Ontogeny of glycerolipid biosynthetic enzymes in swine liver and adipose tissue.

Enzymes associated with glycerolipid biosynthesis were examined in microsomal fractions of liver and adipose tissue obtained from swine of various ages. Generally, liver glycerophosphate acyltransferase, phosphatidate phosphohydrolase, diglyceride acyltransferase, and choline phosphotransferase activities were substantial at birth but increased 2- to 3-fold by day 14 postpartum, decreased at day 25, then increased at the oldest ages studied (up to 155 days postpartum). In adipose tissue, enzyme activities were low at birth and developed through day 25 in a pattern generally similar to that observed in liver. In contrast to liver, the adipose enzymes were depressed immediately postweaning (day 32) with subsequent recovery. The observed decline in adipose tissue enzyme activities expressed on a tissue basis at older ages was primarily the result of increased adipocyte size, since the activities expressed on a cell basis did not decline as rapidly. In both liver and adipose tissue, phosphatidate was the major glycerolipid synthesized by the microsomal glycerophosphate acyltransferase enzymes at all ages (generally greater than 75%). The ratio of neutral lipids to phospholipids produced by acylation of glycerophosphate was increased when a microsomal--cytosolic preparation was used as a source of enzyme in contrast to a microsomal preparation.     

The G protein-coupled receptor Gpr1 and the Galpha protein Gpa2 act through the cAMP-protein kinase A pathway to induce morphogenesis in Candida albicans

We investigated the role in cell morphogenesis and pathogenicity of the Candida albicans GPR1 gene, encoding the G protein-coupled receptor Gpr1. Deletion of C. albicans GPR1 has only minor effects in liquid hypha-inducing media but results in strong defects in the yeast-to-hypha transition on solid hypha-inducing media. Addition of cAMP, expression of a constitutively active allele of the Galpha protein Gpa2 or of the catalytic protein kinase A subunit TPK1 restores the wild-type phenotype of the CaGPR1-deleted strain. Overexpression of HST7, encoding a component of the mitogen-activated protein kinase pathway, does not suppress the defect in filamentation. These results indicate that CaGpr1 functions upstream in the cAMP-protein kinase A (PKA) pathway. We also show that, in the presence of glucose, CaGpr1 is important for amino acid-induced transition from yeast to hyphal cells. Finally, as opposed to previous reports, we show that CaGpa2 acts downstream of CaGpr1 as activator of the cAMP-PKA pathway but that deletion of neither CaGpr1 nor CaGpa2 affects glucose-induced cAMP signaling. In contrast, the latter is abolished in strains lacking CaCdc25 or CaRas1, suggesting that the CaCdc25-CaRas1 rather than the CaGpr1-CaGpa2 module mediates glucose-induced cAMP signaling in C. albicans.     

In silico fine-mapping: narrowing disease-associated loci by intergenomics

SUMMARY: Genetic linkage and association studies define quantitative trait loci (QTLs) and susceptibility loci (SLs) that influence the phenotype of polygenic traits. A web-accessible application was created to identify intergenomic consensuses to fine map QTLs and SLs in silico and select particularly promising candidate genes for such traits. Furthermore, this approach offers an empirical evaluation of animal models for their applicability to the study of human traits. AVAILABILITY: http://qtl.pzr.uni-rostock.de/qtlmix.php CONTACT: serrano@pzr.uni-rostock.de.     

From variable to constant cell numbers: cellular characteristics of the arthropod nervous system argue against a sister-group relationship of Chelicerata and “Myriapoda” but favour the Mandibulata concept

In the new debate on arthropod phylogeny, structure and development of the nervous system provide important arguments. The architecture of the brain of Hexapoda, Crustacea and Chelicerata in recent years has been thoroughly compared against an evolutionary background. However, comparative aspects of the nervous systems in these taxa at the cellular level have been examined in only a few studies. This review sets out to summarize these aspects and to analyse the existing data with respect to the concept of individually identifiable neurons. In particular, mechanisms of neurogenesis, the morphology of serotonergic interneurons, the number of motoneurons, and cellular features and development of the lateral eyes are discussed. We conclude that in comparison to the Mandibulata, in Chelicerata the numbers of neurons in the different classes examined are much higher and in many cases are not fixed but variable. The cell numbers in Mandibulata are lower and the majority of neurons are individually identifiable. The characters explored in this review are mapped onto an existing phylogram, as derived from brain architecture in which the Hexapoda are an in-group of the Crustacea, and there is not any conflict of the current data with such a phylogenetic position of the Hexapoda. Nevertheless, these characters argue against a sister-group relationship of Myriapoda and Chelicerata as has been recently suggested in several molecular studies, but instead provide strong evidence in favour of the Mandibulata concept.Edited by D. Tautz     

