•Co-exposure to MPs and OPFRs induced greater oxidative stress in mice.•Co-exposure to MPs and OPFRs induced greater neurotoxicity in mice.•Co-exposure to MPs and OPFRs enhanced disruption of amino ...acid metabolism and energy metabolism in mice.
This study was performed to reveal the health risks of co-exposure to organophosphorus flame retardants (OPFRs) and microplastics (MPs). We exposed mice to polyethylene (PE) and polystyrene (PS) MPs and OPFRs tris (2-chloroethy) phosphate (TCEP) and tris (1,3-dichloro-2-propyl) phosphate (TDCPP) for 90 days. Biochemical markers and metabolomics were used to determine whether MPs could enhance the toxicity of OPFRs. Superoxide dismutase (SOD) and catalase (CAT) increased (p < 0.05) by 21% and 26% respectively in 10 μg/L TDCPP + PE group compared to TDCPP group. Lactate dehydrogenase (LDH) in TDCPP + MPs groups were higher (18%–30%) than that in TDCPP groups (p < 0.05). Acetylcholinesterase (AChE) in TCEP + PE groups were lower (10%–19%) than those in TCEP groups (p < 0.05). These results suggested that OPFR co-exposure with MPs induced more toxicity than OPFR exposure alone. Finally, in comparison to controls we observed that 29, 41, 41, 26, 40 and 37 metabolites changed significantly (p < 0.05; fold-change > 1.2) in TCEP, TCEP + PS, TCEP + PE, TDCPP, TDCPP + PS and TDCPP + PE groups, respectively. Most of these metabolites are related to pathways of amino acid and energy metabolism. Our results indicate that MPs aggravate the toxicity of OPFRs and highlight the health risks of MP co-exposure with other pollutants.
The dorsal, anal and caudal fins of vertebrates are proposed to have originated by the partitioning and transformation of the continuous median fin fold that is plesiomorphic to chordates. Evaluating ...this hypothesis has been challenging, because it is unclear how the median fin fold relates to the adult median fins of vertebrates. To understand how new median fins originate, here we study the development and diversity of adipose fins. Phylogenetic mapping shows that in all lineages except Characoidei (Characiformes) adipose fins develop from a domain of the larval median fin fold. To inform how the larva's median fin fold contributes to the adipose fin, we study Corydoras aeneus (Siluriformes). As the fin fold reduces around the prospective site of the adipose fin, a fin spine develops in the fold, growing both proximally and distally, and sensory innervation, which appears to originate from the recurrent ramus of the facial nerve and from dorsal rami of the spinal cord, develops in the adipose fin membrane. Collectively, these data show how a plesiomorphic median fin fold can serve as scaffolding for the evolution and development of novel, individuated median fins, consistent with the median fin fold hypothesis.
Systemic lupus erythematosus (SLE) is an autoimmune disease with a strong genetic component and etiology characterized by chronic inflammation and autoantibody production. The purpose of this study ...was to ascertain copy number variation (CNV) in SLE using a case-control design in an admixed Brazilian population. The whole-genome detection of CNV was performed using Cytoscan HD array in SLE patients and healthy controls. The best CNV candidates were then evaluated by quantitative real-time PCR in a larger cohort or validated using droplet digital PCR. Logistic regression models adjusted for sex and ancestry covariates was applied to evaluate the association between CNV with SLE susceptibility. The data showed a synergistic effect between the FCGR3B and ADAM3A loci with the presence of deletions in both loci significantly increasing the risk to SLE (5.9-fold) compared to the deletion in the single FCGR3B locus (3.6-fold). In addition, duplications in these genes were indeed more frequent in healthy subjects, suggesting that high FCGR3B/ADAM3A gene copy numbers are protective factors against to disease development. Overall, 21 rare CNVs were identified in SLE patients using a four-step pipeline created for identification of rare variants. Furthermore, heterozygous deletions overlapping the CFHR4, CFHR5 and HLA-DPB2 genes were described for the first time in SLE patients. Here we present the first genome-wide CNV study of SLE patients in a tri-hybrid population. The results show that novel susceptibility loci to SLE can be found once the distribution of structural variants is analyzed throughout the whole genome.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Female choice for traits signaling male genetic quality is expected to erode heritable variation in fitness, undermining the benefits of choice. Known as the lek paradox, this contradiction has ...motivated extensive population genetic theory, yet remains unresolved. Recent modeling by Bonduriansky and Day concludes that costly female preference is best maintained when male condition is determined by environmentally induced factors transmitted across single generations. Here, we reformulate their model in explicitly epigenetic terms, and review evidence that environmentally induced paternal effects are mediated through epigenetic changes in sperm. Noncoding RNA expression, DNA methylation and histone modifications are highly sensitive to diet, stress, toxicants and stochastic events. Epigenetic variation renews each generation and cannot be exhausted by selection. By choosing well‐endowed males that produce gametes in epigenetically good states, females can increase their fitness directly through increased fertilization success or indirectly through epigenetic effects on the fitness of offspring and potentially subsequent generations.
