Root nodule organogenesis : molecular characterization of the zonation central tissue

Legume plants form root nodules by interacting with the soil bacterium, Rhizobium. In these nodules bacteria are able to convert atmospheric nitrogen into ammonia which is used by the host plants as nitrogen source. Therefore symbiotic nitrogen fixation in root nodules is of great importance for agriculture.Root nodule formation involves several developmental stages, namely are: induction of cell divisions in the root cortex, formation of nodule primordium and meristern, and finally differentiation of the meristern into nodule tissues. A mature nodule is composed of a central tissue where bacteria are hosted and several peripheral tissues. The induction of nodule specific genes of the host plants as well as the bacteria in a temporally and spatially controlled manner regulates the development of root nodules. The aim of the research described in this thesis was to investigate mechanisms that control nodule development. For this purpose genes of interest have been isolated and their expression was studied by means of the in situ hybridization technique.In chapter 2 a general introduction summarizing what we know about nodule development at present is given with an emphasis on gene expression and exchange of signals between the host plant and the rhizobia.Early studies of Allen et al. (1953) and more recently Hirsch et al. (1989) on polar auxin transport inhibitors (ATIs) provided evidences that exogenously applied ATIs cause the formation of nodule-like structures on several legume plants. These studies showed that auxin plays a major role in nodule development. Since certain flavonoids, e.g. quercetin, are endogenous ATIs, we studied the expression of chalcone synthase (CHS) genes, which encode a key enzyme in flavonoid biosynthesis, in situ during nodule development. The results are presented in chapter 3.To study gene expression during nodule development, two nodulin genes, ENOD40 and NOD6, were isolated and their expression during nodule development was studied by in situ hybridization. In chapter 4, a cDNA clone of the early nodulin gene ENOD40 was characterized. The pattern of expression of ENOD40 during soybean and pea nodule development suggested that it may play an important role in nodule formation. In chapter 5, the isolation of the late nodulin gene NOD6 was described and its expression pattern was compared with that of other nodulin genes.In chapters 6 and 7, the expression patterns in pea nodules of several bacterial genes were studied. These genes are nif A and nif H , and rop A The expression pattern of nif A and nif H in nodules is described in chapter 6. The expression of the rop A gene, which encodes a bacterial outer membrane protein, is described in chapter 7. The expression pattern of rop A in nodules is compared with that of nif H . The rop A protein was localized at a ultrastructural level by immunocytochemistry.In chapter 8, the results reported in this thesis are discussed with respect to the mechanisms that controls the induction of cortical cell divisions, meristern formation and formation of zones in the nodule central tissue

Robust variance-constrained H∞ control for stochastic systems with multiplicative noises

This is the post print version of the article. The official published version can be obtained from the link below - Copyright 2007 Elsevier Ltd.In this paper, the robust variance-constrained H∞ control problem is considered for uncertain stochastic systems with multiplicative noises. The norm-bounded parametric uncertainties enter into both the system and output matrices. The purpose of the problem is to design a state feedback controller such that, for all admissible parameter uncertainties, (1) the closed-loop system is exponentially mean-square quadratically stable; (2) the individual steady-state variance satisfies given upper bound constraints; and (3) the prescribed noise attenuation level is guaranteed in an H∞ sense with respect to the additive noise disturbances. A general framework is established to solve the addressed multiobjective problem by using a linear matrix inequality (LMI) approach, where the required stability, the H∞ characterization and variance constraints are all easily enforced. Within such a framework, two additional optimization problems are formulated: one is to optimize the H∞ performance, and the other is to minimize the weighted sum of the system state variances. A numerical example is provided to illustrate the effectiveness of the proposed design algorithm.This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grant GR/S27658/01, the Nuffield Foundation of the UK under Grant NAL/00630/G, and the Alexander von Humboldt Foundation of Germany

Sumoylation of LAP1 is involved in the HDAC4-mediated repression of COX-2 transcription

