Paramecium bursaria (Ehrenberg 1831) is a ciliate species living in a symbiotic relationship with green algae. The aim of the study was to identify green algal symbionts of P. bursaria originating from distant geographical locations and to answer the question of whether the occurrence of endosymbiont taxa was correlated with a specific ciliate syngen (sexually separated sibling group). In a comparative analysis, we investigated 43 P. bursaria symbiont strains based on molecular features. Three DNA fragments were sequenced: two from the nuclear genomes—a fragment of the ITS1-5.8S rDNA-ITS2 region and a fragment of the gene encoding large subunit ribosomal RNA (28S rDNA), as well as a fragment of the plastid genome comprising the 3′rpl36-5′infA genes. The analysis of two ribosomal sequences showed the presence of 29 haplotypes (haplotype diversity Hd = 0.98736 for ITS1-5.8S rDNA-ITS2 and Hd = 0.908 for 28S rDNA) in the former two regions, and 36 haplotypes in the 3′rpl36-5′infA gene fragment (Hd = 0.984). The following symbiotic strains were identified: Chlorella vulgaris, Chlorella variabilis, Chlorella sorokiniana and Micractinium conductrix. We rejected the hypotheses concerning (i) the correlation between P. bursaria syngen and symbiotic species, and (ii) the relationship between symbiotic species and geographic distribution.

Paramecium bursaria is a symbiotic ciliate species which cells contain hundreds of algae enclosed in perialgal vacuoles. The aim of the present study was to identify endosymbiotic algal strains of P. bursaria and to define the geographical distribution of the identified species. We analyzed symbiotic strains of P. bursaria originating from distant geographical locations and housed at the Culture Collection of Ciliates and their Symbionts (CCCS) at St. Petersburg University. Based on the obtained results, we identified these strains as Micractinium reisseri, Chlorella vulgaris, and Chlorella variabilis. We did not confirm the occurrence of a division into American and European groups and we guess that this division is only contractual and corresponds to the amount of introns in the 18S rDNA, and that there is no strong correlation with the geographical location. We have demonstrated that the range of M. reisseri is greater than previously supposed. We identified algae strains originating from Southern Europe (Serbia), Western Asia, and from the Far East (Kamchatka) as M. reisseri. Moreover, we identified two strains originating from Europe as C. variabilis, which also contradicts the predetermes about a division into American and European groups.

Background/Objectives: Long-term recovery following adolescent anorexia nervosa (AN) remains incompletely understood because restoration of nutritional status does not necessarily coincide with psychological remission. Comprehensive evaluation of recovery requires consideration of psychological, behavioural, and patient-reported outcomes in addition to anthropometric measures. To evaluate long-term recovery following adolescent anorexia nervosa by integrating clinical outcomes, patient- and caregiver-reported experiences, orthorexic tendencies, and eating-disorder psychopathology, and to identify factors associated with persistent psychological impairment. Methods: This retrospective follow-up study employed a cross-sectional survey design. Families of 100 former patients previously hospitalized for adolescent anorexia nervosa in a child and adolescent psychiatric inpatient unit were invited to participate 5–10 years after discharge. Follow-up questionnaires were returned by 23 former patients and 17 caregivers. Former patients completed the SCOFF questionnaire and questions assessing orthorexic tendencies, whereas caregivers and the patients as well provided information regarding their child’s long-term recovery, treatment experiences, current functioning, and selected demographic characteristics. Responses from former patients and caregivers were analysed according to respondent group and the variables available for each group, while information from both groups was used to obtain a comprehensive assessment of long-term recovery. Descriptive and inferential statistical analyses were performed. Results: Mean BMI increased from 13.4 kg/m² during the acute phase of illness to 18.8 kg/m² at follow-up, indicating substantial nutritional improvement. Nevertheless, approximately 60% of former patients screened positive on the SCOFF questionnaire, suggesting persistent eating-disorder symptoms despite nutritional rehabilitation. Orthorexic tendencies were strongly associated with positive SCOFF screening results (Cramér’s V = 0.828; p < 0.001). Psychiatric comorbidity and poorer subjective health perception were also associated with less favourable long-term outcomes. Qualitative findings further demonstrated that recovery was perceived as extending beyond symptom reduction to include psychological wellbeing, restoration of autonomy, interpersonal functioning, and social reintegration.

Eating disorders (EDs), including anorexia nervosa (AN), bulimia nervosa (BN), and binge-eating disorder (BED), are complex psychiatric conditions characterized by high morbidity and mortality. Increasing evidence suggests that beyond disorder-specific symptomatology, shared transdiagnostic mechanisms contribute to their onset and persistence. This narrative review synthesizes current data on neurobiological and nutritional factors implicated in EDs, with particular emphasis on trait–state interactions and starvation-induced neuroadaptations. Predisposing vulnerabilities such as heightened anxiety, cognitive rigidity, and perfectionism appear to interact with state-dependent biological alterations induced by malnutrition. Chronic dietary restriction is associated with measurable alterations in serotonergic and dopaminergic systems, altered reward processing, and persistent activation of the hypothalamic–pituitary–adrenal (HPA) axis. Experimental studies suggest that acute tryptophan depletion may transiently reduce anxiety in individuals with anorexia nervosa, suggesting that, in some individuals, food restriction may function as a biologically reinforced strategy of affect regulation. Furthermore, disturbances in leptin and ghrelin signaling, along with widespread micronutrient deficiencies—including zinc, iron, selenium, and B vitamins—may exacerbate cognitive inflexibility, mood instability, and impaired decision-making. These metabolic and endocrine adaptations may contribute to a self-perpetuating cycle in which starvation-induced neurochemical changes reinforce restrictive or dysregulated eating behaviors. Importantly, several of these mechanisms extend beyond anorexia nervosa and may represent common transdiagnostic processes across eating disorders and related mental health conditions, including anxiety, depression, and addictive behaviors. Recognition of these biological and nutritional factors has significant implications for treatment. Nutritional rehabilitation should be conceptualized not solely as weight restoration, but as a neurobiological recalibration of stress regulation, reward sensitivity, and affective processing systems. An integrative treatment approach that combines behavioral stabilization with attention to underlying neurobiological and relational mechanisms may offer a more comprehensive framework for long-term recovery.