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The evolutionary development of plant-feeding insects and their nutritional endosymbionts

Insect Science 2017年第6期24卷 910-928页

作者： Isabel H. Sk.dmore allison k. hansen Department of Entomology University of Illinois Urbana-Champaign Ilfinois USA

Herbivorous insects have evolved diverse mechanisms enabling them to feed on plants with suboptimal nutrient availability. Low nutrient availability negatively impacts insect herbivore development and fitness. To overcome this obstacle numerous insect lineages have evolved intimate associations with nutritional endosymbionts. This is especially true for insects that specialize on nitrogen-poor substrates, as these insects are highly dependent on intraceUular symbionts to provide nitrogen lack.ng in their insect host＇s diet. Emerging evidence in these systems suggest that the symbiont＇s and/or the insect＇s biosynthetic pathways are dynamically regulated throughout the insect＇s development to potentially cope with the insect＇s changing nutritional demands. In this review, we evaluate the evolutionary development of symbiotic insect cells （bacteriocytes） by comparing and contrasting genes and mechanisms involved in maintaining and regulating the nutritional symbiosis throughout insect development in a diversity of insect herbivore-endosymbiont associations. With new advances in genome sequencing and functional genomics, we eval- uate to what extent nutritional symbioses are shaped by （i） the regulation of symbiont titer, （ii） the regulation of insect symbiosis genes, and （iii） the regulation of symbiont genes. We discuss how important these mechanisms are for the biosynthesis of essential amino acids and vitamins across insect life stages in divergent insect-symbiont systems. We conclude by suggesting future directions of research to further elucidate the evolutionary development of bacteriocytes and the impact of these nutritional symbioses on insect plant interactions.

关键词： development evolutionary insect herbivores plant-insect microbe interactions symbiosis

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Ineffective oesophageal motility:Manometric subsets exhibit different symptom profiles

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World Journal of Gastroenterology 2008年第23期14卷 3719-3724页

作者： Horst Gunter Haack.Ross David hansen allison Malcolm John Edward k.llow Department of Gastroenterology Gastrointestinal Investigation UnitRoyal North Shore HospitalUniversity of SydneyAustralia

AIM:To compare the demographic and clinical features of different manometric subsets of ineffective oesophageal motility(IOM;defined as ≥ 30% wet swallows with distal contractile amplitude < 30 mmHg) ,and to determine whether the prevalence of gastro-oesophageal reflux differs between IOM subsets. METHODS:Clinical characteristics of manometric subsets were determined in 100 IOM patients(73 female,median age 58 years) and compared to those of 100 age-and gender-matched patient controls with oesophageal symptoms,but normal manometry. Supine oesophageal manometry was performed with an eight-channel DentSleeve water-perfused catheter,and an ambulatory pH study assessed gastro-oesophageal reflux. RESULTS:Patients in the IOM subset featuring a majority of low-amplitude simultaneous contractions(LASC) experienced less heartburn(prevalence 26%) ,but more dysphagia(57%) than those in the IOM subset featuring low-amplitude propagated contractions(LAP;heartburn 70%,dysphagia 24%;both P ≤ 0.01) . LASC patients also experienced less heartburn and more dysphagia than patient controls(heartburn 68%,dysphagia 11%;both P < 0.001) . The prevalence of heartburn and dysphagia in IOM patients featuring a majority of non-transmitted sequences(NT) was 54%(P = 0.04 vs LASC) and 36%(P < 0.01 vs controls) ,respectively. No differences inage and gender distribution,chest pain prevalence,acid exposure time(AET) and symptom/reflux association existed between IOM subsets,or between subsets and controls. CONCLUSION:IOM patients with LASC exhibit a different symptom profile to those with LAP,but do not differ in gastro-oesophageal reflux prevalence. These findings raise the possibility of different pathophysiological mechanisms in IOM subsets,which warrants further investigation.

关键词：食管运动性压力测试同步收缩

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