Cortical somatostatin long-range projection neurons and interneurons exhibit divergent developmental trajectories.

The mammalian cerebral cortex contains an extraordinary diversity of cell types that emerge by implementing different developmental programs. Delineating when and how cellular diversification occurs is particularly challenging for cortical inhibitory neurons because they represent a small proportion of all cortical cells and have a protracted development. Here, we combine single-cell RNA sequencing and spatial transcriptomics to characterize the emergence of neuronal diversity among somatostatin-expressing (SST+) cells in mice. We found that SST+ inhibitory neurons segregate during embryonic stages into long-range projection (LRP) neurons and two types of interneurons, Martinotti cells and non-Martinotti cells, following distinct developmental trajectories. Two main subtypes of LRP neurons and several subtypes of interneurons are readily distinguishable in the embryo, although interneuron diversity is likely refined during early postnatal life. Our results suggest that the timing for cellular diversification is unique for different subtypes of SST+ neurons and particularly divergent for LRP neurons and interneurons.

α-Synuclein at the Presynaptic Axon Terminal as a Double-Edged Sword.

α-synuclein (α-syn) is a presynaptic, lipid-binding protein strongly associated with the neuropathology observed in Parkinson's disease (PD), dementia with Lewy bodies (DLB), and Alzheimer's Disease (AD). In normal physiology, α-syn plays a pivotal role in facilitating endocytosis and exocytosis. Interestingly, mutations and modifications of precise α-syn domains interfere with α-syn oligomerization and nucleation that negatively affect presynaptic vesicular dynamics, protein expressions, and mitochondrial profiles. Furthermore, the integration of the α-syn oligomers into the presynaptic membrane results in pore formations, ion influx, and excitotoxicity. Targeted therapies against specific domains of α-syn, including the use of small organic molecules, monoclonal antibodies, and synthetic peptides, are being screened and developed. However, the prospect of an effective α-syn targeted therapy is still plagued by low permeability across the blood-brain barrier (BBB), and poor entry into the presynaptic axon terminals. The present review proposes a modification of current strategies, which includes the use of novel encapsulation technology, such as lipid nanoparticles, to bypass the BBB and deliver such agents into the brain.

Loss of Cntnap2 Causes Axonal Excitability Deficits, Developmental Delay in Cortical Myelination, and Abnormal Stereotyped Motor Behavior.

Contactin-associated protein-like 2 (Caspr2) is found at the nodes of Ranvier and has been associated with physiological properties of white matter conductivity. Genetic variation in CNTNAP2, the gene encoding Caspr2, has been linked to several neurodevelopmental conditions, yet pathophysiological effects of CNTNAP2 mutations on axonal physiology and brain myelination are unknown. Here, we have investigated mouse mutants for Cntnap2 and found profound deficiencies in the clustering of Kv1-family potassium channels in the juxtaparanodes of brain myelinated axons. These deficits are associated with a change in the waveform of axonal action potentials and increases in postsynaptic excitatory responses. We also observed that the normal process of myelination is delayed in Cntnap2 mutant mice. This later phenotype is a likely modulator of the developmental expressivity of the stereotyped motor behaviors that characterize Cntnap2 mutant mice. Altogether, our results reveal a mechanism linked to white matter conductivity through which mutation of CNTNAP2 may affect neurodevelopmental outcomes.

Development and Functional Diversification of Cortical Interneurons.

In the cerebral cortex, GABAergic interneurons have evolved as a highly heterogeneous collection of cell types that are characterized by their unique spatial and temporal capabilities to influence neuronal circuits. Current estimates suggest that up to 50 different types of GABAergic neurons may populate the cerebral cortex, all derived from progenitor cells in the subpallium, the ventral aspect of the embryonic telencephalon. In this review, we provide an overview of the mechanisms underlying the generation of the distinct types of interneurons and their integration in cortical circuits. Interneuron diversity seems to emerge through the implementation of cell-intrinsic genetic programs in progenitor cells, which unfold over a protracted period of time until interneurons acquire mature characteristics. The developmental trajectory of interneurons is also modulated by activity-dependent, non-cell-autonomous mechanisms that influence their ability to integrate in nascent circuits and sculpt their final distribution in the adult cerebral cortex.

