Droplet vitrification versus straw cryopreservation for spermatozoa banking in Persian sturgeon (Acipenser persicus) from metabolite point of view

Abstract Persian sturgeon( Acipenser persicus ), a commercially valuable and critically endangeredfish species has been suffering considerable declines in populations in the nature due to over-fishing, habitat destructionand marine pollutionduring past decades. Since there were no achievements in artificial reproductionprograms, genetic resource banking such as gametesand embryo cryopreservationcan be a good strategy however, reported resulting gametequalities were considerably low. In the present study, the metabolome content of Persian sturgeonspermatozoa was investigated during common straw cryopreservationand novel droplet vitrificationby the use of 1 H NMR ( Nuclear Magnetic Resonance) spectroscopy. Univariate (ANOVA) and multivariate (PCA) analysis showed significant differences in the metabolic profiles between cryopreservedand fresh spermatozoa samples. Adenine, creatine, creatinephosphate, glucose, guanidoacetate, lactate, N, N - dimethylglycine, and glycine levels showed no significant differences between these two cryopreservationtechniques suggesting these metabolites and their corresponding enzymes and chemical pathways are so vulnerable to the temperature changes and even higher cooling rate in droplet vitrificationcould not conserve them. However, significant differences were found in acetate, creatinine, betaine, β-alanine and trimethylamine N- oxidesuggesting better efficiency of droplet vitrificationin protection of some metabolites associated to spermatozoa energetics, redox balance and hypoxia compensation compared to straw cryopreservation.