Patterns of DNA and chromosome variation during in vitro growth in various genotypes of potato

Patterns of variation in nuclear DNA content and chromosome number were analysed in a temporal sequence, during in vitro growth of calli and cell suspensions in two monohaploids, a dihaploid and a tetraploid of potato (Solanum tuberosum). The results showed that both polyploidization and aneuploidy occurred during the initial stages of callus induction in all the genotypes. With further growth of callus, the frequency and extent of polyploidy and aneuploidy increased. In addition, the patterns of DNA and chromosome variation in cell suspension cultures revealed continued mitotic activity and transmission of cells with higher ploidy levels and aneuploidy. The results suggest that endoreduplication as well as endomitosis are important mechanisms of polyploidization, and that chromosome lagging and non-disjunction contribute to the production of aneuploidy.The various genotypes cultured under the same in vitro growth conditions differed in genetic instability, as assessed from the rate and degree of polyploidization and aneuploidy. Monohaploids showed more rapid rate of polyploidization than the dihaploid and tetraploid potatoes. It was concluded that the differences in genetic stability were due to different ploidy levels and genetic make-up of the genotypes.     

Apomixis in plants: structural and functional aspects of diplospory inPoa nemoralis andP. palustris

Summary Data on structural and functional aspects of mitotic diplospory and later stages of apomictic seed formation are reported forPoa palustris andP. nemoralis. In this study, the plant material of two Russian populations ofP. nemoralis andP. palustris were used for transmission electron microscope observations. Seed formation was investigated by phase contrast microscopy in two populations ofP. nemoralis collected in The Netherlands. The processes of transformation of the megasporocytes to the megaspore mother cells of diplosporous embryo sacs, and thereafter to one- and two-nucleate diplosporous embryo sacs (Antennaria type) were characterized by an increase of cell size, structural and functional reorganization of the nucleus, nucleolus, and cytoplasm, and cell isolation as a result of thickening of the cell wall. These were accompanied by an increase in the cell metabolic activity inferred from visual evidence of the activation of nucleus, nucleolus, endoplasmic reticulum, dictyosomes, mitochondria, and from the appearance of a dense population of ribosomes and polysomes. The diplosporous embryo sac of the Antennaria type was characteristic for bothP. nemoralis andP. palustris. No signs of the presence of synaptonemal complexes were observed during the process of diplosporous-embryo-sac megaspore mother cell differentiation and division. About 90–95% of the diploid egg cells of diplosporous embryo sacs were able to produce apomictic embryos. These embryos developed before anthesis. However, many of them degenerated at the globular stage because of lack of endosperm. The ultrastructural events occurring during the process of diplospory of apomictic species, and meiosis and megagametogenesis of sexually reproduced plants are discussed.Abbreviations DMC megaspore mother cell of diplosporous embryo sac - TEM transmission electron microscopy - ER endoplasmic reticulum     

Embodied Subjects and Fragmented Objects: Women’s Bodies,Assisted Reproduction Technologies and the Right to Self-Determination

This article focuses on the transformation of the female reproductive body with the use of assisted reproduction technologies under neo-liberal economic globalisation, wherein the ideology of trade without borders is central, as well as under liberal feminist ideals, wherein the right to self-determination is central. Two aspects of the body in western medicine—the fragmented body and the commodified body, and the integral relation between these two—are highlighted. This is done in order to analyse the implications of local and global transactions in women’s reproductive body parts for their right to self-determination and individual agency and what this means for their embodiment. We conclude by exploring whether women can become embodied subjects by exercising their proprietary right to their bodies through directing technology to achieve their own goals, while at the same time being fragmented into parts and losing their personhood and bodily integrity. This article has been translated and adapted from the Dutch version published in the Tijdschrift voor Humanistiek, 2006; 26(7).     

Myocardial Metastases on 6-[18F] fluoro-L-DOPA PET/CT: A Retrospective Analysis of 116 Serotonin Producing Neuroendocrine Tumour Patients

Purpose

This study evaluates the prevalence of cardiac metastases in patients with serotonin producing neuroendocrine tumours (NET), examined with ¹⁸F-FDOPA PET/CT, and the relationship of these metastases to the presence of carcinoid heart disease (CHD) based on echocardiography.

Background

CHD occurs in patients with serotonin producing NET. The diagnostic method of choice remains echocardiography. The precise prevalence of cardiac metastases is unknown given the limitations of standard technologies. Nuclear medicine modalities have the potential to visualize metastases of NET.

Methods

All patients who underwent ¹⁸F-FDOPA PET/CT because of serotonin producing NET between November 2009 and May 2012 were retrospectively analyzed. The presence of cardiac metastasis was defined as myocardial tracer accumulation higher than the surrounding physiological myocardial uptake. Laboratory tests and transthoracic echocardiography (TTE) results were digitally collected.

Results

116 patients (62 male) underwent ¹⁸F-FDOPA PET/CT, mean age was 61±13 years. TTE was performed in 79 patients. Cardiac metastases were present in 15 patients, of which 10 patients also underwent TTE. One patient had both cardiac metastasis (only on ¹⁸F-FDOPA PET/CT) and echocardiographic signs of CHD. There were no differences in echocardiographic parameters for CHD between patients with and without cardiac metastases. TTE in none of the 79 patients showed cardiac metastases.

Conclusion

The prevalence of cardiac metastases detected with ¹⁸F-FDOPA PET/CT in this study is 13%. ¹⁸F-FDOPA PET/CT can visualize cardiac metastases in serotonin producing NET patients. There appears to be no relationship between the presence of cardiac metastases and TTE parameters of CHD.     

