Background

The occurrence of liver cancer is higher in males than in females, and the incidence increases during aging. Signaling pathways regulated by retinoid x receptor alpha (RXRalpha) are involved in hepatocellular carcinogenesis. The phenotype of hepatocyte RXRalpha deficient mice is different between genders. To explore the impact of hepatocyte RXRalpha deficiency on gender-dependent hepatic gene expression, we compared the expression profiles of cancer-related genes in 6 and 24 month old male and female mice.

Results

In 6 month old mice, male mutant mice showed more cancer-related genes with alteration in mRNA levels than females did (195 vs. 60). In aged mice (24 month), female mutant mice showed greater deviation in mRNA expression levels of cancer-related genes than their male counterparts (149 vs. 82). The genes were classified into five categories according to their role in carcinogenesis: apoptosis, metastasis, cell growth, stress, and immune respnse. In each category, dependent upon age and gender, the genes as well as the number of genes with altered mRNA levels due to RXRalpha deficiency varies.

Conclusion

The change in hepatic cancer-related gene expression profiles due to RXRalpha deficiency was gender- and age-dependent. The alteration of mRNA levels of cancer-related genes implied that aberrant RXRalpha signaling could potentially increase the risk of liver cancer and that retinoid signaling might contribute to gender- and age-associated liver cancer incidence.

We describe PSR J1926-0652, a pulsar recently discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Using sensitive single-pulse detections from FAST and long-term timing observations from the Parkes 64 m radio telescope, we probed phenomena on both long and short timescales. The FAST observations covered a wide frequency range from 270 to 800 MHz, enabling individual pulses to be studied in detail. The pulsar exhibits at least four profile components, short-term nulling lasting from 4 to 450 pulses, complex subpulse drifting behaviors and intermittency on scales of tens of minutes. While the average band spacing P 3 is relatively constant across different bursts and components, significant variations in the separation of adjacent bands are seen, especially near the beginning and end of a burst. Band shapes and slopes are quite variable, especially for the trailing components and for the shorter bursts. We show that for each burst the last detectable pulse prior to emission ceasing has different properties compared to other pulses. These complexities pose challenges for the classic carousel-type models.