Volume and antimicrobial activity of secretions of the uropygial gland are correlated with malaria infection in house sparrows.
BACKGROUND
Animals have developed a wide range of defensive mechanisms against parasites to reduce the likelihood of infection and its negative fitness costs. The uropygial gland is an exocrine gland that produces antimicrobial and antifungal secretions with properties used as a defensive barrier on skin and plumage. This secretion has been proposed to affect the interaction between avian hosts and their ectoparasites. Because uropygial secretions may constitute a defense mechanism against ectoparasites, this may result in a reduction in prevalence of blood parasites that are transmitted by ectoparasitic vectors. Furthermore, other studies pointed out that vectors could be attracted by uropygial secretions and hence increase the probability of becoming infected. Here we explored the relationship between uropygial gland size, antimicrobial activity of uropygial secretions and malaria infection in house sparrows Passer domesticus.


METHODS
A nested-PCR was used to identify blood parasites infection. Flow cytometry detecting absolute cell counting assessed antimicrobial activity of the uropygial gland secretion


RESULTS
Uninfected house sparrows had larger uropygial glands and higher antimicrobial activity in uropygial secretions than infected individuals. We found a positive association between uropygial gland size and scaled body mass index, but only in uninfected sparrows. Female house sparrows had larger uropygial glands and higher antimicrobial activity of gland secretions than males.


CONCLUSIONS
These findings suggest that uropygial gland secretions may play an important role as a defensive mechanism against malaria infection.
Departamento de Anatomía Biología Celular y Zoología, Universidad de Extremadura, Avda. de Elvas s/n, E-06006, Badajoz, Spain.
Sergio
S
Magallanes
Laboratoire d'Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, Bâtiment 362, F-91405, Orsay Cedex, France.
Anders Pape
AP
Møller
Departamento de Anatomía Biología Celular y Zoología, Universidad de Extremadura, Avda. de Elvas s/n, E-06006, Badajoz, Spain.
Luz
L
García-Longoria
Departamento de Anatomía Biología Celular y Zoología, Universidad de Extremadura, Avda. de Elvas s/n, E-06006, Badajoz, Spain.
Florentino
F
de Lope
Departamento de Anatomía Biología Celular y Zoología, Universidad de Extremadura, Avda. de Elvas s/n, E-06006, Badajoz, Spain. amarzal@unex.es.
Alfonso
A
Marzal
D000818:Animals; D000890:Anti-Infective Agents / Q000378:metabolism*; D012634:Bodily Secretions / Q000378:metabolism*; D005260:Female; D008289:Malaria, Avian / Q000469:parasitology*; D008297:Male; D012737:Sex Factors; D046370:Sparrows
D000890:Anti-Infective Agents
Antimicrobial activity; Flow cytometry; Haemosporidian parasites; Passer domesticus; Preen gland