Markers of serotonergic function in the orbitofrontal cortex and dorsal raphé nucleus predict individual variation in spatial-discrimination serial reversal learning.

Dysfunction of the orbitofrontal cortex (OFC) impairs the ability of individuals to flexibly adapt behavior to changing stimulus-reward (S-R) contingencies. Impaired flexibility also results from interventions that alter serotonin (5-HT) and dopamine (DA) transmission in the OFC and dorsomedial striatum (DMS). However, it is unclear whether similar mechanisms underpin naturally occurring variations in behavioral flexibility. In the present study, we used a spatial-discrimination serial reversal procedure to investigate interindividual variability in behavioral flexibility in rats. We show that flexibility on this task is improved following systemic administration of the 5-HT reuptake inhibitor citalopram and by low doses of the DA reuptake inhibitor GBR12909. Rats in the upper quintile of the distribution of perseverative responses during repeated S-R reversals showed significantly reduced levels of the 5-HT metabolite, 5-hydroxy-indoleacetic acid, in the OFC. Additionally, 5-HT2A receptor binding in the OFC of mid- and high-quintile rats was significantly reduced compared with rats in the low-quintile group. These perturbations were accompanied by an increase in the expression of monoamine oxidase-A (MAO-A) and MAO-B in the lateral OFC and by a decrease in the expression of MAO-A, MAO-B, and tryptophan hydroxylase in the dorsal raphé nucleus of highly perseverative rats. We found no evidence of significant differences in markers of DA and 5-HT function in the DMS or MAO expression in the ventral tegmental area of low- vs high-perseverative rats. These findings indicate that diminished serotonergic tone in the OFC may be an endophenotype that predisposes to behavioral inflexibility and other forms of compulsive behavior.This work was supported by Medical Research Council Grants (G0701500; G0802729), a 503 Wellcome Trust Programme Grant (grant number 089589/Z/09/Z), and by a Core Award 504 from the Medical Research Council and the Wellcome Trust to the Behavioural and Clinical 505 21 Neuroscience Institute (MRC Ref G1000183; WT Ref 093875/Z/10/Z). RLB was supported 506 by a studentship from the Medical Research Council. JA was supported by a Fellowship from 507 the Swedish Research Council (350-2012-230). BJ was supported by Fellowships from the 508 AXA Research Fund and the National Health and Medical Research Council of Australia. 509 Financial support from the Fredrik and Ingrid Thuring Foundation is also acknowledged.This is the accepted manuscript. The final version is available from Nature Publishing at http://www.nature.com/npp/journal/vaop/ncurrent/full/npp2014335a.html

An integrated approach to elucidate the interplay between iron uptake dynamics and magnetosome formation at the single-cell level in Magnetospirillum gryphiswaldense

Iron is a crucial element integral to various fundamental biological molecular mechanisms, including magnetosome biogenesis in magnetotactic bacteria (MTB). Magnetosomes are formed through the internalization and biomineralization of iron into magnetite crystals. However, the interconnected mechanisms by which MTB uptake and regulate intracellular iron for magnetosome biomineralization remain poorly understood, particularly at the single-cell level. To gain insights we employed a holistic multiscale approach, i.e., from elemental iron species to bacterial populations, to elucidate the interplay between iron uptake dynamics and magnetosome formation in Magnetospirillum gryphiswaldense MSR-1 under near-native conditions. We combined a correlative microscopy approach integrating light and X-ray tomography with analytical techniques, such as flow cytometry and inductively coupled plasma spectroscopy, to evaluate the effects of iron and oxygen availability on cellular growth, magnetosome biogenesis, and intracellular iron pool in MSR-1. Our results revealed that increased iron availability under microaerobic conditions significantly promoted the formation of longer magnetosome chains and increased intracellular iron uptake, with a saturation point at 300 μM iron citrate. Beyond this threshold, additional iron did not further extend the magnetosome chain length or increase total intracellular iron levels. Moreover, our work reveals (i) a direct correlation between the labile Fe2+ pool size and magnetosome content, with higher intracellular iron concentrations correlating with increased magnetosome production, and (ii) the existence of an intracellular iron pool, distinct from magnetite, persisting during all stages of biomineralization. This study offers insights into iron dynamics in magnetosome biomineralization at a single-cell level, potentially enhancing the industrial biomanufacturing of magnetosomes

Endocannabinoid Regulation of Acute and Protracted Nicotine Withdrawal: Effect of FAAH Inhibition

