Vertical jumping performance of bonobo (Pan paniscus) suggests superior muscle properties

Vertical jumping was used to assess muscle mechanical output in bonobos and comparisons were drawn to human jumping. Jump height, defined as the vertical displacement of the body centre of mass during the airborne phase, was determined for three bonobos of varying age and sex. All bonobos reached jump heights above 0.7 m, which greatly exceeds typical human maximal performance (0.3-0.4m). Jumps by one male bonobo (34 kg) and one human male (61.5 kg) were analysed using an inverse dynamics approach. Despite the difference in size, the mechanical output delivered by the bonobo and the human jumper during the push-off was similar: about 450 J, with a peak power output close to 3000 W. In the bonobo, most of the mechanical output was generated at the hips. To account for the mechanical output, the muscles actuating the bonobo's hips (directly and indirectly) must deliver muscle-mass-specific power and work output of 615 Wkg-1 and 92 Jkg-1, respectively. This was twice the output expected on the basis of muscle mass specific work and power in other jumping animals but seems physiologically possible. We suggest that the difference is due to a higher specific force (force per unit of cross-sectional area) in the bonobo.     

No correlation between time-linked plasma and CSF Aβ levels

Plasma β-amyloid protein (Aβ) isoforms are considered potential biomarkers for Alzheimer's disease (AD) and dementia. The relation between plasma and cerebrospinal fluid (CSF) levels of Aβ isoforms remains unclear. In order to identify possible correlations between Aβ levels in plasma and CSF we determined Aβ levels in time-linked plasma and CSF samples. Aβ concentrations in plasma (Aβ_1–42 and Aβ_N–42) and CSF (Aβ_1–42) samples from 49 AD patients, 47 non-Alzheimer's disease dementia (NONAD) patients, 39 MCI patients and 29 controls were determined using a multi-parameter fluorimetric bead-based immunoassay using xMAP^® technology (for plasma) and a conventional single-parameter ELISA (for CSF). Plasma Aβ_1–42 concentrations did not correlate with CSF Aβ_1–42 concentrations in the total study population, or in the different diagnostic groups. No correlations between plasma Aβ_N–42 and CSF Aβ_1–42 levels were found either. The CSF/serum albumin index did not show any significant differences between AD, NONAD, MCI and controls.These results suggest that the Aβ levels in plasma are independent of the Aβ levels in CSF both in dementia and controls. The fact that CSF and plasma Aβ do not correlate in patients as well as controls and no significant differences in plasma Aβ_1–42 or Aβ_N–42 between patients and controls can be detected hampers the diagnostic utility of the plasma Aβ levels as biomarkers for dementia.     

Neighbour identity hardly affects litter-mixture effects on decomposition rates of New Zealand forest species

The mass loss of litter mixtures is often different than expected based on the mass loss of the component species. We investigated if the identity of neighbour species affects these litter-mixing effects. To achieve this, we compared decomposition rates in monoculture and in all possible two-species combinations of eight tree species, widely differing in litter chemistry, set out in two contrasting New Zealand forest types. Litter from the mixed-species litter bags was separated into its component species, which allowed us to quantify the importance of litter-mixing effects and neighbour identity, relative to the effects of species identity, litter chemistry and litter incubation environment. Controlling factors on litter decomposition rate decreased in importance in the order: species identity (litter quality) >> forest type >> neighbour species. Species identity had the strongest influence on decomposition rate. Interspecific differences in initial litter lignin concentration explained a large proportion of the interspecific differences in litter decomposition rate. Litter mass loss was higher and litter-mixture effects were stronger on the younger, more fertile alluvial soils than on the older, less-fertile marine terrace soils. Litter-mixture effects only shifted percentage mass loss within the range of 1.5%. There was no evidence that certain litter mixtures consistently showed interactive effects. Contrary to common theory, adding a relatively fast-decomposing species generally slowed down the decomposition of the slower decomposing species in the mixture. This study shows that: (1) species identity, litter chemistry and forest type are quantitatively the most important drivers of litter decomposition in a New Zealand rain forest; (2) litter-mixture effects—although statistically significant—are far less important and hardly depend on the identity and the chemical characteristics of the neighbour species; (3) additive effects predominate in this ecosystem, so that mass dynamics of the mixtures can be predicted from the monocultures.     

Modulation and variability of prey capture kinematics in clariid catfishes

Species with narrow or limited diets (trophic specialists) are expected to be less flexible in their feeding repertoire compared to species feeding on a wide range of different prey (trophic generalists). The ability to modulate prey capture kinematics in response to different prey types and prey position, as well as the overall variability in prey capture kinematics, is evaluated in four clariid species ranging from trophic generalist (Clarias gariepinus) to species with morphological specializations and a narrow diet (Channallabes apus and Gymnallabes typus). High-speed video recordings were made of prey captures on two prey that differ in shape, attachment strength and hardness. While the observed amount of strike-to-strike variability in prey capture kinematics is similar for all species and not influenced by prey type, only the two less specialized species showed the ability to modulate their prey capture kinematics in function of the presented prey types. All species did, however, show positional modulation during the strike by adjusting the magnitude of neurocranial elevation. These results indicate that the narrow dietary breadth of trophic specialists is indeed indicative of functional stereotypy in this group of fishes. Although most studies focussing on prey processing found a similar result, the present study is one of the few that was able to demonstrate this relationship when focussing on prey capture mechanics. Possibly, this relationship is less frequently observed for prey capture compared to prey processing because, regardless of prey type, the initial capture of prey requires a higher amount of variability.     

