Checklist of coral reef fishes of Darvel Bay, Sabah, Malaysian Coral Triangle, with a note on the biodiversity and community structure.

The Darvel Bay is a large semi-enclosed bay with spectacular natural land and seascape. The inward side of the Bay has only been recently known to be an important foraging ground for the endangered, threatened and protected (ETP) elasmobranch species, such as the Whale Shark and mobulid rays. Following a recent scientific expedition, we present a checklist of the coral reef fishes of Darvel Bay. A note on the biodiversity and community structure is presented, based on our analysis using diversity indices, univariate and multivariate approaches. Seven natural coral reefs comprising two fringing reefs and five patch reefs, were surveyed at 10 m depth using underwater visual census (UVC) and baited remote underwater video station (BRUVS) methods. A diverse list of 66 species of reef fishes from 17 families is recorded. However, this is overwhelmingly dominated by the small-sized omnivorous damselfish, family Pomacentridae (62%; N = 1485 individuals). Species richness and abundance were observed to increase at sites surveyed furthest from the coast within the Bay. Significantly distinct reef fish assemblages were observed between three priori groups, based on proximity to shore (ANOSIM, R = 0.65, p < 0.05). SIMPER analysis further revealed that 22 species of the total reef fish species recorded drive 76% dissimilarities between the groups. The pattern of the reef fish communities observed, reflected as a logseries distribution model, is that commonly found in disturbed habitats or habitats characterised by restricted resources in a community, where the dominant species takes up a high proportion of available resources. The ecological indices (Shannon-Wiener Diversity Index, 2.05; Simpson Index of Diversity, 0.79; Simpson Dominance Index, 0.20; and Pielou's Evenness Index, 0.43), all reflect the relatively low diversity and uneven species distribution of the reef fish community. We conclude that the present status of the coral reef fish community dominating Darvel Bay as having undergone a rapid shift in structure following intense and rampant fishing pressure, as reported by the media.

Evidence that microtubules do not mediate opsin vesicle transport in photoreceptors.

The organization of the rod photoreceptor cytoskeleton suggests that microtubules (MTs) and F actin are important in outer segment (OS) membrane renewal. We studied the role of the cytoskeleton in this process by first quantifying OS membrane assembly in rods from explanted Xenopus eyecups with a video assay for disc morphogenesis and then determining if the rate of assembly was reduced after drug disassembly of either MTs or F actin. Membrane assembly was quantified by continuously labeling newly forming rod OS membranes with Lucifer Yellow VS (LY) and following the tagged membranes' distal displacement along the OS. LY band displacement displayed a linear increase over 16 h in culture. These cells possessed a longitudinally oriented network of ellipsoid MTs between the sites of OS protein synthesis and OS membrane assembly. Incubation of eyecups in nocodazole, colchicine, vinblastine, or podophyllotoxin disassembled the ellipsoid MTs. Despite their absence, photoreceptors maintained a normal rate of OS assembly. In contrast, photoreceptors displayed a reduced distal displacement of LY-labeled membranes in eyecups treated with cytochalasin D, showing that our technique can detect drug-induced changes in basal rod outer segment assembly. The reduction noted in the cytochalasin-treated cells was due to the abnormal lateral displacement of newly added OS disc membranes that occurs with this drug (Williams, D. S., K. A. Linberg, D. K. Vaughan, R. N. Fariss, and S. K. Fisher. 1988. J. Comp. Neurol. 272:161-176). Together, our results indicate that the vectorial transport of OS membrane constituents through the ellipsoid and their assembly into OS disc membranes are not dependent on elliposid MT integrity.

Complete mitochondrial genome of six Cheilinus undulatus (Napoleon Wrasse): an endangered marine fish species from Sabah, Malaysia.

We report here the complete mitochondrial (mt) genomes of six individuals of Cheilinus undulatus (Napoleon Wrasse), an endangered marine fish species. The six mt DNA sequences had an average size of 17,000 kb and encoded 22 tRNA, two sRNA, 13 highly conserved protein coding genes and a control region. The polymorphic variation (control region) in these six individuals suggests their potential use as a specific marker for phylogeographic conservation. Moreover, the sequence polymorphism within the control region (D-loop) suggests that this locus can be applied for phylogenetic studies.

