Biomedical subjects

Melinda K Duncan

Publications and source records attributed to Melinda K Duncan.

At least 19 recordsLinked to original sources

PubMed2006

Deletion of JAM-A causes morphological defects in the corneal epithelium.

Junctional adhesion molecule-A (JAM-A, JAM-1, F11R) is an Ig domain containing transmembrane protein that has been proposed to function in diverse processes including platelet activation and adhesion, leukocyte transmigration, angiogenesis, epithelial cell shape and endothelial cell migration although its function in vivo is less well established. In the mouse eye, JAM-A protein expression is first detected at 12.5 dpc in the blood vessels of the tunica vasculosa, while it is first detected in both the corneal epithelium and lens between 13.5 and 14.5 dpc. In the corneal epithelium, JAM-A levels remain appreciable throughout life, while JAM-A immunostaining becomes stronger in the lens as the animals age. Both the cornea and lens of mice lacking an intact JAM-A gene are transparent until at least a year of age, although the cells of the JAM-A null corneal epithelium are irregularly shaped. In wild-type mice, JAM-A protein is found at the leading edge of repairing corneal epithelial wounds, however, corneal epithelial wound repair was qualitatively normal in JAM-A null animals. In summary, JAM-A is expressed in the corneal epithelium where it appears to regulate cell shape.

Animals↗

PubMed2006

Regulation of alphaA-crystallin via Pax6, c-Maf, CREB and a broad domain of lens-specific chromatin.

Pax6 and c-Maf regulate multiple stages of mammalian lens development. Here, we identified novel distal control regions (DCRs) of the alphaA-crystallin gene, a marker of lens fiber cell differentiation induced by FGF-signaling. DCR1 stimulated reporter gene expression in primary lens explants treated with FGF2 linking FGF-signaling with alphaA-crystallin synthesis. A DCR1/alphaA-crystallin promoter (including DCR2) coupled with EGFP virtually recapitulated the expression pattern of alphaA-crystallin in lens epithelium and fibers. In contrast, the DCR3/alphaA/EGFP reporter was expressed only in 'late' lens fibers. Chromatin immunoprecipitations showed binding of Pax6 to DCR1 and the alphaA-crystallin promoter in lens chromatin and demonstrated that high levels of alphaA-crystallin expression correlate with increased binding of c-Maf and CREB to the promoter and of CREB to DCR3, a broad domain of histone H3K9-hyperacetylation extending from DCR1 to DCR3, and increased abundance of chromatin remodeling enzymes Brg1 and Snf2h at the alphaA-crystallin locus. Our data demonstrate a novel mechanism of Pax6, c-Maf and CREB function, through regulation of chromatin-remodeling enzymes, and suggest a multistage model for the activation of alphaA-crystallin during lens differentiation.

Adenosine Triphosphatases↗

PubMed2006

Production of monoclonal antibodies against Prox1.

Prox1 is a divergent homeodomain protein important for the development of the lens, retina, liver, pancreas, and lymphatic vasculature. Prox1 expression is highly upregulated in transformed hepatocytes and has been used as a marker to distinguish lymphatic from blood vasculature. We produced recombinant human Prox1 (amino acids 547-737) fused to glutathione S-transferase (GST) and used it to create two hybridomas, 5G10 and 4G10. Both of these hybridomas produced monoclonal antibodies able to detect Prox1 by immunofluorescence in lenses from diverse terrestrial vertebrates, including humans, rats, chickens, and lizards, although 5G10 was generally more sensitive in this application. Further, 4G10 was able to robustly detect endogenous and recombinant Prox1 in both cell and tissue extracts by Western blotting, while 5G10 was notably less sensitive for this purpose. These monoclonal antibodies will be useful for diverse studies on the role of Prox1 in both normal development and disease processes in terrestrial vertebrates.

Animals↗

PubMed2006

Inbred FVB/N mice are mutant at the cp49/Bfsp2 locus and lack beaded filament proteins in the lens.

