Electron microscopic demonstration of a common structural motif in human complement factor C3 and rat α1 -inhibitor 3 (murinoglobulin)

Electron microscopy of two homologous giant proteins revealed that complement factor C3 and α_i-inhibitor 3 have a common structural motif of a semicircularly bent string 18–20 nm long with two or three bumps indicating globular domains. C3 had a structure similar to the letter C with a small but distinct hole in the center. α₁-Inhibitor 3 was a more complete ring sometimes ajar at one corner. When the latter was treated with a proteinase, it became slightly flattened and adopted a squarish C-shape.     

Cooperation in a deep helical energy well

In contrast to random coil polymers, polyisocyanates maintain a highly extended helical conformation in solution. This structural characteristic causes unusually large chiral optical properties to arise from copolymerization of tiny proportions of optically active monomer isocyanates with achiral isocyanates or even from stereospecific placement of deuterium in the side chain of poly(n-hexyl isocyanate). These effects can be understood as phenomenologically related to the optical activity amplification properties of vinyl polymers studied by Pino and his co-workers and ascribed to breaking the energetic degeneracy of the otherwise equally populated left- and right-handed helical states of the backbone. Statistical thermodynamic calculations, based on this model, and analogous to those carried out earlier on the vinyl polymers, allow matching the temperature and molecular weight dependence of the optical activity in poly((R)-1-deuterio-1-hexyl isocyanate) to the approximate responsible energy terms.     

Crown profile of foliage area characterized with the Weibull distribution in a hinoki (Chamaecyparis obtusa) stand

Summary Thirten sample trees of various sizes in a 29-year-old hinoki [Chamaecyparis obtusa (Sieb, et Zucc.) Endl.] plantation were felled and subjected to the stratified clip technique. Crown profile of foliage area fitted well with the Weibull distribution. The crown profile tended to be more skewed toward the top of crowns in smaller trees than in larger trees. This tendency was reflected in the value of the shape parameter of the Weibull distribution. The shape parameter ranged from 1.73 to 3.23 and gradually increased up to an asymptotic value with an increase of stem diameter at breast height. The scale parameter of the distribution ranged from 1.0 to 4.2 and tended to increase in proportion to stem diameter at breast height. Foliage area of a tree correlated well with stem diameter at breast height through an ordinary allometric equation. Tree height could be approximated fairly well by a generalized allometric equation as a function of stem diameter at breast height. On the basis of the census of stem diameter at breast height, canopy profile could be constructed synthesizing crown profiles of foliage area for individual trees in the stand. Leaf area index was estimated to be 6.6 ha ha^–1.     

Changes in the interior surface of newly mesodermalized ectoderm and its contact activity with competent ectoderm in the newtCynops (Amphibia)

Summary The presumptive ectoderm (pE) ofCynops gastrulae was artificially mesodermalized by contact with teleost swimbladder. The newly mesodermalized ectoderm (mE) acquired the capacity for neural induction (Suzuki et al. 1986a). SEM observations revealed that the mE cells altered their cellular profiles immediately after mesodermalization. The characteristics of the cell surface and the cell architecture became similar to those of invaginated mesoderm cells. There were distinct differences in the cellular contact between mE—pE and pE—pE combinations. The mE-pE combinations kept close contact at their interior surfaces, while the pE—pE combinations did not keep contact. Both TEM and SEM observations also indicated that there were tight contacts between mE and pE cells. These findings suggest that neural-inducing activity of the newly mesodermalized ectoderm cells is coupled with acquisition of cellular affinity toward the interior surface of competent ectoderm cells, and probably requires close cell contacts.     

