Migratory Stream Research Articles

Child fostering and maternal migration in sub-Saharan Africa

Rising feminization of migration has resulted in substantial flows of women migrating in Africa, increasing the importance of migration in women’s lives. Although child fostering is an enduring feature of family life throughout Africa, few studies have examined the role that maternal migration may play in these arrangements. I use Demographic and Health Survey data from 24 African countries to explore associations between maternal migration experience and fostering out of children aged 0–17, focusing on maternal migrant status, migrant stream, motivation, and timing of migration relative to births of children, to explore potential disruption introduced by migration. Results suggest that maternal migration disrupts mother–child co-residence, with greater fostering among children of migrant mothers, particularly rural–urban migrants. Children born before migration display the highest probability of fostering, consistently across migrant streams. These results suggest a need for greater attention to the impacts of maternal migration for children’s living arrangements, particularly as migration flows become increasingly feminized.

High spatial resolution gene expression profiling and characterization of neuroblasts migrating in the peri-injured cortex using photo-isolation chemistry.

In the ventricular-subventricular-zone (V-SVZ) of the postnatal mammalian brain, immature neurons (neuroblasts) are generated from neural stem cells throughout their lifetime. These V-SVZ-derived neuroblasts normally migrate to the olfactory bulb through the rostral migratory stream, differentiate into interneurons, and are integrated into the preexisting olfactory circuit. When the brain is injured, some neuroblasts initiate migration toward the lesion and attempt to repair the damaged neuronal circuitry, but their low regeneration efficiency prevents functional recovery. Elucidation of the molecular basis of neuroblast migration toward lesions is expected to lead to the development of new therapeutic strategies for brain regenerative medicine. Here, we show gene expression profiles of neuroblasts migrating in the peri-injured cortex compared with those migrating in the V-SVZ using photo-isolation chemistry, a method for spatial transcriptome analysis. Differentially expressed gene analysis showed that the expression levels of 215 genes (97 upregulated and 118 downregulated genes) were significantly different in neuroblasts migrating in the peri-injured cortex from those migrating in the V-SVZ. Gene Ontology analysis revealed that in neuroblasts migrating in the peri-injured cortex, expression of genes involved in regulating migration direction and preventing cell death was upregulated, while the expression of genes involved in cell proliferation and maintenance of the immature state was downregulated. Indeed, neuroblasts migrating in the peri-injured cortex had significantly lower Cyclin D2 mRNA and Ki67 protein expression levels than those in the V-SVZ. In the injured brain, amoeboid microglia/macrophages expressed transforming growth factor-β (TGF-β), and neuroblasts migrating in the peri-injured cortex expressed TGF-β receptors. Experiments using primary cultured neuroblasts showed that application of TGF-β significantly decreased proliferating cells labeled with BrdU. These data suggest that the proliferative activity of neuroblasts migrating toward lesions is suppressed by TGF-β secreted from cells surrounding the lesion. This is the first comprehensive study characterizing the gene expression profiles of neuroblasts migrating in the peri-injured cortex.

A Critical Analysis of Marital Status and Streams of Migration in India

A Critical Analysis of Marital Status and Streams of Migration in India

The number and distribution of proliferating cells in the rat’s rostral migratory stream as identified by means of two different proliferation markers

