  The presence of transitional dwarf galaxies in filaments and cluster
outskirts may be closely related to pre-processing in the filament; however,
the underlying mechanism is not yet comprehensively understood. We present the
spatially resolved chemical and kinematical properties of three blue-cored
dwarf early-type galaxies (dE(bc)s) in the Virgo cluster and Virgo-related
filaments (Crater & Virgo III) using the Sydney-AAO Multi-object Integral-field
spectrograph (SAMI) Galaxy Survey. We map the spatial distribution of H-alpha,
oxygen abundance (O/H), nitrogen-to-oxygen abundance ratio (N/O), stellar
population age, and gas-stellar internal kinematics. We find irregular shapes
of enhanced star-forming regions from the centers to the outlying regions of
blue cores in dE(bc)s. These regions are relatively metal-poor compared with
the surrounding regions, rendering the overall metallicity gradient of each
galaxy positive. Furthermore, they exhibit higher N/O ratios at a given O/H
relative to their surroundings, implying metal-poor gas infall by external
processes. The equivalent width of the H-alpha emission line in metal-poor
regions indicates young age of star formation, 6-8 Myr. The disturbed ionized
gas velocity field, one of the most prominent features of galaxy mergers is
also discovered in two dE(bc)s. We propose that a moderately dense filament
environment is favorable for the formation of blue cores in dEs, in which
dE(bc)s in filaments may have already been transformed before they fall into
the Virgo cluster. This process may contribute to the composition of galaxy
population at the outskirts of the cluster.
