Role of the Mitochondrial Genome During Early Development in Mice

The role of the mitochondrial genome in early development and differentiation was studied in mouse embryos cultured in vitro from the two to four cell stage to the blastocyst (about 100 cells). During this period the mitochondria undergo morphological differentiation: progressive enlargement followed by an increase in matrix density, in number of cristae, and in number of mitochondrial ribosomes. Mitochondrial ribosomal and transfer RNA synthesis occurs from the 8 to 16 cell stage on and contributes to the establishment of a mitochondrial protein-synthesizing system. Inhibition of mitochondrial RNA- and protein-synthesis by 0.1 µg/ml of ethidium bromide or 31.2 µg/ml of chloramphenicol permits essentially normal embryo development and cellular differentiation. Mitochondrial morphogenesis is also nearly normal except for the appearance of dilated and vesicular cristae in blastocyst mitochondria. Such blastocysts are capable of normal postimplantation development when transplanted into the uteri of foster mothers. Higher concentrations of these inhibitors have general toxic effects and arrest embryo development. It is concluded that mitochondrial differentiation in the early mouse embryo occurs through the progressive transformation of the preexisting mitochondria and is largely controlled by the nucleocytoplasmic system. Mitochondrial protein synthesis is required for the normal structural organization of the cristae in blastocyst mitochondria. Embryo development and cellular differentiation up to the blastocyst stage are not dependent on mitochondrial genetic activity

Debris control design achievements of the booster separation motors

The stringent debris control requirements imposed on the design of the Space Shuttle booster separation motor are described along with the verification program implemented to ensure compliance with debris control objectives. The principal areas emphasized in the design and development of the Booster Separation Motor (BSM) relative to debris control were the propellant formulation and nozzle closures which protect the motors from aerodynamic heating and moisture. A description of the motor design requirements, the propellant formulation and verification program, and the nozzle closures design and verification are presented

Evolution of midplate hotspot swells: Numerical solutions

The evolution of midplate hotspot swells on an oceanic plate moving over a hot, upwelling mantle plume is numerically simulated. The plume supplies a Gaussian-shaped thermal perturbation and thermally-induced dynamic support. The lithosphere is treated as a thermal boundary layer with a strongly temperature-dependent viscosity. The two fundamental mechanisms of transferring heat, conduction and convection, during the interaction of the lithosphere with the mantle plume are considered. The transient heat transfer equations, with boundary conditions varying in both time and space, are solved in cylindrical coordinates using the finite difference ADI (alternating direction implicit) method on a 100 x 100 grid. The topography, geoid anomaly, and heat flow anomaly of the Hawaiian swell and the Bermuda rise are used to constrain the models. Results confirm the conclusion of previous works that the Hawaiian swell can not be explained by conductive heating alone, even if extremely high thermal perturbation is allowed. On the other hand, the model of convective thinning predicts successfully the topography, geoid anomaly, and the heat flow anomaly around the Hawaiian islands, as well as the changes in the topography and anomalous heat flow along the Hawaiian volcanic chain

Stored mafic/ultramafic crust and early Archean mantle depletion

Both early and late Archean rocks from greenstone belts and felsic gneiss complexes exhibit positive epsilon(Nd) values of +1 to +5 by 3.5 Ga, demonstrating that a depleted mantle reservoir existed very early. The amount of preserved pre-3.0 Ga continental crust cannot explain such high epsilon values in the depleted residue unless the volume of residual mantle was very small: a layer less than 70 km thick by 3.0 Ga. Repeated and exclusive sampling of such a thin layer, especially in forming the felsic gneiss complexes, is implausible. Extraction of enough continental crust to deplete the early mantle and its destructive recycling before 3.0 Ga ago requires another implausibility, that the sites of crustal generation of recycling were substantially distinct. In contrast, formation of mafic or ultramafic crust analogous to present-day oceanic crust was continuous from very early times. Recycled subducted oceanic lithosphere is a likely contributor to present-day hotspot magmas, and forms a reservoir at least comparable in volume to continental crust. Subduction of an early mafic/ultramafic oceanic crust and temporary storage rather than immediate mixing back into undifferentiated mantle may be responsible for the depletion and high epsilon(Nd) values of the Archean upper mantle

Does settlement plate material matter? The influence of substrate type on fouling community development

