Functional variation among frugivorous birds: implications for rainforest seed dispersal in a fragmented subtropical landscape

Seed dispersal plays a critical role in rainforest regeneration patterns, hence loss of avian seed dispersers in fragmented landscapes may disrupt forest regeneration dynamics. To predict whether or not a plant will be dispersed in fragmented forests, it is necessary to have information about frugivorous bird distribution and dietary composition. However, specific dietary information for frugivorous birds is often limited. In such cases, information on the seed-crushing behaviour, gape width and relative dietary dominance by fruit may be used to describe functional groups of bird species with respect to their potential to disperse similar seeds. We used this information to assess differences in the seed dispersal potential of frugivorous bird assemblages in a fragmented rainforest landscape of southeast Queensland, Australia. The relative abundance of frugivorous birds was surveyed in extensive, remnant and regrowth rainforest sites (16 replicates of each). Large-gaped birds with mixed diets and medium-gaped birds with fruit-dominated diets were usually less abundant in remnants and regrowth than in continuous forest. Small-gaped birds with mixed diets and birds with fruit as a minor dietary component were most abundant in regrowth. We recorded a similar number of seed-crushing birds and large-gaped birds with fruit-dominated diets across site types. Bird species that may have the greatest potential to disperse a large volume and wide variety of plants, including large-seeded plants, tended to be less abundant outside of extensive forests, although one species, the figbird Sphecotheres viridis, was much more abundant in these areas. The results suggest that the dispersal of certain plant taxa would be limited in this fragmented landscape, although the potential for the dispersal of large-seeded plants may remain, despite the loss of several large-gaped disperser species.     

Biodegradation of hydrocarbon cuts used for diesel oil formulation

The biodegradability of various types of diesel oil (DO), such as straight-run DO, light-cycle DO, hydrocracking DO, Fischer–Tropsch DO and commercial DO, was investigated in biodegradation tests performed in closed-batch systems using two microflorae. The first microflora was an activated sludge from an urban wastewater treatment plant as commonly used in biodegradability tests of commercial products and the second was a microflora from a hydrocarbon-polluted soil with possible specific capacities for hydrocarbon degradation. Kinetics of CO₂ production and extent of DO biodegradation were obtained by chromatographic procedures. Under optimised conditions, the polluted-soil microflora was found to extensively degrade all the DO types tested, the degradation efficiencies being higher than 88%. For all the DOs tested, the biodegradation capacities of the soil microflora were significantly higher than those of the activated sludge. Using both microflora, the extent of biodegradation was highly dependent upon the type of DO used, especially its hydrocarbon composition. Linear alkanes were completely degraded in each test, whereas identifiable branched alkanes such as farnesane, pristane or phytane were degraded to variable extents. Among the aromatics, substituted mono-aromatics were also variably biodegraded.     

A recent insertion of an alu element on the Y chromosome is a useful marker for human population studies

A member of the Alu family of repeated DNA elements has been identified on the long arm of the human Y chromosome, Yq11. This element, referred to as the Y Alu polymorphic (YAP) element, is present at a specific site on the Y chromosome in some humans and is absent in others. Phylogenetic comparisons with other Alu sequences reveal that the YAP element is a member of the polymorphic subfamily-3 (PSF-3), a previously undefined subfamily of Alu elements. The evolutionary relationships of PSF-3 to other Alu subfamilies support the hypothesis that recently inserted elements result from multiple source genes. The frequency of the YAP element is described in 340 individuals from 14 populations, and the data are combined with those from other populations. There is both significant heterogeneity among populations and a clear pattern in the frequencies of the insertion: sub-Saharan Africans have the highest frequencies, followed by northern Africans, Europeans, Oceanians, and Asians. An interesting exception is the relatively high frequency of the YAP element in Japanese. The greatest genetic distance is observed between the African and non-African populations. The YAP is especially useful for studying human population history from the perspective of male lineages.      

DNA methylation pattern of CALCA in preterm neonates with bacterial sepsis as a putative epigenetic biomarker

Diagnosis of bacterial sepsis in preterm neonates can be difficult when using serum markers that rely on physiological changes because these changes may not necessarily be the result of bacterial infections alone. This retrospective investigation explores the potential use of the DNA methylation pattern of CpG sites in the promoter region of the calcitonin-related polypeptide α (CALCA) gene as an epigenetic biomarker for bacterial sepsis in preterm newborns. Four novel changes in the DNA methylation of eight CpG sites were detected in this gene and are present only in neonates with bacterial sepsis: (1) partial methylation at -769 CpG in gram-negative or gram-positive early onset sepsis (EOS) and late onset sepsis (LOS) episodes; (2) demethylation of 8 CpGs in gram-negative EOS followed by LOS (ELS) and in gram-negative EOS; (3) demethylation of 7 CpGs in gram-positive ELS and gram-positive EOS; (4) -771 C:G > T:A; 5′ de novo -778 CpG mutation on both alleles in EOS. These changes were not detected in birth weight and gestational age matched controls or in newborns with isolated infections. Our results indicate that the DNA methylation pattern of the promoter region of the CALCA gene varies in different types of bacterial preterm sepsis, thus suggesting a potential use as an epigenetic biomarker. A prospective confirmation of these results is essential.     

Florivory increases selfing: an experimental study in the wild strawberry, Fragaria virginiana

Florivores are antagonists that damage flowers, and have direct negative effects on flowering and pollination of the attacked plants. While florivory has mainly been studied for its consequences on seed production or siring success, little is known about its impact on mating systems. Damage to flowers can alter pollinator attraction to the plant and may therefore modify patterns of pollen transfer. However, the consequences of damage for mating systems can take two forms: a decrease in flower number reduces opportunities for intra-inflorescence pollen deposition (geitonogamy), which, in turn, may lead to a decrease in selfing; whereas a decrease in floral display may also reduce overall visitation and thus increase the chances of self-pollination via facilitated or autonomous autogamy. We investigated the effects of damage by a bud-clipping weevil ( Anthonomus signatus ) in Fragaria virginiana in an experimental setting mimicking natural conditions. We found that increased damage led to an increase in selfing, a result consistent with the increased autogamy pathway. We discuss the implications of this finding and evaluate the generality of florivore-mediated mating system expression.