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Variation in diet, stress, and exercise affects male sexually selected trait expression and sperm epigenetic profiles that modulate offspring development, growth, and reproduction. Transmission of male condition via sperm‐borne epigenetic states provides a parsimonious explanation for the maintenance of adaptive female choice and heritable variation in male attractiveness and quality.
The study of host shifts by herbivorous insects has played an important role in evolutionary biology, contributing to research in coevolution, ecological speciation, and adaptive radiation. As ...invasive plants become more abundant in many ecosystems, the potential for exotic host use by native insects increases. Graves and Shapiro (2003) have documented exotic host use by 34% of Californian butterflies, suggesting that the plants and butterflies of California might be an important model system for the colonization and utilization of novel resources. In this study, we analyze relationships among geographic range, native diet breadth, and the use of exotic hosts by Californian butterflies and skippers (Lepidoptera). Geographic range and, to a lesser extent, native diet breadth are significant predictors of exotic host use, with positive relationships found both before and after phylogenetic correction. These results give insight into the process of insect host range evolution, as geographically widespread generalists have an apparently greater tendency to use novel, exotic hosts than geographically constrained specialists. Increasing occurrences of exotic host use are expected and those species not capable of shifting to nonnative hosts are likely to have higher vulnerability to extirpation and extinction in the future.
Although climate change models predict relatively modest increases in temperature in the tropics by the end of the century, recent analyses identify tropical ectotherms as the organisms most at risk ...from climate warming. Because metabolic rate in ectotherms increases exponentially with temperature, even a small rise in temperature poses a physiological threat to tropical ectotherms inhabiting an already hot environment. If correct, the metabolic theory of climate warming has profound implications for global biodiversity, since tropical insects and arachnids constitute the vast majority of animal species. Predicting how climate change will translate into fitness consequences for tropical arthropods requires an understanding of the effects of temperature increase on the entire life history of the species. Here, in a comprehensive case study of the fitness consequences of the projected temperature increase for the tropics, we conducted a split‐brood experiment on the neotropical pseudoscorpion, Cordylochernes scorpioides, in which 792 offspring from 33 females were randomly assigned at birth to control‐ and high‐temperature treatments for rearing through the adult stage. The diurnally varying, control treatment temperature was determined from long‐term, average daily temperature minima and maxima in the pseudoscorpion's native habitat. In the high temperature treatment, increasing temperature by the 3.5 °C predicted for the tropics significantly reduced survival and accelerated development at the cost of reduced adult size and a dramatic decrease in level of sexual dimorphism. The most striking effects, however, involved reproductive traits. Reared at high temperature, males produced 45% as many sperm as control males, and females failed to reproduce. Sequencing of the mitochondrial ND2 gene revealed two highly divergent haplogroups that differed substantially in developmental rate and survivorship but not in reproductive response to high temperature. Our findings suggest that reproduction may be the Achilles’ heel of tropical ectotherms, as climate warming subjects them to an increasingly adverse thermal environment.
Maternal inheritance of mitochondria creates a sex‐specific selective sieve through which mitochondrial mutations harmful to males but not females accumulate and contribute to sexual differences in ...longevity and disease susceptibility. Because eggs and sperm are under disruptive selection, sperm are predicted to be particularly vulnerable to the genetic load generated by maternal inheritance, yet evidence for mitochondrial involvement in male fertility is limited and controversial. Here, we exploit the coexistence of two divergent mitochondrial haplogroups (A and B2) in a Neotropical arachnid to investigate the role of mitochondria in sperm competition. DNA profiling demonstrated that B2‐carrying males sired more than three times as many offspring in sperm competition experiments than A males, and this B2 competitive advantage cannot be explained by female mitochondrial haplogroup or male nuclear genetic background. RNA‐Seq of testicular tissues implicates differential expression of mitochondrial oxidative phosphorylation (OXPHOS) genes in the B2 competitive advantage, including a 22‐fold upregulation of atp8 in B2 males. Previous comparative genomic analyses have revealed functionally significant amino acid substitutions in differentially expressed genes, indicating that the mitochondrial haplogroups differ not only in expression but also in DNA sequence and protein functioning. However, mitochondrial haplogroup had no effect on sperm number or sperm viability, and, when females were mated to a single male, neither male haplogroup, female haplogroup nor the interaction between male/female haplogroup significantly affected female reproductive success. Our findings therefore suggest that mitochondrial effects on male reproduction may often go undetected in noncompetitive contexts and may prove more important in nature than is currently appreciated.
