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Intrinsic constraints on sympodial growth morphologies of azooxanthellate scleractinian coral Dendrophyllia.

Sentoku A, Ezaki Y - PLoS ONE (2013)

Bottom Line: However, little is known about the intrinsic mechanisms that control asexual reproduction and the resultant morphologies of colonies.The strict constraints on budding regularities and shifts in budding sites observed in the sympodial growth forms of corals greatly affect resulting morphologies in azooxanthellate coral colonies.A precise understanding of these intrinsic constraints leads to a fundamental comprehension of colony-forming mechanisms in modular organisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Geosciences, Graduate School of Science, Osaka City University, Osaka, Japan. sentoku@sci.osaka-cu.ac.jp

ABSTRACT

Background: Asexual increase occurs in virtually all colonial organisms. However, little is known about the intrinsic mechanisms that control asexual reproduction and the resultant morphologies of colonies. Scleractinian corals, both symbiotic (zoaxanthellate) and non-symbiotic (azooxanthellate) corals are known to form elaborate colonies. To better understand the growth mechanisms that control species-specific type of colony in azooxanthellate dendrophyllid scleractinian corals, we have studied details of the budding pattern in the sympodial colonies of Dendrophyllia boschmai and Dendrophyllia cribrosa.

Principal findings: Budding exhibits the following regularities: (1) the two directive septa of offset corallites are oriented almost perpendicular to the growth direction of parent corallites; (2) offsets generally occur in either of the lateral primary septa that occur on one side of a corallite; the individuals thus show a definite polarity with respect to the directive septa, and only when branching dichotomously offsets occur in both primary septa; (3) the lateral corallites grow more-or-less diagonally upwards; and (4) the regularities and polarities are maintained throughout growth. Given these regularities, D. boschmai grows in a zigzag fashion by alternately budding on the right and left sites. In contrast, D. cribrosa grows helically by budding at a particular site.

Conclusions/significance: The strict constraints on budding regularities and shifts in budding sites observed in the sympodial growth forms of corals greatly affect resulting morphologies in azooxanthellate coral colonies. A precise understanding of these intrinsic constraints leads to a fundamental comprehension of colony-forming mechanisms in modular organisms.

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Schematic diagrams of the budding modes and the polarity (red bars, directive septa; green bars, the four lateral primary septa; red circles, budding site; white circles, polarity; arrows, growth direction; white lines, plane of bilateral symmetry).A–D, Dendrophyllia boschmai. E–H, Dendrophyllia cribrosa. A and E, Locations of budding sites and growth direction of individual corallites. x and y, dichotomous branching areas of a colony. B and F, Essential units of sympodial growth. C and G, Top views. D and H, Lateral views. Notably, given these regularities, D. boschmai grows in a zigzag fashion by budding at right and left sites alternatively, whereas D. cribrosa grows helically by budding at a particular site. In addition, D. cribrosa inevitably changes the direction of rotation in right and left branches after branching due to the presence of developmental constraints for maintaining polarity.
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pone-0063790-g008: Schematic diagrams of the budding modes and the polarity (red bars, directive septa; green bars, the four lateral primary septa; red circles, budding site; white circles, polarity; arrows, growth direction; white lines, plane of bilateral symmetry).A–D, Dendrophyllia boschmai. E–H, Dendrophyllia cribrosa. A and E, Locations of budding sites and growth direction of individual corallites. x and y, dichotomous branching areas of a colony. B and F, Essential units of sympodial growth. C and G, Top views. D and H, Lateral views. Notably, given these regularities, D. boschmai grows in a zigzag fashion by budding at right and left sites alternatively, whereas D. cribrosa grows helically by budding at a particular site. In addition, D. cribrosa inevitably changes the direction of rotation in right and left branches after branching due to the presence of developmental constraints for maintaining polarity.

Mentions: Figure 8 provides schematic views of the sympodial forms of Dendrophyllia boschmai and D. cribrosa. Four regularities are common to both species: (1) the directive septa of each corallite are oriented almost perpendicular to the growth directions of parent septa (Figs. 4A–D, H–J, 8B, F); (2) the lateral corallites never occur in the sectors of the two directive septa, but at specific primary septa on a particular side of the colony (Figs. 4E–F, J–L, 8A, E). Offsets occur in the two lateral primary septa only when branching dichotomously (Figs. 6A–B, E–F, 8A, E); (3) the individual budding corallites grow acute (diagonally upwards) at least in the beginning with respect to the growth direction of immediately preceding corallites (Fig. 8B, F); (4) irrespective of generation of budding, those regularities remain consistent during the growth of the entire colony (Fig. 8D, H).


