Efficient in vitro regeneration of leek (Allium ampeloprasum L.) via flower stalk segments

A new simple, efficient and rapid in vitro method for mass clonal propagation of leek (Allium ampeloprasum L.) plants, using small (5 mm) flower stalk (peduncle) explants, was established. Adventitious shoots were produced from single subepidermal cells. A wide variation in the percentage of regenerating explants and number of regenerated shoots per explant between individual plants within one cultivar was observed. The concentration of the growth regulators 6-benzylaminopurine and α-naphthalene-acetic acid influenced the percentage of regenerating explants and the average number of regenerated shoots per explant. A combination of 10 mg.l(-1) 6-benzylaminopurine and 10 mg.l(-1) α-naphthalene-acetic acid, resulted in a maximum percentage of regenerating explants and a high average number of regenerated shoots per explant. The percentage of regenerating explants and the average number of regenerated shoots per explant decreased with increasing flower stalk length (age). The basal explants gave both the highest percentage of regenerating explants and average number of regenerated shoots per explant. An average of 300 shoots per flower stalk was obtained for all plants, making this new in vitro method a powerful tool in hybrid leek breeding.

Factors affecting the inhibition by antisense RNA of granule-bound starch synthase gene expression in potato

Inhibition of expression of specific genes by means of antisense RNA is widely used, although little information is available regarding conditions that affect the efficacy of inhibition. In this study, inhibition of granule-bound starch synthase (GBSS), a key enzyme in starch biosynthesis, is used as a model system. Eleven antisense constructs derived from the full-length GBSS cDNA, the genomic GBSS coding region (gDNA) or fragments of each of these sequences, were analysed with respect to their inhibitory effect. Introduction of full-length gDNA constructs yielded a lower percentage of transgenic clones showing complete inhibition than did introduction of the full-length cDNA constructs. This may be caused by a lower antisense binding capacity of the former due to the relatively low GC content in intron sequences present in the gDNA constructs. The presence of multiple T-DNA insertions was related to a higher degree of inhibition. Putative polyadenylation signals on the antisense strand of the GBSS gene resulted in a premature stop of transcription of some of the antisense genes, as demonstrated by the expression of smaller antisense RNA transcripts. Introduction of antisense constructs driven by the promoter of the (target) GBSS gene resulted in a higher percentage of clones with complete inhibition than introduction of antisense constructs driven by the 35S CaMV promoter. Complete antisense inhibition was achieved in 25% of the clones carrying the antisense construct pKGBA50, which is based on the GBSS promoter and the full-length GBSS cDNA. Thus, it is concluded that the use of pKGBA50 is very suitable for the modification of the composition of potato tuber starch via antisense RNA.

Development of a cyclic somatic embryogenesis regeneration system for leek (Allium ampeloprasum L.) using zygotic embryos

In leek (Allium ampeloprasum L.) a cyclic system of somatic embryogenesis was developed. Somatic embryos used for cyclic embryogenesis were able to develop the same type of embryogenic callus as zygotic embryos in the primary cycle. For the first time a comparison of the efficiencies of both expiants was made. Ten families were investigated for somatic embryogenesis. There was a genetic relationship with respect to somatic embryo production between the reciprocal crosses. From each family one genotype was selected for investigating cyclic somatic embryogenesis. Different levels of somatic embryo production were found between the expiants of zygotic and somatic embryos. The two best genotypes, 92.001-03 and 92.002-33 produced twice as many somatic embryos as the overall average. On average, 56% of the somatic embryos finally developed into greenhouse plantlets.

Field evaluation of transgenic potato plants expressing an antisense granule-bound starch synthase gene: increase of the antisense effect during tuber growth

Transgenic plants of a tetraploid potato cultivar were obtained in which the amylose content of tuber starch was reduced via antisense RNA-mediated inhibition of the expression of the gene encoding granule-bound starch synthase (GBSS). GBSS is one of the key enzymes in the biosynthesis of starch and catalyses the formation of amylose. The antisense GBSS genes, based on the full-length GBSS cDNA driven by the 35S CaMV promoter or the potato GBSS promoter, were introduced into the potato genome by Agrobacterium tumefaciens-mediated transformation. Expression of each of these genes resulted in the complete inhibition of GBSS gene expression, and thus in the production of amylose-free tuber starch, in mature field-grown plants originating from rooted in vitro plantlets of 4 out of 66 transgenic clones. Clones in which the GBSS gene expression was incompletely inhibited showed an increase of the extent of inhibition during tuber growth. This is likely to be due to the increase of starch granule size during tuber growth and the specific distribution pattern of starch components in granules of clones with reduced GBSS activity. Expression of the antisense GBSS gene from the GBSS promoter resulted in a higher stability of inhibition in tubers of field-grown plants as compared to expression from the 35S CaMV promoter. Field analysis of the transgenic clones indicated that inhibition of GBSS gene expression could be achieved without significantly affecting the starch and sugar content of transgenic tubers, the expression level of other genes involved in starch and tuber metabolism and agronomic characteristics such as yield and dry matter content.

