Germination characteristics of Rhinanthus minor influence field emergence, competitiveness and potential use in restoration projects

The facultative root hemi-parasite Rhinanthus minor is often used in grassland habitat restoration projects to regulate ecosystem structure and function. Its impact on community productivity and diversity as a function of resource supply, sward composition and management has been widely investigated. However, there is a lack of information about the possible influence of seed quality on the efficacy of the hemi-parasite. Ten seed lots from commercial sources were sown in the field and their germination characteristics investigated in the laboratory. Seeds from four lots were also germinated and sown in pots alongside plants of two host species, Lotus corniculatus and Holcus lanatus. Plant establishment, height and flowering density were evaluated for the hemi-parasite, while plant biomass was measured for both R. minor and its host. Two aspects of seed quality influenced the field emergence of seed lots of R. minor, the radicle emergence (%) and the length of the lag period from the beginning of imbibition to germination (mean germination time), which indicates seed vigour. A longer lag period (lower vigour) was associated with higher levels of seedling mortality and lower plant vigour, in terms of plant height and biomass accumulation and was also reflected in the parasitic impact of the seed lots. Seed quality, specifically germination and vigour, can influence the establishment, survival, subsequent plant productivity and parasitic impact of R. minor in vegetation restoration projects. Seed quality is discussed as a key factor to consider when predicting the impact of the hemi-parasite on community productivity and diversity.

Responses of Primula vulgaris to light quality in the maternal and germination environments

In the model species Arabidopsis thaliana phytochromes mediate dormancy and germination responses to seasonal cues experienced during seed maturation on the maternal plants. However, the effect of the maternal light environment on seed germination in native wild species has not been well studied. This is particularly important given its practical application in the context of environmental restoration, when there can be marked changes in the canopy. Plants of Primula vulgaris were grown in the field over two vegetative seasons under four shading treatments from low to high ratio of red to far-red light (R:FR). Leaf and seed traits were assessed in response to the light treatments. The germination of seeds from these four maternal environments (pre-dispersal) was investigated at seven light and five temperature treatments (post-dispersal). Thinner leaves, larger leaf area and greater chlorophyll content were found in plants growing in reduced R:FR. Shading in the maternal environment led to increased seed size and yield, although the conditions experienced by the maternal plants had no effect on seed germination. Seeds responded strongly to the cues experienced in their immediate germination environment. Germination was always enhanced under higher R:FR conditions. The observed phenotypic trait variation plays a major role in the ability of P. vulgaris to grow in a wide range of light conditions. However, the increased germination capacity in response to a higher R:FR for all maternal environments suggests potential for seedling establishment under vegetative shade only in the presence of canopy gaps.

Abstract P3-03-03: DNA Mutation as a Biomarker for Tracking Circulating Tumor Cells and Disseminated Tumor Cells in Breast Cancer Metastases

Introduction: Most cancer deaths are caused by metastatic disease. Tumor cells exit the primary tumor and travel through blood and/or lymphatic channels to distant sites. Circulating tumor cells (CTCs) from blood and disseminated tumor cells (DTCs) from bone marrow may play key roles in the metastatic process. Primary tumor heterogeneity and how the metastatic process evolves over time may confound the study of metastatic biology. To better distinguish the cells of origin in metastases, we developed new methodologies to isolate single tumor cells from tissues, blood, and bone marrow for DNA and RNA analyses. We compared these analyses in individual cells from primary and metastatic tumors, CTCs and DTCs. Materials and Methods: Single tumor cell suspensions from primary and metastatic tissues were prepared from fresh human specimens or mouse xenografts. Single cells were isolated from blood, bone marrow, or single tumor cell suspensions from tissue using EpCAM-conjugated microbeads and the MagSweeper, a device invented by our group. Unbounded microbeads were removed and the single cells were placed into individual PCR tubes for further nucleic acid analyses. Live CTCs and DTCs from some breast cancer patients were cultured for further testing. Single cell DNA mutational analyses were performed by multiplex PCR sequencing. Single cell transcriptional profiling was performed by multiplex qRT-PCR. Single tumor cells with mutations were compared among multiple compartments: primary tumor, metastatic tumor, blood and bone marrow. Array CGH analysis was used to focus single cell analysis on genes in potential areas of DNA deletion or amplification. Xenograft mouse models were generated using primary or tumor tissues and single cells were compared.

Results: Single tumor cells from fresh or fixed solid tumor tissues were successfully isolated for nucleic acid analyses. CTCs and DTCs isolated by MagSweeper from breast cancer patients could be isolated live and cultured or injected for growth in xenografts. Single cell DNA mutation analysis of the PIK3CA gene was identified in 3/27 breast cancer patients, showing the mutation in only 45/178 single tumor cells. Sequential PIK3CA mutational analyses of CTCs, DTCs, and metastases showed that DTCs better reflected the mutational status of metastases at time points earlier in the metastatic process.

