Anaerobic co-digestion of olive mill wastewater with olive mill solid waste in a tubular digester at mesophilic temperature

Anaerobic co-digestion is a well established process for treating many types of organic wastes, both solid and liquid. In this study we have investigated, on a laboratory scale, the anaerobic co-digestion of olive mill wastewater (OMW) with olive mill solid waste (OMSW) using semi-continuous, feeding, tubular digesters operated at mesophilic temperatures. Each digester was fed with an influent, composed of OMW and OMSW, at an organic loading rate (OLR) varying between 0.67 and 6.67 g COD/l/d. The hydraulic retention times (HRT) were 12, 24 and 36 days. The TCOD concentrations of OMW used as the main substrate were 24, 56 and 80 g COD/l; the amount of the dry OMSW used as a co-substrate was fixed to approximately 56 g/l of OMW. The results indicated that the best methane production was about 0.95 l/l/day obtained at an OLR = 4.67 g COD/l/d, corresponding to influent TCOD = 56 g COD/l at an HRT = 12d. In contrast, the maximum TCOD removal efficiency (89%) was achieved at an OLR = 0.67 g COD/l/d, corresponding to influent TCOD = 24 g COD/l at an HRT = 36 d. Moreover, the inhibition of biogas production was observed at the highest OLR studied.     

Trichinella spiralis: strong antibody response to a 49 kDa newborn larva antigen in infected rats

In this work, we analyzed the kinetics of anti-Trichinella spiralis newborn larva (NBL) antibodies (Ab) and the antigenic recognition pattern of NBL proteins and its dose effects. Wistar rats were infected with 0, 700, 2000, 4000 and 8000 muscle larvae (ML) and bled at different time intervals up to day 31 post infection (p.i.). Ab production was higher with 2000 ML dose and decreased with 8000, 4000 and 700 ML. Abs were not detected until day 10, peaked on day 14 for the 2000 ML dose and on day 19 for the other doses and thereafter declined slowly from 19 to 31 days p.i. In contrast, Abs to ML increased from day 10, peaked on day 19 and remained high until the end of the study. Abs bound strongly at least to three NBL components of 188, 205 and 49 kDa. NBL antigen of 188 and 205 kDa were recognized 10-26 days p.i. and that of 49 kDa from day 10 to day 31 p.i. A weak recognition towards antigens of 52, 54, 62 and 83 kDa was also observed during the infection. An early recognition of 31, 43, 45, 55, 68 and 85 kDa ML antigens was observed whereas the response to those of 43, 45, 48, 60, 64 and 97 kDa (described previously as TSL-1 antigens) occurred late in the infection. A follow-up of antigen recognition up to day 61 with the optimal immunization dose (2000 ML) evidenced a decline of Ab production to the 49 kDa NBL antigen 42 days p.i., which suggested antigenic differences with the previously reported 43 kDa ML antigen strongly recognized late in the infection. To analyze the stage-specificity of the 49 kDa NBL antigen, polyclonal antibodies (PoAb) were obtained in rats immunized with 49 kDa NBL antigen. PoAb reacted strongly with the 49 kDa NBL component in NBL total soluble extract but no reactivity was observed with soluble antigen of the other T. spiralis stages. Albeit with less intensity, the 49 kDa component was also recognized by PoAb together with other antigens of 53, 97 and 107 kDa, in NBL excretory-secretory products (NBL-ESP). Thus, our results reveal differences in the kinetics of anti-NBL and ML Ab responses. While anti-NBL Abs declined slowly from day 19 until the end of the experiment, Abs to ML antigen remained high in the same period. It is remarkable the optimal Ab response to NBL antigens with 2000 ML infective dose and the reduced number of NBL antigens identified throughout the experimental T. spiralis infection, standing out the immunodominant 49 kDa antigen. Interestingly, this antigen, which was prominently expressed in NBL somatic proteins, was also detected in NBL-ESP.     

Cortical State Fluctuations across Layers of V1 during Visual Spatial Perception

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The Population Decline and Extinction of Darwin’s Frogs

