Effect of the metals iron, copper and silver on fluorobenzene biodegradation by Labrys portucalensis

Organic and metallic pollutants are ubiquitous in the environment. Many metals are reported to be toxic to microorganisms and to inhibit biodegradation. The effect of the metals iron, copper and silver on the metabolism of Labrys portucalensis F11 and on fluorobenzene (FB) biodegradation was examined. The results indicate that the addition of 1 mM of Fe²⁺ to the culture medium has a positive effect on bacterial growth and has no impact in the biodegradation of 1 and 2 mM of FB. The presence of 1 mM of Cu²⁺ was found to strongly inhibit the growth of F11 cultures and to reduce the biodegradation of 1 and 2 mM of FB to ca. 50 %, with 80 % of stoichiometrically expected fluoride released. In the experiments with resting cells, the FB degraded (from 2 mM supplied) was reduced ca. 20 % whereas the fluoride released was reduced to 45 % of that stoichiometrically expected. Ag⁺ was the most potent inhibitor of FB degradation. In experiments with growing cells, the addition of 1 mM of Ag⁺ to the culture medium containing 1 and 2 mM of FB resulted in no fluoride release, whereas FB degradation was only one third of that observed in control cultures. In the experiments with resting cells, the addition of Ag⁺ resulted in 25 % reduction in substrate degradation and fluoride release was only 20 % of that stoichiometrically expected. The accumulation of catechol and 4-fluorocatechol in cultures supplemented with Cu²⁺ or Ag⁺ suggest inhibition of the key enzyme of FB metabolism—catechol 1,2-dioxygenase.     

Characterization of the cardiac phospholipidome of small cetaceans provides adaptational insight and a foundation for indirect population health screening

The maintenance of a tightly regulated heart lipidome is a general hallmark of mammal health. However, in the case of cetaceans, heart tissue lipid composition remains obscure. This work represents a first in-depth state-of-the-art characterization of the lipid content of small cetacean hearts, namely those of Delphinus delphis, Phocoena phocoena, and Stenella coeruleoalba. Phospholipid classes identified were similar to those found in terrestrial mammals. Regarding fatty acid profiles, they revealed a much higher n-3 fatty acid content than that reported for terrestrial counterparts. Phospholipidome characterization allowed identification of 198 lipid species, including phospholipids, lysophospholipids, and sphingomyelins, generally characterized by a high content of species with esterified n-3 fatty acids. The cardiac lipid profile of the three cetacean species is similar in terms of lipid classes, fatty acids, and even molecular lipid species present. However, quantitative differences suggest a divergence of S. coeruleoalba from the other species in terms of fatty acid and phospholipid profile. The identified differences regarding terrestrial counterparts will contribute to better understanding the details of small cetacean cardiac physiology. Moreover, the characterization of cardiac phospholipidome may represent an opportunity to establish lipidomic-based practical tools to reliably and reproducibly assess small cetacean health population status by remote sampling.     

A population genetic assessment of taxonomic species: The case of Lake Malawi cichlid fishes

Organisms sampled for population‐level research are typically assigned to species by morphological criteria. However, if those criteria are limited to one sex or life stage, or the organisms come from a complex of closely related forms, the species assignments may misdirect analyses. The impact of such sampling can be assessed from the correspondence of genetic clusters, identified only from patterns of genetic variation, to the species identified using only phenotypic criteria. We undertook this protocol with the rock‐dwelling mbuna cichlids of Lake Malawi, for which species within genera are usually identified using adult male coloration patterns. Given high local endemism of male colour patterns, and considerable allele sharing among species, there persists considerable taxonomic uncertainty in these fishes. Over 700 individuals from a single transect were photographed, genotyped and separately assigned: (a) to morphospecies using photographs; and (b) to genetic clusters using five widely used methods. Overall, the correspondence between clustering methods was strong for larger clusters, but methods varied widely in estimated number of clusters. The correspondence between morphospecies and genetic clusters was also strong for larger clusters, as well as some smaller clusters for some methods. These analyses generally affirm (a) adult male‐limited sampling and (b) the taxonomic status of Lake Malawi mbuna, as the species in our study largely appear to be well‐demarcated genetic entities. More generally, our analyses highlight the challenges for clustering methods when the number of populations is unknown, especially in cases of highly uneven sample sizes.     

Rates of transposition in Escherichia coli

The evolutionary role of transposable elements (TEs) is still highly controversial. Two key parameters, the transposition rate (u and w, for replicative and non-replicative transposition) and the excision rate (e) are fundamental to understanding their evolution and maintenance in populations. We have estimated u, w and e for six families of TEs (including eight members: IS1, IS2, IS3, IS4, IS5, IS30, IS150 and IS186) in Escherichia coli, using a mutation accumulation (MA) experiment. In this experiment, mutations accumulate essentially at the rate at which they appear, during a period of 80 500 (1610 generations × 50 lines) generations, and spontaneous transposition events can be detected. This differs from other experiments in which insertions accumulated under strong selective pressure or over a limited genomic target. We therefore provide new estimates for the spontaneous rates of transposition and excision in E. coli. We observed 25 transposition and three excision events in 50 MA lines, leading to overall rate estimates of u ∼ 1.15 × 10^–5, w ∼ 4 × 10⁻⁸ and e ∼ 1.08 × 10⁻⁶ (per element, per generation). Furthermore, extensive variation between elements was found, consistent with previous knowledge of the mechanisms and regulation of transposition for the different elements.     