Discussion: Our results indicate that isolating single tumor cells from tumor tissues, blood, and bone marrow provides detailed information about different tumor compartments in individual cancer patients. Single cell DNA mutational analysis can provide a biomarker for tracking CTCs and DTCs over time during the metastatic process. Based on our initial findings, we postulate that the bone marrow serves as a tumor cell reservoir for early metastatic spread in breast cancer.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-03-03.

Circulating tumour cells demonstrate an altered response to hypoxia and an aggressive phenotype

Background:

Tumours contain hypoxic regions that select for an aggressive cell phenotype; tumour hypoxia induces metastasis-associated genes. Treatment refractory patients with metastatic cancer show increased numbers of circulating tumour cells (CTCs), which are also associated with disease progression. The aim of this study was to examine the as yet unknown relationship between hypoxia and CTCs.

Methods:

We generated human MDA-MB-231 orthotopic xenografts and, using a new technology, isolated viable human CTCs from murine blood. The CTCs and parental MDA-MB-231 cells were incubated at 21 and 0.2% (hypoxia) oxygen, respectively. Colony formation was assayed and levels of hypoxia- and anoxia-inducible factors were measured. Xenografts generated from CTCs and parental cells were compared.

Results:

MDA-MB-231 xenografts used to generate CTCs were hypoxic, expressing hypoxia factors: hypoxia-inducible factor1 alpha (HIF1α) and glucose transporter protein type 1 (GLUT1), and anoxia-induced factors: activating transcription factor 3 and 4 (ATF3 and ATF4). Parental MDA-MB-231 cells induced ATF3 in hypoxia, whereas CTCs expressed it constitutively. Asparagine synthetase (ASNS) expression was also higher in CTCs. Hypoxia induced ATF4 and the HIF1α target gene apelin in CTCs, but not in parental cells. Hypoxia induced lower levels of carbonic anhydrase IX (CAIX), GLUT1 and BCL2/adenovirus E1B 19-KD protein-interacting protein 3 (BNIP3) proteins in CTCs than in parental cells, supporting an altered hypoxia response. In chronic hypoxia, CTCs demonstrated greater colony formation than parental cells. Xenografts generated from CTCs were larger and heavier, and metastasised faster than MDA-MB-231 xenografts.

Conclusion:

CTCs show an altered hypoxia response and an enhanced aggressive phenotype in vitro and in vivo.

Bile acid hydrophobicity is correlated with induction of apoptosis and/or growth arrest in HCT116 cells

Faecal bile acids have long been associated with colon cancer; highly hydrophobic bile acids, which induce apoptosis, have been implicated in the promotion of colon tumours. The moderately hydrophobic chemopreventive agent ursodeoxycholic acid (UDCA) does not induce apoptosis; rather, it causes colon-derived tumour cells to arrest their growth. To investigate the relationship between bile acid hydrophobicity and biological activity we examined 26 bile acids for their capacity to induce apoptosis or alter cell growth. We found that the rapidity with which, and the degree to which, bile acids could induce apoptosis or growth arrest was correlated with their relative hydrophobicities. Of the bile acids tested, only deoxycholic acid (DCA) and chenodeoxycholic acid, the most hydrophobic bile acids tested, could induce apoptosis in less than 12 h in the human colon cancer cell line HCT116. The moderately hydrophobic bile acids hyoDCA, lagoDCA, norDCA, homoUDCA and isoUDCA induced growth arrest at 12 h but longer incubations resulted in apoptosis. Conjugation of glycine or taurine to the bile acids decreased relative hydrophobicity and eliminated biological activity in our assays. In addition, we tested a subset of these bile acids for their ability to translocate across cell membranes. When (14)C-labelled and (3)H-labelled DCA, UDCA and lagoDCA were added to cell cultures, we found only minimal uptake by colon cells, whereas hepatocytes had considerably higher absorption. These experiments suggest that hydrophobicity is an important determinant of the biological activity exhibited by bile acids but that under our conditions these activities are not correlated with cellular uptake.

The influence of aerated hydration seed treatment on seed longevity as assessed by the viability equations

