Mexican Southeast Research Articles

Length-weight relationship and condition factor of armored catfish (Pterygoplichthys sp.) in the Grijalva and Usumacinta rivers, Mexico

Length-weight relationship and condition factor (K) are descriptors of the biology of fish populations, providing fundamental information on growth strategies, nutritional status, and reproduction. These parameters are used to compare the condition of fish populations in aquatic systems with different degrees of anthropogenic intervention. This study aimed to explore the length-weight relationship of Pterygoplichthys sp., to observe whether the physiological condition factor reveals variation from a dammed river (Grijalva) to a free-flowing river (Usumacinta). Given the physiological characteristics of armored catfish (benthic consumer, tolerance to hydrological disturbance and aquatic pollution, and wide reproductive range), we predict that this fish will have a better welfare condition in the Grijalva River than in the Usumacinta. Highest abundance of armored catfish was obtained in the Grijalva River (282 specimens). However, the largest and heaviest fish were caught in the Usumacinta River (34.4 ± 5.31 cm and 389 ± 138 g, respectively). Length-weight ratio of armored catfish showed a negative allometric growth rate in both rivers (b>3), i.e., the fish grew more in length than in weight. However, the condition factor revealed that armored catfish have better physiological conditions in the Usumacinta River. Food availability, species population density, intra- and interspecific competition probably played an important role in fish welfare. Information generated in this study can be used as a guide to analyze more detailed the populations of armored catfish, taking into consideration sex and different bodies of water, to adequately monitor the populations of Pterygoplichthys sp., in the Mexican southeast.

Changes in the Properties of Soils Contaminated with Oil Production Water Before and Af ter Treatment with CaO

In the Mexican southeast, hydrocarbon spills and their residues af fect various agricultural sites. A specific case is spills of oil production or congenital waters that cause soil salinization. When soil is contaminated, restorations are regularly carried out based on regulatory limits, but many regions still do not consider the pedological classification, so restorations are not entirely ef fective and, in the case of agricultural soils, reduce your productivity. For these reasons, this study evaluated the cation exchange with CaO applied to four soils contaminated with congenital waters and determined if there are dif ferences in the treatment behavior according to the properties of each soil. It will be found that sandy soils require less treatment time, but have greater ef fects on their properties compared to clay soils, mainly in field capacity, pH, and porosity. Furthermore, it was found that contaminant removal times vary with respect to the type of soil and that this could be related to the amount and type of clay. In the case of congenital water spills, clay soils show a greater increase in electrical conductivity (EC) compared to sandy soils. When remediated with CaO, clay soils needed longer treatment times to reduce EC, but presented fewer changes in their physical and chemical properties. In addition, it was found that, although washing with drinking water is carried out, the treatment with CaO adds alkalinity to the soils, so they must be managed according to the crop to be developed. It is concluded that soils have dif ferent physical and chemical properties, this influences the response they have to an external agent, both when contaminated and when remediated.

Influence of didactic strategies in the learning of biochemistry in students of a university in the Mexican Southeast

The purpose of this study was to evaluate the relationship between the teaching strategies used by teachers in teaching biochemistry and the level of learning achieved by students. The teaching-learning process in higher education institutions must adapt to the current demands and requirements of a constantly changing society. University students who study biochemistry need to develop skills that encourage self-learning. The research was carried out with 115 students from a university in the southeast of Mexico, (USoM), to observe and describe a phenomenon. Since there was no control or manipulation of variables, we classify this study as descriptive and "ex post facto," given that the phenomenon had already occurred. Students primarily developed their competencies in comprehension (37%) and analysis (33%). However, when applying for a pilot exam, the majority of responses focused on the aspects of knowledge (36%) and understanding (32%). The present study was carried out under the ethical conditions of informed consent of the participants, promulgated in the Declaration of Helsinki. The participation was voluntary, it was developed with an attitude of empathy, and respect, emotional support, and understanding. The confidentiality and privacy of participants were protected at all times. According to the results observed, a transformation in the didactic strategies employed in the teaching of Biochemistry in the Health Science courses in Mexican universities is suggested.

