scholarly journals Morphological Study and 3D Reconstruction of the Larva of the Ascidian Halocynthia roretzi

2021 ◽  
Vol 10 (1) ◽  
pp. 11
Author(s):  
Lucia Manni ◽  
Federico Caicci ◽  
Chiara Anselmi ◽  
Virginia Vanni ◽  
Silvia Mercurio ◽  
...  

The swimming larva represents the dispersal phase of ascidians, marine invertebrates belonging to tunicates. Due to its adhesive papillae, the larva searches the substrate, adheres to it, and undergoes metamorphosis, thereby becoming a sessile filter feeding animal. The larva anatomy has been described in detail in a few species, revealing a different degree of adult structure differentiation, called adultation. In the solitary ascidian Halocynthia roretzi, a species reared for commercial purposes, embryogenesis has been described in detail, but information on the larval anatomy is still lacking. Here, we describe it using a comparative approach, utilizing 3D reconstruction, as well as histological/TEM observations, with attention to its papillae. The larva is comparable to those of other solitary ascidians, such as Ciona intestinalis. However, it displays a higher level of adultation for the presence of the atrium, opened outside by means of the atrial siphon, and the peribranchial chambers. It does not reach the level of complexity of the larva of Botryllus schlosseri, a phylogenetically close colonial ascidian. Our study reveals that the papillae of H. roretzi, previously described as simple and conform, exhibit dynamic changes during settlement. This opens up new considerations on papillae morphology and evolution and deserves to be further investigated.

2017 ◽  
Vol 69 ◽  
pp. 60-74 ◽  
Author(s):  
Marie L. Nydam ◽  
Emily E. Stephenson ◽  
Claire E. Waldman ◽  
Anthony W. De Tomaso

2000 ◽  
Vol 49 (1-2) ◽  
pp. 84 ◽  
Author(s):  
A. Kenjo ◽  
M. Takahashi ◽  
M. Matsushita ◽  
Y. Endo ◽  
T. Fujita

2020 ◽  
Vol 8 (6) ◽  
pp. 396
Author(s):  
Francesca Cima ◽  
Roberta Varello

Dichlofluanid has long been employed as a fungicide in agriculture and has been massively introduced in antifouling paints for boat hulls over the last two decades. One of the most important toxic effects of antifoulants is represented by immunosuppression in marine invertebrates, which can be analysed in vitro with a number of short-term toxicity assays on haemocytes. Among bioindicators, the colonial ascidian Botryllus schlosseri is a useful candidate; it is a filter-feeding organism living in the water-sediment interface that is found worldwide and is sensitive to antifouling xenobiotics. Dichlofluanid adversely affects both immunocyte lines (phagocyte and cytotoxic lines) after exposure to sublethal concentrations. At 0.05 μM (16.65 μg/L), dichlofluanid induced haemocyte apoptosis and cell shrinkage with a decrease in both motility and phagocytosis. At the lowest concentration (0.01 μM, 3.33 μg/L), inhibition of pivotal enzymatic activities of phagocytes and cytotoxic cells occurred. At the highest concentration (0.1 μM, 33.3 μg/L), dichlofluanid increased glutathione oxidation, leading to stress conditions. The effects of dichlofluanid on immune defence responses are similar to those of organometal-based antifoulants (i.e., organotin compounds and zinc pyrithione), and its use in coastal areas requires attention.


1998 ◽  
Vol 35 (6-7) ◽  
pp. 363 ◽  
Author(s):  
X. Ji ◽  
K. Azumi ◽  
M. Nonaka ◽  
C. Namikawa-Yamada ◽  
M. Sasaki ◽  
...  

2002 ◽  
Vol 19 (3) ◽  
pp. 263-270 ◽  
Author(s):  
Makoto Arai ◽  
Miho Suzuki-Koike ◽  
Shin-Ichi Ohtake ◽  
Hiroyoshi Ohba ◽  
Kunio Tanaka ◽  
...  

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