Increased adult mortality and reduced breeding success with age in a population of common guillemot Uria aalge using marked birds of unknown age

Although there is general consensus about the existence of senescence in vertebrates, empirical evidence of senescence in demographic parameters in wild populations is limited. Data on breeding success and survival of breeding common guillemots Uria aalge were collected over 20 years on the Isle of May (Scotland) using a pool of individuals marked as adults. Because the years of hatching of individuals were not known, we used the time (years) elapsed since first capture (TFC) as a measure of age. The use of this proxy did not create any bias in estimating senescence in the case of a linear decline, nor did it greatly decrease the power of a test for senescence. Breeding success declined significantly from 0.81 (95% CI: 0.77–0.84) to 0.62 (0.54–0.68) over the study period. It also varied in relation to age, initially increasing (from 0.62 (0.54–0.68) at TFC of 0 year to 0.76 (0.73–0.79) at TFC of 9 years) up to a plateau (from TFC of 9 years with 0.76 (0.73–0.79) until TFC of 13 years with 0.77 (0.74–0.79) before declining in later life to 0.70 (0.61–0.78) at TFC of 19 years). Survival was generally high and varied significantly from year to year. It also declined with TFC: survival of birds marked in 1982 decreased from 0.92 (0.85–0.96) at a TFC of 0 year to 0.88 (0.82–0.92) at a TFC of 19 years. Resighting probabilities also declined with TFC suggesting that the oldest birds do not come back to the colony to breed as regularly as younger individuals. These findings indicate that individual common guillemots on the Isle of May showed both actuarial and reproductive senescence.     

Long-term removal of wheat straw decreases soil amorphous silica at Broadbalk, Rothamsted

Aims

Most cereals accumulate Si in their shoots. Soil bioavailability of Si may be a constraint on the beneficial role of silica in cereals but it is not yet well supported by field data. The aim of this study is to evaluate the long-term impact of wheat straw exports on the pool of soil phytoliths, which, it is suggested, represents the most labile and renewable pool of soil Si.

Methods

We measured the amorphous Si (ASi) in soils from several experiments at Rothamsted Research (UK), which provided long-term soil data back to the middle of the 19th century, using two alternative extraction techniques: Na₂CO₃ (referred to as AS_nc) or zinc bromide extraction (referred to as ASi_zb).

Results

All samples showed a similar range of AS_nc and ASi_zb but low values (0.1–3.4?mg?g^?1 DW) compared to published data on natural ecosystems. In the Broadbalk experiment, a decrease over time in ASi in the topsoil samples is in good agreement with the hypothesis that cropping and exports of straw leads to depletion of soil phytoliths. A decrease in Si concentration in straw samples was observed between 1883 and 1944. From 1944 to the present, Si concentration increased irregularly in the straw, probably as the result of liming, which enhanced the dissolution of the remaining phytoliths through increasing pH. In the reforested Geescroft field the higher phytolith concentration in the modern topsoil samples is in good agreement with a re-building of phytolith storage from litter input in an acidic environment.

Conclusions

Our results therefore support the hypothesis that export of wheat straw leads to a decrease in bioavailable Si.     

An improved procedure to estimate wolf abundance using non-invasive genetic sampling and capture–recapture mixture models

Non-invasive genetic sampling (NGS) is increasingly used to estimate the abundance of rare or elusive species such as the wolf (Canis lupus), which cannot be directly counted in forested mountain habitats. Wolf individual and familial home ranges are wide, potentially connected by long-range dispersers, and their populations are intrinsically open. Appropriate demographic estimators are needed, because the assumptions of homogeneous detection probability and demographic closeness are violated. We compiled the capture–recapture record of 418 individual wolf genotypes identified from ca. 4,900 non-invasive samples, collected in the northern Italian Apennines from January 2002 to June 2009. We analysed this dataset using novel capture–recapture multievent models for open populations that explicitly account for individual detection heterogeneity (IDH). Overall, the detection probability of the weakly detectable individuals, probably pups, juveniles and migrants (P = 0.08), was ca. six times lower than that of the highly detectable wolves (P = 0.44), probably adults and dominants. The apparent annual survival rate of weakly detectable individuals was lower (Φ = 0.66) than those of highly detectable wolves (Φ = 0.75). The population mean annual finite rate of increase was λ = 1.05 ± 0.11, and the mean annual size ranged from N = 117 wolves in 2003 to N = 233 wolves in 2007. This procedure, combining large-scale NGS and multievent IDH demographic models, provides the first estimates of abundance, multi-annual trend and survival rates for an open large wolf population in the Apennines. These results contribute to deepen our understanding of wolf population ecology and dynamics, and provide new information to implement sound long-term conservation plans.     

Selective roles for cholesterol and actin in compartmentalization of different proteins in the Golgi and plasma membrane of polarized cells

To determine the roles of cholesterol and the actin cytoskeleton in apical and basolateral protein organization and sorting, we have performed comprehensive confocal fluorescence recovery after photobleaching analyses of apical and basolateral and raft- and non-raft-associated proteins, both at the plasma membrane and in the Golgi apparatus of polarized MDCK cells. We show that at both the apical and basolateral plasma membrane domains, raft-associated proteins diffuse faster than non-raft-associated proteins and that, different from the latter, they become restricted upon depletion of cholesterol. Furthermore, only transmembrane apical proteins are restricted by the actin network. This indicates that cholesterol-dependent domains exist both at the apical and basolateral membranes of polarized cells and that the actin cytoskeleton has a predominant role in the organization of transmembrane proteins independent of their association with rafts at the apical membrane. In the Golgi apparatus apical proteins appear to be segregated from the basolateral ones in a compartment that is sensitive both to cholesterol depletion and actin rearrangements. Furthermore, consistent with the role of actin rearrangements in apical protein sorting, we found that apical proteins exhibit a differential sensitivity to actin depolymerization in the Golgi of polarized and nonpolarized cells.     

