Clinical disorders affecting mesopic vision

Vision in the mesopic range is affected by a number of inherited and acquired clinical disorders. We review these conditions and summarize the historical background, describing the clinical characteristics alongside the genetic basis and molecular biological mechanisms giving rise to rod and cone dysfunction relevant to twilight vision. The current diagnostic gold standards for each disease are discussed and curative and symptomatic treatment strategies are summarized

Heterogeneity and organization of the ribosomal RNA genes of Cucurbita maxima

Thirty-six clones were recovered from Cucurbita maxima genomic DNA which had been enriched for rDNA and cleaved at the unique repeat unit Hin d III site. Twenty-nine of these, which contain complete rDNA units, were compared to a standard whose intergenic spacer (IGS) nucleotide sequence has been determined. Twenty-one are identical in length and restriction site pattern. Eight which differ from the standard in length do so because of addition or deletion of varying numbers of IGS subrepetitive units of two different classes, with four of the length variants being different in both of these classes. Seven clones were isolated which contain incomplete repeat units, six of which are composites of rDNA and non-rDNA material. They have been cleaved at the unique rDNA Hin d III site at one end and at a non-rDNA Hin d III site at the other. We consider it most likely that these are derived from the termini of repeat unit tandem arrays, although other explanations are possible. Twelve individual plants of two different cultivars were examined for heterogeneity of IGS length distribution. They all appear to be identical in this regard.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43423/1/11103_2004_Article_BF00019390.pd

Genomic organization, sequence analysis and expression of all five genes encoding the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase from tomato

We have cloned and sequenced all five members of the gene family for the small subunit (rbcS) of ribulose-1,5-bisphosphate carboxylase/oxygenase from tomato, Lycopersicon esculentum cv. VFNT LA 1221 cherry line. Two of the five genes, designated Rbcs-1 and Rbcs-2 , are present as single genes at individual loci. Three genes, designated Rbcs-3A, Rbcs-3B and Rbcs-3C , are organized in a tandem array within 10 kb at a third independent locus. The Rbcs-2 gene contains three introns; all the other members of the tomato gene family contain two introns. The coding sequence of Rbcs-1 differs by 14.0% from that of Rbcs-2 and by 13.3% from that of Rbcs-3 genes. Rbcs-2 shows 10.4% divergence from Rbcs-3 . The exon and intron sequences of Rbcs-3A are identical to those of Rbcs-3C , and differ by 1.9% from those of Rbcs-3B . Nucleotide sequence analysis suggests that the five rbcS genes encode four different precursors, and three different mature polypeptides. S 1 nuclease mapping of the 5′ end of rbcS mRNAs revealed that the mRNA leader sequences vary in length from 8 to 75 nucleotides. Northern analysis using gene-specific oligonucleotide probes from the 3′ non-coding region of each gene reveals a four to five-fold difference among the five genes in maximal steady-state mRNA levels in leaves.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47566/1/438_2004_Article_BF00329650.pd

Novel Lipids of the Rabbit Harderian Gland Improve Tear Stability in an Animal Model of Dry Eye Disease

Purpose: Instability of the tear film leads to evaporative dry eye disease (EDED), but the Harderian gland in some terrestrial vertebrates may produce novel lipids that stabilize the tear film and protect against dry eye. Here, the nonpolar lipids in the Harderian gland and tears of the rabbit but absent in human tears were identified and tested in preclinical studies to determine whether they could treat severe EDED. Methods: Lipids were identified primarily by atmospheric pressure chemical ionization mass spectrometry (MS) and fragmentation MS/MS. An identified lipid was synthesized and formulated as an emulsion and as a cyclodextrin (CD) clathrate. Following doses with test agents and controls, tear film breakup time (TBUT), tear production, corneal fluorescein staining, macrophage infiltration, and goblet cell survival were measured using standard tests at 0, 2 and 4 weeks in an animal model of EDED. Results: The lipid emulsion increased TBUT (P < 0.01) and tear production (P < 0.05), while it decreased corneal staining (P < 0.01) compared to controls. The lipid CD formulation increased TBUT (P < 0.05) and tear production (P < 0.05) but had no significant effect on the remaining test parameters. There were no differences in macrophage infiltration and conjunctival impression cytology scores between the formulations and their vehicle controls. Conclusions: Lipids in the rabbit Harderian gland and tears differ from those identified in human meibum and tears. These unique rabbit lipids may confer a protective effect against EDED and, as supplements to human tears, fulfill a similar role