It is generally accepted that ancient fishes first experienced freshwater (FW), and then variably by lineage moved onto the land or re-entered the seas during evolution. As both land and sea are desiccating environments, animals must change their strategies for body fluid regulation from protecting against overhydration in FW to coping with dehydration in seawater (SW) or on land. The evolution of the mechanisms for acquisition of water surely must have accompanied these dramatic environmental changes. The major route for water acquisition is by oral drinking in terrestrial tetrapods (represented here by mammals) and in SW fishes (represented by teleosts as they are dehydrated in SW), but the regulation is contrasting between the two groups; mechanisms inducing thirst have developed in mammals, whereas inhibitory mechanisms are dominant in marine teleosts as observed in FW teleosts. Thus, the apparent difference was found not between hydrating and dehydrating habitat, but rather between terrestrial and aquatic habitats. This contrast is also reflected in regulatory hormones; dipsogenic hormones such as angiotensin II play pivotal roles in water homeostasis in mammals, whereas antidipsogenic hormones such as atrial natriuretic peptide are essential in teleosts. Imbibed water becomes body fluid only after absorption by the intestine, and there is a distinct difference in the mechanisms for water absorption between mammals and teleosts. Like regulation of drinking, we found that the inhibitory mechanisms are dominant for intestinal water absorption in teleosts. In the initial part of this short review, interesting differences in the body fluid regulation between mammals and teleosts are introduced, particularly with regard to water acquisition (drinking and intestinal absorption). Then an attempt was made to discuss the evolution of the mechanisms from the two perspectives; transitions from aquatic to terrestrial habitats and from hydrating (FW) to dehydrating (land and SW) habitats.

This review presents the principal methods used in taxonomic studies of rumen ciliates: live observation, Lugol staining, fixation and staining with methyl-green formalin saline (MFS) solution, protargol staining, silver carbonate impregnation, scanning electron microscopy and molecular techniques. Mastering these techniques is essential for successful research on the taxonomy of rumen ciliates. No single technique reveals all of the characteristics required for a complete description of a rumen ciliate; therefore, it is necessary to combine the use of these techniques as appropriate to the rumen ciliate group under study. Tables are provided to summarize: 1) morphological methods more appropriate for revealing morphological structures of interest, 2) morphological methods indicated for each group of rumen ciliates, and 3) main primers used for PCR amplification of the 18S rDNA of rumen ciliates.

For species in which mating is resource-independent and offspring do not receive parental care, theoretical models of age-based female mate preference predict that females should prefer to mate with older males as they have demonstrated ability to survive. Thus, females should obtain a fitness benefit from mating with older males. However, male aging is often associated with reductions in quantity of sperm. The adaptive significance of age-based mate choice is therefore unclear. Various hypotheses have made conflicting predictions concerning this issue, because published studies have not investigated the effect of age on accessory gland proteins and sperm traits. D. melanogaster exhibits resource-independent mating, and offspring do not receive parental care, making this an appropriate model for studying age-based mate choice. In the present study, we found that D. melanogaster females of all ages preferred to mate with the younger of two competing males. Young males performed significantly greater courtship attempts and females showed least rejection for the same than middle-aged and old males. Young males had small accessory glands that contained very few main cells that were larger than average. Nevertheless, compared with middle-aged or old males, the young males transferred greater quantities of accessory gland proteins and sperm to mated females. As a result, females that mated with young male produced more eggs and progeny than those that mated with older males. Furthermore, mating with young male reduced female's lifespan. These studies indicate that quantity of accessory gland proteins and sperm traits decreased with male age and females obtain direct fitness benefit from mating with preferred young males.

To obtain a comprehensive picture of microtubule dynamics during conjugation, the mode of sexual reproduction in ciliates, we combined indirect immunofluorescence and three-dimensional imaging using confocal laser-scanning microscope to visualize the cellular localization of DNA, microtubules, and γ-tubulin, the main component of the microtubule-organizing center in mating Tetrahymena cells. As the conjugational stages proceeded, the distribution of γ-tubulin changed drastically and microtubules showed dynamic appearance and disappearance during meiosis, nuclear selection, nuclear exchange, and the development of new macronuclei. This study highlights the involvement of cytoskeletal regulation in the modulation of germline nuclear motilities required for ciliate reproduction.

Hedgehog is a toolkit gene conserved in metazoans. However, its function differs among taxa, and it shows versatile expression patterns in morphogenesis. We analyzed the expression pattern of hedgehog in the indirect development of the hemichordate, Ptychodera flava, during development and regeneration. Pf-Hh showed distinct enteropneust-specific expression at the anterior tip of the larvae, as well as deuterostome-conserved expression in the pharyngeal endoderm. In contrast, the gene is expressed only in the pharyngeal region during anterior regeneration, but not in the anterior tip of the proboscis. These data suggest that anterior regeneration is driven not only by conserved developmental mechanisms, but also by some regeneration-specific mechanism(s).

