ABSTRACT Ocean acidification can affect the ability of calcifying organisms to build and maintain mineralized tissue. In decapod crustaceans, exoskeleton is a multilayered structure composed chitin, protein mineral, predominately magnesian calcite or amorphous calcium carbonate (ACC). We investigated effects on mature (post-terminal-molt) female southern Tanner crabs, Chionoecetes bairdi. Crabs...

Ichthyoliths—microfossil fish teeth and shark dermal scales (denticles)—are found in nearly all marine sediments. Their small size and relative rarity compared to other microfossil groups means that they have been largely ignored by the paleontology and paleoceanography communities, except as carriers of certain isotopic systems. Yet, when properly concentrated, ichthyoliths are sufficiently ab...

In a taxonomic review of the species of the Heterodera "cacti group," H. thornei n. sp. is described and illustrated from Miner's lettuce in California. This new species is distinguishable especially by havpunctate egg shells and a larval stylet (27 mum) and tail (56 mum) longer than other related species. Heterodera weissi is redescribed, type specimens are designated, and new data added on th...

The Neotropical freshwater stingray Potamotrygom orbignyi (Castelnau, 1855), and other similar "reticulated" species occurring in northern South American basins, were submitted to a thorough taxonomic analysis based on an extensive external and internal morphological study. The identity of P. orbignyi and the taxonomic status of the related nominal species Potamotrygon dumerilii (Castelnau, 185...

The closely related Hox transcription factors Ultrabithorax (Ubx) and Antennapedia (Antp) respectively direct first abdominal (A1) and second thoracic (T2) segment identities in Drosophila. It has been proposed that their functional differences derive from their differential occupancy of DNA target sites. Here we show that a hybrid version of Ubx (Ubx-VP16), which possesses an enhanced transcri...

Each segment of a Drosophila larva shows a precisely organized pattern of cuticular structures, indicating diverse cellular identities in the underlying epidermis. Mutations in the segment polarity genes alter the cuticle pattern secreted by the epidermal cells; these mutant patterns provide clues about the role that each gene product plays in the development of wild-type epidermal pattern. We ...

The North American genus Heterocloeon McDunnough is redefined and shown to be distinct from other two-tailed Baetis complex genera, including Acentrella Bengtsson and Plauditus Lugo-Ortiz and McCafferty, which are also represented in North America. Heterocloeon is divided into three distinct subgenera, including Heterocloeon s.s., Iswaeon McCafferty and Webb, new subgenus, and Jubilatum McCaffe...

Essentially we show recent data to shed new light on the thorny controversy of how teeth arose in evolution. Essentially we show (a) how teeth can form equally from any epithelium, be it endoderm, ectoderm or a combination of the two and (b) that the gene expression programs of oral versus pharyngeal teeth are remarkably similar. Classic theories suggest that (i) skin denticles evolved first an...

Mosasaur researchers have used varieties of tooth crown ornamentation as diagnostic and phylogenetic characters for decades. Such features include facets, flutes, striations, serrated carinae, coarse anastomosing texture. This study investigates the relative contribution dentine enamel to development these dental assesses possible homologies between structures. Histological analysis isolated mo...

The taxonomy of the enigmatic dark-mouth skate, Bathyraja arctowskii (Dollo, 1904), from Southern Ocean was finally resolved after more than 100 years ambiguity in 2021. This species is smallest known species-rich deep-water skate genus Ishiyama, 1958, which attains a total length only about 61 cm and appears to be wide-ranging locally common Ocean. It differs its congeners small adult size, da...