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Comparative Study of the Primate Retina
Published in Jon H. Kaas, Christine E. Collins, The Primate Visual System, 2003
One of the most interesting results of comparative studies about the primate visual system was the discovery by John Mollon, James Bowmaker, and Gerald Jacobs that platyrrhines, in contrast to catarrhines, have several normal color vision pheno-types.5 Together with a chromosome 7 gene that codes the S-cone opsin, several diurnal platyrrhines possess a single locus in the X chromosome that codes for M-or L-cone opsins. However, due to the existence of a polyallelism of the X chromosome opsin gene, there are several possible color vision phenotypes. All males and some females are dichromats, whereas the majority of females are trichromats. The number of di- and trichromatic phenotypes, as well as the proportion of females that are di- or trichromats, depends on the number of alleles present in the population. In some platyrrhines, such as Ateles, there are only two alleles; in others such as Cebus, Saimiri, Callithrix, and Saguinus, there are three alleles; whereas in some others, such as Callicebus, there are up to five alleles (reviewed by Jacobs6). There is at least one exception to this pattern among diurnal platyrrhines. The Alouatta has color vision similar to catarrhines, with two loci in the X chromosome coding M and L opsins, respectively, and a single allele for each locus.67× Another exception is the nocturnal, monochromatic Aotus. It lacks a functioning gene on chromosome 7 and has a single allele for the X chromosome, coding for a M-cone opsin.6,8
RPE-derived exosomes rescue the photoreceptors during retina degeneration: an intraocular approach to deliver exosomes into the subretinal space
Published in Drug Delivery, 2021
Yange Wang, Qian Zhang, Guoqing Yang, Yuanmeng Wei, Miao Li, Enming Du, Haijun Li, Zongming Song, Ye Tao
Since the ERG data demonstrated critical improvement in the photopic vision RPE-Exos treated mice, we performed immunostaining experiments to examine the cone survival in these retinas (Figure 3(D)). Extensive punctate PNA staining was detected in the retinal sections of the RPE-Exos treated group, indicating a substantial cone photoreceptors were preserved by RPE-Exos treatment. In the retinal sections of MNU group, no PNA staining was found since the outer and inner segments of the cone photoreceptors were severely disrupted. Furthermore, the viability of M- and S-cone subtypes was assessed using opsin antibodies. Abundant M- and S-cone opsin staining was found in the retinal sections of RPEs-Exos treated group. Conversely, these cone opsin staining disappeared in the vehicle treated group. These data indicated that the RPEs-Exos conferred extensive benefits on the M- and S-cone photoreceptors.
RPGR gene therapy presents challenges in cloning the coding sequence
Published in Expert Opinion on Biological Therapy, 2020
Cristina Martinez-Fernandez De La Camara, Jasmina Cehajic-Kapetanovic, Robert E. MacLaren
The codon optimized vector synthetized by Aguirre and collaborators (patent publication US20150353938A1) is very similar to the codon optimized sequence produced by Fischer and colleagues. This vector was validated in a large animal model of RPGR-XLRP [38]. The subretinal injection of codon optimized vector in RPGR mutant dogs provided a long-term rescue of both rod- and cone-mediated vision as shown in ERG measurements and visual behavioral studies. The treatment with this gene therapy vector also rescued photoreceptor morphology and reduced the mislocalization of the rod and the medium/long wavelength (M/L) cone opsin. These results together support the use of codon optimized RPGR sequences in clinical trials and it is difficult to see how they would not have a good chance of long-term success in humans. Both vectors are currently being tested in Phase I/II clinical trials.
Intranasal administration of erythropoietin rescues the photoreceptors in degenerative retina: a noninvasive method to deliver drugs to the eye
Published in Drug Delivery, 2019
Ye Tao, Chong Li, Anhui Yao, Yingxin Qu, Limin Qin, Zuojun Xiong, Jianbin Zhang, Weiwen Wang
In greater detail, the viability of different cone populations was examined using opsin-specific antibodies. As shown in the retinal sections, both M- and S-opsin positive cells in the MNU group were lost. On the other hand, the positive M-opsin and S-opsin positive cells were evident in the retinal sections of the INas administered group, although with a delayed manner relative to the normal controls. The M-opsin and S-opsin staining in the retinal sections of the IVen administered group were weaker compared with the INas administered group. The average number of M-cone opsin-positive cells in the INas group and IVen administered group was respectively 43.0% and 23.6% of that in the normal control (Table 1); the average number of S-cone opsin–positive cells in the INas and IVen administered group was 51.9% and of 34.2% respectively, of that in the normal control. In the INas administered group, both the M- and S-cone opsin–positive cells were distributed throughout the retinal whole-mount. However, the distribution was not uniformly equal and formed a topographic gradient across retina: most of the M-opsin positive cells located in the DT quadrants, and the fewest in the VN quadrant; most of the S- opsin positive cells located in the VN quadrants, and the fewest in the DT quadrant. These findings suggested the M-cone, and S-cone populations were both amenable to the INas administration of EPO. In particular, the M-cone photoreceptors in the DT quadrant and S- cone photoreceptors in the VN quadrant benefited most from the EPO therapy.