Hollow sperm syndrome during spermatogenesis in the giant tiger shrimpPenaeus monodon(Fabricius 1798) from eastern Australia

Abstract

During spermatogenesis, giant tiger shrimp (Penaeus monodon) from Queensland, eastern Australia had a high proportion of testicular spermatids that appeared ‘hollow’ because their nuclei were not visible with the haematoxylin and eosin stain. When examined by transmission electron microscopy, the nuclei of hollow spermatids contained highly decondensed chromatin, with large areas missing fibrillar chromatin. Together with hollow spermatids, testicular pale enlarged (PE) spermatids with weakly staining and marginated chromatin were observed. Degenerate‐eosinophilic‐clumped (DEC) spermatids that appeared as aggregated clumps were also present in testes tubules. Among 171 sub‐adult and adult P. monodon examined from several origins, 43% displayed evidence of hollow spermatids in the testes, 33% displayed PE spermatids and 15% displayed DEC spermatids. These abnormal sperm were also found at lower prevalence in the vas deferens and spermatophore. We propose ‘Hollow Sperm Syndrome (HSS)’ to describe this abnormal sperm condition as these morphological aberrations have yet to be described in penaeid shrimp. No specific cause of HSS was confirmed by examining either tank or pond cultured shrimp exposed to various stocking densities, temperatures, salinities, dietary and seasonal factors. Compared with wild broodstock, HSS occurred at higher prevalence and severity among sub‐adults originating from farms, research ponds and tanks. Further studies are required to establish what physiological, hormonal or metabolic processes may cause HSS and whether it compromises the fertility of male P. monodon.

A morphological study of the male reproductive tract, post‐testicular acrosome maturation and spermatophore formation in the black tiger prawn (Penaeus monodon)

“…Poor reproductive potential of domesticated Penaeus monodon broodstock has been a major hurdle to the expansion of aquacultural production in this species (Kumar & Engle, ). Reproductive issues for the male P. monodon broodstock in captivity include abnormal spermatogenesis (Chong et al, ), a lack of mating behavior (Marsden, Richardson, Mather, & Knibb, ) and pathological changes in the reproductive tract (Chamberlain, Johnson, & Lewis, ); consequently, a better understanding of basic male reproductive biology including spermatogenesis, post‐testicular sperm maturation and spermatophore formation is fundamental and critical to addressing these reproductive problems in aquaculture.…”

Spermatogenesis and sperm assessment in the Black Tiger Prawn, Penaeus monodon

“…The inferior reproduction performance of domesticated broodstock of P. monodon has been regarded as one of the prioritized issues for the nauplii production in the prawn aquaculture hatcheries (Browdy, 1998). Although the female domesticated broodstock were believed to be major contributor of poor reproductive outcome (Arnold et al, 2013;Coman et al, 2006), recent studies have also shown the reproductive performance of male broodstock were similarly undermined by the process of domestication (Alfaro-Montoya, 2010;Chong et al, 2015;Parnes et al, 2007). For this case, the level of SDF may be considered as a potential parameter, for which the relative reproductive capacity of selected male broodstock could be assessed; the selection of genetic lines of males exhibiting low levels of SDF could then be the basis of improvements in reproductive efficiency within the prawn aquaculture.…”

“…Ten sexually mature male P. monodon showing no melanization in the gonopores were euthanized in an ice water slurry for 10 min (Thompson et al, 2010) and their reproductive organs were dissected out. The left side of the reproductive organ was fixed in Davidson's solution (1 L contains 220 mL 37-40% formaldehyde, 330 mL 95-100% ethanol, 115 mL glacial acetic acid, 335 mL distilled water, pH 3.5-4.0) for 24 h at room temperature and then transferred to a 70% ethanol solution (Chong et al, 2015) for histological study, whereas the right side was preserved in the crustacean reproductive fixative (2% paraformaldehyde, 2.5% glutaraldehyde in 0.1 M sodium cacodylate with 5% sucrose, pH 7.6) at 4 °C for 24 h (Ro et al, 1990) for transmission electron microscopic study.…”

“…Litopenaeus vannamei (Alfaro-Montoya et al, 2017). Although Hong et al (1998) andChong et al (2015) have previously observed spermatogenesis of Penaeus monodon, the results of those studies were too brief and vague. A thorough understanding of sperm and spermatophore production is fundamental for the assessments and improvements in the reproductive performance of the male domesticated black tiger prawn, P. monodon and other penaeid prawns.…”

“…Poor reproductive potential of domesticated Penaeus monodon broodstock has been a major hurdle to the expansion of aquacultural production in this species (Kumar and Engle, 2016). Reproductive issues for the male P. monodon broodstock in captivity include abnormal spermatogenesis (Chong et al, 2015), a lack of mating behaviour (Marsden et al, 2013) and pathological changes in the reproductive tract (Chamberlain et al, 1983);…”