Intrinsic constraints on sympodial growth morphologies of azooxanthellate scleractinian coral Dendrophyllia.

Sentoku A, Ezaki Y - PLoS ONE (2013)

Schematic diagrams of the budding modes and the polarity (red bars, directive septa; green bars, the four lateral primary septa; red circles, budding site; white circles, polarity; arrows, growth direction; white lines, plane of bilateral symmetry).A–D, Dendrophyllia boschmai. E–H, Dendrophyllia cribrosa. A and E, Locations of budding sites and growth direction of individual corallites. x and y, dichotomous branching areas of a colony. B and F, Essential units of sympodial growth. C and G, Top views. D and H, Lateral views. Notably, given these regularities, D. boschmai grows in a zigzag fashion by budding at right and left sites alternatively, whereas D. cribrosa grows helically by budding at a particular site. In addition, D. cribrosa inevitably changes the direction of rotation in right and left branches after branching due to the presence of developmental constraints for maintaining polarity.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646883&req=5

pone-0063790-g008: Schematic diagrams of the budding modes and the polarity (red bars, directive septa; green bars, the four lateral primary septa; red circles, budding site; white circles, polarity; arrows, growth direction; white lines, plane of bilateral symmetry).A–D, Dendrophyllia boschmai. E–H, Dendrophyllia cribrosa. A and E, Locations of budding sites and growth direction of individual corallites. x and y, dichotomous branching areas of a colony. B and F, Essential units of sympodial growth. C and G, Top views. D and H, Lateral views. Notably, given these regularities, D. boschmai grows in a zigzag fashion by budding at right and left sites alternatively, whereas D. cribrosa grows helically by budding at a particular site. In addition, D. cribrosa inevitably changes the direction of rotation in right and left branches after branching due to the presence of developmental constraints for maintaining polarity.
Mentions: Figure 8 provides schematic views of the sympodial forms of Dendrophyllia boschmai and D. cribrosa. Four regularities are common to both species: (1) the directive septa of each corallite are oriented almost perpendicular to the growth directions of parent septa (Figs. 4A–D, H–J, 8B, F); (2) the lateral corallites never occur in the sectors of the two directive septa, but at specific primary septa on a particular side of the colony (Figs. 4E–F, J–L, 8A, E). Offsets occur in the two lateral primary septa only when branching dichotomously (Figs. 6A–B, E–F, 8A, E); (3) the individual budding corallites grow acute (diagonally upwards) at least in the beginning with respect to the growth direction of immediately preceding corallites (Fig. 8B, F); (4) irrespective of generation of budding, those regularities remain consistent during the growth of the entire colony (Fig. 8D, H).

Bottom Line: However, little is known about the intrinsic mechanisms that control asexual reproduction and the resultant morphologies of colonies.The strict constraints on budding regularities and shifts in budding sites observed in the sympodial growth forms of corals greatly affect resulting morphologies in azooxanthellate coral colonies.A precise understanding of these intrinsic constraints leads to a fundamental comprehension of colony-forming mechanisms in modular organisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Geosciences, Graduate School of Science, Osaka City University, Osaka, Japan. sentoku@sci.osaka-cu.ac.jp

ABSTRACT

Background: Asexual increase occurs in virtually all colonial organisms. However, little is known about the intrinsic mechanisms that control asexual reproduction and the resultant morphologies of colonies. Scleractinian corals, both symbiotic (zoaxanthellate) and non-symbiotic (azooxanthellate) corals are known to form elaborate colonies. To better understand the growth mechanisms that control species-specific type of colony in azooxanthellate dendrophyllid scleractinian corals, we have studied details of the budding pattern in the sympodial colonies of Dendrophyllia boschmai and Dendrophyllia cribrosa.

Principal findings: Budding exhibits the following regularities: (1) the two directive septa of offset corallites are oriented almost perpendicular to the growth direction of parent corallites; (2) offsets generally occur in either of the lateral primary septa that occur on one side of a corallite; the individuals thus show a definite polarity with respect to the directive septa, and only when branching dichotomously offsets occur in both primary septa; (3) the lateral corallites grow more-or-less diagonally upwards; and (4) the regularities and polarities are maintained throughout growth. Given these regularities, D. boschmai grows in a zigzag fashion by alternately budding on the right and left sites. In contrast, D. cribrosa grows helically by budding at a particular site.

Conclusions/significance: The strict constraints on budding regularities and shifts in budding sites observed in the sympodial growth forms of corals greatly affect resulting morphologies in azooxanthellate coral colonies. A precise understanding of these intrinsic constraints leads to a fundamental comprehension of colony-forming mechanisms in modular organisms.

Show MeSH