Immunohistochemical evidence for multiple photosystems in box jellyfish

Cubomedusae (box jellyfish) possess a remarkable visual system with 24 eyes distributed in four sensory structures termed rhopalia. Each rhopalium is equipped with six eyes: two pairs of pigment cup eyes and two unpaired lens eyes. Each eye type probably captures specific features of the visual environment. To investigate whether multiple types of photoreceptor cells are present in the rhopalium, and whether the different eye types possess different types of photoreceptors, we have used immunohistochemistry with a range of vertebrate opsin antibodies to label the photoreceptors, and electroretinograms (ERG) to determine their spectral sensitivity. All photoreceptor cells of the two lens eyes of the box jellyfish Tripedalia cystophora and Carybdea marsupialis displayed immunoreactivity for an antibody directed against the zebrafish ultraviolet (UV) opsin, but not against any of eight other rhodopsin or cone opsin antibodies tested. In neither of the two species were the pigment cup eyes immunoreactive for any of the opsin antibodies. ERG analysis of the Carybdea lower lens eyes demonstrated a single spectral sensitivity maximum at 485 nm suggesting the presence of a single opsin type. Our data demonstrate that the lens eyes of box jellyfish utilize a single opsin and are thus color-blind, and that there is probably a different photopigment in the pigment cup eyes. The results support our hypothesis that the lens eyes and the pigment cup eyes of box jellyfish are involved in different and specific visual tasks.     

A pilot study to evaluate the levels of aqueous humor trace elements in open-angle glaucoma

BackgroundPrimary open angle glaucoma (POAG) is the most common form of chronic, progressive optic neuropathies characterized by slow degeneration of the retinal ganglion cells and their axons, resulting in visual field loss. Risk factors for this disease are elevated intraocular pressure (IOP), increased age, European and African ethnicity, family history, myopia and decreased corneal thickness. In addition, studies indicated that levels of trace elements are also significantly related to the POAG.MethodThe association between toxic and essential elements and POAG was explored in a population-based case–control study in the Sardinia Island (Italy). The aqueous humor levels of Al, Cd, Cu, Fe, Hg, Mn, Ni, Pb and Zn were measured in 25 POAG patients compared to 20 age- and gender-matched healthy controls by sector field inductively coupled mass spectrometry. Risk factors as gender, age and increased IOP were also explored.ResultsThe concentrations of Fe, Hg and Zn were significantly higher in POAG patients than in control subjects, showing these elements as possible determinants in POAG development or degeneration. Other findings were the increased Cu and Fe levels in glaucomatous patients with age less than 70 years. Levels of Ni were found elevated in POAG females. Mercury accumulated more in POAG females, in patients over 70 years and in those with higher levels of IOP in the left eye. Moreover, the positive associations CuFe and Mn-Zn may indicate synergistic effects of elements.ConclusionsAltogether, these findings suggested a multifactorial role in the risk for POAG disease. The present study documented the levels of trace elements in aqueous humor of Sardinian POAG patients for the first time.     

眼部常见疾病的超声诊断分析

目的：总结眼部常见疾病的超声表现,探讨超声对其的诊断价值。方法：对2009年6月～2010年6月来我院超声科行眼部超声检查（占位性病变经手术或病理学结果证实）的63例患者的资料进行回顾性分析,归纳总结了眼部常见疾病的二维超声（2D）、彩色多普勒（CDFI）及超声造影（CEUS）表现。结果：眼部疾病的超声图像在位置、形状、边界、声学特点及对周围组织的影响等方面具有特征性表现;超声造影能有效地显示出病灶内的血管及血流灌注情况。结论：超声对眼部常见病的诊断是一种简便、无创、经济且诊断符合率高的辅助影像学方法,具有较高的实际应用价值。     

Cross species analysis of Prominin reveals a conserved cellular role in invertebrate and vertebrate photoreceptor cells

The two fundamental types of photoreceptor cells have evolved unique structures to expand the apical membrane to accommodate the phototransduction machinery, exemplified by the cilia-based outer segment of the vertebrate photoreceptor cell and the microvilli-based rhabdomere of the invertebrate photoreceptor. The morphogenesis of these compartments is integral for photoreceptor cell integrity and function. However, little is known about the elementary cellular and molecular mechanisms required to generate these compartments. Here we investigate whether a conserved cellular mechanism exists to create the phototransduction compartments by examining the functional role of a photoreceptor protein common to both rhabdomeric and ciliated photoreceptor cells, Prominin. First and foremost we demonstrate that the physiological role of Prominin is conserved between rhabdomeric and ciliated photoreceptor cells. Human Prominin1 is not only capable of rescuing the corresponding rhabdomeric Drosophila prominin mutation but also demonstrates a conserved genetic interaction with a second photoreceptor protein Eyes Shut. Furthermore, we demonstrate the Prominin homologs in vertebrate and invertebrate photoreceptors require the same structural features and post-translational modifications for function. Moreover, expression of mutant human Prominin1, associated with autosomal dominant retinal degeneration, in rhabdomeric photoreceptor cells disrupts morphogenesis in ways paralleling retinal degeneration seen in ciliated photoreceptors. Taken together, our results suggest the existence of an ancestral Prominin-directed cellular mechanism to create and model the apical membranes of the two fundamental types of photoreceptor cells into their respective phototransduction compartments.     

