Instituto Tecnológico de La Paz

BACKGROUND: Crassostrea gigas accumulates paralytic shellfish toxins (PST) associated with red tide species as Gymnodinium catenatum. Previous studies demonstrated bivalves show variable feeding responses to toxic algae at physiological level; recently, only one study has reported biochemical changes in the transcript level of the genes involved in C. gigas stress response. PRINCIPAL FINDINGS: We found that 24 h feeding on toxic dinoflagellate cells (acute exposure) induced a significant decrease in clearance rate and expression level changes of the genes involved in antioxidant defense (copper/zinc superoxide dismutase, Cu/Zn-SOD), cell detoxification (glutathione S-transferase, GST and cytochrome P450, CPY450), intermediate immune response activation (lipopolysaccharide and beta glucan binding protein, LGBP), and stress responses (glutamine synthetase, GS) in Pacific oysters compared to the effects with the non-toxic microalga Isochrysis galbana. A sub-chronic exposure feeding on toxic dinoflagellate cells for seven and fourteen days (30×10³ cells mL⁻¹) showed higher gene expression levels. A significant increase was observed in Cu/Zn-SOD, GST, and LGBP at day 7 and a major increase in GS and CPY450 at day 14. We also observed that oysters fed only with G. catenatum (3×10³ cells mL⁻¹ produced a significant increase on the transcription level than in a mixed diet (3×10³ cells mL⁻¹ of G. catenatum+0.75×10⁶ cells mL⁻¹ I. galbana) in all the analyzed genes. CONCLUSIONS: Our results provide gene expression data of PST producer dinoflagellate G. catenatum toxic effects on C. gigas, a commercially important bivalve. Over expressed genes indicate the activation of a potent protective mechanism, whose response depends on both cell concentration and exposure time against these toxic microalgae. Given the importance of dinoflagellate blooms in coastal environments, these results provide a more comprehensive overview of how oysters respond to stress generated by toxic dinoflagellate exposure.

BACKGROUND: Crassostrea gigas accumulates diarrheic shellfish toxins (DSP) associated to Prorocentrum lima of which Okadaic acid (OA) causes specific inhibitions of serine and threonine phosphatases 1 and 2A. Its toxic effects have been extensively reported in bivalve mollusks at cellular and physiological levels, but genomic approaches have been scarcely studied. METHODOLOGY/PRINCIPAL FINDINGS: Acute and sub-chronic exposure effects of P. lima were investigated on farmed juvenile C. gigas (3-5 mm). The Pacific oysters were fed with three dinoflagellate concentrations: 0.3, 3, and 30 ×10(3) cells mL-1 along with a nontoxic control diet of Isochrysis galbana. The effects of P. lima on C. gigas were followed by analyzing expression levels of a total of four genes, three involved in cell cycle regulation and one in immune response by polymerase chain reaction and real time quantitative PCR, where changes in time and cell concentration were found. The highest expression levels were found in oysters fed 3 × 10(3) cells mL-1 at 168 h for the cycle regulator p21 protein (9 fold), chromatin assembly factor 1 p55 subunit (8 fold), elongation factor 2 (2 fold), and lipopolysaccharide/β-1, 3 glucan binding protein (13 fold above base line). Additionally, the transcript level of all the genes decreased in oysters fed wich the mixed diet 30 × 10(3) cells mL-1 of dinoflagellate after 72 h and was lowest in the chromatin assembly factor 1 p55 subunit (0.9 fold below baseline). CONCLUSIONS: On C. gigas the whole cell ingestion of P lima caused a clear mRNA modulation expression of the genes involved in cell cycle regulation and immune system. Over-expression could be related to DNA damage, disturbances in cell cycle continuity, probably a genotoxic effect, as well as an activation of its innate immune system as first line of defense.

