摘要:

AbstractStreptomyces coelicolorA3(2) gives rise to spontaneous chloramphenicol sensitive mutants at a frequency of about 0.3% per spore. These mutants are often genetically unstable and give rise to arginine auxotrophs (Arg−) at frequencies of 1–7% per spore. These Arg−mutants usually lack the enzyme argininosuccinate synthetase (one exception was found that lacked ornithine carbamoyltransferase) and were shown to have deleted the correspondingargGgene by hybridisation analysis using a clonedS. cattleya argGgene. The Arg−strains also showed a variety of different DNA amplification and deletion events in a region homologous to an amplified DNA sequence found in spontaneous Arg−mutants inS. l

ISSN:0233-111X    

DOI:10.1002/jobm.3620270102

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractSporangia and zoospores of the oomycetePhytophthora infestansare characterized by a number of tubular cytoskeletal elements: Single and bundled cytoplasmic microtubules, arising from electron dense material at the centrioles, form a network inside the zoospores of the fungus. Nucleus‐associated microtubules surround the nucleus in a basket‐like manner. Spindle microtubules occurring during mitosis in zoosporangia are partially maintained from the late telophase till the zoospore stage. The pattern of flagellar microtubules is identical to that of the typical eukaryotic flagella. The bundles of 15 nm‐tubules observed in ER‐cisternae of zoosporangia and zoospores are similar to preformed mastigonemes of tinsel flagella because of their dimensions. Microtubules, flagellar fragments, and mastigonemes, similar in substructure to those of other lower and higher eukaryotes, have been isolated from zoospores ofPhytophthora infestansby lysis in Triton X‐100 on microtubule‐stabilizing

ISSN:0233-111X    

DOI:10.1002/jobm.3620270103

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractIn mycelia ofStreptomyces granaticolorgrown in liquid cultures the distribution of DNA was surveyed by staining and autoradiographic methods. The frequency of stained nucleoids was rather similar in young and old hyphal regions. However, the size of the nucleoids increased with the age of a hyphal region. The degree of heterogeneity in nucleoid size was particularly high during slow growth. In the autoradiograms silver grains (3H‐thymidine label) were also heterogeneously distributed along the hyphae. Calculation of the average number of silver grains per nucleoid revealed that the amount of DNA per nucleoid was 1.6 times higher in the more distant subapical regions than within the 35 μm long apical region.From a chase experiment it became obvious that the DNA segregated in a normal manner only within the apical region. When the chase lasted for one doubling time, the frequency of silver grains was reduced to 50% only within the about 30 μm long apical region. The label incorporated subapieally remained almost constant, therefore, indicating a lack of normal segregation. Only about 10% of the label was lost by branching. The lack of segregation of sister nucleoids after repeated rounds of replication was found to be responsible for the increase of nucleoid size within subapieal hyphal regi

ISSN:0233-111X    

DOI:10.1002/jobm.3620270104

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractAddition of cooper‐monovalent‐nicotinic acid complex to a synthetic medium specific for kojie acid production byAspergillus flavusenhanced the production by about 47%. The substance is proposed to act via a biochemical utilization of the copper(I)‐B3complex in a manner similar to that of the naturally utilized nicotinic acid. NAD and NADP like carriers with higher reactivity have been predicted.According to this prediction the biosynthetic route of kojic acid has been interpreted on the basis of a model proposed by BAJPAIet al.(1981). In this model the enzymes participating are dependent on NAD and NADP (glucose dehydrogenase and gluconate dehydrogenase) as well as on other reduction proc

ISSN:0233-111X    

DOI:10.1002/jobm.3620270105

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractDifferences in intracellular enzyme activities between cells accumulating lipid and proliferating cells were studied withLipomyces starkeyi, a fat‐producing yeast. When the cells were removed from a medium for lipid accumulation to a medium for cell proliferation, activities of several enzymes on the glycolytic pathway, pentosephosphate cycle, glycerol 3‐phosphate pathway, tricarboxylic acid cycle and fatty‐acid biosynthesis pathway changed. In the proliferating cells, activities of glycerol‐3‐phosphate dehydrogenase (GDH) and ATP citrate lyase were very low, as compared to those in the cells accumulating lipids. Activities of these two enzymes and 6‐phosphogluconate dehydrogenase, particularly GDH, decreased with the addition of zinc ion to the cell‐free extract of the cells accum

ISSN:0233-111X    

DOI:10.1002/jobm.3620270106

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractEight species of fungi were consistently obtained from crown rots of Nigerian bananas cv. Robusta. The predominant species wereBotryodiplodia theobromaePAT. andColletotrichum musae(BERK.&CURT) VON ARX. Others include:Ceratocystis paradoxa(DADE) C. MOREAU,Fusarium solani(MART.) SACC.,Fusarium roseumSAYD.&HANS,Fusarium moliniformaeSHELDON,Fusarium oxysporumSCHLECHT andVerticillum theobromae(TURC.) MASON&HUGHES. Growth‐temperature relations showed thatB. theobromaeandC. musaegrew best at 30 °C within the 8‐day incubation period. Both fungal species produced extracellularly, amylases, pectin (methyl) esterase and CM‐cellulases. The synthesis of these enzymes was completely inhibited by the presence of the fungicide benomyl at concentrations of 200 ppm and above in the growth medium. At lower concentrations (50–150 ppm), pectin esterase and CM‐cellulase production was also suppressed while amylases were produced in measurab

ISSN:0233-111X    

DOI:10.1002/jobm.3620270107

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractSerratia marcescens HYbacteria must be lysogenic with either prophageyor ψ to make it possible for phage χ to form plaques unless they carry a so‐calledinkmutation. Genes inyand ψ termedanyandanpwere identified that after infection ofink+cells are necessary for an effective propagation of these phages as well as of coinfecting χ phage. When χ infectsyand/or ψ‐Iysogenic cells it transactivates the respective prophage genes by means of two early genes termedtayandtap.It appears that on infection of nonlysogenicink+cells χ damps its own development, provided the regulatory region of the responsible gene is undermethylated. After χ infection duly to achieve the special methylation of this region seems to be the function ofanyandanp.There are some more genes inyand ψ prophage under the control oftayandtap, concerning in both cases a Dam methylation (recognition sequence GATC) of χ DNA, a recombination proneness under restricting conditions of χ DNA not modified by the modification enzyme ofHY, and the χ plaque size. By hybridization studies a region of homology common toyand ψ was demonstrated which from its size might comprise all the transactivated genes. The view is supported by genetic data indicating an affinity among theanyandanpgenes.Investigation of variousanymutants were indicative of DNA inversions in this region of theygenome. Surprisingly some of theanymutants had become sensitive in their plaque forming ability to an inhibitory activity exerted by prophage ψ. Mutants of ψ unable to interfere but still able to lysogenize were isolated. A model is presented accounting for the formation of pleiotropic and nonpleiotropic mutations with Any phenotype and their reversion types. Possible functions of theygenes and their counterparts

ISSN:0233-111X    

DOI:10.1002/jobm.3620270108

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe specific binding ofEscherichia coliRNA polymerase molecules to the DNA of plasmid pNH602, a deletion derivative of R6K having an increased copy number, was detected by electron microscopy. Seven strong RNApol binding sites were found on pNH602 DNA linearized withBamHI orEcoRI restriction endonuclease. All of these specific sites occur in genetically defined regions of the pNH602 molecule. Two of them correspond with the recently reported transcription initiation sites within a region essential for plasmid R6K replication.

ISSN:0233-111X    

DOI:10.1002/jobm.3620270109

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620270101

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY