Sleep Deprivation Influences Diurnal Variation of Human Time Perception with Prefrontal Activity Change: A Functional Near-Infrared Spectroscopy Study

Human short-time perception shows diurnal variation. In general, short-time perception fluctuates in parallel with circadian clock parameters, while diurnal variation seems to be modulated by sleep deprivation per se. Functional imaging studies have reported that short-time perception recruits a neural network that includes subcortical structures, as well as cortical areas involving the prefrontal cortex (PFC). It has also been reported that the PFC is vulnerable to sleep deprivation, which has an influence on various cognitive functions. The present study is aimed at elucidating the influence of PFC vulnerability to sleep deprivation on short-time perception, using the optical imaging technique of functional near-infrared spectroscopy. Eighteen participants performed 10-s time production tasks before (at 21:00) and after (at 09:00) experimental nights both in sleep-controlled and sleep-deprived conditions in a 4-day laboratory-based crossover study. Compared to the sleep-controlled condition, one-night sleep deprivation induced a significant reduction in the produced time simultaneous with an increased hemodynamic response in the left PFC at 09:00. These results suggest that activation of the left PFC, which possibly reflects functional compensation under a sleep-deprived condition, is associated with alteration of short-time perception.     

Spo5/Mug12, a putative meiosis-specific RNA-binding protein, is essential for meiotic progression and forms Mei2 dot-like nuclear foci

We report here a functional analysis of spo5(+)(mug12(+)) of Schizosaccharomyces pombe, which encodes a putative RNA-binding protein. The disruption of spo5(+) caused abnormal sporulation, generating inviable spores due to failed forespore membrane formation and the absence of a spore wall, as determined by electron microscopy. Spo5 regulates the progression of meiosis I because spo5 mutant cells display normal premeiotic DNA synthesis and the timely initiation of meiosis I but they show a delay in the peaking of cells with two nuclei, abnormal tyrosine 15 dephosphorylation of Cdc2, incomplete degradation of Cdc13, retarded formation and repair of double strand breaks, and a reduced frequency of intragenic recombination. Immunostaining showed that Spo5-green fluorescent protein (GFP) appeared in the cytoplasm at the horsetail phase, peaked around the metaphase I to anaphase I transition, and suddenly disappeared after anaphase II. Images of Spo5-GFP in living cells revealed that Spo5 forms a dot in the nucleus at prophase I that colocalized with the Mei2 dot. Unlike the Mei2 dot, however, the Spo5 dot was observed even in sme2Delta cells. Taken together, we conclude that Spo5 is a novel regulator of meiosis I and that it may function in the vicinity of the Mei2 dot.     

Drift patterns of particulate matter and organisms during artificial high flows in a large experimental channel

Using a large experimental channel, five artificial high flows with different flow regimes were launched to reveal the precise temporal sequences of drifting particulate matter and organisms during the high flows. Drifting fine particulate matter and organisms were collected by sampling bottles and a water pump, respectively. The peaks of drift abundance occurred before the peak discharges, and the abundance declined quickly within several minutes during the rising phase of high flows. The major determinant of drift abundance of particulate matter and organisms was periods of stable conditions before each high flow (tested by determination coefficients in a correlation analysis). The drift of macroscopic plant material also accelerated the drifts of epiphytic fauna and infauna, which drifted with plants and bed sediments. The magnitude (discharge and duration of peak flows) of high flows only slightly affected drift abundance. The fauna more resistant to high flows were invertebrates that fasten their cases or retreats by silk threads on the substrata. Invertebrate taxa having sucking apparatus or high swimming activity were also resistant to high flows.     

Interferonbeta-induced changes in metallothionein expression and subcellular distribution of zinc in HepG2 cells

We evaluated the changes of metallothionein induction and cellular zinc distribution in HepG2 cells by interferonbeta treatment. Immunohistochemical staining of metallothionein was observed in the cytoplasm and nuclei of hepatocytes; which was observed predominantly in the cells treated with interferon and zinc compared to those with zinc alone, interferon alone or the no-treated control. The cellular zinc level was higher in order of the interferon- and zinc-treated cells, the zinc-alone-treated cells, and the interferon-alone-treated cells. Flow cytometry showed that S-phase population increased in interferon-alone-treated cells and interferon- and zinc-treated cells, but not in zinc-alone-treated ones. Cellular elemental distribution was analyzed using in-air micro-particle induced X-ray emission. In zinc-alone-treated sample, X-ray spectra showed good consistency between the enhanced cellular zinc distribution and the phosphorous map. Localizations of bromine followed by interferon treatment were found accompanying a spatial correlation with the phosphorous map. The samples treated with interferon and zinc showed the marked accumulation of zinc and bromine. Discrete bromine accumulation sites were clearly visible with a strong spatial correlation followed by zinc accumulation. These findings suggest that interferonbeta in combination with zinc predominantly induces metallothionein expression in HepG2 cells. In addition, interferonbeta may promote the translocation of metallothionein-bound zinc from cytoplasm to S-phase nuclei.     

