Differential responses of nematode communities to soybean genotypes resistant and susceptible to Heterodera glycines race 3

Heterodera glycines and Helicotylenchus dihystera were the two most abundant plant-parasitic nematodes found in two H. glycines race 3-infested fields, Chapadão do Céu, MS and Campo Alegre, MG. These fields had been planted with resistant (R) and susceptible (S) plants to cyst nematodes. In the first field, soybean (Glycine max) FT-Cristalina (S) was susceptible to H. glycines but resistant to H. dihystera, while GOBR93 122243 (R) was just the opposite. In the second field, M-Soy 8400 (R) was more resistant to the spiral nematode than M-Soy8411 (S), but the resistance to the cyst nematode was not different between the two genotypes. The total abundance of nematodes was not different between the susceptible and resistant plants in the two fields, suggesting that H. dihystera and/or bacterial feeders and other trophic groups replaced the reduced abundance of the cyst nematodes in resistant plants. Bacterial feeders acted as a compensatory factor to plant-parasitic nematodes in ecological function. The populations of fungal feeders were higher in GOBR93 122243 (R) than in susceptible FT-Cristalina (S) in Chapadão do Céu, but lower in M-Soy 8400 (R) than in M-Soy 8411 (S) in Campo Alegre. This is being attributed to the different periods of soil samplings that were made at the florescent period in the first field, and at the final growing cycle in the second field. Only four nematodes, H. glycines, H. dihystera, Acrobeles sp. and Panagrolaimus sp. dominated the nematode resistant community GOBR93 122243 (R) in Chapadão do Céu, but dominance was shared by ten genera in Campo Alegre, which explains why the five diversity indexes (S, d, Ds, H' and T) were higher in resistant plants than in susceptible plants in field two.

Evaluation of genetic mixtures of sorghum lines for anthracnose resistance management

The main objective of this work was to evaluate the diversification of sorghum (Sorghum bicolor) populations as a way to manage resistance to the sorghum anthracnose fungus Colletotrichum graminicola. A total of 18 three-way hybrids were obtained by crossing six single cross male-sterile F1 hybrids, derived by crossing A (non restorer sterile cytoplasm) and B (non restorer normal cytoplasm) lines, with three fertile R (restorer) lines, previously evaluated for their differential reaction to the pathogen. Variation in the level of resistance was observed, as indicated by the values of the area under the disease progress curve (AUDPC) obtained for each hybrid. Lines contributed differently to the level of resistance of each hybrid. All hybrids in which CMSXS169R was the male progenitor were classified as highly resistant. Some hybrids had a level of resistance superior to the maximum levels of each line component individually.

Natural variability in Arabidopsis thaliana germplasm response to Xanthomonas campestris pv. campestris

This work aimed to study the interaction between the model plant Arabidopsis thaliana and Xanthomonas campestris pv. campestris (Xcc), the pathogen responsible for black rot of crucifers. The response of 32 accessions of A. thaliana to the Brazilian isolate of Xcc CNPH 17 was evaluated. No immunity-like response was observed. "CS1308", "CS1566" and "CS1643" grown in continuous light were among the accessions that showed strongest resistance when inoculated with 5 x 10(6) CFU/mL. In contrast, "CS1194" and "CS1492" were among the most susceptible accessions. Similar results were obtained when plants were grown under short-day conditions. To quantify the differences in disease symptoms, total chlorophyll was extracted from contrasting accessions at different time points after inoculation. Chlorophyll levels from controls and Xcc inoculated plants showed a similar reduction in resistant accessions, whereas Xcc-inoculated susceptible accessions showed a greater reduction compared to controls. To test the specificity of resistance, accessions CS1308, CS1566, CS1643 and CS1438 (which showed partial resistance to CNPH 17), were inoculated with a more aggressive isolate of Xcc (CNPH 77) and Ralstonia solanacearum. Among the accessions tested, "CS1566" was the most resistant to Xcc CNPH 77 and also displayed resistance to R. solanacearum. Accessions CS1308, CS1566 and CS1643 were also inoculated with a high titer of Xcc CNPH 17 (5 x 10(8) CFU/mL). No collapse of tissue was observed up to 48 h after inoculation, indicating that a hypersensitive response is not involved in the resistance displayed by these accessions.

