Beach almond (Terminalia catappa, Combretaceae) seed production and predation by scarlet macaws (Ara macao) and variegated squirrels (Sciurus variegatoides) / Producción de semillas y depredación del almendro de playa (Terminalia catappa, Combretaceae) por lapas rojas (Ara macao) y ardillas chizas (Sciurus variegatoides)

Knowledge of ecological impacts of exotic beach almond (Terminalia catappa) in the central Pacific of Costa Rica are little known, but studies have found this species to be a potentially important food source for endangered scarlet macaws (Ara macao). In this study, reproductive phenology and seed predation by variegated squirrels (Sciurus variegatoides) and scarlet macaws were measured during March and April 2011 on beaches of central Pacific coastal Costa Rica. Seed productivity and predation levels were quantified on a weekly basis for 111 beach almond trees to assess the importance of beach almond as a food source for scarlet macaws and the extent of resource partitioning between seed predators. Seed production of the trees was great (about 194 272 seeds) and approximately 67% of seeds were predated by seed predators. Macaws consumed an estimated 49% of seeds while squirrels consumed 18%. Additionally, evidence of resource partitioning between squirrels and macaws was found. Scarlet macaws preferred to feed on the northern side and edge of the canopy while squirrels preferred to feed on the southern and inside parts of the canopy. Both species ate most seeds on the ocean side of the tree. Despite the status of this tree as an exotic species, the beach almond appears to be an important resource for scarlet macaw population recovery. The resource produced by this tree should be taken into account as reforestation efforts continue in Costa Rica. Rev. Biol. Trop. 62 (3): 929-938. Epub 2014 September 01.

El conocimiento de los impactos ecológicos del almendro de playa exótico (Terminalia catappa) en el Pacífico Central de Costa Rica son poco conocidos, pero los estudios han encontrado que esta especie es una fuente de alimento potencialmente importante para la lapa roja (Ara macao), en peligro de extinción. En este estudio, se midieron la fenología reproductiva y la depredación de semillas por las ardillas (Sciurus variegatoides) y lapas rojas durante marzo y abril 2011 en las playas de la costa Pacífica Central de Costa Rica. Los niveles de productividad y depredación de semillas se cuantificaron semanalmente para 111 almendros de playa, para evaluar la importancia del almendro de playa como fuente de alimento para la lapa roja y el grado de repartición de recursos entre los depredadores de semillas. La producción de semillas de los árboles fue alta (cerca de 194 272 semillas) y aproximadamente el 67% de las semillas fueron comidas por los depredadores, las lapas rojas consumen un estimado de 49% de las semillas, mientras que las ardillas consumen el 18%. Adicionalmente, se encontró evidencia de la repartición de recursos entre las ardillas y las lapas. Las lapas rojas prefieren alimentarse en el lado norte y el borde de la copa, mientras que las ardillas prefieren las regiones del sur y el interior de la copa. Ambas especies se comieron la mayoría de las semillas en la parte del árbol con lado al mar. A pesar de la situación de este árbol como una especie exótica, la playa de almendras parece ser un recurso importante para la recuperación de la población de lapas rojas. El recurso que produce este árbol debe tomarse en cuenta para continuar con los esfuerzos de reforestación en Costa Rica.

Biochemical adaptations of mammalian hibernation: exploring squirrels as a perspective model for naturally induced reversible insulin resistance

An important disease among human metabolic disorders is type 2 diabetes mellitus. This disorder involves multiple physiological defects that result from high blood glucose content and eventually lead to the onset of insulin resistance. The combination of insulin resistance, increased glucose production, and decreased insulin secretion creates a diabetic metabolic environment that leads to a lifetime of management. Appropriate models are critical for the success of research. As such, a unique model providing insight into the mechanisms of reversible insulin resistance is mammalian hibernation. Hibernators, such as ground squirrels and bats, are excellent examples of animals exhibiting reversible insulin resistance, for which a rapid increase in body weight is required prior to entry into dormancy. Hibernator studies have shown differential regulation of specific molecular pathways involved in reversible resistance to insulin. The present review focuses on this growing area of research and the molecular mechanisms that regulate glucose homeostasis, and explores the roles of the Akt signaling pathway during hibernation. Here, we propose a link between hibernation, a well-documented response to periods of environmental stress, and reversible insulin resistance, potentially facilitated by key alterations in the Akt signaling network, PPAR-γ/PGC-1α regulation, and non-coding RNA expression. Coincidentally, many of the same pathways are frequently found to be dysregulated during insulin resistance in human type 2 diabetes. Hence, the molecular networks that may regulate reversible insulin resistance in hibernating mammals represent a novel approach by providing insight into medical treatment of insulin resistance in humans.

