Inner Nuclear Layer Of Retina Research Articles

Methylmercury induces ectopic expression of complement components and apoptotic cell death in the retina of the zebrafish embryo

Methylmercury (MeHg) is a well-known neurotoxin of humans and wildlife. Visual impairments, including blindness, are frequently present in human patients with MeHg poisoning and in affected animals. It is widely assumed that MeHg-induced damage to the visual cortex is the sole or primary cause of vision loss. MeHg has been shown to accumulate in the outer segments of photoreceptor cells, and to alter the thickness of the inner nuclear layer of the fish retina. However, it is unclear whether the bioaccumulated MeHg has direct deleterious effects on the retina. Herein we report that the genes encoding complement components 5 (c5), c7a, c7b, and c9 were ectopically expressed in the inner nuclear layer of the retinas of zebrafish embryos exposed to MeHg (6–50 μg/L). The numbers of apoptotic cell deaths scored in the retinas of MeHg-treated embryos significantly increased in a concentration-dependent manner. In comparison with cadmium and arsenic, ectopic expression of c5, c7a, c7b, and c9, and the observed apoptotic cell death in the retina were specific to MeHg exposure. Our data provide evidence supporting the hypothesis that MeHg has deleterious impacts on the retinal cells, especially the inner nuclear layer. We propose that MeHg-induced retinal cell death may trigger the activation of the complement system.

Glutathione Coating of Liposomes Enhances the Delivery of Hydrophilic Cargo to the Inner Nuclear Layer in Retinal Cultures.

To successfully deliver intracellular compounds to retinal cells, a delivery system based on purified lipids, self-assembled into synthetic vesicles called liposomes, can be used. Liposomes have the potential to target distinct tissues and cells in the body by molecular targeting moieties conjugated to their surface. To enhance liposome delivery to neurons, glutathione has formerly been used as targeting moiety. It is unclear whether and how the glutathione conjugation improves the liposome-induced uptake to cells within the retina. To explore this, glutathione-liposomes were prepared and loaded with a fluorescent tracer, which was added to organotypic retinal explant cultures derived from mice. The fluorescence in the tissue was analyzed from histological sections using fluorescent microscopy. Comparisons were done with liposomes without a targeting device and cysteine-conjugated liposomes. A significant increase (p≤0.05) of fluorescent signal was observed from the inner nuclear layer of retinas exposed to glutathione-conjugated liposomes. Qualitatively, this might be attributed to the accumulation of glutathione-liposomes in the retinal inner vasculature, but further studies are needed for verification.

Primary Cilia in Amacrine Cells in Retinal Development.

PurposePrimary cilia are conserved organelles found in polarized cells within the eye that regulate cell growth, migration, and differentiation. Although the role of cilia in photoreceptors is well-studied, the formation of cilia in other retinal cell types has received little attention. In this study, we examined the ciliary profile focused on the inner nuclear layer of retinas in mice and rhesus macaque primates.MethodsRetinal sections or flatmounts from Arl13b-Cetn2 tg transgenic mice were immunostained for cell markers (Pax6, Sox9, Chx10, Calbindin, Calretinin, ChaT, GAD67, Prox1, TH, and vGluT3) and analyzed by confocal microscopy. Primate retinal sections were immunostained for ciliary and cell markers (Pax6 and Arl13b). Optical coherence tomography (OCT) and ERGs were used to assess visual function of Vift88 mice.ResultsDuring different stages of mouse postnatal eye development, we found that cilia are present in Pax6-positive amacrine cells, which were also observed in primate retinas. The cilia of subtypes of amacrine cells in mice were shown by immunostaining and electron microscopy. We also removed primary cilia from vGluT3 amacrine cells in mouse and found no significant vision defects. In addition, cilia were present in the outer limiting membrane, suggesting that a population of Müller glial cells forms cilia.ConclusionsWe report that several subpopulations of amacrine cells in inner nuclear layers of the retina form cilia during early retinal development in mice and primates.

