Biology subjects

Silveira, L.

Publications and source records attributed to Silveira, L..

8 recordsLinked to original sources

bioRxiv2026

The knowledge landscape of jaguar science: rapid growth, thematic structure, and regional inequalities

Understanding how scientific effort is distributed is essential for evaluating the evidence available to guide species conservation. We assessed the temporal, thematic, methodological, and spatial organization of jaguar (Panthera onca) research across the species range. Using 1,028 bibliographic records, we applied a metadata-based scope filter, defining a primary analytical corpus of 857 articles and an inclusive sensitivity corpus of 989. We analyzed publication growth from 1946-2024, author-keyword networks, high-specificity research-domain and methodological indicators, article-based spatial concentration across nine regions, and anthropogenic context using the Human Impact Index. Publication output increased strongly and nonlinearly, with the negative-binomial generalized additive model explaining 96% of deviance. Population and abundance, human-wildlife conflict and coexistence, and movement and connectivity were the most frequent research domains, whereas camera trapping was the most frequent methodological approach. Spatial analyses included 237 georeferenced terrestrial articles. Research was strongly concentrated in the Pantanal, Mesoamerica, and Atlantic Forest, but was underrepresented relative to range area in the Andes and Choco-Darien, Amazon, and Guiana Shield. These patterns were stable to the broader scope definition. Research concentration showed no strong association with region-wide anthropogenic pressure, although studies within several extensive regions tended to occur in more human-influenced portions than the regional average. Jaguar research therefore shows substantial growth and partial alignment with applied conservation challenges but remains geographically uneven. Expanding representative research in underrepresented regions, while maintaining work in threatened landscapes, would strengthen the evidence base for range-wide conservation planning and improve coordination among countries, institutions, and regional research traditions.

ecology↗

bioRxiv2026

Severely lipoatrophic mice are hypermetabolic and hyperthermic under thermoneutral conditions in part due to an enhanced liver de novo lipogenesis

White, beige and brown adipocytes store energy as lipids, secrete hormones and produce heat, playing an important role in the regulation of energy balance through not completely defined mechanisms. We investigate herein the impact of the almost complete absence of mature adipocytes (severe lipoatrophy) in the determination of energy balance (energy intake and expenditure) and homeothermy in mice. For this, mice with severe lipoatrophy induced by adipocyte deletion of peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) (PPAR{gamma} flox adiponectin-Cre) and littermate controls (PPAR{gamma} flox) were evaluated for energy balance, thermoneutral zone, core body temperature, locomotor activity, and gene expression profiles at different ambient temperatures. Severely lipoatrophic mice are heavier, hypermetabolic and hyperphagic and feature a widened thermoneutral zone, lower ambulatory activity, and metabolic inflexibility at both 23 and 17{degrees}C, along with unstable thermal behavior characterized by hyperthermia at 30{degrees}C, normothermia at 23{degrees}C, and bouts of hypothermia at 17{degrees}C. Noteworthy, lipoatrophic mice hypermetabolism at 30{degrees}C is not due to thyroid hormones, impaired insulation or increased body and lean masses and is not altered by pharmacological blockade of either {beta}-adrenergic receptor signaling with propranolol or skeletal muscle sarcoplasmic/endoplasmic reticulum Ca2+-ATPases (SERCA) and sarcolipin (SLN)-mediated calcium cycling with dantrolene, but is partially attenuated by pharmacological inhibition of acetyl-CoA carboxylase (ACC) and de novo lipogenesis with ND-630. In conclusion, severe lipoatrophy causes hypermetabolism and hyperthermia at 30{degrees}C partly through the activation of liver de novo fatty acid synthesis.

physiology↗

bioRxiv2026

Hepatocyte-, but not myeloid cell-Rictor/mTORC2 deficiency moderately attenuates steatotic liver disease induced by intake of a choline-deficient, amino acid-defined high-fat diet

Previous studies have demonstrated that mechanistic target of rapamycin complex 2 (mTORC2) deficiency provides complete protection against steatotic liver disease driven by constitutive activation of the phosphoinositide 3-kinase (PI3K)-Akt signaling pathway and de novo lipogenesis, and partial protection against disease induced by a high-fat diet. We investigated herein whether mTORC2 deficiency in hepatocytes and myeloid cells, including Kupffer cells and recruited macrophages, influences the development of liver disease induced by intake of a choline-deficient, amino acid-defined high-fat diet (CDAHFD), a model in which liver disease is induced by impaired hepatic secretion of very low-density lipoprotein (VLDL) triacylglycerol. For this, mice with either hepatocyte- or myeloid cells-specific deletion of mTORC2 essential component rapamycin-insensitive companion of mTOR (Rictor) and their respective littermate controls were fed with either chow or CDAHFD for 10 weeks and evaluated for hepatic steatosis, inflammation and fibrosis. Our main findings indicate that hepatocyte Rictor/mTORC2 deficiency slightly attenuated the CDAHFD-induced increases in liver mass, macrovesicular steatosis and triacylglycerol accumulation, without affecting though liver cholesterol, serum markers of liver injury (AST and ALT), as well as the upregulation in proinflammatory cytokine IL-1{beta} and expression of fibrosis-related genes. Myeloid cells-Rictor deletion had no detectable impact on liver steatosis, inflammatory, or fibrosis induced by CDAHFD. In conclusion, mTORC2 deficiency show modest beneficial effects in counteracting liver disease induced by CDAHFD intake.

