Fitness reduction and potential extinction of wild populations of Atlantic salmon, Salmo salar, as a result of interactions with escaped farm salmon

The high level of escapes from Atlantic salmon farms, up to two million fishes per year in the North Atlantic, has raised concern about the potential impact on wild populations. We report on a two-generation experiment examining the estimated lifetime successes, relative to wild natives, of farm, F(1) and F(2) hybrids and BC(1) backcrosses to wild and farm salmon. Offspring of farm and "hybrids" (i.e. all F(1), F(2) and BC(1) groups) showed reduced survival compared with wild salmon but grew faster as juveniles and displaced wild parr, which as a group were significantly smaller. Where suitable habitat for these emigrant parr is absent, this competition would result in reduced wild smolt production. In the experimental conditions, where emigrants survived downstream, the relative estimated lifetime success ranged from 2% (farm) to 89% (BC(1) wild) of that of wild salmon, indicating additive genetic variation for survival. Wild salmon primarily returned to fresh water after one sea winter (1SW) but farm and 'hybrids' produced proportionately more 2SW salmon. However, lower overall survival means that this would result in reduced recruitment despite increased 2SW fecundity. We thus demonstrate that interaction of farm with wild salmon results in lowered fitness, with repeated escapes causing cumulative fitness depression and potentially an extinction vortex in vulnerable populations.     

Differential Regulation of Cellular Senescence and Differentiation by Prolyl Isomerase Pin1 in Cardiac Progenitor Cells

Autologous c-kit⁺ cardiac progenitor cells (CPCs) are currently used in the clinic to treat heart disease. CPC-based regeneration may be further augmented by better understanding molecular mechanisms of endogenous cardiac repair and enhancement of pro-survival signaling pathways that antagonize senescence while also increasing differentiation. The prolyl isomerase Pin1 regulates multiple signaling cascades by modulating protein folding and thereby activity and stability of phosphoproteins. In this study, we examine the heretofore unexplored role of Pin1 in CPCs. Pin1 is expressed in CPCs in vitro and in vivo and is associated with increased proliferation. Pin1 is required for cell cycle progression and loss of Pin1 causes cell cycle arrest in the G₁ phase in CPCs, concomitantly associated with decreased expression of Cyclins D and B and increased expression of cell cycle inhibitors p53 and retinoblastoma (Rb). Pin1 deletion increases cellular senescence but not differentiation or cell death of CPCs. Pin1 is required for endogenous CPC response as Pin1 knock-out mice have a reduced number of proliferating CPCs after ischemic challenge. Pin1 overexpression also impairs proliferation and causes G₂/M phase cell cycle arrest with concurrent down-regulation of Cyclin B, p53, and Rb. Additionally, Pin1 overexpression inhibits replicative senescence, increases differentiation, and inhibits cell death of CPCs, indicating that cell cycle arrest caused by Pin1 overexpression is a consequence of differentiation and not senescence or cell death. In conclusion, Pin1 has pleiotropic roles in CPCs and may be a molecular target to promote survival, enhance repair, improve differentiation, and antagonize senescence.     

Mitochondrial Analysis of the Most Basal Canid Reveals Deep Divergence between Eastern and Western North American Gray Foxes (Urocyon spp.) and Ancient Roots in Pleistocene California

