Ethanol-induced hypothermia. Cross tolerance with morphine

The development of tolerance to ethanol-induced hypothermia and hypnosis, and cross-tolerance with morphine was studied in mice and rats. Ethanol significantly decreased the body temperature in rats (3.0 and 3.2 g/kg) and in mice (3.5 and 4.0 g/kg). Chronic administration of ethanol resulted in the tolerance not only to ethanol hypothermia but also to hypothermic effects of morphine in examined animals. Implantation of morphine pellets caused the development of cross tolerance to ethanol-induced hypothermia in rats but not in mice. The hypnotic effect of ethanol was significantly shorter in chronic alcoholized rats but not in morphine-implanted rats. Neither chronic ethanol administration nor implantation of morphine pellets changed the duration of ethanol-induced hypnosis in mice. These results seem to support the hypothesis on the opiate-like mechanism of ethanol action.     

Extensive variation in synonymous substitution rates in mitochondrial genes of seed plants

Background  

It has long been known that rates of synonymous substitutions are unusually low in mitochondrial genes of flowering and other land plants. Although two dramatic exceptions to this pattern have recently been reported, it is unclear how often major increases in substitution rates occur during plant mitochondrial evolution and what the overall magnitude of substitution rate variation is across plants.     

Isolation and fluorometric determination of homovanillic acid in urine and tissues

The fluorometric method is described for determination of the final product of dopamine metabolism homovanillic acid in urine, amniotic fluid and tissue extracts. The metabolite was isolated using three chromatographic columns (1-Amberlit CG-50, 2-Dowex AG 1 x 2, 8-Aluminium oxide). Oxidation of eluates to emitter was done with potassium ferricyanide in alkalic medium. The use of internal standards made high recovery of compound and a good specificity and sensitivity of detection.     

The antioxidant characteristics of medicinal plant extracts from Western Siberia

An antioxidant activity of the water-alcohol extracts of leaves of ten herbs from Western Siberia was studied. In vivo the capability of extracts to protect cells of Escherichia coli against the bacteriostatic action of H ₂O₂ and the influence of the extracts on the expression of the antioxidant gene katG coding catalase-hydroperoxidase I were investigated. In vitro the radical-binding activity with DPhPG^· (1,1-diphenyl-2-picrylhydrazyl radical), the chelating capability with ferrozine, and total composition of flavonoids and tannins were determined. The extracts of Filipendula stepposa and Limonium gmelinii were characterized by the highest antioxidant activity. According to data, the test extracts could have an antioxidant effect on bacteria in different ways at once including the direct inhibition of ROS (reactive oxygen species), iron ion chelation and antioxidant gene induction.     

Colonization and extinction of land planarians (Platyhelminthes,Tricladida) in a Brazilian Atlantic Forest regrowth remnant

Long-term assessments of species assemblages are valuable tools for detecting species ecological preferences and their dispersal tracks, as well as for assessing the possible effects of alien species on native communities. Here we report a 50-year-long study on population dynamics of the four species of land flatworms (Platyhelminthes, Tricladida, Terricola) that have colonized or become extinct in a 70-year-old Atlantic Forest regrowth remnant through the period 1955–2006. On the one hand, the two initially most abundant species, which are native to the study site, Notogynaphallia ernesti and Geoplana multicolor have declined over decades and at present do not exist in the forest remnant. The extinction of these species is most likely related with their preference for open vegetation areas, which presently do not exist in the forest remnant. On the other hand, the neotropical Geoplaninae 1 and the exotic Endeavouria septemlineata were detected in the forest only very recently. The long-term study allowed us to conclude that Geoplaninae 1 was introduced into the study area, although it is only known from the study site. Endeavouria septemlineata, an active predator of the exotic giant African snail, is originally known from Hawaii. This land flatworm species was observed repeatedly in Brazilian anthropogenic areas, and this is the first report of the species in relatively well preserved native forest, which may be evidence of an ongoing adaptive process. Monitoring of its geographic spread and its ecological role would be a good practice for preventing potential damaging effects, since it also feeds on native mollusk fauna, as we observed in lab conditions. Júlio Pedroni: Granted by CNPQ–Brazil.     

Population dynamics of two small pelagic fish in the central-south area off Chile: delayed density-dependence and biological interaction

It is widely believed that environmental variability is the main cause for fluctuations in commercially exploited small pelagic fish populations around the world. Nevertheless, density-dependent factors also can drive population dynamics. In this paper, we analyzed thirteen years of a relative abundance index of two clupeoids fish populations coexisting in the central-south area off Chile, namely the common sardine, Strangomera bentincki, and anchovy, Engraulis ringens. We applied the classical diagnostic tools of time series analysis to the observed time-series. Also, the realized per capita population growth rate was studied with the aim of detecting the feedback structure that is characterizing the population dynamics of the two species. The analysis suggests that population fluctuations of the two species have an important density-dependent component, displaying first-order (direct density-dependent) and second-order (delayed density-dependent) simultaneously. The density-dependent component explained 70.5 and 55.6 % of the realized per capita population growth rate of common sardine and anchovy, respectively. The deterministic skeleton model showed an asymptotic convergence to equilibrium density. In presence of a stochastic environment, fluctuations were reproduced for the species showing a component of fluctuation with a period of 4 year. The intrinsic dynamics of each species is typical of interacting species resulting from trophic interactions. It is postulated that the second-order dynamics of S. bentincki and E. ringens in central-south Chile, may be the result from interactions with a specialist predator (the fishing fleet), interacting with exogenous environmental factors.