SCAPER, a novel cyclin A-interacting protein that regulates cell cycle progression

Cyclin A/Cdk2 plays an important role during S and G2/M phases of the eukaryotic cell cycle, but the mechanisms by which it regulates cell cycle events are not fully understood. We have biochemically purified and identified SCAPER, a novel protein that specifically interacts with cyclin A/Cdk2 in vivo. Its expression is cell cycle independent, and it associates with cyclin A/Cdk2 at multiple phases of the cell cycle. SCAPER localizes primarily to the endoplasmic reticulum. Ectopic expression of SCAPER sequesters cyclin A from the nucleus and results specifically in an accumulation of cells in M phase of the cell cycle. RNAi-mediated depletion of SCAPER decreases the cytoplasmic pool of cyclin A and delays the G1/S phase transition upon cell cycle re-entry from quiescence. We propose that SCAPER represents a novel cyclin A/Cdk2 regulatory protein that transiently maintains this kinase in the cytoplasm. SCAPER could play a role in distinguishing S phase- from M phase-specific functions of cyclin A/Cdk2.     

Extracellular proteolytic activity and molecular analysis of Microsporum canis strains isolated from symptomatic and asymptomatic cats

Microsporum canis is the main zoophylic dermatophyte in dogs and cats, and it is also an important zoonotic agent. The literature showed that cats are asymptomatic carriers of M. canis. This is apparently due to host resistance and/or the presence of strains with lower virulence. This study was aimed to evaluate the keratinolytic, elastinolytic and collagenolytic activities of M. canis strains and their relationship with symptomatic and asymptomatic cats. In addition, these strains were analysed by RFLP. The strains isolated from cats with clinical dermatophytosis had higher keratinase and elastase activity than those isolated from asymptomatic animals (p minus than 0.05). There were not differences in RFLP patterns based on Hind III digestion.     

Antithrombotic activity of kininogen is mediated by inhibitory effects of domain 3 during arterial injury in vivo

High-molecular-weight kininogen (HK) and its domain 3 (D3) exhibit anticoagulant properties and inhibit platelet activation at low thrombin concentration in vitro. We hypothesized that the rapid occlusive thrombosis in HK-deficient (HKd) rats following endothelial injury of the aorta results from enhanced platelet aggregation by thrombin. The effects of D3 (G235-M357) or D3-derived peptides on thrombosis in vivo were tested. D3 and its exon 7C terminal peptide (E7CP, K270-Q292), expressed as glutathione S-transferase (GST) fusion proteins (GST-D3, GST-E7CP), or GST alone, as well as cleaved HK (HKa) or synthetic peptide E7CP, were infused intravenously 10 min before endothelial injury. Blood flow was reduced down to 10% of baseline flow within 28 +/- 5.2 min by a platelet-fibrin thrombus in GST-treated HKd rats compared with >240 min in GST-treated normal HK rats (wild type). GST-D3, GST-E7CP, HKa, or E7CP infusion prolonged the flow time to 233, >240, 223, and >240 min, respectively, in HKd rats. When GST-E7CP was infused 10 min after the injury, blood flow was maintained for >240 min. Thrombin-antithrombin concentrations were elevated by injury in HKd rats receiving GST from 35 to 55 microg/l and decreased with GST-E7CP, HKa, or E7CP reconstitution to 40, 15, and 9 microg/l, respectively. We conclude that HKd rats are prothrombotic and that HKa, kininogen D3, and its fragment E7CP modulate arterial thrombosis after endothelial injury.     

Plant Growth Regulators and Induction of Leaf Senescence in Nitrogen-Deprived Wheat Plants

The sequence of events and the signals that regulate the remobilization of nitrogen (N) reserves during senescence induced by N starvation were studied in leaf 3, the last fully expanded leaf, in 17-day-old wheat (Triticum aestivum L.) plants. The first event observed was a rapid decrease in the isopentenyl adenosine (iPA) concentration during the first 24 h of N starvation. No differences in t-zeatin riboside and dihydrozeatin riboside concentrations were observed until the end of the assay. During the following 6 days, a decrease in soluble amino acids, chlorophyll, and protein, as well as an increase in soluble sugar concentration and endoproteolytic activity, could be observed. At day 3 of the experiment, the abscisic acid (ABA) concentration in the leaves of N-deprived plants started to increase. After 6 days of N deprivation there was a rise in oxidative stress, as indicated by the increase in malondialdehyde concentration, as well as a decrease in the activities of antioxidant enzymes catalase and ascorbate peroxidase. To analyze interactions with leaf development, the first, second, third, and fourth leaves were studied. iPA concentration decreased in all the leaf stages, including leaf 4, which was not fully expanded. A linear correlation between iPA and protein concentration was determined. These results suggest that the sharp fall in iPA could be the earliest event that induces protein degradation during the development of senescence induced by N deficiency, and that only later is ABA accumulated and oxidative stress developed.     