Metabolic Syndrome Triggered by Fructose Diet Impairs Neuronal Function and Vascular Integrity in ApoE-KO Mouse Retinas: Implications of Autophagy Deficient Activation.

Metabolic syndrome is a disorder characterized by a constellation of clinical findings such as elevated blood glucose, hyperinsulinemia, dyslipidemia, hypertension, and obesity. A positive correlation has been found between metabolic syndrome or its components and retinopathy, mainly at microvascular level, in patients without a history of diabetes. Here, we extend the investigations beyond the vascular component analyzing functional changes as well as neuronal and glial response in retinas of Apolipoprotein E knockout (ApoE-KO) mice fed with 10% w/v fructose diet. Given that autophagy dysfunction is implicated in retinal diseases related to hyperglycemia and dyslipidemia, the activation of this pathway was also analyzed. Two months of fructose intake triggered metabolic derangements in ApoE-KO mice characterized by dyslipidemia, hyperglycemia and hyperinsulinemia. An increased number of TUNEL positive cells, in addition to the ganglion cell layer, was observed in the inner nuclear layer in retina. Vascular permeability, evidenced by albumin–Evans blue leakage and extravasation of albumin was also detected. Furthermore, a significant decrease of the glial fibrillary acidic protein expression was confirmed by Western blot analysis. Absence of both Müller cell gliosis and pro-angiogenic response was also demonstrated. Finally, retinas of ApoE-KO FD mice showed defective autophagy activation as judged by LC3B mRNA and p62 protein levels correlating with the increased cell death. These results demonstrated that FD induced in ApoE-KO mice biochemical alterations compatible with metabolic syndrome associated with neuronal impairment and mild vascular alterations in the retina.

The influence of human umbilical cord mesenchymal stem cells transplanted into the tail vein of diabetic rats on apoptosis of retinal neurons and the retinal expression of glial fibrillary acidic protein

Objective To observe the influence of human umbilical cord mesenchymal stem cells(hUCMSC) transplanted into the tail vein of diabetic rats on apoptosis of retinal neurons and the retinal expression level of glial fibrillary acidic protein (GFAP). Methods Seventy clean male Sprague-Dawley rats were randomly divided into the normal control group (group A), diabetes mellitus (DM) only group (group B), DM + balanced salt solution (BSS) group (group C), DM + hUCMSC group (group D), with 10 rats in each group. DM rats were induced by intraperitoneal injection of streptozotocin. Apoptosis of retinal cells was assayed by dUTP nick end labeling. Immunohistochemistry and Western blot was performed to detect the retinal expressions of GFAP in rats. Results Compared with group A, large numbers of apoptotic cells could be found in the retinal ganglion cell layer (GCL) and inner nuclear layer (INL) of group B and group C, however the apoptotic cells in group D were significantly reduced than group B and C. The expression of GFAP was mainly located in the retinal GCL and retinal nerve fibre layer (RNFL) in group A, throughout the inner plexiform layer(IPL) in group B and C, only distributed in RNFL and GCL in group D. It was obvious that the expression of GFAP in group B and C was higher than group A. Compared with group B and C, the expression of GFAP in group D was significantly reduced. The difference of GFAP expression among the 4 groups was significant(F=79.635, P<0.05). Conclusion hUCMSC could inhibit the apoptosis of retinal cells and activation of glial cells in early DM rats. Key words: Diabetic retinopathy; Mesenchymal stem cells; Neurons; Apoptosis

Early changes in retinal structure and BMP2 expression in the retina and crystalline lens of streptozotocin-induced diabetic pigs

