Spatio-temporal expression profile of Mettl3/Mettl14 during mouse retina development / Perfil de expresión espacio-temporal de Mettl3 / Mettl14 durante el desarrollo de la retina del ratón

SUMMARY: The Mettl3/Mettl14 methyltransferase complex installs the most ubiquitous internal mRNA modification- N6-methyladenosine (m6A). The vertebrate retina development is a multi-step process that requires fine-tuning of multiple cellular events, but very little is known about the potential function of Mettl3 and Mettl14 in this process. In this study, we demonstrated the spatio-temporal expression of Mettl3 and Mettl14 during retina development in mouse by quantitative PCR and immunofluorescence staining. We found that these two components of methyltransferase complex could be detected from the beginning of retina development; and the expression of Mettl3 and Mettl14 were gradually restricted to inner nuclear layer (INL) and ganglion cell layer (GCL); Double labeling showed that Mettl3 and Mettl14 had similar expression patterns in mature retinal INL and GCL. Overall, our spatio-temporal expression data provided the foundation for future research on the function of m6A modification in the retina development.

RESUMEN: El complejo Mettl3 / Mettl14 metiltransferasa establece la modificación interna más significativa de ARNm: N6- metiladenosina (m6A). El desarrollo de la retina de los vertebrados es un proceso de varios pasos que requiere múltiples eventos celulares; existe muy poca información sobre la función potencial de Mettl3 y Mettl14 en este proceso. En este estudio, demostramos la expresión espacio-temporal de Mettl3 y Mettl14 durante el desarrollo de la retina en ratón mediante PCR cuantitativa y tinción de inmunofluorescencia. Descubrimos que estos dos componentes del complejo de metiltransferasa podían ser detectados desde el comienzo del desarrollo de la retina; la expresión de Mettl3 y Mettl14 se restringió gradualmente a la capa nuclear interna (INL) y la capa de células ganglionares (GCL); se observó que Mettl3 y Mettl14 tenían patrones de expresión similares en INL y GCL retinianos maduros. En general, nuestros datos de expresión espacio-temporal proporcionan información para futuras investigaciones sobre la función de la modificación de m6A en el desarrollo de la retina.

Apoptosis durante el desarrollo embrionario de la retina de tortuga (Trachemys scripta elegans) / Apoptosis in turtle embryonic retina (Trachemys scripta elegans)

La apoptosis o muerte celular programada es un proceso que ocurre durante el desarrollo del sistema nervioso. El objetivo de este estudio fue observar los patrones de apoptosis que se producen durante el desarrollo embrionario de la retina, desde el estadio S16 al momento del nacimiento, mediante miscoscopía óptica y electrónica. Se utilizaron retinas de embriones de tortuga. Nuestros datos muestran que los primeros signos de apoptosis comienzan en el estadio S16, en la capa nuclear interna y alcanzan su máxima densidad tanto en la capa nuclear interna como en la capa de células ganglionares en S20, para extinguirse, prácticamente, en el momento del nacimiento. Por otra parte, la apoptosis sigue un gradiente centro-periferia.

Apoptosis or programmed cell death is a process that occurs during development of the nervous system. The aim of this study was to observe the patterns of apoptosis that occur during embryonic development of the retina from the stage S16 at birth, by light and electron miscoscopia. Turtle embryonic retinas were used for the study. Our data show that the first signs of apoptosis begins at stage S16 in the inner nuclear layer and reaches maximum density both in the inner nuclear layer and the ganglion cell layer in S20 until they practically disappear at the time of birth. Furthermore, apoptosis follows a gradient center-periphery.