Effect of Leishmania spp infection on the survival,life expectancy,fecundity and fertility of Lutzomyia longipalpis s.l. and Lutzomyia pseudolongipalpis

We evaluated the effects of Leishmania spp infection on several population parameters of Lutzomyia longipalpis sensu lato andLutzomyia pseudolongipalpis, vectors of visceral leishmaniasis in Venezuela, under experimental conditions during the first post-feeding period. Females of both species were allowed to feed and engorge on a suspension of fresh washed human red blood cells in foetal calf serum. These blood cells were either non-infected or infected with one of the fourLeishmania spp strains and were offered through a chicken skin membrane. The longevity, life expectancy and the fecundity of uninfected flies were similar in both species, but the fertility was significantly lower in uninfected Lu. longipalpis females. In all cases, the infection of Lu. longipalpis and Lu. pseudolongipalpis by the Leishmania strains resulted in significant detrimental effects, which exerted a fitness cost expressed by reduced survival and life expectancy, as well as decreased fertility and fecundity compared with the control groups. Nevertheless, differences in these parameters were observed between these vector species depending on whether they were infected with the autochthonous Venezuelan Leishmania infantum strain (NESA) or the Brazilian reference strain (PP75). The experimental data obtained agree with field data on the natural infection of these vector species and the significance of this scenario is discussed.     

A new species of Hyalella (Crustacea,Amphipoda, Dogielinotidae) from the Atlantic Forest of Misiones,Argentina

The freshwater genus Hyalella Smith, 1874 has a distribution restricted to the Western Hemisphere with most species being found in South America. In this report we describe a new species of Hyalella from the Atlantic Forest of the Misiones province, Argentina.     

Nuclear factor erythroid 2-related factor-2 activity controls 4-hydroxynonenal metabolism and activity in prostate cancer cells

4-Hydroxynonenal (HNE) is an end product of lipoperoxidation with antiproliferative and proapoptotic properties in various tumors. Here we report a greater sensitivity to HNE in PC3 and LNCaP cells compared to DU145 cells. In contrast to PC3 and LNCaP cells, HNE-treated DU145 cells showed a smaller reduction in growth and did not undergo apoptosis. In DU145 cells, HNE did not induce ROS production and DNA damage and generated a lower amount of HNE-protein adducts. DU145 cells had a greater GSH and GST A4 content and GSH/GST-mediated HNE detoxification. Nuclear factor erythroid 2-related factor-2 (Nrf2) is a regulator of the antioxidant response. Nrf2 protein content and nuclear accumulation were higher in DU145 cells compared to PC3 and LNCaP cells, whereas the expression of KEAP1, the main negative regulator of Nrf2 activity, was lower. Inhibition of Nrf2 expression with specific siRNA resulted in a reduction in GST A4 expression and GS-HNE formation, indicating that Nrf2 controls HNE metabolism. In addition, Nrf2 knockdown sensitized DU145 cells to HNE-mediated antiproliferative and proapoptotic activity. In conclusion, we demonstrated that increased Nrf2 activity resulted in a reduction in HNE sensitivity in prostate cancer cells, suggesting a potential mechanism of resistance to pro-oxidant therapy.     

Human plasma glycome in attention-deficit hyperactivity disorder and autism spectrum disorders

Over a half of all proteins are glycosylated, and their proper glycosylation is essential for normal function. Unfortunately, because of structural complexity of nonlinear branched glycans and the absence of genetic template for their synthesis, the knowledge about glycans is lagging significantly behind the knowledge about proteins or DNA. Using a recently developed quantitative high throughput glycan analysis method we quantified components of the plasma N-glycome in 99 children with attention-deficit hyperactivity disorder (ADHD), 81 child and 5 adults with autism spectrum disorder, and a total of 340 matching healthy controls. No changes in plasma glycome were found to associate with autism spectrum disorder, but several highly significant associations were observed with ADHD. Further structural analysis of plasma glycans revealed that ADHD is associated with increased antennary fucosylation of biantennary glycans and decreased levels of some complex glycans with three or four antennas. The design of this study prevented any functional conclusions about the observed associations, but specific differences in glycosylation appears to be strongly associated with ADHD and warrants further studies in this direction.