Actin rings in cytokinesis of apical cells in red algae

1996 ◽  
Vol 74 (6) ◽  
pp. 971-974 ◽  
Author(s):  
David J. Garbary ◽  
A. Rosa McDonald
Keyword(s):  
Cell Division ◽  
Red Algae ◽  
Ring Formation ◽  
Transverse Wall ◽  
Actin Ring ◽  
Dense Ring ◽  
Red Algal ◽  
First Time ◽  
Actin Rings ◽  
Peripheral Cytoplasm

Actin rings are demonstrated for the first time in florideophyte red algae in Audouinella botryocarpa (Acrochaetiales) and Tiffaniella snyderae and Griffithsia pacifica (Ceramiales). Rings formed a complete circle in the peripheral cytoplasm prior to the development of the septum by furrowing. In the uninucleate A. botryocarpa, ring formation precedes mitosis. In all species F-actin initially has a diffuse to longitudinal alignment throughout the cell. The actin realigns and then contracts to form a dense actin ring. Following cell division, aggregations of actin are maintained along the transverse wall in at least G. pacifica and A. botryocarpa, and a dense ring of actin was observed around a pit plug in T. snyderae. The occurrence of actin rings in cell division of members of the Acrochaetiales and Ceramiales is consistent with ultrastructural observations on red algal unicells and suggests that actin rings are part of the ancestral cytokinetic mechanism in red algae. Keywords: actin rings, cell division, cytokinesis, cytoskeleton, microfilaments, Rhodophyta.

scholarly journals Dephosphorylation of Iqg1 by Cdc14 regulates cytokinesis in budding yeast

2015 ◽  
Vol 26 (16) ◽  
pp. 2913-2926 ◽  
Author(s):  
Daniel P. Miller ◽  
Hana Hall ◽  
Ryan Chaparian ◽  
Madison Mara ◽  
Alison Mueller ◽  
...  
Keyword(s):  
Ring Formation ◽  
Cyclin Dependent Kinase ◽  
Filamentous Actin ◽  
Actin Ring ◽  
Ring Assembly ◽  
Cdk Phosphorylation ◽  
Necessary And Sufficient ◽  
Type Ii Myosin ◽  
Actin Rings

Cytokinesis separates cells by contraction of a ring composed of filamentous actin (F-actin) and type II myosin. Iqg1, an IQGAP family member, is an essential protein in Saccharomyces cerevisiae required for assembly and contraction of the actomyosin ring. Localization of F-actin to the ring occurs only after anaphase and is mediated by the calponin homology domain (CHD) of Iqg1, but the regulatory mechanisms that temporally restrict actin ring assembly are not well defined. We tested the hypothesis that dephosphorylation of four perfect cyclin-dependent kinase (Cdk) sites flanking the CHD promotes actin ring formation, using site-specific alanine mutants. Cells expressing the nonphosphorylatable iqg1-4A allele formed actin rings before anaphase and exhibited defects in myosin contraction and cytokinesis. The Cdc14 phosphatase is required for normal cytokinesis and acts on specific Cdk phosphorylation sites. Overexpression of Cdc14 resulted in premature actin ring assembly, whereas inhibition of Cdc14 function prevented actin ring formation. Cdc14 associated with Iqg1, dependent on several CHD-flanking Cdk sites, and efficiently dephosphorylated these sites in vitro. Of importance, the iqg1-4A mutant rescued the inability of cdc14-1 cells to form actin rings. Our data support a model in which dephosphorylation of Cdk sites around the Iqg1 CHD by Cdc14 is both necessary and sufficient to promote actin ring formation. Temporal control of actin ring assembly by Cdk and Cdc14 may help to ensure that cytokinesis onset occurs after nuclear division is complete.

