50 research outputs found
Trends in the Offshore Distribution and Relative Abundance of Beaufort Sea Belugas, 1982â85 vs 2007â09
We used systematic strip-transect aerial surveys to examine the distribution and relative abundance of surfaced belugas in the offshore Beaufort Sea in late August of 1982, 1984â85, and 2007â09. Belugas were seen throughout the offshore area in both survey series, on 114 of 149 transects (76.5%). They were common over the continental shelf offshore of the Tuktoyaktuk Peninsula and within 30 km seaward of the Mackenzie River estuary, but they were also seen in most other offshore habitats surveyed. The distribution of belugas had a similar pattern in both series, but the number of surfaced belugas counted was higher in the 2000s than in the 1980s. In total, 305 belugas (145 sightings, mean group size 2.1) were observed on-transect in 20 858 km2 of surveying in the 1980s, and more than three times that number (1061) were observed in a similar area (19 829 km2) during the 2007â09 survey series (378 sightings; mean group size 2.6). Population growth alone, though probably not sufficient to explain the changes observed in relative abundance between decades, could be partly responsible for the apparent increase in belugas. The most plausible explanation is that the offshore became more attractive to belugas in the 2000s, because of either a decrease in the intensity or extent of industrial activity or changes to the marine ecosystem related to climate warming, or both.Nous avons utilisĂ© des levĂ©s aĂ©riens systĂ©matiques par transects en bandes pour examiner la rĂ©partition et lâabondance relative des bĂ©lugas faisant surface au large de la mer de Beaufort Ă la fin dâaoĂ»t 1982, dâaoĂ»t 1984 Ă 1985 et dâaoĂ»t 2007 Ă 2009. Des bĂ©lugas ont Ă©tĂ© aperçus au large dans les deux sĂ©ries de levĂ©s et ce, dans 114 des 149 transects (76,5 %). Les bĂ©lugas Ă©taient courants au large du plateau continental de la pĂ©ninsule Tuktoyaktuk ainsi que dans un rayon de 30 km du cĂŽtĂ© mer de lâestuaire du fleuve Mackenzie, bien quâils aient Ă©galement Ă©tĂ© aperçus dans la plupart des autres habitats Ă©tudiĂ©s au large. Dans les deux sĂ©ries, la rĂ©partition de bĂ©lugas se ressemblait, mais le nombre de bĂ©lugas faisant surface Ă©tait plus Ă©levĂ© dans les annĂ©es 2000 que dans les annĂ©es 1980. Au total, 305 bĂ©lugas (145 observations, taille moyenne du groupe de 2,1) ont Ă©tĂ© observĂ©s dans les transects des 20 858 km2 Ă©tudiĂ©s dans les annĂ©es 1980, et plus de trois fois ce nombre (1 061) ont Ă©tĂ© observĂ©s dans une aire semblable (19 829 km2) dans les annĂ©es 2007 Ă 2009 (378 observations, taille moyenne du groupe de 2,6). Lâaccroissement de la population seul pourrait ĂȘtre responsable en partie de lâaugmentation apparente du nombre de bĂ©lugas, bien que ce facteur ne suffise probablement pas Ă expliquer les changements observĂ©s sur le plan de lâabondance relative dâune dĂ©cennie Ă lâautre. Lâexplication la plus plausible serait que les bĂ©lugas ont Ă©tĂ© davantage attirĂ©s par le secteur extracĂŽtier dans les annĂ©es 2000 soit en raison de la diminution de lâintensitĂ© ou de lâampleur de lâactivitĂ© industrielle, soit en raison des changements Ă lâĂ©cosystĂšme marin attribuables au rĂ©chauffement climatique, soit en raison dâun ensemble de ces deux causes
An Emerging Pattern of Declining Growth Rates in Belugas of the Beaufort Sea: 1989â2008
