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injections, a distinct effect on melanocyte patterning was observed. Specifically, the ErBb/Kit
dependent regenerative pool of melanocytes that populate the lateral mid-line around 36-38
hpf were found to be significantly decreased in numbers. Further, the Tg Ftyrp:GFP line was used
to estimate the number and positioning of the total number of differentiated melanocytes (both
pigmented and non-pigmented). Here, it was observed that GFP+ve melanocytes were
accumulated near the trunk region and were significantly delayed in their migration towards the
tail at 48hpf. Therefore, to observe melanocytes during early induction of precursor migration
TgMitfa:GFP line was used. PlxnD1 morphants in Tg Mitfa:GFP line failed to migrate well in the
dorso-ventral axis between 24-36 hpf. This was quantified as their displacement from doral end
to ventral end in the trunk region of the embryo. Plxnd1 knock-down specifically affected
melanocyte migration in the dorso-ventral axis depleting the total number of regeneration
competent midline melanophores. To investigate the long-term effect and role of PlxnD1 in
regeneration and adult melanocyte patterning, the PlxnD1 CRISPR KOs are being generated.
Further, the cognate ligands of PlxnD1 receptor were individually knocked down to identify the
PlxnD1 signaling partner in this context. Sema3e knockdown phenocopies the effects of PlxnD1
morpholino with respect to melanocyte migration. This prompted the further study of both
Plxnd1 and Sema3e in greater detail. Melanocyte regeneration and patterning: Melanocytes are
terminally differentiated cell types with very limited potential to proliferate. Humans retain a
small pool of melanocyte stem cells within the hair follicle bulge that gets depleted with each
follicle cycle. However, in order to tap in their total potential in repopulating the epidermal
melanocytes it is important to understand inclination to respond to various guidance cues.
Subsequent to previous observation of a possible role of Plxnd1 in maintenance of melanocyte
regenerative pool (ErBb/Kit dependent melanocytes) in zebrafish embryos, its role in melanocyte
regeneration is now set to be understood. Various chemical treatments are known to specifically
ablate melanocytes from developed tissue. MoTP (toxic quinone, that kills actively melanising
cells) was used to ablate melanocyte in zebrafish larvae and neocuproine (NCP, copper chelator,
kills only mature terminally differentiated melanocytes) to ablate melanocyte in adult zebrafish.
In either case, upon returning the fish to freshwater, melanocyte regeneration ensues, and
normal pigment pattern eventually returns. Further aim is to intervene the regeneration, by
knocking down plexin D1 or by over-expressing Sema3e to study their respective effects on
melanocyte repopulation.

AN INVESTIGATION TOWARDS UNDERSTANDING THE ROLE OF MELANOCYTES
IN SKIN WOUND HEALING OF GUINEA PIGS

Wound healing in skin is a complex process that requires spatiotemporal interplay of cells of
different lineages. It is an integrated, dynamic process consisting of multiple temporally and
spatially overlapping but distinct phases, namely hemostasis, inflammation, re-epithelialization,
and remodeling. The project conducted in Archana Singh’s laboratory, aims to develop a guinea
pig model to study cutaneous tissue repair to especially investigate if epidermal melanocytes
influence the wound healing kinetics of skin. The guinea pig model overcomes the caveat of
absence of epidermal melanocytes present in mouse or rat models. Pigmented and depigmented
skin of guinea pigs for melanocyte presence, melanosome content, keratinocyte stratification
were analyzed at its basal state (without wound) and at 6 different days post wound (full-

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