Respiratory enzymes of the silkmoth Antheraea pernyi in relation to metamorphosis and pupal diapause

1. 1. Wing epidermis from diapausing and non-diapausing silkmoths (Antheraea pernyi) was assayed for NADH [nicotinamide adenine dinucleotide (reduced form)] oxidase, NADH- and succinate-cyctochrome c reductases, and cytochrome c oxidase.2. 2. Diapausing pupae showed a marked decline in activities after pupation and the same subsequent profile of very low activities reported for diapausing Cecropia silkmoths.3. 3. Non-diapausing pupae showed only a slight and transient decline after pupation and otherwise retained relatively high activities throughout metamorphosis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22213/1/0000646.pd

OXIDATIVE ENZYMES AND THE INJURY METABOLISM OF DIAPAUSING CECROPIA SILKWORMS *

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75474/1/j.1749-6632.1960.tb27576.x.pd

TiB_2 and ZrB_2 diffusion barriers in GaAs Ohmic contact technology

The transition metal diboride compounds, ZrB_2 and TiB_2, interposed between Ni/Ge/Au Ohmic contact metallization on n‐type GaAs wafers and an overlying thick Au contact layer, have been investigated to evaluate their effectiveness in stabilizing the Ohmic contact by limiting the in‐diffusion of Au. All of the metal layers were e‐beam deposited except the ZrB_2 which was rf‐diode sputtered. The barrier layer thicknesses were 50 and 100 nm for the TiB_2 and the ZrB_2, respectively. Postdeposition alloying of the contacts was performed at 400, 425, or 450 °C. Auger electron spectroscopy depth profiling of the resultant Ohmic contacts demonstrates that the barrier layers effectively preclude penetration of Au to the Ohmic contact structure. Specific contact resistivities for such contacts are in the low 10^(−7) Ω cm^2 range; although some degradation of the contact resistivity is observed after long term annealing, the values of resistivities do not exceed 1.5×10^(−6) Ω cm^2 after 92 h at 350 °C

Comparative studies of oxidative enzyme systems in epidermis and fat body of diapausing and non-diapausing silkmoths

The activities of four oxidative enzyme systems, including NADH oxidase, succinate-cytochrome c reductase, NADH-cytochrome c reductase, and cytochrome c oxidase, were compared in mitochondrial-microsomal preparations from wing epidermis and fat body of diapausing Samia cynthia pupae, presumptively non-diapausing S. cynthia ricini pupae which were caused to diapause by removal of the brain, and non-diapausing S. cynthia ricini during the pupal and pharate adult period. In diapausing pupae the activities of all enzyme systems were low and presented a profile similar to that previously reported for the Cecropia silkmoth. By contrast, in non-diapausing individuals the activities showed substantially higher levels, and an essentially unchanging pattern from just after the larval-pupal ecdysis through most of adult development. These events are functionally correlated with the patterns of biosynthetic activity in diapausing and non-diapausing silkmoths and are discussed in relation to the endocrine control of diapause and development.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22419/1/0000869.pd

Ion Composition of Titan's Ionosphere Observed During T9 Magnetotail Crossing

In a recent paper, Sittler et al., (2010) presented new results on the T9 encounter by the Cassini spacecraft when it passed through Titan s induced magnetotail. Two crossings were observed, but the first crossing, event 1, is thought to be out flowing ionosphere plasma. T9 is ideal for CAPS IMS probing of the ionosphere, since the ion densities at the higher altitudes of the T9 flyby approx. 10,000 km, allows measurements to be made down to 1 eV without saturating its detectors. Sittler et al., (2010) reported possible detection of NH4+ ions, but favored the detection of CH5+ and C2H5+ ions. In this report we investigate both the medium mass resolution (straight through (ST)) and high mass resolution (linear electric field (LEF)) composition data from the Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer (IMS). We present a more in depth analysis of the composition data and make comparisons with ionospheric models including nitrogen chemistry such as that by Vuitton et al. (2007). The LEF data does not support NH4+ identification, but favors a CH5+ and C2H5+ identification, but also molecular ions C2N+ and CH2NH2+ are chemically allowed possibilities

The injury metabolism of the cecropia silkworm--II. Injury-induced alterations in oxidative enzyme systems and respiratory metabolism of the pupal wing epidermis

