Resolving a 200-year-old taxonomic conundrum: neotype designation for Cephalothrix linearis (Nemertea: Palaeonemertea) based on a topotype from Bergen, Norway

Some nemertean species from the genus Cephalothrix accumulate tetrodotoxin (TTX) in extremely high concentrations. The current study is the first to provide high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) data on tetrodotoxin and its analogues (TTXs) profile and concentration in different regions and organs of Cephalothrix cf. simula, and its secretions produced in response to stimulation. Different specimens of C. cf. simula possessed 7–11 analogues, including nine previously found in this species and two new for nemerteans—4,9-anhydro-8-epi-5,6,11-trideoxyTTX and 1-hydroxy-8-epi-5,6,11-trideoxyTTX. The study of the toxins’ distribution in different regions and organs of nemerteans revealed the same qualitative composition of TTXs throughout the body but differences in the total concentration of the toxins. The total concentration of TTXs was highest in the anterior region of the body and decreased towards the posterior; the ratio of the analogues also differed between regions. The data obtained suggest a pathway of TTXs uptake in C. cf. simula and the role of toxins in the life activity of nemerteans.

“…In the current work, C. cf. simula, belonging to the group of species Cephalothrix simula s. l, was investigated [15]. The concentration of TTXs in nemerteans varied from 133.3 (No.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Tetrodotoxin and Its Analogues in Cephalothrix cf. simula (Nemertea: Palaeonemertea) from the Sea of Japan (Peter the Great Gulf): Intrabody Distribution and Secretions

Vlasenko

Magarlamov

2020

“…Taxonomical studies of C. simula have shown that this species comprises three networks [ 45 ] which are currently considered as independent cryptic species [ 1 , 7 , 46 ]. In the present study, the object was one of the cryptic species referred to as Cephalothrix cf.…”

Section: Methodsmentioning

confidence: 99%

Tetrodotoxin and Its Analogues (TTXs) in the Food-Capture and Defense Organs of the Palaeonemertean Cephalothrix cf. simula

Malykin,

Velansky,

Magarlamov

2024

Tetrodotoxin (TTX), an extremely potent low-molecular-weight neurotoxin, is widespread among marine animals including ribbon worms (Nemertea). Previously, studies on the highly toxic palaeonemertean Cephalothrix cf. simula showed that toxin-positive structures are present all over its body and are mainly associated with glandular cells and epithelial tissues. The highest TTXs concentrations were detected in a total extract from the intestine of the anterior part of the body and also in a total extract from the proboscis. However, many questions as to the TTXs distribution in the organs of the anterior part of the worm’s body and the functions of the toxins in these organs are still unanswered. In the present report, we provide additional results of a detailed and comprehensive analysis of TTXs distribution in the nemertean’s proboscis, buccal cavity, and cephalic gland using an integrated approach including high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS), confocal laser scanning microscopy with anti-TTX antibodies, light and electron microscopies, and observations of feeding behavior. For the proboscis, we have found a ТТХs profile different from that characteristic of other organs and tissues. We have also shown for the first time that the major amount of TTXs is localized in the anterior part of the proboscis that is mainly involved in hunting. TTX-containing glandular cells, which can be involved in the prey immobilization, have been found in the buccal cavities of the nemerteans. A significant contribution of the cephalic gland to the toxicity of this animal has been shown for the first time, and the role of the gland is hypothesized to be involved not only in protection against potential enemies but also in immobilizing prey. The data obtained have made it possible to extend the understanding of the role and features of the use of TTXs in the organs of the anterior part of nemertean’s body.

“…Studies on intratissue distribution were fragmentary and focused on the foregut [ 16 , 17 ] and intestine only [ 18 ]. Later on, investigations focused mostly on the palaeonemertean cryptic species Cephalothrix simula [ 19 , 20 , 21 , 22 ] due to the extremely high toxicity of its representatives found in different areas [ 6 , 7 , 9 , 23 , 24 ], which sometimes reaches levels comparable to those recorded from pufferfishes and blue-ringed octopuses [ 25 ]. Recently, studies have been carried out that consider different aspects of C. simula toxicity, including the intratissue and intracellular distribution of TTXs; as a result, a contribution of TTXs to self-defense and food capture behavior is suggested [ 15 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

Tetrodotoxins in Tissues and Cells of Different Body Regions of Ribbon Worms Kulikovia alborostrata and K. manchenkoi from Spokoynaya Bay, Sea of Japan

Vlasenko,

Pereverzeva,

Velansky

et al. 2024

Nemerteans, or ribbon worms, possess tetrodotoxin and its analogues (TTXs), neurotoxins of bacterial origin, which they presumably use for capturing prey and self-defense. Most TTXs-containing nemertean species have low levels of these toxins and, therefore, have usually been neglected in studies of TTXs functions and accumulation. In the present study, Kulikovia alborostrata and K. manchenkoi, two closely related species, were analyzed for TTXs distribution in the body using the HPLC–MS/MS and fluorescence microscopy methods. The abundance of TTXs-positive cells was determined in the proboscis, integument, and digestive system epithelium. As a result, six TTXs-positive cell types were identified in each species; however, only four were common. Moreover, the proportions of the toxins in different body parts were estimated. According to the HPLC–MS/MS analysis, the TTXs concentrations in K. alborostrata varied from 0.91 ng/g in the proboscis to 5.52 ng/g in the precerebral region; in K. manchenkoi, the concentrations ranged from 7.47 ng/g in the proboscis to 72.32 ng/g in the posterior body region. The differences observed between the two nemerteans in the distribution of the TTXs were consistent with the differences in the localization of TTXs-positive cells. In addition, TTXs-positive glandular cell types were found in the intestine and characterized for the first time. TTXs in the new cell types were assumed to play a unique physiological role for nemerteans.