ABSTRACT In the brains of adult rodents, the cells arising in the subventricular zone of the lateral ventricles maintain the ability to divide when migrating to the olfactory bulb along the rostral migratory stream (RMS). Dividing cells in the RMS are most frequently revealed through immunohistochemical detection of an exogenous marker of proliferation, 5-Bromo-2-deoxyuridine (BrdU), which incorporates into DNA during the S-phase of mitosis. The more recently recognized antigen Ki-67 (also known as Kiel-67 and MKI67), an endogenous protein expressed in nuclei at all stages of mitosis, is also used for proliferation detection. BrdU and Ki-67 are often used as alternative methods, but they have not previously been compared in the RMS. We analyzed the numbers and distribution of cells labeled either with BrdU or Ki-67 within the RMS of adult rats. The first group of animals received a single i.p. dose of BrdU. In the second group, dividing cells were visualized by Ki-67 immunohistochemistry. Some sections from brains of BrdU-treated rats were also immunostained for Ki-67. Labeled cells were counted in the three anatomical parts of the RMS (vertical arm, elbow and horizontal arm) using a method for unbiased estimation of cell density. The distribution of proliferating cells was similar for both markers. Most BrdU and Ki-67 positive cells were located in the vertical arm and in the elbow, but a caudo-rostral reduction in cell divisions was more evident with Ki-67 labeling. The number of Ki-67 positive cells significantly exceeded the number of BrdU positive cells in all parts of the RMS. Our results indicate that BrdU and Ki-67 are not interchangeable markers for evaluation of proliferative activity in the RMS.

Returning home from exile? Arnold Cornelisz's ministerial networks and the religious landscape of the liberated Netherlands☆

AbstractScholars of the Dutch Reformation have attributed the rapid development of Reformed churches in the liberated areas of the Northern Netherlands after 1572 to the immigration of radical migrants from Flanders or returning exiles who learned the trade in the refugee churches outside the Low Countries. However, the impact of the networks, rather than the ideology, of a third transformative stream of migrants often gets overlooked. This article argues that a wider network of mobile ministers centred around the University of Heidelberg had a profound impact on the religious landscape of the Low Countries. It demonstrates this using a network analysis of the correspondence of one of the leading Reformed ministers in the liberated Netherlands after 1572, Arnold Cornelisz, combined with a prosopographical examination of the network. The idea that exile brought innovation through the formation of networks itself is not new. Yet, the article suggest that scholars should also take into account the interaction of exile with other forms of migration. Although Reformed ministers did not always recognize themselves as refugees or exiles, they were part of a large, transferable network that formed an innovative force after their return to the Low Countries.

Migration scale, process, and impact in the Tiwanaku colonies: Paleomobility at the archaeological site of Omo M10.

Contemporary migrations show form and intensity of interaction between homeland and host communities to shape social dynamics and identities. We apply here a contemporary theoretical framework and biogeochemical analyses to elucidate the scale, processes, and impacts of migration in the Tiwanaku polity (6th-11th c. CE) by inferring the mobility of individuals interred at the Tiwanaku-affiliated site of Omo M10 (Moquegua Valley, Peru). For each of 124 individuals, we captured paleomobility across the life-course by analyzing up to four enamel and bone samples that formed during discrete developmental periods for radiogenic strontium (87Sr/86Sr) and stable oxygen (δ18Ocarbonate(VPDB)) isotopes. At Omo M10, archaeological human enamel and bone values range from 87Sr/86Sr = 0.70632-0.72183 and δ18Ocarbonate(VPDB) = -13.4‰ to +1.7‰, with a mean of 87Sr/86Sr = 0.70763 ± 0.00164 (1σ, n = 334) and δ18O = -7.8‰ ± 1.9‰ (1σ, n = 334). Together with archaeological evidence, we interpret these data as evidence for multigenerational interaction between communities in the high-altitude Tiwanaku heartland and at the site of Omo M10. Our results suggest that one-fourth of individuals spent some part of their life outside of Moquegua and one in eight individuals from Omo M10 were first-generation migrants. Greater mobility of females and juveniles at Omo M10 indicates that gender and family were important social constructs in maintaining relationships and cultural continuity in provincial Tiwanaku life, and communities maintained autochthonous migration streams with Tiwanaku-affiliated populations throughout the south-central Andes. Intra-individual biogeochemical analyses of migration at Omo M10 contribute a nuanced perspective on the diverse experiences of multigenerational Tiwanaku colonies.

