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991.
Rafael Navarro-González Susana Castillo-Rojas Alicia Negrón-Mendoza 《Origins of life and evolution of the biosphere》1991,21(1):39-49
The radiation-induced decomposition of aqueous solutions of formaldehyde was studied at 298 and 77 K in order to obtain an insight into the possible role of ionizing radiation on cometary chemistry. Aqueous solutions of 1.0 mol dm–3 formaldehyde were exposed to -radiation in the dose range from 0.01 kGy to 1.2 MGy. The radiation chemical yield of decomposition of formaldehyde was determined to be: G(–CH2(OH)2)=26.3±1.2 at 298 K and G0.48 at 77 K.Based on previous estimates of the total dose of ionizing radiation that comets have accumulated over 4.6 billion years, we predict a radiation-induced depletion of formaldehyde as a function of depth in comet nuclei: 100% destruction in the outer layers (0–20 m) and 10% destruction in the interior layers.A Portion of this work was presented at the XXVIII COSPAR Plenary Meeting (MF. 7) held at the Hague, The Netherlands on June 25–26, 1990. 相似文献
992.
Patrick A. Randall Marta Pardo Eric J. Nunes Laura López Cruz V. Kiran Vemuri Alex Makriyannis Younis Baqi Christa E. Müller Mercè Correa John D. Salamone 《PloS one》2012,7(10)
Mesolimbic dopamine (DA) is involved in behavioral activation and effort-related processes. Rats with impaired DA transmission reallocate their instrumental behavior away from food-reinforced tasks with high response requirements, and instead select less effortful food-seeking behaviors. In the present study, the effects of several drug treatments were assessed using a progressive ratio (PROG)/chow feeding concurrent choice task. With this task, rats can lever press on a PROG schedule reinforced by a preferred high-carbohydrate food pellet, or alternatively approach and consume the less-preferred but concurrently available laboratory chow. Rats pass through each ratio level 15 times, after which the ratio requirement is incremented by one additional response. The DA D2 antagonist haloperidol (0.025–0.1 mg/kg) reduced number of lever presses and highest ratio achieved but did not reduce chow intake. In contrast, the adenosine A2A antagonist MSX-3 increased lever presses and highest ratio achieved, but decreased chow consumption. The cannabinoid CB1 inverse agonist and putative appetite suppressant AM251 decreased lever presses, highest ratio achieved, and chow intake; this effect was similar to that produced by pre-feeding. Furthermore, DA-related signal transduction activity (pDARPP-32(Thr34) expression) was greater in nucleus accumbens core of high responders (rats with high lever pressing output) compared to low responders. Thus, the effects of DA antagonism differed greatly from those produced by pre-feeding or reduced CB1 transmission, and it appears unlikely that haloperidol reduces PROG responding because of a general reduction in primary food motivation or the unconditioned reinforcing properties of food. Furthermore, accumbens core signal transduction activity is related to individual differences in work output. 相似文献
993.
M.J Fraqueza L.C Roseiro J Almeida E Matias C Santos J.M Randall 《Applied animal behaviour science》1998,60(4):931-330
Twenty three groups of about 30 pigs each were kept in an environmentally controlled room in lairage, at temperatures of 20 or 35°C for periods of 0.5 or 3 h, to establish the effects of these parameters on animal behaviour and meat quality. Following initial exploration, 50% of pigs kept at 35°C but only 5% kept at 20°C lay down before the end of the 0.5 h period. Seven percent of pigs fought in both temperature conditions. When held in lairage for 0.5 h there was no difference in meat quality or skin damage at either temperature. When held for 3 h, about 95% of pigs were lying down after 2 h in the pens. Again, the percentage of animals fighting was similar for both temperatures, the number of encounters increasing during the first 30–40 min. The more intense initial fighting within the group held at 35°C resulted in the pigs lying down slightly earlier. Irrespective of the lairage time, the frequency of sexual activity decreased with temperature. The proportion of carcasses with skin damage increased with lairage time due, perhaps, to the longer duration of aggressive encounters. Increased lairage time at 20°C reduced the incidence of PSE meat, but at 35°C the longer lairage time showed no benefit to animal welfare or meat quality. 相似文献
994.
