Measurement of Trace Elements (Zinc, Copper, Magnesium, and Iron) in the Saliva of Horses: Validation Data and Changes in Equine Gastric Ulcer Syndrome (EGUS).

The objective of this study was to evaluate the possible use of spectrophotometric assays for the measurement of trace elements, including Zinc (Zn), Copper (Cu), Magnesium (Mg), and iron (Fe) in the saliva of horses and study their possible changes in equine gastric ulcer syndrome (EGUS). EGUS is a highly prevalent disease, with a current high incidence due to the increase in intensive management conditions. There are two EGUS diseases: equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD), which can appear individually or together. For this purpose, automated spectrophotometric assays for measuring these analytes in horse saliva were analytically validated. Then, these analytes were measured in the saliva of horses with only ESGD, only EGGD, both ESGD and EGGD and a group of healthy horses. The methods used to measure the analytes were precise and accurate. Horses diagnosed with EGGD presented significantly lower levels of Zn and Mg. Fe concentrations were significantly lower in the saliva of horses with ESGD and EGGD. Overall, these results indicate that there are changes in trace elements in saliva in EGUS that could reflect the physiopathological mechanisms involved in this process and open the possibility of using trace elements as biomarkers of this syndrome.

Dominance of African racial ancestry in honey bee colonies of Mexico 30 years after the migration of hybrids from South America.

The Africanized honey bee, a hybrid of Apis mellifera scutellata from Africa with European subspecies, has been considered an invasive species and a problem for beekeeping. Africanized bees arrived in Mexico in 1986, 30 years after their accidental release in Brazil. Although government programs were implemented for its eradication, Africanized populations persist in Mexico, but precise information on the patterns of genetic introgression and racial ancestry is scarce. We determined maternal and parental racial ancestry of managed and feral honey bees across the five beekeeping regions of Mexico, using mitochondrial (mtDNA, COI-COII intergenic region) and nuclear markers (94 ancestrally informative SNPs), to assess the relationship between beekeeping management, beekeeping region, altitude, and latitude with the distribution of maternal and parental racial ancestry. Results revealed a predominantly African ancestry in the Mexican honey bees, but the proportion varied according to management, beekeeping regions, and latitude. The Mexican honey bees showed 31 haplotypes of four evolutionary lineages (A, M, C, and O). Managed honey bees had mitochondrial and nuclear higher proportions of European ancestry than feral honey bees, which had a higher proportion of African ancestry. Beekeeping regions of lower latitudes had higher proportions of African nuclear ancestry. Managed and feral honey bees showed differences in the proportion of maternal and nuclear racial ancestry. Managed honey bees from the Yucatan Peninsula and feral honey bees had a higher mtDNA than nuclear proportions of African ancestry. Managed honey bees, except those on the Yucatan Peninsula, had a higher nuclear than mtDNA proportion of African ancestry. Our study demonstrates that Africanized honey bee populations are genetically diverse and well established in Mexico, which highlights the limitations of management and government programs to contain the Africanization process and demands the incorporation of this lineage in any breeding program for sustainable beekeeping.

Effects of floral resources on honey bee populations in Mexico: Using dietary metabarcoding to examine landscape quality in agroecosystems.

The decline of honey bee populations significantly impacts the human food supply due to poor pollination and yield decreases of essential crop species. Given the reduction of pollinators, research into critical landscape components, such as floral resource availability and land use change, might provide valuable information about the nutritional status and health of honey bee colonies. To address this issue, we examine the effects of landscape factors like agricultural area, urban area, and climatic factors, including maximum temperature, minimum temperature, relative humidity, and precipitation, on honey bee hive populations and nutritional health of 326 honey bee colonies across varying landscapes in Mexico. DNA metabarcoding facilitated the precise identification of pollen from 267 plant species, encompassing 243 genera and 80 families, revealing a primary herb-based diet. Areas characterized by high landscape diversity exhibited greater pollen diversity within the colony. Conversely, colonies situated in regions with higher proportions of agricultural and urban landscapes demonstrated lower bee density. The maximum ambient temperature outside hives positively correlated with pollen diversity, aligning with a simultaneous decrease in bee density. Conversely, higher relative humidity positively influenced both the bee density of the colony and the diversity of foraged pollen. Our national-level study investigated pollen dietary availability and colony size in different habitat types, latitudes, climatic conditions, and varied levels and types of disturbances. This effort was taken to gain a better insight into the mechanisms driving declines in honey bee populations. This study illustrates the need for more biodiverse agricultural landscapes, the preservation of diverse habitats, and the conservation of natural and semi-natural spaces. These measures can help to improve the habitat quality of other bee species, as well as restore essential ecosystem processes, such as pollination and pest control.

