Non-volant mammals of the Ibura National Forest, northeastern Brazil

Less than 10% of the original Atlantic Forest cover now remains standing in the Brazilian state of Sergipe, although few scientific studies have focused on its mammalian diversity. The present study describes the diversity of non-volant mammals found in the Ibura National Forest (INF), based on live trapping, and direct and indirect observations. We sampled the IBF on six days per month between June 2012 and August 2013, using live-traps (Sherman-type) positioned in pairs (ground and understory). We equally sampled semideciduous forest and an abandoned Eucalyptusplantation with dense understory (over 30 years). We also used non-systematics methods (direct observations, vestiges, camera-trap, and opportunistic captures). We recorded 18 species, from 12 families and 7 orders considering all the applied methods. Among recorded species, Bradypus torquatusand Lontra longicaudisare considered threatened of extinction. Considering only the live-trapping (totaling 3,240 trapping nights), we captured 125 individuals (3.85% success) from four species, Marmosa demerarae(52%), Didelphis albiventris(19.2%), Cerradomys vivoi(15.2%), and M. murina(13.6%). Estimated and observed richness was the same, suggesting a satisfactory effort. Didelphis albiventrisand M. demeraraeshowed significantly higher captures in the dry seasons. Didelphis albiventrisand C.vivoishowed significantly higher captures in the substratum, and M. demeraraehigher in the understory. Cerradomysvivoishowed significantly higher captures in the Eucalyptusphytophysiognomy. Non-Metric Multidimensional Scaling and the ANOSIM showed a significant difference in the captured species among semidecidual forest and Eucalyptus. Despite the small area (144 ha), the INF still houses a relatively high mammalian diversity. Further investigations may help to understand the role of habitat reduction in the diversity and habitat partitioning among mammal species in the Atlantic Forest of Northeastern Brazil.

Diversidad, abundancia relativa y patrones de actividad de mamíferos medianos y grandes en una selva seca del Istmo de Tehuantepec, Oaxaca, México / Diversity, relative abundance and activity patterns of medium and large mammals in a tropical deciduous forest in the Isthmus of Tehuantepec, Oaxaca, Mexico

The use of camera traps and mammal track search are complementary methods to monitoring species of which is not well documented their natural history, as in the case of medium and large mammals. To ensure its conservation and good management, it is necessary to generate information about the structure of the community and their populations. The objective of the present study was to estimate the diversity, relative abundance and activity patterns of medium and large mammals in a tropical deciduous forest located in the Isthmus of Tehuantepec, Oaxaca, Mexico. Samplings were conducted in three month intervals, from September 2011 to May 2013. We used photographic-sampling and track search, two complementary sampling methods. For photographic-sampling, 12 camera traps were placed covering an area of 60km², while for the tracks search a monthly tour of four line-transect surveys of three kilometers length each was undertaken. We obtained a total of 344 pictures with 5 292 trap-days total sampling effort; in addition, 187 track records in a total of 144km. With both methods we registered 21 species of mammals, in 13 families and seven orders, and five species resulted in new records to the area. The diversity index of Shannon-Wiener obtained with the method of tracks was H´=2.41, while the most abundant species were Urocyon cinereoargenteus (IAR=0.23) and Pecari tajacu (IAR=0.20). By the method of trap the most abundant species were P. tajacu (IAR=2.62) and Nasua narica (IAR=1.28). In terms of patterns of activity P. tajacu, N. narica and Odocoileus virginianus were primarily diurnal species; Canis latrans and Leopardus pardalis did not show preference for any schedule in particular, and Didelphis virginiana and Dasypus novemcinctus preferred to have nocturnal activity. This information can be of help to the creation of programs of management and conservation of mammals of medium and large in the Isthmus of Tehuantepec, Oaxaca, México. Rev. Biol. Trop. 62 (4): 1433-1448. Epub 2014 December 01.

