Dosage compensation in birds

AbstractThe Z and W sex chromosomes of birds have evolved independently from the mammalian X and Y chromosomes [1]. Unlike mammals, female birds are heterogametic (ZW), while males are homogametic (ZZ). Therefore male birds, like female mammals, carry a double dose of sex-linked genes relative to the other sex. Other animals with nonhomologous sex chromosomes possess “dosage compensation” systems to equalize the expression of sex-linked genes. Dosage compensation occurs in animals as diverse as mammals, insects, and nematodes, although the mechanisms involved differ profoundly [2]. In birds, however, it is widely accepted that dosage compensation does not occur [3–5], and the differential expression of Z-linked genes has been suggested to underlie the avian sex-determination mechanism [6]. Here we show equivalent expression of at least six of nine Z chromosome genes in male and female chick embryos by using real-time quantitative PCR [7]. Only the Z-linked ScII gene, whose ortholog in Caenorhabditis elegans plays a crucial role in dosage compensation [8], escapes compensation by this assay. Our results imply that the majority of Z-linked genes in the chicken are dosage compensated

CC161 Better Corn More Profits 1957 Summary

Campaign circular 161: Better Corn, talks about the profit that one could earn with the better types of corn, it also has statistics of the different places corn is cropped and being distributed

Loving Blues

https://digitalcommons.library.umaine.edu/mmb-vp/6442/thumbnail.jp

Analysis of a Thrust Vectoring Fighter Aircraft Using Realtime Flight Simulation

A real-time flight simulation model based on the McDonnell Douglas F/A-18 Hornet was created. This model was then modified with two different styles of thrust vectoring so that a study of each system\u27s effect on the aircraft\u27s pitch performance could be conducted in order to determine the best system. At present, work is proceeding on the development of active flight controls for the aircraft. After that effort is completed the thrust vectoring study can begin

Unsteady pressure and structural response measurements of an elastic supercritical wing

Results are presented which define unsteady flow conditions associated with high dynamic response experienced on a high aspect ratio elastic supercritical wing at transonic test conditions while being tested in the NASA Langley Transonic Dynamics Tunnel. The supercritical wing, designed for a cruise Mach number of 0.80, experienced the high dynamic response in the Mach number range from 0.90 to 0.94 with the maximum response occurring at a Mach number of approximately 0.92. At the maximum wing response condition the forcing function appears to be the oscillatory chordwise movement of strong shocks located on both the wing upper and lower surfaces in conjunction with the flow separating and reattaching in the trailing edge region

Examining the Perceptions of School Teams Participating in Professional Development on Restorative Practice

In recent years, restorative justice (RJ) has been used by the criminal justice system to provide an alternative to punishment and retribution in response to crime. Restorative justice’s response to crime requires all parties affected or involved in the crime to come together to repair the harm done to the victim. The parties involved or affected include victim, offender, family, and community. Many schools have considered restorative justice as alternative to suspension and a way to build school community. The purpose of this study was to explore the perceptions of school faculty participating in professional development on restorative practices (RP). Data were collected from the staff making up four focus group teams. The staff were selected from four school teams. The school level represented were Pre-k-2, Pre-k-6 & 8 and Grades 9-12. Several interrelated findings were identified as result of this study. The goals of RP are not in alignment with the primary goals and structure of schools. Misalignment of goals and purpose creates implementation challenges. The research participants acknowledged pockets of RP success within and between schools. However, success was mired with perceived barriers such as the frustrations of absent leadership, competing priorities, voluntary professional development, buy-in challenges, inconsistent implementation and school grade level configuration. These interrelated challenges informed the formulation of several recommendations regarding the implementation of RP. Restorative practices requires the support and participation of leadership at the highest possible level. Staff need to be reassured that academics/ assessment and social emotional growth are equally important school goals. Leadership reassurance needs to be demonstrated through a commitment of time and resources for professional development. Successful implementation requires more than the use of common language. Success implementation requires a common understanding