A simple model for early morphogenesis

Despite the large amount of knowledge which continues to accumulate about early developmental events, very little is known about the processes which control them. Part of the problem may lie in that workers applying different approaches and techniques have different points of view and appear to be reluctant to read each others' literature. My aim in this paper is not to give a generative, formal model for early development, but rather to suggest several connecting strands between the physiological, biochemical, cell biological and experimental embryological approaches which may stimulate new research in fields between those already exploited.     

New bovine adrenal medullary peptide and its precursor

We have isolated a previously unknown peptide and its precursor from bovine adrenal medullary chromaffin granules. The peptide sequence is Leu-Pro-Val-Asn-Ser-Pro-Met-Asn-Lys-Gly-Asn-Glu-Val-Met-Lys. The peptide is cleaved from the precursor at a Lys site. The sequence shows no homology to any known protein in the largest sequence data bank available.     

Infective Factors in Exacerbations of Bronchitis and Asthma

Infections of the respiratory tract were studied in a group of families each containing a patient with chronic bronchitis or with asthma. A wide variety of infective agents may be associated with exacerbations in susceptible subjects, but the types of organism to which patients are most at risk differ according to the family structure. Exacerbations in the susceptible subject are more likely to be related to viral infections when the family contains children than when it does not.Two patients with asthma experienced frequent respiratory infections, many of which provoked attacks of asthma.     

Simple methods for generating neural,bone and endodermal cell types from chick embryonic stem cells

Most work on embryonic stem cell differentiation uses mammalian cells derived from the blastocyst stage and some of the most widely used protocols to induce differentiation involve growing these cells in monolayer culture. Equivalent stem cells can be obtained from embryos of non-mammalian vertebrates, but to date this has only been successful in birds. These cells can contribute to all somatic lineages in chimaeras and can be induced to differentiate into a variety of cell types in vitro via embryoid body formation. However to date there are no reliable methods for differentiating them into descendants from each of the germ layers in monolayer culture, comparable to the protocols used in mammals. Here we describe three simple and reproducible protocols for differentiation of chick embryonic stem cells into mesoderm (bone), endoderm and neuroectoderm (neurons and glia) in monolayer culture. These methods open the way for more direct comparisons of the properties of mammalian and avian embryonic stem cells that may highlight similarities and differences.     

Rotator cuff muscle function and its relation to scapular morphology in apes

It is widely held that many differences among primate species in scapular morphology can be functionally related to differing demands on the shoulder associated with particular locomotor habits. This perspective is largely based on broad scale studies, while more narrow comparisons of scapular form often fail to follow predictions based on inferred differences in shoulder function. For example, the ratio of supraspinous fossa/infraspinous fossa size in apes is commonly viewed as an indicator of the importance of overhead use of the forelimb, yet paradoxically, the African apes, the most terrestrial of the great apes, have higher scapular fossa ratios than the more suspensory orangutan. The recent discovery of several nearly complete early hominin scapular specimens, and their apparent morphological affinities to scapulae of orangutans and gorillas rather than chimpanzees, has led to renewed interest in the comparative analysis of human and extant ape scapular form. To facilitate the functional interpretation of differences in ape scapulae, particularly in regard to relative scapular fossa size, we used electromyography (EMG) to document the activity patterns in all four rotator cuff muscles in orangutans and gibbons, comparing the results with previously published data for chimpanzees.     

Uncoupling of Natural IgE Production and CD23 Surface Expression Levels

CD23, the low affinity receptor for immunoglobulin E (IgE), has been proposed to play a critical role in the regulation of IgE production, based on altered IgE levels in CD23-deficient mice and transgenic mouse models, as well as in mouse strains with mutations in the CD23 gene, e.g. 129 substrains. Here, we have investigated a mouse line termed LxT1 that expresses reduced CD23 surface levels on B cells, and its influence on natural IgE production. Extensive phenotypic analysis showed that CD23 surface expression was reduced in LxT1 compared to the control, without affecting B cell development in general. This CD23^low surface level in LxT1 mice is not as a result of reduced CD23 mRNA expression levels or intracellular accumulation, but linked to a recessive locus, a 129-derived region spanning 28 Mb on chromosome 8, which includes the CD23 gene. Sequence analysis confirmed five mutations within the CD23 coding region in LxT1 mice, the same as those present in New Zealand Black (NZB) and 129 mice. However, this CD23^low phenotype was not observed in all 129 substrains despite carrying these same CD23 mutations in the coding region. Moreover, serum IgE levels in LxT1 mice are as low as those in the C57BL/6 (B6) strain, and much lower than those in 129 substrains. These data indicate that the CD23 surface level and serum IgE level are uncoupled and that neither is directly regulated by the mutations within the CD23 coding region. This study suggests that caution should be taken when interpreting the immunological data derived from mice with different genetic background, especially if the gene of interest is thought to influence CD23 surface expression or serum IgE level.