Biology subjects

Gal, Z.

Publications and source records attributed to Gal, Z..

10 recordsLinked to original sources

bioRxiv2024

Do pyrethroid insecticides influence sex ratios in agile frogs (Rana dalmatina)?

Environmental pollutants have the potential to alter sex ratios in wildlife through sex-biased mortality. Furthermore, endocrine disruptors may cause sex reversal during early ontogeny in ectothermic vertebrates, resulting in a phenotypic sex that is not concordant with the genotypic sex encoded by the sex chromosomes. Despite the wide-ranging implications of these sex-ratio biasing effects, they are rarely studied in ecotoxicology, especially in a way that allows for disentangling the two mechanisms. We investigated these effects of two synthetic pyrethroids, deltamethrin and etofenprox, that are commonly used insecticides and have been linked to adverse effects on fish and amphibian biodiversity. We assessed the effects of environmentally relevant concentrations of these two pyrethroids on phenotypic sex ratio, sex-dependent mortality, and sex reversal in agile frogs (Rana dalmatina). Tadpoles from field-collected eggs were reared in mesocosm until metamorphosis by adding 0.03 or 0.3 g/L of deltamethrin or etofenprox three times to the water. We observed no effect in three of the four treatment groups. However, in the lower-concentration etofenprox treatment, phenotypic sex ratio was male-biased two months post-metamorphosis, and genotypic sexing revealed that this was due to female-biased mortality during metamorphosis and not to sex reversal. Although the estimation certainty of these effects was somewhat limited, they highlight that not all sex-ratio distorting effects are caused by sex reversal. Therefore, ecotoxicological studies aiming to understand the endocrine distruptor effects of environmental contaminants should strive to separate the effects on sex determination and sex-dependent mortality.

ecology↗

bioRxiv2023

Concerted SUMO-targeted ubiquitin ligase activities of TOPORS and RNF4 are essential for stress management and cell proliferation

Protein SUMOylation provides a principal driving force for cellular stress responses including DNA-protein crosslink (DPC) repair and arsenic-induced PML body degradation. In genome-scale screens, we identified the human E3 ligase TOPORS as a key effector of SUMO-dependent DPC resolution. We demonstrate that TOPORS promotes DPC repair by functioning as a SUMO-targeted ubiquitin ligase (STUbL) for DPCs, combining ubiquitin ligase activity through its RING domain with poly-SUMO chain binding via a cluster of SUMO-interacting motifs, analogous to the STUbL RNF4. Surprisingly, the STUbL activities of TOPORS and RNF4 are both required for SUMO-dependent DPC repair, PML degradation and other stress responses, making overlapping and distinct contributions to ubiquitin chain formation on SUMOylated targets to enable p97/VCP unfoldase recruitment. Combined loss of TOPORS and RNF4 is synthetic lethal even in unstressed cells, leading to defective clearance of SUMOylated proteins from chromatin accompanied by cell cycle arrest and apoptosis. Together, our findings establish TOPORS as a novel STUbL whose concerted action with RNF4 defines a general mechanistic principle in crucial cellular processes governed by direct SUMO-ubiquitin crosstalk. HighlightsO_LIThe RING E3 ligase TOPORS is required for SUMO-dependent DPC repair C_LIO_LITOPORS is a novel SUMO-targeted ubiquitin ligase (STUbL) C_LIO_LITOPORS promotes multiple STUbL-driven processes in conjunction with RNF4 C_LIO_LICombined TOPORS and RNF4 loss is synthetic lethal in human cells C_LI

molecular biology↗

bioRxiv2023

Does stress make males? An experiment on the role of glucocorticoids in anuran sex reversal

Environmentally sensitive sex determination may help organisms adapt to environmental change but also makes them vulnerable to anthropogenic stressors, with diverse consequences for population dynamics and evolution. The mechanisms translating environmental stimuli to sex are controversial: although several fish experiments supported the mediator role of glucocorticoid hormones, results on some reptiles challenged it. We tested this hypothesis in amphibians by investigating the effect of corticosterone on sex determination in agile frogs (Rana dalmatina). This species is liable to environmental sex reversal whereby genetic females develop into phenotypic males. After exposing tadpoles during sex determination to waterborne corticosterone, the proportion of genetic females with testes or ovotestes increased from 11% to up to 32% at 3 out of 4 concentrations. These differences were not statistically significant except for the group treated with 10 nM corticosterone, and there was no monotonous dose-effect relationship. These findings suggest that corticosterone is unlikely to mediate sex reversal in frogs. Unexpectedly, animals originating from urban habitats had higher sex-reversal and corticosterone-release rates, reduced body mass and development speed, and lower survival compared to individuals collected from woodland habitats. Thus, anthropogenic environments may affect both sex and fitness, and the underlying mechanisms may vary across ectothermic vertebrates.

