Transcriptional profiles underlying parent-of-origin effects in seeds of Arabidopsis thaliana.

Background: Crossing plants of the same species but different ploidies can have dramatic effects on seed growth, but little is known about the alterations to transcriptional programmes responsible for this. Parental genomic imbalance particularly affects proliferation of the endosperm, with an increased ratio of paternally to maternally contributed genomes ('paternal excess') associated with overproliferation, while maternal excess inhibits endosperm growth. One interpretation is that interploidy crosses disrupt the balance in the seed of active copies of parentally imprinted genes.

The maternally expressed WRKY transcription factor TTG2 controls lethality in interploidy crosses of Arabidopsis.

The molecular mechanisms underlying lethality of F1 hybrids between diverged parents are one target of speciation research. Crosses between diploid and tetraploid individuals of the same genotype can result in F1 lethality, and this dosage-sensitive incompatibility plays a role in polyploid speciation. We have identified variation in F1 lethality in interploidy crosses of Arabidopsis thaliana and determined the genetic architecture of the maternally expressed variation via QTL mapping.

MATERNALLY EXPRESSED PAB C-TERMINAL, a novel imprinted gene in Arabidopsis, encodes the conserved C-terminal domain of polyadenylate binding proteins.

Parental imprinting is important for seed development, but few imprinted genes have been identified in plants. The four known imprinted genes in Arabidopsis thaliana encode transcriptional regulators. Here, we describe a novel imprinted gene, MATERNALLY EXPRESSED PAB C-TERMINAL (MPC), which encodes the C-terminal domain of poly(A) binding proteins (PABPs).

Yield assessment of integument-led seed growth following targeted repair of auxin response factor 2.

It is becoming increasingly vital to improve the yield of seed crops to feed an expanding population and, more recently, for biofuel production. One strategy to increase the yield is to increase the seed size, provided that there is not a concomitant decrease in seed number. In a previous study, we described a mutant in the auxin response factor 2 (ARF2) gene which produced extra cells in the seed coat and, subsequently, enlarged seeds.

Double fertilization in Arabidopsis thaliana involves a polyspermy block on the egg but not the central cell.

In animal reproduction, thousands of sperm may compete to fertilize a single egg, but polyspermy blocks prevent multiple fertilization that would otherwise lead to death of the embryo. In flowering plants, successful seed development requires that only two sperm are delivered to the embryo sac, where each must fertilize a female gamete (egg or central cell) to produce the embryo and endosperm. Therefore, polyspermy must be avoided, not only to prevent abnormalities in offspring, but to ensure double fertilization.

[Nipple areola complex conservation in immediate breast reconstruction: prospective study of 66 cases].

Objective Of The Study: Our objective is to define a sub-group of patients in whom skin-sparing mastectomy with immediate reconstruction and preservation of the nipple-areola complex is technically and oncologically feasible without increasing the risk of complications and local recurrence.

Patients And Methods: Between September 1999 and December 2005, 66 patients presenting an in situ and/or invasive breast carcinoma justifying a mastectomy underwent immediate breast reconstruction preserving the skin and nipple-areolar complex.

Results: After a median follow-up of 37 months, definitive conservation of the nipple-areolar complex with good esthetic results was achieved in 71% of the cases.

Proliferative phase endosperm promoters from Arabidopsis thaliana.

Endosperm accounts for a large proportion of human nutrition and is also a major determinant of seed viability and size, not only in cereals, but also in species with ephemeral endosperms, such as soybean and oilseed rape. The extent of endosperm proliferation early in seed development is a crucial component in setting seed size; therefore, a biotechnological approach for the modification of this trait requires promoters active in early endosperm. To find such promoters, we constructed an array based on cDNAs extracted from developing Arabidopsis seeds enriched for proliferating endosperm.

Deeper into the maize: new insights into genomic imprinting in plants.

