Helena Bilandzija

Helena Bilandzija
Ruđer Bošković Institute | RBI · Department of Molecular Biology

PhD

About

43
Publications
11,768
Reads
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564
Citations
Citations since 2017
27 Research Items
460 Citations
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
Additional affiliations
May 2019 - present
Ruđer Bošković Institute
Position
  • Principal Investigator
July 2017 - April 2019
Ruđer Bošković Institute
Position
  • PostDoc Position
December 2014 - June 2017
University of Maryland, College Park
Position
  • PostDoc Position

Publications

Publications (43)
Conference Paper
Full-text available
Telomeres are specialized and highly repetitive noncoding DNA structures at the end of linear chromosomes that are essential for maintaining genomic integrity. Each time a cell divides, telomeres are not fully replicated and the resulting cells have shorter telomeres than the progenitor cells. This incomplete replication of telomeres (i.e., shorten...
Article
Objective obstacles such as high water levels that prevent access to caves at certain times of the year or the need to use complex tools and skills such as cave diving make biological research in caves extremely complex and occasionally dangerous. Moreover, to study physiological and behavioral adaptations of cave animals, they must be kept under c...
Article
Full-text available
A traditional explanation for the loss of pigmentation in cave dwellers is the absence of negative selection acting on surface species to remove all albinos from the population. Recently, however, evidence has been accumulating that albinism in the cavefish Astyanax mexicanus has several beneficial pleiotropic effects. Albino cavefish have higher c...
Article
Full-text available
Darkness is the hallmark of all subterranean habitats and, to some degree, of many surface habitats. Many surface animals that live in semi-dark habitats, such as freshwater benthos, are photophobic. Yet, few of them can colonize caves and form subterranean populations. We hypothesize that phenotypic plasticity induced by darkness enables surface c...
Article
Full-text available
The surface ancestors of subterranean species are often hypothesized to possess pre-adaptations that enable them to successfully initiate colonization of caves. Nocturnal habits and the use of microhabitats such as the underside of rocks or leaf litter are two simple examples. However, there are many exceptions, and a mechanistic explanation for th...
Article
Full-text available
Albinism, or loss of pigment, is a typical adaptation to living in caves and occurs in numerous cave dwellers. To understand the evolution of this trait, one must identify the type of biological pigment present in the phylogenetically closest surface relatives. The absence of pigmentation has been studied primarily in terms of melanin deficiency, w...
Article
Full-text available
Many aspects of cave animal biology cannot be understood through field observations alone. Access to some subterranean habitats is often technically challenging, rendering long-term monitoring of cave-dwelling species or investigating some aspects of their biology difficult. Also, contemporary research questions and methods require sampling individ...
Article
Full-text available
An extraordinary longevity has been observed in some cave species, and this raised the hypothesis that a longer lifespan may be considered one of the characteristic traits of these animals. However, only a few cave species have been studied thus far, and a firm conclusion remains to be drawn. Here we review the available knowledge on the longevity...
Article
Brazil’s caves, home to diverse species and minerals, were stripped of protections by a recent presidential decree.
Article
Adaptation to novel environments often involves the evolution of multiple morphological, physiological, and behavioral traits. One striking example of multi-trait evolution is the suite of traits that has evolved repeatedly in cave animals, including regression of eyes, loss of pigmentation, and enhancement of non-visual sensory systems.1,2 The Mex...
Article
Full-text available
• Caves and other subterranean habitats fulfill the requirements of experimental model systems to address general questions in ecology and evolution. Yet, the harsh working conditions of these environments and the uniqueness of the subterranean organisms have challenged most attempts to pursuit standardized research. • Two main obstacles have syner...
Preprint
Full-text available
Groundwater habitats in the Dinaric Karst are home to the only known cave-adapted genus of bivalve mollusks, which currently survives as three distinct species with a highly fragmented distribution. Over the past few decades, Congeria populations suffered a steep decline across their range, as a result of human activities. Here, we identify the mos...
Book
Full-text available
As karst phenomena, caves represent the most secluded, but also the most fascinating natural values of the Island of Mljet. Many of them contain a diverse rare and endemic subterranean fauna; impressive cave formations (speleothems), and archaeological artifacts which bear witness to the first inhabitants of the Island of Mljet who frequented the u...
Preprint
Full-text available
(1) Caves and other subterranean habitats fulfill the requirements of experimental model systems to address general questions in ecology and evolution. Yet, the harsh working conditions of these environments and the uniqueness of the subterranean organisms have challenged most attempts to pursuit standardized research (2) Two main obstacles have sy...
Article
Full-text available
A widely accepted model for the evolution of cave animals posits colonization by surface ancestors followed by the acquisition of adaptations over many generations. However, the speed of cave adaptation in some species suggests mechanisms operating over shorter timescales. To address these mechanisms, we used Astyanax mexicanus, a teleost with ance...
Article
Full-text available
A widely accepted model for the evolution of cave animals posits colonization by surface ancestors followed by the acquisition of adaptations over many generations. However, the speed of cave adaptation in some species suggests mechanisms operating over shorter timescales. To address these mechanisms, we used Astyanax mexicanus, a teleost with ance...
Article