Moonlight pollination in the gymnosperm Ephedra (Gnetales)

Most gymnosperms are wind-pollinated, but some are insect-pollinated, and in Ephedra (Gnetales), both wind pollination and insect pollination occur. Little is, however, known about mechanisms and evolution of pollination syndromes in gymnosperms. Based on four seasons of field studies, we show an unexpected correlation between pollination and the phases of the moon in one of our studied species, Ephedra foeminea. It is pollinated by dipterans and lepidopterans, most of them nocturnal, and its pollination coincides with the full moon of July. This may be adaptive in two ways. Many nocturnal insects navigate using the moon. Further, the spectacular reflection of the full-moonlight in the pollination drops is the only apparent means of nocturnal attraction of insects in these plants. In the sympatric but wind-pollinated Ephedra distachya, pollination is not correlated to the full moon but occurs at approximately the same dates every year. The lunar correlation has probably been lost in most species of Ephedra subsequent an evolutionary shift to wind pollination in the clade. When the services of insects are no longer needed for successful pollination, the adaptive value of correlating pollination with the full moon is lost, and conceivably also the trait.     

Pollen morphology of Xanthium L. (s.l.) (Asteraceae,Asteroideae, Heliantheae,Ambrosiinae) in the Iberian Peninsula - a palynotaxonomic approach to a poisonous,allergenic and invasive genus

Abstract

The pollen morphology of the Iberian taxa of the genus Xanthium s.l. and of the non-Iberian species X. ambrosioides was studied to help to identify these poisonous, allergenic and invasive taxa and clarify their taxonomic relationships. In addition, the question of the existence and structure of a mesoaperture in the apertural system of Xanthium was also considered. The pollen grains of sections Acanthoxanthium and Xanthium clearly differ by their characters, which supports the separation of both taxa and allows for their distinction based on pollen morphology. It is suggested that the morphological and palynological differences between Xanthium and Acanthoxanthium, together with the lack of hybridisation between the two sections and the monophyly of Acanthoxanthium, could lead to the elevation of the latter to the generic status. The two species of section Xanthium present in the Iberian Peninsula (X. orientale and X. strumarium) and of section Acanthoxanthium are well separated by their palynological features. Likewise, the Iberian subspecies of Xanthium, X. orientale subsp. orientale and X. orientale subsp. italicum are palynologically distinguishable. However, no significant difference could be found between the pollen of X. strumarium subsp. strumarium and of X. strumarium subsp. brasilicum. The pollen data do not support the hypotheses of a hybrid origin for X. strumarium subsp. brasilicum. A mesoaperture intersecting the foot layer and the upper part of the endexine is present in both sections, which is congruent with the results already found for other Asteroideae.     

European rabbit research in the Iberian Peninsula: state of the art and future perspectives

The European rabbit (Oryctolagus cuniculus) is a high-profile prey, native from the Iberian Peninsula, the only region in the world where the two rabbit subspecies (O. cuniculus algirus and O. cuniculus cuniculus) currently co-exist in natural conditions. In this area, this important prey represents a keystone species and ecosystem engineer of Mediterranean landscapes, being also the most harvested and one of the most managed small-game species. Additionally, the species can create damage to crops in some parts of the Iberian Peninsula where it is regarded as an agricultural pest. The scientific interest towards the species is becoming increasingly apparent most likely as a repercussion of declining population trends over the last decades. The latter has been the result of the impact of habitat deterioration, viral diseases, unsustainable hunting, and predation. In this paper, I present a review of the scientific literature currently available on the European rabbit in the Iberian Peninsula. I discuss knowledge gaps and highlight priority research guidelines to suppress them, in an attempt to provide a general perspective to target research efforts more effectively. This analysis is particularly relevant due to the current vulnerability of rabbit populations in Iberia and to the recent news of cuts in scientific funding in most Mediterranean countries.     

Influence of radiation exposure rate on somatic mutation frequency and loss of reproductive integrity in tradescantia stamen hairs

Inflorescences of Tradescantia clone 02 (2n = 12), hetero- or hemi-zygous for flower color, were exposed to a series of γ-ray exposures at two different exposure rates, 29.3 R/min and 0.026–0.52 R/min. Pink mutation-response curves, and survival curves based on reproductive integrity, were constructed for each of the exposure rates. Loss of reproductive intergrity was also assessed at high (256 R/min) and low (0.52–4.17 R/min) γ-ray exposure rates in T. blossfeldiana (2n = 72). All observations were made on stamen hairs.The higher exposure rate was 1.3–1.7 times more effective in inducing pink mutations in clone 02. A greater efficiency of the higher exposure rate was also found for both taxa at the loss of reproductive integrity endpoint. The D₀ values obtained at the higher exposure rates, 154 R for clone 02 and 720 R for T. blossfeldiana, were significantly lower than the corresponding values of 270 R and 1880 R obtained at the lower exposure rates. These D₀'s differ by factors of 1.75 and 2.61 for clone 02 and T. blossfeldiana, respectively. D₀'s for the two taxa were found to be inversely correlated with their interphase chromosome volumes.