Isolation, molecular and biological properties of a lectin from rice embryo: relationship with wheat germ agglutinin properties

Rice lectin (Oryza sativa, var. Balilla 28) was purified from defatted embryos by aqueous acid extraction at pH 1.3 followed by ammonium sulfate precipitation between 2 and 4 M, affinity chromatography on agarose-p-aminophenyl-beta-D-N-acetylglucosamine, and gel filtration on AcA 54. The homogeneity of the lectin was checked by polyacrylamide gel electrophoresis, gel filtration, and immunodiffusion. The amino acid analysis revealed a high half-cystine content (9%) and a low aromatic and hydrophobic amino acid content. The lectin contained neither neutral carbohydrates nor amino sugars. The isoelectric point was estimated to be 8.1. The molecular weight of rice lectin was estimated to be 38,000. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions showed two polypeptides with Mr 19,000 and 15,000. The circular dichroism spectrum of rice lectin in far ultraviolet was characterized by a positive maximum at 228 nm and a negative band at 203 nm suggesting the presence of a beta-pleated sheet and the absence of alpha-helix. Rice lectin had no human blood group specificity and agglutinated rabbit erythrocytes more efficiently than erythrocytes from other animal species. Furthermore, agglutination was enhanced by trypsin treatment of erythrocytes. The erythroagglutinating activity was very high since the minimal concentration needed to agglutinate erythrocytes was 0.05 micrograms/ml. Although [methyl-3H]thymidine incorporation was stimulated in human lymphocytes, rice lectin could not be considered as a mitogenic lectin since it stimulated neither blast transformation nor lymphocyte proliferation. The saccharide specificity of rice lectin was related to N-acetylglucosamine and its oligomers: N,N',N"-triacetylchitotriose was the most powerful inhibitor. Furthermore, the N-acetylneuraminic acid was not a specific rice determinant. Finally, the double immunodiffusion method revealed a cross-reactivity between rice lectin and wheat germ agglutinin, indicating that these lectins were closely antigenically related. The analogies and differences between biological and immunological properties of rice lectin and wheat germ agglutinin are discussed and the possibility of their evolution from a common ancestor is put forward.     

Seed size,number and strategies in annual plants: a comparative functional analysis and synthesis

Background and AimsPlants depend fundamentally on establishment from seed. However, protocols in trait-based ecology currently estimate seed size but not seed number. This can be rectified. For annuals, seed number should simply be a positive function of vegetative biomass and a negative function of seed size.MethodsUsing published values of comparative seed number as the ‘gold standard’ and a large functional database, comparative seed yield and number per plant and per m² were predicted by multiple regression. Subsequently, ecological variation in each was explored for English and Spanish habitats, newly calculated C-S-R strategies and changed abundance in the British flora.Key ResultsAs predicted, comparative seed mass yield per plant was consistently a positive function of plant size and competitive ability, and largely independent of seed size. Regressions estimating comparative seed number included, additionally, seed size as a negative function. Relationships differed numerically between regions, habitats and C-S-R strategies. Moreover, some species differed in life history over their geographical range. Comparative seed yield per m² was positively correlated with FAO crop yield, and increasing British annuals produced numerous seeds. Nevertheless, predicted values must be viewed as comparative rather than absolute: they varied according to the ‘gold standard’ predictor used. Moreover, regressions estimating comparative seed yield per m² achieved low precision.ConclusionsFor the first time, estimates of comparative seed yield and number for >800 annuals and their predictor equations have been produced and the ecological importance of these regenerative traits has been illustrated. ‘Regenerative trait-based ecology’ remains in its infancy, with work needed on determinate vs. indeterminate flowering (‘bet-hedging’), C-S-R methodologies, phylogeny, comparative seed yield per m² and changing life history. Nevertheless, this has been a positive start and readers are invited to use estimates for >800 annuals, in the Supplementary data, to help advance ‘regenerative trait-based ecology’ to the next level.     

