The hemoglobin concentration ofChironomus cf.Plumosus l. (Diptera: Chironomidae) larvae from two lentic habitats

Hemoglobin concentrations ofChironomus cf.plumosus larvae were measured in two different habitats of the same pond. Larger larvae have higher hemoglobin concentrations than small larvae. There is strong indication that the animals of poorly oxygenated deep water, have higher hemoglobin concentrations than the animals from the well-oxygenated littoral zone.     

Flocculation of microalgae using cationic starch

Due to their small size and low concentration in the culture medium, cost-efficient harvesting of microalgae is a major challenge. We evaluated the potential of cationic starch as a flocculant for harvesting microalgae using jar test experiments. Cationic starch was an efficient flocculant for freshwater (Parachlorella, Scenedesmus) but not for marine microalgae (Phaeodactylum, Nannochloropsis). At high cationic starch doses, dispersion restabilization was observed. The required cationic starch dose to induce flocculation increased linearly with the initial algal biomass concentration. Of the two commercial cationic starch flocculants tested, Greenfloc 120 (used in wastewater treatment) was more efficient than Cargill C*Bond HR 35.849 (used in paper manufacturing). For flocculation of Parachlorella using Greenfloc 120, the cationic starch to algal biomass ratio required to flocculate 80% of algal biomass was 0.1. For Scenedesmus, a lower dose was required (ratio 0.03). Flocculation of Parachlorella using Greenfloc 120 was independent of pH in the pH range of 5 to 10. Measurements of the maximum quantum yield of PSII suggest that Greenfloc 120 cationic starch was not toxic to Parachlorella. Cationic starch may be used as an efficient, nontoxic, cost-effective, and widely available flocculant for harvesting microalgal biomass.     

Studies on the antigenic behaviour of egg- and egg-mouse-egg-lines of strains of influenza virus,with the aid of the haemagglutination-inhibition test

Summary Egg- and egg-mouse-egg-lines of strains of influenza virus were compared with the aid of the haemagglutination inhibition test. In most experiments it was found that the crossing of an antiserum of an egg-mouse-egg-line against the homologous egg-line or against a heterologous egg-line of a strain belonging to the same subgroup yields a low or very low antititre. We are indebted to DrG. K. Hirst (New York) and DrJ. Y. Sugg (New York) for sending us the strains of influenza virus Ala and Cam. Financial support was provided by the Institute for Preventive Medicine, Leyden; N. V. Philips Roxane, Weesp; the State Department of Science; the Jan Dekker Fund, and the Cura?ao Fund for Preventive Medicine.     

CD98 marks a subpopulation of head and neck squamous cell carcinoma cells with stem cell properties

Patients with advanced head and neck squamous cell carcinomas (HNSCCs) are often treated with concomitant chemotherapy and radiotherapy, but only 50% is cured. A possible explanation for treatment failure is therapy resistance of the cancer stem cells (CSCs). The application of compounds specifically targeting these CSCs, in addition to routinely used therapeutics, would likely improve clinical outcome. We demonstrate that the previously described monoclonal antibody K984 recognizes the CD98 cell surface protein, which is specifically expressed by cells forming the squamous basal cell layer, the region where the squamous stem cells reside. Moreover, CD98 is highly resistant to the proteolytic enzymes required for CSC enrichment procedures. We show that CD98^high cells, in contrast to CD98^low cells, are able to generate tumors in immunodeficient mice, indicating that CD98^high cells have stem cell characteristics. Furthermore, the CD98^high subpopulation expresses high levels of cell cycle control and DNA repair genes, while the CD98^low fraction shows expression patterns that represent the more differentiated cells forming the bulk of the tumor. CD98 is a promising CSC enrichment marker in HNSCC. Our data support the CSC concept in head and neck cancer and the potential relevance of these cells for treatment outcome.     

Lesser Black-backed Gulls Larus fuscus thriving on a non-marine diet

Capsule: Lesser Black-backed Gulls Larus fuscus breeding 30?km from the coast in the Netherlands focussed entirely on terrestrial food sources and reached relatively high breeding success.

Aim: To gain insight in the foraging ecology, habitat use and breeding performance of inland-breeding Lesser Black-backed Gulls.

