Y-27632 inhibits gastric motility in conscious rats

Y-27632, a highly selective inhibitor of p160ROCK, desensitizes the smooth muscle to Ca2+ and inhibits smooth muscle contraction. While this drug has the potential to become a novel drug for hypertension, it might also affect other smooth muscle, including that of gastrointestinal tract. We studied the effects of Y-27632 on gastric contractions in conscious rats. Strain gauge force transducers were sutured onto the serosal side of the gastric antrum and contractions were recorded before and after the intravenous injection of Y-27632. Doses of 1.0 mg/kg to 10 mg/kg significantly decreased contraction amplitude and the motility index in a dose dependent manner. With 10 mg/kg, the mean amplitude was decreased by up to 69 +/- 14% and the motility index by up to 81 +/- 7%. The change occurred immediately after drug infusion and lasted for 3.5h. Contraction frequency showed only a slight decrease. No signs of bowel obstruction were observed. These results indicate that Rho-mediated Ca sensitization has a role in the physiologic contractions of gastric smooth muscle in rats. Y-27632 is useful to investigate the physiology of gastrointestinal motility.     

Induced Response of Tomato Plants to Injury by Green and Red Strains of Tetranychus Urticae

We studied the induced response of tomato plants to the green strain and the red strain of the spider mite Tetranychus urticae. We focused on the olfactory response of the predatory mite Phytoseiulus persimilis to volatiles from T. urticae-infested tomato leaves in a Y-tube olfactometer. Tomato leaves attracted the predatory mites when slightly infested with the red strain, or moderately or heavily infested with the green strain. In contrast, neither leaves that were slightly infested with green-strain mites, nor leaves that were moderately or heavily infested with the red strain attracted the predators. We discuss the specific defensive responses of tomato plants to each of the two strains.     

Trend of adenovirus type 7 infection, an emerging disease in Japan. A report of the National Epidemiological Surveillance of Infectious Agents in Japan

The program of the National Epidemiological Surveillance of Infectious Diseases under the auspices of the Ministry of Health and Welfare started in 1981 apprehended in 1995 emergence of adenovirus type 7 in Japan. We analyzed the reported data of type 7 comparing with those of type 3, both belonging to the same subgenus B, and the following results were obtained: After 1981, the main serotypes in the reports of adenovirus isolation/detection were types 3, 2, and 1 in this order. The reports of isolation of adenovirus type 7 used to be extremely few, however, suddenly increased in 1995. In 1997, reports of isolation of adenovirus type 3 decreased and those of type 7 acquired the third place after those of types 2 and 3. Type 7 infection occur almost every month, but most frequently during May-September. The ages of cases from which type 7 was isolated were 0-4 years accounting for 55%, 5-9 years 35%, teens 6.3% and adults 4.0%, being similar proportions to those yielding type 3. Clinical diagnoses of cases yielding adenovirus type 7 were pharyngo-conjunctival fever (PCF) and influenza-like illness, these two accounting for half. The symptoms were severe, being characterized by higher maximum body temperature during the feverish period and severe pneumonia. Encephalitis and arthro-muscular pain were seen in only type 7-infected cases, although such cases were few.     

Presence of the Photoactive Reaction-Center Chlorophyll of PSI (P700) in Dark-Grown Cells of a Chlorophyll-Deficient Mutant of Chlorella kessleri

Compositions of pigments and polypeptides of pale green membranesthat had been isolated from dark-grown cells of a chlorophyll-deficientmutant of Chlorella kessleri were investigated. They containedChl a in a level corresponding to about 1% of that present inthe thylakoid membranes isolated from autotrophically grownwild-type cells and a trace amount of chlorophyllide a, butneither Chl b nor carotenoids. The polypeptide profile of themutant membranes was similar to that of membranes isolated fromwild-type cells that were grown in the dark. Neither the chlorophyll-bindingsubunits of PSI nor the apoproteins of LHCP were detected bySDS-PAGE and immunoblot analysis. However, the light-minus-darkdifference spectrum of the mutant membranes revealed the presenceof the reaction-center chlorophyll of PSI (P700) at a molarratio of 190 chlorophyll (Chl a plus Chlide a) per P700. P700was more stable than Chl a and Chlide a in the light so thatprolonged illumination led to a decline in the Chl/P700 ratioto 24. The initial rate of P700 photooxidation in the mutantmembranes was comparable to that in CP1 isolated from the dark-grownwild-type cells. Under illumination with strong light, the initialrate was decreased in parallel to the decrease in Chl/P700 ratio.The results suggest that most of Chi present in the mutant membranescan transfer excitation energy to P700. (Received March 13, 1998; Accepted August 7, 1998)     

CENTRORADIALIS/TERMINAL FLOWER 1 gene homolog is conserved inN. tabacum, a determinate inflorescence plant

A mutation in theCENTRORADIALIS (CEN) gene ofAntirrhinum and in theTERMINAL FLOWER 1 (TFL1) gene ofArabidopsis causes their indeterminate inflorescence to determinate. We clonedCEN/TFL1 homologs fromNicotiana tabacum, the wild-type of which has a determinate inflorescence. TheCEN gene was expressed in the inflorescnece meristem and kept its inflorescence meristem identity, whereas the tobacco homolog (NCH) was expressed at a low level throughout the plant’s development. AlthoughCEN andNCH are highly homologous genes, they may have been recruited to different developmental functions during their evolution. TwoNCH genes are derived from amphidiploidN. tabacum, but both of them hybridized with its diploid parents,N. sylvestris andN. tomentosiformis. Southern blotting, and the genomic organization ofTFL1 inArabidopsis revealed that anotherCEN homolog exists in the genome ofArabidopsis. These results suggest that there are two copies of theCEN homolog per diploid plant. The extended abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International Prize for Biology “Frontier of Plant Biology” These two authors contributed to this work equally.     

