Occurrence and phylogenetic significance of cytokinesis-related callose in green algae, bryophytes, ferns and seed plants

2001 ◽  
Vol 20 (2) ◽  
pp. 143-149 ◽  
Author(s):  
P. Scherp ◽  
R. Grotha ◽  
U. Kutschera
2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Siti Murdiyah ◽  
Pujiastuti Pujiastuti ◽  
Rino Tri Prasetyo

The area of Indonesia is 1.3% of the Earth, but it has the highest level of biodiversity. Biodiversity in the environment needs to be explored. The mountain area is one of the most suitable environments for exploring biodiversity, such as the Gumitir Mountain. Gumitir Mountain has altitude around 620 meters above sea level. Gumitir Mountain has high biodiversity. Mosses (Bryophyta), ferns (Pteridophyta), till seed plants (Spermatophyta), and including Lichen was found in this area. Lichen is a mutualism symbiotic organism between fungi and green algae or blue-green algae that lives on the surface of the tree or another substrate with a variety of shapes and colours. This study aims to determine the diversity of kinds and frequencies of each kind of lichen found in the Gumitir Mountain area of Jember Regency. This research classified into exploratory research. Data retrieval is using the cruised method. Lichens are found in 20 species with Phlyctis arena (Ach.) Flot. as kind of lichen that is abundant in Gumitir Mountain Area.


2021 ◽  
Vol 7 (5) ◽  
pp. eabe9487
Author(s):  
Emily M. Carlisle ◽  
Melina Jobbins ◽  
Vanisa Pankhania ◽  
John A. Cunningham ◽  
Philip C. J. Donoghue

The timing of origin of eukaryotes and the sequence of eukaryogenesis are poorly constrained because their fossil record is difficult to interpret. Claims of fossilized organelles have been discounted on the unsubstantiated perception that they decay too quickly for fossilization. We experimentally characterized the pattern and time scale of decay of nuclei, chloroplasts, and pyrenoids in red and green algae, demonstrating that they persist for many weeks postmortem as physical substrates available for preservation, a time scale consistent with known mechanisms of fossilization. Chloroplasts exhibit greater decay resistance than nuclei; pyrenoids are unlikely to be preserved, but their presence could be inferred from spaces within fossil chloroplasts. Our results are compatible with differential organelle preservation in seed plants. Claims of fossilized organelles in Proterozoic fossils can no longer be dismissed on grounds of plausibility, prompting reinterpretation of the early eukaryotic fossil record and the prospect of a fossil record of eukaryogenesis.


Author(s):  
L. V. Leak

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.


Author(s):  
A. E. Hotchkiss ◽  
A. T. Hotchkiss ◽  
R. P. Apkarian

Multicellular green algae may be an ancestral form of the vascular plants. These algae exhibit cell wall structure, chlorophyll pigmentation, and physiological processes similar to those of higher plants. The presence of a vascular system which provides water, minerals, and nutrients to remote tissues in higher plants was believed unnecessary for the algae. Among the green algae, the Chaetophorales are complex highly branched forms that might require some means of nutrient transport. The Chaetophorales do possess apical meristematic groups of cells that have growth orientations suggestive of stem and root positions. Branches of Chaetophora incressata were examined by the scanning electron microscope (SEM) for ultrastructural evidence of pro-vascular transport.


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