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51.
Ninety-seven strains of Cryptococcus neoformans and C. bacillisporus were examined for 44 biochemical characters and the results were analyzed numerically. One phenon emerged at the 86% level of similarity when strains were clustered according to their M-similarity values. All strains grew in ten carbon sources (D-glucose, D-galactose, arbutin, maltose, sucrose, D-melezitose, D-xylose, D-mannitol, D-glucitol, and meso-inositol), and also grew at 37 ° C and produced urease and phenoloxidase. None of them grew in melibiose, lactose, nor valine, and none reduced nitrate to nitrite. Comparison of selected biochemical characters, creatinine utilization, and serotypes of 49 aberrant strains is presented. Forty-eight of the 97 strains produced the Filobasidiella state either alone or when paired with a strain of compatible mating-type. Filobasidiella neoformans serotypes A and D were interfertile with compatible mating-types of F. bacillispora serotypes B and C. The 44 biochemical characters and 4 serotypes did not predict barriers to mating competence. The present study further substantiates that Filobasidiella neoformans and F. bacillispora are one species. 相似文献
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53.
Christopher R. Bailey Hugh A. Penfold Herbert N. Arst Jr. 《Molecular & general genetics : MGG》1979,169(1):79-83
Summary In Aspergillus nidulans expression of the gabA gene, the probable structural gene for the -amino-n-butyrate (GABA) permease, is controlled by induction, via the intA gene, ammonium repression, mediated by the areA gene, and probably carbon catabolite repression. Regulatory mutations, tightly linked to gabA, were selected by reverting an areA-2 strain on GABA as nitrogen source. These mutations, gabI-1, gabI-2, and gabI-3 result in increased gabA expression and are cis-dominant in their effects on the gabA gene. Mapping data show that the regulatory mutations map on one side of all gabA- alleles tested. 相似文献
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55.
Recombination inH-1, the major histocompatibility complex (MHC) of the rat, has defined two regions,H-1A andH-1B, which determine antigens apparently homologous to the KJD and Ia antigens of the mouse, respectively. Alloantisera directed at these antigens have been absorbed with kidney homogenates. The results showed that cells in the kidney express serologically detectable MHC antigens determined by both theH-1A andH-1B region. Control absorptions indicated that to account for these results in terms of recirculating lymphocytes, two perfused kidneys would need to contain more than 60 percent of the recirculating lymphocyte pool. It appears likely, therefore, that H-1B antigens are expressed by cells resident in the kidney. 相似文献
56.
Summary In an effort to establish the reasons for the limitations in the final ethanol concentration of Zymomonas mobilis fermentation, the effects of CO2 and ethanol on the fermentation were investigated using continuous and fed-batch cultivation systems. The nucleation and
stripping out of CO2 from the fermenter using diatomaceous earth or nitrogen gas or both exhibited a profound effect on the glucose uptake rate
during the early stages of fed-batch fermentation, but did not improve final ethanol yields. The addition of ethanol together
with above mentioned experiments confirmed conclusively that ethanol inhibition is responsible for the final ethanol concentration
obtainable during Zymomonas mobilis fermentation. The final concentration lies between 90 and 110 gl−1 or approximately 12–15% (v/v) ethanol. 相似文献
57.
Hugh B. Martin L.L. Houston 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1983,762(1):128-134
A conjugate containing α2-macroglobulin and highly purified ricin A chain was made using N-succinimidyl-3-(2-pyridyldithio)propionate. Radioimmunoassay indicated that it contained 1.2 mol A chain per mol α2-macroglobulin. The conjugate inhibited polyuridylic-acid directed translation by rat liver ribosomes and protein synthesis in human fibroblasts. There was a 90 min lag period before the beginning of inhibition in fibroblasts, but complete inhibition could be achieved. By measuring protein synthesis as a function of protein concentration, it was demonstrated that 8.25·10?9M conjugate was required to inhibit 50% of protein synthesis in 6 h. To achieve the same level of inhibition, 165-times more (1.3·10?6M) unconjugated A chain was required, and 180-times less ricin (4.6·10?11M). Ricin was more than 28 000 times more inhibitory than A chain alone. The presence of α2-macroglobulin did not increase the cytotoxicity of unconjugated A chain, and it even protected the cells to a slight extent. The inhibitory action of the conjugate was blocked by antibodies specific for α2-macroglobulin or ricin, and it was not prevented by galactose or antibodies specific for ricin B chain. Electron microscopy of the conjugate indirectly labelled with ferritin demonstrated that it was internalized by receptor mediated endocytosis through coated pits. These data indicate that the A chain portion of the conjugate survives the conditions in the lysosomes to the extent that it retains its ability to inactivate cytoplasmic ribosomes. 相似文献
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59.
An age-structured population dynamics model is presented that incorporates pheromone-trapping and food-trapping as control methods for an insect pest. The model yields the following results. Low rates of pest survivorship allow lower trapping rates for control. Species with long developmental periods are easier to control than those with shorter developmental periods (other factors being equal) due to lower net survival. The rates of pheromone trapping alone for effective control are usually very high. The combination of pheromone and food trapping allows control with much lower trapping rates than either method alone. Even small amounts of immigration of adult pests into the control area renders pheromone control ineffective, whereas food traps suppress both the immigrants and the resident population. Food- (or odor-) baited traps which attract both males and females are only somewhat more efficient than those which attract females alone. The existence of density-dependent population regulation assists the control program substantially, but this assistance declines as food trapping becomes a more important part of the control program. Larval competition strongly affects the required trapping rates for eradication; species in which all larvae exert strong competition are much easier to control than those in whic the younger larvae contribute little to the total competitive depression. 相似文献
60.
Hugh J. Barclay 《Population Ecology》1992,34(1):131-141
A methodology is developed to assess the effects of spatial distribution on the efficiency of insect pest control. This methodology is especially applicable to pest control methods whose efficiency of action depends either positively or negatively on pest density It is applied here to the sterile insect technique and pheromone trapping for male annihilation, which both depend negatively on density. This methodology relies on quantifying clumps of various size and then relating this to efficiency of control and predicting the total pest production given the information on clump sizes and efficiency of control for each clump size. It is found that control is about four times as difficult for a population that is highly clumped (k of the negative binomial distribution=0.25) as for a regularly dispersed population. 相似文献