Sub-fossil Insects and ecosystem dynamics in wetlands; implications for biodiversity and conservation.

We review the uses of fossil insects, particularly Coleoptera (beetles) and Chironomidae (non-biting midges) from ancient deposits to inform the study of wetland ecosystems and their ecological and restoration processes. In particular, we focus on two contrasting ecosystems, drawing upon research undertaken by us on British raised mire peats and shallow lake systems, one an essentially terrestrial ecosystem, the other aquatic, but in which wetland insects play an important and integral part. The study of raised mire peats suggests that faunal stability is a characteristic of these wetland systems, over what appear to be extensive periods of time (up to several millennia), whilst studies of shallow lake ecosystems over recent timescales indicates that faunal instability appears to be more common, usually driven by increasing eutrophication. Drawing upon a series of fossil Coleoptera records spanning several thousand years from Hatfield Moors, south Yorkshire, we reconstruct in some detail the mire’s ontogeny and fluctuations in site hydrology and vegetation cover, illustrating the intimate association between substrate, topography and peat development. A comparison between fossil and modern beetle populations indicates that the faunal characteristics of this mire and its adjacent neighbour, Thorne Moors, become established during the early phases of peat development, including its rare endemics, and that the faunal biodiversity on the sites today is dictated by complex site histories. The over-riding characteristic of these faunas is of stability over several thousand years, which has important implications for the restoration of degraded sites, especially those where refugial areas are limited. In contrast, analyses of fossil Chironomidae from shallow lakes allow researchers to track changes in limnological status and while attempts have been made to reconstruct changes in nutrient levels quantitatively, the chironomids respond indirectly to such changes, typically mediated through complex ecosystem dynamics such as changes in fish and/or macrophyte communities. These changes are illustrated via historic chironomid stratigraphies and diversity indices from a range of shallow lakes located across Britain: Slapton Ley, Frensham Great Pond, Fleet Pond, Kyre Pool and Barnes Loch. These sites have shown varying degrees of eutrophication over recent timescales which tends to be associated with a decline in chironomid diversity. While complex functional processes exist within these ecosystems, our evidence suggests that one of the key drivers in the loss of shallow lake chironomid diversity appears to be the loss of aquatic macrophytes. Overall, while chironomids do show a clear response to altered nutrient regimes, multi-proxy reconstructions are recommended for a clear interpretation of past change. We conclude that if we are to have a better understanding of biota at the ecosystem level we need to know more of the complex interactions between different insect groups as well as with other animal and plant communities. A palaeoecological approach is thus crucial in order to assess the role of insect groups in ecosystem processes, both in the recent past and over long time scales, and is essential for wetland managers and conservation organisations involved in long term management and restoration of wetland systems.

Disturbances in social interaction occur along with pathophysiological deficits following sub-chronic phencyclidine administration in the rat.

A sub-chronic administration of phencyclidine to the rat brings about enduring pathophysiological and cognitive changes that resemble some features of schizophrenia. The present study aimed to determine whether the behavioural consequence of this phencyclidine regime extends to a long-term disruption of social interaction that might provide a parallel with some negative symptoms of the disease. Rats were treated with phencyclidine (2mg/kg bi-daily for 1 week) or vehicle followed by a drug-free period. Social interaction was assessed 24h, 1 week, 3 weeks and 6 weeks post-treatment. A long-lasting disturbance of social behaviour was observed in the phencyclidine group, namely more contact and non-contact interaction with an unfamiliar target rat at all time points. Six weeks post-phencyclidine, analysis of brains showed a reduction in expression of parvalbumin immunoreactive neurons in the hippocampus with significant reductions localised to the CA1 and dentate gyrus regions. These results show that sub-chronic phencyclidine produces long-lasting disruptions in social interaction that, however, do not model the social withdrawal seen in patients with schizophrenia. These disturbances of social behaviour may be associated with concurrent pathophysiological brain changes.

Metabolic effects of sub-chronic ablation of the incretin receptors by daily administration of (Pro(3))GIP and exendin(9-39)amide in obese diabetic (ob/ob) mice

Effects of chemical ablation of the GIP and GLP-1 receptors on metabolic aspects of obesity-diabetes were investigated using the stable receptor antagonists (Pro(3))GIP and exendin(9-39)amide. Ob/ob mice received a daily i.p. injection of saline vehicle, (Pro(3))GIP, exendin(9-39)amide or a combination of both peptides over a 14-day period. Non-fasting plasma glucose levels were significantly (p <0.05) lower in (Pro(3))GIP-treated mice compared to control mice after just 9 days of treatment. (Pro(3))GIP-treated mice also displayed significantly lower plasma glucose concentrations in response to feeding and intraperitoneal administration of either glucose or insulin (p <0.05 to p <0.001). The (Pro(3))GIP-treated group also exhibited significantly (p <0.05) reduced pancreatic insulin content. Acute administration of exendin(9-39) amide immediately prior to re-feeding completely annulled the beneficial effects of sub-chronic (Pro(3))GIP treatment, but non-fasting concentrations of active GLP-1 were unchanged. Combined sub-chronic administration of (Pro(3)GIP) with exendin(9-39)amide revealed no beneficial effects. Similarly, daily administration of exendin(9-39)amide alone had no significant effects on any of the metabolic parameters measured. These studies highlight an important role for GIP in obesity-related forms of diabetes, suggesting the possible involvement of GLP-1 in the beneficial actions of GIP receptor antagonism.