PURPOSE: FVB/N is considered an ideal inbred mouse strain for transgenic mouse production because of the ease of pronuclear microinjection and its overall fecundity. It is well established that vertebrate lens fiber cells normally express a modified intermediate filament network consisting of the proteins filensin and CP49, and it was recently reported that the mouse strain 129 harbors mutations in CP49 that have the potential to confound the interpretation of gene knockout studies of the lens. The purpose of this study was to evaluate the status of the CP49/Bfsp2 gene in the FVB/N strain. METHODS: PCR analysis of genomic DNA was used to evaluate the status of the CP49 gene in FVB/N mice procured from the four major US distributors of these animals--Harlan Laboratories, Taconic Farms, Jackson Laboratory, and the NIH/NCI/DCT production facility run by Charles River Laboratories. The structure of the CP49 transcript was evaluated by RT-PCR, and the presence of CP49 protein in the lens was evaluated by immunofluorescence. RESULTS: FVB/N mice obtained from all four US distributors were shown to harbor a 6-kb deletion of the CP49 gene identical with that previously reported in mouse strain 129; C57BL/6 mice did not have this modification. Immunofluorescence demonstrated that FVB/N mice do not have detectable CP49 or filensin protein in the lens, whereas C57BL/6 mice have the expected protein distribution. CONCLUSIONS: In humans, mutations in the CP49/BFSP2 gene have been linked to familial, congenital cataract, demonstrating an important role of this gene in lens transparency. The demonstration that FVB/N mice lack CP49 protein in the lens suggests that it may be necessary to reevaluate the mechanisms underlying lens phenotypes obtained as a result of transgenic manipulation of this strain.

Animals↗

PubMed2005

Xcat, a novel mouse model for Nance-Horan syndrome inhibits expression of the cytoplasmic-targeted Nhs1 isoform.

Nance-Horan syndrome (NHS) is an X-linked disorder characterized by congenital cataracts, dental anomalies, dysmorphic features and mental retardation. A recent report suggests that the novel gene NHS1 is involved in this disorder due to the presence of point mutations in NHS patients. A possible mouse model for NHS, Xcat, was mapped to a 2.11 Mb interval on the X-chromosome. Sequence and FISH analysis of the X-chromosome region containing the Xcat mutation reveal a large insertion between exons 1 and 2 of the mouse Nhs1 gene. The insertion inhibits the expression of the Nhs1 isoform containing exon 1 and results in exclusive expression of the alternative isoform containing exon 1A. Quantitative RT-PCR of Xcat cDNA shows reduced levels of Nhs1 transcripts. The Nhs1 protein is strongly expressed within the cytoplasm of elongating lens fiber cells from wild-type neonate lens, but is significantly reduced within the Xcat lens. Transient transfection studies of CHO cells with Nhs1-GFP fusion proteins were done to determine whether the amino acids encoded by exon 1 were critical for protein localization. We found the presence of Nhs1 exon 1 critical for localization of the fusion protein to the cytoplasm, whereas fusion proteins lacking Nhs1 exon 1 are predominantly nuclear. These results indicate that the first exon of Nhs1 contains crucial information required for the proper expression and localization of Nhs1 protein. Inhibition of expression of the exon 1 containing isoform results in the abnormal phenotype of Xcat.

Abnormalities, Multiple↗

PubMed2005

Palm is expressed in both developing and adult mouse lens and retina.

BACKGROUND: Paralemmin (Palm) is a prenyl-palmitoyl anchored membrane protein that can drive membrane and process formation in neurons. Earlier studies have shown brain preferred Palm expression, although this protein is a major water insoluble protein in chicken lens fiber cells and the Palm gene may be regulated by Pax6. METHODS: The expression profile of Palm protein in the embryonic, newborn and adult mouse eye as well as dissociated retinal neurons was determined by confocal immunofluorescence. The relative mRNA levels of Palm, Palmdelphin (PalmD) and paralemmin2 (Palm2) in the lens and retina were determined by real time rt-PCR. RESULTS: In the lens, Palm is already expressed at 9.5 dpc in the lens placode, and this expression is maintained in the lens vesicle throughout the formation of the adult lens. Palm is largely absent from the optic vesicle but is detectable at 10.5 dpc in the optic cup. In the developing retina, Palm expression transiently upregulates during the formation of optic nerve as well as in the formation of both the inner and outer plexiform layers. In short term dissociated chick retinal cultures, Palm protein is easily detectable, but the levels appear to reduce sharply as the cultures age. Palm mRNA was found at much higher levels relative to Palm2 or PalmD in both the retina and lens. CONCLUSION: Palm is the major paralemmin family member expressed in the retina and lens and its expression in the retina transiently upregulates during active neurite outgrowth. The expression pattern of Palm in the eye is consistent with it being a Pax6 responsive gene. Since Palm is known to be able to drive membrane formation in brain neurons, it is possible that this molecule is crucial for the increase in membrane formation during lens fiber cell differentiation.

