Snail Mantle Tissue as a Matrix for Processing Insect Eggs and Other Small Objects

It has been found that by aligning Drosophila eggs in the desired order on the external surface of a piece of excised mantle tissue of the garden snail, Helix aspersa, it is possible easily to handle large numbers of these eggs. The mantle tissue secretes mucus which holds the eggs in position so that they may be carried through stages of fixation, dehydration and imbedding without loss and without any of the technical difficulties usually attendant upon handling small objects. The method need not be restricted to insect eggs but may be extended to other small bits of biological material.     

The exudation and characterization of iron-solubilizing compounds in a rice cell suspension culture

Some compounds capable of solubilizing ferric chloride as theiron source were released into the growth medium from culturedrice cells in the latter half of the growth cycle. This exudationof iron-solubilizing compounds was repressed by an additionof ammonium ion, which, of five cations, was taken up most rapidly.These iron-solubilizing compounds from cultured rice cells wereidentified by chromatography to be principally malic acid andsome citric acid. In the medium containing almost insolubleferric chloride as the iron source, the growth rate of the culturedcells decreased when cells were inoculated at a low populationdensity. This iron deficiency at the low initial populationwas rectified by an addition of a small amount of conditionedmedium or malic acid. (Received May 22, 1980; )     

The exudation and characterization of iron-solubilizing compounds in a rice cell suspension culture

Some compounds capable of solubilizing ferric chloride as theiron source were released into the growth medium from culturedrice cells in the latter half of the growth cycle. This exudationof iron-solubilizing compounds was repressed by an additionof ammonium ion, which, of five cations, was taken up most rapidly.These iron-solubilizing compounds from cultured rice cells wereidentified by chromatography to be principally malic acid andsome citric acid. In the medium containing almost insolubleferric chloride as the iron source, the growth rate of the culturedcells decreased when cells were inoculated at a low populationdensity. This iron deficiency at the low initial populationwas rectified by an addition of a small amount of conditionedmedium or malic acid. (Received May 22, 1980; )     

A possible mechanism for the changes in hepatic and intestinal alkaline phosphatase activities in bile-duct-ligated rats or guinea pigs

The effects of bile-duct ligation on hepatic and intestinal (jejunum) alkaline phosphatase activities were studied using rats and guinea pigs. In ligated rats, the enzyme activity was increased 4.1-fold in the liver after 24 h and 2.8-fold in the intestine after 12 h. In guinea pigs, the hepatic and intestinal enzyme activities were increased 2.3-fold and 1.5-fold after 100 and 24 h, respectively. The intestinal activity was induced sooner after ligation than hepatic activity. The induction of alkaline phosphatase was inhibited by prior treatment of animals with amanitin, an inhibitor of RNA polymerase activity. This result indicates that the induction is associated with de novo enzyme synthesis. The content of cyclic AMP in liver and intestine increased immediately after ligation. The increase in alkaline phosphatase activities was also inhibited by pretreatment with chlorpromazine, an inhibitor of adenylate cyclase activity. Hence, cellular cyclic AMP may be implicated in playing a role in the induction of alkaline phosphatase by bile-duct ligation.     

Calpain II-like proteinase of scallop (Patinopecten yessoensis) striated adductor muscle.

1. A Ca(2+)-dependent cysteine proteinase was purified from scallop striated adductor muscle by ammonium sulfate fractionation and column chromatography on DEAE-cellulose and Sephacryl S-300. 2. The enzyme is of Mr approximately 200,000, composed of two Mr 100,000 subunits. 3. The enzyme is a cysteine proteinase with optimum activity at pH 6.8 and about 18 degrees C. In addition, it requires 1.7 mM Ca2+ for half-maximal activity and more than 10 mM Ca2+ for maximal activity. Thus the enzyme can be classified as calpain II.     