Bacteriophage P2 and P4 morphogenesis: assembly precedes proteolytic processing of the capsid proteins

Several of the structural proteins of phage P2 and its satellite P4 undergo proteolytic processing during development of mature phage particles. Here, we report that uncleaved shell protein, gpN, is present in immature capsids of both P2 and P4, showing that assembly precedes processing. This excludes the possibility that processing of gpN is involved in capsid size determination. We also find that N*, the fully processed version of gpN, produced from a plasmid, can assemble into both P2- and P4-sized particles, implying that the amino-terminal end of gpN is not required for assembly initiation nor for the formation of a T = 4 shell. As may be expected for a scaffolding protein, we find that gpO coexists with gpN in immature P2, as well as P4, capsids. This result supports the conclusion that gpO is required for both phages and strongly suggests that the O derivative, h7 (found in mature capsids), results from proteolytic cleavage after gpN/gpO coassembly.

[Kasabach-Merritt syndrome]

Kasabach Merritt syndrome, first recognized in 1940, is characterized by haemangiomatosis, thrombocytopenia and intravascular coagulation. It is most often seen in children, rarely in adults. The mortality rate is 20-30%. Treatment is by removing the haemangiomatosis and correcting the consumptive coagulopathy. The purpose of this paper is to present a patient with Kasabach Merritt syndrome with haemangiomatosis in the spleen and the liver. A review of the relevant literature is given.

Expression of a wild-type GBSS gene introduced into an amylose-free potato mutant by Agrobacterium tumefaciens and the inheritance of the inserts at the microsporic level

Granule-bound starch synthase (GBSS) catalyses the synthesis of amylose in starch granules. Transformation of a diploid amylose-free (amf) potato mutant with the gene encoding GBSS leads to the restoration of amylose synthesis. Transformants were obtained which had wild-type levels of both GBSS activity and amylose content. It proved to be difficult to increase the amylose content above that of the wild-type potato by the introduction of additional copies of the wild-type GBSS gene. Staining of starch with iodine was suitable for investigating the degree of expression of the inserted GBSS gene in transgenic amf plants. Of the 19 investigated transformants, four had only red-staining starch in tubers indicating that no complementation of the amf mutation had occured. Fifteen complemented transformants had only blue-staining starch in tubers or tubers of different staining categories (blue, mixed and red), caused either by full or partial expression of the inserted gene. Complementation was also found in the microspores. The segregation of blue- and red-staining microspores was used to analyse the inheritance of the introduced GBSS genes. A comparison of the results from microspore staining and Southern hybridisation indicated that, in three tetraploid transgenics, the gene was probably inserted before (duplex), and in all others after, chromosome doubling (simplex). The partial complementation was not due to methylation of the HPAII/MSPI site in the promoter region. Partially complemented plants had low levels of mRNA as was found when the GBSS expression levels were inhibited by anti-sense technology.

The first and second backcross progeny of the intergeneric fusion hybrids of potato and tomato after crossing with potato

Somatic fusion hybrids between the diploid potato and tomato were backcrossed to several genotypes of potato. Two ploidy levels of fusion hybrids, 4x and 6x, were used as female parents in backcrosses with five clones of 4x-potato. An estimate of the berry set and "seed set" in immature berries harvested 14-21 days after pollination indicated that crosses between certain combinations of 6x-fusion hybrids and male parents were more successful than others. The culture of over 4000 young seeds from berries harvested 2-2.5 weeks after pollination gave rise to a single seedling, 93.6701, from the cross between the 6x-fusion hybrid C 31-17-1 and the 4x-potato AM 66.42. This seedling was found to possess a pentaploid chromosome number, which was expected of a 6x × 4x cross. Isozyme analysis and DNA hybridisation studies confirmed that the seedling 93.6701 was indeed a backcross (BC1) progeny. Morphologically, this BC1 plant resembled potato with respect to plant habit, leaf shape, stolons and tuber characteristics, while some of the characters, such as floral morphology and the fragrance of the crushed leaves (typical of tomato), were intermediate. It was male sterile but could be successfully hybridized with 4x-potato through in vitro culture of yound seeds; thus, BC2 plants were obtained. The possibilities of backcrossing and the potential use of BC1 and BC2 plants in genetics and breeding are discussed.

