The impact of polystyrene microplastics on feeding, function and fecundity in the marine copepod Calanus helgolandicus.

In marine food webs, copepods are the major producers of a carotenoid pigment astaxanthin, which is an important antioxidant. The availability of astaxanthin for higher trophic levels can be affected by changes in phytoplankton stocks and copepod feeding; however, the functional relationship between food availability and astaxanthin production is poorly understood. We hypothesized that with a given food type and quality, astaxanthin content in copepods is positively related to feeding and egg production rates. The hypothesis was tested by measuring astaxanthin accumulation in concert with ingestion and egg production rates in the copepod Acartia bifilosa exposed to different algal concentrations (Tetraselmis suecica; 0 to 1200 μg C L−1). Egg production and ingestion rates increased with increasing food availability and reached a plateau at ≥400–600 μg C L−1. In contrast, increasing accumulation of astaxanthin with increasing food availability was observed only at concentrations ≤150 μg C L−1. Contrary to our hypothesis, at 600–1200 μg C L−1 copepods had maximal ingestion and egg production rates, but low astaxanthin contents. It is suggested that this low accumulation of astaxanthin at high food concentrations results from a food-dependant decrease in assimilation efficiency. These findings are important for the understanding of astaxanthin dynamics within marine food webs, where increases in phytoplankton biomass may translate to a trade-off between zooplankton quantity and its nutritional quality for zooplanktivores.

同粒径聚苯乙烯微塑料(polystyrene microplastics, PS-MPs)联合苯并(a)芘(benzo(a)pyrene, BaP)暴露, 对成年斑马鱼

Many suspension-feeding copepods show omnivorous feeding behavior. However, the relative contribution to egg production of herbivorous and heterotrophic feeding in copepods remains an open question. In this study, we quantified pigment ingestion rates and egg production rates of the planktonic calanoid copepod Acartia tonsa from July to November of 1986 in Long Island Sound, a large temperate estuary. Pigment ingestion and egg production rates were better correlated to the > 10-µm chlorophyll size fraction than total chlorophyll. Maximum pigment ingestion and egg production rates were observed during the fall bloom in September. Pigment ingestion and egg production rates were linearly related. However, pigment ingestion rates accounted for only 48% of the variance in egg production rates. If female A. tonsa had fed entirely as herbivores over the course of the season, the observed gross efficiency of egg production, K'1 = egg production rate/pigment ingestion rate, in terms of nitrogen, would have been 0.68. This growth efficiency is considerably higher than the expected value, K 1 = 0.38, for this species based on laboratory studies of herbivorous feeding. We suggest that the ratio H = K 1/K' 1 is a measure of the fraction of egg production that is due to herbivorous feeding. Thus, we infer that herbivory accounted for 56% (0.38/0.68) of egg production in A. tonsa in this study. The ratio H is an useful tool in examining the relative contribution to egg production of herbivorous and heterotrophic feeding in copepods.

The crucial role of heavy metals on the interaction of engineered nanoparticles with polystyrene microplastics

The effects of microwave radiation and conventional heating on the reproductive processes in Drosophila melanogaster were investigated. The egg production of females exposed to heat and females exposed to microwave radiation was significantly reduced when compared to their respective sham. The egg production of these females was not significantly different when compared to each other. There was a significant difference in survival of eggs laid by both the heat-exposed and the microwave-irradiated females when compared to their respective sham. In the heat-exposed group, the surviral was significantly greater than that of their. The microwave-irradiated group showed the opposite effect--a significant decrease in survival when compared to their respective shams. Both groups showed a significant difference in egg survival when compared to each other. Egg production and survival of eggs laid by normal females mated to treated males was not significantly different in either the heat-treated or the microwave-irradiated groups, nor was either group significantly different when compared to their respective shams.

First Demonstration of the FLASH Effect With Ultrahigh Dose-Rate High-Energy X-Rays

Microplastic (MP) pollution is a critical planetary boundary threat. Once released into aquatic environments, MPs become rapidly colonized by microbial assemblages forming biofilm communities collectively known as the “plastisphere”. Diatoms are early colonizers and often outcompete other primary producers onto MPs. Although diatoms drive synthesis of many different bioactive secondary metabolites, such as oxylipins, little is known about how diatom-derived chemicals could affect MP-associated community dynamics or even responses of organisms ingesting MPs. Copepods, pivotal components of pelagic ecosystems, can passively entrain MPs into their feeding currents and thus ingest the particles overlapping in size with natural preys such as diatoms, dinoflagellates and ciliates. Ingestion of MPs can alter copepod feeding behavior, reproductive output, hatching success, and finally disrupt carbon export through modified fecal pellet production. Interestingly, these effects largely resemble those historically described after exposure of adult copepod females to oxylipin-producing diatoms. Considering that several diatom genera colonizing MPs are also reported as oxylipin producers, our review proposes a conceptual framework in which MPs not only may cause physical and nutritional stress to copepods but also mediate chemical stress through their epiplastic diatoms. Potential oxylipin synthesis following ingestion of diatom-colonized MPs could multiply the negative impacts of MPs on copepod fitness, with cascading effects at the population level possibly extending to trophic dynamics and carbon cycling. Future research should focus on quantifying oxylipin production in epiplastic biofilms, and on experimental assays comparing copepod responses to sterile versus diatom-colonized MPs to clarify the ecological relevance of these combined stressors.

