Identification of an S-locus glycoprotein allele introgressed from B. napus ssp. rapifera to B. napus ssp. oleifera.

We have previously described a developmentally regulated mRNA in maize that accumulates in mature embryos and is involved in a variety of stress responses in the plant. The sequence of the encoded 16 kDa protein (MA16) predicts that it is an RNA-binding protein, since it possesses a ribonucleoprotein consensus sequence-type RNA-binding domain (CS-RBD). To assess the predicted RNA binding property of the protein and as a starting point to characterize its function we have used ribohomopolymer-binding assays. Here we show that the MA16-encoded protein binds preferentially to uridine- and guanosine-rich RNAs. In light of these results a likely role for this protein in RNA metabolism during late embryogenesis and in the stress response is discussed.     

Purification, cloning, and RXR identity of the HeLa cell factor with which RAR or TR heterodimerizes to bind target sequences efficiently.

We have purified and cloned a HeLa cell nuclear protein that strongly stimulates binding of retinoic acid and thyroid hormone receptors (RARs and TRs) to response elements. The purified protein is a human retinoid X receptor beta (hRXR beta). Three murine members of the RXR family (mRXR alpha, beta, and gamma) have also been cloned, and their interactions with RARs and TRs have been investigated. Under conditions where RAR, RXR, and TR bound poorly as homodimers to various response elements, strongly cooperative RAR-RXR and TR-RXR binding was observed. The binding efficiency was dependent on the sequence, relative orientation, and spacing of the repeated motifs of response elements. We show also that unstable RAR-RXR heterodimers were formed in solution, and that C-terminal sequences and the DNA-binding domains of both receptors were required for efficient formation of stable heterodimers on response elements. These findings suggest a convergence of the signaling pathways of some members of the nuclear receptor superfamily.     

Substance P-immunoreactive neurons in the brainstem of the cat related to cardiovascular centers

Summary The distribution of substance P-immunoreactivity (SP-IR) in the brainstem and spinal cord of normal and colchicine-pretreated cats was analysed using the peroxidase-antiperoxidase (PAP) technique. Numerous SP-IR fibers are present in the nucleus solitarius, nucleus dorsalis nervi vagi and nucleus spinalis nervi trigemini, various parts of the formatio reticularis, substantia grisea centralis mesencephali, locus coeruleus and nucleus parabrachialis. SP-IR perikarya occur in the substantiae gelatinosa and intermedia of the spinal cord, the nucleus spinalis nervi trigemini-pars caudalis, the nucleus dorsalis nervi vagi, and the nucleus solitarius, as well as in the adjacent formatio reticularis and the medullary nuclei of the raphe. In addition, SP-IR cell bodies are located in the nuclei raphe magnus and incertus, ventral and dorsal to the nucleus tegmentalis dorsalis (Gudden), nucleus raphe dorsalis, substantia grisea centralis mensencephali, locus coeruleus, nucleus parabrachialis and colliculus superior.The results indicate that SP-IR neurons may be involved in the regulation of cardiovascular functions both at the central and peripheral level. A peripheral afferent portion seems to terminate in the nucleus solitarius and an efferent part is postulated to originate from the nucleus dorsalis nervi vagi and from the area of the nuclei retroambiguus, ambiguus and retrofacialis.     

Employment Situation of Parents of Long-Term Childhood Cancer Survivors

Background

Taking care of children diagnosed with cancer affects parents’ professional life. The impact in the long-term however, is not clear. We aimed to compare the employment situation of parents of long-term childhood cancer survivors with control parents of the general population, and to identify clinical and socio-demographic factors associated with parental employment.

Methods

As part of the Swiss Childhood Cancer Survivor Study, we sent a questionnaire to parents of survivors aged 5–15 years, who survived ≥5 years after diagnosis. Information on control parents of the general population came from the Swiss Health Survey (restricted to men and women with ≥1 child aged 5–15 years). Employment was categorized as not employed, part-time, and full-time employed. We used generalized ordered logistic regression to determine associations with clinical and socio-demographic factors. Clinical data was available from the Swiss Childhood Cancer Registry.

Results

We included 394 parent-couples of survivors and 3’341 control parents (1’731 mothers; 1’610 fathers). Mothers of survivors were more often not employed (29% versus 22%; p_trend = 0.007). However, no differences between mothers were found in multivariable analysis. Fathers of survivors were more often employed full-time (93% versus 87%; p_trend = 0.002), which remained significant in multivariable analysis. Among parents of survivors, mothers with tertiary education (OR = 2.40, CI:1.14–5.07) were more likely to be employed. Having a migration background (OR = 3.63, CI: 1.71–7.71) increased the likelihood of being full-time employed in mothers of survivors. Less likely to be employed were mothers of survivors diagnosed with lymphoma (OR = 0.31, CI:0.13–0.73) and >2 children (OR = 0.48, CI:0.30–0.75); and fathers of survivors who had had a relapse (OR = 0.13, CI:0.04–0.36).