Multiple alleles for tuber shape in diploid potato detected by qualitative and quantitative genetic analysis using RFLPs

Tuber shape in potato is commonly regarded as displaying continuous variation, yet at the diploid level phenotypes can be discerned visually, having round or long tubers. Inheritance of qualitative tuber shape can be explained by a single locus Ro, round being dominant to long. With restriction fragment length polymorphisms (RFLPs) the Ro locus was mapped on chromosome 10. Tuber shape was also studied as a quantitative trait, using the length/width ratio as trait value. The estimated broad sense heritability was h2 = 0.80. The morphologically mapped Ro locus explained 75% of the genetic variation, indicating the presence of a major quantitative trait locus (QTL) at the Ro locus and minor genetic factors. RFLP alleles linked with Ro alleles were used to divide the progeny into four genotypic classes: RofemaleRomale:Rofemalero:roRomale:roro = 1:1:1:1. The recessive ro allele is identical by descent in both parents. The significantly different effects (P = 0.0157) of the non-identical alleles Rofemale and Romale provided evidence for multiallelism at the Ro locus. Linkage mapping of the Ro locus was compared with QTL mapping. Only those markers which are polymorphic in both parents allow accurate QTL mapping when genetic factors segregate from both parents. This finding applies to QTL mapping in all outbreeders without homozygous inbred strains.

Bacteriophage P2 and P4 morphogenesis: identification and characterization of the portal protein

The portal structure has been implicated in several aspects of the bacteriophage life cycle, including capsid assembly initiation and DNA packaging. Here we present evidence that P2 gene Q codes for the P2 and P4 portal protein. First, microsequencing shows that capsid protein h6 is derived from gpQ, most probably by proteolytic cleavage. Second, antibodies against gpQ bind to the portal structure in disrupted P2 phage virions, as observed by electron microscopy. Third, gpQ partially purified from an overexpressing plasmid assembles into portal-like structures. We also show by microsequencing that capsid protein h7 is encoded by the P2 scaffold gene, O, and is probably derived from gpO by proteolytic cleavage. Previous work has demonstrated processing of the major capsid protein. Thus, all essential capsid proteins of P2 and P4 are proteolytically cleaved during the morphogenetic process.

Segregation analysis and RFLP mapping of the R1 and R3 alleles conferring race-specific resistance to Phytophthora infestans in progeny of dihaploid potato parents

Phytophthora infestans (Mont.) de Bary is the most important fungal pathogen of the potato (Solanum tuberosum). The introduction of major genes for resistance from the wild species S. demissum into potato cultivars is the earliest example of breeding for resistance using wild germplasm in this crop. Eleven resistance alleles (R genes) are known, differing in the recognition of corresponding avirulence alleles of the fungus. The number of R loci, their positions on the genetic map and the allelic relationships between different R variants are not known, except that the R1 locus has been mapped to potato chromosome V. The objective of this work was the further genetic analysis of different R alleles in potato. Tetraploid potato cultivars carrying R alleles were reduced to the diploid level by inducing haploid parthenogenetic development of 2n female gametes. Of the 157 isolated primary dihaploids, 7 set seeds and carried the resistance alleles R1, R3 and R10 either individually or in combinations. Independent segregation of the dominant R1 and R3 alleles was demonstrated in two F1 populations of crosses among a dihaploid clone carrying R1 plus R3 and susceptible pollinators. Distorted segregation in favour of susceptibility was found for the R3 allele in 15 of 18 F1 populations analysed, whereas the R1 allele segregated with a 1:1 ratio as expected in five F1 populations. The mode of inheritance of the R10 allele could not be deduced as only very few F1 hybrids bearing R10 were obtained. Linkage analysis in two F1 populations between R1, R3 and RFLP markers of known position on the potato RFLP maps confirmed the position of the R1 locus on chromosome V and localized the second locus, R3, to a distal position on chromosome XI.

Formation and Deposition of Amylose in the Potato Tuber Starch Granule Are Affected by the Reduction of Granule-Bound Starch Synthase Gene Expression

