From two segments and beyond: Investigating the onset of regeneration in Syllis malaquini.

Annelids feature a diverse range of regenerative abilities, but complete whole-body regeneration is less common, particularly in the context of the head and anterior body regeneration. This study provides a detailed morphological description of Syllis malaquini regenerative abilities. By replicating previous experiments and performing diverse surgical procedures, we explored the capacity of this species for whole-body regeneration.

Sex-biased gene expression precedes sexual dimorphism in the agonadal annelid .

Gametogenesis is the process by which germ cells differentiate into mature sperm and oocytes, cells essential for sexual reproduction. The sex-specific molecular programs that drive spermatogenesis and oogenesis can also serve as sex identification markers. is a research organism that has been studied in many areas of developmental biology.

New species and record of Dodecaceria (Annelida: Cirratulidae) the Biological Reserve of Rocas Atoll, Brazil, the only atoll in the South Atlantic Ocean.

The polychaete Family Cirratulidae is one of the most abundant and diverse groups of Annelida, although it remains poorly known worldwide. Dodecaceria Ørsted, 1843 is one of the least described genera of Cirratulidae. The present report is the first taxonomic study of the genus Dodecaceria for the Brazilian coast.

Kirkegaardia Blake, 2016 (Annelida: Cirratulidae) from Southeastern Brazil with description of nine new species.

This is the first taxonomic study of cirratulid polychaetes of the genus Kirkegaardia Blake, 2016 from Brazil. Nine new species of the genus are described from the Southern Brazilian coast (50-3000 m deep). The genus Kirkegaardia is generally subdivided into three distinct groups of species (Kirkegaardia dorsobranchialis-heterochaeta, Kirkegaardia baptisteae-tesselata and Kirkegaardia luticastella) and several out-group species for which relationships remains to be defined.

Monsters reveal patterns: bifurcated annelids and their implications for the study of development and evolution.

During recent decades, the study of anatomical anomalies has been of great relevance for research on development and its evolution. Yet most animal groups have never been studied under this perspective. In annelids, one of the most common and remarkable anomalies is anteroposterior axis bifurcation, that is animals that have two or more heads and/or tails.

Effects of GSK3β inhibition in the regeneration of Syllis malaquini (Syllidae, Annelida).

The Wnt/β-catenin signaling pathway has been widely associated to the reestablishment of anteroposterior body polarities in the embryonic development and regeneration in animals. For instance, in annelids, cellular proliferation, wound healing, and blastema development can be affected when this pathway is disrupted. However, very little is known about the genetic regulatory processes involved in these anomalies.

Cellular proliferation dynamics during regeneration in Syllis malaquini (Syllidae, Annelida).

Background: In syllids (Annelida, Syllidae), the regenerative blastema was subject of many studies in the mid and late XX century. This work on syllid regeneration showed that the blastema is developed by a process of dedifferentiation of cells near the wound, followed by their proliferation and redifferentiation (cells differentiate to the original cell type) or, in some specific cases, transdifferentiation (cells differentiate to a cell type different from the original). Up to date, participation of stem cells or pre-existing proliferative cells in the blastema development has never been observed in syllids.

Integrative anatomical study of the branched annelid Ramisyllis multicaudata (Annelida, Syllidae).

The sponge-dwelling Syllidae Ramisyllis multicaudata and Syllis ramosa are the only annelid species for which a branched body with one head and multiple posterior ends is known. In these species, the head is located deep within the sponge, and the branches extend through the canal system of their host. The morphology of these creatures has captivated annelid biologists since they were first discovered in the late XIXth century, and their external characteristics have been well documented.

Pilargidae (Annelida: Phyllodocida) from coastal and deep waters of the Southwestern Atlantic, with descriptions of two new species.

We describe seven species of Pilargidae from the coast and deep sea (300-1400 m deep) of southeastern Brazil, belonging to the genera Ancistrosyllis McIntosh, 1878, Cabira Webster, 1879, Glyphohesione Friedrich, 1950, Hermundura Müller, 1858, and Pilargis Saint-Joseph, 1899. Of those, two are new species (Glyphohesione campensis sp. nov.

Sex-specific gene expression differences in reproducing Syllis prolifera and Nudisyllis pulligera (Annelida, Syllidae).

Syllidae is an annelid family characterized by its complex life cycles involving some of the most outstanding annelid reproductive strategies. Syllid reproductive modes sometimes imply the modification of the posterior body to form independent reproductive units (schizogamy) or the development of swimming adults (epigamy). These modes of sexual reproduction have been studied for more than 150 years, and yet, little is known regarding their molecular background.

Comparative transcriptomics in Syllidae (Annelida) indicates that posterior regeneration and regular growth are comparable, while anterior regeneration is a distinct process.

Background: Annelids exhibit remarkable postembryonic developmental abilities. Most annelids grow during their whole life by adding segments through the action of a segment addition zone (SAZ) located in front of the pygidium. In addition, they show an outstanding ability to regenerate their bodies.

Regeneration mechanisms in Syllidae (Annelida).

Syllidae is one of the most species-rich groups within Annelida, with a wide variety of reproductive modes and different regenerative processes. Syllids have striking ability to regenerate their body anteriorly and posteriorly, which in many species is redeployed during sexual (schizogamy) and asexual (fission) reproduction. This review summarizes the available data on regeneration in syllids, covering descriptions of regenerative mechanisms in different species as well as regeneration in relation to reproductive modes.

A new species of and an annotated checklist of polychaetes from mangroves of the Brazilian Amazon Coast (Annelida, Paraonidae).

The polychaete fauna from the mangroves of the Amazon Coast in Maranhão state, Brazil, is reported in this study. Fourteen species are listed, namely (Leuckart, 1847); Arabella (Arabella) iricolor Montagu, 1804; (Fabricius, 1780) complex; Exogone (Exogone) breviantennata Hartmann-Schröder, 1959; (Claparède, 1864); Müller, 1858; Hartman, 1944; Nageswara Rao, 1981; (Gravier, 1901); (Saint-Joseph, 1901); Perkins, 1980; ; (Hartman, 1945); and Müller, 1858. Among them, and are recorded for the first time in Brazil.