Effect of microwave radiation on adult neurogenesis and behavior of prenatally exposed rats

Postnatal neurogenesis appears to be highly sensitive to environmental factors, including microwave electromagnetic radiation (MWR). Here, we investigated the impact of MWR during intrauterine development on juvenile and adult neurogenesis in the rostral migratory stream (RMS) and the dentate gyrus of the hippocampus in the rat brain, as well as its effect on animal behavior. Female rats were exposed to MWR at a frequency of 2.45 GHz for 2 hours daily throughout pregnancy. The offspring of irradiated mothers survived to either juvenile age or adulthood. The brains of the rats were subjected to morphological analysis, assessing cell proliferation and death in both neurogenic regions. In the RMS, the differentiation of nitrergic neurons was also investigated. The effect of MWR on behavior was evaluated in rats surviving to adulthood. Prenatal MWR exposure caused significant changes in the number of proliferating and dying cells, depending on the age of the animals and the observed neurogenic region. In addition, MWR attenuated the maturation of nitrergic neurons in the RMS in both juvenile and adult rats. Morphological alterations in neurogenesis were accompanied by changes in animals’ behavior. Affected neurogenesis and changes in animal behavior suggest a high sensitivity of the developing brain to MWR.

The effects of Atoh8 on postnatal murine neurogenesis.

Introduction Basic helix-loop-helix (bHLH) transcription factors are expressed in various organs and are involved in diverse developmental processes. The mouse atonal homolog 8 (Atoh8), a bHLH transcription factor plays a crucial role in various developmental processes, especially as a regulator of neurogenesis in the retina. Besides, Atoh8 expression has been observed in the central nervous system. The function of Atoh8 during the postnatal neurogenesis is still unclear. Methods This study focuses on elucidating the impact of Atoh8 on postnatal neurogenesis in the brain, particularly in selected regions; the subventricular zone (SVZ), rostral migration stream (RMS) and olfactory bulb (OB), across different life stages, using male homozygous Atoh8-knockout (M6KO) mice. Our morphometric analysis is based on immunohistochemically labeled markers for neuroblasts (Doublecortin) and proliferation (Phospho-Histone H3, PHH3) as well as pan neuronal markers. Results In Atoh8-/- mice alteration in the postnatal neurogenesis can be observed. Immunohistochemical analysis revealed a significant reduction in doublecortin-positive neuroblasts within the SVZ of neonatal M6KO mice compared to wildtype (WT) mice. Interestingly, no differences in cell number and distribution was observed in the subsequent migration of neuroblasts through the rostral migration stream (RMS) to the olfactory bulb (OB). Proliferating PHH3-positive neuronal progenitor cells were significantly diminished in proliferation rate in both the SVZ and RMS of neonatal and young M6KO mice. Furthermore, in the glomerular layer of the OB significantly fewer neurons were detected in the neonatal stage. Conclusion In conclusion, Atoh8 emerges as a positive regulator of postnatal neurogenesis in the brain. Its role encompasses the promotion of neuroblast formation, modulation of proliferation rates, differentiation, and maintenance of mature neurons. Understanding the intricacies of Atoh8 function provides valuable insights into the complex regulatory mechanisms governing neurogenesis.

Unidirectional dispersal of blow fly larvae following decomposition fluids from a pig carcass

The decomposition of a body, and the associated gaseous and liquid discharges emanating from it, attract gravid female blow flies which lay their eggs in or on the body. After the eggs have hatched, the emerging larvae start feeding on the body. As decomposition progresses, the blow fly larvae often migrate away, typically in a random manner in search of favourable conditions for pupation. In this paper, we report on a rarely described phenomenon of unidirectional mass migration of blow fly larvae and postulate on the factors which may drive this process. A decomposition trial utilising a 60-kg pig carcass, deployed in the summer months in Table Mountain National Park, Cape Town, South Africa, was conducted in 2022. On the fifth day of the trial, simultaneous unidirectional mass dispersal of blow fly larvae was observed. The larvae moved downhill in a southeasterly direction, following the flow of decomposition fluids oozing out from the pig carcass. The ‘larval migration stream’ had a length of approximately 1.5 m with a width of 40 cm, tapering to 17 cm at the terminal point. The larval migration stream consisted of the larvae of Chrysomya albiceps and Chrysomya chloropyga. This study demonstrates the importance of understanding the timing and pattern of dispersal of post-feeding blow fly larvae in each geographical region. This is crucial as the minimum post-mortem interval can be miscalculated if older immature insects dispersing from the corpse are not considered and collected during crime scene investigations.

