Zyxin, a regulator of actin filament assembly, targets the mitotic apparatus by interacting with h-warts/LATS1 tumor suppressor.

The mitotic apparatus plays a pivotal role in dividing cells to ensure each daughter cell receives a full set of chromosomes and complement of cytoplasm during mitosis. A human homologue of the Drosophila warts tumor suppressor, h-warts/LATS1, is an evolutionarily conserved serine/threonine kinase and a dynamic component of the mitotic apparatus. We have identified an interaction of h-warts/LATS1 with zyxin, a regulator of actin filament assembly. Zyxin is a component of focal adhesion, however, during mitosis a fraction of cytoplasmic-dispersed zyxin becomes associated with h-warts/LATS1 on the mitotic apparatus. We found that zyxin is phosphorylated specifically during mitosis, most likely by Cdc2 kinase, and that the phosphorylation regulates association with h-warts/LATS1. Furthermore, microinjection of truncated h-warts/LATS1 protein, including the zyxin-binding portion, interfered with localization of zyxin to mitotic apparatus, and the duration of mitosis of these injected cells was significantly longer than that of control cells. These findings suggest that h-warts/LATS1 and zyxin play a crucial role in controlling mitosis progression by forming a regulatory complex on mitotic apparatus.

A human homolog of Drosophila warts tumor suppressor, h-warts, localized to mitotic apparatus and specifically phosphorylated during mitosis.

We identified a human homolog of Drosophila warts tumor suppressor gene, termed h-warts, which was mapped at chromosome 6q24-25.1. The h-warts protein has a serine/threonine kinase domain and is localized to centrosomes in interphase cells. However, it becomes localized to the mitotic apparatus, including spindle pole bodies, mitotic spindle, and midbody, in a highly dynamic manner during mitosis. Furthermore, h-warts is specifically phosphorylated in cells at mitotic phase, most likely by Cdc2 kinase. These findings suggest that h-warts functions as a component of the mitotic apparatus and is involved in proper progression of mitosis.

Comparison of bacterial community structures in the rhizoplane of tomato plants grown in soils suppressive and conducive towards bacterial wilt.

It has been reported that the growth of Ralstonia solanacearum is suppressed at the rhizoplane of tomato plants and that tomato bacterial wilt is suppressed in plants grown in a soil (Mutsumi) in Japan. To evaluate the biological factors contributing to the suppressiveness of the soil in three treated Mutsumi soils (chloroform fumigated soil; autoclaved soil mixed with intact Mutsumi soil; and autoclaved soil mixed with intact, wilt-conducive Yamadai soil) infested with R. solanacearum, we bioassayed soil samples for tomato bacterial wilt. Chloroform fumigation increased the extent of wilt disease. More of the tomato plant samples wilted when mixed with Yamadai soil than when mixed with Mutsumi soil. Consequently, the results indicate that the naturally existing population of microorganisms in Mutsumi soil was significantly able to reduce the severity of bacterial wilt of tomato plants. To characterize the types of bacteria present at the rhizoplane, we isolated rhizoplane bacteria and classified them into 22 groups by comparing their 16S restriction fragment length polymorphism patterns. In Yamadai soil a single group of bacteria was extremely predominant (73.1%), whereas in Mutsumi soil the distribution of the bacterial groups was much more even. The 16S rDNA sequence analysis of strains of dominant groups suggested that gram-negative bacteria close to the beta-proteobacteria were most common at the rhizoplane of the tomato plants. During in vitro assays, rhizoplane bacteria in Mutsumi soil grew more vigorously on pectin, one of the main root exudates of tomato, compared with those in Yamadai soil. Our results imply that it is difficult for the pathogen to dominate in a diversified rhizobacterial community that thrives on pectin.

[Correlation analysis between visual acuity and sitting postural parameters of young students].

The relationship between failing eyesight and the sitting posture of young students while studying was studied quantitatively. Among the 19 students who participated in this study, 9 were classified as emmetropic and 10 were myopic. The mean age was 13.2 +/- 2.2 (mean +/- standard deviation) years. Viewing distance, neck angle, viewing angle, vertical gaze direction, and ocular surface area while studying were measured from the lateral and frontal view images of video recordings of the posture. Viewing distance, accommodative power, neck angle, viewing angle, near point, and log transformed visual acuity showed significant differences between these two groups (p < 0.001). Viewing distance of myopes (15.0 +/- 1.9 cm) (mean +/- standard desviation) is shorter than that of emmetropes (30.2 +/- 4.1 cm). Accommodative power of myopes was lower than that of emmetropes. Correlation analysis revealed that the viewing distance of students significantly correlates to neck angle, viewing angle, accommodative power, near point, and visual acuity (p < 0.01). It can be surmised that the failing eyesight of young students results from postural problems such as shortness of viewing distance and increased neck flexion.

Kinetic studies on androstenedione production in ovarian microsomes from immature rats.

Androstenedione formation from progesterone by P-450(17 alpha,lyase) was investigated in ovarian microsomes of immature rats treated with pregnant mare serum gonadotropin. Successive monooxygenase reactions in the formation of androstenedione without the intermediate leaving P-450(17 alpha,lyase) were demonstrated by a double-substrate double-label experiment using [14C]progesterone and 17 alpha-[3H]hydroxyprogesterone as substrates and also by specific reduction in the concentration of intermediate 17 alpha-hydroxyprogesterone in the reaction medium by reaction of liposomal P-450C21. A detailed kinetic study on the reactions of P-450(17 alpha,lyase) in microsomes was conducted in the steady state. Kinetic parameters indicated the C17,C20-lyase reaction for 17 alpha-hydroxyprogesterone (Km = 80 nM) to be strongly inhibited by progesterone (Ki = 8 nM). In the presence of a high concentration of progesterone, as in the case of in vivo rat ovary, most androstenedione is concluded to be formed directly from progesterone by successive monooxygenase reactions catalyzed by P-450(17 alpha,lyase). 20 alpha-Dihydroprogesterone competitively inhibited the C17,C20-lyase reaction for 17 alpha-hydroxyprogesterone with Ki = 23 nM, but had only slight effect on progesterone metabolism to androstenedione. 20 alpha-Dihydroprogesterone, thus, cannot be a regulator for androstenedione formation in rat ovary.

[The influence of aging and different type of targets on eye accommodation].

The influence of aging and a couple of external and internal targets on eye accommodation under monocular vision using an infrared optometer were studied. The subjects were 11 healthy adults aged 20-40. In comparison with using internal targets, the amount of accommodative response, tension velocity for accommodation and relaxation velocity for accommodation showed a tendency to increase when using an external target. In particular, these tendencies showed a predominantly in middle-aged subjects. It is suggested that external targets gives some more precise information concerning eye accommodation. In using internal targets, instrument myopia and psycho-physiological factors might bring about a disturbance of reproducibility during eye accommodation.