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Background The cytoskeleton is a key component of the system responsible for transmitting mechanical cues from the cellular environment to the nucleus, where they trigger downstream responses. This communication is particularly relevant in embryonic stem (ES) cells since forces can regulate cell fate and guide developmental processes. However, little is known regarding cytoskeleton organization in ES cells, and thus, relevant aspects of nuclear-cytoskeletal interactions remain elusive. Results We explored the three-dimensional distribution of the cytoskeleton in live ES cells and show that these filaments affect the shape of the nucleus. Next, we evaluated if cytoskeletal components indirectly modulate the binding of the pluripotency transcription factor OCT4 to chromatin targets. We show that actin depolymerization triggers OCT4 binding to chromatin sites whereas vimentin disruption produces the opposite effect. In contrast to actin, vimentin contributes to the preservation of OCT4-chromatin interactions and, consequently, may have a pro-stemness role. Conclusions Our results suggest roles of components of the cytoskeleton in shaping the nucleus of ES cells, influencing the interactions of the transcription factor OCT4 with the chromatin and potentially affecting pluripotency and cell fate.

Canine babesiosis is a disease caused by a parasite of the genus Babesia which destroys red blood cells. Previous studies have shown the presence of Babesia vogeli in rural areas in Costa Rica using molecular techniques. The objective of the present study was to determine the seroprevalence and prevalence of B. vogeli in clinically healthy dogs and their ticks at the national level, both within and outside the Central Valley. Blood samples and ticks from 482 dogs were collected between June 2011 and May 2014, and analyzed by immunofluorescence assay (IFA) and real-time polymerase chain reaction (qPCR); two protocols of endpoint PCR and sequencing were used to confirm qPCR-positive samples. Seroprevalence of canine babesiosis of 5.3% (24/453) was determined at the national level, specifically 2.0% (5/253) within and 9.5% (19/200) outside the Central Valley, respectively. Real-time PCR determined a global prevalence of B. vogeli of 31.3% (125/400): 21.4% (47/220) within the Central Valley and 43.3% (78/180) outside the Central Valley. The endpoint PCR amplified only 10 of the 125 blood samples identified as positive in qPCR. One sample amplified by endpoint PCR was sequenced and identified as B. vogeli . Twelve canines were identified with past infections, seven canines with active infection, and 111 canines with early infection. Two species of ticks were found with B. vogeli : Rhipicephalus sanguineus sensu lato ( n  = 40) and Amblyomma ovale ( n  = 1). The prevalence of canine babesiosis at the national level, both within and outside the Central Valley, is reported here for the first time, determining the presence of the piroplasmid throughout the country, with a higher circulation of the agent outside the Central Valley. Only one species, B. vogeli , was detected in the blood of dogs and their ticks. Therefore, veterinarians should consider using qPCR to determine the presence of the parasite in blood donors and before starting treatment of vector-borne disease in dogs.

Brucellosis has been an endemic disease of cattle and humans in Costa Rica since the beginning of XX century. However, brucellosis in sheep, goats, pigs, water buffaloes, horses and cetaceans, has not been reported in the country. We have performed a brucellosis survey in these host mammal species, from 1999-2016. In addition, we have documented the number of human brucellosis reported cases, from 2003-2016. The brucellosis seroprevalence in goat and sheep herds was 0.98% and 0.7% respectively, with no Brucella isolation. Antibodies against Brucella were not detected in feral or domestic pigs. Likewise, brucellosis seroprevalence in horse and water buffalo farms was estimated in 6.5% and 21.7%, respectively, with no Brucella isolation. Six cetacean species showed positive reactions against Brucella antigens, and B. ceti was isolated in 70% (n = 29) of striped dolphins (Stenella coeruleoalba). A steady increase in the diagnosis of human brucellosis cases was observed. Taking into account the prevalence of brucellosis in the various host mammals of Costa Rica, different measures are recommended.

