Month: September 2022

LEAF VS FLOWER CLOCKS. "When grown outdoors, the flowers of C. arvensis open in the morning and close in the afternoon, for about 5 d prior to petal wilting. Temperature changes had no effect on opening or closure. Under continuous darkness, opening and closure showed a 24 h rhythm. When the leaves were subjected to a different day/night cycle from the flowers, the opening and closing rhythm followed that of the flowers." https://lnkd.in/eTEzGE9 View in LinkedIn

ENDOGENOUS CLOCKS. "The 24 h rhythm in continuous darkness also occurred in plants that had previously been subjected to a day/night cycle of 6 h rather than 12 h, in plants that had been held under continuous light, and in plants previously subjected to irregular periods of light and darkness. The flowers thus show a rhythm based on a clock that apparently resides in the flower, and which is unaffected by the light/dark regime prior to continuous darkness." https://lnkd.in/eTEzGE9 View in LinkedIn

DARK TRIGGER. "The time of the onset of darkness, however, had a large effect on the rhythm. In plants grown in the field and brought into 12 h darkness, starting at 12 noon, the flowers from then on showed a 24 rhythm whereby they followed the new cycle. Normally all flowers on a plant opened and closed at the same time. However, if buds on the same plant were placed in darkness at various times, they opened and closed at different times, set by the time of the onset of continuous darkness." https://lnkd.in/eTEzGE9 View in LinkedIn

RHYTHM FLIPS. "In light/dark (LD) cycles of 6 h or 9 h, flower opening followed the imposed cycle (i.e. they were 6 h open and 6 h closed, etc). Interestingly, if the light and dark periods were made as short as 2 h, the flowers again showed a 24 h rhythm. Within limits, therefore, the endogenous rhythm can become entrained by shorter light/dark cycling. Entrainment is defined as the process whereby the plant, exposed to repeated periods of light and darkness with a period P, changes its rhythm to the same period." https://lnkd.in/eTEzGE9 View in LinkedIn

RHYTHM SLIPS. "When plants of Cereus grandifolius (a night‐bloomer) were kept in darkness during the day and exposed to light at night, the normal periodicity was retained for some days but gradually became weaker, and then assumed a new phase in which opening occurred at the end of the light period." https://lnkd.in/eTEzGE9 View in LinkedIn

CLOCK GENES. "In Arabidopsis and other plants, several genes with a circadian expression pattern have been identified, for example, a catalase, cysteine protease, a putative β‐amylase, nitrate reductase, sucrose phosphate synthase, and chlorophyll a/b binding proteins (Cab) of photosystems I and II." https://lnkd.in/eTEzGE9 View in LinkedIn

OSCILLATING GENES. "Circadian factors affect hormone concentrations. For example, cytokinin, auxin, and ABA concentrations show diurnal patterns. TANDEMZINC KNUCKLE/PLU3 (TZP) affects diurnal growth patterns. Its gene expression oscillates, with a peak in the morning. TZP regulates the expression of auxin-related genes." https://lnkd.in/eTEzGE9 View in LinkedIn

SO ENDS this two week venture into the subject of flower opening and closing. Flowers arose in order to achieve fresh genetic recombination through sharing genes, by sexual reproduction. Perhaps the biggest driver in the natural world is the generation of ever better adapted genes, niche exploitation, and success of that species. Flowering plants have excelled at all three. View in LinkedIn

INFORMATION PROCESSING. "RNAs play complementary roles in information processing and regulation. In most cases they have an inheritable status, being integrated in the genome of organisms, and are termed endogenous. In other cases they are ancient individuals living in the cytoplasm of cells as persistent nonlytic parasites similar to DNA settlers, with important endosymbiotic roles." https://lnkd.in/euyhznh View in LinkedIn

RIBOZYME-LIKE FIRST CELLS. "Something like these capabilities of ribozymes had to have been components of the first cells. The metabolism of the first cells functioned without feeding. Photoautotrophic and chemoautotrophic organisms do not need to feed: they obtain their energy from sunlight or from hydrogen-rich compounds." https://lnkd.in/eDswHmC View in LinkedIn