Effect of aestivation on long bone mechanical properties in the green-striped burrowing frog, Cyclorana alboguttata

The green-striped burrowing frog, Cyclorana alboguttata, survives extended drought periods by burrowing underground and aestivating. These frogs remain immobile within cocoons of shed skin and mucus during aestivation and emerge from their burrows upon heavy rains to feed and reproduce. Extended periods of immobilisation in mammals typically result in bone remodelling and a decrease in bone strength. We examined the effect of aestivation and, hence, prolonged immobilisation on cross-sectional area, histology and bending strength in the femur and tibiolibula of C alboguttata. Frogs were aestivated in soil for three and nine months and were compared with control animals that remained active, were fed and had a continual supply of water. Compared with the controls, long bone size, anatomy and bending strength remained unchanged, indicating an absence of disuse osteoporosis. This preservation of bone tissue properties enables C. alboguttata to compress the active portions of their life history into unpredictable windows of opportunity, whenever heavy rains occur.

Blood-respiratory and acid-base changes during extended diving in the bimodally respiring freshwater turtle Rheodytes leukops

Changes in blood-gas, acid-base, and plasma-ion status were investigated in the bimodally respiring turtle, Rheodytes leukops, during prolonged dives of up to 12 h. Given that R. leukops routinely submerges for several hours, the objective of this study was to determine whether voluntarily diving turtles remain aerobic and simultaneously avoid hypercapnic conditions over increasing dive lengths. Blood PO2, PCO2, and pH, as well as plasma concentrations of lactate, glucose, Na+, K+, Cl-, total Ca, and total Mg were determined in venous blood collected from the occipital sinus. Blood PO2 declined significantly with dive length; however, oxy-haemoglobin saturation remained greater than 30% for all R. leukops sampled. No changes were observed in blood PCO2, pH, [HCO3-], or plasma glucose, with increasing dive length. Despite repeated dives lasting more than 2 h, plasma lactate remained less than 3 mmol l(-1) for all R. leukops sampled, indicating the absence of anaerobiosis. Compensatory acid-base adjustments associated with anaerobiosis (e.g. declining [Cl-], increasing total [Ca] and [Mg]) were likewise absent, with plasma-ion concentrations remaining stable with increasing dive length. Results indicate that R. leukops utilises aquatic respiration to remain aerobic during prolonged dives, thus effectively avoiding the development of a metabolic and respiratory acidosis.

Understanding the phylogeographic patterns of European hedgehogs, Erinaceus concolor and E-europaeus using the MHC

The genome of the European hedgehog, Erinaceus concolor and E. europaeus, shows a strong signal of cycles of restriction to glacial refugia and postglacial expansion. Patterns of expansion, however, differ for mitochondrial DNA (mtDNA) and preliminary analysis of nuclear markers. In this study, we determine phylogeographic patterns in the hedgehog using two loci of the major histocompatibility complex (MHC), isolated for the first time in hedgehogs. These genes show long persistence times and high polymorphism in many species because of the actions of balancing selection. Among 84 individuals screened for variation, only two DQA alleles were identified in each species, but 10 DQB alleles were found in E. concolor and six in E. europaeus. A strong effect of demography on patterns of DQB variability is observed, with only weak evidence of balancing selection. While data from mtDNA clearly subdivide both species into monophyletic subgroups, the MHC data delineate only E. concolor into distinct subgroups, supporting the preliminary findings of other nuclear markers. Together with differences in variability, this suggests that the refugia history and/or expansion patterns of E. concolor and E. europaeus differ.

Arousal and re-feeding rapidly restores digestive tract morphology following aestivation in green-striped burrowing frogs

During aestivation, the gut of the green-striped burrowing frog, Cyclorana alboguttata undergoes significant morphological down-regulation. Despite the potential impact such changes might have on the re-feeding efficiency of these animals following aestivation, they appear to be as efficient at digesting their first meals as active, non-aestivating animals. Such efficiency might come about by the rapid restoration of intestinal morphology with both arousal from aestivation and the initial stages of re-feeding. Consequently, this study sought to determine what morphological changes to the intestine accompany arousal and re-feeding following 3 months of aestivation. Arousal from aestivation alone had a marked impact on many morphological parameters, including small and large intestine masses, small intestinal length, LF heights, enterocyte cross-sectional area and microvilli height and density. In addition, the onset of re-feeding was correlated with an immediate reversal of many morphological parameters affected by 3 months of aestivation. Those parameters that had not returned to control levels within 36 h of feeding generally had returned to control values by the completion of digestion (i.e. defecation of the meal). Re-feeding was also associated with several changes in enterocyte morphology including the incorporation in intracytoplasmic lipid droplets and the return of enterocyte nuclear material to the 'active' euchromatin state: In conclusion, morphological changes to the gut of aestivating frogs which occur during aestivation are transitory and rapidly reversible with both arousal from aestivation and re-feeding. The proximate causes behind these transitions and their functional significance are discussed. (C) 2005 Elsevier Inc. All rights reserved.