Effects of Phenylcapsaicin on Intraocular and Ocular Perfusion Pressure During a 30-Min Cycling Task: A Placebo-Controlled, Triple-Blind, Balanced Crossover Study.

The main objective of this placebo-controlled, triple-blind, balanced crossover study was to assess the acute effects of phenylcapsaicin (PC) intake (2.5 mg) on intraocular pressure (IOP), ocular perfusion pressure (OPP), and heart rate (HR) during a 30-min cycling task performed at 15% of the individual maximal power. Twenty-two healthy young adults performed the cycling task 45 min after ingesting PC or placebo. IOP was measured with a rebound tonometer before exercise, during cycling (every 6 min), and after 5 and 10 min of recovery. OPP was assessed before and after exercise. HR was monitored throughout the cycling task. We found an acute increase of IOP levels related to PC consumption while cycling (mean difference = 1.91 ± 2.24 mmHg; p = .007, ηp2=.30), whereas no differences were observed for OPP levels between the PC and placebo conditions (mean difference = 1.33 ± 8.70 mmHg; p = .608). Mean HR values were higher after PC in comparison with placebo intake (mean difference = 3.11 ± 15.87 bpm, p = .019, ηp2=.24), whereas maximum HR did not differ between both experimental conditions (p = .199). These findings suggest that PC intake before exercise should be avoided when reducing IOP levels is desired (e.g., glaucoma patients or those at risk). Future studies should determine the effects of different ergogenic aids on IOP and OPP levels with other exercise configurations and in the long term.

Unlocking Photocatalytic Activity of Acridinium Salts by Anion-Binding Co-Catalysis.

The in situ generation of active photoredox organic catalysts upon anion-binding co-catalysis by making use of the ionic nature of common photosensitizers is reported. Hence, the merge of anion-binding and photocatalysis permitted the modulation of the photocatalytic activity of simple acridinium halide salts, building an effective anion-binding - photoredox ion pair complex able to promote a variety of visible light driven transformations, such as anti-Markovnikov addition to olefins, Diels-Alder and the desilylative C-C bond forming reactions. Anion-binding studies, together with steady-state and time-resolved spectroscopy analysis, supported the postulated ion pair formation between the thiourea hydrogen-bond donor organocatalyst and the acridinium salt, which proved essential for unlocking the photocatalytic activity of the photosensitizer.

Nanofibrous ε-Polycaprolactone Matrices Containing Nano-Hydroxyapatite and Humulus lupulus L. Extract: Physicochemical and Biological Characterization for Oral Applications.

Oral bone defects occur as a result of trauma, cancer, infections, periodontal diseases, and caries. Autogenic and allogenic grafts are the gold standard used to treat and regenerate damaged or defective bone segments. However, these materials do not possess the antimicrobial properties necessary to inhibit the invasion of the numerous deleterious pathogens present in the oral microbiota. In the present study, poly(ε-caprolactone) (PCL), nano-hydroxyapatite (nHAp), and a commercial extract of Humulus lupulus L. (hops) were electrospun into polymeric matrices to assess their potential for drug delivery and bone regeneration. The fabricated matrices were analyzed using scanning electron microscopy (SEM), tensile analysis, thermogravimetric analysis (TGA), FTIR assay, and in vitro hydrolytic degradation. The antimicrobial properties were evaluated against the oral pathogens Streptococcus mutans, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans. The cytocompatibility was proved using the MTT assay. SEM analysis established the nanostructured matrices present in the three-dimensional interconnected network. The present research provides new information about the interaction of natural compounds with ceramic and polymeric biomaterials. The hop extract and other natural or synthetic medicinal agents can be effectively loaded into PCL fibers and have the potential to be used in oral applications.

Bridging personality dimensions and eating symptoms: A transdiagnostic network approach.

