Development and germination of Sandersonia aurantiaca (Hook.) seeds : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Biology and Biotechnology at Massey University

Sandersonia aurantiaca (Hook.) has recently become an important horticultural crop through its economic value for export of its cut flowers and tubers. Little information however is available on seed structure, morphology, development and propagation. The main objectives of this study were to investigate the pattern of seed development, to find satisfactory methods of improving the seed germination and to assess possible mechanisms of seed dormancy of Sandersonia aurantiaca (Hook.). Seed development was investigated by fixing plant material in FAA solution, embedding in paraffin, and staining with safranin-fast green. A series of sections were examined and photographed under a microscope. Both embryo and endosperm development in Sandersonia show close similarity to development in Allium fistulosum (Alliaceae). Embryo development passes through early globular, late globular, elongated spheroidal and linear embryo development stages. Endosperm development conforms to the Nuclear type. Freely-growing walls between the endosperm nuclei may be associated with the embryo sac wall as projections. The structure of the mature seeds is very similar to that of Iris (Iridaceae) seeds. The small, linear embryo is embedded in the endosperm which constitutes most of the seed volume. Such small, linear embryos may be one reason for embryo dormancy in Sandersonia seed. A special structure (a conical or cylindrical protuberance) is observed in the inner part of the seed coat, which may combine with a lignified layer (and perhaps including the endosperm) to contribute to the coat-imposed domancy in this species. Eighty five treatments were firstly used to improve the germination percentage of Sandersonia seed. Only the treatment in which seeds scarified firstly with sandpaper for 1 min and then nicked near the radicle end showed increased germination from 0 to 10.6% by 30 days, at 20°C. Based on this result, 31 new treatment methods were designed in germination experiment 2. Water uptake patterns, allelopathic effect on lettuce seeds and embryo rescue of Sandersonia seed were also studied for assessing the possible mechanisms of dormancy. The findings of the present study suggest that the Sandersonia seeds have double dormancy. The dormancy mechanism is located in both the seed coat and the embryo and it consists of at least two steps that must be activated in sequence before germination can occur. The first step can be activated prematurely by scarifying and nicking the seeds, thus allowing the seed coat to become permeable to water, oxygen or to reduced mechanical restriction. The second step can be activated directly GA3 which stimulates embryo growth. This germination-promoting technique has great potential for Sandersonia for improvement of the germination percentage of seeds from 0 to about 70%, but development on a commercial scale needs further studies

Thick Domain Walls in AdS Black Hole Spacetimes

Equations of motion for a real self-gravitating scalar field in the background of a black hole with negative cosmological constant were solved numerically. We obtain a sequence of static axisymmetric solutions representing thick domain wall cosmological black hole systems, depending on the mass of black hole, cosmological parameter and the parameter binding black hole mass with the width of the domain wall. For the case of extremal cosmological black hole the expulsion of scalar field from the black hole strongly depends on it.Comment: 20 pages, 19 figures, accepted for publication in Phys. Rev.

Automated Discrimination of Pathological Regions in Tissue Images: Unsupervised Clustering vs Supervised SVM Classification

Recognizing and isolating cancerous cells from non pathological tissue areas (e.g. connective stroma) is crucial for fast and objective immunohistochemical analysis of tissue images. This operation allows the further application of fully-automated techniques for quantitative evaluation of protein activity, since it avoids the necessity of a preventive manual selection of the representative pathological areas in the image, as well as of taking pictures only in the pure-cancerous portions of the tissue. In this paper we present a fully-automated method based on unsupervised clustering that performs tissue segmentations highly comparable with those provided by a skilled operator, achieving on average an accuracy of 90%. Experimental results on a heterogeneous dataset of immunohistochemical lung cancer tissue images demonstrate that our proposed unsupervised approach overcomes the accuracy of a theoretically superior supervised method such as Support Vector Machine (SVM) by 8%