Evidence shows that the endocannabinoid system modulates the addictive properties of nicotine. In the present study, we hypothesized that spontaneous withdrawal resulting from removal of chronically implanted transdermal nicotine patches is regulated by the endocannabinoid system. A 7-day nicotine dependence procedure (5.2 mg/rat/day) elicited occurrence of reliable nicotine abstinence symptoms in Wistar rats. Somatic and affective withdrawal signs were observed at 16 and 34 hours following removal of nicotine patches, respectively. Further behavioral manifestations including decrease in locomotor activity and increased weight gain also occurred during withdrawal. Expression of spontaneous nicotine withdrawal was accompanied by fluctuation in levels of the endocannabinoid anandamide (AEA) in several brain structures including the amygdala, the hippocampus, the hypothalamus and the prefrontal cortex. Conversely, levels of 2-arachidonoyl-sn-glycerol were not significantly altered. Pharmacological inhibition of fatty acid amide hydrolase (FAAH), the enzyme responsible for the intracellular degradation of AEA, by URB597 (0.1 and 0.3 mg/kg, i.p.), reduced withdrawal-induced anxiety as assessed by the elevated plus maze test and the shock-probe defensive burying paradigm, but did not prevent the occurrence of somatic signs. Together, the results indicate that pharmacological strategies aimed at enhancing endocannabinoid signaling may offer therapeutic advantages to treat the negative affective state produced by nicotine withdrawal, which is critical for the maintenance of tobacco use

Genetic determinants of testicular sperm extraction outcomes: Insights from a large multicentre study of men with non-obstructive azoospermia

\ua9 2025 The Author(s). Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology.STUDY QUESTION What is the diagnostic yield and the pre-testicular sperm extraction (TESE) prognostic value of a non-obstructive azoospermia (NOA)-specific virtual gene panel? SUMMARY ANSWER The diagnostic yield in our cohort was 6.1%, and by combining our data with published literature, we identified 11 genes compatible with testicular sperm production and 19 genes associated with no sperm retrieval in carriers of pathogenic (P) or likely pathogenic (LP) mutations. WHAT IS KNOWN ALREADY Azoospermia, the most severe form of male infertility, affects ∼1% of the male population, with TESE being the primary treatment option. However, in NOA, TESE fails in nearly 50% of cases and existing clinical parameters are unable to predict TESE failure. Over the past decade, next-generation sequencing (NGS) has identified several candidate NOA genes, but their diagnostic utility and impact on TESE outcomes have not been fully explored. STUDY DESIGN, SIZE AND DURATION A literature search was addressed to identify well-established NOA genes for designing a specific virtual gene panel for NOA. Our retrospective study analysed the diagnostic yield of the NGS-based virtual gene panel, comprising 145 genes, in 571 men affected by idiopathic NOA with known TESE outcomes. Subsequently, a second literature search was performed to identify carriers of LP/P variants in the genes where we identified mutations, focusing on individuals with known TESE outcomes. This approach allowed us to integrate the published data with our findings and predict a genotype-phenotype correlation between the affected genes and TESE success. PARTICIPANTS/MATERIALS, SETTINGS, METHODS 571 NOA patients with known TESE outcomes were recruited in two European and one Middle East centres. Variants were obtained from a whole-exome sequencing dataset and crossed with the 145 genes of the virtual gene panel. After a filtering process, variants were manually assessed and classified according to ACMG guidelines by using two methods: (i) In order to compare our data with previously published studies, we applied ACMG-AMP guidelines along with ClinGen recommendations used by other similar studies. (ii) A new approach was used to optimize ACMG-AMP guidelines with all ClinGen recommendations and incorporated NOA-specific rules addressing phenotypic, locus, and allelic heterogeneity. LP and P variants were confirmed by Sanger sequencing. MAIN RESULTS AND THE ROLE OF CHANCE By using the new variant classification approach adapted for NOA, we identified LP/P variants in 6.1% of patients, with a higher yield (9.4%) in cases with negative TESE outcomes and maturation arrest (11.7%). By integrating our findings with the literature, we highlight 19 genes recurrently associated with negative TESE outcomes and 11 genes associated with positive sperm retrieval either in the testis or in semen. TESE is recommended for patients with LP or P variants in the 11 specific genes. Notably, six of these genes are located on the X chromosome, therefore, these variants will be obligatorily transmitted to daughters, and potentially increase the risk of NOA-related infertility in male offspring. We observed that nine genes, in which we identified LP/P variants, have been previously described in individuals with premature ovarian insufficiency (POI). Of these, eight were associated with negative TESE outcomes in men. Furthermore, we propose seven additional genes mutated in our cohort of NOA patients as novel POI candidates. These genes have not yet been considered as POI candidates, but they result in female infertility when knocked out in mouse models. LARGE SCALE DATA LP/P variants have been submitted to ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/). LIMITATIONS, REASONS FOR CAUTION NOA is genetically heterogeneous, and our panel excludes those genes which were reported only in a single subject or single family. Although this can limit the diagnostic yield in our study, it ensures that only genes with clear relationship with NOA have been analysed. While in our cohort TESE outcomes are known for all patients, this information is often not available for mutation carriers in the published studies. Consequently, the total number of patients with P variants in the same gene remains relatively low, limiting our final conclusions. However, even if the number of carriers of genes associated with positive sperm retrieval is relatively low, it does not constrain our conclusions regarding TESE prediction. On the other hand, caution is warranted for genes linked to negative TESE outcomes, except for TEX11, SYCE1, and MSH4, each of which have 10 or more reported TESE-negative cases. WIDER IMPLICATIONS OF THE FINDINGS Our study was performed on the largest available NOA cohort with known TESE outcomes. It not only provides an estimate on the diagnostic potential of a NOA-specific virtual gene panel, but it also advances the understanding of genetic factors influencing TESE outcomes. Half of the genes mutated in our study and presenting TESE-positive outcomes are already informative for clinical decision-making. The observed genotype-phenotype correlations may help in personalized decision-making prior to TESE, in order to undergo the procedure or to avoid unnecessary invasive treatment. It provides valuable insights that can inform clinical management strategies and potentially offer personalized treatments based on genetic profiles. The use of two different variant classification methods highlights that previous studies may have over-estimated the diagnostic yield, underscoring the need for a standardized variant classification approach addressed specifically to male infertility. Our study also emphasizes the overlap between NOA- and POI-associated genes, which has important clinical implications for genetic counselling of female siblings of affected individuals. STUDY FUNDING/COMPETING INTEREST(S) This work was funded by the Spanish Ministry of Health Instituto Carlos III-FIS FONDOS FEDER (grant numbers PI20/01562 and PI23/00425) and the Fanconi Research Fund awarded to C.K. and A.R.-E. This article is based upon work from COST Action CA20119 (ANDRONET), supported by COST (European Cooperation in Science and Technology) (www.cost.eu). C.K., A.R.-E., G.F., M.J.X., M.S.O., C.A., M.S., and E.R.-C. are members of the Action. This research was also supported by the Qatar National Research Fund (QNRF) under grant NPRP12S-0318-190394, and by an Investigator Award in Science from the Wellcome Trust (209451 to J.A.V.). The authors declare no competing interests

