AGL1-AGL6, an Arabidopsis gene family with similarity to floral homeotic and transcription factor genes

The predicted products of floral homeotic genes, AGAMOUS (AG) from Arabidopsis thaliana and DEFICIENS A (DEF A) from Antirrhinum majus, have been shown previously to share strong sequence similarity with transcription factors from humans (SRF) and yeast (MCM1). The conserved sequence between these proteins is localized within a domain known to be necessary for the DNA binding and for the dimerization of SRF. We have isolated six new genes from A. thaliana, AGL1-AGL6, which also have this conserved sequence motif. On the basis of the sequence comparison between the AG and AGL genes, they can be assigned to two subfamilies of a large gene family. RNA dot blot analysis indicates that five of these genes (AGL1, AGL2, AGL4, AGL5, and AGL6) are preferentially expressed in flowers. In addition, in situ RNA hybridization experiments with AGL1 and AGL2 show that their mRNAs are detected in some floral organs but not in others. Our results suggest that these genes may act to control many steps of Arabidopsis floral morphogenesis. In contrast, the AGL3 gene is expressed in vegetative tissues as well as in flowers, suggesting that it functions in a broader range of tissues. We discuss possible roles of this gene family during the evolution of flowers

The N-end rule pathway controls multiple functions during Arabidopsis shoot and leaf development

The ubiquitin-dependent N-end rule pathway relates the in vivo half-life of a protein to the identity of its N-terminal residue. This proteolytic system is present in all organisms examined and has been shown to have a multitude of functions in animals and fungi. In plants, however, the functional understanding of the N-end rule pathway is only beginning. The N-end rule has a hierarchic structure. Destabilizing activity of N-terminal Asp, Glu, and (oxidized) Cys requires their conjugation to Arg by an arginyl–tRNA–protein transferase (R-transferase). The resulting N-terminal Arg is recognized by the pathway's E3 ubiquitin ligases, called “N-recognins.” Here, we show that the Arabidopsis R-transferases AtATE1 and AtATE2 regulate various aspects of leaf and shoot development. We also show that the previously identified N-recognin PROTEOLYSIS6 (PRT6) mediates these R-transferase-dependent activities. We further demonstrate that the arginylation branch of the N-end rule pathway plays a role in repressing the meristem-promoting BREVIPEDICELLUS (BP) gene in developing leaves. BP expression is known to be excluded from Arabidopsis leaves by the activities of the ASYMMETRIC LEAVES1 (AS1) transcription factor complex and the phytohormone auxin. Our results suggest that AtATE1 and AtATE2 act redundantly with AS1, but independently of auxin, in the control of leaf development

AGL1-AGL6, an Arabidopsis gene family with similarity to floral homeotic and transcription factor genes

The predicted products of floral homeotic genes, AGAMOUS (AG) from Arabidopsis thaliana and DEFICIENS A (DEF A) from Antirrhinum majus, have been shown previously to share strong sequence similarity with transcription factors from humans (SRF) and yeast (MCM1). The conserved sequence between these proteins is localized within a domain known to be necessary for the DNA binding and for the dimerization of SRF. We have isolated six new genes from A. thaliana, AGL1-AGL6, which also have this conserved sequence motif. On the basis of the sequence comparison between the AG and AGL genes, they can be assigned to two subfamilies of a large gene family. RNA dot blot analysis indicates that five of these genes (AGL1, AGL2, AGL4, AGL5, and AGL6) are preferentially expressed in flowers. In addition, in situ RNA hybridization experiments with AGL1 and AGL2 show that their mRNAs are detected in some floral organs but not in others. Our results suggest that these genes may act to control many steps of Arabidopsis floral morphogenesis. In contrast, the AGL3 gene is expressed in vegetative tissues as well as in flowers, suggesting that it functions in a broader range of tissues. We discuss possible roles of this gene family during the evolution of flowers

Alignment between PIN1 Polarity and Microtubule Orientation in the Shoot Apical Meristem Reveals a Tight Coupling between Morphogenesis and Auxin Transport