Impaired olfactory performance and anxiety-like behavior in a rat model of multiple sclerosis are associated with enhanced adenosine signaling in the olfactory bulb via A1R, A2BR, and A3R.

The present study shows that animals with experimental autoimmune encephalomyelitis (EAE) exhibit olfactory dysfunction and impaired general cognitive abilities, as well as anxiety-like behavior. Olfactory dysfunction occurs on average at 2 dpi, well before the onset of the first motor signs of EAE (8-10 dpi). After the initial olfactory dysfunction, the EAE animals show a fluctuation in olfactory performance that resembles the relapsing-remitting course of human MS. The study also shows severe neuroinflammation in the olfactory bulb (OB), with numerous infiltrated CD4+ T cells and peripheral macrophages in the superficial OB layers, marked microgliosis, and massive induction of TNF-α, IL-1β, and IL-6. Reduced tyrosine hydroxylase activity in the glomerular layer, pronounced granule cell atrophy, and reduced numbers of type B neuroblasts in the rostral migratory stream also indicate altered plasticity of the neuronal network in the OB. Considering the exceptionally high purinome expression in the OB, the possible involvement of purinergic signaling was also investigated. The study shows that macrophages infiltrating the OB overexpress A3R, while highly reactive microglia overexpress the adenosine-producing enzyme eN/CD73 as well as A2BR, A3R, and P2X4R. Given the simultaneous induction of complement component C3, the results suggest that the microglial cells develop a functional phenotype of phagocytizing microglia. The study also demonstrates transcriptional and translational upregulation of A1R in mitral and tufted cells, which likely influence resting network activity in OB and likely contribute to olfactory dysfunction in EAE. Overall, our study shows that olfactory dysfunction and altered social and cognitive behavior in EAE are associated with increased adenosine signaling via A1R, A2BR, and A3R.

Social support and economic conditions among older migrants in India: do distance, duration, and streams of migration play a role in later life?

BackgroundBeing older and having a migrant feature might cause a double risk of vulnerability in poor economic, social support, and health status at the place of destination. This study examines the association of migration on the social support and economic condition of older persons in India.MethodsLongitudinal Ageing Study in India (LASI) wave-I (2017–2018) data with total samples of 66,156 older adults aged 45 + with 30,869 and 35,287 male and female samples, respectively, used in this study. Descriptive and bivariate analyses have been performed to examine the pattern of older migrants, and multinomial logistic regression analysis has been used to establish the associations between migration, social support, and economic condition.ResultsOver half (57.5%) of the population aged 45 + in India had migrant characteristics; 80% migrated before 25 years. Of all migrants, about 90% migrated within one state (Intrastate), and 9% migrated to another (Interstate). The association between social support and migration by distance and the adjusted result showed that immigrants were less likely to have medium [RRR = 0.56 (CI; 0.46–0.68)] and high [RRR = 0.39 (CI; 0.30–0.50)] social support. The interstate migrants were also less likely to have high [RRR = 0.90 (CI; 0.83–0.98)] social support. The migrants with 0–9 years of duration were less likely to have high social support, and the urban to rural stream migrants were more likely to have high social support. The association between economic status and migration by distance and the adjusted result showed that more affluent immigrants were likelier to have [RRR = 1.41 (CI; 1.14–1.73)] better economic conditions than affluent non-migrants. Migrants with 0–9-year duration and urban to rural stream were found to be likelier to have better economic conditions.ConclusionsThe findings of this study suggest that distance, duration, and migration stream have a significant association with social support and economic conditions in later life. In exploring migration’s effect on social and economic status, policymakers should prioritize migrants in their agenda to maintain socio-economic and social support for older persons in India to achieve the sustainable goal of active and healthy ageing.

