Asexual reproduction and strobilation of Sanderia malayensis (Scyphozoa, Pelagiidae) in relation to temperature: experimental evidence and implications

Sanderia malayensis is a scyphozoan species present in the Indian and Pacific Oceans, ranging from the Suez Canal to Japan. Although this jellyfish is commonly kept in aquariums around the world, there is a knowledge gap regarding its biology and ecology, especially at the polyp stage. In this study, we tested the asexual reproductive activity of S.malayensis at Three different temperatures: 10, 15 and 20 \ub0C. Results showed significant increases of polyps at 15 \ub0C and 20 \ub0C, and a minimum at 10\ub0C, corresponding with daily budding rates of 6.61\ub1 0.92%, 5.85 \ub1 2.36% and 0.66\ub10.24%, respectively. Moreover, a second experiment was carried out to report about the ability of S. malayensis to prey on Aurelia solida at ephyra stage. Unidirectional predation of S. malayensis ephyrae on A. solida and an absence of inverse predation was observed. These results could give new insights on the potential fitness and survival of this species if it will ever invade the Mediterranean Sea

Determining Obelia spp. diversity and population dynamics in Thau lagoon (Northwestern Mediterranean Sea, France).

The jellyfish Obelia belongs to the family Campanulariidae (Hydrozoa, Leptomedusae), an important and widely distributed family of hydrozoans. Obelia is a very popular and widespread medusa, however first report on its complete life cycle was only published in the late nineties in Northern Japan. This is probably due to its size, as the medusa umbrella diameter is lower than 1mm. This Hydrozoa presents a bentho-pelagic life cycle with both polyp and medusa stages. In Thau lagoon, Northwestern Mediterranean Sea, populations of Obelia occur each year. Some polyps colonies were identified and sampled in the lagoon on Zostera noltii leaves, indicating that the populations realise their full development cycle within the lagoon. Morphological and genetical (COI) approaches, on both polyps and medusae, have revealed that main populations are composed by O. dichotoma individuals (side branches typically irregular in length; hydroteca bell-shaped, usually not very deep, thin walled, often thrown into fine longitudinal folds; hydrotecal rim with smooth or with shallow cusps \u2013crenate, slightly flared; diaphragm transverse to oblique) but that O. bidentata (lateral branches roughly in right angles pairs are given on both sides; slightly oblique diaphragm; hydrotecal rim with bimucronate cusps) is also present in lower abundances. An in situ pelagic monitoring every two weeks since 2008 have allowed understanding the populations dynamics of the genus and the environmental factors that seemed to be particularly appropriated for promoting optimum growth conditions. Baseline information regarding seasonal cycles and historical abundances were provided from a 8 years monitoring, which has allowed detecting blooms. Indeed, the medusae were found at very low densities during the study period with main abundances under 5 ind.m-3, in accordance to previous reports for Obelia spp. medusae around the world. Nevertheless, 2 exceptional events took place in June 2008 and May 2013 were blooms reached 1232 and 660 ind.m-3 respectively. Such data raise questions regarding the potential importance of this small and understudied hydrozoa in the pelagic community of Thau lagoon. Consequently, it is necessary to improve the available databases documenting medusae blooms, as this will provide baseline information about these little-studied events

Asexual Reproduction and Strobilation of Sanderia malayensis (Scyphozoa, Pelagiidae) in Relation to Temperature: Experimental Evidence and Implications

Sanderia malayensis is a scyphozoan species present in the Indian and Pacific Oceans, ranging from the Suez Canal to Japan. Although this jellyfish is commonly kept in aquariums around the world, there is a knowledge gap regarding its biology and ecology, especially at the polyp stage. In this study, we tested the asexual reproductive activity of S. malayensis at three different temperatures: 10, 15 and 20 °C. Results showed significant increases of polyps at 15 and 20 °C, and a minimum at 10 °C, corresponding with daily budding rates of 6.61% ± 0.92%, 5.85% ± 2.36% and 0.66% ± 0.24%, respectively. Moreover, a second experiment was carried out to report about the ability of S. malayensis to prey on Aurelia solida at the ephyra stage. Unidirectional predation of S. malayensis ephyrae on A. solida and an absence of inverse predation was observed. These results could give new insights on the potential fitness and survival of this species if it will ever invade the Mediterranean Sea

Inhibiting anterior insula changes interoceptive accuracy: a combined TMS-fMRI study

The insular cortex (IC) is involved in sensing and interpreting visceral signals, an ability called interoception, the lack of which is considered a transdiagnostic risk factor for psychopathology. It is still unknown whether it is possible to modulate insular activity to change interoception using noninvasive brain stimulation techniques. Transcranial magnetic stimulation, including theta-burst stimulation (TBS), has proven to be an effective method to non-invasively modulate cortical regions' activity, producing facilitatory (iTBS) or inhibitory (cTBS) effects. By combining TBS with fMRI, we hypothesized that iTBS and cTBS would affect IC activity and, consequently, interoception. Thirty-six participants (18 F; Mage: 23.78 ± 3.56 years) volunteered for this study. cTBS and iTBS, over the right anterior insula, and sham stimulation over vertex were administered in a counterbalanced order across participants. After each stimulation, participants performed the heartbeat counting task and were scanned while performing an explicit emotional judgment task. During this task, they saw disgusting (or, as control, neutral) images that have proven to consistently activate the insula. We found preliminary evidence indicating that cTBS is able to change bilateral anterior IC activation. Specifically, cTBS reduced the bilateral activation of the IC during disgusting blocks and reduced participants’ ability to accurately detect their heartbeats compared to sham. Given the growing use of TMS protocols in psychiatry, current results could be used to inform the conduction of clinical trials aimed at actively changing the IC activity, for example, in patients showing alterations in interoception (e.g., anxiety disorders) or increased disgust sensitivity (e.g., obsessive-compulsive disorders)

