Symbiote-Free Hemoflagellates,Blastocrithidia culicis and Crithidia oncopelti: their Liver Factor Requirement and Serologic Identity*

SYNOPSIS. Several aposymbiotic strains of Blastocrithidia culicis and Crithidia oncopelti were cultivated in Trager's chemically defined medium as well as in a blood broth, both supplemented with 0.25% (v/v) liver extract concentrate. For all such strains, the liver extract was found to serve as an essential growth factor in the defined medium and as growth promoting additive in the blood broth. The active molecules were found to be water-soluble, heat stable, dialyzable, and probably nonlipid fractions. Antisera were developed in rabbit against all the available aposymbiotic strains. An almost total cross-reactivity at very high titers was observed in reciprocal agglutination test using strains with and without the bacterial symbiotes. These results indicate that the loss of the symbiotes does not affect the antigenic identity of B. culicis and C. oncopelti.     

Cultivation studies on wild and hybrid strains of Pleurotus tuberregium (Fr.) Sing. on wheat straw substrate

Wild of strains Pleurotus tuberregium from Nigeria and the Australasian-Pacific regions and selected hybrids were studied to determine their growth and sclerotia production capacity on wheat straw substrate. Although the Australasian-Pacific strains showed faster growth rates, the wild strains from Nigeria performed better than the Australasian-Pacific strains in sclerotia yield. Under similar conditions, some hybrids had sclerotial yields that were higher than any wild strain. Our study showed the possibilities of using selected strains and the low cost methods adopted in this experiment, for the cultivation of sclerotia of P. tuberregium.     

Genetic studies of murine catalase: Regulation of multiple molecular forms of kidney catalase

Starch gel electrophoresis of kidney catalase in inbred strains C3H and C57BL/6, their F₁ hybrid, and first and second backcross generations demonstrated that single-component (type A) v. multiple-component (type B) electrophoretic patterns are controlled by a single locus. The type A electrophoretic pattern is dominant. Twenty-five inbred strains of mice were classified according to their kidney catalase electrophoretic pattern. The data indicate that the segregating genetic factor determines a specific substance in the type A kidney which affects the electrophoretic mobility of catalase. A comparison of the F₁ hybrid enzyme with a 1:1 mixture of C3H and C57BL/6 enzyme showed that the alteration of electrophoretic mobility is the result of posttranslational modification of the catalase molecule. An association of kidney catalase electrophoretic pattern and the H-2 ^k haplotype indicates that the locus controlling the electrophoretic pattern is most likely located on chromosome 17 in close proximity to the H-2 complex.     

Genetic characterization of Tetrahymena thermophila mutants unable to secrete capsules

Under appropriate conditions, Alcian Blue-induced exocytosis of Tetrahymena mucocysts leads to formation of a capsule that surrounds the cell. This phenomenon is an example of regulated secretion, a mechanism of fundamental significance in eukaryotic cells. In order to dissect genetically the mechanism of mucocyst biogenesis and regulated exocytosis, mutants unable to form capsules (Caps–) were isolated. In this paper we report a genetic characterization of Caps– mutants in this collection. The mutations in mutants SB255 and SB281 behave as single recessive Men-delian mutations. The mutation in SB251 is restricted to the macronucleus, and could not be further characterized by the genetic methods we used. Complementation tests suggest the existence of at least 2 genes, named exoA and exoB; additional mutant loci are likely to be included in the mutant collection. Deletion mapping using nulli-somic strains showed that exoA and exoB are located on the left arm of chromosome 4. The exo-3 mutation, which behaves as recessive and complements with exoA1 in SB255 and exoB2 in SB281, maps to chromosome 3. These Caps– mutants may be useful for the elucidation of the developmental pathway of mucocyst biogenesis and the control of regulated secretion in eukaryotic cells. © 1992 Wiley-Liss, Inc.     

