Mother-infant bonding

A study of the research on postpartum mother-infant bonding shows that results from poorly constructed research programs were published in major journals and became a part of hospital policy because the bonding concept was politically useful in the struggle between advocates of natural childbirth and managers of the medical model of birth. The concept was also uncritically accepted because it was consistent with a longstanding ideology of motherhood that sees women as the prime architects of their children’s personalities. Diane Eyer earned her Ph.D. in developmental psychology from the University of Pennsylvania. She is currently writing a book on the ways in which the concepts of bonding and attachment have affected our understanding of appropriate early childcare.     

Cyclooxygenase and 5-lipoxygenase inhibitory activity of 2,6 di-t-butylphenols linked by a sulfur atom to 1,3,4-thiadiazoles and 1,3,4-oxadiazoles

The preparation of a series of 1,3,4-thiadiazoles and 1,3,4-oxadizoles linked by a thioether to 2,6-di-t-butylphenol and the inhibition of cyclooxygenase (CO) and 5-lipoxygenase (5-LO) by these compounds is dicussed.     

A rapid assay for chloroplast-encoded triazine resistance in higher plants

We have designed a simple and rapid assay for chloroplast-based triazine resistance in higher plants using PCR amplification of thepsbA gene coupled toMaeI digestion of the amplified product to distinguish triazine resistant from sensitive biotypes. Our assay is universal and avoids the need of lengthy procedures of previously published assays, which either required spraying of seedlings in a controlled environment, quantification of chlorophyll fluorescence of leaf discs after incubation in triazine solution, DNA sequencing of thepsbA gene, or Southern-blot analysis. Our diagnostic system is qualitative, reliable, fast and simple. More than 100 seedlings taken directly from the field can be analyzed in one day. This system has a direct application towards a more rational use of herbicides in production fields. It also represents a valuable tool to monitor spreading of resistant biotypes through time and space and can serve as a model system applicable to other gene monitoring needs.     

Aspects of early postnatal development of cortical neurons that proceed independently of normally present extrinsic influences

To examine the contribution of local versus extrinsic influences on postnatal development of cortical neurons, we compared the maturation of deep (infragranular) layer neurons in isolated slices of neocortex grown in organotypic culture to a similar population of neurons developing in vivo. All slice cultures were prepared from sensorimotor cortices of newborn mice (P0) and neurons in these cultures were examined at daily intervals during the first 9 days in vitro (DIV). The maturational state of neurons developing in vivo over this same time period was assessed in acute slices prepared from animals of equivalent postnatal age, P1–P9. Electrophysiological recordings were obtained from neurons in both cultured and acute slices, using Lucifer yellow filled whole-cell recording electrodes, enabling subsequent morphometric analysis of the labeled cells. We report significant changes in both cellular morphology and electrical membrane properties of these deep layer cortical neurons during the frist week in culture. Morphological maturation over this time period was characterized by a two- to three-fold increase in cell body size and total process length, and an increase in dendritic complexity. In this same population of cells a three-fold decrease in input resistance and changes in the action potential waveform, including a two-fold decrease in the AP duration, also occur. The degree of morphological and electrophysiological differentiation of individual neurons was highly correlated across developmental ages, suggesting that the maturational state of a cell is reflected in both cellular morphology and intrinsic membrane properties. A remarkably similar pattern of neuronal maturation was observed in neurons in layers V, VI/SP examined in acute slices prepared from animals between P1–P9. Because our culture system preserves many aspects of the local cortical environment while eliminating normal extrinsic influences (including thalamic, brainstem, and callosal connections), our findings argue that this early phase of neuronal differentiation, including the rate and extent of dendritic growth and development of AP waveform, results from instructive and/or permissive local influences, and appears to proceed independently of the many normally present extrinsic factors. © 1993 John Wiley & Sons, Inc.     

COMPONENTS OF PHENOTYPIC SELECTION: POLLEN EXPORT AND FLOWER COROLLA WIDTH IN IPOMOPSIS AGGREGATA

In the hummingbird-pollinated herb Ipomopsis aggregata, selection through male function during pollination favors wide corolla tubes. We explored the mechanisms behind this selection, using phenotypic selection analysis to compare effects of corolla width on two components of male pollination success, pollinator visit rate and pollen exported per visit. During single visits by captive hummingbirds, flowers with wider corollas exported more pollen, and more dye used as a pollen analogue, to stigmas of recipient flowers. Corolla width was less strongly related to visit rate in the field, and had no direct effect on visit rate after nectar production and corolla length were controlled for. Moreover, the phenotypic selection differential was 80% higher for the effect on pollen exported per visit, suggesting that this is the more important mechanism of selection.     

