Osteoderm histology of the Pampatheriidae (Cingulata,Xenarthra, Mammalia): Implications for systematics,osteoderm growth,and biomechanical adaptation

Pampatheres are extinct, large‐bodied cingulates, which share morphological characters with both armadillos and glyptodonts but are considered to be more closely related to the latter. The osteoderm histology of six pampathere taxa was examined and compared to the histology of other cingulate osteoderms. This study investigates the development and functional adaptation of pampathere osteoderms as well as the phylogenetic relationships of the Pampatheriidae within the Cingulata. We found that pampathere osteoderms share a uniform histological organization based on a basic diploe‐like structure. After initial stages of intramembranous growth, metaplastic ossification, that is, the direct incorporation and mineralization of pre‐existing protein fibers, plays an important role in osteoderm development and provides information on various kinds of soft tissue otherwise not preserved. The latest stages of osteoderm growth are dominated by periosteal bone formation especially in the superficial cortex. Movable band osteoderms show regular arrangements of incorporated fibers that may increase the resistance of particularly weak areas against strain. The histological composition of pampathere osteoderms is plesiomorphic in its basic structure but shows a number of derived features. A unique array of Sharpey's fibers that are incorporated into the bone matrix at sutured osteoderm margins is interpreted as a synapomorphy of pampatheres. The arrangement of dermal fibers in the deep and superficial cortexes supports the close relationship between pampatheres and glyptodonts. J. Morphol., 2012. © 2011 Wiley Periodicals, Inc.     

Development of Eye Position Dependency of Slow Phase Velocity during Caloric Stimulation

The nystagmus in patients with vestibular disorders often has an eye position dependency, called Alexander’s law, where the slow phase velocity is higher with gaze in the fast phase direction compared with gaze in the slow phase direction. Alexander’s law has been hypothesized to arise either due to adaptive changes in the velocity-to-position neural integrator, or as a consequence of processing of the vestibular-ocular reflex. We tested whether Alexander’s law arises only as a consequence of non-physiologic vestibular stimulation. We measured the time course of the development of Alexander’s law in healthy humans with nystagmus caused by three types of caloric vestibular stimulation: cold (unilateral inhibition), warm (unilateral excitation), and simultaneous bilateral bithermal (one side cold, the other warm) stimulation, mimicking the normal push-pull pattern of vestibular stimulation. Alexander’s law, measured as a negative slope of the velocity versus position curve, was observed in all conditions. A reversed pattern of eye position dependency (positive slope) was found <10% of the time. The slope often changed with nystagmus velocity (cross-correlation of nystagmus speed and slope was significant in 50% of cases), and the average lag of the slope with the speed was not significantly different from zero. Our results do not support the hypothesis that Alexander’s law can only be observed with non-physiologic vestibular stimulation. Further, the rapid development of Alexander’s law, while possible for an adaptive mechanism, is nonetheless quite fast compared to most other ocular motor adaptations. These results suggest that Alexander’s law may not be a consequence of a true adaptive mechanism.     

Stimulation of phospholipid hydrolysis and arachidonic acid mobilization in human uterine decidua cells by phorbol ester.

Vasopressin and oxytocin both stimulated inositol phosphate accumulation in isolated uterine decidua cells. Pretreatment of cells with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) prevented this agonist-induced phosphoinositide hydrolysis. TPA (0.1 microM) alone had no effect on basal inositol phosphate accumulation, but stimulated phosphoinositide deacylation, as indicated by a 2-fold increase in lysophosphatidylinositol and glycerophosphoinositol. TPA also stimulated a dose-related release of arachidonic acid from decidua-cell phospholipid [phosphatidylcholine (PC) much greater than phosphatidylinositol (PI) greater than phosphatidylethanolamine]. The phorbol ester 4 beta-phorbol 12,13-diacetate (PDA) at 0.1 microM had no effect on arachidonic acid mobilization. The TPA-stimulated increase in arachidonic acid release was apparent by 2 1/2 min (116% of control), maximal after 20 min (283% of control), and remained around this value (306% of control) after 120 min incubation. TPA also stimulated significant increases in 1,2-diacylglycerol and monoacylglycerol production at 20 and 120 min. Although the temporal increases in arachidonic acid and monoacylglycerol accumulation in the presence of TPA continued up to 120 min, that of 1,2-diacylglycerol declined after 20 min. In decidua cells prelabelled with [3H]choline, TPA also stimulated a significant decrease in radiolabelled PC after 20 min, which was accompanied by an increased release of water-soluble metabolites into the medium. Most of the radioactivity in the extracellular pool was associated with choline, whereas the main cellular water-soluble metabolite was phosphorylcholine. TPA stimulated extracellular choline accumulation to 183% and 351% of basal release after 5 and 20 min respectively and cellular phosphorylcholine production to 136% of basal values after 20 min. These results are consistent with a model in which protein kinase C activation by TPA leads to arachidonic acid mobilization from decidua-cell phospholipid by a mechanism involving phospholipase A-mediated PI hydrolysis and phospholipase C-mediated PC hydrolysis, coupled with further hydrolysis of the 1,2-diacylglycerol product.     