Animals↗

PubMed2005

JAM-A expression during embryonic development.

Cell adhesion molecules of the immunoglobulin superfamily play an important role in embryonic development. We have shown recently that JAM-A, a member of this family expressed at endothelial and epithelial tight junctions, is involved in platelet activation, leukocyte transmigration, and angiogenesis. Here, we determine the expression pattern of the JAM-A gene during embryogenesis using transgenic mice expressing lacZ under the control of the endogenous JAM-A promoter. Histochemical staining for beta-galactosidase in heterozygous mouse embryos was first seen in the inner cell mass and trophectoderm of the blastocyst. By 8.5 days post coitum (dpc), JAM-A gene activity was detected in the endoderm and part of the surface ectoderm. At 9.5 dpc, JAM-A expression began to localize to certain organ systems, most notably the developing inner ear and early vasculature. Localization of JAM-A to embryonic vasculature was confirmed by double-staining with antibodies against JAM-A and platelet endothelial cell adhesion molecule-1, a known endothelial cell marker. As organogenesis progressed, high levels of JAM-A expression continued in the epithelial component of the inner ear as well as the epithelium of the developing skin, olfactory system, lungs, and kidneys. In addition, JAM-A gene activity was found in the developing liver, choroid plexuses, and gut tubes. Immunofluorescent staining with a JAM-A antibody was performed to confirm that expression of the JAM-A-beta-galactosidase fusion protein accurately represented endogenous JAM-A protein. Thus, JAM-A is prominently expressed in embryonic vasculature and the epithelial components of several organ systems and may have an important role in their development.

Animals↗

PubMed2005

Expression of tissue plasminogen activator during eye development.

Tissue plasminogen activator (tPA) is a serine protease responsible for the activation of plasminogen to plasmin as well as extracellular matrix remodeling. While tPA is used clinically to treat some retinal disorders and it is expressed at low levels in the adult eye, its expression pattern during eye development had never been determined. tPA protein is broadly dispersed in the lens placode and optic vesicle of the mouse eye and it becomes highly localized to the apical surfaces of both the lens pit and the optic cup as they invaginate. In the lens, tPA remains at the apical tips of both lens epithelial and fiber cells from the lens vesicle stage until birth in the mouse, when it begins to downregulate to barely detectable levels in adults. In humans, tPA is found in a similar pattern in the lens vesicle and early lens, however, appreciable protein is also detected in the cytoplasm of lens epithelial cells until adulthood. In the retina, tPA is found at the apical interface between the developing retinal pigmented epithelium and neural retina, then begins to downregulate once the photoreceptors have differentiated. In conclusion, tPA protein is found in a different pattern in embryonic versus adult eyes and may be involved in remodeling of the extracellular environment during eye development.

Adult↗

PubMed2004

Mafs, Prox1, and Pax6 can regulate chicken betaB1-crystallin gene expression.

During lens fiber cell differentiation, the regulation of crystallin gene expression is coupled with dramatic morphological changes. Here we report that Mafs, Prox1, and Pax6, which are essential transcription factors for normal lens development, bind to three functionally important cis elements, PL1, PL2, and OL2, in the chicken betaB1-crystallin promoter and may cooperatively direct the transcription of this lens fiber cell preferred gene. Gel shift assays demonstrated that Mafs bind to the MARE-like sequences in the PL1 and PL2 elements, whereas Prox1, a sequence-specific DNA-binding protein like its Drosophila homolog Prospero, interacts with the OL2 element. Furthermore, Pax6, a known repressor of the chicken betaB1-crystallin promoter, binds to all three of these cis elements. In transfection assays, Mafs and Prox1 activated the chicken betaB1-crystallin promoter; however, their transactivation ability was repressed when co-transfected with Pax6. Taken together with the known spatiotemporal expression patterns of Mafs, Prox1, and Pax6 in the developing lens, we propose that Pax6 occupies and represses the chicken betaB1-crystallin promoter in lens epithelial cells, and is displaced by Prox1 and Mafs, which activate the promoter, in differentiating cortical fiber cells.

