A randomized controlled trial to compare the effects of time-restricted eating versus Mediterranean diet on symptoms and quality of life in bipolar disorder.

BACKGROUND: The primary objective of this randomized controlled trial (RCT) is to establish the effectiveness of time-restricted eating (TRE) compared with the Mediterranean diet for people with bipolar disorder (BD) who have symptoms of sleep disorders or circadian rhythm sleep-wake disruption. This work builds on the growing evidence that TRE has benefits for improving circadian rhythms. TRE and Mediterranean diet guidance will be offered remotely using self-help materials and an app, with coaching support. METHODS: This study is an international RCT to compare the effectiveness of TRE and the Mediterranean diet. Three hundred participants will be recruited primarily via social media. Main inclusion criteria are: receiving treatment for a diagnosis of BD I or II (confirmed via DIAMOND structured diagnostic interview), endorsement of sleep or circadian problems, self-reported eating window of ≥ 12 h, and no current mood episode, acute suicidality, eating disorder, psychosis, alcohol or substance use disorder, or other health conditions that would interfere with or limit the safety of following the dietary guidance. Participants will be asked to complete baseline daily food logging for two weeks and then will be randomly allocated to follow TRE or the Mediterranean diet for 8 weeks, during which time, they will continue to complete daily food logging. Intervention content will be delivered via an app. Symptom severity interviews will be conducted at baseline; mid-intervention (4 weeks after the intervention begins); end of intervention; and at 6, 9, and 15 months post-baseline by phone or videoconference. Self-rated symptom severity and quality of life data will be gathered at those timepoints, as well as at 16 weeks post baseline. To provide a more refined index of whether TRE successfully decreases emotional lability and improves sleep, participants will be asked to complete a sleep diary (core CSD) each morning and complete six mood assessments per day for eight days at baseline and again at mid-intervention. DISCUSSION: The planned research will provide novel and important information on whether TRE is more beneficial than the Mediterranean diet for reducing mood symptoms and improving quality of life in individuals with BD who also experience sleep or circadian problems. TRIAL REGISTRATION: ClinicalTrials.gov ID NCT06188754.

Methamphetamine effects in zebrafish (Danio rerio) depend on behavioral endpoint, dose and test session duration.

Research using zebrafish (Danio rerio) has begun to provide novel information in many fields, including the behavioral pharmacology of drug use and misuse. There have been limited studies on the effects of methamphetamine in adult zebrafish and the parameters of exposure (dose, test session length) have not been well-documented. Behavior following drug exposure is generally measured during relatively short sessions (6-10 min is common) in a novel tank environment. Many procedural variables (isolation, netting, novel tank) elicit anxiety-like behavior that is most apparent during the initial portion of a test session. This anxiety-like behavior might mask the initial effects of methamphetamine. During longer test sessions, these anxiety-like responses would be expected to habituate and drug effects should become more apparent. To test this idea, we measured several locomotor activity responses for 50-min following a range of methamphetamine doses (0.1-3.0 mg/L via immersion in methamphetamine solution). Methamphetamine failed to alter swimming velocity, distance travelled, or freezing time. In contrast, methamphetamine produced a dose-dependent decrease in time spent in the bottom of the tank, an increase in the number of visits to the top of the tank, and an increase in the number of transitions along the sides of the tank. The effects of methamphetamine were apparent 10-20 min following exposure and generally persisted throughout the session. These findings indicate that longer test sessions are required to measure methamphetamine-induced changes in behavior in zebrafish, as has been shown in other laboratory animals. The results also suggest that anxiety-like responses associated with various procedural aspects (netting, isolation, novel test apparatus) likely interfere with the ability to observe many behavioral effects of methamphetamine in zebrafish. Based on the current results, habituation to testing procedures to reduce anxiety-like behaviors is recommended in determining the effects of methamphetamine in zebrafish.

Urged to feel certain again: The role of emotion-related impulsivity on the relationships between intolerance of uncertainty and OCD symptom severity.

