Hummingbirds and their flowers in the coastal mountains of southeastern Brazil

Summary Observations were made on the nectar-feeding of hummingbirds in three areas of natural forest in the coastal mountains of southeastern Brazil. Five of the seven hummingbird species observed are endemic to the region. The observations are summarised and discussed, and limited comparison is made with the feeding ecology of Andean hummingbirds. The data suggest that two plant families of prime importance in temperate forest in the Andes, the Rubiaceae and Ericaceae, are unimportant in southeastern Brazilian montane forest. The close fit between the bill ofPhaethornis eurynome and the corollas of three species of plants suggests coevolution. The data presented are preliminary and incomplete, and indicate the need for more thorough research into the relationships between hummingbirds and plants in this region.

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Kolibris und die von ihnen besuchten Blüten im Küstengebirge Südostbrasiliens

Zusammenfassung Die Beobachtungen über blütenbesuchende Kolibris stammen aus drei Naturwaldgebieten im Küstengebirge Südostbrasiliens. 5 der 7 beobachteten Kolibriarten sind in dieser Region endemisch. Die Zusammenfassung der Beobachtungen gestattet unter Einschränkung gewisse Vergleiche mit der Nahrungsökologie andiner Kolibris. Die Daten machen wahrscheinlich, daß Rubiaceae und Ericaceae, zwei Pflanzenfamilien von vorrangiger Bedeutung in den Wäldern der gemäßigten Zone der Anden, im südostbrasilianischen Bergwald unwichtig sind. Die enge Anpassung des Schnabels vonPhaethornis eurynome an die Gestalt der Blütenkrone dreier Pflanzenarten läßt Koevolution vermuten. Die Beobachtungen sind jedoch unvollständig und forden weitere intensive Untersuchung der Beziehungen zwischen Kolibris und Pflanzen in den bearbeiteten Gebieten.

     

Distribution and infection of triatomines (Hemiptera: Reduviidae) by Trypanosoma cruzi in the state of Michoacán, Mexico

An entomological study of triatomine species was carried out to assess their prevalence in 10 localities of the state of Michoacán, Mexico. Entomological indices were calculated to estimate the risk for vector-borne transmission of Trypanosoma cruzi to the human population in this area. Four triatomine species (Triatoma barberi, Triatoma dimidiata, Meccus pallidipennis and Meccus longipennis) were collected from the study area. This is the first report of M. longipennis and T. dimidiata in Michoacán. M. pallidipennis was significantly (p < 0.05) more abundant than any of the other species collected in the study area. Infection indices were greater than 50% for each of the four collected triatomine species. Significantly more triatomines were collected from intradomiciliary areas than from peridomiciliary or sylvatic areas. Infestation, crowding and density indices were low, whereas colonisation indices were high in five localities. The current vectorial conditions in the study area require continuous entomological and serological surveillance to diminish the risk of T. cruzi transmission to human populations.     

Identification of quantitative trait loci that affect endoreduplication in maize endosperm

Endoreduplication in maize endosperm precedes the onset of starch and storage protein synthesis, and it is generally thought to influence grain filling. We created four backcross populations by reciprocally crossing the F₁ progeny of a cross between Sg18 and Mo17 to the parental inbreds, which differ in endoreduplication by two parameters—mean ploidy and percentage of endoreduplicated nuclei. This four-backcross design allowed us to estimate and test the additive and dominant genetic effects of quantitative trait loci (QTLs) affecting endoreduplication. An analysis of endosperm from the four backcross populations at 16 days after pollination using a modified triploid mapping approach identified three endosperm QTLs influencing mean ploidy and two endosperm QTLs affecting the percentage of endoreduplicated nuclei. Some of these QTLs may manifest their effects on endoreduplication via expression in the embryo. The QTLs detected display strong dominance or over-dominance and interacted epistatically with an embryo-expressed QTL. This helps to explain the genetic basis for transgressive segregation in the backcross progeny. Although the favorable alleles that increase mean ploidy and percentage of endoreduplicated nuclei can be contributed by both parents, the Mo17-derived alleles for endoreduplication were often dominant or over-dominant to the Sg18-derived allele. One QTL on chromosome 7 that may be expressed in both the embryo and endosperm exerted a pleiotropic effect on two different parameters of endoreduplication. The results from this study shed light on the regulation of endoreduplication in maize endosperm and provide a marker-assisted selection strategy for potentially improving grain yield. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. C. M. Coelho and S. Wu contributed equally to this work and should be considered as first authors.     

Association between Knops blood group polymorphisms and susceptibility to malaria in an endemic area of the Brazilian Amazon

Complement receptor 1 (CR1) gene polymorphisms that are associated with Knops blood group antigens may influence the binding of Plasmodium parasites to erythrocytes, thereby affecting susceptibility to malaria. The aim of this study was to evaluate the genotype and allele and haplotype frequencies of single-nucleotide polymorphisms (SNPs) of Knops blood group antigens and examine their association with susceptibility to malaria in an endemic area of Brazil. One hundred and twenty-six individuals from the Brazilian Amazon were studied. The CR1-genomic fragment was amplified by PCR and six SNPs and haplotypes were identified after DNA sequence analysis. Allele and haplotype frequencies revealed that the Kn(b) allele and H8 haplotype were possibly associated with susceptibility to Plasmodium falciparum. The odds ratios were reasonably high, suggesting a potentially important association between two Knops blood antigens (Kn(b) and KAM(+)) that confer susceptibility to P. falciparum in individuals from the Brazilian Amazon.