Month: September 2022

PERSISTENT VIRUSES. "Several capabilities of the eukaryotic nucleus show features common to large DNA viruses and cannot be found in any cellular organism, which may indicate that the symbiogenesis of eukaryotes additionally depended on a persistent virus as its nucleus and maybe even its nucleolus." http://onlinelibrary.wiley.com/doi/10.1111/nyas.12570/abstract View in LinkedIn

PLACENTAL NOVELTY. "If we were to investigate the evolutionary novelty of placental mammals, we would have to explain a rather complex genotype, the syncitin complex, by randomly derived replication errors. However, generation, integration, and regulation of the placenta are not a stepwise process, and missing links have not yet been found." https://lnkd.in/bpZMBAH View in LinkedIn

RADICAL CHANGES. "Today we know that it was a strong infection event with persistent viral settlers that transferred complete genetic blocks into single, or a very few infection events to host organisms that changed the phenotypic organism in a radical way without an infinite number of small steps." http://onlinelibrary.wiley.com/doi/10.1111/nyas.12570/abstract View in LinkedIn

FRAGMENT FROM NATURE focuses for the next two weekends on pine tree seasonal adaptations. I live among Mediterranean pine trees and observe a significant sequence of annual events: winter pine cone drops, spring -- yellow pollen coating everything, followed by enormous flower drops and two sets of old needle falls, along with the emergence of a new crop of cones in the crowns. The leaf whorl senescence is clearly hierarchical, dropping needles distally. A very busy creature. View in LinkedIn

SPECIALIZED LEAVES. "Needle-shaped leaves have a very low light absorptive surface area. Each needle, then, is not able to capture very much sunlight energy for photosynthesis. Needles also have a very thick, outer cuticle coating and special "pit-like" stomatae designed to prevent excessive water loss. Trees with needle-shaped leaves are especially well suited to site's that have drier soils and to climates in which the careful conservation of water is an important survival strategy." https://lnkd.in/evhFvqV View in LinkedIn

HIGHER PHOTOSYNTHESIS. "A study in Germany compared energy production in beech trees (which have broad, flat leaves) and Norway spruce trees (which have needles). It was found that the beech trees photosynthesize for 176 days in a year while the Norway spruce photosynthesize 260 days in a year! The bottom energy line was that with this increased time base for photosynthesis, the smaller leafed surface area of the Norway spruce was actually 58% more productive than the beech!" https://lnkd.in/evhFvqV View in LinkedIn

SEASONAL STRESSORS. "Throughout its growing range, this evergreen species is exposed to subfreezing temperatures that range from -10 to -30°C during the winter and high temperatures exceeding 30°C during the summer. These extremes are generally indicative of conditions leading to photo-oxidative stress, especially during periods of high irradiance and reduced CO2 fixation, when the primary sink for the removal of electrons from PSI is limited." (Eastern White Pine). https://lnkd.in/eqkRiKP View in LinkedIn

PHOTON EXCESS. "At subfreezing temperatures, net photosynthesis in white pine approaches zero, and photodynamic damage to the chloroplast can occur if energy from absorbed photons is not dissipated." https://lnkd.in/eqkRiKP View in LinkedIn

ENERGY DISSIPATION. "In order to maintain the photosynthetic energy balance, leaves have mechanisms to modulate the absorption of radiation and the capacity to harmlessly dissipate the energy absorbed in excess. In the short term, many plants species change the orientation of leaves and reposition chloroplasts inside the cells to minimize harmful quantities of light." https://lnkd.in/eYuQ_dT View in LinkedIn

ENDURING PINE NEEDLES. "Unlike deciduous plants, overwintering ever-green plants do not shed their leaves annually but retain them for several years. For example, in Scots pine from boreal and sub-boreal regions...eight-year-old needles can be found." View in LinkedIn