CEBPB, one of the CEBP family members, is a crucial regulator of gene expression during innate immunity, inflammatory responses and adipogenesis. In this study, the EGF-induced increase of CEBPB mRNA is shown to be coincident with the decrease of COX-2 mRNA. We identified that all of the individual CEBPB isoforms, LAP1, LAP2 and LIP, attenuate EGF-induced COX-2 promoter activity. Although increased sumoylation of both LAP1 and LAP2 is observed during the lagging stage of EGF treatment, only the sumoylated LAP1, but not the sumoylated LAP2, is responsible for COX-2 gene repression. In addition, EGF treatment can regulate the nucleocytoplasmic redistribution of HDAC4 and SUMO1. We further demonstrated by loss-of- and gain-of-function approaches that HDAC4 can be a negative regulator while inactivating COX-2 transcription. The sumoylation mutant LAP1, LAP1K174A, exhibits an attenuated ability to interact with HDAC4, and increased COX-2 promoter activity. Furthermore, the in vivo DNA binding assay demonstrated that LAP1K174A and CEBPDK120A, sumoylation-defective CEBPD mutants, attenuate the binding of HDAC4 on the COX-2 promoter. In light of the above, our data suggest that the suCEBPD and suLAP1 are involved in the repression of COX-2 transcription through the recruitment of HDAC4

Evolution of genomes, host shifts and the geographic spread of SARS-CoV and related coronaviruses

Severe acute respiratory syndrome (SARS) is a novel human illness caused by a previously unrecognized coronavirus (CoV) termed SARS-CoV. There are conflicting reports on the animal reservoir of SARS-CoV. Many of the groups that argue carnivores are the original reservoir of SARS-CoV use a phylogeny to support their argument. However, the phylogenies in these studies often lack outgroup and rooting criteria necessary to determine the origins of SARS-CoV. Recently, SARS-CoV has been isolated from various species of Chiroptera from China (e.g., Rhinolophus sinicus) thus leading to reconsideration of the original reservoir of SARS-CoV. We evaluated the hypothesis that SARS-CoV isolated from Chiroptera are the original zoonotic source for SARS-CoV by sampling SARS-CoV and non-SARS-CoV from diverse hosts including Chiroptera, carnivores, artiodactyls and humans. Regardless of alignment parameters, optimality criteria, or isolate sampling, the resulting phylogenies clearly show that the SARS-CoV was transmitted to small carnivores well after the epidemic of SARS in humans that began in late 2002. The SARS-CoV isolates from small carnivores in Shenzhen markets form a terminal clade that emerged recently from within the radiation of human SARS-CoV. There is evidence of subsequent exchange of SARS-CoV between humans and carnivores. In addition SARS-CoV was transmitted independently from humans to farmed pigs (Sus scrofa). The position of SARS-CoV isolates from Chiroptera are basal to the SARS-CoV clade isolated from humans and carnivores. Although sequence data indicate that Chiroptera are a good candidate for the original reservoir of SARS-CoV, the structural biology of the spike protein of SARS-CoV isolated from Chiroptera suggests that these viruses are not able to interact with the human variant of the receptor of SARS-CoV, angiotensin-converting enzyme 2 (ACE2). In SARS-CoV study, both visually and statistically, labile genomic fragments and, putative key mutations of the spike protein that may be associated with host shifts. We display host shifts and candidate mutations on trees projected in virtual globes depicting the spread of SARS-CoV. These results suggest that more sampling of coronaviruses from diverse hosts, especially Chiroptera, carnivores and primates, will be required to understand the genomic and biochemical evolution of coronaviruses, including SARS-CoV.Fil: Janies, Daniel. Ohio State University; Estados UnidosFil: Habib, Farhat. Ohio State University; Estados UnidosFil: Alexandrov, Boyan. Ohio State University; Estados UnidosFil: Hill, Andrew. University of Colorado; Estados UnidosFil: Pol, Diego. Museo Paleontológico Egidio Feruglio; Argentina. Ohio State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Moving granular-bed filter development program - option 1 - component test facilities

The Westinghouse Science & Technology Center has proposed a novel moving granular bed filter concept, the Standleg Moving Granular Bed Filter (SMGBF). The SMGBF has inherent advantages over the current state-of-the-art moving granular bed filter technology and is potentially competitive with ceramic barrier filters. The SMGBF system combines several unique features that make it highly effective for use in advanced coal-fueled power plants, such as pressurized fluidized-bed combustion (PFBC), and integrated coal-gasification combined cycles (IGCC). The SMGBF is being developed in a phased program having an initial Base Contract period followed by optional periods. The Base Contract period was successfully completed and previously documented by Westinghouse. The Option 1 period, {open_quote}Component Test Facilities{close_quotes}, has also been completed and its results are reported in this document. The objective of the Option 1 program was to optimize the performance of the SMGBF system through component testing focused on the major technology issues. The SMGBF has been shown to be a viable technology in both cold flow simulations and high-temperature, high-pressure testing, and conditions to lead to best performance levels have been identified. Several development activities remain to be complete before the SMGBF can achieve commercial readiness