Standardized, hunter-based sampling of harvested beluga whales was initiated in the three main harvesting areas of the Mackenzie River delta (Shallow Bay, Kendall Island, Kugmallit Bay) in 1980 and near Paulatuk, Northwest Territories, in 1989. Standard length and sex of landed whales have been recorded for 90 to 110 belugas per year since 1980, and ages have been determined since 1988. Hunters select larger and older belugas; males outnumbered females 2.0 to 1 between 1980 and 1989, 3.0 to 1 between 1990 and 1999, and 3.6 to 1 between 2000 and 2009. Age classes younger than 10 growth layer groups (GLGs) were essentially absent from harvests both in the Delta and near Paulatuk. Asymptotic lengths, calculated using GLG counts from teeth of 839 males and 225 females sampled over 16 seasons (1989, 1993 â 2008), were 435.3 cm (SE 2.0) for males and 380.1 cm (SE 1.8) for females. Males were 14.5% longer than females. Belugas landed in the Delta and Paulatuk were mainly mature adults (by hunter selection). Mature belugas landed by Paulatuk hunters were younger and shorter than those taken in the Delta because of age and sex segregation in the hunting areas. There was no difference in the size-at-age relationships for belugas landed at Paulatuk vs the Delta. The linear trend in size-at-age indicated a decline of 0.08% (SE 0.038%) per year, or 1.75% over the 19 year time series. The 314 male belugas landed in the Delta between 2000 and 2007 showed statistically significant differences in blubber thickness among years, but only a slight downward trend over this short period. Mean blubber was thickest in 2002 and 2003 and thinnest in 2005. The thinness of belugas in 2005, and subtle changes in growth of the belugas over the time series, may reflect ecosystem changes that have reduced the availability or quality and quantity of their prey in recent years. Further research, including isotope and fatty acid profiling, would be helpful in substantiating the declining trend in growth and elucidating the causative factors.Des Ă©chantillons standardisĂ©s provenant de pĂȘcheurs ayant capturĂ© des bĂ©lugas ont Ă©tĂ© prĂ©levĂ©s dans trois lieux de capture principaux du delta du fleuve Mackenzie (baie Shallow, Ăźle Kendall et baie Kugmallit) en 1980 et prĂšs de Paulatuk, dans les Territoires du Nord-Ouest, en 1989. La longueur standard et le sexe des baleines dĂ©barquĂ©es ont Ă©tĂ© enregistrĂ©s dans le cas de 90 Ă 110 bĂ©lugas par annĂ©e depuis 1980, et les Ăąges ont Ă©tĂ© dĂ©terminĂ©s depuis 1988. Les pĂȘcheurs choisissent les bĂ©lugas qui sont plus gros et plus ĂągĂ©s. Le nombre de mĂąles a dĂ©passĂ© le nombre de femelles dans une mesure de 2,0 contre 1 entre 1980 et 1989, de 3,0 contre 1 entre 1990 et 1999, et de 3,6 contre 1 entre 2000 et 2009. Les classes dâĂąge plus jeunes que dix groupes de couches dâaccroissement (GCA) Ă©taient pour ainsi dire absentes des rĂ©coltes du delta et de la proximitĂ© de Paulatuk. Les longueurs asymptotiques, calculĂ©es au moyen des dĂ©nombrements de GCA Ă partir des dents de 839 mĂąles et de 225 femelles Ă©chantillonnĂ©s au cours de 16 saisons (1989, 1993-2008) Ă©taient de 435,3 cm (ET de 2,0) chez les mĂąles et de 380,1 cm (ET de 1,8) chez les femelles. Les mĂąles Ă©taient plus longs que les femelles dans une mesure de 14,5 %. Les bĂ©lugas dĂ©barquĂ©s dans le delta et Ă Paulatuk Ă©taient surtout des adultes en pleine maturitĂ© (en raison du choix des pĂȘcheurs). Les bĂ©lugas adultes dĂ©barquĂ©s par les pĂȘcheurs de Paulatuk Ă©taient plus jeunes et moins longs que ceux capturĂ©s dans le delta en raison de la sĂ©grĂ©gation entre les sexes et de lâĂąge dans les zones de pĂȘche. Il nây avait pas de diffĂ©rence dans les relations en fonction de la taille selon lâĂąge pour les bĂ©lugas dĂ©barquĂ©s Ă Paulatuk par rapport Ă ceux dĂ©barquĂ©s au delta. La tendance linĂ©aire dans la taille selon lâĂąge a fait ressortir un dĂ©clin de 0,08 % (ET de 0,038 %) par annĂ©e, soit 1,75 % pour la sĂ©rie temporelle de 19 ans. Les 314 bĂ©lugas mĂąles dĂ©barquĂ©s dans le delta entre 2000 et 2007 ont affichĂ© dâimportantes diffĂ©rences statistiques sur le plan de lâĂ©paisseur du lard au fil des ans, mais seulement une faible tendance Ă la baisse pendant cette courte pĂ©riode. LâĂ©paisseur moyenne du lard Ă©tait Ă son point le plus Ă©levĂ© en 2002 et en 2003, et Ă son point le plus faible en 2005. La maigreur des bĂ©lugas en 2005 et les changements mineurs sur le plan de la croissance des bĂ©lugas au cours de la sĂ©rie temporelle pourraient ĂȘtre le reflet de changements caractĂ©risant lâĂ©cosystĂšme, changements qui ont eu pour effet de rĂ©duire la disponibilitĂ© ou la qualitĂ© et la quantitĂ© des proies des baleines ces derniĂšres annĂ©es. Des recherches plus poussĂ©es, prenant notamment la forme du profilage des isotopes et des acides gras, aideraient Ă valider la tendance Ă la baisse en matiĂšre de croissance et Ă Ă©lucider les facteurs causals
