Correlation of Radiocesium Activity between Muscle and Peripheral Blood of Live Cattle Depending on Presence or Absence of Radiocontamination in Feed.

To monitor radiocesium activity in skeletal muscle of live cattle, the animals were given radiocesium-contaminated feed continuously, then switched to contamination-free feed after radiocecium concentration in peripheral blood (PB) reached plateau. Radioactivity in skeletal muscles of neck and rump was measured by attaching the probe of a NaI survey meter closely on the body surface just above the muscle of the live cattle (external measurement). We validated the strong positive correlation between the value of the external measurement and radiocesium activity concentration of dissected muscle (r = 0.89, P < 0.001 for neck; r = 0.80, P < 0.001 for rump). Accumulation of radiocesium both in muscle and PB was proportional to the total amount of radiocesium cattle ingested. However, radioactivity concentration in PB was constant in the cattle that had continuously ingested radiocesium, lower than 2.0 × 105 Bq in total within 67 days from the beginning of radiocesium intake. In addition, the ratio of radiocesium activity in muscle to that in PB was lower during the time when radiocontaminated feed was ingested than that of contamination-free feed ingestion. Using the correlation of radioactivity between muscle and PB, we confirmed that a majority of the cattle in the ex-evacuation zone of the Fukushima Daiichi nuclear power plant accident, from 167 to 365 days after the accident occurred, were in the declining period of radiocesium intake.

Exogenous neurotensin modulates sperm function in Japanese Black cattle.

Recently, the conception rates after artificial insemination have been pointed out to decline continuously. To overcome this problem, the control of frozen and thawed sperm quality is required. However, the mechanism of bovine sperm functional regulation is still largely unknown. In mammals, the ejaculated sperm are capable of showing fertilizing ability during migration in the female reproductive organs. It is well known that these female organs secrete several factors contributing to sperm capacitation. We previously reported that neurotensin (NT) secreted from the oviduct and cumulus cells enhanced sperm capacitation and acrosome reaction in mice. In this study, we confirmed the expression of the NT receptor (NTR1) in the bovine sperm neck region and the secretion of NT in the bovine uterus and oviduct. The similar expression patterns of NT and NTR1 suggests a conserved mechanism of sperm functional regulation between mouse and cattle. Thus, we examined the effects of exogenous NT on the bovine sperm functions. First, we showed that NT induced sperm protein tyrosine phosphorylation in a dose-dependent manner, suggesting that NT enhances sperm capacitation. Second, we showed that NT induced acrosome reactions of capacitated sperm in a dose-dependent manner, suggesting that NT facilitates acrosome reaction. Finally, we used a computer-aided sperm analysis system to show that NT did not have a great effect on sperm motility. These results suggest that NT acts as a facilitator of sperm capacitation and acrosome reaction in the female reproductive tracts in cattle, highlighting the importance of NT-mediated signaling to regulate sperm functions.