The optic neuropiles and chiasmata of Crustacea

Summary On the basis of ontogeny and adult morphology, an interpretation of the arrangement of optic neuropiles and fibre connexions of the Crustacean compound eye is presented. In the embryo of phyllopods and decapods, the ommatidia, the lamina ganglionaris, and the medulla externa are developed synchronously from a common medial proliferation zone. As this zone persists in all investigated adult Crustacea that possess compound eyes, such a derivation of the mentioned structures is taken to be universal within the group. The direction of growth of the lamina ganglionaris is parallel with the row of ommatidia, the growth direction of the medulla externa is perpendicular to it and parallel with the long axis of the eyestalk. This arrangement is more or less retained in most adult non-Malacostracan Crustacea, and the axons of fully developed neurons pierce the optic neuropiles and leave and enter on the neuropile side. As a result, there is no chiasma in the non-Malacostracan groups.The Malacostraca have an extra neuropile, the medulla interna, derived from the medulla terminalis. Chiasmata occur between the lamina ganglionaris and the medulla externa, and between the medulla externa and the medulla interna. This difference from the non-Malacostracans depends on the course of the fibres. Those coming from the lamina ganglionaris leave the lamina on the neuropile side and enter medulla externa between the cell bodies in the perikaryon layer of the medulla externa neurons and the neuropile of the medulla. The fibres from the medulla externa to the lamina come from T-shaped neurons and emanate from the perikaryon layer side, entering the lamina on its neuropile side. The fibre relations between the medulla externa and the medulla interna are similar. Thus in both cases, chiasmata are present from the beginning, but they become obvious when the medulla externa rotates through part of a circle.The directed growth of the optic neuropiles and the course of the fibre connexions are consequently crucial to the understanding of the topographic relations between the neuropiles. A pattern with short neurons connecting neighbouring optic neuropiles and long neurons connecting the medulla externa with the central nervous system is common to all crustaceans.In memoriam Bertil Hanström.This work has been supported by a grant from the Swedish Natural Science Research Council 2760-3, 99-35.     

The larval eye of the aeolid nudibranch Trinchesia aurantia (Alder and Hancock)

Summary The larval eye of the aeolid nudibranch Trinchesia aurantia has been investigated at three different stages; in all, the eyes remain closely attached to, and in cellular contact with, the central ganglia. The larval eye is a simplified version of the adult eye in that, the eye and the constituent cells, nuclei, lens, microvilli and pigment granules are all smaller, and the interdigitation between the retinal cells is not developed. The absence of the small cells of the cornea and of the spherical vesicles in the cytoplasm of the sensory cells, is further evidence of the incomplete formation of the eye. The possible origin of the eye of Trinchesia is discussed and compared with that of other gastropods.I am very grateful for the help and guidance of my supervisor Dr. D. A. Dorsett throughout the preparation of this paper. I was sponsored by a grant from the N.E.R.C.     

A light and electron microscope study of some opisthobranch eyes

Summary The retina of nudibranch eyes contains two types of large cells; pigment cells which comprise about two-thirds of the total, with unpigmented sensory cells making up the remainder. Both pigment and receptor cells carry microvilli on their distal borders, but no traces of cilia were observed among them. The cornea of the eyes of aeolid and dendronotid nudibranchs is composed of a single layer of small cells, unlike the dorids where the cornea is made up of one of more large cells. The latter contain nuclei comparable in size with those of the pigment cells in the retina, but are themselves unpigmented.The elliptical eyes ofAplysia contain three types of retinal cell; the pigment cells and two kinds of receptor cells. The ciliary receptor cells bear equal numbers of cilia (9+2) and microvilli, while the microvillous receptor cells carry long tufts of microvilli with only an occasional cilium among them. The proximal cytoplasm of the receptor cells inAplysia and the nudibranchs contains large quantities of the small spherical vesicles (averaging 660 Å in diameter) which appear to be characteristic of gastropod eyes.