Crystal structures of Fe2+ dioxygenase superoxo, alkylperoxo, and bound product intermediates

We report the structures of three intermediates in the O2 activation and insertion reactions of an extradiol ring-cleaving dioxygenase. A crystal of Fe2+-containing homoprotocatechuate 2,3-dioxygenase was soaked in the slow substrate 4-nitrocatechol in a low O2 atmosphere. The x-ray crystal structure shows that three different intermediates reside in different subunits of a single homotetrameric enzyme molecule. One of these is the key substrate-alkylperoxo-Fe2+ intermediate, which has been predicted, but not structurally characterized, in an oxygenase. The intermediates define the major chemical steps of the dioxygenase mechanism and point to a general mechanistic strategy for the diverse 2-His-1-carboxylate enzyme family.     

The future for fisheries

Formal analyses of long-term global marine fisheries prospects have yet to be performed, because fisheries research focuses on local, species-specific management issues. Extrapolation of present trends implies expansion of bottom fisheries into deeper waters, serious impact on biodiversity, and declining global catches, the last possibly aggravated by fuel cost increases. Examination of four scenarios, covering various societal development choices, suggests that the negative trends now besetting fisheries can be turned around, and their supporting ecosystems rebuilt, at least partly.     

Electron-induced oxygen desorption from the TiO2(011)-2x1 surface leads to self-organized vacancies

When low-energy electrons strike a titanium dioxide surface, they may cause the desorption of surface oxygen. Oxygen vacancies that result from irradiating a TiO2(011)-2x1 surface with electrons with an energy of 300 electron volts were analyzed by scanning tunneling microscopy. The cross section for desorbing oxygen from the pristine surface was found to be 9 (+/-6) x 10(-17) square centimeters, which means that the initial electronic excitation was converted into atomic motion with a probability near unity. Once an O vacancy had formed, the desorption cross sections for its nearest and next-nearest oxygen neighbors were reduced by factors of 100 and 10, respectively. This site-specific desorption probability resulted in one-dimensional arrays of oxygen vacancies.     

Stomatal patterning and differentiation by synergistic interactions of receptor kinases

Coordinated spacing and patterning of stomata allow efficient gas exchange between plants and the atmosphere. Here we report that three ERECTA (ER)-family leucine-rich repeat-receptor-like kinases (LRR-RLKs) together control stomatal patterning, with specific family members regulating the specification of stomatal stem cell fate and the differentiation of guard cells. Loss-of-function mutations in all three ER-family genes cause stomatal clustering. Genetic interactions with a known stomatal patterning mutant too many mouths (tmm) revealed stoichiometric epistasis and combination-specific neomorphism. Our findings suggest that the negative regulation of ER-family RLKs by TMM, which is an LRR receptor-like protein, is critical for proper stomatal differentiation.     

Hexameric structure and assembly of the interleukin-6/IL-6 alpha-receptor/gp130 complex

Interleukin-6 (IL-6) is an immunoregulatory cytokine that activates a cell-surface signaling assembly composed of IL-6, the IL-6 alpha-receptor (IL-6Ralpha), and the shared signaling receptor gp130. The 3.65 angstrom-resolution structure of the extracellular signaling complex reveals a hexameric, interlocking assembly mediated by a total of 10 symmetry-related, thermodynamically coupled interfaces. Assembly of the hexameric complex occurs sequentially: IL-6 is first engaged by IL-6Ralpha and then presented to gp130in the proper geometry to facilitate a cooperative transition into the high-affinity, signaling-competent hexamer. The quaternary structures of other IL-6/IL-12 family signaling complexes are likely constructed by means of a similar topological blueprint.     

European seasonal and annual temperature variability, trends, and extremes since 1500

Multiproxy reconstructions of monthly and seasonal surface temperature fields for Europe back to 1500 show that the late 20th- and early 21st-century European climate is very likely (>95% confidence level) warmer than that of any time during the past 500 years. This agrees with findings for the entire Northern Hemisphere. European winter average temperatures during the period 1500 to 1900 were reduced by approximately 0.5 degrees C (0.25 degrees C for annual mean temperatures) compared to the 20th century. Summer temperatures did not experience systematic century-scale cooling relative to present conditions. The coldest European winter was 1708/1709; 2003 was by far the hottest summer.     

Effectiveness of donor natural killer cell alloreactivity in mismatched hematopoietic transplants

T cells that accompany allogeneic hematopoietic grafts for treating leukemia enhance engraftment and mediate the graft-versus-leukemia effect. Unfortunately, alloreactive T cells also cause graft-versus-host disease (GVHD). T cell depletion prevents GVHD but increases the risk of graft rejection and leukemic relapse. In human transplants, we show that donor-versus-recipient natural killer (NK)-cell alloreactivity could eliminate leukemia relapse and graft rejection and protect patients against GVHD. In mice, the pretransplant infusion of alloreactive NK cells obviated the need for high-intensity conditioning and reduced GVHD. NK cell alloreactivity may thus provide a powerful tool for enhancing the efficacy and safety of allogeneic hematopoietic transplantation.     

Genetic characterization of an Italian Giant Reed (Arundo donax L.) clones collection: exploiting clonal selection

This study is the first report of combining ability and heterosis for important vitamins and antioxidant plant pigments in cauliflower. Five CMS lines were crossed with 8 male fertile lines in line × tester design to develop 40 hybrids. These hybrids along with parental lines were evaluated for different vitamins and anti-oxidant pigments to reveal extent of heterosis and genetic combining ability. The CMS line Ogu12A was good general combiner (gca effect) and Ogu16A was poor general combiner for most of the important traits under study. Most of the heterotic hybrid combinations were associated high specific combing ability (sca effect). However, gca effect was also important in developing quality heterotic hybrids. The proportions of $\sigma_{\text{gca}}^{ 2} /\sigma_{\text{sca}}^{2}$ were less than unity in all the cases indicating the role of non-additive gene action for most of the traits. Highest number of heterotic hybrids in positive direction was recorded for ascorbic acid content followed by anthocyanin content. The accumulated average heterosis of the 40 hybrids was in positive direction for ascorbic acid, anthocyanin and lycopene concentration whereas it was in negative direction for carotenoids and chlorophyll pigments. Very high heterosis for ascorbic acid, anthocyanin and carotenoids in cauliflower indicated the scope for development of F₁ hybrids with higher concentration of these vitamins and anti-oxidant pigments. It is possible to develop heterotic hybrids for different vitamins and anti-oxidant plant pigments through selection of parental lines based on desirable genetic combing ability.