• The Korean Journal of Physiology and Pharmacology
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• v.25 no.6
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• pp.575-583
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• 2021

Composition of the gut microbiota changes with aging and plays an important role in age-associated disease such as metabolic syndrome, cancer, and neurodegeneration. The gut microbiota composition oscillates through the day, and the disruption of their diurnal rhythm results in gut dysbiosis leading to metabolic and immune dysfunctions. It is well documented that circadian rhythm changes with age in several biological functions such as sleep, body temperature, and hormone secretion. However, it is not defined whether the diurnal pattern of gut microbial composition is affected by aging. To evaluate aging effects on the diurnal pattern of the gut microbiome, we evaluated the taxa profiles of cecal contents obtained from young and aged mice of both sexes at daytime and nighttime points by 16S rRNA gene sequencing. At the phylum level, the ratio of Firmicutes to Bacteroidetes and the relative abundances of Verrucomicrobia and Cyanobacteria were increased in aged male mice at night compared with that of young male mice. Meanwhile, the relative abundances of Sutterellaceae, Alloprevotella, Lachnospiraceae UCG-001, and Parasutterella increased in aged female mice at night compared with that of young female mice. The Lachnospiraceae NK4A136 group relative abundance increased in aged mice of both sexes but at opposite time points. These results showed the changes in diurnal patterns of gut microbial composition with aging, which varied depending on the sex of the host. We suggest that disturbed diurnal patterns of the gut microbiome can be a factor for the underlying mechanism of age-associated gut dysbiosis.

• Ocean and Polar Research
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• v.36 no.1
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• pp.59-69
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• 2014

The long-term mooring performed at a KOGA station, located at about $30^{\circ}20^{\prime}N$, $126^{\circ}12^{\prime}E$ in the East China Sea shelf, shows some different behaviors between "semi-diurnal" and "diurnal currents" defined as the currents with periods around, respectively, a half day and a day. They appear to be predominantly tidal having significant coherences with sea level changes around the semi-diurnal and diurnal frequencies. The "semi-diurnal current" is strongly barotropic all year round. However, contrastingly, it is largely baroclinic in summer in the area about 70 km nearer to the continental slope, referred to as the "slope-area", as was found in previous current observations. The "diurnal current" of tidal origin is strongly barotropic in winter. In spring and summer, however, it becomes more baroclinic although it still remains largely barotropic, also showing more of its barotropic nature than in the "slope-area". The inertial oscillation contributing to the "diurnal current" appears to be more prominent when the current is baroclinic, indicating the important role played by stratification in generation of inertial oscillations. Downward energy propagation of inertial oscillation is not observed, suggesting that it is not created at the surface by wind. Considering that the study area is both near a critical latitude and proximity to the continental slope, it is suggested that parametric subharmonic instability (PSI) plays a significant role in creating the baroclinic inertial oscillation.

• Journal of Korean Society of Forest Science
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• v.54 no.1
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• pp.76-79
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• 1981

This thesis emphasize on diurnal changes of leaf water potential in relation to differences of cutting arrangement. 1. The more is leaves attached to the cutting, the higher is water stress in the cutting compared with less leaves. 2. The less is diameter of cut-part, the more are shown changes in increased and decrease in diurnal leaf water potential. 3. The more is length of stem, the more are shown water stress in diurnal leaf water potential 4. There is no differences between earthen-ball cutting and non-earthen ball cutting in diurnal leaf water potential. 5. Cuttings with two year's slip, compared with one year's leaf water potential increases slowly, dry weigh of root and numbers of rooted cutting are most likely dependent upon other factors rather than the water stress.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.119-127
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• 2000

Diurnal vertical distribution of phytoplankton and physico-chemical characteristics were studied in Kongsan reservoir during summer 1996, when a dense algal bloom, consisting mostly of Microcystis, developed. The maximum biomass was observed near the surface layer, where Microcystis aeruginosa dominated and declined gradually with depth. The dense population of blue-green alga M. aeruginosa acumulated near the surface layer during the early morning and evening, but abruptly decreased after sunrise. The most of biomass was distributed above 5 m of the water column and diurnal changes of biomass clearly appeared at the surface but was not showed upward and downward migration. The results of this study suggest that diurnal variation of biomass at the surface layer was affected by horizontal migration with wind.

• Journal of Ginseng Research
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• v.17 no.3
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• pp.240-245
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• 1993

This study was conducted with ginseng plants to investigate photosynthetic response to changes of light intensity and leaf temperature. $CO_2$ uptake in diurnal course was highest in the first phase (8 00~5 : 30 Am.) on May 30, 1992. In $CO_2$ uptake related to stomatal conductance, these relationship was synchronized in diurnal course, but relationship between TEX>$CO_2$ uptake and intercellular $CO_2$ concentration in diurnal course was synchronized oppositely. Leaf temperature and light intensity at the highest $CO_2$ uptake were in the range of 23~$24^{\circ}C$) and 95$\mu$mol.$m^{-2}$.$s^{-1}$), $CO_2$ , respectively. In response to an increasing light intensity under a constant leaf temperature ($18^{\circ}C$), $CO_2$ uptake was increased throughout the light intensity sequence up to 250$\mu$mol.$m^{-2}$.$s^{-1}$), $CO_2$ When $CO_2$ uptake was measured with a series of leaf temperature under a constant light intensity (250 $\mu$mol.$m^{-2}$.$s^{-1}$), $CO_2$ uptake was highest at $18^{\circ}C$ as a 4.1$\mu$mol.$m^{-2}$.$s^{-1}$), $CO_2$ . Similar changes were also observed in stomatal conductance and intercellular $CO_2$ concentration. Evidences from several approaches indicate that synchronization of $CO_2$ uptake, stomatal conductance and intercellular $CO_2$ concentration were closely inter-related and changes of leaf temperature iuluenced the photo-response in photosynthetic processes.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.12
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• pp.1708-1716
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• 2000

