We report an entoproct epibiotic on the surface of a sea spider (Pycnogonida). The pycnogonid was identified as sp. (Nymphonidae). The entoproct was colonial, with three zooids, and was identified both morphologically and by a molecular phylogeny as sp. (Barentsiidae). The largest zooid had eight tentacles and was about 0.7 mm long, smaller than for most colonial entoproct species. We determined partial sequences for the 18S rRNA and 28S rRNA genes from the entoproct. In an 18S-based maximum likelihood tree (1507 characters), the entoproct was the sister taxon to .

In ectotherms, body size differences between latitudes resulting from shorter activity periods at higher latitudes may disappear due to higher growth rates. Although such latitudinal variations have been examined for various taxa, only a few studies have examined such variations in Japanese vertebrates. is widely distributed in the northern part of Honshu, Japan, and although their larval period in the wild is shorter at high latitudes, there is no latitudinal variation in the body size of juveniles in the wild. Therefore, larvae may grow faster at high latitudes, and they can grow into juveniles with body sizes similar to those at low latitudes. To examine whether the growth rate of larvae is faster at high latitudes, we reared groups at 15°C and 20°C. We found that the larval period was shorter and the growth rate was greater at high latitudes. Next, we examined whether the body sizes of reared individuals differed between latitudes. We found that the body sizes of metamorphosed juveniles were smaller at high latitudes. Some ectotherms are known to feed more at high latitudes, leading to the disappearance of latitudinal differences in body size between latitudes. In this study, we provided the same amount of food regardless of latitude, which might have caused the differences in body size between latitudes. Our study suggested that the high growth rate at relatively high latitudes can compensate for the short activity period, leading to similar body sizes of juveniles among latitudes.

Most true predators are generalists, and it is difficult to examine their actual diets in the wild. In many cases, the prey that experience a large impact are also not well known. Amphibians are generalist predators that prey mainly on insects, and amphibian species active beginning in spring are considered to prey on food resources other than insects in this season due to the low number of insects. The Japanese red-bellied newt () is a generalist predator widely distributed in Japan and is known to frequently prey on amphibian eggs. Here, we showed that amphibian eggs are a precious food resource for in spring. The total weights of stomach contents were compared among seasons and we found that the total weights of stomach contents in spring were the same as those in summer. Also, we examined whether preys on amphibian eggs instead of insects in spring. The composition of the taxonomic groups in their stomach contents was compared among the seasons, and the indicator groups in their stomach contents were identified in each season. We found that they preyed not only upon insects but also upon amphibian eggs in spring, while they preyed mainly upon insects in summer and autumn. Our results suggest that preys on amphibian eggs to compensate for the shortage of food in spring when the number of insects is low.

Although genome editing techniques have made significant progress, introducing exogenous genes into the genome through knock-in remains a challenge in many organisms. In silkworm , TALEN-mediated knock-in methods have been established. However, difficulties in construction and limitations of the target sequence have hindered the application of these methods. In the present study, we verified several CRISPR/Cas9-mediated knock-in methods to expand the application of gene knock-in techniques and found that the short single-stranded oligodeoxynucleotide (ssODN)-mediated method is the most effective in silkworms. Using ssODN-mediated methods, we established knock-in silkworm strains that harbor an attP sequence, a 50 bp phiC31 integrase recognition site, at either the () or () locus. Additionally, we found that the long ssODN (lsODN)-mediated method successfully introduced the GAL4 gene at the locus in embryos. The present study provides valuable information on CRISPR/Cas9-mediated knock-in methods in silkworms, expanding the utility of genome editing techniques in insects and paving the way for analyzing gene and genome function in silkworms.

