Detailed analysis of the male reproductive system in a potential bio-indicator species – The marine invertebrate Galeolaria caespitosa (Polychaeta: Serpulidae)

Abstract

For the first time, this study has systemically investigated the male reproductive system in a sessile broadcast-spawning marine invertebrate, Galeolaria caespitosa (Polychaeta: Serpulidae), which has significant potential as a bio-indicator species of coastal marine pollution. The abdomen of G. caespitosa was divided by intersegmental septa into over 80 trunk segments. Each segment served as a germinal chamber with a C-shaped gonadal arrangement consisting of several distinct compartments: a seminiferous epithelium (SE) compartment located in the centre of the chamber, with each of its two ends connecting to a nurse cell (NC) compartment and then an efferent duct (ED) compartment. The SE compartment contained a multilayered seminiferous epithelium where spermatogenesis was initiated. Spermatids were released in pairs into the lumen of the SE compartment and then transported to the NC compartment where they underwent spermiogenesis with the support of secretory vesicles released by the nurse cells. Spermatozoa were stored in the ED compartment and subsequently released into the seawater through the vas deferens. Unlike vertebrates where germ cells differentiated in close proximity to the nurse cell population (i.e. Sertoli cells), the spermatogenic cells of G. caespitosa exhibited no direct contact with supporting cells at any spermatogenic stage. This finding suggested that the spermatogenesis in G. caespitosa was more dependent on intrinsic developmental programming than most species. Notwithstanding such differences, there were clear parallels between the male reproductive system of G. caespitosa and mammals, in terms of the structure and function. The independence of spermatogenic cells from supporting cells in G. caespitosa raised the possibility of inducing spermiogenesis in vitro, which would provide a useful tool to dissect the mechanisms underlying this complex cell differentiation process in invertebrates and other higher order animals.

Opinion paper about organic trace pollutants in wastewater: Toxicity assessment in a European perspective

“…The results can be applied in ecological risk assessments (ERA), to yield Species Sensitivity Distributions (SSDs), which model species sensitivity to chemicals or other stressors (Posthuma et al, 2002) (Tulloch et al, 2016b) (Liu et al, 2014). At the border between organismal and population levels, alterations on growth and development, reproduction and behavior, are issues of concern: tests on fish, birds, terrestrial and aquatic invertebrates, terrestrial and aquatic macrophytes, and microscopic plants are commonly part of monitoring campaigns (Kapustka, 2003) (Moro et al, 2014) (Gauthier et al, 2016) (Schwindt, 2015) (Lu et al, 2017) (Díaz-Gil et al, 2017 (Gür et al, 2016) (Gopalapillai et al, 2014) (van Wijngaarden and Arts, 2018).…”

Embryonic and larval development in the semelparous Nereid polychaete Hediste diversicolor (OF Müller, 1776) in Norway: Challenges and perspectives

“…Males' germ cells originate from the seminiferous epithelium and are released into the coelom at an early stage (Dales, 1950). Lu, Aitken, and Lin (2017) found that the spermatids consisted of paired spermatocytes connected by a cytoplasmic bridge. Spermatids in early development were without tails, which developed over time.…”

Ultrastructural investigation and in vitro recapitulation of spermatid differentiation in a potential bio-indicator species – The marine invertebrate Galeolaria gemineoa (Polychaeta: Serpulidae)

“…According to previous studies from our laboratory, the entire process of spermiogenesis in G . gemineoa occurs while the gametes are floating freely in the lumen of the germinal chamber unattached to nurse cells of any kind [ 20 ]. Such independence from supporting cells makes spermiogenesis in G .…”