OBJECTIVE: Eating disorders (ED) have recently been studied from a network approach, conceptualising them as a complex system of interconnected variables, while highlighting the role of non-ED symptoms and personality dimensions. This study aims to explore the connections between personality and ED symptoms, identify central nodes, and compare the EDs network to a healthy control network. METHODS: We employed network analysis to examine the personality-ED symptom connections in 329 individuals with an ED diagnosis and 192 healthy controls. We estimated a regularised partial correlation network and the indices of centrality and bridge centrality to identify the most influential nodes for each group. Network differences between groups were also examined. RESULTS: Low Self-Directedness and high Harm avoidance emerged as central bridge nodes, displaying the strongest relationship with ED symptoms. Both networks differed in their global connectivity and structure, although no differences were found in bridge centrality and centrality indices. CONCLUSIONS: These findings shed light on the role of personality dimensions, such as Self-Directedness and Harm Avoidance in the maintenance of ED psychopathology, supporting the transdiagnostic conceptualisation of ED. This study advances a deeper understanding of the complex interplay between personality dimensions and ED symptoms, offering potential directions for clinical interventions.

Impact of squat set configuration on mechanical performance in paired sets of upper-body exercises.

BACKGROUND: Paired sets and alternative set configurations (e.g., cluster sets) are frequently employed by strength and conditioning practitioners; however, their synergistic impact remains underexplored in research. This study aimed to elucidate whether the set configuration used in a lower-body exercise affects mechanical performance during paired sets of upper-body exercises. METHODS: Twenty-one resistance-trained individuals (14 men and 7 women) randomly completed three experimental sessions that involved four sets of five repetitions at 75%1RM during both the bench press and bench pull exercises. The three experimental sessions varied solely in the activity conducted during the inter-set rest periods of each upper-body exercise: (i) Traditional squat - six squat repetitions without intra-set rest at 65%1RM; (ii) Rest redistribution squat - two clusters of three repetitions of the squat exercise at 65%1RM with 30 s of intra-set rest; and (iii) Passive rest - no exercise. RESULTS: The rest redistribution set configuration allowed the sets of the squat exercise to be performed at a faster velocity than the traditional set configuration (p = 0.037). However, none of the mechanical variables differed between the exercise protocols neither in the bench press (p ranged from 0.279 to 0.875) nor in the bench pull (p ranged from 0.166 to 0.478). CONCLUSIONS: Although rest redistribution is an effective strategy to alleviate fatigue during the sets in which it is implemented, it does not allow subjects to perform better in subsequent sets of the training session.

Physical manifestations of stress in women. Correlations between temporomandibular and pelvic floor disorders.

INTRODUCTION: Stress is characterized as a challenging occurrence that triggers a physiological and/or behavioral allostatic response, alongside the demands typically encountered throughout the natural course of life. A sustained state of stress gives rise to secondary effects, including insomnia and neck pain. Also, the risk of musculoskeletal problems in the cervical and lumbar spine can be increased due to a sustained state of stress. The present study main objective is to study the association between orofacial and pelvic floor muscles in women in Spain. METHODOLOGY: An observational, cross-sectional, retrospective analytical study was designed and carried out in the laboratories of the European University of Madrid. Sixty-five participants were recruited with a mean age of 29.9 ± 7.69. Measurements were taken by myotonometry on natural oscillation frequency (Hz), dynamic stiffness (N/m), elasticity (N/m2), mechanical stress relaxation time (ms) and creep, for the following muscles: right and left masseter, right and left temporalis and central fibrous nucleus of the perineum (CFPF). On the other hand, the subjects completed the following questionnaires: perceived stress scale (PSS-14), anxiety scale (STAI), self-reported bruxism questionnaire (CBA), Fonseca Anamnestic Index and the Pittsburgh Sleep Quality Scale (PSQI). RESULTS: Significant correlations were found in several parameters between the right temporalis and CFPF (p<0.05). Highlighting the correlation between TMDs and lubrication r = -0.254 (p = 0.041) and bruxism with pain in sexual intercourse r = 0.261 (p = 0.036). CONCLUSION: The results support the proposed hypothesis. To the author's knowledge, this is the first study which relates both locations, and it is suggested to continue with the research and expand the knowledge of it.

The stress experienced in an emergency medical service (EMS): A descriptive study.

