Argyrophil endocrine cells with ACTH and HCG immunoreactivity in a carcinoma of the breast

A middle-aged woman without any symptoms of ectopic hormone production underwent a right-sided mastectomy for infiltrating ductal carcinoma. She later developed axillary lymph node metastases which were somewhat carcinoid-like. This prompted further investigation, when scattered argyrophilic endocrine cells were found in both the primary tumour and its metastases. The endocrine cells reacted immunocytochemically with antisera against ACTH and HCG. Despite the endocrine activity of the tumour, it was still regarded as a ductal carcinoma since the endocrine cells constituted the minority cell population. The present study indicates strongly that ectopic hormone production in association with carcinoma of the breast is a result of hormone synthesis and release by the tumour cells.     

Diphtheria toxin-receptor interaction: A polyphosphate-insensitive diphtheria toxin-binding domain

Inositol hexaphosphate, and other polyphosphates, inhibit diphtheria toxin-mediated cytotoxicity by binding to the toxin at a highly cationic site called the P site and preventing toxin binding to cell surface receptors. The binding of diphtheria toxin to a solubilized cell surface glycoprotein (150,000 daltons) is also inhibited by these polyphosphates. Treatment of this 150,000 dalton diphtheria toxin-binding cell surface glycoprotein with papain yielded an 88,000 dalton and a 74,000 dalton diphtheria toxin-binding glycoprotein whose binding to toxin was no longer inhibited by inositol hexaphosphate. This result suggests a model of diphtheria toxin-receptor interaction in which the toxin receptor possesses one binding site which interacts with the P site of the toxin in a $\text{polyphosphate-sensitive}$ fashion, and another binding site (located within the papain-derived 74,000–88,000 dalton glycoproteins) which can interact with the toxin at a site distinct from the P site (the X site) in a $\text{polyphosphate-insensitive}$ fashion. This X site-receptor interaction may be involved in the binding of CRM proteins that bind to the toxin receptor but that do not bind polyphosphates, or it may be involved in the entry process of the toxin.     

Growth of mouse embryos implanted in the subcutaneous tissue of recipient mice

Eight-days-old mouse embryos were transferred to the subcutaneous tissue of the dorsal skin of host mice. A high rate of embryos developed into hemorrhagic (HN) or nonhemorrhagic nodules (NHN). The latter had trophoblastic cells as well as embryoblastic derivatives whereas HN contained almost only trophoblastic cells. At least two kinds of trophoblastic cells were present in NHN: small cells and large cells similar to trophoblastic giant cells. In HN most trophoblastic cells arranged themselves into a network whose meshes contained host blood. Although embryoblastic derivatives such as endoderm and Reichert's membrane were apposed to host connective tissue cells, trophoblastic cells were always surrounded by collagen fibrils or by a layer of an amorphous material.     

The distribution of dissolved DNA in an oligotrophic and a eutrophic river of Southwest Florida

The distribution of dissolved DNA concentrations and some microbial variables were compared in an oligo-mesotrophic river (the Crystal River) and a phosphate-rich eutrophic river (the Alafia River) in Southwest Florida over a 15 month period. Concentrations of phosphate and nitrate in the Alafia River averaged 135 and 18.2 times the respective phosphate and nitrate concentrations of the oligo-mesotrophic Crystal River. The seasonal average dissolved DNA concentration for the Alafia River exceeded that of the Crystal River by a factor of 1.8 (8.2 g 1^–1 compared to 4.6 g 1^–1, respectively). The greatest concentrations of dissolved DNA in the Alafia River were found in areas that contained the largest populations of phytoplankton and bacteria (a reservoir formed from an abandoned phosphate mining pit and two downstream stations near the mouth of the river). Differences in dissolved DNA concentrations between these environments and more pristine environments (i.e. all Crystal River Stations and upstream Alafia River stations) were of the same order of magnitude (1.8 to 2.2-fold) as the differences in bacterial abundance and activity, but considerably less than differences in phytoplankton abundance and activity between such environments. Seasonal variations in dissolved DNA concentrations in the Crystal River corresponded to seasonal variations in microbial populations, with minimal values in January and greater values in July. In the Alafia River, lowest concentrations for dissolved DNA occurred in July during the wet season, when seasonal flooding of area of leaf litter yielded high levels of dissolved organic carbon (DOC) which were low in dissolved DNA. These results suggest that: 1) in situ planktonic activity is a greater source of dissolved DNA than allochthonous or terrestrial sources of DOC; 2) factors that control the magnitude of heterotrophic bacterial populations are more likely to control dissolved DNA levels than factors regulating autotrophic population activity and abundance; 3) differences in dissolved DNA between eutrophic and oligo-mesotrophic environments are often much smaller than the differences in nutrient concentration between such environments.     

