A. Abzhanov et Tc. Kaufman, Evolution of distinct expression patterns for engrailed paralogues in higher crustaceans (Malacostraca), DEV GENES E, 210(10), 2000, pp. 493-506
The segment-polarity gene engrailed of Drosophila melanogaster and its homo
logues in other arthropods possess a highly conserved expression domain in
the posterior portion of each segment. We report here that the two pan-spec
ific antibodies, Mab4D9 and Mab4F11, reveal strikingly different accumulati
on patterns in both of the malacostracan crustaceans Porcellio scaber (Isop
oda) and Procambarus clarkii (Decapoda), compared with insects. The signal
detected with Mab4D9 resides in the posterior part of each segment, includi
ng the appendages, the ventral and lateral sides of the trunk and the CNS.
However, Mab4F11 reveals a signal only in small groups of neurons in the CN
S and PNS, primarily localized in the pereon. We observe similar Mab4D9 and
Mab4F11 patterns in the crayfish P. clarkii, except that no Mab4F11 signal
is detected in the pleon. To address the possibility of multiple engrailed
paralogues, we cloned partial cDNAs of two engrailed genes, Ps-en1 and Ps-
en2, from P. scaber, and studied their expression patterns using whole-moun
t in situ hybridization. Although the Ps-en1 and Ps-en2 patterns are compar
able in early development, they become distinct in late embryogenesis. Ps-e
n1 is expressed in the CNS, where Mab4F11 stains, but also accumulates in t
he epidermis. In contrast, Ps-en2 is expressed in the lateral aspect and li
mbs of all segments. Phylogenetic analysis of en sequences from crustaceans
and insects suggests that the two en genes from the apterygote insect Ther
mobia domestica (Thysanura) may be related to en1 and en2 of higher crustac
eans.