Antimicrobial Resistance in Campylobacter jejuni and Campylobacter coli

Antimicrobial Resistance in Campylobacter jejuni and Campylobacter coli Campylobacters are a common cause of bacterial gastroenteritis worldwide, with Campylobacter jejuni and C. coli being the most common species isolated in human infections. If antimicrobial treatment is required, the drugs of choice at the moment are the macrolides and fluoroquinolones. In this thesis, the in vitro resistance profiles of the C. jejuni and C. coli strains were evaluated with emphasis on multidrug resistance. The aim was also to evaluate the different resistance mechanisms against the macrolides. Further, the disk diffusion method was compared to agar dilution method and its repeatability was evaluated, since it has been widely used for the susceptibility testing of campylobacters. The results of the present study showed that resistance to the fluoroquinolones is common in strains isolated from Finnish patients, but resistance to the macrolides is still rare. Multidrug resistance was associated with resistance to both ciprofloxacin and erythromycin. Among the available per oral drugs, least resistance was observed to coamoxiclav There was no resistance to the carbapenems. Sitafloxacin and tigecycline were in vitro highly effective towards Campylobacter species. A point mutation A2059G of the 23S rRNA gene was the main mechanism behind the macrolide resistance, whereas the efflux pumps did not seem to play an important role when a strain had A2059G mutation. A five amino acids insertion, which has not been described previously, in the ribosomal protein L22 of one highly-resistant C. jejuni strain without mutation in the 23S rRNA gene was also detected. Concerning the disk diffusion method, there was variation in the repeatability In conclusion, macrolides still appear to be the first-choice alternative for suspected Campylobacter enteritis. The in vitro susceptibilities found suggest that co-amoxiclav might be a candidate for clinical trials on campylobacteriosis, but in life-threatening situations, a carbapenem may be the drug of choice. More studies are needed on whether the disk diffusion test method could be improved or whether all susceptibilities of campylobacters should be done using a MIC based method.

Oxisol resistence to penetration in no-till system after sowing

If inappropriately conducted, management and sowing practices may compromise the environment and the profitability of the agricultural activity. The aim of this study was to analyze the furrow opener mechanisms action and the level of load applied to soil firming mechanism in no-till, on the Oxisol resistance to penetration during soybean sowing, under three soil moistures. The experiment was arranged in split-split plot design, in which the plots were composed by three soil moistures (23.8; 25.5 and 27.5% b.s.), two furrow opener mechanisms sub-plots (double disks and furrow plough) and the split-split plot of three levels of load applied to soil firming mechanism (12.2; 18.5 and 24.1 kPa), according to randomized blocks design, with three replications. The soil moisture provided different resistance behavior to penetration with the depth, on the seedbed, independently of the furrow opener and the level of load applied to soil firming mechanism. The furrow plough use provided less soil resistance to penetration when compared to the double disk furrow opener, on the seedbed, independently of the soil moisture and the level of load applied to soil firming mechanism. The pressure applied by soil firming mechanism of 18.5 kPa provided the lower resistance to penetration, when the furrow plough was used. The soil resistance to penetration was less on the sowing line than on between rows, with 20 cm deep.

Searching for keys to successful post-merger integration : a longitudinal case-study following a public sector merger