Regulation of polar surface structures in Caulobacter crescentus: Pleiotropic mutations affect the coordinate morphogenesis of flagella, pili and phage receptors

Summary A large number of Caulobacter mutants resistant to DNA or RNA phages were isolated. These phage-resistant mutants exhibited phenotypic variations with respect to cell motility and sensitivity to other phages.The majority of the mutants was resistant to both DNA and RNA phages tested. In addition, these mutants were either motile or non-motile. The analysis of spontaneous revertants from these mutants indicated that a single mutation is involved in these phenotypic variations. Other mutants were resistant to RNA phages and only to a certain DNA phage tested, and were also motile or non-motile.Several temperature-sensitive phage-resistant mutants were also isolated. One of them, CB13 ple-801, exhibited the wild type phenotype when grown at 25°C. However, at a higher temperature (35°C), the mutant cells became non-motile and resistant to both DNA and RNA phages. These phenotypes seem to be attributed to the concommitant loss of flagella, pili and phage receptors. In other respects (cell growth and morphology, and asymmetric stalk formation), CB13 ple-801 was normal at 35°C. The spontaneous revertants from CB13 ple-801 simultaneously regained the wild type phenotypes in all respects.It is suggested that a single mutation pleiotropically affects the formation of flagella, pili and phage receptors.     

Metabolism of S-methylcysteine and pectin esterification in Chinese cabbage, Brassica pekinensis Rupr.

S-Methyl-L-cysteine was actively metabolized in Chinese cabbageand carbon from its methyl group was distributed into both thesoluble and insoluble fractions. The high incorporation of ¹⁴Cfrom the methyl group into the insoluble fraction after administeringof S-methyl-L-cysteine-¹⁴CH₃, and our previous results thatS-methyl-L-cysteine is demethylated to give cysteine, suggestthat S-methyl-L-cysteine might act as a methyl donor in Chinesecabbage. To obtain evidence for this possibility, incorporationof the methyl-¹⁴C of S-methyl-L-cysteine into methyl estersof pectic substances was investigated. Most of the ¹⁴C incorporatedinto pectic substances was liberated by treatment with dilutealkali and pectin esterase. The results show that S-methyl-L-cysteineacts as a methyl donor to form pectin ester. (Received October 12, 1971; )     

The effect of the rate of successful dispersal of a Phytoseiid mite,Phytoseiulus persimilis Athias-Henriot (Acarina: Phytoseiidae) on the persistence in the interactive system between the predator and its prey

Dispersal behaviour was studied on a predacious phytoseiid mite, Phytoseiulus persimilisAthias-Henriot in response to the density of its prey, Tetranychus kanzawaiKishida . And the effect of the change in the rate of successful dispersal of the predators among patches was tested on the persistence of the predator-prey system. The results of the study are summarized as follows:

1. With a severe decline in prey density available per individual predator, the predators exhibited a marked behavioural change and dispersed to other areas.
2. When two neighboring host plants did not touch with each other and the dispersal of the predators was possible only through a 20cm plywood “bridge” which connected the two plants, the rate of successful dispersal of the predators was only 20 to 25%, whereas it was 95% when the plants touched with each other.
3. In the system where 32 host plants touched with each other, the predators succeeded in immigrating into all the plants by the 16th day, and they completely eliminated all the prey by the 33rd day.
4. In another system, the 32 plants were equally divided into eight “patches” which were connected with each other with two of the bridges and the predators could move between them only through the bridges as mentioned above. In such a system the predators and their prey coexisted about three times longer than in the other one.
5. It is suggested that for a longer continued coexistence of the predators and prey, it would be necessary to introduce more physical barrier against the dispersal of the predators and to provide more chances for the prey to disperse.

     

Effects of Light on Growth and Glucose Consumption in Colorless Chlorella Mutant Cells

Light inhibited the growth and glucose consumption of colorlessmutant cells of Chlorella vulgaris (# 125). Sugar consumptionwas also inhibited in a medium containing a hexose such as D-fructose,D-galactose and D-mannose. Blue light strongly inhibited growth and glucose consumptionbut red light only slightly affected them. Respiration was notinhibited by blue light. The inhibitions of growth and glucoseconsumption were saturated at light intensities as low as 800mW.m^–2 and continued in the dark for at least one dayafter brief illumination with white light. The half-maximumeffect was observed with 15 min of illumination in both casesand the action spectra for light-induced inhibitions of growthand glucose consumption were similar, both showing peaks at370, 457 and 640 nm. The role of light in the inhibitions of growth and glucose consumptionis discussed. (Received June 18, 1984; Accepted October 29, 1984)