ACGT and vicilin core sequences in a promoter domain required for seed-specific expression of a 2S storage protein gene are recognized by the opaque-2 regulatory protein

The expression of Brazil nut storage albumin genes is highly regulated during seed development. Several sequences in the promoter of one of these genes show homologies with the target sites of the maize O2 bZIP regulatory protein. We therefore asked whether the O2 protein would recognize these promoter sequences. We show that the O2 protein binds to three different sequences (F1, F2 and F3). F1 and F3 are hybrid C/G and A/G boxes, respectively, that are homologous to the O2-binding site of a maize alpha-zein gene. F2 is a new O2-binding sequence related to the O2 target sites of the Coix alpha-coxin, the maize b-32 genes and the AP-1 pseudopalindrome. Molecular modelling showed that an Asn and a Ser in the 02 DNA binding domain make different base-specific contacts with each operator. 5' Promoter deletions of the be2S1 gene showed that the domain containing the O2 target sites F1 and F2 is required for detectable reporter gene expression in transgenic tobacco seeds. Moreover, the homologous coix O2 protein was shown to in situ transactivate the promoter region encompassing the three O2-binding sites F1, F2 and F3. Thus, these sites may be in vivo regulatory sequences mediating activation by bZIP regulatory proteins.

A corm-specific gene encodes tarin, a major globulin of taro (Colocasia esculenta L. Schott)

A gene encoding a globulin from a major taro (Colocasia esculenta L. Schott) corm protein family, tarin (G1, ca. 28 kDa) was isolated from a lambda Charon 35 library, using a cDNA derived from a highly abundant corm-specific mRNA, as probe. The gene, named tar1, and the corresponding cDNA were characterized and compared. No introns were found. The major transcription start site was determined by primer extension analysis. The gene has an open reading frame (ORF) of 765 bp, and the deduced amino acid sequence indicated a precursor polypeptide of 255 residues that is post-translationally processed into two subunits of about 12.5 kDa each. The deduced protein is 45% homologous to curculin, a sweet-tasting protein found in the fruit pulp of Curculigo latifolia and 40% homologous to a mannose-binding lectin from Galanthus nivalis. Significant similarity was also found at the nucleic acid sequence level with genes encoding lectins from plant species of the Amaryllidaceae and Lilliaceae families.

Transgenic plants of ramie (Boehmeria nivea Gaud.) obtained by Agrobacterium mediated transformation

A regeneration and transformation protocol for ramie (Boehmeria nivea Gaud.) is presented. Regeneration was obtained from leaf discs placed on solid B-5 medium (Gamborg et al. 1968) containing adequate concentrations of auxin and cytokinin. Co-cultivation of leaf discs with Agrobacterium tumefaciens and subsequent regeneration resulted in transgenic plants as shown by Southern blot and analysis of expression of the GUS-marker gene.

Schwannoma of the nasal septum. Apropos of 2 cases

We present two cases of schwannoma of the nasal septum. One of the patients has neurofibromatosis type 2; however, her main complaint was nasal obstruction. Schwannoma deriving from the septum is an extremely rare pathology, both in systemic neurofibromatosis type 2 and as a solitary lesion. There are no characteristic symptoms. Histopathologic examination may be inconclusive so that the definitive diagnosis requires immunohistochemic studies or electron microscopy. Differential diagnosis includes several neurogenic and mesenchymal tumors. CT scan and MRI studies are helpful in evaluating the origin, localization and extension of the lesion. Complete resection of the mass is usually curative, although patients with neurofibromatosis present a higher risk of local recurrence and malignant transformation.