Optimization of interneuron function by direct coupling of cell migration and axonal targeting.

Neural circuit assembly relies on the precise synchronization of developmental processes, such as cell migration and axon targeting, but the cell-autonomous mechanisms coordinating these events remain largely unknown. Here we found that different classes of interneurons use distinct routes of migration to reach the embryonic cerebral cortex. Somatostatin-expressing interneurons that migrate through the marginal zone develop into Martinotti cells, one of the most distinctive classes of cortical interneurons. For these cells, migration through the marginal zone is linked to the development of their characteristic layer 1 axonal arborization. Altering the normal migratory route of Martinotti cells by conditional deletion of Mafb-a gene that is preferentially expressed by these cells-cell-autonomously disrupts axonal development and impairs the function of these cells in vivo. Our results suggest that migration and axon targeting programs are coupled to optimize the assembly of inhibitory circuits in the cerebral cortex.

Early emergence of cortical interneuron diversity in the mouse embryo.

GABAergic interneurons (GABA, γ-aminobutyric acid) regulate neural-circuit activity in the mammalian cerebral cortex. These cortical interneurons are structurally and functionally diverse. Here, we use single-cell transcriptomics to study the origins of this diversity in the mouse. We identify distinct types of progenitor cells and newborn neurons in the ganglionic eminences, the embryonic proliferative regions that give rise to cortical interneurons. These embryonic precursors show temporally and spatially restricted transcriptional patterns that lead to different classes of interneurons in the adult cerebral cortex. Our findings suggest that shortly after the interneurons become postmitotic, their diversity is already patent in their diverse transcriptional programs, which subsequently guide further differentiation in the developing cortex.

Tuning of fast-spiking interneuron properties by an activity-dependent transcriptional switch.

The function of neural circuits depends on the generation of specific classes of neurons. Neural identity is typically established near the time when neurons exit the cell cycle to become postmitotic cells, and it is generally accepted that, once the identity of a neuron has been established, its fate is maintained throughout life. Here, we show that network activity dynamically modulates the properties of fast-spiking (FS) interneurons through the postmitotic expression of the transcriptional regulator Er81. In the adult cortex, Er81 protein levels define a spectrum of FS basket cells with different properties, whose relative proportions are, however, continuously adjusted in response to neuronal activity. Our findings therefore suggest that interneuron properties are malleable in the adult cortex, at least to a certain extent.

STIM2 regulates PKA-dependent phosphorylation and trafficking of AMPARs.

STIMs (STIM1 and STIM2 in mammals) are transmembrane proteins that reside in the endoplasmic reticulum (ER) and regulate store-operated Ca(2+) entry (SOCE). The function of STIMs in the brain is only beginning to be explored, and the relevance of SOCE in nerve cells is being debated. Here we identify STIM2 as a central organizer of excitatory synapses. STIM2, but not its paralogue STIM1, influences the formation of dendritic spines and shapes basal synaptic transmission in excitatory neurons. We further demonstrate that STIM2 is essential for cAMP/PKA-dependent phosphorylation of the AMPA receptor (AMPAR) subunit GluA1. cAMP triggers rapid migration of STIM2 to ER-plasma membrane (PM) contact sites, enhances recruitment of GluA1 to these ER-PM junctions, and promotes localization of STIM2 in dendritic spines. Both biochemical and imaging data suggest that STIM2 regulates GluA1 phosphorylation by coupling PKA to the AMPAR in a SOCE-independent manner. Consistent with a central role of STIM2 in regulating AMPAR phosphorylation, STIM2 promotes cAMP-dependent surface delivery of GluA1 through combined effects on exocytosis and endocytosis. Collectively our results point to a unique mechanism of synaptic plasticity driven by dynamic assembly of a STIM2 signaling complex at ER-PM contact sites.

Physically and psychologically hazardous jobs and mental health in Thailand.

