Spider Man Data Chain
Granville Turley
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Formation of spider silk from its constituent proteins-spidroins-involves changes from soluble helical/coil conformations to insoluble β-sheet aggregates. This conversion needs to be regulated to avoid precocious aggregation proximally in the silk gland while still allowing rapid silk assembly in the distal parts. Lowering of pH from about 7 to 6 is apparently important for silk formation. The spidroin N-terminal domain (NT) undergoes stable dimerization and structural changes in this pH region, but the underlying mechanisms are incompletely understood. Here, we determine the NMR and crystal structures of Euprosthenops australis NT mutated in the dimer interface (A72R). Also, the NMR structure of wild-type (wt) E. australis NT at pH7.2 and 300 mM sodium chloride was determined. The wt NT and A72R structures are monomers and virtually identical, but they differ from the subunit structure of dimeric wt NT mainly by having a tryptophan (W10) buried between helix 1 and helix 3, while W10 is surface exposed in the dimer. Wedging of the W10 side chain in monomeric NT tilts helix 3 approximately 5-6 into a position that is incompatible with that of the observed dimer structure. The structural differences between monomeric and dimeric NT domains explain the tryptophan fluorescence patterns of NT at pH7 and pH6 and indicate that the biological function of NT depends on conversion between the two conformations.
Phospholipases D (PLDs), the major dermonecrotic factors from brown spider venoms, trigger a range of biological reactions both in vitro and in vivo. Despite their clinical relevance in loxoscelism, structural data is restricted to the apo-form of these enzymes, which has been instrumental in understanding the functional differences between the class I and II spider PLDs. The crystal structures of the native class II PLD from Loxosceles intermedia complexed with myo-inositol 1-phosphate and the inactive mutant H12A complexed with fatty acids indicate the existence of a strong ligand-dependent conformation change of the highly conserved aromatic residues, Tyr 223 and Trp225 indicating their roles in substrate binding. These results provided insights into the structural determinants for substrate recognition and binding by class II PLDs.
RCSB PDB Core Operations are funded by the U.S. National Science Foundation (DBI-2321666), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM133198.
In old field systems, the common woodlouse may have an indirect effect on a nursery web spider. Woodlice and nursery web spiders feed in different food chains, yet previous work demonstrated that the presence of woodlice is correlated with higher predation success by nursery web spiders upon their grasshopper prey. This finding suggested a new hypothesis which links two seemingly disparate food chains: when woodlice are present, the spider predator or the grasshopper prey changes their location in the vegetative canopy in a way that increases their spatial overlap and therefore predation rate. However, warming temperatures may complicate this phenomenon. The spider cannot tolerate thermal stress, meaning warming temperatures may cause the spider to move downwards in the vegetative canopy or otherwise alter its response to woodlice. Therefore, we would expect warming and woodlice presence to have an interactive effect on predation rate.
Habitat domain observations revealed that spiders shift upward in the canopy when woodlice are present, but the corresponding effect on grasshopper prey survival was variable over the different years of study. Under warming conditions, spiders remained lower in the canopy regardless of the presence of woodlice, suggesting that thermal stress is more important than the effect of woodlice. Our modelling results suggest that spiders do not need to move away from woodlice to maximize net energy gain (expected net energy gain and signal detection theory models). Instead spider behavior is consistent with the null hypothesis that they move away from unsuccessful encounters with woodlice (individual-based simulation). We conclude that mapping how predator behavior changes across biotic (e.g. woodlouse presence) and abiotic conditions (e.g. temperature) may be critical to anticipate changes in ecosystem dynamics.
We would like to thank the many interns who helped collect behavioral data and the Yale School Forests for providing the facilities necessary to conduct our research. We thank Oswald Schmitz and Max Lambert for providing invaluable feedback as we designed our experiments and analysis.
Nathalie R. Sommer and Robert W. Buchkowski conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the paper, and approved the final draft.
The work was funded by the Schiff Fund and the Yale School of Forestry & Environmental Studies. We received in kind contributions from the Yale School Forests. Robert Buchkowski was supported by the Natural Sciences and Engineering Research Council of Canada (PGSD3-454293-2014). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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Our studies led by University of Primorska, Slovenia show on the below video significant differences when using Oval chainrings compared to round. Up to 9% increase of Force effectiveness, up to 7% less oxygen consumption, up to 15% less Ventilation (breathing) and up to 10% heart rate decrease when using oval chainrings versus round. What that means? In short, You will consume less energy at the same power output using oval chainrings so you can ride for longer and/or faster. Our data show that the higher you climb themore effort you have to put in, therefore it's important to maximize efficiency and effectiveness and you can improve both of them by using oval chainrings. Watch the video.
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The researchers collected long-jawed spiders along two tributaries to Lake Superior, and they sampled sediments, dragonfly larvae and yellow perch fish from these waterways. Next, the team measured and identified the mercury sources, including direct industrial contamination, precipitation and runoff from soil. The team observed that the origin of mercury in the sediments was the same up the aquatic food chain in wetlands, reservoir shorelines and urban shorelines. For instance, when sediment contained a higher proportion of industrial mercury, so did the dragonfly larvae, spider and yellow perch tissues that were collected. Based on the data, the researchers say that long-jawed spiders could indicate how mercury pollution moves from aquatic environments to terrestrial wildlife. The implication of these findings is that spiders living next to the water provide clues to the sources of mercury contamination in the environment, informing management decisions and providing a new tool for monitoring of remediation activities, explain the researchers.
Worldwide Cyclery has worked with Neko Mulally this past year with his Frameworks project where he sets out to design and race his own downhill bike at the highest level, he is experimenting with different suspension types and system. One of those is the O-Chain spider, a crank spider designed to give you a chainless feeling on the bike. After a season of racing and testing Neko has been kind enough to share his thoughts on the O-Chain and how it helped him achieve the perfect setup this past season. - Worldwide Cyclery
O-Chain devices are becoming increasingly common on World Cup downhill and EWS race bikes. Nearly half of the field in any given World Cup DH final are using O-Chain devices. So, what do they do and how do they work?
O-Chain uses a dual spring system allowing the spider to rotate up to 12 degrees. The first spring is a small coil spring that takes the O-chain through its stroke and returns it to the starting position. The second spring is an elastomer bushing responsible for absorbing the bottom out as the pedal stroke is engaged. Technically, the elastomer bushing is a spring because it deforms as it is compressed, but it does not add to the stroke or the rotation of the device, it just softens the bottom out. Without that, there would be a harsh metal on metal bottom out as the pedal stroke is engaged. The size of the elastomer bushing is adjustable on the current O-Chain design to allow for different degrees of rotation, or amount of travel, at 4, 6, 9 and 12 degrees.
The topic of pedal kickback brings a lot of debate. Pedal kickback occurs when the upper chainline pulls backwards on the chainring as the rear suspension system is compressed. This is obvious to see if you remove the spring from your bike and compress the suspension; the crank arm will rotate backwards. Using a standard chainring, with your foot firmly applying pressure to the pedal as you stand on your bike, the chain pulls the cassette forward until the free hub is engaged and chainring backward, creating chain tension that resists the suspension system from moving freely through its travel.
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