Nuclear DNA content of Vitis vinifera cultivars and ploidy level analyses of somatic embryo-derived plants obtained from anther culture

Flow cytometry was employed to determine the ploidy level of Vitis vinifera L. somatic embryo-derived plants obtained from anther culture. Only one among the 41 analysed plants (2.4%) presented somaclonal variation (tetraploidy); the other plants were diploid. No significant differences (P<or=0.05) were detected between diploid and parental field plants. No haploid or aneuploid plants were observed. The nuclear DNA content of nine V. vinifera cultivars was also estimated using flow cytometry. A non-significant variation was found among the cultivars, with DNA content ranging from 1.17 pg/2C (cv. 'Tinta Barroca' and 'Viosinho') to 1.26 pg/2C (cv. 'Cabernet Sauvignon'). These results and previous studies on other Vitis species suggest that Vitis genome is stable with regard to nuclear DNA content.

Caseinolytic activity of fruit extract from Opuntia ficus-indica on bovine, caprine, and ovine sodium caseinates

The rates and extents of hydrolysis of alpha(S)- and beta-caseins from bovine, caprine, and ovine sodium caseinates produced by an enzymatic extract of the fruit of Opuntia ficus-indica, (L.) Miller were evaluated and compared with those produced by a commercial animal rennet. A mechanistic model based on a pseudo-first-order enzymatic reaction, in the presence of first-order deactivation of the enzyme, was postulated and successfully fitted to the experimental data. The animal rennet exhibited higher enzymatic efficiency than the fruit extract, irrespective of the source (i.e., bovine, caprine, or ovine) and the type (i.e., alpha(S)- or beta-casein) of substrate. The enzymatic efficiency (k(cat)/K(m)) for alpha(S)-casein ranged from 72 to 220 and from 43 to 65 L g(-1) h(-1), and for beta-casein from 242 to 742 and from 55 to 164 L g(-1) h(-1), for the animal rennet and the enzymatic extract of O. ficus-indica, respectively. Finally, it was observed that beta-casein from caprine and ovine caseinates was degraded by O. ficus-indica faster than its alpha(S) counterpart, but the reverse was observed for bovine caseinate.

Purification, cloning and autoproteolytic processing of an aspartic proteinase from Centaurea calcitrapa

Plant aspartic proteinases (APs) have been isolated from several seed and leaf sources but the only well characterized enzymes from flowers are cardosins and cyprosins from cardoon, Cynara cardunculus L. Here we report a full-length cDNA clone encoding an AP named cenprosin from the flowers of Centaurea calcitrapa L., a thistle related to cardoon. As found for all eukaryotic APs, the deduced primary sequence consists of a signal sequence, a propart and a mature enzyme. In addition, an internal sequence region of 104 residues typical only of plant APs (a plant-specific insert) is present in the primary structure. Northern analysis revealed that the strongest expression is in fresh flowers. The enzyme is also expressed in fairly high amounts in seeds and in leaves, a feature not detected for cardoon APs. The corresponding enzyme was purified in its precursor form from fresh flowers using ammonium-sulfate precipitation followed by ion-exchange and hydrophobic-interaction chromatography. The processing of the precursor into its mature form was studied in vitro. The enzyme underwent autocatalytic processing at pH 3.0 resulting in two chains of 16 and 30 kDa. When dried flowers were used as a starting material for purification, only 16- and 30-kDa chains were obtained, suggesting that autoproteolytic activation of procenprosin in vivo occurs mainly during drying of the flowers. This may indicate a specific degradative role for the enzyme during senescence of the flowers.

Organogenesis from internode-derived nodules of Humulus lupulus var. Nugget (Cannabinaceae): histological studies and changes in the starch content

The sequence of histological and histochemical events occurring during organogenesis from Humulus lupulus var. Nugget internode-derived nodules was studied. Sections were made and studies were carried out from the start of culture treatment until the development of shoot buds. Cell division was observed in both cambial and cortical regions during the first week of culture establishment. Cell division in cortical cells led to the formation of an incipient callus tissue. From the calluses prenodular structures of cambial origin appeared and gave rise to nodules from which shoot buds formed. Nodules kept separating into "daughter nodules" from which arose an increasing number of shoot buds. Iodide staining showed a strong starch accumulation in callus tissue and in prenodular structures. During shoot-bud primordia formation starch content decreased in nodules. Some starch was also noted in control explants (cultured on basal medium), however at a lower level than that observed in explants cultured on media with growth regulators. Shoot-bud regeneration was not observed in control explants.