It is known that localized injury to the integument of diapausing silkmoth pupae causes an increase in the respiratory metabolism of an insect as a whole. In the present study, this `injury metabolism' has been analysed in an individual tissue, the wing epidermis, both in terms of the oxygen consumption of the isolated intact wing, and through measurement of the activities of several oxidative enzyme systems in mitochondrial-microsomal preparations derived from homogenates of wing.The participation of the wing in the respiratory response of the pupa is clearly evident from both types of experiment. The oxygen consumption of isolated wings is a linear function of that of the pupa and shows a corresponding increase after injury. Moreover, an increase of several fold is observed in the activities of cytochrome c oxidase, DPNH-, TPNH-, and succinatecytochrome c reductase, and DPNH oxidase systems. The enzymatic changes appear to be associated with an increase in concentration of respiratory enzymes, similar in character and magnitude to that observed in the uninjured silkmoth when diapause is terminated.The oxygen consumption of the isolated wing also typifies the behaviour of the pupa as a whole in showing a substantial resistance to inhibition by carbon monoxide. In the intact pupa and in the isolated wing, the degree of sensitivity to this agent increases as a function of the prior respiratory rate in air. Thus the wings of injured pupae, whose respiration is augmented, exhibit greater sensitivity to carbon monoxide than do those isolated from uninjured diapausing pupae. These findings are considered in relation to the `excessoxidase' hypothesis whereby cytochrome oxidase has previously been proposed to function as a carbon monoxide-resistant terminal oxidase in pupal tissues. The present findings are in accord with the hypothesis but do not rule out other explanations for the mechanism of resistance to carbon monoxide.The alterations in respiratory rate and enzyme concentration are of interest in relation to general problems of metabolic control in animal cells and, in particular, the control of specific protein synthesis. The increase in concentration and activity of respiratory enzymes after injury is correlated functionally with the enhanced biosynthetic activity that prevails at this time. Synthesis of respiratory enzymes is viewed as the action of an intracellular regulatory device to maintain a balance of exergonic and endergonic functions under the altered conditions of biological maintenance imposed by injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32044/1/0000087.pd

Influence of Annealing on the Optical and Scintillation Properties of CaWO4_4 Single Crystals

We investigate the influence of oxygen annealing on the room temperature optical and scintillation properties of CaWO$_4$ single crystals that are being produced for direct Dark Matter search experiments. The applied annealing procedure reduces the absorption coefficient at the peak position of the scintillation spectrum ($\sim430$ nm) by a factor of $\sim6$ and leads to an even larger reduction of the scattering coefficient. Furthermore, the annealing has no significant influence on the \emph{intrinsic} light yield. An additional absorption occurring at $\sim400$ nm suggests the formation of O$^-$ hole centers. Light-yield measurements at room temperature where one crystal surface was mechanically roughened showed an increase of the \emph{measured} light yield by $\sim40$ and an improvement of the energy resolution at 59.5 keV by $\sim12$ for the annealed crystal. We ascribe this result to the reduction of the absorption coefficient while the surface roughening is needed to compensate for the also observed reduction of the scattering coefficient after annealing

Preliminary results on Saturn's inner plasmasphere as observed by Cassini: Comparison with Voyager

We present an analysis of Saturn's inner plasmasphere as observed by the Cassini Plasma Spectrometer ( CAPS) experiment during Cassini's initial entry into Saturn's magnetosphere when the spacecraft was inserted into orbit around Saturn. The ion fluxes are divided into two subgroups: protons and water group ions. We present the relative amounts of these two groups and the first estimates of their fluid parameters: ion density, flow velocity and temperature. We also compare this data with electron plasma measurements. Within the plasmasphere and inside of Enceladus' orbit, water group ions are about a factor of similar to 10 greater than protons in number with number densities exceeding 40 cm(-3). Within this inner region the spacecraft acquires a negative potential so that the electron density is underestimated. The electron and proton temperatures, which could not be measured in this region by Voyager, are T similar to 2 eVat L similar to 3. Also, within this inner region the protons, because of a negative spacecraft potential, appear to be super-corotating. By enforcing the condition that protons and water group ions are co-moving we may be able to acquire an independent estimate of the spacecraft potential relative to that estimated when comparing ion-electron measurements. Using our estimates of plasma properties, we estimate the importance of the rotating plasma on the stress balance equation for the inner magnetosphere and corresponding portion of the ring current

Preliminary results on Saturn's inner plasmasphere as observed by Cassini: Comparison with Voyager

We present an analysis of Saturn's inner plasmasphere as observed by the Cassini Plasma Spectrometer ( CAPS) experiment during Cassini's initial entry into Saturn's magnetosphere when the spacecraft was inserted into orbit around Saturn. The ion fluxes are divided into two subgroups: protons and water group ions. We present the relative amounts of these two groups and the first estimates of their fluid parameters: ion density, flow velocity and temperature. We also compare this data with electron plasma measurements. Within the plasmasphere and inside of Enceladus' orbit, water group ions are about a factor of similar to 10 greater than protons in number with number densities exceeding 40 cm(-3). Within this inner region the spacecraft acquires a negative potential so that the electron density is underestimated. The electron and proton temperatures, which could not be measured in this region by Voyager, are T similar to 2 eVat L similar to 3. Also, within this inner region the protons, because of a negative spacecraft potential, appear to be super-corotating. By enforcing the condition that protons and water group ions are co-moving we may be able to acquire an independent estimate of the spacecraft potential relative to that estimated when comparing ion-electron measurements. Using our estimates of plasma properties, we estimate the importance of the rotating plasma on the stress balance equation for the inner magnetosphere and corresponding portion of the ring current