Expression patterns of gdnf and gfrα1 in rainbow trout testis.

In mice, glial cell line-derived neurotrophic factor (GDNF) is essential for normal spermatogenesis and in vitro culture of spermatogonial stem cells. In murine testes, GDNF acts as paracrine factor; Setoli cells secrete it to a subset of spermatogonial cells expressing its receptor, GDNF family receptor α1 (GFRα1). However, in fish, it is unclear what types of cells express gdnf and gfrα1. In this study, we isolated the rainbow trout orthologues of these genes and analyzed their expression patterns during spermatogenesis. In rainbow trout testes, gdnf and gfrα1 were expressed in almost all type A spermatogonia (ASG). Noticeably, unlike in mice, the expression of gdnf was not observed in Sertoli cells in rainbow trout. During spermatogenesis, the expression levels of these genes changed synchronously; gdnf and gfrα1 showed high expression in ASG and decreased dramatically in subsequent developmental stages. These results suggested that GDNF most likely acts as an autocrine factor in rainbow trout testes

Cricoid ossification mimicking an impacted foreign body.

金沢大学医学部附属病院耳鼻咽喉科A 54-year-old man complained of severe throat pain and showed subglottic oedema on fibre-optic endoscopy with a distinctly narrowed subglottic space on anteroposterior radiography of the neck and dense linear opacity at the level of the cricoid cartilage on lateral plain radiography. These findings suggested a foreign body just posterior to the cricopharyngeus, but a computed tomography (CT) scan demonstrated a dense calcified ridge on the posterior lamina of the cricoid cartilage but no foreign body.The patient improved symptomatically with systemic antibiotics and topical steroids, and gastrointestinal endoscopy did not detect any foreign body. This is a rare case of vertical ossification of the cricoid lamina masquerading as a foreign body

Functional Sperm of the Yellowtail (Seriola quinqueradiata) Were Produced in the Small-Bodied Surrogate, Jack Mackerel (Trachurus japonicus).

Production of xenogeneic gametes from large-bodied, commercially important marine species in closely related smaller surrogates with short generation times may enable rapid domestication of the targeted species. In this study we aimed to produce gametes of Japanese yellowtail (Seriola quinqueradiata) using jack mackerel (Trachurus japonicus) as a surrogate with a smaller body size and shorter maturation period. Donor spermatogonia were collected from the testes of yellowtail males and transferred into the peritoneal cavity of 10- and 12-day-old jack mackerel larvae. Twenty days later, 59.5% of the recipients survived of which 88.2% had donor-derived germ cells in their gonads. One year later, genomic DNA templates were prepared from the semen of 96 male recipients and subjected to PCR analyses using primers specific for the yellowtail vasa sequence, resulting in the detection of positive signals in semen from two recipients. The milt collected from the recipients was used for fertilization with yellowtail eggs. Of eight hatchlings obtained from the crosses, two were confirmed to be derived from donor yellowtail by DNA markers, although the others were gynogenetic diploids. These findings indicate that it is possible to produce donor-derived sperm in xenogeneic recipients with smaller body size and shorter generation time by transplanting spermatogonia. Thus, the xenogeneic transplantation of spermatogonia might be a potential tool to produce gametes of large-bodied, commercially important fish although the efficiency of the method requires further improvement. This is the first report demonstrating that donor-derived sperm could be produced in xenogeneic recipient via spermatogonial transplantation in carangid fishes

Identification and Migration of Primordial Germ Cells in Atlantic Salmon, Salmo salar : Characterization of Vasa, Dead End, and Lymphocyte Antigen 75 Genes

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Identification and migration of primordial germ cells in Atlantic salmon, Salmo salar: characterization of vasa, dead end, and lymphocyte antigen 75 genes

No information exists on the identification of primordial germ cells (PGCs) in superorder Protacanthopterygii, which includes the Salmonidae family and Atlantic salmon (Salmo salar L.), one of the most commercially important aquatic animals worldwide. In order to identify salmon PGCs, we cloned the full-length cDNA of vasa, dead end (dnd), and lymphocyte antigen 75 (ly75/CD205) genes as germ cell marker candidates, and analyzed their expression patterns in both adult and embryonic stages of Atlantic salmon. Semi-quantitative RT-PCR results showed that salmon vasa and dnd were specifically expressed in testis and ovary, and vasa, dnd, and ly75 mRNA were maternally deposited in the egg. Vasa mRNA was consistently detected throughout embryogenesis, while dnd and ly75 mRNA were gradually degraded during cleavages. Further in situ hybridization (ISH) analyses revealed the localization of vasa, dnd mRNA, and Ly75 protein in PGCs of hatched larvae. Whole-mount ISH (WISH) detected vasa mRNA during embryogenesis, showing a distribution pattern somewhat different to that of zebrafish; specifically, at mid-blastula stage, vasa-expressing cells were randomly distributed at the central part of blastodisc, and then they migrated to the presumptive region of embryonic shield. Therefore, the typical vasa localization pattern of four clusters during blastulation, as found in zebrafish, was not present in Atlantic salmon. In addition, salmon PGCs could be specifically labeled with a green fluorescence protein (GFP) using Gfp-rt-vasa 3’UTR RNA microinjection for further applications. These findings may assist in understanding PGC development not only in Atlantic salmon but also in other salmonids