The synthesis of amylose in amyloplasts is catalyzed by granule-bound starch synthase (GBSS). GBSS gene expression was inhibited via antisense RNA in Agrobacterium rhizogenes-transformed potato plants. Analysis of starch production and starch granule composition in transgenic tubers revealed that reduction of GBSS activity always resulted in a reduction of the production of amylose. Field experiments, performed over a 2-year period, showed that stable inhibition of GBSS gene expression can be obtained. Microscopic evaluation of iodine-stained starch granules was shown to be a sensitive system for qualitative and quantitative examination of amylose formation in starch granules of transgenic potato tubers. In plants showing inhibition of GBSS gene expression, the reduced amylose content in tuber starch was not a consequence of a lower amylose content throughout the entire starch granule. Starch granules of transgenic tubers were found to contain amylose at a percentage similar to wild-type starch in a core of varying size at the hilum of each granule. This indicated that reduced GBSS gene expression results in amylose formation in a restricted zone of the granules. The size of this zone is suggested to be dependent on the GBSS protein level. During development of the granules, the available GBSS protein is thought to become limiting, resulting in the formation of starch that lacks amylose. RNA gel blot analysis of tuber tissue showed that inhibition of GBSS gene expression resulted in a reduced GBSS mRNA level but did not affect the expression level of other starch synthesizing enzymes. Antisense RNA could only be detected in leaf tissue of the transgenic plants.

Posttraumatic osteolysis of the pubic bone simulating malignancy

Posttraumatic osteolysis (PO) of the os pubis is a diagnostic entity characterized at radiography by rapidly progressing destructive changes in fractures of the pubic body or rami. Fourteen patients with PO are here reported of whom in 8 the radiographic course of the condition was followed. They were all post-menopausal women and 7 were predisposed to osteopenia. The primary fractures were related to mild trauma in 7 patients and 7 had insufficiency fractures. Four patients had bilateral symmetrical PO. All 14 patients had concomitant insufficiency fractures of the sacrum observed at radiography, CT, scintigraphy or MR, probably due to pelvic instability caused by the PO of the os pubis. Symptoms of the sacral fractures usually dominated the clinical condition. Bony healing of the PO did not occur in any of the patients, but in all 8 patients followed radiographically, the fractures of the sacrum healed clinically and at CT. Knowledge about the condition is important to avoid unnecessary biopsy of the PO considered a metastatic lesion and/or extensive diagnostic search for a primary tumor.

Formation and Deposition of Amylose in the Potato Tuber Starch Granule Are Affected by the Reduction of Granule-Bound Starch Synthase Gene Expression

The synthesis of amylose in amyloplasts is catalyzed by granule-bound starch synthase (GBSS). GBSS gene expression was inhibited via antisense RNA in Agrobacterium rhizogenes-transformed potato plants. Analysis of starch production and starch granule composition in transgenic tubers revealed that reduction of GBSS activity always resulted in a reduction of the production of amylose. Field experiments, performed over a 2-year period, showed that stable inhibition of GBSS gene expression can be obtained. Microscopic evaluation of iodine-stained starch granules was shown to be a sensitive system for qualitative and quantitative examination of amylose formation in starch granules of transgenic potato tubers. In plants showing inhibition of GBSS gene expression, the reduced amylose content in tuber starch was not a consequence of a lower amylose content throughout the entire starch granule. Starch granules of transgenic tubers were found to contain amylose at a percentage similar to wild-type starch in a core of varying size at the hilum of each granule. This indicated that reduced GBSS gene expression results in amylose formation in a restricted zone of the granules. The size of this zone is suggested to be dependent on the GBSS protein level. During development of the granules, the available GBSS protein is thought to become limiting, resulting in the formation of starch that lacks amylose. RNA gel blot analysis of tuber tissue showed that inhibition of GBSS gene expression resulted in a reduced GBSS mRNA level but did not affect the expression level of other starch synthesizing enzymes. Antisense RNA could only be detected in leaf tissue of the transgenic plants.

Isolation and characterization of a cDNA encoding granule-bound starch synthase in cassava (Manihot esculenta Crantz) and its antisense expression in potato

A tuber-specific cDNA library of cassava (Manihot esculenta Crantz) was constructed and a full-length cDNA for granule-bound starch synthase (GBSS, also known as waxy protein), the enzyme responsible for the synthesis of amylose in reserve starch, was cloned. Sequencing of the cloned cDNA showed that it has 74% identity with potato GBSS and 60-72% identity with GBSS from other plant species. The cDNA encodes a 608 amino acid protein of which 78 amino acids form a chloroplast/amyloplast transit peptide of 8.37 kDa. The mature protein has a predicted molecular mass of 58.61 kDa (530 amino acids). Comparison of the GBSS proteins of various plant species and glycogen synthase of bacteria showed extensive identity among the mature form of plant GBSS proteins, in which the monocots and dicots form two separate branches in the evolutionary tree. From analysis of the genomic DNA of allotetraploid cassava, it is shown that GBSS is a low-copy-number gene. GBSS transcript is synthesized in a number of different organs, but most abundantly in tubers. Potato plants were transformed with the cassava GBSS cDNA in antisense orientation fused between the potato GBSS promoter and the nopaline synthase terminator. The expression of the endogenous GBSS gene in these transgenic potato plants was partially or completely inhibited. Complete inhibition of GBSS activity by the cassava antisense gene resulted in absence of GBSS protein and amylose giving rise to almost complete amylose-free potato starch. This shows that also heterologous genes can be used to achieve antisense effects in other plant species.