Animals↗

PubMed2004

OptiRNAi, an RNAi design tool.

RNA interference (RNAi), a recently developed reverse genetics tool, has many advantages compared to traditional gene knockout methods. Appropriate selection of double stranded RNAs identical to a specific region(s) of the target gene is critical for the successful implementation of this technology. Recently, Elbashir et al. [Methods 26 (2002) 199] has established empirical criteria for siRNA sequence selection that significantly improved the success rate for RNAi attempts. We have developed OptiRNAi, a computational tool, which uses the Elbashir et al. criteria to predict appropriate target sequences for siRNA production. Specificity of these siRNAs for the target of interest can then be assessed by the investigator using the embedded Blast search engine optimized for RNAi design. Thus, OptiRNAi is an efficient and user friendly tool for RNAi design based on criteria that are more stringent than other available tools.

Animals↗

PubMed2004

Chromosomal proteins HMGN3a and HMGN3b regulate the expression of glycine transporter 1.

HMGN proteins promote chromatin unfolding, enhance access to nucleosomes, and modulate transcription from chromatin templates. It is not known whether they act indiscriminately as general modulators of transcription or whether they regulate specific gene expression. Here, we investigated the role of HMGN3, a recently discovered HMGN family member, in transcription in vivo. We created cell lines overexpressing HMGN3a or its splice variant, HMGN3b, and analyzed their gene expression profiles using microarrays and reverse transcriptase PCR. We found that ectopic expression of HMGN3a alters the expression of approximately 0.8% of genes. Both HMGN3a and HMGN3b upregulate the expression of the glycine transporter 1 gene (Glyt1). Glyt1 encodes a membrane transporter that regulates the glycine concentration in synaptic junctions. Both GLYT1 and HMGN3 are highly expressed in glia cells and the eye, and we show that both proteins are coexpressed in the retina. Chromatin immunoprecipitation assays showed that HMGN3 protein is recruited to a region of the Glyt1 gene encompassing the Glyt1a transcriptional start site. These results suggest that HMGN3 regulates Glyt1 expression and demonstrate that members of the HMGN family can regulate the transcription of specific genes.

Amino Acid Transport Systems, Neutral↗

PubMed2004

Proteomic and sequence analysis of chicken lens crystallins reveals alternate splicing and translational forms of beta B2 and beta A2 crystallins.

PURPOSE: To characterize the adult chicken lens proteome using mass spectrometry and two-dimensional gel electrophoresis (2-DE). METHODS: Lens proteins from 10-week old chickens were separated by gel filtration and reversed-phase chromatography, and whole protein masses were measured with electrospray mass spectrometry. Water-soluble lens proteins were separated by 2-DE and identified by tandem mass spectrometry of in-gel digests. RESULTS: Whole protein masses were consistent with all major chicken lens crystallin sequences, except for beta B2 and beta B3. Subsequent cDNA sequencing revealed errors in published sequences translating into 2- and 7-amino-acid differences, respectively, for beta B2 and beta B3, which were in better agreement with the measured masses. Previously uncharacterized forms of beta A2 and beta B2 were observed. The novel form of beta A2 had four fewer amino acids, was more abundant, and resulted from translation at a second start codon. The novel form of beta B2 contained 14 additional amino acids in the interdomain linker and resulted from alternate splicing within intron 4 of the transcript. All examined crystallins, except beta A3, for which data could not be obtained, were N-terminally acetylated, and all beta-crystallins lacked an initial methionine, except for the smaller beta A2 form. In-gel digests identified 29 proteins on the 2-DE map and indicated that truncation occurs within N-terminal extensions of beta-crystallins during lens maturation. CONCLUSIONS: The complementary techniques 2-DE, mass spectrometry, and DNA sequencing were used to provide the most complete description of the adult chicken lens proteome to date and identified alternate forms of beta A2 and beta B2.

Alternative Splicing↗

PubMed2004

Ectopic Pax6 expression disturbs lens fiber cell differentiation.

