Transdisciplinary unifying implications of circadian findings in the 1950s

Afew puzzles relating to a small fraction of my endeavors in the 1950s are summarized herein, with answers to a few questions of the Editor-in-Chief, to suggest that the rules of variability in time complement the rules of genetics as a biological variability in space. I advocate to replace truisms such as a relative constancy or homeostasis, that have served bioscience very well for very long. They were never intended, however, to lower a curtain of ignorance over everyday physiology. In raising these curtains, we unveil a range of dynamics, resolvable in the data collection and as-one-goes analysis by computers built into smaller and smaller devices, for a continued self-surveillance of the normal and for an individualized detection of the abnormal. The current medical art based on spotchecks interpreted by reference to a time-unqualified normal range can become a science of time series with tests relating to the individual in inferential statistical terms. This is already doable for the case of blood pressure, but eventually should become possible for many other variables interpreted today only based on the quicksand of clinical trials on groups. These ignore individual differences and hence the individual's needs. Chronomics (mapping time structures) with the major aim of quantifying normalcy by dynamic reference values for detecting earliest risk elevation, also yields the dividend of allowing molecular biology to focus on the normal as well as on the grossly abnormal.     

Retention of Rice dwarf virus by Descendants of Pairs of Viruliferous Vector Insects After Rearing for 6 Years

ABSTRACT Rice dwarf virus (RDV) is characterized by its unusual ability to multiply in both plants and leafhopper vector insects and by its transovarial mode of transmission. Colonies of Nephotettix cincticeps, derived originally from pairs of leafhoppers infected with an ordinary strain of RDV, were maintained for 6 years in the laboratory and were found, at the end of this time, still to harbor RDV. Moreover, the isolate of RDV, designated RDV-I, obtained from these colonies retained the ability to infect rice plants. When we raised leafhoppers separately from eggs that had been placed individually on pieces of water-soaked filter paper and reared them in the presence of healthy rice seedlings, we found that all of these leafhoppers harbored RDV. This observation suggested that RDV-I had been maintained in the leafhoppers by transovarial transmission. Two further observations, namely, the low rate of acquisition of RDV by virus-free insect nymphs on symptomless plants on which viruliferous insects had been reared, and the fact that only 2 to 5% of plants had symptoms when rice seedlings were inoculated via RDV-I-viruliferous insects, confirmed that the maintenance of RDV-I by any other mode of transmission through plants and insects was unlikely. This efficient and long-term maintenance of RDV in a population of viruliferous insects might explain the prolonged duration of rice dwarf disease in the field, once there has been a serious outbreak.     

Citrus breeding,genetics and genomics in Japan

Citrus is one of the most cultivated fruits in the world, and satsuma mandarin (Citrus unshiu Marc.) is a major cultivated citrus in Japan. Many excellent cultivars derived from satsuma mandarin have been released through the improvement of mandarins using a conventional breeding method. The citrus breeding program is a lengthy process owing to the long juvenility, and it is predicted that marker-assisted selection (MAS) will overcome the obstacle and improve the efficiency of conventional breeding methods. To promote citrus molecular breeding in Japan, a genetic mapping was initiated in 1987, and the experimental tools and resources necessary for citrus functional genomics have been developed in relation to the physiological analysis of satsuma mandarin. In this paper, we review the progress of citrus breeding and genome researches in Japan and report the studies on genetic mapping, expression sequence tag cataloguing, and molecular characterization of breeding characteristics, mainly in terms of the metabolism of bio-functional substances as well as factors relating to, for example, fruit quality, disease resistance, polyembryony, and flowering.     