This article presents a controller for global joint position tracking control of torque-driven robot manipulators involving dynamic Dahl friction. The control law has been designed using a novel theoretical Hamiltonian inspired framework, which allows global uniform asymptotic stability (GUAS) of the nonautonomous nonlinear closed-loop system. An observer is provided to estimate the nonmeasurable state of internal friction of the Dahl model, preserving the GUAS attribute in the closed-loop system. The performance of the proposed control scheme is illustrated through experiments on a two-degree-of-freedom direct-drive robot arm.

A novel procedure for designing an interconnection and damping assignment passivity-based control to perform different walking gaits of a compass-like biped robot is presented. The interconnection and damping assignment passivity-based control method is often used to achieve asymptotic stability of the closed-loop desired equilibrium point in underactuated systems. Nevertheless, in this article, for the first time, this method is used to shape the kinetic energy of the robot and thus perform different gaits by modifying its limit cycle. One degree of underactuation of the compass-like biped robot is considered, and a suitable change of coordinates is made in order to design the proposed control law. The effectiveness of this controller and some advantages with respect to another similar approach are shown through a deep numerical simulation study.

The influence of organic fertilizers on the chemical properties of soil and the production of Alpinia purpurata. Cien. Inv. Agr. 41(2

Big-leaf mahogany ( Swietenia macrophylla King) is an economically important timber species in the Neotropics. For over three centuries, it has been selectively extracted from tropical forests, threatening its populations. We investigate the actual and potential distribution of big-leaf mahogany and assess its abundance on the Yucatan Peninsula based on the National Forest and Soils Inventory database. Furthermore, we evaluate environmental factors associated with its distribution, abundance, and tree size. The actual and potential distribution models show the presence of mahogany in a wide geographic area covering the southern and eastern portions of the Yucatan Peninsula. Abundance of mahogany in the landscape varies and in general is low. The spatial potential distribution model was best explained by the environmental variables of vegetation cover (medium- and high-stature semievergreen tropical forest) and elevation (upland areas). Results also indicate that mahogany remains relatively abundant and contain larger size classes in localities where the species has been harvested and managed for decades under community forest management. Furthermore, statistical analyses show greater tree density of mahogany mostly associated with low-stature semievergreen tropical forest having deep soils (gleysols and vertisols), while larger tree size (diameter at breast height) was associated with medium-stature semievergreen tropical forests in upland areas with moderately deep or shallow soils (mostly rendzinas or leptosols). Despite deforestation, land-use change and forestry activities on the Yucatan Peninsula, particularly in the past 20 years, the distribution and abundance of mahogany do not appear to be as drastically reduced as described in other neotropical regions.

CTD measurements were processed to analyze the thermohaline variability, presence of water masses and geostrophic circulation during a period of neutral ENSO. The abrupt stratification and the steep thermocline, halocline and pycnocline in May and the thermocline and pycnocline in July, were generated by the entry of water of the gulf, originating from coastal upwelling, due to southerly winds. In October, the salinity decrease with a minimum and a maximum subsurface, was caused by water intrusion from the gulf, as the bay is considered an evaporation basin without river discharge with evaporation of 176.16 mm and null precipitation in this month. The mixed layer and stratification decreased in February, was the result of homogenization and cooling water by winds from the north and the lowest solar radiation received. The water exchange with the gulf, on May, July and February, involved Gulf of California Water on the surface and Subtropical Subsurface Water in the deep; exceptionally in October, the Tropical Surface Water, replaced the Gulf of California Water. The bathymetric North Mouth's sill prevented the flow incursion of Pacific Intermediate Water into the bay. In May, July and October, the geostrophic circulation in the bay, was dominated by a cyclonic gyre, which facilitated the exchange of water with the gulf, while in February the circulation was anticyclonic.