Plant responses to rising water tables and nutrient management in calcareous dune slacks

Plant species of oligotrophic wet dune slacks have dramatically decreased as a result of desiccation and eutrophication. The aim of this study was to test in a field experiment the effects of restoration management in oligotrophic, wet dune slacks (groundwater level rise in combination with topsoil removal or mowing) on abiotic variables and on survival and biomass of four plant species. The effect of groundwater level rise on abiotic variables strongly differed between mown sampling locations and those with topsoil removal. At locations with a mowing treatment, a large rise in water tables led to increased N availability and higher reduced iron concentrations than at other locations. Such effects were absent at locations with recent topsoil removal. No effect of groundwater level rise on P-availability was found. Topsoil removal on average lowered N availability by 13%, P availability by 65% and Fe²⁺ by 56%. All phytometer species survived better in mown dune slacks than in dune slacks that had received topsoil removal. Survival of all species was negatively related to groundwater level rise. On the short term local extinction risks of small populations may be enhanced by rewetting and topsoil removal. On the long-term, however, such measures are crucial to maintain vegetation of oligotrophic wet dune slacks in a degraded dune landscape.     

Gene prioritization through genomic data fusion

The identification of genes involved in health and disease remains a challenge. We describe a bioinformatics approach, together with a freely accessible, interactive and flexible software termed Endeavour, to prioritize candidate genes underlying biological processes or diseases, based on their similarity to known genes involved in these phenomena. Unlike previous approaches, ours generates distinct prioritizations for multiple heterogeneous data sources, which are then integrated, or fused, into a global ranking using order statistics. In addition, it offers the flexibility of including additional data sources. Validation of our approach revealed it was able to efficiently prioritize 627 genes in disease data sets and 76 genes in biological pathway sets, identify candidates of 16 mono- or polygenic diseases, and discover regulatory genes of myeloid differentiation. Furthermore, the approach identified a novel gene involved in craniofacial development from a 2-Mb chromosomal region, deleted in some patients with DiGeorge-like birth defects. The approach described here offers an alternative integrative method for gene discovery.     

Does initial litter chemistry explain litter mixture effects on decomposition?

Abstract We tested the hypothesis that interactions in litter mixtures (expressed as the difference between observed and expected decomposition rates) are greater when the component species differ more in their initial litter chemistry. Thereto, we collected freshly senesced leaf litter from a wide range of species from an old field and woodland vegetation, and a fen ecosystem in The Netherlands. Litterbags with either mono-specific litter (20 and 15 species), or litter mixtures (50 and 42 species pairs) of randomly drawn combinations of two representatives from different plant functional types were incubated for 20, 35 and 54 weeks in a purpose-built decomposition bed (woodland/old field) or in the field (fen). Species showed a wide range of decomposition rates. For the woodland/old field species, initial litter C and P concentrations were significantly correlated with litter decomposition rate. For the fen species, litter phenolics concentration was correlated with decomposition rate. If the Sphagnum species were left out of the analyses, initial litter P and phenolics concentration both showed a significant relationship, albeit only with the remaining mass after 1 year. Differences between observed and expected decomposition were often considerable in individual litter mixtures. Regression analysis showed that such differences were not related to the differences in litter chemistry of the component species. Furthermore, litter mixtures containing species with very different initial litter chemistry did not show stronger interaction when tested against litter mixtures containing chemically similar litter types. From these observations we conclude that the difference in initial single litter chemistry parameters of the component is not a useful concept to explain interactions in litter mixtures.Due to an error in the citation line, this revised PDF (published in December 2003) deviates from the printed version, and is the correct and authoritative version of the paper.     

Differential microorganism-induced mannose-binding lectin activation

Mannose-binding lectin (MBL) is a serum complement factor playing a dominant role in first-line defense. When MBL binds to specific sugar moieties on microorganisms, the lectin complement pathway (LCP) is activated. Changes in the mbl gene and promotor may result in MBL with less activity, predisposing the individual to recurrent infections. Using a functional MBL assay, we investigated at what concentration different microbes activated MBL. Less than 1 colony-forming unit (CFU) of Neisseria meningitidis groups B and C still activated MBL, which may be ascribed to filterable blebs. Nocardia farcinica and Legionella pneumophila activated MBL well, which raises new questions about host susceptibility. In contrast to other research, Pseudomonas aeruginosa activated the LCP potently.