Walter M. Robertson

Scottish Crop Research Institute; Dundee, United Kingdom

CZ4734

Caenorhabditis elegans

CZ4733

Caenorhabditis elegans

CZ5847

Caenorhabditis elegans

Blaxter ML et al. "The Cuticle."

Robertson WM, Blaxter ML

The nematode cuticle, like the endo- and exo-skeletons of other animals, is much more than just an inert structure against which muscles can act during locomotion. The cuticle performs complex roles in organismal physiology, protection from the environment, nutrition and excretion. Cuticle composition and structure reflects this complexity. In this chapter we review briefly the ultrastructure of the cuticle and examine the biochemistry and genetics of the components of nematode cuticles. We also discuss the cuticle as a dynamic structure, both over the lifetime of the nematode (through the moults) and on shorter timescales.

TX895

Caenorhabditis elegans

CZ9236

Caenorhabditis elegans

TX335

Caenorhabditis elegans

Young IM et al. (1998) European Journal of Soil Science "Nematode (Caenorhabditis elegans) movement in sand as affected by particle size, moisture and the presence of bacteria (Escherichia coli)."

Griffiths BS, McNicol JW, Robertson WM, Young IM

[European Journal of Soil Science, 1998]

The movement of bacterial-feeding nematodes (Caenorhabditis elegans) through sand was investigated using a range of sand sizes, equilibrated at a range of matric potentials, in the presence or absence of an attractant source (Escherichia coli) at the distal end of a column. In the presence of E. coli there was significantly greater movement of the nematode population towards the E. coli population, and the extent of the movement depended on the matric potential of the sand. Over time, an increasing proportion of the C. elegans population responded to the presence of the E. coli. The processes controlling these effects are discussed with respect to taxis and kinesis mechanisms of the nematode population, and with regard to the diffusive characteristics of the physical structure of the sand.

Anderson ARA et al. (1997) Fundamental and Applied Nematology "Nematode movement along a chemical gradient in a structurally heterogeneous environment. 1. Experiment."

Young IM, Anderson ARA, Sleeman BD, Robertson WM, Griffiths BS

[Fundamental and Applied Nematology, 1997]

The interaction between soil structural heterogeneity and chemical gradients, and their effect on the movement of free-living nematodes was investigated. Four experimental treatments were used. These consisted of a nematode (Caenorhabditis elegans) on a homogeneous layer of nutrient agar in a Petri dish, with or without a localised bacterial food source (Escherichia coli) acting as an attractant. Structural heterogeneity was then introduced by adding a monolayer of sand grains onto both of the homogeneous treatments. AU trails were recorded using time-lapse video, and subsequently digitised prior to analysis. Turning angle distributions and the fractal dimension of the trails were calculated for each treatment. There was a statistically significant effect (P less than or equal to 0.01) of all treatments on the movement of the nematode. In the presence of the attractant, nematode movement was more linear and directed towards the bacterial source. Structural heterogeneity caused the nematode to have more linear movement compared to a homogeneous environment. The fractal dimension of the nematode trails was significantly higher (P less than or equal to 0.01) for the treatment without structure or bacteria, than for the other treatments. The results, for the first time, quantify the degree to which nematodes carry out random foraging type behaviour in a homogeneous environment and produce more directed non-random movement in the presence of attractant. Finally, when structure is present the foraging strategy becomes more of an avoidance strategy, allowing the nematode to escape structural traps, such as ''dead-end'' pores, and then continue to react to attractant gradients.