Can biochemical tracers reveal ontogenetic trophic shift and individual prey selection in white sharks from Guadalupe Island, Northeast Pacific?

Refining the role of apex predators in marine food webs is a necessary step in predicting the consequences of their global decline under the footprint of fishing activities. White sharks (Carcharodon carcharias) are vulnerable predators, performing large migrations and able to forage on a variety of prey in different habitats. In the Northeast Pacific, juvenile and adult white sharks are found seasonally at the same aggregation sites, such as Guadalupe Island off Mexico.

Do marine protected areas influence mercury exposure? Insights from a shark community in the tropical Northeast Pacific.

Biomass depletion caused by overfishing is likely to alter the structure of food webs and impact mercury transfer to marine predators. Although marine protected areas (MPAs) are spared from fishing pressure, their influence on biota mercury levels is poorly understood. Here, we used carbon and nitrogen stable isotope compositions as well as mercury concentrations in fin clips to characterize foraging habitat and mercury exposure of a shark community composed of migratory and resident species of the Revillagigedo archipelago, an offshore MPA in the Northeast Pacific off Mexico.

infective endocarditis in a homeless man with unexpected positive blood culture.

species represent important causative agents of blood culture-negative infective endocarditis (IE). Their diagnosis represents a challenge for microbiologists and often relies on serological and molecular tools. However, even if the sensitivity of blood culture remains low, it should not be definitely ruled out.

Mercury stable isotopes suggest reduced foraging depth in oxygen minimum zones for blue sharks.

Oxygen minimum zones (OMZs) are currently expanding across the global ocean due to climate change, leading to a compression of usable habitat for several marine species. Mercury stable isotope compositions provide a spatially and temporally integrated view of marine predator foraging habitat and its variability with environmental conditions. Here, we analyzed mercury isotopes in blue sharks Prionace glauca from normoxic waters in the northeastern Atlantic and from the world's largest and shallowest OMZ, located in the northeastern Pacific (NEP).

Mercury concentrations, biomagnification and isotopic discrimination factors in two seabird species from the Humboldt Current ecosystem.

Assessing mercury (Hg) biomagnification requires the description of prey-predator relationships, for each species and ecosystem, usually based on carbon and nitrogen isotope analyses. Here, we analyzed two seabirds from the Humboldt Current ecosystem, the Guanay cormorant (Phalacrocorax bougainvillii) and the Peruvian booby (Sula variegata), as well as their main prey, the Peruvian anchovy (Engraulis ringens). We reported Hg concentrations, Hg biomagnification (BMF) and isotopic discrimination factors (ΔC and ΔN) in seabird whole blood.

Foraging plasticity diversifies mercury exposure sources and bioaccumulation patterns in the world's largest predatory fish.

Large marine predators exhibit high concentrations of mercury (Hg) as neurotoxic methylmercury, and the potential impacts of global change on Hg contamination in these species remain highly debated. Current contaminant model predictions do not account for intraspecific variability in Hg exposure and may fail to reflect the diversity of future Hg levels among conspecific populations or individuals, especially for top predators displaying a wide range of ecological traits. Here, we used Hg isotopic compositions to show that Hg exposure sources varied significantly between and within three populations of white sharks (Carcharodon carcharias) with contrasting ecology: the north-eastern Pacific, eastern Australasian, and south-western Australasian populations.

Foraging depth depicts resource partitioning and contamination level in a pelagic shark assemblage: Insights from mercury stable isotopes.

The decline of shark populations in the world ocean is affecting ecosystem structure and function in an unpredictable way and new ecological information is today needed to better understand the role of sharks in their habitats. In particular, the characterization of foraging patterns is crucial to understand and foresee the evolution of dynamics between sharks and their prey. Many shark species use the mesopelagic area as a major foraging ground but the degree to which different pelagic sharks rely on this habitat remains overlooked.

Concentrations and stable isotopes of mercury in sharks of the Galapagos Marine Reserve: Human health concerns and feeding patterns.