Para asegurar la conservación y buen manejo de mamíferos medianos y grandes, es necesario generar información sobre la estructura de la comunidad y de sus poblaciones. El objetivo del presente estudio fue estimar la diversidad, abundancia relativa y patrones de actividad de mamíferos medianos y grandes en una selva baja caducifolia en el Istmo de Tehuantepec, Oaxaca, México. El muestreo se llevó a cabo a intervalos de tres meses de septiembre 2011 a mayo 2013. Se utilizaron dos métodos complementarios: se colocaron 12 cámaras trampa cubriendo un área de 60km² y se realizó la búsqueda de rastros en transectos lineales de tres kilómetros de longitud. Se obtuvieron un total de 344 fotografías con un esfuerzo de muestreo de 5 292 días-trampa; además, 187 rastros en un total de 144km recorridos. En total se registraron 21 especies de mamíferos, de 13 familias y siete órdenes. El índice de diversidad de Shannon-Wiener fue más alto con el método de rastros (H´=2.41). Las especies más abundantes por medio de rastros fueron: Urocyon cinereoargenteus (IAR=0.23) y Pecari tajacu (IAR=0.20). Por medio del fototrampeo las especies más abundantes fueron: P. tajacu (IAR=2.62) y Nasua narica (IAR=1.28). Los patrones de actividad de P. tajacu, N. narica y Odocoileus virginianus fueron diurnos; Canis latrans y Leopardus pardalis no presentaron preferencia hacia algún horario en particular y Didelphis virginiana y Dasypus novemcinctus tuvieron actividad nocturna. Esta información puede ser de ayuda para la creación de programas de manejo y conservación de mamíferos medianos y grandes en el Istmo de Tehuantepec, Oaxaca, México.

Bronchial tree architecture in mammals of diverse body mass / Arquitectura del árbol bronquial en mamíferos de diferentes masas corporales

The anatomy of mammal's lung air space constitutes the bronchial tree which disposition is associated to air flux dynamics. Casts obtained from human, pig and rat lungs were studied to analyze possible differences of the bronchial tree architecture in mammals with diverse dimensions and posture. Air spaces were filled with polymers through trachea followed by acid corrosion. Tracheal and main bronchial division's diameters were measured to relate with body mass using allometry. The results revealed a dichotomic bronchial branching pattern in the human casts and a monopodial pattern in animals. In allometric relationship trachea was larger in rats, then pigs and lastly in humans, differences were statistically significant, the same occurs in right bronchus, as in the left bronchus there was no difference between rat and pig. The linear relationship between the human tracheal diameters was 1.2 times larger than the pig and 6.7 times larger than the rat; the pig tracheal diameter was 5.6 times larger than the rat. Quadruped position of the pig and rat is linked to a horizontal air way while the erect position, biped in human, correspond to a vertical air way. A big mammal shows less respiratory frequency than small mammals. Mammals with small, medium and high body mass allied to diverse posture and habits was compared revealing morphological differences in the bronchial trees as different allometric correlations between quadruped animals and human biped.

La anatomía de los espacios aéreos en los pulmones de mamíferos constituyen el árbol bronquial cuya disposición es asociada a la dinámica del flujo aéreo. Moldes obtenidos de los pulmones de humanos, cerdos y ratones fueron estudiados para analizar las posibles diferencias de las arquitecturas de los árboles bronquiales en mamíferos de diferentes dimensiones y posturas. Los espacios aéreos fueran llenados con polímeros por la tráquea y posterior corrosión con ácido. Los diámetros de la tráquea y de las principales divisiones de los bronquios fueron medidos y relacionados con las masas corporales por medio de alometría. Los resultados revelaron uno patrón dicotómico en los moldes de humanos y un patrón monopodial en los animales. La relación alométrica determinço que la tráquea es mayor en los ratones, seguidos de los cerdos y por último en los humanos, las diferencias fueran estadísticamente significativas. Lo mismo ocurrió en el bronquio derecho en cambio en el bronquio izquierdo no hubo diferencia entre el cerdo y el ratón. La relación linear entre los diámetros de la tráquea fue 1,2 mayor en el humano comparada con el cerdo y 6,7 mayor que el ratón, el diámetro de la tráquea del cerdo fue 5,6 mayor que el ratón. La posición cuadrúpede del cerdo y del ratón es vinculada a una vía aérea horizontal en cuanto a que la posición erecta en humanos corresponde a una vía aérea vertical. Los grandes mamíferos muestran menor frecuencia respiratoria que los pequeños mamíferos. Mamíferos con masas corporales pequeñas, medias y grandes con diversas posturas y hábitos fueron comparados mostrando diferencias morfológicas en los árboles bronquiales así como diferentes correlaciones alométricas entre animales cuadrúpedos y humanos bípedos.