Brain Metabolism during Hallucination-Like Auditory Stimulation in Schizophrenia

Auditory verbal hallucinations (AVH) in schizophrenia are typically characterized by rich emotional content. Despite the prominent role of emotion in regulating normal perception, the neural interface between emotion-processing regions such as the amygdala and auditory regions involved in perception remains relatively unexplored in AVH. Here, we studied brain metabolism using FDG-PET in 9 remitted patients with schizophrenia that previously reported severe AVH during an acute psychotic episode and 8 matched healthy controls. Participants were scanned twice: (1) at rest and (2) during the perception of aversive auditory stimuli mimicking the content of AVH. Compared to controls, remitted patients showed an exaggerated response to the AVH-like stimuli in limbic and paralimbic regions, including the left amygdala. Furthermore, patients displayed abnormally strong connections between the amygdala and auditory regions of the cortex and thalamus, along with abnormally weak connections between the amygdala and medial prefrontal cortex. These results suggest that abnormal modulation of the auditory cortex by limbic-thalamic structures might be involved in the pathophysiology of AVH and may potentially account for the emotional features that characterize hallucinatory percepts in schizophrenia.     

Unraveling the Nexus: Exploring the Pathways to Combined Resource Use

In response to the unprecedented decline in global natural resource endowments, the so‐called nexus framework is gaining increasing influence on resource management practices. In this research, we approach the resource nexus through the concept of nexus pathways. Nexus pathways are configurations that resource flows follow along supply chains leading to the combined use of two or more resources. Three general types of pathways are identified: direct (on‐site use), dependent (one‐way supply chains), and interdependent (supply‐chain feedbacks). We quantify and compare each pathway by means of multiregional input‐output analysis and structural path analysis, and apply this approach to a comparative case study on the water‐energy nexus (WEN) in the United States and China. Interdependencies or feedbacks are generally thought to be relevant for the WEN, especially between water and energy sectors. Our economy‐wide analysis for both countries indicates, however, that feedbacks neither play an important role in the WEN nor substantially take place between water and energy sectors. The most important feedbacks contribute to less than 1% of total resource use, and these take place mostly between manufacturing sectors. Overall, the studied WEN is mostly driven by dependent pathways and, to a lesser degree, direct resource use. Comparative differences between the two countries are largely explained by differences in economic structure, technology, and resource endowments. Our findings call into question current research and policy focus and suggest greater attention to less complex, but more determining, pathways leading to absolute resource use.     

Multiple phosphorylation of rat liver 3-hydroxy 3-methylglutaryl coenzyme a reductase

Rat liver homogeneous ³²P-labeled hydroxy methylglutaryl coenzyme A reductase, was treated independently with CNBr and trypsin and the resulting [³²P]phosphopeptides were analyzed by disc gel electrophoresis. CNBr treatment produced only one ³²P-fragment of Mr 18,000. The time course of trypsin hydrolysis initially showed the appearance of some phosphopeptides, which were lately converted in two phosphopeptides of low Mr. These results provide direct support for the concept that hydroxy methyl glutaryl coenzyme A reductase kinase solubilized from microsomes phosphorylates only two sites or set of sites in the reductase molecule.     

Development of ten microsatellite markers from the keystone mistletoe <Emphasis Type="Italic">Tristerix corymbosus</Emphasis> (Loranthaceae) using 454 next generation sequencing and their applicability to population genetic structure studies

Tristerix corymbosus (Loranthaceae) is a keystone mistletoe from the South American temperate rainforests. As most mistletoes, T. corymbosus relies on biotic pollination and seed dispersal, which may cause population structure. For a better understanding of its ecology, we isolated and characterized ten polymorphic microsatellite loci for this species. We used 454 Next Generation Sequencing to build a microsatellite library from a high quality DNA sample. We tested 90 sequences from which we obtained ten polymorphic markers. In order to assess their variability, the novel markers were tested in 48 individuals from three locations of the Valdivian Coastal Reserve in Chile. We also estimated genetic differences between pairs of populations using the F_ST statistic. The mean number of alleles per locus in the 48 individuals studied was 7.1 (2–17 alleles per locus). The observed and expected heterozygosity ranged from 0.298 to 0.634 and from 0.310 to 0.881, respectively. There were genetic differences among the three populations assessed, according to the F_ST values (ranging from 0.048 to 0.100, all significant) and, the number of alleles per locus ranged from 3.9 to 5.1. These are the first microsatellite markers developed for T. corymbosus, and they arise as a powerful tool for studying population structure, genetic diversity and gene flow at the landscape scale, along its distribution.     