Digestive proteases of Morelet’s crocodile (Crocodylus moreletii) in three life stages

Introduction: Morelet’s crocodile (Crocodylus moreletii) is a species distributed in the Mexican southeast and threatened due to multiple pressures. Objective: To characterize the digestive proteases in the acid phase (stomach) and alkaline phase (intestine) of three life stages of C. moreletii in captivity (hatchling, juvenile, and adult). Methods: Total alkaline and acid protease activities were quantified using casein and haemoglobin as substrates. Trypsin, chymotrypsin, leucine aminopeptidase, and elastase activities were quantified using synthetic substrates. Protease profiles were analysed by SDS-PAGE and Native-PAGE. Results: The specific activity of acid and alkaline proteases showed differences between the three stages, finding the highest activity in the juveniles. Trypsin, chymotrypsin, leucine aminopeptidase, and elastase activities were higher in hatchlings. There were differences in optimum pH and temperature of acid and alkaline proteases, trypsin, and leucine aminopeptidase between the three stages, demonstrating the diversification of the enzymes according to different stages, as well as the presence of specific isoforms in each stage of C. moreletii. The acid phase zymogram showed four bands with pepsin-like acid activity in the hatchling and juvenile crocodile, while in the adult only two of the four bands were detected. The alkaline zymogram showed that the hatchling had the highest number of activity bands compared to the other stages, corresponding to the high specific activity reported in the alkaline phase. Conclusions: Digestive proteases of Morelet’s crocodile differ in their biochemical characteristics and the number of proteases between hatchling, juvenile, and adult. This could help in the future design of balanced diets as well to the sustainable management and production of this species.

A Frenchman in the Solitudes of the Mexican Southeast: Désiré Charnay’s use of Landscapes and Emotions in the Construction of his Exploration Narrative and Identity

This article examines travel writings by Désiré Charnay, a French explorer better known for his work in the fields of archeology and photography than for his literary production. The article examines Charnay’s writings about southeastern Mexico, published during the second half of the nineteenth century, particularly his descriptions of the jungle, the mountains, the plains, the ancient ruins, along with accounts of his own perils and adventures. Charnay’s descriptions not only of nature but also himself—he fashioned himself as a kind of explorer-hero—were influenced by Romanticism.

Management of an urban lagoon. Study case: Ilusiones Lagoon, Tabasco, Mexico

As a delta, Tabasco, located in the Mexican southeast, is susceptible to flooding. The city of Villahermosa, the capital of Tabasco, is not an exception. The most recent event occurred in November 2020, when an excess of rain provoked an urban lagoon to exceed its levels. The lagoon discharges at a river by a diversion channel controlled by a culvert. To analyze it, a hydraulic model -HEC RAS V6.0- was used. Precipitation, flow, and level data recorded during 2020 were used to simulate four scenarios: I) one culvert of 1.5 m x 1.75 m (current situation); II) three culverts of 1.5 m x 1.75 m; III) three culverts of 2 m x 2.5 m; and IV) one culvert of 10 m x 2.5 m. The dimensions of the culverts were subject to the available physical space of the discharge channel. It was found that the best performance was achieved with scenario II. This result is contrasting because this alternative is not the largest as might be expected; it is also encouraging because it improves the performance of this lagoon. With this proposal, we reduce the damage by 75.31%, which means 296 homes are protected. Finally, the proposed methodology can guide designers and decision-makers to evaluate hydraulic works in urban lagoons like those presented in this work.

Exploratory study of the relationship of the NOM-035-STPS with stress levels in the nursing staff of a private clinic in the Mexican southeast

Exploratory study of the relationship of the NOM-035-STPS with stress levels in the nursing staff of a private clinic in the Mexican southeast

Evidence of resistance to ivermectin in the gastrointestinal nematodes of horses from Mexican southeast.

