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Plant genomes are earmarked with defined patterns of chromatin marks. Little is known about the stability of these epigenomes when related, but distinct genomes are brought together by intra-species hybridization. Arabidopsis thaliana accessions and their reciprocal hybrids were used as a model system to investigate the dynamics of histone modification patterns. The genome-wide distribution of histone modifications H3K4me2 and H3K27me3 in the inbred parental accessions Col-0, C24 and Cvi and their hybrid offspring was compared by chromatin immunoprecipitation in combination with genome tiling array hybridization. The analysis revealed that, in addition to DNA sequence polymorphisms, chromatin modification variations exist among accessions of A. thaliana. The range of these variations was higher for H3K27me3 (typically a repressive mark) than for H3K4me2 (typically an active mark). H3K4me2 and H3K27me3 were rather stable in response to intra-species hybridization, with mainly additive inheritance in hybrid offspring. In conclusion, intra-species hybridization does not result in gross changes to chromatin modifications.

Studies have shown that microvessel density influences breast-cancer prognosis. Since tumor angiogenesis is considered to be substantially affected by the excretion of vascular endothelial growth factor (VEGF) from tumor cells, we examined whether VEGF concentration is different in malignant and in non-malignant breast tissue. It was also of interest to discover whether intratumoral VEGF concentration influences disease-free survival (DFS) of breast-cancer patients. Analysis is based on 120 tissue specimens taken from breast fibromas (n = 23), normal epithelial breast tissue adjacent to fibromas (n = 8) and invasive breast cancer (n = 89). VEGF concentration was quantified by using an immunoassay. Microvessel density was determined by immunostaining for factor-VIII-related antigen. Median VEGF concentration is given in pg/mg protein (25%-quantile-75%-quantile) and it was 0 (0-1.8) in normal breast tissue, 9.8 (0.52-43.0) in fibromas and 130.4 (50.8-362.2) in invasive carcinomas. A univariate Cox model revealed that node status, tumor size, estrogen-receptor concentration, histological grading and microvessel density were prognostic factors for disease-free survival in breast cancer. We found a significant correlation between VEGF concentration and microvessel count, but VEGF concentration did not significantly influence disease-free survival. Although VEGF protein was found at a significantly higher concentration in malignant than in non-malignant tissue, determination of intratumoral VEGF protein by an enzyme immunoassay was not prognostically relevant in our patient population.

The transcription factor LEAFY COTYLEDON1 (LEC1) controls aspects of early embryogenesis and seed maturation in Arabidopsis thaliana. To identify components of the LEC1 regulon, transgenic plants were derived in which LEC1 expression was inducible by dexamethasone treatment. The cotyledon-like leaves and swollen root tips developed by these plants contained seed-storage compounds and resemble the phenotypes produced by increased auxin levels. In agreement with this, LEC1 was found to mediate up-regulation of the auxin synthesis gene YUCCA10. Auxin accumulated primarily in the elongation zone at the root-hypocotyl junction (collet). This accumulation correlates with hypocotyl growth, which is either inhibited in LEC1-induced embryonic seedlings or stimulated in the LEC1-induced long-hypocotyl phenotype, therefore resembling etiolated seedlings. Chromatin immunoprecipitation analysis revealed a number of phytohormone- and elongation-related genes among the putative LEC1 target genes. LEC1 appears to be an integrator of various regulatory events, involving the transcription factor itself as well as light and hormone signalling, especially during somatic and early zygotic embryogenesis. Furthermore, the data suggest non-embryonic functions for LEC1 during post-germinative etiolation.

It has been proposed that the timing of breast-cancer surgery in relation to menstrual phase has a prognostic impact on outcome. We carefully evaluated a combined 2-center series of 385 pre-menopausal women operated on for stage-I and stage-II breast cancer with a median follow-up of 5 years for a possible impact on outcome of the date of their last menstrual period (LMP) before surgery. The distribution of risk factors of the study cohort as well as prognostic indicators corresponded to previously published results. Nodal status, grading, and (in part) hormone-receptor status differentiate well between patient subgroups with high and low risk of relapse and death after breast-cancer surgery. In neither univariate nor multivariate analysis was any impact of the so-called “unopposed” estrogen secretion detected. We did not observe any effect of LMP on long-term survival in any of several prognostic subgroups, in particular in hormone-receptor-positive patients. From our results and from the literature, we conclude that LMP does not provide any prognostic information for outcome after breast- cancer surgery and therefore the proposed modification of scheduling of breast-cancer operations is not justified. © 1992 Wiley-Liss, Inc.

Aus der Propolis (Bienenwaben-Kittharz) wurden Alkane, Alkene und Alkadiene isoliert. Die Charakterisierung der Verbindungen erfolgte durch GC/MS-Analyse. Die Positionen der Doppelbindungen wurden nach Methoxymercurierung und Deuterierung durch Analyse des Massen-Fragmentierungsmusters und deren Z-Konfiguration durch NMR-Analyse bestimmt. Constituents of the Propolis, I Alkanes, alkenes, and alkadienes have been isolated from the propolis (bee glue). The substances have been identified by GC/MS analysis. The position of the double bond has been determined after methoxymercuration and deuteration by analysis of the mass fragmentation pattern. The Z configuration of the double bonds was determined by NMR.