There are few milestones in speleobiology, and Proteus anguinus, commonly named the olm, proteus or “human fish”, is undoubtedly part of its (hi)story. The animal was first mentioned in 1689 by ...Johann Weikhard von Valvasor (Janez Vajkard Valvasor) in his The Glory of the Duchy of Carniola (Slava Vojvodine Kranjske). The scientific name Proteus anguinus was given by Josephus Nicolaus Laurenti in 1768. The animal gained the interest of the scientific community later in the 19th century, culminating in 1859 in Charles Darwin's famous monograph On the Origin of Species as an example of evolutionary reduction of body structures through disuse. The study of this remarkable animal intensified in the 20th century. Its longevity, its general peculiarity and the mystery governing the underground world of the Dinaric karst triggered more systematic research. Much interesting data was obtained from study of proteus in captivity in various laboratories worldwide, including Slovenia, France, England, Belgium, Hungary, Germany and Italy. In the 21st century, the year 2019 represents another important milestone in the research of proteus. The draft genome of Proteus anguinus was first publicly presented on 25 November 2019 in Ljubljana, Slovenia. The event coincided with 330 years since proteus was introduced to the scientific community by Valvasor, 160 years since its popularization by Darwin, and the 100th anniversary of Ljubljana University. This is undoubtedly an achievement with many superlatives, starting from excellent collaboration among different international laboratories and the very short period – one year – used to finish the sequencing of the huge proteus genome, which is 15-times larger in size than the human genome. On this occasion, we spoke with the two most important players in the story, prof. Nina Gunde-Cimerman and prof. Rok Kostanjšek, from the University of Ljubljana, Biotechnical Faculty. Prof. Nina Gunde-Cimerman directs research of extremophiles adapted to extreme conditions, in particular fungi, at the Biotechnical Faculty. Prof. Rok Kostanjšek leads a research team that continues the investigation of proteus begun by his predecessors, prof. Lili Istenič and prof. Boris Bulog.
Proteus anguinus
is a neotenic cave salamander, endemic to the Dinaric Karst and a symbol of world natural heritage. It is classified as “vulnerable” by the International Union for Conservation of ...Nature (IUCN) and is one of the EU priority species in need of strict protection. Due to inaccessibility of their natural underground habitat, scientific studies of the olm have been conducted mainly in captivity, where the amphibians are particularly susceptible to opportunistic microbial infections. In this report, we focused on the diversity of cultivable commensal fungi isolated from the skin of asymptomatic and symptomatic animals obtained from nature (20 specimens) and captivity (22 specimens), as well as from underground water of two karstic caves by direct water filtration and by exposure of keratin-based microbial baits and subsequent isolation from them. In total 244 fungal isolates were recovered from the animals and additional 153 isolates were obtained from water samples. Together, these isolates represented 87 genera and 166 species. Symptomatic animals were colonized by a variety of fungal species, most of them represented by a single isolate, including genera known for their involvement in chromomycosis, phaeohyphomycosis and zygomycosis in amphibians:
Acremonium
,
Aspergillus
,
Cladosporium
,
Exophiala
,
Fusarium
,
Mucor
,
Ochroconis
,
Phialophora
and
Penicillium
. One symptomatic specimen sampled from nature was infected by the oomycete
Saprolegnia parasitica
, the known causative agent of saprolegniosis. This is the first comprehensive report on cultivable skin mycobiome of this unique amphibian in nature and in captivity, with an emphasis on potentially pathogenic fungi and oomycetes.