Gastrointestinal nematodes (GIN) are a major impediment to breeding and exploitation of horses. Traditional control of GIN has generated resistance to main anthelmintics, including ivermectin. An analysis of five ranches with a history of IVM use was done to determine the efficacy and resistance of GIN to IVM treatment in horses from the Mexican southeast. Predesigned questionnaires were applied to collect information on previous treatment protocols. The fecal egg count reduction test (FECRT) was applied to determine resistance. Before IVM application, a McMaster test was used to diagnose GIN infection in horses, and feces cultures were done to identify L3 larvae for Strongylida eggs. Pre-treatment samples showed that 72.7% (80/110) of horses were GIN positive, with cyathostomins being the most frequent (91.8%), followed by Oxyuris equi (7.0%), Parascaris equorum (1.0%), and Strongylus vulgaris (0.2%). Based on the results, the horses at each ranch were divided in control (CG) and experimental (EG) groups with similar eggs per gram of feces (EPG). The EG (40/80) was dewormed with IVM (0.2mg/kg orally) and the CG (40/80) remained untreated. After 14days, EPG were measured, and feces cultures were done again to identify L3 larvae. After treatment of EG, 40% (16/40) of horses were positive, the most frequently identified GIN were cyathostomins (98.6%), followed by P. equorum (1.0%) and S. vulgaris (0.2%). Three of the five ranches were classified as resistant, according to the FECRT, with a percentage of reduction from 53 to 68%, all of which used IVM ≥4 times annually. This is the first evidence of resistance in cyathostomins to IVM treatment in horses from the Mexican southeast, adding to the current problem of anthelmintic resistance in equine GIN.

TENDENCIAS Y DESAFIOS DEL TRABAJO DESDE CASA EN EL SECTOR AGROPECUARIO POST-COVID-19: UN ENFOQUE EN EL PERSONAL ADMINISTRATIVO

With the purpose of establishing a relevant precedent for future situations that require the adoption of remote work, this study focuses on the implementation of tools, guidelines and strategic practices during the COVID-19 pandemic in a company in the agricultural sector. The experience of the administrative staff of the company in the Mexican Southeast in relation to the home office is examined. The main objective of this research is to propose improvements in the guidelines and practices of remote work applied in the administration of the company during the various stages of the contingency. The aim is to optimize the management of work from home and develop effective strategies to face future adversities related to the health and integrity of employees. This study is based on applied research with an exploratory and quantitative approach. A non-experimental and longitudinal design is used to examine the restrictions that the staff faced in terms of infrastructure, equipment and logistics to carry out their functions during the home office. The results present a management and continuous improvement proposal based on the experience acquired during the social isolation caused by the COVID-19 pandemic. This proposal aims to strengthen the control of adversities that may arise in situations of risk to the health and integrity of collaborators. The vision obtained from the employment situation confirms the importance of planning and administrative and economic forecasting in organizations. These processes increase the probability of efficiently and effectively addressing any event that requires modifying or adapting normality, as has been the case with remote work during the COVID-19 pandemic in companies in the agricultural sector.

Prevalence of flukes (Fasciola hepatica and paramphistomids) in cattle in south-eastern Mexico.

The objective of this study was to determine the risk factors and prevalence of trematodes in south-eastern Mexico. The prevalence of trematodes was determined in 1010 bovines. The study was carried out from October 2018 (n=291) to December 2019 (n=719). Only in 2019 rumen and liver fluke eggs were differentiated. Faecal samples (n=311) were obtained from farms in southeast Mexico located in Tabasco, Chiapas and Campeche. In addition, the presence of flukes in liver and rumen from slaughtered cattle in abattoirs was recorded with a total of 408 samples. A logistic procedure was used to obtain the prevalence and the effect of main risk factors such as land physiography (flooded areas and hills), year, sex, animals' age and type of sample obtained (eggs in faeces and flukes). The general prevalence of flukes in cattle was 32.3 % in 2018 and 41.7 % in 2019. Prevalence of F. hepatica (liver fluke) was 18.6 % (134/719) and that of paramphistomids (rumen fluke) was 33.4 % (240/719). The infected cattle from the slaughterhouse indicated a lower prevalence of F. hepatica (1 %) and rumen fluke (26.7 %) than in farms detected by egg in faeces (41.8 % and 42.1 %, respectively). The physiographic zone was decisive in the presence of F. hepatica and rumen fluke, while sex did not represent a risk factor (P > 0.05). The environmental conditions of the Mexican southeast favour the presence of both liver and rumen fluke.