Two new whiprays, Maculabatis arabica sp. nov. and M. bineeshi sp. nov. (Myliobatiformes: Dasyatidae), from the northern Indian Ocean.

Two new medium-sized whiprays, Maculabatis arabica sp. nov. and M. bineeshi sp. nov., are described from specimens collected in coastal habitats of the northern Indian Ocean, off India and Pakistan. Both species superficially resemble M. randalli (Last, Manjaji-Matsumoto & Moore), and appear to have been confused with a more widely distributed whipray M. gerrardi Gray, and another undescribed species from the Indian Ocean. Maculabatis arabica sp. nov. (attains at least 63 cm DW) is diagnosed by a combination of external characters, i.e. morphometrics (e.g. relatively short disc, narrow interspaces between paired structures on the head), squamation (relatively slow denticle development and a characteristic denticle band shape), plain dorsal disc coloration (rather than spotted), and tail light brown and banded beyond the caudal sting in juveniles but almost plain in adults. Maculabatis bineeshi sp. nov. (attains at least 66 cm DW) is diagnosed by a combination of characters, i.e. morphometrics (e.g. suboval to weakly rhombic disc in young), squamation (rapid denticle development and broad denticle band with margins truncate near pectoral-fin insertions), plain dorsal disc coloration (no white spots), and a dark blackish tail (especially in young) with weakly mottled banding on its dorsal surface beyond the caudal sting. Maculabatis arabica sp. nov. appears to be confined to the Arabian Sea (from Pakistan to western India), whereas M. bineeshi sp. nov. occurs in the Arabian Sea (off Pakistan and northwestern India) and in the Bay of Bengal (confirmed off Odisha, eastern India).

A revised classification of the family Dasyatidae (Chondrichthyes: Myliobatiformes) based on new morphological and molecular insights.

The higher-level taxonomy of the stingrays (Dasyatidae) has never been comprehensively reviewed. Recent phylogenetic studies, supported by morphological data, have provided evidence that the group is monophyletic and consists of four major subgroups, the subfamilies Dasyatinae, Neotrygoninae, Urogymninae and Hypolophinae. A morphologically based review of 89 currently recognised species, undertaken for a guide to the world's rays, indicated that most of the currently recognised dasyatid genera are not monophyletic groups. These findings were supported by molecular analyses using the NADH2 gene for about 77 of these species, and this topology is supported by preliminary analyses base on whole mitochondrial genome comparisons. These molecular analyses, based on data generated from the Chondrichthyan Tree of Life project, are the most taxon-rich data available for this family. Material from all of the presently recognised genera (Dasyatis, Pteroplatytrygon and Taeniurops [Dasyatinae]; Neotrygon and Taeniura [Neotrygoninae]; Himantura and Urogymnus [Urogymninae]; and Makararaja and Pastinachus [Hypolophinae]), are included and their validity largely supported. Urogymnus and the two most species rich genera, Dasyatis and Himantura, are not considered to be monophyletic and were redefined based on external morphology. Seven new genus-level taxa are erected (Megatrygon and Telatrygon [Dasyatinae]; Brevitrygon, Fluvitrygon, Fontitrygon, Maculabatis and Pateobatis [Urogymninae], and an additional three (Bathytoshia, Hemitrygon and Hypanus [Dasyatinae]) are resurrected from the synonymy of Dasyatis. The monotypic genus Megatrygon clustered with 'amphi-American Himantura' outside the Dasyatidae, and instead as the sister group of the Potamotrygonidae and Urotrygonidae. Megatrygon is provisionally retained in the Dasyatinae pending further investigation of its internal anatomy. The morphologically divergent groups, Bathytoshia and Pteroplatytrygon, possibly form a single monophyletic group so further investigation is needed to confirm the validity of Pteroplatytrygon. A reclassification of the family Dasyatidae is provided and the above taxa are defined based on new morphological data.