Changes in expression of stress genes in copepods feeding upon a non-brevetoxin-producing strain of the dinoflagellate Karenia brevis

Copepods are important components of marine ecosystems. Understanding copepod population dynamics can help interpret variations in both primary producers and higher trophic levels. Egg production, stage duration, and stage-specific mortality rates are key parameters describing copepod population dynamics. Estimation of stage-specific mortality is complicated due to a complex life history, patchiness, and sampling biases. This study was undertaken to quantify the population dynamics of the copepod Clausocalanus furcatus in the northern Gulf of Mexico and to assess the utility of available mortality estimation methods in a highly advective environment. Zooplankton samples were taken every 12h from March 18-April 6, and May 15-June 9, 2003 from an offshore petroleum platform using a 153μm net and a 30L Niskin bottle to characterize the mesozooplankton assemblage. Incubation experiments were conducted during June-July 2002, March-April 2003, and May-June 2003 to measure egg production rates and stage durations. Stage-specific mortality rates were estimated using the horizontal life table (HTL), vertical life table (VTL), quadratic programming method (QPM) and inverse matrix method (IMM). Mesozooplankton communities in the study area were influenced by the Mississippi River plume. Field estimates of the mean egg production rate of C. furcatus were lower than measurements from lab incubation experiments. Egg production rates did not appear to be limited by food availability. A complete generation time ranged from ~13-20d. Early naupliar stages had shorter durations than late copepodite stages. Comparisons among HTL, VTL, QPM and IMM showed that the HTL and VTL had the disadvantage of producing negative mortality estimates, while the QPM likely overestimated mortality rates. Simulation experiments indicated that variability in stage abundances was a key factor affecting estimates of copepod mortality by the QPM and IMM techniques. Neither the QPM nor the IMM performed well when stage abundance variability was high. IMM estimates of instantaneous egg mortality rates were 1.30d-1 in March-April and 1.60d-1 in May-June. While instantaneous mortality rates for NI-CCIV stages ranged from 0.02 to 0.18d-1. Simulated populations using the mortality rates estimated from the IMM technique were consistent with observed field population trajectories.

Salmonid eggs are known to be sensitive to physical shock at certain stages of development. Survivability of the eggs is unknown when incubating under natural conditions and subjected to the seismic shock of underground nuclear detonations. Rainbow trout eggs were incubated to various stages of development (37.5, 75, 125 or 250 Temperature Units) in simulated redds and subjected to five sequential physical shocks of either 1, 2, 5 or 10 g. Eggs were then allowed to continue incubation to hatch or near hatch. Results indicated no significant difference in survival of eggs subjected to physical shocks of these four magnitudes at the various developmental stages when compared to eggs subjected to no shock. There was no significant difference in egg survival after shocking at 8.2 C (47 F) or at 11.1 C (52 F).

Microplastics have become emerging contaminants, causing widespread concern about their potential toxic effects. In this study, the uptake and tissue accumulation of polystyrene microplastics (PS-MPs) in zebrafish were detected, and the toxic effects in liver were investigated. The results showed that after 7 days of exposure, 5 μm diameter MPs accumulated in fish gills, liver, and gut, while 20 μm diameter MPs accumulated only in fish gills and gut. Histopathological analysis showed that both 5 μm and 70 nm PS-MPs caused inflammation and lipid accumulation in fish liver. PS-MPs also induced significantly increased activities of superoxide dismutase and catalase, indicating that oxidative stress was induced after treatment with MPs. In addition, metabolomic analysis suggested that exposure to MPs induced alterations of metabolic profiles in fish liver and disturbed the lipid and energy metabolism. These findings provide new insights into the toxic effects of MPs on fish.

Mechanisms underlying mitochondrial dysfunction and intestinal damage induced by ingestion of microplastics in Leuciscus waleckii: The role of the NF-κB/Nrf2 signaling pathway

Survival after radiotherapy vs. radical prostatectomy for unfavorable intermediate-risk prostate cancer

Background: Primary rectal malignant melanoma is an exceptionally rare neoplasm associated with an extremely poor prognosis despite aggressive treatment. The described management options for localized disease are abdominoperineal resection (APR) and wide local excision (WLE) with or without radiation. Objective: To assess the surgical outcomes of the patients with anorectal melanoma. Design and Setting: Retrospective study. Patients and Methods: This retrospective study describes the experience in surgical management of 18 cases of anorectal melanoma treated surgically at our center, between 2010 and 2015. Main Outcome Measures: To assess the median survival and recurrence rates of anorectal melanoma patients who underwent surgery. Sample size: Eighteen cases. Results: This is a retrospective study of 18 cases of anorectal melanoma. APR was performed in 77.8%, wide excision (WLE) in 16.7%, and posterior exenteration in 5.6%. The median survival of patients undergoing APR was 14.66 months and median survival of patients undergoing WLE was 18 months. No significant difference in median survival was observed in the patients undergoing abdominoperineal resection (APR) or wide local excision (P = 0.168). A significant difference in median survival between the node negative group and node positive group was observed (17 months vs 13.4 months P = 0.019). The median survival of patients with stage I, II, and III cancers were 17.28 months, 16 months, and 13.4 months, respectively. A statistically significant difference in median survival was found between patients with lympho-vascular invasive and noninvasive cancer (13.37 months vs 16.7 months P = 0.029). There was no significant difference in the recurrence rate between APR and WLE groups (86% vs 66% P = 0.893).Conclusion: Anorectal melanoma is an aggressive disease which require timely diagnosis. Nodal status is an important factor that impact median survival. There is no significant difference in survival when WLE compared to APR. Node positivity and lympho-vascular invasion confer poor prognosis. Recurrence rates are identical regardless of the surgical approach. Limitations: It is a retrospective series based on case records. A major drawback of this investigation is the limited detail available for each case. Not all patients who underwent local excision received radiotherapy. Conflict of Interest: None.

Chronic exposure to polystyrene microplastics induced LHR reduction and decreased testosterone levels through NF-κB pathway