Cone and rod photoreceptor transplantation in models of the childhood retinopathy Leber congenital amaurosis using flow-sorted Crx-positive donor cells

Retinal degenerative disease causing loss of photoreceptor cells is the leading cause of untreatable blindness in the developed world, with inherited degeneration affecting 1 in 3000 people. Visual acuity deteriorates rapidly once the cone photoreceptors die, as these cells provide daylight and colour vision. Here, in proof-of-principle experiments, we demonstrate the feasibility of cone photoreceptor transplantation into the wild-type and degenerating retina of two genetic models of Leber congenital amaurosis, the Crb1rd8/rd8 and Gucy2e−/− mouse. Crx-expressing cells were flow-sorted from the developing retina of CrxGFP transgenic mice and transplanted into adult recipient retinae; CrxGFP is a marker of cone and rod photoreceptor commitment. Only the embryonic-stage Crx-positive donor cells integrated within the outer nuclear layer of the recipient and differentiated into new cones, whereas postnatal cells generated a 10-fold higher number of rods compared with embryonic-stage donors. New cone photoreceptors displayed unambiguous morphological cone features and expressed mature cone markers. Importantly, we found that the adult environment influences the number of integrating cones and favours rod integration. New cones and rods were observed in ratios similar to that of the host retina (1:35) even when the transplanted population consisted primarily of cone precursors. Cone integration efficiency was highest in the cone-deficient Gucy2e−/− retina suggesting that cone depletion creates a more optimal environment for cone transplantation. This is the first comprehensive study demonstrating the feasibility of cone transplantation into the adult retina. We conclude that flow-sorted embryonic-stage Crx-positive donor cells have the potential to replace lost cones, as well as rods, an important requirement for retinal disease therapy

Electron Spin Polarization in Resonant Interband Tunneling Devices

We study spin-dependent interband resonant tunneling in double-barrier InAs/AlSb/ GaMnSb heterostructures. We demonstrate that these structures can be used as spin filters utilizing spin-selective tunneling of electrons through the light-hole resonant channel. High densities of the spin polarized electrons injected into bulk InAs make spin resonant tunneling devices a viable alternative for injecting spins into a semiconductor. Another striking feature of the proposed devices is the possibility of inducing additional resonant channels corresponding to the heavy holes. This can be implemented by saturating the in-plane magnetization in the quantum well.Comment: 11 pages, 4 eps figure

Efecto de la adición de enzimas sobre el valor nutritivo de seis diferentes variedades de altramuz

An experiment was conducted to study the effect on chick performance of crude enzyme preparations when added to diets containing six different cultivars of lupin (Lupinus albus L.) seed grown in Canada. The lupin cultivars studied were Pnognus, NL, LAD, Hutterite, Amiga and Brandon. The total alkaloid content of these cultivars was 0.01, 0.02, 0.01, 0.04, 0.01 and 1.42%, respectively. The weight gain and feed consumption of the birds fed the high alkaloid content were reduced significantly (PSe ha realizado una prueba experimental en pollos con el objetivo de estudiar el efecto sobre los índices productivos de la inclusión de un complejo enzimático en raciones que contenían seis variedades distintas de altramuz (Lupinus albus L.). Se estudiaron las variedades canadienses Pnognus, NL, LAD, Hutterite, Amiga y Brandon, con un contenido total en alcaloides de 0,01, 0,02, 0,01, 0,04, 0,01 y 1,42%, respectivamente. La inclusión en las raciones de variedades con alto contenido en alcaloides producía una reducción (