Functional traits driving species role in the structure of terrestrial vertebrate scavenger networks

Species assemblages often have a non-random nested organization, which in vertebrate scavenger (carrion-consuming) assemblages is thought to be driven by facilitation in competitive environments. However, not all scavenger species play the same role in maintaining assemblage structure, as some species are obligate scavengers (i.e., vultures) and others are facultative, scavenging opportunistically. We used a database with 177 vertebrate scavenger species from 53 assemblages in 22 countries across five continents to identify which functional traits of scavenger species are key to maintaining the scavenging network structure. We used network analyses to relate ten traits hypothesized to affect assemblage structure with the "role" of each species in the scavenging assemblage in which it appeared. We characterized the role of a species in terms of both the proportion of monitored carcasses on which that species scavenged, or scavenging breadth (i.e., the species "normalized degree"), and the role of that species in the nested structure of the assemblage (i.e., the species "paired nested degree"), therefore identifying possible facilitative interactions among species. We found that species with high olfactory acuity, social foragers, and obligate scavengers had the widest scavenging breadth. We also found that social foragers had a large paired nested degree in scavenger assemblages, probably because their presence is easier to detect by other species to signal carcass occurrence. Our study highlights differences in the functional roles of scavenger species and can be used to identify key species for targeted conservation to maintain the ecological function of scavenger assemblages.

Scavenging in the Anthropocene: Human impact drives vertebrate scavenger species richness at a global scale

Understanding the distribution of biodiversity across the Earth is one of the most challenging questions in biology. Much research has been directed at explaining the species latitudinal pattern showing that communities are richer in tropical areas; however, despite decades of research, a general consensus has not yet emerged. In addition, global biodiversity patterns are being rapidly altered by human activities. Here, we aim to describe large-scale patterns of species richness and diversity in terrestrial vertebrate scavenger (carrion-consuming) assemblages, which provide key ecosystem functions and services. We used a worldwide dataset comprising 43 sites, where vertebrate scavenger assemblages were identified using 2,485 carcasses monitored between 1991 and 2018. First, we evaluated how scavenger richness (number of species) and diversity (Shannon diversity index) varied among seasons (cold vs. warm, wet vs. dry). Then, we studied the potential effects of human impact and a set of macroecological variables related to climatic conditions on the scavenger assemblages. Vertebrate scavenger richness ranged from species-poor to species rich assemblages (4-30 species). Both scavenger richness and diversity also showed some seasonal variation. However, in general, climatic variables did not drive latitudinal patterns, as scavenger richness and diversity were not affected by temperature or rainfall. Rainfall seasonality slightly increased the number of species in the community, but its effect was weak. Instead, the human impact index included in our study was the main predictor of scavenger richness. Scavenger assemblages in highly human-impacted areas sustained the smallest number of scavenger species, suggesting human activity may be overriding other macroecological processes in shaping scavenger communities. Our results highlight the effect of human impact at a global scale. As species-rich assemblages tend to be more functional, we warn about possible reductions in ecosystem functions and the services provided by scavengers in human-dominated landscapes in the Anthropocene.

Gastric epithelioid haemangioendothelioma

Epithelioid haemangioendothelioma (EHE) is a rare tumour of vascular origin, characterised by celular proliferation, endotelial, epitelioid or hystiocitoid. It may develop in any organ, but it is more common in lung and liver. Surgery is the recommended treatment; however, in case of a potentially benign situation, an expectant attitude should be adopted. The case reports a 71-year-old female who underwent a laparotomy for a colonic adenocarcinoma. During surgery, a polypoid lesion in the dependency of the gastric wall was found incidentally, which was removed. Histopathology and immunohistochemical analysis confirmed the diagnosis of EHE. Gastric vascular neoplasms represent about 0.9-3.3% of all gastric tumours. Usually have a good prognosis, but due to the borderline biological behaviour of these tumours, it is important to have a detailed clinical evaluation at follow-up of these patients.