PurposeThis study aims to evaluate early changes in retinal structure and BMP2 expression in the retina and crystalline lens by comparing streptozotocin-induced diabetic pigs and normal control group pigs.MethodsFive eye samples from five diabetic Micro-pigs (Medikinetics, Pyeongtaek, Korea) and five eye samples from five control pigs bred in a specific pathogen-free area were used. Diabetes was developed through intravenous injection of nicotinamide and streptozotocin, and the average fasting glucose level was maintained at 250 mg/dL or higher for 16 weeks. To evaluate BMP2 expression in the retina and crystalline lens, Western blotting was performed.ResultsIn Hematoxylin and Eosin staining, most diabetic pigs showed structural abnormalities in the inner plexiform layer. The number of nuclei in the ganglion cell layer within the range of 104 μm2 was 3.78±0.60 for diabetic pigs and 5.57±1.07 for control group pigs, showing a statistically significant difference. In immunohistochemical staining, diabetic retinas showed an overall increase in BMP2 expression. In Western blotting, the average BMP2/actin level of diabetic retinas was 1.19±0.05, showing a significant increase compared to the 1.06±0.03 of the control group retinas (P=0.016). The BMP2/actin level of diabetic crystalline lenses was similar to the control group crystalline lenses (P=0.730).ConclusionsCompared to control group pigs, the number of nuclei in the inner nuclear layer of retinas from streptozotocin-induced diabetic pigs decreased, while an increase in BMP2 expression was observed in the retina of diabetic pigs.

Comparison of Cell and Nuclear Size Difference between Diploid and Induced Triploid in Marine Medaka, Oryzias dancena.

The influence of triploidization on cell and nucleus size characteristics of the same tissues of erythrocyte, retina, kidney, hepatocyte and midgut epithelium in marine medaka, Oryzias dancena has been determined histologically. Induced triploid fish are produced by cold shock treatments. Likewise, the size of horizontal cell nucleus in inner nuclear layer of retina, ganglion cell nucleus in ganglion cell layer of retina, proximal tubule cell of kidney, hepatocytes and nuclear height of midgut epithelium all appear to be significantly larger than diploid (p<0.05). On the other hand, retina thickness is larger in diploid than induced triploid (p<0.05). Induced triploid shows low density of cell number. Results of this study suggest that same characteristics in the induced triploid exhibiting larger cells and nucleus sizes with fewer number of cells than the diploid can be useful criteria for the distinction between diploid and induced triploid, and also the ploidy level in marine medaka.

The antioxidant effect of grape seed proanthocyanidin extracts on diabetic retinopathy and its mechanism

Background The pathogenesis of diabetic retinopathy (DR) might be related with oxidative stress and its mechanism has not been fully elucidated.Grape seed proanthocyanidin extracts (GSPE),a powerful antioxidant,plays roles in some systemic diseases.However,the effect and mechanism of GSPE in DR has not been illuminated clearly.Objective This study was to investigate whether GSPE has a protective effect on the retinas of diabetic subjects and explore its mechanism.Methods Thirty SPF adult Wistar rats were divided into the control group,diabetic group and diabetes + GSPE group according to the randomized number table.Diabetic models were induced by intraperitoneal injection of 100 mg/kg strebtozotocin (STZ) prepared with citrate buffer,and only the equal amount of citrate buffer was used in the same way in the control group.GSPE solution was intragastrally used 250 mg/kg daily in the rats of the diabetes+GSPE group from injective day through 8 weeks,and distilled water was used in the same way in the rats of the control and diabetic groups.The rats were sacrificed in the eighth week after injection and the retinas were isolated.The morphology of the retina were examined by hematoxylin and eosin stain.Retinal homogenatewas prepared for the assay of superoxide dismutase (SOD),glutathione peroxidase (GSH-Px) activity and malonaldehyde (MDA) content.The expressions and location of nuclear erythroid related factor 2 (Nrf2) was determined by immunochemistry,and the expressions of Nrf2 and heme oxygenase-1 (HO-1) were quantitatively analyzed by Western blot.The apoptosis of retinal cells was detected by TUNEL.Results In the eighth week after modeling,the blood glucose levels were significantly higher and the body weight was lower in the rats of the diabetic group and diabetes+GSPE group compared with the control group (all at P＜0.01).Retinal structure was normal in the rats of the control group.However,loose tissue,irregular arrangement of cells and thickness decrease of retinal fiber layer,retinal ganglion cell layer and inner plexiform layer were exhibited in the rats of the diabetic group,while the morphology abnormality was slight in the rats of the diabetes+GSPE group.The SOD and GSH-Px activities and MDA content were significantly different among the 3 groups (F =11.010,P =0.001 ; F =12.072,P =0.000 ; F =25.224,P=0.000),and activities of SOD and GSH-Px in the retinas were significantly lower,and the MDA level was higher in the rats of diabetic group than those of the diabetes+GSPE group and the control group (all at P＜0.01).The relative expressing levels of Nrf2 were (165.5±29.4) ％ and (134.8 ±7.8) ％ in the diabetes+ GSPE group and diabetic group,with a significant difference between them (t=2.450,P=0.044).Compared with the diabetic group,the expressing level of the HO-1 was sigficantly increased ([170.2±22.0)％ versus [125.3±9.2] ％,t =2.360,P =0.002).TUNEL showed that the retinal apoptotic cells of diabetic rats were mainly located in the retinal fiber layer,RGCs layer,inner and outer nuclear layer,and the number of apoptotic cells was less in the diabetes+GSPE group compared with the diabetic group under the fluorescence microscope.Conclusions GSPE can play a protective role on diabetic rats by activating Nrf2 pathway and therefore improving retinal oxidative stress and decreasing apoptosis. Key words: Diabetes/complication; Retinopathy/treatment; Grape seed proanthocyanidin extracts; Nuclear erythroid related factor 2 ; Oxidative stress; Apoptosis