Brucellosis, caused by Brucella abortus is a major disease of cattle and a zoonosis. In order to estimate the bovine brucellosis prevalence in Costa Rica (CR), a total 765 herds (13078 bovines) from six regions of CR were randomly sampled during 2012-2013. A non-random sample of 7907 herds (532199 bovines) of the six regions, arriving for diagnoses during 2014-2016 to the Costa Rican Animal Health Service was also studied. The prevalence estimated by Rose Bengal test (RBT) ranged from 10.5%-11.4%; alternatively, the prevalence estimated by testing the RBT positives in iELISA, ranged from 4.1%-6.0%, respectively. However, cattle in CR are not vaccinated with B. abortus S19 but with RB51 (vaccination coverage close to 11%), and under these conditions the RBT displays 99% specificity and 99% sensitivity. Therefore, the RBT herd depicted in the random analysis stands as a feasible assessment and then, the recommended value in case of planning an eradication program in CR. Studies of three decades reveled that bovine brucellosis prevalence has increased in CR. B. abortus was identified by biochemical and molecular studies as the etiological agent of bovine brucellosis. Multiple locus variable-number tandem repeat analysis-16 revealed four B. abortus clusters. Cluster one and three are intertwined with isolates from other countries, while clusters two and four have only representatives from CR. Cluster one is widely distributed in all regions of the country and may be the primary B. abortus source. The other clusters seem to be restricted to specific areas in CR. The implications of our findings, in relation to the control of the disease in CR, are critically discussed.

Background Worldwide, Porcine Reproductive and Respiratory Syndrome (PRRS) is among the diseases that cause the highest economic impact in modern pig production. PRRS was first detected in Costa Rica in 1996 and has since then severely affected the local swine industry. Studies of the molecular characterization of circulating strains, correlation with clinical records, and associations with pathogens associated with Porcine Respiratory Disease Complex (PRDC) have not been done in Costa Rica. Results Sequencing and phylogenetic analysis of ORF5 proved that PRRSV-2 was the only species detected in all locations analyzed. These sequences were grouped into three clusters. When comparing samples from San Jose, Alejuela, and Puntarenas to historical isolates of the previously described lineages (1 to 9), it has been shown that these were closely related to each other and belonged to Lineage 5, along with the samples from Heredia. Intriguingly, samples from Cartago clustered in a separate clade, phylogenetically related to Lineage 1. Epitope analysis conducted on the GP5 sequence of field isolates from Costa Rica revealed seven peptides with at least 80% amino acid sequence identity with previously described and experimentally validated immunogenic regions. Previously described epitopes A, B, and C, were detected in the Santa Barbara-Heredia isolate. Conclusions Our data suggest that the virus has three distinct origins or introductions to the country. Future studies will elucidate how recently introduced vaccines will shape the evolutionary change of circulating field strains.

Campylobacter spp. are considered the most common bacterial cause of human gastroenteritis, one of the four main causes of diarrheal disease worldwide, and they are one of the main foodborne pathogens causing hospitalizations and deaths. Here, 148 strains of Campylobacter spp. isolated from poultry at farms, processing plants, and retail stores in Costa Rica were examined for resistance to six antibiotics. An agar dilution test was used to determine the MIC and susceptibility profiles against doxycycline, ciprofloxacin, nalidixic acid, enrofloxacin, chloramphenicol, and erythromycin. In addition, a pulsed-field gel electrophoresis analysis was carried out to determine the genotype relatedness of a representative subset of the isolates. Approximately 136 (92%) of the 148 analyzed isolates showed resistance to the tested drugs. Nalidixic acid, ciprofloxacin, and enrofloxacin were the antibiotics for which resistance occurred most frequently (91.2, 85.8, and 85.8%, respectively), followed by doxycycline (25.0%), chloramphenicol (5.4%), and erythromycin (2.7%). The profile conferring only resistance to quinolones was the most frequently found, and only 2.0% of the isolates showed resistance to quinolones and macrolides simultaneously. Results showed a high frequency of resistant Campylobacter spp. strains and evidenced the distribution, selection, and circulation of resistant strains along the poultry chain from farms to consumers. Cross-contamination and resistance seem to play important roles in the dissemination of these strains at specific points of the poultry chain, even when control measures are being taken. The establishment of effective surveillance and control strategies represents an essential tool for foodborne diseases mitigation. The rational use of antibiotics, especially those still showing efficacy, should be a priority in both human and veterinary medicine to contain the progress of this phenomenon and its consequences.

