Effects of Organic Solvents on the Coupling Between ATP Hydrolysis and Sliding of Microtubules in Axonemes from Chlamydomonas Flagella

ABSTRACT. The effects of organic solvents on the ATPase activity and the sliding disintegration of axonemes from Chlamydomonas were investigated. The axonemal ATPase was markedly activated by methanol accompanying with marked inhibition of the sliding disintegration of axonemes. On the contrary, glycerol inhibited the ATPase activity without serious inhibition of the sliding disintegration. As far as the axonemes are not irreversibly denatured by extremely high concentration of solvents, the effects of solvents both on the ATPase and the ability of sliding are reversible. Therefore, the inhibition of sliding accompanied by the activation of ATPase is probably due to an inability to couple the hydrolysis of ATP to sliding between dynein and microtubule in the presence of methanol. The axonemal ATPase was less sensitive to vanadate inhibition after exposure to methanol. This indicates that methanol makes the dyneinADP.Pi complex unstable and increases product release. On the other hand, glycerol and ethylene glycol seem to stabilize the force generation responsible for the sliding through stabilizing the dynein.ADP.Pi complex.     

Antimelanoma Activity of Chloroquine,an Antimalarial Agent With High Affinity for Melanin

The antimalarial agent chloroquine is known for high affinity for melanin. This 4-aminoquinoline derivative was examined for anti-melanoma activity and uptake into melanoma cells. Chloroquine inhibited growth of cultured melanoma cells; the effect was much greater to a moderately pigmented cell line HMV-II than to a nonpigmented HMV-I. Treatment with chloroquine at a dose of 62 mg/kg i.p. for 12 days prolonged by 71% the life span of mice bearing B16 melanoma, while 24-day treatment at 31 mg/kg resulted in a 81% increase in life span. HMV-II cells showed a two-fold increase in up-take of chloroquine as compared with HMV-I cells. Chloroquine, 24 hr after administration to mice implanted s.c. with B16 melanoma, was selectively accumulated in the pigmented tissues, melanoma and eyes. Other nonpigmented tissues such as the liver, lung, and kidney showed rapid uptake (within 1 hr) and release. These results suggest that chloroquine is toxic to pigmented melanoma cells, the process being partly mediated by binding to melanin     

PHOTOOXIDATION REACTIONS BY CHLOROPLASTS SOLUBILIZED WITH SURFACE-ACTIVE AGENTS

1. Solubilization of chioroplasts with a mixture of 1 per centDuponol C and 1 per cent Span 80 (3: 1) caused a destructionof activity in the HILL reaction, but the treatment broughtabout an increase by about 60 per cent in the rate of ascorbatephotooxidation in the presence of DPIP. Heating the broken chloroplastscaused a marked decrease in the photooxidation activity. Byadding surface- active agents to the boiled preparation, theactivity was restored up to almost 80 per cent of the originallevel.
2. With colloidal suspensions of isolated chiorophylls,ascorbatewas only slightly photooxidized in the presence ofDPIP. Byaddi tion of the surface-active agents, the activitywas greatlyenhanced.
3. Dependency of the photooxidation bywhole and solubilized chloroplastsand isolated chlorophylla on the presence of DPIP was examined.DPIP can serve as anintermediate electron carrier in solubilizedchloroplasts aswell as in whole chloroplasts.
4. Effect of o-phenanthrolineon ascorbate photooxidation by thesethree preparations wastested. With solubilized chloroplastsand isolated chlorophylls,the addition of the inhibitor hadno influence on their ascorbatephotooxidation either in thepresence or absence of DPIP.
5. Treatmentof whole chloroplasts with the surface-active agentsinducedan activity of photooxidation of cytochrome c. The electron-flowpattern for the photooxidation of ascorbate by whole and solubilizedchloroplasts was briefly discussed.

¹ Contribution No. 130 from the Department of Biology, Facultyof Science, Kyushu University. Aided in part by Grant-in-Aidfor Fundamental Scientific Research from the Ministry of Education. (Received August 23, 1962; )     

Inducible Formation of Glutamate Dehydrogenase in Rice Plant Roots by the Addition of Ammonia to the Media

The activity of glutamate dehydrogenase (l-glutamate: NAD oxidoreductase, EC 1.4.1.2.; GDH) of rice plants changes in response to the nitrogen source supplied to the culture solution. The activity of NADH-GDH(aminating) in roots is rapidly increased by the addition of ammonia, whereas the activity in shoots is much less affected by nitrogen supply. The activity increased with increasing concentration of ammonia at least up to 14.3 mM. In roots GDH activity was found in both the mitochondrial and soluble fractions. The increase of NADH-GDH activity caused by the ammonia treatment occurs mainly in the latter fraction. The new band with GDH activity was detected on the zymogram of polyacrylamide gel electrophoresis and this inducible enzyme is active with both NAD and NADP. On the other hand, the constitutive enzyme activity active with NAD is also increased by the ammonia treatment. The increase of enzyme activity is prevented by the addition of cycloheximide or chloramphenicol to culture medium. The incorporation of ¹⁴C-leucine(U) into GDH proteins was also studied using polyacrylamide gel electrophoresis. Higher radioactivity was found in induced samples than in non-induced ones. These results show that the increase of GDH activity in roots by ammonia treatment seems to depend on de novo protein synthesis.     

