  We study the influence of environment on the structure of disc galaxies,
using \texttt{IMFIT} to measure the g- and r-band structural parameters of the
surface-brightness profiles for $\sim$700 low-redshift (z$<$0.063) cluster and
field disc galaxies with intermediate stellar mass (0.8 $\times$ 10$^{10}$
$M_{\odot}$ $<$ $M_{\star}$ $<$ 4 $\times$ 10$^{10}$ $M_{\odot}$) from the
Sloan Digital Sky Survey, DR7. Based on this measurement, we assign each galaxy
to a surface-brightness profile type (Type I $\equiv$ single-exponential, Type
II $\equiv$ truncated, Type III $\equiv$ anti-truncated). In addition, we
measure (g-r) restframe colour for disc regions separated by the break radius.
Cluster disc galaxies (at the same stellar mass) have redder (g-r) colour by
$\sim$0.2 mag than field galaxies. This reddening is slightly more pronounced
outside the break radius. Cluster disc galaxies also show larger global
S\'ersic-indices and are more compact than field discs, both by $\sim$15\%.
This change is connected to a flattening of the (outer) surface-brightness
profile of Type I and - more significantly - of Type III galaxies by $\sim$8\%
and $\sim$16\%, respectively, in the cluster environment compared to the field.
We find fractions of Type I, II and III of (6$\pm$2)\%, (66$\pm$4)\% and
(29$\pm$4)\% in the field and (15$_{-4}^{+7}$)\%, (56$\pm$7)\% and (29$\pm$7)\%
in the cluster environment, respectively. We suggest that the larger abundance
of Type I galaxies in clusters (matched by a corresponding decrease in the Type
II fraction) could be the signature of a transition between Type II and Type I
galaxies produced/enhanced by environment-driven mechanisms.