Changes in plasma alpha and gamma tocopherol levels before and after long-term local hyperthermia in cancer patients

Local hyperthermia is one of the heat therapies for cancer patients. The effect of this therapy is recognized to affect the immune function. On the other hand, researchers have recently suggested that vitamin E has not only antioxidant but also other functions including the immune function. However, the association between local hyperthermia therapy and vitamin E level is not yet well understood. Comparing plasma alpha and gamma tocopherol levels before and after the therapy, the basal levels of both tocopherols in the cancer patients did not significantly differ from those in healthy subjects. However, the interindividual difference in the basal levels was very wide in the cancer patients. After long-term local hyperthermia (more than 70 days), the levels of both tocopherols were significantly higher than the basal levels. This result suggests that long-term local hyperthermia therapy influences plasma tocopherol level in cancer patients; thus, an increase in vitamin E level may play an important role in the therapy of cancer patients.     

Impaired flow-dependent control of vascular tone and remodeling in P2X4-deficient mice

The structure and function of blood vessels adapt to environmental changes such as physical development and exercise. This phenomenon is based on the ability of the endothelial cells to sense and respond to blood flow; however, the underlying mechanisms remain unclear. Here we show that the ATP-gated P2X4 ion channel, expressed on endothelial cells and encoded by P2rx4 in mice, has a key role in the response of endothelial cells to changes in blood flow. P2rx4(-/-) mice do not have normal endothelial cell responses to flow, such as influx of Ca(2+) and subsequent production of the potent vasodilator nitric oxide (NO). Additionally, vessel dilation induced by acute increases in blood flow is markedly suppressed in P2rx4(-/-) mice. Furthermore, P2rx4(-/-) mice have higher blood pressure and excrete smaller amounts of NO products in their urine than do wild-type mice. Moreover, no adaptive vascular remodeling, that is, a decrease in vessel size in response to a chronic decrease in blood flow, was observed in P2rx4(-/-) mice. Thus, endothelial P2X4 channels are crucial to flow-sensitive mechanisms that regulate blood pressure and vascular remodeling.     

Detection of allogeneic Qa/TL and Ly specificities on murine tumor cells with IgD in tumor-regressor serum

Summary Serum from C3H/He mice, which show regression of MM2 tumor cells after transplantation and removal (regressor serum, RS) contains non-gammaglobulin components that cross-react with various tumor cells of mice [22, 23]. In addition to tumor cells, various allogeneic lymphocytes are also susceptible to an RS-dependent lymphocyte-mediated cytotoxic reaction. To identify tumor cell surface antigens that cause the cross-reactive host response, the serum components were analyzed by absorption of RS with allogeneic lymphocytes. RS components were found to recognize allogeneic lymphocyte antigens including Qa-2 and Ly6.2. Specificity for the Qa-2 antigen was further tested using Qa-2-congenic mice. The expression of Qa-2 antigen was detected on the surfaces of MM2 and other tumor cells derived from H-2^k mice (seven among nine cell lines tested) by a membrane immunofluorescence method using a Qa-2-specific mAb. Physical characteristics of the Qa-2-specific component in RS were determined and found to differ from those of regular IgGs but to be similar to those of IgDs. Using an enzyme-linked immunosorbent assay with an IgD-specific mAb and Qa-2-lacZ fusion protein, the existence of IgD in RS with specificity for Qa-2 was confirmed. These results suggest that the RS component with Qa-2 specificity is an IgD, the specificity and physiological role of which are unknown.     

Different cell cycle mechanisms between UV-induced and X-ray-induced apoptosis in WiDr colorectal carcinoma cells

Although DNA-damaging agents such as ultraviolet (UV) and X-ray can induce apoptosis, the difference in the apoptotic mechanism is not clearly understood. In the present study, we investigated the effects of these two genotoxic agents on the induction of DNA damage and subsequent apoptotic cell death from the viewpoint of cell cycle regulation by using WiDr cells. Transient G1 arrest was observed after UV exposure, whereas G2 but not G1 arrest was induced after X-ray irradiation. UV-exposure could induce G1 arrest in both mutant-type (mt-p53) and wild-type p53 (wt-p53) cells, but obvious G1 arrest was not observed in the cells lacking in p53 expression. An increase in the DNA fragmentation was observed at S phase in UV-irradiated cells and at G2 phase in X-irradiated cells, respectively. UV-irradiated cells showed an increase production of p53 protein and accumulation of p21 protein. On the contrary, both p53 and p21 proteins remained at a low level in X-irradiated cells. Treatment with aphidicolin, an S phase blocking agent, prolonged cell cycle arrest and reduced the rate of apoptotic cell death in both UV-irradiated and X-irradiated cells. From these results, it is suggested that UV-induced apoptosis occurs mainly at S phase and is regulated by increased production of p53 and p21 proteins, while X-ray-induced apoptosis occurs after G2 blockade and may be independent of p53.