A study was made of diurnal changes in the ruminal bacteria associated with feed particles, i.e., non-associated (NAB), loosely associated (LAB), and tightly associated with particles (TAB), and the TAB concentration in different particle sizes from sheep fed orchardgrass (OG) or alfalfa (ALF) hay. Diaminopimelic acid (DAPA) was used to determine the TAB mass. Results showed that the bacterial masses in NAB and LAB were small, but comprised over 90% in TAB. The TAB mass in the ALF group sharply increased within 2 h after feeding and decreased afterward. The TAB mass showed the same trend in the OG group, increasing from 0 h to 2 h, but remained at the same level up to 14 h after feeding. The peak bacterial mass was, however, lower in the OG than the ALF group. The TAB concentration reflected the changes in total particulate tightly associated bacterial masses in both groups of hay fed sheep. Number of bacterial colonies per particle increased as the particulate size decreased in both groups. This difference, however, tended to decline as the postprandial period was prolonged. DAPA, however, tended to overestimate the TAB mass in the reticulo-rumen digesta of the hay fed sheep.

• Animal cells and systems
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• v.5 no.2
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• pp.117-126
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• 2001

Occurence, seasonal changes and vertical distribution of the silica-scaled chrysophytes in a small fish-free pond were studied using electron microscopy (EM) and light microscopy (LM) from October 1998 to July 1999. The phytoplankton community was characterized by Chrysophyta and Cryptophyta. Ten species of the silica-scaled chrysophytes of genera Mallomonas, Synura, Chrysosphaerella and Spiniferomonas were identified by EM, and the most abundant species were Mallomonas akrokomos and M. portae-ferreae. The maximum population density of M. akrokomos was observed in December and several peaks appeared periodically at about one to two month intervals, whereas M. portae-ferreae developed the maximum density in March. The diurnal vertical distribution of M. akrokomos exhibited clear downward migration at night and slightly upward migration in the morning. A complex interaction among physico-chemical and biological factors seemed to affect the vertical distribution of M. akrokomos. However, the seasonal changes of M. akrokomos did not show significant corre1ations with the physico-chemical and some biologica1 factors. Although M. akrokomos was evenly distributed throughout the water column during some experimental periods, the diurnal patterns found in the two diurnal cycles showed consistency in that it clearly avoided the surface water during the day. This suggested that M. akrokomos may be a shade plankton with maximum densities below surface layer.

• Journal of Korean Foot and Ankle Society
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• v.24 no.4
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• pp.142-147
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• 2020

Purpose: Diabetic foot ulcers are closely related to body surface heat, which can be affected easily by temperature differences. This study examined the correlation between the healing process of diabetic wounds and abnormal diurnal temperature through an animal study. Materials and Methods: Rats in the abnormal diurnal temperature group and control group were given a 10 mm sized full-thickness skin ulcer. Wound size progression was observed in both groups. H&E and Masson's trichrome staining was performed at 14 days after wound formation, and the number of vessels per unit area and histology analysis were performed. The changes in the ulcer were measured through three dimensional cross-section area using INSIGHT^® devices. Results: The wound recovery period (granulation ingrowing) was 24 days in the abnormal diurnal temperature model and 20 days in the control group. The thickness of scar tissue was 402±23.19 ㎛ in the control group and 424.5±36.94 ㎛ in the diurnal temperature model. Neovascular formation was counted as 5.1±0.97 for the control group and 4.16±0.94 for the diurnal temperature model group. Conclusion: Delayed and inferior diabetic wound healing was observed in the abnormal diurnal temperature group, which was characterized by greater diurnal variations than the typical growth environment.

• Journal of Environmental Science International
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• v.16 no.5
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• pp.633-640
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• 2007

The diurnal changes of chlorophyll fluorescence and antioxidative enzyme activity were investigated in the leaves from four subtropical plant species (Crinum asiaticum var. japonicum Bak., Osmanthus insularis Koidz., Asplenium antiquum Makino and Chloranthus glaber Makino) under the natural habitats in summer and winter. The intensity of chlorophyll fluorescence was lower in O-, I-, J-, P-steps of O-J-I-P transient in winter than summer, and prominent diurnal change was not found in the fluorescence intensity of four subtropical plant species in winter. The activity and isoenzyme pattern of SOD and catalase did irregularly change seasonally and diurnally in four subtropical plant species. In contrast, the peroxidase activity and isoenzyme pattern was different depending on plant species and growth seasons; The activity increased slightly more in winter than in summer in four subtropical plant species, and several isoenzymes appeared in the leaves from C. asiaticum var japonicum, O. insularis and A. antiquum in winter.

• Atmosphere
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• v.16 no.1
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• pp.49-53
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• 2006

The present study has examined interdecadal variations of the diurnal temperature range (DTR, daily maximum temperature minus daily minimum temperature) during the New Year season in Seoul for the period 1954-2005. Here, the average DTR for the New Year holidays (three consecutive days; one day before the New Year, the New Year day, and one day after the New Year) minus the average DTR for 14 days, 7 days before and 7 days after the New Year holidays, is defined for representing the New Year effect. The DTR index does not show notable trend until the late 1970s but shows obvious positive values afterward. For example, the difference of the average DTR between two periods (1980-2005 minus 1954-1979) is $0.65^{\circ}C$, which is meaningful at the 95% confidence level. This result demonstrates that intense human activity even for the limited period may provide climate impact in local regions. Its plausible causes are discussed.