Current models for regulation of parent-specific gene expression in plants have been based on a small number of imprinted genes in Arabidopsis. These present repression as the default state, with expression requiring targeted activation. In general, repression is associated with maintenance methylation of cytosines, while no role has been found in Arabidopsis imprinting for de novo methylation--unlike the case in mammals.

Specimen radiography as predictor of resection margin status in non-palpable breast lesions.

Aim: This study aimed to evaluate the role of specimen radiography in predicting margin status for non-palpable breast malignancies.

Methods: We retrospectively reviewed the clinical and pathological data together with specimen radiographs of 164 women with ductal carcinoma in situ, who were referred to our centre between January 1997 and December 2000. In all cases microcalcifications were discovered on mammography.

Genomic imprinting in plants and mammals: how life history constrains convergence.

In both flowering plants and mammals, DNA methylation is involved in silencing alleles of imprinted genes, but surprising differences in imprinting control are emerging between the two taxa which may be traced to differences in their life cycles. Imprinted gene expression in plants occurs in the endosperm, a separate fertilisation product which transmits nutrients to the embryo and does not contribute a genome to the next generation. Regulation of expression of the known imprinted genes in Arabidopsis involves a cascade of gene expression beginning in the gametophyte, a haploid life phase interposed between the meiotic products and the gametes, which evolved from free-living organisms that constitute the dominant life phase of lower plants.

The AUXIN RESPONSE FACTOR 2 gene of Arabidopsis links auxin signalling, cell division, and the size of seeds and other organs.

Control of seed size involves complex interactions among the zygotic embryo and endosperm, the maternally derived seed coat, and the parent plant. Here we describe a mutant in Arabidopsis, megaintegumenta (mnt), in which seed size and weight are dramatically increased. One factor in this is extra cell division in the integuments surrounding mnt mutant ovules, leading to the formation of enlarged seed coats.

Epigenetics: imprinting in plants and mammals--the same but different?

Plants and animals both exhibit parental imprinting, but do they control it the same way? Recent studies show that in Arabidopsis, as in mammals, imprinted alleles are subject to DNA methylation--but, surprisingly, the default state is silence rather than activity.

Acceptability and technical problems of the female condom amongst commercial sex workers in a rural district of Malawi.

A study was conducted among commercial sex workers (CSWs) in rural southern Malawi, in order to (a) assess the acceptability of the female condom and (b) identify common technical problems and discomforts associated with its use. There were 88 CSWs who were entered into the study with a total of 272 female condom utilizations. Eighty-six (98%) were satisfied with the female condom, 80% preferred it to the male condom and 92% were ready to use the device routinely.

Genomic imprinting and endosperm development in flowering plants.

Genomic imprinting, the parent-of-origin-specific expression of genes, plays an important role in the seed development of flowering plants. As different sets of genes are imprinted and hence silenced in maternal and paternal gametophyte genomes, the contributions of the parental genomes to the offspring are not equal. Imbalance between paternally and maternally imprinted genes, for instance as a result of interploidy crosses, or in seeds in which imprinting has been manipulated, results in aberrant seed development.

Genomic imprinting in plants.

Genomic imprinting, though most extensively studied in mammals, has long been known to perform an important role in seed development in flowering plants. In this chapter, an overview of what is known to date about genomic imprinting in flowering plants and how this knowledge came into being will be given.

Genetic mechanisms of apomixis.

The introduction of apomixis to crops would allow desirable genotypes to be propagated while preventing undesirable gene flow, but so far there has been little success in transferring this trait from a natural apomict to another species. One explanation is the sensitivity of endosperm to changes in relative maternal and paternal contribution owing to parental imprinting, an epigenetic system of transcriptional regulation by which some genes are expressed from only the maternally or paternally contributed allele. In sexual species, endosperm typically requires a ratio of two maternal genomes to one paternal genome for normal development, but this ratio is often altered in apomicts, suggesting that the imprinting system is altered as well.

The basis of natural and artificial postzygotic hybridization barriers in Arabidopsis species.

