Adult sex ratios affect mating behaviour in the common housefly <i>Musca domestica</i> L. (Diptera; Muscidae)

Adult sex ratio determines the level of mate availability and intrasexual competition for each sex. Sex ratio biases have been proposed to enhance the productivity of animal rearing procedures. However, behaviour may change in response to sex ratio manipulations that may counteract potential benefits. We investigated how sex ratios affected mating behaviour of the housefly Musca domestica, a species used in the animal feed industry. We hypothesized a reduced courtship effort and mating latency and increased ejaculate allocation (copulation duration) under male-biased sex ratios, whereas female-biased sex ratios would lead to the opposite effects. However, courtship effort was reduced in female-biased groups, implying reduced male harassment. Mating latency was lower and copulation lasted longer in female-biased groups, which may reduce reproduction time and increase female fecundity and lifespan. Our results indicate that in houseflies, female-biased sex ratios cause behavioural changes in both sexes that could positively contribute to reproductive output

Adult sex ratios affect mating behaviour in the common housefly <i>Musca domestica</i> L. (Diptera; Muscidae)

Adult sex ratio determines the level of mate availability and intrasexual competition for each sex. Sex ratio biases have been proposed to enhance the productivity of animal rearing procedures. However, behaviour may change in response to sex ratio manipulations that may counteract potential benefits. We investigated how sex ratios affected mating behaviour of the housefly Musca domestica, a species used in the animal feed industry. We hypothesized a reduced courtship effort and mating latency and increased ejaculate allocation (copulation duration) under male-biased sex ratios, whereas female-biased sex ratios would lead to the opposite effects. However, courtship effort was reduced in female-biased groups, implying reduced male harassment. Mating latency was lower and copulation lasted longer in female-biased groups, which may reduce reproduction time and increase female fecundity and lifespan. Our results indicate that in houseflies, female-biased sex ratios cause behavioural changes in both sexes that could positively contribute to reproductive output

Radioactive Holmium Acetylacetonate Microspheres for Interstitial Microbrachytherapy: An In Vitro and In Vivo Stability Study

Purpose The clinical application of holmium acetylacetonate microspheres (HoAcAcMS) for the intratumoral radionuclide treatment of solid malignancies requires a thorough understanding of their stability. Therefore, an in vitro and an in vivo stability study with HoAcAcMS was conducted. Methods HoAcAcMS, before and after neutron irradiation, were incubated in a phosphate buffer at 37°C for 6 months. The in vitro release of holmium in this buffer after 6 months was 0.5%. Elemental analysis, scanning electron microscopy, infrared spectroscopy and time of flight secondary ion mass spectrometry were performed on the HoAcAcMS. Results After 4 days in buffer the acetylacetonate ligands were replaced by phosphate, without altering the particle size and surface morphology. HoAcAcMS before and after neutron irradiation were administered intratumorally in VX2 tumor-bearing rabbits. No holmium was detected in the faeces, urine, femur and blood. Histological examination of the tumor revealed clusters of intact microspheres amidst necrotic tissue after 30 days. Conclusion HoAcAcMS are stable both in vitro and in vivo and are suitable for intratumoral radionuclide treatment.Radiation, Radionuclides and ReactorsApplied Science

The ETS Family Member TEL Binds to Nuclear Receptors RAR and RXR and Represses Gene Activation

Retinoic acid receptor (RAR) signaling is important for regulating transcriptional activity of genes involved in growth, differentiation, metabolism and reproduction. Defects in RAR signaling have been implicated in cancer. TEL, a member of the ETS family of transcription factors, is a DNA-binding transcriptional repressor. Here, we identify TEL as a transcriptional repressor of RAR signaling by its direct binding to both RAR and its dimerisation partner, the retinoid x receptor (RXR) in a ligand-independent fashion. TEL is found in two isoforms, created by the use of an alternative startcodon at amino acid 43. Although both isoforms bind to RAR and RXR in vitro and in vivo, the shorter form of TEL represses RAR signaling much more efficiently. Binding studies revealed that TEL binds closely to the DNA binding domain of RAR and that both Helix Loop Helix (HLH) and DNA binding domains of TEL are mandatory for interaction. We have shown that repression by TEL does not involve recruitment of histone deacetylases and suggest that polycomb group proteins participate in the process

Repression of TEL on RAR/RXR-mediated transcription does not involve histone deacetylase activity.

<p>Increasing amounts of TSA were tested on RARE luc reporter in the presence of ATRA, and with and without M1-TEL, M43-TEL or MN1-TEL (120 ng). RAR/RXR-mediated transcription was stimulated by TSA to high levels, whereas M43-TEL prevents this. Intermediate effects were observed with MN1-TEL and M1-TEL.</p

TEL represses transcription that is mediated by the heterodimer RAR/RXR.

<p>(A) Schematic overview of different luciferase reporter constructs RARE-luc, MSV-luc and RARE3MSV-luc. (B) The M43-TEL isoform inhibits the RARE luc reporter whereas the M1-TEL isoform does not. (C) The viral promoter MSV is repressed by both isoforms of TEL. M43-TEL is more efficient. (D) Both TEL isoforms repress the RARE3 MSV-luc construct. M43-TEL is more efficient. All transfections were performed in the presence of <i>all-trans</i> retinoic acid (ATRA).</p

Deletion mutants of TEL have no repressive activity.

<p>(A) Three different reporters were tested with TEL deletion mutants. The repression of TEL on the RAR-RXR dimer (i.e. RARE luc and RARE3-MSV luc) was only detected using full length M43 TEL. Although deletion mutant HD was able to bind RAR in vitro (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0023620#pone-0023620-g001" target="_blank">figure 1</a>), it was unsuccessful in repression. The MSV-luc reporter contains not only an RAR/RXR responsive element but also many possible ETS binding sites (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0023620#pone-0023620-g002" target="_blank">figure 2E</a>). The HD deletion construct of TEL repressed the MSV-luc reporter efficiently. (B) Both modes of repression by TEL (i.e. on RAR/RXR and on ETS sites) are disabled in the HLH mutant of TEL (TEL-V112A/L113A).</p