Lessons from an estivating frog: sparing muscle protein despite starvation and disuse

Long (6- to 9-mo) bouts of estivation in green-striped burrowing frogs lead to 28% atrophy of cruralis oxidative fibers (P < 0.05) and some impairment of in vitro gastrocnemius endurance (P < 0.05) but no significant deficit in maximal twitch force production. These data suggest the preferential atrophy of oxidative fibers at a rate slower than, but comparable to, laboratory disuse models. We tested the hypothesis that the frog limits atrophy by modulating oxidative stress. We assayed various proteins at the transcript level and verified these results for antioxidant enzymes at the biochemical level. Transcript data for NADH ubiquinone oxidoreductase subunit 1 (71% downregulated, P < 0.05) and ATP synthase (67% downregulated, P < 0.05) are consistent with mitochondrial quiescence and reduced oxidant production. Meanwhile, uncoupling protein type 2 transcription (P < 0.31), which is thought to reduce mitochondrial leakage of reactive oxygen species, was maintained. Total antioxidant defense of water-soluble (22.3 +/- 1.7 and 23.8 +/- 1.5 mu M/mu g total protein in control and estivator, respectively, P = 0.53) and membrane-bound proteins (31.5 +/- 1.9 and 42.1 +/- 7.3 mu M/mu g total protein in control and estivator, respectively, P = 0.18) was maintained, equivalent to a bolstering of defense relative to oxygen insult. This probably decelerates muscle atrophy by preventing accumulation of oxidative damage in static protein reserves. Transcripts of the mitochondrially encoded antioxidant superoxide dismutase type 2 ( 67% downregulated, P < 0.05) paralleled mitochondrial activity, whereas nuclear-encoded catalase and glutathione peroxidase were maintained at control values (P = 0.42 and P = 0.231), suggesting a dissonance between mitochondrial and nuclear antioxidant expression. Pyruvate dehydrogenase kinase 4 transcription was fourfold lower in estivators (P = 0.11), implying that, in contrast to mammalian hibernators, this enzyme does not drive the combustion of lipids that helps spare hypometabolic muscle.

Sedimentology of cores from the Iberian margin

Bioturbation in marine sediments has basically two aspects of interest for palaeo-environmental studies. First, the traces left by the burrowing organisms reflect the prevailing environmental conditions at the seafloor and thus can be used to reconstruct the ecologic and palaeoceanographic situation. Traces have the advantage over other proxies of practically always being preserved in situ. Secondly, for high- resolution stratigraphy, bioturbation is a nuisance due to the stirring and mixing processes that destroy the stratigraphic record. In order to evaluate the applicability of biogenic traces as palaeoenvironmental indicators, a number of gravity cores from the Portuguese continental slope, covering the period from the last glacial to the present were investigated through X-ray radiographs. In addition, physical and chemical parameters were determined to define the environmental niche in each core interval. A number of traces could be recognized, the most important being: Thalassinoides, Planolites, Zoophycos, Chondrites, Scolicia, Palaeophycus, Phycosiphon and the generally pyritized traces Trichichnus and Mycellia. The shifts between the different ichnofabrics agree strikingly well with the variations in ocean circulation caused by the changing climate. On the upper and middle slope, variations in current intensity and oxygenation of the Mediterranean Outflow Water were responsible for shifts in the ichnofabric. Larger traces such as Planolites and Thalassinoides dominated in coarse, well oxygenated intervals, while small traces such as Chondrites and Trichichnus dominated in fine grained, poorly oxygenated intervals. In contrast, on the lower slope where calm steady sedimentation conditions prevail, changes in sedimentation rate and nutrient flux have controlled variations in the distribution of larger traces such as Planolites, Thalassinoides, and Palaeophycus. Additionally, distinct layers of abundant Chondrites correspond to Heinrich events 1, 2, and 4, and are interpreted as a response to incursions of nutrient rich, oxygen depleted Antarctic waters during phases of reduced thermohaline circulation. The results clearly show that not one single factor but a combination of several factors is necessary to explain the changes in ichnofabric. Furthermore, large variations in the extent and type of bioturbation and tiering between different settings clearly show that a more detailed knowledge of the factors governing bioturbation is necessary if we shall fully comprehend how proxy records are disturbed. A first attempt to automatize a part of the recognition and quantification of the ichnofabric was performed using the DIAna image analysis program on digitized X-ray radiographs. The results show that enhanced abundance of pyritized microburrows appears to be coupled to organic rich sediments deposited under dysoxic conditions. Coarse grained sediments inhibit the formation of pyritized burrows. However, the smallest changes in program settings controlling the grey scale threshold and the sensitivity resulted in large shifts in the number of detected burrows. Therefore, this method can only be considered to be semi-quantitative. Through AMS-^C dating of sample pairs from the Zoophycos spreiten and the surrounding host sediment, age reversals of up to 3,320 years could be demonstrated for the first time. The spreiten material is always several thousands of years younger than the surrounding host sediment. Together with detailed X-ray radiograph studies this shows that the trace maker collects the material on the seafloor, and then transports it downwards up to more than one meter in to the underlying sediment where it is deposited in distinct structures termed spreiten. This clearly shows that age reversals of several thousands of years can be expected whenever Zoophycos is unknowingly sampled. These results also render the hitherto proposed ethological models proposed for Zoophycos as largely implausible. Therefore, a combination of detritus feeding, short time caching, and hibernation possibly combined also with gardening, is suggested here as an explanation for this complicated burrow.

