Seasonal dynamics of moss-dwelling chironomid communities

Chironomid communities of mosses in a small upland stream in central Germany were highly dynamic across the year with respect to their abundance, biomass and dominant taxa. During 1988 semi-submersed mosses near a main spring and those occurring some 700 m downstream were compared with permanently submersed mosses in immediate vicinity of the downstream site. All the chironomids sampled were conspicuously small, with nearly 98% being less than 5 mm in length. A total of 65 chironomid species from 26 genera were found, with a higher diversity occurring near the source and a change in dominant taxa along the upper stream section. The mean abundance in permanently submersed mosses (250 larvae/10 cm², n = 125) was about five times higher than in semi-submersed mosses. The maximum value of 830 larvae/10 cm² (n = 1) is the highest chironomid density ever reported, which is explained by the sampling method used. The mean standing crop was also highest in permanently submersed mosses (1.5 mg AFDW/10 cm² (n = 125)), even though the highest individual value was recorded in semi-submersed mosses near the spring (10.4 mg AFDW/10 cm²). The evidence suggested that the dominance of chironomid taxa depended mainly on the location of the moss along the stream, whereas abundance and biomass were determined mainly by constancy in the ambient discharge as well as the factors influenced by this (e.g. temperature, detritus deposition). A trend was seen towards a seasonal succession among the chironomid taxa colonizing lotic mosses.     

Genetic engineering of brewing yeast to reduce the content of ethanol in beer

The GPD1 gene encoding the glycerol-3-phosphate dehydrogenase was overexpressed in an industrial lager brewing yeast (Saccharomyces cerevisiae ssp. carlsbergensis) to reduce the content of ethanol in beer. The amount of glycerol produced by the GPD1-overexpressing yeast in fermentation experiments simulating brewing conditions was increased 5.6 times and ethanol was decreased by 18% when compared to the wild-type. Overexpression of GPD1 does not affect the consumption of wort sugars. Only minor changes in the concentration of higher alcohols, esters and fatty acids could be observed in beer produced by the GPD1-overexpressing brewing yeast. However, the concentrations of several other by-products, particularly acetoin, diacetyl and acetaldehyde, were considerably increased.     

Receptor Binding Sites and Antigenic Epitopes on the Fiber Knob of Human Adenovirus Serotype 3

The adenovirus fiber knob causes the first step in the interaction of adenovirus with cell membrane receptors. To obtain information on the receptor binding site(s), the interaction of labeled cell membrane proteins to synthetic peptides covering the adenovirus type 3 (Ad3) fiber knob was studied. Peptide P6 (amino acids [aa] 187 to 200), to a lesser extent P14 (aa 281 to 294), and probably P11 (aa 244 to 256) interacted specifically with cell membrane proteins, indicating that these peptides present cell receptor binding sites. Peptides P6, P11, and P14 span the D, G, and I β-strands of the R-sheet, respectively. The other reactive peptides, P2 (aa 142 to 156), P3 (aa 153 to 167), and P16 (aa 300 to 319), probably do not present real receptor binding sites. The binding to these six peptides was inhibited by Ad3 virion and was independent of divalent cations. We have also screened the antigenic epitopes on the knob with recombinant Ad3 fiber, recombinant Ad3 fiber knob, and Ad3 virion-specific antisera by enzyme-linked immunosorbent assay. The main antigenic epitopes were presented by P3, P6, P12 (aa 254 to 269), P14, and especially the C-terminal P16. Peptides P14 and P16 of the Ad3 fiber knob were able to inhibit Ad3 infection of cells.     