Species richness of terrestrial isopods is high in caves of the Dinaric Karst, which hosts ~10% of the world’s nominal oniscidean troglobionts. The most widespread taxon is the southern European genus Alpioniscus, which consists of two subgenera: Alpioniscus s.s. and Illyrionethes. Before this study, 14 nominal troglobiotic Illyrionethes taxa were...
Preprint
Full-text available
A widely accepted model for the evolution of cave animals posits colonization by surface ancestors followed by the acquisition of adaptations over many generations. However, the speed of cave adaptation in some species suggests mechanisms operating over shorter timescales. To address these mechanisms, we used Astyanax mexicanus , a teleost with anc...
Conference Paper
Full-text available
Recent records of Proteus anguinus outside its historically known range (Gorički et al. 2017), discovered through detection of its DNA dissolved in groundwater (environmental DNA or eDNA), mark the beginning of a new era in the study and conservation of cryptic subterranean biodiversity. An upgraded technology, droplet digital PCR (ddPCR), initiall...
Article
Understanding the molecular basis of repeatedly evolved phenotypes can yield key insights into the evolutionary process. Quantifying gene flow between populations is especially important in interpreting mechanisms of repeated phenotypic evolution, and genomic analyses have revealed that admixture occurs more frequently between diverging lineages th...
Preprint
Full-text available
Understanding the molecular basis of repeated evolved phenotypes can yield key insights into the evolutionary process. Quantifying the amount of gene flow between populations is especially important in interpreting mechanisms of repeated phenotypic evolution, and genomic analyses have revealed that admixture is more common between diverging lineage...
Article
Multiple cave populations of the teleost Astyanax mexicanus have repeatedly reduced or lost eye and body pigmentation during adaptation to dark caves. Albinism, the complete absence of melanin pigmentation, is controlled by loss-of-function mutations in the oca2 gene. The mutation is accompanied by an increase in the melanin synthesis precursor L-t...
Article
Full-text available
Nucleoside diphosphate kinases are enzymes present in all domains of life. In animals, they are called Nme or Nm23 proteins, and are divided into group I and II. Human Nme1 was the first protein identified as a metastasis suppressor. Because of its medical importance, it has been extensively studied. In spite of the large research effort, the exact...
Article
Full-text available
Many species adapted to aphotic subterranean habitats have lost all body pigmentation. Yet, melanization is an important component of wound healing in arthropods. We amputated appendages in a variety of cave-adapted and surface-dwelling arthropods. A dark clot formed at the site of injury in most species tested, including even albino cave-adapted s...
Article
Full-text available
Caves are some of the least-known ecosystems on Earth and long-term ecological studies and population size estimates are very rare. Genus Congeria is a Tertiary relict that comprises three species from Dinaric karst area; C. kusceri, C. jalzici and C. mulaomerovici, each with very limited distribution. They are the only known cave bivalves and in c...
Chapter
Full-text available
The reduction of pigmentation is a hallmark of cave-adapted animals. Cavefish depigmentation involves i) a decrease in the number of melanophores, which is controlled by many different genes; ii) a change in the coloration of melanophores from black to brown due to mutations in the mc1r gene; and iii) in some populations, the complete shutdown of m...
Article
Full-text available
Albinism, the loss of melanin pigmentation, has evolved in a diverse variety of cave animals but the responsible evolutionary mechanisms are unknown. In Astyanax mexicanus, which has a pigmented surface dwelling form (surface fish) and several albino cave-dwelling forms (cavefish), albinism is caused by loss of function mutations in the oca2 gene,...
Article
Full-text available
Background Patterns of biodiversity in the subterranean realm are typically different from those encountered on the Earth’s surface. The Dinaric karst of Croatia, Slovenia and Bosnia and Herzegovina is a global hotspot of subterranean biodiversity. How this was achieved and why this is so remain largely unresolved despite a long tradition of resear...
Data
Full-text available
Shell morphometrics. The file contains details of the methods and results of morphometric shell measurements.
Data
Full-text available
The PCR primers, reactions and conditions used in this study. The file contains details on the PCR primers, reaction components and cycling conditions used in the study.
Article
Full-text available
The complete mitochondrial DNA (mtDNA) genome of the Eunapius subterraneus (Porifera, Demospongiae), a unique stygobitic sponge, was analyzed and compared with previously published mitochondrial genomes from this group. The 24,850bp long mtDNA genome is circular with the same gene composition as found in other metazoans. Intergenic regions (IGRs) c...
Data
Supplementary Fig. 1. Secondary structure of trnX from Ephydatia muelleri, Lubomirskia baicalensis, and Eunapius subterraneus with nucleotide identity presented in the table. Nucleotides that differ in comparison with E. subterraneus are marked in red.
Article
Albinism, the reduction or loss of melanin pigment, is found in many diverse cave-dwelling animals. The mechanisms responsible for loss of melanin pigment are poorly understood. In this study we use a melanogenic substrate assay to determine the position where melanin synthesis is blocked in independently evolved cave planthoppers from Hawaii and C...
Article
The freshwater sponge Eunapius subterraneus was described in 1984 on the basis of its morphology and unique ecological features. It inhabits caves in the Ogulin karst area as the only known stygobitic sponge, and an endangered karst species. We used three genetic markers with different evolutionary rates in phylogenetic analyses of E. subterraneus....
Article
Full-text available
The distribution and morphological variability of the troglobiotic freshwater sponge Eunapius subterraneus Sket & Velikonja, 1984 registered in Croatia as a threatened species in the IUCN category Endangered (EN) was investigated. The research area encompassed Velika and Mala Kapela Mountains as well as the upper catchment area of the Dobra and Mre...