Sexual differences are commonly described as male-biased sexual dimorphism, female-biased dimorphism, and monomorphism. Nevertheless, detailed patterns of sexual dimorphism have only been explored in a few rodent species. We used geometric morphometrics to investigate patterns of sexual dimorphism, static allometry, and modularity in the skull of the Ethiopian white-footed mouse (). Procrustes analysis of variance showed nonsignificant sexual dimorphism for the size and shape of the cranium. Significant sexual differences were detected in the mandibular size but not in the mandibular shape. Discriminant analysis indicated nonsignificant differences between sexes in the Procrustes distance of the cranium and mandible. Additionally, scatter allometric plots demonstrated similar patterns of allometry in both sexes. Allometric variation showed an elongation of the rostrum, widening of the zygomatic bones, and narrowing of the braincase. We also observed an expanding of the ascending ramus and shortening of the alveolar part for the mandible. These may indicate the existence of modularity in the skull, which was supported by modularity analysis. Although these trends have been thought to be a growth-related phenomenon of the mammalian skull, functional requirements may also have an effect. In conclusion, our results indicate sexual monomorphism in the skull of , which may have no effect on allometric variation and modularity patterns.

"," "", and are Red-Listed snail species of the family Ellobiidae that co-occur on salt marshes in mainland Japan. Here, we report the genetic diversity and population structures of the former two taxa in comparison with our previous data on for the evaluation of connectivity and conservation values of their local populations. Analyses of 655-bp or 652-bp sequences of the mitochondrial cytochrome oxidase subunit I gene showed the highest genetic diversity and panmictic structure for sp. cf. throughout its geographic range in Japan, whereas they showed the highest level of genetic subdivision for sp. cf. . Our laboratory observation of egg masses and planktotrophic larvae of "" and reference to previous ontogenetic data for the species of suggested differences in their fecundity and pelagic larval duration, which apparently have led to the contrasting levels of population differentiation in the study species. Particular need of conservation efforts was identified for the isolated population of "" in the Ise-Mikawa Bay area to avoid local extinction and shrinking of the species' geographic range. In addition, we present molecular and morphological evidence that individuals of "" from mangrove swamps in the northern part of Okinawa Island represent an independent, surviving lineage of a different species.

Due to limited spawning seasons, embryogenesis of corals has not fully been studied and the embryonic origin of gastrodermis remains uncertain in . We herein examined how embryonic endodermal cells develop into the gastrodermis and mesentery of polyps in . In juvenile polyps, the gastrodermis invaginates to form mesenteries, both of which were stained with rhodamine-phalloidin, an anti-myocyte-specific enhancer factor 2 (anti-AtMef2) antibody, and an anti-lipoxygenase homology domain-containing protein 1 (anti-AtLoxhd1) antibody. Rhoda-mine-phalloidin staining was traced back to the endodermal cells of 60-85 hpf 'pear'-stage embryos through the larval stage. AtMef2 appeared in the blastomeres of a 12-hpf 'prawnchip'-stage embryo that was a variant U-shaped blastula with a narrow blastocoel. AtMef2 temporarily disappeared from the nuclei of 28-hpf 'donut'-stage embryos and reappeared in the endodermal cells of 40-hpf early 'pear'-stage embryos, suggesting a transition from maternal to zygotic expression of Mef2. The blastopore closed without the invagination of blastomeres. The gastrocoel collapsed and the Mef2-positive endoderm was dissociated into single cells in the well-developed blastocoel filled with yolk cells. The mesoglea appeared in the yolk cell layer. AtLoxhd1 was traced back to the endodermal cells of 'pear'-stage embryos. In 11-dpf larvae, Loxhd1-positive endodermal cells elongated in the vicinity of the mesoglea to adhere to each other and form the gastroderm epithelium in larvae. Therefore, in this coral, the inner wall of U-shaped early embryos is the cellular origin of the gastrodermis. Inner wall-derived endodermal cells move independently toward the mesoglea, where cell-cell adhesion occurs to establish the gastrodermis.