Viral and cellular determinants of hepatitis C virus RNA replication in cell culture

Studies on the replication of hepatitis C virus (HCV) have been facilitated by the development of selectable subgenomic replicons replicating in the human hepatoma cell line Huh-7 at a surprisingly high level. Analysis of the replicon population in selected cells revealed the occurrence of cell culture-adaptive mutations that enhance RNA replication substantially. To gain a better understanding of HCV cell culture adaptation, we characterized conserved mutations identified by sequence analysis of 26 independent replicon cell clones for their effect on RNA replication. Mutations enhancing replication were found in nearly every nonstructural (NS) protein, and they could be subdivided into at least two groups by their effect on replication efficiency and cooperativity: (i). mutations in NS3 with a low impact on replication but that enhanced replication cooperatively when combined with highly adaptive mutations and (ii). mutations in NS4B, -5A, and -5B, causing a strong increase in replication but being incompatible with each other. In addition to adaptive mutations, we found that the host cell plays an equally important role for efficient RNA replication. We tested several passages of the same Huh-7 cell line and found up to 100-fold differences in their ability to support replicon amplification. These differences were not due to variations in internal ribosome entry site-dependent translation or RNA degradation. In a search for cellular factor(s) that might be responsible for the different levels of permissiveness of Huh-7 cells, we found that replication efficiency decreased with increasing amounts of transfected replicon RNA, indicating that viral RNA or proteins are cytopathic or that host cell factors in Huh-7 cells limit RNA amplification. In summary, these data show that the efficiency of HCV replication in cell culture is determined both by adaptation of the viral sequence and by the host cell itself.     

Physical mapping of two Xp markers DXS16 and DXS143

Summary Lymphocyte karyotyping of an infant girl with the clinical features of microphthalmia, iridoschisis, goiter, hip joint dysplasia, labium synechia and craniotabes revealed an Xp deletion. The lymphocyte karyotypes of the parents were normal. Bromodeoxyuridine incorporation studies showed that, in 42 out of 43 metaphases, the deleted X chromosome was late replicating. In one metaphase, the normal X chromosome was observed to be allocyclic. Using DNA markers from the Xp22 region, the breakpoint was assigned distal to DXS16 (pXUT23) and proximal to DXS143 (dic56). Dosage intensity measurements confirmed that the STS gene and the DNA marker DXS31 were involved in the deleted area. Restriction fragment length polymorphism analysis revealed that the paternally derived X-chromosome was deleted.     

Metabolomics of dietary Fatty Acid restriction in patients with phenylketonuria

Background

Patients with phenylketonuria (PKU) have to follow a lifelong phenylalanine restricted diet. This type of diet markedly reduces the intake of saturated and unsaturated fatty acids especially long chain polyunsaturated fatty acids (LC-PUFA). Long-chain saturated fatty acids are substrates of mitochondrial fatty acid oxidation for acetyl-CoA production. LC-PUFA are discussed to affect inflammatory and haemostaseological processes in health and disease. The influence of the long term PKU diet on fatty acid metabolism with a special focus on platelet eicosanoid metabolism has been investigated in the study presented here.

Methodology/Principal Findings

12 children with PKU under good metabolic control and 8 healthy controls were included. Activated fatty acids (acylcarnitines C6–C18) in dried blood and the cholesterol metabolism in serum were analyzed by liquid chromatographic tandem mass spectrometry (LC-MS/MS). Fatty acid composition of plasma glycerophospholipids was determined by gas chromatography. LC-PUFA metabolites were analyzed in supernatants by LC-MS/MS before and after platelet activation and aggregation using a standardized protocol. Patients with PKU had significantly lower free carnitine and lower activated fatty acids in dried blood compared to controls. Phytosterols as marker of cholesterol (re-) absorption were not influenced by the dietary fatty acid restriction. Fatty acid composition in glycerophospholipids was comparable to that of healthy controls. However, patients with PKU showed significantly increased concentrations of y-linolenic acid (C18:3n-6) a precursor of arachidonic acid. In the PKU patients significantly higher platelet counts were observed. After activation with collagen platelet aggregation and thromboxane B₂ and thromboxane B₃ release did not differ from that of healthy controls.

