Sitting maneuver to uncover latent left ventricular outflow tract obstruction in patients without hypertrophic cardiomyopathy.

BACKGROUND: Left ventricular outflow tract obstruction [LVOTO; pressure gradient (PG) ≥30 mmHg] is observed in some patients without hypertrophic cardiomyopathy (HCM), and it may develop especially in older patients without HCM (non-HCM). The aim of this study is to investigate if the Valsalva or an upright sitting maneuver can unveil latent LVOTO in patients with non-HCM. METHODS: A total of 33 non-HCM patients with a late peaking or dagger-shaped pulsed Doppler waveform of the LVOT and PG <30 mmHg were included. The Doppler flow velocity of the LVOT was measured at rest, after the Valsalva and a sitting maneuver. Peak PG of ≥30 mmHg after either maneuver was defined as latent LVOTO. The angle between the left ventricular septum and the aorta in the parasternal long-axis view and the apical three-chamber view was measured. RESULTS: Twenty (61 %) of the 33 patients (mean age 74 ±â€¯9 years) were diagnosed with latent LVOTO. Of these, five (25 %) patients were diagnosed after both the Valsalva and sitting maneuver, and 15 (75 %) were diagnosed only after the sitting maneuver. The latent LVOTO group had a significantly smaller angle than the no-LVOTO group between the ventricular septum and the aorta in the parasternal long axis views (107 ±â€¯8° vs. 117 ±â€¯8°, p < 0.01). CONCLUSION: The sitting maneuver is better than the Valsalva maneuver in unveiling latent LVOTO in older, non-HCM patients.

A Cryptic Sex-Linked Locus Revealed by the Elimination of a Master Sex-Determining Locus in Medaka Fish.

AbstractSex chromosomes rapidly turn over in several taxonomic groups. Sex chromosome turnover is generally thought to start with the appearance of a new sex-determining gene on an autosome while an old sex-determining gene still exists, followed by the fixation of the new one. However, we do not know how prevalent the transient state is, where multiple sex-determining loci coexist within natural populations. Here, we removed a Y chromosome with a master male-determining gene DMY from medaka fish using high temperature-induced sex-reversed males. After four generations, the genomic characteristics of a sex chromosome were found on one chromosome, which was an autosome in the original population. Thus, the elimination of a master sex-determining locus can reveal a cryptic locus with a possible sex-determining effect, which can be the seed for sex chromosome turnover. Our results suggest that populations that seem to have a single-locus XY system may have other chromosomal regions with sex-determining effects. In conclusion, the coexistence of multiple sex-determining genes in a natural population may be more prevalent than previously thought. Experimental elimination of a master sex-determining locus may serve as a promising method for finding a locus that can be a protosex chromosome.

Population admixtures in medaka inferred by multiple arbitrary amplicon sequencing.

Cost-effective genotyping can be achieved by sequencing PCR amplicons. Short 3-10 base primers can arbitrarily amplify thousands of loci using only a few primers. To improve the sequencing efficiency of the multiple arbitrary amplicon sequencing (MAAS) approach, we designed new primers and examined their efficiency in sequencing and genotyping. To demonstrate the effectiveness of our method, we applied it to examining the population structure of the small freshwater fish, medaka (Oryzias latipes). We obtained 2987 informative SNVs with no missing genotype calls for 67 individuals from 15 wild populations and three artificial strains. The estimated phylogenic and population genetic structures of the wild populations were consistent with previous studies, corroborating the accuracy of our genotyping method. We also attempted to reconstruct the genetic backgrounds of a commercial orange mutant strain, Himedaka, which has caused a genetic disturbance in wild populations. Our admixture analysis focusing on Himedaka showed that at least two wild populations had genetically been contributed to the nuclear genome of this mutant strain. Our genotyping methods and results will be useful in quantitative assessments of genetic disturbance by this commercially available strain.

Genetic basis for the evolution of pelvic-fin brooding, a new mode of reproduction, in a Sulawesian fish.