Unsuccessful mergers are unfortunately the rule rather than the exception. Therefore it is necessary to gain an enhanced understanding of mergers and post-merger integrations (PMI) as well as learning more about how mergers and PMIs of information systems (IS) and people can be facilitated. Studies on PMI of IS are scarce and public sector mergers are even less studied. There is nothing however to indicate that public sector mergers are any more successful than those in the private sector. This thesis covers five studies carried out between 2008 and 2011 in two organizations in higher education that merged in January 2010. The most recent study was carried out two years after the new university was established. The longitudinal case-study focused on the administrators and their opinions of the IS, the work situation and the merger in general. These issues were investigated before, during and after the merger. Both surveys and interviews were used to collect data, to which were added documents that both describe and guide the merger process; in this way we aimed at a triangulation of findings. Administrators were chosen as the focus of the study since public organizations are highly dependent on this staff category, forming the backbone of the organization and whose performance is a key success factor for the organization. Reliable and effective IS are also critical for maintaining a functional and effective organization, and this makes administrators highly dependent on their organizations’ IS for the ability to carry out their duties as intended. The case-study has confirmed the administrators’ dependency on IS that work well. A merger is likely to lead to changes in the IS and the routines associated with the administrators’ work. Hence it was especially interesting to study how the administrators viewed the merger and its consequences for IS and the work situation. The overall research objective is to find key issues for successful mergers and PMIs. The first explorative study in 2008 showed that the administrators were confident of their skills and knowledge of IS and had no fear of having to learn new IS due to the merger. Most administrators had an academic background and were not anxious about whether IS training would be given or not. Before the merger the administrators were positive and enthusiastic towards the merger and also to the changes that they expected. The studies carried out before the merger showed that these administrators were very satisfied with the information provided about the merger. This information was disseminated through various channels and even negative information and postponed decisions were quickly distributed. The study conflicts with the theories that have found that resistance to change is inevitable in a merger. Shortly after the merger the (third) study showed disappointment with the fact that fewer changes than expected had been implemented even if the changes that actually were carried out sometimes led to a more problematic work situation. This was seen to be more prominent for routine changes than IS changes. Still the administrators showed a clear willingness to change and to share their knowledge with new colleagues. This knowledge sharing (also tacit) worked well in the merger and the PMI. The majority reported that the most common way to learn to use new ISs and to apply new routines was by asking help from colleagues. They also needed to take responsibility for their own training and development. Five months after the merger (the fourth study) the administrators had become worried about the changes in communication strategy that had been implemented in the new university. This was perceived as being more anonymous. Furthermore, it was harder to get to know what was happening and to contact the new decision makers. The administrators found that decisions, and the authority to make decisions, had been moved to a higher administrative level than they were accustomed to. A directive management style is recommended in mergers in order to achieve a quick transition without distracting from the core business. A merger process may be tiresome and require considerable effort from the participants. In addition, not everyone can make their voice heard during a merger and consensus is not possible in every question. It is important to find out what is best for the new organization instead of simply claiming that the tried and tested methods of doing things should be implemented. A major problem turned out to be the lack of management continuity during the merger process. Especially problematic was the situation in the IS-department with many substitute managers during the whole merger process (even after the merger was carried out). This meant that no one was in charge of IS-issues and the PMI of IS. Moreover, the top managers were appointed very late in the process; in some cases after the merger was carried out. This led to missed opportunities for building trust and management credibility was heavily affected. The administrators felt neglected and that their competences and knowledge no longer counted. This, together with a reduced and altered information flow, led to rumours and distrust. Before the merger the administrators were convinced that their achievements contributed value to their organizations and that they worked effectively. After the merger they were less sure of their value contribution and effectiveness even if these factors were not totally discounted. The fifth study in November 2011 found that the administrators were still satisfied with their IS as they had been throughout the whole study. Furthermore, they believed that the IS department had done a good job despite challenging circumstances. Both the former organizations lacked IS strategies, which badly affected the IS strategizing during the merger and the PMI. IS strategies deal with issues like system ownership; namely who should pay and who is responsible for maintenance and system development, for organizing system training for new IS, and for effectively run IS even during changing circumstances (e.g. more users). A proactive approach is recommended for IS strategizing to work. This is particularly true during a merger and PMI for handling issues about what ISs should be adopted and implemented in the new organization, issues of integration and reengineering of IS-related processes. In the new university an ITstrategy had still not been decided 26 months after the new university was established. The study shows the importance of the decisive management of IS in a merger requiring that IS issues are addressed in the merger process and that IS decisions are made early. Moreover, the new management needs to be appointed early in order to work actively with the IS-strategizing. It is also necessary to build trust and to plan and make decisions about integration of IS and people.