Ringed Seals and Sea Ice in Canadaâs Western Arctic: Harvest-Based Monitoring 1992â2011
We examined the relationship between ringed seal body condition and reproduction and spring sea ice conditions in prime ringed seal habitat in Canadaâs western Arctic during 1992 â 2011. Since 1970, ice conditions in east Amundsen Gulf and west Prince Albert Sound have shown only a slight trend toward earlier ice clearance (breakup) in spring (3 â 7 days per decade) (p < 0.10) and no trend toward later freeze-up or increased variability in timing of spring ice clearance. A subsistence harvest â based sample of 2281 ringed seals was obtained during 1992 â 2011 from Masoyak, a traditional hunting camp located on the northwest shore of west Prince Albert Sound and less than 5 km from east Amundsen Gulf. The results revealed a statistically significant trend of decreasing mean annual body condition of ringed seals (using an index of length-mass-blubber depth [LMD]: adults, 0.14 m1.5/kg0.5/y; subadults, 0.24 m1.5/kg0.5/y) over the past two decades. A parallel result was that mean annual body condition of adults and subadults was correlated with the timing of fast ice clearance in spring (later ice clearance = worse condition). This correlation was most obvious in the extreme ice years in all sex/age groupings and was statistically significant for subadults. In mature females sampled since 1992, annual ovulation rates averaged 92.4 ± 16.3% (SD) and were greater than 80%, and mostly at 100%, in all years but two. Failure to ovulate was obvious in 2005, the most extreme late ice clearance year in our series, when only 30.0% of the mature adult females sampled ovulated. At the same time, values for seal body condition indices (adult females, LMD = 11.3; adult males, LMD = 12.4) and percent pups in the harvest (3.3%) were among the lowest recorded, and spring ice clearance was 38 d later than the 1992 â 2011 average. While this and previous studies indicate that the seal population in this core habitat has recovered from natural and extreme-year sea ice fluctuations over the past four decades, the potentially magnified effect of several consecutive extreme ice years, compounded by the concurrent decline in seal body condition that we have now detected over the past 20 years, is of particular concern.Nous avons examinĂ© le lien qui existe entre lâĂ©tat corporel du phoque annelĂ©, lâĂ©tat de reproduction de ce phoque et lâĂ©tat de la glace de mer printaniĂšre dans son habitat dâĂ©lection de lâouest de lâArctique canadien et ce, entre 1992 et 2011. Depuis 1970, lâĂ©tat de la glace dans lâest du golfe Amundsen et dans lâouest du dĂ©troit de Prince-Albert nâa affichĂ© quâune petite tendance vers une dĂ©bĂącle printaniĂšre plus hĂątive (de 3 Ă 7 jours par dĂ©cennie) (p < 0,10) et aucune tendance vers un englacement plus tardif ou une variabilitĂ© accrue caractĂ©risant la pĂ©riode de la dĂ©bĂącle du printemps. Un Ă©chantillon recueilli Ă partir de 2 281 phoques annelĂ©s ayant fait lâobjet dâune rĂ©colte de subsistance a Ă©tĂ© obtenu entre 1992 et 2011 Ă Masoyak, un camp de chasse traditionnel situĂ© sur la cĂŽte nord-ouest de lâouest du dĂ©troit de Prince-Albert et Ă moins de cinq kilomĂštres de lâest du golfe Amundsen. Les rĂ©sultats ont permis de constater une tendance statistiquement significative sur le plan de la dĂ©croissance de lâĂ©tat corporel annuel moyen des phoques annelĂ©s (en fonction dâun indice de la profondeur et de la longueur de la masse du petit lard [LMD] : reproducteurs, 0,14 m1,5/kg0,5/a; prĂ©reproducteurs, 0,24 m1,5/kg0,5/a) au cours des deux derniĂšres dĂ©cennies. Un rĂ©sultat parallĂšle a permis de corrĂ©ler lâĂ©tat