  In this study, we report on a detailed single pulse analysis of the radio
emission from the pulsar J1401$-$6357 (B1358$-$63) based on data observed with
the ultrawideband low-frequency receiver on the Parkes radio telescope. In
addition to a weak leading component, the integrated pulse profile features a
single-humped structure with a slight asymmetry. The frequency evolution of the
pulse profile is studied. Well-defined nulls, with an estimated nulling
fraction greater than 2\%, are present across the whole frequency band. No
emission is detected with significance above 3$\sigma$ in the average pulse
profile integrated over all null pulses. Using fluctuation spectral analysis,
we reveal the existence of temporal-dependent subpulse drifting in this pulsar
for the first time. A clear double-peaked feature is present at exactly the
alias border across the whole frequency band, which suggests that the apparent
drift sense changes during the observation. Our observations provide further
confirmation that the phenomena of pulse nulling and subpulse drifting are
independent of observing frequency, which suggest that they invoke changes on
the global magnetospheric scale.