The neuroprotection of brain-derived neurotrophic factor in experimental retinal detachment reattached

To investigate the effect of exogenous brain-derived neurotrophic factor (BDNF) on the retinal repair after experimental retinal detachment (RD) reattached. Experimental study. Forty-eight normal rats were randomly divided into four groups:BDNF group, control group, RD reattached group and normal group. In order to detect the effects of BDNF on retinal degeneration caused by RD, the morphology of retina and the ultrastructure of retinal cells were observed by light microscopy and electron microscopy. The effect of BDNF on the apoptosis of retinal cells after RD reattached was detected by Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) technique. Data were analyzed using one-way analysis of variance (ANOVA) and secondary analysis for significance with independent-samples t-test. The average automatically reattached time was (31.3 ± 3.5) days. Compared with control group, there were less damage in out segment and inner segment, more retinal cells in outer nuclear layer (ONL) and inner nuclear layer (INL), thicker ONL of retina and better organizational structure of retina in BDNF group. The average thickness of ONL and INL of retina were (21.166 ± 3.087) µm, (23.508 ± 3.679) µm respectively in BDNF group, and (16.084 ± 2.928) µm, (12.885 ± 3.070) µm respectively in control group. The thickness of ONL and INL of retina showed a significant difference in BDNF group compared with control (P < 0.01). There were less TUNEL-positive cells in ONL of retina in BDNF group compared with control. This study indicates that the morphology of retina and the ultrastructure of retinal cells have changed, and the apoptosis of retinal cells are present after RD reattached. Exogenous BDNF can reduce retinal cells degeneration and inhibit the apoptosis of retinal cells and have a certain protection effects on the retinal damage caused by RD.

Microcystic Changes in the Retinal Internal Nuclear Layer Associated with Optic Atrophy: A Prospective Study

Purpose. This study aimed at assessing the prevalence of pathologies presenting retinal inner nuclear layer (RINL) microcystic perimacular changes associated with optic nerve atrophy (OA). The charts of patients presenting a significant defect of the Retinal Nerve Fiber Layer (RNFL) were included prospectively in this study. Patients were classified according to the etiology of the RNFL defect. Two hundred and one eyes of 138 patients were enrolled in this analysis. Retinal images obtained showed the typical hyporeflective perifoveal crescent-shaped lesion composed of small round hyporeflective microcysts confined to the RINL in 35.3% of the eyes. Those findings were found in 75% of eyes presenting hereditary OA, 50% of eyes presenting ischemic optic neuritis, 50% of eyes with drusen of the optic nerve (ON), 44.4% of eyes presenting a compressive OA, 32% of eyes presenting inflammatory optic neuropathy from multiple sclerosis, 18.5% of eyes presenting OA from undetermined origin, and 17.6% of eyes having primary open-angle glaucoma. This study demonstrates that microcystic changes in RINL are not specific to a disease but are found in OA of various etiologies. Moreover, their incidence was found to be dependent upon the cause of OA, with the highest incidence occurring in genetic OA.