In central Panamanian populations of the harlequin beetle riding pseudoscorpion, Cordylochernes scorpioides, males carrying highly divergent mitochondrial haplogroups (A and B2) differ extensively in the expression of mtDNA genes in testicular tissue. DNA profiling demonstrates that B2‐carrying males sire more than three times as many offspring in two‐male sperm competition experiments than do A males, and this B2 competitive advantage cannot be explained by female mitochondrial haplogroup or male nuclear genetic background. Despite conferring strong fitness benefits on males, the B2 haplogroup remains rare in central Panamá as a consequence of male inability to transmit mitochondria to offspring (mother's curse).
The broad-spectrum antibiotic tetracycline is used in animal production, antimicrobial therapy, and for curing arthropods infected with bacterial endosymbionts such as Wolbachia. Tetracycline ...inhibits mitochondrial translation, and recent evidence indicates that male reproductive traits may be particularly sensitive to this antibiotic. Here, we report the first multi-generation investigation of tetracycline's effects on ejaculate traits. In a study of the pseudoscorpion, Cordylochernes scorpioides, in which siblings were randomly assigned to control and tetracycline treatments across replicate full-sibling families, tetracycline did not affect body size in either sex, female reproduction or sperm number. However, tetracycline-treated males exhibited significantly reduced sperm viability compared to control males, and transmitted this toxic effect of tetracycline on sperm to their untreated sons but not to their F2 grandsons. These results are consistent with tetracycline-induced epigenetic changes in the male germline, and suggest the need for further investigation of transgenerational effects of tetracycline on male reproductive function.
Maternal inheritance of mitochondria creates a sex-specific selective sieve with implications for male longevity, disease susceptibility and infertility. Because males are an evolutionary dead end ...for mitochondria, mitochondrial mutations that are harmful or beneficial to males but not females cannot respond directly to selection. Although the importance of this male/female asymmetry in evolutionary response depends on the extent to which mitochondrial mutations exert antagonistic effects on male and female fitness, few studies have documented sex-specific selection acting on mitochondria. Here, we exploited the discovery of two highly divergent mitochondrial haplogroups (A and B2) in central Panamanian populations of the pseudoscorpion Cordylochernes scorpioides. Next-generation sequencing and phylogenetic analyses suggest that selection on the ND4 and ND4L mitochondrial genes may partially explain sexually antagonistic mitochondrial effects on reproduction. Males carrying the rare B2 mitochondrial haplogroup enjoy a marked advantage in sperm competition, but B2 females are significantly less sexually receptive at second mating than A females. This reduced propensity for polyandry is likely to significantly reduce female lifetime reproductive success, thereby limiting the spread of the male beneficial B2 haplogroup. Our findings suggest that maternal inheritance of mitochondria and sexually antagonistic selection can constrain male adaptation and sexual selection in nature.
Wolbachia are maternally inherited, cellular endosymbionts that can enhance their fitness by biasing host sex ratio in favour of females. Male killing (MK) is an extreme form of sex-ratio ...manipulation that is selectively advantageous if the self-sacrifice of Wolbachia in males increases transmission through females. In live-bearing hosts, females typically produce more embryos than can be carried to term, and reproductive compensation through maternal resource reallocation from dead males to female embryos could increase the number of daughters born to infected females. Here, we report a new strain of MK Wolbachia (wCsc2) in the pseudoscorpion, Cordylochernes scorpioides, and present the first empirical evidence that reproductive compensation favours the killing of males in a viviparous host. Females infected with the wCsc2 strain produced 26 per cent more and significantly larger daughters than tetracycline-cured females. In contrast to the previously described wCsc1 MK Wolbachia strain in C. scorpioides, wCsc2 infection was not accompanied by an increase in the rate of spontaneous brood abortion. Characterization of the wCsc1 and wCsc2 strains by multi-locus sequence typing and by Wolbachia surface protein (wsp) gene sequencing indicates that the marked divergence between these two MK strains in their impact on host reproductive success, and hence in their potential to spread, has occurred in association with homologous recombination in the wsp gene.
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