Morphogenesis during multicellular development is regulated by intercellular signaling molecules as well as by the mechanical properties of individual cells. In particular, normal patterns of organogenesis in plants require coordination between growth direction and growth magnitude. How this is achieved remains unclear. Here we show that in Arabidopsis thaliana, auxin patterning and cellular growth are linked through a correlated pattern of auxin efflux carrier localization and cortical microtubule orientation. Our experiments reveal that both PIN1 localization and microtubule array orientation are likely to respond to a shared upstream regulator that appears to be biomechanical in nature. Lastly, through mathematical modeling we show that such a biophysical coupling could mediate the feedback loop between auxin and its transport that underlies plant phyllotaxis

Revisiting the ‘Great Levelling’: the limits of Piketty’s Capital and Ideology for understanding the rise of late 20th century inequality

In Capital and Ideology, Thomas Piketty returns to questions of historical inequality, not merely to fill in the gaps in the earlier, widely circulated and impactful Capital in the 21st Century, but to undertake a far more ambitious and nuanced project. Critics (Bhambra and Holmwood 2017; Moeller 2015) pointed out that in the previous book, Piketty’s consideration of the role of high concentrations wealth on inequality focused largely on a handful of relatively wealthy countries (the US, UK, France, Germany and Japan). More importantly, it did not consider the political and economic relationships, forged by European colonization and the trans-Atlantic slave trade, that helped create lasting inequalities in wealth, status, education and life expectancy around the globe. These oversights corresponded to significant methodological gaps, in which inequalities defined by social status and identity, including gender, race and caste, were largely left out of considerations that centred around economic and material disparities. Yet these different forms of inequalities are intimately connected, as gender wage gaps and racial wealth gaps in different parts of the world attest

DEP and AFO Regulate Reproductive Habit in Rice

Sexual reproduction is essential for the life cycle of most angiosperms. However, pseudovivipary is an important reproductive strategy in some grasses. In this mode of reproduction, asexual propagules are produced in place of sexual reproductive structures. However, the molecular mechanism of pseudovivipary still remains a mystery. In this work, we found three naturally occurring mutants in rice, namely, phoenix (pho), degenerative palea (dep), and abnormal floral organs (afo). Genetic analysis of them indicated that the stable pseudovivipary mutant pho was a double mutant containing both a Mendelian mutation in DEP and a non-Mendelian mutation in AFO. Further map-based cloning and microarray analysis revealed that dep mutant was caused by a genetic alteration in OsMADS15 while afo was caused by an epigenetic mutation in OsMADS1. Thus, OsMADS1 and OsMADS15 are both required to ensure sexual reproduction in rice and mutations of them lead to the switch of reproductive habit from sexual to asexual in rice. For the first time, our results reveal two regulators for sexual and asexual reproduction modes in flowering plants. In addition, our findings also make it possible to manipulate the reproductive strategy of plants, at least in rice

The Controversy Surrounding The Man Who Would Be Queen: A Case History of the Politics of Science, Identity, and Sex in the Internet Age

In 2003, psychology professor and sex researcher J. Michael Bailey published a book entitled The Man Who Would Be Queen: The Science of Gender-Bending and Transsexualism. The book’s portrayal of male-to-female (MTF) transsexualism, based on a theory developed by sexologist Ray Blanchard, outraged some transgender activists. They believed the book to be typical of much of the biomedical literature on transsexuality—oppressive in both tone and claims, insulting to their senses of self, and damaging to their public identities. Some saw the book as especially dangerous because it claimed to be based on rigorous science, was published by an imprint of the National Academy of Sciences, and argued that MTF sex changes are motivated primarily by erotic interests and not by the problem of having the gender identity common to one sex in the body of the other. Dissatisfied with the option of merely criticizing the book, a small number of transwomen (particularly Lynn Conway, Andrea James, and Deirdre McCloskey) worked to try to ruin Bailey. Using published and unpublished sources as well as original interviews, this essay traces the history of the backlash against Bailey and his book. It also provides a thorough exegesis of the book’s treatment of transsexuality and includes a comprehensive investigation of the merit of the charges made against Bailey that he had behaved unethically, immorally, and illegally in the production of his book. The essay closes with an epilogue that explores what has happened since 2003 to the central ideas and major players in the controversy