Ectopic expression of alpha B-crystallin in Chinese hamster ovary cells suggests a nuclear role for this protein.

alpha B-crystallin (alpha B) is known to be a cytosolic, small heat shock-like multimeric protein that has anti-aggregation, chaperone-like properties. The expression of the alpha B-crystallin gene is developmentally regulated and is induced by a variety of stress stimuli. Importantly, alpha B-crystallin expression is enhanced during oncogenic transformation of cells, in a number of tumors, and most notably, in many neurodegenerative disorders, including Alzheimer's disease and multiple sclerosis. Other than its perceived role as a structural protein in the ocular lens, the actual function of alpha B-crystallin in cellular physiology remains unknown. We have stably transfected CHO cells with an inducible alpha B-cDNA-MMTV-promoter construct that allows the synthesis of recombinant alpha B-crystallin only upon exposure of these cells to dexamethasone. Using immunostaining and conventional and confocal microscopy, we have examined the subcellular distribution of the ectopically expressed alpha B-crystallin. We find that in addition to being in the cytoplasm, the protein resides in the nuclear interior in the interphase nucleus. Double labeling with anti alpha B-crystallin and anti-tubulin, concanavallin, and wheat germ agglutinin, respectively, revealed that during cell division alpha B-crystallin is excluded from condensed chromatin and the nascent nuclei. However, the protein again appears in the newly formed nuclei after the completion of cytokinesis suggesting a conditional, regulatory role for alpha B-crystallin in the nucleus.

Cortical gray matter volume deficit in patients with first-episode schizophrenia.

OBJECTIVE: A cortical gray matter deficit has been found in cross-sectional studies of patients with chronic schizophrenia. The purpose of this study was to examine whether this deficit is present early in the course of illness. METHOD: The authors measured cortical gray matter volume on magnetic resonance images acquired within 6 months of onset of illness from 22 patients with first-episode schizophrenia and 51 age-matched comparison subjects from the Stony Brook First Episode Study. RESULTS: A significant cortical gray matter deficit and lateral ventricular enlargement were found in schizophrenic patients relative to the comparison group. CONCLUSIONS: The presence of the cortical gray matter deficit close to onset of illness supports the role of preexisting structural brain deficits in the genesis of schizophrenia.

The actin network in the ciliary stalk of photoreceptors functions in the generation of new outer segment discs.

Cytochalasin D (CD) interferes with the morphogenesis of outer segment disc membrane in photoreceptors. Disruption of either the actin network in the ciliary stalk, where membrane evagination is initiated, or the actin core of the calycal processes, whose position could define the disc perimeter, could be responsible. We have attempted to determine which of these local F-actin populations is involved in membrane morphogenesis and what step in the process is actin-dependent. Biocytin accumulation in nascent discs, detected by fluorescent avidin and laser scanning confocal microscopy (LSCM), provided a means of labeling abnormal discs and a measure of disc membrane addition. F-actin content and distribution were assessed using fluorescent phalloidin and LSCM. First, we examined the effects of a range of CD dosages (0.1, 1.0, or 10.0 microM) on rod photoreceptors in Xenopus laevis eyecup cultures. Ectopic outgrowth of discs, evaluated by LSCM and transmission electron microscopy (TEM), occurred at each concentration. Phalloidin labeling intensified in the ciliary stalk with increasing CD concentration, indicating F-actin aggregation. In contrast, it diminished in the calycal processes, indicating dispersal; TEM showed that calycal process collapse ensued. Disruption was evident at a lower concentration in the ciliary stalk (0.1 microM) than in the calycal processes (1.0 microM). TEM confirmed that the calycal processes remained intact at 0.1 microM. Thus, CD's action on the ciliary stalk network is sufficient to disrupt disc morphogenesis. Second, we examined the effect of CD on temperature-induced acceleration of the rate of disc formation. In the absence of CD, a 10 degrees C temperature shift increased the disc formation rate nearly three-fold. CD (5 microM) caused a 94% inhibition (P < 0.025) of this response; yet, the rate of membrane addition to ectopically growing discs exhibited the expected three-fold increase. Thus, CD's action interferes with the generation of new discs.

Evidence from normal and degenerating photoreceptors that two outer segment integral membrane proteins have separate transport pathways.

