Letter from A. H. Voorhies to John Muir, 1905 Sep 29.

[letterhead]Sept 29. 05Mr John MuirMartinez,Dear Sir,Have you made a publication of your observations during your late trip through Russia and the Phillipines? If so, where can such be found?I read and re-read your former works. Please drop me a line on 03641 the matter.And obligeYours truly,A H Voorhie

Investigation of Microbial Interactions and Ecosystem Dynamics in a Low O2 Cyanobacterial Mat.

Cyanobacteria are believed to be responsible for the oxygenation of the Earth’s atmosphere and oceans, which enabled the evolution of metabolisms that depend on O2. Little is known about cyanobacteria adapted to low-O2, sulfidic conditions, which dominated the oceans when oxygenic photosynthesis first evolved. To better understand how such cyanobacteria function and contribute to biogeochemistry, metagenomics and metatranscriptomics were used to characterize modern cyanobacterial mats that thrive under low-O2, sulfidic conditions in the Middle Island Sinkhole (MIS) of Lake Huron. Metagenomics revealed a consortium of microorganisms that regulate biogeochemical cycling at the sediment/water interface. The mats were dominated by Phormidium, a cyanobacterium that was inferred to perform anoxygenic photosynthesis in the presence of sulfide based on (i) primary production rate experiments, (ii) expression of sulfide quinone reductase, and (iii) a high ratio of transcripts for photosystem I to photosystem II. Combined with excess organic matter, chemical reductants and rapid utilization of O2 by respiration, this anoxygenic photosynthesis makes the MIS mats a net sink for O2. Such anoxygenic cyanobacterial mats were likely widespread under the low-O2 conditions of the Proterozoic, and may help to explain why atmospheric O2 levels remained low for much of Earth’s history. Genome sequences were reconstructed for the dominant mat organisms, and transcript abundance was used to identify organisms expressing metabolic pathways that regulate geochemical cycling at MIS. Desulfobacterales were responsible for mediating production of sulfide, which likely contributes to hypoxia at MIS and regulates oxygenic versus anoxygenic photosynthesis by Phormidium. Members of the Proteobacteria were found to perform aerobic oxidation of various sulfur species, H2 and CO. Viral predation was detected by two way exchange of DNA between Phormidium and PhV1, an abundant virus at MIS. Phormidium used viral DNA within a CRISPR system to defend itself, while PhV1 was found to possess a host derived nblA gene, which breaks down photosynthetic pigments. Overall, this work suggests that ancient cyanobacterial mats were not necessarily a source for O2, and that sulfide concentration, metabolic products from other organisms, viral predation, and light availability could all influence cyanobacterial production of O2 in low-O2 environments.PHDEarth and Environmental SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/107234/1/alexav_1.pd

Effect of Low Shear Modeled Microgravity (LSMMG) on the Probiotic Lactobacillus Acidophilus ATCC 4356

The introduction of generally recognized as safe (GRAS) probiotic microbes into the spaceflight food system has the potential for use as a safe, non-invasive, daily countermeasure to crew microbiome and immune dysregulation. However, the microgravity effects on the stress tolerances and genetic expression of probiotic bacteria must be determined to confirm translation of strain benefits and to identify potential for optimization of growth, survival, and strain selection for spaceflight. The work presented here demonstrates the translation of characteristics of a GRAS probiotic bacteria to a microgravity analog environment. Lactobacillus acidophilus ATCC 4356 was grown in the low shear modeled microgravity (LSMMG) orientation and the control orientation in the rotating wall vessel (RWV) to determine the effect of LSMMG on the growth, survival through stress challenge, and gene expression of the strain. No differences were observed between the LSMMG and control grown L. acidophilus, suggesting that the strain will behave similarly in spaceflight and may be expected to confer Earth-based benefits

Cyanobacterial life at low O 2 : community genomics and function reveal metabolic versatility and extremely low diversity in a Great Lakes sinkhole mat