Hábitos alimenticios de la ardilla Sciurus variegatoides (Rodentia: Sciuridae) en la Península de Nicoya, Costa Rica / Feeding habits of the squirrel Sciurus variegatoides (Rodentia: Sciuridae) in the Nicoya Peninsula, Costa Rica

Food items consumed by the squirrel Sciurus variegatoides atrirufus were determined in an agricultural setting in the Nicoya Peninsula (9 degrees 47' N, 84 degrees 56' W), Costa Rica, where two life zones (Premontane Moist Forest Basal Belt Transition, and Tropical Dry Forest) predominate. By analyzing the gut contents of 120 squirrels, from February 1987 through January 1988, it was determined that coconut (Cocos nucifera), indian almond (Terminalia catappa) and flamboyant (Delonix regia) were the most common dietary items. There were differences in food consumption according to age: adults preferred coconut, whereas young individuals preferred almond. This finding can be explained in terms of fruit characteristics, as well as tree architecture and accessibility for squirrels; almendro trees provide higher protection and a more accessible food resource, so that it was better used by young individuals.

Se determinaron los componentes de la dieta de la ardilla Sciurus variegatoides atrirufus en un área agrícola de la Península de Nicoya, Costa Rica (9º47’ N, 84º56’ W), correspondiente a las zonas de vida Bosque Húmedo Premontano Transición a Basal y Bosque Seco Tropical. Al analizar el contenido estomacal de 120 ardillas, entre febrero de 1987 y enero de 1988, se determinó que los alimentos más importantes fueron el coco (Cocos nucifera), el almendro (Terminalia catappa) y el malinche (Delonix regia). Hubo diferencias en el tipo de alimento según la edad. Los adultos consumieron más el coco y los jóvenes el almendro, lo cual se explica por las características del fruto, así como por la arquitectura y acceso al árbol; el almendro aporta mejores condiciones de protección y un recurso alimenticio más accesible, por lo que fue mejor aprovechado por los individuos jóvenes.

Profile of organ weights and plasma concentrations of melatonin, estradiol and progesterone during gestation and post-parturition periods in female Indian palm squirrel Funambulus pennanti.

Todate, report about the role of pineal gland in maintaining the normal physiology of gestation is scanty. Present study is the first of its kind giving a detail profile of organ weights and plasma concentration of melatonin, estradiol and progesterone to suggest a possible role of pineal gland in maintaining normal physiology during gestation and post-parturition periods of female Indian palm squirrel F. pennanti. Inspite of, inverse pineal-gonadal/melatonin-steroids interrelationship in adult (non-pregnant) females, the present results study suggest a direct relationship of pineal gland activity with ovarian steroids especially during the gestation period. The inverse relationship of melatonin and ovarian steroids is again established after parturition and maintained throughout the life. Thus the pineal gland (activity as judged by its weight, biochemical contents i.e. protein and cholesterol and plasma melatonin level) maintained ovarian/uterine physiology and regulated plasma concentrations of estradiol and progesterone during gestation and post-parturition periods. It is suggested that the pineal gland and its hormone melatonin play an important role to maintain the normal physiology of gestation and the post-partum recovery in Indian palm squirrel F. pennanti.

Pineal and 5-methoxyindoles in the regulation of seasonal testicular cycle in Indian palm squirrel, Funambulus pennanti.

Effects of late afternoon injections of different doses of melatonin (aMT) and 5-methoxytryptamine (MT) were studied on the testes in sham operated (SO) and pinealectomized (Px) F. pennanti during various reproductive phases. 5-methoxyindoles (MI) in doses 10 and 50 micrograms given for 60 continuous days reduced the weight and activity of the testes in SO and Px animals during the active and regressive phases. During the inactive phase MI administration caused an inhibitory influence on the testes of Px animals. However, during the recrudescence phase no significant effect of MI injections was visible. Both aMT and MT injected for 20 and 40 days respectively failed to influence the testes significantly. Also 1 microgram of the MI had no effect. The results suggest a reproductive phase dependent effect of aMT and MT on the testes of this tropical rodent. The dose and duration of administration are critical and their effects are independent of the pineal gland.

Effect of pinealectomy and testosterone on gonadal regression and accessory sex organs in Indian palm squirrel, Funambulus pennanti.

