Extrinsic Mortality Can Shape Life-History Traits,Including Senescence

The Williams’ hypothesis is one of the most widely known ideas in life history evolution. It states that higher adult mortality should lead to faster and/or earlier senescence. Theoretically derived gradients, however, do not support this prediction. Increased awareness of this fact has caused a crisis of misinformation among theorists and empirical ecologists. We resolve this crisis by outlining key issues in the measurement of fitness, assumptions of density dependence, and their effect on extrinsic mortality. The classic gradients apply only to a narrow range of ecological contexts where density-dependence is either absent or present but with unrealistic stipulations. Re-deriving the classic gradients, using a more appropriate measure of fitness and incorporating density, shows that broad ecological contexts exist where Williams’ hypothesis is supported.     

Über die DesmidiaceeCosmarium annulatum (Nägeli) De Bary und ihr Vorkommen im Lunzer Moorgebiete

Zusammenfassung Es wird über das Vorkommen der Desmidiacee (Conjugate)Cosmarium annulatum im Rehberger Moor bei Lunz in Niederösterreich berichtet; eine Liste der in diesem Moore zwischen 1936 und 1951 vom Verfasser vorgefundenen Desmidiales wird vorgelegt. Der bis jetzt noch ungenügend bekannte Zellbau vonCosmarium annulatum wird beschrieben und die Stellung der Alge im System erörtert.Gewidmet Herrn Prof. Dr.Franz Ruttner, Vorstand der biologischen Station in Lunz am See, der seit 20 Jahren die Arbeiten des Verfassers ermöglicht und in jeder Hinsicht gefördert hat, mit den besten Glückwünschen zum 70. Geburtstage.     

Ocellar interneurones in the blowfly Calliphora erythrocephala: Morphology and central projections

Summary The morphology and central projections of first-order ocellar interneurones were analysed in the blowfly, Calliphora erythrocephala after cobalt and horseradish-peroxidase labelling. Three classes of interneurones can be distinguished on the basis of axon diameters: large, medium and small neurones. In total there are 12 large, 10 medium and an unknown number of small interneurones. These interneurones connect the fused first-order ocellar neuropil (underlying the three ocelli) with various areas of the central nervous system. The large neurones terminate in three subregions of the posterior slope (ocellar foci); the medium neurones arborise in several regions of the lateral protocerebrum, in the posterior slope, the lobula, the ventral medulla, and in the pro- and mesothoracic ganglia. The thin fibers arborise in all the above regions (except in the thoracic ganglia), and in addition in the neuropil dorsal to the oesophagus and antero-ventral to posterior slope (tritocerebrum). The anatomy of the ocellar pathway in C. erythrocephala is compared with those in other studied insects. Possible interactions between ocellar interneurones and other pathways are discussed.     

The production of podophyllotoxin and its 5-methoxy derivative through bioconversion of cyclodextrin-complexed desoxypodophyllotoxin by plant cell cultures

The bioconversion of the lignan desoxypodophyllotoxin by cell suspensions of Linum flavum and of Podophyllum hexandrum was investigated. The apolar substrate could be easily dissolved in the culture medium at a concentration of 2 mM by complexation with dimethyl--cyclodextrin. Growth parameters of the cell suspensions were not affected by either the addition of cyclodextrin itself, or when cyclodextrin-complexed desoxypodophyllotoxin was present in the medium. The complexed lignan disappeared from the medium within 7 days for both cell cultures. Cellularly only small amounts of desoxypodophyllotoxin were found. After feeding of desoxypodophyllotoxin, the cell culture of L. flavum accumulated 5-methoxypodophyllotoxin and 5-methoxypodophyllotoxin--D-glucoside. After 7 days a total maximal content of 2.38% on a dry weight basis of 5-methoxypodophyllotoxin was formed, corresponding with 249 mg l^-1 suspension. The highest bioconversion percentage of 52.3% was found at day 14. The desoxypodophyllotoxin-fed culture of P. hexandrum accumulated podophyllotoxin and its -D-glucoside with a maximal content of 2.87% on a dry weight basis after 9 days, corresponding with 192 mg 1^-1 suspension. The highest bioconversion percentage of 33.2% was also found at day 9.     

VO2 max is associated with ACE genotype in postmenopausal women

Relationships have frequently been found betweenangiotensin-converting enzyme (ACE) genotype and various pathologicaland physiological cardiovascular outcomes and functions. Thuswe sought to determine whether ACE genotype affected maximalO₂ consumption (O_{2 max}) and maximalexercise hemodynamics in postmenopausal women with different habitualphysical activity levels. Age, body composition, and habitual physicalactivity levels did not differ among ACE genotype groups. However, ACEinsertion/insertion (II) genotype carriers had a 6.3 ml · kg¹ · min¹higher O_{2 max}(P < 0.05) than the ACEdeletion/deletion (DD) genotype group after accounting for the effectof physical activity levels. The ACE II genotype group also had a 3.3 ml · kg¹ · min¹higher O_{2 max}(P < 0.05) than the ACEinsertion/deletion (ID) genotype group. The ACE ID group tended to havea higher O_{2 max} thanthe DD genotype group, but the difference was not significant. ACEgenotype accounted for 12% of the variation inO_{2 max} among womenafter accounting for the effect of habitual physical activity levels.The entire difference inO_{2 max} among ACEgenotype groups was the result of differences in maximal arteriovenousO₂ difference (a-vDO₂).ACE genotype accounted for 17% of the variation in maximal a-vDO₂ inthese women. Maximal cardiac output index did not differ whatsoeveramong ACE genotype groups. Thus it appears that ACE genotype accountsfor a significant portion of the interindividual differences inO_{2 max} among thesewomen. However, this difference is the result of genotype-dependentdifferences in maximala-vDO₂ andnot of maximal stroke volume and maximal cardiac output.

