How Do Honeybees Attract Nestmates Using Waggle Dances in Dark and Noisy Hives?

It is well known that honeybees share information related to food sources with nestmates using a dance language that is representative of symbolic communication among non-primates. Some honeybee species engage in visually apparent behavior, walking in a figure-eight pattern inside their dark hives. It has been suggested that sounds play an important role in this dance language, even though a variety of wing vibration sounds are produced by honeybee behaviors in hives. It has been shown that dances emit sounds primarily at about 250–300 Hz, which is in the same frequency range as honeybees' flight sounds. Thus the exact mechanism whereby honeybees attract nestmates using waggle dances in such a dark and noisy hive is as yet unclear. In this study, we used a flight simulator in which honeybees were attached to a torque meter in order to analyze the component of bees' orienting response caused only by sounds, and not by odor or by vibrations sensed by their legs. We showed using single sound localization that honeybees preferred sounds around 265 Hz. Furthermore, according to sound discrimination tests using sounds of the same frequency, honeybees preferred rhythmic sounds. Our results demonstrate that frequency and rhythmic components play a complementary role in localizing dance sounds. Dance sounds were presumably developed to share information in a dark and noisy environment

Dysregulation of Gene Expression in the Artificial Human Trisomy Cells of Chromosome 8 Associated with Transformed Cell Phenotypes

A change in chromosome number, known as aneuploidy, is a common characteristic of cancer. Aneuploidy disrupts gene expression in human cancer cells and immortalized human epithelial cells, but not in normal human cells. However, the relationship between aneuploidy and cancer remains unclear. To study the effects of aneuploidy in normal human cells, we generated artificial cells of human primary fibroblast having three chromosome 8 (trisomy 8 cells) by using microcell-mediated chromosome transfer technique. In addition to decreased proliferation, the trisomy 8 cells lost contact inhibition and reproliferated after exhibiting senescence-like characteristics that are typical of transformed cells. Furthermore, the trisomy 8 cells exhibited chromosome instability, and the overall gene expression profile based on microarray analyses was significantly different from that of diploid human primary fibroblasts. Our data suggest that aneuploidy, even a single chromosome gain, can be introduced into normal human cells and causes, in some cases, a partial cancer phenotype due to a disruption in overall gene expression

Assessment of the effect of betaine on p16 and c-myc DNA methylation and mRNA expression in a chemical induced rat liver cancer model

<p>Abstract</p> <p>Background</p> <p>The development and progression of liver cancer may involve abnormal changes in DNA methylation, which lead to the activation of certain proto-oncogenes, such as <it>c-myc</it>, as well as the inactivation of certain tumor suppressors, such as <it>p16</it>. Betaine, as an active methyl-donor, maintains normal DNA methylation patterns. However, there are few investigations on the protective effect of betaine in hepatocarcinogenesis.</p> <p>Methods</p> <p>Four groups of rats were given diethylinitrosamine (DEN) and fed with AIN-93G diets supplemented with 0, 10, 20 or 40 g betaine/kg (model, 1%, 2%, and 4% betaine, respectively), while the control group, received no DEN, fed with AIN-93G diet. Eight or 15 weeks later, the expression of <it>p16 </it>and <it>c-myc </it>mRNA was examined by Real-time PCR (Q-PCR). The DNA methylation status within the <it>p16 </it>and <it>c-myc </it>promoter was analyzed using methylation-specific PCR.</p> <p>Results</p> <p>Compared with the model group, numbers and areas of glutathione S-transferase placental form (GST-p)-positive foci were decreased in the livers of the rats treated with betaine (<it>P < 0.05</it>). Although the frequency of <it>p16 </it>promoter methylation in livers of the four DEN-fed groups appeared to increase, there is no difference among these groups after 8 or 15 weeks (<it>P > 0.05</it>). Betaine supplementation attenuated the down-regulation of <it>p16 </it>and inhibited the up-regulation of <it>c-myc </it>induced by DEN in a dose-dependent manner (<it>P </it>< 0.01). Meanwhile, increases in levels of malondialdehyde (MDA) and glutathione S-transferase (GST) in model, 2% and 4% betaine groups were observed (<it>P < 0.05</it>). Finally, enhanced antioxidative capacity (T-AOC) was observed in both the 2% and 4% betaine groups.</p> <p>Conclusion</p> <p>Our data suggest that betaine attenuates DEN-induced damage in rat liver and reverses DEN-induced changes in mRNA levels.</p