Interactive Visualization and Industrial Ecology: Applications,Challenges, and Opportunities

The emergence of increasingly complex data in industrial ecology (IE) has caused scholarly interest in interactive visualization (IV). IV allows users to interact with data, aiding in processing and interpreting complex datasets, processes, and simulations. Consequently, IV can help IE practitioners communicate the complexities of their methods and results, shed light on the underlying research assumptions, and enable more transparent monitoring of data quality and error. This can significantly increase the reach and impact of research, promote transparency, reproducibility, and open science, as well as improve the clarity and presentation of IE research. A review of current IV applications reveals that, while data exploration has received some attention among IE practitioners, IV applications in scientific communication are clearly lacking. With the help of a working example, we explore the value of IV, discuss its operationalization, and highlight challenges that the IE community must face during IV uptake. Such challenges include technical and knowledge limitations, limits on user interaction, and implementation strategies. With these challenges in mind, we outline key aspects needed to lift the IE field to the forefront of scientific communication in the coming years. Among these, we draft the basic principles of a “Hub for Interactive Visualization in Industrial Ecology” (HIVE), a point of encounter where IE practitioners could find an array of data visualization tools that are geared toward IE datasets. IV is here to stay, and its inceptive stage presents many opportunities to IE practitioners to shape its operationalization and benefit from early adoption.     

A Model of Chronic Nutrient Infusion in the Rat

Chronic exposure to excessive levels of nutrients is postulated to affect the function of several organs and tissues and to contribute to the development of the many complications associated with obesity and the metabolic syndrome, including type 2 diabetes. To study the mechanisms by which excessive levels of glucose and fatty acids affect the pancreatic beta-cell and the secretion of insulin, we have established a chronic nutrient infusion model in the rat. The procedure consists of catheterizing the right jugular vein and left carotid artery under general anesthesia; allowing a 7-day recuperation period; connecting the catheters to the pumps using a swivel and counterweight system that enables the animal to move freely in the cage; and infusing glucose and/or Intralipid (a soybean oil emulsion which generates a mixture of approximately 80% unsaturated/20% saturated fatty acids when infused with heparin) for 72 hr. This model offers several advantages, including the possibility to finely modulate the target levels of circulating glucose and fatty acids; the option to co-infuse pharmacological compounds; and the relatively short time frame as opposed to dietary models. It can be used to examine the mechanisms of nutrient-induced dysfunction in a variety of organs and to test the effectiveness of drugs in this context.     

Modification of the N-linked oligosaccharides in cell surface glycoproteins during chick embryo development. A using lectin affinity and a high resolution chromatography study

Important differences in asparagine-linked glycopeptides were observed in vitro cultured fibroblasts derived from chick embryo at different stages of development. Cells from 8-day and 16-day embryos were labeled metabolically with [3H]mannose. Cell surface glycopeptides obtained after mild trypsin treatment were extensively digested with pronase and then chromatographed on concanavalin-A-Sepharose and other immobilized lectins. The most important changes concerned the complex type chains. The ratio between triantennary plus tetraantennary and biantennary chains increased about 2.5-fold from the 8th to the 16th day of development. In the same way, complex chains with bisecting N-acetylglucosamine increased from 8-day to 16-day cells as shown by Phaseolus-vulgaris-erythroagglutinin--agarose chromatography. In 16-day cells, the majority of triantennary chains (60%) with alpha-linked mannose substituted at C2 and C6 positions and biantennary chains (50%) were shown to contain fucosyl (alpha 1----6)N-acetylglucosaminyl structure in the core region by their ability to bind to a lentil lectin affinity column. Similarly, in 8-day cells, triantennary chains (50%) were more fucosylated than biantennary chains (35%). Thus, complex structures exhibited an increased fucosylation of their invariable core from the 8th to the 16th day of development, except for fucosylated triantennary chains which were retained on Phaseolus vulgaris Leucoagglutin and on lentil lectin. These latter structures were present at the surface of 8-day cells and absent at the surface of 16-day cells. After chromatography on Bio-Gel P6 and treatment with endo-beta-N-acetylglucosaminidase H, the [3H]-mannose-labeled glycopeptides were separated by high resolution chromatography into glycopeptides with complex chains and glycopeptides with high-mannose chains. Analysis of the high-mannose oligosaccharides released after endo-beta-N-acetylglucosaminidase H treatment by chromatography on Bio-Gel P4 indicated that the same type of high-mannose chains were present at the surface of 8-day and 16-day cells. Quantification of mannose, galactose and sialic acid residues using gas liquid chromatography was consistent with a decrease of the relative amount of oligomannose chains and an increase of the relative amount of complex type chains in 16-day cells compared to 8-day cells. Thus N-linked oligosaccharides derived from cell surface glycoproteins undergo changes during embryo development resulting in greater complexity of carbohydrate chains.