Vitellogenin is not an appropriate biomarker of feminisation in a Crustacean

The expression of the yolk protein vitellogenin (Vtg) has been used as a biomarker of feminisation in multiple fish species throughout the world. Since the late 1990s, researchers have attempted to develop similar biomarkers to address whether reproductive endocrine disruption also occurs in the males of invertebrate groups such as the Crustacea. To date, the vast majority of studies investigating Vtg induction in male Crustacea have resulted in negative or inconclusive results, leading researchers to question the utility of Vtg expression as a biomarker in this taxon. This study measured the expression of Vtg genes in two intersex phenotypes (termed internal and external) found in the male amphipod, Echinogammarus marinus, and compared them with those of normal males and females. Males presenting the external intersex phenotype are infected with known feminising parasites and display a variety of feminised traits including oviduct structures on their testes and external female brood plates (oostegites). The internal intersex male phenotype, that displays a pronounced oviduct structure on the testes without the external intersex characteristics, is not parasite infected and it is thought to be a result of environmental contamination. Given their morphology, these phenotypes might be considered highly ‘feminised’ or ‘de-masculinised’ and can be utilised to test the suitability of feminisation biomarkers. The E. marinus transcriptome was searched for genes resembling Vtg and two sequences were revealed, that we subsequently refer to as Vtg1 and Vtg2. Results from a high-throughput transcriptomic sequencing screen of gonadal cDNA libraries suggested that very low expression (in this manuscript gene transcription is taken to represent gene expression, although it is acknowledged that in addition to transcription, translation, transcript processing, mRNA stability and protein stability can regulate gene expression) of Vtg1 and Vtg2 in normal males (ESTs = 1 and 0 for Vtg1 and Vtg2, respectively), internal intersex males (ESTs = 0 for both Vtg sequences) and external intersex males (ESTs = 5 and 0 for Vtg1 and Vtg2, respectively). In contrast, the sequencing suggested notable levels of expression of both Vtg genes in females (ESTs = 1133 and 84 for Vtg1 and Vtg2, respectively). Subsequent qPCR analysis validates these expression levels, with the signal for Vtg1 and Vtg2 transcripts in all male phenotypes being indistinguishable from that caused by contamination of trace levels of genomic DNA or the low-level amplification non-target sequences. These findings suggest that Vtg expression is not notably induced in highly feminised amphipods and is therefore not an appropriate biomarker of feminisation/de-masculination in crustaceans. We discuss our findings in the context of previous attempts to measure Vtg in male crustaceans and suggest a requirement for more appropriate taxon-specific biomarkers to monitor feminisation in these groups

Population screening and transmission experiments indicate paramyxid-microsporidian co-infection in Echinogammarus marinus represents a non-hyperparasitic relationship between specific parasite strains

Phylogenetically distant parasites often infect the same host. Indeed, co-infections can occur at levels greater than expected by chance and are sometimes hyperparasitic. The amphipod Echinogammarus marinus presents high levels of co-infection by two intracellular and vertically transmitted parasites, a paramyxid (Paramarteilia sp. Em) and a microsporidian strain (Dictyocoela duebenum Em). This co-infection may be hyperparasitic and result from an exploitative ‘hitchhiking’ or a symbiotic relationship between the parasites. However, the best-studied amphipod species are often collected from contaminated environments and may be immune-compromised. Immune-challenged animals frequently present co-infections and contaminant-exposed amphipods present significantly higher levels of microsporidian infection. This suggests the co-infections in E. marinus may result from contaminant-associated compromised immunity. Inconsistent with hyperparasitism, we find that artificial infections transmit Paramarteilia without microsporidian. Our population surveys reveal the co-infection relationship is geographically widespread but find only chance co-infection between the Paramarteilia and another species of microsporidian, Dictyocoela berillonum. Furthermore, we identify a haplotype of the Paramarteilia that presents no co-infection, even in populations with otherwise high co-infection levels. Overall, our results do not support the compromised-immunity hypothesis but rather that the co-infection of E. marinus, although non-hyperparasitic, results from a relationship between specific Paramarteilia and Dictyocoela duebenum strains

