Find research datasets worth reusing

opencc-by-4.0Jun 2020View details →

Sealing. Oval sealing in terracotta with a trident, vase and elephant goad in an oval cartouche.

Sealing. Oval sealing in terracotta with a trident, vase and elephant goad in an oval cartouche. British Museum 2005,0814.23.

opencc-zeroNov 2023View details →

Age estimation of captive Asian elephants (Elephas maximus) based on DNA methylation: An exploratory analysis using methylation-sensitive high-resolution melting (MS-HRM)

Age is an important parameter for bettering the understanding of biodemographic trends-development, survival, reproduction and environmental effects-critical for conservation. However, current age estimation methods are challenging to apply to many species, and no standardised technique has been adopted yet. This study examined the potential use of methylation-sensitive high-resolution melting (MS-HRM), a labour, time, and cost-effective method to estimate chronological age from DNA methylation in Asian elephants (Elephas maximus). The objective of this study was to investigate the accuracy and validation of MS-HRM use for age determination in long-lived species, such as Asian elephants. The average lifespan of Asian elephants is between 50-70 years but some have been known to survive for more than 80 years. DNA was extracted from 53 blood samples of captive Asian elephants across 11 zoos in Japan, with known ages ranging from a few months to 65 years. Methylation rates of two candidate age-related epigenetic genes, RALYL and TET2, were significantly correlated with chronological age. Finally, we established a linear, unisex age estimation model with a mean absolute error (MAE) of 7.36 years. This exploratory study suggests an avenue to further explore MS-HRM as an alternative method to estimate the chronological age of Asian elephants.

opencc-zeroDec 2023View details →

Diving behaviors of juvenile northern and southern elephant seals

Understanding the ontogeny of diving behavior in marine megafauna is crucial due to its influence on foraging success, energy budgets, and mortality. We compared the ontogeny of diving behavior in two closely related species – northern elephant seals (Mirounga angustirostris, n = 4) and southern elephant seals (Mirounga leonina, n = 9) – to shed light on the ecological and evolutionary processes underlying migration. Although both species have similar sizes and behaviors as adults, we discovered that juvenile northern elephant seals have superior diving development, reaching 260 meters diving depth in just 30 days, while southern elephant seals require 160 days. Similarly, northern elephant seals achieve dive durations of ~11 minutes on their first day of migration, while southern elephant seals take 125 days. The faster physiological maturation of northern elephant seals could be related to longer offspring dependency and post-weaning fast durations, allowing them to develop their endogenous oxygen stores. Comparison across both species suggests that weaned seal pups face a trade-off between leaving early with higher energy stores but poorer physiological abilities or leaving later with improved physiology but reduced fat stores. This trade-off might be influenced by their evolutionary history, which shapes their migration behaviors in changing environments over time.

opencc-zeroApr 2024View details →

Data from: Hypoxia blunts angiogenic signaling and upregulates the antioxidant system in elephant seal endothelial cells

Background Elephant seals exhibit extreme hypoxemic tolerance derived from repetitive hypoxia/reoxygenation episodes they experience during diving bouts. Real-time assessment of the molecular changes underlying protection against hypoxic injury in seals remains restricted by their at-sea inaccessibility. Hence, we developed a proliferative arterial endothelial cell culture model from elephant seals and used RNA-seq, functional assays, and confocal microscopy to assess the molecular response to prolonged hypoxia. Results Seal and human endothelial cells exposed to 1% O2 for up to 6 h respond differently to acute and prolonged hypoxia. Seal cells decouple stabilization of the hypoxia-sensitive transcriptional regulator HIF-1α from angiogenic signaling. Rapid upregulation of genes involved in glutathione (GSH) metabolism supports the maintenance of GSH pools, and intracellular succinate increases in seal but not human cells. High maximal and spare respiratory capacity in seal cells after hypoxia exposure occurs in concert with increasing mitochondrial branch length and independent from major changes in extracellular acidification rate, suggesting that seal cells recover oxidative metabolism without significant glycolytic dependency after hypoxia exposure. Conclusions We found that the glutathione antioxidant system is upregulated in seal cells during hypoxia, while this system remains static in comparable human cells. Furthermore, we found that in contrast to human cells, hypoxia exposure rapidly activates HIF-1 in seal cells, but this response is decoupled from the canonical HIF-angiogenesis pathway. These results highlight the unique mechanisms that confer extraordinary tolerance to limited oxygen availability in a champion diving mammal.

