Australian National University

About: Australian National University is a education organization based out in Canberra, Australian Capital Territory, Australia. It is known for research contribution in the topics: Population & Galaxy. The organization has 34419 authors who have published 109261 publications receiving 4315448 citations. The organization is also known as: The Australian National University & ANU.

Nitrogen and Photosynthesis in the Flag Leaf of Wheat (Triticum aestivum L.)

Abstract: Wheat (Triticum aestivum L. cv Yecora 70) plants were grown with various concentrations of nitrate nitrogen available to the roots. Sampling of flag leaves began after they had reached full expansion and continued throughout senescence. Rates of gas exchange, ribulose-1,5-bisphosphate (RuP(2)) carboxylase activity, and the amounts of chlorophyll, soluble protein, nitrogen, and phosphorus were determined for each flag leaf. Rate of CO(2) assimilation was uniquely related to total leaf nitrogen irrespective of nutrient treatment, season, and leaf age. Assimilation rate increased with leaf nitrogen, but the slope of the relationship declined markedly when leaf nitrogen exceeded 125 millimoles nitrogen per square meter. Chlorophyll content and RuP(2) carboxylase activity were approximately proportional to leaf nitrogen content. As leaves aged, RuP(2) carboxylase activity and calculated Hill activity declined in parallel. With normal ambient partial pressure of CO(2), the intercellular partial pressure of CO(2) was always such that rate of assimilation appeared colimited by RuP(2) carboxylation and RuP(2) regeneration capacity.The initial slope of rate of CO(2) assimilation against intercellular partial pressure of CO(2) varied nonlinearly with carboxylase activity. It is suggested that this was due to a finite conductance to CO(2) diffusion in the wall and liquid phase which causes a drop in CO(2) partial pressure between the intercellular spaces and the site of carboxylation. A double reciprocal plot was used to obtain an estimate of the transfer conductance.

Phase III Randomized Comparison of Gemcitabine Versus Gemcitabine Plus Capecitabine in Patients With Advanced Pancreatic Cancer

Abstract: Purpose Both gemcitabine (GEM) and fluoropyrimidines are valuable treatment for advanced pancreatic cancer. This open-label study was designed to compare the overall survival (OS) of patients randomly assigned to GEM alone or GEM plus capecitabine (GEM-CAP). Patients and Methods Patients with previously untreated histologically or cytologically proven locally advanced or metastatic carcinoma of the pancreas with a performance status ≤ 2 were recruited. Patients were randomly assigned to GEM or GEM-CAP. The primary outcome measure was survival. Meta-analysis of published studies was also conducted. Results Between May 2002 and January 2005, 533 patients were randomly assigned to GEM (n = 266) and GEM-CAP (n = 267) arms. GEM-CAP significantly improved objective response rate (19.1% v 12.4%; P = .034) and progression-free survival (hazard ratio [HR], 0.78; 95% CI, 0.66 to 0.93; P = .004) and was associated with a trend toward improved OS (HR, 0.86; 95% CI, 0.72 to 1.02; P = .08) compared with GEM alone. This trend for OS benefit for GEM-CAP was consistent across different prognostic subgroups according to baseline stratification factors (stage and performance status) and remained after adjusting for these stratification factors (P = .077). Moreover, the meta-analysis of two additional studies involving 935 patients showed a significant survival benefit in favor of GEM-CAP (HR, 0.86; 95% CI, 0.75 to 0.98; P = .02) with no intertrial heterogeneity. Conclusion On the basis of our trial and the meta-analysis, GEM-CAP should be considered as one of the standard first-line options in locally advanced and metastatic pancreatic cancer.

Stomatal Behaviour and Environment

Abstract: Publisher Summary Stomata1 movement is a manifestation of strain in the epidermis, associated with change in the hydraulic pressure in the epidermal cells. This chapter discusses the role and behavior of stomata in the hydrology of the soil–plant–atmosphere system. Stomata operate in the light in such a way as to maintain positive turgor in the leaves, in the majority of crop plants and other species. The transient response of stomata to changes in environment which cause rapid changes in plant–water relations is quite dramatic. The nature of the stomatal response to change in water potential must involve the mechanical and hydraulic attributes of the stomatal apparatus. There is only a tenuous relationship between the potential of water in leaf tissue in bulk and the local potential of water to which an individual stoma responds in ways, which are also discussed. Thus the transient response of stomata to change in rate of evaporation may be a device which is designed to enhance the speed of the response to light.

Genome of the marsupial Monodelphis domestica reveals innovation in non-coding sequences

Abstract: We report a high-quality draft of the genome sequence of the grey, short-tailed opossum (Monodelphis domestica). As the first metatherian ('marsupial') species to be sequenced, the opossum provides a unique perspective on the organization and evolution of mammalian genomes. Distinctive features of the opossum chromosomes provide support for recent theories about genome evolution and function, including a strong influence of biased gene conversion on nucleotide sequence composition, and a relationship between chromosomal characteristics and X chromosome inactivation. Comparison of opossum and eutherian genomes also reveals a sharp difference in evolutionary innovation between protein-coding and non-coding functional elements. True innovation in protein-coding genes seems to be relatively rare, with lineage-specific differences being largely due to diversification and rapid turnover in gene families involved in environmental interactions. In contrast, about 20% of eutherian conserved non-coding elements (CNEs) are recent inventions that postdate the divergence of Eutheria and Metatheria. A substantial proportion of these eutherian-specific CNEs arose from sequence inserted by transposable elements, pointing to transposons as a major creative force in the evolution of mammalian gene regulation.

Moving beyond heterogeneity and process complexity: A new vision for watershed hydrology

Abstract: Field studies in watershed hydrology continue to characterize and catalogue the enormous heterogeneity and complexity of rainfall runoff processes in more and more watersheds, in different hydroclimatic regimes, and at different scales. Nevertheless, the ability to generalize these findings to ungauged regions remains out of reach. In spite of their apparent physical basis and complexity, the current generation of detailed models is process weak. Their representations of the internal states and process dynamics are still at odds with many experimental findings. In order to make continued progress in watershed hydrology and to bring greater coherence to the science, we need to move beyond the status quo of having to explicitly characterize or prescribe landscape heterogeneity in our (highly calibrated) models and in this way reproduce process complexity and instead explore the set of organizing principles that might underlie the heterogeneity and complexity. This commentary addresses a number of related new avenues for research in watershed science, including the use of comparative analysis, classification, optimality principles, and network theory, all with the intent of defining, understanding, and predicting watershed function and enunciating important watershed functional traits.