Biology subjects

Nam, H. Y.

Publications and source records attributed to Nam, H. Y..

5 recordsLinked to original sources

bioRxiv2024

Photoperiodicity in Glucose Metabolism in the Human Brain

Photoperiodicity in the human brain function, which is a critical factor for social well-being, has been widely debated. In this study, 432 healthy males underwent fasting-state brain [18F]fluorodeoxyglucose positron emission tomography (PET) scanning twice: first at the baseline and then at the 5-year follow-up. We analyzed the effect of day length on brain glucose uptake separately for the baseline and follow-up studies and examined changes in glucose consumption as a function of the day length deviation for each participant between the repeated PET scans. Glucose uptake in the cuneus was consistently predicted by the day length on the day of scanning and by within-participant day length deviations. This longitudinal large-scale PET study provides a landmark evidence for photoperiodicity in glucose metabolism in the human brain. The cuneus may be an essential part of the visual cortex, translating environmental photoperiodic changes into temporal cues that influence cognitive function and social behavior. Significance statementPhotoperiodicity in the human brain function has been widely debated. The current study provides a landmark evidence in this regard by demonstrating how the photoperiod shapes glucose metabolism in the brain of healthy males, highlighting the crucial role of the cuneus in processing visual information related to photoperiodic changes in the environment. Understanding photoperiodicity in the function of the human brain offers insights into how humans adapt to their environments for social well-being and underscores the potential health implications of changes in the exposure of natural light.

neuroscience↗

bioRxiv2022

Brain glucose metabolism and ageing: A 5-year longitudinal study in a large PET cohort

BackgroundAgeing and clinical factors impact brain glucose metabolism. However, there is a substantial variation of the reported effects on brain glucose metabolism across studies due to the limited statistical power and cross-sectional study designs. MethodsWe retrospectively analyzed data from 441 healthy males (mean 42.8, range 38-50 years) who underwent health check-up program twice at baseline and 5-year follow-up. Health check-up program included 1) brain 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET), 2) anthropometric and body composition measurements, 3) blood samples, and 4) questionnaires for stress and depression. After spatial normalization of brain FDG PET scans, standardized uptake value ratio (SUVR) was measured from 12 region-of-interests. We used hierarchical clustering analysis to reduce their dimensionality before the Bayesian hierarchical modelling. Five clusters were established for predicting regional SUVR; 1) metabolic cluster (body mass index, waist-to-hip ratio, fat percentage, muscle percentage, homeostatic model assessment index-insulin resistance), 2) blood pressure (systolic, diastolic), 3) glucose (fasting plasma glucose level, HbA1c), 4): psychological cluster (stress, depression), and 5) heart rate. The effects of clinical variable clusters on regional SUVR were investigated using Bayesian hierarchical modelling with brms that applies the Markov-Chain Monte Carlo sampling tools. ResultsAll the clinical variables except depression changed during the 5-year follow-up. SUVR decreased in caudate, cingulate, frontal lobe and parietal lobe and increased in cerebellum, hippocampus, occipital lobe, pallidum, putamen, temporal lobe and thalamus. SUVRs of thalamus, pallidum, hippocampus, putamen and parietal lobe were negatively associated with metabolic cluster and the effects of glucose on SUVRs varied across regions. SUVRs of thalamus, hippocampus, cingulate, cerebellum increased and those with occipital lobe decreased with heart rate. The effects of blood pressure and psychological cluster markedly overlapped with zero across regions. ConclusionRegionally selective decline in brain glucose utilization begins already in the middle age, while individual differences in brain glucose metabolism remain stable. In addition to ageing, brain glucose utilization is also associated with metabolic cluster, blood glucose levels and heart rate. These effects are also consistent over the studied period of 5 years in the middle adulthood.

neuroscience↗

bioRxiv2020

Development of a species diagnostic molecular tool for an invasive pest, Mythimna loreyi using LAMP

