No abstract

NRL, a bZIP transcription factor of the Maf subfamily, interacts with the homeodomain protein CRX and synergistically regulates rhodopsin expression. Here we report that six isoforms of NRL (29 -35 kDa) are generated by phosphorylation and expressed specifically in the mammalian retina. The anti-NRL antibody also crossreacts with a cytosolic 45-kDa protein, which is detected in neuronal tissues but is not encoded by the NRL gene. In both human retinal cell cultures and sections of fetal and adult human retina, NRL is present in the nuclei of developing and mature rods but not cones. We propose that NRL regulates rod photoreceptor-specific gene expression and is involved in rod differentiation.Retinal photoreceptors are highly specialized neurons that capture photons and convert them to chemical signals. Humans and Old World primates have four distinct photoreceptor types, each with a specific visual pigment (1) and a characteristic retinal distribution (2). Rhodopsin is the photopigment in rod photoreceptors, which dominate primate retina. Rhodopsin provides high sensitivity, but the rod synaptic circuitry yields low spatial resolution. The red, green, and blue visual pigments define the three cone types, whose neural circuits mediate color vision and high spatial resolution but require bright light.Extensive anatomical, lineage, and birth dating studies have demonstrated that the genesis of specific photoreceptor types from retinal progenitors is guided by intrinsic genetic programs, inductive cell-cell interactions, and extrinsic factors (3-6). Postmitotic neurons committed to a photoreceptor cell fate exhibit varying delays before expressing their cell typespecific photopigment, suggesting that the specification of a differentiated rod or cone phenotype requires additional cues (7-10). It is envisaged that these inductive cues turn on a "molecular switch," which leads to expression of a specific visual pigment and other components of the transduction machinery.Cell type-specific gene expression is achieved by combinatorial and synergistic actions of specific activator proteins that recruit the basal transcription machinery to the promoter region (11, 12). Several transcription factor genes are expressed in retina (13-17), and a number of cis-regulatory elements have been identified in retinal gene promoters (18 -20). However, only two transcription factors, NRL and CRX, have so far been implicated directly in modulating photoreceptor-specific gene expression. NRL was isolated from a subtracted human retinal cDNA library and encodes a basic motif-leucine zipper (bZIP) protein (21). It displays strong homology to Maf proteins, which are involved in differentiation and gene regulation (22). NRL was the first transcription factor shown to bind to a cis-regulatory sequence (called NRE or NRL response element) in the rhodopsin promoter and transactivate its activity in cultured cells (23,24). CRX is a photoreceptor-and pineal-specific homeodomain protein that appears to modulate several retinal gene promoters (25-2...

No abstract

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

What makes instrumental teaching, including vocal teaching, effective? And is this the same in schools and in higher education (HE), including conservatoires? We asked 134 local education authority (LEA) instrumental teachers to state what they believe makes good teaching in schools and in HE, and to list the strengths and weaknesses of the teaching that they recall receiving as students. We found that many teachers believe that good teaching in schools differs from good teaching in HE. There are differences in the beliefs held by teachers with and without qualified teacher status (QTS), and also in those of men and women. Many teachers report that their teaching is influenced by the ways that they were taught, and the ‘peak’ lessons that teachers received often appear particularly influential. We explain the steps we have taken to enable LEAs to apply the findings when planning professional development for their teachers, and suggest further applications.

No abstract

No abstract

Abstract-The paper presents a curriculum design for, and subsequent evaluation of, a communications systems course using problem-based learning (PBL) as the instructional methodology. It details the rationale for implementing PBL as well as reporting intended learning outcomes and assessing the students' achievements.