Skhodstvo i razlichiya lyuciferaz polihet Chaetopterus variopedatus v zavisimosti ot mesta ih obitaniya

Morskie polihety Chaetopterus variopedatus (Renier) (semejstvo Chaetopteridae) — kosmopolity, predstavlyayushchie soboj vidovoj kompleks iz otdel'nyh populyacij-podvidov. Pri razdrazhenii chervi vypuskayut svetyashchiesya (460 nm) oblaka slizi, pri etom chasto yarko svetyatsya i ih parapodii. Na segodnyashnij den' po-prezhnemu ne yasno, kak imenno rabotaet biolyuminescentnaya sistema etih polihet. Ranee bylo vydvinuto predpolozhenie, chto lyuciferaza C. variopedatus mozhet byt' ispol'zovana dlya detekcii ferroptoza — nedavno otkrytogo puti programmiruemoj kletochnoj gibeli, vyzvannoj nakopleniem ionov dvuhvalentnogo zheleza. Cel'yu issledovaniya bylo vydelit' i oharakterizovat' lyuciferazy C. variopedatus, a takzhe sravnit' lyuciferazy C. variopedatus iz raznyh populyacij. Pri vydelenii otvetstvennogo za biolyuminescenciyu fermenta iz zamorozhennyh obrazcov brazil'skih C. variopedatus po usovershenstvovannoj metodike byli polucheny dve aktivnye lyuciferazy — L1 i L2. Predpolozhiv, chto odna iz ukazannyh lyuciferaz opredelyaet svechenie slizi, a drugaya — svechenie parapodij chervej, etu zhe metodiku primenili k razdel'nym obrazcam slizi i parapodij zhivyh dal'nevostochnyh C. variopedatus. Odnako ih sliz' okazalas' nesvetyashchejsya. Pokazano, chto funkciyu svecheniya parapodij polihet C. variopedatus obespechivaet lyuciferaza L2, tak kak ona obnaruzhena v obshchej biomasse brazil'skih polihet i v parapodiyah dal'nevostochnyh polihet. Svechenie slizi brazil'skih C. variopedatus obuslovleno funkcionirovaniem lyuciferazy L1, kotoraya otsutstvuet v slizi dal'nevostochnogo podvida. Nabor izoform lyuciferaz polihet C. variopedatus zavisit ot mesta ih obitaniya.

Similarities and differences between the Chaetopterus variopedatus polychaete luciferases depending on the type of habitat

The marine polychaete Chaetopterus variopedatus (Renier) (family Chaetopteridae) is a cosmopolitan species complex, consisting of distinct populations/ subspecies. The worms release glowing (460 nm) clouds of mucus when disturbed, and their parapodia often glow brightly. Currently, it is still unclear how exactly the bioluminescence system of these polychaetes functions. It has been previously assumed that the C. variopedatus luciferase may be used for detection of ferroptosis, the recently explored pathway of programmed cell death, resulting from accumulation of the ferrous ions. This study was aimed to extract and characterize the C. variopedatus luciferases, as well as to compare luciferases obtained from C. variopedatus of different populations. When extracting the enzyme responsible for bioluminescence from the frozen samples of Brazilian C. variopedatus using the improved method, two active luciferases, L1 and L2, were obtained. We assumed that one of the listed above luciferases was responsible for luminescence of the mucus and the other luciferase was responsible for luminescence in parapodia, and used the method for the distinct samples of mucus and parapodia of the living Far Eastern C. variopedatus. However, mucus of the latter turned out to be non-glowing. It is shown that luciferase L2 is responsible for luminescence in the parapodia of the C. variopedatus polychaete, since this luciferase has been found in the total biomass of Brazilian polychaetes and parapodia of Far Eastern polychaetes. Luminescence of the Brazilian C. variopedatus mucus is attributed to the functioning of luciferase L1, which is lacking in the mucus of the Far Eastern subspecies. The range of luciferase isoforms in polychaetes C. variopedatus depends on the place of origin.

Myogenesis of Siboglinum fiordicum sheds light on body regionalisation in beard worms (Siboglinidae, Annelida)

Background Many annelids, including well-studied species such as Platynereis, show similar structured segments along their body axis (homonomous segmentation). However, numerous annelid species diverge from this pattern and exhibit specialised segments or body regions (heteronomous segmentation). Recent phylogenomic studies and paleontological findings suggest that a heteronomous body architecture may represent an ancestral condition in Annelida. To better understand the segmentation within heteronomous species we describe the myogenesis and mesodermal delineation of segments in Siboglinum fiordicum during development. Results Employing confocal and transmission electron microscopy we show that the somatic longitudinal musculature consists of four separate strands, among which ventrolateral one is the most prominent and is proposed to drive the search movements of the head of the late metatrochophore. The somatic circular musculature lies inside the longitudinal musculature and is predominantly developed at the anterior end of the competent larva to support the burrowing behaviour. Our application of transmission electron microscopy allows us to describe the developmental order of the non-muscular septa. The first septum to form is supported by thick bundles of longitudinal muscles and separates the body into an anterior and a posterior region. The second group of septa to develop further divides the posterior body region (opisthosoma) and is supported by developing circular muscles. At the late larval stage, a septum reinforced by circular muscles divides the anterior body region into a forepart and a trunk segment. The remaining septa and their circular muscles form one by one at the very posterior end of the opisthosoma. Conclusions The heteronomous Siboglinum lacks the strict anterior to posterior sequence of segment formation as it is found in the most studied annelid species. Instead, the first septum divides the body into two body regions before segments are laid down in first the posterior opisthosoma and then in the anterior body, respectively. Similar patterns of segment formation are described for the heteronomous chaetopterid Chaetopterus variopedatus and serpulid Hydroides elegans and may represent an adaptation of these annelids to the settlement and transition to the sedentarian-tubiculous mode of life.

