BLG-e1 - a novel regulatory element in the distal region of the beta-lactoglobulin gene promoter

beta-Lactoglobulin (BLG) is a major ruminant milk protein. A regulatory element, termed BLG-e1, was defined in the distal region of the ovine BLG gene promoter. This 299-bp element lacks the established cis-regulatory sequences that affect milk-protein gene expression. Nevertheless, it alters the binding of downstream BLG sequences to histone H4 and the sensitivity of the histone-DNA complexes to trichostatin A treatment. In mammary cells cultured under favorable lactogenic conditions, BLG-e1 acts as a potent, position-independent silencer of BLG/luciferase expression, and similarly affects the promoter activity of the mouse whey acidic protein gene. Intragenic sequences upstream of BLG exon 2 reverse the silencing effect of BLG-e1 in vitro and in transgenic mice.     

Bietti crystalline corneoretinal dystrophy is caused by mutations in the novel gene CYP4V2

Bietti crystalline corneoretinal dystrophy (BCD) is an autosomal recessive retinal dystrophy characterized by multiple glistening intraretinal crystals scattered over the fundus, a characteristic degeneration of the retina, and sclerosis of the choroidal vessels, ultimately resulting in progressive night blindness and constriction of the visual field. The BCD region of chromosome 4q35.1 was refined to an interval flanked centromerically by D4S2924 by linkage and haplotype analysis; mutations were found in the novel CYP450 family member CYP4V2 in 23 of 25 unrelated patients with BCD tested. The CYP4V2 gene, transcribed from 11 exons spanning 19 kb, is expressed widely. Homology to other CYP450 proteins suggests that CYP4V2 may have a role in fatty acid and steroid metabolism, consistent with biochemical studies of patients with BCD.     

A silent gene allelicto yeast invertase structural gene SUC2 can be activated by mutation to direct the formation of a new type of invertase

Strains fromSaccharomyces cerevisiae unable to produce invertase (suc0) may revert to invertase formation by ultraviolet treatment or spontaneously at a lower rate, as a consequence of activation of a silent gene allelic to the SUC2 locus. However, the new internal protein is physically different from the internal invertase expressed by the SUC2 gene according to electrophoresis analysis.     

Three novel mutations causing a truncated protein within the RP2 gene in Italian families with X-linked retinitis pigmentosa

X-linked retinitis pigmentosa (XLRP) results from mutations in a number of loci, including RP2 at Xp11.3, and RP3 at Xp21.1. RP2 and RP3 genes have been identified by positional cloning. RP2 mutations are found in about 10% of XLRP patients. We performed a mutational screening of RP2 gene inpatients belonging to seven unrelated families in linkage with the RP2 locus. SSCP analysis detected three conformation variants, within exon 2 and 3. Direct sequencing of exon 2, disclosed a G-->A transition at nucleotide 449 (W150X), and a G-->T transversion in position 547 (E183X). Sequence analysis of exon 3 variant revealed an insertion (853/854insG), leading to a frameshift. In this patient, we detected an additional sequence alteration (A-->G at nucleotide 848, E283G). Each mutation was co-segregating with the disease in the affected family members available for the study. These mutations are expected to introduce a stop codon within the RP2 coding sequence probably resulting in a truncated or unstable protein.     

Fusion of the inducible promoter of the PR-1a gene to the Activator transposase gene can transactive excision of a non-autonomous transposable element by external and by internal stimuli

The open reading frame coding for the transposase gene of the maize transposon Activator (Ac) was expressed in transgenic tobacco plants under the control of the promoter of the inducible gene for pathogenesis-related protein 1a (PR-1a). Excision of a non-autonomous transposable element (Ds) from chimeric β-glucuronidase (GUS) and luciferase reporter gene constructs was employed to analyze the induction of the Ac transposase by external and by internal stimuli. Applying the GUS histochemical assay, Ds excision events were detected in leaves, stems, and roots after treatment of regenerating shoots with salicylic acid (SA). Varying the SA induction procedure led to different Ds excision patterns in leaves and in roots. Furthermore, Ds excision events were also observed in non-treated, older transgenic plants in the green leaves, but not in germinal cells. Thus, the PR-1a promoter/Ac transposase gene fusion, together with the improved methods for induction of this chimeric gene, may provide a valuable tool for studying basic mechanisms of Ac transposition and for developing modified transposable element systems suitable for gene tagging in higher plants.