Circadian rhythmicity of nectar secretion in Hoya carnosa

Abstract

Matile Ph. 2006. Circadian rhythmicity of nectar secretion in Hoya carnosa. Bot. Helv. 116: 1-7.A simple device for continuous sampling of nectar secreted in single flowers of Hoya carnosa R. Br. (Asclepiadaceae) is described. Sampling at 3 hrs intervals over several days revealed an oscillating secretion with maxima around midnight. Plants were transferred from a 12:12 hrs photoperiod to continuous illumination in order to distinguish between diurnal and circadian regulation. Under conditions of continuous illumination oscillations prevailed for two cycles and the free running period was about 29 hrs. Upon transfer to an inverted photoperiod, oscillations were immediately resumed and the maxima were entrained as to fall into the dark period. It is concluded that the rhythmicity of nectar secretion in H. carnosa is a manifestation of the biological clock.

Chlorophyll Breakdown in Senescent Banana Leaves: Catabolism Reprogrammed for Biosynthesis of Persistent Blue Fluorescent Tetrapyrroles

“…In a broader sense, the fascinating colors that appear in fall leaves and in ripening fruit, due to the degradation of chlorophyll, stimulate further considerations with respect to the biological49 and ecological50, 51 relevance of such color changes. In a few exceptional cases, degreening leaves are, indeed, known to develop strong luminescence, one example being the fall leaves of Ginkgo biloba 52. The luminescence of the senescent leaves of this tree is mainly caused by an unsaturated alkaloid 52…”

“…In a few exceptional cases, degreening leaves are, indeed, known to develop strong luminescence, one example being the fall leaves of Ginkgo biloba 52. The luminescence of the senescent leaves of this tree is mainly caused by an unsaturated alkaloid 52…”

Neurogenomic signatures of spatiotemporal memories in time-trained forager honey bees

“…This is adaptive because different species of flowering plants bloom at different times of day (Linnaeus, 1751), and nectar and pollen are available for pollinators only during discrete, but consistent, windows of time (Gimenes et al, 1993;Doorn and Meeteren, 2003;Matile, 2006). Honey bees can learn not only where to fly to collect food, but also when to do so (Beling, 1929;Wahl, 1932).…”

Hypermodified Fluorescent Chlorophyll Catabolites: Source of Blue Luminescence in Senescent Leaves

“…[30] However, strongly luminescent senescent leaves are known in only a few plants, one of which is Ginkgo biloba. [31] Luminescence of its leaves is due to an unsaturated alkaloid. [31] Bright colors of fruit are believed to have evolved as valuable signals to attract frugivores, needed for seed dispersal.…”

“…[31] Luminescence of its leaves is due to an unsaturated alkaloid. [31] Bright colors of fruit are believed to have evolved as valuable signals to attract frugivores, needed for seed dispersal. [32,33] Indeed, the blue luminescence of ripe bananas may fulfill such a role.…”