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1.
Summary The xylanolytic and cellulolytic activity fromCellulomanas were reduced by high O2 concentrations in continous culture as well as by an air flow passed trough the samples, suggesting an inhibition or inactivation of enzymes in such conditions. 相似文献
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The phylogeny of the hominoid primates: a statistical analysis of the DNA-DNA hybridization data 总被引:1,自引:0,他引:1
Sibley and Ahlquist compared the single-copy nuclear DNA sequences of the
hominoid primates using DNA-DNA hybridization. From this data set they
estimated a phylogeny that clusters man and chimpanzees using a distance
Wagner procedure. However, no assessment of statistical confidence in this
estimated phylogeny was made, despite the fact that their data set contains
internal inconsistencies concerning the correct branching order. This paper
presents a modification of Pielou's Q- statistic that allows one to make
nonparametric tests of phylogenetic relationship from distance data. The
results of this analysis indicate that the estimated phylogeny of Sibley
and Ahlquist is without statistical significance owing to the internal
inconsistencies of the data set. A survey and additional analyses of other
types of molecular data indicate that the phylogeny that clusters
chimpanzees and gorillas and has the human lineage splitting off earlier is
statistically consistent with all the molecular data (including the DNA-DNA
hybridization data), whereas the phylogeny estimated by Sibley and Ahlquist
can be rejected at the 5% level using the data on restriction- endonuclease
sites in the mitochondrial genome.
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4.
Localization and synthesis of an antigenic determinant of herpes simplex virus glycoprotein D that stimulates the production of neutralizing antibody. 总被引:54,自引:46,他引:8 下载免费PDF全文
G H Cohen B Dietzschold M Ponce de Leon D Long E Golub A Varrichio L Pereira R J Eisenberg 《Journal of virology》1984,49(1):102-108
An antigenic determinant capable of inducing type-common herpes simplex virus (HSV)-neutralizing antibodies has been located on glycoprotein D (gD) of HSV type 1 (HSV-1). A peptide of 16 amino acids corresponding to residues 8 to 23 of the mature glycoprotein (residues 33 to 48 of the predicted gD-1 sequence) was synthesized. This peptide reacted with an anti-gD monoclonal antibody (group VII) previously shown to neutralize the infectivity of HSV-1 and HSV-2. The peptide was also recognized by polyclonal antibodies prepared against purified gD-1 but was less reactive with anti-gD-2 sera. Sera from animals immunized with the synthetic peptide reacted with native gD and neutralized both HSV-1 and HSV-2. 相似文献
5.
Dr AR Holmes RD Cannon HF Jenkinson 《Journal of industrial microbiology & biotechnology》1995,15(3):208-213
The yeastCandida albicans coaggregates with a variety of streptococcal species, an interaction that may promote oral colonization by yeast cells.C. albicans andCandida tropicalis are the yeasts most frequently isolated from the human oral cavity and our data demonstrate that both these species bind toStreptococcus gordonii NCTC 7869 while two otherCandida species (Candida krusei andCandida kefyr) do not. Adherence ofC. albicans was greatest when the yeast had been grown at 30° C to mid-exponential growth phase. For 21 strains ofC. albicans there was a positive correlation between the ability to adhere toS. gordonii and adherence to experimental salivary pellicle. Whole saliva either stimulated or slightly inhibited adherence ofC. albicans toS. gordonii depending on the streptococcal growth conditions. The results suggest that the major salivary adhesins and coaggregation adhesins ofC. albicans are co-expressed. 相似文献
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Field observations on the biology ofMetriona elatior (Col.: Chrysomelidae) onSolanum elaeagnifolium (Solanaceae) from Uruguay.
Specimens ofMetriona elatior were found feeding on leaves of the silverleaf nightshade,Solanum elaeagnifolium, from the eastern of Uruguay since 1984. According to a field study the young leaves were skeletonized since spring to early
autumn by larvae and adults. Oothecae and pupae were found mainly on old leaves. The egg mean volume was of 0.614 mm3. Young plants of the weed were always killed after massive natural infections ofM. elatior. Therefore, this tortoise leaf-beetle may be studied as a potential biocontrol agent on populations ofS. elaeagnifolium.
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Cloning of the two pyruvate kinase isoenzyme structural genes from Escherichia coli: the relative roles of these enzymes in pyruvate biosynthesis. 下载免费PDF全文
We report the cloning of the pykA and pykF genes from Escherichia coli, which code for the two pyruvate kinase isoenzymes (ATP:pyruvate 2-O-phosphotransferases; EC 2.7.1.40) in this microorganism. These genes were insertionally inactivated with antibiotic resistance markers and utilized to interrupt one or both pyk genes in the E. coli chromosome. With these constructions, we were able to study the role of these isoenzymes in pyruvate biosynthesis. 相似文献
10.
Salicylic acid and the plant pathogen Erwinia carotovora induce defense genes via antagonistic pathways 总被引:3,自引:2,他引:1
Sabina Vidal Inés Ponce de León Jürgen Denecke E. Tapio Palva 《The Plant journal : for cell and molecular biology》1997,11(1):115-123
Infection of tobacco plants with the plant pathogenic bacterium Erwinia carotovora subsp. carotovora or treatment of plants with Erwinia -derived elicitor preparations leads to the induction of a number of genes thought to play a role in plant defense response to pathogens. In order to determine the role of salicylic acid (SA) in the induction of the Erwinia responsive genes, the accumulation of mRNAs for these and other genes encoding pathogenesis-related proteins (PR genes) in response to both Erwinia elicitors and SA was determined. PR genes were identified which were preferentially induced by Erwinia elicitor preparations, one gene was induced by SA but not by Erwinia , and another gene was induced by both type of treatments. The differential expression of these genes and the timing of induction suggest that SA is not the signal molecule leading to the early response of plants to Erwinia . This was demonstrated by experiments using transgenic NahG plants that overproduce a salicylate hydroxylase inactivating SA. The elicitation of PR genes by Erwinia was similar in NahG and wild-type plants. Therefore, induction of plant defense genes by Erwinia and SA seems to be by two distinct pathways leading to expression of separate sets of genes. Furthermore, we could demonstrate that Erwinia elicitors antagonize the SA-mediated induction of PR genes. Similarly, SA appeared to inhibit the induction of PR genes elicited by Erwinia . The observed antagonism between the two signal transduction pathways indicates the presence of a common regulatory element in both pathways that acts downstream of SA in the SA-mediated response. 相似文献