1. Various groundwater habitats have exceptionally high levels of endemism caused by strong hydrographical isolation and low dispersal abilities of their inhabitants. More than 10% of ...macro-stygobiotic species nevertheless occupy relatively large ranges, measuring from some hundred to over 2000 km in length. These species represent a challenge because their distributions disregard hydrographical boundaries, and their means to disperse and maintain long-term gene flow are unknown. 2. Based on mitochondrial and nuclear gene sequences, we examined the phylogeographic structure of six formally recognised stygobiotic species (Niphargus virei, N. rhenorhodanensis, Troglocaris anophthalmus, T. hercegovinensis, Spelaeocaris pretneri, Proteus anguinus) and searched for cryptic lineage diversity in a genus-wide phylogeny of Niphargus. Using tree-based criteria as well as comparative divergence measures, we identified cryptic lineages, which may tentatively be equated with cryptic species. 3. Fourteen analysed nominal stygobiotic species with large ranges emerged as highly diversified, splitting into 51 tentative cryptic lineages. The degree of divergence was within the range or larger than the divergence of other related pairs of sister species. A substantial part (94%) of the cryptic lineages had ranges <200 km in length. One half of them were recorded at single sites only. The largest range recorded was that of a cryptic N. virei lineage (700 km), while none of the very large traditional ranges (e.g. Niphargus aquilex- 2300 km, N. tauri- 1900 km) could be corroborated. 4. These data suggest that small ranges of macro-stygobionts are the rule, and ranges over 200 km are extremely rare. 5. The implications of this result for groundwater biodiversity assessment and conservation include a considerable increase in overall diversity at the regional and continental scale and a strong decrease in faunal similarities among regions, coupled with greater endemism.
Microplastic pollution in karst systems is still poorly studied, despite the presence of protected species and habitats, and important water reserves. Vulnerable key species hosted in these habitats ...could consume or assimilate microplastics, which can irreversibly damage management efforts, and thus ecosystems functionality. This can be particularly true for subterranean water habitats where microplastic pollution effects on wildlife management programs are not considered. The aim of this study is to provide a case study from the Classical Karst Region, which hosts peculiar habitats and key species protected at European level, such as the olm Proteus anguinus. As this area has been deeply exploited and modified over time, and is adjacent to highways, roads and railways, which could contribute to pollution within the karst system, threatening the ecosystems, it provides a perfect model system.
In this study we collected and investigated water and sediment samples from aquatic environments of surface and subterranean habitats hosting several subterranean environment-adapted organisms. Examined particles were counted and characterized by size, color and shape via visual identification under a microscope, with and without UV light. Furthermore, spectroscopic analyses were carried out in order to identify microplastics typology. Microplastics were found in all examined habitats. In water, microplastics concentration ranged from 37 to 86 items/L, in sediments from 776 to 2064 items/kg. Fibre-shape was the main present, followed by fragments and beads, suggesting multiple sources of pollution, especially textile products. Most of the particles were fluorescent under UV light and were mainly transparent, while not-fluorescent ones were especially black, blue or brown. Samples contained especially polyesters and copolymers. These results highlight intense MP pollution in karst areas, with significant impacts on water quality, and potential effects on subterranean environment-dwelling species. We stress the importance of monitoring pollution in these critical environments for biodiversity and habitat conservation: monitoring in karst areas must become a priority for habitat and species protection, and water resources management, improving analyses on a larger number of aquatic surface and subterranean habitats.
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•Karst surface and subterranean waters are polluted by microplastics.•Protected habitats and stygobiont species are threatened by microplastics.•Small size and fibre shape microplastics dominate the samples.•Samples contained especially polyesters and copolymers.•Monitoring aquatic environments is fundamental for their conservation.
In comparison to biodiversity on Earth's surface, subterranean biodiversity has largely remained concealed. The olm (Proteus anguinus) is one of the most enigmatic extant cave inhabitants, and until ...now little was known regarding its genetic structure and evolutionary history. Olms inhabit subterranean waters throughout the Dinaric Karst of the western Balkans, with a seemingly uniform phenotypic appearance of cave‐specialized traits: an elongate body, snout and limbs, degenerated eyes and loss of pigmentation (“white olm”). Only a single small region in southeastern Slovenia harbours olms with a phenotype typical of surface animals: pigmented skin, eyes, a blunt snout and short limbs (“black olm”). We used a combination of mitochondrial DNA and genome‐wide single nucleotide polymorphism data to investigate the molecular diversity, evolutionary history and biogeography of olms along the Dinaric Karst. We found nine deeply divergent species‐level lineages that separated between 17 and 4 million years ago, while molecular diversity within lineages was low. We detected no signal of recent admixture between lineages and only limited historical gene flow. Biogeographically, the contemporaneous distribution of lineages mostly mirrors hydrologically separated subterranean environments, while the historical separation of olm lineages follows microtectonic and climatic changes in the area. The reconstructed phylogeny suggests at least four independent transitions to the cave phenotype. Two of the species‐level lineages have miniscule ranges and may represent Europe's rarest amphibians. Their rarity and the decline in other lineages call for protection of their subterranean habitats.