A third family of allelic hsd genes in Salmonella enterica: sequence comparisons with related proteins identify conserved regions implicated in restriction of DNA

Salmonella enterica serovar blegdam has a restriction and modification system encoded by genes linked to serB . We have cloned these genes, putative alleles of the hsd locus of Escherichia coli  K-12, and confirmed by the sequence similarities of flanking DNA that the hsd genes of S. enterica serovar blegdam have the same chromosomal location as those of E. coli K-12 and Salmonella enterica serovar typhimurium LT2. There is, however, no obvious similarity in their nucleotide sequences, and while the gene order in S. enterica serovar blegdam is serB hsdM , S and R , that in E. coli K-12 and S. enterica serovar typhimurium LT2 is serB hsdR , M and S . The hsd genes of S. enterica serovar blegdam identify a third family of serB -linked hsd genes (type ID). The polypeptide sequence predicted from the three hsd genes show some similarities (18–50% identity) with the polypeptides of known and putative type I restriction and modification systems; the highest levels of identity are with sequences of Haemophilus influenzae Rd. The HsdM polypeptide has the motifs characteristic of adenine methyltransferases. Comparisons of the HsdR sequence with those for three other families of type I systems and three putative HsdR polypeptides identify two highly conserved regions in addition to the seven proposed DEAD-box motifs.     

Characterization of a newin vitro model for studies of reepithelialization in human partial thickness wounds

Summary Reepithelialization of artificial partial thickness wounds made in biopsies of human skin was determined after 3, 5, or 7 d of incubation, submerged or elevated to the air-liquid interface. The biopsies were reepithelialized within 5–7 d, with a more complete epidermal healing in wounds exposed to air. Both types of wounds showed similar time-course in deposition of basement membrane components, as detected by immunofluorescence labeling. Laminin and collagen type VII were deposited underneath the migrating tips, whereas collagen type IV was detected after reepithelialization. Markers of terminal differentiation showed a pattern close to normal in the air-liquid incubated wounds after reepithelialization. Involucrin was detected in the suprabasal regions of the migrating epidermis and thereafter in the upper half of neo-epidermis in the air-liquid incubated wound. Filaggrin could not be detected in the submerged wounds at any time during healing, whereas wounds exposed to air showed a well-differentiated epidermis by Day 7. Tritiated thymidine-incorporation indicated proliferation of epidermal and dermal cells during reepithelialization and a maintained viability, as shown by cultivation of endothelial- and fibroblast-like cells obtained from the dermis 7 d after wounding. Reepithelialization in this humanin vitro model is supported by a matrix close to normal with the possibility of extracellular influences and cell-cell interactions and, in addition, the technique is simple and reproducible. Therefore, we suggest this model for studies of regeneration in culture and as a complement toin vivo studies on epidermal healing.     

Analysis of WT1 gene expression during mouse nephrogenesis in organ culture

Summary The temporal and spatial expression patterns of the Wilms tumor gene, WT1, were studied during the organogenesis of the mouse kidneyin vitro. In situ hybridization and immunocytochemistry localized cellular expression of WT1 in whole kidney organ cultures to the induced metanephric mesenchyme and developing podocytes. Organ cultures were further characterized immunocytochemically with antibodies that specifically labeled the different tubular epithelial components and supporting mesenchyme of the developing nephrons. In organ cultures, the WT1 expression pattern could be visualized in induced metanephric mesenchyme and entire cell cohorts of differentiating podocytes. Expression of WT1 and cell specific markers were retained in short-term monolayer cultures of dissociated kidneys. The development of the metanephric kidneyin vitro involves a highly restricted temporal and spatial cellular expression pattern of WT1 which closely follows that observed in tissue sections from gestational kidney isolated during organogenesis in the mouse.     

IN VIVO EFFECTS OF CARDIOTROPHIN-1

Cardiotrophin-1 (CT-1) is a recently discovered cytokine that was isolated based on its ability to induce cardiac myocyte hypertrophy in vitro. In this study, the effects of chronic administration of CT-1 to mice (0.5 or 2 μg by intraperitoneal injection, twice a day for 14 days) were determined. A dose-dependent increase in both the heart weight and ventricular weight to body ratios was observed in the treated groups. The body weights of the animals were unaffected. These results indicate that CT-1 can induce cardiac hypertrophy in vivo. CT-1 was not specific for the heart, however. It stimulated the growth of the liver, kidney, and spleen, and caused atrophy of the thymus. CT-1 administration also increased the platelet counts by 70%, with no change in mean platelet volume. Red blood cell counts were increased in the treated animals, and there was a concomitant increase in haemoglobin concentration. Thus, CT-1 has a broad spectrum of biological activities in vivo. This observation is consistent with previous in-vitro findings showing that the mRNA for CT-1 is expressed in several tissues, and that CT-1 can function through binding to the leukaemia inhibitory factor (LIF) receptor and signalling through the gp130 pathway.