Controlled-release urea (CRU) has better characteristics than conventional urea for synchronizing nitrogen (N) release with plant uptake.  Understanding the effects of CRU on crop yield and N use efficiency (NUE) has long been the key to evaluate the performance of CRU.  A long-term experiment over five consecutive years was conducted in Changsha, Hunan Province, China, to investigate the effects of polyethylene-coated urea with a 90-d release period on the yield and NUE of double rice (early and late crops are grown in the same year), the amount of residual soil mineral N and the soil–plant N balance, as well as on the economic benefits.  Four N fertilizer treatments including CK (no N fertilizer), U (conventional urea), CRU1 (polyethylene-coated urea with equal N application rate to U) and CRU2 (20% reduction in N application rate of CRU1) were established.  The results indicated that CRU1 application increased the yield and NUE of double rice by 11.0 and 13.5%, respectively, compared with U.  Higher yield and NUE of late rice were found than in early rice in CRU treatments.  Compared with conventional U, the yield and NUE of early rice in the CRU1 treatment were increased by 6.0 and 10.2%, respectively, and those of late rice were increased by 15.4 and 13.8%, respectively.  There was no significant difference between CRU1 and CRU2 in double rice yield.  Furthermore, CRU treatments (including CRU1 and CRU2) had higher apparent residual N_min rate (ARNR) and apparent N recovery rate (ANRR), but lower apparent N loss (N_S) than the conventional U treatment.  Concentrations of NH₄⁺-N and NO₃^–-N were greater in the surface soil (0–20 cm) and lower in the deeper soil layer (40–60 cm) with CRU treatments than in the U treatment after harvest.  Moreover, CRU application produced a greater economic benefit than conventional U application.  In general, CRU outperformed U fertilizer in terms of rice yield, NUE, soil–plant N balance, economic benefit, and CRU2 provided greater comprehensive benefits than CRU1.  It is suggested that CRU application is beneficial for solving N management challenges in the production of rice.

CatSper is a unique Ca2+ channel-like protein family exclusively expressed in the testis and sperm, and plays important roles in sperm motility, capacitation, acrosome reaction and sperm-egg interactions. Here we studied the mechanism of regulation of CatSper2-dependent Ca2+ influx, extracellular and intracellular Ca2+ on sperm hyperactivated motility. The siRNA duplexes were transfected into the sperm cells by electroporation (EP) to silence the expression of CatSper2. The results for targeted disruption of CatSper2 showed the highest silence efficiency 77.7% (P<0.05), the hyperactivated sperm rate calculated by computer-assisted semen analysis (CASA) analysis of interferenced sperm was significantly lower 11.1% than the control 99.2%. Flow cytometry (FCM) detection of the intracellular Ca2+ concentration of interferenced sperm was 50 nmol L-1 higher than the normal. It was remarkably lower than hyperactivated sperm with 200-1 000 nmol L-1 (P<0.05). It was not sufficient to evoke hyperactivation. To trigger hyperactivation, the sperm were incubated in 50 μmol L-1 thimerosal or 5 mmol L-1 procaine, it sharply increased the intracellular Ca2+ via two different channels. CASA and FCM detection indicated that intracellular Ca2+ is required for initiating hyperactivation while extracellular Ca2+ is essential to maintain the process. We concluded that to mediate sperm hyperactivation, it is essential to inhibit Ca2+ peak present with targeted disruption of CatSper2 expression. This provides important prospective for further exploration of signal channel of sperm hyperactivated motility, potential factors for male infertility and provide further reference to the exploration of male contraceptive drug targets of male reproduction.