An electron microscopic study on the mating tube formation in the heterobasidiomycete Tremella mesenterica

Ultrastructure of the mating tube formed in yeast haplont of the heterobasidiomycete Tremella mesenterica was studied by electron microscopy. Cell wall of the mating tube emerged as evagination of the inner layers, rupturing outer layers of the mother cell wall. Comparison with budding cells suggested that the tube emergence place at bud scar and the process of tube emergence was the same as that of bud emergence. Electron transparent vesicles of 0.1 m diameter were scattered in the cytoplasm of the mating tube. Nucleus-associated organelle was located at one side of the nuclear envelope which extended towards the mating tube. A few microtubules were detected in the mating tube, but their association with a nucleus was not clear. The cytoplasmic structure of the mating tube was discussed in comparison with that of hyphae of the filamentous fungi.     

Continuous culture of reuber hepatoma cells in serum-free,arginine-, glutamine-and tyrosine-deprived chemically defined medium

Summary The rat hepatoma cell line, H4-II-E, was grown serially over a I-year period and about 30 passages in arginine-, glutamine-, and tyrosine-deprived and ornithine-supplemented Eagle's mininum essential medium with no supplements other than biotin. The adapted cel line, R-Y121B, proliferates in the above mentioned medium with a doubling time of about 4 days and maintains hepatic “marker” enzymes such as tyrosine aminotransferase, phenylalanine hydroxylase, and all the enzymes of the urea cycle. This work was supported in part by Grant-in-Aid for Cancer Research 301050 and Science Research Grant 337013 from the Ministry of Education, Science and Culture, Japan.     

Identification of some abnormal metabolites in psoriatic nail using gas chromatography—mass spectrometry

A gas chromatographic—mass spectrometric analysis was used to separate and identify abnormal compounds in the nail of psoriatic patients. The nail was extracted with heated ethanol, and the extract was analyzed with and without trimethylsilylation. Tetradecanoic acid octadecyl ester, hexadecanoic acid octadecyl ester and octadecanoic acid octadecyl ester were first identified in the psoriatic nail, but were not detected in normal nail.     

Properties of crystalline L-ornithine: alpha-ketoglutarate delta-aminotransferase from Bacillus sphaericus.

The distribution of bacterial L-ornithine: alpha-ketoglutarate delta-aminotransferase (L-ornithine:2-oxo-acid aminotransferase [EC 2.6.1.13]) was investigated, and Bacillus sphaericus (IFO 3525) was found to have the highest activity of the enzyme, which was inducibly formed by addition of L-ornithine or L-arginine to the medium. L-Ornithine:alpha-ketoglutarate delta-aminotransferase, purified to homogeneity and crystallized from B. sphaericus, had a molecular weight of about 80,000 and consisted of two subunits identical in molecular weight (41,000) and in amino-terminal residue (threonine). The enzyme exhibited absorption maxima at 278,343, and 425 nm and contained 1 mol of pyridoxal 5'-phosphate per mol of enzyme. The formyl group of pyridoxal 5'-phosphate was bound through an aldimine linkage to the epsilon-amino group of a lysine residue of the protein. The enzyme-bound pyridoxal 5'-phosphate, absorbing at 425 nm, was released by incubation with phenylhydrazine to yield the catalytically inactive form. The inactive enzyme, which was reactivated by addition of pyridoxal 5'-phosphate, still had a 343-nm peak and contained 1 mol of a vitamin B6 compound. The holoenzyme showed positive circular dichroic bands at 340 and 425 nm, whereas the inactive form had no band at 425 nm. The enzyme was highly specific for L-ornithine and alpha-ketoglutarate and catalyzed delta-transamination between them to produce L-glutamate and L-glutamate-gamma-semialdehyde, which as spontaneously converted to delta 1-pyrroline-5-carboxylate. The enzyme activity was significantly affected by nonsubstrate amino acids, amines, and carbonyl reagents.     

Stimulation of DNA synthesis by heated human serum in primary cultured normal adult rat hepatocytes

In primary culture of normal adult rat hepatocytes, human serum heated at 56°C for 30 min stimulated dose-dependently [³H]thymidine incorporation into trichloroacetic acid insoluble fraction of the cells, most of which was solubilized into hot trichloroacetic acid solution. The solubilized fraction was reduced when hydroxyurea was added to the culture. The heated serum also increased dose-dependently protein synthesis and cell viability determined from morphological findings. These results suggest that human serum has heat-stable factors stimulating DNA synthesis and maintaining cell viability of cultured rat hepatocytes.     

Steering responses of adult and nymphal crickets to light,with special reference to the head rolling movement

Most tethered adult crickets (Gryllus bimaculatus) assumed flight postures with or without flapping their wings in a windstream. Nymphal crickets (sixth and seventh, i.e. final, instars) also displayed the flight posture in spite of the incompleteness of wing development. These adult nymphal crickets rolled their heads towards the light source in response to unequal illumination of the compound eyes only while maintaining the flight posture. The amphtude of the head rolling movements was proportional to the change of light position up to 120°C, and independent of the light intensity if the duration was longer than 1 sec. The unequal illumination could also induce a transient increase in discharge frequency of the wing muscles on both sides, a decrease in wing beat amplitude of the ipsilateral wing on the illuminated side, and bending movements of the legs and abdomen towards the light. Cutting either of the nerve connectives at any level between the subosophageal and metathoracic ganglia did not affect the response of either the head or the abdomen to illumination. These results are discussed in relation to the steering mechanism associated with the dorsal light reaction.     

One step purification procedure of elastase from pancreatic powder by affinity chromatography

Pancreatic elastase was isolated from acetone powder of porcine pancreas by a one step purification procedure on a trialanyl CH-Sepharose 4B affinity column. This column exhibited affinity not only for active elastase but also for trypsin and chymotrypsin which were present in the same pancreatic powder. However, as the extent of affinity toward elastase is considerably higher, the proper conditions were determined with which the adsorbed elastase was isolated in a highly purified form. The yield of elastolytic activity ranged from 60–85% and the purified elastase was shown to be one component by polyacrylamide disc electrophoresis.     

Properties of taurine: alpha-ketoglutarate aminotransferase of Achromobacter superficialis. Inactivation and reactivation of enzyme

The activity of taurine: alpha-ketoglutarate aminotransferase (taurine: 2-oxoglutarate aminotransferase, EC 2.6.1.55) from Achromobacter superficialis is significantly diminished by treatment of the enzyme with (NH4)2SO4 in the course of purification, and recovered by incubation with pyridoxal phosphate at high temperatures such as 60 degrees C. The inactive form of enzyme absorbing at 280 and 345 nm contains 3 mol of pyridoxal phosphate per mol. The activated enzyme contains additional 1 mol of pyridoxal phosphate with a maximum at 430 nm. This peak is shifted to about 400 nm as a shoulder by dialysis of the enzyme, but the activity is not influenced. The inactive form is regarded as a partially resolved form, i.e. a semiapoenzyme. The enzyme catalyzes transamination of various omega-amino aicds with alpha-ketoglutarate, which is the exclusive amino acceptor. Hypotaurine, DL-beta-aminoisobutyrate, beta-alanine and taurine are the preferred amino donors. The apparent Michaelis constants are as follows; taurine 12 mM, hypotaurine 16 mM, DL-beta-aminoisobutyrate 11 mM, beta-alanine 17 mM, alpha ketoglutarate 11 mM and pyridoxal phosphate 5 micron.