Dynamics of maternal and paternal effects on embryo and seed development in wild radish (Raphanus sativus).

BACKGROUND AND AIMS: Variability in embryo development can influence the rate of seed maturation and seed size, which may have an impact on offspring fitness. While it is expected that embryo development will be under maternal control, more controversial hypotheses suggest that the pollen donor and the embryo itself may influence development. These latter possibilities are, however, poorly studied. Characteristics of 10-d-old embryos and seeds of wild radish (Raphanus sativus) were examined to address: (a) the effects of maternal plant and pollen donor on development; (b) the effects of earlier reproductive events (pollen tube growth and fertilization) on embryos and seeds, and the influence of embryo size on mature seed mass; (c) the effect of water stress on embryos and seeds; (d) the effect of stress on correlations of embryo and seed characteristics with earlier and later reproductive events and stages; and (e) changes in maternal and paternal effects on embryo and seed characteristics during development. METHODS: Eight maternal plants (two each from four families) and four pollen donors were crossed and developing gynoecia were collected at 10 d post-pollination. Half of the maternal plants experienced water stress. Characteristics of embryos and seeds were summarized and also compared with earlier and later developmental stages. KEY RESULTS: In addition to the expected effects of the maternal plants, all embryo characters differed among pollen donors. Paternal effects varied over time, suggesting that there are windows of opportunity for pollen donors to influence embryo development. Water-stress treatment altered embryo characteristics; embryos were smaller and less developed. In addition, correlations of embryo characteristics with earlier and later stages changed dramatically with water stress. CONCLUSIONS: The expected maternal effects on embryo development were observed, but there was also evidence for an early paternal role. The relative effects of these controls may change over time. Thus, there may be times in development when selection on the maternal, paternal or embryo contributions to development are more and less likely.

[Cockayne syndrome in two brothers]. / Síndrome de Cockayne em dois irmãos.

We report the clinical history of two brothers with the classical Cockayne syndrome. The main manifestations consisted of cachectic dwarfism, mental retardation, intracranial calcifications, microcephaly, enophthalmos, senile appearance, joint hypomotility and skin photosensitivity. In one of these children, who died at 10 years of age of bronchopneumonia, necropsy studies revealed a variety of anomalies, mainly encephalic,which included an arachnoidal cyst at the base of the cerebellum, a defect apparently previously undescribed inpatients with this syndrome.

Stereophotogrammetric evaluation of the dental interproximal contacting area with amalgam restorations. Use of matrices and matrix holders. Part II. Mandibular first molar.

The authors, as a sequence of a previous research, dealt with a morphological study, by means of level curves, of the lower first molar (mesial surface). This study based on dental amalgam reconstructions used two different types of interproximal cavity preparations; one type was related to the modern or conservative preparation and the other was related to the conventional cavity preparation. Two types of matrix holders were utilized as well as copper rings. In this project the contacting interproximal areas and adjacent structures were observed stereophotogrammetrically. As in the previous study, the models used were obtained from patients with good occlusal anatomical functional conditions and mounted in a semiadjustable articulator. The procedures for restorations followed the prescribed technique for these cases as far as the selection of the material, placement of the matrices, condensation pressure, etc, were concerned. The reconstruction of the serial slices, through level curves, were able to show the location of the contacting area for each matrix used, although it is necessary to stress that the original tooth contour has never been restored.

Characterization of the subunits of beta-conglycinin.

Four subunits of beta-conglycinin were purified from soybean cultivar CX 635-1-1-1, and were designated alpha, alpha', beta, and beta' in accordance with nomenclature proposed by Thanh and Shibasaki [(1977) Biochim. Biophys. Acta 490, 370-384]. Of these subunits, beta' has not previously been reported or characterized. Consistent with the low levels of methionine in these proteins, cyanogen bromide cleavage of alpha', alpha, and beta' subunits produced only a few fragments. The beta subunit contains no methionine and was not cleaved by cyanogen bromide. The NH2-terminal amino acid sequences of the alpha and alpha' subunits are homologous, and each has valine at its amino terminus. The beta subunit has a very different NH2-terminal sequence from those of the alpha and alpha' subunits, and has leucine at its amino terminus. The NH2-terminal sequence of the beta' subunit could not be determined, as it appeared to be blocked to Edman degradation. Although alpha and alpha' subunits have similar NH2-terminal sequences, they differ in the number of methionine residues and so yielded different numbers of cyanogen bromide fragments. Two cyanogen bromide fragments (CB-1 and CB-2) were purified from the alpha subunit. CB-1 originated from the NH2-terminal end of the subunit. The amino acid sequence of CB-2 was identical to that predicted from the nucleotide sequence of cDNA clone pB36. The insert in pB36 encoded 216 amino acids from the COOH-terminal end of the alpha subunit and contained a 138-bp trailer sequence which was followed by a poly-(A) tail. Maps showing the relative positions of methionine residues and carbohydrate moieties in the alpha and alpha' subunits were drawn, based on primary sequence data, and the size and carbohydrate content of the CNBr fragments derived from the subunits.