The pre-Columbian dog from Arica,Chile

Burials and mummies of dogs from the Arica, Chile, area are described. It is concluded that these dogs were brought to this area 2500 years ago by shepherds from the highlands and are still present, relatively unchanged.     

Impact of Non-Native Birds on Native Ecosystems: A Global Analysis

Introduction and naturalization of non-native species is one of the most important threats to global biodiversity. Birds have been widely introduced worldwide, but their impacts on populations, communities, and ecosystems have not received as much attention as those of other groups. This work is a global synthesis of the impact of nonnative birds on native ecosystems to determine (1) what groups, impacts, and locations have been best studied; (2) which taxonomic groups and which impacts have greatest effects on ecosystems, (3) how important are bird impacts at the community and ecosystem levels, and (4) what are the known benefits of nonnative birds to natural ecosystems. We conducted an extensive literature search that yielded 148 articles covering 39 species belonging to 18 families -18% of all known naturalized species. Studies were classified according to where they were conducted: Africa, Asia, Australasia, Europe, North America, South America, Islands of the Indian, of the Pacific, and of the Atlantic Ocean. Seven types of impact on native ecosystems were evaluated: competition, disease transmission, chemical, physical, or structural impact on ecosystem, grazing/ herbivory/ browsing, hybridization, predation, and interaction with other non-native species. Hybridization and disease transmission were the most important impacts, affecting the population and community levels. Ecosystem-level impacts, such as structural and chemical impacts were detected. Seven species were found to have positive impacts aside from negative ones. We provide suggestions for future studies focused on mechanisms of impact, regions, and understudied taxonomic groups.     

Medicinal plants of the Argentine Yungas plants of the Las Yungas biosphere reserve, Northwest of Argentina, used in health care

We have compared the species richness of medicinal plants and the differential patterns of use amongst settlements in the Andean communities of Northwest Argentina which have differing levels of isolation. About 259 ethnoespecies, belonging to 74 plant families, were included, representing between 70 and 80% of the total estimate. The results indicate that Coronopus didymus is the most relevant and important species. The method of use of medicinal plants and the ailments treated by rural doctors compared to those of the layperson is different. Native and exotic plants are used differently according to the body system treated. There are some relationships between internal and external use and body systems and recipes. The greater medicinal species richness found in the less isolated locations is due to external enriching cultural influences.     

Cluster analysis of behavioural and event-related potentials during a contingent negative variation paradigm in remitting-relapsing and benign forms of multiple sclerosis

Background  

Event-related potentials (ERPs) may be used as a highly sensitive way of detecting subtle degrees of cognitive dysfunction. On the other hand, impairment of cognitive skills is increasingly recognised as a hallmark of patients suffering from multiple sclerosis (MS). We sought to determine the psychophysiological pattern of information processing among MS patients with the relapsing-remitting form of the disease and low physical disability considered as two subtypes: 'typical relapsing-remitting' (RRMS) and 'benign MS' (BMS). Furthermore, we subjected our data to a cluster analysis to determine whether MS patients and healthy controls could be differentiated in terms of their psychophysiological profile.     

A pertussis toxin-sensitive G-protein mediates some aspects of insulin action in BC3H-1 murine myocytes.