opencc-zeroApr 2022View details →

Sex-specific body mass aging trajectories in adult Asian elephants

In species with marked sexual dimorphism, the classic prediction is that the sex which undergoes stronger intrasexual competition ages earlier or quicker. However, more recently, alternative hypotheses have been put forward, showing that this association can be disrupted. Here, we utilise a unique, longitudinal dataset of a semi-captive population of Asian elephants (Elephas maximus), a species with marked male-biased intrasexual competition, with males being larger and having shorter lifespans, and investigate whether males show earlier and/or faster body mass ageing than females. We found evidence of sex-specific body mass ageing trajectories: adult males gained weight up to the age of 48 years old, followed by a decrease in body mass until natural death. In contrast, adult females gained body mass with age until a body mass decline in the last year of life. Our study shows sex-specific ageing patterns, with an earlier onset of body mass declines in males than females, which is consistent with the predictions of the classical theory of ageing.

opencc-by-4.0May 2024View details →

Challenges and Realities in Asian Elephant Research: A Global Bibliometric Analysis Highlighting Conservation Crises and Collaborative Opportunities

The Asian elephant (Elephas maximus), also known as Asiatic elephant is facing a significant decline in its wild populations due to habitat loss, fragmentation and degradation, leading to increased conflicts between humans and elephants. Preserving this iconic species is crucial, prompting researchers to explore various aspects of its biology, behavior, ecology, and conservation efforts. In light of the profound importance of this subject, this study utilizes a descriptive systematic literature review (SLR) to examine global research trends on Asian elephants. Analyzing a dataset of 1,780 articles spanning from 1914 to 2022, the study reveals a notable increase in publications, particularly since 2000, with 142 articles published in 2022 alone. This research provides a comprehensive overview of advancements in Asian elephant studies, promoting international collaboration and knowledge exchange among researchers. While research from leading scientific countries can aid in conservation efforts, there is a call for more inclusive, participatory and fair approaches. The study demonstrates a commitment to Equity, Inclusion, and Diversity (EID) by adopting a multifaceted approach that considers the needs, perspectives and contributions of diverse stakeholders. By addressing disparities and advocating for social justice within elephant conservation, the study emphasizes the urgent need for collective action in conservation, welfare improvement, conflict resolution, ecosystem balance, and overall enhancement of understanding about Asian elephants. Serving as a valuable resource for policymakers, conservation organizations, and researchers, the study not only synthesizes existing literature but also identifies research gaps, highlights areas requiring immediate attention, and offers collaborative opportunities for global scientists to contribute to the well-being and preservation of this majestic species.

opencc-by-4.0Dec 2021View details →

FIGURE 2. 3D in The inner morphology of the petrosal bone of the endemic elephant of Tilos Island, Greece

FIGURE 2. 3D reconstruction of the petrosals, samples (A-C) T2406 along with transparent views locating the orientation of the labyrinth in the bone, (D-F) T2506 and (G-I) T137. A, D, G ventrolateral view; B, E, H dorsolateral view; C, F, I dorsomedial view. See text for abbreviations.

Fig. 3 in A standardised faecal collection protocol for intestinal helminth egg counts in Asian elephants, Elephas maximus

Fig. 3. Pairwise comparisons of faecal egg counts (in EPG) for samples taken from different faecal boluses produced in one defecation event of (a) first and middle boluses, (b) first and last boluses, (c) middle and last boluses, all with 95% confidence intervals. For each of (a‾c) 40 samples collected from 20 elephants. Data collected for one elephant not shown, with one extreme data point removed in each of a‾c, to allow for better presentation of plots.