A novel postharvest UV-C treatment to reduce chilling injury (membrane damage,browning and chlorophyll degradation) in banana peel

To investigate the mode of action of UV-C to alleviate CI in banana. Banana [Musa (AAA group), Cavendish subgroup cv. Cavendish] fruits were treated with UV-C at dosages of 0.03 kJ m⁻² prior to storage at 8 or 25 °C. UV-C treatment reduced both the incidence and severity of banana fruits stored under low temperature. UV-C treatment reduced membrane damage indicated by lower activity of lipoxygenase (LOX) and malondialdehyde (MDA) content. In additions, the in vitro polyphenol oxidase (PPO) activity was activated when fruits were stored at CI temperature and UV-C treatment could inhibit the PPO activity. UV-C treatment also delayed yellowing and chlorophyll (Chl) degradation due to the inhibition of chlorophyllase and chl-degrading peroxidase activities. Furthermore, the reduction of ethylene production and respiration rate by UV-C treatment results in extended postharvest shelf life of banana. These finding suggest that the loss of cellular compartments in consequence of membrane degradation, combined with the increase of PPO activity, might contribute to the development of CI in banana peel. UV-C treatment may play an important role in maintained membrane integrity and inhibited PPO activity, reducing the severity of CI symptom and delayed ripening in banana. This novel technique may offer an advance in postharvest handling of bananas and other chilling-sensitive commodities in order to reduce postharvest losses resulting from CI.     

Estimation of fault strength: reconstruction of stress before the 1995 Kobe earthquake

We have estimated the stress field before the 1995 Kobe, Japan, earthquake (moment magnitude 6.9) using in situ post-shock stress measurements obtained from hydraulic fracturing experiments near the fault. We reconstructed the pre-shock stress field using a kinematic source model inverted from seismic waveforms and geodetic deformations. We found that at the center of the fault, two sides of the fault surface coupled completely before the earthquake, with a coefficient of friction of 0.6, which is equivalent to strong crust. At the edge of the fault, a possible aseismic slip is expected to occur from the pre-shock stress orientation.     

Possible Role of ZPAC,Zygote-specific Proteasome Assembly Chaperone,During Spermatogenesis in the Mouse

In the mammalian testis, the ubiquitin-proteasome system plays important roles in the process that promotes the formation of mature sperm. We recently identified zygote-specific proteasome assembly phaperone (ZPAC), which is specifically expressed in the mouse gonads and zygote. ZPAC mediates a unique proteasome assembly pathway in the zygote, but the expression profile and function of ZPAC in the testis is not fully understood. In this study, we investigated the possible role of ZPAC during mouse spermatogenesis. First, we analyzed the expression of ZPAC and 20S proteasome subunit α4/PSMA7 in the adult mouse testis. ZPAC and α4 were expressed in spermatogonia, spermatocytes, and round spermatids. In elongating spermatids, ZPAC was expressed until step 10, whereas expression of α4 persisted until step 12. We then examined the expression profile of ZPAC and α4 in a mouse model of experimental unilateral cryptorchidism. Consistent with appearance of morphologically impaired germ cells following cryptorchidism, the ZPAC protein level was significantly decreased at 4 days post induction of experimental cryptorchidism (D4) compared with the intact testis, although the amount of α4 protein persisted at least until D10. Moreover, intense ZPAC staining was co-localized with staining of annexin V, an early indicator of apoptosis in mammalian cells, in germ cells of cryptorchid testis, but ZPAC was also expressed in germ cells showing no detectable expression of annexin V. These results suggest that ZPAC plays a role during spermatogenesis and raises the possibility that 20S proteasome mediated by ZPAC may be involved in the regulation of germ cell survival during spermatogenesis.     

The Colletotrichum higginsianum secreted effector protein ChEC91 induces plant cell death

ChEC91, a novel cell death-inducing effector protein from the fungal pathogen Colletotrichum higginsianum, causal agent of crucifer anthracnose disease, is described. Both transient expression of ChEC91 and infiltration of purified recombinant protein induced necrotic lesions in Nicotiana benthamiana leaves. The recombinant protein also induced electrolyte leakage and callose deposition in Arabidopsis thaliana leaf tissue and the expression of defence marker genes. Moreover, fungal mutants constitutively over-expressing ChEC91 in C. higginsianum were impaired in appressorial penetration on Brassica rapa cotyledons. These results suggest that inappropriate expression of ChEC91 might negatively affect the early stage of C. higginsianum infection by inducing plant defence responses. Protein domain deletion analysis showed that the C-terminal region of ChEC91 was necessary, but not sufficient, for activity in N. benthamiana. Homologous effector proteins cloned from C. gloeosporioides, Fusarium graminearum, and Pyricularia oryzae differed in their cell death-inducing activity, which appeared related to sequence variations in the C-terminal region of these proteins. Moreover, this region contained amino acid residues that were well conserved within Colletotrichum species. These results suggest that the amino acid residues in the C-terminal region may be important for inducing cell death in plants.

