Month: September 2022

LIGHT DURATION. "Opening and closure in several other species is regulated by changes in light intensity and, in some species with nocturnal opening, by an increase in relative humidity. A minimum duration of darkness and light are usually required for opening and closure, respectively, in flowers that open during the day. Both phytochrome and a blue light receptor seem involved in light perception." http://jxb.oxfordjournals.org/content/54/389/1801.full View in LinkedIn

ENERGY INTENSIVE. "A number of proteins have been linked with pulvinar heliotropism and nyctinasty. H+- ATPase activity increases turgor by H+ efflux and consequent K+ influx, and H+-ATPase inhibitors reduce diaheliotropic response in soybean pulvinus. Blue light is a deactivator of H+-ATPase in Phaseolus vulgaris motor cells which leads to decreased turgor pressure on the illuminated region rather than an activator of H+-ATPase on the opposite region." http://www.pagepress.org/journals/index.php/pb/article/view/4887/4390 View in LinkedIn

ELECTRICAL CUES. "Flowers are negatively charged, while flying insects are positively charged. This has been suggested to facilitate pollen transfer between insects and flowers. A recent paper in Science indicates that the electric fields of flowers also might be pollinator cues. It has not been studied yet how long the electric field lasts in relation to stigma receptivity and pollen availability. It also is not yet clear when the flowers attain the electric field, thus whether and how the field is related to flower opening or closure." https://lnkd.in/eTEzGE9 View in LinkedIn

TEMPERATURE DIFFERENTIAL. "In most of the species studied, petal movements are due to a difference in growth rate of the two sides. In species that open in the morning and mainly respond to temperature, for example, the inner surface of the petal rapidly grows in length when the temperature is raised, whereas the outer surface does not. Cooling results in a more rapid growth of the outer surface." http://jxb.oxfordjournals.org/content/54/389/1801.full View in LinkedIn

CELLULAR SUICIDE SCULPTING. "In Ipomoea (syn. Pharbitis), flower opening and closure are due to movements of the midrib rather than the petal lamina. Differences in cell expansion on both sides drive the movements. The difference in cell expansion was due, in part, to turgor loss in a group of inner epidermal cells of the midrib. For 2 d prior to anthesis, the ultrastructure of these cells underwent rapid changes that are indicative of cell death. Other cells of the rib did not show these changes." http://jxb.oxfordjournals.org/content/54/389/1801.full View in LinkedIn

WEATHER INFLUENCED. "Silene saxifraga flowers close during the day and open during the night for about 5 d. The petals roll up during the day. The inrolling (closing) movement was due to net water loss. Outrolling (opening) was apparently due to refilling of the cells with water. The flowers remain open longer on dry days if the soil is wet, and do not close at all on wet days." http://jxb.oxfordjournals.org/content/54/389/1801.full View in LinkedIn

SO ENDS this first weekend fragment from nature on flower opening and closing. Flowering plants have the most diverse, curious, imaginative and wonderful sexual organs of all species on earth. The numerous advantages of sexual reproduction include purging poorly adapted genes, and these plants have expanded from purely clonal vegetative reproduction to become dominant species on planet earth. View in LinkedIn

ORIGINS. "Genetic parasites, parasite replicators, mobile genetic elements, introns, viruses, and several other entities that are involved in competent genetic content arrangements and natural genome editing are known today. Where, how and when did they evolve?" https://lnkd.in/eg6uePF View in LinkedIn

VIRUS-FIRST VIEW. "For decades it has been assumed that viruses escaped from cellular organisms representing genetic parasites. There are several good arguments why viruses evolved before cellular agents." https://lnkd.in/eg6uePF View in LinkedIn

MORE ANCIENT. "Interestingly, phylogenetic analyses do not support the former concept of RNA- and DNA-viruses descending from cellular life. These analyses also show that DNA and RNA viruses most probably did not have a common ancestor but evolved independently. Viruses probably have to be placed at the very beginning of life, long before cellular life evolved." https://lnkd.in/euyhznh View in LinkedIn