OBJECTIVES: Obsessive-compulsive disorder (OCD) is a debilitating mental disorder characterized by persistent and intrusive thoughts accompanied by repetitive mental or physical acts. While both intolerance of uncertainty and emotion-related impulsivity have been consistently evidenced as cognitive risk factors of OCD, no studies have considered their joint effects. The current study examined the interaction between intolerance of uncertainty and two forms of emotion-related impulsivity-including both a behavioural and cognitive form-in predicting OCD symptoms. DESIGN: Cross-sectional data were collected online from community-based adult participants. METHODS: Participants (N = 673) completed a battery of self-report measures of OCD symptom severity, intolerance of uncertainty, and emotion-related impulsivity. RESULTS: The behavioural form of emotion-related impulsivity positively moderated the relationship between intolerance of uncertainty and OCD symptoms. Elevated levels of both factors predicted the most severe symptoms, particularly checking, washing, and obsessing. This interaction effect was not found for the cognitive form of emotion-related impulsivity, which still emerged as a unique predictor of OCD symptom severity, specifically obsessing symptoms. CONCLUSIONS: Current findings furthered the understanding of the link between intolerance of uncertainty and OCD symptoms by highlighting the role of emotion-related impulsivity. When uncertainty triggers distress in individuals with high intolerance of uncertainty, the urge to behaviourally alleviate this distress could promote the use of maladaptive obsessions and compulsions, leading to greater OCD symptoms. Results also indicated the potentially differential effects from the behavioural versus cognitive forms of emotion-related impulsivity on different symptom domains, and the mechanistic link here is worthy of further investigation.

Emotion-related impulsivity is related to orbitofrontal cortical sulcation.

Background: Emotion-related impulsivity (ERI) describes the trait-like tendency toward poor self-control when experiencing strong emotions. ERI has been shown to be elevated across psychiatric disorders and predictive of the onset and worsening of psychiatric syndromes. Recent work has correlated ERI scores with the neuroanatomy of the orbitofrontal cortex (OFC). Informed by a growing body of research indicating that the morphology of cortical folds (sulci) can produce insights into behavioral outcomes, the present study modeled the association between ERI and the sulcal morphology of OFC at a finer scale than previously conducted. Methods: Analyses were conducted in a transdiagnostic sample of 118 individuals with a broad range of psychiatric syndromes. We first manually defined over 2000 sulci across the 118 participants. We then implemented a model-based LASSO regression to relate OFC sulcal morphology to ERI and test whether effects were specific to ERI as compared to non-emotion-related impulsivity. Results: The LASSO regression revealed bilateral associations of ERI with the depth of eight OFC sulci. These effects were specific to ERI and were not observed in non-emotion-related impulsivity. In addition, we identified a new transverse component of the olfactory sulcus in every hemisphere that is dissociable from the longitudinal component based on anatomical features and correlation with behavior, which could serve as a new transdiagnostic biomarker. Conclusions: The results of this data-driven investigation provide greater neuroanatomical and neurodevelopmental specificity on how OFC is related to ERI. As such, findings link neuroanatomical characteristics to a trait that is highly predictive of psychopathology.

Meta-analysis shows no consistent evidence for senescence in ejaculate traits across animals.

Male reproductive traits such as ejaculate size and quality, are expected to decline with advancing age due to senescence. It is however unclear whether this expectation is upheld across taxa. We perform a meta-analysis on 379 studies, to quantify the effects of advancing male age on ejaculate traits across 157 species of non-human animals. Contrary to predictions, we find no consistent pattern of age-dependent changes in ejaculate traits. This result partly reflects methodological limitations, such as studies sampling a low proportion of adult lifespan, or the inability of meta-analytical approaches to document non-linear ageing trajectories of ejaculate traits; which could potentially lead to an underestimation of senescence. Yet, we find taxon-specific differences in patterns of ejaculate senescence. For instance, older males produce less motile and slower sperm in ray-finned fishes, but larger ejaculates in insects, compared to younger males. Notably, lab rodents show senescence in most ejaculate traits measured. Our study challenges the notion of universal reproductive senescence, highlighting the need for controlled methodologies and a more nuanced understanding of reproductive senescence, cognisant of taxon-specific biology, experimental design, selection pressures, and life-history.

