The Influence of Dormitory Architecture On Resident Behavior

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66943/2/10.1177_001391657300500402.pd

Beyond quantitative and qualitative traits: three telling cases in the life sciences

This paper challenges the common assumption that some phenotypic traits are quantitative while others are qualitative. The distinction between these two kinds of traits is widely influential in biological and biomedical research as well as in scientific education and communication. This is probably due to both historical and epistemological reasons. However, the quantitative/qualitative distinction involves a variety of simplifications on the genetic causes of phenotypic variability and on the development of complex traits. Here, I examine three cases from the life sciences that show inconsistencies in the distinction: Mendelian traits (dwarfism and pigmentation in plant and animal models), Mendelian diseases (phenylketonuria), and polygenic mental disorders (schizophrenia). I show that these traits can be framed both quantitatively and qualitatively depending, for instance, on the methods through which they are investigated and on specific epistemic purposes (e.g., clinical diagnosis versus causal explanation). This suggests that the received view of quantitative and qualitative traits has a limited heuristic power—limited to some local contexts or to the specific methodologies adopted. Throughout the paper, I provide directions for framing phenotypes beyond the quantitative/qualitative distinction. I conclude by pointing at the necessity of developing a principled characterisation of what phenotypic traits, in general, are

Phytochrome A and phytochrome B mediate the hypocotyl-specific downregulation of TUB1 by light in arabidopsis.

Arabidopsis contains six alpha-tubulin and nine beta-tubulin genes that are expressed in a tissue-specific and developmentally regulated manner. We analyzed the effects of light on tubulin mRNA abundance in Arabidopsis seedlings using RNA gel blot hybridizations and gene-specific probes. Transcript levels of all 15 tubulin genes were decreased by continuous white light, although to different degrees. Detailed analysis was performed with the beta-tubulin TUB1 gene. The transcript level of TUB1 was high in etiolated seedlings and decreased to approximately 20% of the dark mRNA level after 2 to 6 hr of white light treatment. We showed that this downregulation requires high-irradiance light treatment and that multiple photoreceptors are involved. In particular, using phytochrome mutants and narrow wave band light, we demonstrated that both the phytochrome A (phyA)-mediated far-red light high-irradiance response and the phytochrome B (phyB)-mediated red light high-irradiance response are involved in the downregulation of TUB1 expression by white light. Histochemical analysis of transgenic plants expressing a TUB1-beta-glucuronidase chimeric transgene indicated that the downregulation observed only in hypocotyls and not in roots is controlled transcriptionally