Interleukin-6 (IL-6) and acute-phase proteins in rats with biliary sepsis.

We measured serum interleukin-6 (IL-6) and acute-phase proteins, alpha 1-acid glycoprotein (AGP) and alpha 2-macroglobulin (alpha 2M), after a retrograde intrabiliary bacterial infection in rats with biliary obstruction. Maximum serum IL-6 was obtained at 6 h in rats following inoculation of bacteria (10(6) CFU/ml E. Coli) in the bile duct and it was higher than that observed in rats undergoing a bile duct ligation or a laparotomy. There was a strict relationship between the level of IL-6 at 6 h and the modified levels of AGP and alpha 2M at 48 h. AGP and alpha 2M levels were the highest in sera of rats with bile duct infection as compared with those found in sera of rats with bile duct ligation or laparotomy. After inoculation of E. Coli or E. Fecalis, blood IL-6 level was always higher at 6 h in inferior vena cava as compared with that found in the supra hepatic vein. These results indicate that IL-6 is synthesized after a biliary sepsis and that its blood level is higher in the systemic circulation than in the local circulation.     

Chimiotaxinomie flavonique des fluviales

The flavonoid patterns of twenty-three species of Fluviales (= Helobieae) were determined. Flavonols and pro-anthocyanidins are uncommon and trihydroxy derivatives are absent. In contrast, flavones (luteolin and chrysoeriol derivatives) are common, often as C-glycosides (Alismataceae, Butomaceae, Potamogetonaceae). From a taxonomic point of view the results suggest that the Fluviales can be divided into two groups: Potamogetonaceae. Zosteraceae, Ruppiaceae, Zanichelliaceae and Juncaginaceae forming the first, and Hydrocharitaceae, Butomaceae. Alismataceae and Aponogetonaceae the second. This arrangement agrees for the most part with the views of Emberger and Takhtajan.

Résumé

Le contenu flavonique de 23 Fluviales (= Hélobiées) a été analysé. Flavonols et leuco-anthocyanes sont rares, les dérivés phényl-trihydroxylés absents. Les flavones, par contre, sont fréquentes (lutéoline, chrysoériol). notamment sous forme de C-glycosides (Alismatacées, Butomacées, Potamogétonacées). D'un point de vue taxinomique, les résultats permettent de regrouper, d'une part Potamogétonacées, Zostéracées, Ruppiacées. Zanichelliacées et Juncaginacées; d'autre part Hydrocharitacées, Butomacées, Alismatacées et Aponogétonacées. Cette proposition s'accorde dans ses grandes lignes avec les rues des botanistes Emberger et Takhtajan.     

Memory and imprinting in multienzyme complexes. Evidence for information transfer from glyceraldehyde-3-phosphate dehydrogenase to phosphoribulokinase under reduced state in Chlamydomonas reinhardtii.

The phosphoribulokinase, when it is in a reduced state in a bi-enzyme complex, is more active than when it is oxidized. This complex dissociates upon dilution to give a metastable reduced form of phosphoribulokinase, which differs from the stable form isolated beside the complex. The kinetic parameters of the reduced stable phosphoribulokinase and those of the complex are very similar, unlike those of the metastable form. Although the kinetic mechanism of the reduced stable form is ordered, with ribulose-5-phosphate binding first, ATP binds first to the phosphoribulokinase in the complex and to the metastable form. Therefore, phosphoribulokinase bears an imprint from glyceraldehyde-3-phosphate dehydrogenase after disruption of the complex. Dissociation of phosphoribulokinase from the complex also enhances its flexibility. The imprinting and greater flexibility result in the catalytic constant of dissociated phosphoribulokinase being 10-fold higher than that of the enzyme in the complex. Imprinting corresponds to stabilization-destabilization energies resulting from conformation changes generated by protein-protein interactions. The energy stored within the metastable phosphoribulokinase is mainly used to decrease the energy barrier to catalysis.     

Epidemiology of trace elements deficiencies in Belgian beef and dairy cattle herds

Selenium (Se), iodine (I), zinc (Zn) and copper (Cu) deficiencies in cattle have been reported in Europe. These deficiencies are often associated with diseases. The aim of the study was to assess trace element status in Belgian cattle herds showing pathologies and to compare them to healthy cattle herds. Eighty-two beef herds with pathologies, 11 healthy beef herds, 65 dairy herds with pathologies and 20 healthy dairy herds were studied during barn period. Blood and/or milk samples were taken in healthy animals. Plasma Zn, Cu, inorganic I (PII) and activity of glutathione peroxidase in erythrocytes (GPX) were assayed. In milk, I concentration was measured. Data about pathologies and nutrition in the herds were collected. According to defined thresholds, it appeared that a large proportion of deficient herds belonged to “sick” group of herds. This conclusion was supported by the mean value of trace elements and by the fact that a majority of individual values of trace elements was below the threshold. Dairy herds had mean values of trace elements higher than beef herds. More concentrates and minerals were used in healthy herds versus “sick” herds. These feed supplements were also used more often in dairy herds, compared to beef herds. Trace elements deficiencies are present in cattle herds in Belgium and are linked to diseases. Nutrition plays a major role in the trace elements status.