Modes of reproduction in animals are diverse, with different modes having evolved independently in multiple lineages across a variety of taxa. However, an understanding of the genomic change driving the transition between different modes of reproduction is limited. Several ricefishes (Adrianichthyidae) on the island of Sulawesi have a unique mode of reproduction called "pelvic-fin brooding," wherein females carry externally fertilized eggs until hatching using their pelvic fins. Phylogenomic analysis demonstrated pelvic-fin brooders to have evolved at least twice in two distant clades of the Adrianichthyidae. We investigated the genetic architecture of the evolution of this unique mode of reproduction. Morphological analyses and laboratory observations revealed that females of pelvic-fin brooders have longer pelvic fins and a deeper abdominal concavity, and that they can carry an egg clutch for longer than nonbrooding adrianichthyids, suggesting that these traits play important roles in this reproductive mode. Quantitative trait locus mapping using a cross between a pelvic-fin brooder Oryzias eversi and a nonbrooding O. dopingdopingensis reveals different traits involved in pelvic-fin brooding to be controlled by different loci on different chromosomes. Genomic analyses of admixture detected no signatures of introgression between two lineages with pelvic-fin brooders, indicating that introgression is unlikely to be responsible for repeated evolution of pelvic-fin brooding. These findings suggest that multiple independent mutations may have contributed to the convergent evolution of this novel mode of reproduction.

Preself-Feeding Medaka Fry Provides a Suitable Screening System for in Vivo Assessment of Thyroid Hormone-Disrupting Potential.

Endocrine-disrupting chemicals are assessed based on their physiological potential and their potential associated adverse effects. However, suitable end points for detection of chemicals that interfere with the thyroid hormone (TH) system have not been established in nonmammals, with the exception of amphibian metamorphosis. The aims of the current study were to develop an in vivo screening system using preself-feeding medaka fry (Oryzias latipes) for the detection of TH-disrupting chemicals and elucidate the underlying molecular mechanism. 17α-Ethinylestradiol (EE2: <100 ng/L) did not induce mRNA expression of estrogen-responsive genes, vitellogenins (vtgs) mRNA. Meanwhile, coexposure with thyroxin (T4) induced an increase of vtg expression. TH-disrupting chemicals (thiourea (TU), perfluorooctanoic acid (PFOA), and tetrabromobisphenol A (TBBPA)) significantly suppressed EE2 (1,000 ng/L)-induced vtg1 expression, while T4 rescued their expression as well as that of thyroid hormone receptor α (tRα) and estrogen receptors (esrs). These results were supported by in silico analysis of the 5'-transcriptional regulatory region of these genes. Furthermore, the esr1 null mutant revealed that EE2-induced vtg1 expression requires mainly esr2a and esr2b in a TH-dependent manner in preself-feeding fry. Application of preself-feeding medaka fry as a screening system might help decipher the in vivo mechanisms of action of TH-disrupting molecules, while providing an alternative to the traditional animal model.

Mesozoic origin and 'out-of-India' radiation of ricefishes (Adrianichthyidae).

The Indian subcontinent has an origin geologically different from Eurasia, but many terrestrial animal and plant species on it have congeneric or sister species in other parts of Asia, especially in the Southeast. This faunal and floral similarity between India and Southeast Asia is explained by either of the two biogeographic scenarios, 'into-India' or 'out-of-India'. Phylogenies based on complete mitochondrial genomes and five nuclear genes were undertaken for ricefishes (Adrianichthyidae) to examine which of these two biogeographic scenarios fits better. We found that Oryzias setnai, the only adrianichthyid distributed in and endemic to the Western Ghats, a mountain range running parallel to the western coast of the Indian subcontinent, is sister to all other adrianichthyids from eastern India and Southeast-East Asia. Divergence time estimates and ancestral area reconstructions reveal that this western Indian species diverged in the late Mesozoic during the northward drift of the Indian subcontinent. These findings indicate that adrianichthyids dispersed eastward 'out-of-India' after the collision of the Indian subcontinent with Eurasia, and subsequently diversified in Southeast-East Asia. A review of geographic distributions of 'out-of-India' taxa reveals that they may have largely fuelled or modified the biodiversity of Eurasia.

Alternative reproductive tactics in male freshwater fish influence the accuracy of species recognition.

Sexual conflict can result in coercive mating. Because males bear low costs of heterospecific mating, coercive males may engage in misdirected mating attempts toward heterospecific females. In contrast, sexual selection through consensual mate choice can cause mate recognition cues among species to diverge, leading to more accurate species recognition. Some species show both coercive mating and mate choice-associated courtship behaviors as male alternative reproductive tactics. We hypothesized that if the selection pressures on each tactic differ, then the accuracy of species recognition would also change depending on the mating tactic adopted. We tested this hypothesis in the guppy (Poecilia reticulata) and mosquitofish (Gambusia affinis) by a series of choice experiments. Poecilia reticulata and G. affinis males both showed imperfect species recognition and directed all components of mating behavior toward heterospecific females. They tended to direct courtship displays more frequently toward conspecific than heterospecific females. With male P. reticulata, however, accurate species recognition disappeared when they attempted coercive copulation: they directed coercions more frequently toward heterospecific females. We also found that heterospecific sexual interaction had little effect on the fecundity of gravid females, which suggests that prepregnancy interactions likely underpin the exclusion of G. affinis by P. reticulata in our region.