Randall M. Zusman M.D. Lloyd Axelrod M.D. Nina Tolkoff-Rubin M.D. 《Prostaglandins & other lipid mediators》1977,13(5):819-830
Three patients with the hepatorenal syndrome were treated with prostaglandin E1 administered through a selective renal arterial catheter. Prostaglandin E1 was given in progressively increasing doses (2 to 100 ng/kg/min) over a 60-minute period. Control plasma prostaglandin E levels were elevated in all three patients, 0.98, 0.91, and 0.83 ng/ml, respectively. At the end of the infusion, plasma prostaglandin E levels had risen to 10.4, 2.63, and 10.3 ng/ml in the three patients respectively. Plasma renin activity increased during the course of the infusion in two of the patients. The plasma aldosterone concentration did not change during the prostaglandin E1 infusion. Intrarenal prostaglandin E1 failed to increase urine volume or urinary sodium concentration in three patients with the hepatorenal syndrome. 相似文献
995.
996.
We quantified the effects of increasing small hive beetle (Aethina tumida Murray) populations on guarding behavior of Cape honey bees (Apis mellifera capensis, an African subspecies). We found more confinement sites (prisons) at the higher (50 beetles per colony) rather than lower (25 beetles per colony) beetle density. The number of beetles per prison did not change with beetle density. There were more guard bees per beetle during evening than morning. Neither guard bee nor beetle behavior varied with beetle density or over time. Forty-six percent of all beetles were found among the combs at the low beetle density and this increased to 58% at the higher one. In neither instance were beetles causing depredation to host colonies. Within the limits of the experiment, guarding behavior of Cape honey bees is relatively unaffected by increasing beetle density (even if significant proportions of beetles reach the combs). 相似文献
997.
Sandra Pérez Álvarez Amaury Méndez Guerrero Bernardo Nayar Débora Duarte Marco Antonio Magallanes Tapia Jesús Alicia Chávez Medina Yoannis Domínguez Rodríguez 《Indian journal of microbiology》2018,58(2):222-226
Metarhizium rileyi (Farlow) Samson is an important entomopathogenic fungus of more than 30 species of Lepidoptera larvae. The aim of this research was to characterize isolate of M. rileyi from Quivicán, Cuba on the basis of morphological and molecular approaches. The fungus was isolated from samples of S. frugiperda larvae collected from maize fields of Quivicán municipality, Mayabeque province, Cuba, and it was cultured on PDA?+?Ampicillin solid media for morphological characterization. The DNA was isolated using CTAB method and internal transcribed spacer (ITS1, ITS4) were used as the primers for the amplification. The amplified products of 1335 bp were purified and sequenced at CINVESTAV-IPN in both the directions using the above primers. A consensus sequence was obtained by alignment of the forward and reverse sequences for this region and deposited in GenBank (MG637450). The fungus produced slightly cottony colony of pale green color and dispersed conidia and septal mycelium were observed under the optical microscope. A BLAST search of the sequence in GenBank revealed a 99% of identity with several strains of N. rileyi (e.g., AF368501.1, AB268359.1 and EU553337.1) and M. rileyi (e.g., KY436756.1). This is the first report of M. rileyi isolate from maize fields of Quivicán in Cuba and this is important for biodiversity studies and is another possibility for Integrated Pest Management. 相似文献
998.
999.
1000.
Rimmer KA Foo JH Ng A Petrie EJ Shilling PJ Perry AJ Mertens HD Lithgow T Mulhern TD Gooley PR 《Journal of molecular biology》2011,405(3):804-5496
The Tom20 and Tom22 receptor subunits of the TOM (translocase of the outer mitochondrial membrane) complex recognize N-terminal presequences of proteins that are to be imported into the mitochondrion. In plants, Tom20 is C-terminally anchored in the mitochondrial membrane, whereas Tom20 is N-terminally anchored in animals and fungi. Furthermore, the cytosolic domain of Tom22 in plants is smaller than its animal/fungal counterpart and contains fewer acidic residues. Here, NMR spectroscopy was used to explore presequence interactions with the cytosolic regions of receptors from the plant Arabidopsis thaliana and the fungus Saccharomyces cerevisiae (i.e., AtTom20, AtTom22, and ScTom22). It was found that AtTom20 possesses a discontinuous bidentate hydrophobic binding site for presequences. The presequences on plant mitochondrial proteins comprise two or more hydrophobic binding regions to match this bidentate site. NMR data suggested that while these presequences bind to ScTom22, they do not bind to AtTom22. AtTom22, however, binds to AtTom20 at the same binding site as presequences, suggesting that this domain competes with the presequences of imported proteins, thereby enabling their progression along the import pathway. 相似文献