Notes [September 1980]

DESOTO NWR RECORDS. First recorded observations of six species of birds were made at DeSoto NWR in 1979: 1. Snowy Egret. Seen 10 May in the old Missouri River channel marsh in Harrison Co., Iowa (about 300 yards from the Iowa-Nebraska boundary line). Observer, D. Menke. 2. Hungarian Partridge. Small flock seen 20 and 28 January in the fields near the Refuge\u27s west boundary in Harrison Co., Iowa. Observer, D. Knauer. 3. Worm-eating Warbler. Seen 28 May on the Cottonwood Nature Trail (heavily wooded area) in Washington Co., Nebraska. Observer, D. Menke. 4. Northern Parula. Seen 22 April on the Cottonwood Nature Trail (woods/brushy area) in Washington Co., Nebraska. Observer, Omaha Audubon Society. 5. Manolia Warbler. Seen 12 and 13 May on Cottonwood Nature Trail (heavily wooded area) in Washington Co., Nebraska. Observer, D. Menke. 6. Hooded Warbler. Seen 22 April on Cotton Nature Trail (brushy areal small trees) in Washington Co., Nebraska. Observer, Omaha Audubon Society. —David W. Menke, DeSoto NWR, RR 1, Box 114, Missouri Valley, Iowa 5155

Mesenchymal adenomatous polyposis coli plays critical and diverse roles in regulating lung development.

BackgroundAdenomatous polyposis coli (Apc) is a tumor suppressor that inhibits Wnt/Ctnnb1. Mutations of Apc will not only lead to familial adenomatous polyposis with associated epithelial lesions, but will also cause aggressive fibromatosis in mesenchymal cells. However, the roles of Apc in regulating mesenchymal cell biology and organogenesis during development are unknown.ResultsWe have specifically deleted the Apc gene in lung mesenchymal cells during early lung development in mice. Loss of Apc function resulted in immediate mesenchymal cell hyperproliferation through abnormal activation of Wnt/Ctnnb1, followed by a subsequent inhibition of cell proliferation due to cell cycle arrest at G0/G1, which was caused by a mechanism independent of Wnt/Ctnnb1. Meanwhile, abrogation of Apc also disrupted lung mesenchymal cell differentiation, including decreased airway and vascular smooth muscle cells, the presence of Sox9-positive mesenchymal cells in the peripheral lung, and excessive versican production. Moreover, lung epithelial branching morphogenesis was drastically inhibited due to disrupted Bmp4-Fgf10 morphogen production and regulation in surrounding lung mesenchyme. Lastly, lung mesenchyme-specific Apc conditional knockout also resulted in altered lung vasculogenesis and disrupted pulmonary vascular continuity through a paracrine mechanism, leading to massive pulmonary hemorrhage and lethality at mid-gestation when the pulmonary circulation should have started.ConclusionsOur study suggests that Apc in lung mesenchyme plays central roles in coordinating the proper development of several quite different cellular compartments including lung epithelial branching and pulmonary vascular circulation during lung organogenesis

A deterministic algorithm for experimental design applied to tomographic and microseismic monitoring surveys

SUMMARY Most general experimental design algorithms are either: (i) stochastic and hence give different designs each time they are run with finite computing power, or (ii) deterministic but converge to results that depend on an initial or reference design, taking little or no account of the range of all other possible designs. In this paper we introduce an approximation to standard measures of experimental design quality that enables a new algorithm to be used. The algorithm is simple, deterministic and the resulting experimental design is influenced by the full range of possible designs, thus addressing problems (i) and (ii) above. Although the designs produced are not guaranteed to be globally optimal, they significantly increase the magnitude of small eigenvalues in the model–data relationship (without requiring that these eigenvalues be calculated). This reduces the model uncertainties expected post-experiment. We illustrate the method on simple tomographic and microseismic location examples with varying degrees of seismic attenuation

Trophic ecology of the invasive argentine ant: spatio-temporal variation in resource assimilation and isotopic enrichment

Studies of food webs often employ stable isotopic approaches to infer trophic position and interaction strength without consideration of spatio-temporal variation in resource assimilation by constituent species. Using results from laboratory diet manipulations and monthly sampling of field populations, we illustrate how nitrogen isotopes may be used to quantify spatio-temporal variation in resource assimilation in ants. First, we determined nitrogen enrichment using a controlled laboratory experiment with the invasive Argentine ant (Linepithema humile). After 12 weeks, worker δ15N values from colonies fed an animal-based diet had δ15N values that were 5.51% greater compared to colonies fed a plant-based diet. The shift in δ15N values in response to the experimental diet occurred within 10 weeks. We next reared Argentine ant colonies with or without access to honeydew-producing aphids and found that after 8 weeks workers from colonies without access to aphids had δ15N values that were 6.31% larger compared to colonies with access to honeydew. Second, we sampled field populations over a 1-year period to quantify spatio-temporal variability in isotopic ratios of L. humile and those of a common native ant (Solenopsis xyloni). Samples from free-living colonies revealed that fluctuations in δ15N were 1.6–2.4‰ for L. humile and 1.8–2.9‰ for S. xyloni. Variation was also detected among L. humile castes: time averaged means of δ15N varied from 1.2 to 2.5‰ depending on the site, with δ15N values for queens ≥ workers > brood. The estimated trophic positions of L. humile and S. xyloni were similar within a site; however, trophic position for each species differed significantly at larger spatial scales. While stable isotopes are clearly useful for examining the trophic ecology of arthropod communities, our results suggest that caution is warranted when making ecological interpretations when stable isotope collections come from single time periods or life stages

