Phytoplankton communities and biomass size structure (fractionated chlorophyll “a”), along trophic gradients of the Basque coast (northern Spain)

Eutrophication is a major threat to coastal ecosystems. Within Europe, the Water Framework Directive (WFD) has established the need of developing methods of assessment. Bulk chlorophyll “a” is used world-wide as an indicator of eutrophication. However, the size structure of the phytoplankton communities has not been investigated, in detail, in relation to eutrophication pressures. This study investigates the suitability of fractionated chlorophyll “a” (<10 and >10 μm), as an indicator of eutrophication. Along the Basque coast (northern Spain) several water bodies, ranging from offshore waters to the heads of the estuaries, were surveyed during 2008. Physico-chemical conditions and chlorophyll “a” showed a distinct spatial gradient. Trophic richness increased towards the middle and inner parts of the estuaries, where nutrient inputs, from natural or anthropogenic sources, together with the residence time of the water are usually higher. In summer, phytoplankton biomass and abundance decreased, generally, in offshore and coastal waters; in estuaries, they tended to increase. The chlorophyll distribution within the two size fractions was coherent with the phytoplankton taxonomic composition. In summer, the relative abundance of small-sized cells (diatoms and non-siliceous taxa) increased. The relationships between size-fractionated chlorophyll and physico-chemical variables differed, when comparing the offshore and coastal waters, with the estuaries. In the offshore and coastal waters, a strong seasonality was observed; in estuaries, an important spatial component was found. Fractionated chlorophyll provided complementary useful information on anthropogenic pressures. However, more research is necessary to utilise this variable as a tool for ecological status assessment, within the WFD.     

Resistance,Resilience or Change: Post-disturbance Dynamics of Boreal Forests After Insect Outbreaks

Ecosystems - Understanding and measuring forest resistance and resilience have emerged as key priorities in ecology and management, particularly to maintain forest functioning. The analysis of the...     

Microbial contamination in methanol biofilters inoculated with a pure strain of Pichia pastoris: A potential limitation for waste revalorization

Novel biotechnologies to valorize waste emissions are based on the use of specialized microbial groups that produce different compounds of industrial interest. On this scenario, the retention of such specific microorganisms in the system is of critical interest; however, the potential limitations of working with simplified cultures in a competitive open environment are neither fully explored nor well understood. In this work, a series of biofilters treating methanol vapors coupled with heterologous endochitinase production were used to evaluate the performance of a specialized microbial population during a typical open-to-environment operation. The biofilters were inoculated with a transformed strain of Pichia pastoris and were operated identically for about 90 days. The results showed that the biofiltration performance became diverse with time in terms of the elimination capacity (EC) shifting from a variation coefficient of 1.5% (EC = 274 ± 24, 279 ± 5, and 281.9 ± 25 g/[m³ h]) at the beginning of the operation to 33% (EC = 297 ± 9, 338 ± 7, and 341 ± 2 g/[m³ h]) at the end of operation. Epifluorescence analysis and cloning-sequencing suggested that P. pastoris remained as the dominant microorganism of methanol degradation, whereas diverse airborne bacteria, including Ochrobactrum spp. and Klebsiella oxytoca, played a secondary role possibly associated with the consumption of intermediates. Overall, this study found that low diversity systems operated under non-sterile conditions could be susceptible to contamination with external microorganisms causing a diversifying behavior at the performance and microbial community levels. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2715, 2019     

Sponges and corals from the Middle Eocene (Bartonian) marly formations of the Pamplona Basin (Navarre, western Pyrenees): taphonomy, taxonomy, and paleoenvironments