Study of a light hydrocarbon fraction spill migration that occurred in an area of the Mexican southeast using computational fluid dynamics

The present work aimed to study, predict and understand benzene migration that occurred during an industrial spill using numerical simulation by computational fluid dynamics. Advection, diffusion and adsorption were the main mechanisms considered that governed the spill incident. The incident occurred due to a fracture under a fuel oil storage tank. The tank was located on a hill 18m high, and the initial value of benzene concentration (soil saturation) was 60ppm. When the spill was discovered, samples in the affected zone were taken using an experimental design. Many samples showed a greater concentration of benzene than allowed by Mexican Official Standards (MOSs) (15ppm). The concentrations found 100m away from the spill were around 60 to 15ppm. Due to the spill being under the tank, it was difficult to discover. The numerical simulation provided an estimate that the spill started around 2years ago. The type of soil in the afflicted zone is rocky, and, consequently, it is difficult to estimate how long it will take to reach the concentration allowed by the MOSs, but the numerical simulation predicts that this concentration will be reached in 14years. Experimental values of the spill contaminant concentration were statistically similar to the CFD estimated data (p < 0.05).

Clinical and Virological Features of SARS-CoV-2 Variants during the Four Waves of the Pandemic in the Mexican Southeast

We conducted a retrospective study using a population of patients who were hospitalized at Dr. Juan Graham Casasus Hospital in Villahermosa (Tabasco, Mexico) and had a positive RT-PCR test for SARS-CoV-2 between June 2020 and January 2022. We analyzed all medical records, including demographic data, SARS-CoV-2 exposure history, underlying comorbidities, symptoms, signs at admission, laboratory findings during the hospital stay, outcome, and whole-genome sequencing data. Finally, the data were analyzed in different sub-groups according to distribution during waves of the COVID-19 pandemic regarding Mexican reports from June 2020 to January 2022. Of the 200 patients who tested positive via PCR for SARS-CoV-2, only 197 had samples that could be sequenced. Of the samples, 58.9% (n = 116) were males and 41.1% (n = 81) females, with a median age of 61.7 ± 17.0 years. Comparisons between the waves of the pandemic revealed there were significant differences in the fourth wave: the age of patients was higher (p = 0.002); comorbidities such as obesity were lower (p = 0.000), while CKD was higher (p = 0.011); and hospital stays were shorter (p = 0.003). The SARS-CoV-2 sequences revealed the presence of 11 clades in the study population. Overall, we found that adult patients admitted to a third-level Mexican hospital had a wide range of clinical presentations. The current study provides evidence for the simultaneous circulation of SARS-CoV-2 variants during the four pandemic waves.

Stuck with Tourism: Space, Power, and Labor in Contemporary Yucatán

Stuck with Tourism: Space, Power, and Labor in Contemporary Yucatán

Impact of climate change on Melipona beecheii and socioeconomic assessment of meliponiculture in the mexican southeast

The present study aimed to show the impact of climate change on Melipona bees in the Yucatan Peninsula and the socioeconomic situation of Melipona honey producers. Meliponiculture is a very important activity for some Mayans in the Yucatan Peninsula. However, the production of Melipona honey and its territorial distribution has decreased in recent decades, compared to the last century. Fieldwork was carried out in the east of the state of Yucatan to assess honey production activities and the socioeconomic situation of the population that depends on them. Data from Worldclim was used to generate distribution models for Melipona bees as well as scenarios of the impact of climate change on these species in the next seven decades. The scenarios that assume the continued presence of Melipona bees in the next seven decades show disappointing results in the face of climate change. It is necessary to implement effective public policies that help promote the well-being of both Melipona bees and the population that depends on them.

Side effects of the Pfizer BioNTech vaccine in health workers of a hospital in the southeast of Mexico.

