The endosome-lysosome system in the absorptive cells of goldfish hindgut

Summary The vacuolar system in the absorptive cells of the goldfish hindgut was studied by rapid freeze-substituted and cytochemical techniques. The apical cytoplasm of the absorptive cells contained two types of vacuoles: endosomes and lysosomes. The former were characterized by an absence of acid phosphatase activity, a dot-like distribution of material at the peripheral rim, the labelling of the inner surface with horseradish peroxidase (HRP), and by frequent connections to cytoplasmic tubules (CT), which were also free of acid phosphatase activity. The latter vacuole was preferentially located in the deeper cytoplasm and was characterized by the presence of acid phosphatase activity, an electron-dense interior matrix, a peripheral electron-lucent region (a halo), and by the detachment of HRP from the inner surface. Connections between CTs and these latter vacuoles were rarely seen. In the deeper cytoplasm, fusion between endosomes and lysosomes was sometimes observed. These results suggest that the vacuoles which are associated with CTs are endosomes, but not lysosomes, and that internalized materials are transported through the endosome-lysosome system to a giant food vacuole in the cell.     

Effects of degranulation of mast cells on proliferation of mesenchymal cells in the mesentery of mice

Summary A mast-cell activator, compound 48/80, causes proliferation of mesenchymal cells in the mesentery of rats. Its effect on W/W ^vmice deficient in mast cells was tested to determine whether the proliferation is mediated in the degranulation of mast cells. Incorporation of [³H]thymidine into mesenchymal cells in the mesentery of these mice with or without compound 48/80 was very small compared to their normal litter mates. However, bone marrow transplantation markedly enhanced the effect of compound 48/80, and resulted in an incorporation of [³H]thymidine almost comparable to that observed in normal mice. Our results provide evidence that mesenchymal cell proliferation is caused by a product secreted by mast cells when stimulated by compound 48/80.Supported by a Grant-in-Aid for Scientific Research, No. 366, from the Japanese Ministry of Health and WelfareThe authors are indebted to Drs. Motomu Minamiyama and Yukio Hirata for valuable advices, and to Miss Mitsuko Inoue for technical assistance     

CO2 is the first species formed upon CO oxidation by CO dehydrogenase from Pseudomonas carboxydovorans

The active species of CO₂, i.e. CO₂ or HCO ₃ ^- , formed in the CO dehydrogenase reaction was determined using the pure enzyme from the carboxydotrophic bacterium Pseudomonas carboxydovorans. Employing an assay system similar to that used to test for carbonic anhydrase, data were obtained which are quite compatible with those expected if CO₂ is the first species formed. In addition, carbonic anhydrase activity was not detected in P. carboxydovorans.     

Photoreception in pineal organs of larval and adult lampreys,Lampetra japonica

A comparative study of the larval and adult pineal organs, which are sensitive to incident light, was carried out in the river lamprey Lampetra japonica, using intracellular recording from the pineal photoreceptors. The tissue overlying the larval pineal organ is transparent, whereas that over the adult pineal is translucent. The optical density of this oval pineal window in the adult lamprey was 1.2. In order to elucidate the early development of the larval pineal, the ratio r of the diameter (micron) of the pineal to the body-length (cm) was measured. The value of r was 62.5 in a small larva of 2.8 cm, 29.7 in a larger one of 14.3 cm, and 9.3 in an adult of 54 cm body-length. The intracellular response to light of the larval pineal was a hyperpolarization, showing fundamentally the same pattern as that of the adult pineal. It was possible to record a typical response even from the pineal of the smallest larva, 2.8 cm in body length, used in this study. The intensity-amplitude relationship was analysed after Naka-Rushton's hyperbolic equation. The value of sigma of isolated larval pineals was 0.88 log unit higher than that of adults. The value of n was larger in larvae, suggesting a sensitive reaction to changing photic stimulus. The spectral sensitivity was compared. The peak was at 505 nm in the larva, but 525 nm in the adult. A change of visual pigment in the pineal during metamorphosis is suggested.     

Electrophoretic heterogeneity and age-related change of serine proteinase fromAspergillus sojae

Five forms of serine proteinase (EC 3.4.21.14) have been purified fromAspergillus sojae. This paper reports heterogeneity of electrophoretic mobilities, isoelectric points, and kinetic parameters of multiple forms of serine proteinase fromAspergillus sojae, including agerelated changes in thek _cat /K _m of electrophoretic species.     

Enzymatic difference between laticifers and cultured cells of papaya

Cell suspension cultures of Carica papaya were found to produce a papain-like enzyme showing an amidase activity similar to papain. Experiments suggested that the enzyme was an SH-enzyme, but an immunological test indicated the absence of papain in cultured cells. The isoelectric point (4.3) of the enzyme of cultured cells was the same as that of the leaf extract, but was different from that of papain or other amidases in the latex of the fruit.     

Cycling of soil carbon in a Japanese red pine forest II. Changes occurring in the first year after a clear-felling

Cycling of soil carbon in the first year after a clear-felling was compared with that before the felling in a Japanese red pine forest in Hiroshima Prefecture, west Japan. The daily mean temperature at the soil surface in summer was increased after the felling in comparison to that before felling, and the water content of both the A₀ layer and the surface mineral soil was decreased due to the loss of the forest canopy. The rate of weight loss of the A₀ layer was reduced after felling. However, accumulation of the A₀ layer rapidly decreased because of the lack of litter supply to the forest floor. Low soil respiration after felling was mainly caused by the cessation of root respiration. Analysis of annual soil carbon cycling was then conducted using a compartment model. The relative decomposition rate of the A₀ layer decreased whereas that of humus and dead roots in mineral soil increased to some extent after felling. The accumulation of carbon in mineral soil, however, increased slightly due to the supply of humus from roots killed by the felling.     

Stimulatory effect of calcium on photoactivation of the water oxidation system in dark-grown spruce chloroplasts

Treatment of platelets or red cells with small amounts of phospholipase C from Clostridium welchii enables both cells, prior to the onset of lysis, to stimulate prothrombin conversion by coagulation factor Xa and Va in the presence of calcium. Phospholipase C treatment of both cells also exposes significant amounts of phosphatidylserine at the outer surface. The level of phosphatidic acid formed from diglycerides produced by phospholipase C action, is similar to that formed in activated platelets upon triggering the phosphatidylinositol cycle. A possible involvement of this cycle to activate platelets to become more procoagulant is discussed.