No abstract

Light regulation of Fed-1 mRNA abundance in the leaves of green plants is primarily a post-transcriptional process. Previously, we have shown that the Fed-1 mRNA light response requires an open reading frame, indicating that the light regulation of the mRNA depends on its concurrent translation. We now show that light-induced increases in Fed-1 mRNA abundance are associated with increases in polyribosome association that require both a functional AUG and a normal Fed-1 translational start context. We also present evidence that light regulation of Fed-1 mRNA levels requires more than efficient translation per se. Substitution of the efficiently translated tobacco mosaic virus Omega 5' untranslated region resulted in a loss of Fed-1 light regulation. In addition, we identified a CAT T repeat element located near the 5' terminus of the Fed-1 5' untranslated region that is essential for light regulation. We introduced two different mutations in the CAT T repeat element, but only one of these substitutions blocked the normal light effect on polyribosome association, whereas both altered dark-induced Fed-1 mRNA disappearance. The element may thus be important for Fed-1 mRNA stability rather than polyribosome loading. We propose a model in which Fed-1 mRNA is relatively stable when it is associated with polyribosomes in illuminated plants but in darkness is not polyribosome associated and is thus rapidly degraded by a process involving the CAT T repeat element.

Research on policy reinvention tends to focus on whether policies become more or less comprehensive over time while neglecting to explain copying policy language verbatim. We argue that the extent to which lawmakers reinvent policy depends on the resources available to them. Lawmakers serving in more professional state legislatures have greater capacity to reinvent policies. In contrast, lawmakers serving in less professional settings are more likely to copy policy language. As evidence, we gather bill texts of 12 policies that diffused across the 50 states between 1982 and 2014. Using cosine similarity scores to measure language copying, we find that less professional legislatures copy more text from previous adopters, and that the likeliest culprit is a lack of funding for staff assistance. The findings have implications for states' ability to amend policies to suit their own citizens' needs.

Ferredoxin-1 (Fed-1) mRNA contains an internal light response element (iLRE) that destabilizes mRNA when light-grown plants are placed in darkness. mRNAs containing this element dissociate from polyribosomes in the leaves of transgenic tobacco (Nicotiana tabacum) plants transferred to the dark for 2 d. Here, we report in vivo labeling experiments with a chloramphenicol acetyl transferase mRNA fused to the Fed-1 iLRE. Our data indicate that the Fed-1 iLRE mediates a rapid decline in translational efficiency and that iLRE-containing mRNAs dissociate from polyribosomes within 20 min after plants are transferred to darkness. Both events occur before the decline in mRNA abundance, and polyribosome association is rapidly reversible if plants are re-illuminated. These observations support a model in which Fed-1 mRNA in illuminated leaves is stabilized by its association with polyribosomes, and/or by translation. In darkness a large portion of the mRNA dissociates from polyribosomes and is subsequently degraded. We also show that a significant portion of total tobacco leaf mRNA is shifted from polyribosomal to non-polyribosomal fractions after 20 min in the dark, indicating that translation of other mRNAs is also rapidly down-regulated in response to darkness. This class includes some, but not all, cytoplasmic mRNAs encoding proteins involved in photosynthesis.

Light regulation of Fed-1 mRNA abundance in the leaves of green plants is primarily a post-transcriptional process. Previously, we have shown that the Fed-1 mRNA light response requires an open reading frame, indicating that the light regulation of the mRNA depends on its concurrent translation. We now show that light-induced increases in Fed-1 mRNA abundance are associated with increases in polyribosome association that require both a functional AUG and a normal Fed-1 translational start context. We also present evidence that light regulation of Fed-1 mRNA levels requires more than efficient translation per se. Substitution of the efficiently translated tobacco mosaic virus Omega 5' untranslated region resulted in a loss of Fed-1 light regulation. In addition, we identified a CAT T repeat element located near the 5' terminus of the Fed-1 5' untranslated region that is essential for light regulation. We introduced two different mutations in the CAT T repeat element, but only one of these substitutions blocked the normal light effect on polyribosome association, whereas both altered dark-induced Fed-1 mRNA disappearance. The element may thus be important for Fed-1 mRNA stability rather than polyribosome loading. We propose a model in which Fed-1 mRNA is relatively stable when it is associated with polyribosomes in illuminated plants but in darkness is not polyribosome associated and is thus rapidly degraded by a process involving the CAT T repeat element.

If politicians in the United States were paid better, would more middle- and working-class people become politicians? Reformers often argue that the low salaries paid in state and local governments make holding office economically infeasible for lower-income citizens and contribute to the enduring numerical under-representation of the working class in our political institutions. Of course, raising politicians’ salaries could also make political office more attractive to affluent professionals, increasing competition for office and ultimately discouraging lower-income citizens from running and winning. In this article, we test these hypotheses using data on the salaries and economic backgrounds of state legislators. Contrary to the notion that paying politicians more promotes economic diversity, we find that the descriptive representation of the working class is the same or worse in states that pay legislators higher salaries. These findings have important implications for research on descriptive representation, political compensation, and political inequality.

Members of historically underrepresented groups—women, African Americans, Latinos, and workers—are serving in American legislatures in increasing numbers. However, legislators wield substantially greater power in the lawmaking process when they hold leadership positions. Incorporation of these groups into leadership positions could indicate fuller political representation, but scholars to date have not assessed how well these groups are represented in leadership. We analyze original data describing the backgrounds of approximately 2,200 leaders in 30 states between 2003 and 2014. The data show that, on average across states, members of these groups are as well represented in state legislative leadership positions as they are in rank-and-file membership, but there is substantial variation across states and across parties. We then ask what factors might explain this variation and explore institutional characteristics, like the number of leadership positions or leader selection methods. The results show that legislative chambers with a higher number of leadership posts tend to have more women in leadership, and that selection through elections is associated with decreased African American presence in leadership. The findings have implications for minority incorporation and influence in American politics.

Tumor spheroids of HT-29 human colon adenocarcinoma and A375 melanoma were established to investigate the uptake and clearance kinetics of TNT-1, a monoclonal antibody that targets necrotic cells of tumors. Our data reveal that there was rapid uptake of TNT-1 and its F(ab')2 fragment in both spheroid models, whereas an antibody of irrelevant specificity, Lym-1, and its F(ab')2 fragment bound poorly to the spheroids. Unlike previously reported monoclonal antibodies to tumor cell-surface antigens, TNT-1 showed 1) a linear uptake that increased over time without saturation in tumor spheroids and 2) an unexpected uptake by a subpopulation of cells in the viable outer rim of the spheroids. These preclinical studies provide important information concerning the therapeutic potential of TNT monoclonal antibodies for the treatment of cancer and micrometastases.