Different methylation characteristics of protein arginine methyltransferase 1 and 3 toward the Ewing Sarcoma protein and a peptide

The multifunctional Ewing Sarcoma (EWS) protein, a member of a large family of RNA-binding proteins, is extensively asymmetrically dimethylated at arginine residues within RGG consensus sequences. Using recombinant proteins we examined whether type I protein arginine methyltransferase (PRMT)1 or 3 is responsible for asymmetric dimethylations of the EWS protein. After in vitro methylation of the EWS protein by GST-PRMT1, we identified 27 dimethylated arginine residues out of 30 potential methylation sites by mass spectrometry-based techniques (MALDI-TOF MS and MS/MS). Thus, PRMT1 recognizes most if not all methylation sites of the EWS protein. With GST-PRMT3, however, only nine dimethylated arginines, located mainly in the C-terminal region of EWS protein, could be assigned, indicating that structural determinants prevent complete methylation. In contrary to previous reports this study also revealed that trypsin is able to cleave after methylated arginines. Pull-down experiments showed that endogenous EWS protein binds efficiently to GST-PRMT1 but less to GST-PRMT3, which is in accordance to the in vitro methylation results. Furthermore, methylation of a peptide containing different methylation sites revealed differences in the site selectivity as well as in the kinetic properties of GST-PRMT1 and GST-PRMT3. Kinetic differences due to an inhibition effect of the methylation inhibitor S-adenosyl-L-homocysteine could be excluded by determining the corresponding K(i) values of the two enzymes and the K(d) values for the methyl donor S-adenosyl-L-methionine. The study demonstrates the strength of MS-based methods for a qualitative and quantitative analysis of enzymic arginine methylation, a posttranslational modification that becomes more and more the object of investigations.     

Toftanes: The Paleoecology of a Faroese <Emphasis Type="Italic">Landnám</Emphasis> Farm

For the first time in the Faroe Islands, the paleoecological content of an early Norse farm has been sampled comprehensively in an effort to understand how it functioned and its relationship to the landscape in which it was located. Organic deposits indicate an increase in species diversity at the time of settlement, including the introduction of several new species. Plant resources from various areas of the treeless landscape were exploited and farm buildings contained suites of synanthropic insects dominated by those associated with accumulations of decaying plant debris. Potential fuels included wood, peat, dung, and seaweed. Insect faunas lacked both ectoparasites and a significant foul beetle component. This may be a reflection of animal husbandry, with stock not being stalled over winter in the farm buildings examined, or an absence of wool-processing in the buildings. Results compare well with other sites in the North Atlantic and argue for the consistent nature of the Norse farming economy across the region.     

Modification of humic acids by the compost-dwelling deuteromycete Paecilomyces inflatus

The soil mold Paecilomyces inflatus is capable of modifying and partially mineralizing synthetic and natural humic acids (HAs) in compost environments. HA degradation studies using a synthetic HA (¹⁴C-HA) in autoclaved compost microcosms showed that, after 12 weeks of cultivation, P. inflatus mineralized approximately 5% of the ¹⁴C-labeled HA to¹⁴CO₂, while 6% of the ¹⁴C-HA was converted into ¹⁴C-labeled water-soluble fragments (fulvic-acid-like fraction). About 40% was still present as NaOH-soluble HA representing unmodified or only slightly modified humic material (compared with 60% in the controls). Modification of natural HAs extracted from compost was followed by their partial decolorization (30%) in liquid cultures of P. inflatus. Bleaching of the medium was accompanied by moderate changes in the molecular mass distribution of both the HA and fulvic-acid fractions, which were analyzed with high-performance size exclusion chromatography. HA modification was most pronounced during the primary growth phase of the fungus and was associated with increased laccase activity.     

Collection of soluble variants of membrane proteins for transcriptomics and proteomics

The existence of a soluble splice variant for a gene encoding a transmembrane protein suggests that this gene plays a role in intercellular signalling, particularly in immunological processes. Also, the absence of a splice variant of a reported soluble variant suggests exclusive control of the solubilisation by proteolytic cleavage. Soluble splice variants of membrane proteins may also be interesting targets for crystallisation as their structure may be expected to preserve, at least partially, their function as integral membrane proteins, whose structures are most difficult to determine. This paper presents a dataset derived from the literature in an attempt to collect all reported soluble variants of membrane proteins, be they splice variants or shedded. A list of soluble variants is derived in silico from Ensembl. These are checked on their presence in multiple organisms and their number of membranespanning regions is inspected. The findings then are confirmed by a comparison with identified proteins of a recent global proteomics study of human blood plasma. Finally, a tool to determine novel soluble variants by proteomics is provided.