Morphological characteristics of eyes and retinas of two sardines (Sardinops melanostictus and Etrumeus sadina,Clupeidae) and an anchovy (Engraulis japonicus,Engraulididae)

The morphology of the eyes and distribution of retinal ganglion cells in two sardine species (Sardinops melanostictus and Etrumeus sadina, Clupeidae) and the Japanese anchovy (Engraulis japonicus, Engraulididae) were investigated anatomically and histologically. The eyes of the sardines faced a slightly dorsolateral direction with the visual field extended obliquely upward. In contrast, the eyes in the anchovy were almost laterally directed. It was hypothesized that the sardines may have an advantage in receiving more downward irradiance compared with the anchovy. The lens muscle was larger in these three species than in many other teleosts, and its surface was entirely melanin‐pigmented. Also, the lens muscle directly and tightly adhered to the backside surface of the iris. The relative area of the lens muscle to the area of the lens, a referential value of the relative power of visual accommodation were notably larger in the species studied than in other teleost values that have been previously reported. A higher M/L% value of these clupeid fishes could facilitate fast and wide ranging visual accommodation and was considered to be associated with maintaining and/or re‐establishing school formations quickly. Analysis of topographical distributions of cells in the ganglion cell layer showed that cell density was highest in the ventrotemporal quadrant of the retina (temporal of the optic cleft) in all three species. Another potentially important role for the black‐pigmented lens muscle may be to block the specialized retinal area from intense sunlight that scatters and irradiates upward or laterally in the surface waters that they inhabit. Thus, the sardine and anchovy may take advantage of efficient detection of visual signals in the frontal‐upward direction and further improve visibility of the target in this direction. J. Morphol. 276:415–424, 2015. © 2014 Wiley Periodicals, Inc.     

Sialidase NEU3 and its pathological significance

Glycoconjugate Journal - Sialidases (EC 3.2.1.18, also called neuraminidases) catalyze the removal of α-glycosidically linked sialic acid residues from glycoproteins and glycolipids; this is...     

Living Monoplacophora: morphological conservatism or recent diversification?

Kano, Y., Kimura, S., Kimura, T. & Warén, A. (2012) Living Monoplacophora: morphological conservatism or recent diversification? —Zoologica Scripta, 41, 471–488. The molluscs of the class Monoplacophora are classic and probably the most striking case of a ‘living fossil’ in the deep sea. Until the discovery of the first living specimens in 1950s, the group was thought to be extinct since the Devonian period, almost 400 million years ago. Morphological conservatism over a long span of time in a ‘living‐fossil’ lineage may theoretically result in distant but closely resembling taxa, and this idea apparently led some authors to recognise as many as six families and three superfamilies for less than three dozen living monoplacophoran species. However, no genetic or fossil data have been available regarding the history of their diversification. Here we describe Veleropilina seisuimaruae sp. n., the first member of the class from the north‐western Pacific, based on the shell, radular and anatomical characteristics. Phylogenetic analyses of 6‐kb DNA sequences estimate that the divergence of V. seisuimaruae and Laevipilina hyalina, the only other monoplacophoran available for genetic studies, dates back only to the Late Cretaceous, despite their significant morphological differences among the living members of the class. The recent Monoplacophora might have radiated fairly recently from a cryptic lineage with ordinary rates of morphological evolution, possibly after the global deep‐sea anoxia at the Cenomanian/Turonian boundary.     

Induction of multinucleation by β-glucosyl Yariv reagent in regenerated cells from <Emphasis Type="Italic">Marchantia polymorpha</Emphasis> protoplasts and involvement of arabinogalactan proteins in cell plate formation

Arabinogalactan proteins (AGPs) are abundant plant cell surface proteoglycans widely distributed in plant species. Since high concentrations of β-glucosyl Yariv reagent (βglcY), which binds selectively to AGPs, inhibited cell division of protoplast-regenerated cells of the liverwort Marchantia polymorpha L. (Shibaya and Sugawara in Physiol Plant 130:271–279, 2007), we investigated the mechanism underlying the inability of the cells to divide normally by staining nuclei, cell walls and β-1,3-glucan. Microscopic observation showed that the diameter of regenerated cells cultured with βglcY was about 2.8-fold larger than that of cells cultured without βglcY. The cells cultured with βglcY were remarkably multinucleated. These results indicated that βglcY did not inhibit mitosis but induced multinucleation. In the regenerated cells cultured with low concentrations of βglcY (5 and 1 μg ml⁻¹), the cell plate was stained strongly by βglcY, suggesting abundant AGPs in the forming cell plate. In these cell plates, β-1,3-glucan was barely detectable or not detected. In multinucleated cells, cell plate-like fragments, which could not reach the cell wall, were frequently observed and they were also stained strongly by βglcY. Our results indicated that AGPs might have an important role in cell plate formation, and perturbation of AGPs with βglcY might result in remarkable multinucleation in protoplast-regenerated cells of M. polymorpha. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.