Modelling the effect of fishing on southern Buller's albatross using a 60-year dataset

Abstract

Many albatross populations are declining and a major cause is believed to be incidental mortality from fishing. We investigated the effect of fishing on southern Buller's albatross Thalassarche bulleri bulleri, using a new approach to seabird population modelling that allows estimation of demographic parameters from multiple data types. Three types of data were used: a 60-year set of mark–recapture observations, four censuses of the breeding population, and estimates of fishing effort and bycatch. The fisheries risk to the viability of this population over the last 60 years appears to have been small, since the adult population is estimated to have increased about five-fold over that time. There is some cause for concern in recent changes (population growth has slowed, and perhaps reversed, and adult survival rates are falling). The most common age at first breeding was 12 years, and about 80% of adults breed each year. Annual survival was estimated to be 0.91 for juveniles, and varied between this value and 1 for adults. Though this population is not in immediate danger from fishing, there is a need for continued monitoring to see whether the recent fall in survival rates persists and causes a decline in abundance. Our analysis showed that when, as is common, mark–recapture data do not provide good estimates of all demographic rates, the assessment of seabird population trends can be improved by the use of other types of data, particularly abundance.     

Nitrogen limitation of heterotrophic biofilms in boreal streams

相似文献   

Persistence with anti-tumour necrosis factor therapies in patients with psoriatic arthritis: observational study from the British Society of Rheumatology Biologics Register

Introduction  

Anti-TNF therapies represent a breakthrough in the treatment of severe psoriatic arthritis. However, little is known about long-term drug persistence with these treatments in patients with psoriatic arthritis in routine clinical practice. The aim of this study was to assess persistence with first-course and second-course treatment with anti-TNF agents in a prospective cohort of psoriatic arthritis patients and to identify factors associated with and reasons for drug discontinuation.     

Synthesis and enzymology of modifiedN-benzyloxycarbonyl-L-cysteinylglycyl-3,3-dimethylaminopropylamide disulphides as alternative substrates for trypanothione reductase fromTrypanosoma crud: Part 3

Summary Kinetic data for alternative substrates of recombinant trypanothione reductase fromTrypanosoma cruzi were measured for a series ofN-substituted-L-cysteinylglycyl-3-dimethylaminopropylamides, in which the cysteineN-substituent was either a variant of the benzyloxycarbonyl group or was L-phenylalanine or L-tryptophan. Replacing the benzylic ether oxygen atom by CH₂. or NH had relatively minor effects on k_cat, but raised the value of K_m, 4.5- and 10-fold, respectively. Similarly, relative to the carbobenzoxy group, anN-L-phenylalanyl orN-L-tryptophanyl replacement on the cysteine hardly altered k_cat, but increased K_m, values by 16.6 and 7.4 fold, respectively. These observations were consistent with the K_m, values referring primarily to binding for this series of nonspecific substrates.Abbreviations DCC N,N-dicyclohexylcarbodiimide - dmapa dimethylaminopropylamine - DMF dimethylformamide - GR glutathione reductase - GSSG glutathione disulphide - GSH reduced glutathione - T[S]₂ trypanothione disulphide - Hbt hydroxybenzotriazole - TFA trifluoroacetic acid - TLC thin layer chromatography - T[SH]₂ reduced trypanothione as dithiol - TR trypanothione reductase - Z.cys.gly.dmapa N-benzyloxycarbonyl-Lcysteinylglycyl-3-dimethylpropylamide     

Functional characterization of human duodenal cytochrome b (Cybrd1): Redox properties in relation to iron and ascorbate metabolism

Duodenal cytochrome b (Dcytb or Cybrd1) is an iron-regulated protein, highly expressed in the duodenal brush border membrane. It has ferric reductase activity and is believed to play a physiological role in dietary iron absorption. Its sequence identifies it as a member of the cytochrome b(561) family. A His-tagged construct of human Dcytb was expressed in insect Sf9 cells and purified. Yields of protein were increased by supplementation of the cells with 5-aminolevulinic acid to stimulate heme biosynthesis. Quantitative analysis of the recombinant Dcytb indicated two heme groups per monomer. Site-directed mutagenesis of any of the four conserved histidine residues (His 50, 86, 120 and 159) to alanine resulted in much diminished levels of heme in the purified Dcytb, while mutation of the non-conserved histidine 33 had no effect on the heme content. This indicates that those conserved histidines are heme ligands, and that the protein cannot stably bind heme if any of them is absent. Recombinant Dcytb was reduced by ascorbate under anaerobic conditions, the extent of reduction being 67% of that produced by dithionite. It was readily reoxidized by ferricyanide. EPR spectroscopy showed signals from low-spin ferriheme, consistent with bis-histidine coordination. These comprised a signal at gmax=3.7 corresponding to a highly anisotropic species, and another at gmax=3.18; these species are similar to those observed in other cytochromes of the b561 family, and were reducible by ascorbate. In addition another signal was observed in some preparations at gmax=2.95, but this was unreactive with ascorbate. Redox titrations indicated an average midpoint potential for the hemes in Dcytb of +80 mV+/-30 mV; the data are consistent with either two hemes at the same potential, or differing in potential by up to 60 mV. These results indicate that Dcytb is similar to the ascorbate-reducible cytochrome b561 of the adrenal chromaffin granule, though with some differences in midpoint potentials of the hemes.     

