Performance of a down-flow fluidized bed reactor under sulfate reduction conditions using volatile fatty acids as electron donors

The use of a down-flow fluidized bed (DFFB) reactor for the treatment of a sulfate-rich synthetic wastewater was investigated to obtain insight into the outcome of sulfate reduction in a biofilm attached to a plastic support under a down-flow regime. Fine low-density polyethylene particles were used as support for developing a biofilm within the reactor. The reactor treated a volatile fatty acids mixture of acetate or lactate, propionate, and butyrate at different chemical oxygen demand (COD) to sulfate ratios ranging from 1.67 to 0.67 (g/g). Organic loading rate changed from 2.5 to 5 g COD/L x day and sulfate loading rate increased from 1.5 to 7.3 g SO(4) (2-)/L x day. At the beginning of continuous operation, methanogenesis was the predominant process; however, after 187 days, sulfate reduction became the main ongoing biological process. After 369 days, a COD removal of 93% and a sulfate removal of 75% were reached. Total sulfide concentrations in the reactor ranged from 105, when the reactor was mainly methanogenic, to around 1,215 mg/L at the end of the experiment. The high sulfide concentrations did not affect the performance of the reactor. Results demonstrated that the configuration of the DFFB reactor was suitable for the anaerobic treatment of sulfate-rich wastewater.     

Testing morphology-based hypotheses of phylogenetic relationships in Parmeliaceae (Ascomycota) using three ribosomal markers and the nuclear RPB1 gene

Parmeliaceae is the largest family of lichen-forming fungi with more than 2000 species and includes taxa with different growth forms. Morphology was widely employed to distinguish groups within this large, cosmopolitan family. In this study we test these morphology-based groupings using DNA sequence data from three nuclear and one mitochondrial marker from 120 taxa that include 59 genera and represent the morphological and chemical diversity in this lineage. Parmeliaceae is strongly supported as monophyletic and six well-supported main clades can be distinguished within the family. The relationships among them remain unresolved. The clades largely agree with the morphology-based groupings and only the placement of four of the genera studied is rejected by molecular data, while four other genera belong to clades previously unrecognised. The classification of these previously misplaced genera, however, has already been questioned by some authors based on morphological evidence. These results support morphological characters as important for the identification of monophyletic clades within Parmeliaceae.     

Evolution and diversification of the forest and hypogean ground-beetle genus Trechus in the Canary Islands

The beetle genus Trechus (Carabidae) is represented in the Macaronesian Islands by 43 endemic species. The Canary Islands have 16 endemic species, with two adapted to hypogean life. Phylogenetic relationships among 177 individuals of 38 Canarian, Madeiran, Azorean and continental Trechus species were examined using mitochondrial DNA and nuclear internal transcribed spacer 2 (ITS2) sequence data. Results show two main lineages in the Canaries: one comprising two sister groups with species from the laurel forest of La Gomera and Tenerife, and the other containing the single species from Gran Canaria and a species complex in the four western islands including two troglobites. Calibrations were applied to a linearized tree using a relaxed molecular clock method to estimate the major evolutionary divergence times of the Canarian Trechus species. Although the species assemblage in this archipelago is relatively ancient (7-8 million years), much of the species diversity is recent. Transition to the hypogean environment is more consistent with the "adaptive shift" rather than with the competing "climatic relict" hypothesis.     

Stable and unstable cadherin dimers: mechanisms of formation and roles in cell adhesion

Numerous attempts to elucidate the strength of cadherin dimerization that mediates intercellular adhesion have produced controversial and inconclusive results. To clarify this issue, we compared E-cadherin dimerization on the surface of living cells with how the same process unfolds on agarose beads. In both cases, dimerization was monitored by the same site-specific cross-linking assay, greatly simplifying data interpretation. We showed that on the agarose surface under physiological conditions, E-cadherin produced a weak dimer that immediately dissociated after the depletion of calcium ions. However, either at pH 5 or in the presence of cadmium ions, E-cadherin produced a strong dimer that was unable to dissociate upon calcium depletion. Both types of dimers were W156-dependent. Remarkably, only the strong dimer was found on the surface of living cells. We also showed that the intracellular cadherin region, the clustering of which through catenins had been proposed as stabilizer of weak intercadherin interactions, was not needed, in fact, for cadherin junction assembly. Taken together, our data present convincing evidence that cadherin adhesion is based on high-affinity cadherin-cadherin interactions.     

The effect of acute moderate hypoxia on accumulated oxygen deficit during intermittent exercise in nonacclimatized men

The objective of this study was to determine the effect of acute moderate hypoxia and rest duration on performance and on the accumulated oxygen deficit (AOD) in high-intensity intermittent efforts. After preliminary tests, 2 groups of nonacclimatized men (resident at 690 m above sea level) carried out 3 randomized protocols of effort (EXP1, EXP2, and EXP5) on 3 different days. These tests were performed at acute moderate altitude (2,320 m) by the hypoxia group (H) and in normoxia by the normoxia group (N). During EXP1 the subjects ran a maximum of five 400-m sprints (90% intensity) on a treadmill, with a pause between efforts of 1 minute. In EXP2 and EXP5 the same protocol was repeated, increasing the rest period between sprints to 2 and 5 minutes, respectively. Lactate accumulation and exhaled gases were measured during the tests. Accumulated oxygen deficit was calculated for each sprint. The total AOD (SigmaAOD) for each type of protocol was determined to be the sum of the corresponding accumulated deficits. The AODs were influenced by the length of rest period (p < 0.05) but not by H. The increase in recovery time between sprints increased the SigmaAOD (7,843 +/- 4,435 vs. 7,137 +/- 2,117 ml; 11,013 +/- 4,616 vs. 9,931 +/- 2,731 ml; 12,611 +/- 4,594 vs. 12,907 +/- 3,085 ml for H and N in EXP1, EXP2, and EXP5, respectively). The AOD increased in value when the same sprint was compared from EXP1 to EXP5 (p < 0.05). The results obtained show that exposure to acute moderate altitude does not affect the anaerobic pathway contribution in intermittent high-intensity exercises. Performance during this type of repeated effort is not altered during acute exposure to moderate altitude, which should be taken into account when an acclimatizing period is not possible.     

Analysis of the spatio-temporal parameters of gaits in Dasypus novemcinctus (Xenarthra: Dasypodidae)

Armadillos comprise a particular group of armoured animals whose functional morphology of locomotion remains unclear. For the first time, the kinematic patterns of Dasypus novemcinctus are analysed. Eight specimens of nine-banded armadillos were studied at a research institute in São Paulo State, Brazil. The individuals were induced to cross a horizontal corridor and each gait performed during the time each of them was kept inside this structure was recorded to a detailed analysis posteriorly performed in a computer program. Four parameters regarding speed range were considered: stride frequency (Hz) (1/stride period), stride length (m), speed (ms⁻¹) and duty factor (%). A total of 89 strides have been analysed among symmetrical (60.6%) and asymmetrical gaits (39.4%), and six footfall patterns were here reported as follows: lateral sequences (symmetrical), transverse gallop, canter, bound, half-bound and crutch walk (asymmetrical). This kind of analysis implements our knowledge on the locomotory aspects of these animals, hence contributing to the improvement of our knowledge on this still poorly known group.     

Browning reduces the availability—but not the transfer—of essential fatty acids in temperate lakes

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Environmental heterogeneity and dispersal limitation explain different aspects of β‐diversity in Neotropical fish assemblages

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