Surrogate production of genome edited sperm from a different subfamily by spermatogonial stem cell transplantation

The surrogate reproduction technique provides a powerful tool for production of allogenic or xenogeneic gametes derived from endangered species or those with valuable genetic traits. Production of functional donor-derived gametes through intra- or inter-specific spermatogonial stem cell transplantation (SSCT) has been achieved in many species. However, generation of functional gametes from a phylogenetically distant species such as from a different subfamily by SSCT has never been successful. Here, using two small cyprinid fishes, Chinese rare minnow (gobiocypris rarus, for brief: Gr) and zebrafish (danio rerio), which belong to different subfamilies, as donors and recipients for SSCT, we optimized the SSCT technique and successfully obtained Gr-derived sperm carrying targeted genome modifications in zebrafish. We revealed that the transplanted Gr spermatogonia supported the host gonadal development and underwent normal spermatogenesis, resulting in a reconstructed fertile testis containing Gr spermatids and zebrafish testicular somatic cells. Interestingly, the surrogate spermatozoa resembled those of host zebrafish but not donor Gr in morphology and swimming behavior. Finally, we showed that Gr-derived genome edited sperm was successfully produced in zebrafish by cross-subfamily SSCT, when the pou5f3 and chd gene knockout Gr SSCs were used as surrogate donors. This is the first report demonstrating the surrogate production of genome edited sperm from a phylogenetically distant species, and this method is feasible to be applied to future breeding of commercial fishes.

The Cambridge–Cambridge controversy on the theory of capital: 50 years after

The paper points out that capital theory has always been a hotly debated subject, partly because the theoretical issues involved are very complex, and partly because rival ideologies and value systems directly affect the issues discussed. The focus is on the history, the main protagonists, and the relevant problems examined and argued about during the two Cambridges controversy on the theory of capital which was at its peak 50 years ago. Whereas one clear result of these debates is that neither Samuelson's surrogate production function nor Solow's rate-of-return concept could resurrect aggregate neoclassical theory, many other questions, such as the treatment of capital in temporary or intertemporal general equilibrium models or the empirical relevance of the reswitching phenomenon, are still discussed controversially.

Dnd1 Knockout in Sturgeons By CRISPR/Cas9 Generates Germ Cell Free Host for Surrogate Production

Sturgeons also known as living fossils are facing threats to their survival due to overfishing and interference in natural habitats. Sterlet (Acipenser ruthenus) due to its rapid reproductive cycle and small body size can be used as a sterile host for surrogate production for late maturing and large sturgeon species. Dead end protein (dnd1) is essential for migration of Primordial Germ Cells (PGCs), the origin of all germ cells in developing embryos. Knockout or knockdown of dnd1 can be done in order to mismigrate PGCs. Previously we have used MO and UV for the aforementioned purpose, and in our present study we have used CRISPR/Cas9 technology to knockout dnd1. No or a smaller number of PGCs were detected in crispants, and we also observed malformations in some CRISPR/Cas9 injected embryos. Furthermore, we compared three established methods to achieve sterility in sterlet, and we found higher embryo survival and hatching rates in CRISPR/Cas9, UV and MO, respectively.

Cryopreservation and transplantation of common carp spermatogonia

Common carp (Cyprinus carpio) is one of the most cultured fish species over the world with many different breeds and plenty of published protocols for sperm cryopreservation, however, data regarding preservation of gonadal tissue and surrogate production is still missing. A protocol for freezing common carp spermatogonia was developed through varying different factors along a set of serial subsequent experiments. Among the six cryoprotectants tested, the best survival was achieved with dimethyl sulfoxide (Me2SO). In the next experiment, a wide range of cooling rates (0.5–10 °C/min) and different concentrations of Me2SO were tested resulting in the highest survival using 2 M Me2SO and cooling rate of –1 Q59 A When testing different tissue sizes and incubation times in the cryomedium, the highest viability was observed when incubating 100 mg tissue fragments for 30 min. Finally, sugar supplementation did not yield significant differences. When testing different equilibration (ES) and vitrification solutions (VS) used for needle-immersed vitrification, no significant differences were observed between the tested groups. Additionally, varied exposure time to VS did not improve the vitrification outcome where the viability was 4-fold lower than that of freezing. The functionality of cryopreserved cells was tested by interspecific transplantation into sterilized goldfish recipients. The exogenous origin of the gonads in goldfish recipients was confirmed by molecular markers and incorporation rate was over 40% in both groups at 3 months post transplantation. Results of this study can serve as an alternative way for long-term preservation of germplasm in carp which can be recovered in a surrogate recipient.