Detachment of the neural retina from the retinal pigment epithelium induces photoreceptor degeneration. We studied the effects of this degeneration on the localization of two photoreceptor outer segment-specific integral membrane proteins, opsin and peripherin/rds, in rod photoreceptors. Results from laser scanning confocal microscopic and electron microscopic immunolocalization demonstrate that these two proteins, normally targeted to the newly-forming discs of the outer segments, accumulate in different sub-cellular compartments during photoreceptor degeneration: opsin immunolabeling increases throughout the photoreceptor cell's plasma membrane, while peripherin/rds immunolabeling occurs within cytoplasmic vesicles. The simplest hypothesis to explain our results is that these proteins are transported in different post-Golgi transport vesicles and separately inserted into the plasma membrane. More complex mechanisms involve having the two co-transported and then opsin finds its way into the plasma membrane but peripherin/rds does not, remaining behind in vesicles. Alternatively, both insert into the plasma membrane but peripherin/rds is recycled into cytoplasmic vesicles. We believe the data most strongly supports the first possibility. Although the transport pathways for these proteins have not been fully characterized, the presence of peripherin/rds-positive vesicles adjacent to the striated rootlet suggests a transport role for this cytoskeletal element. The accumulation of these proteins in photoreceptors with degenerated outer segments may also indicate that their rate of synthesis has exceeded the combined rates of their incorporation into newly forming outer segment disc membranes and their degradation. The accumulation may also provide a mechanism for rapid recovery of the outer segment following retinal reattachment and return of the photoreceptor cell to an environment favorable to outer segment regeneration.

Retinoid cycling proteins redistribute in light-/dark-adapted octopus retinas.

In cephalopods, the complex rhodopsin-retinochrome system serves to regenerate metarhodopsin and metaretinochrome after illumination. In the dark, a soluble protein, retinal-binding protein (RALBP), shuttles 11-cis retinal released from metaretinochrome located in the photoreceptor inner segments to metarhodopsin present in the rhabdoms. While in the rhabdoms, RALBP delivers 11-cis retinal to regenerate rhodopsin and in turn binds the all-trans isomer released by metarhodopsin. RALBP then returns all-trans retinal to the inner segments to restore retinochrome. The conventional interpretation of retinoid cycling is contradicted by immunocytochemical studies showing that, in addition to rhodopsin, retinochrome is present in the rhabdomal compartment, making possible the direct exchange of chromophores between the metapigments with the potential exclusion of RALBP. By using immunofluorescence and laser scanning confocal microscopy, we have precisely located opsin, aporetinochrome, and RALBP in light-/dark-adapted octopus retinas. We found differences in the distribution of all three proteins throughout the retina. Most significantly, comparison of cross sections though light- and dark-adapted rhabdoms showed a dramatic shift in position of the proteins. In the dark, opsin and retinochrome colocalized at the base of the rhabdomal microvilli. In the light, opsin redistributed along the length of the microvillar membranes, and retinochrome retreated to a location that is perhaps extracellular. RALBP was present in the core cytoplasm of the photoreceptor outer segments in the dark, and RALBP moved to the periphery in the light. Because of the colocalization of opsin and retinochrome in the dark, we believe that the two metapigments participate directly in chromophore exchange. RALBP may serve to transport additional chromophore from the inner segments to the rhabdoms and may not be immediately involved in the exchange process.

Diurnal variations in amino acid incorporation into inner segment opsin.

Polyacrylamide gel and immunoelectrophoresis were used to measure the specific activity of nascent inner segment opsin following injections of labeled amino acids into frogs at different times during the diurnal cycle. Animals injected just after light onset showed the greatest incorporation of label into opsin, while animals injected during the night period had the lowest levels of isotope incorporation. As determined by rocket immunoelectrophoresis, there was a 13-fold decline in specific activity in animals injected during the late night hours in comparison with animals injected just after light onset. In contrast, rod outer segment rhodopsin-specific activity did not vary as greatly. Animals subjected to a 12-hour light-12-hour dark diurnal cycle incorporated only twice the radiolabeled amino acids into their rhodopsin compared with animals injected and maintained in constant dark for 24 hours. Taken together, these experiments suggest that adult Rana pipiens accumulate opsin within their inner segments during the dark phase of the diurnal cycle and that alterations of this pool effect changes in inner segment opsin specific activity. Differences in outer segment rhodopsin specific activity are probably due to averaged metabolic differences between constant dark and light-dark animals.