PURPOSE: Pax6 is a transcription factor necessary for the specification and subsequent formation of the ocular lens. It is expressed in all lens cells at early stages of development. After lens formation, Pax6 expression is maintained in the lens epithelium, whereas its level abruptly decreases in differentiated fiber cells. This study is to test the hypothesis that normal fiber cell differentiation would be perturbed by sustained Pax6 expression. METHODS: Transgenic mice expressing the canonical form of mouse Pax6 were created under the control of a modified mouse alphaA-crystallin promoter. The phenotypic changes in the transgenic lens were analyzed by light and electron microscopy. The effect of ectopic Pax6 expression on the lens fiber cells was investigated by in situ hybridization, immunohistochemical staining, real-time reverse transcriptase-polymerase chain reaction (RT-PCR), and two-dimensional (2-D) gel electrophoresis. RESULTS: Transgenic mice from seven different lines all had cataracts with severity that correlated with the transgene expression level in lens fiber cells. In severely affected lines, a lumen was present between the apical surfaces of the epithelial and fiber cells, suggesting that secondary fiber cell elongation is incomplete. Electron microscopy analysis showed that the ball-and-socket interdigitations between neighboring fiber cells were underdeveloped or attenuated in the transgenic lens. Most interesting, elevated levels of Pax6 in fiber cells reduced the protein levels of transcription factor cMaf, which is known to be essential in fiber cell differentiation. Furthermore, the total amount of lens proteins was 60% less than normal in the Pax6 transgenic lens. Among the crystallins examined, the relative ratio of intact betaB1-crystallin protein to total lens protein was significantly reduced. Real-time reverse transcriptase PCR showed that the ratio of betaB1-crystallin transcript levels to total mRNA levels were reduced by 87%. CONCLUSIONS: The data demonstrate that high levels of Pax6 expression disrupt normal fiber cell differentiation and maturation.

Animals↗

PubMed2004

Developmental expression of Pop1/Bves.

Initial studies have suggested that Pop1/Bves protein is exclusively expressed in the smooth muscle walls of the coronary vessels, implying its possible importance in coronary diseases. However, the mRNA and activity of this gene are detected in both skeletal and cardiac muscles, not coronary smooth muscle, and Pop1/Bves knockout mice have defects in skeletal muscle regeneration. Here we used specific monoclonal antibodies (MAbs) raised against chicken Pop1/Bves and demonstrated the presence of this protein in cardiomyocytes through development and its apparent absence in coronary vessels. Immunostaining of cardiomyocytes cultured in vitro confirmed the membrane localization of this protein in cells that participate in cell adhesion, with significant intracellular staining seen in isolated cells. In skeletal muscle, Pop1 protein becomes detectable at embryonic day (E) 7, coincident with the differentiation of morphologically distinct muscle masses from the limb muscle blastema, but the protein is not found at high levels in the cell membrane of myotubes until E11, coincident with the formation of secondary myotubes from satellite cells. These data support the hypothesis that Pop1/Bves is a cell adhesion molecule present in skeletal and cardiac muscle.

Animals↗

PubMed2003

Differential influence of proteolysis by calpain 2 and Lp82 on in vitro precipitation of mouse lens crystallins.

The purpose of the present study was to compare the susceptibility of crystallins proteolyzed by ubiquitous calpain 2 and by lens-specific calpain Lp82 to insolubilization. To test this, transgenic (TG) mice expressing a calpain 2, in which the active site cysteine 105 was mutated to alanine, were produced. Expression of mutated calpain 2 was driven in lens by coupling the mutated gene to the betaB1-crystallin promoter. Light scattering was measured in solutions of lens proteins after activation of endogenous calpain 2 and/or Lp82. Mass spectrometric analysis was performed to determine the cleavage sites and the calpain responsible for insolubilization of crystallins. Lens proteins from TG mice incubated in vitro with calcium showed higher light scattering compared to proteins from wild type (WT) mice. alphaA-crystallin from TG mice was proteolyzed by Lp82. In contrast, alphaA-crystallin in lenses from WT mice were proteolyzed by both calpain 2 and Lp82. These results suggested that Lp82-induced proteolysis of crystallins caused increased susceptibility of truncated crystallins to in vitro precipitation. Since Lp82 is highest in young animals, Lp82-induced proteolysis and precipitation may be one of the factors responsible for the cataract formation in young rodents.

Animals↗

PubMed2003

Requirement for Pax6 in corneal morphogenesis: a role in adhesion.