Myogenesis of Siboglinum Fiordicum Sheds Light on Body Regionalisation in Beard Worms (Siboglinidae, Annelida)

BackgroundMany annelids, including well-studied species such as Platynereis, show similar structured segments along their body axis (homonomous segmentation). However, numerous annelid species diverge from this pattern and exhibit specialised segments or body regions (heteronomous segmentation). Recent phylogenomic studies and paleontological findings suggest that a heteronomous body architecture may represent an ancestral condition in Annelida. To better understand the segmentation within heteronomous species we describe the myogenesis and mesodermal delineation of segments in Siboglinum fiordicum during development. ResultsEmploying confocal and transmission electron microscopy we show that the somatic circular musculature lies inside the longitudinal musculature and is predominantly developed at the anterior end of the larva. The longitudinal musculature consists of four separate strands at the ventral, dorsal, and ventrolateral body sides. Posteriorly, the longitudinal strands form a continuous layer. Our application of transmission electron microscopy allows us to describe the developmental order of the non-muscular septa. The first septum to form is supported by thick bundles of longitudinal muscles and separates the body into an anterior and a posterior region. The second group of septa to develop further divides the posterior body region (opisthosoma) and is supported by developing circular muscles. At the late larval stage, a septum reinforced by circular muscles divides the anterior body region into a forepart and a trunk segment. The remaining septa and their circular muscles form one by one at the very posterior end of the opisthosoma. Functionally, the prominent ventrolateral longitudinal muscles in the larva are proposed to drive the search movements of the head, while the anterior circular muscles and the posterior continuous layers of longitudinal muscles support the burrowing behaviour of the larva.ConclusionsThe heteronomous Siboglinum lacks the strict anterior to posterior sequence of segment formation as it is found in the most studied annelid species. Instead, the first septum divides the body into two body regions, before segments are layed down in first the posterior opisthosoma and then in the anterior body, respectively. Similar pattern of segment formation is described for the heteronomous chaetopterid Chaetopterus variopedatus and may represent an ancestral segmentation process in Annelida.

The potential of using the bioluminescent system of Chaetopterus variopedatus to study ferroptosis in living organisms

Ferroptosis is a form of programmed cell death associated with iron-dependent lipid peroxidation. Novel ferroptosis inducers and suppressors could be instrumental in developing drugs against neurodegenerative disorders and cancer. Prior to embarking on a search for ferroptosis inducers/suppressors, this form of cell death must be studied in living cells and laboratory animals. In addition to two cofactors, luciferase (or photoprotein) of the parchment tubeworm Chaetopterus variopedatus requires the presence of iron ions and hydrogen peroxide or organic hydroperoxides to exert its activity. Therefore, the bioluminescence system of the parchment tubeworm can be used to study ferroptosis in living organisms.

Perspektivy ispol'zovaniya biolyuminescentnoj sistemy Chaetopterus variopedatus dlya monitoringa ferroptoza v zhivyh organizmah

Ferroptoz — osobyj tip programmiruemoj gibeli kletok, svyazannyj s intensivnym okisleniem lipidov pod dejstviem svobodnyh ionov dvuhvalentnogo zheleza. Novye induktory i supressory ferroptoza mogut stat' osnovoj dlya sozdaniya preparatov dlya lecheniya nejrodegenerativnyh i onkologicheskih zabolevanij. Dlya poiska takih induktorov (supressorov) ferroptoza neobhodimo detektirovat' etot process v zhivyh kletkah ili u laboratornyh zhivotnyh. Lyuciferaza (fotoprotein) morskogo drakona Chaetopterus variopedatus dlya svoej aktivnosti trebuet pomimo dvuh kofaktorov nalichiya ionov zheleza i peroksida vodoroda (libo organicheskih gidroperoksidov). Sootvetstvenno biolyuminescentnaya sistema morskogo drakona mozhet byt' ispol'zovana dlya monitoringa ferroptoza v zhivyh organizmah.

Hidden in plain sight, Chaetopterus dewysee sp. nov. (Chaetopteridae, Annelida) – A new species from Southern California

We describe a long-unnamed Chaetopterus Cuvier, 1830 species from southern California, using a combination of DNA barcoding and detailed morphological investigation employing high-resolution X-ray microtomography (micro-CT). Chaetopterus dewysee sp. nov. is not only one of the most dominant annelids in the benthic communities of the shallow end of the La Jolla submarine canyon, but also a well-established model for studying bioluminescence and has a published transcriptome. The description and naming of this southern Californian Chaetopterus is a step towards the much-needed revision of the group’s taxonomy and towards resolving the confusion over the ʻcosmopolitanʼ Chaetopterus variopedatus species complex. Micro-CT data showing details of both internal and external anatomy has been made freely available as the first annelid cybertype.

Worm tubes as conduits for the electrogenic microbial grid in marine sediments

Electrogenic cable bacteria can couple spatially separated redox reaction zones in marine sediments using multicellular filaments as electron conductors. Reported as generally absent from disturbed sediments, we have found subsurface cable aggregations associated with tubes of the parchment worm Chaetopterus variopedatus in otherwise intensely bioturbated deposits. Cable bacteria tap into tubes, which act as oxygenated conduits, creating a three-dimensional conducting network extending decimeters into sulfidic deposits. By elevating pH, promoting Mn, Fe-oxide precipitation in tube linings, and depleting S around tubes, they enhance tube preservation and favorable biogeochemical conditions within the tube. The presence of disseminated filaments a few cells in length away from oxygenated interfaces and the reported ability of cable bacteria to use a range of redox reaction couples suggest that these microbes are ubiquitous facultative opportunists and that long filaments are an end-member morphological adaptation to relatively stable redox domains.