Background Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) continues to impose significant economic losses on pig production globally. In Costa Rica, where the virus is endemic, there is limited knowledge of the farm-level risk factors influencing PRRSV spread. This study aimed to identify biosecurity factors associated with PRRSV seroprevalence in Costa Rican pig farms. Methods A cross-sectional survey was conducted on 21 pig farms across Costa Rica. Data on farm management and biosecurity practices were collected using a structured questionnaire and linked to PRRSV seroprevalence data from a companion study. Logistic regression, and machine learning methods like LASSO (Least Absolute Shrinkage and Selection Operator), and Random Forest models were used to identify significant risk factors associated with herd-level PRRSV positivity. Results Three key risk factors were consistently identified by both LASSO and Random Forest models: historical controlled exposure to PRRSV, restrictions on employee access to the farm, and restrictions on employee visits to other pig farms. Additional risk factors identified included topography, disinfection practices for transport vehicles, sanitation measures for visitors, boot and clothing protocols, and feedback procedures. Farms with a history of controlled exposure had an odds ratio of 90 (95% CI: 7.6–3,550) for being PRRSV-positive. Conclusion The findings underscore the importance of internal and external biosecurity measures, particularly in relation to personnel movement and intentional exposure practices. Modeling approaches such as LASSO and Random Forest provided complementary insights into PRRSV risk factors in a tropical production setting. These insights can guide tailored interventions to reduce PRRSV transmission in Costa Rica and similar regions.

The age at first calving (AFC) is one of the most used indicators to evaluate the efficiency of rearing systems in dairy herds. The objective of the present study was to evaluate the association between AFC and different parameters of productive and reproductive efficiency in dairy cows of Holstein and Jersey breeds and their crosses, reared under pasture-based conditions. A retrospective longitudinal study was carried out with information on the performance of 77,311 cows with birth and culling dates between 1990 and 2016 from 654 specialized dairy herds located in mid and high-altitude regions of Costa Rica. Cows were classified into five classes according to their age in months at first calving (≤24, 25–27, 28–30, 31–33, ≥34). A generalized linear mixed model was used to assess the effect of AFC and breed factors on milk production (first lactation, lifetime total, and per day of life), open period (first calving and lifetime total), and herd life. The mean AFC was 29.5, 29.1, and 28.0 months for Holstein, Holstein × Jersey, and Jersey, respectively. The AFC was significantly associated (p < 0.01) with all the variables evaluated. Cows with AFC ≤ 24 presented a higher (p < 0.01) milk production (total lifetime and per day of life), as well as a longer herd life, compared to cows in classes of AFC > 28 m. The reduction in AFC contributes to a significant increase in the production and reproduction efficiency of pasture-based dairy herds. This effect was consistent across the three breed groups.

The aim of this study was to assess the seasonal effect of an embryo transfer program in the tropics on the donor response, recipient reproductive performance and calf growth from birth to weaning. This study included five-year records from 145 donors, 1149 embryo transfers (ET) and 609 in calves. The effect of the season (dry or wet) was evaluated at the time of embryo flushing, embryo transfer and birth of the calves. There was a seasonal effect on the yield and quality of the embryos. The number of nonfertilized and transferable good quality embryos increased in the wet season. For the recipients, the probability of pregnancy after an ET decreased by 6% for each year of the dam’s age. However, no seasonal effect was found when comparing ET calves with their control group (natural mating—NM), nevertheless, weaning weight was associated with birth body weight, treatment, sex of the calf, season at birth, year of treatment, and dam’s age. Calves born by NM had lower average daily gain (ADG), and male calves registered higher gains than females. Likewise, calves born during the rainy season had lower ADG compared with calves born during the dry season. In conclusion, this study shows that seasonal effect is more apparent in donor and calf performance than in the recipients.

An effective frontal stunning procedure in water buffaloes was assessed using a pneumatic penetrating captive bolt (PPCB) with high air pressure. The study contemplated two phases; first, 352 buffaloes and 168 post-mortem heads were evaluated to determine the most effective anatomical site for stunning. Then, the second phase (n = 182) was used to validate the stunning procedure at the discovered anatomical site in the first phase, which was located 8 cm dorsal above the middle of the forehead on an “X” formed between the eyes and the base of the contralateral horns, and 2 cm lateral, avoiding the midline, where the skull tended to narrow. A total of 95.1% of buffaloes received effective stunning at the first shot with evidence of the presence of collapse, absence of rhythmic breathing, and absence of ocular reflexes (corneal and palpebral). There were no differences in the stunning efficacy by sex, breed, or skull thickness. These findings demonstrated that stunning with a PPCB at pressures of 1379–1516.8 KPa (200–220 pounds per square inch (psi)) in the site reported here produces a highly effective stunning at the first shot in water buffaloes.