Cyanobacteria are renowned as the mediators of Earth’s oxygenation. However, little is known about the cyanobacterial communities that flourished under the low‐O 2 conditions that characterized most of their evolutionary history. Microbial mats in the submerged Middle Island Sinkhole of Lake Huron provide opportunities to investigate cyanobacteria under such persistent low‐O 2 conditions. Here, venting groundwater rich in sulfate and low in O 2 supports a unique benthic ecosystem of purple‐colored cyanobacterial mats. Beneath the mat is a layer of carbonate that is enriched in calcite and to a lesser extent dolomite. In situ benthic metabolism chambers revealed that the mats are net sinks for O 2 , suggesting primary production mechanisms other than oxygenic photosynthesis. Indeed, 14 C‐bicarbonate uptake studies of autotrophic production show variable contributions from oxygenic and anoxygenic photosynthesis and chemosynthesis, presumably because of supply of sulfide. These results suggest the presence of either facultatively anoxygenic cyanobacteria or a mix of oxygenic/anoxygenic types of cyanobacteria. Shotgun metagenomic sequencing revealed a remarkably low‐diversity mat community dominated by just one genotype most closely related to the cyanobacterium Phormidium autumnale , for which an essentially complete genome was reconstructed. Also recovered were partial genomes from a second genotype of Phormidium and several Oscillatoria . Despite the taxonomic simplicity, diverse cyanobacterial genes putatively involved in sulfur oxidation were identified, suggesting a diversity of sulfide physiologies. The dominant Phormidium genome reflects versatile metabolism and physiology that is specialized for a communal lifestyle under fluctuating redox conditions and light availability. Overall, this study provides genomic and physiologic insights into low‐O 2 cyanobacterial mat ecosystems that played crucial geobiological roles over long stretches of Earth history.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90535/1/j.1472-4669.2012.00322.x.pd

Negative phenotypic and genetic associations between copulation duration and longevity in male seed beetles

Reproduction can be costly and is predicted to trade-off against other characters. However, while these trade-offs are well documented for females, there has been less focus on aspects of male reproduction. Furthermore, those studies that have looked at males typically only investigate phenotypic associations, with the underlying genetics often ignored. Here, we report on phenotypic and genetic trade-offs in male reproductive effort in the seed beetle, Callosobruchus maculatus. We find that the duration of a male's first copulation is negatively associated with subsequent male survival, phenotypically and genetically. Our results are consistent with life-history theory and suggest that like females, males trade-off reproductive effort against longevity

Robust Metabolic Responses to Varied Carbon Sources in Natural and Laboratory Strains of Saccharomyces cerevisiae

Understanding factors that regulate the metabolism and growth of an organism is of fundamental biologic interest. This study compared the influence of two different carbon substrates, dextrose and galactose, on the metabolic and growth rates of the yeast Saccharomyces cerevisiae. Yeast metabolic and growth rates varied widely depending on the metabolic substrate supplied. The metabolic and growth rates of a yeast strain maintained under long-term laboratory conditions was compared to strain isolated from natural condition when grown on different substrates. Previous studies had determined that there are numerous genetic differences between these two strains. However, the overall metabolic and growth rates of a wild isolate of yeast was very similar to that of a strain that had been maintained under laboratory conditions for many decades. This indicates that, at in least this case, metabolism and growth appear to be well buffered against genetic differences. Metabolic rate and cell number did not co-vary in a simple linear manner. When grown in either dextrose or galactose, both strains showed a growth pattern in which the number of cells continued to increase well after the metabolic rate began a sharp decline. Previous studied have reported that O2 consumption in S. cerevisiae grown in reduced dextrose levels were elevated compared to higher levels. Low dextrose levels have been proposed to induce caloric restriction and increase life span in yeast. However, there was no evidence that reduced levels of dextrose increased metabolic rates, measured by either O2 consumption or CO2 production, in the strains used in this study