Planktonic larvae of sessile metazoans select substrates for settlement based on various factors. larvae (Ascidiacea: Phlebobranchia: Ascidiidae) showed a negative preference for nano-scale nipple arrays (dense arrays of papillae-like nanostructures approximately 100 nm in height). To clarify whether ascidian larvae discriminate between nano-structure sizes for substrate selection, three different sizes of periodic nano-folds were fabricated using two-beam interference exposure, and substrate selection assays were performed on the three types of nano-folds and flat surfaces made of the same material. The substrate selection assay with 500-2000 freshly hatched larvae was carried out in nine replicates. The ascidian larvae showed a positive preference for flat surfaces and a negative preference for substrates with a height of 120 nm and pitch of 600 nm. Manly's selection indices differed with the size of the periodic nano-folds, supporting the hypothesis that larvae directly or indirectly discriminate between nano-scale differences upon settlement. The present study is the first to show that differences in nanostructure size affect substrate selection during larval settlement of sessile animals. The evolutionary adaptive reasons for larvae to discriminate between nano-scale structures and select substrates for settlement are potentially important to effectively manage ascidian biofouling using non-toxic methods.

The chestnut tiger butterfly, , can undertake long-distance migrations. They flap their wings for power flight and hold the wings for gliding; such repertoires of wing movements may be the key to explaining their excellent flight abilities. Measuring flight muscle activity using the electromyogram (EMG) is the first step toward understanding the neuromuscular mechanism of active flight control. Free-flight EMG measurements have, however, not been reported in butterflies. This study developed a method to acquire two-channel EMGs from free-flying . Stable EMG recordings were acquired using a monopolar electrode by attaching a small pre-amplifier to the dorsal mesonotum. The common-mode noise between channels was resolved by inserting a reference electrode into the mesonotum midline. The EMGs of five flight muscles were measured during free-flight and their activation phases were analyzed. The EMGs of all five muscles demonstrated a burst of spikes per stroke cycle, in contrast to the few spikes per cycle in the EMGs of hawkmoths, which would reflect the differences in wing kinematics and flight abilities. Further analyses, combining the technique developed in this study with high-speed videography, will clarify the neuromuscular mechanisms underlying the flight ability of .

Recent studies have suggested that, in some bird species, predator-elicited vocalizations of males may function as an advertisement to conspecific females, but the evidence remains scarce. Male Japanese bush warblers, , are known for producing long, conspicuous songs (continuous songs), in response to both predators and conspecific females. In this work, I investigated the temporal and spatial associations of continuous songs with the presence of females. In seven surveys throughout a breeding season, male singing activity of continuous songs was low before females arrived at the breeding ground but increased thereafter. Singing activity was higher in territories where the presence of females was confirmed than in those where it was not. Over multiple days, I observed a single male from sunrise to sunset and observed that the locations where the male sang continuous songs were concentrated at the locations where the females were observed. These temporal and spatial associations of the continuous song with the presence of conspecific females support the hypothesis that the continuous song is an advertisement to females. Additional observations showed that females did not fly away or enter the bushes in response to the continuous songs as they did when they encountered danger, and that the male sang continuous songs even towards females that were not considered their mating partner. These findings are inconsistent with the hypothesis that the continuous song is an alarm to alert their mates of danger. This study shows the possibility that male Japanese bush warblers advertise their quality to potential mates by singing continuous songs under dangerous situations.

Extreme temperatures are a major threat to the survival of ectotherms such as amphibians. The tree frogs belonging to the genus have accomplished a latitudinal distribution and a wide range of thermal adaptations. In particular, , referred to as the "hot spring frog", has been reported to tolerate extremely high temperatures. However, it is unclear how the heat tolerance and metamorphic strategies of this species vary among populations at different temperatures. We therefore conducted long-term heat tolerance experiments on multiple populations of tadpoles and their congenic species to determine their survivability and development speed. We observed heat tolerance differences between and exhibited the highest tolerance among all species, and the Seranma hot spring population showed the highest survival rate and accelerated development speed. However, at temperatures higher than 35°C, they could not survive until the completion of metamorphosis, contrary to previous field observations. Our behavioral experiment showed attenuation of the high temperature preference of tadpoles associated with developmental stages, suggesting that they can tolerate extreme temperatures for a limited time window during their development until metamorphosis.