Pleistocene aridification in central North America caused many temperate forest-associated vertebrates to split into eastern and western lineages. Such divisions can be cryptic when Holocene expansions have closed the gaps between once-disjunct ranges or when local morphological variation obscures deeper regional divergences. We investigated such cryptic divergence in the gray fox (Urocyon cinereoargenteus), the most basal extant canid in the world. We also investigated the phylogeography of this species and its diminutive relative, the island fox (U. littoralis), in California. The California Floristic Province was a significant source of Pleistocene diversification for a wide range of taxa and, we hypothesized, for the gray fox as well. Alternatively, gray foxes in California potentially reflected a recent Holocene expansion from further south. We sequenced mitochondrial DNA from 169 gray foxes from the southeastern and southwestern United States and 11 island foxes from three of the Channel Islands. We estimated a 1.3% sequence divergence in the cytochrome b gene between eastern and western foxes and used coalescent simulations to date the divergence to approximately 500,000 years before present (YBP), which is comparable to that between recognized sister species within the Canidae. Gray fox samples collected from throughout California exhibited high haplotype diversity, phylogeographic structure, and genetic signatures of a late-Holocene population decline. Bayesian skyline analysis also indicated an earlier population increase dating to the early Wisconsin glaciation (~70,000 YBP) and a root height extending back to the previous interglacial (~100,000 YBP). Together these findings support California’s role as a long-term Pleistocene refugium for western Urocyon. Lastly, based both on our results and re-interpretation of those of another study, we conclude that island foxes of the Channel Islands trace their origins to at least 3 distinct female founders from the mainland rather than to a single matriline, as previously suggested.     

The digestive gland of the Southern Dumpling Squid (Euprymna tasmanica): structure and function

The cephalopod digestive gland plays an important role in the efficient assimilation of nutrients and therefore the fast growth of the animal. The histological and enzymatic structure of Euprymna tasmanica was studied and used in this experiment to determine the dynamics of the gland in response to feeding. The major roles of the digestive gland were secretion of digestive enzymes in spherical inclusions (boules) and excretion of metabolic wastes in brown body vacuoles. High levels of trypsin, chymotrypsin and α-amylase, low levels of α-glucosidase and negligible carboxypeptidase activity were produced by the gland. There was no evidence of secretion of digestive enzymes in other organs of the digestive tract. Within 60 min of a feeding event, the gland produced increasing numbers of boules to replace those lost from the stomach during the feeding event. Initially, small boules were seen in the digestive cells, they increased in size until they are released into the lumen of the gland where they are transported to the stomach. There was no evidence of an increase in activity of digestive enzymes following a feeding event, despite structural changes in the gland. However, there was large variation among individuals in the level of digestive enzyme activity. A negative correlation between boule and brown body vacuole density suggested that the large variation in enzyme activity may be due to the digestive gland alternating between enzyme production and excretion.     

Aerobic exercise training reduces cannabis craving and use in non-treatment seeking cannabis-dependent adults

Background

Cannabis dependence is a significant public health problem. Because there are no approved medications for this condition, treatment must rely on behavioral approaches empirically complemented by such lifestyle change as exercise.

Aims

To examine the effects of moderate aerobic exercise on cannabis craving and use in cannabis dependent adults under normal living conditions.

Design

Participants attended 10 supervised 30-min treadmill exercise sessions standardized using heart rate (HR) monitoring (60–70% HR reserve) over 2 weeks. Exercise sessions were conducted by exercise physiologists under medical oversight.

Participants

Sedentary or minimally active non-treatment seeking cannabis-dependent adults (n = 12, age 25±3 years, 8 females) met criteria for primary cannabis dependence using the Substance Abuse module of the Structured Clinical Interview for DSM-IV (SCID).

Measurements

Self-reported drug use was assessed for 1-week before, during, and 2-weeks after the study. Participants viewed visual cannabis cues before and after exercise in conjunction with assessment of subjective cannabis craving using the Marijuana Craving Questionnaire (MCQ-SF).

Findings

Daily cannabis use within the run-in period was 5.9 joints per day (SD = 3.1, range 1.8–10.9). Average cannabis use levels within the exercise (2.8 joints, SD = 1.6, range 0.9–5.4) and follow-up (4.1 joints, SD = 2.5, range 1.1–9.5) periods were lower than during the run-in period (both P<.005). Average MCQ factor scores for the pre- and post-exercise craving assessments were reduced for compulsivity (P  = .006), emotionality (P  = .002), expectancy (P  = .002), and purposefulness (P  = .002).

