Horizontal gene transfer of microbial cellulases into nematode genomes is associated with functional assimilation and gene turnover

<p>Abstract</p> <p>Background</p> <p>Natural acquisition of novel genes from other organisms by horizontal or lateral gene transfer is well established for microorganisms. There is now growing evidence that horizontal gene transfer also plays important roles in the evolution of eukaryotes. Genome-sequencing and EST projects of plant and animal associated nematodes such as <it>Brugia</it>, <it>Meloidogyne</it>, <it>Bursaphelenchus </it>and <it>Pristionchus </it>indicate horizontal gene transfer as a key adaptation towards parasitism and pathogenicity. However, little is known about the functional activity and evolutionary longevity of genes acquired by horizontal gene transfer and the mechanisms favoring such processes.</p> <p>Results</p> <p>We examine the transfer of cellulase genes to the free-living and beetle-associated nematode <it>Pristionchus pacificus</it>, for which detailed phylogenetic knowledge is available, to address predictions by evolutionary theory for successful gene transfer. We used transcriptomics in seven <it>Pristionchus </it>species and three other related diplogastrid nematodes with a well-defined phylogenetic framework to study the evolution of ancestral cellulase genes acquired by horizontal gene transfer. We performed intra-species, inter-species and inter-genic analysis by comparing the transcriptomes of these ten species and tested for cellulase activity in each species. Species with cellulase genes in their transcriptome always exhibited cellulase activity indicating functional integration into the host's genome and biology. The phylogenetic profile of cellulase genes was congruent with the species phylogeny demonstrating gene longevity. Cellulase genes show notable turnover with elevated birth and death rates. Comparison by sequencing of three selected cellulase genes in 24 natural isolates of <it>Pristionchus pacificus </it>suggests these high evolutionary dynamics to be associated with copy number variations and positive selection.</p> <p>Conclusion</p> <p>We could demonstrate functional integration of acquired cellulase genes into the nematode's biology as predicted by theory. Thus, functional assimilation, remarkable gene turnover and selection might represent key features of horizontal gene transfer events in nematodes.</p

Vacationers Happier, but Most not Happier After a Holiday

The aim of this study was to obtain a greater insight into the association between vacations and happiness. We examined whether vacationers differ in happiness, compared to those not going on holiday, and if a holiday trip boosts post-trip happiness. These questions were addressed in a pre-test/post-test design study among 1,530 Dutch individuals. 974 vacationers answered questions about their happiness before and after a holiday trip. Vacationers reported a higher degree of pre-trip happiness, compared to non-vacationers, possibly because they are anticipating their holiday. Only a very relaxed holiday trip boosts vacationers’ happiness further after return. Generally, there is no difference between vacationers’ and non-vacationers’ post-trip happiness. The findings are explained in the light of set-point theory, need theory and comparison theory

Active Packaging Technologies with an Emphasis on Antimicrobial Packaging and its Applications

In response to the dynamic changes in current consumer demand and market trends, the area of Active Packaging (AP) is becoming increasingly significant. Principal AP systems include those that involve oxygen scavenging, moisture absorption and control, carbon dioxide and ethanol generation, and antimicrobial (AM) migrating and nonmigrating systems. Of these active packaging systems, the AM version is of great importance. This article reviews: (1) the different categories of AP concepts with particular regard to the activity of AM packaging and its effects on food products, (2) the development of AM and AP materials, and (3) the current and future applications of AM packaging