Facets of Suicidal Ideation.

According to SAMHSA (2023), approximately 16,600,000 American adults and teens reported having serious thoughts of suicide in 2022. While suicide prevention has primarily focused on suicide deaths and attempts, we contend that suicidal ideation (SI) deserves more in-depth investigation and should be an essential intervention target on its own. In support of this point, we provide three examples of ways to improve specificity in understanding of SI through the study of controllability of SI, the language used to assess SI, and measuring SI in real time. We also consider qualitative work on the content of SI, its treatment, and definitional considerations. We thus call for an increased general focus on SI within research, clinical care, and policy.

Emotion-related impulsivity across transdiagnostic dimensions of psychopathology.

OBJECTIVE: Several dimensions have received attention for their potential role in explaining shared variance in transdiagnostic symptoms of psychopathology. We hypothesized emotion-related impulsivity, the trait-like tendency toward difficulty restraining responses to emotion, would relate to symptoms of psychopathology, with two separable dimensions of emotion-related impulsivity relating distinctly to internalizing and externalizing symptoms. METHOD: Across two studies, we tested hypotheses using structural equation models of emotion-related impulsivity and multiple indicators of internalizing, externalizing, and thought symptoms. RESULTS: In Study 1 (658 undergraduates), emotion-related impulsivity was highly correlated with the general psychopathology (p) factor. In study 2 (421 Mechanical Turk participants), models did not support a general p factor; however, we replicated the hypothesized associations of emotion-related impulsivity dimensions with internalizing and externalizing factors. Across both studies, forms of emotion-related impulsivity uniquely and differentially related to internalizing and externalizing symptoms. CONCLUSIONS: Findings indicate emotion-related impulsivity may help explain transdiagnostic dimensions of psychopathology, such as the p factor.

Does Emotion-Related Impulsivity Relate to Specific ADHD Symptom Dimensions, and Do the Effects Generalize Across Comorbid Internalizing and Externalizing Syndromes?

BACKGROUND: Recent work highlights the role of emotion dysregulation in the pathology of Attention-Deficit/Hyperactivity Disorder (ADHD). As such, emotion-related impulsivity (ERI), the trait-like tendency toward disinhibited thoughts (Pervasive Influence of Feelings, PIF) and actions (Feelings Trigger Action, FTA) during heightened emotional states, may be particularly relevant. We explored whether Inattention (IN) and Hyperactivity/Impulsivity (HI), two core symptom dimensions of ADHD, would relate to distinct facets of ERI, and whether externalizing and internalizing symptoms would moderate these relations. METHOD: Using structural equation modeling, we examined hypotheses among 364 adults recruited for high internalizing and externalizing symptoms. RESULTS: We identified significant paths for FTA regressed on HI and PIF regressed on IN, supporting our hypotheses about main effects. Moderating paths were not significant. CONCLUSIONS: IN and HI correlate with distinct forms of ERI, These effects appear to generalize across co-occurring internalizing and externalizing symptoms. Theoretical and clinical implications are discussed.

On the impulsivity path: Examining the unique and conjoint relations between emotion- and non-emotion-related impulsivity, internalizing symptoms, alcohol use, and physical health parameters.