Spectroscopic and in vitro Investigations of Fe2+/alpha-Ketoglutarate-Dependent Enzymes Involved in Nucleic Acid Repair and Modification

The activation of molecular oxygen for the highly selective functionalization and repair of DNA and RNA nucleobases is achieved by alpha-ketoglutarate (alpha-KG)/iron-dependent dioxygenases. Of special interest are the human homologues AlkBH of Escherichia coli EcAlkB and ten-eleven translocation (TET) enzymes. These enzymes are involved in demethylation or dealkylation of DNA and RNA, although additional physiological functions are continuously being found. Given their importance, studying enzyme-substrate interactions, turnover and kinetic parameters is pivotal for the understanding of the mode of action of these enzymes. Diverse analytical methods, including X-ray crystallography, UV/Vis absorption, electron paramagnetic resonance (EPR), circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy have been employed to study the changes in the active site and the overall enzyme structure upon substrate, cofactor, and inhibitor addition. Several methods are now available to assess the activity of these enzymes. By discussing limitations and possibilities of these techniques for EcAlkB, AlkBH and TET we aim to give a comprehensive synopsis from a bioinorganic point-of-view, addressing researchers from different disciplines working in the highly interdisciplinary and rapidly evolving field of epigenetic processes and DNA/RNA repair and modification

Wt1 functions in the development of germ cells in addition to somatic cell lineages of the testis

AbstractThe Wilms' tumor suppressor gene, Wt1, encodes a transcription factor critical for development of the urogenital system. To identify lineages within the developing urogenital system that have a cell-autonomous requirement for Wt1, chimeric mice were generated from Wt1-null ES cells. Males with large contributions of Wt1−/− cells showed hypoplastic and dysgenic testes, with seminiferous tubules lacking spermatogonia. Wt1-null cells contributed poorly to both somatic and germ cell lineages within the developing gonad, suggesting an unexpected role for Wt1 in germ cell development in addition to a role in the development of the somatic lineages of the gonad. Wt1 expression was detected in embryonic germ cells beginning at embryonic day 11.5 after migrating primordial germ cells (PGCs) have entered the gonad. Germ cells isolated from Wt1-null embryos showed impaired growth in culture, further demonstrating a role for Wt1 in germ cell proliferation or survival. Therefore, Wt1 plays important, and in some cases previously unrecognized, roles in multiple lineages during urogenital development

Tomographic image of the Mid-Atlantic Plate Boundary in southwestern Iceland

Publisher's version (útgefin grein)The 170 km South Iceland Seismic Tomography (SIST) profile extends from the west and across the Mid‐Atlantic Ridge spreading center in the Western Volcanic Zone and continues obliquely through the transform zone (the South Iceland Seismic Zone) to the western edge of the Eastern Volcanic Zone. A total of 11 shot points and 210 receiver points were used, allowing precise travel times to be determined for 1050 crustal P wave rays and 180 wide‐angle reflections. The large amplitudes of the wide‐angle reflections and an apparent refractor velocity of 7.7 km/s are interpreted to be from a relatively sharp Moho at a depth of 20–24 km. This interpretation differs from the earlier models (based on data gathered in the 1960s and 1970s), of a 10–15 km thick crust underlain by a upper mantle with very slow velocity of 7.0–7.4 km/s. Nevertheless, these older data do not contradict our new interpretation. Implication of the new interpretation is that the lower crust and the crust‐mantle boundary are colder than previously assumed. A two‐dimensional tomographic inversion of the compressional travel times reveals the following structures in the crust: (1) a sharp increase in thickness of the upper crust (“layer 2A”) from northwest to southeast and (2) broad updoming of high velocity in the lower crust in the Western Volcanic Zone, (3) depth to the lower crust (“layer 3”) increases gradually from 3 km at the northwestern end of the profile to 7 km at the southeastern end of the profile, (4) a low‐velocity perturbation extends throughout the upper crust and midcrust into the lower crust in the area of the transform in south Iceland (South Iceland Seismic Zone), and (5) an upper crustal high‐velocity anomaly is associated with extinct central volcanos northwest of the Western Volcanic Zone. The travel time data do not support the existence of a large (> 0.5 km thick) crustal magma chamber in this part of the Western Volcanic Zone but do not exclude the possibility of a smaller one.This research was supported by the U.S. National Science Foundation, the Iceland National Science Foundation, the National Energy Authority of Iceland, the Incorporated Research Institutions for Seismology, IcelandAir, and the Lamont-Doherty Geological Observatory of Columbia University.Peer Reviewe