Endogenous purine metabolism in the conidia of wild type and certain adenine mutants of neurospora crassa I. The nature of the reserve pools and pool utilization during adenine starvation

Conidia of four adenine auxotrophs (ad 9, ad 3B, ad 8 and ad 4 of Neurospora crassa differ in their ability to germinate on adenine-deficient medium. A large percentage of the ad 9 and ad 3B mutant conidia germinate while those of ad 8 and ad 4 mutant do not. No correlation was found between the size of the conidial purine reserves and the conidial ability to germinate. In all the strains the major fraction of the conidial purine reserved pools was inosine. The ad 8 and ad 4 mutants are blocked after IMP formation in the adenine biosynthetic pathway and therefore cannot use the stored inosine for germination. Pool-utilization studies indicated that in all strains investigated some of the purine reserved were lost from the conidia during incubation. In the most readily germinating strain, ad 9, only small amounts of the purine pool were lost from the conidia and a large portion of the reserve pool was used for nucleic acid synthesis. The nature of the purine reserves present in the conidia, and the ability of the strains to prevent loss of the stored purines from the conidia appear to be among the factors influencing the conidial germination of the adenine mutants of N. crassa.     

A feline large granular lymphoma and its derived cell line

Summary A lymphoma cell line (MCC) was derived from an abdominal mass from a 13-yr-old castrated male cat. The cells resemble natural killer precursor cells, have membrane-bound granules, and are positive for chloroacetate esterase, α-naphthyl butyrate esterase, and tartrate-resistant acid phosphatase activities. The MCC cells are negative for rearranged feline T-cell receptor genes, negative for feline T-cytotoxic antigen, Ia, and surface μ, τ, and lambda chains and do not form E-rosettes. The MCC cell line is negative for the feline leukemia virus (FeLV); e.g., negative for exogenous FeLV (exU3) sequences, negative for cytoplasmic and surface FeLV major core protein of 27 000 daltons (p27) by indirect, immunofluorescence assay, negative for helper FeLV by clone 81 assay, and negative for release of soluble FeLV p27 by enzyme-linked immunosorbent assay. Electron microscopy reveals budding type C retrovirus particles and MCC cells react with anti-RD-114 (anti-endogenous feline retrovirus) reference serum. After in vitro infection, MCC replicate FeLV readily, but replication is noncytopathic. This project has been funded, at least in part, with funds from the U.S. Department of Health and Human services under grants AI 25722, DK41939, and CA 35742 and contract AI-62525.     

The rise to dominance of the angiosperm kingdom: dispersal,habitat widening and evolution during the Late Cretaceous of Europe

Coiffard, C. & Gomez, B. 2009: The rise to dominance of the angiosperm kingdom: dispersal, habitat widening and evolution during the Late Cretaceous of Europe. Lethaia, Vol. 43, pp. 164–169. The earliest fossil records of angiosperms in Europe occur in the Barremian and consist of freshwater wetland plants. From the Barremian onwards, angiosperms show a stepwise widening of their ecological range with the result that they inhabited most environments by the Cenomanian. Nevertheless, most angiosperms had still restricted habitats, while a few angiosperm trees were confined to disturbed environments, such as channel margins. A Wagner’s Parsimony Method analysis performed on a fossil plant and locality database from the Turonian to the Campanian of Europe indicates continued decrease in richness of ferns and gymnosperms compared with angiosperms, turnover between conifer and palm trees in freshwater‐related swamps at about the Cenomanian/Turonian boundary, and spreading of angiosperm trees through the floodplains. The ecological range of angiosperm trees was increased, being recorded in channel margins from the Cenomanian and spreading over floodplains (e.g. Platanaceae) and swamps (e.g. Arecaceae) by the Campanian. These new ecological ranges and successions went with innovative architectures, such as dicot trees and palm trees. Most living core angiosperm families had their earliest representatives in the Late Cretaceous, which should be considered as the dawn of modern angiosperm forests. □Core angiosperms, Europe, Late Cretaceous, palms, Wagner’s Parsimony Method.     

A benefit-finding intervention for family caregivers of persons with Alzheimer disease: study protocol of a randomized controlled trial

Background

Patients with ST-elevation myocardial infarction (STEMI) not treated with primary or rescue percutaneous coronary intervention (PCI) are at risk for recurrent ischemia, especially when viability in the infarct-area is present. Therefore, an invasive strategy with PCI of the infarct-related coronary artery in patients with viability would reduce the occurrence of a composite end point of death, reinfarction, or unstable angina (UA).

Methods

Patients admitted with an (sub)acute myocardial infarction, who were not treated by primary or rescue PCI, and who were stable during the first 48 hours after the acute event, were screened for the study. Eventually, we randomly assigned 216 patients with viability (demonstrated with low-dose dobutamine echocardiography) to an invasive or a conservative strategy. In the invasive strategy stenting of the infarct-related coronary artery was intended with abciximab as adjunct treatment. Seventy-five (75) patients without viability served as registry group. The primary endpoint was the composite of death from any cause, recurrent myocardial infarction (MI) and unstable angina at one year. As secondary endpoint the need for (repeat) revascularization procedures and anginal status were recorded.

