Biology Reference
In-Depth Information
An FHb (GenBank Accession No. FJ874761) has been briefly reported
to be expressed in Cylindrocarpon ( Kim, Fushinobu, Zhou, Wakagi, &
Shoun, 2010 ), a common soil-borne fungus, which causes root rot in many
plant species, but this sequence was not found in our analyses.
6.4. Protozoa
The anti-parasitic effects of nitric oxide have been widely documented in
Protozoa and Metazoa (reviewed in Ascenzi, Bocedi, & Gradoni, 2003 );
however, the defence mechanisms against NO and RNS that must be asso-
ciated with efficient invasion and colonization of the host by pathogens are
incompletely understood. In pathogenic bacteria, the presence of
haemoglobins (e.g. FHb in E. coli and Salmonella , a TrHb in Mycobacterium
tuberculosis and an SDgb in Campylobacter jejuni ; for a review see Bowman
et al., 2011 ) represents the main mechanisms involved in resistance to
nitrosative stress ( Bowman et al., 2011; Vinogradov et al., 2013 ). On the
other hand, a number of pathogenic protozoal genomes lack globin-like
sequences (Supplementary Table S1 at http://www.elsevierdirect.com/
companions/9780124076938 ) . For instance, production by iNOS of NO
from L -arginine by human macrophages is involved in Leishmania killing
( Green, Meltzer, Hibbs, & Nacy, 1990; Liew, Millott, Parkinson,
Palmer, & Moncada, 1990 ). However, evasion and survival strategies of
the protozoan include the suppression of the iNOS induction and the entry
into iNOS-negative target cells ( Bogdan, Gessner, Solbach, & Rollinghoff,
1996 ). Clinical manifestations of American tegumentary leishmaniasis
(ATL) in the New World are mainly associated with Leishmania ( Viannia )
braziliensis and Leishmania ( Leishmania ) mexicana and NO-resistant isolates
of these parasites have been reported and related to disease severity
( Giudice et al., 2007 ). The lack of globin-like sequences in the L . braziliensis
genome indicates a different, unidentified mechanism(s) to detoxify NO but
L. mexicana does have sequences encoding two globin-like sensors; whether
these gene products are related to NO detoxification is unknown.
Activated macrophages kill Entamoeba histolytica trophozoites (Supple-
mentary Table S1 at http://www.elsevierdirect.com/companions/
9780124076938 ) mainly by NO production ( Denis & Chadee, 1989;
Lin, Seguin, Keller, & Chadee, 1994 ). The presence of NO severely
compromises the viability of this parasite by triggering an apoptosis-like
mechanism ( Ramos et al., 2007 ) producing profound morphological
modifications such as generation of vesicle-like structures of the atypical
Search WWH ::




Custom Search