Effect of multidrug resistance modulators on the activity of ivermectin and moxidectin against selected strains of Haemonchus contortus infective larvae

Nematode parasites have shown resistance to the anthelmintics, ivermectin and moxidectin, and there is evidence that the over-expression of parasite P-glycoprotein (P-gp) may account, at least in part, for resistance to ivermectin. The objective of this study was to evaluate whether the multidrug resistance (MDR) modulators, verapamil, CL 347.099 (an analog of verapamil) and cyclosporin A, would enhance the efficacy of ivermectin and moxidectin against selected strains of Haemonchus contortus using an in vitro larval migration assay. The modulators had no effects on the number of migrating larvae when used alone. Ivermectin and moxidectin showed a significant (P<0.05) increase in its efficacy by 52.8 and 58.5% respectively, when used in association with verapamil against a moxidectin-selected strain. CL 347,099 also increased significantly (P<0.05) the ivermectin and moxidectin efficacy by 24.2 and 40.0% respectively, against an ivermectin-selected strain and by 40.0 and 75.6% respectively, against an moxidectin-selected strain. At the concentrations tested cyclosporin A showed a variable effect on increasing the efficacy of the anthelmintics against the susceptible and resistant strains.

Weak phenotypic reversion of ivermectin resistance in a field resistant isolate of Haemonchus contortus by verapamil

Recent advances in anthelmintic resistant phenotype reversion by Pgp modulating drugs in ruminant nematodes indicate that this can be a useful tool to helminth control. The aim of the present study was to evaluate the efficacy of ivermectin (IVM) in combination with verapamil (VRP), in oil or water-based vehicle, against an IVM-resistant field isolate of Haemonchus contortus through a larval migration assay and experimental infection trial. In the in vitro assay was observed a phenotypic reversion of H. contortus resistance to ivermectin at a high concentration of VRP, increasing IVM efficacy from 53.1% to 94.3. In the in vivo trial, IVM + VRP demonstrated 36.02% efficacy compared to the 7.75% of IVM alone. The vehicle formulation showed no influence in efficacy. These are the first results demonstrating the effect of VRP as a partial IVM-resistance phenotype reverser in a field isolate of IVM-resistant H. contortus experimentally inoculated in sheep.

Antimicrobial resistance of Staphylococcus spp. from small ruminant mastitis in Brazil

The study aimed to determine the antimicrobial resistance patterns and to identify molecular resistance markers in Staphylococcus spp. (n=210) isolated from small ruminant mastitis in Brazil. The antimicrobial resistance patterns were evaluated by the disk diffusion test and by detection of the presence of mecA, blaZ, ermA, ermB, ermC and msrA genes by PCR. The efflux pump test was performed using ethidium bromide and biofilm production was determined by Congo red agar test along with PCR for detection of the icaD gene. The isolates were most resistant to amoxicillin (50.0%), streptomycin (42.8%), tetracycline (40.4%), lincomycin (39.0%) and erythromycin (33.8%). Pan-susceptibility to all tested drugs was observed in 71 (33.8%) isolates and 41 Staphylococcus isolates were positive for the efflux pump. Although phenotypic resistance to oxacillin was observed in 12.8% of the isolates, none harbored the mecA gene. However, 45.7% of the isolates harbored blaZ indicating that beta-lactamase production was the main mechanism associated with staphylococci resistance to beta-lactams in the present study. The other determinants of resistance to antimicrobial agents ermA, ermB, ermC, and msrA were observed in 1.4%, 10.4%, 16.2%, and 0.9% of the isolates, respectively. In addition, the icaD gen was detected in 32.9% of the isolates. Seventy three isolates (54 from goats and 19 from sheep) were negative for all resistance genes tested and 69 isolates presented two or more resistance genes. Association among blaZ, ermA, ermB, ermC and efflux pump were observed in 17 isolates, 14 of which originated from goats and three from sheep. The data obtained in this study show the resistance of the isolates to beta-lactamics, which may be associated with the use of antimicrobial drugs without veterinary control.