The growth of four species of Azolla as affected by temperature

The growth of 22 strains of Azolla pinnata R. Br., 3 strains of A. filiculoides Lam. and one strain each of A. mexicana Presl and A. caroliniana Willd. was tested separately in liquid culture media kept in controlled, artificial light (30 klux) growth cabinets. Three temperature levels were used: 33°C (37/29°C day/night), 29°C (33/25°C) and 22°C (26/18°C)/ Photoperiod was 12 h a day.For most A. pinnata strains (except three) and an A. mexicana strain the maximum weekly relative growth rate was higher at 33°C than at 22°C, but not for A. filiculoides and A. caroliniana. The highest value of maximum relative growth rate corresponded to 1.9 doubling days and in most strains this occurred in the first week. As the plants grew, the growth rate slowed down more severely at higher temperatures. The maximum biomass was higher at 22°C than at 33°C in all strains. At 22°C, it took 30–50 days to attain maximum biomass and the highest value was 14 g N m^?2 or 320 g dry m^?2 by A. caroliniana, followed by 12 g N m^?2 or 290 g dry wt. m^?2 by one strain of A. filiculoides. At 29°C, the maximum biomass was attained in 20–35 days. The highest value was 6.3 g N m^?2 or 154 g dry wt. m^?2 by A. caroliniana. At 33°C, most A. pinnata strains gave a maximum biomass of less than 4 g N m^?2 after 13–23 days, while some strains grew up to 30 days, resulting in a higher maximum biomass. The highest maximum biomass at 33°C was 5.5 g N m^?2 or 140 g m^?2 dry wt. by A. pinnata from Cheng Mai while the maximum biomass of A. filiculoides and A. caroliniana was much less. Azolla filiculoides requires lower temperature than other species for its growth. Azolla pinnata has the best tolerance to high temperatures among the four species. Azolla mexicana could not be discriminated from A. pinnata in its response to temperature. Azolla caroliniana may keep an intermediate position between A. filiculoides and A. pinnata in temperature response.The formation of ammonia in the medium was examined and it occurred mostly under stationary growth conditions, but, at 33°C, some strains of A. pinnata and A. mexicana released or formed ammonia at 0.3–0.8 μg N ml^?1 per week during their initial exponential growth stage.     

Ca2+-sensitizing effects of the mutations at Ile-79 and Arg-92 of troponin T in hypertrophic cardiomyopathy

Several mutationsin human cardiac troponin T (TnT) gene have been reported to causehypertrophic cardiomyopathy (HCM). To explore the effects of themutations on cardiac muscle contractile function under physiologicalconditions, human cardiac TnT mutants, Ile79Asn and Arg92Gln, as wellas wild type, were expressed in Escherichiacoli and exchanged into permeabilized rabbit cardiac muscle fibers, and Ca²⁺-activatedforce was determined. The freeCa²⁺ concentrations required fortension generation were found to be significantly lower in the mutantTnT-exchanged fibers than in the wild-type TnT-exchanged fibers,whereas no significant differences were found in tension-generatingcapability under maximal activating conditions and in cooperativity.These results suggest that a heightenedCa²⁺ sensitivity of cardiac musclecontraction is one of the factors to cause HCM associated with theseTnT mutations.

     

Activation of phospholipase A2 in rabbit erythrocyte membranes by a novel hemolytic toxin (H-toxin) of Clostridium septicum

A primary effect of a novel H-toxin of Clostridium septicum on the hemolysis of rabbit erythrocytes was shown to be the activation of phospholipase A2 (PLA2) associated with rabbit erythrocyte membranes by 20-fold that of controls. Furthermore, the activation of PLA2 induced by the H-toxin was enhanced in the presence of NAD. The H-toxin itself had no PLA2 activity. On the contrary, the H-toxin bound to palmitic acid at a molar proportion of 1:1 and lost its hemolytic activity. The PLA2 was not activated by the H-toxin bound to palmitic acid. These results suggest that activation of the PLA2 is responsible for development of the hemolytic activity of the H-toxin.