191 research outputs found
Recommended from our members
An integrated evaluation of costs and benefits of corticosterone secretion through development
textGlucocorticoids (GCs) play critical roles during development: transient increases
in GCs facilitate anticipatory physiological changes and trigger ontogenetic transitions
such as promoting fetal/embryonic organ maturation and initiating birth/hatching. In
contrast, chronically elevated GCs can be detrimental to growth, cognition, and survival.
Thus, animals going through substantial growth may have higher corticosteroid binding
globulin (CBG) levels, or enhance negative feedback/tonic inhibition on the
hypothalamic-pituitary-adrenal (HPA) axis to keep GCs levels low. Here I investigated
these hypotheses using altricial white-crowned sparrow nestlings. I examined 1) the
ontogeny of the corticosterone (CORT) response (both total and free hormone levels), 2)
changes in corticosteroid receptor levels in brain with age, and 3) effects of acute and
extended elevation of CORT on behavior and growth.
In response to acute stress, nestlings showed a low HPA reactivity in total CORT
during the first 1/3 of the nestling period. When free CORT is considered, this
hyporesponsive period was extended to 2/3 of the nestling period, suggesting CBG is one
of the mechanisms to keep free CORT low. These periods coincided with rapid mass
gain and acquiring thermoregulatory ability. The low reactivity was partly due to a
dampened sensitivity at pituitary level or higher as all stages of nestlings responded to
adrenocorticotropic hormone challenges; however it was not due to an enhanced negative
feedback/tonic inhibition on hypothalamus or hippocampus. When CORT levels were
artificially elevated, I only observed detrimental effects on begging behavior and growth.
These series of data elucidated the ontogeny of the HPA axis in altricial nestlings
regarding CORT, binding globulin, and receptor levels. In addition, I found that
measured effects of exogenous CORT are primarily costly and highly age-specific.Ecology, Evolution and Behavio
Transient Elevation of Corticosterone Alters Begging Behavior and Growth of White-Crowned Sparrow Nestlings
Developing animals may face a costâbenefit tradeoff during growth mediated through hormones such as glucocorticoids, as the hormone is essential for development but can have detrimental consequences. To investigate potential tradeoffs caused by brief, moderate elevations of corticosterone in avian young, we artificially elevated the hormone levels in two ways: feeding corticosterone-containing worms and applying corticosterone dermal patches. The former experiment tested the effects of an acute corticosterone elevation (25 min) on begging behavior, whereas the latter explored the effects of artificially elevated corticosterone for 24 to 48 h on growth. Corticosterone altered both begging behavior and growth of white-crowned sparrow nestlings. It increased latency to beg immediately after the treatment and suppressed growth as early as 24 h after the patch application. These experiments also showed that the effects depended on the age or types of development (e.g. gaining mass or growing feathers) that the nestlings were going through
Mapping of Protein-Protein Interaction Sites in the Plant-Type [2Fe-2S] Ferredoxin
Knowing the manner of protein-protein interactions is vital for understanding biological events. The plant-type [2Fe-2S] ferredoxin (Fd), a well-known small iron-sulfur protein with low redox potential, partitions electrons to a variety of Fd-dependent enzymes via specific protein-protein interactions. Here we have refined the crystal structure of a recombinant plant-type Fd I from the blue green alga Aphanothece sacrum (AsFd-I) at 1.46 Ă
resolution on the basis of the synchrotron radiation data. Incorporating the revised amino-acid sequence, our analysis corrects the 3D structure previously reported; we identified the short α-helix (67-71) near the active center, which is conserved in other plant-type [2Fe-2S] Fds. Although the 3D structures of the four molecules in the asymmetric unit are similar to each other, detailed comparison of the four structures revealed the segments whose conformations are variable. Structural comparison between the Fds from different sources showed that the distribution of the variable segments in AsFd-I is highly conserved in other Fds, suggesting the presence of intrinsically flexible regions in the plant-type [2Fe-2S] Fd. A few structures of the complexes with Fd-dependent enzymes clearly demonstrate that the protein-protein interactions are achieved through these variable regions in Fd. The results described here will provide a guide for interpreting the biochemical and mutational studies that aim at the manner of interactions with Fd-dependent enzymes
Stress Responses in Tropical Sparrows: Comparing Tropical and Temperate Zonotrichia