biochemistry↗

bioRxiv2026

Population analysis and host-disease associations of Shiga toxin-producing Escherichia coli from various sources across eleven European countries using whole genome sequencing

Shiga toxin-producing Escherichia coli (STEC) are important foodborne pathogens, able to cause severe disease in humans. In the DiSCoVeR project (https://onehealthejp.eu/jrp-discover/) a STEC inventory from human and non-human sources from 11 European countries was set up and [≥] 3500 strains were sequenced to perform comparative genomics analysis. We used this dataset to assess STEC population structure and to investigate potential associations between genomic features, host reservoirs and symptoms. Most STEC isolates analysed by Whole Genome Sequencing (WGS) in this study were collected between years 2010-2020. An ad hoc pipeline was deployed for a harmonised characterization of the STEC in the database, allowing the determination of serotyping, stx gene subtyping, 7-loci MLST, virulotyping and cgMLST. The results were analysed with Principal Component Analysis (PCoA) in relation with isolation source to assess clustering of STEC subpopulations. When human STEC data were analysed, the PCoA revealed three distinct human STEC subpopulations (STEC_1, STEC_2 and STEC_3), which were further analysed for associations between genomic features, symptoms and variance. The non-human STEC showed a more dispersed distribution, except for one subpopulation with genes linked to specific host species, and some virulence profiles overlapping with the STEC_1 population. In conclusion, our analysis identified distinct STEC subpopulations from human cases, each characterized by specific genetic features and associated with varying proportions of severe disease outcomes. These findings provide novel insights supporting the risk assessment of STEC. Impact statement[This lay summary of your article should be no more than 200 words, and should a) provide a perspective of how this article adds to the literature in the field; b) identify breadth of interest/utility; and c) state the significance of output (incremental or step), in terms of relevance.] This study is based on the establishment of a One Health STEC genomes database, including sequences from isolates of different sources. Most of the isolates had been isolated in the ten-years time span 2010-2020, in 11 different countries, for surveillance and monitoring activities or specific surveys and research purposes. The final dataset included the whole genome sequencing of 3,418 STEC isolates, mainly from human cases of infections. The metadata included the host symptoms, where available, for human STEC strains and the animal source the strains had been isolated from. We set up a pipeline for the harmonized analysis of STEC WGS, called Discover, made available though ARIES webserver or GitHub. The analysis allowed a deep characterization of STEC strains circulating in Europe. We used this resource to assess STEC population structure and to investigate potential associations between genomic features, host reservoirs, and various symptoms associated with STEC infection by PCoA. This analysis highlighted the presence of subpopulation of human STEC associated with specific features. We provide new information useful for risk characterization, as well as a large dataset genome database and associated metadata compiled from STEC strains, representing a valuable resource for the scientific community, enabling further investigations into STEC diversity, evolution, source attribution and public health relevance. Data summaryThe authors confirm all supporting data, including sequence data accession numbers, code and protocols have been provided within the article or through supplementary data files. One supplementary method and five supplementary tables are available with the online version of this article

genomics↗

bioRxiv2025

Kilometre-scale jaguar swimming reveals permeable hydropower barriers: implications for conservation in the Cerrado hotspot

Hydropower reservoirs are expanding rapidly across tropical biomes, yet their function as barriers or filters to carnivore movement remains poorly understood. Here, we report the first confirmed long-distance swim by a jaguar (Panthera onca) across an artificial lake and discuss its implications for landscape connectivity. Camera traps around Serra da Mesa Reservoir (Central Brazil; 1,784 km2; 54.4 km3) photographed an adult male on the mainland and later on a forested island. Flank-pattern matching confirmed a 100% identity between records. Geodesic analysis identified two possible routes: a direct 2.48 km crossing or an alternative path involving a stepping-stone islet (1.06 km + 1.27 km). In the absence of evidence for use of the islet, we conservatively adopt the largest continuous water segment--1.27 km--as the minimum distance swum. This represents nearly six times the longest previously verified jaguar swim ({approx} 200 m). The event supports a graduated-resistance framework in which water bodies exceeding 1 km impose high, but not insurmountable, costs to movement. We propose an ordinal aquatic-cost scale (1 = < 300 m; 3 = 300-1,000 m with stepping-stones; 6 = > 1,000 m open water) for use in circuit-based connectivity models. By contrasting this record with predator collapse on > 1 km islands in Lake Guri and with genetic segregation across the Amazon River, we demonstrate that aquatic permeability is strongly context-dependent. Incorporating rare but consequential swims into environmental impact assessments will improve corridor design and better inform hydropower licensing throughout the jaguars range. Highligts- Extends the longest recorded jaguar swim by almost six times. - Demonstrates that reservoirs act as costly filters rather than absolute barriers for large carnivores. - Introduces an ordinal aquatic-cost scale to enhance connectivity models. - Informs hydropower impact assessments and the design of amphibious corridors for mammal conservation.

