We sought to experimentally verify if testis specific serine/threonine kinases (Tssks) play a role in spermatogenesis and/or the regulation of sperm function. Purified Tssk proteins were obtained based on cloning and expression of mouse Tssk1 and Tssk2. Tssk1 and Tssk2 were detected in mature mouse and human sperm by western blotting. Immunofluorescence indicated that Tssk1 is distributed in the acrosome and the entire flagellum of mouse sperm while Tssk2 was mainly distributed in post-acrosomal region. There was no alteration in the distribution pattern of Tssk1 and Tssk2 in non-capacitated and capacitated sperm. Tssk2 distribution remained unchanged after induced acrosome reaction but no signals were detected in the acrosome for Tssk1, which was present before the acrosome reaction, though signals in flagellum were undisturbed. In human sperm, Tssk1 was found in neck and flagellum while Tssk2 was found in the equatorial region. Our results suggest Tssk1 and/or Tssk2 do play an important role(s) in the regulation of sperm function.

Large-scale dinoflagellate blooms have appeared in recent decades in the Taiwan Strait, Southeast China. To study spatial variability of phytoplankton community composition, physical and chemical environmental drivers in surface seawater of the Taiwan Strait, we conducted cruises in May and July 2019. Cell numbers of dinoflagellates were significantly higher than that of diatoms in most sampling stations during the cruise in May, whereas diatoms were the major contributor to autotrophic biomass in July. Phytoplankton community shifted from a dinoflagellate- and diatom-dominated system in May to diatom dominance in July. The dominant phytoplankton species (genera) were the harmful algal bloom dinoflagellates Prorocentrum donghaiense and Scrippsiella trochoidea and the diatoms Coscinodiscus in May, and Rhizosolenia, Pseudo-nitzschia, and Guinardia in July. Cell densities of dinoflagellates and P. donghaiense reduced exponentially with increasing seawater temperature and salinity and decreasing dissolved inorganic nitrogen (DIN) concentrations. Based on the results of our work and previous studies, it becomes obvious that harmful dinoflagellate blooms are likely to be a major component of the planktonic food web in the Taiwan Strait at a temperature of 17.0–23.0 °C, a salinity of 29.0–33.0 psu, and a DIN concentration higher than 2.0 μmol L–1.