Light and temperature modulated staining of the rod outer segment distal tips with Lucifer yellow.

External application of the dye Lucifer yellow to isolated retinas of Xenopus laevis causes a specific staining of the distal tips of the rod outer segment (ROS). Staining occurs most frequently in the distal 4 micron of the ROS and does not diffuse throughout the ROS cytosol. In contrast, damaged ROS fill with the dye and exhibit a diffuse fluorescence. Retinas from constant light-treated animals show a greater frequency of labeling when isolated in the light than when isolated in the dark after 0.5 and 3 hr. Increased frequency of distal tip staining for dark-treated animals can be achieved if animals are returned to the light. Distal tip labeling also occurs in cyclic-light maintained animals but at a much lower frequency. The frequency of distal tip staining can also be altered by temperature and metabolic poisons. Isolated retinas exposed to dye solutions kept at either 3 degrees C or containing the metabolic poisons, iodoacetate or dinitrophenol, exhibited a reduced frequency of staining. This suggests that staining is an active process involving cellular metabolism. The distal location, dimensions, and light dependence of staining suggests that labeled regions are destined for detachment as part of disc shedding. The sensitivity of distal tip staining to metabolic poisons suggests that the photoreceptor plays a role in determining the membrane domains destined for shedding.

Topographic variations in the rabbit and primate internal limiting membrane.

The internal limiting membrane (ILM) and cortical vitreous of the rabbit and primate were studied with transmission electron microscopy following staining with the cationic dye, Alcian blue GX. An unusual feature of the cortical vitreal collagen fibril was its displacement from the ILM: it did not insert into the lamina densa. The separation between vitreal collagen and the ILM was especially noticeable in the rabbit eye, which possessed an extremely strong vitreal retinal attachment in the posterior fundus. The lack of fibril insertion was observed in rabbit tissue that had been fixed by quick freezing on a helium-cooled copper block. The similarity in the appearance of tissue fixed by glutaraldehyde, glutaraldehyde supplemented with Alcian blue, or by quick freezing suggested that the lack of collagen fibril insertion into the ILM was an accurate representation of the relationship between collagen and the ILM. It was found that these two animal species had radically different ILM's; the rabbit ILM was a thin basement membrane throughout all areas of the posterior fundus, whereas the ILM of the cynomolgus monkey was a thick basement membrane in the peripapillary region and a thin basement membrane in the region of the fovea centralis. The topographic variations in the primate ILM thickness and appearance followed the pattern observed in human eyes. Like man, the thickening of the cynomolgus ILM in the posterior fundus was age related. The similarity between the cynomolgus and human ILM suggests that this animal would be more suitable than the rabbit for studying age-related changes or alterations in the strength of vitreal attachment following trauma.

Effects of retinal detachment on rod disc membrane assembly in cultured frog retinas.

The authors compared rod outer segment (ROS) disc membrane assembly rates in detached and attached frog retinas to determine if there was a rapid impairment of membrane assembly in response to retinal detachment. Membrane assembly was quantified in vitro by incubating retinas in medium containing Lucifer yellow, which is entrapped by nascent discs. Video microscopy was used to detect incorporation of the dye. During the first 10 hr after separation of the retina from the retinal pigment epithelium (RPE), ROS-disc membrane assembly in isolated Xenopus laevis neural retinas continued at a near normal rate, 0.81 microns/10 hr, a 13% reduction (P less than .01), compared with the 0.93 microns/10 hr observed in attached control retinas. The morphology of the OS appeared normal in most rod photoreceptors by transmission electron microscopy, although vesiculation of the most basal OS membranes was seen in a small population (25%) of rods. Approximately 90% of rod photoreceptors continued to assemble OS membranes for more than 10 hr after detachment, but by the end of 2 days, only 55% were still making new discs. The percentage of rods with normal basal OS membranes also decreased (to approximately 50%). Therefore, only 25% were assembling morphologically normal discs 2 days after detachment. In attached control regions, rod photoreceptors showed a comparatively minor response to culture conditions; assembly of morphologically normal discs continued for 2 days in about 85% and ceased in only 10%. These results indicate that the effects on disc membrane assembly of disrupting photoreceptor-RPE interaction in vitro initially are slight but become progressively severe with time.