El objetivo es determinar la percepción promedio de la calidad en el servicio (CS) y su incidencia en las medias de la satisfacción del cliente (SC) en 54 restaurantes adscritos a la Cámara Nacional de Restaurantes y Alimentos Condimentados, A.C. de La Paz, Baja California Sur. El método se realizó mediante encuestas a comensales valorando cinco dimensiones (instalaciones, accesibilidad, capital humano, atmósfera y la comida) y una serie de análisis de varianza donde los factores fueron los tipos de especialidades de restaurantes. Los resultados revelan que los dimensiones de la CS y SC no presentaron diferencias significativas, excepto en el factor atmósfera y comida. Este hallazgo revela que es necesario realizar un análisis estratégico del servicio para los empresarios. La originalidad consistió en medir la SC en relación a la CS la cual presentó una r=0.9 global. Una limitación fue que solo se segmenta a la población por sexo.

To describe the hydrographical variability at the North Mouth of La Paz Bay, its main point of communication with the Gulf of California, CTD data were analyzed from four sampling surveys conducted during an annual cycle (May, July and October 2001, and February 2002). The results showed an absence of the mixed layer and intense temperature and salinity stratification in spring and summer. In autumn a 30-m mixed layer was registered, with a temperature of 28.5ºC, while in winter an unusual 100-m mixed layer was detected, with a temperature of 17.9ºC. Particular noteworthy is the similarity of the structure between the surface and subsurface layers of the bay and gulf. The most significant difference was the presence of Pacific Intermediate Water (PIW) in the gulf, which does not intrude into the bay due to the barrier created by the sill at the mouth. The T-S diagrams revealed the presence of Gulf of California Water (GCW), Subtropical Subsurface Water (SSW) and PIW in May. In July, however, four water masses were identified: GCW, Equatorial Surface Water (ESW), SSW and PIW. In October, a significant amount of ESW and a considerable decrease in GCW were detected, but in February only GCW and SSW were found. This study shows important hydrographic seasonal variability in the area of the North Mouth, with marked differences between the bay and the gulf, contributing to the understanding of the regional oceanography.

Bemisia tabaci (Aleyrodidae family) is an insect vector of plant viruses that affects a wide variety of crops around the world. In the following study, we analyzed the variation in the bacterial communities associated with natural populations of B. tabaci (MEAM1) of four different crops from six regions from Mexico semi-arid zone (Baja California Sur). PCR was used to amplify the mitochondrial cytochrome oxidase I gene (mtCOI), and then to carry out the phylogenetic analysis for genetic identification of the isolated B. tabaci. Next generation sequencing coupled with 16S metagenomic analysis was applied in order to characterize B. tabaci inner microbial community. Finally, bacterial obligate symbiont and facultative symbiont were confirmed by PCR amplification and by phylogenetic analysis. Ours results pointed toward that B. tabaci MEAM1 inner bacterial communities were predominantly structured by Proteobacteria phylum. Moreover, the most represented endosymbionts were the obligate endosymbiont from the genus “Candidatus Portiera”, as well as two facultative symbionts belonging to genera Rickettsia and Hamiltonella; both obligate and facultative endosymbionts were present for all samples, and their relative abundance varied was crop-independent. Geographic localization and insect diet play a central role to maintain bacterial community structure of the B. tabaci MEAM1 whitefly at phylum taxonomic level. Agricultural practices were a factor that affected samples of bacterial community structure similarities, reflected in samples clustering. Host plants that are part of B. tabaci diet did not influence directly, in spite of sap nutrient differences, into obligate and facultative endosymbionts relative abundance.

The land use change was analyzed based on the effect of the urban growth of Villahermosa city, Tabasco, on arboreal vegetation and aquatic ecosystems. A multitemporal analysis was carried out using the Land Change Modeler for Ecological Sustainability and the CrossTab module of IDRISI Selva® software and change rates were calculated. According to the results, for almost three decades (1984-2008), a total of 4,008 ha of land occupied by arboreal vegetation and 289 ha of wetland were lost, due to the accelerated growth of grasslands and urban areas. Stochastic transition models (Markov chains and cellular automata) projected a loss of 1,171 ha of arboreal vegetation and 247 ha of wetland between 2008 and 2030. This trend is likely to be sustained by the relentless growth of grassland and urban area.