This paper investigates associations between hazardous jobs, mental health and wellbeing among Thai adults. In 2005, 87 134 distance-learning students from Sukhothai Thammathirat Open University completed a self-administered questionnaire; at the 2009 follow-up 60 569 again participated. Job characteristics were reported in 2005, psychological distress and life satisfaction were reported in both 2005 and 2009. We derived two composite variables grading psychologically and physically hazardous jobs and reported adjusted odds ratios (AOR) from multivariate logistic regressions. Analyses focused on cohort members in paid work: the total was 62 332 at 2005 baseline and 41 671 at 2009 follow-up. Cross-sectional AORs linking psychologically hazardous jobs to psychological distress ranged from 1.52 (one hazard) to 4.48 (four hazards) for males and a corresponding 1.34-3.76 for females. Similarly AORs for physically hazardous jobs were 1.75 (one hazard) to 2.76 (four or more hazards) for males and 1.70-3.19 for females. A similar magnitude of associations was found between psychologically adverse jobs and low life satisfaction (AORs of 1.34-4.34 among males and 1.18-3.63 among females). Longitudinal analyses confirm these cross-sectional relationships. Thus, significant dose-response associations were found linking hazardous job exposures in 2005 to mental health and wellbeing in 2009. The health impacts of psychologically and physically hazardous jobs in developed, Western countries are equally evident in transitioning Southeast Asian countries such as Thailand. Regulation and monitoring of work conditions will become increasingly important to the health and wellbeing of the Thai workforce.

Sugar sweetened beverages and weight gain over 4 years in a Thai national cohort--a prospective analysis.

INTRODUCTION: Sugar sweetened beverages (SSBs) are implicated in the rising prevalence of obesity and diet-related chronic diseases worldwide. However, little is known about their contribution to weight gain in Asian populations. This study aimed to investigate weight change associated with SSB consumption between 2005 and 2009 in a large national cohort of Thai university students. METHODS: Questionnaire data were collected from a large Thai cohort (the Thai Health-Risk Transition: a National Cohort Study). The analysis was based on responses from 59 283 of the 60 569 (98%) cohort members who had valid SSB consumption and weight variables in 2005 and 2009. The relationship between SSB consumption in 2005 and self-reported weight change was analysed using multiple linear regression models controlled for socio-demographic, activity and (non-validated) dietary factors shown to influence weight. RESULTS: Higher frequency of SSB consumption in 2005 was significantly associated with greater weight gain between 2005 and 2009 in all age groups and in both sexes (p<0.0001); persons who consumed SSBs at least once a day in 2005 gained 0.5 kg more than those who consumed SSBs less than once a month. The estimated weight gain for the average person in the sample was 1.9 kg (95% C I 1.95-1.96). The difference in weight gain between those who increased their consumption frequency ( once per day) between 2005 and 2009 compared to those who maintained it was 0.3 kgs, while persons who reduced their consumption frequency (once a day to > once a month) gained 0.2 kgs less than those whose consumption remained unchanged. CONCLUSION: SSB consumption is independently associated with weight gain in the Thai population. Research and health promotion in Thailand and other economically transitioning countries should focus on reducing their contribution to population weight gain and to diet-related chronic diseases.

Gene discovery for enzymes involved in limonene modification or utilization by the mountain pine beetle-associated pathogen Grosmannia clavigera.