Fig. 2 in A standardised faecal collection protocol for intestinal helminth egg counts in Asian elephants, Elephas maximus

Fig. 2. Regression of the faecal egg counts (in EPG) for samples taken of the centre and edge of a single faecal bolus with 95% confidence intervals, 474 samples collected from 119 elephants.

Fig. 1 in A standardised faecal collection protocol for intestinal helminth egg counts in Asian elephants, Elephas maximus

Fig. 1. Averaged helminth egg counts for every elephant host sampled for each experiment; investigating egg distribution within (a) an individual bolus (centre and edge samples), 474 samples from 119 elephants and (b) multiple boluses (centre and edge samples from different boluses), 120 samples from 20 elephants, (c) when determining optimal sampling time, 94 samples from 47 elephants, and (d) if storage methods had any impact on egg recovery during faecal egg counts (FEC), 132 samples from 33 elephants. Helminth eggs were always aggregated within host elephants, with few hosts having substantial parasite burdens (in excess of 200 EPG) and the majority having none or insubstantial levels of infection.

Fig. 4 in Occurrence and seasonality of internal parasite infection in elephants, Loxodonta africana, in the Okavango Delta, Botswana

Fig. 4. The prevalence of fluke (= trematode) eggs in wild elephants of different ages, using sedimentation of FP-samples (formalin-preserved faecal samples).

Fig. 2 in Occurrence and seasonality of internal parasite infection in elephants, Loxodonta africana, in the Okavango Delta, Botswana

Fig. 2. Nematode egg densities found in UP-samples (unpreserved, immediately analysed faecal samples) from wild elephants, categorised into two group types. Group 1 consists of groups with all female elephants and/or male elephants under the age of 15 years, and Group 2 consists of male elephants aged 15 years or more. Error bars show the standard deviation. EPG = eggs per gram of faeces.

Fig. 1 in Occurrence and seasonality of internal parasite infection in elephants, Loxodonta africana, in the Okavango Delta, Botswana

Fig. 1. The prevalence of coccidial oocysts in FP-samples (formalin-preserved faecal samples) from wild elephants, in each month (2008 to 2012 combined).

Fig. 4 in A standardised faecal collection protocol for intestinal helminth egg counts in Asian elephants, Elephas maximus

Fig. 4. Faecal egg counts (in EPG) were significantly decreased in samples which had been stored in 10% formalin or 10% formol saline in comparison to subsamples collected at the same time but analysed as fresh, without storage in fixative solution. This figure is based on 132 samples collected from 33 elephants, with data lying between the first and third quartiles as represented by the top and bottom horizontal lines of the boxplot. The data range is shown by the vertical black lines, with the median of each dataset represented by the middle horizontal line within each boxplot and with any outliers shown as points.

Fig. 3 in Occurrence and seasonality of internal parasite infection in elephants, Loxodonta africana, in the Okavango Delta, Botswana

Fig. 3. Photomicrographs of typical nematode (A) and trematode (= fluke, B) eggs found in elephant faecal samples. For dimensions see text.

opencc-by-4.0Apr 2020View details →

Fig. 6 in Morphological and molecular identification of cyathostomine gastrointestinal nematodes of Murshidia and Quilonia species from Asian elephants in Myanmar

Fig. 6. Molecular phylogenetic analysis of COI gene sequences of cyathostomine species using the maximum likelihood method in MEGA7. The percentage of trees in which associated taxa clustered together is shown next to the branches. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. GenBank accession numbers are indicated alongside taxa name.

opencc-by-4.0Apr 2020View details →

Fig. 5 in Morphological and molecular identification of cyathostomine gastrointestinal nematodes of Murshidia and Quilonia species from Asian elephants in Myanmar

Fig. 5. Photomicrographs of Quilonia travancra. A, anterior end of a male, showing head papillae (arrows) and mouth collars (*); B, head of a male, showing crown leaflets (arrow); C, bursa of a male, lateral view, showing two branches (arrows) and three sub-branches of the posterior branch at approximately the same length (*); D, posterior branch of dorsal ray of bursa of a male, showing an appearance of trifurcation although the median and internal sub-branches are fused (*).