G. Villanueva-López, P. Martínez-Zurimendi, L. Ramírez-Avilés, F. Casanova-Lugo, and A. Jarquín-Sánchez. 2014. Influence of livestock systems with live fences of Gliricidia sepium on several soil properties in Tabasco, Mexico. Cien Inv. Agr. 41(2): 175-186. The aim of the current study was to evaluate the effects of two livestock systems, a livestock system with live fences (LSLF) of Gliricidia sepium associated with signal grass (Brachiaria decumbens) and a livestock system based on a grass monoculture (LSPM), on specific physical and chemical soil characteristics at different depths and distances from the fence. In each system, we randomly selected 9 plots of 600 m². A completely randomized design was used with a 2 x 3 factorial arrangement in which we analyzed the influence of the livestock systems (LSLF and LSPM), soil strata (0-10, 10-20 and 2030 cm) and the interaction of both factors using a multivariate analysis of variance. In addition, we performed analysis of variance to determine the effect of distance sampling in the LSLF (0-3, 3-6 and 6-9 m). The LSLFs were associated with higher (P≤0.05) soil organic matter (OM), carbon (C) and nitrogen (N) content as well as lower pH and bulk density (BD) when compared with the LSPM. In both livestock systems, the soil OM, C and N were higher (P≤0.05) in the upper (0-10 cm) strata and in the LSLF at a 3 to 6 m distance from the live fences. In the LSLF soil, the pH and BD were similar (P>0.05) at different depths and distances from the live fences. However, the soil pH varied between soil depths in the LSPM. Regarding the physical soil properties, only the sand and clay content varied (P≤0.05) at different depths in both systems but not at different distances from the LSLF. We concluded that the LSLF presents high potential to substantially improve the physical and chemical soil properties and provide an important option for reducing soil degradation in future in livestock production systems based on pasture monoculture.

La conservación de los sistemas agroforestales de cacao (SAFC) en Tabasco, México, requiere la revaloración de sus funciones ambientales, debido a que representan relictos de vegetación arbórea en un paisaje dominado por áreas cultivadas. Por tal motivo, se desarrolló una investigación para evaluar la diversidad, estructura arbórea y carbono almacenado en sistemas agroforestales de cacao en la región de la Chontalpa en el estado de Tabasco, México, según edad, suelos y municipios. Para ello, los SAFC se inventariaron para determinar la diversidad a través de los índices de Shannon-Wienner y Sorenson, la estructura arbórea mediante el índice de valor de importancia, clases diamétricas y altura, así como la biomasa aérea estimada a través de ecuaciones alométricas, con lo que se calcularon los contenidos de carbono. Se identificaron 24 familias, 37 géneros y 39 especies. Los SAFC ≥ 40 años poseen ligeramente más diversidad y densidad arbórea. Con base en la edad de los SAFC, la diversidad y estructura arbórea es mayor en los SAFC ≥ 40 años con respecto a los SAFC > (10-15) años y SAFC > (20-35) años; mientras que, con respecto al grupo de suelo, los indicadores antes mencionados son más altos en los Gleysols, seguido de los Fluvisols, Cambisols y Vertisols. La edad y el tipo de suelo determinan el carbono almacenado en la biomasa aérea. Setenta y cinco por ciento del carbono de la biomasa aérea se almacena en los árboles de sombra y 25% en el cacao. Se concluye que los SAFC en Tabasco son similares en diversidad y estructura arbórea. Los más viejos, establecidos en suelos Fluvisoles, son ligeramente más diversos y registran mayor área basal, por lo que almacenan más carbono en la biomasa aérea.