Pigment-based coloration is prevalent in animals, but its expression greatly varies across species, populations, and even among individuals in the same populations. Some animals are highly pigmented and thus have conspicuous coloration, whereas others are modestly pigmented and thus have drab coloration. A possible explanation for the variety in pigmentation is a resource-based tradeoff, in which resources invested in pigmentation are unavailable for other functional traits, and thus animals that need to invest in the latter have limited resources to invest in pigmentation. Resource-based tradeoff is plausible in theory, but direct tests are scarce, partially because of many components of pigment-based coloration (i.e., multiple pigments, integument microstructure, and stains) that affect coloration, preventing the use of coloration as an index of pigmentation. Here, using the barn swallow, , we examined the relationship between pheomelanin pigmentation in reddish throat patch (a precopulatory sexual trait) and total sperm length (a postcopulatory sexual trait), with particular attention to glutathione as the common resource. We predicted that pheomelanin, which is the predominant pigment in the reddish throat patch, should be negatively related to total sperm length, and that both sexual traits should be further negatively related to the amount of glutathione. As predicted, we found a negative relationship between pheomelanin pigmentation and total sperm length. However, the amount of glutathione in the blood showed no detectable relationship to them. The tradeoff between pheomelanin pigmentation and sperm size, as inferred from the current and previous results, might not be a simple glutathione-based tradeoff.

The TGF-β signaling pathway plays an important role in wound healing and immune response. In this study, a TGF-β type I receptor (TGF-βRI) homolog was cloned and characterized from freshwater mussel . The full-length cDNA of the gene was 2017 bp, with a 1554 bp open reading frame (ORF), and encoded 517 amino acids. The predictive analysis further identified distinct regions within the TGF-βRI protein: a signal peptide, a membrane outer region, a transmembrane region, and an intracellular region. Real-time quantitative PCR results showed that the gene was expressed in all tissues of healthy mussels. The transcripts of in hemocytes and hepatopancreas were significantly up-regulated at different periods after stimulation with and peptidoglycan (PGN) ( < 0.05). The mRNA expression of progressively increased from day 1 to day 10 after trauma ( < 0.05), and it returned to the initial level by day 15. The expression levels of , , , , but not , were significantly up-regulated at different time points after trauma. However, the expression levels of , , and were decreased after treatment with the inhibitor SB431542. Furthermore, the recombinant TGF-βRI proteins were expressed in vitro and existed in the form of inclusion bodies. Western blotting results showed that TGF-βRI proteins were expressed constitutively in various tissues of mussels, and their expression was up-regulated after trauma, which was consistent with the mRNA expression trend. These results indicate that is involved in the process of wound repair and immune response.

Left-right asymmetry in paired organs is well documented across various species, including the claws of fiddler crabs and snail-eating snakes' dentition. However, the mechanisms underlying these asymmetries remain largely elusive. This study investigates (Coleoptera: Erotylidae), a lizard beetle species known for pronounced left-sided asymmetry in adult female mandible and gena. Given that insect mouthparts comprise multiple functionally significant appendages, we aimed to clarify the degree of asymmetry extending beyond the mandibles and genae. Phenotypic morphology was assessed through trait measurement and asymmetry index calculations. Our detailed morphometric analyses revealed left-longer asymmetry not only in mandibles and genae but also in maxillae and labium. Notably, the degree of asymmetry in other mouthparts was generally less pronounced compared to that in outer mandibles, suggesting a potential influence of left mandible development on other mouthparts. Additionally, male mandibles exhibited region-specific asymmetry, potentially indicative of constrained evolutionary adaptations. This study enhances a comprehensive understanding of adult phenotype morphology and offers insights into the developmental basis of asymmetrical mouthparts.