Interfering with the activity of the insular cortex to modulate interoceptive awareness: a combined TMS/fMRI study

Aims: Insular cortex (IC) is involved in sensing, interpreting and being aware of signals coming from the viscera, an ability called interoceptive awareness (IA), the lack of which is considered a transdiagnostic risk factor for psychopathology1. However, it is still unknown if and to what extent it is possible to modulate IC activity to eventually modify individuals’ IA by using noninvasive brain stimulation techniques. Transcranial magnetic stimulation, including theta-burst stimulation (TBS) protocols, has proven to be an effective method to non-invasively modulate a variety of cortical regions' activity, producing facilitatory (iTBS) or inhibitory (cTBS) effects. It has been recently demonstrated that cTBS delivered over a fronto-temporal region changes participants’ performance at the heartbeat counting task2, a measure of IA. However, it has not been tested yet if this is because TBS changes excitability of the IC. By combining TBS with fMRI, we hypothesized that iTBS and cTBS would affect IC activity and, consequently, interoceptive awareness. Materials and Methods: 22 healthy individuals (13 F/ 9 M; mean age: 23.86 ± 3.91 years) participated in this study. cTBS and iTBS, over the right anterior IC and a sham stimulation over a control brain region were administered in a counterbalanced order across participants. After each stimulation, participants performed an IA task and were scanned throughout a MRI 3T Siemens, while performing an explicit emotional judgment task. During this task, they saw disgusting or neutral images from the dataset DIRTI3 that has proven to consistently activate the insula. The task was composed by 20 blocks, and each block was composed by six images. After each block of images, participants reported on a 5-point Likert scale how much they felt disgusted. Results: We found preliminary evidence indicating that the two TBS sessions changed bilateral IC activation. In particular, the cTBS, reduced bilateral activation of the anterior IC when disgusting images were displayed. Discussion and Conclusions: Given the growing use of TMS protocols in psychiatry, current results could be used to inform the conduction of clinical trials aimed at facilitating or inhibiting the activity of the insular cortex (for example in patients showing impaired interoception) with the ultimate goal to harness scientific advances to select treatment options with the greatest likelihood of success. 1)Craig, A. D. (2009). How do you feel—now? The anterior insula and human awareness. Nature reviews neuroscience, 10(1), 59-70. 2)Pollatos, O., Herbert, B. M., Mai, S., & Kammer, T. (2016). Changes in interoceptive processes following brain stimulation. Philosophical Transactions of the Royal Society B: Biological Sciences, 371(1708) 3)Haberkamp, A., Glombiewski, J. A., Schmidt, F., & Barke, A. (2017). The DIsgust-RelaTed-Images (DIRTI) database: Validation of a novel standardized set of disgust pictures. Behaviour research and therapy, 89, 86-94

Neutral red stain diffusion into the gastrovascular system of an excised oral arm

The stain was released on the cutting plan (top). Internal wing on the left, the external ones on the right.Peer reviewe

A novel endocast technique providing a 3D quantitative analysis of the gastrovascular system in Rhizostoma pulmo: An unexpected through-gut in cnidaria

International audienceThe investigation of jellyfish gastrovascular systems mainly focused on stain injections and dissections, negatively affected by thickness and opacity of the mesoglea. Therefore, descriptions are incomplete and data about tridimensional structures are scarce. In this work, morphological and functional anatomy of the gastrovascular system of Rhizostoma pulmo (Macri 1778) was investigated in detail with innovative techniques: resin endocasts and 3D X-ray computed microtomography. The gastrovascular system consists of a series of branching canals ending with numerous openings within the frilled margins of the oral arms. Canals presented a peculiar double hemi-canal structure with a medial adhesion area which separates centrifugal and centripetal flows. The inward flow involves only the “mouth” openings on the internal wing of the oral arm and relative hemi-canals, while the outward flow involves only the two outermost wings’ hemi-canals and relative “anal” openings on the external oral arm. The openings differentiation recalls the functional characteristics of a through-gut apparatus. We cannot define the gastrovascular system in Rhizostoma pulmo as a traditional through-gut, rather an example of adaptive convergence, that partially invalidates the paradigm of a single oral opening with both the uptake and excrete function

Early development of the manubrium canal system

(a) Young specimen of 2.7 cm diam., subumbrellar view. Arrow indicates the residual of the central mouth opening still open (scale bar = 0.25 cm). (b) As in (a), specimen 3 cm diam. (scale bar = 0.25 cm). (c) Subumbrellar view of a 4 cm diam. specimen, manubrium excised under the genital sinuses. Visible the four perradial canals projecting into the still wide central canal (scale bar = 0.25 cm). (d) Same view in a specimen of 5 cm diam., with the same pattern as in (c), but with a noticeable size reduction of the central quadrangular canal (scale bar = 0.25 cm). Black arrows in (c) and (d)indicate the edges of the perradial canals, white arrows indicate the central quadrangular canal.Peer reviewe

Micro CT-scan 3D rendering [longitudinal sections at central canal level]

360° animation of the whole endocast evidencing transverse sections of the umbrella, manubrium at supra-scapular and sub-scapular (at the distal portion of the central canal) level and finally longitudinal sections at central canal level.Peer reviewe

Micro CT-scan 3D rendering [oblique and longitudinal]

360° animation of the whole endocast evidencing oblique, longitudinal, and transverse sections of the manubrium at supra-scapular and sub-scapular (at the distal portion of the central canal) level.Peer reviewe