Metallothionein induction by nonsteroidal antiinflammatory drugs

In the present study we report on the effects of commonly used nonsteroidal antiinflammatory drugs on metallothionein (MT) and MT-I mRNA levels. A single dose of chloroquine (100 mg/kg), diclofenac (100 mg/kg), indomethacin (10 mg/kg), or piroxicam (100 mg/kg) was administered ip to C57B1 mice. After 18 h, MT levels were determined with a Cd-saturation radioassay. MT-I mRNA levels were measured by Northern Blot analyses using a probe containing the mouse MT-I gene. All drugs tested caused an increase in the MT content of the liver but not of the kidneys and lung. The lowest and highest effects were observed with chloroquine (8 times the control value) and diclofenac (18 times), respectively. In accordance with the stimulation of MT synthesis, increased accumulation of hepatic MT-I mRNA could be demonstrated. These results indicate that elevated MT levels may contribute to the effectiveness of nonsteroidal antiinflammatory drugs in the treatment of rheumatoid arthritis (RA).     

Phosphatidylinositol hydrolysis in isolated guinea-pig islets of Langerhans.

Previous studies have reported an increased turnover of phospholipid in isolated islets of Langerhans in response to raised glucose concentrations. The present investigation was thus undertaken to determine the nature of any phospholipases that may be implicated in this phenomenon by employing various radiolabelled exogenous phospholipids. Hydrolysis of 1-acyl-2-[14C]arachidonoylglycerophosphoinositol by a sonicated preparation of islets optimally released radiolabelled lysophosphatidylinositol, arachidonic acid and 1,2-diacylglycerol at pH 5,7 and 9 respectively. This indicates the presence of a phospholipase A1 and a phospholipase C. However, the lack of any labelled lysophosphatidylinositol production when 2-acyl-1-[14C]stearoylglycerophosphoinositol was hydrolysed argues against a role for phospholipase A2 in the release of arachidonic acid. Phospholipase C activity as measured by phosphatidyl-myo-[3H]inositol hydrolysis was optimal around pH8, required Ca2+ for activity and was predominantly cytosolic in origin. The time course of phosphatidylinositol hydrolysis at pH 6 indicated a precursor-product relationship for 1,2-diacylglycerol and arachidonic acid respectively. The release of these two products when phosphatidylinositol was hydrolysed by either islet or acinar tissue was similar. However, phospholipase A1 activity was 20-fold higher in acinar tissue. Substrate specificity studies with islet tissue revealed that arachidonic acid release from phosphatidylethanolamine and phosphatidylcholine was only 8% and 2.5% respectively of that from phosphatidylinositol. Diacylglycerol lipase was also demonstrated in islet tissue being predominantly membrane bound and stimulated by Ca2+. The availability of non-esterified arachidonic acid in islet cells could be regulated by changes in the activity of a phosphatidylinositol-specific phospholipase C acting in concert with a diacylglycerol lipase.     