An ultrastructural study of cell division in the coralline red alga Bossiella orbigniana

1993 ◽  
Vol 71 (3) ◽  
pp. 434-446 ◽  
Author(s):  
Sharon Broadwater ◽  
Joe Scott ◽  
Dawn Field ◽  
Bill Saunders ◽  
Jewel Thomas
Keyword(s):  
Cell Division ◽  
Red Algae ◽  
Polar Region ◽  
Algal Cell ◽  
Metaphase Plate ◽  
Red Alga ◽  
Nucleolar Material ◽  
Red Algal ◽  
Polar Gap ◽  
Rough Er

This investigation of Bossiella orbigniana (Decaisne) Silva ssp. orbigniana represents the first ultrastructural account of cell division in the order Corallinales. The mitotic process in this alga is differentiated from that of other red algae by a combination of characters. During prometaphase–metaphase the division poles contain unusual membrane arrangements including quantities of smooth-surfaced membranes and elongate extensions of perinuclear rough ER. At anaphase extensive remnants of nucleolar material attach to the chromosomes, trailing them to the poles. After telophase, the distal nucleus continues to move toward the apex resulting in much greater nuclear segregation than accomplished by anaphase alone. Cytokinesis is temporally displaced from mitosis and displaced distally from the metaphase plate. A reevaluation of ultrastructural patterns of red algal cell division suggests that there are two basic types of mitosis, the polar gap type and the polar fenestrations type to which B. orbigniana belongs. These two types are differentiated by a number of characters with the most important being the configuration of the prometaphase–metaphase polar region and spindle origin. Key words: Bossiella, cell division, Corallinales, mitosis, phylogeny, red algae.

A catalogue and bibliography of non-marine (freshwater and estuarine) Rhodophyta (red algae) of India

Phytotaxa ◽  
2018 ◽  
Vol 364 (1) ◽  
pp. 1 ◽  
Author(s):  
E. K. GANESAN ◽  
JOHN A. WEST ◽  
ORLANDO NECCHI JR.
Keyword(s):  
Red Algae ◽  
Molecular Data ◽  
Hot Water ◽  
Eastern Ghats ◽  
Red Algal ◽  
Algal Groups ◽  
Voucher Specimens ◽  
Nicobar Islands ◽  
Water Springs ◽  
First Time

An annotated bibliographic catalogue of Indian red algae (Rhodophyta) occurring in freshwater and estuarine habitats (moist terrestrial soils, ponds, streams, rivers, lakes, large inland brackish water lagoons and coastal estuaries), based on more than a century (1846 to 2017) of publications is presented in a single coherent work for the first time. There have been 81 taxonomic entities (species, varieties and doubtful records), distributed among 21 genera recorded for the vast Indian sub-continent. Species distribution among the 21 genera are as follows: Audouinella—12; Balliopsis—1; Batrachospermum—11; Bostrychia—7; Caloglossa—8; Catenella—3; Chroodactylon (including Asterocytis)—2; Chroothece—1; Compsopogon—8, Compsopogonopsis—1; Hildenbrandia—1; Kumanoa—7; Kyliniella—1; Lemanea—6; Nothocladus—1; Polysiphonia—1; Porphyridium—1; Sheathia—1; Sirodotia—4; Thorea—2; and Tuomeya—2. Of the seven currently recognized classes of Rhodophyta, no members of Bangiophyceae, Cyaniodiophyceae, or Rhodellophyceae are recorded from India. For each taxon, the following information is provided: (i) valid and currently accepted binomial (ii) synonyms as applicable to Indian records (iii) references with distribution in India and (iv) brief notes. Descriptions of new species based on Indian collections (holotypes) are indicated and some new combinations were made, when necessary. Several generic records (e.g., Balliopsis, Hildenbrandia, Kyliniella, Nothocladus and Tuomeya) and some species records (e.g. Batrachospermum longiarticulatum, Lemanea australis, L. catenata, L. fluviatilis, L. mamillosa, L. torulosa and Thorea hispida) warrant detailed confirmatory data based on reinvestigation of fresh collections for morphology, reproduction and particularly molecular data to confirm the presence in the country. Future collections, especially in the Indian Biodiversity Hotspots (Indo-Burma, Western and Eastern Ghats and Andaman & Nicobar Islands), may uncover the occurrence of genera such as Bangia, Cyanidium and Nemalionopsis known to be present in neighbouring countries of Pakistan, Nepal and Thailand. Geothermal (acidic) hot water springs in India may reveal the presence of extremophilic unicellular red algal genera like Cyanidium, Cyanidioschyzon and Galdieria of the Cyanidiophyceae. Two maps showing the political and biogeographic zones of India are included. The need to preserve holotype and duplicate/voucher specimens with GPS data of future collections of red algal groups in a centralized national facility is also highlighted.