[Pulse oximetry and obstructive sleep apnea]

We report a case of a 54 years old man, treated with Methylphenidate (Ritalin) because of narcolepsy, who was referred with suspected vertebro-basilar insufficiency. In the hospital, apnoea during sleep attacks were observed. A polysomnography showed marked obstructive sleep apnoea with a disturbed hypnogram, but during the apnoeas the oxygen saturation only decreased by three to six percent. If a patient suspected for obstructive sleep apnoea has only small desaturations, an oximetry can be insensitive as the only "sleep examination", and a full polysomnography is recommended.

Salen-manganese complexes are superoxide dismutase-mimics

Complexes of manganese have previously been shown to exhibit SOD activity. In this study, we tested the ability of several (salen)-manganese complexes to scavenge O2.. Both neutral and cationic complexes were determined to be SOD-mimics. The activity of the complexes was not affected by the presence of bovine serum albumin in the assay. For most compounds, the activity was inhibited by the addition of EDTA. The stability and high catalytic activity of some of these molecules suggest that they might have potential use in a variety of conditions which involve overproduction of oxygen free radicals.

[Complications of spinal anesthesia compared to general anesthesia. A prospective study of 408 consecutive orthopedic patients]

In this prospective study the preoperative risk classification and pulmonary status was compared to postoperative mortality and morbidity, following either spinal or general anaesthesia. We studied 408 consecutive orthopaedic patients. Comparing the anaesthetic methods we found no differences in mortality or in frequency of cardiac complications, while the non-cardiac complications were seen more frequently in patients who had undergone spinal anaesthesia (p < 0.05). Patients from the lower risk groups with a preoperative abnormal pulmonary status had a higher frequency of postoperative pulmonary complications following spinal anaesthesia than following general anaesthesia (p = 0.015).

IN CONCLUSION

1) We find no difference in postoperative mortality depending on the anaesthetic method chosen, 2) the predictive value of the Boston Cardiac Risk index is identical for the two anaesthetic methods, and 3) the anaesthetic method of choice for the pulmonary disabled patient has not yet been established.

Identification and mapping of three flower colour loci of potato (S. tuberosum L.) by RFLP analysis

The inheritance of flower colour in diploid potato (2 n = 2x = 24), was found to be controlled by three unlinked loci D, F and P. To determine the allelism with previously described loci and to dissect this oligogenic trait, a set of tester clones with well-defined genotypes was developed. By backcrossing the mapping population with these tester clones it was possible to obtain monogenic segregation ratios. These were required to detect linkage with RFLP loci and, despite distorted Mendelian ratios, the inheritance and mapping of the D, F and P loci could be unambiguously determined. Locus D, involved in the biosynthesis of red anthocyanins, was mapped on chromosome 2, while locus P, involved in the production of blue anthocyanins, was mapped on chromosome 11. Locus F, involved in the flower-specific expression of gene(s) accommodated by the D and P loci, was mapped on chromosome 10. The tester clones and the map position of the D, F and P loci may be of considerable value in simplifying the genetics of anthocyanin pigmentation.

[Respiratory monitoring during sleep]

A review of respiratory disorders of sleep with the possible related clinical alterations are described. Techniques and methods used in non-invasive respiratory monitoring during sleep are presented. Diagnostic events and therapeutic approaches are discussed related to special patient groups: the obstructive sleep apnoea syndrome, asthma, chronic obstructive pulmonary disease and neuromuscular diseases.

Improvements of cyclic somatic embryogenesis of cassava (Manihot esculenta Crantz)

In cassava a cyclic system of somatic embryogenesis was developed. Primary (torpedo shaped or germinated) embryos, originating from leaf lobes, could only be obtained after culture on solid medium. Cyclic embryos, originating from embryos, could be obtained in both liquid and on solid medium. The production of embryos in liquid medium was distinctly higher, faster and more synchronized than on solid medium. Lower densities and fragmentation of starting embryos improved the production significantly. The highest production found was 32.1 embryos per initial embryo. In all treatments the explants initiated multiple embryos. The production of single embryos was achieved by pressing starting embryos through a fine meshed sieve, indicating that embryos can be produced from a piece of tissue with a restricted number of cells. The shoot conversion rate of embryos from liquid medium was comparable with that of embryos from solid medium.