Morphological variation in relation to flower use in bumblebees

To understand resource partitioning in a bumblebee community, we analyzed various morphological characters. A total of 1269 individuals of six bumblebee species, Bombus ardens, B. hypocrita, B. diversus, B. ignitus, B. honshuensis and B. beaticola, were examined and principal component analysis showed that the bumblebee species were clearly differentiated. Glossa, prementa and head lengths were positively correlated with the second component, and a longer proboscis was associated with a narrower body, which may help bees to intrude into and access deep‐lying nectar sources. Bombus diversus, with a long proboscis and narrow body, preferred flowers with a long corolla tube, whereas B. hypocrita and B. ignitus, which have short proboscises and wide bodies, visited flowers with short corollas or dish‐shaped flowers. Two pairs of consubgeneric species that have similar morphological characteristics, B. ardens and B. beaticola, and B. hypocrita and B. ignitus, divided flower resources by habitat selection and seasonal partitioning. For resource partitioning among bumblebee species, not only morphology but also other factors, such as habitat and seasonal preference, flower use, foraging behavior, and interspecific interactions, are responsible.     

Effects of channelisation on stream habitat in relation to a spate and flow refugia for macroinvertebrates in northern Japan

1. The effects of channelisation on macroinvertebrates were examined in relation to a spate and flow refugia. Habitat components that can function as flow refugia were identified in a small, low‐gradient stream in northern Hokkaido, Japan. 2. Macroinvertebrates and their habitat characteristics (depth, current velocity and substratum) were sampled and measured in natural and channelised sections on three occasions: before, during and immediately after a spate. For macroinvertebrate sampling and habitat measurements, five (riffle, glide, pool, backwater and inundated habitats) and three (channelised‐mid, channelised‐edge and inundated habitats) habitat types were classified in the natural and channelised section, respectively. 3. The rate of velocity increase with discharge was compared among habitat types to determine which habitat types were less affected by increased discharge. The rate was the highest in riffles followed by glides and channelised‐mids. Backwaters maintained low current velocity even at high flow. In addition, current velocity in both natural and channelised inundated habitats was low relative to other habitat types during the spate. 4. Through the spate, total density of macroinvertebrates in channelised‐mids and taxon richness in both channelised‐mids and edges decreased. In the natural section, however, such a significant decrease was not found except for taxon richness in pools. This indicated that the spate had a greater impact on assemblages in the channelised section. Riffle assemblages exhibited a rapid recovery immediately after the spate, suggesting the existence of flow refugia in the natural section. Among the habitat types we examined, backwaters and inundated habitats appeared to have acted as flow refugia, because these habitats accumulated macroinvertebrates during the spate. 5. The lower persistence of the macroinvertebrate assemblage in the channelised section was attributable to the lower availability of flow refugia such as backwaters and inundated habitats. Our results emphasised the importance of considering flow fluctuations and refugia in assessing the effects of channelisation. In addition, the lateral heterogeneity of stream channels should be considered in stream restoration and management.     

Descriptions of two new and one little known species of the genus Cacopsylla (Hemiptera: Psyllidae) on Sorbus japonica (Rosaceae) and an observation of their biology

Three species of the genus Cacopsylla were collected from Sorbus japonica in Japan. Two of them, Cacopsylla elegans and Cacopsylla sorbicoccinea, are described as new species based on adults and fifth (final) nymphal instars. The third species, Cacopsylla midoriae, is newly transferred from the genus Psylla. The adult of C. midoriae is redescribed and the nymph is described for the first time. A key to the species feeding on S. japonica (adults and nymphs) is provided. The three species were observed to coexist on the same tree of S. japonica in northern Kyushu. Such coexistence of psylloid congeners is uncommon in Japan.     

Amphibian chytridiomycosis in Japan: distribution,haplotypes and possible route of entry into Japan

A serious disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis was first found in Japan in December 2006 in imported pet frogs. This was the first report of chytridiomycosis in Asia. To assess the risk of pandemic chytridiomycosis to Japanese frogs, we surveyed the distribution of the fungus among captive and wild frog populations. We established a nested PCR assay that uses two pairs of PCR primers to amplify the internal transcribed spacer (ITS) region of a ribosomal RNA cassette to detect mild fungal infections from as little as 0.001 pg (1 fg) of B. dendrobatidis DNA. We collected swab samples from 265 amphibians sold at pet shops, 294 bred at institutes and 2103 collected at field sites from northern to southwestern Japan. We detected infections in native and exotic species, both in captivity and in the field. Sequencing of PCR products revealed 26 haplotypes of the B. dendrobatidis ITS region. Phylogenetic analysis showed that three of these haplotypes were specific to the Japanese giant salamander (Andrias japonicus) and appeared to have established a commensal relationship with this native amphibian. Many other haplotypes were carried by alien amphibians. The highest genetic diversity of B. dendrobatidis was found in the American bullfrog (Rana catesbeiana). Some strains of B. dendrobatidis appeared to be endemic to Japanese native amphibians, but many alien strains are being introduced into Japan via imported amphibians. To improve chytridiomycosis risk management, we must consider the risk of B. dendrobatidis changing hosts as a result of anthropogenic disturbance of the host‐specific distribution of the fungus.     

A New Method for Inoculation of Poor Germinator, Nosema sp. NIS M11 (Microsporida: Nosematidae), into an Insect Cell Culture

ABSTRACT. Spores of Nosema sp. NIS M11, primed with 0.1 N KOH solution, were mixed with either physiological salt solutions or IPL-41 medium, an insect cell culture medium, for germination. In the latter medium, only a few spores germinated, while high percentages of spore germination were obtained in physiological salt solutions, particularly in Rinaldini's solution. By using the salt solutions as inoculation media, KOH-primed NIS M11 spores were inoculated into the Spodoptera frugiperda SF21AEII cell line. The initial infection levels were consistently higher than that obtained by using IPL-41 medium. Among the salt solutions, Rinaldini's solution, containing KCl in place of NaCl, gave the highest percentage of initial cell infection. Increased osmolarity of salt solutions did not improve the efficiency of spore germination and infection of N. sp. NIS M11.