Benthic community composition and ascidian abundance can differ dramatically between adjacent man-made and natural substrates. Although multiple factors, including light exposure, surface orientation, predation exposure, and habitat type, are known to contribute to these patterns, few studies have directly tested the influence of substrate identity on community development. We compared fouling communities on settlement plates composed of commonly occurring natural (granite) and artificial (concrete, high density polyethylene, and PVC) marine materials deployed from late May to mid November 2014 from a floating dock in Newcastle, NH. We sought to determine if observed patterns resulted from differential recruitment onto substrate materials or post-settlement survival and growth. To do this, half of the plates were cleaned during bi-weekly examinations, and half were left un-cleaned. Preliminary analyses indicate that community composition differs between substrate types. These results will help us understand how substrate features contribute to non-native species establishment and habitat dominance, and may inform decisions regarding material usage in marine construction. These findings also underline the importance of settlement substrate choice in scientific studies, as plate material may influence experimental conclusions

Effects of roughness on droplet apparent contact angles on a fiber

This paper reports on our investigation of the effects of surface roughness on the equilibrium shape and apparent contact angles of a droplet deposited on a fiber. In particular, the shape of a droplet on a roughened fiber is studied via the energy minimization method implemented in the surface evolver finite element code. Sinusoidal roughness varying in both the longitudinal and radial directions is considered in the simulations to study the effects of surface roughness on the most stable shape of a droplet on a fiber (corresponding a global minimum energy state). It is found that surface roughness delays droplet shape transition from a symmetric barrel to a clamshell or an asymmetric barrel profile. A phase diagram that includes the effects of fiber roughness on droplet configurations-symmetric barrel, clamshell, and asymmetric barrel-is presented for the first time. It is also found that droplet apparent contact angle tends to decrease on rough fibers. Likewise, roughness tends to increase the force required to detach a droplet from a fiber but the effect diminishes as droplet size increases relative to the size of surface roughness. The results presented in our study have been compared with experimental data or those from prior studies whenever possible, and good agreement has been observed

A Subsurface Irrigated, Controlled Traffic, No- Tillage System

A subsurface trickle irrigation system was protected from damage for 21 months through use of a controlled traffic pattern and no-till agriculture. During this period, seven successive vegetable crops were grown without disturbing the irrigation system. Subsequent inspection of the system indicated that this combination of techniques would enable it to operate for periods greater than two years at acceptable levels without replacement. The experiment was conducted on two soils, a light volcanic ash soil and a heavy alluvial soil with less favorable physical properties, to assess the general applicability of the results. Natural soil compaction over a 16-month period showed no significant effect on yields. Severe compaction imposed by tractor traffic resulted in a decrease in lettuce root weight of one-half, yet it had no significant effect on crop yield. Emitter plugging increased from an average of 23% in the non-compacted plots to 36% in the compacted plots with similar results in both shallow and deep (13 and 28 cm) lateral line placement. Plugging did not significantly reduce crop yields. Water movement along the trickle line and the intermittent nature of plugging may have reduced the influence of plugging on lettuce yields. The results from these experiments indicate that for shallow-rooted, short duration, transplanted vegetable crops, such as lettuce and cabbage, acceptable yields can be obtained without extensive tillage if water and nutrients are adequately supplied. Phosphorus fertilizer distributed through the trickle system was immobilized within 10 cm or less of the emitters. Because transplanted seedlings were placed directly over the emitters, this "banding" effect was more efficient than broadcast applications at similar rates in supplying nutrients to the first crop of lettuce. The results of this research suggest that economy in time and expense may be achieved with a no-till, controlled traffic, subsurface trickle irrigation system. This method permits vegetable growers and others to exploit the benefits of reduced tillage, optimum soil-water conditions, and distribution of fertilizers through the irrigation system. In addition, phosphorus use efficiency may be increased by transplanting over the emitters. With this approach, growers can minimize the cost of lateral line repair and eliminate the cost of removing or replacing trickle laterals for each harvest cycle

Public Broadcasting and the Problem of Government Influence: Towards a Legislative Solution

This article will explore the problems raised by the emergence of the federal government as a television sponsor. It will argue that fundamental structural reform is needed to promote the constitutional values at issue, that such reform will also promote the interests of local control sought by the Public Broadcasting Act of 1967, and that legislative action in furtherance of this structural solution is desirable. In this context this article will consider the proposed Public Broadcasting Financing Act of 1974 and will argue that any bill modeled on it would not eliminate the problems despite its salutary innovations. Not considered, except by implication, is the parallel national public radio structure, the use of public money for television by the Department of Health, Education and Welfare or the somewhat remote issues raised by activities of the National Endowment for the Arts