BACKGROUND: Researchers have increasingly differentiated trait-like tendencies toward impulsivity occurring during emotional states (emotion-related impulsivity [ERI]) from impulsivity not tied to emotion (non-ERI). Relative to non-ERI, ERI has shown robust correlations with psychopathology and mild to moderate associations with physical health parameters (e.g., physical activity, poor sleep quality, body mass index [BMI]). Therefore, we first aimed to investigate the unique contributions of ERI and non-ERI to psychopathology symptoms while controlling for neuroticism. Second, we sought to explore the combined associations of physical health parameters with several impulsivity forms. METHODS: German-speaking adults (N = 350, 35.9 ± 14.6 years, 69.1% female, BMI: 24.0 ± 4.8 kg/m2 , mostly students or employees) completed measures of impulsivity, psychopathology symptoms, neuroticism, and physical health. We gathered measures of two ERI forms: Feelings Trigger Action and Pervasive Influence of Feelings. As a control comparison, we gathered a measure of non-ERI, the Lack of Follow-Through scale. We conducted separate path models for Aims 1 and 2. RESULTS: For Aim 1, Pervasive Influence of Feelings showed strong links with internalizing symptoms. Feelings Trigger Action and Lack of Follow-Through showed small links with alcohol use. For Aim 2, poor sleep quality was related to all three impulsivity factors, while physical activity was only related to Pervasive Influence of Feelings and Lack of Follow-Through. BMI showed a curvilinear association with impulsivity. CONCLUSIONS: ERI is more directly relevant than non-ERI for psychopathology symptoms, emphasizing the need to differentiate between the two ERI types. The association of ERI and non-ERI with physical activity and poor sleep quality may serve as potential treatment targets for impulsivity-related problems.

Assessing the dominance behavioral system in early childhood using observational methods.

BACKGROUND: The dominance behavioral system (DBS) is a biologically based system that underpins individual differences in motivation for dominance and power. However, little is known about the DBS in childhood. In order to make strong claims about the DBS's trait-like properties and predictive validity, a clearer understanding of its early development is required. PARTICIPANTS AND PROCEDURE: In a pilot study aimed at developing a behavioral coding system for dominance, a key facet of the DBS, we collected and coded observational data from 58 children, assessed at ages 3 and 5-6. These data were examined in conjunction with measures of child temperament via observational measures, and symptoms of psychopathology. RESULTS: Dominance was moderately stable in early childhood to a degree comparable to other early child temperament traits. Consistent with the study hypotheses, boys were more dominant than girls, and dominance was negatively associated with children's behavioral inhibition, effortful control, and internalizing symptoms. CONCLUSIONS: These results provide initial support for the validity and developmental sensitivity of an objective coding system for assessing facets of the DBS in early childhood. Ultimately, the use of this coding system will facilitate future studies of how early DBS predicts psychological adjustment later in life.

Uncontrollability of suicidal ideation adds incremental explanatory power in prediction of later suicidal ideation.

OBJECTIVE: Suicidal ideation and suicidal behaviors are major public health concerns in the United States and are difficult to treat and predict. Risk factors that are incrementally informative are needed to improve prediction and inform prevention of suicidal thoughts and behaviors. Uncontrollability of suicidal ideation, one parameter of suicidal ideation, is one such candidate. METHOD: In the current study, we assessed the predictive power of uncontrollability of suicidal ideation, over and above overall suicidal ideation, for future suicidal ideation in a large sample of active-duty service members. A total of 1044 suicidal military service members completed baseline assessments, of whom 664 (63.6%) completed 3-month follow-up assessments. RESULTS: While baseline overall suicidal ideation itself was the strongest predictor of future suicidal ideation, uncontrollability of suicidal ideation added some incremental explanatory power. CONCLUSION: Further study of uncontrollability of suicidal thought is needed to elucidate its impact on suicidal outcomes.

Emotion-related impulsivity moderates the role of arousal on reflection impulsivity.

Emotion-related impulsivity is an important behavioural phenotype in clinical psychology and public health. Here, we test the hypothesis that emotion-related impulsivity moderates the effects of arousal on cognition using pharmacological manipulation. Participants completed a measure of emotion-related impulsivity, four cognitive tasks tapping onto different facets of impulsive behaviours, and a blinded arousal manipulation using yohimbine hydrochloride, which acts on noradrenergic receptors. Our findings suggest that emotion-related impulsivity moderates the role of arousal on impulsive performance on the Information Sampling Task. As expected, more severe emotion-related impulsivity was related to more impulsive decisions in the yohimbine but not in the placebo group. Results provide some of the first experimental evidence that emotion-related impulsivity is related to differential behavioural responses in the face of high arousal. Despite this preliminary support, we discuss findings for one task that did not fit hypotheses, and provide suggestions for replication and extension.

