The genomic response to urbanization in the damselfly Ischnura elegans

The complex and rapid environmental changes brought about by urbanization pose significant challenges to organisms. The multifaceted effects of urbanization often make it difficult to define and pinpoint the very nature of adaptive urban phenotypes. In such situations, scanning genomes for regions differentiated between urban and non-urban populations may be an attractive approach. Here, we investigated the genomic signatures of adaptation to urbanization in the damselfly Ischnura elegans sampled from 31 rural and urban localities in three geographic regions: southern and northern Poland, and southern Sweden. Genome-wide variation was assessed using more than 370,000 single nucleotide polymorphisms (SNPs) genotyped by ddRADseq. Associations between SNPs and the level of urbanization were tested using two genetic environment association methods: Latent Factors Mixed Models and BayPass. While we found numerous candidate SNPs and a highly significant overlap between candidates identified by the two methods within the geographic regions, there was a distinctive lack of repeatability between the geographic regions both at the level of individual SNPs and of genomic regions. However, we found "synapse organization" at the top of the functional categories enriched among the genes located in the proximity of the candidate urbanization SNPs. Interestingly, the overall significance of "synapse organization" was built up by the accretion of different genes associated with candidate SNPs in different geographic regions. This finding is consistent with the highly polygenic nature of adaptation, where the response may be achieved through a subtle adjustment of allele frequencies in different genes that contribute to adaptive phenotypes. Taken together, our results point to a polygenic adaptive response in the nervous system, specifically implicating genes involved in synapse organization, which mirrors the findings from several genomic and behavioral studies of adaptation to urbanization in other taxa.

The effect of temperature and invasive alien predator on genetic and phenotypic variation in the damselfly Ischnura elegans: cross-latitude comparison

BACKGROUND

Understanding and predicting how organisms respond to human-caused environmental changes has become a major concern in conservation biology. Here, we linked gene expression and phenotypic data to identify candidate genes underlying existing phenotypic trait differentiation under individual and combined environmental variables. For this purpose, we used the damselfly Ischnura elegans. Egg clutches from replicated high- (southern Sweden) and central-latitude (southern Poland) populations facing different degrees of seasonal time constraints were collected. Damselfly larvae were exposed to experimental treatments: current and mild warming temperatures crossed with the presence or absence of an invasive alien predator cue released by the spiny-cheek crayfish, Faxonius limosus, which is only present in Poland to date. We measured the following traits: larval development time, body size, mass and growth rate, and used the larvae for gene expression analysis by RNA-seq. Data were analysed using a multivariate approach.

RESULTS

We showed latitudinal differences in coping with mild warming and predator cues. When exposed to an increased temperature and a predator cue, central-latitude individuals had the shortest development and the fastest growth compared to high-latitude individuals. There was a general effect of predator cues regarding mass and growth rate reduction independent of latitude. Transcriptome analysis revealed that metabolic pathways related to larval anatomy and development tended to be upregulated in response to mild warming but only in fast-growing central-latitude individuals. Metabolic pathways linked to oxidative stress tended to be downregulated in response to a predator cue, especially in central-latitude individuals.

CONCLUSION

Different phenotypic and transcriptomic responses to environmental factors might be attributed to the variability in I. elegans life history strategies between the two latitudes caused by seasonal time constraints and to its coexistence with the invasive alien predator in nature. By providing insights into how organisms may respond to future anthropogenic changes, our results may be of particular interest in conservation biology.

Interspecific introgression of MHC genes in Triturus newts: Evidence from multiple contact zones

The major histocompatibility complex (MHC) genes are central to the adaptive immune response in vertebrates. Selection generally maintains high MHC variation because the spectrum of recognized pathogens depends on MHC polymorphism. Novel alleles favoured by selection originate by interallelic recombination or de novo mutations but may also be acquired by introgression from related species. However, the extent and prevalence of MHC introgression remain an open question. In this study, we tested for MHC introgression in six hybrid zones formed by six Triturus newt species. We sequenced and genotyped the polymorphic second exons of the MHC class I and II genes and compared their interspecific similarity at various distances from the centre of the hybrid zone. We found evidence for introgression of both MHC classes in the majority of examined hybrid zones, with support for a more substantial class I introgression. Furthermore, the overall MHC allele sharing outside of hybrid zones was elevated between pairs of Triturus species with abutting ranges, regardless of the phylogenetic distance between them. No effect of past hybrid zone movement on MHC allele sharing was found. Finally, using previously published genome-wide data, we demonstrated that MHC introgression was more extensive than genome-wide introgression, supporting its adaptive potential. Our study thus provides evidence for the prevalence of MHC introgression across multiple Triturus hybrid zones, indicating that MHC introgression between divergent hybridizing species may be widespread and adaptive.