Results

The primary combined endpoint of death, recurrent MI and unstable angina was 7.5% (8/106) in the invasive group and 17.3% (19/110) in the conservative group (Hazard ratio 0.42; 95% confidence interval [CI] 0.18-0.96; p = 0.032). During follow up revascularization-procedures were performed in 6.6% (7/106) in the invasive group and 31.8% (35/110) in the conservative group (Hazard ratio 0.18; 95% CI 0.13-0.43; p < 0.0001). A low rate of recurrent ischemia was found in the non-viable group (5.4%) in comparison to the viable-conservative group (14.5%). (Hazard-ratio 0.35; 95% CI 0.17-1.00; p = 0.051).

Conclusion

We demonstrated that after acute MI (treated with thrombolysis or without reperfusion therapy) patients with viability in the infarct-area benefit from a strategy of early in-hospital stenting of the infarct-related coronary artery. This treatment results in a long-term uneventful clinical course. The study confirmed the low risk of recurrent ischemia in patients without viability.

Trial registration

ClinicalTrials.gov: NCT00149591.     

Augmentation of cocaine hyperactivity in rats by systemic ghrelin

The feeding-relevant pathway by which food deprivation (FD) augments cocaine action is unknown. Systemic administration of the 28 amino acid acylated peptide ghrelin (1-10 nmol) increases food intake in rats and circulating levels of rat ghrelin are up-regulated by FD. The present experiment examined the impact of ghrelin or vehicle pretreatment on the locomotion and stereotypy induced by systemic cocaine hydrochloride. Male Sprague-Dawley rats were pretreated at -60 min with 0 or 5 nmol rat ghrelin (IP) and then injected (IP) at time 0 with 0, 2.5, 5.0, or 10.0 mg/kg cocaine. Locomotor activity was monitored over a 45-min post-cocaine period. Rats received the same ghrelin dose, but a different cocaine dose (in random order) on each of the four drug trials, with each drug trial separated by at least 2 days. Administration of 5 nmol ghrelin-0 mg/kg cocaine slightly increased locomotion relative to that of 0 nmol ghrelin-0 mg/kg cocaine. Cocaine increased locomotion as a function of dose in the 0 nmol ghrelin group, but the effect of cocaine was even greater when preceded by 5 nmol ghrelin. These results indicate that acute injection of ghrelin, at a feeding-relevant dose, augments the acute effects of cocaine on locomotion in rats.     

Comparison of marker types and map assumptions using Markov chain Monte Carlo-based linkage analysis of COGA data

We performed multipoint linkage analysis of the electrophysiological trait ECB21 on chromosome 4 in the full pedigrees provided by the Collaborative Study on the Genetics of Alcoholism (COGA). Three Markov chain Monte Carlo (MCMC)-based approaches were applied to the provided and re-estimated genetic maps and to five different marker panels consisting of microsatellite (STRP) and/or SNP markers at various densities. We found evidence of linkage near the GABRB1 STRP using all methods, maps, and marker panels. Difficulties encountered with SNP panels included convergence problems and demanding computations.     

Analysis of Aβ (1-40) and Aβ (1-42) monomer and fibrils by capillary electrophoresis

A method based on capillary electrophoresis (CE) with UV absorbance detection is presented to characterize synthetic amyloid beta (Aβ) peptide preparations at different aggregation states. Aggregation of Aβ (1-40) and Aβ (1-42) is closely linked to Alzheimer's disease (AD), and studying how Aβ peptides self-assemble to form aggregates is the focus of intense research. Developing methods capable of identifying, characterizing and quantifying a wide range of Aβ species from monomers to fully formed fibrils is critical for AD research and is a major analytical challenge. Monomer and fibril samples of Aβ (1-40) and Aβ (1-42) were prepared and characterized for this study. The monomer-equivalent concentration for each sample was determined by HPLC-UV, and aggregate formation was confirmed and characterized by transmission electron microscopy. The same samples were studied using CE with UV absorbance detection. Analysis by mass spectrometry of collected CE fractions was used to confirm the presence of Aβ for some CE-UV peaks. The CE-UV method reported here clearly indicates that monomeric and aggregated Aβ were electrophoretically separated, and substantial differences in the electrophoretic profiles between samples of Aβ (1-40) and Aβ (1-42) were observed. This CE-UV method can differentiate between Aβ monomer, oligomeric intermediates, and mature fibrils.     

Nature of 6-methylpurine inhibition and characterization of two 6-methylpurine-resistant mutants of Neurospora crassa.