The human ingestion of mercury (Hg) from sea food is of big concern worldwide due to adverse health effects, and more specifically if shark consumption constitutes a regular part of the human diet. In this study, the total mercury (THg) concentration in muscle tissue were determined in six sympatric shark species found in a fishing vessel seized in the Galapagos Marine Reserve in 2017. The THg concentrations in shark muscle samples (n = 73) varied from 0.

The Twilight Zone as a Major Foraging Habitat and Mercury Source for the Great White Shark.

The twilight zone contains the largest biomass of the world's ocean. Identifying its role in the trophic supply and contaminant exposure of marine megafauna constitutes a critical challenge in the context of global change. The white shark () is a threatened species with some of the highest concentrations of neurotoxin methylmercury (MeHg) among marine top predators.

Trophic resources and mercury exposure of two silvertip shark populations in the Northeast Pacific Ocean.

Worldwide shark populations have experienced rapid declines over the last decades, mainly due to overfishing. Marine protected areas (MPAs) have thus become an indispensable tool for the protection of these marine predators. Two recently-created MPAs in the Northeast Pacific Ocean, the Revillagigedo National Park and Clipperton Atoll, are characterized by different trophic structures potentially influencing the trophic niche and contaminant exposure of resident sharks in these two sites.

Stable isotope analyses revealed the influence of foraging habitat on mercury accumulation in tropical coastal marine fish.

Bioaccumulation of toxic metal elements including mercury (Hg) can be highly variable in marine fish species. Metal concentration is influenced by various species-specific physiological and ecological traits, including individual diet composition and foraging habitat. The impact of trophic ecology and habitat preference on Hg accumulation was analyzed through total Hg concentration and stable isotope ratios of carbon (δC) and nitrogen (δN) in the muscle of 132 fish belonging to 23 different species from the Senegalese coast (West Africa), where the marine ecosystem is submitted to nutrient inputs from various sources such as upwelling or rivers.

Significance of metallothioneins in differential cadmium accumulation kinetics between two marine fish species.

Impacted marine environments lead to metal accumulation in edible marine fish, ultimately impairing human health. Nevertheless, metal accumulation is highly variable among marine fish species. In addition to ecological features, differences in bioaccumulation can be attributed to species-related physiological processes, which were investigated in two marine fish present in the Canary Current Large Marine Ecosystem (CCLME), where natural and anthropogenic metal exposure occurs.

Trophic ecology influence on metal bioaccumulation in marine fish: Inference from stable isotope and fatty acid analyses.

The link between trophic ecology and metal accumulation in marine fish species was investigated through a multi-tracers approach combining fatty acid (FA) and stable isotope (SI) analyses on fish from two contrasted sites on the coast of Senegal, one subjected to anthropogenic metal effluents and another one less impacted. The concentrations of thirteen trace metal elements (As, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sn, U, and Zn) were measured in fish liver. Individuals from each site were classified into three distinct groups according to their liver FA and muscle SI compositions.

Characterization of pif, a gene required for the per os infectivity of Spodoptera littoralis nucleopolyhedrovirus.

During plaque purification of Spodoptera littoralis nucleopolyhedrovirus in S. littoralis Sl52 cell culture, a deletion mutant virus was isolated. Analysis of the biological properties of this mutant virus revealed an absence of per os infectivity of the occluded virus.

Diversity, distribution, and mobility of bro gene sequences in Bombyx mori nucleopolyhedrovirus.

Genetic differences between strains of a baculovirus are often limited to some restriction sites, short DNA deletions or absence of some nonessential genes. The recently coined bro gene family, represents a new major source of intraspecific variability. A comparison between two bro gene sets of Bombyx mori nucleopolyhedroviruses (NPV) shows that bro genes are distributed in three regions for the -T3 and -SC7 virus strains.

Comparative analysis of the granulin regions of the Phthorimaea operculella and Spodoptera littoralis granuloviruses.

The nucleotide sequence of two cloned restriction fragments encompassing the granulin genes from the granuloviruses of the potato tuber moth, Phthorimaea operculella, PhopGV, and the Egyptian cotton leaf worm, Spodoptera littoralis, SpliGV, have been determined. Although both viruses are able to infect the same Ph. operculella cell line, their granulins do not cluster in the same phylogenetic branches.