physiology↗

bioRxiv2023

A novel ground truth dataset enables robust 3D nuclear instance segmentation in early mouse embryos

For investigations into fate specification and cell rearrangements in time-lapse images of preimplantation embryos, automated 3D instance segmentation of nuclei and subsequent nuclear tracking are invaluable. Often, the images low signal-to-noise ratio and high voxel anisotropy and the nucleis dense packing and variable shapes limit the performance of many segmentation methods, while subsequent tracking of nuclear instances is complicated by low frame rates and sample movements. Supervised machine learning approaches can radically improve segmentation accuracy and enable easier tracking, but they often require large amounts of difficult-to-obtain annotated 3D data. Here we report a novel mouse line expressing near-infrared nuclear reporter H2B-miRFP720. H2B-miRFP720 is the longest wavelength nuclear reporter in mice and can be imaged simultaneously with other reporters with minimal overlap. We then generate a dataset, which we call BlastoSPIM, of 3D microscopy images of H2B-miRFP720-expressing embryos with ground truth for nuclear instance segmentation. Using BlastoSPIM, we benchmark the performance of seven convolutional neural networks and identify Stardist-3D as the most accurate instance segmentation method across preimplantation development. We then construct a complete pipeline for nuclear instance segmentation with our BlastoSPIM-trained Stardist-3D models and lineage tracking from the 8-cell stage to the end of preimplantation development (> 100 nuclei). Finally, we demonstrate BlastoSPIMs usefulness as pre-train data for related problems, both for a different imaging modality and for different model systems. BlastoSPIM, its corresponding Stardist-3D models, and documentation of the full associated analysis pipeline are available at: blastospim.flatironinstitute.org.

developmental biology↗

bioRxiv2022

Analysis of the abomasal transcriptome of LDA affected cattle

Left displacement of the abomasum (LDA) is a common condition in Holstein population mainly occur around the time of parturition. The entrapped abomasum located between the rumen and the abdominal wall caused by the abomasal hypomotility. The heritability of LDA estimated higher than for other bovine diseases but a number of management and nutritional conditions are also affecting the disease appearance. Genome studies revealed many significant genomic regions associated with LDA, although an RNA sequencing analysis of abomasum is missing from the literature. Within the framework of this research, we tried to patch up this area missing from the literature and to reveal the genetic causes and a complex interaction between the endocrine and neuromuscular pathways behind the symptoms of the disease with the help of transcriptomic analysis.

bioinformatics↗

bioRxiv2022

Patterns of numtogenesis in sixteen different mice strains

1Numtogenesis is the phenomenon of mitochondrial sequence localisation and integration into the nuclear genome. This is an ongoing process which contributed to the complexity of eukaryotic genomes. The sequences that are integrated into the nuclear genome are called nuclear mitochondrial sequences (numt). numts have a wide variety of applications in tumor biology, phylogenetic studies, forensic research and so on. Mus musculus musculus is the most popular model organism. Numerous mouse strains are used in medical research to model human diseases. Numts were described in the genome of Mus musculus musculus just like in many other species however the characterisation of numts in different mouse strains is missing. In this study we explored the patterns of numtogenesis in 16 mouse strains by aligning the nuclear genomes with the corresponding mitochondria. Investigation of numts shed light on strain specific differences and resembles the phylogenetic relationships as to our current knowledge in most of the cases.

bioinformatics↗

bioRxiv2021

"Heat waves" experienced during larval life have species-specific consequences on life-history traits and sexual development in anuran amphibians

Extreme temperatures during heat waves can induce mass-mortality events, but can also exert sublethal negative effects by compromising life-history traits and derailing sexual development. Ectothermic animals may, however, also benefit from increased temperatures via enhanced physiological performance and the suppression of cold-adapted pathogens. Therefore, it is crucial to address how the intensity and timing of naturally occurring or human-induced heat waves affect life-history traits and sexual development in amphibians, to predict future effects of climate change and to minimise risks arising from the application of elevated temperature in disease mitigation. We raised agile frog (Rana dalmatina) and common toad (Bufo bufo) tadpoles at 19 {degrees}C and exposed them to a simulated heat wave of 28 or 30 {degrees}C for six days during one of three ontogenetic periods (early, mid or late larval development). In agile frogs, exposure to 30 {degrees}C during early larval development increased mortality. Regardless of timing, all heat-treatments delayed metamorphosis, and exposure to 30 {degrees}C decreased body mass at metamorphosis. Furthermore, exposure to 30 {degrees}C during any period and to 28 {degrees}C late in development caused female-to-male sex reversal, skewing sex ratios strongly towards males. In common toads, high temperature only slightly decreased survival and did not influence phenotypic sex ratio, while it reduced metamorph mass and length of larval development. Juvenile body mass measured two months after metamorphosis was not adversely affected by temperature treatments in either species. Our results indicate that heat waves may have devastating effects on amphibian populations, and the severity of these negative consequences, and sensitivity can vary greatly between species and with the timing and intensity of heat. Finally, thermal treatments against cold-adapted pathogens have to be executed with caution, taking into account the thermo-sensitivity of the species and the life stage of animals to be treated.

ecology↗

bioRxiv2020

Sex reversal and ontogeny under climate change and chemical pollution: are there interactions between the effects of elevated temperature and a xenoestrogen on early development in agile frogs?