Mobile phone radiations, possible disruptor to early retinal development

This study was conducted with an objective to investigate the effects of mobile phone induced radiations on retinal morphogenesis of chick embryo. Experimental Study. This study was conducted at Anatomy department, Regional Centre, College of Physicians and Surgeons Pakistan, Islamabad from Jan. 2006 to Jan. 2007. Chicken embryos were exposed to mobile phone silent mode ringing by placing a GSM operated phone in the centre of the fertilized eggs developing in the incubator. This phone was ringed upon for 15 minutes twice daily for one experimental subgroup and 25 minutes twice for the other subgroup. The control and experimental groups were sacrificed at the end of 10 post incubation days. The retinae of the embryos were dissected out and statistically compared for the heights of different retinal layer after paraffin processing of sections. For lower dosage [15 minutes of ringing] of mobile phone induced EMFs. Thickness of the rods and cones layer and inner plexiform layer of the treated subgroup was significantly less than the control. On increasing the dosage to 25 minutes, thickness of the pigment epithelial layer of the treated group was significantly more than the control group. All the other layers were more in thickness in this subgroup but this difference was not statistically significant. The results of the study conclude that mobile phone radiations have a dose dependant regulatory effect on the early developmental process of chick embryo retina. EMFs dose Mobile phone induced EMFs disrupt the developmental process of embryonal retinogenesis. This effect is influenced differently at different levels exposure

Neurochemical phenotype and birthdating of specific cell populations in the chick retina

The chick embryo is one of the most traditional models in developing neuroscience and its visual system has been one of the most exhaustively studied. The retina has been used as a model for studying the development of the nervous system. Here, we describe the morphological features that characterize each stage of the retina development and studies of the neurogenesis period of some specific neurochemical subpopulations of retinal cells by using a combination of immunohistochemistry and autoradiography of tritiated-thymidine. It could be concluded that the proliferation period of dopaminergic, GABAergic, cholinoceptive and GABAceptive cells does not follow a common rule of the neurogenesis. In addition, some specific neurochemical cell groups can have a restrict proliferation period when compared to the total cell population.

O embrião de galinha é um dos mais tradicionais modelosde estudos da neurociência do desenvolvimento e seu sistema visual tem sido um dos mais exaustivamente estudado. Aretina tem sido utilizada como modelo para estudar o desenvolvimento do sistema nervoso. Aqui, nós descrevemos as características morfológicas que caracterizam cada estádio da retina em desenvolvimento e os estudos do período de neurogênese de algumas subpopulações de células neuroquímicamente específicas da retina usando uma combinação de imunohistoquímica e autoradiografia de timidina-tritiada. Conclui-se que o período de proliferação das células dopaminérgicas, GABAérgicas, colinoceptivas e GABAceptivas não segue uma regra comum. Além disso, alguns grupos celulares neuroquimicamente distintos podem ter um período de proliferaçãomais restrito quando comparado ao da população total destas células.

Disfuncionalidad neuronal y psicomotora como resultado del retraso del tratamiento de la ambliopía / Neuronal and psychomotor malfunction secondary to delayed amblyopia treatment

BACKGROUND: A review of neuronal and psychomotor alterations related to delay of amblyopia treatment was carried out. METHODS: We reviewed various studies to explain the anomalies of visual cortex because of the prevalence of anomalous stimulus in patients with amblyopia. RESULTS: Visual pathways are developed embryologically. The newborn has ocular dominance columns ready to be stimulated, but visual alterations present at this time will generate neuronal changes in visual cortex. CONCLUSIONS: Delay of amblyopia treatment with anomalous visual stimulus will provoke organic changes in visual cortex, inducing alterations of brain functions depending on binocularity. Memory and learning have also been related to this condition.