INTRODUCTION: Stress, described as an adaptation of the body to an event, is a considerable problem among health workers, especially for those who work in emergency situations, as they very often have to face complex situations. It has been proven that stress affects the performance of health professionals, which is why it is interesting to measure it in these situations, to be able to know what methods to implement to reduce it in future events. Despite having previous measurements in healthcare personnel during clinical simulations, this study is relevant because stress has never before been measured in EMS professionals when performing their work. OBJECTIVE: To determine the acute stress experienced by professionals in an Emergency Medical Service (EMS) when handling five types of clinical emergencies. As secondary objectives, to determine if there were differences in the increases in stress in relation to sex, age, profession, team, and above all, type of emergency handled. METHOD: The following were measured for the analysis: physiological (mean heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure), and biochemical (salivary alpha amylase (sAA) activity) markers, before (Basal) and after (Post-Stress) the interventions of 27 professionals from an EMS. RESULTS: In general, the results obtained showed significant differences between the baseline measurement of physiological and biochemical markers versus the post-exposure measurement. Some of the differences in stress levels in relation to sex and professional role are striking. CONCLUSION: The determination of acute stress experienced by professionals from an EMS in a real emergency showed significant increases in the sAA enzymatic marker of acute stress. These results are the first data published in this regard, and could be used as a reference to follow in clinical simulation in the training of students and the training of nursing professionals. IMPLICATIONS FOR CLINICAL PRACTICE: Evidence based studies are needed to improve the education and training of emergency and intensive care professionals. The results from are a great step in the analysis of the real stress that professionals are subjected to when they handle different emergencies.

Ductal carcinoma in situ within a fibroadenoma: A case report and review of literature.

BACKGROUND: Fibroadenoma (FA) is the most common tumor found in young women, although it can occur in any age group. Ductal carcinoma in situ (DCIS) that is confined in a FA is rare; it is most frequently reported as an incidental finding. CASE SUMMARY: We report a case of DCIS within a FA in a 46-year-old female without cancer-related personal and family histories. The patient was diagnosed with a breast conglomerate of nodules and was followed for 1 year. In the current control image study, we found suspicious microcalcification, as a new finding, within one of the nodules. Consequently, a core biopsy of the tumor, which appeared hypoechoic, oval, and circumscribed, was performed. The pathological diagnosis was ductal carcinoma in situ within a fibroepithelial lesion. The patient underwent breast-conserving surgery and received radiotherapy as well as endocrine therapy (tamoxifen). CONCLUSION: We recommend a multidisciplinary approach for adequate treatment and follow-up.

Validation of two immunoassays for oxytocin measurements in human saliva.

The objective of this research was to develop and validate two immunoassays for oxytocin measurement in human saliva, one using a monoclonal and the other a polyclonal antibody against oxytocin, whose affinity for oxytocin was tested by an antibody mapping epitope analysis. These assays were analytically validated and used to compare oxytocin concentrations with those obtained with a commercial kit before and after the extraction or reduction/alkylation (R/A) treatments to saliva samples. The assays were also used to evaluate changes in salivary oxytocin concentrations following a physical effort and an induced psychological stress, which have previously been described as situations that cause an increase in salivary oxytocin. Both assays showed to be precise and accurate in the validation studies, and the antibodies used showed a defined binding region in case of the monoclonal antibody, whereas the polyclonal antibody showed binding events through all the oxytocin sequence. Although the monoclonal and polyclonal assays showed a positive correlation, they give results in a different range of magnitude. Both assays showed significant increases in oxytocin concentrations when applied after the physical effort and the psychological stress. This study shows that a variability in the reported values of oxytocin can occur depending on the assay and indicates that the use of different types of antibodies can give a different range of values when measuring oxytocin in saliva.

Automated Spectrophotometric Assays for the Measurement of Ammonia and Bicarbonate in Saliva of Horses: Analytical Validation and Changes in Equine Gastric Ulcer Syndrome (EGUS).

Ammonia (NH3) and bicarbonate (HCO3) have been related to gastric ulcers in humans. Ammonia is considered a possible cause of gastric ulcers, whereas bicarbonate has a protective function. The presence of ulcers in the stomach of horses is defined as Equine Gastric Ulcer Syndrome (EGUS), which is a frequent disease in this species, and it has been associated with changes in saliva composition, such as in analytes related to inflammation, immune system and oxidative stress. The objectives of this study were (1) to perform an analytical validation of two automated spectrophotometric assays, one for ammonia and one for bicarbonate, in the horses' saliva and (2) to evaluate their possible variations with EGUS. Analytical validation of the automated assays for ammonia and bicarbonate in the saliva of horses showed that both assays were precise and accurate. In addition, significantly higher values of ammonia and lower values of bicarbonate were found in the saliva of horses with EGUS compared to healthy horses. It can be concluded that ammonia and bicarbonate can be measured in the saliva of horses and that ammonia increases and bicarbonate decreases in this sample type could be related to the presence of EGUS in this species.