We investigated geographic, genetic, and morphological variations in the intertidal limpet , a species with a broad distribution across Japan. A total of 98 specimens were obtained from 36 locations spanning the entire Japanese Archipelago, encompassing both the northern and southern regions. Examination of mitochondrial COI sequences revealed a distinct geographic genetic structure, delineating three prominent clades: (1) the Kuroshio Current, (2) the Tsushima Current, and (3) the Ryukyu-China groups. The observed geographical structuring between the Pacific and Sea of Japan side mirror patterns was noted in previously studied species, such as and . Within , the Kuroshio Current group exhibited a substantial genetic distance, reaching a maximum of 12.35%, when compared to the more closely linked Tsushima Current and Ryukyu-China groups. Compared to other groups, the Ryukyu and China groups represented relatively recent differentiations, and the former group is currently facing a heightened risk of extinction owing to its sparse population density. The emergence of intraspecific geographic structures is likely attributable to the comparatively brief planktonic larval stage, which is a common characteristic of patellogastropod limpets.

Microfocus X-ray computed tomography (micro-CT) is expected to be utilized in the taxonomy of macroturbellarians that require histological technique(s) for identification, allowing nondestructive observation of the internal structures of specimens in a short time. With micro-CT, we observed a polyclad flatworm, (Schmarda, 1859), in this study. In the CT images, the main reproductive organs in the polyclad specimen were well observed, but some diagnostic characters were unclear or undetectable. We also prepared histological sections from the CT-scanned specimen. The histological sections were still observable and we could confirm the structures that were indistinct in the CT images; however, dye-affinity of tissues was slightly altered compared with those in usual sections. Integrating information from micro-CT images and subsequent histological observations, we successfully generated a 3D model of the reproductive organs of the polyclad. Our results suggest that the micro-CT imaging, as of the current resolution, would not completely replace the traditional histological technique; instead, these two techniques need to complement each other for a better understanding of the morphology that underpins the polyclad systematics.

Most tortoise beetles, belonging to the subfamily Cassidinae (Coleoptera: Chrysomelidae), possess distinctive explanate margins, comprising elongations of the pronotum and elytra outer margins. These margins flatten against the ground, serving as a unique defensive mechanism against predators. To understand the developmental and evolutionary origins of explanate margins, we examined the development of the pronotal part of these structures in two tortoise beetle species: (Boheman) (tribe Cassidini) and (Boheman) (tribe Aspidimorphini). Although final (fifth) instar larvae of both species exhibited no external prothoracic structures associated with explanate margins, pupae possessed a plate-shaped structure projecting anterolaterally on their pronotum. This plate-shaped structure was identified as the pupal primordium of the pronotal explanate margin, as the explanate margin emerged from inside the structure during eclosion. In prepupae of , the primordial tissue exhibited three region-specific folding and furrowing patterns, beneath larval cuticles. These epithelial structures expanded within minutes at the onset of pupation, resulting in pupal primordial formation. Thus, pronotal explanate margins originate from pronotal epithelia, with the furrowing and folding patterns of the epithelia shaping pupal and even adult pronotal explanate margins. The presence of morphologically similar pupal pronotal projections in various Cassidinae suggests that the development of pronotal explanate margins is likely common in these beetles.

We identified two gall-inducing wasp species infesting eucalypts leaves, including an undescribed species, sp. nov., and , which is a new record for Taiwan. The major hosts of were , , and (Myrtaceae) We observed failed galls of at an early stage on and . All adults discovered on infected leaves were females, and four parasitoid species were identified in samples collected from two cities, three counties, and four municipalities across Taiwan. was exclusively found on in Hsinchu, Nantou, and Tainan Cities. This marks the first record of in Asia, accompanied by the identification of one parasitoid species. The adult longevity of adults which emerged from their major hosts, when provided with honey-water solution, was 5.5 days for and 5.7 days for . Recognizing the potential damage by these wasps on production areas in the absence of parasitoids, further investigations of their biology and control are warranted.