Behavioural differences in predator aware and predator naïve Wellington tree weta, Hemideina crassidens.

Insects have evolved a wide range of behavioural traits to avoid predation, with anti-predator behaviours emerging as important adaptive responses to the specific strategies employed by predators. These responses may become ineffective, however, when a species is introduced to a novel predator type. When individuals cannot recognise an introduced predator for instance, they may respond in ways that mean they fail to avoid, escape, or neutralize a predator encounter. New Zealand's endemic insect fauna evolved in the absence of terrestrial mammalian predators for millions of years, resulting in the evolution of unique fauna like the large, flightless Orthopteran, the weta. Here we investigate how experience with introduced mammalian predators might influence anti-predator behaviours by comparing behaviours in a group of Wellington tree weta (Hemideina crassidens) living in an ecosanctuary, Zealandia, protected from non-native mammalian predators, and a group living in adjacent sites without mammalian predator control. We used behavioural phenotyping assays with both groups to examine rates of activity and defensive aggression shortly after capture, and again after a period of acclimation. We found that weta living in protected areas were more active shortly after capture than weta in non-protected habitats where mammalian predators were present. Male weta living in non-protected areas tended to be less aggressive than any other group. These results suggest that lifetime experience with differing predator arrays may influence the expression of antipredator behaviour in tree weta. Disentangling innate and experiential drivers of these behavioural responses further will have important implications for insect populations in rapidly changing environments.

Shame on me for needing you: A multistudy examination of links between receiving interpersonal emotion regulation and experiencing shame.

Recent theory and research have drawn attention to interpersonal dimensions of emotion regulation. Yet, few empirical investigations of the outcomes of interpersonal emotion regulation have been conducted. We propose that one negative affective outcome of received interpersonal emotion regulation of conceptual and practical interest is shame. In the present series of studies, participants from six disparate samples reported on experiences of receiving interpersonal emotion regulation using autobiographical recall and ecological sampling paradigms (total analyzed n = 1,868; total analyzed k = 2,515 instances of receiving interpersonal emotion regulation). We sought to quantify the frequency and distinctiveness of shame as an outcome of receiving interpersonal emotion regulation. We used an exploratory-confirmatory approach to identify robust and generalizable correlates of shame. We considered individual (e.g., trait external shame-proneness), situational (e.g., desire for regulation), relational (e.g., perceived closeness with the provider), and interaction-specific (e.g., perceptions of provider hostility) variables. Our results indicate that it is not uncommon for people to experience receiving interpersonal emotion regulation as shame-inducing, and these perceptions are distinct from their evaluations of the overall helpfulness of the interaction. An internal mini meta-analysis showed that the strongest correlates of shame across studies and samples were individual differences in nonacceptance of negative emotions and expressive suppression and interaction-specific ratings of provider responsiveness and hostility. We discuss the conceptual, methodological, and practical implications of these findings for studying interpersonal emotion regulation and shame. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Emotion-related impulsivity and risky decision-making: A systematic review and meta-regression.

Emotion-related impulsivity, the trait-like tendency toward regrettable behavior during states of high emotion, is a robust predictor of internalizing and externalizing psychopathology. Despite substantial evidence that emotion-related impulsivity is important transdiagnostically, relatively little is known about its cognitive correlates. This systematic review and meta-regression investigates one such candidate, risky decision-making. We analyzed 195 effect sizes from 51 studies of 14,957 total participants, including 105 newly calculated effect sizes that were not reported in the original publications. The meta-regression demonstrated evidence for a small, positive relationship of emotion-related impulsivity with behavioral indices of risky decision-making (ß = 0.086). Effects generalized across sample age, gender, Positive versus Negative Urgency, and clinical versus nonclinical samples. The average effect size varied by task type, with stronger effects for the Iowa Gambling Task and Delay Discounting Task. Experimental arousal manipulation was nearly a significant moderator, with stress and pharmacological manipulations yielding significant effect sizes. Analyses indicated that publication bias did not skew the current findings. Notwithstanding limitations, the data suggest that risky decision-making is a cognitive domain that relates to emotion-related impulsivity. We conclude with recommendations regarding the specific types of tasks and arousal inductions that will best capture emotion-related impulsivity in future experimental research.