Red algal diversity (Rhodophyta) from Peru based on molecular analysis

Phytotaxa ◽  
2020 ◽  
Vol 454 (1) ◽  
pp. 1-23
Author(s):  
MARTHA S. CALDERON ◽  
DANILO E. BUSTAMANTE ◽  
SUNG MIN BOO
Keyword(s):  
Dna Sequences ◽  
Red Algae ◽  
Morphological Analysis ◽  
Algal Diversity ◽  
Molecular Approaches ◽  
The Family ◽  
Red Algal ◽  
Marine Flora ◽  
First Time ◽  
Ongoing Project

In Peru, an ongoing project has been to document the marine macroalgal biodiversity using molecular approaches because, to date, the Peruvian marine flora has been mostly characterized on the basis of morphological observations. We herein report on red algae collected along the coast of Peru, including specimens collected at historically important collecting sites, in order to provide a better understanding of Peruvian red algal diversity. Using phylogenetic analysis of rbcL DNA sequences, we report for the first time the occurrence of Nothogenia chilensis, Porphyra mumfordii, and Schizymenia dubyi in Peru. Results from molecular and morphological analysis of topotype material show that Chondracanthus glomeratus (M.Howe) Guiry is conspecific with C. chamissoi (C.Agardh) Kützing. Both Rhodymenia howeana E.Y.Dawson and R. multidigitata E.Y.Dawson, Acleto & Foldvik are proposed to be later taxonomic synonyms of R. corallina (Bory) Greville. Future studies will reveal more diversity of red algae from Peru with special emphasis on members of the family Bangiaceae, Delesseriaceae, and Lithophyllaceae.

scholarly journals Estrogen Decreases Cytoskeletal Organization by Forming an ERα/SHP2/c-Src Complex in Osteoclasts to Protect against Ovariectomy-Induced Bone Loss in Mice

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 619
Author(s):  
Hyun-Jung Park ◽  
Malihatosadat Gholam-Zadeh ◽  
Sun-Young Yoon ◽  
Jae-Hee Suh ◽  
Hye-Seon Choi
Keyword(s):  
Bone Resorption ◽  
Bone Loss ◽  
Ring Formation ◽  
Tartrate Resistant Acid Phosphatase ◽  
Actin Ring ◽  
Collagen Crosslinks ◽  
Trap Staining ◽  
Src Activation

Loss of ovarian function is closely related to estrogen (E2) deficiency, which is responsible for increased osteoclast (OC) differentiation and activity. We aimed to investigate the action mechanism of E2 to decrease bone resorption in OCs to protect from ovariectomy (OVX)-induced bone loss in mice. In vivo, tartrate-resistant acid phosphatase (TRAP) staining in femur and serum carboxy-terminal collagen crosslinks-1 (CTX-1) were analyzed upon E2 injection after OVX in mice. In vitro, OCs were analyzed by TRAP staining, actin ring formation, carboxymethylation, determination of reactive oxygen species (ROS) level, and immunoprecipitation coupled with Western blot. In vivo and in vitro, E2 decreased OC size more dramatically than OC number and Methyl-piperidino-pyrazole hydrate dihydrochloride (MPPD), an estrogen receptor alpha (ERα) antagonist, augmented the OC size. ERα was found in plasma membranes and E2/ERα signaling affected receptor activator of nuclear factor κB ligand (RANKL)-induced actin ring formation by rapidly decreasing a proto-oncogene tyrosine-protein kinase, cellular sarcoma (c-Src) (Y416) phosphorylation in OCs. E2 exposure decreased physical interactions between NADPH oxidase 1 (NOX1) and the oxidized form of c-Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2), leading to higher levels of reduced SHP2. ERα formed a complex with the reduced form of SHP2 and c-Src to decrease c-Src activation upon E2 exposure, which blocked a signal for actin ring formation by decreased Vav guanine nucleotide exchange factor 3 (Vav3) (p–Y) and Ras-related C3 botulinum toxin substrate 1 (Rac1) (GTP) activation in OCs. E2/ERα signals consistently inhibited bone resorption in vitro. In conclusion, our study suggests that E2-binding to ERα forms a complex with SHP2/c-Src to attenuate c-Src activation that was induced upon RANKL stimulation in a non-genomic manner, resulting in an impaired actin ring formation and reducing bone resorption.