Camino de la Muerte: Crossing the Darién Gap and Migration in the Americas

As the only land bridge connecting South and North America, the Darién Gap has become one of the most widely used migration paths in the Americas. It is also one of the deadliest. Fleeing poverty, economic, political and social instability, migrants on this trek come from different countries around the world. Venturing through over 60 miles of dense rainforest, steep mountains and swamps, this manuscript examines the growing importance of the Darién Gap as a strategic transit point for migrants in Latin America. Examining the dynamics of forced migration, this work also evaluates the complex confluence of factors driving migration on the Pan-American highway. Facing immense harms to personal safety and autonomy, this manuscript underscores how factors such as human rights violations, gender-based violence (GBV) and climate change have affected forced migration streams through the Darién Gap.

FMRP regulates postnatal neuronal migration via MAP1B.

The fragile X syndrome (FXS) represents the most prevalent form of inherited intellectual disability and is the first monogenic cause of autism spectrum disorder. FXS results from the absence of the RNA-binding protein FMRP (fragile X messenger ribonucleoprotein). Neuronal migration is an essential step of brain development allowing displacement of neurons from their germinal niches to their final integration site. The precise role of FMRP in neuronal migration remains largely unexplored. Using live imaging of postnatal rostral migratory stream (RMS) neurons in Fmr1-null mice, we observed that the absence of FMRP leads to delayed neuronal migration and altered trajectory, associated with defects of centrosomal movement. RNA-interference-induced knockdown of Fmr1 shows that these migratory defects are cell-autonomous. Notably, the primary Fmrp mRNA target implicated in these migratory defects is microtubule-associated protein 1B (MAP1B). Knocking down MAP1B expression effectively rescued most of the observed migratory defects. Finally, we elucidate the molecular mechanisms at play by demonstrating that the absence of FMRP induces defects in the cage of microtubules surrounding the nucleus of migrating neurons, which is rescued by MAP1B knockdown. Our findings reveal a novel neurodevelopmental role for FMRP in collaboration with MAP1B, jointly orchestrating neuronal migration by influencing the microtubular cytoskeleton.

FMRP regulates postnatal neuronal migration via MAP1B

FMRP regulates postnatal neuronal migration via MAP1B

Impact of subthalamic nucleus deep brain stimulation at different frequencies on neurogenesis in a rat model of Parkinson's disease

Neurogenesis, play a vital role in neuronal plasticity of adult mammalian brains, and its dysregulation is present in the pathophysiology of Parkinson's disease (PD). While subthalamic nucleus deep brain stimulation (STN-DBS) at various frequencies has been proven effective in alleviating PD symptoms, its influence on neurogenesis remains unclear. This study aimed to investigate the effects of 1-week electrical stimulation at frequencies of 60Hz, 130Hz, and 180Hz on neurogenesis in the subventricular zone (SVZ) of PD rats. A hemiparkinsonian rat model was established using 6-hydroxydopamine and categorized into six groups: control, PD, sham stimulation, 60Hz stimulation, 130Hz stimulation, and 180Hz stimulation. Motor function was assessed using the open field test and rotarod test after one week of STN-DBS at different frequencies. Tyrosine hydroxylase (TH) expression in brain tissue was analyzed via Western blot and immunohistochemistry. Immunofluorescence analysis was conducted to evaluate the expression of BrdU/Sox2, BrdU/GFAP, Ki67/GFAP, and BrdU/DCX in bilateral SVZ and the rostral migratory stream (RMS). Our findings revealed that high-frequency STN-DBS improved motor function. Specifically, stimulation at 130Hz increased dopaminergic neuron survival in the PD rat model, while significantly enhancing the proliferation of neural stem cells (NSCs) and neuroblasts in bilateral SVZ. Moreover, this stimulation effectively facilitated the generation of new NSCs in the ipsilateral RMS and triggered the emergence of fresh neuroblasts in bilateral RMS, with notable presence within the lesioned striatum. Conversely, electrical stimulation at 60Hz and 180Hz did not exhibit comparable effects. The observed promotion of neurogenesis in PD rats following STN-DBS provides valuable insights into the mechanistic basis of this therapeutic approach for PD.

