Phytoplankton physiology is dynamic and highly responsive to the environment. Phytoplankton acclimate to changing environmental conditions by a complex reallocation of carbon and energy through metabolic pathways to optimize growth. Considering the tremendous diversity of phytoplankton, it is not surprising that different phytoplankton taxa use different strategies to partition carbon and energy resources. It has therefore been satisfying to discover that general principles of energetic stoichiometry appear to govern these complex processes and can be broadly applied to interpret phytoplankton distributions, productivity, and food web dynamics. The expectation of future changes in aquatic environments brought on by climate change warrants gathering knowledge about underlying patterns of photosynthetic energy allocation and their impacts on community structure and ecosystem productivity.

Acid and base environmental stress responses were investigated in Bacillus subtilis. B. subtilis AG174 cultures in buffered potassium-modified Luria broth were switched from pH 8.5 to pH 6.0 and recovered growth rapidly, whereas cultures switched from pH 6.0 to pH 8.5 showed a long lag time. Log-phase cultures at pH 6.0 survived 60 to 100% at pH 4.5, whereas cells grown at pH 7.0 survived <15%. Cells grown at pH 9.0 survived 40 to 100% at pH 10, whereas cells grown at pH 7.0 survived <5%. Thus, growth in a moderate acid or base induced adaptation to a more extreme acid or base, respectively. Expression indices from Affymetrix chip hybridization were obtained for 4,095 protein-encoding open reading frames of B. subtilis grown at external pH 6, pH 7, and pH 9. Growth at pH 6 upregulated acetoin production (alsDS), dehydrogenases (adhA, ald, fdhD, and gabD), and decarboxylases (psd and speA). Acid upregulated malate metabolism (maeN), metal export (czcDO and cadA), oxidative stress (catalase katA; OYE family namA), and the SigX extracytoplasmic stress regulon. Growth at pH 9 upregulated arginine catabolism (roc), which generates organic acids, glutamate synthase (gltAB), polyamine acetylation and transport (blt), the K ؉ /H ؉ antiporter (yhaTU), and cytochrome oxidoreductases (cyd, ctaACE, and qcrC). The SigH, SigL, and SigW regulons were upregulated at high pH. Overall, greater genetic adaptation was seen at pH 9 than at pH 6, which may explain the lag time required for growth shift to high pH. Low external pH favored dehydrogenases and decarboxylases that may consume acids and generate basic amines, whereas high external pH favored catabolism-generating acids.Bacillus subtilis can grow over several log units of environmental pH while maintaining cytoplasmic pH within a relatively narrow range that preserves protein and nucleic acid stability (19, 50, 55a). Environmental pH is important for the pathogenesis of related Bacillus species, such as the food-borne pathogen Bacillus cereus, which encounters acidic environments in the gastrointestinal tract and in food products where organic acids are used as preservatives (9, 64). B. cereus shows an acid tolerance response in which vegetative growth in a moderate acid induces proteins that enable survival under extreme acid conditions (64). In Bacillus anthracis, the lethal factor toxin undergoes a low-pH-driven structural change as it passes through acidic vesicles, which allows it to translocate into the cytosol (45). The Bacillus thuringiensis toxin is activated by alkaline pH upon entering the midgut of insect larvae (13), and bacterial growth is inhibited by acids (46).Cytoplasmic pH homeostasis has been studied extensively in B. subtilis, which maintains cytoplasmic pH within approximately pH 7.3 to pH 7.6 during vegetative growth over a range of environmental pH, from pH 6.0 to pH 9.0 (14, 50, 55a). At high external pH, cytoplasmic pH homeostasis involves Na ϩ /H ϩ antiporters as well as other Na ϩ transport components (14,26,50,67,68). Low pH triggers spore germi...

The purpose of this study was to determine the effect of different static and dynamic stretch protocols on 20-m sprint performance. The 97 male rugby union players were assigned randomly to 4 groups: passive static stretch (PSS; n = 28), active dynamic stretch (ADS; n = 22), active static stretch (ASST; n = 24), and static dynamic stretch (SDS; n = 23). All groups performed a standard 10-minute jog warm-up, followed by two 20-m sprints. The 20-m sprints were then repeated after subjects had performed different stretch protocols. The PSS and ASST groups had a significant increase in sprint time (p < or = 0.05), while the ADS group had a significant decrease in sprint time (p < or = 0.05). The decrease in sprint time, observed in the SDS group, was found to be nonsignificant (p > or = 0.05). The decrease in performance for the 2 static stretch groups was attributed to an increase in the musculotendinous unit (MTU) compliance, leading to a decrease in the MTU ability to store elastic energy in its eccentric phase. The reason why the ADS group improved performance is less clear, but could be linked to the rehearsal of specific movement patterns, which may help increase coordination of subsequent movement. It was concluded that static stretching as part of a warm-up may decrease short sprint performance, whereas active dynamic stretching seems to increase 20-m sprint performance.

Background: In Escherichia coli, pH regulates genes for amino-acid and sugar catabolism, electron transport, oxidative stress, periplasmic and envelope proteins. Many pH-dependent genes are co-regulated by anaerobiosis, but the overall intersection of pH stress and oxygen limitation has not been investigated.

Physical and mental health is known to have wide influence over most aspects of social life—be it schooling and employment or marriage and broader social engagement—but has received limited attention in explaining different forms of political participation. We analyze a unique dataset with a rich array of objective measures of cognitive and physical well-being and two objective measures of political participation, voting and contributing money to campaigns and parties. For voting, each aspect of health has a powerful effect on par with traditional predictors of participation such as education. In contrast, health has little to no effect on making campaign contributions. We recommend additional attention to the multifaceted affects of health on different forms of political participation.