National University of Río Cuarto

Since detyrosinated tubulin (Glu-Tub) is increased in the membranes of hypertensive erythrocytes and a reduced content and activity of the enzyme tubulin tyrosine ligase (TTL) in erythrocytes from hypertensive individuals with respect to normotensive individuals was reported, role of TTL in hypertension development was analysed. Erythrocytes and brain of 4 and 10-week-old spontaneously hypertensive rats (SHR) and their normotensive Wistar controls were used to determine content and distribution of tubulin and TTL by immunoblot and immunofluorescence, respectively. TTL activity was determined by incorporation of [14C]Tyrosine in tubulin. Moreover, arterial pressure and erythrocyte deformability was determined after treatment of animals with tyrosine and 3-NO3-tyrosine as substrates of TTL. Results show that the content and enzymatic activity of erythrocyte TTL remain constant in SHR rats in their prehypertensive stage until the pathology develops, while normotensive rats increase both the activity and the amount of TTL throughout their lives. This is consistent with an increase in Glu-Tub in SHR membranes with developed hypertension compared to normotensive rats. Moreover, decrease in Glu-Tub in the erythrocyte membrane in SHR rats treated with tyrosine or 3-NO3-tyrosine as TTL substrates, partially reverses the low deformability of their erythrocytes and high blood pressure caused by the high content of Glu-Tub in the membrane. The results suggest that alterations in the tubulin tyrosination/detyrosination cycle are involved in biochemical and rheological changes in the blood of hypertensive subjects and, consequently, in the development of hypertension.

The effectiveness of rhizobial inoculants depends on their ability to survive environmental stresses associated with water-limiting conditions. This study aimed to evaluate the physiological and lipid responses of the membrane of Bradyrhizobium sp. SEMIA6144, a peanut (Arachis hypogaea) symbiont, under PEG-induced osmotic stress. Bacterial growth, viability, cell morphology, membrane lipid composition, fatty acid profile, and membrane fluidity were analyzed in Bradyrhizobium sp. SEMIA6144 under osmotic stress induced by polyethylene glycol (PEG 6000, 15mmol.L⁻¹). Osmotic stress significantly reduced bacterial growth and viability, resulting in a 42% decrease in dry biomass and a prolonged generation time. Fluorescence microscopy revealed increased cell mortality under stress conditions. Lipid analyses based on radiolabeled acetate incorporation and GC-MS showed that phospholipids remained the predominant lipid class; however, osmotic stress altered neutral lipid distribution, decreasing free fatty acids and increasing fatty acid methyl esters. The phospholipid profile shifted toward higher phosphatidylcholine and cardiolipin contents, accompanied by reduced phosphatidylethanolamine and phosphatidylglycerol levels, indicating a trend toward membrane stabilization. Fatty acid composition was markedly modified, with an increase in the unsaturated 18:1Δ11 fatty acid and a decrease in 16:0, 18:0, and 16:1Δ9 species, resulting in a higher unsaturated/saturated fatty acid ratio. Despite these compositional changes, membrane fluidity remained unchanged, reflecting efficient homeostatic regulation under osmotic stress conditions. These results demonstrate that Bradyrhizobium sp. SEMIA6144 adapts to osmotic stress through coordinated physiological and biochemical adjustments that preserve membrane functionality. These adaptive characteristics are relevant to understanding the persistence of rhizobia under water scarcity conditions and could contribute to the development of more robust inoculant formulations for agricultural applications.

This study aimed to estimate the association of udder health and herd management practices with bulk tank SCC (BTSCC) and the partial costs of subclinical mastitis (milk yield losses and penalties) on dairy farms in Uruguay. As part of a cross-sectional study, a survey on udder health and herd management practices was conducted on 190 randomly selected dairy farms stratified by region and milk shipment volume (MSV). Herd data comprising 13 mo of BTSCC and MSV were obtained from the dairy processing company, and BTSCC values exceeding 250 × 103 cells/mL (BTSCC >250) were identified. Multivariable regression models were developed to evaluate the association between udder health and herd management practices and 4 response variables on a monthly basis: BTSCC, BTSCC >250, milk yield losses, and penalties. In addition, we calculated the population attributable fraction (PAF) of practices associated with BTSCC >250 and their attributable cost. Postmilking teat disinfection (78%) and dry-cow therapy (80%) showed the highest adoption rates. Some practices such as culling of chronically infected cows based on records (11%), the use of automatic cluster removers (22%), the maintenance of calving areas (24%), monthly individual SCC (ISCC; 16%), and a monthly California Mastitis Test (CMT) on all cows (10%) showed low adoption rates. When adoption rates differed across MSV levels, small farms consistently had lower uptake. The lack of use of postmilking teat disinfection was associated with a higher BTSCC (30 ± 11 × 103 cells/mL), higher odds of BTSCC >250 (odds ratio = 2.45), and higher milk yield losses ($1.22 ± $0.45 per cow per month). Similarly, farms that manually removed clusters showed higher BTSCC (29 ± 13 × 103 cells/mL), higher odds of BTSCC >250 (odds ratio = 2.73), and higher penalties ($0.67 ± $0.28 per cow per month). For monthly ISCC, the odds of BTSCC >250 and the milk yield losses and penalties were lower, whereas on farms with maintenance of calving areas, the odds for BTSCC >250 and the penalties were lower. The partial cost of subclinical mastitis was $9.2 ± $3.9 per cow per month. Yield losses comprised 88% of the cost, and variability among farms was high. Practices associated with BTSCC >250 (postmilking teat disinfection, use of automatic cluster removers, monthly ISCC, and maintenance of calving areas) showed high PAF values. Our results highlight opportunities, some with a potential population effect, to reduce subclinical mastitis and increase overall farm profitability, particularly on smaller farms, and underscore the potential benefits of improved udder health management in Uruguay.