To successfully colonize and eventually kill pine trees, Grosmannia clavigera (Gs cryptic species), the main fungal pathogen associated with the mountain pine beetle (Dendroctonus ponderosae), has developed multiple mechanisms to overcome host tree chemical defenses, of which terpenoids are a major component. In addition to a monoterpene efflux system mediated by a recently discovered ABC transporter, Gs has genes that are highly induced by monoterpenes and that encode enzymes that modify or utilize monoterpenes [especially (+)-limonene]. We showed that pine-inhabiting Ophiostomale fungi are tolerant to monoterpenes, but only a few, including Gs, are known to utilize monoterpenes as a carbon source. Gas chromatography-mass spectrometry (GC-MS) revealed that Gs can modify (+)-limonene through various oxygenation pathways, producing carvone, p-mentha-2,8-dienol, perillyl alcohol, and isopiperitenol. It can also degrade (+)-limonene through the C-1-oxygenated pathway, producing limonene-1,2-diol as the most abundant intermediate. Transcriptome sequencing (RNA-seq) data indicated that Gs may utilize limonene 1,2-diol through beta-oxidation and then valine and tricarboxylic acid (TCA) metabolic pathways. The data also suggested that at least two gene clusters, located in genome contigs 108 and 161, were highly induced by monoterpenes and may be involved in monoterpene degradation processes. Further, gene knockouts indicated that limonene degradation required two distinct Baeyer-Villiger monooxygenases (BVMOs), an epoxide hydrolase and an enoyl coenzyme A (enoyl-CoA) hydratase. Our work provides information on enzyme-mediated limonene utilization or modification and a more comprehensive understanding of the interaction between an economically important fungal pathogen and its host's defense chemicals.

Body mass index, physical activity, and fracture among young adults: longitudinal results from the Thai cohort study.

BACKGROUND: We investigated risk factors for fracture among young adults, particularly body mass index (BMI) and physical activity, which although associated with fracture in older populations have rarely been investigated in younger people. METHODS: In 2009, 4 years after initial recruitment, 58 204 Thais aged 19 to 49 years were asked to self-report fractures incident in the preceding 4 years. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% CIs for associations of fracture incidence with baseline BMI and physical activity. RESULTS: Very obese women had a 70% increase in fracture risk (OR = 1.73, 95% CI 1.21-2.46) as compared with women with a normal BMI. Fracture risk increased by 15% with every 5-kg/m(2) increase in BMI. The effects were strongest for fractures of the lower limbs. Frequent purposeful physical activity was also associated with increased fracture risk among women (OR = 1.52, 95% CI 1.12-2.06 for 15 episodes/week vs none). Neither BMI nor physical activity was associated with fracture among men, although fracture risk decreased by 4% with every additional 2 hours of average sitting time per day (OR = 0.96, 95% CI 0.93-0.99). CONCLUSIONS: The increase in obesity prevalence will likely increase fracture burden among young women but not young men. While active lifestyles have health benefits, our results highlight the importance of promoting injury prevention practices in conjunction with physical activity recommendations, particularly among women.

The genome and transcriptome of the pine saprophyte Ophiostoma piceae, and a comparison with the bark beetle-associated pine pathogen Grosmannia clavigera.

BACKGROUND: Ophiostoma piceae is a wood-staining fungus that grows in the sapwood of conifer logs and lumber. We sequenced its genome and analyzed its transcriptomes under a range of growth conditions. A comparison with the genome and transcriptomes of the mountain pine beetle-associated pathogen Grosmannia clavigera highlights differences between a pathogen that colonizes and kills living pine trees and a saprophyte that colonizes wood and the inner bark of dead trees. RESULTS: We assembled a 33 Mbp genome in 45 scaffolds, and predicted approximately 8,884 genes. The genome size and gene content were similar to those of other ascomycetes. Despite having similar ecological niches, O. piceae and G. clavigera showed no large-scale synteny. We identified O. piceae genes involved in the biosynthesis of melanin, which causes wood discoloration and reduces the commercial value of wood products. We also identified genes and pathways involved in growth on simple carbon sources and in sapwood, O. piceae's natural substrate. Like the pathogen, the saprophyte is able to tolerate terpenes, which are a major class of pine tree defense compounds; unlike the pathogen, it cannot utilize monoterpenes as a carbon source. CONCLUSIONS: This work makes available the second annotated genome of a softwood ophiostomatoid fungus, and suggests that O. piceae's tolerance to terpenes may be due in part to these chemicals being removed from the cells by an ABC transporter that is highly induced by terpenes. The data generated will provide the research community with resources for work on host-vector-fungus interactions for wood-inhabiting, beetle-associated saprophytes and pathogens.