Understorey plant community and light availability in conifer plantations and natural hardwood forests in Taiwan

Questions: What are the effects of replacing mixed species natural forests with Cryptomeria japonica plantations on understorey plant functional and species diversity? What is the role of the understorey light environment in determining understorey diversity and community in the two types of forest? Location: Subtropical northeast Taiwan. Methods: We examined light environments using hemispherical photography, and diversity and composition of understorey plants of a 35‐yr C. japonica plantation and an adjacent natural hardwood forest. Results: Understorey plant species richness was similar in the two forests, but the communities were different; only 18 of the 91 recorded understorey plant species occurred in both forests. Relative abundance of plants among different functional groups differed between the two forests. Relative numbers of shade‐tolerant and shade‐intolerant seedling individuals were also different between the two forest types with only one shade‐intolerant seedling in the plantation compared to 23 seedlings belonging to two species in the natural forest. In the natural forest 11 species of tree seedling were found, while in the plantation only five were found, and the seedling density was only one third of that in the natural forest. Across plots in both forests, understorey plant richness and diversity were negatively correlated with direct sunlight but not indirect sunlight, possibly because direct light plays a more important role in understorey plant growth. Conclusions: We report lower species and functional diversity and higher light availability in a natural hardwood forest than an adjacent 30‐yr C. japonica plantation, possibly due to the increased dominance of shade‐intolerant species associated with higher light availability. To maintain plant diversity, management efforts must be made to prevent localized losses of shade‐adapted understorey plants

A connection between stress and development in the multicelular prokaryote Streptomyces coelicolor

Morphological changes leading to aerial mycelium formation and sporulation in the mycelial bacterium Streptomyces coelicolor rely on establishing distinct patterns of gene expression in separate regions of the colony. sH was identified previously as one of three paralogous sigma factors associated with stress responses in S. coelicolor. Here, we show that sigH and the upstream gene prsH (encoding a putative antisigma factor of sH) form an operon transcribed from two developmentally regulated promoters, sigHp1 and sigHp2. While sigHp1 activity is confined to the early phase of growth, transcription of sigHp2 is dramatically induced at the time of aerial hyphae formation. Localization of sigHp2 activity using a transcriptional fusion to the green fluorescent protein reporter gene (sigHp2–egfp) showed that sigHp2 transcription is spatially restricted to sporulating aerial hyphae in wild-type S. coelicolor. However, analysis of mutants unable to form aerial hyphae (bld mutants) showed that sigHp2 transcription and sH protein levels are dramatically upregulated in a bldD mutant, and that the sigHp2–egfp fusion was expressed ectopically in the substrate mycelium in the bldD background. Finally, a protein possessing sigHp2 promoter-binding activity was purified to homogeneity from crude mycelial extracts of S. coelicolor and shown to be BldD. The BldD binding site in the sigHp2 promoter was defined by DNase I footprinting. These data show that expression of sH is subject to temporal and spatial regulation during colony development, that this tissue-specific regulation is mediated directly by the developmental transcription factor BldD and suggest that stress and developmental programmes may be intimately connected in Streptomyces morphogenesis

Hypothalamic AMP-Activated Protein Kinase Regulates Glucose Production

OBJECTIVE—The fuel sensor AMP-activated protein kinase (AMPK) in the hypothalamus regulates energy homeostasis by sensing nutritional and hormonal signals. However, the role of hypothalamic AMPK in glucose production regulation remains to be elucidated. We hypothesize that bidirectional changes in hypothalamic AMPK activity alter glucose production. RESEARCH DESIGN AND METHODS—To introduce bidirec-tional changes in hypothalamic AMPK activity in vivo, we first knocked down hypothalamic AMPK activity in male Sprague-Dawley rats by either injecting an adenovirus expressing the dominant-negative form of AMPK (Ad-DN AMPK2 [D157A]) or infusing AMPK inhibitor compound C directly into the medio-basal hypothalamus. Next, we independently activated hypotha-lamic AMPK by delivering either an adenovirus expressing the constitutive active form of AMPK (Ad-CA AMPK1312 [T172D]

Natural and anthropogenic climate change

This final report provides a broad overview of program accomplishments. Brief descriptions are provided for accomplishments with respect to intercomparisions and improvements in general circulation models, analysis of climatic data and climate model statistics, and accomplishments in the China Meteorology coordination