Effects of weathered polyethylene microplastic ingestion on sexual maturation, fecundity and egg quality in maturing broodstock Atlantic cod Gadus morhua.

Microplastics (MPs) have become a global issue as they are omnipresent in the ocean. Fish ingesting MPs through feed could be affected in their physiological function, e.g., disrupted enzyme production and function, reduction of feeding and reproductive failure. This study assessed the effects of feed containing naturally weathered MPs from the Oslofjord (Norway) on the reproductive physiology of Atlantic cod (Gadus morhua). Farmed cod broodstock were fed either control (C-diet) or feeds containing 1% microplastic (MP-diet) starting nine months prior to spawning, from June until May. No major differences were found between diet groups in overall biometrics or gonad histology. Sex steroid levels (testosterone, 11-ketotestosterone and 17ß-estradiol) resulted in expected profiles increasing over time without any significant differences between treatments. Gene expression levels of the steroidogenic enzyme 20ß-hydroxysteroid dehydrogenase (20ß-hsd) and vitellogenin1 (vtg1) showed significant differences between dietary treatments with lower expression in the control group. This can be a direct effect of MPs, but endocrine disrupting effects of potentially leachable plastic additives cannot be completely ruled out. Thus, these enzymes could be indicators of exposure to contaminants that disrupt sexual maturation by affecting the production of primarily maturation-inducing steroid. Although the concentration of MPs employed in this study may not be high enough to elicit any observable short-term biological effects, the observed gene expression suggests that long-term consequences should be considered caused by an expected increase of MPs in marine environments.

Functionalization of La0.33Ca0.67MnO3 with biologically active small ligand at room temperature.

We report the structural, morphological and optical activities of a paramagnetic manganite (La0.33Ca0.67MnO3) synthesized at 900 °C. A simple method of formation of complex was employed. A complex was formed between a pre-prepared manganite dissolved in HCl and reacted with an organic ligand (ethyl 4-nitrobenzoate). The optical and antimicrobial properties of a complex were determined. The Ultraviolet-visible and Fourier-transform infra-red spectroscopy were used in monitoring optical activities of the resulting product. It was observed to absorb in the visible region (205 nm and 256 nm). The peaks observed from the infra-red spectra indicated that the reaction occurred at the nitroso end of the ethyl 4-nitrobenzoate. The bacterial inhibitory property of the LCMO-ethyl 4-nitrobenzoate was determined against Pseudomonas aeruginosa, Candida albican, Aspergillus niger and Staphylococcus auerus. It was observed to inhibit the growth of all the microbes with zone of inhibitions of 60 mm, 56 mm, 45 mm and 32 mm, for Pseudomonas aeruginosa, Candida albican, Aspergillus niger and Staphylococcus auerus, respectively. •The method used was simple and a complex was formed within 6 h without the use of complicated equipment.•The method requires no heat treatment and can be prepared at room temperature.•LCMO-ethyl 4-nitrobenzoate was biologically active against Pseudomonas aeruginosa, Candida albican, Aspergillus niger and Staphylococcus aureus.

Note: On the study of metal/oxide hybrid ferromagnets with magneto-optical techniques.

We analyze here the magneto-optical measurements of hybrid materials containing metallic and oxide ferromagnetic phases. We show that the magnetization curves obtained with this technique can be fairly different to those obtained with standard magnetometry techniques and cannot be representative of the contribution of each phase to the magnetization of the material, due to the very different optical properties of metals and oxides. However, a proper numerical analysis of the magneto-optical measurements allows estimating the fraction of each phase present in the material.

PERMANENT GENETIC RESOURCES: Development of microsatellite markers for the ecosystem bioengineer mussel Perumytilus purpuratus and cross-priming testing in six Mytilinae genera.