Comparative scanning electron microscopy of platelets and fibrin networks of human and differents animals / Microscopía electrónica de barrido comparativa de plaquetas y redes de fibrina de humano y de diferentes animales

The purpose of the present study was to compare the platelet and fibrin network ultrastructure of humans to eight different animal species in order to determine the differences between human and animal platelet and fibrin morphology, and to determine whether the animals studied differ in their platelet and fibrin morphology, and whether these differences can be observed by scanning electron microscopy. Platelets and fibrin networks play an important role both in the coagulation process as well as physiologically in allergic processes and immunological mechanisms. The thickness of human fibrin networks were compared to mouse (Mus musculus), equine (Equus caballus), vervet monkey (Chlorocebus aethiops previously Cercopithecus aethiops), oryx (Oryx gazella), ovine (Ovis aries), penguin (Spheniscus demersus), rabbit (Oryctolagus cuniculus) and sea turtle (Caretta caretta). Fibers were measured and divided into thin (minor) fibers, intermediate fibers and thick (major) fibers. The results obtained indicated that for each of the three fibrin classes, the size ranges of the monkey, oryx and equine were not significantly different to one another, and the human, penguin, oryx and ovine not significantly different to one other. From these results it can be concluded that mammals and aves possess a distinct tri-modal fibrin fiber distribution, different from that of the studied reptilian species where the sea turtle possesses a distinct bimodal fibrin fiber distribution and it can be suggested that the utilization of mammalian and avian models, in terms of fibrin fiber distribution patterns, might be a suitable alternative for ultrastructural studies.

El propósito del presente estudio fue comparar la ultraestructura de plaquetas y las redes de fibrina de los seres humanos y de ocho diferentes especies de animales, con el fin de determinar las diferencias morfológicas de estas estructuras y si las diferencias pueden ser observadas por microscopía electrónica de barrido. Las plaquetas y las redes de fibrina desempeñan un papel importante tanto en el proceso de coagulación como, fisiológicamente en procesos alérgicos y mecanismos inmunológicos. Elgrosor de las redes de fibrina humana fue comparado con las del ratón (Mus musculus), equino (Equus caballus), mono vervet (Chlorocebus aethiops, anteriormente Cercopithecus aethiops, antílope Africano (Oryx gazella), ovino (Ovis aries), pingüino (Spheniscus demersus), conejo (Oryctolagus cuniculus) y tortuga marina (Caretta caretta). Las fibras fueron medidas y agrupadas en fibras delgadas (menor), fibras intermedias y fibras gruesas (grandes). Los resultados obtenidos indicaron que para cada una de las tres clases de fibrina, los rangos de su tamaño en el mono, antílope africano y en equino no fueron significativamente diferentes entre sí, mientras que en humano, pingüino, antílope africano y ovino no fueron significativamente diferentes entre éstos. De estos resultados se pudo concluir que mamíferos y aves poseen una distribución tri-modal de fibras de fibrina, distinta a la de las especies de reptiles estudiadas, donde la tortuga de mar posee una distribución bimodal de fibras de fibrina. Se puede sugerir que la utilización de los modelos mamíferos y aviar, en términos de patrones de distribución de fibras de fibrina, pueden ser una alternativa adecuada para los estudios ultraestructurales.

