Search Results - (Author, Cooperation:T. Moens)

2014-08-12

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Amyotrophic Lateral Sclerosis/*genetics/pathology ; Animals ; Cell Line, Tumor ; DNA Repeat Expansion/*genetics ; Dipeptides/metabolism ; Disease Models, Animal ; Drosophila melanogaster/*genetics ; Escherichia coli ; Frontotemporal Dementia/*genetics/pathology ; Humans ; Neurons/metabolism/pathology ; Proteins/*genetics

0022-5320

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract A recent review suggests that meiofauna are important grazers of microphytobenthic primary production as well as of bacterial secondary production. The potential importance of meiofauna grazers may nevertheless have systematically been underestimated, since label leakage from chemically preserved animals has hitherto not been accounted for. Furthermore, a majority of studies have used relatively long incubation times and assumed, rather than proved, that label recycling over this period is negligible. In the present study we tested the influence of sample preservation on label retention in the marine nematode Pellioditis marina Andrassy, 1983 fed 3H-labelled bacteria. Label loss from formaldehyde-preserved specimens averaged 40% after 1 h preservation and amounted to a maximum of 85% after 24 h in formaldehyde, irrespective of formaldehyde concentration; no further leakage occurred beyond 24 h. Glutaraldehyde and ethanol yielded significantly better and poorer results, respectively, but the former fixative still yielded label losses of up to 70%. A comparison of label uptake as a function of time with observations on ingestion and defecation behaviour suggest that on time scales of hours an indication of assimilation (after correction for label leakage) rather than of ingestion is obtained. When killed with formaldehyde at room temperature, P. marina egested a significant part of its gut contents. The sources of bias identified here may have generally led to significant underestimations of true grazing rates. The cumulative effect of label leakage, prey egestion and long incubation times, each at the highest rates observed in this study, may yield as much as a 15-fold underestimation of true food consumption. Cooling samples on ice and fixation with ice-cold formaldehyde, followed by immediate freeze-preservation, and sorting of the nematodes within 2 h after thawing, gives average values for label leakage of 50%, and hence allows the application of a proximate correction factor for label losses of 2.

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract This paper reports on the feeding biology of a predatory and of a facultatively predatory nematode, Enoploides longispiculosus and Adoncholaimus fuscus, respectively. Both species represent genera which are common and abundant in the littoral of the North Sea and in adjacent estuaries. Observations on the foraging behaviour of both species are given, and for the former species, a range of prey from its natural habitat is identified. Respiration was determined using a polarographic oxygen electrode technique and compared to consumption determined as predation rates on the monhysterid nematode Diplolaimelloides meyli. The daily C-loss due to respiration accounted for 15% of the measured C-consumption in E. longispiculosus and for 111% in A. fuscus, proving the observed feeding rates in the latter species to have been inadequate for the maintenance of its aerobic metabolism. Daily respiration rates at an average environmental temperature were 219 ng C ind−1 d−1 for adults of A. fuscus and 21.9 ng C ind−1 d−1 for adults of E. longispiculosus. Using radiotracer techniques, no uptake of bacterial cells or of organic matter in the dissolved phase was demonstrated for E. longispiculosus. In A. fuscus, however, a significant drinking of label in the dissolved or volatile fraction occurred; bacterial cells were taken up at a level insignificant to the nematode's daily C-ration. It is concluded that E. longispiculosus has a fairly strict predatory feeding strategy, while A. fuscus gains a majority of C from additional foraging strategies, among which the uptake of dissolved material and scavenging on macrofauna carcasses (as reported in the literature) may be of particular importance.

Electronic Resource

1432-2242

Key words Wheat ; Triticum aestivum ; Transformation ; Nuclear male sterility ; DNA-integration

Springer Online Journal Archives 1860-2000

Biology

Abstract  Nuclear male sterility within Triticum aestivum is considered as the ideal basis for the development of a hybridization system for wheat. We engineered nuclear male sterility in wheat by introducing the barnase gene under the control of tapetum-specific promoters derived from corn and rice. A biolistic-mediated transformation method, based on the use of the poly(ADP-ribose)polymerase inhibitor niacinamide, was set up which enriched for low-copy integrations (1–3 copies). Most of these copies were not linked and segregated in the next generation.

Electronic Resource