The Pax6 transcription factor functions early during embryogenesis to control key steps in brain, pancreas, olfactory and ocular system development. A requirement for Pax6 in proper formation of lens, iris and retina is well documented. By examining the corneas of heterozygous Small eye (SEY) mice, this report shows that Pax6 is also necessary for normal corneal morphogenesis. In particular, the epithelial component of the postnatal and adult SEY (+/-) cornea is thinner owing to a reduction in the number of cell layers, despite a tenfold increase in the proliferative index and no change in TUNEL labeling. Ultrastructural views revealed large gaps between corneal epithelial cells and a change in the appearance of desmosomes, suggesting that adhesion abnormalities contribute to the corneal phenotype of SEY (+/-) mice. Western blot analysis and immunofluorescence showed equivalent amounts and normal localization of E-cadherin in SEY (+/-) corneas, and the actin cytoskeleton appeared normal as judged by phalloidin staining. By contrast, the levels of desmoglein, beta-catenin and gamma-catenin were reduced in the SEY (+/-) cornea. In addition, the amount of keratin-12 mRNA and protein, the major intermediate filament, was reduced in SEY (+/-) corneal epithelium as shown by in situ hybridization and immunohistochemistry. Finally, the SEY (+/-) corneal epithelium adheres less well than wild-type when challenged with gentle rubbing using a microsponge. In conclusion, our results indicate that cellular adhesion is compromised in the SEY (+/-) corneal epithelium and suggests a role for Pax6 in the proper generation and maintenance of the adult cornea.

Age Factors↗

PubMed2003

Protein expression patterns for ubiquitous and tissue specific calpains in the developing mouse lens.

Calcium activated proteases (calpains) have been implicated in the processing of lens crystallins during lens maturation and cataract formation. Ubiquitous type calpain 2 and calpain 10 and lens specific Lp82 and Lp85 protein distribution were determined using immunohistochemistry and immunoblotting in embryonic and post-natal mouse eyes. Calpain 2 was first expressed late in embryonic development and localized to the lens epithelium and transition zone. Lp82 was expressed at E9.5 in the lens placode, head ectoderm, and throughout the fiber cells during embryonic lens maturation. Lp82 co-localized at sites of crystallin modification in the juvenile lens. In the adult lens, Lp82 protein was maintained in cortical fibers but could not be detected in the lens nucleus. Lp85, the slightly larger splice variant of Lp82, was first observed at E9.5 and throughout early embryonic lens development. Abundant localization of this enzyme was observed in the cell nuclei of lens epithelium, elongating fibers, and undifferentiated mesoderm. Robust peri-nuclear localization of calpain 10 was observed in the head ectoderm, lens placode, and optic vesicle during early eye induction. Further, calpain 10 protein was maintained in the lens epithelium of pre- and post-natal lens. These data support the hypothesis that Lp82 in rodent lens has an important role in crystallin proteolysis during normal lens maturation. In contrast, calpain 2, Lp85, and calpain 10 may have roles in cell signaling pathways.

Aging↗

PubMed2002

Identification of genes downstream of Pax6 in the mouse lens using cDNA microarrays.

Pax6 is a transcription factor that regulates the development of the visual, olfactory, and central nervous systems, pituitary, and pancreas. Pax6 is required for induction, growth, and maintenance of the lens; however, few direct Pax6 target genes are known. This study was designed to identify batteries of differentially expressed genes in three related systems: 8-week old Pax6 heterozygous lenses, 8-week old Pax6 heterozygous eyes, and transgenic lenses overexpressing PAX6(5a), using high throughput cDNA microarrays containing about 9700 genes. Initially, we obtained almost 400 differentially expressed genes in lenses from mice heterozygous for a Pax6 deletion, suggesting that Pax6 haploinsufficiency causes global changes in the lens transcriptome. Comparisons between the three sets of analyses revealed that paralemmin, molybdopterin synthase sulfurylase, Tel6 oncogene (ETV6), a cleavage-specific factor (Cpsf1) and tangerin A were abnormally expressed in all three experimental models. Semiquantitative reverse transcription (RT)-PCR analysis confirmed that all five of these genes were differentially expressed in Pax-6 heterozygous and Pax6(5a) transgenic lenses. Western blotting and immunohistochemistry demonstrated that paralemmin is found at high levels in the adult lens and confirmed its down-regulation in the Pax6(5a)-transgenic lenses. Collectively, our data provide insights into the genetic programs regulated by Pax6 in the lens.

Animals↗