A Comparative Histomorphometric Study of the Stomach of Rat (Rattus norvegicus), Bat (Eidolon helvum) and Pangolin (Manis tricuspis) in Relation to Diet / Estudio Comparativo Histomorfométrico del Estómago de Rata (Rattus norvegicus), Murciélago (Eidolon helvum) y Pangolin (Manis tricuspis) en Relación con la Dieta

This study verified the comparative histomorphometric adaptations in the stomach of rat, bat and pangolin in relation to diet. Ten rats, ten bats and ten pangolins of both sexes were used for this investigation. The animals were sacrificed after slight anesthesia under chloroform inhalation. The stomach were excised, fixed in 10 percent formol saline and processed for light microscopic study. Stained slides were also subjected to morphometric analysis at a magnification of 400x. The results revealed that the cellular diameter/ density of parietal and zymogenic cells are significantly different in the three mammals (p<0.05) with the exception of the diameter of the zymogenic cells in pangolin which was not statistically significant (p>0.05) when compared with that of rat. Also, histological analysis revealed slight differences in the pattern of organization and distribution of connective tissue fibers. All these observations were reflections of the different pattern the stomachs of the three mammals have adopted to cope with their respective diets.

En este estudio se verificaron las adaptaciones histomorfométricas comparativas en el estómago de ratas, murciélagos y pangolines en relación a la dieta. Se utilizaron para esta investigación 10 ejemplares de cada especie, de ambos sexos. Los animales fueron sacrificados después de anestesia bajo inhalación de cloroformo. Los estómagos fueron extirpados, fijados en formol al 10 por ciento de solución salina y procesados para su estudio microscópico de luz. Los cortes teñidos fueron también objeto de análisis morfométrico con un aumento de X 400. Los resultados revelaron que el diámetro/densidad celular de parietal y las células cimógenas son significativamente diferentes en los tres mamíferos (p <0,05), con la excepción del diámetro de la células cimógenas de pangolines que no era estadísticamente significativa (p> 0,05) en comparación con la de rata. Por otra parte, el análisis histológico reveló ligeras diferencias en las características de organización y distribución de las fibras del tejido conjuntivo. Todas estas observaciones son un reflejo del patrón de los diferentes estómagos de los tres mamíferos, que han adoptado para hacer frente a sus respectivas dietas.

Microarchitectural adaptations in the stomach of African tree pangolin (Manis tricuspis) / Adaptaciones microarquitecturales en el estómago del pangolin africano (Manis tricuspis)

The microarchitecture of the pangolin's stomach favouring the high chitinous diet has been less waived into, despite extensive morphological investigations. Histological analysis of the microanatomy will provide powerful tools for interpretation to yield reliable insights. We investigated this by fixing the tissues in 10 percent formol saline for histological analysis. Serial sections at 5 micron m thickness were subjected to general staining methods for light microscopic study (Haematoxylin and eosin, Van Gieson's and Verhoeff's). The results revealed basic structural arrangements in their coats, with a modification of the epithelial lining of cardia and fundus into stratified squamous keratinized epithelium. These modifications were also reflected in the distribution of collagen and elastic fibers in the various layers (coats) of the stomach. The present study has shown that there was an adaptation of the stomach of African tree pangolin to its diet as reflected in the microarchitectural configuration.

La micro arquitectura del estómago de los pangolines que favorece la alta dieta de chitinous sido poco tomada en cuenta, a pesar de las amplias investigaciones morfológicas. El análisis histológico de la microanatomía proporcionará herramientas de gran importancia para la interpretación, junto con dar una información confiable. Se investigó mediante la fijación de los tejidos en solución salina de formol al 10 por ciento para análisis histológico. Las serie de secciones fueron sometidos a métodos de tinción estándar para el estudio con microscopía de luz (hematoxilina y eosina, Van Gieson y Verhoeff s). Los resultados revelaron adaptaciones estructurales básicas en sus capas, con una modificación del revestimiento epitelial del cardias y fundus en epitelio escamoso estratificado (queratinizado). Estas modificaciones también se reflejan en la distribución de colágeno y fibras elásticas en las diversas capas del estómago. El presente estudio ha demostrado que es una adaptación del estómago a la dieta como se refleja en la configuración de la microarquitectura.

