Enterococcus faecium CCM4231, isolated from the rumen content of a calf, produced an antimicrobial agent active against Gram‐positive and Gram‐negative indicator organisms. After 100‐fold concentration by ultrafiltration, the diameters of zones of inhibition ranged from 2 to 10 mm. The agent was sensitive to pronase and trypsin and resistant to heating at 60°C for 30 min.
Aims:1 This work was carried out to develop a rapid molecular profiling technique to screen ciliate populations in the rumen of sheep. Methods and Results: DGGE was used to study the ciliate diversity in the rumen of sheep. There was considerable variation between sheep which were co-housed, and fed the same diet. However, no difference in the major banding patterns was detected, when samples were collected from a single sheep sampled at different points. Following dietary changes, use of a pair-wise comparison of lanes, demonstrated that although there was still diversity between the ciliate population of sheep, the effects as a result of dietary changes were greater. Conclusions: The technique generated molecular profiles which are sufficiently different to allow comparison between samples, and to permit molecular ecological studies on the rumen ciliate population. Significance and Impact of the Study: The outcome of this study means that ciliate diversity in the rumen may now be studied by those unfamiliar with morphological identification of these organisms.
The diversity of methanogenic archaea associated with different species of ciliated protozoa in the rumen was analysed. Partial fragments of archaeal SSU rRNA genes were amplified from DNA isolated from single cells from the rumen protozoal species Metadinium medium, Entodinium furca, Ophryoscolex caudatus and Diplodinium dentatum. Sequence analysis of these fragments indicated that although all of the new isolates clustered with sequences previously described for methanogens, there was a difference in the relative distribution of sequences detected here as compared to that of previous work. In addition, many of the novel sequences, although clearly of archaeal origin have relatively low identity to the sequences in database which are most closely related to them.
To date, various G-quadruplex structures have been reported in human telomeric sequences. Human telomeric repeats can form many topological structures depending on conditions and on base modification; parallel, antiparallel, and hybrid forms. The effect of salts and some specific ligands on conformational switches between different conformers is known, but the influence of protruding sequences has rarely been discussed. In this paper, we analyze different quadruplex-forming oligomers derived from human telomeric sequences which contain 3′- and 5′-protruding nucleotides, not usually associated with the G-quadruplex motif. The study was performed using electrophoresis, CD, and UV spectroscopies. The major findings are (i) protruding nucleotides destabilize the G-quadruplex structure, and (ii) overhanging sequences influence the folding of the quadruplex.
Aims: Purification and partial characterization of an extracellular bacteriocin produced by the ruminal isolate Enterococcus faecalis II/1 and determine the frequency of occurrence of enterolysin A structural gene within the ruminal cocci.
Methods and Results: Bacteriocin produced by E. faecalis II/1 was purified to homogeneity. Purified bacteriocin exhibited a single band on sodium dodecylsulphate polyacrylamide gel electrophoresis with an apparent molecular weight of about 35 kDa. The amino acid sequence of the first 30 amino acids of purified bacteriocin was identical with the enterolysin A sequence. The DNA sequence of the nearly complete E. faecalis II/1 bacteriocin structural gene was identical to the enterolysin A gene sequence, confirming that this bacteriocin is identical to enterolysin A, a cell wall‐degrading bacteriocin from E. faecalis LMG 2333. Enterolysin A structural genes were detected in approximately one‐sixth of the Gram‐positive ruminal cocci examined by PCR using primers targeting the enterolysin A structural gene.
Conclusions: Bacteriocin produced by E. faecalis II/1 is identical to enterolysin A. Enterolysin A structural gene homologues are frequently encountered in rumen enterococcal and streptococcal bacterial strains.
Significance and Impact of the study: This is the first evidence of a large heat‐labile bacteriocin produced by rumen E. faecalis strain, enlarging the number and types of known anti‐bacterial proteins produced by rumen bacteria.
Substantial percentage of world food production depends on pollinating service of honeybees that directly depends on their health status. Among other factors, the success of bee colonies depends on health of developed larvae. The crucial phase of larval development is the first 6 days after hatching when a worker larva grows exponentially and larvae are potentially exposed to xenobiotics via diet. In the present study, we determined the lethal concentration LC (72 h) following single dietary exposure of honeybee larvae to formetanate under laboratory conditions, being also the first report available in scientific literature. Activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) were also measured in the homogenates of in vitro reared honeybee larvae after single formetanate exposure. Decreased specific activity of SOD and increased activities of CAT and GST suggest the induction of oxidative stress. Higher levels of thiobarbituric reactive species in all samples supported this fact. Comparing determined larval toxicity (LC of 206.01 mg a.i./kg diet) with adult toxicity data, we can suppose that the larvae may be less sensitive to formetanate than the adult bees.
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