A specialized ABC efflux transporter GcABC-G1 confers monoterpene resistance to Grosmannia clavigera, a bark beetle-associated fungal pathogen of pine trees.

Grosmannia clavigera is a bark beetle-vectored pine pathogen in the mountain pine beetle epidemic in western North America. Grosmannia clavigera colonizes pines despite the trees' massive oleoresin terpenoid defences. We are using a functional genomics approach to identify G. clavigera's mechanisms of adaptation to pine defences. We annotated the ABC transporters in the G. clavigera genome and generated RNA-seq transcriptomes from G. clavigera grown with a range of terpenes. We functionally characterized GcABC-G1, a pleiotropic drug resistance (PDR) transporter that was highly induced by terpenes, using qRT-PCR, gene knock-out and heterologous expression in yeast. Deleting GcABC-G1 increased G. clavigera's sensitivity to monoterpenes and delayed development of symptoms in inoculated young lodgepole pine trees. Heterologous expression of GcABC-G1 in yeast increased tolerance to monoterpenes. G. clavigera but not the deletion mutant, can use (+)-limonene as a carbon source. Phylogenetic analysis placed GcABC-G1 outside the ascomycete PDR transporter clades. G. clavigera appears to have evolved two mechanisms to survive and grow when exposed to monoterpenes: GcABC-G1 controls monoterpene levels within the fungal cells and G. clavigera uses monoterpenes as a carbon source. This work has implications for understanding adaptation to host defences in an important forest insect-fungal system, and potentially for metabolic engineering of terpenoid production in yeast.

Association between occupational heat stress and kidney disease among 37,816 workers in the Thai Cohort Study (TCS).

BACKGROUND: We examined the relationship between self-reported occupational heat stress and incidence of self-reported doctor-diagnosed kidney disease in Thai workers. METHODS: Data were derived from baseline (2005) and follow-up (2009) self-report questionnaires from a large national Thai Cohort Study (TCS). Analysis was restricted to full-time workers (n = 17 402 men and 20 414 women) without known kidney disease at baseline. We used logistic regression models to examine the association of incident kidney disease with heat stress at work, after adjustment for smoking, alcohol drinking, body mass index, and a large number of socioeconomic and demographic characteristics. RESULTS: Exposure to heat stress was more common in men than in women (22% vs 15%). A significant association between heat stress and incident kidney disease was observed in men (adjusted odds ratio [OR] = 1.48, 95% CI: 1.01-2.16). The risk of kidney disease was higher among workers reporting workplace heat stress in both 2005 and 2009. Among men exposed to prolonged heat stress, the odds of developing kidney disease was 2.22 times that of men without such exposure (95% CI 1.48-3.35, P-trend <0.001). The incidence of kidney disease was even higher among men aged 35 years or older in a physical job: 2.2% exposed to prolonged heat stress developed kidney disease compared with 0.4% with no heat exposure (adjusted OR = 5.30, 95% CI 1.17-24.13). CONCLUSIONS: There is an association between self-reported occupational heat stress and self-reported doctor-diagnosed kidney disease in Thailand. The results indicate a need for occupational health interventions for heat stress among workers in tropical climates.

Secular changes and predictors of adult height for 86 105 male and female members of the Thai Cohort Study born between 1940 and 1990.

BACKGROUND: Height trends can be useful indicators of population health but, despite Thailand's rapid socioeconomic development since the 1950s, few studies have examined accompanying secular changes in adult height or the effects of the transition on the heights of rural versus urban populations. This study therefore sought to document average heights in different age groups of rural and urban Thais and to investigate factors associated with attained height. METHODS: Data from 86,105 Thai Cohort Study participants was used to estimate mean heights for men and women in different birth year groups. Simple regression was used to calculate the change in height per decade of birth year among those based in rural or urban locations as children. Multiple linear regression was used to investigate effects of other childhood factors on height. RESULTS: Overall, average heights were found to have increased by approximately 1 cm per decade in those born between 1940 and 1990. However, the rate of increase was 0.4-0.5 cm per decade greater among urban-based Thais compared with those from the countryside. Parental education levels, household assets, birth size, sibling number, birth rank and region of residence were also significantly associated with adult height. CONCLUSIONS: These data suggest a marked secular increase in Thai heights in the second half of the 20th century probably reflecting improved childhood health and nutrition over this time. Rural-born Thais, who benefited to a lesser extent from the changes, may face future health challenges with greater risks of, among other things, obesity and its health consequences.

