Attenuation of estradiol on the reduction of striatal dopamine by amphetamine in ovariectomized rats

Amphetamine (AMPH) is a highly addictive drug of abuse which exhibits toxicity to dopaminergic neurons in long‐term abusers. Estrogen seems to show neuroprotection in dopamine (DA) deficit caused by AMPH. The present study was to investigate the effects of estradiol on the levels of striatal DA in ovariectomized (Ovx) rats treated with or without AMPH. Female rats were Ovx for 2 weeks before administration of AMPH (5 mg/kg/day, i.p.) with or without 17β‐estradiol benzoate (EB) (25 µg/kg/day, s.c.) for 7 days. The striatal tissues were collected, homogenized with DA mobile phase, and centrifuged. The concentrations of DA in the supernatants were detected by HPLC. The protein expressions of dopamine transporter (DAT), vesicular monoamine transporter 2 (VMAT‐2), and tyrosine hydroxylase (TH) were analyzed by Western blotting. The results indicated that AMPH could attenuate DA level significantly in striatum (P < 0.01). Comparing to control groups, administration of either EB or EB plus AMPH increased DA level (P < 0.01). The protein expression of striatal DAT was significant greater (P < 0.01) in rats treated with AMPH plus EB than AMPH treated animals. These results suggest that the DA levels in striatum can be enhanced by EB via an increase of DAT expression following administration of AMPH. J. Cell. Biochem. 108: 1318–1324, 2009. © 2009 Wiley‐Liss, Inc.     

Diversity and distribution of fungal foliar endophytes in New Zealand Podocarpaceae

The diversity and distribution of fungal endophytes in the leaves of four podocarps (Dacrydium cupressinum, Prumnopitys ferruginea, Dacrycarpus dacrydioides, and Podocarpus totara, all Podocarpaceae) and an angiosperm (Kunzea ericoides, Myrtaceae) occurring in close stands were studied. The effects of host species, locality, and season on endophyte assemblages were investigated. Host species was the major factor shaping endophyte assemblages. The spatial separation of sites and seasonal differences played significant but lesser roles. The mycobiota of each host species included both generalist and largely host-specialised fungi. The host-specialists were often observed at low frequencies on some of the other hosts. There was no clear evidence for family-level specialisation across the Podocarpaceae. Of the 17 species found at similar frequencies on several of the podocarp species, 15 were found also on Kunzea. Many of the endophytes isolated appear to represent species of fungi not previously recognised from New Zealand.     

Mitochondrial DNA regionalism and historical demography in the extant populations of Chirocephalus kerkyrensis (Branchiopoda: Anostraca)

Background

Mediterranean temporary water bodies are important reservoirs of biodiversity and host a unique assemblage of diapausing aquatic invertebrates. These environments are currently vanishing because of increasing human pressure. Chirocephalus kerkyrensis is a fairy shrimp typical of temporary water bodies in Mediterranean plain forests and has undergone a substantial decline in number of populations in recent years due to habitat loss. We assessed patterns of genetic connectivity and phylogeographic history in the seven extant populations of the species from Albania, Corfu Is. (Greece), Southern and Central Italy.

Methodology/Principal Findings

We analyzed sequence variation at two mitochondrial DNA genes (Cytochrome Oxidase I and 16s rRNA) in all the known populations of C. kerkyrensis. We used multiple phylogenetic, phylogeographic and coalescence-based approaches to assess connectivity and historical demography across the whole distribution range of the species. C. kerkyrensis is genetically subdivided into three main mitochondrial lineages; two of them are geographically localized (Corfu Is. and Central Italy) and one encompasses a wide geographic area (Albania and Southern Italy). Most of the detected genetic variation (≈81%) is apportioned among the aforementioned lineages.

Conclusions/Significance

Multiple analyses of mismatch distributions consistently supported both past demographic and spatial expansions with the former predating the latter; demographic expansions were consistently placed during interglacial warm phases of the Pleistocene while spatial expansions were restricted to cold periods. Coalescence methods revealed a scenario of past isolation with low levels of gene flow in line with what is already known for other co-distributed fairy shrimps and suggest drift as the prevailing force in promoting local divergence. We recommend that these evolutionary trajectories should be taken in proper consideration in any effort aimed at protecting Mediterranean temporary water bodies.     

Effects of tenuiorin and methyl orsellinate from the lichen Peltigera leucophlebia on 5-/15-lipoxygenases and proliferation of malignant cell lines in vitro.

The orcinol derivatives tenuiorin (1) and methyl orsellinate (2) were identified as active components of an extract from the lichen Peltigera leucophlebia (Nyl.) Gyeln. showing in vitro inhibitory activity against 15-lipoxygenase from soybeans. The compounds were subsequently tested for in vitro activity against 5-lipoxygenase from porcine leucocytes and proved to be moderately active, with IC50 values of 41.6 microM and 59.6 microM respectively. Tenuiorin is a known constituent of several Peltigera species but has not previously been isolated from P. leucophlebia. As correlation between 5-lipoxygenase inhibition and antiproliferative effects has earlier been witnessed for related lichen metabolites, tenuiorin and methyl orsellinate were further tested for antiproliferative activity on cultured human breast (T-47D)-, pancreatic (PANC-1)- and colon (WIDR) cancer cell lines. The monomeric methyl orsellinate exhibited no detectable antiproliferative activity whereas the trimeric tenuiorin caused moderate/weak reduction in [3H]-thymidine uptake of the pancreatic- and colon cancer cells, with ED50 values of 87.9 and 98.3 microM respectively.     