Interplay between the morphometry of the lungs and the mode of locomotion in birds and mammals

We studied the lung diffusion parameters of two species of birds and two species of mammals to explore how structural and functional features may be paralleled by differences in life style or phylogenetic origin. We used two fast-flying species (one mammal and one bird), one running mammal and one bird species that flies only occasionally as models. The harmonic mean thickness of the air-blood barrier was very thin in the species we studied. An exception was the Chilean tinamou Notoprocta perdicaria, which only flies occasionally. It showed an air-blood barrier as thick as that of flightless Galliformes. We found that the respiratory surface density was significantly greater in flying species compared to running species. The estimated values for the oxygen diffusion capacity, DtO2 follow the same pattern: the highest values were obtained in the flying species, the bat and the eared dove. The lowest value was in N. perdicaria. Our findings suggest that the studied species show refinements in their morphometric lung parameters commensurate to their energetic requirements as dictated by their mode of locomotion, rather than their phylogenetic origin. The air-blood barrier appears to be thin in most birds and small mammals, except those with low energetic requirements such as the Chilean tinamou. In the species we studied, the respiratory surface density appears to be the factor most responsive to the energetic requirements of flight

Mitochondrial apoptotic pathways

Apoptosis or programmed cell death (PCD) is a physiological process characteristic of pluricellular organisms leading to self-destruction of the cell. It is therefore involved in development, homeostasis and host defense. However, a significant difference has been shown between mammalian cell apoptosis and non-mammalian cell apoptosis: mitochondria are implicated only in the former. Execution of PCD includes the release of several proapoptotic proteins from the intermembrane space of mitochondria. They could exert their actions through a caspase dependent as well as a caspase independent way. On the other hand, regulation of PCD is mainly given by the Bcl-2 family members, which are in turn essentially regulated by activation of death receptors and/or DNA damage. Nowadays, execution of apoptosis is better known than its regulation. Nevertheless, we are still far of a complete understanding of the apoptotic process

Allometric scaling of biological rhythms in mammals

A wide spectrum of cyclic functions in terrestrial mammals of different size, from the 3-gram shrew to the 3-ton elephant, yields an allometric exponent around 0.25, which is correlated - as a kind of common denominator - with the specific metabolic rate. Furthermore, the applicability of these empirical findings could be extrapolated to chronological events in the sub-cellular realm. On the other hand, the succession of growth periods (T98 percent) until sexual maturity is reached also follows the 1/4 power rule. By means of Verhulst's logistic equation, it has been possible to simulate three different biological conditions, which means that by modifying the numerical value of only one parameter, revertible physiological and pathological states can be obtained, as for instance isostasis, homeostasis and heterostasis.

A study on 'Vermiform Appendix'--a caecal appendage in common laboratory mammals.

The vermiform appendix, a small structure without any known function in human being has been regarded as a vestigial remnant of a more developed distal caecum in man's herbivorous ancestors. A detailed study of the morphological and histological changes in the appendix and the caecum of different mammals with varying dietary habits revealed a distinctly well-defined vermiform appendix in rabbit only. However, the apical part of caecum among the carnivorous animals like cat and dog showed a clear histological picture with heavy infiltration of lymphoid tissue in the mucous & sub-mucous coats as seen in rabbit or human being. Thus, the vermiform appendix is in no way a vestigial organ but a specialized structure without any definitely known function, probably concerned with the establishment and maintenance of the body defence and immunity of the body.

La importancia pericial del estudio comparativo histomorfológico del hueso humano y de otros géneros / Forensic importance of the comparative histomorphometric study of the human bone and bones from other genders