Sponges and corals from the Bartonian marly formations of the Pamplona Basin (South Pyrenean area, Navarre) are described for the first time. The fossiliferous levels correspond respectively to flood-influenced delta-front (Ardanatz Sandstone) and restricted outer-platform (Ilundain Marls Fm.) environments. The fossil sponges exhibit diagenetic fragmentation, but they are often complete specimens. The skeleton appears partially or totally replaced by calcite and/or in some cases large crystals of celestite. Celestite forms relatively early during diagenesis in a dysoxic environment. Neomorphic fibrous quartzine-lutecine spherulites are also present. Hexactinellids and lithistids occur, but the former predominate. The associations include the species Laocoetis samueli, Guettardiscyphia thiolati and/or Pleuroguettardia iberica, cf. Rhizocheton robustus, and two lithistids indet. Corals are present only in the Ardanatz Sandstone. The fossil skeletons are composed of large neomorphic sparry calcite crystals. The assigned species are Stylocoenia taurinensis, Astrocoenia octopartita, Ceratotrochus bodellei, Placosmiliopsis bilobatus, and Desmophyllum castellolense. The sponge and coral taxa are similar to those previously described from other contemporaneous geological formations of the Pyrenean realm. The Pamplona Basin assemblages appear less diverse than those of the Bartonian of the eastern South Pyrenean area, more similar to that of the Eocene of Biarritz (Aquitanian Basin). This lower diversity is not due to a lower-resolution sampling but to taphonomic bias and/or paleoecological differences. The dominance of hexactinellids, erect morphologies, and sedimentological and micropaleontological data show that the sponge communities lived in deep shelfal waters. The corals, mainly associated with levels with high terrigenous content, seem reworked from shallower and more proximal environments.     

Advantages and Versatility of Fluorescence-Based Methodology to Characterize the Functionality of LDLR and Class Mutation Assignment

Familial hypercholesterolemia (FH) is a common autosomal codominant disease with a frequency of 1∶500 individuals in its heterozygous form. The genetic basis of FH is most commonly mutations within the LDLR gene. Assessing the pathogenicity of LDLR variants is particularly important to give a patient a definitive diagnosis of FH. Current studies of LDLR activity ex vivo are based on the analysis of ¹²⁵I-labeled lipoproteins (reference method) or fluorescent-labelled LDL. The main purpose of this study was to compare the effectiveness of these two methods to assess LDLR functionality in order to validate a functional assay to analyse LDLR mutations. LDLR activity of different variants has been studied by flow cytometry using FITC-labelled LDL and compared with studies performed previously with ¹²⁵I-labeled lipoproteins. Flow cytometry results are in full agreement with the data obtained by the ¹²⁵I methodology. Additionally confocal microscopy allowed the assignment of different class mutation to the variants assayed. Use of fluorescence yielded similar results than ¹²⁵I-labeled lipoproteins concerning LDLR activity determination, and also allows class mutation classification. The use of FITC-labelled LDL is easier in handling and disposal, cheaper than radioactivity and can be routinely performed by any group doing LDLR functional validations.     

Sedimentology and taphonomy of sirenian remains from the Middle Eocene of the Pamplona Basin (Navarre, western Pyrenees)

Sirenian vertebrae and ribs have been recently discovered from two Middle Eocene localities of the Pamplona Basin, Navarre (western Pyrenees). These outcrops correspond to different lower Bartonian lithostratigraphic units: the lower part of the Pamplona Marl Formation (Uztarrotz site) and the upper part of the Ardanatz Sandstone (Ardanatz site). The former represents a deep and low-energy sea floor far away from a deltaic slope; the Ardanatz environment probably corresponds to a semi-closed deltaic bay periodically affected by catastrophic floods (i.e., fluvial hyperpycnal flows). The presence of epibiontic activity suggests that the bones were exposed for a while prior to the burial. The histological structures are well preserved except in the peripheral region, where tubular-like microstructures filled by pyrite and iron oxides probably correspond to microbial bioerosion. The major mineral component of the fossil bones is francolite (carbonate fluorapatite). In the Ardanatz samples there is evidence of secondary francolite due to the late replacement of original carbonate fluorapatite through internal fractures. The Ardanatz and Uztarrotz sirenian fossils do not show any evidence of reelaboration. They have similar sum of rare earth elements (REE) concentrations relative to the host rock, but comparatively lower than in other vertebrate fossil bones. This feature may be due to the dense compact structure of pachyosteosclerotic sirenian bones.