Timing of attachment to wintering site as revealed by experimental displacements of Dunlins (Calidris alpina)

Summary Two groups of adult and two groups of juvenile colour-marked Dunlins (Calidris alpina) were moved from their wintering site in four successive years, in order to assess the existence of time- and age-dependent differences in homing behaviour and, in particular, to determine when attachment to wintering grounds is achieved by juveniles. Each group was released on different dates at the beginning of the wintering season 133 km to the south of the capture site. We expected that the behaviour of adults would not vary according to date, whereas that of juveniles would. In all four experiments the majority of birds left the release site. Juveniles displaced early in the season (5 Nov.) remained at the release site in higher numbers (34% vs 0–14%) and homed to a lesser extent (20% vs 57–62%) than juveniles displaced late in the season (13 Dec.) and both adult groups. The final return rates of adults displaced early and late in the season (8 and 24 Nov.) were similar. Most birds that left the release site departed within 20 days of displacement, whereas observations of colour-marked Dunlins at the capture site indicated a more gradual pattern of return. The first homed birds were observed three days after release, but new birds continued arriving back at the release site for at least 40 days longer. Most juvenile Dunlins seem to become attached to a wintering site during November. Recovery rates of displaced and non-displaced birds retrapped in following winters suggested that year-to-year site fidelity is developed after a longer period.

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Zeitpunkt der Festlegung von Bindungen an das Winterquartier nach Ergebnissen von Verfrachtungsexperimenten an Alpenstrandläufern(Calidris alpina)

Zusammenfassung Je zwei Gruppen von adulten und juvenilen farbmarkierten Alpenstrandläufern (Calidris alpina) wurden in vier aufeinanderfolgenden Wintern von ihren Winterquartieren verfrachtet. Die Untersuchungen dienten dazu, die zeit- und altersabhängige Unterschieden im Heimfindeverhalten zu überprüfen und vor allem festzustellen, wann die Jungvögel eine Winterortsbindung eingehen. Jede Gruppe wurde zu Beginn der Überwinterungssaison an unterschiedlichen Zeitpunkten 133 km südlich des Fangortes freigelassen. Es wurde erwartet, daß sich das Verhalten der Altvögel nicht in Abhängigkeit zum Datum änderte, wohl aber das der Jungvögel. Bei allen vier Experimenten verließ die Mehrheit der Vögel den Auflassungsort. Jungvögel, die früh in der Saison verfrachtet wurden (5. Nov.), verblieben in größerer Zahl im Gebiet der Freilassung (34%) und kehrten in geringerem Maße zum Fangort zurück (20%) als Jungvögel, die spät verfrachtet wurden (13. Dez.; 0–14% bzw. 57–62%) und als beide Altvogelgruppen. Die letztendlichen Rückkehrraten früh und spät in der Saison (8. und 24. Nov.) verfrachteter Altvögel waren ähnlich. Die meisten Vögel, die das Auflassungsgebiet verließen, flogen innerhalb von 20 Tagen nach der Verfrachtung ab, wogegen Beobachtungen am Fangort auf ein graduelleres Rückkehrmuster schließen ließen. Die ersten zurückkehrenden Vögel wurden drei Tage nach ihrer Freilassung gesehen. Die Rückkehr neuer Vögel zog sich jedoch mindestens 40 Tage länger hin. Die meisten juvenilen Alpenstrandläufer schienen im November eine Bindung an ein Überwinterungsgebiet einzugehen. Die Wiederfangraten verfrachteter und nicht verfrachteter Vögel in nachfolgenden Wintern lassen vermuten, daß Alpenstrandläufer ihre Winterortstreue erst nach einer längeren Zeit entwickeln.

     

Activation of the ubiquitin proteolytic system in murine acquired immunodeficiency syndrome affects IkappaBalpha turnover.

Murine acquired immunodeficiency syndrome (MAIDS) is a complex immunopathology caused by a defective murine leukemia virus (LP-BM5) that mainly targets B-lymphocytes. Lymphadenophathy, splenomegaly, hypergammaglobulinemia and progressive immunodeficiency are prominent features of MAIDS. Previously, we showed that the ubiquitin proteolytic system was upregulated in infected lymph nodes [Crinelli, R., Fraternale, A., Casabianca, A. & Magnani, M. (1997) Eur. J. Biochem. 247, 91-97]. In this report, we demonstrate that increased 26S proteasome activity is responsible for accelerated turnover of the IkappaBalpha inhibitor in lymph node extracts derived from animals with MAIDS. The molecular mechanisms mediating IkappaBalpha proteolysis involved constitutive phosphorylation of IkappaBalpha at Ser32 and Ser36 and subsequent ubiquitination, suggesting persistent activation of an NF-kappaB inducing pathway. Interestingly, enhanced IkappaBalpha degradation did not result in enhanced NF-kappaB DNA binding activity, but rather in a different subunit composition. The modulation of NF-kappaB/IkappaB system may affect multiple immunoregulatory pathways and may in part explain the mechanisms leading to the profound immune dysregulation involved in MAIDS pathogenesis.     