Changes in the organization and expression of cytoskeletal proteins during retinal degeneration induced by retinal detachment.

PURPOSE: The goal of this study was to determine the changes in the organization of the retinal cytoskeleton after experimental retinal detachment. METHODS: Cat retinas were detached from the retinal pigment epithelium and then processed for Western blot analysis and fluorescence microscopy. Proteins examined included glial fibrillary acidic protein (GFAP), vimentin, tubulin, and actin. Sections were viewed using a laser scanning confocal microscope. RESULTS: GFAP and vimentin: At 1 day after detachment, there was an aggregation of intermediate filaments in the endfoot of Müller cells. At 3 days, intermediate filament containing Müller cell processes could be detected within the subretinal space, and, at 28 days, these processes formed large glial scars in the subretinal space. beta-tubulin: At 3 days after detachment, an increase in immunolabeling could be detected within the Müller cell endfoot and in Müller cell processes within the subretinal space. Actin: At 3 days after detachment, rhodamine-phalloidin staining decreased in the inner segments, the photoreceptor synaptic terminals, and the outer limiting membrane. CONCLUSIONS: The decrease in labeling of the photoreceptor inner segment and synaptic terminal cytoskeleton may be a key indicator of early changes in photoreceptors after detachment. The increase in cytoskeletal proteins GFAP, vimentin, and tubulin within the retinal Müller cells after detachment may help to stabilize this cell type as it hypertrophies during glial scar formation. Inhibition of this response may aid in the treatment of diseases in which Müller cell hypertrophy plays a role.

Cytoskeletal redifferentiation of feline, monkey, and human RPE cells in culture.

Retinal pigment epithelial (RPE) cells in vivo have a polarized structure with specialized apical and basal faces. Isolated RPE cells lose but eventually regain their epithelial morphology under appropriate culture conditions. We evaluated the ability of isolated feline, primate, and human RPE cells to regain this morphology in culture with scanning electron, transmission electron, phase contrast, and immunofluorescence microscopy. In culture, isolated RPE cells lose their cuboidal shape, their apical microvilli, and their in vivo cytoskeletal organization. Stress fibers from in these cells; microtubules radiate from the cells' center to their periphery; and vimentin filaments radiate from the cells' nucleus to their periphery. As cultures become confluent, RPE cells aggregate into small groups, gradually regaining a cuboidal shape and acquiring microvilli on their apical surface. Filamentous actin redistributes to the apical face where it presumably forms the cytoskeletal core normally present in RPE microvilli. Stress fibers disappear and are replaced by a circumferential microfilament bundle (CMB). Confluent cells surrounding the colonies of differentiated RPE attain a cuboidal shape but do not show complete cytoskeletal redifferentiation. Such cells, while appearing to be differentiated by phase contrast microscopy, fail to develop a compacted CMB. In these cells, f-actin is organized as a loose peripheral band within the cell cytoplasm. Our observations indicate that confluency cannot be equated with the end stage of morphologic differentiation, and that cytoskeletal organization provides a more accurate gauge of RPE maturation in culture.

Identification and localization of a beta-1 receptor from the integrin family in mammalian retinal pigment epithelial cells.