scholarly journals Shadowing the Actions of a Predator: Backlit Fluorescent Microscopy Reveals Synchronous Nonbinary Septation of Predatory Bdellovibrio inside Prey and Exit through Discrete Bdelloplast Pores

2010 ◽  
Vol 192 (24) ◽  
pp. 6329-6335 ◽  
Author(s):  
A. K. Fenton ◽  
M. Kanna ◽  
R. D. Woods ◽  
S.-I. Aizawa ◽  
R. E. Sockett
Keyword(s):  
Cell Division ◽  
Outer Membrane ◽  
Fluorescent Microscopy ◽  
Gram Negative Bacteria ◽  
Bacterial Cell Division ◽  
Prey Cell ◽  
Gram Negative ◽  
A Genome ◽  
Predatory Bacteria ◽  
First Time

ABSTRACT The Bdellovibrio are miniature “living antibiotic” predatory bacteria which invade, reseal, and digest other larger Gram-negative bacteria, including pathogens. Nutrients for the replication of Bdellovibrio bacteria come entirely from the digestion of the single invaded bacterium, now called a bdelloplast, which is bound by the original prey outer membrane. Bdellovibrio bacteria are efficient digesters of prey cells, yielding on average 4 to 6 progeny from digestion of a single prey cell of a genome size similar to that of the Bdellovibrio cell itself. The developmental intrabacterial cycle of Bdellovibrio is largely unknown and has never been visualized “live.” Using the latest motorized xy stage with a very defined z-axis control and engineered periplasmically fluorescent prey allows, for the first time, accurate return and visualization without prey bleaching of developing Bdellovibrio cells using solely the inner resources of a prey cell over several hours. We show that Bdellovibrio bacteria do not follow the familiar pattern of bacterial cell division by binary fission. Instead, they septate synchronously to produce both odd and even numbers of progeny, even when two separate Bdellovibrio cells have invaded and develop within a single prey bacterium, producing two different amounts of progeny. Evolution of this novel septation pattern, allowing odd progeny yields, allows optimal use of the finite prey cell resources to produce maximal replicated, predatory bacteria. When replication is complete, Bdellovibrio cells exit the exhausted prey and are seen leaving via discrete pores rather than by breakdown of the entire outer membrane of the prey.

MinD directly interacting with FtsZ at the H10 helix suggests a model for robust activation of MinC to destabilize FtsZ polymers

2017 ◽  
Vol 474 (18) ◽  
pp. 3189-3205 ◽  
Author(s):  
Ashoka Chary Taviti ◽  
Tushar Kant Beuria
Keyword(s):  
Cell Division ◽  
Single Point ◽  
Point Mutations ◽  
Direct Interaction ◽  
Ring Formation ◽  
Z Ring ◽  
Single Point Mutations ◽  
Biochemical Analyses ◽  
Ftsz Assembly ◽  
The Mind

Cell division in bacteria is a highly controlled and regulated process. FtsZ, a bacterial cytoskeletal protein, forms a ring-like structure known as the Z-ring and recruits more than a dozen other cell division proteins. The Min system oscillates between the poles and inhibits the Z-ring formation at the poles by perturbing FtsZ assembly. This leads to an increase in the FtsZ concentration at the mid-cell and helps in Z-ring positioning. MinC, the effector protein, interferes with Z-ring formation through two different mechanisms mediated by its two domains with the help of MinD. However, the mechanism by which MinD triggers MinC activity is not yet known. We showed that MinD directly interacts with FtsZ with an affinity stronger than the reported MinC–FtsZ interaction. We determined the MinD-binding site of FtsZ using computational, mutational and biochemical analyses. Our study showed that MinD binds to the H10 helix of FtsZ. Single-point mutations at the charged residues in the H10 helix resulted in a decrease in the FtsZ affinity towards MinD. Based on our findings, we propose a novel model for MinCD–FtsZ interaction, where MinD through its direct interaction with FtsZ would trigger MinC activity to inhibit FtsZ functions.

Sign in / Sign up

Export Citation Format

Share Document