Eight microsatellite markers have been characterized from the Perumytilus purpuratus genome. Their gene diversity ranged from 0.057 to 0.873 and significant interpopulation genic heterogeneity was observed between two populations of southeastern Pacific (Chile) and southwestern Atlantic (Argentine). Distinct cross-priming amplification rates were recovered on nine additional species belonging to six Mytilinae genera. The microsatellites developed herein would likely be a powerful intraspecific genetic tool to undertake fine population studies in the intertidal ecosystem bioengineer P. purpuratus along the South American shoreline.

New polymorphic microsatellite markers for the limpet Patella rustica and cross-priming testing in four Patella species.

Eighteen microsatellite markers have been characterized from the Patella rustica genome. An average of 10 alleles per locus and an expected heterozygosity ranging from 0.054 to 0.937 were observed in a sample of 32 wild individuals from Viana do Castelo, Portugal. Distinct cross-priming amplification rates were recovered on four additional Patella species. Three monomorphic P. rustica loci were polymorphic in other Patella species. The microsatellites developed herein could be a useful intraspecific genetic tool to undertake fine population studies in the genus Patella.

Development and characterization of 248 novel microsatellite markers in turbot (Scophthalmus maximus).

The turbot is a flatfish species of great relevance to marine aquaculture in Europe. Only a limited number of microsatellites have been isolated to date in this species. To increase the number of potentially useful mapping markers, we screened simple sequence repeat (SSR)--enriched genomic libraries obtained from several di-, tri-, and tetranucleotide tandem repeat motifs. A total of 248 new polymorphic microsatellites were successfully optimized. The efficiency of the protocol applied (6.4%) was higher than that in other studies of fish that used the same method. Dinucleotide and perfect microsatellites were predominant in this species; the (AC)n motif was the most frequent class of repeat. Polymorphism and structural properties at these loci, together with 30 variable loci previously reported in turbot, were evaluated in 6 wild individuals. The number of alleles per locus ranged from 2 to 10, with an average of 4.046. The microsatellite markers characterized in this study will contribute to the development of the turbot genetic map, which can be used for quantitative trait locus (QTL) identification, marker-assisted selection programs, and other applications to improve its culture.

Distribution properties of polymononucleotide repeats in molluscan genomes.

A total of 635 DNA sequences from 35 species of mollusks were used as taxonomic support to investigate several distribution features of polymononucleotides in genomic regions of different functionality. We show that all polymononucleotide types in mollusks fit to expectations in exons but not in nonexonic regions, in agreement with a leading role of negative selection on expansions/contractions of transcription-linked poly-(A/T) repeats. The fit of all repeat length types to an exponential decay precludes the existence of a threshold size for replication slippage, a popular but unsatisfactorily explained concept in mutation models for single repeats. The genomic density of poly-(A/T) repeats is not correlated with the DNA content of species, suggesting that the differential density of repeats between species could be better explained by the species-specific performance of its repair mechanisms. This research allows a better understanding of the distribution patterns of single repeats in eukaryotes.

Phylogeographic congruence between mtDNA and rDNA ITS markers in brown trout.

Variation in the internal transcribed spacer (ITS) of rDNA was examined throughout the range of the brown trout (Salmo trutta) to analyze the usefulness of this molecular marker for phylogeographic analysis. The results were compared with those previously obtained with mtDNA, a region exhaustively analyzed along the brown trout distribution. ITS2 was essentially conserved at all populations sampled, no informative characters being detected across the main lineages described in this species. Conversely, ITS1 showed a greater homogenization than other genetic markers at a microgeographic scale, with variation partitioning into several major phylogenetic groups. Phylogeographic patterns were partially congruent between both ITS1 and mtDNA. The main discrepancies were the detection of intra-individual variation and putative recombinant ITS1 sequences in hybridization areas between genetically different, yet historically overlapping, assemblages. Also, the existence of an ancient ITS1 sequence in the Mediterranean-southeastern area (rMEDA), not revealed by mtDNA analysis, was evidenced after rDNA ITS1 analysis.

Anisotropic relaxations introduced by Cd impurities in rutile TiO(2): first-principles calculations and experimental Support.