Immunohistochemical study on the development of cholinergic and nitrergic nerve structures in the bovine esophageal groove

The proper functioning of the perinatal sucking reflex in calves is essential for the prevention of milk leakage into the rumen. The complex process behind its regulation is mediated at the gut level via multiple excitatory and inhibitory neurotransmitters, of which acetylcholine and nitric oxide are of fundamental importance. The aim of our study was to depict age-related alterations in the cholinergic and nitrergic innervation of the esophageal groove (EG) using immunohistochemistry and Real-Time PCR methods. We found out that the highest number of cholinergic nerve cells was present in the second trimester fetuses. From this developmental stage onward, their amount was gradually decreasing and reached the lowest value in 4-year-old cows. The same developmental pattern was observed for nitrergic nerve structures with the highest percentage of nitrergic neurons in the third trimester fetuses. Our observations prove that both neuronal populations are crucial for a proper closure of EG in calves. Therefore, their contribution to a general neuronal activity in the ENS diminishes with age as the high motility of a gastric groove is not necessarily required in older cattle.

Bistability of magnetic states in Fe-Pd nanocap arrays

Magnetic bistability between vortex and single domain states in nanostructures are of great interest from both fundamental and technological perspectives. In soft magnetic nanostructures, the transition from a uniform collinear magnetic state to a vortex state (or vice versa) induced by a magnetic field involves an energy barrier. If the thermal energy is large enough for overcoming this energy barrier, magnetic bistability with a hysteresis-free switching occurs between the two magnetic states. In this work, we tune this energy barrier by tailoring the composition of FePd alloys, which were deposited onto self-assembled particle arrays forming magnetic vortex structures on top of the particles. The bifurcation temperature, where a hysteresis-free transition occurs, was extracted from the temperature dependence of the annihilation and nucleation field which increases almost linearly with Fe content of the magnetic alloy. This study provides insights into the magnetization reversal process associated with magnetic bistability, which allows adjusting the bifurcation temperature range by the material properties of the nanosystem.

The effect of Fe on the structure and electrical conductivity of sodium borosilicate glasses

We report the synthesis and characterization of iron-bearing sodium borosilicate glasses with an Fe₂O₃ content lower than 10 mol%. Using Mössbauer spectroscopy we demonstrate that Fe ions most probably have a tetrahedral oxygen environment for an iron oxide content higher than 5 mol%. Additionally, the Mössbauer results along with the X-ray diffraction studies indicate the formation of magnetite nanoclusters. The electrical conductivity of iron-containing sodium borosilicate glasses is studied over a wide temperature range. The impact of iron content on the dielectric permittivity and electrical properties is discussed. Finally, ionic conduction is identified in the high temperature region and its physical origin is explained. A similar activation energy of the dc conductivity and the activation energy of the electrical relaxation suggest that both the relaxation and conduction processes can be ascribed to the same type of entities.

Fabrication of flexible highly ordered porous alumina templates by combined nanosphere lithography and anodization

In this work, we propose a new method for the large-scale production of flexible, periodic alumina arrays with well-ordered pores. We show the incorporation of pre-patterning based on polystyrene (PS) nanosphere lithography into an aluminium anodization process. We prepared ordered monolayers of PS spheres with average diameters of (510 ± 10) nm and (430 ± 10) nm on a large area (1.5 × 1.5 cm²) of the Si substrate. Next, we deposited a 5 μm aluminium layer on arrays of PS nanospheres using the sputtering technique. After the deposition, we covered the aluminium film with a polymer Scotch adhesive tape, and separated it from the silicon substrate by ultrasonic-assisted lift-off. Finally, we performed the anodization of the aluminium. We compared the pore and cell sizes, and the pore distance for the templates obtained by this technique, with reference to the templates prepared by a two-step anodization process. Using this new approach, we obtained highly ordered hexagonal 2D lattices over a large area of up to 2 cm² with sparse defects, amounting to not more than four defects per 1000 μm² on average. Here, we show that the use of indentation techniques is not necessary and can be replaced by a fast, cheap and easy pre-patterning step based on nanosphere lithography.