Chronic hyperglycemia inhibits vasoregression in a transgenic model of retinal degeneration

Vasoregression characterizes diabetic retinopathy in animal models and in humans. We have recently demonstrated that vasoregression is earlier initiated in a rat model of ciliopathy-induced retinal neurodegeneration (TGR rat). The aim was to assess the balance between vasoregressive effects of chronic hyperglycemia and photoreceptor degeneration on adult vascular remodelling. The retinas were analyzed at 4 and 9 months after streptozotocin-induced diabetes. Neurodegeneration was determined by quantitation of cell numbers and retinal layer thickness. Vasoregression was assessed by quantitative retinal morphometry in retinal digest preparations. Retinal VEGF levels were measured by ELISA. Glial activation, expression and location of HSP27 and phosphorylated HSP27 were evaluated by immunofluorescence staining. Unexpectedly, the numbers of acellular capillaries were reduced at both time points and led to fewer intraretinal microvascular abnormalities in late stage diabetic TGR. Concomitantly, inner nuclear layers (INLs) in diabetic TGR rats were protected from cell loss at both time points. Consequently, glial activation was reduced, but VEGF level was increased in diabetic TGR retinas. Expressions of HSP27 were upregulated in glia cells in the preserved INL of diabetic TGR. Chronic hyperglycemia preserves the microvasculature in the retinal model of neurodegeneration. Cell preservation in the retinal INL was associated with protective gene regulation. Together, these data indicate that diabetes can induce vasoprotection, in which retinal glia can play a particular role.

Influence of 460-480 nm wavelength light at three different irradiance on retina tissue of SD rats

To investigate the survival of SD rat retinal cells after irradiated with 460-480 nm wavelength blue light at three different irradiance. Experimental study. Seventy-six SD rats six weeks old were divided into control group (4 animals) and experimental groups (18 different subgroups) with 4 animals for each group. Healthy SD rats were exposed to the 460-480 nm blue light for 3 or 12 hours on three different irradiance of 0.6, 1.5 and 10.0 W/m(2) respectively. After recovery in darkness for 4 hours, 24 hours or 3 days, retinal tissue was collected after the eyes were enucleated. Hematoxylin-eosin staining was performed to evaluate the general anatomical changes of the rat retinal layers. TdT-mediated dUTP nick-end labeling was performed to detect apoptotic cells and immunofluorescence staining was conducted to illustrate the expression and location of related proteins in Müller cells. The number of ganglion cells was analyzed by one-way ANOVA. No injury was observed in SD rat retina at the irradiance of 0.6 W/m(2). Retinal cells were damaged with irradiance at 10.0 W/m(2), which mainly affected photoreceptors and retinal pigment epithelial cells, while Müller cells of retinal inner nuclear layer were also involved. Apoptosis began after 4 hours of exposure and peaked at 24 hours. Moderate damage of retina was observed at the irradiance of 1.5 W/m(2) after 12 hours rather than 3 hours exposure. The number of ganglion cells was significantly different among the different groups 3 days after exposure. When the exposure time was 3 hours, the number of retinal ganglion cells under different irradiance at 0.0, 0.6, 1.5 and 10.0 W/m(2) was respectively 41.42 ± 0.17, 40.58 ± 0.50, 40.92 ± 0.32 and 22.83 ± 0.79 (F = 1305.86, P = 0.000). When the exposure time was 12 hours, the number of retinal ganglion cells under different irradiance at 0.0, 0.6, 1.5 and 10.0 W/m(2) was respectively 41.42 ± 0.17, 40.83 ± 0.69, 41.08 ± 0.17 and 22.75 ± 0.83 (F = 1095.78, P = 0.000). The number of retinal ganglion cells showed significant decrease 3 days after exposure at the irradiance 10.0 W/m(2) (exposure time 3 h:t = 52.32, P = 0.000; exposure time 12 h:t = 47.58, P = 0.000). The safe exposure time to SD rat retina layers is 12 hours for the blue light with wavelength 460-480 nm at the irradiance 0.6 W/m(2). And the safe exposure time descends to 3 hours at the irradiance 1.5 W/m(2).

