WATER PERMEABILITY OF THE CELL WALL IN NITELLA

1. A method has been developed to measure the hydraulic conductivityof the wall of the internodal cell of Nitella flexilis.
2. Therate of water penetration through the cell wall varies linearlywith the hydrostatic pressure difference between the two sidesof the wall, showing that water permeability of the cell wallremains independent of the pressure difference applied.
3. Waterpermeability of the cell wall is inversely proportionalto itsthickness It is 30µµmin^–3{dot}atm^–3when the thickness of the wall is 10 µ.
4. Water permeabilityof the cell wall is the same for inward andoutward water flow.The polar water permeability of the entiremembrane system (walland protoplasmic part) of the living celldemonstrated by KAMIYAand TAZAWA (1) is, therefore, due tothe living protoplasmicpart.
5. The ratio of the inward to outward permeability constantsofthe protoplasmic layer alone is higher than that of the entiremembrane system composed of protoplasmic layer and cell wall.

¹ Dedicated to Prof. H. TAMIYA on the occasion of his 60th birthday.The present work was supported in part by a Grant-in-Aid forFundamental Scientific Research from the Ministry of Education. ² Present address: Sh?in Women's College, Kobe. (Received July 21, 1962; )     

Carbon accumulation at depth in Ferralsols under zero‐till subtropical agriculture

Conservation agriculture can provide a low‐cost competitive option to mitigate global warming with reduction or elimination of soil tillage and increase soil organic carbon (SOC). Most studies have evaluated the impact of zero till (ZT) only on surface soil layers (down to 30 cm), and few studies have been performed on the potential for C accumulation in deeper layers (0–100 cm) of tropical and subtropical soils. In order to determine whether the change from conventional tillage (CT) to ZT has induced a net gain in SOC, three long‐term experiments (15–26 years) on free‐draining Ferralsols in the subtropical region of South Brazil were sampled and the SOC stocks to 30 and 100 cm calculated on an equivalent soil mass basis. In rotations containing intercropped or cover‐crop legumes, there were significant accumulations of SOC in ZT soils varying from 5 to 8 Mg ha^?1 in comparison with CT management, equivalent to annual soil C accumulation rates of between 0.04 and 0.88 Mg ha^?1. However, the potential for soil C accumulation was considerably increased (varying from 0.48 to 1.53 Mg ha^?1 yr^?1) when considering the soil profile down to 100 cm depth. On average the estimate of soil C accumulation to 100 cm depth was 59% greater than that for soil C accumulated to 30 cm. These findings suggest that increasing sampling depth from 30 cm (as presently recommended by the IPCC) to 100 cm, may increase substantially the estimates of potential CO₂ mitigation induced by the change from CT to ZT on the free‐draining Ferralsols of the tropics and subtropics. It was evident that that legumes which contributed a net input of biologically fixed N played an important role in promoting soil C accumulation in these soils under ZT, perhaps due to a slow‐release of N from decaying surface residues/roots which favored maize root growth.     

6-Phosphogluconate Dehydrogenase (6PGD) Gene Duplication in Kalimeris (Asteraceae)

Abstract The genus Kalimeris with a diagnostic character of short or inconspicuous pappus consists of two sections, Asteromoea and Cordifolium. As a result of 6PGD isozyme analysis, sect, Asteromoea, including 2 × and poly-ploid taxa from 5 × to 8 ×, show similar cytosolic isozyme multiplicity and share a monomorphic locus. The data suggest that gene duplication of polyploid members was derived from a common ancestor. K. miqueliana, belonging to sect. Cordifolium. also possessed a gene duplication in 6PGD, though significant differences were detected in electrophoretic mobility between the sections. The occurrence of gene duplication in East Asian diploid Astereae leaves intact the validity of the allopolyploid-origin hypothesis of n= 9, which was rejected by Gottlieb (1981a) in American Astereae.     

Failure of Immunological Memory in DMBA-treated Mice

SEVERAL chemical carcinogens show immunosuppressive activity in various experimental systems^1–4. Stjernswärd⁵ reported a remarkable correlation between carcinogenic activity and immunosuppressive capacity of chemicals, that is, potent carcinogens such as 3-methylcholanthrene (MCA), benz(a)pyrene and 7,12-dimethylbenzanthracene (DMBA) suppressed the immune response to sheep red blood cells (SRBC) but noncarcinogenic analogues did not. Stutman² showed that administration of MCA depressed the immune response to SRBC in mice (C3Hf/Bi strain) sensitive to oncogenic effect of the drug, but the drug was not immunosuppressive in the I strain, which is relatively resistant to its oncogenic effect. These suggest an important role of immunosuppressive activity of the carcinogens on the process of carcinogenesis, perhaps by weakening the immune surveillance capacity of the host. On the other hand, many potent carcinogens, such as urethane, do not seem to have an immunosuppressive effect⁶. Here we have analysed the effect of DMBA on the antibody response of C3H/He mice to soluble protein antigen, bacterial α-amylase (BαA). Our findings suggest a marked effect of DMBA on the immunological memory.     