Darwin’s frogs (Rhinoderma darwinii and R. rufum) are two species of mouth-brooding frogs from Chile and Argentina. Here, we present evidence on the extent of declines, current distribution and conservation status of Rhinoderma spp.; including information on abundance, habitat and threats to extant Darwin’s frog populations. All known archived Rhinoderma specimens were examined in museums in North America, Europe and South America. Extensive surveys were carried out throughout the historical ranges of R. rufum and R. darwinii from 2008 to 2012. Literature review and location data of 2,244 archived specimens were used to develop historical distribution maps for Rhinoderma spp. Based on records of sightings, optimal linear estimation was used to estimate whether R. rufum can be considered extinct. No extant R. rufum was found and our modelling inferred that this species became extinct in 1982 (95% CI, 1980–2000). Rhinoderma darwinii was found in 36 sites. All populations were within native forest and abundance was highest in Chiloé Island, when compared with Coast, Andes and South populations. Estimated population size and density (five populations) averaged 33.2 frogs/population (range, 10.2–56.3) and 14.9 frogs/100 m² (range, 5.3–74.1), respectively. Our results provide further evidence that R. rufum is extinct and indicate that R. darwinii has declined to a much greater degree than previously recognised. Although this species can still be found across a large part of its historical range, remaining populations are small and severely fragmented. Conservation efforts for R. darwinii should be stepped up and the species re-classified as Endangered.     

Ecotypic differentiation in Medicago polymorpha L. along an environmental gradient in central Chile. I. Phenology,biomass production and reproductive patterns

Burr Medic (Medicago polymorpha) is awidespread, polymorphic annual legume of Mediterranean origin, and as aself-reseeding, highly effective nitrogen fixer it has important value invarious dryland farming systems. In central Chile, it is naturalized along a1000 km long environmental gradient, from an arid zone(29°–31° S) to a perhumid one(37°–38°24' S). Comparative and experimental studiesof its ecotypic differentiation patterns along this gradient should be usefulinelucidating the evolutionary forces at work along environmental gradients, andalso for efforts to select annual legumes for pastures and fallow fieldimprovement in mediterranean climate areas. In this first paper of atwo-part series, we present results of two common-environmentexperiments conducted at a subhumid site in central Chile to compare vegetativeand reproductive traits in 69 populations of Burr Medic collected in 1988 and1994. Multivariate analyses based on 11 phenological and agronomic characters,including phenology and biomass accumulation, winter vigour and degree ofhard-seededness, showed that three principal components (PCs)explained nearly 70% of total variability, in both collections. For thelarger collection (1988), the diagram of dispersion for the first twoPCs – phenology, winter vigour and above-ground biomass –provided good discrimination between accessions from arid-semiarid andhumid-perhumid mediterranean zones. Onset of flowering was positivelycorrelated with both latitude and longitude, as well as mean annualprecipitation/potential evapotranspiration (PP/ETP) ofcollecting site; days from first flower to pod ripening was negativelycorrelated with PP/ETP. In contrast to reports from Syria and Sardinia, noclear trends in Burr Medic seed or pod-related traits was found along theChilean gradient, apart from the concentration of spiny pod accessions in thesouthern, more mesic end of the gradient. Winter vigour (according to asemi-quantitative analysis of growth) was greater in accessions fromthe warmer, arid and semiarid zones than in those from cooler, subhumid tohumidones. Both winter vigour and harvest index were negatively correlated with daysto first flower. Applied and evolutionary aspects of the results are brieflydiscussed.     

INCREASED RESIDUAL VARIANCE AT DEVELOPMENTAL SWITCH POINTS: STATISTICAL ARTIFACT OR INDICATOR OF EXPOSED GENOTYPIC INFLUENCE?

Discussing the organization of developmental switches, West-Eberhard (2003) proposed the use of regression residual plots to locate the neutral point of the switch, which is characterized by maximum genotypic influence on the resulting phenotype. However, statistical artifacts due to measurement error in nonlinear models might account for a substantial proportion of the increase of residuals variance at the switch point. Simulations based on field data show that increases in residual variance occur as artifacts when normal amounts of measurement error are present, even in absence of any genotypic variance. The results suggest that interpretation of nonlinear variation in thresold traits is problematic and requires considering this statistical effect. A method to estimate the weight of genotypic contribution to residual variance is proposed, and its assumptions and limitations are discussed.     

Multivariate discrimination between East African cape hares (Lepus capensis) and savanna hares (L. victoriae) based on occipital bone shape

In East Africa, cape hares (Lepus capensis) and savanna hares (L. victoriae) look much alike where their ranges overlap. Earlier studies suggested discrimination between the two species by several skull traits, but did not present morphometric statisitics. Our present discriminant analysis based on seven metric variables of the occipital bone related to skull length (condylobasal length) resulted in a high (95.1%) overall probability of correct separation of the two species. While all cape hares were classified correctly, correct classification was a bit lower in savanna hares (88.2%). A principal components analysis of the same variables confirmed the shape difference for the two species. Both region and sex-specific variation in the shape of the studied occipital bone complex was found in savanna hares but not in cape hares. The somewhat reduced level of correct identification of savanna hares might be due to a tendency for higher shape variation. Application of our discriminant analysis to other regions in East Africa is discussed.