Long-Term Pyrene Exposure of Grass Shrimp, \u3ci\u3ePalaemonetes pugio\u3c/i\u3e, Affects Molting and Reproduction of Exposed Males and Offspring of Exposed Females

The objective of this study was to investigate the impact of long-term pyrene exposure on molting and reproduction in the model estuarine invertebrate, the grass shrimp (Palaemonetes pugio). Grass shrimp were exposed to measured concentrations of 5.1, 15.0, and 63.4 ppb (mu g/L) pyrene for 6 weeks, during which time we determined molting and survivorship. At the end of the exposure, we immediately sacrificed some of the shrimp for biomarker (CYP1A and vitellin) analyses. The remaining shrimp were used to analyze fecundity and embryo survivorship during an additional 6 weeks after termination of pyrene exposure. Male shrimp at the highest pyrene dose (63 ppb) experienced a significant delay in molting and in time until reproduction, and showed elevated ethoxycoumarin o-deethylase (ECOD) activity immediately after the 6-week exposure period. In contrast, 63 ppb pyrene did not affect these parameters in female shrimp. Females produced the same number of eggs per body weight, with high egg viability (98-100%) at all exposure levels, but with decreased survival for the offspring of the 63-ppb pyrene-exposed females. In addition, vitellin levels were elevated only in females at 63 ppb pyrene after the 6-week exposure. We hypothesize that the elevated vitellin binds pyrene and keeps it biologically unavailable to adult females, resulting in maternal transfer of pyrene to the embryos. This would account for the lack of effect of pyrene exposure on ECOD activity, molting, and reproduction in the adult females, and for reduced survival of their offspring

Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles

Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) throughout their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nanomaterials. Information about safety and potential hazards is urgently needed. Results of older bio-kinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract. The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels. Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species. Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need for basic research on their interactions with subcellular structures. Additional considerations for assessing safety of engineered NSPs include careful selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and also the benefits of possible desirable effects. An interdisciplinary team approach (e.g., toxicology, materials science, medicine, molecular biology, and bioinformatics, to name a few) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment

In Caenorhabditis elegans Nanoparticle-Bio-Interactions Become Transparent: Silica-Nanoparticles Induce Reproductive Senescence

While expectations and applications of nanotechnologies grow exponentially, little is known about interactions of engineered nanoparticles with multicellular organisms. Here we propose the transparent roundworm Caenorhabditis elegans as a simple but anatomically and biologically well defined animal model that allows for whole organism analyses of nanoparticle-bio-interactions. Microscopic techniques showed that fluorescently labelled nanoparticles are efficiently taken up by the worms during feeding, and translocate to primary organs such as epithelial cells of the intestine, as well as secondary organs belonging to the reproductive tract. The life span of nanoparticle-fed Caenorhabditis elegans remained unchanged, whereas a reduction of progeny production was observed in silica-nanoparticle exposed worms versus untreated controls. This reduction was accompanied by a significant increase of the ‘bag of worms’ phenotype that is characterized by failed egg-laying and usually occurs in aged wild type worms. Experimental exclusion of developmental defects suggests that silica-nanoparticles induce an age-related degeneration of reproductive organs, and thus set a research platform for both, detailed elucidation of molecular mechanisms and high throughput screening of different nanomaterials by analyses of progeny production

Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles-3

<p><b>Copyright information:</b></p><p>Taken from "Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles"</p><p>Environmental Health Perspectives 2005;113(7):823-839.</p><p>Published online 22 Mar 2005</p><p>PMCID:PMC1257642.</p><p>This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original DOI.</p

Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles-11

<p><b>Copyright information:</b></p><p>Taken from "Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles"</p><p>Environmental Health Perspectives 2005;113(7):823-839.</p><p>Published online 22 Mar 2005</p><p>PMCID:PMC1257642.</p><p>This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original DOI.</p

Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles-10

<p><b>Copyright information:</b></p><p>Taken from "Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles"</p><p>Environmental Health Perspectives 2005;113(7):823-839.</p><p>Published online 22 Mar 2005</p><p>PMCID:PMC1257642.</p><p>This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original DOI.</p