     

Microscopic processes of shearing fracture of old wood, examined using the acoustic emission technique

We examined the process of microscopic fracturing peculiar to old wood, based on the generation characteristics of acoustic emission (AE) events and fracture surface analysis. The shearing tests of old wood obtained from construction-derived lumber and new wood within 3 years after lumbering were performed in accordance with the Japanese Industrial Standards (JIS Z 2101-1994). The species of wood used in this study was Japanese red pine. The old wood had been used as a beam in a building for 270 years. The number of the occurrences of AEs at low load levels was larger in the old wood than in the new wood. As a result of analyzing the AE amplitude distributions, we found that the period in which AEs with small amplitudes were frequently generated was longer in the old wood than in the new wood. Also, the fracture surfaces after the final rupture under scanning electron microscope showed more uneven and complicated surfaces in the old wood. Based on the above findings, we presume that during the shearing test the old wood underwent a relatively long and stable progress of microcracking before the final fracture.     

Effects of helical angle of router bit on acoustic emission

The purpose of this study was to investigate the effects of changes in the helical angle of the router bit on the acoustic emission (AE) signal for various workpiece grain angles. The helical angle varied from 0° to 50° at 10° increments. The workpiece grains were oriented from 0 degrees (cutting parallel to the grain), through 90° (cutting end of the grain), to 165° at 15° increments. The AE signals and machined surface roughness were measured in an attempt to clarify the relations between them. The results were summarized as follows: (1) The AE signals were lowest in the with the grain cutting zones and slightly increased in the against the grain cutting zones; they rapidly reached the highest values at the 135°–165° grain angles. The greater the helical angle of the router bit, the smaller were the AE count rates for each grain angle investigated. There was no significant change in AE generation for helical angles of 0° and 10°. Moreover, the greater the feed rate, the greater was the AE count rate for every cutting condition investigated. (2) The surface roughness, similar to the AE count rate, had the lowest values in the with the grain cutting zones, slightly increased until the 120° grain angle, and then rapidly become extremely rough, reaching a maximum at the grain angles of 135°–150°. There was no remarkable change in the machined surface roughness while routing with the grain using the router bit of greater helical angle. However, when routing against the grain, the greater the helical angle the smoother was the machined surface. (3) There were correlations between the AE count rate and the machined surface roughness for each helical angle investigated. Therefore, acoustic emission has shown promise for monitoring and controlling the routing operation, including various grain angles and helical angles of the router bit.     

Effects of substituted D genome chromosomes on photosynthetic rate of durum wheat (Triticum turgidum L. var. durum)

Summary A durum wheat cultivar Langdon (LDN) and fourteen disomic D genome chromosome substitution lines of Langdon, where A or B genome chromosomes were replaced with homoeologous D genome chromosomes of Chinese Spring (CS), were used to assess the compensatory effect of the D genome chromosomes on photosynthetic rates at tetraploid level. The LDN 1D(1B) and LDN 3D(3B) lines showed significantly higher photosynthetic rates than Langdon, whereas LDN 1D(1A) and LDN 3D(3A) lines were not greatly different from Langdon. It appears that chromosomes 1B and 3B decrease photosynthesis. This suggests the differentiation of the effects on the photosynthesis within the first and third homoeologous groups. Substitution with the 2D chromosomes did not compensate the effects of either 2A or 2B chromosomes as it reduced photosynthetic rate compared to plant with either chromosomes 2A or 2B. Tetra CS had a higher photosynthetic rate than CS and Penta CS. The photosynthetic rate of CS was similar to that of Penta CS, which lacked one set of D genome. The results suggest that it may be possible to increase photosynthesis, if both sets of the D genome were entirely removed from hexaploid wheat. However, it is difficult to conclude that the lower rate of photosynthesis of the hexaploids was mainly attributable to D genome chromosome effects, because we did not find a dose dependent effect of D genome. Homoeologous differentiation of chromosomes may be involved in photosynthesis.