Addition Of Lincomycin Research Articles

The impact of antibiotic residues on resistance patterns in leek at harvest

When crops are cultivated on fields fertilized with animal manure, the risk exists that plants may take up antibiotic residues and may be exposed to antibiotic resistance genes and antibiotic resistant bacteria. During cultivation in a greenhouse pot experiment, leek (Allium porrum) was fertilized with either pig slurry or mineral fertilizer and exposed to either no antibiotics, doxycycline (10,000 μg/kg manure), sulfadiazine (1000 μg/kg manure), or lincomycin (1000 μg/kg manure). At harvest, 4.5 months later, lincomycin, sulfadiazine or doxycycline were not detected in any of the leek samples nor in their corresponding soil samples. Further, antimicrobial susceptibility testing was performed on 181 Bacillus cereus group isolates and 52 Pseudomonas aeruginosa isolates from the grown leek. For the B. cereus group isolates, only a small shift in MIC50 for lincomycin was observed among isolates from the lincomycin and control treatment. For P. aeruginosa, only in the setup with doxycycline treatment a higher MIC50 for doxycycline was observed compared to the control, specifically the isolates selected from growth media supplemented with 8 mg/L doxycycline. Nine antibiotic resistance genes (tet(B), tet(L), tet(M), tet(O), tet(Q), tet(W), erm(B), erm(F) and sul2) were investigated at harvest in the leek and soil samples. In the leek samples, none of the antibiotic resistance genes were detected. In the soil samples fertilized with pig slurry, the genes erm(B), erm(F), tet(M), sul2, tet(W) and tet(O) were detected in significantly higher copy numbers in the lincomycin treatment as compared to the other antibiotic treatments. This could be due to a shift in soil microbiota induced by the addition of lincomycin. The results of this study indicate that consumption of leek carries a low risk of exposure to antibiotic residues or antibiotic resistance to doxycycline, sulfadiazine or lincomycin.

Reduced turnover of the D1 polypeptide and photoactivation of electron transfer in novel herbicide resistant mutants of Synechocystis sp. PCC 6803.

Two missense mutants, A263P and S264P, and a deletion mutant des-Ala263, Ser264, have been constructed in the D1 protein of the cyanobacterium Synechocystis sp PCC 6803. All were expected to induce a significant conformational change in the QB-binding region of photosystem II (PSII). Although the des-Ala263, Ser264-D1 mutant accumulated some D1 protein in the thylakoid membrane it was unable to grow photoautotrophically or evolve oxygen. Thermoluminescence and chlorophyll fluorescence studies confirmed that this deletion mutant did not show any functional PSII activity. In contrast, [S264P]D1 was able to grow photoautotrophically and give light-saturated rates of oxygen evolution at 60% of the rate of the wild-type control strain, TC31. The A263P missense mutant was also able to evolve oxygen at 50% of TC31 rates although it did not readily grow photoautotrophically. Thermoluminescence, flash oxygen yield and chlorophyll fluorescence measurements indicated that in both missense mutants electron transfer from QA to QB was significantly impaired in dark adapted cells. However, QA to QB electron transfer could be photoactivated in the mutants by background illumination. Both the A263P and S264P mutants also showed an increase in resistance to the s-triazine family of herbicides although this feature did not hold for the phenolic herbicide, ioxynil. Of particular interest was that the two missense mutants, especially S264P, possessed a slower rate of turnover of the D1 protein compared with TC31 and in vivo contained detectable levels of a 41-kDa adduct consisting of D1 and the alpha subunit of cytochrome b559. When protein synthesis was blocked by the addition of lincomycin, D1 degradation was again slower in S264P than TC31. The results are discussed in terms of structural changes in the QB-binding region which affect herbicide and plastoquinone binding and perturb the normal regulatory factors that control the degradation of the D1 protein and its synchronisation with the synthesis of a replacement D1 protein.

Isolation of mycoplasmas from bovine semen in Northern Ireland.