Purification and characterization of fructan: fructan fructosyl transferase from chicory (Cichorium intybus L.) roots

Fructan: fructan fructosyl transferase (FFT, EC 2.4.1.100) was purified from chicory (Cichorium intybus L. var. foliosum cv. Flash) roots by a combination of ammonium sulfate precipitation, concanavalin A affinity chromatography, and anion- and cation-exchange chromatography. This protocol produced a 60-fold purification and a specific activity of 14.5 mol·(mg protein) ^–1·min^–1. The mass of the enzyme was 69 kDa as estimated by gel filtration. On sodium dodecyl sulfatepolyacrylamide gel electrophoresis and mass spectrometry, 52-kDa and 17-kDa fragments were found, suggesting that the enzyme was a heterodimer. Optimal activity was found between pH 5.5 and 6.5. The enzyme used 1-kestose, 1,1-nystose, oligofructan and commercial chicory root inulin (degree of polymerization 10) as donors and acceptors. Sucrose was the best acceptor but could not be used as a donor. However, at higher concentrations sucrose acted as a competitive inhibitor for donors of FFT. 1-Kestose was the most efficient and 1,1-nystose the least efficient donor. The purified enzyme exhibited -fructosidase activity, specially at higher temperatures and lower substrate concentrations. The synthesis of fructans from 1-kestose decreased at higher temperatures (5–50°C). Therefore enzyme assays were performed at 0°C. The same fructan oligosaccharides, with a distribution similar to that observed in vivo, were obtained upon incubation of the enzyme with sucrose and commercial chicory root inulin.Abbreviations Con A concanavalin A - DP degree of polymerization - FFT fructan: fructan fructosyl transferase - Fru fructose - Glc glucose - Kes 1-kestose - MALDI-TOF MS matrix-assisted laser desorption ionisation time of flight mass spectrometry - Nys 1,1-nystose - pI isoelectric point - SST sucrose: sucrose fructosyl transferase - Suc sucrose The authors would like to thank E. Nackaerts for valuable assistance. W. Van den Ende is also grateful to the National Fund for Scientific Research (NFSR Belgium) for giving a grant for research assistants. P. Verhaert is a research associate of the NFSR. This work was also supported by grant OT/91/18 from the Research Fund K.U. Leuven.     

Conversion of 2-chloromaleylacetate in Alcaligenes eutrophus JMP134

2,4-Dichlorophenoxyacetate (2,4-D) in Alcaligenes eutrophus JMP134 (pJP4) is degraded via 2-chloromaleylacetate as an intermediate. The latter compound was found to be reduced by NADH in a maleylacetate reductase catalyzed reaction. Maleylacetate and chloride were formed as products of 2-chloromaleylacetate reduction, the former being funnelled into the 3-oxoadipate pathway by a second reductive step. There was no indication for an involvement of a pJP4-encoded enzyme in either the reduction or the dechlorination reaction.Abbreviations 2,4-D 2,4-dichlorophenoxyacetate     

Enhancing the structural diversity between forest patches—A concept and real-world experiment to study biodiversity,multifunctionality and forest resilience across spatial scales

Intensification of land use by humans has led to a homogenization of landscapes and decreasing resilience of ecosystems globally due to a loss of biodiversity, including the majority of forests. Biodiversity–ecosystem functioning (BEF) research has provided compelling evidence for a positive effect of biodiversity on ecosystem functions and services at the local (α-diversity) scale, but we largely lack empirical evidence on how the loss of between-patch β-diversity affects biodiversity and multifunctionality at the landscape scale (γ-diversity). Here, we present a novel concept and experimental framework for elucidating BEF patterns at α-, β-, and γ-scales in real landscapes at a forest management-relevant scale. We examine this framework using 22 temperate broadleaf production forests, dominated by Fagus sylvatica. In 11 of these forests, we manipulated the structure between forest patches by increasing variation in canopy cover and deadwood. We hypothesized that an increase in landscape heterogeneity would enhance the β-diversity of different trophic levels, as well as the β-functionality of various ecosystem functions. We will develop a new statistical framework for BEF studies extending across scales and incorporating biodiversity measures from taxonomic to functional to phylogenetic diversity using Hill numbers. We will further expand the Hill number concept to multifunctionality allowing the decomposition of γ-multifunctionality into α- and β-components. Combining this analytic framework with our experimental data will allow us to test how an increase in between patch heterogeneity affects biodiversity and multifunctionality across spatial scales and trophic levels to help inform and improve forest resilience under climate change. Such an integrative concept for biodiversity and functionality, including spatial scales and multiple aspects of diversity and multifunctionality as well as physical and environmental structure in forests, will go far beyond the current widely applied approach in forestry to increase resilience of future forests through the manipulation of tree species composition.