Aerated hydration (AH) treatments of cauliflower seeds for 12 h (12AH) and 28 h (28AH) at 20 degrees C resulted in improved or reduced storage potential of low or high vigour seeds, respectively. Seeds were stored at their initial seed moisture content (mean 5.5% mc) or at 12% mc at 10 degrees C for 12 months and at 20 degrees C for 4 months. The improved longevity of low vigour seeds was associated with increased K(i) (initial seed viability) and a reduced rate of deterioration (1/sigma) whereas the K(i) of high vigour seeds fell after 28AH and the rate of deterioration increased such that the time to lose one probit of viability decreased from 28.7 to 5.3 months at 10 degrees C and from 10.4 to 1.2 months at 20 degrees C. The improved K(i) of low vigour seeds could be explained by the reduction in the extent of deterioration after AH, as indicated by the increase in germination after cotrolled deterioration (CD), and the possible activation of metabolic repair during treatment. In contrast the reduced germination after CD of AH-treated high vigour seeds was indicative of deterioration as a result of treatment. Both high and low vigour seeds contained constitutive levels of ss-tubulin which increased during AH treatment, the increase being greater in high vigour seeds. High vigour seeds also showed an increase in the proportion of nuclear DNA present as 4C DNA, from 3% (untreated seeds) to 26% (28AH), indicative of germination advancement from the G(1) to G(2) phase of the cell cycle during treatment. This higher proportion of 4C DNA is correlated with the increased sensitivity of seeds to drying and/or storage after AH, leading to their reduced K(i) and storage potential. In contrast, there was little change in %4C in low vigour seeds. Priming in polyethylene glycol (PEG, -1.0 MPa) for 5 d or 13 d also improved the longevity of low vigour seeds stored at their initial and 12% mc at 10 degrees C for 8 months, as reflected in their laboratory and CD germination. In this case, however, the improved longevity of the low vigour seeds following 13 d priming was associated with an increase in 4C DNA from 4% (dry control) to 56% after treatment. The germination of both untreated and primed high vigour seeds remained high throughout the storage period. Increases in the rate of germination (decreased mean germination time) observed after all AH and PEG treatments were not consistently associated with an increase in the proportion of nuclei containing 4C DNA.

Different bile acids exhibit distinct biological effects: the tumor promoter deoxycholic acid induces apoptosis and the chemopreventive agent ursodeoxycholic acid inhibits cell proliferation

Epidemiological studies have suggested that the concentration and composition of fecal bile acids are important determining factors in the etiology of colon cancer. However, the mechanism by which these compounds influence tumor development is not understood. To begin to elucidate their mechanism of action, four bile acids, cholic acid, chenodeoxycholic acid, deoxycholic acid (DCA), and ursodeoxycholic acid, were examined for their effects on the growth of several different tumor cell lines. We found that incubating cells with chenodeoxycholic acid or DCA caused morphological changes, seen by electron and light microscopy, that were characteristic of apoptosis, whereas incubating cells with ursodeoxycholic acid inhibited cell proliferation but did not induce apoptosis. Cholic acid had no discernible effect on cells. Notably, the apoptosis induced by DCA could be suppressed by inhibiting protein kinase C activity with calphostin C. These results indicate that different bile acids exhibit distinct biological activities and suggest that the cytotoxicity reported for DCA may be due to its capacity to induce apoptosis via a protein kinase C-dependent signaling pathway.

Bacillus isolates from the spermosphere of peas and dwarf French beans with antifungal activity against Botrytis cinerea and Pythium species

A range of isolation procedures including washing, sonication and incubation in nutrient broth were used separately and in combination to obtain potential bacterial antagonists to Botrytis cinerea and Pythium mamillatum from the testae and cotyledons of peas and dwarf French beans. Heat treatment was also used to bias this selection towards spore-forming bacteria. Ninety-two bacterial isolates were obtained, 72 of which were provisionally characterized as species of Bacillus. Four of these Bacillus isolates (B3, C1, D4 and J7) displayed distinct antagonism in vitro against Botrytis cinerea and P. mamillatum when screened using dual culture analysis. Further characterization of these antagonists using API 50CHB biochemical profiling identified isolate D4 as Bacillus polymyxa and isolates B3, C1 and J7 as strains of B. subtilis. In vitro screening techniques, using cell-free and heat-killed extracts of liquid cultures against Botrytis cinerea, demonstrated the production of antifungal compounds by these four Bacillus antagonists. With each isolate the antifungal activity was found not to be either exclusively spore-bound nor released entirely into the medium but present in both fractions. The antifungal compounds produced by these isolates were shown to be heat-stable. Their identification, production and release require further study for exploitation as biocontrol systems.

Peripheral edema

Distribution of accumulated fluid is the important element in the differentiation of peripheral edema resulting from different etiologies. Isolated upper extremity edema is rare and is usually caused by obstruction of the superior vena cava by a malignancy. The cause of unilateral edema of a lower limb can usually be determined by the history (heart, liver or kidney disease, trauma, malignancy, radiation or surgery), a physical examination (distribution of edema, stigmata of infection, trauma, malignancy or organ failure) and appropriate laboratory and other tests. Determining the etiology of bilateral lower extremity edema requires a similar approach; this condition may be the result of systemic conditions, drug use, lipidema or idiopathic edema, in addition to obstructive causes and chronic venous states. Algorithms, based on the patient's history, physical examination and diagnostic tests, can help guide physicians to the correct diagnosis.