Production and characterization of a specific rubisco monoclonal antibody, and its use in rubisco quantification during Zantedeschia aethiopica spathe development

Ribulose 1,5-bisphosphate carboxylase/oxygenase was purified from leaves of Zantedeschia aethiopica and used to immunize female Balb/c mice. Monoclonal antibodies (MAbs) were raised by hybridoma technology using Sp2/0 myeloma cells as fusion partner. A random selected IgG2a subclass MAb was purified from ascitic fluid by affinity chromatography on Protein A-Sepharose CL-4B, with a recovery of 84.3% and it was apparently homogeneous on native PAGE. The monoclonality of the purified MAb was determined by IEF. The MAb was highly specific for Rubisco from leaves of Z. aethiopica as determined by Western blotting and was used to determine the concentration of Rubisco protein by enzyme-linked immunoadsorbent assay (ELISA), at three distinct stages of Z. aethiopica spathe development and in the leaf. The results suggest de novo synthesis of Rubisco during the spathe regreening, which could explain, at least in part, the increase of photosynthetic activity observed during regreening.

Genetic transformation of European chestnut

Stable incorporation of the nptII gene into Castanea sativa Mill. has been achieved by Agrobacterium-mediated transformation. The transformation assays were performed by infecting wounded hypocotyls with a strain of Agrobacterium tumefaciens, LBA 4404 harbouring the plasmid p35SGUSINT. Although two schemes of selection were tested, many escapes were obtained. The best strategy to avoid this problem is the introduction of higher concentrations of kanamycin in the culture medium, immediately after coculture. PCR analysis showed of the selectable nptII gene integration in the plant genome. β-Glucuronidase histochemical assay revealed the expression of the uidA gene in shoots, regenerated from transformed explants.

Calcium Channel Activity during Pollen Tube Growth and Reorientation

We have shown previously that the inhibition of pollen tube growth and its subsequent reorientation in Agapanthus umbellatus are preceded by an increase in cytosolic free calcium ([Ca2+]c), suggesting a role for Ca2+ in signaling these processes. In this study, a novel procedure was used to measure Ca2+ channel activity in living pollen tubes subjected to various growth reorienting treatments (electrical fields and ionophoretic microinjection). The method involves adding extracellular Mn2+ to quench the fluorescence of intracellular Indo-1 at its ca2+-insensitive wavelength (isosbestic point). The spatial and temporal kinetics of Ca2+ channel activity correlated well with measurements of [Ca2+]c dynamics obtained by fluorescence ratio imaging of Indo-1. Tip-focused gradients in Ca2+ channel activity and [Ca2+]c were observed and quantified in growing pollen tubes and in swollen pollen tubes before reoriented growth. In nongrowing pollen tubes, Ca2+ channel activity was very low and [Ca2+]c gradients were absent. Measurements of membrane potential indicated that the growth reorienting treatments induced a depolarization of the plasma membrane, suggesting that voltage-gated Ca2+ channels might be activated.

Calcium Channel Activity during Pollen Tube Growth and Reorientation

We have shown previously that the inhibition of pollen tube growth and its subsequent reorientation in Agapanthus umbellatus are preceded by an increase in cytosolic free calcium ([Ca2+]c), suggesting a role for Ca2+ in signaling these processes. In this study, a novel procedure was used to measure Ca2+ channel activity in living pollen tubes subjected to various growth reorienting treatments (electrical fields and ionophoretic microinjection). The method involves adding extracellular Mn2+ to quench the fluorescence of intracellular Indo-1 at its ca2+-insensitive wavelength (isosbestic point). The spatial and temporal kinetics of Ca2+ channel activity correlated well with measurements of [Ca2+]c dynamics obtained by fluorescence ratio imaging of Indo-1. Tip-focused gradients in Ca2+ channel activity and [Ca2+]c were observed and quantified in growing pollen tubes and in swollen pollen tubes before reoriented growth. In nongrowing pollen tubes, Ca2+ channel activity was very low and [Ca2+]c gradients were absent. Measurements of membrane potential indicated that the growth reorienting treatments induced a depolarization of the plasma membrane, suggesting that voltage-gated Ca2+ channels might be activated.