Es un hecho notable que la identificación de huesos o fragmentos de éstos contribuye sobremanera en el esclarecimiento de problemas judiciales. Cuando no se dispone del esqueleto o de huesos íntegros, el análisis de características histomorfológicas óseas se torna un factor decisivo en la elucidación de ciertos casos de identificación. El propósito del presente estudio fue ampliar o buscar nuevas posibilidades en la identificación de fragmentos óseos de seres humanos y de otros 19 mamíferos. Así, analizamos los sistemas de Havers, los canales de Havers, los osteocitos y los canalículos de los mismos, del hombre, anta, aracambé, buey, cabra, perro montés, perro, capivara, carnero, cateto, caballo, conejo, cutia, gato, mono-clavo, jaguar, puerco espín, cerdo, oso hormiguero y venado. Fueron analizados cortes histológicos por desgaste del tejido óseo en sentido longitudinal y transversal y analizados con microscopio de luz. Los resultados demuestran con claridad y precisión que el análisis histomorfológico de las estructuras citadas posibilita la identificación y diferenciación de los géneros estudiados o excluyen la posibilidad de que fragmentos óseos examinados pertenezcan al género Homo sapiens

Is the relationship between population density and body size consistent across independent studies? A meta-analytical approach

The Energetic Equivalence Rule (EER) is a controversial issue in ecology. This rule states that the amount of energy that each species uses per unit of area is independent of its body size. Here, we perform a meta-analytical procedure to combine and compare the slopes of population density and body size relationships across independent studies of mammals and birds. We then compared a distribution of 50,000 bootstrap combined slopes with the expected slope (b = -0.75) under the EER. The combined slopes obtained for mammals and birds separately were -0.755 and -0.321, respectively. The homogeneity hypothesis (i. e. within studies the slopes differ by no more than would be expected due sampling variation) was rejected in both cases. So, EER cannot be supported since the use of an exponent of -0.75 is, in fact, an oversimplification. Significant heterogeneity of slopes within each group (mammals and birds) is an indicator of inferential problems related with variation in body size, spatial scale, the regression model adopted and phylogenetic relationships among species. So, we consider that questions regarding the estimation and validity of slopes is the next challenge of density-body size relationship studies

Scanning electron microscopic study of the epididymis in the dog canis familiaris L

El epidídimo en el perro está revestido por epitelio de tipo columnar pseudoestratificado, encontrándose el tejido conjuntivo inmediatamente debajo de él. El tejido conjuntivo epididimario consiste de estroma e intersticio. Fueron observadas células epiteliales con microvellosidades en el lumen del conducto. Se comparan los resultados obtenidos con los reportados diversos autores en otros mamíferos

Allometry of ECG waves in mammals

The present allometric study deals with the duration of three electrocardiographic intervals (PQ, QRS, QT) and their relationships with the corresponding cardiac cycle length (R-R interval) in mammals across a wide body mass range. The numerical values of the different ECG intervals were obtained from Grauwiler's (1965) monograph on the subject. Because the corresponding body masses were not given by this author, Heusner's (1991) data on basal metabolic rate as function of body mass were used to establish the most likely body mass figure for each case, based on the taxonomic identity between the corresponding specimens. On the other hand, in a recent study we established the "duality" of physiological times (Günther & Morgado, 1996) and, therefore, we adopted this novel approach to investigate the ECG intervals and their relationships with the R-R interval (heart rate reciprocal). Considering that the anatomy and physiology of auricles and ventricles are different (spheroids versus quasi-cylinders), and that excitation (sino-atrial node and His-Purkinje's system) and contraction processes can be described either by Euclidean or fractal geometries, only a quantitative analysis of the different ECG waves could resolve the dilemma. From the present preliminary study we can conclude that fractal geometry is prevalent with regard to ECG intervals

Criterios de definición y sistematización de la musculatura hiposomática en la enseñanza de la anatomía veterinaria / Definition and systematizing criteria of the hiposomatic musculature in the teaching of veterinary anatomy