Butterfly wing color patterns are highly complex and diverse, but they are believed to be derived from the nymphalid groundplan, which is composed of several color pattern systems. Among these pattern systems, the marginal band system, including marginal and submarginal bands, has rarely been studied. Here, we examined the color pattern diversity of the marginal band system among nymphalid butterflies. Marginal and submarginal bands are usually expressed as a pair of linear bands aligned with the wing margin. However, a submarginal band can be expressed as a broken band, an elongated oval, or a single dot. The marginal focus, usually a white dot at the middle of a wing compartment along the wing edge, corresponds to the pupal edge spot, one of the pupal cuticle spots that signify the locations of color pattern organizing centers. A marginal band can be expressed as a semicircle, an elongated oval, or a pair of eyespot-like structures, which suggest the organizing activity of the marginal focus. Physical damage at the pupal edge spot leads to distal dislocation of the submarginal band in Junonia almana and in Vanessa indica, suggesting that the marginal focus functions as an organizing center for the marginal band system. Taken together, we conclude that the marginal band system is developmentally equivalent to other symmetry systems. Additionally, the marginal band is likely a core element and the submarginal band a paracore element of the marginal band system, and both bands are primarily specified by the marginal focus organizing center.

DNA analysis can reveal the origins and dispersal patterns of invasive species. The green anole Anolis carolinensis is one such alien animal, which has been dispersed widely by humans from its native North America to many Pacific Ocean islands. In the Ogasawara (Bonin) Islands, this anole was recorded from Chichi-jima at the end of the 1960s, and then from Haha-jima in the early 1980s. These two islands are inhabited. In 2013, it was also found on the uninhabited Ani-jima, close to Chichi-jima. Humans are thought to have introduced the anole to Haha-jima, while the mode of introduction to Ani-jima is unknown. To clarify its dispersal patterns within and among these three islands, we assessed the fine-scale population genetic structure using five microsatellite loci. The results show a homogeneous genetic structure within islands, but different genetic structures among islands, suggesting that limited gene flow occurs between islands. The recently established Ani-jima population may have originated from several individuals simultaneously, or by repeated immigration from Chichi-jima. We must consider frequent incursions among these islands to control these invasive lizard populations and prevent their negative impact on native biodiversity.

We investigated mating pair formation between three Blepharisma species Blepharisma undulans, Blepharisma japonicum, and Blepharisma stoltei to determine whether their respective gamones (mating pheromones) effectively induce mating pairs between different species. Cell-free fluid from type II cells (CFF2) of B. undulans (megakaryotype II) induced pairing of B. japonicum and B. stoltei type I cells (megakaryotype IV), and CFF2 of B. japonicum and B. stoltei induced pairing of B. undulans type I cells. Cell-free fluid from B. undulans type I cells (CFF1) did not induce pairing of B. japonicum and B. stoltei type II cells, and CFF1 of B. japonicum and B. stoltei failed to induce pairing of B. undulans. CFF1 from B. japonicum and B. stoltei mutually induced pairing, as previously reported. These results indicate that gamone 2 is common among megakaryotypes II and IV, and that gamone 1 appears to be at least megakaryotype-specific. When cells belonging to megakaryotypes II and IV are separately pre-treated with effective gamones and mixed, mating pairs between megakaryotypes rarely form. Taken together, these results suggest at least two barriers, a gamone and a factor involved in pair formation, that prevent conjugation between different megakaryotypes of Blepharisma.

Among beetles, thousands of species develop horns, the size of which is often extraordinarily disproportionate with respect to body size. The Scarabaeidae is the family in which horned species are most predominant, but other families, such as the Geotrupidae (dor beetles), also show remarkable horns, although in a more limited number of species. Horn expression mechanisms are well documented in Scarabaeidae but, despite the wealth of studies on this family, the horn morphological pattern of the Geotrupidae, to our knowledge, has never been investigated. In this paper, we describe for the first time the horn expression pattern in a dor beetle. As a study species, we chose Ceratophyus rossii, an Italian endemic dor beetle of the protected Mediterranean maquis in Tuscany, which shows remarkable head and pronotal horns in males and a notable cephalic horn in females. We identified and modeled shape and size horn patterns combining traditional and geometric morphometric approaches. We discuss the results in the wider landscape of developmental models described for other, more well-characterized, scarab beetles.

The intensity of environmental factors differs in natural habitats and could shape the response of an animal that is able to assess a factor's gradient. However, intensity-dependent response to environmental factors has been only occasionally reported in animals. In laboratory experiments, I studied changes in sexual induction in response to a series of temperature decreases in different clones of Hydra oligactis. The percentage of sexually-induced clone-mates was related to the temperature gradient intensity. This intensity-dependent response was observed independently of the H. oligactis clone and gender. The magnitude of the response differed significantly between the clones originated from the distinct sites. The possible significance of the intensity-dependent response in the Hydra clones is discussed in evolutionary terms.