Immunohistochemical characterization of the jugular (superior vagal) ganglion in the pig

The study was carried out on three 4-month old female pigs. All the animals were deeply anesthetized and transcardially perfused with 4% buffered paraformaldehyde (pH 7.4). Left and right superior vagal ganglia (SVG) were collected and processed for immunofluorescence labeling method. The preparations were examined under a Zeiss LSM 710 confocal microscope equipped with adequate filter block. Neurons forming SVG were round or oval in shape with a round nucleus in the center. The majority of them (52%) were medium (M) (31-50 μm in diameter) while 7% and 41% were small (S) (up to 30μm in diameter) or large (L) (above 50 μm in diameter) in size, respectively. Double-labeling immunofluorescence revealed that SVG neurons stained for CGRP (approx. 57%; among them 37%, 9% and 54% were M, S and L in size, respectively), SP (14.5%; 72.4% M, 3.4% S, 24.2% L), VACHT (26%; 63% M, 24% S and 13% L), GAL (14%; 57% M, 29% S, 14% L), NPY (12%; 53% M, 12% S, 35% L), Met-Enk (5%; 40% M, 6% S and 54% L), PACAP (15%; 52% M, 24% S and 24% L), VIP (6.3%; 67% M, 8% S and 25% L), and NOS-positive (6%; 31% M and 69% L). The most abundant populations of intraganglionic nerve fibers were those which stained for CGRP or GAL, whereas only single SP-, PACAP- or Met-ENK-positive nerve terminals were observed.

Magnetic transition from dot to antidot regime in large area Co/Pd nanopatterned arrays with perpendicular magnetization

We have studied the transition between two different magnetization reversal mechanisms for thin Co/Pd multilayers with perpendicular magnetic anisotropy, appearing in magnetic dot and antidot arrays, which were prepared by nanosphere lithography. Various ordered arrays of nanostuctures, both magnetic dots and antidots, were created by varying size and distance between the nanospheres employing RF-plasma etching. We have shown that the coercivity values reach a maximum for the array of antidots with a separation length close to the domain wall width. In this case, each area between three adjacent holes corresponds to a single domain configuration, which can be switched individually. On the contrary, small hole sizes and large volume of material between them results in domain wall propagation throughout the system accompanied by strong domain wall pinning at the holes. We have also shown the impact of edge effects on the magnetic anisotropy energy.

Ordered FePdCu nanoisland arrays made by templated solid-state dewetting

Ordered FePdCu nanoisland arrays were formed by annealing at 600 °C, which caused solid state dewetting of [Cu/Fe/Pd] multilayers deposited on self-assembled SiO2 nanospheres with a size of 100 nm. A single FePdCu island was formed on the top of each SiO2 nanosphere. The structure of the obtained system was studied by x-ray diffraction (XRD), while its magnetic properties were studied by SQUID magnetometry. A partially ordered L10 alloy appeared in the annealed films, leading to magnetic hardening of the material. The paper presents the influence of the patterning on the system properties. It is shown that templated dewetting is a method providing nanoislands with well-controlled sizes and positions. The role of copper admixture in controlling the structural and magnetic properties is also discussed.

