Thesis (doctoral)--Lund University, 1992. / Added t.p. with thesis statement inserted.

The objectives of this thesis were to trace the developmental pathways of somatic embryos of an abscisic-acid independent line of Larix x eurolepis. to catalogue the phenotypes of mature embryos, to determine critical stages of development and to attempt to increase the number of maturing somatic embryos. The low rate of maturation could not be entirely explained by differences in phenotypes of early embryos, critical stages of development, or the lack of plant growth regulators in the medium. In addition, the shape and epidermal type of the mature embryo did not always determine the type of epicotyl produced, nor did it affect the rooting and mortality rates. Six types of embryonal structures were evident in the aggregates of line 2086: (1) a smooth (SEMLS) or (2) rough (REMLS) embryonal mass subtended by a cylindrical, compact, long suspensor. (3) a rough embryonal mass subtended by a long, loose suspensor (REMLLS). (4) a rough embryonal mass subtended by a suspensor arising from greater than one quarter of the surface area of the embryonal mass (REMST). (5) a rough embryonal mass subtended by a short, compact, cylindrical suspensor (REMSS). and (6) a cluster of meristematic cells which may or may not have single suspensor cells attached (MC). For isolated embryonal structures of all types, to continue development into a nodule or a mature embryo was the least common fate, while proliferation and developmental arrest were more common. In general, the more organized embryonal structure types (SEMLS and REMLS) had higher rates of maturation compared to the other 4 types but the most common fate was still developmental arrest (74% SEMLS. 62% REMLS), followed by proliferation (10% SEMLS. 30% REMLS), and nodule or embryo development (16% SEMLS. 9% REMLS). REMLLS and REMST embryonal structures became developmentally arrested or proliferated (43-47%) while the rate of nodules/mature embryos production was 9-11%. Neither individual REMSS nor MC structures produced any nodules or mature embryos, but REMSS had a lower rate of developmental arrest (81%) and a higher rate of proliferation (19%) than MC (89% and 11% respectively). Embryos at more advanced stages of development were less likely to die, become developmentally arrested or become nodules, but more likely to become mature embryos than embryos at less advanced stages of development. A critical stage of development appeared to be the focal zone stage at the formation of a complete polyphenol band around the basal end of the embryonal mass. At this stage, the majority of immature embryos became mature embryos (61%) while only 3% of the embryos died. 10% became developmentally arrested, and 20% became nodules. The majority of mature somatic embryos were normally proportioned with a smooth epidermis (43%) rather than vitrified (12%). normal with a rough epidermis (12%) or misshapen (smooth or rough. 33%). The shape of the mature embryo was associated with the type of epidermis, with mature somatic embryos with normal proportions more likely to have smooth epidermis (78%) than a rough epidermis (22%) while mature embryos with abnormal proportions were as likely to have a smooth epidermis as a rough epidermis. The shape of the mature embryo was associated with the shape of the epicotyl produced. Normal-smooth, mature embryos were more likely to produce normal-smooth epicotyls (73%) than twin epicotyls (21%), vitrified epicotyls (2%) or misshapen epicotyls (5%) compared to vitrified mature embryos (42% normal-smooth epicotyls, 34% twin epicotyls, 23% vitrified epicotyls, 1% misshapen epicotyls) or misshapen mature embryos (22% normal-smooth epicotyls, 47% twin epicotyls, 7% vitrified epicotyls, 24% misshapen smooth/rough embryos). The number of mature embryos which germinated or died was not associated with either the epidermal quality or the shape of the mature embryo. Few SEMLS or REMLS embryonal structures responded to auxin and cytokinin treatments. There appeared to be a trend towards less developmental arrest and proliferation and more nodules/mature embryos produced on media with no auxin compared to media with 2,4-D and a trend towards more developmental arrest and fewer nodules/mature embryos on media without BA compared to media with BA. Only nodules on media without plant growth regulators produced roots or cotyledons. There was no effect of embryonal structure type (SEMLS or REMLS), or sucrose concentration (58 μM or 174 μM) on the maturation of immature embryos, but on media without ABA, fewer immature embryos proliferated or became developmently arrested and more embryos became nodules or mature embryos than on medium with 6-24 μM ABA. / Graduate

This study focused on induction of somatic embryogenesis of Magnolia spp. and cultivars utilizing leaf and seed (immature and mature) tissues with attempted micropropagation experiments. In a preliminary experiment, direct embryo regeneration was successful in a single leaf tissue of M. ‘Yellow Bird’. After various micropropagation experiments, microshoot proliferation rates decreased. As a result of minimal leaf material, mature seeds were utilized but had contamination issues. Subsequent experiments utilized immature seeds. M. ‘Leonard Messel’ and M. stellata had significantly greater embryo regeneration rates and M. ‘Rosea’, M. stellata, and M. kobus had greater callus induction rates. Woody Plant Medium had significantly greater rates of embryo regeneration as compared to Yellow Poplar medium. Further experimental measures including various collection times of immature seeds are necessary for an efficient regeneration protocol to support potential research utilizing floral-inducing genes to induce rapid breeding cycles for selection of magnolias with diverse floral characteristics.

No description available.

This paper examined the claims postulated by the somatic marker hypothesis and compares those claims to the current evidence surrounding the neural basis of alexithymia. The results were then compared to see if they contradict or have a distinct localisation in the brain separate from those behavioural brain regions hypothesized by the somatic marker hypothesis. It was concluded that the somatic marker hypothesis and the neural basis for alexithymia share certain regions of interest, primarily the amygdala and insula, but also potentially the anterior cingulate cortex.