This study reviews the data available on the distribution of three-banded armadillos of the genus Tolypeutes, identifying potential geographic barriers and evaluating possible biogeographic processes that may account for the present-day distribution of the species and its conservation status. The database was derived from published records, interviews, and voucher specimens, over a timescale ranging from the fossil record to specimens collected in 2013. A total of 236 localities were recorded, with 68 attributed to Tolypeutes matacus and 168 to Tolypeutes tricinctus. The vegetation within the range of the genus is predominantly a xerophytic mosaic of grassland, savannas, open woodland, and xeric thorn forest. The marine transgressions of the Miocene and the uplifting of the Brazilian Shield may have contributed to the vicariant separation of the ancestral populations of T. matacus, to the west and south, and T. tricinctus, to the north and east. The three-banded armadillo is possibly one of the most threatened of Brazilian mammals, considering the low number of recent records and the fact that it is hunted intensively throughout its range.

In mammalian liver development, intrahepatic biliary morphogenesis takes place in periportal, but not in pericentral, regions. Liver progenitor cells transiently form epithelial plate structures and then intrahepatic bile ducts around the portal veins under the influence of the mesenchyme. The present study was undertaken to histochemically examine normal biliary development and its dependence on the action of the thyroid hormone triiodothyronine (T3) in Xenopus laevis tadpoles. In these tadpoles, the development of hepatic ducts and intrahepatic biliary ducts commenced along the portal veins at NF stages 48–50 and stages 50–52, respectively, when the blood concentration of thyroid hormone may be still low. Some periportal hepatocytes expressed carbamoylphosphate synthase I and SOX9, which are hepatocyte and biliary cell markers, respectively, suggesting that periportal hepatocytes give rise to biliary epithelial cells. Periportal biliary cells did not form ductal plates, nor was the periportal mesenchyme well developed as seen in fetal mouse livers. jag1 mRNA was moderately expressed in cells of portal veins and biliary epithelial cells, and notch1 and notch2 mRNAs were weakly detectable in biliary epithelial cells during metamorphosis as seen in developing mammalian livers. These results suggest that Notch signaling plays a decisive role in biliary cell differentiation and morphogenesis of Xenopus tadpoles. Anti-thyroid agent treatment of the tadpoles resulted in delayed biliary morphogenesis, suggesting that biliary development may depend on T3. However, T3 treatment of the tadpoles did not enhance biliary development. Thus, T3 may act positively on biliary development at a very low concentration.

Sapajus apella is a wild monkey of South America distributed across almost all of Brazil. This species adapts to domesticated life and reproduces easily. The present study describes the macro- and microscopic morphology of male genital organs (penis, penis bone, glans penis, prepuce, bulb of penis, and urethra) of Sapajus apella. Four male monkeys were used in this study. For macroscopic description, the genitals were dissected, examined and photographed. For microscopic analysis, samples were stained by HE and Tricom Masson and analyzed by scanning electron microscopy and light microscopy. The penis has a gutter shape with numerous spines on the free part of the penis and glans, and showed cavernous body elements in which mesenchymal cells appear. The glans penis is well developed with a broad crown shape. The prepuce does not cover the free part of the penis. The bulb displays well-developed muscle structure and the membranous urethra is very elongated. These results reveal that Sapajus apella shows specific male genital features, different from other primates.

We conducted phylogenetic analyses using mitochondrial COI gene sequences of Tylos granuliferus, a semiterrestrial coastal isopod in East Asia, to clarify possible phylogeographic patterns and to assess relationships between present and past marine environments and genetic population structures. Our results strongly suggest the presence of four clades of T. granuliferus, one of which consists of three subclades. The distribution pattern of clades and subclades seems to have been affected by ocean current activities. Our results also suggest that historical changes in oceanic environments and the subsequence bifurcation of current streamlines affected the first and second divergences of T. granuliferus during the late Miocene and near the beginning of the Pliocene, respectively.

This study reports a viable means of identifying the vitellogenic cycle and limited estrus period in hawksbill turtles for the purposes of developing captive breeding program, based on the combination of blood metabolite parameters (triglyceride, total protein, and calcium levels), feeding status, and ovary condition. Follicle size of two focal captive females showed clear seasonal changes, with major development occurring between March and May (19.0–24.4 mm), and exceeding 25 mm between June and September. Triglyceride, total protein, and calcium levels dropped with follicular development and maintenance (March to October), and then began to rise when follicular retraction occurred from October onwards. The two focal turtles reduced food intake during intensive follicular development (April to May). These findings suggest that blood metabolite parameters and feeding conditions are inferred by the vitellogenic cycle. An additional 10 females exhibiting follicular development were mated with a single male for 7-day period between May and June. Follicle size was measured immediately prior to pairing, and a statistically significant difference in follicle size of 10 females was recorded between the seven failed (20.9 mm) and three successful (23.6 mm) mating events. This indicates follicle development is essential to successful mate and monitoring of vitellogenic cycle may help improve the success rates of captive hawksbill breeding programs.