The intensive use of chemical fertilizers in soybean (Glycine max) cultivation has caused significant environmental degradation, underscoring the urgent need for sustainable alternatives. In Argentina, Bradyrhizobium japonicum E109 is widely employed as a liquid bioinoculant, yet its efficiency is limited by loss of viability during storage. This study investigated the physiological and biophysical mechanisms underlying membrane adaptation of B. japonicum E109 under storage stress and evaluated lipid supplementation as a stabilization strategy. During six months of liquid storage at 28 °C, bacterial viability (Log CFU mL−1) declined from 10.0 to 7.7, accompanied by morphological collapse and a 29% reduction in membrane fluorescence polarization, indicating increased fluidity. Fatty acid analysis revealed a drastic decrease of unsaturated 18:1 (from 80% to 40%) and a 300–400% increase in saturated 18:0, reducing the U/S ratio from 4 to 1. Spectral phasor analysis confirmed a shift in the lipid microenvironment from an ordered to a disordered state. Supplementation with 400 µM of stearic acid (18:0) restored membrane rigidity, lowered the U/S ratio to 1.5, and improved thermal tolerance. After one month of storage, 18:0-treated cultures maintained 8.0 Log CFU mL−1 and preserved viability after exposure to 37 °C, whereas controls dropped to 3.8 Log CFU mL−1. These results identify lipid remodeling as a key determinant of B. japonicum stability and demonstrate that exogenous 18:0 supplementation mimics natural adaptation, preventing membrane fluidization and enhancing inoculant shelf-life. This lipid-biophysical approach provides a rational framework for developing next generation, more resilient rhizobia formulations for sustainable agriculture.

Hemocyanins are multifunctional soluble proteins found in most mollusks and some arthropods that may turn into a phenoloxidase-like enzyme (PO) associated with innate immune functions. To expand the structural understanding of gastropod hemocyanins and their physiological implications, here we report the single-particle cryogenic electron microscopy (cryo-EM) structure of Pomacea canaliculata snail hemocyanin (PcH) at 4.4 Å resolution along with its intrinsic and proteolytically induced PO activity. PcH shows a Megathura crenulata (giant keyhole limpet) hemocyanin (KLH)-type structure with a cylindrical shape, comprising 20 protomers assembled as di-pentamers of antiparallel asymmetric dimers, organized in a D5 symmetry. Each protomer comprises eight paralogous functional units (FUs) sharing conserved structural features typical of hemocyanins. The achieved map resolution allowed delineation of interaction networks among adjacent subunits across quaternary structure tiers-dimer, pentamer of dimers (decamer), and di-pentamer of dimers (di-decamer). Additionally, we identified six N-glycosylation sites per protomer, totaling 120 glycan trees in the overall structure. Kinetic analysis of intrinsic PO activity using catechol as substrate revealed a Michaelis constant (KM) of 45.3 mm and a catalytic rate constant (kcat) of 2.87 min-1. This specific activity was enhanced by limited proteolysis using digestive and bacterial proteases. Potential protease cleavage sites were identified in silico, mapped onto the PcH model, and their accessibility assessed. Combined with molecular dynamics simulations, these findings suggest a structural basis for the PO induction mechanism. This study expands our knowledge of KLH-type hemocyanins and provides clues into their PO activation, which is triggered by endogenous and/or pathogen-associated proteases. This further underscores the role of molluscan hemocyanins in the innate immune system.

This work is contextualised in the course Inglés Técnico I, which we teach for the Chemical Engineering and Mechanical Engineering programs (School of Engineering, UNRC). The course aims at training students to read academic genres that are instrumental in the engineering disciplinary culture, in order to contribute to the students´ academic literacy development. In view of the new educational programs for both careers, we have been considering gradual changes to systematize the three new courses to be lectured in 2026: Inglés Académico, Inglés Profesional I and Inglés Profesional II. This curricular framework will allow us to scaffold the students’ development of academic literacy in Inglés Académico, so that we can transition into Inglés Profesional I and Inglés Profesional II and therefore foster the development of competences that students will need in work contexts for professional purposes. In this scenario, the purpose of this work is to socialize an activity we carried out at the beginning of Inglés Técnico I (2024), to be able to listen to our students’ voices regarding their beliefs and expectations about their roles as future engineers, related to the use of English in their professional practice. We conducted an educational experience based on an action research approach with the use of narrative frames as data collection instruments. The data about the students’ beliefs provide relevant information to design and teach Inglés Profesional I and Inglés Profesional II in the new educational programs.

The incorporation of new artifacts in the classroom was often thought of as automatically promoting innovation in teaching. However, this inclusion did not always entail significant transformations in teaching practices or important qualitative changes in student learning (Litwin, 1995).The article proposes a series of considerations about innovation in university teaching that derive from the Master's thesis work Consonar: inter-acciones innovadoras para la enseñanza del fenómeno sonoro en dos asignaturas de carreras de grado - Facultad de Ciencias Humanas - UNRC. The conclusions and reflections derived from this experience reveal some key points for considering innovations in university teaching as a singular configuration of resources and strategies with the guiding purpose of fostering comprehension processes.