Expression of P-glycoprotein, multidrug resistance-associated protein, glutathione-S-transferase pi and p53 in canine transmissible venereal tumor

The overexpression of proteins P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP1), mutant p53, and the enzyme glutathione-S-transferase (GSTpi) are related to resistance to chemotherapy in neoplasms. This study evaluated the expression of these markers by immunohistochemistry in two groups of canine TVT, without history of prior chemotherapy (TVT1, n=9) and in TVTs presented unsatisfactory clinical response to vincristine sulfate (TVT2, n=5). The percentage of specimens positively stained for P-gp, MRP1, GSTpi and p53 were, respectively 88.8%, 0%, 44.5% and 22.2% in TVT1 and 80%, 0%, 80% and 0% in TVT2. In TVT1, one specimen presented positive expression for three markers and four specimens for two markers. In TVT2, three specimens expressed P-gp and GSTpi. In conclusion, the canine TVTs studied expressed the four markers evaluated, but just P-gp and GSTpi were significantly expressed, mainly at cytoplasm and cytoplasm and nuclei, respectively, either before chemotherapy as after vincristine sulfate exposure. Future studies are needed to demonstrate the function of these two markers in conferring multidrug resistance (MDR) or predict the response to chemotherapy in canine TVT.

A Modified phosphate-carrier protein theory is proposed as a non-target site mechanism For glyphosate resistance in weeds

Glyphosate is an herbicide that inhibits the enzyme 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPs) (EC 2.5.1.19). EPSPs is the sixth enzyme of the shikimate pathway, by which plants synthesize the aromatic amino acids phenylalanine, tyrosine, and tryptophan and many compounds used in secondary metabolism pathways. About fifteen years ago it was hypothesized that it was unlikely weeds would evolve resistance to this herbicide because of the limited degree of glyphosate metabolism observed in plants, the low resistance level attained to EPSPs gene overexpression, and because of the lower fitness in plants with an altered EPSPs enzyme. However, today 20 weed species have been described with glyphosate resistant biotypes that are found in all five continents of the world and exploit several different resistant mechanisms. The survival and adaptation of these glyphosate resistant weeds are related toresistance mechanisms that occur in plants selected through the intense selection pressure from repeated and exclusive use of glyphosate as the only control measure. In this paper the physiological, biochemical, and genetic basis of glyphosate resistance mechanisms in weed species are reviewed and a novel and innovative theory that integrates all the mechanisms of non-target site glyphosate resistance in plants is presented.

Eletrolite leakage as a technique to diagnose euphorbia heterophylla biotypes resistant to ppo-inhibitors herbicides

The action of herbicides that affect the integrity of cell membranes and cause leakage, like PPO-inhibitors, can be detected by measuring the electric conductivity (EC) of a solution in which the plant tissue target is incubated in the presence of herbicide. The objectives of this work were to confirm PPO resistance in a new Euphorbia heterophylla (EPHHL) biotype, and to compare the electrolyte leakage from R and S to PPO-inhibitors biotypes, using two different methods of incubation in a solution containing herbicides. One experiment was carried in greenhouse and three in laboratory, with a completely randomized design. In the greenhouse experiment, four biotypes of EPHHL were sprayed with seven rates of fomesafen to confirm resistance in suspected biotypes. Leaf disks from R and S EPHHL biotypes in the second and the third experiments and entire leaves in the fourth experiment were incubated in a solution containing PPO-inhibitors to subsequently determine EC of solution. The study confirmed the resistance to PPO-inhibitors in two EPHHL biotypes. There were no significant differences between S and R biotypes in the experiments with the incubation of leaf disks, but incubation of entire leaves of EPHHL S biotype showed higher EC when in a solution with fomesafen, in comparison to the R biotype. The results of this work are an indirect evidence that resistance to PPO-inhibitors is related to lower absorption of herbicide by the shoots and also to some kind of mechanism to cope with oxidative stress.