White-nose syndrome initiates a cascade of physiologic disturbances in the hibernating bat host

Acknowledgments This project was financially supported by the US Geological Survey through a cooperative agreement with the University of Wisconsin – Madison. We are indebted to Dave and Jennifer Redell and Paul White from the Wisconsin Department of Natural Resources for collecting the animals used to complete this study and for assisting with data collection. We thank Melissa Behr for assistance with necropsies and NWHC Animal Care Staff for their help with set-up and maintenance of animals. We thank Lobke Vaanholt and Catherine Hambly (University of Aberdeen, Scotland) for their expertise and coordination in the analyses of the DLW blood samples. Funds were used for direct project costs only. Use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

Investigating the Intrinsic and Extrinsic Drivers of Primate Heterothermy

Seasonal heterothermy—an orchestrated set of extreme physiological responses—is directly responsible for the over-winter survival of many mammalian groups living in seasonal environments. Historically, it was thought that the use of seasonal heterothermy (i.e. daily torpor and hibernation) was restricted to cold-adapted species; it is now known that such thermoregulatory strategies are used by more species than previously appreciated, including many tropical species. The dwarf and mouse lemurs (family Cheirogaleidae) are among the few primates known to use seasonal heterothermy to avoid Madagascar’s harsh and unpredictable environments. These primates provide an ideal study system for investigating a common mechanism of mammalian seasonal heterothermy. The overarching theme of this dissertation is to understand both the intrinsic and extrinsic drivers of heterothermy in three species of the family Cheirogaleidae. By using transcriptome sequencing to characterize gene expression in both captive and natural settings, we identify unique patterns of differential gene expression that are correlated with extreme changes in physiology in two species of dwarf lemurs: C. medius under captive conditions at the Duke Lemur Center and C. crossleyi studied under field conditions in Madagascar. Genes that are differentially expressed appear to be critical for maintaining the health of these animals when they undergo prolonged periods of metabolic depression concurrent with the hibernation phenotype. Further, a comparative analysis of previously studied mammalian heterotherms identifies shared genetic mechanisms underlying the hibernation phenotype across the phylogeny of mammals. Lastly, conducting a diet manipulation study with a captive colony of mouse lemurs (Microcebus murinus) at the Duke Lemur Center, we investigated the degree to which dietary effects influence torpor patterns. We find that tropical primate heterotherms may be exempt from the traditional paradigms governing cold-adapted heterothermy, having evolved different dietary strategies to tolerate circadian changes in body temperature.

designing + (dis)assembling disputes: an ethnography of disputes & lawyers in the construction industry

The UK construction industry is notorious for the sheer amount of disputes which are likely to arise on each building and engineering project. Despite numerous creative attempts at “dispute avoidance” and “dispute resolution”, this industry is still plagued with these costly disputes. Whilst both academic literature and professional practices have investigated the causes of disputes and the mechanisms for avoidance/resolution of these disputes, neither has studied in any detail the nature of the construction disputes and why they develop as they do once a construction lawyer is engaged. Accordingly, this research explores the question of what influences the outcome of a construction dispute and to what extent do construction lawyers control or direct this outcome? The research approach was ethnographic. Fieldwork took place at a leading construction law firm in London over 18 months. The primary focus was participant observation in all of the firm’s activities. In addition, a database was compiled from the firm’s files and archives, thus providing information for quantitative analysis. The basis of the theoretical framework, and indeed the research method, was the Actor‐Network Theory (ANT). As such, this research viewed a dispute as a set of associations – an entity which takes form and acquires its attributes as a result of its relations with other entities. This viewpoint is aligned with relational contract theories, which in turn provides a unified platform for exploring the disputes. The research investigated the entities and events which appeared to influence the dispute’s identity, shape and outcome. With regard to a dispute’s trajectory, the research took as its starting point that a dispute follows the transformation of “naming, blaming, claiming…”, as identified by Felstiner, Abel and Sarat in 1980. The research found that construction disputes generally materialise and develop prior to any one of the parties approaching a lawyer. Once the lawyer is engaged, we see the reverse of the trajectory “naming, blaming, claiming…” this being: “claiming, blaming, naming…” The lawyers’ role is to identify or name (or rename) the dispute in the best possible light for their client in order to achieve the desired outcome – the development of which is akin to the design process. The transformation of a dispute and the reverse trajectory is by no means linear, but rather, iterative and spatial as it requires alliances, dependencies and contingencies to assemble and take the shape it does. The research concludes that construction disputes are rarely ever completely “resolved” as such. Whilst an independent third party may hand down a judgment, or the parties may reach a settlement agreement, this state is only temporal. Some construction disputes dissipate whist others reach a state of hibernation for a period of time only to pick up momentum and energy some years later. Accordingly, this research suggests that the concept of “dispute resolution” does not exist in the UK construction industry. The ultimate goal should be for parties to reach this ultimate and perpetual state of equilibrium as quickly and as cost effectively as possible: “dispute dissolution”, the slowing down of the dispute’s momentum. Rather than focusing on the design and assemblage of the dispute, the lawyers’ role therein is, or should be, to assist with the “disassembling” of the dispute.

