Characteristics and fate of plastic pollution in urban stormwater ponds.

Stormwater runoff is often assumed to be an important pathway for microplastics from the terrestrial to the marine environment, although few studies have attempted to quantify the significance of this pathway or the interactions between stormwater infrastructure and plastic pollution. The objective of this study was to determine what factors influence the concentrations and behaviors of microplastics in stormwater ponds. Samples were taken from the water and bottom sediments of six stormwater ponds in Tampa (Florida, USA) using a neuston net and a sediment dredger. They were processed using a combination of density separations, visual sorting, and Raman spectroscopy. Concentrations ranged by several orders of magnitude between sites and rounds of sampling (0.0-55.5 items/m3 in water, 2.5-203.0 items/kg dry weight in sediment) but were comparable to other studies. The sediments of fenced and residential sites had significantly lower plastic count concentrations, compared to unfenced sites with mixed land uses. The ratio of impervious drainage area to pond surface area was found to be positively correlated with sediment concentrations. Particle shapes in water were more variable than those found in sediments, suggesting that regular-shaped plastics tend to settle first. Circularity was identified as an important parameter in determining settling behaviors. Shape characteristics were similar to those observed in a downstream river, suggesting that degradation leading to the observed shapes occurred prior to entering the ponds. This study highlights the importance of stormwater infrastructure in understanding plastic transport and how plastic shape characteristics can impact their behavior in the environment.

Effects of chronic oxytocin on attention to dynamic facial expressions in infant macaques.

Studies in a variety of species have reported enhanced prosocial effects after an acute administration of the neuromodulating hormone, oxytocin (OT). Although the exact mechanisms underlying these effects are not fully understood, there is broad interest in developing OT into a treatment for social deficits. Only a few studies, however, have examined the effects of OT if given repeatedly during early development, the period when early intervention is likely to have the greatest benefits for reversing the progression towards social impairment. Those studies, exclusively in rodents, report mixed results. Some have shown enhancement of prosocial behavior, including increased social exploration, but others have shown anti-social effects, including increased aggression. In the present study, infant rhesus macaques were treated with a high-frequency (3× per week) or low-frequency (1× per week) dose of intranasal oxytocin (IN-OT) or placebo (IN-saline) between two and six months of age, after which their reactions to dynamic facial expressions (neutral, lipsmacking and threats) were measured. Results showed that IN-OT, compared to placebo, increased the time monkeys spent viewing the expression videos, but selectively reduced attention to the eyes in neutral faces in a dose dependent manner. The mechanism for this non-prosocial effect may be that repeated IN-OT administration down-regulates the expression of OT receptors in brain regions important for regulating social attention. Consequently, our results raise questions about the efficacy of implementing chronic IN-OT as a pharmacotherapy for the treatment of social deficits, particularly if given early in development. More work is needed, not only to identify optimal treatment schedules, but also to understand how IN-OT exerts its influences on the brain and behavior.

The development of visual preferences for direct versus averted gaze faces in infant macaques (Macaca mulatta).

Human and nonhuman primates show a preference for looking at faces with direct gaze. In humans, this preference emerges shortly after birth, but little is known about the development of gaze preferences in monkeys. This study tracked the development of gaze preferences in infant monkeys from birth through 6 months of age using infrared eye-tracking. Although absent in the first week, a strong significant preference for direct compared to averted gaze faces emerged rapidly, peaking around 2 months of age. When looking at the eyes, the monkeys' fixations were equivalent in duration for both gaze types in the first 2 months, but thereafter remained longer for the averted gaze faces. Therefore, the infants spent a greater proportion of time overall, but made shorter fixations, when looking at the direct compared to averted gaze faces. These results suggest that monkeys develop an efficient strategy when viewing the preferred direct gaze faces that involves longer viewing times, but shorter fixations.

Establishing the reliability of rhesus macaque social network assessment from video observations.