Anthropogenic environmental change poses a special threat to species in which genetic sex determination can be overwritten by the thermal and chemical environment. Endocrine disrupting chemicals as well as extreme temperatures can induce sex reversal in such species, with wide-ranging consequences for fitness, demography, population viability and evolution. Despite accumulating evidence suggesting that chemical and thermal effects may interact in ecological contexts, little is known about their combined effects on sex reversal. Here we assessed the simultaneous effects of high temperature (masculinizing agent) and 17-ethinylestradiol (EE2), a widespread xenoestrogen (feminizing agent), on sexual development and fitness-related traits in agile frogs (Rana dalmatina). We exposed tadpoles to a six-days heat wave (30 {degrees}C) and/or an ecologically relevant concentration of EE2 (30 ng/L) in one of three consecutive larval periods, and diagnosed sex reversals two months after metamorphosis using species-specific markers for genetic sexing. We found that high temperature induced female-to-male sex reversal, decreased survival, delayed metamorphosis, decreased body mass at metamorphosis, and increased the proportion of animals that had no fat bodies, while EE2 had no effect on these traits. Simultaneous exposure to heat and EE2 had non-additive effects on juvenile body mass, which were dependent on treatment timing and further complicated by a negative effect of sex reversal on body mass. These results show that environmentally relevant exposure to EE2 does not diminish the masculinizing effects of high temperature. Instead, our findings on growth suggest that climate change and chemical pollution may have complex consequences for individual fitness and population persistence in species with environment-sensitive sex determination.

pharmacology and toxicology↗

bioRxiv2020

A new molecular method for the exploration of hybrid zones between two toad species of conservation interest

Analyzing hybrid zones between previously isolated lineages allows insight into processes determining the fate of re-encounter of these taxa. The distributions of Fire-bellied (Bombina bombina) and Yellow-bellied toads (B. variegata) meet in the Carpathian Basin resulting in a narrow contact zone in the foothill regions, where hybrids often appear. Our aim was to explore a transient zone between B. bombina and B. variegata within the Carpathian Basin along a transect including the Borzsony Hills in Hungary and Krupinska Planina in Slovakia. We visited 28 locations in these areas and collected altogether 230 specimens, photographed and sampled them using buccal swabs. In order to distinguish between the two species and determine hybrid individuals, we used mitochondrial markers and designed a novel technique based on the restriction of the Ncx-1 gene. The geographical distribution pattern of these two species delivered unexpected results, as Borzsony Hills was completely colonised by B. bombina including locations which can be classified as typical habitats of B. variegata. Moreover, in Krupinska Planina many locations were also colonised by B. bombina, including high altitude ponds. The most remote sites still harbour B. variegata populations, but seven of these were found with hybrid individuals. This pattern may indicate the northward and altitudinal range expansion of B. bombina and the colonisation of habitats of its sister species in these areas. Our results warrant enhanced attention to hybrid zones, where introgression and changes in population composition may reflect recent rapid environmental alterations and redirect conservation focus.

ecology↗

bioRxiv2018

CRISPR/Cas9-mediated knock-out of dUTPase in mice leads to early embryonic lethality

Sanitization of nucleotide pools is essential for genome maintenance. Among the enzymes significant in this mechanism, deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase) performs cleavage of dUTP into dUMP and inorganic pyrophosphate. By this reaction the enzyme efficiently prevents uracil incorporation into DNA and provides dUMP, the substrate for de novo thymidylate biosynthesis. Despite its physiological significance, knock-out models of dUTPase have not yet been investigated in mammals, only in unicellular organisms, such as bacteria and yeast. Here we generate CRISPR/Cas9-mediated dUTPase knock-out in mice. We find that heterozygous dut +/-animals are viable while the decreased dUTPase level is clearly observable. We also show that the enzyme is essential for embryonic development. Based on the present results, early dut -/-embryos can still reach the blastocyst stage, however, they die shortly after implantation. Analysis of preimplantion embryos indicate perturbed growth of both inner cell mass (ICM) and trophectoderm (TE). We conclude that dUTPase is indispensable for post-implantation development in mice. The gene targeting model generated in the present study will allow further detailed studies in combination with additional gene knock-outs.

developmental biology↗