Polypeptide binding of Escherichia coli FtsH (HflB)

The Escherichia coli FtsH protein is a membrane-bound and ATP-dependent protease. In this study, we describe ATP-dependent conformational changes in FtsH as well as a polypeptide binding ability of this protein. A 33 kDa segment of FtsH became trypsin resistant in the presence of ATP. ATP and ATPγS prevented self-aggregation of detergent-solubilized FtsH-His₆-Myc at 37°C, again suggesting that the binding of ATP induces a conformational change in FtsH. Affinity chromatography showed that FtsH-His₆-Myc can associate with denatured alkaline phosphatase (PhoA) but not with the native enzyme. Denatured PhoA also prevented the aggregation of FtsH, and these two proteins co-sedimented through a sucrose gradient. Binding between FtsH-His₆-Myc and detergent-solubilized SecY was also demonstrated. Although FtsH-bound SecY was processed further for ATP-dependent proteolysis, FtsH-bound PhoA was not. Thus, FtsH association with denatured PhoA is uncoupled from proteolysis. Overproduction of FtsH significantly increased the cytoplasmic localization of the PhoA moiety of a MalF–PhoA hybrid protein, in which a charged residue had been introduced into a transmembrane segment. Thus, denatured PhoA binding of FtsH may also occur in vivo .     

Lipase-induced hydrolysis of castor oil: effect of various metals

The ability of an extracellular lipase from Pseudomonas aeruginosa KKA-5 to commence hydrolysis of castor oil in the presence of various metal chlorides, was investigated. Apart from CaCl₂ (commonly used for castor oil hydrolysis), AlCl₃ (group IIIB), CrCl₃ (group VIA) and MgCl₂ (group IIA) displayed enhanced hydrolysis capability. Specifically, our statistics show that with respect to time, when Cr³⁺ was used, hydrolysis of castor oil was four times faster than that of calcium, and 1.6 times faster with regards to Al³⁺. The chlorides of group VIII and alkali metals had no effect on hydrolysis. Group IV metal chlorides did not enhance lipase activity and inhibited castor oil hydrolysis. The effect of metal ions from other groups on lipase activity is also reported. Received 14 August 1998/ Accepted in revised form 22 October 1998     

Mitochondrial DNA Variation Follows a Geographic Pattern in Japanese Beech Species

The amount and distribution of mitochondrial (mt) DNA restriction fragment length polymorphism was determined among individual tree samples of two Japanese beech species, Fagus crenata and F.japonica. Individual plants were collected from 16 F. crenata populations throughout the range of the species, and from three F. japonica populations. We detected enough variation to characterize eleven and three chondriome types in F. crenata and F.japonica, respectively. The grouping of beech chondriome types based upon the cladistic analysis of mtDNA polymorphism allowed us to recognize the apparent geographical patterns of mtDIMA diversity: the resulting three main groups occupied distinct geographic areas. This geographic differentiation is likely to reflect the history of the Japanese beech forests after the last glacial period of the Pleistocene. In addition, the mtDNA polymorphism encountered within F. crenata encompassed all the variation observed in F.japonica. Our result suggests the need for re-evaluation of their phylogenetic relationships.     

Phosphoinositide-specific phospholipase C forms a complex with 14-3-3 proteins and is involved in expression of UV resistance in fission yeast

The fission yeast plc1 ⁺ gene encodes phosphoinositide-specific phospholipase C. The two- hybrid interaction assay with plexA-plc1 ⁺ as a bait revealed that Plc1p interacted with the 14-3-3 proteins Rad24p and Rad25p. Formation of a complex containing Plc1p and Rad24p in vivo was confirmed by an immunological method. As predicted from the fact that rad24 null mutant cells are hypersensitive to UV irradiation, plc1 null mutant cells were almost as sensitive to UV irradiation as rad24 null mutant cells. In addition, deletion of rad24 in the plc1 null mutant cells did not enhance the UV sensitivity, indicating that plc1 ⁺ and rad24 ⁺ belong to the same epistasis group with respect to UV sensitivity. Whereas Rad24p has been reported to be involved in the DNA damage checkpoint pathway, the delay to mitosis after UV irradiation was not defective either in rad24 null mutant cells or in plc1 null mutant cells in our analysis. Thus, Plc1p is responsible for resistance to UV irradiation, but not for the DNA damage checkpoint pathway, in cooperation with 14-3-3 proteins.