Shell choice and occupation by the hermit crab (Crustacea: Diogenidae) in laboratory environment

The Neotropical hermit crabs’ behaviour is rarely studied, although it is an important tool for the conservation of these invertebrates. In this context, the present study aimed to describe the hermit crab ethogram on its behaviour in the choice and dispute by shells. 60 specimens of hermit crabs were collected that were occupying mollusc shells Cerithium atratum, in sandstone reefs. In the laboratory, 30 hermit crabs were removed from their host shells by heating, the rest remained in their shells. The specimens were submitted to five experimental tests: (I) behaviour, (II) shell dispute, (III) shell preference, (IV) specimen behaviour with and without shell, and (V) shell contention between individuals with and without shell. The ethogram was built and evaluated by the Ad Libitum type of observational sampling methods and by the scanning type, for 30 uninterrupted minutes, records every two minutes, in total 15 observations per each observer. There were eight behavioural acts divided into 4 categories: immobility, interaction between specimen, environment exploration, and shell occupation. The most frequent behaviour was "walking", for both hermit crabs (54.2%) and those without shell (59.3%), followed by the rest of the individuals with and without shell, 16.9% and 12.4%, respectively. All hermits preferred mollusc shell Bulla striata, when offered in conjunction with the shell of Astrea tecta. However, all specimens returned to C. atratum shells when it was experimentally offered with all shells. Studies with hermits have shown that the species has preferences of gastropods shell C. atratum

Multiancestry analysis of the HLA locus in Alzheimer’s and Parkinson’s 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 Parkinson’s disease (PD) and Alzheimer’s 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 Aβ42. 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

Aspectos da história natural de Frostius pernambucensis Bokermann, 1962 (Amphibia, Anura, Bufonidae), em um remanescente de mata atlântica no Nordeste do Brasil

A espécie de Frostius pernambucensis Bokermann 1962 é membro dos bufonídeos, pertence ao gênero Frostius Cannatella 1986, gênero endêmico da mata Atlântica Nordestina. Possui como localidade tipo o Parque Estadual de Dois Irmãos, no qual foi documentado recentemente após 50 anos do último registro. Nesse contexto, o presente estudo teve como objetivo descrever os aspectos reprodutivos e comportamentais da espécie de F. pernambucensis, em sua localidade tipo, bem como, modelar áreas potenciais para sua distribuição geográfica. As observações ocorreram em uma área de conservação ambiental, no Parque Estadual de Dois Irmãos (Nordeste do Brasil), com a realização de observações diurnas e noturnas, no período de outubro de 2014 a abril de 2017, em nove campanhas de dez dias consecutivos. Para a modelagem de nicho ecológico, foi utilizado o algoritmo de máxima entropia (MaxEnt), aplicando-se os pontos de ocorrência e variáveis ambientais já estabelecidos. Um total de 17 indivíduos de F. pernambucensis foi registrado. Esses exemplares utilizavam como substratos para sítio de canto, folhas, cupinzeiros e bromélias, em uma área de floresta madura. A espécie utilizou como sítio de oviposição e cuidado parental fitotelmos em troncos de árvores (n = 03). O canto de anúncio é harmônico, composto por notas multipulsionadas, com frequência dominante entre 2.17 e 2.62 kHz. Os parâmetros acústicos parecem ter sido influenciados pelos fatores abióticos, comprimento rostro-cloacal e massa do macho vocalizante, o que indicou que há reconhecimento individual. O comportamento de defesa registrado foi o de exibir a área ventral, arqueando os membros anteriores e posteriores para frente, com olhos semiabertos, mantendo-se imóveis por alguns segundos (60 a 90 segundos). Nas observações de cuidado parental, o macho apresentou comportamentos de defesa, guarda, averiguação da prole e vocalização. O modelo de nicho ecológico gerado para a espécie de F. pernambucensis ampliou a sua área de distribuição geográfica, com potencial área de ocorrência para ecossistemas da mata atlântica do estado do Rio Grande do Norte. A espécie é registrada, atualmente, para alguns fragmentos de mata atlântica nos Estados de Pernambuco, Paraíba, Alagoas, Sergipe e Bahia. Os dados fornecidos aqui servirão de base para o monitoramento e estratégias de preservação de uma espécie considerada vulnerável para o estado de Pernambuco.Frostius pernambucensis Bokermann 1962 is a bufonidae belonging to the Frostius Cannatella 1986 genus, an endemic Northeastern Atlantic Rainforest genus. The type locality for this species is the Dois Irmãos State Park, where it was recently documented, 50 years after the last registry. In this context, the present study aims to describe F. pernambucensis reproductive and behavioral aspects in its type locality, as well as model potential areas for its geographic distribution. Observations were carried out in an environmental conservation area, the Dois Irmãos State Park (Northeastern Brazil), with both diurnal and nocturnal observations, from October 2014 to April 2017, in nine ten-consecutive-day campaigns. The maximum entropy algorithm (MaxEnt) was used for ecological niche modeling, applying established points of occurrence and environmental variables. A total of 17 F. pernambucensis individuals were recorded. These specimens used leaves, termites and bromeliads in a mature forest area as advertisement site substrates. Oviposition and parental care sites were phyotelma established in tree trunks (n = 03). The advertisement call is harmonic, composed of multi-pulsed notes, with a dominant frequency ranging from 2.17 to 2.62 kHz. Acoustic parameters seem to have been influenced by abiotic factors, snout-cloacal length and the mass of the vocalizing male, indicating individual recognition. Recorded defense behavior comprised a ventral area display, stiffening and arching the front and back limbs forward, with eyes half-open, standing still for a few seconds (60 to 90 seconds). During parental care, the male presented defense, guard, offspring investigation and vocalization behaviors. The ecological niche model generated for the F. pernambucensis extended its geographic distribution area, with a potential occurrence area in Atlantic Rainforest ecosystems in the state of Rio Grande do Norte. The species is currently recorded in some Atlantic Rainforest fragments in the states of Pernambuco, Paraíba, Alagoas, Sergipe and Bahia. The data provided herein will serve as basis for monitoring and conservation strategies of a species considered vulnerable in the state of Pernambuco

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 ε4 allele