Cloning and characterization of the durable tomato mosaic virus resistance gene Tm-22 from Lycopersicon esculentum

In tomato, infections by tomato mosaic virus are controlled by durable Tm-2² resistance. In order to gain insight into the processes underlying disease resistance and its durability, we cloned and analysed the Tm-2² resistance gene and the susceptible allele, tm-2. The Tm-2² gene was isolated by transposon tagging using a screen in which plants with a destroyed Tm-2² gene survive. The Tm-2² locus consists of a single gene that encodes an 861 amino acid polypeptide, which belongs to the CC-NBS-LRR class of resistance proteins. The putative tm-2 allele was cloned from susceptible tomato lines via PCR with primers based on the Tm-2² sequence. Interestingly, the tm-2 gene has an open reading frame that is comparable to the Tm-2² allele. Between the tm-2 and the Tm-2² polypeptide 38 amino acid differences are present of which 26 are located in the second half of the LRR-domain. Susceptible tomato plants, which were transformed with the Tm-2² gene, displayed resistance against ToMV infection. In addition, virus specificity, displayed by the Tm-2² resistance was conserved in these transgenic lines. To explain the durability of this resistance, it is proposed that the Tm-2²-encoded resistance is aimed at the Achilles' heel of the virus.     

Survival after Locoregional Recurrence or Second Primary Breast Cancer: Impact of the Disease-Free Interval

The association between the disease-free interval (DFI) and survival after a locoregional recurrence (LRR) or second primary (SP) breast cancer remains uncertain. The objective of this study is to clarify this association to obtain more information on expected prognosis. Women first diagnosed with early breast cancer between 2003–2006 were selected from the Netherlands Cancer Registry. LRRs and SP tumours within five years of first diagnosis were examined. The five-year period was subsequently divided into three equal intervals. Prognostic significance of the DFI on survival after a LRR or SP tumour was determined using Kaplan-Meier estimates and multivariable Cox regression analysis. Follow-up was complete until January 1, 2014. A total of 37,278 women was included in the analysis. LRRs or SP tumours were diagnosed in 890 (2,4%) and 897 (2,4%) respectively. Longer DFI was strongly and independently related to an improved survival after a LRR (long versus short: HR 0.65, 95% CI 0.48–0.88; medium versus short HR 0.81, 95% CI 0.65–1.01). Other factors related to improved survival after LRR were younger age (<70 years) and surgical removal of the recurrence. No significant association was found between DFI and survival after SP tumours. This is the first study to explore the association between the DFI and survival after recurrence in a nationwide population-based cancer registry. The DFI before a LRR is an independent prognostic factor for survival, with a longer DFI predicting better prognosis.     

Interspecific transfer of isolated plant mitochondria by microinjection

Summary Data on isolation, purification and transfer of mitochondria from a cytoplasmic male sterile line of the Ogura type of Raphanus sativus to a male fertile line of Brassica napus are reported. Microinjection has been used for the transfer of the donor mitochondria to the recipient protoplasts. The injected protoplasts were identified and followed individually throughout their development using a computerized microscope stage which greatly enhanced the number of injections (five-fold). The transferred donor mitochondria were stably maintained during several successive cell divisions, revealing that they were viable and functional. Several calluses were obtained from injected protoplasts without using any selection pressure. Restriction fragment length analysis of seventeen calluses, using mitochondrial DNA probes, indicated that three contained the donor Ogura type mitochondria. No recombinant types of mitochondria have been observed. Flow cytometric and karyotype analyses of the calluses revealed the presence of similar amount of DNA and chromosome number as those of the recipient plants of B.napus. The application of microinjection for the manipulation of cytoplasmic composition is discussed.Abbreviations ATPase adenosine triphosphate phosphohydrolase - BSA bovine serum albumin - CMS cytoplasmic male sterility - DIOC6(3) 3,3-dihexyloxacarbocyanine-iodide - mt mitochondria(I) - PEG polyethylene glycol - RFLP restriction fragment length polymorphism - UV ultraviolet     

Identification and molecular analysis of transgenic potato chromosomes transferred to tomato through microprotoplast fusion

 Results are reported on the integration sites and copy number of alien marker genes neomycin phosphotransferase II (nptII) and β-glucuronidase (uidA), introduced into diploid potato Solanum tuberosum through transformation by Agrobacterium tumefaciens. Also, the transgenic potato chromosomes 3 and 5 harbouring the nptII and uidA genes, which were transferred to tomato (wild species Lycopersicon peruvianum) by microprotoplast fusion, as revealed by genomic in situ hybridization (GISH), were identified by RFLP analysis using chromosome-specific markers. The data revealed three integration sites in the donor potato genome, each containing the uidA gene, and two also harbouring the nptII gene. Analysis of monosomic-addition hybrid plants obtained after microprotoplast fusion showed that each of these three integration sites is located on a different potato chromosome. The microprotoplast hybrid plants contained only the chromosomes that carried the selectable gene nptII. The data on sexual transmission of the donor potato chromosome carrying the uidA and nptII genes were obtained by analysing the first backcross progeny (BC₁) derived from crossing a monosomic-addition hybrid plant to tomato (L. peruvianum). The glucuronidase (GUS) assay and PCR analysis using primers for the uidA gene indicated the presence of the potato chromosome in GUS-positive and its absence in GUS-negative BC₁ plants. RFLP analysis confirmed sexual transmission of the potato chromosome carrying the nptII and uidA genes to the BC₁ plants. A few BC₁ plants contained the nptII and uidA genes in the absence of the potato additional chromosome, indicating that the marker genes were integrated into the tomato genome. The potential applications of the transfer of alien chromosomes and genes by microprotoplast fusion technique are discussed. Recieved: 1 September 1996 / Accepted: 20 September 1996