24 research outputs found
The Effect of Diet and Opponent Size on Aggressive Interactions Involving Caribbean Crazy Ants (Nylanderia fulva)
Biotic interactions are often important in the establishment and spread of invasive species. In particular, competition
between introduced and native species can strongly influence the distribution and spread of exotic species and in some
cases competition among introduced species can be important. The Caribbean crazy ant, Nylanderia fulva, was recently
introduced to the Gulf Coast of Texas, and appears to be spreading inland. It has been hypothesized that competition with
the red imported fire ant, Solenopsis invicta, may be an important factor in the spread of crazy ants. We investigated the
potential of interspecific competition among these two introduced ants by measuring interspecific aggression between
Caribbean crazy ant workers and workers of Solenopsis invicta. Specifically, we examined the effect of body size and diet on
individual-level aggressive interactions among crazy ant workers and fire ants. We found that differences in diet did not alter
interactions between crazy ant workers from different nests, but carbohydrate level did play an important role in
antagonistic interactions with fire ants: crazy ants on low sugar diets were more aggressive and less likely to be killed in
aggressive encounters with fire ants. We found that large fire ants engaged in fewer fights with crazy ants than small fire
ants, but fire ant size affected neither fire ant nor crazy ant mortality. Overall, crazy ants experienced higher mortality than
fire ants after aggressive encounters. Our findings suggest that fire ant workers might outcompete crazy ant workers on an
individual level, providing some biotic resistance to crazy ant range expansion. However, this resistance may be overcome
by crazy ants that have a restricted sugar intake, which may occur when crazy ants are excluded from resources by fire ants
Promoter regions of Plasmodium vivax are poorly or not recognized by Plasmodium falciparum
BACKGROUND: Heterologous promoter analysis in Plasmodium has revealed the existence of conserved cis regulatory elements as promoters from different species can drive expression of reporter genes in heterologous transfection assays. Here, the functional characterization of different Plasmodium vivax promoters in Plasmodium falciparum using luciferase as the reporter gene is presented. METHODS: Luciferase reporter plasmids harboring the upstream regions of the msp1, dhfr, and vir3 genes as well as the full-length intergenic regions of the vir23/24 and ef-1α genes of P. vivax were constructed and transiently transfected in P. falciparum. RESULTS: Only the constructs with the full-length intergenic regions of the vir23/24 and ef-1α genes were recognized by the P. falciparum transcription machinery albeit to values approximately two orders of magnitude lower than those reported by luc plasmids harbouring promoter regions from P. falciparum and Plasmodium berghei. A bioinformatics approach allowed the identification of a motif (GCATAT) in the ef-1α intergenic region that is conserved in five Plasmodium species but is degenerate (GCANAN) in P. vivax. Mutations of this motif in the P. berghei ef-1α promoter region decreased reporter expression indicating it is active in gene expression in Plasmodium. CONCLUSION: Together, this data indicates that promoter regions of P. vivax are poorly or not recognized by the P. falciparum transcription machinery suggesting the existence of P. vivax-specific transcription regulatory elements