Two frameshift mutations in the cystic fibrosis gene

Cystic fibrosis (CF) is a recessive disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. We have identified in exon 7 two frameshift mutations, one caused by a two-nucleotide insertion and the other caused by a one-nucleotide deletion; these mutations--CF1154insTC and CF1213delT, respectively, are predicted to shift the reading frame of the protein and to introduce UAA(ochre) termination codons at residues 369 and 368.     

Comparison of binding of mixed ribose-deoxyribose analogues of CUCU to a ribozyme and to GGAGAA by equilibrium dialysis: evidence for ribozyme specific interactions with 2' OH groups

Dissociation constants at 15 degrees C were measured by equilibrium dialysis for the binding of rCrUrCrU, dCrUrCrU, rCdUrCrU, rCrUdCrU, and rCrUrCdU to the L-21 ScaI form of the self-splicing group I LSU intron from Tetrahymena thermophila. Substitution of deoxyribose for ribose in each of the middle two positions makes the free energy change for binding 1-2 kcal/mol less favorable, compared to about 0.3 kcal/mol less favorable for each of the terminal positions. Dissociation constants for binding of the same oligomers to rGGAGAA were measured by optical melting methods. Substitution of a single deoxyribose for ribose makes the free energy change for binding less favorable by 0.4-0.9 kcal/mol for this simple duplex formation. Comparison of the effects for binding to ribozyme and to rGGAGAA indicate that ribozyme-specific tertiary interactions dependent on the middle two 2' OH groups of rCrUrCrU add about 2 kcal/mol of favorable free energy for binding to L-21 ScaI. Comparisons are made with results from gel retardation studies [Pyle, A. M., McSwiggen, J. A., & Cech, T. R. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 8187-8191; Pyle, A. M., & Cech, T. R. (1991) Nature (London) 350, 628-631].     

MULTIVARIATE PHENOTYPIC DIFFERENTIATION AMONG BOTTLENECK LINES OF THE HOUSEFLY

Multivariate phenotypic differentiation in eight morphometric traits was examined in bottleneck lines of the housefly initiated with one, four, or 16 pairs of flies from a natural outbred population. Differentiation was assessed using a Mahalanobis' distance metric in units of additive genetic variance and covariance estimated from the ancestral population (i.e., generalized genetic distance). This distance metric was partitioned into contributions of size and shape to total distance. Bottleneck lines of all sizes diverged significantly from the ancestral line, but the direction of these shifts differed among the lines of different initial founding size. Those populations founded with single pairs diverged from the ancestral line mostly in shape; the 16-pair lines differentiated almost entirely in size, and the four-pair lines were intermediate in the relative contribution of shape to differentiation from the control. Bottlenecks serve to alter the genetic relationships among traits within the derived populations and in doing so could promote speciation by permitting differentiation of the populations along evolutionary trajectories less accessible to the base population.     

Occurrence of Nitrate Reductase and Molybdopterin in Xanthomonas maltophilia

Fifteen of 23 ATCC strains and 2 of 9 clinical isolates of Xanthomonas maltophilia, all of which grew aerobically on ammonia, but not nitrate, as a sole nitrogen source, reduced nitrate to nitrite. X. maltophilia failed to grow anaerobically on complex medium with or without nitrate, so it is considered an obligate aerobe. Nitrate-reducing strains contained reduced methyl viologen nitrate reductase (MVH-NR) with specific activities ranging from 49.2 to 192 U mg of protein⁻¹. Strain ATCC 17666 doubled its cell mass after 3 h of growth on nitrate broth under low aeration, possessed maximal MVH-NR activity, and converted the added nitrate to nitrite, which accumulated. Dissolved oxygen above 15% saturation greatly suppressed nitrite formation. All strains, except ATCC 14535, possessed between 0.25 and 5.05 pmol of molybdopterin mg of protein⁻¹ as measured by the Neurospora crassa nit-1 assay. The molybdopterin activity in the soluble fraction sedimented as a single symmetrical peak with an s_20,w of 5.1. Studies identified MVH-NR in selected strains as a membrane-bound protein. The deoxycholate-solubilized MVH-NR sedimented as a single peak in sucrose density gradients with an s_20,w of 8.8. The MVH-NR of X. maltophilia has the physical characteristics of a respiratory nitrate reductase and may enable cells to use nitrate as an electron sink under semiaerobic conditions.