The cloning of Aspergillus nidulans mitochondrial DNA in Escherichia coli on plasmid pBR322

Summary We report the cloning of almost the entire mitochondrial DNA of Aspergillus nidulans on plasmid pBR322 in Escherichia coli. Only one fragment containing about 11% of the mitochondrial genome has not been cloned. We believe that this fragment cannot be maintained in E. coli on the pBR322 plasmid.     

Effect of inorganic pyrophosphate on respiration and oxidative phosphorylation in higher plants

In coupled mitochondria of maize, inorganic pyrophosphate has no effect on electron transport whereas it competitively inhibits state 3 (with addition of ADP) respiration. The degree of inhibition depends on the ADP concentration in the reaction medium. At 150 and 30O μM ADP, the inhibition constant (K_i) has a value of 1.1 × 10⁻⁴ M. Pyrophosphate either does not penetrate throucvh the membranes or penetrates through them in only very small amounts. It does not inhibit the exchange ³²PiPi; however, it undergoes an exchange with ADP (2 nmol PPi/mg protein for 10 min at 30°).     

Density-dependent predation ofChaoborus flavicans onDaphnia longispina in a small lake: the effect of prey size

Functional response curves of fourth instar larvae ofChaoborus flavicans preying on two size classes ofDaphnia longispina were examined throughout three summer seasons in a small forest lake. Data for each size class were fitted to Holling's disc equation. The parametersa (attack rate) andTh (handling time) were calculated for each prey size from these curves. Attack rate was greater and handling time was shorter for small (0.77 mm) than for large (1.82 mm)Daphnia. In 1:1 mixture of these prey size classes the predation rates ofChaoborus on smallDaphnia at prey densities above 20 l^–1 were greater than predicted from the single size-class experiments. The observed predation rates on largeDaphnia were lower than predicted at all prey densities. Since both single size-class and two size-class experiments were run during the same period of time the difference in observed and predicted predation rates could not be attributed to seasonal changes in prey preference ofChaoborus larvae. In experiments with a concentrated mixture of lake zooplankton (dominated byD. longispina)Chaoborus preference forDaphnia decreased as prey body size increased. There was no obvious correlation between selectivity coefficients and size-frequency distributions ofDaphnia. When medium-sizedDaphnia were omitted from calculations the preference of small over large prey did not differ significantly from the predictions of the single size-class model.     

Effects of fatty acid chain length and saturation on gastric inhibitory polypeptide release in obese hyperglycaemic (ob/ob) mice

Plasma gastric inhibitory polypeptide (GIP) responses to equimolar intragastrically administered emulsions of fatty acids (2.62 mmol/7.5 ml/kg) were examined in 18 h fasted obese hyperglycaemic (ob/ob) mice. Propionic acid (C3:0), a saturated short-chain fatty acid, and capric acid (C10:0), a saturated medium chain fatty acid, did not signilicantly stimulate GIP release. However, the saturated long-chain fatty acid stearic acid (C18:0), and especially the unsaturated long-chain fatty acids oleic (C18:1), linoleic (C18:2) and linolenic (C18:3) acids produced a marked GIP response. The results show that chain length and to a lesser extent the degree of saturation are important determinants of fatty acid-stimulated GIP release. The GIP-release action of long-chain, but not short-chain, fatty acids may be r e l a t e d to differences in their intracellular handling.     

Petite deletion map of the mitochondrial oxi3 region in Saccharomyces cerevisiae.

Summary Fifty eight mitochondrial mutants (p ⁺ mit^- mutants), all deficient in cytochrome oxidase activity and previously assigned to the genetic region oxi3 on the mitochondrial DNA, were mapped by the method of petite deletion mapping.This procedure resulted in the identification of at least twenty one different classes of oxi3 mutants, which could be arranged in a linear order.Moreover, it provided a set of twenty three p ^- petite mutants, each containing a differentially deleted mit DNA segment included in the oxi3 region. The two sets of mutants, p ⁺ oxi3 ^- and p ^- oxi3 ⁺, will be of interest for a further genetic and physical analysis of this mitochondrial DNA segment which spans over about ten thousand base pairs and controls the subunit I of cytochrome oxidase.     

Enhancing Pseudo-Telepathy in the Magic Square Game

We study the possibility of reversing an action of a quantum channel. Our principal objective is to find a specific channel that reverses as accurately as possible an action of a given quantum channel. To achieve this goal we use semidefinite programming. We show the benefits of our method using the quantum pseudo-telepathy Magic Square game with noise. Our strategy is to move the pseudo-telepathy region to higher noise values. We show that it is possible to reverse the action of a noise channel using semidefinite programming.     

Cloning and analysis of a bifunctional methyltransferase/restriction endonuclease TspGWI, the prototype of a Thermus sp. enzyme family

Background  

Restriction-modification systems are a diverse class of enzymes. They are classified into four major types: I, II, III and IV. We have previously proposed the existence of a Thermus sp. enzyme family, which belongs to type II restriction endonucleases (REases), however, it features also some characteristics of types I and III. Members include related thermophilic endonucleases: TspGWI, TaqII, TspDTI, and Tth111II.     

Ni-Supported Pd Nanoparticles with Ca Promoter: A New Catalyst for Low-Temperature Ammonia Cracking

In this paper we report a new nanometallic, self-activating catalyst, namely, Ni-supported Pd nanoparticles (Pd_NPs/Ni) for low temperature ammonia cracking, which was prepared using a novel approach involving the transfer of nanoparticles from the intermediate carrier, i.e. nano-spherical SiO₂, to the target carrier technical grade Ni (t-Ni) or high purity Ni (p-Ni) grains. The method that was developed allows a uniform nanoparticle size distribution (4,4±0.8 nm) to be obtained. Unexpectedly, the t-Ni-supported Pd NPs, which seemed to have a surface Ca impurity, appeared to be more active than the Ca-free (p-Ni) system. A comparison of the novel Pd_NPs/Ni catalyst with these reported in the literature clearly indicates the much better hydrogen productivity of the new system, which seems to be a highly efficient, flexible and durable catalyst for gas-phase heterogeneous ammonia cracking in which the TOF reaches a value of 2615 mmol_H2/g_Pd min (10,570 mol_NH3/mol_Pd(NP) h) at 600°C under a flow of 12 dm³/h (t-Ni).     

Tokenism

Before Writing, Volume 1: From Counting to Cuneiform . Denise Schmandt-Besserat. Austin: University of Texas Press, 1992. 288 pp.
Before Writing, Volume 2: A Catalog of Near Eastern Tokens . Denise Schmandt-Besserat. Austin: University of Texas Press, 1992. 452 pp.