Relationship of obesity to physical activity, domestic activities, and sedentary behaviours: cross-sectional findings from a national cohort of over 70,000 Thai adults.

BACKGROUND: Patterns of physical activity (PA), domestic activity and sedentary behaviours are changing rapidly in Asia. Little is known about their relationship with obesity in this context. This study investigates in detail the relationship between obesity, physical activity, domestic activity and sedentary behaviours in a Thai population. METHODS: 74,981 adult students aged 20-50 from all regions of Thailand attending the Sukhothai Thammathirat Open University in 2005-2006 completed a self-administered questionnaire, including providing appropriate self-reported data on height, weight and PA. We conducted cross-sectional analyses of the relationship between obesity, defined according to Asian criteria (Body Mass Index (BMI) ≥25), and measures of physical activity and sedentary behaviours (exercise-related PA; leisure-related computer use and television watching ("screen-time"); housework and gardening; and sitting-time) adjusted for age, sex, income and education and compared according to a range of personal characteristics. RESULTS: Overall, 15.6% of participants were obese, with a substantially greater prevalence in men (22.4%) than women (9.9%). Inverse associations between being obese and total weekly sessions of exercise-related PA were observed in men, with a significantly weaker association seen in women (p(interaction) < 0.0001). Increasing obesity with increasing screen-time was seen in all population groups examined; there was an overall 18% (15-21%) increase in obesity with every two hours of additional daily screen-time. There were 33% (26-39%) and 33% (21-43%) reductions in the adjusted risk of being obese in men and women, respectively, reporting housework/gardening daily versus seldom or never. Exercise-related PA, screen-time and housework/gardening each had independent associations with obesity. CONCLUSIONS: Domestic activities and sedentary behaviours are important in relation to obesity in Thailand, independent of exercise-related physical activity. In this setting, programs to prevent and treat obesity through increasing general physical activity need to consider overall energy expenditure and address a wide range of low-intensity high-volume activities in order to be effective.

Social Capital, Trust, Economic Stress and Religion in a Cohort of 87,134 Thai Adults.

Social capital includes collective features such as social trust, norms, and networks. This paper examines social capital-related variables against demographic, socioeconomic and geographic characteristics of 87,134 adult distance-learning students from Sukhothai Thammathirat Open University.We have found economic stress to be higher in non-married groups, lower income groups, and those residing in rural areas. Social trust was higher among married, especially with higher income and those in rural areas. Those who were separated, divorced or widowed and those with lower socioeconomic status had the highest economic stress and the least social trust. These groups also reported high importance of religious belief, karma and spiritual belief, along with lower income groups. Despite having high economic stress, social interaction with and support from families were found to be high among those not-married, with lower income, and in rural areas.As Thailand urbanises and progresses economically, diverse patterns of social capital have emerged and some changes might have offset others. For example, we have shown that economic stress associated with low income tends to co-occur with high social interaction and family support. This observation should be reassuring to policymakers aiming to preserve and promote social capital as Thailand continues to urbanise and modernise.

Social capital and health in a national cohort of 82,482 Open University adults in Thailand.

We report associations between social capital and health among 82,482 adults in a national cohort of Open University students residing throughout Thailand.After adjusting for covariates, poor self-assessed health was positively associated with low social trust (OR = 1.88; 95% CI 1.76-2.01) and low social support (OR = 1.79; 95% CI 1.63-1.95). In addition, poor psychological health was also associated with low social trust (OR = 2.52; 95% CI 2.41-2.64) and low social support (OR = 1.80; 95% CI 1.69-1.92). Females, elderly, unpartnered, low income, and urban residents were associated with poor health. Findings suggest ways to improve social capital and heath in Thailand and other middle-income countries.