A rapid identification method for aflatoxin-producing strains ofAspergillus flavus andA. parasiticus by ammonia vapor

The colony reverse of aflatoxin (AF)-producing strains ofAspergillus flavus andA. parasiticus turned pink when their cultures were exposed to ammonia vapor. The color change was visible for colonies grown on media suitable for AF production such as potato dextrose, coconut, and yeast extract sucrose agars after 2 d incubation at 25°C. Of the 120 strains ofA. flavus, A. parasiticus, and two related species inA. flavus group:A. oryzae andA. sojae tested in this study, only the AF-producing strains ofA. flavus andA. parasiticus showed the pink pigmentation. The color change occurred immediately after the colony was contacted with ammonia vapor. This method was useful for rapid screening the AF-producing strains ofA. flavus andA. parasiticus.     

Isoelectrophoretic characterization of extracellular polygalacturonases of variousAspergillus alliaceus strains

The composition of pectin hydrolase complexes produced by variousAspergillus alliaceus strains was studied under the conditions of induction, catabolite repression, or constitutive synthesis. The strains were found similar in terms of the polygalacturonase spectrum and different with regard to the levels of endo- and exoenzyme activities. The analysis of the zymograms of inducible polygalacturonases revealed that all tested cultures contained at least 24 molecular forms of polygalacturonase. Taking into account only the three molecular forms typical of all analyzed strains ofA. alliaceus with pI values of 5.7, 5.9, and 6.3, one can use the spectrum of constitutive, catabolite repression-resistant polygalacturonases as an additional taxonomic species criterion.     

Nucleotide sequence of the extracellular α-amylase gene in the yeast Schwanniomyces occidentalis ATCC 26077

The Schwanniomyces occidentalis (formerly castellii) ATCC 26077 (CBS 2863) alpha-amylase (AMY 26077) gene was cloned in Saccharomyces cerevisiae and sequenced. An open-reading frame encoding the AMY consists of 1536 base pairs and contains 512 amino-acid residues, which is almost the same in size as the AMY of Sch. occidentalis ATCC 26076 and CCRC 21164. The amino-acid sequence of AMY 26077 differed from that of ATCC 26076 alpha-amylase (AMY 26076) at two residues and from that of CCRC 21164 alpha-amylase (AMY 21164) at three residues. Comparison of the AMY 26077 gene with its homologues from two other strains (Sch. alluvius CBS 1153 and Sch. persoonii CBS 2169) using several restriction enzymes revealed that the AMY 26077 was very similar to AMY CBS 1153 but different from that of CBS 2169.     

Amino acid composition of azolla as affected by strains and population density

The total nitrogen and amino acid composition of seven Azolla strains were compared at four different growth phases. Total nitrogen content of the individual strains ranged from 2.6% to 5.7% of dry matter and was not significantly influenced by growth phase or population density. The concentration of the sixteen amino acids determined was maximal during the linear growth stage and specific differences occurred among Azolla strains. AnAzolla microphylla strain was the best source of amino acids and anA. filiculoides strain the poorest under the cultural conditions used. The chemical index score demonstrated the potential of some species, such as theA. microphylla strain, as contributor of protein for animals. Strains of other species, such asA. filiculoides, had several limiting amino acids and appear more suited for use solely as a green manure. All Azolla strains contained a similar proportion of essential (55%) and non-essential (45%) amino acids. Leucine, lysine, arginine and phenylanine+tyrosine were the predominant essential amino acids whereas the sulfur containing amino acids (methionine and cystine) were present in smaller amounts.     

Specific relations between some strains of diazotrophs and corn hybrids

Summary We tested the effect of a large number of diazotrophic strains from the genera Azotobacter, Klebsiella, Escherichia, Derxia, Beijerinckia, and Azospirillum, on nitrogen concentration in four corn hybrids. The range obtained, from highly significant positive to highly significant negative effects, indicates that the strains studied differed in their characters, including the capacity to form useful associations with certain hybrids. The forming of positive associations depended on the specificity of diazotrophic strains and corn hybrids.