Chordata

FGFs act in vertebrate mesoderm induction and also play key roles in early mesoderm formation in ascidians and amphioxus. However, in sea urchins initial characterizations of FGF function do not support a role in early mesoderm induction, making the ancestral roles of FGF signaling and mechanisms of mesoderm specification in deuterostomes unclear. In order to better characterize the evolution of mesoderm formation, we have examined the role of FGF signaling during mesoderm development in Saccoglossus kowalevskii, an experimentally tractable representative of hemichordates. We report the expression of an FGF ligand, fgf8/17/18, in ectoderm overlying sites of mesoderm specification within the archenteron endomesoderm. Embryological experiments demonstrate that mesoderm induction in the archenteron requires contact with ectoderm, and loss-of-function experiments indicate that both FGF ligand and receptor are necessary for mesoderm specification. fgf8/17/18 gain-of-function experiments ...

Devario comprises 38 potentially valid species in southern Asia. Ten species of Devario have been reported so far from Myanmar, six of which belong in the group of striped devarios, with predominantly horizontal stripes in the colour pattern. Among them, records of D. aequipinnatus most likely represent misidentifications. Remaining species of striped devarios in Myanmar are known only from brief descriptions and are in need of taxonomic revision. Devario yuensis and D. deruptotalea, known previously only from India, are here reported for the first time from Myanmar. Devario fangae, new species, is described on the basis of specimens collected in 1998 from small streams in Putao in the extreme north of Myanmar. These streams drain to the Mali Hka River, a tributary of the Ayeyarwaddy River. Devario fangae shares uniquely with D. browni and D. kakhienensis an anterior expansion in width of the middle dark stripe on the side (P stripe). It differs from D. browni and D. kakhienensis in...

Coprological examinations of eight Ruppell’s agamas Agama rueppelli (Vaillant) revealed the presence of a coccidium of the genus Isospora Schneider, 1881 that represents a previously undescribed species. Oöcysts of Isospora farahi n. sp. are spherical or subspherical, 29.1 (26–31) × 28.8 (26–31) μm, with a shape-index of 1.01 (1–1.07). An oöcyst residuum, polar granules and micropyle are absent. The oöcyst wall is bilayered, brownish and smooth, c. 1.5–2 μm thick. The sporocysts are oval, 16.6 (15–18) × 11.4 (11–12) μm, with a shape-index of 1.46 (1.25–1.64) and both Stieda and substieda bodies. A sporocyst residuum is present as medium-sized granules scattered irregularly among the sporozoites. The sporozoites are vermiform, with a large posterior spherical refractile body. Endogenous development is intranuclear in the epithelial cells of the small intestine. Sporulation is unknown, as oöcysts were recovered from the faeces.

This study aimed at analysing concentrations of heavy metals including arsenic, lead, cadmium, aluminium and mercury in commonly consumed seafood species belonging to Echinodermata (Anthocidaris crassispina and Stichopus japonicus) and Chordata (Halocynthia roretzi and Styela plicata). The samples were digested by a microwave system and analysed for As, Cd and Pb by inductively coupled plasma mass spectrometer, for Al by inductively coupled plasma-optical emission spectrometer and Hg by Direct Mercury Analyser. The analytical method was validated by determining sensitivity, linearity, precision, spiking recoveries and analysis of the Standard Reference Material (SRM) NIST 1566-b, an Oyster Tissue. Results showed considerably higher accumulation of Al and As in analysed samples, compared to Pb and Cd, while Hg had the lowest contamination. On comparison, the obtained results with the recommended standards by the Food and Agriculture Organization, European Commission and Ministry of F...

Gonadal sex differentiation and reproduction are the keys to the perpetuation of favorable gene combinations and positively selected traits. In vertebrates, several gonad development features that differentiate tetrapods and fishes are likely to be, at least in part, related to the water-to-land transition. The collection of information from basal sarcopterygians, coelacanths, and lungfishes, is crucial to improve our understanding of the molecular evolution of pathways involved in reproductive functions, since these organisms are generally regarded as "living fossils" and as the direct ancestors of tetrapods. Here, we report for the first time the characterization of >50 genes related to sex differentiation and gametogenesis in Latimeria menadoensis and Protopterus annectens. Although the expression profiles of most genes is consistent with the intermediate position of basal sarcopterygians between actinopterygian fish and tetrapods, their phylogenetic placement and pr...

The functional separation between skeletal and cardiac muscles, which occurs at the threshold between vertebrates and invertebrates, involves the evolution of separate contractile and control proteins for the two types of striated muscles, as well as separate mechanisms of contractile activation. The functional link between electrical excitation of the surface membrane and activation of the contractile material (known as excitation–contraction [e–c] coupling) requires the interaction between a voltage sensor in the surface membrane, the dihydropyridine receptor (DHPR), and a calcium release channel in the sarcoplasmic reticulum, the ryanodine receptor (RyR). Skeletal and cardiac muscles have different isoforms of the two proteins and present two structurally and functionally distinct modes of interaction. We use structural clues to trace the evolution of the dichotomy from a single, generic type of e–c coupling to a diversified system involving a novel mechanism for skeletal muscle ...