ecology↗

bioRxiv2025

JAGUAR CONSERVATION UNITS AS EFFECTIVE TOOL IN A PAYMENT FOR ECOSYSTEM SERVICES SCHEME FOR APEX PREDATOR

This paper proposes a redefinition of Jaguar Conservation Units, emphasizing the role of private rural properties in jaguar populations in Brazil while mitigating conflicts with the species and allowing a more effective implementation of payment for the species environmental services. Jaguars prey domestic livestock, leading to retaliatory killings by ranchers. In this context, the study aims to analyze the environmental and economic parameters associated with the ecosystem services provided by jaguars. The ultimate goal is to develop a regional Payment for Environmental Services (PES) scheme to support jaguar conservation by promoting forest code compliance, maintaining habitat connectivity, and compensating cattle predation, using data from Mato Grosso do Sul (MS), Brazil. Our findings demonstrate the advantages of implementing such program and reveal that the cost of maintaining jaguar populations through a PES, with funds from several independent sources, would be feasible and important for one of the largest jaguar populations in Brazil. HIGHLIGHTSO_LIAnalysis of environmental and economic parameters linked to jaguar ecosystem services. C_LIO_LIDevelopment of a regional Payment for Environmental Services (PES) scheme in Mato Grosso do Sul. C_LIO_LIEvidence of the feasibility and importance of PES to maintain one of the largest jaguar populations in Brazil. C_LI

ecology↗

bioRxiv2025

Spatial Ecology of Jaguars in a Coastal Amazon Island Ecosystem

Understanding the spatial ecology of large carnivores is essential for effective conservation, particularly in insular or fragmented systems where movement is constrained. Jaguars are particularly important to study, as they are opportunistic predators whose diet and behaviour shifts flexibly with local prey availability. We investigated the movement patterns, home range dynamics, and social interactions of jaguars (Panthera onca) on Maraca-Jipioca Island, a pair of small, seasonally flooded islands, in a low-disturbance reserve in the Brazilian Amazon. Using GPS collars, we tracked seven individuals and found that males had significantly larger home ranges (mean: 77.8 km{superscript 2}) than females (mean: 19.5 km{superscript 2}). Despite the islands limited area, home-range overlap was low, and direct encounters were rare. This mirrored the territorial behaviour seen in more expansive mainland populations, but contradicted patterns seen in other populations that specialised on aquatic prey. Jaguars on Maraca-Jipioca moved an average of 7.3 km/day, with no significant differences across sex, age, nor body size. However, movement speed and probability of activity varied significantly across habitats: individuals moved faster in grasslands, wetlands, and water, and more slowly in forests and mangroves. Animals also spent more time resting while in forests and mangroves as compared to grasslands, water, and wetlands. In contrast to the predominantly nocturnal habits reported in continental populations, jaguar activity on Maraca-Jipioca peaked during daylight hours, especially among females. Jaguars showed a marked preference for coastal areas but did not appear to adjust habitat use in response to tidal variation in sea level. Collectively, these findings suggest that the spatial ecology of Maraca-Jipioca jaguars is comprised of typical and novel behaviours, shaped by both the species evolutionary history, and the islands unique ecological context. These findings highlight the species behavioural flexibility and offer rare insights into how a large carnivore persists in an insular Amazonian landscape.

ecology↗

bioRxiv2020

Clues on an intraspecific communication system in early plant establishment: The seed-seedling transition from the point of view of a crosstalk between information theory and gene expression

How much interactivity is there in a seed-seedling transition system? The answer for this question can reveal a key aspect for early plant establishment. Thus, we hypothesize that information entropy is correlated with early plant development because it is directly related to interactions between seed-seed, seed-seedling, and seedling-seedling. To test this hypothesis, we perform an overlapping of classical physiological measurements (embryo protrusion), gene expression in germination sensu stricto, water dynamics in germinating seeds and information theory. For a biological model, we used Solanum lycocarpum A. St.{square}Hil. seeds. This is a Neotropical species with high intra-specific variability in the seed sample. Our finds demonstrate that the dynamic and transient seed-seedling transition system is influenced by the number of individuals (seed or seedling) in the sample, especially at a same physiological stage. In addition, we also discuss that: (i) information entropy enables the quantification of system disturbance relative to individuals in the same physiological stage (seed-seed or seedling-seedling), which may be determinant for embryo growth during germination. (ii) there is possible intraspecific communication in seed-seedling transition systems formed by germinating seeds with the potential to alter the pattern of embryonic development of the sample. In view of this, we suggest the use of information entropy as a tool for studies of biological systems to clarify the phenomenon of mutual stimulation in the germination process.

plant biology↗