Biology Reference
In-Depth Information
globins.No genomes are available for theCentroheliozoa,Glaucocystophyceae,
Jakobida, Katablepharidophyta and Malawimonadidae. The Haptophyceae are
represented by the genome of
Emiliania huxleyi
, a unicellular phytoplankton
covered with extraordinary calcium carbonate discs, one of the most abundant
andwidely distributed coccolithophores, with a global distribution fromthe tro-
pics to subarctic waters. It is unique in having three SDgbs, three FHbs and a
chimeric protein with an unidentified N-terminus, four TrHb1 domains and
a C-terminal von Willebrand factor (vWF) type A domain (
Sadler, 1998
).
The physiological basis of this wealth of globins is unknown.
4.6. Opisthokonta
The Opisthokonta comprise metazoans (animals), fungi and several addi-
tional microbial eukaryote lineages, including the Choanoflagellida,
Ichthyosporea, Nucleariidae and Capsaspora. It is likely that the closest
extant relative of both fungi and metazoans is a member of the
Opisthokonta. Furthermore, it appears that the closest relatives of metazoans
are the choanoflagellates, followed by the Capsaspora and Ichthyosporea lin-
eages (
Ruiz-Trillo, Roger, Burger, Gray, & Lang, 2008
). Recently, the
genomes of five, close relatives of fungi and metazoa have been sequenced,
as part of the Origin of Multicellularity Project at the Broad Institute (
Ruiz-
Trillo et al., 2007
). These include
Capsaspora owczarzaki
, an amoeboid par-
asite of the pulmonate snail
Biomphalaria glabrata
, which has a relatively small
genome about 22-25 Mbp (
Ruiz-Trillo, Lane, Archibald, & Roger, 2006
),
the apusozoan
T. trahens
(formerly
Amastigomonas
sp. ATCC 50062), two
choanoflagellates,
Salpingoeca rosetta
(formerly
Proterospongia
sp. ATCC
50818) and
Monosiga brevicollis
, and two basal fungi,
Allomyces macrogynus
and
Spizellomyces punctatus
. Although these genomes contain globins,
T
.
trahens
has only one FHb, and
A. macrogynus
has two SSDgbs and a chi-
meric globin with a C-terminal TrHb1 domain. The ichthyosporean
Sphaeroforma arctica
has five SDgbs and an FHb, while
C. owczarzaki
has
two chimeric two-SDgb domain proteins (
Table 9.3
). No nucleariid
genomes are available. The two available choanoflagellate genomes, each
encode three SDgbs. It is worth pointing out that a hypothetical protein
of 1653 amino acids PTSG_01043 (EGD76343.1) can be identified in
S. rosetta
(
Salpingoeca
sp. ATCC 50818) via BLASTP search using
Stron-
gylocentrotus purpuratus
androglobin (isoform 1; XP_001186225.2). Whereas
the N-terminal cysteine protease domain is present, the central globin
domain is not identified by either BLASTP or FUGUE searches. Although