Conclusion/Significance

Long-term dietary fatty acid restriction influenced the intermediates of mitochondrial beta-oxidation. No functional influence on unsaturated fatty acid metabolism and platelet aggregation in patients with PKU was detected.     

Microbial stabilization of riverine sediments by extracellular polymeric substances

Sediment stability is a critical component for the understanding of cohesive sediment dynamics. Traditionally, physico-chemical sediment conditions have been regarded as most important drivers of sediment stability. However, over the last decade, the stabilization of sediment by biological activity, particularly the influence of highly hydrated matrices of extracellular polymeric substances (EPS) has been given increasing attention. However, most studies have focused on the sediment/water interface and, usually, of marine systems. The present study exploits current knowledge of EPS dynamics from marine systems and applies it to freshwater habitats, also considering a wide range of biological and physico-chemical variables. Natural sediments were taken from a freshwater site with high levels of heavy metal pollution (Lauffen reservoir, River Neckar, Germany). Vertical profiles from the flocculent surface layer to depth of 50 cm within the sediment were investigated, monthly, over the course of year. Tubificidae and Chironomidae larvae constituted the majority of the macrofauna. Despite the turbidity of the water column, a highly diverse and abundant microphytobenthic community of diatoms (11-82 microg g(-1) DW) was found at the sediment surface closely associated with high numbers of bacteria (10(9) cells g(-1) DW). The concentrations of all EPS moieties were remarkably high (0.1-0.5, 1.7-3.8, 0.9-5.2 mg g(-1) DW, for colloidal and bound carbohydrates and proteins, respectively) and levels were comparable to those determined in intertidal studies. The microalgal and bacterial biomass both showed strong correlations with the colloidal and bound EPS carbohydrate fractions. The data suggested that the present macrofauna as well as the metabolic activities of microalgae and bacteria interact with sedimentological factors to influence the properties of the sediment by binding fine-grained sediment, changing water content and enhancing the organic content through secretion products. The colloidal and bound EPS moieties showed strong correlation with the critical shear stress for erosion over sediment depth. It is suggested that the cohesive strength of the sediment was controlled by a high number of active adsorption sites and higher charge densities in fine grained sediments. The EPS network may significantly enhance this by embedding particles and permeating the void space but also in offering additional ionic binding sites and cross-linkages.     

Survival after intratumoral interleukin-2 treatment of 72 melanoma patients and response upon the first chemotherapy during follow-up

Systemic high-dose interleukin-2 (IL-2) treatment achieves long-term survival in a subset of advanced patients with melanoma. As we reported previously, intratumoral IL-2 induced complete local responses in more than 60% of melanoma patients. This study aimed to analyze the long-term outcome of 72 patients treated in two prior trials. Melanoma patients (49 stage III, 23 stage IV) with injectable metastases received intratumoral IL-2 injections thrice weekly at individually escalated doses (median duration, 6.5 weeks; median total IL-2 dose, 72 MIU; median number of injected metastases, 10). The observed 2-year overall survival rates were 95.5% for stage III patients with cutaneous metastases only (stage IIIB), 72% for those with combined cutaneous and lymph node involvement (stage IIIC), 66.7% for stage IV patients with disease limited to distant soft-tissue metastases (stage IV M1a), and 9.1% for those with visceral metastases (stage IV M1b and stage IV M1c). Thirty patients who reported recurrence of unresectable distant metastases subsequently received chemotherapy in the further course of disease and showed an overall response rate of 36.7% (16.7% complete responses, 20% partial responses). A high total dose of IL-2 and a dacarbazine/temozolomide-based chemotherapy regimen were variables correlated with a clinical response. In conclusion, patients with cutaneous metastasis without lymph node involvement in stage III and with soft-tissue metastasis without visceral involvement in stage IV showed unexpected favorable survival rates after intratumoral treatment with IL-2. Furthermore, the intratumoral IL-2 treatment seemed to be associated with increased complete and partial responses in subsequent chemotherapies.