corporel annuel moyen des reproducteurs et des prĂ©reproducteurs Ă la pĂ©riode dâune dĂ©bĂącle printaniĂšre rapide (dĂ©bĂącle tardive = pire Ă©tat). Cette corrĂ©lation Ă©tait plus Ă©vidente au cours des annĂ©es oĂč la glace Ă©tait extrĂȘme chez tous les groupements en fonction du sexe ou de lâĂąge, et elle Ă©tait statistiquement significative chez les prĂ©reproducteurs. Parmi les femelles matures Ă©chantillonnĂ©es depuis 1992, les taux dâovulation annuels atteignaient 92,4 ± 16,3 % (DS) en moyenne, et Ă©taient plus grands que 80 %, et Ă prĂšs de 100 % au cours de toutes les annĂ©es, sauf deux. Lâanovulation Ă©tait Ă©vidente en 2005, ce qui correspondait Ă lâannĂ©e de notre sĂ©rie oĂč la dĂ©bĂącle a Ă©tĂ© la plus tardive, lorsque seulement 30,0 % des femelles adultes et matures qui avaient Ă©tĂ© Ă©chantillonnĂ©es ont ovulĂ©. En mĂȘme temps, les valeurs relatives aux indices de lâĂ©tat corporel des phoques (femelles adultes, LMD = 11,3; mĂąles adultes, LMD = 12,4) et au pourcentage de petits faisant partie de la rĂ©colte (3,3 %) figuraient parmi les valeurs les plus basses Ă nâavoir jamais Ă©tĂ© enregistrĂ©es, et la dĂ©bĂącle printaniĂšre Ă©tait plus tardive de 38 jours par rapport Ă la moyenne de 1992-2011. Bien que cette Ă©tude et des Ă©tudes antĂ©rieures laissent croire que la population de phoques de cet habitat important a rĂ©ussi Ă se remettre des fluctuations naturelles et extrĂȘmes des conditions de glace des quatre derniĂšres dĂ©cennies, lâeffet potentiellement grossissant de plusieurs annĂ©es consĂ©cutives de glace extrĂȘme, alliĂ© au dĂ©clin concurrent de lâĂ©tat corporel des phoques que nous avons dĂ©celĂ© au cours des 20 derniĂšres annĂ©es, prĂ©sente une source dâinquiĂ©tude particuliĂšre
Percepção e medidas de gestão de riscos por produtores de arroz irrigado na Fronteira Oeste do Rio Grande do Sul
New insights into the genetic etiology of Alzheimer's disease and related dementias
Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE Δ4 allele
Multiancestry analysis of the HLA locus in Alzheimerâs and Parkinsonâs diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes
Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinsonâs disease (PD) and Alzheimerâs disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased AÎČ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues
Metabolism-dependent taxis towards (methyl)phenols is coupled through the most abundant of three polar localized Aer-like proteins of Pseudomonas putida
Identification and analysis of a glutaryl-CoA dehydrogenase-encoding gene and its cognate transcriptional regulator from Azoarcus sp. CIB
9 pĂĄginas, 3 figuras, 1 tabla -- PAGS nros. 474-482In this work, the gcdH gene from the denitrifying ÎČ-proteobacterium Azoarcus sp. CIB was shown to encode a glutaryl-CoA dehydrogenase, which is essential for the anaerobic catabolism of many aromatic compounds and some alicyclic and dicarboxylic acids. The primary structure of the GcdH protein is highly conserved in many organisms. The divergently transcribed gcdR gene, encoding a LysR-type transcriptional regulator, accounts for the glutaconate/glutarate-specific activation of the Pg promoter driving expression of gcdH. The Azoarcus sp. CIBdgcdH mutant strain harbouring a disrupted gcdH gene was used as host to identify heterologous gcdH genes, such as that from Pseudomonas putida KT2440. Moreover, the expression of gcdH from P. putida can be efficiently controlled by the GcdR activator in Azoarcus sp. CIB, demonstrating the existence of cross-talk between GcdR regulators and gcdH promoters from members of different phylogenetic subgroups of proteobacteriaThis work was supported by Grants BIO2003-01482, BIO2006-05957, VEM2003-20075-CO2-02 and GEN2006-27750-C5-3-E/SYS from the Spanish Ministerio de EducaciĂłn y Ciencia, and by Grant P-AMB-259â0505 from the Comunidad AutĂłnoma de Madrid. B. BlĂĄzquez was supported by a predoctoral fellowship associated to Projects BIO2003-01482 and CSIC2006 2 0I 069Peer reviewe