In vitro and in vivo antitumor activity of benzyl isothiocyanate: a natural product from Tropaeolum majus

Cultured cells of Tropaeolum majus produce significant amounts of benzyl glucosinolate which, through enzymatic hydrolysis, results in the production of benzyl isothiocyanate (BITC). This study reports on the in vitro anticancer properties of BITC against a variety of human and murine tumor cell lines by four independent methods; SRB, MTT, cell counting, and clonogenic assays. Regardless of the assay used, BITC showed promising cytotoxicity in the low micromolar range (0.86 to 9.4 microM) against four human ovarian carcinoma cell lines (SKOV-3, 41-M, CHl, CHlcisR), a human lung tumor (H-69), a murine leukemia (L-1210), and a murine plasmacytoma (PC6/sens). The L1210 cells were most sensitive. BITC administered to mice bearing the ADJ/PC6 plasmacytoma subcutaneous tumor showed toxic effects at a dose of 200 mg/kg (within 24 h of drug administration) but no reduction in tumor mass. However, the growth inhibitory properties of BITC against a range of tumor cell types warrant further in vivo anti-tumor evaluation as well as its biotechnological production.

Isolation and characterization of a cDNA from flowers of Cynara cardunculus encoding cyprosin (an aspartic proteinase) and its use to study the organ-specific expression of cyprosin

Poly(A)+ RNA isolated from flower buds of Cynara cardunculus has been used to prepare a cDNA library. Screening of the cDNA after expression of cloned DNA with antibodies raised against the large subunit of cyprosin 3 resulted in the isolation of six positive clones. One of these clones (cypro1s; a 1.7 kb Eco RI fragment) codes for cyprosin. The nucleotide sequence contain a 1419 bp open reading frame coding for 473 amino acids (aa) including a putative full-length mature protein (440 aa) and a partial prosequence (33 aa). Cypro1s contains a 162 bp 3' non-coding region followed by a poly(A) tail. The deduced amino acid sequence shows high homology to other plant aspartic proteinases. The homology to mammalian and microbial aspartic proteinases is somewhat lower. Plant aspartic proteinases contain an insert of around 100 aa. We are modelling where this plant-specific insert will appear in the structure of cyprosin. Using cypro1s as a probe in northern blot analysis, the expression of cyprosin in developing flowers and other tissues has been studied. The signal on the northern blot increased for RNA samples from early (flower buds 6 mm in length) to later stages of floral development (flower buds up to 40 mm in length). In late stages of floral development (open flowers 50 mm in length and styles from such flowers) no hybridization signal was visualized showing that the synthesis of mRNA encoding the cyprosin starts in early stages of floral development and switches off at maturation of the flower.(ABSTRACT TRUNCATED AT 250 WORDS)

Direct embryo formation in leaves of Camillia japonica L

The culture conditions for direct embryo formation in leaves of Camellia japonica L. were established. An auxin treatment followed by incubation during 11 days in darkness on diluted Murashige and Skoog modified basal medium induced direct morphogenesis. The number of subcultures, subculture interval and leaf age affected in vitro leaf response. The results showed that the cells from a cultured leaf respond differently to the same culture conditions by forming embryos, roots, and non-morphogenic as well as organogenic callus. Direct embryo formation occurred only in the marginal leaf regions. Direct root formation only occurred in a well-defined region of the midrib whereas callus was preferentially formed on the leaf basis. The results suggest the existence of differences in morphogenic competence according to leaf regions. Plantlet regeneration was successfully achieved from somatic embryos and from leaf basisderived callus, via shoot bud induction.

