A study of the hatching process in aquatic invertebrates. XVI. Events of eclosion in Calopsectra neoflavellus Malloch (Diptera,Tendipedidae). XVII. Hatching in Argulus megalops Smith (Crustacea,Branchiura)

Summary Hatching in the tendipedid, Calopsectra neoflavellus involves first a slow uptake of water by the embryo during development, whereby it increases in size and comes to fill entirely the space within the chorion. After completion of embryonic development, the prolarva increases still more in size by swallowing and absorbing water. Internal pressure thus generated results in the bursting of the chorion. The larva then frees itself by active movements.In the branchiuran, Argulus megalops, hatching is similar to that previously described for Copepoda, in that an inner egg membrane swells osmotically and splits the outer chorion. Subsequent bursting of the inner membrane throws the larva nearly out of the egg, but final emergence is by active struggle of the larva.

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Zusammenfassung Das Ausschlüpfen von Calopsectra neoflavellus enthält erstens eine langsame Wasseraufnahme durch den Embryo, wodurch der Embryo wächst und das Wasser den ganzen Raum zwischen Embryo und Chorion füllt. Nach Vollendung der Entwicklung quillt der Embryo noch mehr auf durch den Schluckakt und Aufnahme des Wassers. Dann zerreisst das Chorion durch den intraovularen Druck. Endlich befreit sich die Larve durch Sträuben.In Argulus megalops (Branchiura) gleicht das Ausschlüpfen dem vorher dargestellten für den Copepoden. Eine innere Membran schwillt osmotisch und zerreisst; das Chorion dann zerreist auch die innere Membran selbst and wirft die Larve nahezu aus dem Ei hinaus, aber die schliessiiche Befreiung geschieht durch Sträuben.

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Supported by National Science Foundation grant GB-219, entitled A study of hatching and of the ecology of egg masses of aquatic invertebrates.     

The Chilliwack Respiratory Survey, 1963: Part I. Methodology

In order to ascertain the prevalence of chronic respiratory disease in residents of a rural town and to determine the relative importance of tobacco smoking and air pollution, a survey was conducted of 726 persons living at Chilliwack, British Columbia, in May and June, 1963. Over 95% of a random sample of adults was interviewed and performed simple tests of respiratory function. The sample was selected from a commercial census. An analysis of the demographic characteristics of the sample indicated that the group, aged 25 to 74 years, was reasonably representative for detailed study of chronic respiratory disease.     

Heterozygotes for cystic fibrosis: models for study of airway and autonomic reactivity

Airway reactivity to cold air and methacholine, alpha-adrenergic and cholinergic reactivity measured as pupillary responses to phenylephrine and carbachol, respectively, and beta-adrenergic reactivity assessed by lymphocyte adenosine 3',5'-cyclic monophosphate (cAMP) response to isoproterenol were compared in 108 parents of patients with cystic fibrosis (CF) and 133 healthy adult controls. No differences were found between CF parents and controls in airway response to cold air or methacholine or in lymphocyte cAMP response to isoproterenol. Significant differences were found, however, in the response of the pupils to both phenylephrine and carbachol. Heterozygotes for CF have more reactive pupils; i.e., they require smaller doses of agonist for a 10% change in pupil size. In control subjects, the response of the pupils to phenylephrine and carbachol is highly correlated (r = 0.45, P less than 0.001), whereas in CF heterozygotes, the correlation is not significantly different from zero (r = -0.02). In controls, the pupil response to carbachol has a significant negative correlation with cold air response (r = 0.39, P less than 0.05), indicating that those whose pupils were most sensitive to carbachol had the greatest airway reactivity to cold air, but in CF heterozygotes the correlation is not significant (r = 0.10). A significant correlation exists between lymphocyte cAMP response and airway cold air response in CF heterozygotes (r = -0.32, P less than 0.05) (those whose beta-adrenergic responsiveness is low have greater airway reactivity), but not in controls. The CF parents with the most reactive airways tend to have lower beta-adrenergic responses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Definition of subchromosomal intervals around the myotonic dystrophy gene region at 19q

The localization to 19q of the gene causing myotonic dystrophy (DM) has been defined more precisely by refinement of the physical location of several linked markers. A somatic cell hybrid mapping panel from cells with t(1;19), t(12;19), and t(X;19) translocation products was constructed to define five different intervals across 19q. In addition, we have derived a series of cell hybrids by irradiation of a der(19)-only hybrid to further subdivide the cen-q13.1 region. Using an array of 36 cloned genes, anonymous DNAs, and enzyme markers, we have tested the location of the panel breakpoints and refined the regional assignment of several of these markers. All markers tightly linked to DM are localized mainly within 19q13.2, thus suggesting that the DM gene is also close to this region.     