Emergy required for the complete treatment of municipal wastewater

The continuous increase of human pressure on the environment and the concomitant pollution threat call for more complete and efficient environmental protection systems. Wastewater treatment plants are a technological response to the accumulation of pollution that occurs during the human-dominated phases of water cycle. In recent years, thanks to significant improvements in sewage treatment methodology, a number of upgrades have been assessed to improve the efficiency and functionality of treatment systems. Nonetheless, this activity requires large material and energy consumptions that have to be carefully accounted for when evaluating the efficiency of the process. In this work we present an emergy approach to the evaluation of a wastewater treatment plant located along the Ligurian coast (NW Mediterranean Sea). Besides the evaluation of the water treatment plant system, a preliminary assessment of the environmental costs in terms of natural fluxes required for the treatment process was performed. In fact, at the end of the treatment discharged water is still loaded with substances that have to be adsorbed by the receiving natural system. The work done by nature assimilating this load is generally considered as free while it is counted as a further cost in the total emergy budget of the water purification process.     

New mammalian cellular systems to study mutations introduced at the break site by non-homologous end-joining

The non-homologous end-joining (NHEJ) pathway is a mechanism to repair DNA double strand breaks, which can introduce mutations at repair sites. We constructed new cellular systems to specifically analyze sequence modifications occurring at the repair site. In particular, we looked for the presence of telomeric repeats at the repair junctions, since our previous work indicated that telomeric sequences could be inserted at break sites in germ-line cells during primate evolution. To induce specific DNA breaks, we used the I-SceI system of Saccharomyces cerevisiae or digestion with restriction enzymes. We isolated human and hamster cell lines containing the I-SceI target site integrated in a single chromosomal locus and we exposed the cells to a continuous expression of the I-SceI endonuclease gene. Additionally, we isolated human cell lines that expressed constitutively the I-SceI endonuclease and we introduced the target site on an episomal plasmid stably transfected into the cells. These strategies allowed us to recover repair junctions in which the I-SceI target site was modified at high frequency (100% in hamster cells and about 70% in human cells). Finally, we analyzed junctions produced on an episomal plasmid linearized by restriction enzymes. In all the systems studied, sequence analysis of individual repair junctions showed that deletions were the most frequent modifications, being present in more than 80% of the junctions. On the episomal plasmids, the average deletion length was greater than at intrachromosomal sites. Insertions of nucleotides or deletions associated with insertions were rare events. Junction organization suggested different mechanisms of formation. To check for the insertion of telomeric sequences, we screened plasmid libraries representing about 3.5 x 10(5) junctions with a telomeric repeat probe. No positive clones were detected, suggesting that the addition of telomeric sequences during double strand break repair in somatic cells in culture is either a very rare event or does not occur at all.     

Expression of Metalloproteinase 2 in the Cell Response to Porous Demineralized Bovine Bone Matrix

Summary The purpose of the study was to analyze the involvement of metalloproteinase 2 (MMP-2) and macrophages in the tissue and cell response to the organic graft material produced from bovine cancellous bone. Thirty adult male white Wistar rats (Rattus norvegicus) received implants of blocks of demineralized bovine bone matrix between the fasciae of the quadriceps muscle. The specimens collected at 3, 7, 14, 21 and 28 days after implantation (n = 6/period). Sections of 6 μm thick were stained with hematoxylin and eosin and immunolabeled with anti-MMP-2 and anti-CD68 using standard avidin–biotin–peroxidase method. The tissue response to the material was initially mediated by polymorphonuclear neutrophils, evolving to a mononuclear inflammatory infiltrate with macrophages and few lymphocytes and plasma cells and presence of inflammatory multinucleated giant cells (GC) in contact with the material that exhibited signs of resorption. The number of cells immunolabeled to MMP-2 was highest at day 7 (103.2 ± 39.1), but significantly decreased (F = 3.67; p = 0.044) until day 28 (45.9 ± 13.1). CD68 immunostaining also significantly decreased (F = 6.75; p = 0.007) from day 7 (49.5 ± 10.4) to day 28 (19.5 ± 8.9). A positive and statistically significant correlation was observed between the evolutions of these two variables. The material had been almost completely resorbed at day 28. Among cells present at the granuloma, anti-MMP-2 immunostaining was predominant and more intense in macrophages, yet lightly immunolabeled multinucleated giant cells were found in close contact with the material. Thus, considering the experimental limitations of this study, we concluded that MMP-2 produced by macrophages participates in the resorption of demineralized bovine bone.     

Conformational changes in CLIP-170 regulate its binding to microtubules and dynactin localization

Cytoplasmic linker protein (CLIP)-170, CLIP-115, and the dynactin subunit p150(Glued) are structurally related proteins, which associate specifically with the ends of growing microtubules (MTs). Here, we show that down-regulation of CLIP-170 by RNA interference results in a strongly reduced accumulation of dynactin at the MT tips. The NH(2) terminus of p150(Glued) binds directly to the COOH terminus of CLIP-170 through its second metal-binding motif. p150(Glued) and LIS1, a dynein-associating protein, compete for the interaction with the CLIP-170 COOH terminus, suggesting that LIS1 can act to release dynactin from the MT tips. We also show that the NH(2)-terminal part of CLIP-170 itself associates with the CLIP-170 COOH terminus through its first metal-binding motif. By using scanning force microscopy and fluorescence resonance energy transfer-based experiments we provide evidence for an intramolecular interaction between the NH(2) and COOH termini of CLIP-170. This interaction interferes with the binding of the CLIP-170 to MTs. We propose that conformational changes in CLIP-170 are important for binding to dynactin, LIS1, and the MT tips.