CYTOCHEMICAL AND BIOCHEMICAL DETERMINATIONS OF CHANGES IN NUCLEAR HISTONE CONTENT DURING DIFFERENTIATION OF BARLEY ROOT CELLS

Changes in nuclear histone content in barley root cells have been studied by cytochemical methods for identification of histone subtypes and by conjunction with standard biochemical extraction procedure for various histone fractions and alkaline fast green stainability. The results obtained by the cytochemical methods indicate that the nuclear histones in cell nuclei found in their terminal stages of cellular differentiation or elongation contain histones rich in arginine, whereas the nuclei in meristematic cells contain histones rich in lysine. Cytochemicaly intermediate or transitional types of nuclear histones have been observed in cell nuclei which are undergoing differentiation or elongation and in chromosomes of mitotic nuclei. Information obtained from the conjunction of methods of biochemical extraction procedures for various histone fractions and alkaline fast green stainability indicate that the nuclei in well-differentiated cells contain predominantly histones rich in arginine (f3), whereas the nuclei of meristematic cells contain both very lysine-rich histones (f1) and slightly lysine-rich histones (f2). These results suggest the replacement of lysine-rich histones in the nuclei of meristematic cells by arginine-rich histones during cellular differentiation.     

Clinical,Pathological, and Etiologic Aspects of Acquired Dermal Melanocytosis

To study the pathogenesis of acquired dermal melanocytosis (ADM), we reviewed the clinical, immunohistochemical, and ultrastructual features of 34 cases (female, 33, and male, 1) of ADM. The patients’ ages at onset ranged from 8 to 51 years and averaged 26.8+12.7 years. There was a positive family history. Gray-brown macules were mostly recognized on the face. Not only active dermal melanocytes but also non-pigmented c-KIT-and TRP-2-positive immature melanocytes were detected in the dermis. Taken together those clinical and histological findings, activation of pre-existing immature melanocytes by sunlight, estrogen, and/or progesterone, and some other factors, may be the most likely mode of the development of ADM. Moreover, using cultured murine neural crest cells as a model of c-KIT-positive immature melanocytes, we confirmed that endothelin-1, which is produced and secreted by keratinocytes after UV-irradiation, affects melanocytes and accelerated melanogenesis.     

Biological control of container-breeding mosquitoes, Aedes albopictus and Culex quinquefasciatus, in a Japanese island by release of Toxorhynchites splendens adults

To control container-breeding mosquitoes in the small island of Minnajima (0.56 km2), northern Okinawa, Japan, laboratory-reared adults (aged 7-10 days) of Toxorhynchites splendens (Palawan strain), a mosquito with predatory larvae, were released repeatedly during 1984, 1986 and 1987. Thirteen species of mosquitoes (Diptera: Culicidae) occurred in artificial containers, ground pools or crab-holes on the island, the predominant species being Aedes (Stegomyia) albopictus and Culex (Culex) quinquefasciatus. Predatory mosquito larvae of Culex (Lutzia) fuscanus and Cx (Lt.) halifaxii were found commonly in wet containers. In the first year of study, during a period of 54 days from 13 May to 5 July 1984, totals of 879 female and 806 male adults of Tx.splendens were released on six occasions. Similarly, between 29 April and 30 August 1986, totals of 2920 female and 2878 male adult Tx.splendens were released. In the third study year, totals of 2041 female and 1783 male Tx.splendens were released on eight occasions during 199 days from 23 April to 7 November 1987. After adult releases at two sites, the immature stages of Tx.splendens were found in 164 out of 502 traps in 1984, 421 out of 933 traps in 1986, and 151 out of 502 traps in 1987. The number of immatures of Tx.splendens present in each trap varied from 1 to 40 in 1984, 1 to 29 in 1986 and 1 to 9 in 1987. Numbers of immatures of the target species found in the traps during August-September averaged 71.9/trap/month in 1984, 114.7/trap/month in 1986 and 36.0/trap/month in 1987, significantly less in the traps with Tx.splendens than in those without them. The present field studies indicated that, in this small island, approximately 250 adult female and 200 male Tx.splendens per month should be released from April to November, and the releases should be carried out every year, in order to control effectively the target mosquitoes Ae.albopictus and Cx quinquefasciatus breeding in artificial containers in Minnajima.