The distribution of an adhesion receptor from the integrin family was mapped in cultured mammalian retinal pigment epithelial cells (RPE), and in primate RPE cells in vivo, using antibodies to the human fibronectin receptor (FnR) in conjunction with indirect immunofluorescence and immunoelectron microscopy. Protein homogenates from human RPE or MG-63 cells were separated by sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) under nonreducing conditions. On Western blots of proteins from both cell types, anti-FnR and a monoclonal antibody to the beta 1 subunit of human FnR each recognized a single band with a molecular mass of approximately 115 kDa. After 1-6 weeks in culture human, monkey and feline RPE cells gradually acquired a morphology and cytoskeletal arrangement typical of a mature cuboidal epithelium. The distribution of anti-FnR labeling changed dramatically in accordance with the cells' phenotype. In preconfluent cells, labeling consisted of streaks and flecks of fluorescence at the termini of stress fibers and at putative sites of cell substratum attachment. As the cells became confluent and acquired an epithelioid morphology, the bulk of anti-FnR labeling shifted to the peripheral cytoplasm and appeared as a cross-hatched meshwork. In fully differentiated RPE cells anti-FnR labeling consisted of a dense punctate pattern on or close to the apical cell surface that coincided with the distribution of f-actin as shown by phalloidin staining, and to the distribution of apical microvilli as identified by scanning electron microscopy. In addition, a compacted rim of fluorescence appeared at the cells' lateral margins that was also virtually identical to the phalloidin staining pattern. No basal surface labeling was apparent at this stage. At the ultrastructural level, FnR was localized to the apical surface of nonpermeabilized RPE cells and, in particular, to the plasma membrane of apical microvilli in vitro and in vivo using an indirect, pre-embedding method. The results strongly suggest that: (1) a membrane receptor/s containing the integrin beta 1 subunit is normally present on the plasma membrane of apical microvilli and on the lateral cell surfaces of cultured mammalian RPE cells; and (2) this receptor also is present on the plasmalemma of RPE apical microvilli in vivo.

Rapid changes in the expression of glial cell proteins caused by experimental retinal detachment.

We examined the expression of several proteins normally present in Müller's glia after the production of experimental retinal detachment in adult cats. Retinas were detached for one-half to seven days, after which the tissue was processed for correlative immunocytochemistry and biochemistry. Previous studies demonstrated that the intermediate filament proteins glial fibrillary acidic protein and vimentin, increase after long-term retinal detachment (30 to 60 days), whereas glutamine synthetase, carbonic anhydrase C, and cellular retinaldehyde-binding protein all decrease to barely detectable levels. Alterations in Müller cell protein expression are rapid and specific events that can be detected as early as two days after retinal detachment. By seven days, levels of protein expression are similar to those in the long-term retinal detachments. Within the first week after injury the Müller cell processes hypertrophy and begin forming glial scars, which indicates that early intervention may be required to halt or reverse the effects of detachment.

Quantification of cerebellar structures with MRI.

Methodological issues have limited neuroimaging studies of cerebellar structures. In this article we describe a method that addresses some of these limitations and phantom studies that examine the validity of the image manipulations. We compared volumes derived from 3D Spoiled Gradient Recalled Acquisition MR images sliced with respect to three different alignment methods: one based on cerebellar landmarks, another on cerebral landmarks and a third on the plane of acquisition. Examination of coefficients of variation, coefficients of error and convergent validity suggests that although regional cerebellar volumes based on cerebellar landmarks provide the best estimates of the true volumes, observed differences between volume measurements from alignments based on cerebellar or cerebral landmarks were generally not significant and were inconsequential. In this case, the measure was improved with alignment along local, relevant cerebellar landmarks. A set of phantom experiments showed that realignment, reslicing and interpolation in 3-dimensional image processing exerted, at most, trivial distortion on the estimates of actual object volumes.

Morphological study of epiretinal membrane following posterior penetrating injury in the monkey eye.

Posterior vitreous detachment (PVD) and epiretinal membranes occur in a number of vitreoretinal diseases. We have developed an experimental model in which we can provide the morphologic correlation of these dynamic processes. The method provides the opportunity to study epiretinal membrane formation with the scanning electron microscope (SEM); with SEM, some epiretinal membranes that could not be readily detected either clinically or by routine light microscopy can now be identified and studied in detail. We performed an experimental posterior penetrating injury with injection of autologous whole blood or blood and lens material into the vitreous. Five eyes with posterior vitreous detachment but no retinal detachment were selected for SEM. A reduction in the cortical vitreous filaments and the presence of epiretinal membranes was apparent with SEM. In most areas the epiretinal membranes were separated from the internal limiting membrane by a narrow cleft; however, limited attachment sites between the epiretinal membranes and retina were observed in areas overlying retinal blood vessels. In two eyes we observed microscopic retinal folds beneath the membranes, demonstrating a possible morphologic correlation between epiretinal cellular contraction and traction on the retina.