Note:

No description available.

Date palms (Phoenix dactylifera L.) and papayas (carica papaya L.) are two commercially important plantation crops. Their economic potential in South Africa and worldwide is increasing. However, due to disease, pests and socio-economic reasons, planting material is in short supply. Micropropagation provides a method for rapidly propagating selected superior cultivars for commercial and environmental interests. A satisfactory process for the regeneration of elite cultivars should result in individuals phenotypically and genetically identical to the explant from which they were derived. However, due to somaclonal variation generated during in vitro culture, the true-to-typeness is questionable. For this reason a southern African survey for off-types on date palms produced using somatic embryogenesis was conducted. Plant growth variations such as leaf variegation, seedless fruit, broad leaves, compact growth habit and parthenocarpic fruit were recorded and possible explanations for each phenomenon given. Factors influencing the date palm initiation process such as decontaminating agents, plant growth regulators, explant type and nurse cultures were investigated. A double decontamination process with 2.6% and 1.3% sodium hypochlorite was most effective at reducing contamination. Alternative plant growth regulators, TIBA and NAA were ineffective as a substitute to 2,4-D for somatic embryogenesis. The size of the explant and "nurse cultures" played an important role in explant growth and initiating callogenesis. A "nurse culture" reduced the time in culture significantly. The problem areas in the three commercial tissue culture techniques used for date palms were outlined. In the second part of the study, factors influencing initiation, multiplication and rooting of papaya were determined. Presoaking with antibiotic, Rifampicin, and various fungicides had a positive effect on decontaminating papaya explants, while Bronocide™ had little effect. Various methods and materials were used to optimize papaya multiplication and rooting in vitro. The growth and multiplication of papaya was optimal at 50 g l ¯¹ sucrose. Gelling agent, Gelrite, increased multiplication rates significantly but had a negative effect on overall growth causing plants to become vitrified. The addition of activated charcoal reduced vitrification but also reduced multiplication rate. Activated charcoal greatly improved overall growth of papaya and reduced leaf senescence. No vitrification was observed in multiplying papaya cultures where agar and Gelrite combinations were used, but multiplication rate was reduced compared to cultures grown on Gelrite alone. callus removal from the bases of papaya at subculturing reduced multiplication rate and influenced elongation, growth and leaf senescence. Lower concentrations magar and Gelrite improved rooting percentages, but did not provide good support. Damaged roots and lower rooting percentages were observed on plantlets treated with IBA for four weeks compared to those exposed for only two days. A one hour pulse with a higher concentration (5 mg l ¯¹) of IBA greatly improved rooting percentage and further eliminated a second subculture onto an IBA-free medium after two days. Good, strong roots with root hairs were produced on vermiculite medium containing equal volumes of DS salts and vitamins. Modified lids with cotton-wool plugs also reduced leaf abscission. In vitro grafting using stericrepe proved impractical, while grafting in vitro unrooted papaya plants onto ex vitro seedlings was more successful, using wedge and slant grafts. Grafts sealed with pegs and Parafilm™ were less effective. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2000.

The present study examines the relationship of emotional awareness to anticipatory psychophysiological markers and performance on the Iowa Gambling Task (IGT). The IGT is a computerized card game that simulates real-life decisions through uncertainty of reward or punishment. The participant’s goal is to make advantageous card choices. Anticipatory somatic markers of physiological arousal, like electrodermal activity and heart rate, have been proposed to bias decisions in the IGT. The central hypothesis is that a participant’s emotional awareness is related to their ability to make advantageous decisions through biasing psychophysiological responses. The Toronto Alexithymia Scale was used to assess each participant’s emotional awareness. Less emotional awareness was associated with enhanced performance on the IGT. However, anticipatory physiological arousal (electrodermal activity and heart rate) and emotional awareness yielded no significant relationships. Findings suggest a need for further research on cognitive models, such as the expectancy valence model, in relation to decision-making.

Conifer species are subjected to major time constraints in tree improvement because of their long regeneration cycle and large sizes. However, integration of developing biotechnologies could significantly reduce this time limitation in tree breeding programs. In this regard, somatic embryogenesis (SE) offers a great potential in commercially important Turkish red pine (Pinus brutia TEN.) for rapid production of larger number of clones as well as capture of greater genetic gains. In this study, seven collections were done to sample precotyledonar zygotic embryos for induction of embryogenic tissue (ET) from 15 clones located in Antalya. Afterwards, abscisic acid, carbohydrates, polyethylene glycol (PEG), and gellan gum were tested to obtain mature somatic embryos in maturation experiments. Analyses of variance showed a significant variation among collection dates (43.1% of total variance) and clones studied (18.8% of total variance) for induction of ETs. Overall initiation frequency of ET in this study was 11.6% with clonal range of 4.7 &amp / #8211 / 24.1%. Of those tested maturation treatments, 80&amp / #956 / M ABA, sucrose and maltose at 3 and 6%, 3.75% PEG combined with 1% gellan gum were found to be suitable for maturation of somatic embryos in Turkish red pine. Sixty nine somatic embryos were obtained from Clone 22, which was one of tested clones. Induction frequencies could be further improved by using different basal media and/or manipulating media components, such as plant growth regulators. For proper maturation of somatic embryos, embryogenic lines need to be screened to find suitable lines, which are developmentally responsive to ABA treatment.