6-Methylpurine, an analog of adenine, inhibits the growth of Neurospora crassa. From kinetic studies it was found that 6-methylpurine is converted to its nucleotide form by adenine phosphoribosyltransferase (EC 2.4.2.7), and inhibits the de novo purine biosynthesis. Adenine relieves the growth inhibition caused by 6-methylpurine, whereas hypoxanthine is not very effective. Studies dealing with hypoxanthine utilization in the presence of 6-methylpurine indicated a severely reduced uptake of hypoxanthine and a general slowdown in its further metabolism. Two mutants (Mepr-3 and Mepr-10) which are resistant to 6-methylpurine were characterized. Studies of purine base uptake and the in vivo and in vitro conversion to nucleotides indicated that Mepr-10 may be an adenine phosphoribosyltransferase-defective mutant, whereas Mepr-3 may be a mutant with altered feedback response to 6-methylpurine. Both mutants showed a severely lowered hypoxanthine phosphoribosyltransferase activity, but because 6-methylpurine did not have any effect on the conversion of hypoxanthine to IMP in the wild type, it was concluded that 6-methylpurine resistance in these mutants cannot be due to lowered hypoxanthine phosphoribosyltransferase activity, but rather that the lowering of enzyme activity may be a secondary effect.     

Permeability changes in membranes of Neurospora crassa after freezing and thawing.

Conidia of Neurospora crassa which are in different physiological states show different rates of survival after freezing and thawing. [¹⁴C]adenine uptake by frozen and thawed conidia in different physiological states show a correlation with their survival. The uptake method was extended to study the survival of mycelium in log phase and stationary phase. From the uptake data it appears that log phase mycelium is extremely sensitive to all rates of freezing and thawing studied, while the stationary phase mycelium showed slight tolerance to freezing, if freezing was done at a slow rate. A study of the efflux of labeled compounds from the conidia in various physiological states or from the mycelia after freezing and thawing showed that, although efflux followed the same general trend as survival in conidia, it did not relate to the survival in mycelium, suggesting that the death of conidia or mycelium in the freeze-thaw treatments is not due to efflux of compounds.     

Dendritic reorganization in pyramidal neurons in medial prefrontal cortex after chronic corticosterone administration

Chronic stress produces deficits in cognition accompanied by alterations in neural chemistry and morphology. For example, both stress and chronic administration of corticosterone produce dendritic atrophy in hippocampal neurons (Woolley C, Gould E, McEwen BS. 1990. Exposure to excess glucocorticoids alters dendritic morphology of adult hippocampal pyramidal neurons. Brain Res 531:225–231; Watanabe Y, Gould E, McEwen BS, 1992b. Stress induces atrophy of apical dendrites of hippocampal CA3 pyramidal neurons. Brain Res 588:341–345). Prefrontal cortex is also a target for glucocorticoids involved in the stress response (Meaney MJ, Aitken DH. 1985. [³H]Dexamethasone binding in rat frontal cortex. Brain Res 328:176–180); it shows neurochemical changes in response to stress (e.g., Luine VN, Spencer RL, McEwen BS. 1993. Effect of chronic corticosterone ingestion on spatial memory performance and hippocampal serotonergic function. Brain Res 616:55–70; Crayton JW, Joshi I, Gulati A, Arora RC, Wolf WA. 1996. Effect of corticosterone on serotonin and catecholamine receptors and uptake sites in rat frontal cortex. Brain Res 728:260–262; Takao K, Nagatani T, Kitamura Y, Yamawaki S. 1997. Effects of corticosterone on 5‐HT_1A and 5‐HT₂ receptor binding and on the receptor‐mediated behavioral responses of rats. Eur J Pharmacol 333:123–128; Sandi C, Loscertales M. 1999. Opposite effects on NCAM expression in the rat frontal cortex induced by acute vs. chronic corticosterone treatments. Brain Res 828:127–134), and mediates many of the behaviors that are altered by chronic corticosterone administration (e.g., Lyons DM, Lopez JM, Yang C, Schatzberg AF. 2000. Stress‐level cortisol treatment impairs inhibitory control of behavior in monkeys. J Neurosci 20:7816–7821). To determine if glucocorticoid‐induced morphological changes also occur in medial prefrontal cortex, the effects of chronic corticosterone administration on dendritic morphology in this corticolimbic structure were assessed. Adult male rats received s.c. injections of either corticosterone (10 mg in 250 μL sesame oil; n = 8) or vehicle (250 μL; n = 8) daily for 3 weeks. A third group of rats served as intact controls (n = 4). Brains were stained using a Golgi‐Cox procedure and pyramidal neurons in layer II‐III of medial prefrontal cortex were drawn; dendritic morphology was quantified in three dimensions. Sholl analyses demonstrated a significant redistribution of apical dendrites in corticosterone‐treated animals: the amount of dendritic material proximal to the soma was increased relative to intact rats, while distal dendritic material was decreased relative to intact animals. Thus, chronic glucocorticoid administration dramatically reorganized apical arbors in medial prefrontal cortex. This reorganization likely reflects functional changes and may contribute to stress‐induced changes in cognition. © 2001 John Wiley & Sons, Inc. J Neurobiol 49: 245–253, 2001