We present an ab initio study of the relaxations introduced in TiO (2) when a Cd impurity substitutes a Ti atom and an experimental test of this calculation by a perturbed-angular-correlation (PAC) measurement of the orientation of the electric-field gradient (EFG) tensor at the Cd site. The ab initio calculation predicts strong anisotropic relaxations of the nearest oxygen neighbors of the impurity and a change of the orientation of the largest EFG tensor component, V(33 ), from the [001] to the [110] direction upon substitution of a Ti atom by a Cd impurity. The last prediction is confirmed by the PAC experiment that shows that V(33 ) at the Cd site is parallel to either the [110] or the [1 1;0] crystal axis.

Juxtaposed microsatellite systems as diagnostic markers for admixture: an empirical evaluation with brown trout (Salmo trutta) as model organism.

A juxtaposed microsatellite system (JMS) is composed of two microsatellite repeat arrays separated by a sequence of less than 200 bp and more than 20 bp. This paper presents the first empirical evaluation of JMSs for the study of genetic admixture induced by man, with brown trout (Salmo trutta) as model organism. Two distinct admixture situations were studied: native populations from streams of the Atlantic basin and of the Mediterranean basin, respectively, all stocked with domestic strains originating from the Atlantic basin. For these two situations, we first evaluated by simulation the ability of JMSs to differentiate between alien alleles and naturally shared homoplasious or ancestral alleles, and thus to behave as diagnostic markers for admixture. Simulations indicated that JMSs are expected to be reliable diagnostic markers in most divergent (i.e. Mediterranean) populations and nonreliable diagnostic markers in most closely related (i.e. Atlantic) populations. Three JMSs were genotyped in domestic strains as well as in nonstocked and stocked populations of brown trout sampled in different rivers of the Mediterranean and Atlantic basins. The observed distributions of JMS haplotypes were consistent with simulation predictions confirming that JMSs were reliable diagnostic markers only over a given proportion of the species range, i.e. in substantially divergent populations. JMSs also reinforced the diagnostic character of three microsatellite sites for the studied Mediterranean populations. This last result is consistent with our simulation results which showed that, although much less frequently than at JMSs, diagnostic markers are likely to be found at single site microsatellites provided that the native Mediterranean population has a sufficiently small effective population size. For each population of the Mediterranean basin admixture coefficients did not differ significantly across JMSs and mean admixture coefficients sometimes differ among populations. The interpretation of the origin of JMS haplotypes based on the allele length variants was supported by nucleotide sequence analysis.

(CT)n and (GT)n microsatellites: a new class of genetic markers for Salmo trutta L. (brown trout).

Thirteen (GT)n and four (CT)n microsatellite loci (n = 10 or more and n = 20 or more, respectively) have been isolated from a partial genomic library of brown trout and sequenced. On average, a (GT)n repeat sequence occurs approximately every 23 kb and a (CT)n repeat sequence every 76 kb in brown trout genome. Primers for DNA amplifications using the polymerase chain reaction (PCR) were synthesized for three single locus microsatellites. Mendelian inheritance of the observed polymorphisms was confirmed in full-sib families. Four brown trout populations (10 unrelated individuals per population) were screened for polymorphism with these three microsatellite loci. The total number of alleles detected in the four populations is five at one locus, six at the other two microsatellite loci and is three, on average, per population. Heterozygosities range from 0.18 to 0.74. The largest differences in allelic frequencies occurred between the Mediterranean and the Atlantic populations: this result is congruent with previous allozymic data. The gene-centromere distances of the three microsatellite markers were determined on gynogenetic lines: post-reduction rates range from 0.17 to 0.60. For all the three microsatellite loci, the primers designed from brown trout sequences can be used in another closely related species of salmonid, the rainbow trout (Oncorhynchus mykiss). This last aspect supports the view that microsatellite markers may have wide application in genetic studies in salmonid species and fishes in general.