Deciphering the genetic code of organisms with unusual phenotypes can help answer fundamental biological questions and provide insight into mechanisms relevant to human biomedical research. The cave ...salamander Proteus anguinus (Urodela: Proteidae), also known as the olm, is an example of a species with unique morphological and physiological adaptations to its subterranean environment, including regenerative abilities, resistance to prolonged starvation, and a life span of more than 100 years. However, the structure and sequence of the olm genome is still largely unknown owing to its enormous size, estimated at nearly 50 gigabases. An international Proteus Genome Research Consortium has been formed to decipher the olm genome. This perspective provides the scientific and biomedical rationale for exploring the olm genome and outlines potential outcomes, challenges, and methodological approaches required to analyze and annotate the genome of this unique amphibian.
An international Proteus Genome Research Consortium has been formed to decipher the genome of Proteus anguinus (the olm). This perspective provides the scientific and biomedical rationale for exploring the olm genome and outlines potential outcomes, challenges, and methodological approaches required to analyze and annotate the genome of this unique amphibian.
Most research on mechanisms of aging is being conducted in a very limited number of classical model species, i.e., laboratory mouse (
Mus musculus
), rat (
Rattus norvegicus domestica
), the common ...fruit fly (
Drosophila melanogaster
) and roundworm (
Caenorhabditis elegans
). The obvious advantages of using these models are access to resources such as strains with known genetic properties, high-quality genomic and transcriptomic sequencing data, versatile experimental manipulation capabilities including well-established genome editing tools, as well as extensive experience in husbandry. However, this approach may introduce interpretation biases due to the specific characteristics of the investigated species, which may lead to inappropriate, or even false, generalization. For example, it is still unclear to what extent knowledge of aging mechanisms gained in short-lived model organisms is transferable to long-lived species such as humans. In addition, other specific adaptations favoring a long and healthy life from the immense evolutionary toolbox may be entirely missed. In this review, we summarize the specific characteristics of emerging animal models that have attracted the attention of gerontologists, we provide an overview of the available data and resources related to these models, and we summarize important insights gained from them in recent years. The models presented include short-lived ones such as killifish (
Nothobranchius furzeri
), long-lived ones such as primates (
Callithrix jacchus, Cebus imitator, Macaca mulatta
), bathyergid mole-rats (
Heterocephalus glaber, Fukomys spp.
), bats (
Myotis spp.
), birds, olms (
Proteus anguinus
), turtles, greenland sharks, bivalves
(Arctica islandica
), and potentially non-aging ones such as
Hydra
and
Planaria
.
In surveillance of subterranean fauna, especially in the case of rare or elusive aquatic species, traditional techniques used for epigean species are often not feasible. We developed a non-invasive ...survey method based on environmental DNA (eDNA) to detect the presence of the red-listed cave-dwelling amphibian, Proteus anguinus, in the caves of the Dinaric Karst. We tested the method in fifteen caves in Croatia, from which the species was previously recorded or expected to occur. We successfully confirmed the presence of P. anguinus from ten caves and detected the species for the first time in five others. Using a hierarchical occupancy model we compared the availability and detection probability of eDNA of two water sampling methods, filtration and precipitation. The statistical analysis showed that both availability and detection probability depended on the method and estimates for both probabilities were higher using filter samples than for precipitation samples. Combining reliable field and laboratory methods with robust statistical modeling will give the best estimates of species occurrence.
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