Effects of sub-chronic exposure to naturally occurring N-terminally truncated metabolites of glucose-dependent insulinotrophic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), GIP(3-42) and GLP-1 (9-36)amide, on insulin secretion and glucose homeostasis in ob/ob mice

Glucose-dependent insulinotrophic polypepticle (GIP) and glucagon-like peptide-1 (GLP-1) are important enteroendocrine hormones that are rapidly degraded by an ubiquitous enzyme dipeptidyl peptidase IV to yield truncated metabolites GIP(3-42) and GLP-1 (9-36)amide. In this study, we investigated the effects of sub-chronic exposure to these major circulating forms of GIP and GLP-1 on blood glucose control and endocrine pancreatic function in obese diabetic (ob/ob) mice. A once daily injection of either peptide for 14 days had no effect on body weight, food intake or pancreatic insulin content or islet morphology. GLP-1(9-36)amide also had no effect on plasma glucose homeostasis or insulin secretion. Mice receiving GIP(3-42) exhibited small but significant improvements in non-fasting plasma glucose, glucose tolerance and glycaemic response to feeding. Accordingly, plasma insulin responses were unchanged suggesting that the observed enhancement of insulin sensitivity was responsible for the improvement in glycaemic control. These data indicate that sub-chronic exposure to GIP and GLP-1 metabolites does not result in physiological impairment of insulin secretion or blood glucose control. GIP(3-42) might exert an overall beneficial effect by improving insulin sensitivity through extrapancreatic action.

Beneficial effects of sub-chronic activation of glucagon-like peptide-1 (GLP-1) receptors on deterioration of glucose homeostasis and insulin secretion in aging mice

Aging is associated with an increased incidence of glucose intolerance and type 2 diabetes. Glucagon-like peptide-1 (GLP-1) is an important insulinotropic peptide secreted from the gastrointestinal tract in response to nutrient absorption. The present study was designed to assess the sub-chronic glucose regulatory effects of the potent long-acting GLP-1 receptor agonist, (Val(8))GLP-1, in aging 45-49 week old mice. Daily injection of (Val$)GLP-1 (25 nmol/kg body weight) for 12 days had no significant effect on food intake, body weight, non-fasting plasma glucose and insulin concentrations. However, after 12 days, the glycaemic response to intraperitoneal glucose was improved (P <0.05) in (Val(8))GLP-1 treated mice. In keeping with this, glucose-mediated insulin secretion was enhanced (P <0.05) and insulin sensitivity improved (P <0.05) compared to controls. These data indicate that sub-chronic activation of the GLP-1 receptor by daily treatment with (Val(8))GLP-1 counters aspects of the age-related impairment of pancreatic beta-cell function and insulin sensitivity. 2006 Elsevier Inc. All rights reserved.

Fabrication of Sub-micron Active Layer SSOI Substrates using Ion Splitting and Wafer Bonding Technologies

This paper reports the fabrication of SSOI (Silicon on Silicide On Insulator) substrates with active silicon regions only 0.5mum thick, incorporating LPCVD low resistivity tungsten silicide (WSix) as the buried layer. The substrates were produced using ion splitting and two stages of wafer bonding. Scanning acoustic microscope imaging confirmed that the bond interfaces are essentially void-free. These SSOI wafers are designed to be employed as substrates for mm-wave reflect-array diodes, and the required selective etch technology is described together with details of a suitable device.

GLP-1 and related peptides cause concentration-dependent relaxation of rat aorta through a pathway involving KATP and cAMP

increasing evidence from both clinical and experimental studies indicates that the insulin-releasing hormone, glucagon-like peptide-1 (GLP-1) may exert additional protective/reparative effects on the cardiovascular system. The aim of this study was to examine vasorelaxant effects of GLP-1(7-36)amide, three structurally-related peptides and a non-peptide GLP-1 agonist in rat aorta. Interestingly, all GLP-1 compounds, including the established GLP-1 receptor antagonist, exendin (9-39) caused concentration-dependent relaxation. Mechanistic studies employing hyperpolarising concentrations of potassium or glybenclamide revealed that these relaxant effects are mediated via specific activation of ATP-sensitive potassium channels. Further experiments using a specific membrane-permeable cyclic AMP (cAMP) antagonist, and demonstration of increased cAMP production in response to GLP-1 illustrated the critical importance of this pathway. These data significantly extend previous observations suggesting that GLP-1 may modulate vascular function, and indicate that this effect may be mediated by the GLP-1 receptor. However, further studies are required in order to establish whether GLP-1 related agents may confer additional cardiovascular benefits to diabetic patients. (c) 2008 Elsevier Inc. All rights reserved.

Effect of wall thickness on the ferroelastic domain size of BaTiO3

Extremely regular self-organized patterns of 90^o ferroelastic domains have been reported in freestanding single crystal thin films of ferroelectric BaTiO₃. Lukyanchuk et al. [Phys Rev B 79, 144111 (2009)] have recently shown that the domain size as a function of thickness for such free standing films can be well described assuming that the domains are due to stress caused by a surface tension layer that does not undergo the paraelectric–ferroelectric transition. From the starting point of Lukyanchuk’s model, it is shown here that the ‘‘universal’’relationship between domain size and domain wall thickness previously observed in ferroelectrics, ferromagnets and multiferroics is also valid for ferroelastic domains.Further analysis of experimental data also shows that the domain wall thickness can vary considerably (an order of magnitude) from sample to sample even for the same material (BaTiO₃), in spite of which the domain size scaling model is still valid, provided that the correct,sample dependent, domain wall thickness is used.