Limited occurrence of resistant radish (Raphanus sativus) to AHAS-inhibiting herbicides in Argentina

Radish has developed feral and weedy biotypes, which is a concern for agriculture around the world. In Argentina, it is one of the most widespread and troublesome crop weeds. In Brazil, this species has developed herbicide-resistance to acetohydroxyacid synthase (AHAS) inhibiting herbicides. The objective of this study was to record the presence of herbicide-resistant weedy radish plants in Argentina. In spring 2008, we found a small population of radish at the end of the flowering stage in an imidazolinone-tolerant canola field treated with imazethapyr. Screening and dose-response tests were conducted to two successive generations. They proved the biotype resistant status, and showed extensive survival (between 50 and 80% of control) to the application of a double dose of four AHAS‑inhibiting herbicides from two different chemical families (imidazolinones and sulfonylureas). Dose-response assays exhibited very high resistance for imazethapyr (LD50 = 2452.5 g a.i. ha-1, GR50 = 2926.9 g a.i. ha-1) and intermediate for metsulfuron (LD50 = 3.0 g a.i. ha-1, GR50 = 43.2 g a.i. ha-1). The acquisition of cross-resistance to different herbicide families would confer an adaptive and invasive advantage in agricultural environments to this biotype. Due to the herbicide rotation conducted in the field, the dispersion of this biotype was restricted. This is the first report of resistance in weedy radish in Argentina.

Acetolactate synthase activity in Euphorbia heterophylla resistant to ALS- and protox- inhibiting herbicides

The objective of this study was to determine the activity of the enzyme acetolactate synthase in biotypes of wild poinsettia (Euphorbia heterophylla) with multiple resistance to ALS- and Protox- inhibitors in the presence and absence of imazapyr, imazethapyr and nicosulfuron. We conducted in vitro assay of ALS enzyme extracted from plants of Vitorino, Bom Sucesso do Sul and Medianeira biotypes (with multiple resistance) and a susceptible population in the absence and presence of imazapyr, imazethapyr and nicosulfuron. In the absence of herbicides, biotypes with multiple resistance showed higher affinity for the substrate of the enzyme compared with the susceptible population. The herbicides imazapyr, imazethapyr and nicosulfuron had little effect on the enzyme activity of ALS-resistant biotypes and, conversely, high inhibitory effect on ALS of the susceptible population. Resistance factors were very high, greater than 438, 963 and 474 for Vitorino, Bom Sucesso do Sul and Medianeira biotypes, respectively. The resistance to ALS inhibitors is due to the insensitivity of ALS to herbicides of both imidazolinone and sulfonylurea groups, characterizing a cross-resistance.

Resistence of Radish Biotypes to Iodosulfuron and Alternative Control

The repetitive use of iodosulfuron for the control of weeds in winter cereals in the south of Brazil has favored the emergence of resistant Raphanus sativus biotypes. The objective of this study was to evaluate: the response of Raphanus sativus biotypes susceptible and resistant to different dosages of iodosulfuron; the control of biotypes with alternative registered herbicides for the control of the species in crops of wheat, corn and soybean; and the existence of cross-resistance of the biotypes. Thus, four experiments were done in a greenhouse, with a completely randomized design and four replicates. The experimental units were composed of vases with a volumetric capacity of 0.75 L filled with substrate, containing a plant each. For the dose-response curve, three biotypes (factor A) and nine doses of the iodosulfuron herbicide (factor B) were used. For the alternative control, the recommendation was herbicides in pre or postemergence of the crops, and the crossed-resistance was evaluated by using herbicides that inhibit the ALS enzyme of different chemical groups. The analyzed variables were control and shoot dry matter. GR50 of the susceptible biotype (B1) was 0.11 g a.i. ha-1, whereas GR50 of resistant biotypes (B4 and B13) was 102.9 and 86.8 g a.i. ha-1 of the iodosulfuron herbicide, respectively. The resistant biotypes presented crossed resistance to herbicides that inhibit the ALS enzyme, where the control can be efficient with the use of herbicides with different action mechanisms.