Estimation of distance from objects in real‐world scenes is an important topic in several applications such as navigation of autonomous robots, simultaneous localization and mapping (SLAM), and augmented reality (AR). Even though there is a technology for this purpose, in some cases, this technology has some disadvantages. For example, GPS systems are susceptible to interference, especially in places surrounded by buildings, under bridges or indoors; alternatively, RGBD sensors can be used, but they are expensive, and their operational range is limited. Monocular vision is a low‐cost suitable alternative that can be used indoor and outdoor. However, monocular odometry is challenging because the object location can be known up a scale factor. Moreover, when objects are moving, it is necessary to estimate the location from consecutive images accumulating error. This paper introduces a new method to compute the distance from a single image of the desired object, with known dimensions, captured with a monocular calibrated vision system. This method is less restrictive than other proposals in the state‐of‐the‐art literature. For the detection of interest points, a Region‐based Convolutional Neural Network combined with a corner detector were used. The proposed method was tested on a standard dataset and images acquired by a low‐cost and low‐resolution webcam, under noncontrolled conditions. The system was tested and compared with a calibrated stereo vision system. Results showed the similar performance of both systems, but the monocular system accomplished the task in less time.

Functional electrical stimulation (FES) is a rehabilitation and assistive technique used for stroke survivors. FES systems mainly consist of sensors, a control algorithm, and a stimulation unit. However, there is a critical need to reassess sensing and control techniques in FES systems to enhance their efficiency. This SLR was carried out following the PRISMA 2020 statement. Four databases (PubMed, Scopus, Web of Science, Wiley Online Library) from 2010 to 2024 were searched using terms related to sensing and control strategies in FES systems. A total of 322 articles were chosen in the first stage, while only 60 of them remained after the final filtering stage. This systematic review mainly focused on sensor techniques and control strategies to deliver FES. The most commonly used sensors reported were inertial measurement units (IMUs), 45% (27); biopotential electrodes, 36.7% (22); vision-based systems, 18.3% (11); and switches, 18.3% (11). The control strategy most reported is closed-loop; however, most of the current commercial FES systems employ open-loop strategies due to their simplicity. Three main factors were identified that should be considered when choosing a sensor for gait-oriented FES systems: wearability, accuracy, and affordability. We believe that the combination of computer vision systems with artificial intelligence-based control algorithms can contribute to the development of minimally invasive and personalized FES systems for the gait rehabilitation of patients with FDS.

El déficit de forrajes tropicales en la temporada seca requiere de estrategias de alimentación alternas que involucren trasferencia de tecnologías y la conservación de alimentos locales. El objetivo fue evaluar la respuesta animal y el costo beneficio ante raciones mixtas con diferentes niveles de inclusión de ensilado de maíz en sistemas de producción doble propósito del sur de Quintana Roo. Se utilizaron nueve vacas lactantes con 152 días en leche en un diseño experimental de cuadrado latino 3 x 3 por triplicado. Las secuencias de tratamiento fueron asignadas al azar con periodos experimentales de 12 días, el tratamiento uno (T1) estuvo conformado por la inclusión del 15% de ensilado maíz; el T2 por 31%, T3 por un 45%. Se evaluó la producción de leche, peso vivo, condición corporal, la composición química de la leche y la viabilidad económica. La producción de leche promedio fue de 4.4 kg vaca−1 día−1, con un contenido de grasa de 3.3% y proteína cruda de 3.4%. El peso vivo promedio fue de 424.6 kg y la condición corporal de 2.3, manteniéndose constante a lo largo del experimento. Solo se observaron diferencias (P < 0.05) para la condición corporal siendo favorable para T3. La incorporación del ensilado de maíz en un 15, 31 o 45% vaca−1 día−1 en las raciones mixtas de vacas doble propósito que producen 4.4 kg leche−1 día−1 no incrementó la producción de leche, pero si tienen un efecto en los costó total de alimentación.


