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Embryopathies that develop as a consequence of maternal diabetes have been studied intensely in both experimental and clinical scenarios. Accordingly, hyperglycaemia has been shown to downregulate the expression of elements in the non-canonical Wnt-PCP pathway, such as the Dishevelled-associated activator of morphogenesis 1 (Daam1) and Vangl2. Daam1 is a formin that is essential for actin polymerization and for cytoskeletal reorganization, and it is expressed strongly in certain organs during mouse development, including the eye, neural tube and heart. Daam1gt/gt and Daam1gt/+ embryos develop ocular defects (anophthalmia or microphthalmia) that are similar to those detected as a result of hyperglycaemia. Indeed, studying the effects of maternal diabetes on the Wnt-PCP pathway demonstrated that there was strong association with the Daam1 genotype, whereby the embryopathy observed in Daam1gt/+ mutant embryos of diabetic dams was more severe. There was evidence that embryonic exposure to glucose in vitro diminishes the expression of genes in the Wnt-PCP pathway, leading to altered cytoskeletal organization, cell shape and cell polarity in the optic vesicle. Hence, the Wnt-PCP pathway appears to influence cell morphology and cell polarity, events that drive the cellular movements required for optic vesicle formation and that, in turn, are required to maintain the fate determination. Here, we demonstrate that the Wnt-PCP pathway is involved in the early stages of mouse eye development and that it is altered by diabetes, provoking the ocular phenotype observed in the affected embryos.

We investigated the photocurrents from isolated rods of the South American anuran, Caudiverbera caudiverbera. Rod outer segments were on average 66.4 ± 11.2 μm (mean ± S.D., n = 104) in length and 6.6 ± 0.9 μm (mean ± S.D.) in diameter; 40 ± 22 photoisomerizations (mean ± S.D., range 10–99, n = 16) were required for eliciting a half-saturating photocurrent response. The time-to-peak was 911 ± 217 ms (mean ± S.D., n = 14, 20°C) in the linear range of the response and the integration time of the current response was 1744 ± 451 ms (mean ± S.D., n = 14). The time-to-peak appears to be slower and the integration time shorter in Caudiverbera than in Ambystoma tigrinum, Rana pipiens or Xenopus laevis rods under similar experimental conditions. The α-band of rod spectral sensitivity has a λmax at 520 ± 2.1 nm (mean ± S.D., range 516–525 nm, n = 24) and the bandwidth fits a porphyropsin visual pigment. The single-event response amplitude ranges from 0.31–0.51 pA, depending on the calculation method. The intrinsic dark current (variance at dark minus variance under bright light) was 0.045 ± 0.040 pA2 (mean ± S.D., n = 24). Our results support the presence of a dark-noise component below 1 Hz, with kinetics similar to the single-photon evoked response and a rate of 0.006 events s−1 (n = 9).