Identification of two arylalkylamine N-acetyltranferase 1 genes with different developmental expression profiles in the flatfish Solea senegalensis

The existence of two arylalkylamine N-acetyltransferase 1 (Aanat1) genes in the genome of some teleosts has been reported recently by in silico analysis. However, there are no data concerning the similarities and/or differences between them and many questions remain to be answered, such as their expression sites, development, or kinetics. Here, we report the cloning of Aanat1a and Aanat1b cDNAs from the sole retina and show for the first time that at least three Aanat genes are expressed in a vertebrate species. Because melatonin is involved in fish ontogeny, we analyzed the developmental transcript levels of Aanat1a and Aanat1b by quantitative real-time PCR, showing their inverse and stage-specific expression patterns. Aanat1a was more abundant during early than late larval stages. Before metamorphosis, nocturnal expression was higher. At metamorphosis, Aanat1a expression decreased and lost these day-night variations. In contrast, the abundance of Aanat1b transcripts, low during early developing stages, rose significantly throughout metamorphosis. This situation seemed to apply to the adult because Aanat1a expression was lower than Aanat1b expression in the retina of adults, where the former did not exhibit day-night variations, while the latter did so with much higher nocturnal transcript levels. In situ hybridization analysis detected Aanat1a and Aanat1b messengers in the outer and inner nuclear layers of retina. The differences in abundance and distinct day-night expression patterns between Aanat1a and Aanat1b during sole development suggest different functions for these two enzymes as well as the existence of interactions between the melatoninergic and thyroid hormone systems during flatfish metamorphosis.

A Novel Calpain Inhibitor, ((1S)-1-((((1S)-1-Benzyl-3-cyclopropylamino-2,3-di-oxopropyl)amino)carbonyl)-3-methylbutyl)carbamic Acid 5-Methoxy-3-oxapentyl Ester (SNJ-1945), Reduces Murine Retinal Cell Death In Vitro and In Vivo

We examined whether ((1S)-1-((((1S)-1-benzyl-3-cyclopropylamino-2,3-di-oxopropyl)amino)carbonyl)-3-methylbutyl)carbamic acid 5-methoxy-3-oxapentyl ester (SNJ-1945), a new orally available calpain inhibitor, might reduce retinal cell death in vivo and/or in vitro. Retinal cell damage was induced in vivo in mice by intravitreal injection of N-methyl-d-aspartate (NMDA), and SNJ-1945 was intraperitoneally or orally administered twice. NMDA-induced calpain activity (measured as the cleaved products of alpha-spectrin) and its substrate, p35 (a neuron-specific activator for cyclin-dependent kinase 5), in the retina were examined by immunoblotting. In RGC-5 (a rat retinal ganglion cell line) cell culture, cell damage was induced by a 4-h oxygen-glucose deprivation (OGD) treatment followed by an 18-h reoxygenation period. In mouse retinas, SNJ-1945 (30 or 100 mg/kg i.p., 100 or 200 mg/kg p.o.) significantly inhibited the cell loss in the ganglion cell layer (GCL) and the thinning of the inner plexiform layer induced by NMDA. Furthermore, the number of positive cells for terminal deoxynucleotidyl transferase dUTP nick-end labeling was significantly reduced in the GCL and the inner nuclear layer of retinas treated with SNJ-1945 compared with vehicle-treated retinas 24 h after NMDA injection. Levels of cleaved alpha-spectrin products increased and p35 decreased 6 h after NMDA injection or later, and their effects were attenuated by SNJ-1945. In vitro, SNJ-1945 (10 and 100 muM) inhibited the OGD stress-induced reduction in cell viability. In conclusion, SNJ-1945 may afford valuable neuroprotection against retinal diseases, because it was effective against retinal damage both in vitro and in vivo. Our results also indicate that calpain activation and subsequent p35 degradation may be involved in the mechanisms underlying retinal cell death.