Understanding the margin squeeze: differentiation in fitness-related traits between central and trailing edge populations of Corallina officinalis

Assessing population responses to climate-related environmental change is key to understanding the adaptive potential of the species as a whole. Coralline algae are critical components of marine shallow water ecosystems where they function as important ecosystem engineers. Populations of the calcifying algae Corallina officinalis from the center (southern UK) and periphery (northern Spain) of the North Atlantic species natural distribution were selected to test for functional differentiation in thermal stress response. Physiological measurements of calcification, photosynthesis, respiration, growth rates, oxygen, and calcification evolution curves were performed using closed cell respirometry methods. Species identity was genetically confirmed via DNA barcoding. Through a common garden approach, we identified distinct vulnerability to thermal stress of central and peripheral populations. Southern populations showed a decrease in photosynthetic rate under environmental conditions of central locations, and central populations showed a decline in calcification rates under southern conditions. This shows that the two processes of calcification and photosynthesis are not as tightly coupled as previously assumed. How the species as whole will react to future climatic changes will be determined by the interplay of local environmental conditions and these distinct population adaptive traits.South African Research Chairs Initiative (SARChI) IF/01413/2014/CP1217/CT0004 University of Portsmouthinfo:eu-repo/semantics/publishedVersio

Shipping in the north-east Atlantic : identifying spatial and temporal patterns of change

This work was supported by a faculty PhD bursary from the University of Portsmouth. Work was supported by the Marine Ecosystems Research Programme.Maritime traffic is increasing globally, with a four-fold increase in commercial vessel movements between 1992 and 2012. Vessels contribute to noise and air pollution, provide pathways for non-native species, and collide with marine wildlife. While knowledge of shipping trends and potential environmental impacts exists at both local and global levels, key information on vessel density for regional-scale management is lacking. This study presents the first in-depth spatio-temporal analysis of shipping in the north-east Atlantic region, over three years in a five-year period. Densities increased by 34%, including in 73% of Marine Protected Areas. Western Scotland and the Bay of Biscay experienced the largest increases in vessel density, predominantly from small and slow vessels. Given well-documented impacts that shipping can have on the marine environment, it is crucial that this situation continues to be monitored – particularly in areas designated to protect vulnerable species and ecosystems which may already be under pressure.Publisher PDFPeer reviewe

Association between GDF-15 levels and changes in vascular and physical function in older patients with hypertension

Background: Growth differentiation factor-15 (GDF-15) may be a biomarker of disease, protective response and/or prognosis, in older people with hypertension. Aims: To correlate baseline GDF-15 levels with physical and vascular health data in this population. Methods: Baseline blood samples were analysed using a GDF-15 ELISA assay kit. Correlations with baseline and 12-month outcome data, including measures of physical and vascular function, were performed. Results: A total of 147 individuals, mean age 76.8 ± 4.7 years, were included. 77 (52 %) were male. Baseline log10GDF-15 showed significant correlations with age (r = 0.37, p < 0.001), total cholesterol (r = −0.33, p < 0.001) and 6-min walking distance (r = −0.37, p < 0.001). Age remained significantly associated with log10GDF-15 in multivariable analysis (beta = −0.29, p = 0.001). Baseline log10GDF-15 was significantly associated with decline in 6-min walk distance over 12 months (beta = −0.27, p = 0.01) in multivariable models. No significant correlations were seen with changes in vascular function over 12 months. Conclusion: Baseline GDF-15 predicts declining physical, but not vascular, function in our population

On the chirality of quark modes

A model for the QCD vacuum based on a domainlike structured background gluon field with definite duality attributed to the domains has been shown elsewhere to give confinement of static quarks, a reasonable value for the topological susceptibility and indications that chiral symmetry is spontaneously broken. In this paper we study in detail the eigenvalue problem for the Dirac operator in such a gluon mean field. A study of the local chirality parameter shows that the lowest nonzero eigenmodes possess a definite mean chirality correlated with the duality of a given domain. A probability distribution of the local chirality qualitatively reproduces histograms seen in lattice simulations.Comment: RevTeX4, 5 figures, 14 page