摘要:

A model for congenital syphilis in rabbits was developed based on multiple intravenous injections of pregnant does with high concentrations ofTreponema pallidum. A total of 48 pregnant does and 394 newborns were evaluated. Indications ofin uteroinfection included a 7- to 10-fold increase in fetal mortality and a 49% reduction in birth weight. The size of the stillborns varied. Some developed to normal size, whereas others were poorly developed, hemorrhagic, and 1/10th normal size. Fetuses were surgically removed after 25 to 28 days of gestation and extracts of the fetal tissues were injected into adult rabbits. Syphilitic lesions resulted demonstrating the presence ofT.pallidumwithin the fetal tissues. Treponemes were also demonstrated within splenic tissue from a 1-week-old newborn. Isolated amniotic membranes were placed in Franz Biologic chambers. Viable organisms readily penetrated through the amnion but heat-inactivated organisms did not. Further evidence forin uterotransmission of organisms was provided by intradermal injection of 6- to 7-week-old newborns. In control newborns in which the does were not infected during pregnancy, lesions occurred at 90% of the sites injected and developed in typical fashion. In newborns from does infected during pregnancy, lesions occurred in 18% of the sites injected and developed in atypical fashion (flat, nonulcerating, rapid healing). Finally, overt congenital syphilis did not occur if the does were immune prior to pregnancy, then infected withT.pallidumduring pregnancy. The percent mortalities and birth weights of newborns were equivalent to control newborns from noninfected does.

ISSN:0008-4166    

DOI:10.1139/m85-142

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

The growth ofPseudomonas putidaATCC 11172 onL-asparagine, citrate,D-glucose, andL-lactate was followed in air and in 40% CO2+ air, using batch and carbon-limited continuous cultures. Batch cultures in air utilized a mixture of the carbon sources simultaneously. However, a change to 40% CO2favoured the utilization of glucose. The maximum specific growth rate (μmax) in air was about 0.3 h−1on glucose and 0.6 h−1on the other carbon sources. In CO2, the μmaxfor glucose was reduced by 16% compared with almost 60–70% for the others. An order of preference for the different carbon sources in continuous cultures was determined by comparing the dilution rates at which the different carbon sources started to appear in the effluent. Glucose was the first compound to appear as the dilution rate increased (lowest preference when grown in air). In 40% CO2, the μmaxfor glucose was slightly higher than the others and the recorded preference for glucose in continuous culture was equal to that for citrate but was somewhat lower than that of lactate and asparagine.D-Gluconate and glucono-δ-lactone were produced as a step in the utilization of glucose. TheD-gluconate production was enhanced by CO2.

ISSN:0008-4166    

DOI:10.1139/m85-143

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

A metabolite ofTrichoderma hamatum, 3-(3-isocyanocyclopent-2-enylidene)propionic acid, was tested for its effects on growth of and carbohydrate metabolism in 11 strains of functionally important rumen bacteria. To standardize the biological activity of this unstable metabolite, a rapid, aerobic disc diffusion assay was developed usingEscherichia coliATCC 11775. In an anaerobic broth dilution assay using a medium lacking rumen fluid and containing a soluble carbohydrate, the minimum inhibitory concentration of the metabolite which completely inhibited growth of the rumen bacteria for 18 h at 39 °C was generally < 10 μg∙mL−1; however, the minimum inhibitory concentrations forMegasphaera elsdeniiB159 andStreptococcus bovisPe18 were 10–25 and 25–64 μg∙mL−1, respectively. In general, the Gram-negative strains were more sensitive than the Gram positive. The minimum inhibitory concentration forBacteroides ruminicola23 grown with glucose was 1 μg∙mL−1; forB.ruminicolaGA33 (glucose),B.succinogenesS85 (cellobiose), andSuccinivibrio dextrinosolvens24 (maltose), it was 2 μg∙mL−1. When added to a cellulose-containing rumen fluid medium, 1–4 μg∙mL−1of the metabolite delayed cellulose hydrolysis byB.succinogenesS85,Ruminococcus albus7, andR.flavefaciensFD1 for up to 4 days, and 6–7 μg∙mL−1prevented hydrolysis for at least 1 month. In the presence of the metabolite, the proportion of acetate produced from soluble carbohydrate by the majority of strains increased, but with some strains net production of acetate decreased relative to production of other acidic fermentation products. If the metabolite gained entrance to the rumen, a concentration of as little as 1 μg∙mL−1would probably cause a significant depression of the fermentation and result in nutritional deprivation

ISSN:0008-4166    

DOI:10.1139/m85-144

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Five different mushrooms were screened for extracellular inulinase and invertase activities. The enzymes were found to be produced constitutively by the mushrooms, but the carbon source, glucose, sucrose, and starch, in the medium influenced the production of individual enzymes. The highest producers of inulinase and invertase werePanaeolus papillonaceusgrowing in starch medium andAgaricus bisporusgrowing in glucose medium, respectively. A medium for the optimum production of invertase and inulinase byP.papillonaceuswas developed by determining the optimum concentrations of suitable carbon and nitrogen sources. Some of the physicochemical properties of the enzymes present in the culture filtrate were studied. Both of the activities have pH optima at 6.5 and temperature optima at 60 °C.Kmvalues for both enzyme activities were found to be identical at 2.5 mg of substrate/mL, whereas the νmfor the inulinase activity was more than two times greater than that for invertase activity.

ISSN:0008-4166    

DOI:10.1139/m85-145

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

The polypeptide patterns of two different strains ofPhysarum polycephalum, sensitive and killer, showed only minor differences on two-dimensional electrophoretograms. After heterologous fusion of the sensitive and killer plasmodia, newly formed proteins could be demonstrated which were not detectable in homologous fused plasmodia. The lethal reaction did not occur until after the aforementioned protein synthesis.