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Projects (2)
Project
Subterranean environments are characterized by distinct ecological conditions, the most important of which is the absence of light. Sunlight can penetrate only the entrance areas, creating a gradient towards the deepest zone, where the microclimate is very stable. Darkness prevents colonization by most primary producers, creating a peculiar food web that, with a few exceptions (e.g. systems based on chemoautotrophy), relies on the input of organic matter from the surface. Consequently, food in most subterranean habitats is scarce and only occasionally available. The animals that live in these environments show peculiar adaptations. Among the most striking features is the loss of eyes and pigmentation, which is almost ubiquitous in various groups of cave animals. The extent of eye and pigment loss is regularly studied and even used to ecologically categorize species into strictly or facultatively subterranean. These two traits have been capturing the interest of researchers since Charles Darwin, and have recently been the subject of heated debates about the evolutionary mechanisms of their origin. Other common morphological changes include the enhancement of non-visual sensory systems and associated structures, such as the elongation of chemoreceptor- or mechanoreceptor-bearing appendages in arthropods, or the increase in the number of neuromasts and taste buds in fish. Physiological adaptations include lower metabolic rate, increased fat deposition, increased resistance to starvation, reduced number of offspring, enlarged eggs, and altered longevity. Behavioral adaptations include changes in activity patterns, feeding behavior, and social behavior, among others. Compared to morphological traits, these adaptations are less well known because the study of physiology and behavior requires live animals that are difficult to observe in their natural environment or, when brought into the laboratory, the survival (and possibly behavior) of the species is usually strongly influenced by the artificial conditions. As a result, most of our knowledge of these adaptations comes from the study of only a handful of species, and many of the commonly cited subterranean adaptations have been demonstrated in only a few animals (often vertebrates). Another major gap in our knowledge is the mechanistic understanding of the evolution of cave adaptations at the molecular level. Few molecular mechanisms have been discovered to date, and studies in both model and non-model species can provide important information and open new frontiers of research. Therefore, this Research Topic aims to fill in the gaps regarding the extent of occurrence as well as the molecular and evolutionary mechanisms behind different adaptations in diverse groups of cave-dwelling animals. We would also like to stimulate studies on lesser-known traits such as behavior and physiology. In addition, we would like to emphasize the importance of evaluating adaptations in facultative cave-dwelling species, as they may exhibit early-stage changes that are no longer apparent or are enhanced in evolved cave species. We also invite reviews that summarize current knowledge on the occurrence of different adaptations in a given species or animal group or, conversely, the occurrence of a given adaptation in different groups of cave-dwelling animals. https://www.frontiersin.org/research-topics/29052/adaptations-to-subterranean-environments
Project
Pigmentation protects animals from solar radiation and has critical roles in temperature control, camouflage, and in species and sex recognition. However, pigmentation is absent in some animals, a condition known as albinism. Albinism is one of the prime examples of convergence in nature because it has evolved repeatedly in phylogenetically distant taxa and in different environments lacking sunlight, regardless of the types of pigments present. Albinism is one of the defining features in animals adapted to cave habitats. Our previous research identified a relevant molecular change in multiple cave animals with melanin pigmentation, and that natural selection as opposed to drift may be involved. However, the exact genes and mutations that control this trait remain elusive. Also, nothing is known about the other pigments that are lost in cave animals. We will investigate the molecular and evolutionary mechanisms of albinism across different animal groups and the types of pigment they use to understand the mechanisms of cave adaptation at the molecular level (genotype to phenotype) and evolutionary forces related to convergent evolution. We will integrate experimental procedures across biological disciplines (molecular to organismal), using diverse organisms (carefully selected from planarians to vertebrates) from diverse environments (cave and surface, terrestrial and aquatic), and applying various methodological approaches (from laboratory to field).