Relaxin family peptide systems and the central nervous system

Since its discovery in the 1920s, relaxin has enjoyed a reputation as a peptide hormone of pregnancy. However, relaxin and other relaxin family peptides are now associated with numerous non-reproductive physiologies and disease states. The new millennium bought with it the sequence of the human genome and subsequently new directions for relaxin research. In 2002, the ancestral relaxin gene RLN3 was identified from genome databases. The relaxin-3 peptide is highly expressed in a small region of the brain and in species from teleost to primates and has both conserved sequence and sites of expression. Combined with the discovery of the relaxin family peptide receptors, interest in the role of the relaxin family peptides in the central nervous system has been reignited. This review explores the relaxin family peptides that are expressed in or act upon the brain, the receptors that mediate their actions, and what is currently known of their functions.     

Number and condition of seeds in ponderosa pine cones in central Arizona

Ponderosa pine cones from 10 areas in Arizona were collected prior to natural seed dispersal and dissected to determine the number of sound, hollow, and insect-damaged seeds in each cone. Total and sound seed yields per cone did not vary significantly among areas but did vary significantly among trees within each area. Numbers of hollow and Megastigmus -infested (Hymenoptera: Torymidae) seeds varied significantly among areas and trees within areas. Numbers of sound seed increased significantly with increasing cone length but did not change with increasing numbers of cones per cluster. The percentages of Megastigmus -infested seed did not change significantly with increasing cone length or number of cones per cluster.     

Influence of precipitation and temperature on ring, annual branch increment, and needle growth of White Fir and Douglas-fir in central Utah

The study evaluates growth variations in mixed stands of Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) and White Fir ( Abies concolor Hoopes) from the Bighorn Ranch in northern Sanpete County, Utah. The study area lies 26 km southwest of Thistle, Utah. Tree-ring width, annual branch growth and needle length for the period 1970–1976 were obtained from Douglas-Fir and White Fir individuals distributed along an altitudinal and moisture gradient. Elevation ranged from 2257 m to 2500 m above sea level. Temperature and precipitation are shown to exert a significant influence on needle and annual branch growth and width of the annual rings. It was found that multiple correlation coefficients were always larger than the simple correlation coefficients. This suggests that the trees are responding to both temperature and precipitation. Annual branch growth is shown to be positively correlated with ring width and needle length. The influence of precipitation on growth is synchronized with 1 October–1 June precipitation. Best growth occurs in cool, moist years and at lower elevations.     

On Cowania and its intergeneric hybrids in Arizona

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Analysts’ Dynamic Decisions: Timeliness versus Accuracy

For analysts there is a tradeoff between the accuracy and the timeliness of their forecasts. Prior literature heavily investigates analyst forecast accuracy. Few papers investigate the importance of timeliness. To our best knowledge, there are no empirical papers to date to investigate the dynamic interplay between these key characteristics. We show that if analysts experience a period of high accuracy relative to their peers, they subsequently focus more on the timeliness of their forecasts in the subsequent period and thus issue their forecasts earlier than they did in the prior period. Copyright © 2016 John Wiley & Sons, Ltd.     

Horses damp the spring in their step.

The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle. Despite being apparently redundant for such a mechanism, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30-40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb.     

Stem cells find their niche.

The concept that stem cells are controlled by particular microenvironments known as 'niches' has been widely invoked. But niches have remained largely a theoretical construct because of the difficulty of identifying and manipulating individual stem cells and their surroundings. Technical advances now make it possible to characterize small zones that maintain and control stem cell activity in several organs, including gonads, skin and gut. These studies are beginning to unify our understanding of stem cell regulation at the cellular and molecular levels, and promise to advance efforts to use stem cells therapeutically.     

Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution.

Ion transport proteins must remove an ion's hydration shell to coordinate the ion selectively on the basis of its size and charge. To discover how the K+ channel solves this fundamental aspect of ion conduction, we solved the structure of the KcsA K+ channel in complex with a monoclonal Fab antibody fragment at 2.0 A resolution. Here we show how the K+ channel displaces water molecules around an ion at its extracellular entryway, and how it holds a K+ ion in a square antiprism of water molecules in a cavity near its intracellular entryway. Carbonyl oxygen atoms within the selectivity filter form a very similar square antiprism around each K+ binding site, as if to mimic the waters of hydration. The selectivity filter changes its ion coordination structure in low K+ solutions. This structural change is crucial to the operation of the selectivity filter in the cellular context, where the K+ ion concentration near the selectivity filter varies in response to channel gating.     

On Joseph Fourier: the man,the mathematician and the physicist

In 1793 Lord Macartney arrived in China as ambassador of King George III. The aims of his embassy were largely directed towards the enlargement of British trade with the far east, and especially with China. The embassy also had a diplomatic and cultural mission, to impress the Chinese with British achievements. They were to do so largely by distributing presents of British manufactures, chief among them being scientific instruments. The Chinese refused the embassy's requests, and clearly regarded the gifts of instruments as merely ingenious toys. This paper describes the role of instruments in the embassy, and contrasts British expectations with Chinese attitudes to scientific instruments. The embassy's failure is shown to reveal fundamental differences in British and Chinese eighteenth-century responses to science, and has wide cultural implications.