Polyamines, hydroxycinnamoylputrescines, and root formation in leaf explants of tobacco cultivated in vitro: effects of the suicide inhibitors of putrescine synthesis

In vitro formation of roots is obtained directly, without intermediate growth of callus, from foliar explants of a tobacco (Nicotiana tabacum) plant cultured on Murashige and Skoog medium containing IAA. Auxin-induced root formation was accompanied by significant changes in hydroxycinnamoylputrescine levels. Increasing levels were found in leaf explants during the first 14 days in culture; this was followed by a sharp decline after 20 days. Early changes in putrescine conjugates were detected in leaf explants before the visible appearance of roots. An early and transitory accumulation of hydroxycinnamoylputrescines was observed in the roots. Free polyamines (putrescine, spermidine, and spermine) in leaf explants and roots were always at a low level and only small changes in their concentrations were observed, α-dl-difluoromethylarginine and α-dl-difluoromethylornithine, specific, irreversible inhibitors of arginine decarboxylase and ornithine decarboxylase, respectively, inhibited putrescine accumulation and root initiation and reduced the fresh and dry weights of leaf explants. These effects were reversed by free putrescine or hydroxycinnamoylputrescines. The results reported here suggest that hydroxycinnamoylputrescines are associated with root formation. The relationship among free polyamines, hydroxycinnamoylputrescines, cell division, and root formation is discussed.     

Production of 5-methoxypodophyllotoxin in cell suspension cultures of Linum flavum L.

Cell suspension cultures of Linum flavum L., routinely grown on a NAA-containing medium, accumulated low levels of the phenylpropanoid-derived lignan 5-methoxypodophyllotoxin (5-MPT), up to 0.004% on a dry weight basis. Feeding experiments with the precursor L-phenylalanine resulted in a 3–5-fold increase in 5-MPT levels, but caused the levels of PAL activity to fall. Treatment of the cultures with the elicitor Nigeran, either alone or in combination with phenylalanine, caused the 5-MPT production to cease, even though PAL activity was rapidly enhanced by these treatments. Transfer of the cultures to NAA-free medium resulted in a 40–50 fold higher level of 5-MPT accumulation, the PAL activity levels being lowered compared to the routinely grown cells. With these more differentiated cultures, phenylalanine feeding and elicitor treatment, both on its own and in combination with the precursor, had no effect on 5-MPT production, even though the PAL activity levels were higher than in the untreated cells. It can be concluded that in lignan-accumulating cultures of L. flavum, PAL activity is nearly always detectable and seems to show a reciprocal relationship with 5-MPT accumulation.Abbreviations 5-MPT 5-methoxypodophyllotoxin - PAL phenylalanine ammonia lyase (EC 4:3:1.5) - NAA naphthaleneacetic acid     

A tomato cDNA inducible by salt stress and abscisic acid: nucleotide sequence and expression pattern

We have characterized a new tomato cDNA, TAS14, inducible by salt stress and abscisic acid (ABA). Its nucleotide sequence predicts an open reading frame coding for a highly hydrophilic and glycine-rich (23.8%) protein of 130 amino acids. Southern blot analysis of tomato DNA suggests that there is one TAS14 structural gene per haploid genome. TAS14 mRNA accumulates in tomato seedlings upon treatment with NaCl, ABA or mannitol. It is also induced in roots, stems and leaves of hydroponically grown tomato plants treated with NaCl or ABA. TAS14 mRNA is not induced by other stress conditions such as cold and wounding. The sequence of the predicted TAS14 protein shows four structural domains similar to the rice RAB21, cotton LEA D11 and barley and maize dehydrin genes.     

A new species of Lernanthropus De Blainville, 1822 (Copepoda: Lernanthropidae) parasitic on Menticirrhus ophicephalus (Jenyns) (Teleostei: Sciaenidae) from the Peruvian coast

Lernanthropus huamani n. sp. (Copepoda: Lernanthropidae), a parasite of the Peruvian sciaenid fish Menticirrhus ophicephalus (Jenyns), is described and illustrated. The new species differs from all other species of Lernanthropus by a combination of characters, including the dorsal plate, legs and other appendages. L. guacoldae Villalba & Fernández, 1984 is considered a synonym of L. pacificus Oliva & Duran, 1982.     