     

Motor Unit Characteristics after Targeted Muscle Reinnervation

Targeted muscle reinnervation (TMR) is a surgical procedure used to redirect nerves originally controlling muscles of the amputated limb into remaining muscles above the amputation, to treat phantom limb pain and facilitate prosthetic control. While this procedure effectively establishes robust prosthetic control, there is little knowledge on the behavior and characteristics of the reinnervated motor units. In this study we compared the m. pectoralis of five TMR patients to nine able-bodied controls with respect to motor unit action potential (MUAP) characteristics. We recorded and decomposed high-density surface EMG signals into individual spike trains of motor unit action potentials. In the TMR patients the MUAP surface area normalized to the electrode grid surface (0.25 ± 0.17 and 0.81 ± 0.46, p < 0.001) and the MUAP duration (10.92 ± 3.89 ms and 14.03 ± 3.91 ms, p < 0.01) were smaller for the TMR group than for the controls. The mean MUAP amplitude (0.19 ± 0.11 mV and 0.14 ± 0.06 mV, p = 0.07) was not significantly different between the two groups. Finally, we observed that MUAP surface representation in TMR generally overlapped, and the surface occupied by motor units corresponding to only one motor task was on average smaller than 12% of the electrode surface. These results suggest that smaller MUAP surface areas in TMR patients do not necessarily facilitate prosthetic control due to a high degree of overlap between these areas, and a neural information—based control could lead to improved performance. Based on the results we also infer that the size of the motor units after reinnervation is influenced by the size of the innervating motor neuron.     

Assessment of Global and Regional Diffusion Changes along White Matter Tracts in Parkinsonian Disorders by MR Tractography

Purpose

The aim of the study was to determine the usefulness of diffusion tensor tractography (DTT) in parkinsonian disorders using a recently developed method for normalization of diffusion data and tract size along white matter tracts. Furthermore, the use of DTT in selected white matter tracts for differential diagnosis was assessed.

Methods

We quantified global and regional diffusion parameters in major white matter tracts in patients with multiple system atrophy (MSA), progressive nuclear palsy (PSP), idiopathic Parkinson’s disease (IPD) and healthy controls). Diffusion tensor imaging data sets with whole brain coverage were acquired at 3 T using 48 diffusion encoding directions and a voxel size of 2×2×2 mm³. DTT of the corpus callosum (CC), cingulum (CG), corticospinal tract (CST) and middle cerebellar peduncles (MCP) was performed using multiple regions of interest. Regional evaluation comprised projection of fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and the apparent area coefficient (AAC) onto a calculated mean tract and extraction of their values along each structure.

Results

There were significant changes of global DTT parameters in the CST (MSA and PSP), CC (PSP) and CG (PSP). Consistent tract-specific variations in DTT parameters could be seen along each tract in the different patient groups and controls. Regional analysis demonstrated significant changes in the anterior CC (MD, RD and FA), CST (MD) and CG (AAC) of patients with PSP compared to controls. Increased MD in CC and CST, as well as decreased AAC in CG, was correlated with a diagnosis of PSP compared to IPD.

Conclusions

DTT can be used for demonstrating disease-specific regional white matter changes in parkinsonian disorders. The anterior portion of the CC was identified as a promising region for detection of neurodegenerative changes in patients with PSP, as well as for differential diagnosis between PSP and IPD.     

Suitability of Molluscs as Bioindicators for Meadow‐ and Flood‐Channels of the Elbe‐Floodplains

The goals of the subproject “molluscs” within the inter‐disciplinary research project “Indicator systems for the characterisation and prediction of ecological changes in floodplain systems” were: – develop further existing mollusc‐based indicator systems of site quality and to test their transferability, – characterise grassland sites within the recent floodplains of three study areas along the Elbe River, – analyse the relationships between indicator species‐/groups and abiotic parameters, – compile and use selected species traits in the analytical process. The results clearly show several characteristic species groups related to the hydrology of the sites (i.e. inundation and desiccation regime) and on to the degree of agricultural use. These dependencies can be interpreted by the simultaneous analysis of the species traits. “Models” are proposed, that are applicable to nature protection measures at the landscape scale. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Environmental contamination by vancomycin resistant enterococci (VRE) in Swedish broiler production

Background  

Vancomycin resistant enterococci are a frequent cause of nosocomial infections and their presence among farm animals is unwanted. Using media supplemented with vancomycin an increase in the proportion of samples from Swedish broilers positive for vancomycin resistant enterococci has been detected. The situation at farm level is largely unknown. The aims of this study were to obtain baseline knowledge about environmental contamination with vancomycin resistant enterococci in Swedish broiler production and the association between environmental contamination and colonisation of birds.