Conformational changes in SP-B as a function of surface pressure

X-ray reflectivity of bovine and sheep surfactant-associated protein B (SP-B) monolayers is used in conjunction with pressure-area isotherms and protein models to suggest that the protein undergoes changes in its tertiary structure at the air/water interface under the influence of surface pressure, indicating the likely importance of such changes to the phenomena of protein squeeze out as well as lipid exchange between the air-water interface and subphase structures. We describe an algorithm based on the well-established box- or layer-models that greatly assists the fitting of such unknown scattering-length density profiles, and which takes the available instrumental resolution into account. Scattering-length density profiles from neutron reflectivity of bovine SP-B monolayers on aqueous subphases are shown to be consistent with the exchange of a large number of labile protons as well as the inclusion of a significant amount of water, which is partly squeezed out of the protein monolayer at elevated surface pressures.     

Myocardial fibrosis blunts nitric oxide synthase-related preload reserve in human dilated cardiomyopathy

It is clear that ischemia inhibits successful defibrillation by altering regional electro-physiology. However, the exact mechanisms are unclear. This study investigated whether regional gap junction inhibition increases biphasic shock defibrillation thresholds (DFT). Sixteen swine were instrumented with a mid-left anterior descending (LAD) perfusion catheter for regional infusion of 0.5 mM/h heptanol (n = 8) or saline (n = 8). DFT values and effective refractory periods (ERP) at five myocardial sites were determined. Regional conduction velocity (CV) was determined in an LAD drug-perfused and nondrug-perfused region in an additional seven swine. Regional heptanol infusion increased 50% DFT values by 33% (P = 0.01) and slowed CV by 42-59% (P < 0.01) but did not affect ERP. Regional heptanol also increased CV dispersion by approximately 270% (P < 0.05) but did not change ERP dispersion. Regional placebo did not alter any of these parameters. Furthermore, regional heptanol infusion induced spontaneous ventricular fibrillation in eight of eight animals. Increasing spatial conduction velocity dispersion by impairing regional gap junction conductance increased DFT values. Dispersion in conduction velocity slowing during regional ischemia may be an important determinant of defibrillation efficacy.     

Inteins as enzymes.

The term "self-catalyzed" as applied to protein processing reactions might be considered a contradiction, since catalysis implies that the catalyst is regenerated without change. However, as our understanding of protein autoprocessing reactions such as protein splicing advances, it is becoming clear that they have many of the hallmarks of enzymatic reactions. In this review, we will examine the properties of protein splicing elements, or inteins, and show how these can be understood in terms of enzyme catalysis, both with respect to substrate specificity and the stabilization of reactive intermediates.     

Effects of juice from Morinda citrifolia (Noni) on gastric emptying in male rats

The effects of juice from Morinda citrifolia (noni) on gastric emptying, gastrointestinal transit, and plasma level of cholecystokinin (CCK) in rats were studied. Male rats were given noni by gavage at levels of 0.25, 1, or 4 ml/kg once per day for one or 7 days. The rats in the control group were given water, while the rats in the experimental group were fasted overnight before measurement of gastrointestinal motility. Gastrointestinal motility was assessed in rats 15 min after intragastric instillation of a test meal containing charcoal (10%) and Na251CrO4 (0.5 microCi/ml). Gastric emptying was determined by measuring the amount of radiolabeled chromium contained in the small intestine as a percentage of the initial amount received. Then, gastrointestinal transit was evaluated by calculating the geometric center of distribution of the radiolabeled marker. Finally, blood samples were collected for measurement of CCK by radioimmunoassay. The administration of noni at 0.25 ml/kg, but not at 1 ml/kg and 4 ml/kg, for 1 day significantly inhibited gastric emptying. In contrast, gastric emptying was significantly inhibited by oral noni (0.25, 1, or 4 ml/kg) for 7 days. Intraperitoneal injection of lorglumide (5 or 10 mg/kg), a selective CCK1 receptor antagonist, effectively attenuated the noni-induced inhibition of gastric emptying. The intestinal transit and body weight, food intake, water intake, urine volume as well as feces weight were not altered by the administration of noni either acutely or chronically, but the administration of oral noni (1 ml/kg) for 7 days increased the level of plasma CCK in male rats. These results suggest that oral noni inhibits gastric emptying in male rats via a mechanism involving stimulation of CCK secretion and CCK1 receptor activation.     

RNA stem-loop enhanced expression of previously non-expressible genes

The key step in bacterial translation is formation of the pre-initiation complex. This requires initial contacts between mRNA, fMet-tRNA and the 30S subunit of the ribosome, steps that limit the initiation of translation. Here we report a method for improving translational initiation, which allows expression of several previously non-expressible genes. This method has potential applications in heterologous protein synthesis and high-throughput expression systems. We introduced a synthetic RNA stem-loop (stem length, 7 bp; DeltaG(0) = -9.9 kcal/mol) in front of various gene sequences. In each case, the stem-loop was inserted 15 nt downstream from the start codon. Insertion of the stem-loop allowed in vitro expression of five previously non-expressible genes and enhanced the expression of all other genes investigated. Analysis of the RNA structure proved that the stem-loop was formed in vitro, and demonstrated that stabilization of the ribosome binding site is due to stem-loop introduction. By theoretical RNA structure analysis we showed that the inserted RNA stem-loop suppresses long-range interactions between the translation initiation domain and gene-specific mRNA sequences. Thus the inserted RNA stem-loop supports the formation of a separate translational initiation domain, which is more accessible to ribosome binding.