Methods: We received data from seven birds fitted with global positioning system (GPS) loggers. The colony was frequently visited to collect pellets and boluses and to monitor reproductive success, mortality and growth rate of chicks.

Results: The GPS data revealed that mainly terrestrial habitats were used, 98% of these GPS positions were within 25?km of the colony. Refuse dumps were the most preferred sites, but also agricultural fields and freshwater bodies were often visited. Only two of the 710 recorded trips were directed to the North Sea. The pellet and bolus analyses confirmed the GPS data: no marine food remains were found. Breeding success of birds in the enclosure was relatively high, with 90% of eggs hatched and 51% of chicks fledged (1.6 chicks/pair).

Conclusions: Relying on terrestrial food is feasible when sources are available in the vicinity of the colony. We conclude that Lesser Black-backed Gulls could theoretically shift towards inland breeding after a fishery discards ban.     

Effect of Antimicrobial Consumption and Production Type on Antibacterial Resistance in the Bovine Respiratory and Digestive Tract

The aim of this study was to investigate the relationship between antimicrobial use and the occurrence of antimicrobial resistance in the digestive and respiratory tract in three different production systems of food producing animals. A longitudinal study was set up in 25 Belgian bovine herds (10 dairy, 10 beef, and 5 veal herds) for a 2 year monitoring of antimicrobial susceptibilities in E. coli and Pasteurellaceae retrieved from the rectum and the nasal cavity, respectively. During the first year of observation, the antimicrobial use was prospectively recorded on 15 of these farms (5 of each production type) and transformed into the treatment incidences according to the (animal) defined daily dose (TI_ADD) and (actually) used daily dose (TI_UDD). Antimicrobial resistance rates of 4,174 E. coli (all herds) and 474 Pasteurellaceae (beef and veal herds only) isolates for 12 antimicrobial agents demonstrated large differences between intensively reared veal calves (abundant and inconstant) and more extensively reared dairy and beef cattle (sparse and relatively stable). Using linear mixed effect models, a strong relation was found between antimicrobial treatment incidences and resistance profiles of 1,639 E. coli strains (p<0.0001) and 309 Pasteurellaceae (p≤0.012). These results indicate that a high antimicrobial selection pressure, here found to be represented by low dosages of oral prophylactic and therapeutic group medication, converts not only the commensal microbiota from the digestive tract but also the opportunistic pathogenic bacteria in the respiratory tract into reservoirs of multi-resistance.     

Protein Kinase B Localization and Activation Differentially Affect S6 Kinase 1 Activity and Eukaryotic Translation Initiation Factor 4E-Binding Protein 1 Phosphorylation

Recent studies indicate that phosphatidylinositide-3OH kinase (PI3K)-induced S6 kinase (S6K1) activation is mediated by protein kinase B (PKB). Support for this hypothesis has largely relied on results obtained with highly active, constitutively membrane-localized alleles of wild-type PKB, whose activity is independent of PI3K. Here we set out to examine the importance of PKB signaling in S6K1 activation. In parallel, glycogen synthase kinase 3beta (GSK-3beta) inactivation and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) phosphorylation were monitored as markers of the rapamycin-insensitive and -sensitive branches of the PI3K signaling pathway, respectively. The results demonstrate that two activated PKBalpha mutants, whose basal activity is equivalent to that of insulin-induced wild-type PKB, inhibit GSK-3beta to the same extent as a highly active, constitutively membrane-targeted wild-type PKB allele. However, of these two mutants, only the constitutively membrane-targeted allele of PKB induces S6K1 activation. Furthermore, an interfering mutant of PKB, which blocks insulin-induced PKB activation and GSK-3beta inactivation, has no effect on S6K1 activation. Surprisingly, all the activated PKB mutants, regardless of constitutive membrane localization, induce 4E-BP1 phosphorylation and the interfering PKB mutant blocks insulin-induced 4E-BP1 phosphorylation. The results demonstrate that PKB mediates S6K1 activation only as a function of constitutive membrane localization, whereas the activation of PKB appears both necessary and sufficient to induce 4E-BP1 phosphorylation independently of its intracellular location.     

Specific Labeling of Stem Cell Activity in Human Colorectal Organoids Using an ASCL2-Responsive Minigene

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