Genome editing reveals fitness effects of a gene for sexual dichromatism in Sulawesian fishes.

Sexual selection drives rapid phenotypic diversification of mating traits. However, we know little about the causative genes underlying divergence in sexually selected traits. Here, we investigate the genetic basis of male mating trait diversification in the medaka fishes (genus Oryzias) from Sulawesi, Indonesia. Using linkage mapping, transcriptome analysis, and genome editing, we identify csf1 as a causative gene for red pectoral fins that are unique to male Oryzias woworae. A cis-regulatory mutation enables androgen-induced expression of csf1 in male fins. csf1-knockout males have reduced red coloration and require longer for mating, suggesting that coloration can contribute to male reproductive success. Contrary to expectations, non-red males are more attractive to a predatory fish than are red males. Our results demonstrate that integrating genomics with genome editing enables us to identify causative genes underlying sexually selected traits and provides a new avenue for testing theories of sexual selection.

Variation in Mating Behaviors Between a Tropical and a Temperate Species of Medaka Fishes.

In medaka fishes, the family Adrianichthyidae, tropical species are known to be sexually more dimorphic than temperate species. If this reflects that tropical species are exposed to stronger sexual-selection pressures than temperate species, mating behaviors may also differ between tropical and temperate species. Our mating experiments revealed that males of Oryzias woworae, a tropical species of the family, perform "chasing" another male more frequently than males of O. sakaizumii, a temperate congener, and that male-male "combats" of O. woworae tended to be followed by chasing compared with combats of O. sakaizumii males, indicating that O. woworae males are more aggressive in male-male interactions than O. sakaizumii males. Males of O. woworae also performed "approaching" a female and "mating dance" more frequently than O. sakaizumii males, indicating that O. woworae males are also more active in courting females. Males of O. sakaizumii often omitted "mating dance" in their mating sequences, supporting this view. Moreover, O. woworae females tended to reject male "wrapping", an attempt for fertilization, more frequently than O. sakaizumii females, suggesting that O. woworae females are choosier in mating than O. sakaizumii females. These findings are concordant with the view that O. woworae is exposed to stronger sexual-selection pressures than O. sakaizumii.

Evidence for sympatric speciation in a Wallacean ancient lake.

Sympatric speciation has been demonstrated in few empirical case studies, despite intense searches, because of difficulties in testing the criteria for this mode of speciation. Here, we report a possible case of sympatric speciation in ricefishes of the genus Oryzias on Sulawesi, an island of Wallacea. Three species of Oryzias are known to be endemic to Lake Poso, an ancient tectonic lake in central Sulawesi. Phylogenetic analyses using RAD-seq-derived single nucleotide polymorphisms (SNPs) revealed that these species are monophyletic. We also found that the three species are morphologically distinguishable and clearly separated by population-structure analyses based on the SNPs, suggesting that they are reproductively isolated from each other. A mitochondrial DNA chronogram suggested that their speciation events occurred after formation of the tectonic lake, and existence of a historical allopatric phase was not supported by coalescent-based demographic inference. Demographic inference also suggested introgressive hybridization from an outgroup population. However, differential admixture among the sympatric species was not supported by any statistical tests. These results all concur with criteria necessary to demonstrate sympatric speciation. Ricefishes in this Wallacean lake provide a promising new model system for the study of sympatric speciation.

Phylogenomics reveals habitat-associated body shape divergence in Oryzias woworae species group (Teleostei: Adrianichthyidae).

The Oryzias woworae species group, composed of O. asinua, O. wolasi, and O. woworae, is widely distributed in southeastern Sulawesi, an island in the Indo-Australian Archipelago. Deep-elongated body shape divergence is evident among these three species to the extent that it is used as a species-diagnostic character. These fishes inhabit a variety of habitats, ranging from upper streams to ponds, suggesting that the body shape divergence among the three species may reflect adaptation to local environments. First, our geometric morphometrics among eight local populations of this species group revealed that the three species cannot be separated by body shape and that riverine populations had more elongated bodies and longer caudal parts than lacustrine populations. Second, their phylogenetic relationships did not support the presence of three species; phylogenies using mitochondrial DNA and genomic data obtained from RNA-Seq revealed that the eight populations could not be sorted into three different clades representing three described species. Third, phylogenetic corrections of body shape variations and ancestral state reconstruction of body shapes demonstrated that body shape divergence between riverine and lacustrine populations persisted even if the phylogenies were considered and that body shape evolved rapidly irrespective of phylogeny. Sexual dimorphism in body shape was also evident, but the degree of dimorphism did not significantly differ between riverine and lacustrine populations after phylogenetic corrections, suggesting that sexual selection may not substantially contribute to geographical variations in body shape. Overall, these results indicate that the deep-elongated body shape divergence of the O. woworae species group evolved locally in response to habitat environments, such as water currents, and that a thorough taxonomic reexamination of the O. woworae species group may be necessary.