Health impact of the Tajogaite volcano eruption in La Palma population (ISVOLCAN study): rationale, design, and preliminary results from the first 1002 participants.

BACKGROUND: The eruption of the Tajogaite volcano began on the island of La Palma on September 19, 2021, lasting for 85 days. This study aims to present the design and methodology of the ISVOLCAN (Health Impact on the Population of La Palma due to the Volcanic Eruption) cohort, as well as the preliminary findings from the first 1002 enrolled participants. METHODS: A prospective cohort study was conducted with random selection of adult participants from the general population, with an estimated sample size of 2600 individuals. The results of the first 857 participants are presented, along with a group of 145 voluntary participants who served as interveners during the eruption. Data on epidemiology and volcano exposure were collected, and participants underwent physical examinations, including anthropometry, blood pressure measurement, spirometry, and venous blood extraction for toxicological assessment. RESULTS: In the general population (n = 857), descriptive analysis revealed that the participants were mostly middle-aged individuals (50.8 ± 16.4), with a predominance of females. Before the eruption, the participants resided at a median distance of 6.7 km from the volcano in the Western region and 10.9 km in the Eastern region. Approximately 15.4% of the sample required evacuation, whose 34.8% returning to their homes on average after 3 months. A significant number of participants reported engaging in daily tasks involving cleaning of volcanic ash both indoors and outdoors. The most reported acute symptoms included ocular irritation, insomnia, mood disorders (anxiety-depression), and respiratory symptoms. Multivariate analysis results show that participants in the western region had a higher likelihood of lower respiratory tract symptoms (OR 1.99; 95% CI:1.33-2.99), depression and anxiety (OR 1.95; 95% CI:1.30-2.93), and insomnia (OR 2.03; 95% CI:1.33-3.09), compared to those in the eastern region. CONCLUSION: The ongoing follow-up of the ISVOLCAN cohort will provide valuable insights into the short, medium, and long-term health impact related to the material emitted during the Tajogaite eruption, based on the level of exposure suffered by the affected population.

Performance of oxygenation indices and risk scores to predict invasive mechanical ventilation and mortality in COVID-19.

BACKGROUND: Information on the performance of oxygenation indices (OIs) and risk scores in patients requiring invasive mechanical ventilation (IMV) is limited. We determine the performance of the OIs and risk scores in hospitalized patients with COVID-19 to predict the requirement of IMV and death at 28 days after admission. METHODS: A retrospective study of diagnostic tests in patients admitted to the emergency department, hospitalization, and intensive care unit diagnosed with COVID-19. The receiver operating characteristic curve (ROC-curve) were built with the OIs and risk scores to predict IMV and mortality. RESULTS: A total of 1402 subjects entered the final analysis, of whom 19.5% (274/1402) received IMV and 23.0% (323/1402) died at 28 days. The ROC-curve of the delta PaO2/FiO2 ratio for the requirement of IMV and mortality at 28-day was 0.589 (95% CI: 0.546-0.632) and 0.567 (95% CI: 0.526-0.608), respectively. PaO2/FiO2 ≤ 300 shows a ROC curve of 0.669 (95% CI: 0.628-0.711) to predict IMV. PaO2/FiO2 ≤ 300 and 4 C mortality score in mortality at 28 days showed an ROC-curve of 0.624 (95% CI: 0.582-0.667) and 0.706 (95% CI: 0.669-0.742), respectively. CONCLUSION: PaO2/FiO2 ≤ 300, 4 C mortality score ≥ 8, SOFA score ≥ 4 y SaO2/FiO2 ≤ 300 were weak predictors of the IMV requirement from admission, and 4 C mortality score ≥ 8 was weak predictors of the mortality from admission in patients with pulmonary involvement by COVID-19.

Evaluation of Bioactive Effects of Five Plant Extracts with Different Phenolic Compositions against Different Therapeutic Targets.