La musculatura hiposomática está constituida por una masa muscular continua que envuelve las cavidades corporales, situada entre la columna vertebral y la línea media ventral. Está integrada por un conjunto de musculos con características comunes en cuanto a origen embriológico e inervación, posible de ser sistematizado en virtud de sus propiedades morfológicas y funcionales. Como consecuencia de la división del cuerpo en regiones diferentes, así como también, de la superposición de estructuras extrínsecas relacionadas a ella, la musculatura hiposomática sufre grandes modificaciones regionales que dificultan su tratamiento como unidades anatómicas coherentes. Por esta causa, su estudio se realiza fragmentado, en forma topográfica, según la división corporal que afecta a los mamíferos. En este trabajo se analizan posibles pautas para definir, caracterizar y sistematizar la musculatura hiposomática, que permitan un aprendizaje constructivo y asociativo, en el marco global del estudio de un modelo anatómico básico, teórico, común a todas las especies con el que se compara la anatomía particular de cada una de ellas. Se logra definir y sistematizar a la musculatura hiposomática en base a su inervación y orígen embriológico y se concluye que la presencia de grandes variaciones regionales no constituyen obstáculo para reconocer un patrón de organización lógico, que permite relacionar los músculos, funcional y estructuralmente

Morfofisiología de la trompa de eustaquio en mamíferos, aves y batracios: estudio comparativo / Morpho-physiology of the eustachian tube in mammals, birds and frogs: comparative estudy

El presente trabajo es un estudio comparativo de la trompa de Eustaquio en mamíferos, aves y batracios, con la finalidad de encontrar un modelo ideal para estudios experimentales de la trompa de Eustaquio. Se describe la anatomía y fisiología de la trompa de Eustaquio en las clases y especies estudiadas, se encontró que la principal diferencia es la situación del torus tubario que varia, pudiéndose encontrar en la rinofaringe o la orofaringe según la especie. Otras diferencias que se describen, en cuanto al funcionamiento del torus tubario en mamíferos, aves y batracios, se relacionan en forma muy especial con el habitat y las circunstancias muy especiales que privan en estos animales, para facilitar la función primordial de la trompa de Eustaquio y el equilibrio de presiones intra y extratimpanicas

Estudio morfológico comparativo de la nariz de animales de laboratorio / Morphological study of the nasal cavity and septum in laboratory animals

Se hizo comparación de la anatomía macroscópica e histológica del septum nasal de tres especímenes de perros, gatos, cobayos, conejos, ratas y ratones. Se describen las similitudes y las diferencias entre las porciones anterior, media y posterior en cada especie.

Oxidative metabolism and body weight: inactive, active, and mitochondrial volumes

In homeotherms, the standardized (basal) metabolic rate should not be expressed per kilogram of body weight (specific metabolic rate), nor per unit of body surface (square meters of body-ambient interface), since both mitochondrial thermogenesis and heat-loss mechanisms (radiation, conduction, convection, evaporation) are not uniform processes. On the contrary, each organism is an heterogeneous bioreactor, which is composed at least of two compartments: 1) a metabolically active volume (aV), where oxidative phosphorylation takes place; and 2) a metabolically inactive volume (iV), where oxygen consumption is negligible. The ratio (aV/iV) is not invariant, since iV increases disproportionately with the scaling up of body size, and as shown by us, when the three main components of iV, i.e., skeleton, fat deposits, and blood volume, are added together, a similar disproportionality is found. The aV was determined by subtracting the iV from the total volume (V) of an organism, or by estimating the volume occupied by all mitochondria, or mitochondrial volume (mtV). For this purpose two procedures are discussed: 1) the stereological or morphometric method; and 2) the oxygen consumption per unit time or physiometric method. The latter procedure is based on the equivalence between an VO2 = 3 ml O2.min-1 and a mtV of 1 ml, whose oxidative phosphorylation yields an approximate power output of 1 watt. The correspondence between oxygen consumption, heat production, and electron flux at the respiratory chain of the mitochondrial cristae, is discussed. From a physical point of view, the metabolic rate is a ®power® function (P = M L2T-3), where M = mass, L = length, and T = time. The dimensional analysis and the statistical treatment of the corresponding numerical values of more than 200 allometric equations yields the 3/4 power, law established by Kleiber (1961), for the relationship between basal metabolism and body weight. Instead of expressing the metabolic rate per unit body weight (kg-1) or per unit body surface (m-2) structural and functional criteria should be taken into account as, for instance, the distinction between iV and aV, and particularly by emphasizing the paramount importance of the mtV where oxidative phosphorylation takes place. An allometric equation relating mtV and body weight (W) could be tentatively established for interspecies comparisons