 
 
 Modelos ensamblados de Circulación General de la Atmósfera y Océano Acoplados (AOGCM’s) a nivel regional y para diferentes escenarios, indican que para finales del presente siglo, para Tabasco la temperatura puede incrementarse desde 1 a 3.8 oC y la precipitación total anual puede reducirse hasta 14.4%. Eso es lo que modelos a escala regional reportan. Poco se ha investigado con datos observados, a nivel regional para comparar esos escenarios con lo que ha ocurrido en la realidad. El objetivo fue determinar si los datos meteorológicos durante el periodo de 1961 a 2010 registran alguna tendencia de cambio en la temperatura máxima, temperatura mínima, temperatura media y la precipitación y con ello determinar el sentido y magnitud del cambio a nivel regional y estatal. Los resultados que se muestran en las gráficas y cuadros del presente estudio indican que durante el periodo de tiempo estudiado, sí existe evidencia de cambio respecto al tiempo para las variables analizadas. Se encontró que las tendencias de cambio no son uniformes, sino contradictorias para las diferentes variables y localidades estudiadas. En unas localidades el cambio de una misma variable es positivo y en otros negativos. A nivel estatal, la temperatura media anual se ha incrementado 0.9 oC durante el periodo estudiado, con f luctuaciones -0.6 oC a 2.5 oC entre regiones del estado. Asimismo, para el mismo periodo, se tuvo un incremento en la anomalía de la precipitación total promedio anual de 0.5% con fluctuaciones las regiones de -12.1% a 10.2%.
 
 

<p>El objetivo del presente trabajo fue realizar una revisión acerca de las mezclas de materiales orgánicos e inorgánicos utilizados en la elaboración de un nuevo material, el tamaño de partícula, la proporción y su respuesta en planta. En México, los desechos agropecuarios son considerados un reservorio de contaminantes; sin embargo, desde otra perspectiva, representan una industria con mucho potencial. Los nutrientes ingeridos por los animales representan nutrimentos disponibles para las plantas cuando son reciclados adecuadamente. Una de las opciones que minimiza el riesgo de contaminación y mejora su calidad, es la elaboración de compostaje y vermicompost. Ambos procesos constituyen una alternativa para la producción orgánica. Un material por si solo no cumple con las condiciones óptimas. La reducción del volumen de un material orgánico aumenta la compactación y la compresión de las raíces, afectando la eficiencia de riego y la fertilización, por lo que es necesario hacer mezclas con materiales inorgánicos, lo cual se aprovecha en la elaboración de un nuevo material para obtener mejores condiciones de crecimiento para la planta.</p>

The protein scaffold that includes the caspases is ancient and found in all domains of life. However, the stringent specificity that defines the caspase biologic function is relatively recent and found only in multicellular animals. During the radiation of the Chordata, members of the caspase family adopted roles in immunity, events coinciding with the development of substrates that define the modern innate immune response. This review focuses on the switch from the non-inflammatory cellular demise of apoptosis to the highly inflammatory innate response driven by distinct members of the caspase family, and the interplay between these two regulated cell death pathways.

"El análisis de suelo para predecir el nivel de disponibilidad de fósforo (P) es singular para cada cultivo y condición donde se desarrolla; por tanto, debe basarse en la relación entre el P extraído por la planta y el análisis de suelo realizado con una técnica apropiada. El objetivo del presente estudio fue comparar los métodos químicos de análisis de Olsen y Bray P1 para evaluar la disponibilidad de P aprovechable y determinar el nivel crítico para el cultivo el chile habanero (Capsicum chinense Jacq). Se desarrollaron plantas de chile habanero en invernadero usando muestras de 16 suelos del Estado de Yucatán con dos niveles de P (0 y 200 kg ha-1), y se evaluaron los índices de rendimiento (incremento del rendimiento y rendimiento relativo), número de frutos, altura de la planta, diámetro del tallo y materia seca. Los métodos para determinar los niveles críticos fueron el procedimiento gráfico y el método estadístico. La magnitud de la respuesta al P estuvo en función de la disponibilidad inicial de este elemento en el suelo. El método que mejor correlacionó la disponibilidad de P con el rendimiento fue el Olsen (r=0.801) y el nivel crítico fue 11.9 mg kg-1 utilizando el método gráfico. Se concluye que en suelos con concentraciones menores al nivel crítico de P, la probabilidad de una respuesta económica a la adición de fertilizantes es alta."