Conclusion

Employment situation of parents of long-term survivors reflected the more traditional parenting roles. Specific support for parents with low education, additional children, and whose child had a more severe cancer disease could improve their long-term employment situation.     

Inhibition of a nutrient-dependent pinocytosis in dictyostelium discoideum by the amino acid analogue hadacidin

In the present study we examine the effects of the drug hadacidin (N-formyl-N- hydroxyglycine) on pinocytosis in the eukaryotic microorganism dictyostelium discoideum. At concentrations of up to approximately 8 mg/ml, hadacidin inhibited the rate of pinocytosis of fluorescein isothiocyanate (FITC) dextran in cells in growth medium in a concentration-dependent manner but had no effect on cells in starvation medium. Because hadacidin also inhibits cellular proliferation at this concentration, the relationship between growth rate and pinocytosis was studied further using another drug, cerulenin, to produce growth-arrest. These experiments showed no changes in the rate pinocytosis even after complete cessation of cellular proliferation. Other studies showed that the transfer of cells from growth to starvation medium reduced the rate of pinocytosis by approximately 50 percent. A reduction of similar magnitude occurred if cells were transferred from growth to starvation medium containing hadacidin. Also, no additional reduction in pinocytosis occurred when cells that had been treated with hadacidin were transferred to starvation medium containing hadacidin. These cells were able to take up [(14)C]hadacidin in the starvation medium. In contrast to the results with hadacidin-treated cells, cells in a cerulenin-induced state of growth-arrest when transferred to starvation medium exhibited the same 50 percent reduction in pinocytosis observed in cells not previously exposed to either drug. Cells treated with azide, in either growth or starvation medium, exhibited an immediate inhibition of all pinocytotic activity. After the transfer of log-phase cells to starvation medium supplemented with glucose, the reduction in rate was only approximately 10-15 percent. In contrast, a 50 percent reduction was observed after supplementation of starvation medium with sucrose, KCl, or concanavalin A. Maintaining the cells in growth medium containing hadacidin for as long as 16 h had no effect on the rate at which cells aggregated. These results are consistent with the conclusion that D. discoideum exhibits two types of pinocytotic activity: one that is nutrient dependent and the other independent of nutrients. This latter activity persists in starvation medium and is unaffected by hadacidin, whereas the nutrient-dependent activity is present in growth medium and is inhibited by hadacidin.     

Nuclear membrane fusion in electrofused mammalian cells

Fusion of nuclei was studied in electrofused cells using staining procedures and DNA flow cytometry. Homogeneous and heterogeneous electrofusion of Ehrlich ascites tumor cells. Muntjac cells and V79-S181 cells were performed in balanced-salt solutions at low temperature. Incubation of the cells subjected to electrofusion in fusion media for about 2 h was required to complete cell fusion and, in particular, nuclear membrane fusion. Under optimum electrofusion conditions it was found that fusion of nuclei is a very frequent event. Half of the fused cells (about 30 to 50% of the field-exposed cells) underwent nuclear membrane fusion. It is shown that the high frequency of nuclear membrane fusion in electrofused, unsynchronised cells resulted from intracellular dielectrophoresis occurring during cell alignment. In accordance with theory, maximum nuclear membrane fusion was observed using alignment fields of between 1 and 4 MHz (depending on the cell species), that is above the frequencies at which the plasmalemma capacity no longer shielded the cell interior from participation in the conduction process. In this frequency range a potential difference can be built up across the nuclear membrane leading to repositioning of the nuclei into the contact zone of the plasmalemmas of two attached cells. This intracellular dielectrophoresis apparently facilitated fusion of nuclei once intermingling of the plasma membranes had occurred. It was further demonstrated that exponentially growing cells showed higher cell fusion rates than cells taken from the unfed plateau phase. One, but not the only reason, might be the higher ATP content of exponentially growing cells compared to cells of the plateau phase. Addition of external ATP to plateau phase cells during electrofusion resulted, in accordance with this assumption, in an increase of fusion frequency, whereas ATP had apparently no effect on the fusion yield of exponentially growing cells. G1 cells obtained by mitotic selection after nocodazole-induced blockage in metaphase also showed higher cellular and nuclear membrane fusion yields than exponentially growing cells. Most importantly, it could be demonstrated both experimentally and theoretically that electrofusion of cells in a dielectrophoretically aligned chain is controlled by a simple law of probability resulting predominantly in fusion of two cells independent of the number of cells in the chain. The likelihood of fusion of various numbers of cells in a chain is given by the appropriate power of the probability of two-cell fusion.(ABSTRACT TRUNCATED AT 400 WORDS)