Enzymatic Maceration of Plant Tissue

Tissue cells of Vicia faba were separated from the leaf pieces by the pectinase treatment after which the chlorophyll determination method was employed. The separation proceeded at a constant rate for 3 hours', the maximum rate of separation was at pH 5.3. The optimal pH shifted to 5.5 in the presence of 0.001 M 2Na-ethylenediaminetetraacetic acid (EDTA), which accelerated the separation at pH levels higher than 5.5. The separation was enhanced by NaCl and MgCL₂ and delayed by CaCl₂ and hypertonicity produced by sugars. Indoleacetic acid (IAA) and naphthaleneacetic acid (NAA) accelerated the separation at physiological concentrations. The rate of separation differed markedly by the age of the leaf and the species which offered the substrate material.     

Improved maintenance of adult rat hepatocytes in a new serum-free medium in the presence or absence of barbiturates

Summary For serum-free primary culture of adult rat hepatocytes, a synthetic medium DM-160 and rat-tail collagen were selected for the basal medium and for the culture substratum, respectively. Barbiturates, such as phenobarbital and 1-ethyl-5-isobutylbarbiturate, efficiently supported survival of hepatocytes and maintained their morphologic features at lower concentrations under the serum-free conditions than under the serum-supplemented conditions. However, the hepatocyte survival rates under the serum-free conditions were lower than those under the serum-supplemented conditions in the presence or absence of barbiturates. Supplementation of the basal medium with a combination of five groups of factors (5Fs), such as eight amino acids (Ala, Arg, Gly, Ile, Met, Phe, Pro, and Trp), two unsaturated fatty acids (linoleate and oleate), a protease inhibitor (aprotinin), three vitamins (A, C, and E), and five trace elements (Mn, Fe, Cu, Zn, and Se), improved the hepatocyte survival under the serum-free conditions in the presence or absence of barbiturates. In other words, the serum could be completely substituted by the 5Fs. Hepatocyte cultures maintained in the 5Fs-suppelemented basal medium showed excellent induction of tyrosine aminotransferase activity in response to dexamethasone in the presence or absence of barbiturates. The efficiency of the 5Fs-supplemented basal medium for maintaining hepatocytes was not inferior to those of other media in common use with hepatocytes, such as Williams' medium E and Waymouth's medium MB-752/1. In conclusion, maintenance of functional hepatocytes in serum-free primary culture could be improved by use of the new medium preparation (the 5Fs-supplemented DM-160) in the presence of barbiturates. This work was supported by a grant no. 61771923 from the Ministry of Education, Science and Culture of Japan.     

Spatio-temporal distribution patterns of two tachinid flies,Epicampocera succincta andCompsilura concinnata parasitizingPieris

Larvae of genus Pieris in the northern part of Kyoto City are parasitized by two tachinid flies:Epicampocera succincta, a specialist on genus Pieris, and Compsilura concinnata, a generalist with very wide host-range. We surveyed the parasitism rates of Pieris by both flies for two years at six study areas. In these study areas, there lived three host species in the genus Pieris: P. rapae, P. melete, and P. napi, but neither tachinid parasitized P. napi to any significant extent. In the mountainous district, P. rapae and P. melete coexisted and their populations were relatively continuous, while in the lowland, only P. rapae larvae were abundant in spring and autumn, but even they disappeared in summer. Parasitisms by E. succincta occurred mainly in mountainous district and never in the lowland. C. concinnata parasitized Pieris in all the areas, but its parasitisms occurred mainly in autumn. We analyzed the factors affecting the spatial and temporal patterns of parasitism rates and presumed that the temporal discontinuity of host population restricted the distribution of the specialist parasitoid.     

Changes of lung surfactant and pressure-volume curve in bleomycin-induced pulmonary fibrosis.

We investigated whether alveolar surface force increased and participated in the lung pressure-volume relationship in bleomycin-induced pulmonary fibrosis in hamsters and, if so, whether lung surfactant was hampered in the lungs. On the air-filled pressure-volume curve, decreases of lung volume from control level were significantly higher at 3-8 cmH2O pressure on day 10 than on day 30. Because the change of lung tissue elasticity evaluated from the saline-filled pressure-volume curve was equal for the 2 days, the higher decrease of air volume on day 10 was due primarily to contribution of alveolar surface force. Pressure differences between deflation limbs of air-filled and saline-filled pressure-volume curves, which represented net alveolar surface force, were significantly higher at any lung volume between 50 and 90% total lung capacity on day 10, but almost no significance was observed on day 30. Phospholipid concentration in bronchoalveolar lavage fluid significantly decreased on day 10 but had improved by day 30. Analysis of phospholipid species in purified lung surfactant showed decreased fractions of disaturated phosphatidylcholine and phosphatidylglycerol on day 10. Surface-active properties of the surfactant, measured by a modified Wilhelmy balance, were remarkably hampered on day 10, but most of them had improved by day 30. We consider that the quantitative and functional abnormalities of lung surfactant have a part in the aggravation of lung mechanics in the acute phase of pulmonary fibrosis.     

Plant regeneration from isolated microspore cultures of Chinese cabbage (Brassica campestris spp. pekinensis)

Isolated microspores of Chinese cabbage (Brassica campestris ssp. pekinensis) were incubated in modified NN medium containing 10% sucrose in darkness at 33°C for one day followed by culture at 25°C. After 14 days of culture, microspores developed into embryos ranging from globular to cotyledonary stage. Plants were regenerated after transfer of embryos to medium containing 3% sucrose and no plant growth regulators.Abbreviations NN Nitsch and Nitsch - MS Murashige and Skoog - NAA naphthaleneacetic acid - BA 6-benzylaminopurine