Neuroanatomical Correlates of Emotion-Related Impulsivity.

BACKGROUND: Emotion-related impulsivity (ERI) refers to chronically poor self-control during periods of strong emotion. ERI robustly predicts psychiatric disorders and related problems, yet its neuroanatomical correlates are largely unknown. We tested whether local brain morphometry in targeted brain regions that integrate emotion and control could explain ERI severity. METHODS: One hundred twenty-two adults (ages 18-55 years) with internalizing or externalizing psychopathology completed a structural magnetic resonance imaging (MRI) scan, the Three-Factor Impulsivity Index, and the Structured Clinical Interview for DSM-5. The Three-Factor Impulsivity Index measures two types of ERI and a third type of impulsivity not linked to emotion. Cortical reconstruction yielded cortical thickness and local gyrification measurements. We evaluated whether morphometry in the orbitofrontal cortex (OFC), insula, amygdala, and nucleus accumbens was associated with ERI severity. Hypotheses and analyses were preregistered. RESULTS: Lower cortical gyrification in the right lateral OFC was associated with high ERI severity in a full, preregistered model. Separate examinations of local gyrification and cortical thickness also showed a positive association between gyrification in the left lateral OFC and ERI. An integrated measure of hemispheric imbalance in lateral OFC gyrification (right < left) correlated with ERI severity. These findings were specific to ERI and did not appear with non-emotion-related impulsivity. CONCLUSIONS: Local gyrification in the lateral OFC is associated with ERI severity. The current findings fit with existing theories of OFC function, strengthen the connections between the transdiagnostic literature in psychiatry and neuroscience, and may guide future treatment development.

Who disengages from emotion and when? An EMA study of how urgency and distress intolerance relate to daily emotion regulation.

Overreliance on disengagement emotion regulation strategies (e.g., emotion avoidance, emotion suppression) has been shown to relate to poor clinical outcomes. Two traits characterized by difficulties in goal-directed responses to emotion-urgency and distress intolerance-may help explain who is likely to disengage from emotion and when. These traits are associated with diverse forms of psychopathology and greater reliance on disengagement strategies. Gaps remain about how these traits relate to emotion regulation in daily life. The present study uses ecological momentary assessment (EMA) to determine the associations of urgency and distress intolerance with momentary high arousal negative affect and momentary attempts to regulate negative emotions. Participants (N = 101) were college students who endorsed at least weekly behaviors often characterized by emotion dysregulation (e.g., self-harm, binging/purging, alcohol/drug use). Participants completed trait measures at baseline and EMA surveys of momentary affect and emotion regulation, six times daily for 4 days. Results indicated that at certain levels, urgency and distress intolerance moderated the relationship between high arousal negative affect and disengagement from emotion: low urgency scores related to relatively greater disengagement from emotion following reported high arousal negative affect, whereas high distress intolerance scores related to relatively greater disengagement following high arousal negative affect. Findings support the role of both urgency and distress intolerance in the relationship between high arousal negative affect and disengagement, which implicates the utility of clinical interventions that focus on emotion regulation, especially during high arousal states. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Emotion-related impulsivity and suicidal ideation: Towards a more specific model.