In holometabolous insects, the larval body is almost completely decomposed and reconstructed into the adult body during the pupal-pharate adult stages. Therefore, the total energetic cost of this process is a key thermodynamic quantity necessary for evaluating the benefit of their life history. Here, we measured whole-body thermal dissipation of single pupae of the fruit fly, , during the period from puparium formation to adult eclosion as a function of age, using a high-precision isothermal calorimeter at = 298 K. The mass-specific energy consumption during the period from the onset of larval-pupal apolysis to adult eclosion was determined to be 2.3 kJ/g for an individual of (adult) = 1.0 mg, while it was observed to follow Kleiber's law for individuals smaller than (adult) = 1.0 mg. During the pupal-pharate adult period, in addition to the U-shaped variation, several characteristic thermal dissipations related to various events, including somatic muscle contractions, ecdyses, pulsatile hormone secretion in a pharate adult, and vaporization of the exuvial fluid, were observed. The periodic bursts in the pharate adult stage grew exponentially, suggesting that the positive feedback in the metabolic system synchronized with the progression of development, making the energy consumption in this stage more efficient. The present study showed that high-precision calorimetry is a powerful and credible method for measuring not only the total energy spent during development but also the energy spent during every specific developmental event in an organism.

Some anguillid eels migrate thousands of kilometers from their spawning grounds, dispersing across vast geographic areas to fresh and brackish water habitats, where they settle and grow. Japanese eels () and giant mottled eels () are both found in Japan, although their distributions differ, and their exact distributions are poorly known. We assumed that topographic distribution patterns of Japanese and giant mottled eels must differ among and within rivers along the northwest coast of Kyushu, Japan. Environmental DNA (eDNA) analysis was conducted at 87 sites in 23 rivers. Japanese eel eDNA was detected in 19 rivers (82.6%) and that of giant mottled eels was detected in eight (34.8%). We detected giant mottled eel eDNA in five rivers where they were previously unknown. eDNA for Japanese eels was detected at six of nine sites in the north (66.7%), 13 of 23 sites in Omura (56.5%), and 37 of 55 sites in the south (67.3%). In contrast, giant mottled eel eDNA was detected at one of nine sites in the north (11.1%), no sites in Omura, and 15 of 55 sites in the south (27.3%). There was no correlation between eDNA concentrations of the two species at 10 sites in the five rivers where eDNA of both species was detected. These findings suggest differences in the distribution of the two eel species and the northern distributional limit of giant mottled eels in the area facing the East China Sea.

The circadian system comprises multiple clocks, including central and peripheral clocks. The central clock generally governs peripheral clocks to synchronize circadian rhythms throughout the animal body. However, whether the peripheral clock influences the central clock is unclear. This issue can be addressed through a system comprising a peripheral clock (compound eye clock [CE clock]) and central clock (the optic lobe [OL] clock) in the cricket . We previously found that the compound eye regulates the free-running period () and the stability of locomotor rhythms driven by the OL clock, as measured by the daily deviation of °C. However, the role of the CE clock in this regulation remains unexplored. In this study, we investigated the importance of the CE clock in this regulation using RNA interference (RNAi) of the () gene localized to the compound eye (). The abolished the compound eye rhythms of the electroretinogram (ERG) amplitude and clock gene expression but the locomotor rhythm driven by the OL clock was maintained. The locomotor rhythm of the tested crickets showed a significantly longer and greater daily variation of than those of control crickets treated with ds. The variation of was comparable with that of crickets with the optic nerve severed. The was considerably longer but was comparable with that of crickets with the optic nerve severed. These results suggest that the CE clock regulates the OL clock to maintain and stabilize .