Chemical modulation on heterogeneous growth in Prochilodus lineatus (Valenciennes, 1847) (Pisces; Characiformes)

In the present study, the effect of chemical factors released by conspecifics on growth variability (heterogeneous growth - HetG) in a gregarious fish species (Prochilodus lineatus) was tested. HetG was assessed by the weight variation coefficient in two consecutive 21-day periods. The fish were grouped in tanks (4 fish in each) that received running water with constant draining. The tanks contained either conspecifics (C) or non-conspecifics (N). Four conditions were established in accordance with the tank water supply: a) water with previous contact with conspecifics throughout the experiment (CC); b) water without previous contact with conspecifics throughout the experiment (NN); c) water with previous contact with conspecifics in just the first period, 0 to 21 days (CN); and d) just in the period from 21 to 42 days (NC). At the end of the experiments, the occurrence of chemical modulation on the growth variability in P. lineatus was verified: the fish that received water with previous contact with a conspecific (C) presented exacerbation of HetG. This corroborates the notion that the predominant mechanism in the determination of intraspecific growth variation in the gregarious species is associated to chemical factors released by conspecifics.

Heterogeneous growth fingerlings of the Nile tilapia Oreochromis niloticus: effects of density and initial size variability

In this study, the effect of initial heterogeneity of weight and density on heterogeneous growth (HetG) evaluated by the coefficient of the variation of weight in the young Nile tilapia Oreochromis niloticus of the territorial species was tested. Fish were maintained in a glass aquarium (8 and 2 L of water) with two levels of initial heterogeneity of weight: low and high, under two density conditions: low and high, thus constituting four conditions (six replications for each). Initially, the weights of the animals were taken after 8, 16, 22 and 30 days (end of experiment). The results, evaluated by the non-parametric test of Kruskal- Wallis, demonstrated that in the groups where the animals were stored under high initial HetG, there was a reduction of the same and that in the groups where the animals were stored under high density, there was exacerbation or maintained high values of HetG. High density in association with high initial heterogeneity caused more exacerbation of HetG in such a way that the density appeared to be a determining factor for exacerbation or the maintenance of high values of HetG, whereas the initial heterogeneity of the weight could be a secondary factor.

[Brazilian pemphigus foliaceus (fogo selvagem)]

Most of the clinical, histological and immunohistological features of fogo selvagem resemble those of idiopathic pemphigus foliaceus (PF). Both diseases are clinically characterized by small flaccid bullae evolving into to scaly and crusted lesions, sometimes with pustules, mainly in seborrheic areas of the skin. Mucosal surfaces are mostly spared. The main histologic feature of endemic pemphigus foliaceus is a subcorneal acantholytic blister. Standard immunofluorescence studies demonstrate intercellular IgG deposits throughout the entire epidermis. These IgG antibodies are mainly of the IgG4-subclass. Almost all patients have circulating IgG-autoantibodies in their serum directed against stratified epithelial desmosomes. The fogo selvagem autoantibodies and the PF antibodies are directed against the 160 kD desmosomal glycoprotein desmoglein 1 which together with plakoglobin (85 kD) forms a complex of adhesion proteins with desmosomes of stratified epithelia. Fogo selvagem occurs in endemic foci in some areas of Brazil and possibly in neighbouring South American countries, very often in children, adolescents and young adults. The etiology of fogo selvagem is still unknown. The frequent association with insect bites has lead to the concept of fogo selvagem being a transmissible disease with acquired immunity in adulthood. However, the infectious agent and possible vectors have not yet been identified.

Clinical, autoimmune and demographic profile in systemic lupus erythematosus (SLE) patients from southern Brazil

With the purpose of determining the association of clinical, autoimmune and demographic features, a group of 90 SLE patients from Southern Brazil were investigated. At diagnosis, 24% of them were under 20 years, 63% were between 20 and 40 years and 13% were older than 40 years. According to the ethnic background, there were 66% Brazilian-white patients, 21% Caucasians and 13% Mullatos/Blacks. Antinuclear antibodies (ANA) were present in 98%, anti-ds-DNA in 56% and anti-Sm in 31% of the patients. Anti-ds-DNA were more prevalent in the Caucasians (79%), while anti-Sm were increased in the Mullatos/Blacks (58%, p < 0.02) as compared to the white patients (Brazilian-whites = 22% and Caucasians = 42%). Neurologic involvement had lower prevalence in the group of Mullato/Black patients (8%) than in the Brazilian-whites (32%) and Caucasians (31%). Serositis was present in 51% of the Brazilian-whites, in 21% of the Caucasians and in 41% of the Mullatos/Blacks. On the other hand, the Mullato/ Black group had an increased prevalence of vasculitis (50%) and none of them presented with Raynaud's phenomenon. Younger patients at diagnosis presented higher frequency of renal involvement (p < 0.05), anti-ds-DNA positivity (p < 0.02) and more severe disease (p < 0.07), and in those patients diagnosed after age 40, 33% presented with Raynaud's phenomenon (p < 0.05). Regarding the anti-ds-DNA positivity, 78% of the patients had renal involvement (p < 0.01 RR 2.2) and 66% severe disease (p < 0.05). These results might be important in assessing clinical subsets and may aid individualized management of Brazilian SLE patients. Also, they may corroborate the need for special attention to racial composition in clinical and immunogenetic studies.