Indian palm squirrel (Funambulus pennanti), is a tropical seasonal breeder presents a short gonadal regression period (October-November), concomitant with declining plasma testosterone level. If pinealectomized (Px), however, squirrels maintain full gonadal activity and plasma testosterone levels. The aim of the present study was, therefore, to determine if the Px and exogenous testosterone in intact and Px squirrels would prevent natural gonadal regression. Experiment was performed during testicular regression phase (i.e. August end to November) revealed that both the Px (60 days) and exogenous testosterone (100 micrograms/day/squirrel/30 days) prevented gonadal and accessory sex organ regression. This could be due to negative feedback by testosterone treatment which was more obvious in intact than the Px squirrels. A decline in day time plasma melatonin level after testosterone treatment was also indicative of inverse relationship between the gonadal and pineal hormones which in turn did not allow the collapse of accessory sex organs. Further, the pineal gland is under direct control of steroid hormones since receptors and aromatizing enzymes are noted in the same. Therefore, a pineal secreted melatonin stimulation of hypothalamic negative feedback centers for gonadal regression could be suggested in this tropical rodent as receptors for melatonin have been detected in above areas.

Gonado-modulatory effects of high humidity is pineal dependent in Indian palm squirrel Funambulus pennanti (Wroughton).

F. pennanti presented a clear biphasic pineal mediated seasonal sexual cycle. This sexual cycle was essentially characterised by a very short period of sexual quiescence with an arrest of spermatogenesis during October-November. A small but clear decrease in sexual activity was also observed during March-April. This decrease in sexual activity, however, had no quantifiable effect on spermatogenesis. Sexual recrudescence was observed from December-January. The testes remained sexually active from January till September. Almost an inverse relationship was observed between pineal and testicular weight. Pinealectomy, however, prevented naturally induced gonadal regression during both the periods, i.e. September-November and February-April. Exposure of animals to high RH (80 +/- 4%) during sexually active phase induced a steep regression in testicular weight of sham-operated animals even in the presence of gonad stimulatory long photoperiod (16L:8D) and high temperature (40 degrees +/- 5 degrees C) while exposure of animals to moderate RH (65 +/- 5%) during sexual regression phase partially prevented testicular regression even in presence of inhibitory short photoperiod (11L:13D) and normal environmental temperature (30 degrees +/- 5 degrees C). Pinealectomized animals, neither exhibited testicular regression in February-March nor had involuted testes in September-October, thus, suggesting that the effect of humidity is mediated via the pineal gland.

A study of retinal projections in the ground squirrel, Spermophilus tridecemlineatus, using anterograde transport techniques

Luego de aplicar inyecciones intraoculares unilaterales de prolina radioactiva o de mezclas de fucosa y prolina, consistentemente se detectó radioactividad en el núcleo supraquismático, en los núcleos terminales medial, lateral y dorsal del sistema ópico accesorio, en los núcleos geniculado lateral dorsal y geniculado lateral ventral, en los núcleos pretectales anterior, olivar, posterior y núcleo del tracto óptico y en el colículo superior. En aquellas ardillas terrestres que recibieron una dósis grande de compuesto radioactivos y que sobrevieron durante períodos largos de tiempo después de las inyecciones, también se detectó radioactividad en el núcleo lateral posterior, el núcleo parabigémino y en una porción de la materia gris central del puente. Luego de que se aplicaran inyecciones intraoculares de peroxidasa de rábano, el marcador fue detectado en los lugares que convencionalmente se marcan, y en adición, en el núcleo lateral posterior. Por lo tanto, el marcador presente en todos los núcleo, parabigémino y la materia gris pontina, puede atribuirse a proyecciones directas de la retina. La mayor parte de las proyecciones fueron bilaterales y se podían observar algunas diferencias relacionadas con la lateralidad de las proyecciones. En el núcleo geniculado lateral dorsal se definieron tres láminas en base a las proyecciones de las retinas de ojo ipsilateral y contralateral; se definió una cuarta lámina en base a citoarquitectura. La proyección de la cabeza del nervio óptico se pudo observar en las láminas del núcleo geniculado latreral dorsal que recibían inervación contralateral y en el colículo superior contralateral al ojo inyectado

Biotic Potential of Captured Chipmunks

Captured wild chipmunks which have been extensively used for leprosy research, were studied in our laboratory for the reproductive potentials. Histologically normal organs, which are involved in reproduction in both sexes, were observed. Functionally active viable sperms in sufficient amount were produced by the males, and were used for artificial inseminations. A state of normal reproductive physiology of the females was also confirmed by studies on histologic analysis of oogenesis in the ovaries and in cultured ovaries in vitro. Regularity in ovulation was also determined by vaginal epithelial cell examinations. Thus these animals appeared to be normal in terms of fecundity. It was considered that the inability of these animals to have successful breeding in the captured state was due to problems in fertility, especially in maintaining the pregnancy.