The success or failure of interspecific crosses is vital to evolution and to agriculture, but much remains to be learned about the nature of hybridization barriers. Several mechanisms have been proposed to explain postzygotic barriers, including negative interactions between diverged sequences, global genome rearrangements, and widespread epigenetic reprogramming. Another explanation is imbalance of paternally and maternally imprinted genes in the endosperm.

TETRASPORE encodes a kinesin required for male meiotic cytokinesis in Arabidopsis.

A key step in pollen formation is the segregation of the products of male meiosis into a tetrad of microspores, each of which develops into a pollen grain. Separation of microspores does not occur in tetraspore (tes) mutants of Arabidopsis thaliana, owing to the failure of male meiotic cytokinesis. tes mutants thus generate large 'tetraspores' containing all the products of a single meiosis.

The epigenetic basis of gender in flowering plants and mammals.

What makes a sperm male or an egg female, and how can we tell? A gamete's gender could be defined in many ways, such as the sex of the individual or organ that produced it, its cellular morphology, or its behaviour at fertilization. In flowering plants and mammals, however, there is an extra dimension to the gender of a gamete--due to parental imprinting, some of the genes it contributes to the next generation will have different expression patterns depending on whether they were maternally or paternally transmitted. The non-equivalence of gamete genomes, along with natural and experimental modification of imprinting, reveal a level of sexual identity that we describe as 'epigender'.

Hypomethylation promotes autonomous endosperm development and rescues postfertilization lethality in fie mutants.

In most flowering plants, fertilization is necessary for development of the central cell into endosperm, but in the fie-1 mutant of Arabidopsis, the central cell can proliferate autonomously. However, autonomous fie-1 endosperms do not develop completely: They have fewer nuclei than sexually produced endosperms, cellularization does not take place, and no clear distinction is seen between the different endosperm compartments. Here, we show that autonomous endosperm develop much further in hypomethylated than normally methylated fie-1 mutants, undergoing cellularization and regional specification to resemble endosperm in sexually produced wild-type seeds.

Parent-of-origin effects on seed development in Arabidopsis thaliana require DNA methylation.

Some genes in mammals and flowering plants are subject to parental imprinting, a process by which differential epigenetic marks are imposed on male and female gametes so that one set of alleles is silenced on chromosomes contributed by the mother while another is silenced on paternal chromosomes. Therefore, each genome contributes a different set of active alleles to the offspring, which develop abnormally if the parental genome balance is disturbed. In Arabidopsis, seeds inheriting extra maternal genomes show distinctive phenotypes such as low weight and inhibition of mitosis in the endosperm, while extra paternal genomes result in reciprocal phenotypes such as high weight and endosperm overproliferation.

Efficacy and safety of docetaxel (Taxotere) in heavily pretreated advanced breast cancer patients: the French compassionate use programme experience.

The aim of this investigation was to assess retrospectively docetaxel safety and efficacy in advanced breast cancer patients in a French compassionate use programme. Patients had received > 1 prior chemotherapy regimen for advanced disease, were either anthracycline-resistant (that is progressed within 6 months after anthracycline-based chemotherapy) or had received the maximum cumulative dose. The recommended docetaxel dose was 100 mg/m2/cycle (75 mg/m2 in case of liver function impairment: transaminases > 1.

Factors predicting for efficacy and safety of docetaxel in a compassionate-use cohort of 825 heavily pretreated advanced breast cancer patients.

Purpose: To identify predictive factors for efficacy and safety in advanced breast cancer (ABC) patients treated in the French compassionate-use docetaxel program.

Patients And Methods: A total of 825 ABC patients treated with docetaxel (100 mg/m(2) every 3 weeks) were source-reviewed and analyzed for prognostic factors associated with overall response rate (ORR), time to treatment failure (TTF), overall survival (OS), febrile neutropenia, mucositis, and severe fluid retention syndrome by univariate and multivariate analysis.

Results: The ORR was 22.