Evaluating neural crest cell migration in a Col4a1 mutant mouse model of ocular anterior segment dysgenesis

The periocular mesenchyme (POM) is a transient migratory embryonic tissue derived from neural crest cells (NCCs) and paraxial mesoderm that gives rise to most of the structures in front of the eye. Morphogenetic defects of these structures can impair aqueous humor outflow, leading to elevated intraocular pressure and glaucoma. Mutations in collagen type IV alpha 1 (COL4A1) and alpha 2 (COL4A2) cause Gould syndrome – a multisystem disorder often characterized by variable cerebrovascular, ocular, renal, and neuromuscular manifestations. Approximately one-third of individuals with COL4A1 and COL4A2 mutations have ocular anterior segment dysgenesis (ASD), including congenital glaucoma resulting from abnormalities of POM-derived structures. POM differentiation has been a major focus of ASD research, but the underlying cellular mechanisms are still unclear. Moreover, earlier events including NCC migration and survival defects have been implicated in ASD; however, their roles are not as well understood. Vascular defects are among the most common consequences of COL4A1 and COL4A2 mutations and can influence NCC survival and migration. We therefore hypothesized that NCC migration might be impaired by COL4A1 and COL4A2 mutations. In this study, we used 3D confocal microscopy, gross morphology, and quantitative analyses to test NCC migration in Col4a1 mutant mice. We show that homozygous Col4a1 mutant embryos have severe embryonic growth retardation and lethality, and we identified a potential maternal effect on embryo development. Cerebrovascular defects in heterozygous Col4a1 mutant embryos were present as early as E9.0, showing abnormal cerebral vasculature plexus remodeling compared to controls. We detected abnormal NCC migration within the diencephalic stream and the POM in heterozygous Col4a1 mutants whereby mutant NCCs formed smaller diencephalic migratory streams and POMs. In these settings, migratory NCCs within the diencephalic stream and POM localize farther away from the developing vasculature. Our results show for the first time that Col4a1 mutations lead to cranial NCCs migratory defects in the context of early onset defective angiogenesis without affecting cell numbers, possibly impacting the relation between NCCs and the blood vessels during ASD development.

Sensory Stimulation-dependent Npas4 Expression in the Olfactory Bulb during Early Postnatal Development.

The development of the olfactory system is influenced by sensory inputs, and it maintains neuronal generation and plasticity throughout the lifespan. The olfactory bulb contains a higher proportion of interneurons than other brain regions, particularly during the early postnatal period of neurogenesis. Although the relationship between sensory stimulation and olfactory bulb development during the postnatal period has been well studied, the molecular mechanisms have yet to be identified. In this study, we used western blotting and immunohistochemistry to analyze the expression of the transcription factor Npas4, a neuron-specific immediate-early gene that acts as a developmental regulator in many brain regions. We found that Npas4 is highly expressed in olfactory bulb interneurons during the early postnatal stages and gradually decreases toward the late postnatal stages. Npas4 expression was observed in all olfactory bulb layers, including the rostral migratory stream, where newborn neurons are generated and migrate to the olfactory bulb. Under sensory deprivation, the olfactory bulb size and the number of olfactory bulb interneurons were reduced. Furthermore, Npas4 expression and the expression of putative Npas4 downstream molecules were decreased. Collectively, these findings indicate that Npas4 expression induced by sensory input plays a role in the formation of neural circuits with excitatory mitral/tufted cells by regulating the survival of olfactory bulb interneurons during the early stages of postnatal development.