In a survey of 332 fresh and 137 processed bovine semen samples and 25 preputial washes, mycoplasmas and, or, ureaplasmas were isolated from 46 per cent, 31 per cent and 80 per cent, respectively. Intermittent isolation from different semen collections from the same bull indicated that at least three collections per bull were necessary to determine whether infection was present. When stored processed samples were examined Mycoplasma canadense and M bovigenitalium were isolated from straws taken as long ago as 1975. Addition of lincomycin and spectinomycin to the semen extender eliminated the isolation of mycoplasmas and reduced the rate of isolation of ureaplasmas.

A Differential Response in Turkey Poults to Various Antibiotics in Diets Designed to be Deficient or Adequate in Certain Essential Nutrients

Two experiments, each consisting of two trials, were conducted with day-old Nicholas Large White turkey poults to compare the effectiveness of four antibiotics for growth promotion and the utilization of sulfur amino acids. A corn-soybean meal basal diet that contained no supplemental methionine, choline, or inorganic sulfate was used in order to furnish nutritional stress. The diet was calculated to contain 25.4% protein, .448% methionine, .403% cystine, 1014 mg/kg choline, and 2990 kcal metabolizable energy/kg. In Experiment 1, a 2 × 4 factorial arrangement of treatments was used. This included two levels, (0% (control) and .18%), of supplemental DL-methionine and no antibiotic or bacitracin MD, flavomycin, or virginiamycin; antibiotics were fed at 50, 2, and 20 g/ton, respectively. In Experiment 2, lincomycin also was included as a treatment (at 4 g per ton) resulting in a 2 × 5 factorial arrangement of treatments.Only the addition of Virginiamycin to the control diet in Experiment 1 resulted in significantly increased body weights. Supplementation by .18% methionine increased body weights and feed efficiency. In addition, all three antibiotics increased body weights significantly when added to the .18% methionine diets. Feed efficiency values were improved by all four antibiotics at both methionine levels. In Experiment 2, increases in body weights similar to those in Experiment 1 were obtained with the addition of .18% methionine to the basal diets. Addition of lincomycin and virginiamycin improved body weights and feed efficiencies in the presence and absence of supplemental methionine.

EFFECTS OF SALINOMYCIN AND LINCOMYCIN UPON PERFORMANCE, MORTALITY AND INTESTINAL LESION SCORE IN BROILER CHICKENS USING AN IN-FEED COCCIDIA MODEL

A floor pen trial using an in-feed coccidia model was conducted to determine the efficacy of salinomycin at the rate of 60 mg/kg of feed and to ascertain any interference of lincomycin at 2.2 mg/kg upon salinomycin efficacy in broiler chickens. Inclusion of salinomycin effectively controlled mortality due to coccidiosis (P < 0.05), and improved mean intestinal lesion score and performance (P < 0.05). Addition of lincomycin to the diet did not interfere with the coccidiostatic properties of salinomycin. Key words: Broiler chickens, coccidiosis, salinomycin, lincomycin

Effect of Drug Additives and Type of Diet on Methionine Requirement of Chicks for Growth and Feed Efficiency

Three short-term (2 week) experiments were conducted with broiler type chicks to determine the effect of monensin, lasalocid, and lincomycin on growth and feed efficiency responses in chicks to graded levels of methionine. Lasalocid and monensin were added at levels of 125 and 121 ppm, respectively. These levels are at the upper level of the range permitted for use in poultry feeds. In one of these experiments, two different types of diets (corn-soy and pea-corn) were used which differed primarily in the source of protein. Both types of diets, on a calculated basis, were deficient in methionine and total sulfur amino acids. The addition of lasalocid to the diet that was most deficient in methionine had a methionine sparing effect. Addition of monensin to both types of diets depressed growth and feed efficiency in most of the comparisons where it was used. Some of the differences were not statistically significant. Addition of lincomycin at a level of 2 ppm gave a marked growth response when added to the diet without a coccidiostat and to the one containing lasalocid. The response in the presence of monensin was greatly reduced. In two experiments out of three, growth plateaued at a level of .1% added methionine in the presence of monensin and at a level of .2% added methionine in the presence of lasalocid. In the third experiment, growth plateaued at the .2% level added methionine for diets containing no coccidiostat or monensin and lasalocid. The results indicate that a maximum response was not obtained to methionine because of the growth depressing effect of monensin. On an overall basis, lincomycin improved feed efficiency and the improvement was more striking in the presence of lasalocid than in the presence of monensin. No improvement was obtained in the latter comparison.