Mutational analysis of a lactogenic hormone reveals a role for lactogen-specific amino acid residues in receptor binding and mitogenic activity

Mutant forms of mouse placental lactogen-II (PL-II) have been generated to assess the role of specific amino acid residues and protein regions in binding to the PRL receptor and in mitogenic activity. Conversion of any of three lactogen-specific residues significantly reduced both of these hormone functions; mutation of the two other lactogen-specific amino acids revealed only minimal effects unless these changes were coupled with a second mutation. Deletions within the PL-II protein all resulted in a complete loss of function, but switching regions between PL-II and proliferin, another member of the prolactin family in the mouse, did yield a chimeric protein with some PRL-like activity. This activity was increased substantially by conversion of one amino acid residue in the proliferin region to the corresponding lactogen-specific residue. The locations of the amino acids that have been found to affect hormone function are predicted to be closely apposed in the folded protein, suggesting that this region may be the site of interaction of this lactogenic hormone with the PRL receptor.     

Expression of beta-amyloid precursor protein in reactive astrocytes following neuronal damage

Although the beta-amyloid peptide is an established core component of neuritic plaques that accumulate in Alzheimer's disease, the mechanisms responsible for its deposition are not well understood. We now report that lesions of rat hippocampal neurons cause a time-dependent, long-lasting elevation of immunoreactivity for the beta-amyloid precursor protein (APP) in neighboring astrocytes, a cell type not normally containing the protein. The increase represents astroglial expression of the protein rather than a scavenging of APP released by damaged neurons. Immunoelectron microscopy confirmed that APP-containing cells are reactive astroglia, both surrounding capillaries and within the neuropil. These results demonstrate that neuronal damage stimulates APP expression in adult brain and suggest that reactive astrocytes may be a source of the beta-amyloid that forms neuropathological plaques in Alzheimer's disease.     

Altered expression of keratin and vimentin in human retinal pigment epithelial cells in vivo and in vitro.

Actively proliferating human retinal pigment epithelial (RPE) cells grown in tissue culture possess keratin-containing intermediate filaments that react with a combination of AE1 and AE3 anti-keratin monoclonal antibodies. Antibody reactivity is lost, however, from RPE cells as the cell population ceases to proliferate when it approaches confluence and attains morphological characteristics more similar to those in vivo. In contrast, clone 8.13 anti-keratin antibody stains all cells in the culture at all stages of the growth cycle and cell densities. These findings were reflected in vivo using retinal pigment epithelium taken directly from the eye. Normal non-proliferating RPE cells bound 8.13 antibody to cytoskeletal structures, as judged by indirect immunofluorescence, but did not bind AE1/AE3 antibodies. However, proliferating dedifferentiated RPE cells from the vitreous humor of patients with proliferative vitreoretinopathy possess filaments that bind both AE1/AE3 and 8.13 antibodies. Thus it appears that structures detected by AE1/AE3 antibodies only occur in actively growing RPE cells in vitro and in vivo. Keratins produced by RPE cells were identified using Western blotting. Species with molecular masses of 54 (keratin 7), 52 (keratin 8), 42 (keratin 18), and 40 (keratin 19) kiloDaltons were the most abundant in proliferating cultured cells, but cells isolated directly from the eye were found to lack keratin 7 and 19. Keratin 19 was, however, observed in proliferating RPE cells from some patients with proliferative vitreoretinopathy. The latter findings explain the differential staining observed with AE1/AE3 antibodies in cells in culture and isolated directly from the eye since these antibodies interact primarily with keratin 19 which is absent from non-proliferating RPE cells. In contrast to the presence of keratin-containing intermediate filaments in human RPE cells in vivo, there are apparently no detectable vimentin-containing cytoskeletal structures. However, all RPE cells cultured in vitro develop filaments composed of vimentin which persist in cells that have reached confluence.     

The protein Id: a negative regulator of helix-loop-helix DNA binding proteins

We have isolated a cDNA clone encoding a novel helix-loop-helix (HLH) protein, Id. Id is missing the basic region adjacent to the HLH domain that is essential for specific DNA binding in another HLH protein, MyoD. An in vitro translation product of Id can associate specifically with at least three HLH proteins (MyoD, E12, and E47) and attenuate their ability to bind DNA as homodimeric or heterodimeric complexes. Id is expressed at varying levels in all cell lines tested. In three cell lines that can be induced to undergo terminal differentiation, Id RNA levels decrease upon induction. Transfection experiments indicate that over-expression of Id inhibits the trans-activation of the muscle creatine kinase enhancer by MyoD. Based on these findings, we propose that HLH proteins lacking a basic region may negatively regulate other HLH proteins through the formation of nonfunctional heterodimeric complexes.