Studies on the physiological bases of morphogenesis in fungi; the respiratory metabolism of dimorphic pathogenic fungi

The interconversions of mycelial and yeast-like forms (M right harpoon over left harpoon Y) in Blastomyces dermatitidis and in Blastomyces brasiliensis are characterized as examples of thermal dimorphism since the phenomena are apparently dependent only on the temperature of incubation of these two species. The change in morphology consequent upon Y --> M conversion is considered to result from the selective inhibition of cell division, without the simultaneous inhibition of growth. Such selective inhibition is viewed in a wider context as an example of the differential operation of the physicochemical apparatus of the cell in the control of form development by an organism. To analyze this differential operation, which is here dependent only on temperature, we have studied the effect of temperature on oxygen consumption by each of the dimorphic forms. In the absence of external substrate the yeast forms consume 5 to 6 times more oxygen per unit dry weight than do the M forms.The Y forms exhibit an exogenous oxidation of acetate and of glucose, as well as an oxidative assimilation of these substrates, whereas the M forms exhibit no exogenous metabolism in either a resting or starved condition. A study of the effect of a wide range of temperatures on oxygen consumption by the M forms indicates the operation of two rate-limiting processes: (a) one with an activation energy of 13,250 calories/gm. molecule over the range 5-30 degrees , and (b) reversible enzyme inactivation; the latter process assuming importance in the higher temperature range. On abrupt, large changes in temperature the balance between these two rate-limiting reactions (which it is suggested characterizes the steady state) is apparently disrupted as a result of a lag in the assumption of a rate of reversible enzyme inactivation characteristic of the new temperature. This disruption of balance is evidenced in overshoot phenomena. The effect of an analogous disruption of balance, and of increasing enzymic inactivation; on a competition between enzyme systems, competing for substrate for cell elongation and for cell division, is considered in explanation of the observed dependence of the cell division mechanism on the maintenance of an elevated temperature.     

Polyamines in dimorphic fungi

The polyamine contents of the yeast and mycelial forms of seven dimorphic fungi were examined to determine if a relationship existed between polyamine composition and fungal morphology. Although the polyamine contents differed, no consistent patterns emerged. Evidently, the observed differences in polyamine composition were not related to fungal dimorphism but rather to the growth conditions used to achieve those morphological forms.     

The parasitic fungi of Aydin province

This paper gives a list of 57 species of parasitic fungi collected from the province of Aydin. Out of these species, 5 are new to the Turkish parasitic fungal flora, and new hosts for 7 species are reported from Turkey for the first time.Thesis submitted by the senior author for M. S. degree.     

Phase transition in dimorphic fungi

The morphogenetic process, the transition from the micelial to fungal growth phase in imperfect microscopic dimorphic fungi Phaeococcomyces de Hoog (strain Ch49), induced by high concentrations of transition metal ions, was considered in terms of the phase transition theory. It was shown that, although microscopic dimorphic fungi developing in the culture represent a system far from equilibrial, the transitions from the micelial to fungal phase under determined external influences have features characteristic for a common phase transition.     

Protective antibodies and endemic dimorphic fungi

The host response to infection is the outcome of a complex interaction between a microbe and a host's innate and adaptive immune system. In this context, the role of antibody in the endemic mycoses is relatively poorly understood. Recently, a monoclonal antibody to a cell surface protein has been shown to be protective in a murine histoplasmosis model. The findings with Histoplasma capsulatum may provide a paradigm for antibody protection against endemic fungi. This paper reviews the recent data on protective antibody in histoplasmosis and previous data supporting a role for antibody in protective responses in other dimorphic fungi.     

Genomics of parasitic and symbiotic fungi

Complete and partial genome sequence information is underway in several parasitic and symbiotic fungi that infect humans, other animals and plants. Comparative analyses of these sequences will provide new insights into the genomic plasticity and evolution of parasitism and mutualism in fungi.     

Nematode-trapping fungi against parasitic cattle nematodes

Interactions between larvae of bovine gastrointestinal nematode parasites and nematode-trapping fungi, such as Arthrobotrys and Duddingtonia species and strains have been studied in Denmark. In this article J?rn Gr?nvold, Jens Wolstrup, Peter Nansen and Svend Aage Henriksen discuss how these fungi are able to grow, trap and kill parasitic nematode larvae, both on agar in the laboratory and in cattle faeces in the field.     

丛枝菌根真菌和植物寄生线虫

本文综述了土壤微生物中丛枝菌根真菌和植物寄生线虫的互作关系及其互作机理,并阐述了丛枝菌根真菌在防治植物线虫病害方面的应用前景和实际操作中应注意的技术环节。     

Synthesis and processing of the dimorphic forms of rat alpha 2u-globulin

alpha 2u-Globulin the androgen-dependent male rat urinary protein, can be resolved into two distinct molecular forms by SDS-polyacrylamide slab gel electrophoresis. These two forms designated as alpha 2u-A (M, 18,800) and alpha 2u (Mr 18,100) are found both in urine and in the liver cells. Translation of rat liver mRNA in the rabbit reticulocyte lysate produced two preprotein forms of alpha 2u-globulin, designated as alpha 2uA' (Mr 20,300) and alpha 2uB' (Mr 19,600). Cell-free translation of rat liver mRNA in the presence of dog pancreas microsomal membrane or in Xenopus oocytes produced the two processed forms of alpha 2u-globulin (alpha 2uA and alpha 2uB). Quantitation of alpha 2uA and alpha 2uB within the in vitro translation products of the hepatic mRNA from albino rats of Yale, Sprague-Dawley and Fischer strains showed genetic differences in the proportion of translatable mRNA for alpha 2uA and alpha 2uB. The ratio of alpha 2uA: alpha 2uB in the translation products of liver mRNA from Yale rats was found to be 1:2.5 while in the case of both Sprague-Dawley and Fischer rats, the ratio was 1:4. A small portion of the alpha 2uA and alpha 2uB synthesized in the cultured hepatocytes, in the Xenopus oocytes or in the membrane-supplemented cell-free system appeared as two additional forms, designated as alpha 2uA" (Mr 21,200) and alpha 2uB" (Mr 20,600). Unlike alpha 2uA and alpha 2uB both alpha 2uA" and alpha 2uB" were found to bind to Con A-Sepharose, suggesting their glycoprotein nature.     

The morphogenesis of dimorphic pollen and anthers in Tripogandra amplexicaulis. Light microscopy and growth analysis

A characteristic of the genus Tripogandra is the presence of two dissimilar whorls of anthers. In T. amplexicaulis the short filamented anthers (S anthers) develop fertile, spheroidal pollen, the long filamented ones (L anthers) develop elongated spores, which degenerate prior to anthesis. Meiosis is regular in both types but occurs approximately two days later in the L anthers. Developmental traits of the L spores are a continuous, uniaxial extension and a sigmoid course of growth in volume accompanied by progressive vacuolarization and growth of starch grains and usually no division. The number of spores in the L anthers amounts to only 60 % of that in the S anthers, but the values for anther fresh weight and pollen sac volume of the former eventually exceed those of the latter and the relative growth rate in these variables is consistently higher in the L anthers. The relative rate in dry weight, however, is similar for both anthers and the absolute rate is clearly lower in the L anthers. These growth characteristics are reflected in a greater vacuolarization of both spores and the amoeboid tapetum in the L anthers. Cytological features of male sterile plants with hypotrophy of the tapetum are related to the sterility syndrome of the L anthers and a common hypothesis for the deviating features is presented.