Anaerobic degradation of papermill sludge in a two-phase digester containing rumen microorganisms and colonized polyurethane foam

Summary The use of reticulated polyurethane foam as a support material for the immobilization of methanogenic associations and its application to the anaerobic treatment of fine particulate solid wastes was investigated. The colonization of polyurethane support particles in a continuous upflow reactor fed on a mixture of acetate, propionate and butyrate, was both rapid and dense. The combination of rumen microorganisms and colonized support particles in a two-phase digester resulted in an efficient anaerobic decomposition of papermill sludge.     

Neurospora crassa Cytoplasmic Ribosomes: Isolation and Characterization of a Cold-Sensitive Mutant Defective in Ribosome Biosynthesis

Twenty-seven cold-sensitive mutants of Neurospora crassa were isolated by mutagenesis of wild-type conidia followed by filtration enrichment in complete medium at the nonpermissive temperature (10 C). Zone sedimentation analyses of cytoplasmic ribosomes isolated from the wild-type strain and from 14 of the mutant strains grown at 10 C indicate that one cold-sensitive mutant is defective in ribosome biosynthesis at that temperature: instead of the 2.3:1 mass ratio of 60S:37S ribosomal subunits characteristic of wild type, the mutant strain PJ30201 (called crib-1 for cytoplasmic ribosome biosynthesis) exhibits a mass ratio of approximately 7.2:1. Ribosomal subunits synthesized by strain PJ30201 at 25 C are present in wild-type proportions. The cold-sensitive and ribosomal phenotypes segregate together in tetrads isolated from crosses between strain PJ30201 and the wild type indicating that a single nuclear gene mutation is probably responsible for both mutant phenotypes. The crib-1 locus lies near the centromere in linkage group IV.     

The effect of genomic information on optimal contribution selection in livestock breeding programs

Background

Long-term benefits in animal breeding programs require that increases in genetic merit be balanced with the need to maintain diversity (lost due to inbreeding). This can be achieved by using optimal contribution selection. The availability of high-density DNA marker information enables the incorporation of genomic data into optimal contribution selection but this raises the question about how this information affects the balance between genetic merit and diversity.

Methods

The effect of using genomic information in optimal contribution selection was examined based on simulated and real data on dairy bulls. We compared the genetic merit of selected animals at various levels of co-ancestry restrictions when using estimated breeding values based on parent average, genomic or progeny test information. Furthermore, we estimated the proportion of variation in estimated breeding values that is due to within-family differences.

Results

Optimal selection on genomic estimated breeding values increased genetic gain. Genetic merit was further increased using genomic rather than pedigree-based measures of co-ancestry under an inbreeding restriction policy. Using genomic instead of pedigree relationships to restrict inbreeding had a significant effect only when the population consisted of many large full-sib families; with a half-sib family structure, no difference was observed. In real data from dairy bulls, optimal contribution selection based on genomic estimated breeding values allowed for additional improvements in genetic merit at low to moderate inbreeding levels. Genomic estimated breeding values were more accurate and showed more within-family variation than parent average breeding values; for genomic estimated breeding values, 30 to 40% of the variation was due to within-family differences. Finally, there was no difference between constraining inbreeding via pedigree or genomic relationships in the real data.

Conclusions

The use of genomic estimated breeding values increased genetic gain in optimal contribution selection. Genomic estimated breeding values were more accurate and showed more within-family variation, which led to higher genetic gains for the same restriction on inbreeding. Using genomic relationships to restrict inbreeding provided no additional gain, except in the case of very large full-sib families.     

Manipulation of CD45 antigen in transplantation tolerance

CD45 is known to have tyrosine phosphatase activity for signal transduction of T cells. Immunomodulation of CD45 has been tried to prevent T cell-mediated graft rejection in organ transplantation. In vitro study showed that blockade of CD45RB, an alternative splicing isoform of CD45, inhibited proliferative response of T cells after allogeneic stimulation. Treatment with a monoclonal antibody (mAb) against CD45RB induced long-term allograft acceptance in some mouse organ transplantation models. In a rat heart allograft model, a single injection of anti-rat CD45 (RT7) mAb which bound to allomorphic region of RT7 also induced allograft acceptance. CD45/RT7 is also a useful tool of targeting hematopoietic cells, because of the selective expression on all hematopoietic cells. There are two allomorphic forms of CD45 (RT7a and RT7b) in the rat. Using RT7 system, a rat heart allograft model from RT7a donors to RT7b recipients was designed to test functional relevance of graft-associated hematopoietic cells (microchimerism) to allograft acceptance. Then donor-derived hematopoietic cells were selectively depleted using anti-RT7a mAb in vivo. Depletion on day 0 prevented allograft acceptance and was associated with severe acute or chronic graft rejection, while depletion on day 18 after transplantation showed no effect. This experimental study showed a crucial role of microchimerism in induction phase of allograft acceptance. In conclusion, the CD45/RT7 system is not only a target molecule for tolerance induction, but also an useful tool for experimental models in transplantation immunology. In this review, we introduce basic properties of CD45 and recent results with manipulation of CD45.     

A novel mode of chromosomal evolution peculiar to filamentous Ascomycete fungi

Background  

Gene loss, inversions, translocations, and other chromosomal rearrangements vary among species, resulting in different rates of structural genome evolution. Major chromosomal rearrangements are rare in most eukaryotes, giving large regions with the same genes in the same order and orientation across species. These regions of macrosynteny have been very useful for locating homologous genes in different species and to guide the assembly of genome sequences. Previous analyses in the fungi have indicated that macrosynteny is rare; instead, comparisons across species show no synteny or only microsyntenic regions encompassing usually five or fewer genes. To test the hypothesis that chromosomal evolution is different in the fungi compared to other eukaryotes, synteny was compared between species of the major fungal taxa.     

Modelling gene networks at different organisational levels

Approaches to modelling gene regulation networks can be categorized, according to increasing detail, as network parts lists, network topology models, network control logic models, or dynamic models. We discuss the current state of the art for each of these approaches. There is a gap between the parts list and topology models on one hand, and control logic and dynamic models on the other hand. The first two classes of models have reached a genome-wide scale, while for the other model classes high throughput technologies are yet to make a major impact.