OBJECTIVES: Suicidal ideation is a pervasive and painful experience that varies considerably in its phenomenology. Here, we consider how one key risk variable might inform our understanding of variation in suicidal ideation: emotion-related impulsivity, the trait-like tendency towards unconstrained speech, behaviour, and cognition in the face of intense emotions. We hypothesized that emotion-related impulsivity would be tied to specific features, including severity, perceived lack of controllability, more rapidly fluctuating course, higher scores on a measure of acute suicidal affective disturbance, and more emotional and cognitive disturbance as antecedents. METHODS: We recruited two samples of adults (Ns = 421, 221) through Amazon Mechanical Turk (MTurk), with oversampling of those with suicidal ideation. Both samples completed psychometrically sound self-report measures online to assess emotion- and non-emotion-related dimensions of impulsivity and characteristics of suicidal ideation. RESULTS: One form of emotion-related impulsivity related to the severity, uncontrollability, dynamic course, and affective and cognitive precursors of ideation. CONCLUSIONS: Despite limitations of the cross-sectional design and self-report measures, the current findings highlight the importance of specificity in considering key dimensions of impulsivity and suicidal ideation.

Sperm quality of artificially matured shortfinned eel is not affected by human chorionic gonadotropin dose and route of administration.

Background: Acquisition of high quality sperm is key to the artificial propagation of eels in captivity, but fertility drugs are expensive and repeated handling is stressful to the fish. An interrupted treatment regime (an initial hormone injection to stimulate spermatogenesis, followed several weeks later by weekly booster injections to induce sperm maturation) for acquisition of sperm in captive male eels has promise for high sperm quality on the one hand, and animal welfare benefits on the other. To further develop this approach for shortfinned eel, Anguilla australis, we evaluated the efficacy of (i) different initial doses of human chorionic gonadotropin (hCG) and (ii) route of administration. Methods: Male eels were artificially induced to mature with a single injection of 0, 250, 500 or 1,000 IU/fish of hCG, administered either intramuscularly (IM) or intraperitoneally (IP). Sperm maturation was induced with 150 IU hCG/fish from week 5 onwards and sperm collected for evaluation of quality by computer-assisted sperm analysis. Results: Control males did not mature and hence, sperm could not be retrieved and analysed, but all other treatments were effective in inducing testicular maturation. Milt volume tended to be higher for fish injected IM compared to those injected IP, whereas hCG dose had no effect. Conversely, the concentration of spermatozoa tended to be higher for several sperm collection time points in IP-injected than in IM-injected fish. Sperm quality, represented by percent motility, percent progressive motility and curvilinear velocity, was equal in fish given an initial dose of 250 IU hCG to those given higher initial doses of hCG. Conclusions: We recommend that an initial dose of 250 IU hCG/fish be administered to induce spermatogenesis in male A. australis, and, after a period of 4-5 weeks, weekly booster injections of ∼150 IU hCG/fish be administered in the day prior to sperm collection; both routes of administration (IM or IP) are equally effective. We contend that an interrupted treatment regime has notable benefits for induced maturation in male anguillids, as it reduces fish handling and manipulation and reduces the resources required to produce high quality sperm.

Paternal hypoxia exposure primes offspring for increased hypoxia resistance.

BACKGROUND: In a time of rapid environmental change, understanding how the challenges experienced by one generation can influence the fitness of future generations is critically needed. Using tolerance assays and transcriptomic and methylome approaches, we use zebrafish as a model to investigate cross-generational acclimation to hypoxia. RESULTS: We show that short-term paternal exposure to hypoxia endows offspring with greater tolerance to acute hypoxia. We detected two hemoglobin genes that are significantly upregulated by more than 6-fold in the offspring of hypoxia exposed males. Moreover, the offspring which maintained equilibrium the longest showed greatest upregulation in hemoglobin expression. We did not detect differential methylation at any of the differentially expressed genes, suggesting that other epigenetic mechanisms are responsible for alterations in gene expression. CONCLUSIONS: Overall, our findings suggest that an epigenetic memory of past hypoxia exposure is maintained and that this environmentally induced information is transferred to subsequent generations, pre-acclimating progeny to cope with hypoxic conditions.