Genetic Architecture of the Variation in Male-Specific Ossified Processes on the Anal Fins of Japanese Medaka.

Traits involved in reproduction evolve rapidly and show great diversity among closely related species. However, the genetic mechanisms that underlie the diversification of courtship traits are mostly unknown. Japanese medaka fishes (Oryzias latipes) use anal fins to attract females and to grasp females during courtship; the males have longer anal fins with male-specific ossified papillary processes on the fin rays. However, anal fin morphology varies between populations: the southern populations tend to have longer anal fins and more processes than the northern populations. In the present study, we conducted quantitative trait locus (QTL) mapping to investigate the genetic architecture underlying the variation in the number of papillary processes of Japanese medaka fish and compared the QTL with previously identified QTL controlling anal fin length. First, we found that only a few QTL were shared between anal fin length and papillary process number. Second, we found that the numbers of papillary processes on different fin rays often were controlled by different QTL. Finally, we produced another independent cross and found that some QTL were repeatable between the two crosses, whereas others were specific to only one cross. These results suggest that variation in the number of papillary processes is polygenic and controlled by QTL that are distinct from those controlling anal fin length. Thus, different courtship traits in Japanese medaka share a small number of QTL and have the potential for independent evolution.

Female mate preference for longer fins in medaka.

Medaka, Oryzias latipes complex, display sexual dimorphisms in anal- and dorsal-fin lengths that suggest that females may prefer males with longer fins. However, female preference for longer anal and/or dorsal fins has not yet been described for the medaka. One reason that previous studies have not investigated this relationship may be because variations in male fin lengths within a single population are too small to experimentally detect female preference. In this study, we artificially crossed individuals from two wild populations (Aomori and Okinawa) that differed in male anal- and dorsal-fin lengths to increase phenotypic variation. We then tested female mate preference using these hybrid males. The results of the mating experiments and stepwise multiple regression analyses indicate that anal- and/or dorsal-fin lengths of the males contributed to female preference (i.e., males with longer anal and/or dorsal fins were less likely to be rejected by females). Variation in male standard length did not affect female preference. The evolution of female preference for longer fins in the medaka species complex may be explained by the "sexy son" hypothesis or the direct benefit hypothesis.

Ontogenetic stage-specific quantitative trait loci contribute to divergence in developmental trajectories of sexually dimorphic fins between medaka populations.

Sexual dimorphism can evolve when males and females differ in phenotypic optima. Genetic constraints can, however, limit the evolution of sexual dimorphism. One possible constraint is derived from alleles expressed in both sexes. Because males and females share most of their genome, shared alleles with different fitness effects between sexes are faced with intralocus sexual conflict. Another potential constraint is derived from genetic correlations between developmental stages. Sexually dimorphic traits are often favoured at adult stages, but selected against as juvenile, so developmental decoupling of traits between ontogenetic stages may be necessary for the evolution of sexual dimorphism in adults. Resolving intralocus conflicts between sexes and ages is therefore a key to the evolution of age-specific expression of sexual dimorphism. We investigated the genetic architecture of divergence in the ontogeny of sexual dimorphism between two populations of the Japanese medaka (Oryzias latipes) that differ in the magnitude of dimorphism in anal and dorsal fin length. Quantitative trait loci (QTL) mapping revealed that few QTL had consistent effects throughout ontogenetic stages and the majority of QTL change the sizes and directions of effects on fin growth rates during ontogeny. We also found that most QTL were sex-specific, suggesting that intralocus sexual conflict is almost resolved. Our results indicate that sex- and age-specific QTL enable the populations to achieve optimal developmental trajectories of sexually dimorphic traits in response to complex natural and sexual selection.

Supported liquid membrane transport of alkali metal cations by monoazacryptand with a partially fluorinated sidearm and the corresponding monoazacrown ethers.

Monoazacryptand [20.18.18] (1), monoaza-15-crown-5 (2a), and monoaza-18-crown-6 (2b) with a partially fluorinated sidearm were newly prepared and their transport abilities were estimated in a supported liquid membrane containing a mixture of 2- (perfluorohexyl) ethyl alcohol and 2- (perfluorooctyl) ethyl alcohol. In competitive passive transport of K+, Na+, and Li+ under neutral conditions, the K+ selectivity increased in the order: ionophore 2a