Somatic embryogenesis in leaves and leaf-derived protoplasts of Actinidia deliciosa var. deliciosa cv. Hayward (kiwifruit)

The obtention of embryogenic competence in Actinidia deliciosa var. deliciosa cv. Hayward is reported. Axillary buds from shoots submitted to cold (4°C) and starvation for 1.5 months, developed leaves with embryogenic competence. These leaves, cultured in darkness for 1.5 months on a medium containing zeatin as a sole growth regulator, originated compact structures from which embryos developed. The plating orientation and sectioning of leaves strongly affected the expression of the embryogenic potential. A selected fraction of the protoplasts isolated from these leaves was able to develop in an embryogenic way. The germination of the embryos is still only occasional.

Plant regeneration from protoplasts of long-term callus cultures of Actinidia deliciosa var. deliciosa cv. Hayword (Kiwifruit)

Plant regeneration of Actinidia deliciosa var. deliciosa cv. Hayword was obtained from protoplasts isolated from petiole derived long-term callus cultures. Protoplasts were cultured in liquid medium over agarose gelled medium. Regenerated green callus, plated on solid medium, could develop shoots that rooted spontaneously in hormone-less medium. The plants obtained are growing fast in soil and present a normal phenotype.

Somatic hybridization by microfusion of defined protoplast pairs in Nicotiana: morphological, genetic, and molecular characterization

Somatic hybrid/cybrid plants were obtained by microfusion of defined protoplast pairs from malefertile, streptomycin-resistant Nicotiana tabacum and cytoplasmic male-sterile (cms), streptomycin-sensitive N. tabacum cms (N. bigelovii) after microculture of recovered fusants. Genetic and molecular characterization of the organelle composition of 30 somatic hybrid/cybrid plants was performed. The fate of chloroplasts was assessed by an in vivo assay for streptomycin resistance/ sensitivity using leaf explants (R0 generation and R1 seedlings). For the analysis of the mitochondrial (mt) DNA, species-specific patterns were generated by Southern hybridization of restriction endonuclease digests of total DNA and mtDNA, with three DNA probes of N. sylvestris mitochondrial origin. In addition, detailed histological and scanning electron microscopy studies on flower ontogeny were performed for representative somatic hybrids/cybrids showing interesting flower morphology. The present study demonstrates that electrofusion of individually selected pairs of protoplasts (microfusion) can be used for the controlled somatic hybridization of higher plants.

One-step purification and properties of catalase from leaves of Zantedeschia aethiopica

Catalase (E.C 1.11.1.6) was purified from leaves of Zandedeschia aethiopica to apparent homogeneity by a one-step hydrophobic interaction chromatography on a phenyl Sepharose CL-4B column. The purified enzyme preparation was obtained with a final recovery of enzyme activity of about 61% and a specific activity of 146 U/mg protein. The purified enzyme ran as a single protein band when analyzed both by native PAGE and SDS-PAGE corresponding to an Mr of 220,000 Da, which consists of 4 subunits with identical Mr of 54,000 Da. The pI of purified enzyme was found to be 5.2 by isoelectric focusing on ultrathin polyacrylamide gels. The purified catalase has an optimum temperature of activity at 40 degrees C, whereas it is stable between 0 degrees and 50 degrees C. As regards pH, the enzyme has an optimum activity at pH 7.0 and it is stable in the range pH 6-8. The absorption spectrum of the purified enzyme exhibited 2 peaks at 280 nm and 405 nm.

Impregnation of biological material by ZnI2-OSO4, KI-OSO4 and NaI-OSO4 mixtures for electron microscopic observations: chemical interpretation of the reaction

Alkaline iodide-osmium tetroxide mixtures were used in an electron microscopic study of plant cells and gave better results in the preservation of the cell structure in contrast to the cell structure observed when ZnI2-OSO4 mixtures are used. The electron density observed in the reactive sites of the cell by OSO4-iodide mixtures is controlled by the presence and oxidation state of iodine that acts as a regulator of the potential redox of the reaction of OSO4 with the biological material.