University of Guelph

About: University of Guelph is a education organization based out in Guelph, Ontario, Canada. It is known for research contribution in the topics: Population & Gene. The organization has 26542 authors who have published 50553 publications receiving 1715255 citations. The organization is also known as: U of G & Guelph University.

Protein Phosphorylation in Amyloplasts Regulates Starch Branching Enzyme Activity and Protein–Protein Interactions

Abstract: Protein phosphorylation in amyloplasts and chloroplasts of Triticum aestivum (wheat) was investigated after the incubation of intact plastids with γ-32P-ATP. Among the soluble phosphoproteins detected in plastids, three forms of starch branching enzyme (SBE) were phosphorylated in amyloplasts (SBEI, SBEIIa, and SBEIIb), and both forms of SBE in chloroplasts (SBEI and SBEIIa) were shown to be phosphorylated after sequencing of the immunoprecipitated 32P-labeled phosphoproteins using quadrupole-orthogonal acceleration time of flight mass spectrometry. Phosphoamino acid analysis of the phosphorylated SBE forms indicated that the proteins are all phosphorylated on Ser residues. Analysis of starch granule–associated phosphoproteins after incubation of intact amyloplasts with γ-32P-ATP indicated that the granule-associated forms of SBEII and two granule-associated forms of starch synthase (SS) are phosphorylated, including SSIIa. Measurement of SBE activity in amyloplasts and chloroplasts showed that phosphorylation activated SBEIIa (and SBEIIb in amyloplasts), whereas dephosphorylation using alkaline phosphatase reduced the catalytic activity of both enzymes. Phosphorylation and dephosphorylation had no effect on the measurable activity of SBEI in amyloplasts and chloroplasts, and the activities of both granule-bound forms of SBEII in amyloplasts were unaffected by dephosphorylation. Immunoprecipitation experiments using peptide-specific anti-SBE antibodies showed that SBEIIb and starch phosphorylase each coimmunoprecipitated with SBEI in a phosphorylation-dependent manner, suggesting that these enzymes may form protein complexes within the amyloplast in vivo. Conversely, dephosphorylation of immunoprecipitated protein complex led to its disassembly. This article reports direct evidence that enzymes of starch metabolism (amylopectin synthesis) are regulated by protein phosphorylation and indicate a wider role for protein phosphorylation and protein–protein interactions in the control of starch anabolism and catabolism.

Imitation dynamics predict vaccinating behaviour

Abstract: There exists an interplay between vaccine coverage, disease prevalence and the vaccinating behaviour of individuals. Moreover, because of herd immunity, there is also a strategic interaction between individuals when they are deciding whether or not to vaccinate, because the probability that an individual becomes infected depends upon how many other individuals are vaccinated. To understand this potentially complex interplay, a game dynamic model is developed in which individuals adopt strategies according to an imitation dynamic (a learning process), and base vaccination decisions on disease prevalence and perceived risks of vaccines and disease. The model predicts that oscillations in vaccine uptake are more likely in populations where individuals imitate others more readily or where vaccinating behaviour is more sensitive to changes in disease prevalence. Oscillations are also more likely when the perceived risk of vaccines is high. The model reproduces salient features of the time evolution of vaccine uptake and disease prevalence during the whole-cell pertussis vaccine scare in England and Wales during the 1970s. This suggests that using game theoretical models to predict, and even manage, the population dynamics of vaccinating behaviour may be feasible.

Flies and flowers: taxonomic diversity of anthophiles and pollinators

Abstract: The Diptera are the second most important order among flower-visiting (anthophilous) and flower-pollinating insects worldwide. Their taxonomic diversity ranges from Nematocera to Brachycera, including most families within the suborders. Especially important are Syrphidae, Bombyliidae, and Muscoidea. Other families, especially of small flies, are less appreciated and often overlooked for their associations with flowers. We have compiled records of their flower visitations to show that they may be more prevalent than usually thought. Our knowledge of anthophilous Diptera needs to be enhanced by future research concerning (i) the significance of nocturnal Nematocera and acalypterate muscoids as pollinators, (ii) the extent to which the relatively ineffective pollen-carrying ability of some taxa can be compensated by the abundance of individuals, and (iii) the role of Diptera as pollinators of the first flowering plants (Angiospermae) by using phylogenetic and palaeontological evidence. Specializations in floral relationships involve the morphology of Diptera, especially of their mouthparts, nutritional requirements, and behaviour, as well as concomitant floral attributes. The South African flora has the most highly specialized relations with dipterous pollinators, but in arctic and alpine generalist fly–flower relations are important in pollination and fly nutrition.

Integrating food web diversity, structure and stability

Abstract: Given the unprecedented rate of species extinctions facing the planet, understanding the causes and consequences of species diversity in ecosystems is of paramount importance. Ecologists have investigated both the influence of environmental variables on species diversity and the influence of species diversity on ecosystem function and stability. These investigations have largely been carried out without taking into account the overarching stabilizing structures of food webs that arise from evolutionary and successional processes and that are maintained through species interactions. Here, we argue that the same large-scale structures that have been purported to convey stability to food webs can also help to understand both the distribution of species diversity in nature and the relationship between species diversity and food web stability. Specifically, the allocation of species diversity to slow energy channels within food webs results in the skewed distribution of interactions strengths that has been shown to confer stability to complex food webs. We end by discussing the processes that might generate and maintain the structured, stable and diverse food webs observed in nature.

Direct and Mediated Influences of Home Literacy and Literacy Interest on Prereaders' Oral Vocabulary and Early Written Language Skill.

Abstract: Home literacy (reports of children's literacy activities at home and parents' storybook title recognition) and literacy interest (children's reports of feelings about literacy activities) were identified as 2 independent sources of literacy experience among 92 kindergarten prereaders. Together, they accounted for significant variance in oral vocabulary (21%) and on a letter-name and letter-sound measure of early written language (18%). Entering phonological awareness first in hierarchical regression eliminated home literacy's unique contribution to written language but not to vocabulary, indicating that home literacy is directly related to vocabulary but that phonological awareness mediates its relationship with written language. Literacy interest was unrelated to phonological awareness and accounted for unique variance in written language only. Discussion focused on print exposure versus explicit print-sound instruction in home literacy activities.