The goal of this study was to evaluate the side effects of application of the Pfizer BioNTech vaccine on the workers at a Mexican hospital. A cross-sectional study was carried out, in which 1351 workers from a tertiary care center in the Mexican southeast were included. Sociodemographic data, comorbidities, and side effects after the Pfizer BioNTech vaccine were obtained through an online survey. The variables were analyzed through descriptive statistics. The presence or absence of side effects was analyzed through the Chi-square test or t-test, as appropriate. The result was considered statistically significant at p < 0.05. A total of 1351 health workers participated in the online survey. The mean age was 37.8 ± 10.9 years and 56.4% were women. Among them, 8.2% suffered from high blood pressure. In addition, 76.7% manifested pain in the application area. The presence of side effects was associated with the female gender (p < 0.01). Side effects were more prevalent in younger age (37.2 ± 10.7) than older age (41.5 ± 10.8) (p < 0.01). There was no association with the presence of comorbidities (p > 0.05). The data suggest that pain in the application area is the most frequent side effect among workers in a Mexican hospital who received the Pfizer BioNTech vaccine against COVID-19. In addition, we observed sialorrhea as a side effect in the studied population and this had not previously been reported. The highest number of adverse events occurred between 24 to 72 hours after application.

Laparoscopic nephrectomy in patients with renal exclusion secondary to urolithiasis. Which factors can predispose conversion to open surgery?

The prevalence of urolithiasis is 7-10% and has increased over the past years. Simple nephrectomy is, therefore, indicated when renal exclusion is associated with recurrent urinary tract infections and/or chronic pain. The aim of the study was to describe the surgical experience of laparoscopic nephrectomy (LPN) due to urolithiasis in Mexican South-east and which factors can predispose conversion to open surgery. This was a retrospective study including patients with renal exclusion secondary to urolithiasis, who underwent laparoscopic simple nephrectomy between 2016 and 2019. Forty simple LPN for renal exclusion due to urolithiasis was performed between 2016 and 2019. Mean age was 47 ± 10.8 and 82.5% were female. The mean BMI was 30.2 ± 5 kg/m2, mean operative time was 165.2 ± 64. Conversion rate was 12.5% (n = 5). Conversion was significantly associated with abnormal hilum vascular anatomy (p = 0.001), hilum adherences (p = 0.001), and hydronephrosis (p = 0.001). LPN is a safe surgical technique for renal exclusion due to urolithiasis. Hydronephrosis, abnormal vascular anatomy, and the adherences that involved de hilum are the factors that could predictive conversion to open surgery.

Biological Activities of Seven Medicinal Plants Used in Chiapas, Mexico.

Seven medicinal plants from Chiapas, Mexico, used by Native Americans were analyzed, aiming to improve the understanding of their medicinal properties through the evaluation of various biological activities, i.e., bactericidal, antioxidant, α-glucosidase inhibition, and toxicity, to provide a scientific basis for the management of infectious and hyperglycemic diseases in the Mexican southeast. Plant extracts were obtained from Cordia dodecandra, Gaultheria odorata, Heliotropium angiospermum, Justicia spicigera, Leucaena collinsii spp. collinsii, Tagetes nelsonii, and Talisia oliviformis through maceration techniques using methanol and chloroform (1:1). Minimum Inhibitory Concentration (MIC) was employed to determine the antibacterial activity against Staphylococcus aureus, Enterobacter faecalis, Escherichia coli, Enterobacter aerogenes, Enterobacter cloacae, Klebsiella pneumoniae, and Pseudomonas aeuroginosa. The antiradical/antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays and antihemolytic activity using the 2,2’-Azobis(2-amidinopropane) dihydrochloride radical (APPH). The anti-α-glucosidase activity was evaluated in vitro through the chromogenic PNPG assay. The toxicity was assessed using the brine shrimp lethality assay. The highest antimicrobial activity was displayed by T. nelsonii, mainly against E. faecalis and P. aeuroginosa. The extracts of L. collinsii, J. spicigera, and T. nelsonii possess antioxidant properties with EC50 < 50 μg/mL. J. spicigera and T. nelsonii extracts showed the highest antihemolytic activity with IC50 < 14 μg/mL. T. nelsonii exhibited a remarkable inhibitor effect on the α-glucosidase enzyme and the greatest toxic effect on Artemia salina with IC50 = 193 ± 20 μg/mL and LD50 = 14 ± 1 μg/mL, respectively. According to our results, G. odorata, J. spicigera, T. nelsonii, and T. oliviformis extracts contained active antimicrobial compounds. At the same time, T. nelsonii stands to be a possible source of effective antineoplastic and antihyperglycemic compounds.

