It is critical for spring wheat (Triticum aestivum L.) production in the semi-arid Loess Plateau to understand the impact of nitrogen (N) fertilizer on changes in N metabolism, photosynthetic parameters, and their relationship with grain yield and quality. The photosynthetic capacity of flag leaves, dry matter accumulation, and N metabolite enzyme activities from anthesis to maturity were studied on a long-term fertilization trial under different N rates [0 kg ha?1(N1), 52.5 kg ha?1 (N2), 105 kg ha?1 (N3), 157.5 kg ha?1 (N4), and 210 kg ha?1 (N5)]. It was observed that N3 produced optimum total dry matter (5407 kg ha?1), 1000 grain weight (39.7 g), grain yield (2.64 t ha?1), and protein content (13.97%). Our results showed that N fertilization significantly increased photosynthetic parameters and N metabolite enzymes at all growth stages. Nitrogen harvest index, partial productivity factor, agronomic recovery efficiency, and nitrogen agronomic efficiency were decreased with increased N. Higher N rates (N3–N5) maintained higher photosynthetic capacity and dry matter accumulation and lower intercellular CO2 content. The N supply influenced NUE by improving photosynthetic properties. The N3 produced highest chlorophyll content, photosynthetic rate, stomatal conductance and transpiration rate, grain yield, grain protein, dry matter, grains weight, and N metabolite enzyme activities compared to the other rates (N1, N2, N4, and N5). Therefore, increasing N rates beyond the optimum quantity only promotes vegetative development and results in lower yields.
Antigen testing is now recognized as the method of choice for detection of Wuchereria bancrofti infections. Unlike tests that detect microfilariae, antigen tests can be performed with blood collected during the day or night. However, existing enzyme-linked immunosorbent assay (ELISA) tests for filarial antigenemia are difficult to perform in the field, and this has limited their use in endemic countries. In this article, Gary Weil, Patrick Lammie and Niggi Weiss review their experience with a new rapid-format filarial antigen test. They found that the ICT card test was very easy to perform and that it was comparable with ELISA for the detection of filarial antigen in sera from people with microfilaremia. The introduction now of an antigen test suitable for use in the field is especially timely, in that it may facilitate implementation of new strategies proposed by the World Health Organization for control and elimination of lymphatic filariasis. 相似文献
A radioimmunoassay for a new anticancer drug, bruceantin, has been developed using [3H]acetylbruceantin and antibody induced by immunizing rabbits with succinylbruceantin-bovine serum albumin conjugates. [3H]Acetylbruceantin was synthesized by reacting bruceantin with [3H]acetyl anhydride. The assay is simple and reproducible. The standard curve was linear on a logit-log plot, and the lower limit of sensitivity of the assay was 1 ng/ml. Using this assay, drug levels were easily determined in tissues of experimental animals following bruceantin administration. The assay procedure does not require sample extraction for plasma, urine, and bile. Bruceantin in other tissues can be extracted quantitatively with ethanol before being measured by the radioimmunoassay. 相似文献
Parasites of the Apicomplexa phylum, such as Plasmodium spp. and Toxoplasma gondii, undergo complex life cycles involving multiple stages with distinct biology and morphologies. Post‐translational modifications (PTMs), such as phosphorylation, acetylation and glycosylation, regulate numerous cellular processes, playing a role in every aspect of cell biology. PTMs can occur on proteins at any time in their lifespan and through alterations of target protein activity, localization, protein–protein interactions, among other functions, dramatically increase proteome diversity and complexity. In addition, PTMs can be induced or removed on changes in cellular environment and state. Thus, PTMs are likely to be key regulators of developmental transitions, biology and pathogenesis of apicomplexan parasites. In this review we examine the roles of PTMs in both parasite‐specific and conserved eukaryotic processes, and the potential crosstalk between PTMs, that together regulate the intricate lives of these protozoa. 相似文献
Helicobacter pylori infects half of the world's population, and strains that encode the cag type IV secretion system for injection of the oncoprotein CagA into host gastric epithelial cells are associated with elevated levels of cancer. CagA translocation into host cells is dependent on interactions between the H. pylori adhesin protein HopQ and human CEACAMs. Here, we present high‐resolution structures of several HopQ‐CEACAM complexes and CEACAMs in their monomeric and dimeric forms establishing that HopQ uses a coupled folding and binding mechanism to engage the canonical CEACAM dimerization interface for CEACAM recognition. By combining mutagenesis with biophysical and functional analyses, we show that the modes of CEACAM recognition by HopQ and CEACAMs themselves are starkly different. Our data describe precise molecular mechanisms by which microbes exploit host CEACAMs for infection and enable future development of novel oncoprotein translocation inhibitors and H. pylori‐specific antimicrobial agents. 相似文献
Between 1989 and 2003, Liberia experienced a brutal civil war characterized by ethnic killings, sexual violence and the use of child soldiers. Five years after the war ended, half the population of Liberia was under 18 years old. Understanding the needs of these youth is thus essential to the recovery of the nation. This study focuses on the narratives of two female adolescents, selected from 75 in-depth individual interviews with post-conflict Liberian youth conducted in 2012. A narrative analysis approach was employed to examine each interview for multiple layers of meaning. The aim of the study was to elucidate factors that may enable post-conflict youth to reclaim a sense of agency and return to normal developmental tasks. The study explores the ways in which these youth navigate complicated power dynamics in the post-conflict setting and how gender impacts their experiences of their own agency and capability. The dynamics between the participants and the interviewer are explored to further illustrate how power dynamics manifest. These narratives support the involvement of youth in projects that help others as an avenue for promoting agency and resilience for themselves. 相似文献