Conclusions

The findings of this pilot study warrant larger, adequately powered controlled trials to test the efficacy of prescribed moderate aerobic exercise as a component of cannabis dependence treatment. The neurobiological mechanisms that account for these beneficial effects on cannabis use may lead to understanding of the physical and emotional underpinnings of cannabis dependence and recovery from this disorder.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00838448","term_id":"NCT00838448"}}NCT00838448]     

A new method to study changes in microvascular blood volume in muscle and adipose tissue: real-time imaging in humans and rat

We employed and evaluated a new application of contrast-enhanced ultrasound for real-time imaging of changes in microvascular blood volume (MBV) in tissues in females, males, and rat. Continuous real-time imaging was performed using contrast-enhanced ultrasound to quantify infused gas-filled microbubbles in the microcirculation. It was necessary to infuse microbubbles for a minimum of 5-7 min to obtain steady-state bubble concentration, a prerequisite for making comparisons between different physiological states. Insulin clamped at a submaximal concentration (～75 μU/ml) increased MBV by 27 and 39% in females and males, respectively, and by 30% in female subcutaneous adipose tissue. There was no difference in the ability of insulin to increase muscle MBV in females and males, and microvascular perfusion rate was not increased significantly by insulin. However, perfusion rate of the microvascular space was higher in females compared with males. In rats, insulin clamped at a maximal concentration increased muscle MBV by 60%. Large increases in microvascular volume and perfusion rate were detected during electrical stimulation of muscle in rats and immediately after exercise in humans. We have demonstrated that real-time imaging of changes in MBV is possible in human and rat muscle and in subcutaneous adipose tissue and that the method is sensitive enough to pick up relatively small changes in MBV when performed with due consideration of steady-state microbubble concentration. Because of real-time imaging, the method has wide applications for determining MBV in different organs during various physiological or pathophysiological conditions.     

The behavioral immune system and social conservatism: a meta-analysis

The behavioral immune system (BIS) is a cluster of psychological mechanisms (e.g., disgust) that have evolved to promote disease-avoidance (Schaller M. (2006). Parasites, behavioral defenses, and the social psychological mechanisms through which cultures are evoked. Psychological Inquiry, 17, 96–101). Recent evidence suggests that the BIS may promote avoidance of outgroup members, an historical source of contamination, by evoking social conservatism (Terrizzi JA Jr, Shook NJ, & Ventis WL. (2010). Disgust: A predictor of social conservatism and prejudicial attitudes toward homosexuals. Personality and Individual Differences, 49, 587–592; Terrizzi J, Shook N, Ventis L. (2012). Religious conservatism: An evolutionarily evoked disease-avoidance strategy. Religion, Brain & Behavior, 2, 105–120.). That is, the BIS mechanisms may encourage the endorsement of socially conservative beliefs, which promote social exclusivity, tradition, and negativity toward outgroups. The current study provides a systematic review and meta-analysis of 24 studies to evaluate the hypothesis that the BIS is predictive of social conservatism. The results indicate that behavioral immune strength, as indicated by fear of contamination and disgust sensitivity, is positively related to social conservatism (i.e., right-wing authoritarianism, social dominance orientation, religious fundamentalism, ethnocentrism, collectivism, and political conservatism). These findings provide initial evidence that socially conservative values may function as evolutionarily evoked disease-avoidance strategies.     

Testing for size and allometric differences in fossil hominin body mass estimation

Body size reconstructions of fossil hominins allow us to infer many things about their evolution and lifestyle, including diet, metabolic requirements, locomotion, and brain/body size relationships. The importance of these implications compels anthropologists to attempt body mass estimation from fragmentary fossil hominin specimens. Most calculations require a known “calibration” sample usually composed of modern humans or other extant apes. Caution must be taken in these analyses, as estimates are sensitive to overall size and allometric differences between the fossil hominin and the reference sample. Am J Phys Anthropol 151:215–229, 2013. © 2013 Wiley Periodicals, Inc.