The Impact of Sulfur-Containing Inorganic Compounds during the Depolymerization of Lignin by Hydrothermal Liquefaction of Black Liquor.

Lignin is a promising resource for the sustainable production of platform chemicals and biofuels. The paper industry produces large quantities of lignin every year, mostly dissolved in a black liquor. With the help of hydrothermal liquefaction, black liquor can be used directly as a feedstock to depolymerize the lignin to desired products.

From Pulp to Aromatic Products-Reaction Pathways of Lignin Depolymerization.

This study investigated the depolymerization of lignin into aromatic monomer compounds under hydrothermal conditions. A reaction scheme highlighting secondary alkylation reactions as well as the molecular weight shift was developed based on the experimental data. Lignin is produced in large quantities in paper production and dissolved in what is known as black liquor (BL).

Hydrothermal liquefaction of sewage sludge: use of HCOOH and KOH to improve the slurry pumpability in a continuously operated plant.

We studied the hydrothermal liquefaction (HTL) of digested sewage sludge (DSS) as model of waste biomass in batch and continuous reactors. HCOOH and KOH were used to improve the slurry pumpability. HTL experiments were conducted at the same kinetic severity factor in a batch reactor of 25 mL of volume and in a continuously operated tubular reactor with 350 mL of volume.

Valorisation of the residual aqueous phase from hydrothermally liquefied black liquor by persulphate-based advanced oxidation.

Hydrothermal liquefaction of Kraft black liquor is a promising method for the production of valuable organic chemicals. However, the separation of the biochar and biocrude leaves a residual aqueous phase in large volumes, which needs to be properly managed to make the process profitable. In this work, the persulphate-based advanced oxidation was assessed, for the first time ever, as a pretreatment of this aqueous phase to reduce its content of phenolic compounds and alcohols, which hinder further valorisation strategies.

Suppression of tar and char formation in supercritical water gasification of sewage sludge by additive addition.

This study explored the feasibility of char and tar formation inhibition during supercritical water gasification of sewage sludge (SS) by additive addition. Experiments were conducted in autoclave with 5 wt% additives at 400 °C for 30 min. The non-additive gasification of SS resulted in a higher char yield (12.

Assessing microalgae biorefinery routes for the production of biofuels via hydrothermal liquefaction.

The interest in third generation biofuels from microalgae has been rising during the past years. Meanwhile, it seems not economically feasible to grow algae just for biofuels. Co-products with a higher value should be produced by extracting a particular algae fraction to improve the economics of an algae biorefinery.

Expression of the male determining gene dmrt1bY and its autosomal coorthologue dmrt1a in medaka.

Dmrt1bY (aka dmy) has been identified as the master male sex-determining gene of medaka by positional cloning and genetic evidence. How this gene on the molecular level determines the differentiation of the gonad primordium towards a testis, however, is unknown. To better understand the roles of dmrt1bY and its autosomal counterpart dmrt1a in the process of sex determination, a detailed expression analysis by quantitative real-time RT-PCR was performed showing non-organ-specific expression of dmrt1bY during embryogenesis and low expression in adult testes.

Inhibition of primordial germ cell proliferation by the medaka male determining gene Dmrt I bY.

Background: Dmrt I is a highly conserved gene involved in the determination and early differentiation phase of the primordial gonad in vertebrates. In the fish medaka dmrt I bY, a functional duplicate of the autosomal dmrt I a gene on the Y-chromosome, has been shown to be the master regulator of male gonadal development, comparable to Sry in mammals. In males mRNA and protein expression was observed before morphological sex differentiation in the somatic cells surrounding primordial germ cells (PGCs) of the gonadal anlage and later on exclusively in Sertoli cells.

Genomic organization of the sex-determining and adjacent regions of the sex chromosomes of medaka.

Sequencing of the human Y chromosome has uncovered the peculiarities of the genomic organization of a heterogametic sex chromosome of old evolutionary age, and has led to many insights into the evolutionary changes that occurred during its long history. We have studied the genomic organization of the medaka fish Y chromosome, which is one of the youngest heterogametic sex chromosomes on which molecular data are available. The Y specific and adjacent regions were sequenced and compared to the X.

Genetics: relatedness among east African coelacanths.

Coelacanths were discovered in the Comoros archipelago to the northwest of Madagascar in 1952. Since then, these rare, ancient fish have been found to the south off Mozambique, Madagascar and South Africa, and to the north off Kenya and Tanzania -- but it was unclear whether these are separate populations or even subspecies. Here we show that the genetic variation between individuals from these different locations is unexpectedly low.

Evolutionary origin of the medaka Y chromosome.

Genetic sex determination in an XX-XY chromosome system can be realized through a locus on the Y chromosome that makes the undifferentiated gonad develop into a testis. Although this mechanism is widespread, only in two cases so far have the corresponding master male sex-determining genes been identified. One is Sry, which initiates testes determination in most mammals.

Developmentally regulated and non-sex-specific expression of autosomal dmrt genes in embryos of the Medaka fish (Oryzias latipes).

The dmrtgene family of vertebrates comprises several transcription factors that share a highly conserved DNA-binding domain, the DM domain. Like some of their invertebrate counterparts, e.g.

Identification of a second egfr gene in Xiphophorus uncovers an expansion of the epidermal growth factor receptor family in fish.