Olfactory bulb anomalies in KBG syndrome mouse model and patients

ANKRD11 (ankyrin repeat domain 11) is a chromatin regulator and the only gene associated with KBG syndrome, a rare neurodevelopmental disorder. We have previously shown that Ankrd11 regulates murine embryonic cortical neurogenesis. Here, we show a novel olfactory bulb phenotype in a KBG syndrome mouse model and two diagnosed patients. Conditional knockout of Ankrd11 in murine embryonic neural stem cells leads to aberrant postnatal olfactory bulb development and reduced size due to reduction of the olfactory bulb granule cell layer. We further show that the rostral migratory stream has incomplete migration of neuroblasts, reduced cell proliferation as well as aberrant differentiation of neurons. This leads to reduced neuroblasts and neurons in the olfactory bulb granule cell layer. In vitro, Ankrd11-deficient neural stem cells from the postnatal subventricular zone display reduced migration, proliferation, and neurogenesis. Finally, we describe two clinically and molecularly confirmed KBG syndrome patients with anosmia and olfactory bulb and groove hypo-dysgenesis/agenesis. Our report provides evidence that Ankrd11 is a novel regulator of olfactory bulb development and neuroblast migration. Moreover, our study highlights a novel clinical sign of KBG syndrome linked to ANKRD11 perturbations in mice and humans.

Wpływ płci na doświadczenia migracyjne Polaków w Niemczech. Przykład Berlina i Hamburga

Gender influences most aspects of migration, placing migrants in slightly different positions in the host country. Gender differences are visible not only in masculinized or feminized migration streams, but also in those that are balanced in terms of gender ratio. In the case of Polish migrations to Germany, the third type of migration streams dominates. This type of migration is characterized by a relatively equal gender structure of Polish migrants. The main aim of this paper is to identify the migration experiences of Poles in the context of revealing gender differences and their potential impact on everyday life in the host country. The article was prepared based on the results of original quantitative (surveys) and qualitative (in-depth interviews) social research conducted among Polish women and men living in Berlin and Hamburg. The example of Germany as a host country allowed to prove that Polish women and men migrants experience the migration process differently. A significant difference in the context of gender was revealed in the following areas: activity in the public sphere, satisfaction with remuneration and level of knowledge of the German language.

Radiation-induced bystander effect on the brain after fractionated spinal cord irradiation of aging rats

We investigated the influence of the so-called bystander effect on metabolic and histopathological changes in the rat brain after fractionated spinal cord irradiation. The study was initiated with adult Wistar male rats (n = 20) at the age of 9 months. The group designated to irradiation (n = 10) and the age-matched control animals (n = 10) were subjected to an initial measurement using in vivo proton magnetic resonance spectroscopy (1H MRS) and magnetic resonance imaging (MRI). After allowing the animals to survive until 12 months, they received fractionated spinal cord irradiation with a total dose of 24 Gy administered in 3 fractions (8 Gy per fraction) once a week on the same day for 3 consecutive weeks. 1H MRS and MRI of brain metabolites were performed in the hippocampus, corpus striatum, and olfactory bulb (OB) before irradiation (9-month-old rats) and subsequently 48 h (12-month-old) and 2 months (14-month-old) after the completion of irradiation. After the animals were sacrificed at the age of 14 months, brain tissue changes were investigated in two neurogenic regions: the hippocampal dentate gyrus (DG) and the rostral migratory stream (RMS). By comparing the group of 9-month-old rats and individuals measured 48 h (at the age of 12 months) after irradiation, we found a significant decrease in the ratio of total N-acetyl aspartate to total creatine (tNAA/tCr) and gamma-aminobutyric acid to tCr (GABA/tCr) in OB and hippocampus. A significant increase in myoinositol to tCr (mIns/tCr) in the OB persisted up to 14 months of age. Proton nuclear magnetic resonance (1H NMR)-based plasma metabolomics showed a significant increase in keto acids and decreased tyrosine and tricarboxylic cycle enzymes. Morphometric analysis of neurogenic regions of 14-month-old rats showed well-preserved stem cells, neuroblasts, and increased neurodegeneration. The radiation-induced bystander effect more significantly affected metabolite concentration than the distribution of selected cell types.