Stereotypic horses (Equus caballus) are not cognitively impaired

Stereotypies in animals are thought to arise from an interaction between genetic predisposition and sub-optimal housing conditions. In domestic horses, a well-studied stereotypy is crib-biting, an abnormal behaviour that appears to help individuals to cope with stressful situations. One prominent hypothesis states that animals affected by stereotypies are cognitively less flexible compared to healthy controls, due to sensitization of a specific brain area, the basal ganglia. The aim of this study was to test this hypothesis in crib-biting and healthy controls, using a cognitive task, reversal learning, which has been used as a diagnostic for basal ganglia dysfunction. The procedure consisted of exposing subjects to four learning tasks; first and second acquisition, and their reversals. For each task, we measured the number of trials to reach criterion and heart rate and heart-rate variability. Importantly, we did not try to prevent crib-biters from executing their stereotypic behaviour. We found that the first reversal learning task required the largest number of trials, confirming its challenging nature. Interestingly, the second reversal learning task required significantly fewer trials to reach criterion, suggesting generalisation learning. However, we did not find any performance differences across groups; both stereotypic and control animals required a similar numbers of trials and did not differ in their physiological responses. Our results thus challenge the widely held belief that crib-biting horses, and stereotypic animals more generally, are cognitively impaired. We conclude that cognitive underperformance may occur in stereotypic horses if they are prevented from crib-biting to cope with experienced stress.PostprintPeer reviewe

Behavioral responses of three plant-inhabiting predators to different prey densities

While measuring the predators' functional response for the assessment of their aptitude as biological control agents, the time that predators allocate to activities other than handling or searching for the prey, the preference to allocate some of these activities to different locations, and the patch departure tendencies dependent on prey density, are ignored. We test whether these factors have an effect on the predation rates of three plant-inhabiting predators that are used as biological control agents, Dicyphus tamaninii Wagner, Macrolophus caliginosus Wagner, and Orius majusculus (Reuter), at high and low densities of pupae of Trialeurodes vaporariorum Westwood. Continuous behavioral observations of the three species were done on a non-enclosed plant, thus allowing predators to visit different plant locations and to leave the plant at their will. We compared the current results with the ones obtained in a previous functional response experiment. We found that predators' plant-departure tendency at low prey density was the main reason for differences found in attack rates between experiments. The predators' preference for laying eggs in the stem, thus spending time in prey-free areas, explained the differences found in attack rates at high prey density. Our results provide more realistic information on predators' performance to better assess their suitability as biological control agents. Predator behavioral differences depending on prey densities allow for a complementary use of these predators for biological control