ISSN:0008-4166    

DOI:10.1139/m85-146

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Fusion of sensitive and killer plasmodia ofPhysarum polycephalumcaused a change in membrane composition which did not occur after fusion of two sensitive plasmodia. This change, which was mainly the result of an increase in the synthesis of phosphatidylethanolamine, began 1.5 h after fusion. Heat production and oxygen consumption declined during the processes which underlie the lethal reaction which destroys the fused plasmodia of sensitive and killer strains.

ISSN:0008-4166    

DOI:10.1139/m85-147

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Laterispora brevirama, a fungus found in association with theSclerotiniamycoparasitesSporidesmium sclerotivorumandTeratosperma oligocladum, was markedly similar in morphology to the other two fungi yet differed in its parasitic activity.Laterispora breviramacolonized and proliferated on sclerotia ofSclerotinia minorwhich had been infected first bySporidesmium sclerotivorumorT.oligocladumbut did not do so in the absence of these specific mycoparasites. Macroconidia ofL.breviramagerminated in soil in response to sclerotia infected bySporidesmium sclerotivorum, and to hyphae ofSporidesmium sclerotivorum. Aqueous extracts of hyphal mats ofSporidesmium sclerotivorumstimulated maximal germination of macroconidiain vitro, although other nutrients also supported germination to a lesser extent. In culture and in its parasitic phase in soil,L.breviramaformed specialized contact cells on the hyphae ofSporidesmium sclerotivorumandT.oligocladum, but never appeared to invade hyphae.Laterispora breviramaadded to soil at 1000 macroconidia/g, along withSporidesmium sclerotivorumat the same concentration, did not influence the rate of infection and destruction of sclerotia ofSclerotinia minorbySporidesmium sclerotivorum. The resulting numbers of new macroconidia ofSporidesmium sclerotivorumformed in the soil from energy derived from the infected sclerotia, however, were reduced by the presence ofL.brevirama.Laterispora breviramais either a direct parasite ofSporidesmium sclerotivorumandT.oligocladumor is a secondary parasite ofSclerotiniaspp. that is active only in association with either of the two primary mycoparasites.

ISSN:0008-4166    

DOI:10.1139/m85-148

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

A statistical analysis of relations between the respiration type of Gram-negative marine bacilli and their resistance to zinc and cadmium or their ability to concentrate zinc was carried out on 453 strains isolated from seawater and oysters. A highly significant relation was found between the respiratory type of strains and their resistance (strict aerobes were 3 times more sensitive than facultative aerobes) or their binding capability (strict aerobes accumulated 2.5 times more zinc)

ISSN:0008-4166    

DOI:10.1139/m85-149

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Application of the fungicide Captan to whole soybean seeds stored at 85% relative humidity did not prevent either the development of the natural fungal population underneath the seed coat or the increase of free fatty acids. At 65 and 75% relative humidity the increase in free fatty acids and fungi development during storage were lower than at 85% relative humidity, but even at these lower levels no differences were observed between Captan-treated and nontreated seeds. In split soybeans, where fungi developed profusely on the unprotected damaged site of the seed, treatment with Captan or thiourea resulted in free fatty acid values significantly lower than those of the untreated controls. The fungi most frequently isolated from stored soybeans wereAspergillus candidus,A.ruber,A.versicolor, andPenicillium cyclopium, all of which showed lipolytic activity. Inoculation of intact soybean seeds with these fungi did not cause an increase in free fatty acids as compared with noninoculated controls, probably because the intact seed coat prevented the penetration of the inoculated fungus. The similar increase in free fatty acids in both the inoculated and the noninoculated controls was probably caused by the internal mycoflora in both treatments. Since fungicide treatments prevented the increase of free fatty acid levels in all cases where the fungicide could reach those sites at which fungi developed, it was concluded that fungi play an important role in the increase of free fatty acids in stored soybeans.

ISSN:0008-4166    

DOI:10.1139/m85-150

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

The effect of the partial pressure of oxygen (PO2) on the formation of vesicles, which are thought to be the site of N2fixation inFrankia, was studied in HFPCcI3, an effective isolate fromCasuarina cunninghamiana. Unlike other actinorhizal root nodules, vesicles are not produced by the endophyte inCasuarinanodules. However, in culture under aerobic conditions, large, phase-bright vesicles are formed in HFPCcI3 within 20 h following removal offrom the culture medium and reach peak numbers within 72 to 96 h.In vivoacetylene reduction activity parallels vesicle formation. Optimum rates of acetylene reduction in short-term assays occurred at 20% O2(0.2 atm (1 atm = 101.325 kPa)) in the gas phase. O2uptake (respiration) determined polarographically showed diffusion-limited kinetics and remained unsaturated by O2until 300 μMO2. In contrast, respiration in-grown cells was saturated by O2between 8 and 10 μMO2. These results indicate the presence of a diffusion barrier associated with the vesicles. Vesicle development was repressed in cells incubated in N-free media sparged with gas mixtures withPO2between 0.001 and 0.003 atm. Nitrogenase was induced under these conditions, but acetylene reduction was extremely O2sensitive. The kinetics of O2uptake as a function of dissolved O2concentration in avesicular cells were similar to those in-grown cells indicating the lack of a diffusion barrier. These results demonstrate that vesicle formation and the development of the O2protection mechanisms of nitrogenase are regulated by ambientPO2in HFPCcI3.

ISSN:0008-4166    

DOI:10.1139/m85-151

出版商:NRC Research Press    

年代:1985

数据来源: NRC