Plant extracts rich in phenolic compounds have been reported to exert different bioactive properties. Despite the fact that there are plant extracts with completely different phenolic compositions, many of them have been reported to have similar beneficial properties. Thus, the structure-bioactivity relationship mechanisms are not yet known in detail for specific classes of phenolic compounds. In this context, this work aims to demonstrate the relationship of extracts with different phenolic compositions versus different bioactive targets. For this purpose, five plant matrices (Theobroma cacao, Hibiscus sabdariffa, Silybum marianum, Lippia citriodora, and Olea europaea) were selected to cover different phenolic compositions, which were confirmed by the phytochemical characterization analysis performed by HPLC-ESI-qTOF-MS. The bioactive targets evaluated were the antioxidant potential, the free radical scavenging potential, and the inhibitory capacity of different enzymes involved in inflammatory processes, skin aging, and neuroprotection. The results showed that despite the different phenolic compositions of the five matrices, they all showed a bioactive positive effect in most of the evaluated assays. In particular, matrices with very different phenolic contents, such as T. cacao and S. marianum, exerted a similar inhibitory power in enzymes involved in inflammatory processes and skin aging. It should also be noted that H. sabdariffa and T. cacao extracts had a low phenolic content but nevertheless stood out for their bioactive antioxidant and anti-radical capacity. Hence, this research highlights the shared bioactive properties among phenolic compounds found in diverse matrices. The abundance of different phenolic compound families highlights their elevated bioactivity against diverse biological targets.

Adherence to a healthy lifestyle behavior composite score and cardiometabolic risk factors in Spanish children from the CORALS cohort.

To assess the associations between the adherence to a composite score comprised of 6 healthy lifestyle behaviors and its individual components with several cardiometabolic risk factors in Spanish preschool children. Cross-sectional analyses were conducted in 938 participants included in the CORALS cohort aged 3-6 years. Six recognized healthy lifestyle behaviors (breastfeeding, sleep duration, physical activity, screentime, adherence to the Mediterranean diet, and eating speed) were assessed in a composite score. Multiple linear and logistic regression models were fitted to assess the associations with cardiometabolic risk factors (weight status, waist circumference, fat mass index, blood pressure, fasting plasma glucose, and lipid profile). In the adjusted multiple linear and logistic regression models, compared with the reference category of adherence to the healthy lifestyle behavior composite score, those participants in the category of the highest adherence showed significant decreased prevalence risk of overweight or obesity [OR (95% CI), 0.4 (0.2, 0.6)] as well as significant lower waist circumference, fat mass index (FMI), systolic blood pressure and fasting plasma glucose concentration [ß (95% CI), - 1.4 cm (- 2.5, - 0.4); - 0.3 kg/m2 (- 0.5, - 0.1); and - 3.0 mmHg (- 5.2, - 0.9); - 1.9 mg/dL (- 3.5, - 0.4), respectively]. Slow eating speed was individually associated with most of the cardiometabolic risk factors.   Conclusions: Higher adherence to the healthy lifestyle behavior composite score was associated with lower waist circumference, FMI, other cardiometabolic risk factors, and risk of overweight or obesity in Spanish preschool children. Further studies are required to confirm these associations. What is Known: • Lifestyle is a well-recognized etiologic factor of obesity and its comorbidities. • Certain healthy behaviors such as adhering to a healthy diet, increasing physical activity, and decreasing screentime are strategies for prevention and treatment of childhood obesity. What is New: • Higher adherence to the healthy lifestyle behavior composite score to 6 healthy behaviors (breastfeeding, sleep duration, physical activity, screentime, eating speed, and adherence to the Mediterranean diet) was associated with decreased adiposity, including prevalence risk of overweight or obesity, and cardiometabolic risk in preschool children. • Slow eating and greater adherence to the Mediterranean diet were mainly associated to lower fasting plasma and serum triglycerides concentration, respectively.

A Novel System to Selective Tagging of Sinorhizobium fredii Symbiotic Plasmids.

Conventional systems used to tag and transfer symbiotic plasmids (pSyms) of rhizobial strains are based in mutagenesis with transposons. In those processes, numerous clones must be analyzed to find one of them with the transposon inserted in the pSym. Following this strategy, the insertion might interrupt a gene that can affect the symbiotic phenotype of the bacteria tagged. Here, we have developed a new system based in homologous recombination that generates Sinorhizobium fredii strains with pSyms tagged by the insertion of a suicide vector which harbor a truncated copy of S. fredii HH103 nodZ gene, a mob site, and a kanamycin-resistant gene. When it is introduced by conjugation in a S. fredii strain, the vector integrates in pSym by only one recombination event. This pSym tagged can be transferred in matting experiments to other strains in the presence of a helper plasmid. Following this method, we have tagged several strains and transferred their pSyms to a recipient strain demonstrating the potential of this new system.