The epidermal growth factor receptor (EGFR) gives name to a family of receptors formed by four members in mammals (EGFR, ErbB2, ErbB3, and ErbB4). Members of this family can be activated to become potent oncogenes, and many human and animal tumors express qualitatively or quantitatively altered receptors from this group. We have isolated and characterized a second egfr gene in the melanoma model fish Xiphophorus.

Hormonal induction and stability of monosex populations in the medaka (Oryzias latipes): expression of sex-specific marker genes.

The model teleost medaka (Oryzias latipes, d-rR.YHNI strain) was used to produce offspring of a defined sex (monosex populations) by crossing experimentally produced YY and XX males to normal females. These monosex populations had the predicted chromosomal constitution as shown by a sex chromosome-specific DNA sequence.

Absence of the candidate male sex-determining gene dmrt1b(Y) of medaka from other fish species.

Although the sex-determining genes are known in mammals, Drosophila, and C. elegans, little is known in other animals. Fishes are an attractive group of organisms for studying the evolution of sex determination because they show an amazing variety of mechanisms, ranging from environmental sex determination and different forms of hermaphroditism to classical sex chromosomal XX/XY or WZ/ZZ systems and modifications thereof.

Common spontaneous sex-reversed XX males of the medaka Oryzias latipes.

In the medaka, a duplicated version of the dmrt1 gene, dmrt1bY, has been identified as a candidate for the master male sex-determining gene on the Y chromosome. By screening several strains of Northern and Southern medaka we identified a considerable number of males with normal phenotype and uncompromised fertility, but lacking dmrt1bY. The frequency of such males was >10% in some strains and zero in others.

Isolation and characterization of cold-shock domain protein genes, Oryzias latipes Y-box protein 2 (OlaYP2) and Fugu rubripes Y-box protein 1 (FruYP1), in medakafish and pufferfish.

The Y-box protein (YP) family shares a nucleic acid binding domain, called cold-shock domain, that has been evolutionarily highly conserved from bacteria to human. The different YPs identified so far in vertebrates are thought to function as transcriptional activators, transcriptional repressors and/or translational repressors. Medakafish and pufferfish are very suitable vertebrate models for the study of developmental genetics and comparative genomics, respectively.

Molecular cloning and characterization of DMRT genes from the medaka Oryzias latipes and the platyfish Xiphophorus maculatus.

The DMRT genes constitute a family of genes, which possess a common motif called the DM domain. DMRT1 is considered to be involved in sex determination and/or sex differentiation, but not much information exists about the function of the other gene family members. We cloned DMRT genes of two important model fish species, the medaka, Oryzias latipes, and the platyfish, Xiphophorus maculatus.

A duplicated copy of DMRT1 in the sex-determining region of the Y chromosome of the medaka, Oryzias latipes.

The genes that determine the development of the male or female sex are known in Caenorhabditis elegans, Drosophila, and most mammals. In many other organisms the existence of sex-determining factors has been shown by genetic evidence but the genes are unknown. We have found that in the fish medaka the Y chromosome-specific region spans only about 280 kb.

Genomic organization and expression of the doublesex-related gene cluster in vertebrates and detection of putative regulatory regions for DMRT1.

Genes related to the Drosophila melanogaster doublesex and Caenorhabditis elegans mab-3 genes are conserved in human. They are identified by a DNA-binding homology motif, the DM domain, and constitute a gene family (DMRTs). Unlike the invertebrate genes, whose role in the sex-determination process is essentially understood, the function of the different vertebrate DMRT genes is not as clear.

Fish retroposons related to the Penelope element of Drosophila virilis define a new group of retrotransposable elements.

Poseidon and Neptune are two ancient lineages of retroposons related to the Penelope element from Drosophila virilis. They have been identified in various teleost fish species, including the medakafish (Oryzias latipes), and the pufferfishes Fugu rubripes and Tetraodon nigroviridis, whose genomes are currently being sequenced. Some of these elements are highly reiterated in fish genomes.

Melanoma loss-of-function mutants in Xiphophorus caused by Xmrk-oncogene deletion and gene disruption by a transposable element.

The overexpression of the Xmrk oncogene (ONC-Xmrk) in pigment cells of certain Xiphophorus hybrids has been found to be the primary change that results in the formation of malignant melanoma. Spontaneous mutant stocks have been isolated that have lost the ability to induce tumor formation when crossed with Xiphophorus helleri. Two of these loss-of-function mutants were analyzed for genetic defects in ONC-Xmrk's.

Triplet repeat variability in the signal peptide sequence of the Xmrk receptor tyrosine kinase gene in Xiphophorus fish.

Trinucleotide repeats in several human genes have been found to undergo spontaneous variation in repeat numbers in succeeding generations. Expansion of the repeat beyond a certain length causes specific pathological disorders. So far, a naturally occurring triplet repeat instability of transcribed sequences has been reported only from humans.

Susceptibility to the development of pigment cell tumors in a clone of the Amazon molly, Poecilia formosa, introduced through a microchromosome.

The Amazon molly Poecilia formosa is a gynogenetic fish that reproduces through the development of ameiotic diploid eggs triggered by insemination by males of related species without following karyogamie. This leads to clonal offspring. In rare cases, however, this gynogenesis is leaky, and paternal DNA in the form of small supernumerary chromosomes is included into the maternal genome.