Die cromerzeitlichen Bären aus der Einhornhöhle bei Scharzfeld

Up to now the bear remains from the "Einhornhöhle,, Cave near Scharzfeld at the foot of the Harz Mountains have been aseribed to the species "Ursus spelaeus" without undertaking comprehensive studies. Owing to an erroneous Classification of the gravel deposits covering part of the cave floor into the Middle Terrace of the Oder Rivulet, the fossil-bearing strata have been assigned to the Eemian Interglacial. RODE, who included a part of the Scharzfeld teeth in his treatise on teeth of the bears, has stated arctoidal features in their formation apart from certain specializations. He arrived at the conclusion that the Scharzfeld Bear differs more pronouncedly from all Central European Cave Bears he had investigated than the same differ from each other, and he named the Scharzfeld Bear: "Ursus spelaeus var. hercynica". The geological exploration of the Einhornhöhle Cave and of its environs carried out by DUPHORN in 196? resulted in the aforesaid gravels pertaining to a terrace of a Pre-Elster- Glaciation age; according to DUPHORN the fossil-bearing Sediments were deposited in a Pre-Elster-Glaciation ffarm- Climate Period. The very sparse aceompanying fauna does not contain any Stratigraphie key form; arctic elements and members of an interglacial forest fauna are missing. Its composition teils in favour of a dry, yet not too cool period of the Pleistocene, which is younger than the Villa- franchium. Consequently the cave must have been taken pos- session of for settling in the Cromerian Interglacial. The investigation of the bear remains has led to the result that, in all systematically .important teeth and skeleton characteristics, the Scharzfeld Bear shows either concor- dance with Ursus deningeri or greater analogy to the same than to Ursus spelaeus; in a few properties it even appears somewhat more primitive than Ursus deningeri. Therefore the bears of the Einhornhöhle Cave belong to the species "Ursus deningeri v. REICHENAU 1906". In the frontal teeth certain specializations occur. However, in view to the great varia- bility of the deningeri-"rassenkreis" there does not seem to be a justification for establishing a subspecies of its own. Whereas up to now nothing had been known in respect of the hibernation habits of Ursus deningeri, there has for the first time been furnished proof that an Ursus deningeri population had oecologically become "cave" bears. Consequently this specialization, as the onset and cause of which the Elster Glaciation was up to now considered, must already be originating in older cold epochs.

Developing strategies to mitigate the energy consumed by network infrastructures

The energy consumption by ICT (Information and Communication Technology) equipment is rapidly increasing which causes a significant economic and environmental problem. At present, the network infrastructure is becoming a large portion of the energy footprint in ICT. Thus the concept of energy efficient or green networking has been introduced. Now one of the main concerns of network industry is to minimize energy consumption of network infrastructure because of the potential economic benefits, ethical responsibility, and its environmental impact. In this paper, the energy management strategies to reduce the energy consumed by network switches in LAN (Local Area Network) have been developed. According to the lifecycle assessment of network switches, during usage phase, the highest amount of energy consumed. The study considers bandwidth, link load and traffic matrixes as input parameters which have the highest contribution in energy footprint of network switches during usage phase and energy consumption as output. Then with the objective of reducing energy usage of network infrastructure, the feasibility of putting Ethernet switches hibernate or sleep mode was investigated. After that, the network topology was reorganized using clustering method based on the spectral approach for putting network switches to hibernate or switched off mode considering the time and communications among them. Experimental results show the interest of this approach in terms of energy consumption

Czynniki kształtujące liczebność populacji jeża wschodniego Erinaceus roumanicus Barrett-Hamilton, 1900 w środowisku zurbanizowanym

Wydział Biologii