[Chronic phase of Chagas disease. Clinical aspects and course of the disease]

PURPOSE

To evaluate the clinical and evolutive aspects of chronic chagasic patients.

METHODS

Three hundred chronic chagasic patients, 180 females, with age ranging from 19 to 81 years (55.6 +/- 13.1) were retrospectively studied. Patients were divided according to the following clinical types: indeterminated, cardiac (with the subtypes: arrhythmogenic, dilated and mixed), digestive isolated and digestive plus cardiac involvement. The following variables were analysed: prevalence of each clinical forms, symptoms, electrocardiographic pattern and clinical outcome.

RESULTS

At the start of the study, 73 (24.3%) patients were in indetermined type, 106 (35.3%) in cardiac arrhythmogenic, 95 (31.6%) in mixed, 7 (2.3%) in dilated, 16 (5.3%) in digestive plus cardiac type and 3 (1%) in the pure digestive type. The most prevalent symptoms were dyspnea on efforts (57%), palpitations (41.33%) and chest pain (33%). The most frequent electrocardiographic pattern was right bundle branch block plus antero-superior fascicular block, in 30% of the patients. The average follow-up time was 7.8 +/- 6.1 years and the outcome was considered good in 20 patients (6.6%), stable in 214 (71.3%) and bad in 66 (23%). At the end of the follow-up, 9 patients have evaluated from the indeterminated to the cardiac and digestive types, and 19 (17.92%), from the arrhythmogenic to mixed cardiac subtype. The follow-up was lost in 79 patients (26.3%), most of them, probably dead.

CONCLUSION

With a mean time of 7.8 years, 12.3% of the patients in the indeterminated type evolved to the cardiac and/or digestive type; right brundle branch block with antero-superior fascicular block was the most prevalent electrocardiographic pattern; the outcome was stable or good in the majority of these patients.

[Pathology of experimental infection in domestic rodents using various strains of Yersinia pestis]

Os autores estudaram 253 ratos domésticos (Rattus norvegicus e Rattus r. frugivorus), infectados experimentalmente (via subcutânea) com duas cepas de Yersinia pestis (cepas "PEXU-19" e "RANGEL"), isoladas de roedores silvestres capturados no nordeste brasileiro (Exú - Pernambuco) e na Venezuela, respectivamente, as quais foram mantidas em meio de cultura e subinoculadas periodicamente. A sobrevida dos animais infectados variou de dois a sete dias, sendo os sobreviventes sacrificados no 20º dia após a data da inoculação. Para cada uma das duas espécies de rato, foram empregadas cargas infectantes de intensidades diferentes (750 - 4.250; 7.500 - 41.250 e 75.000 - 750.000 bacilos), correspondentes a cada uma das duas cepas de Y. pestis utilizadas. A patologia foi estudada em relação ao fígado, baço, pulmão e linfonodo inguinal, órgãos onde as lesões se mostraram mais exuberantes. As lesões hepáticas foram essencialmente representadas por congestão, necrose coagulativa multifocal e infiltração inflamatória aguda portal e sinusoidal, com formação de microabscessos. No baço ocorreu atrofia acentuada dos folículos linfóides de Malpighi, congestão, hemorragia e esplemite aguda abscedada. No pulmão, foi achado freqüente a pneumonite aguda, ás vezes acompanhada de abscessos. De um modo geral, a cepa PEXU-19 revelou maior poder patogênico que a cepa RANGEL, embora, em relação à espécie de roedor infectado não tenha sido possível surpreender diferenças quanto á sua susceptibilidade frente ás duas cepas Y. pestis utilizadas no presente trabalho.

Sur la Structure du Poumon du Dauphin (Delphinus delphis)

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