Effect of an urban area in the distribution pattern and diversity of Neotropical rodents

Urbanization implies the loss of biodiversity and promotes the extirpation of local flora and fauna. It favors habitat fragmentation and the establishment and increase of non-native species and, eventually, the homogenization of the landscape. This study aims to evaluate the urbanization process in a medium-sized city in the Mexican southeast, San Cristóbal de Las Casas (SCLC) in the Neotropics, and the response of the rodent community to such process. The study area was categorized according to its structural characteristics into four coverage classes: urban, forest, agricultural and mountain wetlands. Rodents were sampled over urbanization gradients. In each gradient, nine sampling sites were established. The responses of rodent alpha and beta diversities to landscape structure (landscape metrics) were evaluated. The larger diversity of rodents was found in the mosaic and transition landscape categories and the least diverse were the conserved and urban ones. In SCLC, rodent richness responds to the number of fragments and the diversity of the landscape. Mus musculus and Rattus rattus were more abundant in landscapes with a high percentage of urban cover, while Peromycus mexicanus and P. beatae, in landscapes with higher forest cover. San Cristóbal de Las Casas is a city that grows over areas with native vegetation, forests and mountain wetlands; of which fragments remain embedded in the urban matrix. Mosaic and transition landscapes favor areas with high diversity and richness of rodent species (intermediate disturbance hypothesis). This study suggests that both native and non-native rodent species are abundant in areas with natural vegetation and also in urban sites. Sanitary measures are granted, since reservoir species of pathogens with zoonotic potential can be found in the area.

Intestinal Lipase Characterization in Common Snook (Centropomus undecimalis) Juveniles

The common snook (Centropomus undecimalis) is a euryhaline fish with high commercial demand in the Mexican southeast, Caribbean, and South America. However, some aspects of its digestive physiology are still unknown, particularly in relation to lipid hydrolysis. Therefore, the characterization of the digestive lipase of this species was carried out. Our results show that the digestive lipase’s optimal temperature is 35 °C, being stable between 25 and 35 °C, and shows maximum activity at pH 9, with stability between pH 5 and 8. Different degrees of inhibition were presented by Orlistat (61.4%), Ebelactone A (90.36%), Ebelactone B (75.9%), SDS 1% (80.7%), SDS 0.1% (73.5%), and SDS at 0.01% (34.9%). Orlistat and Ebelactone A and B completely inhibited the lipase band in the zymogram, but not SDS addition. Lipase showed a molecular weight of 43.8 kDa. The high lipase activities in the digestive tract indicate the importance of lipids in the diet of C. undecimalis.

Forecasting of locational marginal price components with artificial intelligence and sensitivity analysis: A study under tropical weather and renewable power for the Mexican Southeast

Electricity price forecasting is fundamental for energy market orientation, providing information contributing to decision making in the short term. Electricity prices are affected by the seasonal, environmental, operational, and regional factors that introduce complex nonlinearities to the prediction process. This work presents a novel hybrid approach based on artificial intelligence and global sensitivity analysis (GSA) to determine the degree to which these external factors influence the components that make up the locational marginal price (LMP) of electricity. The proposed approach is applied for the day-ahead market conditions of the Mexican southeast, a region with a tropical climate having substandard transmission capacity. The study considered a database composed of 11 independent variables (integrated by seasonal, environmental, operational, and economic factors) to forecast the energy, loss, and congestion components presented in the LMP. The data were subjected to preprocessing consisting of filters for cleaning, smoothing, and normalization. Subsequently, a multi-output model based on artificial neural networks (ANN) was trained. In the end, a global sensitivity analysis (GSA) was performed, which quantified the impact of inputs on products as well as the interactions among the inputs. The optimal model has a 50–50–50 architecture, which resulted in a forecast accuracy of over 90% for energy and losses components. GSA results show a strong relationship between the input variables and electricity prices, highlighting that the components are not affected in the same way by the exogenous inputs. The day of the year was the variable with the most significant impact on the loss and congestion components. The aforementioned is associated with the electricity transmission capacity deficit. On the other hand, fuel prices significantly impact the energy component, which is related to the generation mix profile of the peninsular region. The new hybrid methodology would improve the activities of researchers, energy companies, modelers, and electricity market forecasters, such as planning, energy management, and decision-making for policymakers and electricity traders.