Immunoreactivity of Constitutive and Inducible Heat Shock Protein 70 in Human Fetal Retina

The purpose of this study was to measure the level of expression of the inducible heat shock protein70 (Hsp70), the constitutive heat shock protein70 (Hsc70) in the outer nuclear layer and the photoreceptors in the human fetal retina. Fetal eyeballs were selected from fetal autopsy specimens of 12 and 17 to 40 week old fetuses, with no history of congenital anomalies. The retinas had differentiated from neuroblastic cells, into matured sensory retinas, from a gestational age (GA) from 12 to 36 weeks. The Hsp70 and Hsc70 were prominently expressed in the nuclear layers. The Hsc70 was expressed at all GAs and the Hsp70 was expressed from 20 to 33 weeks GA. This period is in accordance with the maturation of the sensory retina. The expression of heat shock protein may be regulated by the development of the fetus, and play an important role in the ocular development.

Inhibition of carbachol-induced inositol phosphate accumulation in the embryonic retina promoted by kainate and veratridine

In the present study, we report that low concentrations of the glutamate ionotropic agonist kainate decreased the turnover of [3H]-phosphoinositides ([3H]-InsPs) induced by muscarinic receptors in the chick embryonic retina. When 100 muM carbachol was used, the estimated IC50 value for kainate was 0.2 muM and the maximal inhibition of ~50 percent was obtained with 1 muM or higher concentrations of the glutamatergic agonist. Our data also show that veratridine, a neurotoxin that increases the permeability of voltage-sensitive sodium channels, had no effect on [3H]-InsPs levels of the embryonic retina. However, 50 muM veratridine, but not 50 mM KCl, inhibited ~65 percent of the retinal response to carbachol. While carbachol increased [3H]-InsPs levels from 241.2 + 38.0 to 2044.5 + 299.9 cpm/mg protein, retinal response decreased to 861.6 + 113.9 cpm/mg protein when tissues were incubated with carbachol plus veratridine. These results suggest that the accumulation of phosphoinositides induced by activation of muscarinic receptors can be inhibited by the influx of Na+ ions triggered by activation of kainate receptors or opening of voltage-sensitive sodium channels in the chick embryonic retina.

Doenças do corpo vítreo, retina e uveíte / Vitreous, retina and uveites

Este capítulo trata de problemas do corpo vítreo, problemas da retina e de uveítes, iniciando com noçöes de Embriologia e com a descriçäo do fundo de olho normal.

Effect of oxytetracycline on the developing retina of the chick embryo

In the present work fifty fresh fertile fayoumy eggs were used, 20 eggs were used as control and 30 eggs were injected with [1mg/embryo] of oxyteracycline on the 5 th day of incubation. The embryos were extracted on the 10 th, 12 th and 15 th days of incubation. Oxytetracyclines caused retatdation of grwth of the retina in 10 and 12 days treated chick embryos as evidenced by reduction of the size of the retina associated with disappearance of some layers of it the treated embryos showed signs of incomplete regeneration when examined on the 15 th day of incubation

A Histochemical Study of Cholinesterase Activity in Rabbit's Retinae

In the present study the specific and nonspecific cholinesterase activities of the rabbit's retinae in the fetus, the neonatal, the light-isolated, and the reopened group, which consisted of 65 healthy young rabbits, weighing about 300 to 500 gm, 33 rabbit's fetuses, and neonatal rabbits, were histochemically ovserved by means of the cholinesterase method recommended by Gerebtzoff (1953) and the embedding and sectioning method pesented by Koelle and Friedenwald (1950). Cholinesterase activity of the retinae in the 15 days fetuses was not present but began to develop in the 20 days fetuses. In the 1 week group after suturing the eyelids, the most remarkable activity of specific and nonspecific cholinesterase was observed in the posterior polar area. The nearer to the peripheral area of the retina the weaker the enzymetic activities became. In the 2 weeks group after suturing eyelids, the enzymatic activity was reduced. In the 4, and 8weeks groups after suturing the eyelides, the enzymatic activities were remarkably reduced. In the l4 days after reopening eyelide, which group has previously been kept under the condition of light isolation for 4 weeks, enzymatic activities were fairly recovered and compared with the normal control group. Consequently it is histochemically deduced that the gradual change of specific cholinesterase activities in the rabbit's retinae was closely related to the visual function.