PAC Studies of Ag-Hf Intermetallic Compounds

The hyperfine quadrupole interaction of 181Ta and 111Cd probes in HfAg and HfiAg com-pounds was studied at 24 to 1100 K with the time -differential perturbed angular correlation (TDPAC) technique. The EFGs measured in HfAg on 181Ta and 111Cd are 1.388(5)x1018 Vcm-2 and 0.340(5)x1018 Vcm -2 , respectively. For both probe atoms a linear decrease of the EFG with temperature was observed with slopes 1.11(2)x10-4 K-1 and 1.73(5)x10-4 K-1 for 181Ta and 111Cd, respectively. In Hf2 Ag, 0.469(2)x1018 Vcm-2 was determined on 181Ta nuclei and 0.428(5)x1018 Vcm-2 on 111Cd. Also a linear EFG temperature dependence with the large slope of 2.39(6)x10-4 K-1 was observed for 111Cd probes in Hf2Ag, while the EFG measured on 181Ta nuclei in this compound exhibits a very weak temperature variation which can be fitted neither with a linear T nor a T 3/2 dependence. In all cases the electronic contributions to the EFG are very small indicating that these transition element systems do not obey the universal correlation between the electronic and the ionic EFG observed in numerous other systems not belonging to the transition metal series.

[Experimental hepatocarcinogenesis--evaluation of the significance of theoretical models. Contemporary models]

There are an increasing number of models for the study of liver cancer development with such agents as chemicals, hormones, and viruses. This process is almost always a multistep and during the long period of cancer development, discrete cells or cell populations acquire step-by step the various properties that go to make up a cancer. The hepatocarcinogenesis models are useful in identification and analysis of the preneoplastic and neoplastic alterations, as well HCC. This article presents a review of theoretical foundation and mechanisms of various models of experimental hepatocarcinogenesis as well contain a short presentation of animals practical in those experiments, principally rats. The remarkable similarities between many models with different carcinogens in animals and humans suggest the importance of such studies in understanding of molecular basis of liver cancer development.

[Experimental hepatocarcinogenesis--evaluation of the significance of experimental modeling. Classical models]

There are an increasing number of models for the study of liver cancer development with such agents as chemicals, hormones, and viruses. This process is almost always a multistep and during the long period of cancer development, discrete cells or cell populations acquire step-by-step the various properties that go to make up a cancer. The hepatocarcinogenesis models are useful in identification and analysis of the preneoplastic and neoplastic alterations, as well HCC. This article presents a review of theoretical foundation and mechanisms of various models of experimental hepatocarcinogenesis as well contain a short presentation of animals practical in those experiments, principally rats. The remarkable similarities between many models with different carcinogens in animals and humans suggest the importance of such studies in understanding of molecular basis of liver cancer development.

Nuclear antigen with a molecular weight of 48,000 associated with malignant transformation

1. Analysis of immunoblots of one- and two-dimensional electropherograms of non-histone proteins from Kirkman-Robbins hepatoma, Morris hepatoma 7777, regenerating liver and normal liver demonstrated the presence of elevated level of nuclear antigen with mol. wt of 48,000 and pI of 5.4 in tumour cells. 2. Small amounts only were detected in proliferating and quiescent cells suggesting that different expression of this component may reflect biochemical events related to malignant transformation rather than to general cell activation.

Studies on low molecular weight nuclear protein of tumour and normal cells

1. Preliminary results of comparative electrophoretical and immunological analyses of the components of two classes of non-histone proteins, i.e. NHP1 and NHP2 eluted from hydroxyapatite allowed to suppose that protein of Mw 18,000 is specific for animal tumour cells. 2. However, the studies on cellular distribution of this polypeptide indicated that it is exclusively located in nuclei of hepatoma and normal liver as well. 3. The former observation seems to be the result of changes of the affinity of this protein to DNA during neoplastic transformation.

Identification of a nuclear antigen with molecular weight of 48,000 differentially expressed in tumour and normal cells

A non-histone protein with mol. wt of 48,000 differentially expressed in normal and tumour cells was identified using immunological criteria. Antibodies were raised against a component specific for Kirkman-Robbins hepatoma of mol. wt about 48,000 separated from hepatoma non-histone proteins by preparative electrophoresis in polyacrylamide gel. It was demonstrated by immunoblotting that Morris hepatoma 7777 and Ehrlich ascites cells share an antigenic non-histone protein with Kirman-Robbins hepatoma. Tumour cells when compared with normal cells, i.e. hamster and rat liver, are characterized by significant enrichment of this component. Intracellular distribution of the polypeptide with mol. wt 48,000 suggests that this component may be a structural protein the biosynthesis of which increases or the antigenic determinants of which change in tumour cells.