Understanding the properties of a social environment is important for understanding the dynamics of social relationships. Understanding such dynamics is relevant for multiple fields, ranging from animal behaviour to social and cognitive neuroscience. To quantify social environment properties, recent studies have incorporated social network analysis. Social network analysis quantifies both the global and local properties of a social environment, such as social network efficiency and the roles played by specific individuals, respectively. Despite the plethora of studies incorporating social network analysis, methods to determine the amount of data necessary to derive reliable social networks are still being developed. Determining the amount of data necessary for a reliable network is critical for measuring changes in the social environment, for example following an experimental manipulation, and therefore may be critical for using social network analysis to statistically assess social behaviour. In this paper, we extend methods for measuring error in acquired data and for determining the amount of data necessary to generate reliable social networks. We derived social networks from a group of 10 male rhesus macaques, Macaca mulatta, for three behaviours: spatial proximity, grooming and mounting. Behaviours were coded using a video observation technique, where video cameras recorded the compound where the 10 macaques resided. We collected, coded and used 10 h of video data to construct these networks. Using the methods described here, we found in our data that 1 h of spatial proximity observations produced reliable social networks. However, this may not be true for other studies due to differences in data acquisition. Our results have broad implications for measuring and predicting the amount of error in any social network, regardless of species.

Resetting the transcription factor network reverses terminal chronic hepatic failure.

The cause of organ failure is enigmatic for many degenerative diseases, including end-stage liver disease. Here, using a CCl4-induced rat model of irreversible and fatal hepatic failure, which also exhibits terminal changes in the extracellular matrix, we demonstrated that chronic injury stably reprograms the critical balance of transcription factors and that diseased and dedifferentiated cells can be returned to normal function by re-expression of critical transcription factors, a process similar to the type of reprogramming that induces somatic cells to become pluripotent or to change their cell lineage. Forced re-expression of the transcription factor HNF4α induced expression of the other hepatocyte-expressed transcription factors; restored functionality in terminally diseased hepatocytes isolated from CCl4-treated rats; and rapidly reversed fatal liver failure in CCl4-treated animals by restoring diseased hepatocytes rather than replacing them with new hepatocytes or stem cells. Together, the results of our study indicate that disruption of the transcription factor network and cellular dedifferentiation likely mediate terminal liver failure and suggest reinstatement of this network has therapeutic potential for correcting organ failure without cell replacement.

A nonhuman primate model of human radiation-induced venocclusive liver disease and hepatocyte injury.

BACKGROUND: Human liver has an unusual sensitivity to radiation that limits its use in cancer therapy or in preconditioning for hepatocyte transplantation. Because the characteristic veno-occlusive lesions of radiation-induced liver disease do not occur in rodents, there has been no experimental model to investigate the limits of safe radiation therapy or explore the pathogenesis of hepatic veno-occlusive disease. METHODS AND MATERIALS: We performed a dose-escalation study in a primate, the cynomolgus monkey, using hypofractionated stereotactic body radiotherapy in 13 animals. RESULTS: At doses ≥40 Gy, animals developed a systemic syndrome resembling human radiation-induced liver disease, consisting of decreased albumin, elevated alkaline phosphatase, loss of appetite, ascites, and normal bilirubin. Higher radiation doses were lethal, causing severe disease that required euthanasia approximately 10 weeks after radiation. Even at lower doses in which radiation-induced liver disease was mild or nonexistent, latent and significant injury to hepatocytes was demonstrated by asialoglycoprotein-mediated functional imaging. These monkeys developed hepatic failure with encephalopathy when they received parenteral nutrition containing high concentrations of glucose. Histologically, livers showed central obstruction via an unusual intimal swelling that progressed to central fibrosis. CONCLUSIONS: The cynomolgus monkey, as the first animal model of human veno-occlusive radiation-induced liver disease, provides a resource for characterizing the early changes and pathogenesis of venocclusion, for establishing nonlethal therapeutic dosages, and for examining experimental therapies to minimize radiation injury.