Vsx1 3′ untranlated region-mediated translation difference at differentdevelopmental stages of goldfish embryos

Visual system homeobox-1 (vsx1) is important in retinal progenitor proliferation, differentiation, and function maintenance of bipolar cells in vertebrates. Recent study in Xenopus laevis has shown that vsx1 3' untranslated region (3' UTR) can mediate cell-specific translation of vsx1 mRNA in the bipolar cells of the retinal inner nuclear layer (INL). vsx1 is also transcribed at the early developmental stages prior to eye formation and its spatiotemporal expression patterns are conserved in all the examined vertebrates. In order to determine whether the vsx1 3' UTR has a role in regulating the spatiotemporal expression of vsx1 during early embryogenesis, we constructed a vsx1 UTR-controlled green fluorescent protein (GFP) reporter gene system and examined the GFP expression pattern in goldfish, Carassius auratus, at different developmental stages. Our results indicated that both the vsx1 5' UTR and the vsx1 3' UTR remarkably repressed GFP expression at transcription level but did not regulate tissue-specific translation at early developmental stages. GFP protein was ubiquitously expressed in the embryos injected with GFP-sensors containing vsx1 UTRs before 60 h post-fertilization (hpf). From hatching stage (72 hpf) onwards, however, GFP protein was specifically expressed in the bipolar cells of the retinal INL in the vsx1 3'UTR-GFP-sensor embryos, but was still ubiquitously expressed in the embryos injected with GFP-sensor lacking vsx1 3' UTR. These observations showed a significant difference of vsx1 3' UTR-mediated translation between early and late developmental stages and suggested that vsx1 3' UTR might not be involved in regulating the spatiotemporal expression of vsx1 until hatching stage during embryogenesis.

Characterization and Expression of Serotonin Transporter Genes in Zebrafish

To understand the development of serotonergic neurons in vertebrates, we used zebrafish as a model system. In this study we cloned two cDNAs (complementary DNAs) coding for serotonin transporter (SERT) from the zebrafish, named serta and sertb. The serta cDNA encodes a protein of 693 amino acids and showed high level of sequence identity with rat and human SERTs. In situ hybridization showed serta to be expressed in raphe nuclei, ventral posterior tuberculum and pineal organ. The expression of serta in raphe and ventral posterior tuberculum overlapped with the location of serotonin and expression of tryptophan hydroxylase, which is a key enzyme for serotonin synthesis. In the pineal organ serta is expressed in the cells in the vicinity of tryptophan hydroxylase-positive cells. We also cloned another zebrafish serotonin transporter, sertb, and found to be expressed in the medulla oblongata and in the inner nuclear layer of retina. The existence of two sert genes in the zebrafish genome indicates the gene was duplicated in the process of evolution as can be seen in other genes in the teleosts including zebrafish. The expression of the serta cDNA in cultured cells conferred a serotonin transport activity, thus indicating the validity of the cloned cDNA. We have established the expression system of zebrafish serotonin transporter in the cell culture in the present study, which is useful for the pharmacological analysis to determine the important residues for the interaction with serotonin and inhibitors. The expression system in the cell culture can be used to determine the effective concentration of inhibitors and addictive drugs. These information might be useful to evaluate the effect of those chemicals on serotonin neuron development and behavior of the animal.