Preliminary evaluation of a thin organic film coating Final report

High temperature and humidity resistance of thin siloxane films on metal substrate

Magnetic properties of GaMnAs single layers and GaInMnAs superlattices investigated at low temperature and high magnetic field

Magnetotransport properties of GaMnAs single layers and InGaMnAs/InGaAs superlattice structures were investigated at temperatures from 4 K to 300 K and magnetic fields up to 23 T to study the influence of carriers confinement through different structures. Both single layers and superlattice structures show paramagnetic-to-ferromagnetic phase transition. In GaMnAs/InGaAs superlattice beside the Curie temperature (Tc ~ 40 K), a new phase transition is observed close to 13 K.Comment: 8 pages, 5 figures, Proceedings of the XXXII International School on the Physics of Semiconducting Compounds, Jaszowiec 2003, Polan

Exploiting the accumulated evidence for gene selection in microarray gene expression data

Machine Learning methods have of late made signicant efforts to solving multidisciplinary problems in the field of cancer classification using microarray gene expression data. Feature subset selection methods can play an important role in the modeling process, since these tasks are characterized by a large number of features and a few observations, making the modeling a non-trivial undertaking. In this particular scenario, it is extremely important to select genes by taking into account the possible interactions with other gene subsets. This paper shows that, by accumulating the evidence in favour (or against) each gene along the search process, the obtained gene subsets may constitute better solutions, either in terms of predictive accuracy or gene size, or in both. The proposed technique is extremely simple and applicable at a negligible overhead in cost.Postprint (published version

Spatial and temporal changes in the distribution of proteoglycans during avian neural crest development

In this study, we describe the distribution of various classes of proteoglycans and their potential matrix ligand, hyaluronan, during neural crest development in the trunk region of the chicken embryo. Different types of chondroitin and keratan sulfate proteoglycans were recognized using a panel of monoclonal antibodies produced against specific epitopes on their glycosaminoglycan chains. A heparan sulfate proteoglycan was identified by an antibody against its core protein. The distribution of hyaluronan was mapped using a biotinylated fragment that corresponds to the hyaluronan-binding region of cartilage proteoglycans. Four major patterns of proteoglycan immunoreactivity were observed. (1) Chondroitin-6-sulfate-rich proteoglycans and certain keratin sulfate proteoglycans were absent from regions containing migrating neural crest cells, but were present in interstitial matrices and basement membranes along prospective migratory pathways such as the ventral portion of the sclerotome. Although initially distributed uniformly along the rostrocaudal extent of the sclerotome, these proteoglycans became rearranged to the caudal portion of the sclerotome with progressive migration of neural crest cells through the rostral sclerotome and their aggregation into peripheral ganglia. (2) A subset of chondroitin/keratan sulfate proteoglycans bearing primarily unsulfated chondroitin chains was observed exclusively in regions where neural crest cells were absent or delayed from entering, such as the perinotochordal and subepidermal spaces. (3) A subset of chondroitin/keratan sulfate proteoglycans was restricted to the perinotochordal region and, following gangliogenesis, was arranged in a metameric pattern corresponding to the sites where presumptive vertebral arches form. (4) Certain keratan sulfate proteoglycans and a heparan sulfate proteoglycan were observed in basement membranes and in an interstitial matrix uniformly distributed along the rostrocaudal extent of the sclerotome. After gangliogenesis, the neural crest-derived dorsal root and sympathetic ganglia contained both these proteoglycan types, but were essentially free of other chondroitin/keratan-proteoglycan subsets. Hyaluronan generally colocalized with the first set of proteoglycans, but also was concentrated around migrating neural crest cells and was reduced in neural crest-derived ganglia. These observations demonstrate that proteoglycans have diverse and dynamic distributions during times of neural crest development and chondrogenesis of the presumptive vertebrae. In general, chondroitin/keratan sulfate proteoglycans are abundant in regions where neural crest cells are absent, and their segmental distribution inversely correlates with that of neural crest-derived ganglia