Microbial diversity and complexity in hypersaline environments: A preliminary assessment

The microbial communities in solar salterns and a soda lake have been characterized using two techniques: BIOLOG, to estimate the metabolic potential, and amplicon length heterogeneity analysis, to estimate the molecular diversity of these communities. Both techniques demonstrated that the halophilic Bacteria and halophilic Archaea populations in the Eilat, Israel saltern are dynamic communities with extensive metabolic potentials and changing community structures. Halophilic Bacteria were detected in Mono Lake and the lower salinity ponds at the Shark Bay saltern in Western Australia, except when the crystallizer samples were stressed by exposure to Acid Green Dye #9899. At Shark Bay, halophilic Archaea were found only in the crystallizer samples. These data confirm both the metabolic diversity and the phylogenetic complexity of the microbial communities and assert the need to develop more versatile media for the cultivation of the diversity of bacteria in hypersaline environments. Journal of Industrial Microbiology & Biotechnology (2002) 28, 48–55 DOI: 10.1038/sj/jim/7000175 Received 20 May 2001/ Accepted in revised form 15 June 2001     

Animal models with enhanced erythropoiesis and iron absorption

The regulation of iron absorption is of considerable interest in mammals since excretion is minimal. Recent advances in iron metabolism have expounded the molecular mechanisms by which iron absorption is attuned to the physiological demands of the body. The pinnacle was the discovery and identification of hepcidin, a hepatic antimicrobial peptide that regulates absorption to maintain iron homeostasis. While the intricacies of its expression and regulation by HFE, transferrin receptor 2 and hemojuvelin are still speculative, hepcidin responsiveness has correlated negatively with iron absorption in different models and disorders of iron metabolism. Consequently, hepcidin expression is repressed to enhance iron absorption during stimulated erythropoiesis even in situations of elevated iron stores. Animal models have been crucial to the advances in understanding iron metabolism and the present review focuses on phenylhydrazine treated and hypotransferrinaemic rodents. These, respectively, experimental and genetic models of enhanced erythropoiesis highlight the shifting focus of iron absorption regulation from the marrow to the liver.     

Placing biodiversity and ecosystem functioning in context: environmental perturbations and the effects of species richness in a stream field experiment

Greater biodiversity is often associated with increased ecosystem process rates, and is expected to enhance the stability of ecosystem functioning under abiotic stress. However, these relationships might themselves be altered by environmental factors, complicating prediction of the effects of species loss in ecosystems subjected to abiotic stress. In boreal streams, we investigated effects of biodiversity and two abiotic perturbations on three related indices of ecosystem functioning: leaf decomposition, detritivore leaf processing efficiency (LPE) and detritivore growth. Replicate field enclosures containing leaves and detritivore assemblages were exposed to liming and nutrient enrichment, raising pH and nutrient levels. Both treatments constitute perturbations for our naturally acidic and nutrient-poor streams. We also varied detritivore species richness and density. The effects of the abiotic and diversity manipulations were similar in magnitude, but whereas leaf decomposition increased by 18% and 8% following liming and nutrient enrichment, respectively, increased detritivore richness reduced leaf decomposition (6%), detritivore LPE (19%) and detritivore growth (12%). The detritivore richness effect on growth was associated with negative trait-independent complementarity, indicating interspecific interference competition. These interactions were apparently alleviated in both enriched and limed enclosures, as trait-independent complementarity became less negative. LPE increased with detritivore density in the monocultures, indicating benefits of intra-specific aggregation that outweighed the costs of intra-specific competition, and dilution of these benefits probably contributed to lowered leaf decomposition in the species mixtures. Finally, the effects of liming were reduced in most species mixtures relative to the monocultures. These results demonstrate how environmental changes might regulate the consequences of species loss for functioning in anthropogenically perturbed ecosystems, and highlight potential influences of biodiversity on functional stability. Additionally, the negative effects of richness and positive effects of density in our field study were opposite to previous laboratory observations, further illustrating the importance of environmental context for biodiversity–ecosystem functioning relationships.     

Forefoot disease activity in rheumatoid arthritis patients in remission: results of a cohort study

Introduction  

The aim of our study was to investigate the presence of disease activity in the metatarsophalangeal (MTP) joints of the forefoot in rheumatoid arthritis (RA) patients in remission according to the Disease Activity Score based on 28 joints (DAS28) remission criterion.