Periodic variations in the ratio of free to thylakoid-bound chloroplast ribosomes during the cell cycle of Chlamydomonas reinhardtii.

The ratio of free to thylakoid-bound chloroplast ribosomes in Chlamydomonas reinhardtii undergoes periodic changes during the synchronous light-dark cycle. In the light, when there is an increase in the chlorophyll content and synthesis of thylakoid membrane proteins, about 20-30% of the chloroplast ribosomes are bound to the thylakoid membranes. On the other hand, only a few or no bound ribosomes are present in the dark when there is no increase in the chlorophyll content. The ribosome-membrane interaction depends not only on the developmental stage of the cell but also on light. Thus, bound ribosomes were converted to the free variety after cultures at 4 h in the light had been transferred to the dark for 10 min. Conversely, a larger number of chloroplast ribosomes became attached to the membranes after cultures at 4 h in the dark had been illuminated for 10 min. Under normal conditions, when there was slow cooling of the cultures during cell harvesting, chloroplast polysomal runoff occurred in vivo leading to low levels of thylakoid-bound ribosomes. This polysomal runoff could be arrested by either rapid cooling of the cells or the addition of chloramphenicol or erythromycin. Each of these treatments prevented polypeptide chain elongation on chloroplast ribosomes and thus allowed the polyosomes to remain bound to the thylakoids. Addition of lincomycin, an inhibitor of chain initiation on 70S ribosomes, inhibited the assembly of polysome-thylakoid membrane complex in the light. These results support a model in which initiation of mRNA translation begins in the chloroplast stroma, and the polysome subsequently becomes attached to the thylakoid membrane. Upon natural chain termination, the chloroplast ribosomes are released from the membrane into the stroma.

Synthesis and translation site of light-induced mRNAs in etiolated Euglena gracilis

Poly(A)-mRNA synthesis has been studied in etiolated Euglena gracilis exposed to 1 or 2 h of illumination. 1. 1. Labeling kinetics of mRNAs containing poly(A) sequences, during illumination or after return to darkness, reach a plateau in 10 or 20 min according to nutritional conditions. When the cultures are returned to darkness, the mRNA synthesis decreases rapidly. Thus, the synthesis of these mRNAs (light-induced mRNAs) is dependent on light and their half-life can be evaluated. 2. 2. Cycloheximide induces accumulation of label in poly(A)-containing mRNA; such an accumulation is not observed after addition of lincomycin. Labeling during illumination of mRNA in a chloroplast mutant is similar to that in the wild type strain. These data suggest that the poly(A)-mRNAs synthesized in the two first hours of illumination are translated on cytoplasmic polyribosomes.

Dark starvation and plant metabolism

The fixation pattern of radioactive labelled photosynthetic intermediates was followed under steady state conditions during prolonged dark starvation of spinach plants (Spinacia oleracea L.). It is suggested that the considerable increase of radioactive dihydroxyacetonephosphate is correlated with a specific leakage of the outer chloroplast envelope induced by dark starvation. The primary fixation product, phosphoglyceric acid, followed the same decreasing tendency as observed for the net CO2 fixation. In contrast, the relative label in other intermediates is the same as in the controls. When after several days of dark starvation the plants were again transferred into light, a regeneration of the CO2 fixation accompanied by the appearance of a normal fixation pattern was observed. Since the regeneration was prevented by the addition of lincomycin, the net increase is considered to be due to a new protein synthesis rather than a reactivation.