Pituitary adenylate cyclase-activating polypeptide (PACAP) can act as determinant of the tyrosine hydroxylase phenotype of dopaminergic cells during retina development

In the chick retina, dopaminergic cells are generated between embryonic days 3 and 7 (E3/E7). However, the expression of tyrosine hydroxylase (TH), the first enzyme in the catecholamine synthetic pathway, is only detected after E11/E12. During the interval comprising E7 to E12, signals conveyed by cAMP are important to determine the TH phenotype. The present study shows that pituitary adenylyl cyclase-activating polypeptide (PACAP), via cAMP, is a major endogenous component in defining the TH phenotype of retina dopaminergic cells during development. PACAP type 1 receptor and its mRNA were detected in retinas since E6. PACAP was also immunodetected in cells localized in the inner nuclear layer of retinas since E8. This peptide promoted greater than 10-fold increase in cAMP accumulation of retinas obtained from embryos since E8, an effect that was blocked by PACAP6-38 (PAC1 receptor antagonist). In cultured retina cells from E8 and E9, maintained for 6 days in vitro with 10 nM PACAP (for 5 days), the number of dopaminergic cells expressing tyrosine hydroxylase increased 2.4-fold. The cAMP analog, 8-Br-cAMP and 3-isobutyl-1-methylxanthine (IBMX, a phosphodiesterase inhibitor) also increased the number of tyrosine hydroxylase-positive cells by 4- to 6-fold. IBMX plus PACAP treatment resulted in 17-fold increase in the number of cells positive for tyrosine hydroxylase. Under this condition the amount of tyrosine hydroxylase expression, as detected by western blot analysis, was also increased. The protein kinase-A inhibitor, rp-cAMPS, significantly reduced the effect of PACAP. Our data show that this peptide is an important factor influencing the definition of the tyrosine hydroxylase phenotype of retina dopaminergic cells within a narrow window of development.

Retina of Vertebrates: An Internal Cell Reserve for Regeneration

The recent data were summarized concerning the presence in the retina of fish, amphibians and birds of additional sources of growth and regeneration, alternative to the already known sources, such as growth zone of eye, pigment epithelium, and cells--precursors of rods, and which are localized in the inner nuclear layer of retina. These sources are represented by as yet not finally identified oval small cells and cells of Muller glia. Both types of cells are capable of proliferating and producing precursors for various differentiated cells, including photoreceptors or their additional precursors. The current immunochemistry data are provided, which were obtained using markers of proliferation, proneural phenotype, and specific cell differentiation in the growing retina and in the retina after various damages. The regulatory mechanisms and methods of the stimulation of proliferation of the cells, which are sources of increase in the number and restoration of photoreceptors, interneurons, and glial cells of vertebrate retina, are discussed.

Quantitative analysis of the organization of the inner nuclear layer of the horse retina.

Four cell types including the bipolar, amacrine, horizontal and Muller cells were investigated quantitatively in the inner nuclear layer of the retina in the horse. Cells were identified on the basis of the morphology and distribution of processes leaving from their somata, cytological features and positional features. The average percentages of the above 4 cell types were 44%, 24%, 1% and 29%, respectively. The average total cell densities in the inner nuclear layer in the visual streak, the nasal and temporal regions, the dorsal and ventral regions of the retina were also estimated. It is expected that the results of this study will supply the basic data for further study of the neural circuits in the horse retina.

Molecular cloning of a mercurial-insensitive water channel expressed in selected water-transporting tissues.

Two mercurial-inhibitable water-transporting proteins have been identified: CHIP28, an erythrocyte water channel also expressed in kidney tubules and selected extrarenal epithelia, and WCH-CD, a kidney collecting duct water channel. In searching for a protein responsible for the high transcellular water permeability in lung alveolus, we cloned a 32-kDa water channel (mercurial-insensitive water channel (MIWC)) from a rat lung cDNA library with several novel features. Water permeability was strongly increased in Xenopus oocytes expressing MIWC in a mercurial-insensitive manner, in contrast to known water channels. By in situ hybridization, MIWC showed an unique distribution in cells that do not express CHIP28, including kidney papillary vasa recta, cells lining the subarachnoid space and ventricles in brain, the inner nuclear layer in retina, and the conjunctival epithelium. An alternatively spliced form of MIWC with a 165-base pair deletion in the coding sequence was also identified; relative expression of the spliced mRNA was tissue-specific. The MIWC water channel may participate in the urinary concentrating mechanism, the absorption of cerebrospinal fluid, and other physiological processes.