The sequence and organization of the core histone H3 and H4 genes in the early branching amitochondriate protistTrichomonas vaginalis

Among the unicellular protists, several of which are parasitic, some of the most divergent eukaryotic species are found. The evolutionary distances between protists are so large that even slowly evolving proteins like histones are strongly divergent. In this study we isolated cDNA and genomic histone H3 and H4 clones fromTrichomonas vaginalis. Two histone H3 and three histone H4 genes were detected on three genomic clones with one complete H3 and two complete H4 sequences. H3 and H4 genes were divergently transcribed with very short intergenic regions of only 194 bp, which containedT. vaginalis-specific as well as histone-specific putative promoter elements. Southern blot analysis showed that there may be several more histone gene pairs. The two complete histone H4 genes were different on the nucleotide level but encoded the same amino acid sequence. Comparison of the amino acid sequences of theT. vaginalis H3 and H4 histones with sequences from animals, fungi, and plants as well as other protists revealed a significant divergence not only from the sequences in multicellular organisms but especially from the sequences in other protists likeEntamoeba histolytica, Trypanosoma cruzi, andLeishmania infantum.     

Xp-duplications with and without sex reversal

Duplications in Xp including the DSS (dosage sensitive sex reversal) region cause male to female sex reversal. We investigated two patients from families with Xp duplications. The first case was one of two sisters with karyotype 46,XY, der(22), t(X;22)(p11.3;p11)mat and unambiguous female genitalia. The living sister was developmentally retarded, and showed multiple dysmorphic features and an acrocallosal syndrome. The second case was a boy with a maternally inherited direct duplication of Xp21.3-pter with the breakpoint close to the DSS locus. He had multiple abnormalities and micropenis, but otherwise unambiguous male genitalia. We performed quantitative Southern blot analysis with probes from Xp22.13 to p21.2 to define the duplicated region. Clinical, cytogenetic, and molecular data from both patients were compared with those of previously reported related cases. A comparison of the extragenital symptoms revealed no differences between patients with or without sex reversal. In both cases, the symptoms were non-specific. Among 22 patients with a duplication in Xp, nine had unambiguous female genitalia and a well-documented duplication of the DSS region. Two patients with duplication of DSS showed ambiguous external genitalia. From these data, we conclude that induction of testicular tissue may start in these patients, but that the type of genitalia depends on the degree of subsequent degeneration by a gene in DSS.     

Linkage disequilibrium and extended haplotypes in the HLA-A to D6S105 region: implications for mapping the hemochromatosis gene (HFE)

The hemochromatosis gene (HFE) maps to 6p21.3, in close linkage with the HLA Class I genes. Linkage disequilibrium (LD) studies were designed to narrow down the most likely candidate region for HFE, as an alternative to traditional linkage analysis. However, both the HLA-A and D6S105 subregions, which are situated 2–3 cM and approximately 3 Mb apart, have been suggested to contain HFE. The present report extends our previous study based upon the analysis of a large number of HFE and normal chromosomes from 66families of Breton ancestry. In addition to the previously used RFLP markers spanning the 400-kb surrounding HLA-A, we examined three microsatellites: D6S510, HLA-F, and D6S105. Our combined data not only confirm a peak of LD at D6S105, but also reveal a complex pattern of LD over the i82 to D6S105 interval. Within our ethnically well-defined population of Brittany, the association of HFE with D6S105 is as great as that with HLA-A, while the internal markers display a lower LD. Fine haplotype analysis enabled us to identify two categories of haplotypes segregating with HFE. In contrast to the vast majority of normal haplotypes, 50% of HFE haplotypes are completely conserved over the HLA-A to D6S105 interval. These haplotypes could have been conserved through recombination suppression, selective forces and/or other evolutionary factors. This particular haplotypic configuration might account for the apparent inconsistencies between genetic linkage and LD data, and additionally greatly complicates positional cloning of HFE through disequilibrium mapping.The authors contributed equally to this work