The involvement of G-proteins in the insulin signal transduction system has been studied in detail using the murine BC3H-1 myocyte system. Pertussis toxin (PT) treatment, previously shown to attenuate some of the metabolic effects of insulin in this cell line (Luttrell, L.M., Hewlett, E.L., Romero, G., and Rogol, A.D. (1988) J. Biol. Chem. 263, 6134-6141), abolished insulin-induced generation of diacylglycerol and inositolglycan mediators with no effects on either the autophosphorylation of the insulin receptor or the phosphorylation of the major endogenous substrates for insulin-stimulated tyrosine kinase activity (pp185 and pp42-45). In vitro ADP-ribosylation and immunoblotting studies suggest that the major PT substrate is a 40-kDa protein of the G alpha family. This protein band did not exhibit detectable tyrosine phosphorylation upon stimulation of either intact cells or cell membranes with insulin. In the presence of low concentrations of GTP, insulin treatment of isolated myocyte plasma membranes resulted in a small (30-40%) but significant stimulation of GTP hydrolysis. This effect was best observed in the presence of small concentrations of sodium dodecyl sulfate. The rate of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) binding to BC3H-1 membranes was also significantly increased in the presence of insulin. The effects of insulin on GTP hydrolysis and GTP gamma S binding were found to be dependent on the concentration of insulin. These effects were not detected in plasma membranes prepared from PT-pretreated BC3H-1 myocytes. In contrast, pretreatment with the B (inactive) subunit of PT did not alter the response of myocyte membranes to insulin. High affinity binding of [125I]iodoinsulin to myocyte plasma membranes was reduced by 60-70% in the presence of guanine nucleotides. Similar effects on insulin binding were produced by PT pretreatment of the cells. In contrast, adenine nucleotides had no effect on insulin binding. Scatchard analysis of the binding data showed that the observed effects of guanine nucleotides and PT on insulin binding resulted either from a reduction in the number of high affinity insulin binding sites or from a significant reduction of the affinity of insulin for its receptor. Low affinity binding sites did not appear to be affected by either guanine nucleotides nor PT pretreatment. These results provide substantial evidence suggestive of a noncovalent interaction between the insulin receptor and a regulatory G-protein system during the process of insulin signaling.     

Host Cell Poly(ADP-Ribose) Glycohydrolase Is Crucial for Trypanosoma cruzi Infection Cycle

Trypanosoma cruzi, etiological agent of Chagas’ disease, has a complex life cycle which involves the invasion of mammalian host cells, differentiation and intracellular replication. Here we report the first insights into the biological role of a poly(ADP-ribose) glycohydrolase in a trypanosomatid (TcPARG). In silico analysis of the TcPARG gene pointed out the conservation of key residues involved in the catalytic process and, by Western blot, we demonstrated that it is expressed in a life stage-dependant manner. Indirect immunofluorescence assays and electron microscopy using an anti-TcPARG antibody showed that this enzyme is localized in the nucleus independently of the presence of DNA damage or cell cycle stage. The addition of poly(ADP-ribose) glycohydrolase inhibitors ADP-HPD (adenosine diphosphate (hydroxymethyl) pyrrolidinediol) or DEA (6,9-diamino-2-ethoxyacridine lactate monohydrate) to the culture media, both at a 1 µM concentration, reduced in vitro epimastigote growth by 35% and 37% respectively, when compared to control cultures. We also showed that ADP-HPD 1 µM can lead to an alteration in the progression of the cell cycle in hydroxyurea synchronized cultures of T. cruzi epimastigotes. Outstandingly, here we demonstrate that the lack of poly(ADP-ribose) glycohydrolase activity in Vero and A549 host cells, achieved by chemical inhibition or iRNA, produces the reduction of the percentage of infected cells as well as the number of amastigotes per cell and trypomastigotes released, leading to a nearly complete abrogation of the infection process. We conclude that both, T. cruzi and the host, poly(ADP-ribose) glycohydrolase activities are important players in the life cycle of Trypanosoma cruzi, emerging as a promising therapeutic target for the treatment of Chagas’ disease.     

Photosynthetic electron transport interaction of xanthorrhizol isolated from Iostephane heterophylla and its derivatives

A bioactivity-guided chemical study of Iostephane heterophylla (Asteraceae) led to the isolation of xanthorrhizol (1) as the compound that causes inhibition of ATP synthesis, H⁺-uptake and electron flow from water to methylviologen (basal, phosphorylating and uncoupled) in freshly lysed spinach chloroplasts, thus acting as an inhibitor of the Hill reaction. Acetyl (2), dihydro (3) and acetyl-dihydro (4) derivatives were synthesized. It was found that 4 was less active than 1 and 2 in ATP synthesis, whereas 3 was the most potent inhibitor of the Hill reaction and was also an inhibitor of H⁺-ATPase. Studies of the photosynthetic partial redox reactions from PQ to MV indicated that 1 partially inhibited the PQ pool, but that 3 did not. However, both inhibited the uncoupled electron transport in PSII from water to DCBQ. Uncoupled electron flow from water to silicomolybdate was completely inhibited by 3 and partially by 1. The reaction from DPC to DCPIP was inhibited by both 1 and 3. These results indicate that the inhibition site is located within PSII for 1 and 3 as was corroborated by fluorescence decay data.