Protein requirements for assembly of virus-like particles of Junonia coenia densovirus in insect cells.

The coding sequences of four overlapping polypeptides starting at four different in-frame AUG codons and co-terminating at the stop codon of the cap gene of Junonia coenia densovirus (JcDNV) were inserted under the control of the p10 promoter of Autographa californica nucleopolyhedrovirus (AcMNPV) to generate AcMNPV-VP1 (four polypeptides), AcMNPV-VP2 (three polypeptides), AcMNPV-VP3 (two polypeptides), and AcMNPV-VP4 (one polypeptide) recombinant viruses. In all cases, infection of Spodoptera frugiperda cells (Sf9) by each of the four recombinant viruses resulted in the production of virus-like particles (VLPs) 22-25 nm in diameter. The VLPs produced by the three recombinants AcMNPV-VP2, AcMNPV-VP3 and AcMNPV-VP4 were abundant and contained three, two and one polypeptides, respectively.

Two key mutations in the host-range specificity domain of the p143 gene of Autographa californica nucleopolyhedrovirus are required to kill Bombyx mori larvae.

Autographa californica nucleopolyhedrovirus (AcMNPV) does not replicate in Bombyx mori cells (Bm5, BmN). We have shown previously that when a short DNA sequence within AcMNPV ORF95, which encodes the viral helicase P143, is replaced with the colinear region of B. mori nucleopolyhedrovirus (BmNPV), AcMNPV gains the ability to replicate in Bm5 cells.

The pnk/pnl gene (ORF 86) of Autographa californica nucleopolyhedrovirus is a non-essential, immediate early gene.

Autographa californica nucleopolyhedrovirus (AcMNPV) ORF 86, located within the HindIII C fragment, potentially encodes a protein which shares sequence similarity with two T4 bacteriophage gene products, RNA ligase and polynucleotide kinase. This AcMNPV gene has been designated pnk/pnl but has yet to be assigned a function in virus replication. It has been classified as an immediate early virus gene, since the promoter was active in uninfected insect cells and mRNA transcripts were detectable from 4 to 48 h post-infection and in the presence of cycloheximide or aphidicolin in virus-infected cells.

Temporal expression of the AcMNPV lef-4 gene and subcellular localization of the protein.

Autographa californica nucleopolyhedrovirus (AcMNPV) lef-4 gene [ORF 90; Ayres et al. (1994) Virology 202, 586-605] is involved in both late and very late gene expression [Passarelli and Miller (1993) Virology 197, 704-714]. The transcriptional properties of this gene have been analyzed.

Infection of a Spodoptera frugiperda cell line with Bombyx mori nucleopolyhedrovirus.

The interactions of Bombyx mori nucleopolyhedrovirus (BmNPV) with Spodoptera frugiperda cells (Sf9) were investigated. S. frugiperda cells are usually considered nonpermissive for BmNPV.

Nucleotide sequence of the polyhedrin gene of Spodoptera littoralis multiple nucleocapsid nuclear polyhedrosis virus.

1286 nt portion of the 3.1 kbp HindIII-K fragment of the Spodoptera littoralis multiple nucleocapsid nuclear polyhedrosis virus (SIMNPV) DNA genome has been sequenced. The sequence contains the polyhedrin gene preceded by a highly-repeated AGATAA-rich sequence.

Extension of Autographa californica nuclear polyhedrosis virus host range by interspecific replacement of a short DNA sequence in the p143 helicase gene.

Recombinant baculoviruses obtained by coinfection of insect cells with Autographa californica and Bombyx mori nuclear polyhedrosis viruses (AcNPV and BmNPV, respectively) possess a wider in vitro host range than either parent virus. To localize the DNA sequences responsible for this species specificity, we used a two-step method of production and selection of recombinant viruses with altered specificity. Sf9 cells, which are permissive for AcNPV, were first cotransfected with genomic AcNPV DNA and a complete or incomplete set of BmNPV restriction fragments.