The Mythimna loreyi (Duponchel) is one of the well-known a noctuid pest in Africa, Australia, and many Asian countries. This species has recently emerged as an invasive pest of some cereal crops in Korea. However, it is extremely difficult to identify the morphologically similar species, Mythimna separate, which occur at the cornfield in the larvae stage. Therefore, it is hard to accurately investigate invasive pests. In this study, the LAMP assay was developed for rapid, simple, effective species identification. By analyzing the mt genome, the species-specific sequence was found at the coding region of the NADH dehydrogenase subunit 5 gene. Based on this unique sequence, four LAMP primers and two loop primers were designed. The F3 and B3 primers were able to diagnose species-specific in general and multiplex PCR, and specifically reacted within the inner primers in LAMP assay. The optimal incubation condition of the LAMP assay was 61 {square} for 60 minutes with four LAMP primers, though additional loop primer, BF and LF, did not significantly shorten the amplification time. The broad range of DNA concentration was workable in LAMP assay, in which the minimum detectable DNA concentration was 100 pg. Here, DNA releasing method was applied which took five minutes of incubation at 95 {square} without the DNA extraction process, and only some pieces of tissue from larvae and adult samples were needed. The incidence of invasive pests is gradually diversifying, therefore, this simple and accurate LAMP assay possibly applied in the intensive field monitoring for the invasive pests and integrated management of Mythimna loreyi.

ecology↗

bioRxiv2020

Development of a diamide resistance diagnostic method using LAMP based on a resistance-specific indel in ryanodine receptors for Spodoptera exigua (Lepidoptera: Noctuidae)

Recently, resistance to diamide insecticides (IRAC group 28) has been reported in various lepidopteran pests, including Spodoptera exigua. In the present study, susceptibility of six field populations was evaluated to two diamide insecticides: chlorantraniliprole and flubendiamide. The bioassay test for resistance revealed a high level of diamide resistance and helped to select a diamide resistant (Di-R) strain, whose LC50 values against chlorantraniliprole and flubendiamide were 28,950- and 135,286-fold higher, respectively, than those of susceptible strains. In the ryanodine receptor, instead of the G4946E mutation, one of the well-known diamide resistance mechanisms, we found a I4790M mutation and identified the resistance allele-specific indel linked to it. Resistance allele diagnostic primers were designed using this distinct region and applied in loop-mediated isothermal amplification (LAMP) and general PCR. LAMP accurately detected the specific indel when conducted for 2 h at temperature range from 63 {degrees}C to 65 {degrees}C and using four LAMP primers; its efficiency was further amplified by an additional loop primer. A broad range of DNA concentrations was workable in the LAMP assay, with the minimum detectable DNA concentration of 100 pg. The new DNA releasing method used for the LAMP assay consisted of 5 min of incubation of a larva or adult tissue at 95{degrees}C. The entire diagnostic process, which included the DNA releasing technique and LAMP, lasted only 100 min. This simple and accurate LAMP assay can be applied to monitor diamide resistance and for integrated resistance management of S. exigua in the field.

ecology↗

bioRxiv2020

Development of a simple and accurate molecular tool for Spodoptera frugiperda species identification using LAMP

The fall armyworm, Spodoptera frugiperda is a native species in the Americas. However, nowadays it is one of the most serious invasive lepidopteran pests in African and Asian countries. S. frugiperda has been spread very quickly after the first outbreak was reported in many countries. Based on mt genome sequence alignment, S. frugiperda specific sequence region was identified in tRNAs coding region between NADH dehydrogenase, ND3 and ND5. By using this unique region, species diagnostic primers were designed and applied in LAMP (lamp loop mediated isothermal amplification) assay as well as conventional PCR to identify the field-collected samples of S. frugiperda. Optimal incubation condition of LAMP assay was 61{degrees}C for 90 minutes with 4 LAMP primers, and additional loop primer increased the amplification efficiency. Also, wide range of DNA concentration responded in LAMP assay and minimum detectable DNA concentration was 10 pg. This LAMP assay was also applied in DNA releasing technique from larval and adult sample, without DNA extraction, 95{degrees}C incubation for five minutes of the tissue sample. This new molecular diagnostic method is easy to use and accurate. It possibly applied in intensive field monitoring of S. frugiperda and its ecological studies.

ecology↗