate shift." Paleosols include Entisols, Inceptisols, Vertisols, Aridisols, and Alfisols, with transfer functions for mean annual precipitation (chemical index of alteration minus potassium [CIA–K]) and mean annual temperature (NAK) (salinization) developed from analogous modern data sets. The most notable shift is the appearance of carbonate-enriched paleo-Inceptisols and paleo-Vertisols after 214.7 Ma and paleo-Aridisols after 210 Ma. Prior to the middle Norian climate shift, the region is classified as humid (humidity province) based on rainfall estimates. Initiation of the middle Norian climate shift was characterized by an increase in paleosol carbonate content and rapidly declining rainfall as the region shifted to subhumid, and eventually to semiarid and arid after 210 Ma. Paleosol-derived temperatures are indicative of warm temperate to subtropical ecozones, whereas general circulation models show higher temperatures and tropical conditions, perhaps because boundary conditions were set to atmospheric p CO 2 4–5 x present. Elevations of 〉1.5–2 km adjacent to the Cordilleran magmatic arc complex located ~400 km west of the study area may account for nontropical temperatures. After 210 Ma, however, temperatures began to increase, possibly as a result of escalating atmospheric p CO 2 from shale oxidation during marine regression and from coal and paleosol organic matter oxidation during prolonged aridification. Paleomagnetic studies have suggested northward continental drift of western equatorial Pangea to outside of the Intertropical Convergence Zone as the cause of monsoonal collapse during the Late Triassic to Early Jurassic. The formation of a rain shadow as a result of the evolving Cordilleran magmatic arc as the cause of aridification is supported by recent magnetostratigraphic work substantiating that the region remained in the tropics through the Triassic. According to our age model, the middle Norian climate shift is dated to near the same time as the Manicouagan impact crater, but there is no evidence of such an event in the study area, either geochemically or sedimentologically at our scale of observation. However, a regionally defined faunal turnover may have been a response to rapidly changing climates in the region.