Seasonal modulation of the adrenocortical response appears to be ubiquitous in mid- to high- latitude vertebrates but has not been investigated in tropical vertebrates. Previous studies demonstrate that temperate passerines show seasonality in corticosterone secretion and corticosteroid binding globulin capacities. We examined seasonal and sex differences in the stress response in an equatorial population of Zonotrichia capensis, the only Zonotrichia that breeds in the tropics, and compared the results with those of northern Zonotrichia. Seasonal differences in tropical Zonotrichia would presumably be independent of photoperiod and thus directly related to such activities as reproduction and feather molt. In addition, we investigated the possible role of binding globulin as a sex steroid binding globulin, as suggested for temperate passerines. Similar to northern congeners, Z. capensis show seasonal modulation in total corticosterone and binding globulin capacity with higher levels during breeding than molt. However, unlike many temperate passerines, there are no sex differences in corticosterone secretion or binding globulin capacity. Furthermore, the seasonal differences in total corticosterone diminish when the free levels are calculated. The contrast between equatorial and northern congeners indicates factors such as breeding environment and life-history strategy may play important roles in shaping stress response in these species
Ontogeny and Individual Variation in the Adrenocortical Response of Zebra Finch (Taeniopygia Guttata) Nestlings
Numerous studies indicate interspecies variation in the ontogeny of the adrenocortical response in birds; however, little is known about the extent of interindividual variation in avian young. Toward this end, we examined the ontogeny and interindividual variation in the adrenocortical response in zebra finch (Taeniopygia guttata) nestlings. We measured baseline and stress-induced total (bound and free) corticosterone, corticosteroid binding globulin capacity, and resulting estimated free corticosterone levels in nestlings of four different ages ( days 5, 10, 16, and 21). In addition, we investigated the potential correlates of interindividual variation (brood size and mass). Nestlings at days 5 and 10 post-hatching showed no significant increase in total or free corticosterone levels in response to a standardized handling stress, whereas an adult-like stress response was seen by day 16 post-hatching. There was large interindividual (fivefold) variation in both baseline and stress-induced corticosterone among individual nestlings at any age. We estimate that half of this individual variation in the adrenocortical response could be explained by between-clutch variation (e.g., genetics), while the other half could be explained by other factors such as rearing environment (based on estimated intraclass correlation coefficients). Total baseline corticosterone, but not stress-induced corticosterone, was negatively correlated with fledging mass in this species
Transient and permanent effects of suboptimal incubation temperatures on growth, metabolic rate, immune function and adrenocortical responses in zebra finches
n birds, incubation temperature can vary by several degrees Celsius among nests of a given species. Parents may alter incubation temperature to cope with environmental conditions and/or to manipulate embryonic development, and such changes in incubation behavior could have long-lasting effects on offspring phenotype. To investigate short- and long-term effects of suboptimal incubation temperatures on survival and physiological functions in zebra finches, eggs were incubated at 36.2, 37.4 or 38.4°C for the entire incubation period. The post-hatch environment was identical among the treatment groups. We found that hatching success was lowest in the 38.4°C group, while post-hatch survival was lowest in the 36.2°C group. Incubation temperature had sex-specific effects on offspring phenotype: incubation temperatures affected body mass (Mb) but not physiological parameters of males and conversely, the physiological parameters but not Mb of females. Specifically, males from the 38.4°C group weighed significantly less than males from the 36.2°C group from the nestling period to adulthood, whereas females from different incubation temperature groups did not differ in Mb. In contrast, females incubated at 36.2°C had transient but significantly elevated basal metabolic rate and adrenocortical responses during the nestling and fledgling periods, whereas no treatment effect was observed in males. Innate immunity was not affected by incubation temperature in either sex. These results suggest that a 1°C deviation from what is considered an optimal incubation temperature can lower offspring performance and offspring survival.Publisher PDFPeer reviewe
DialMAT: Dialogue-Enabled Transformer with Moment-Based Adversarial Training
This paper focuses on the DialFRED task, which is the task of embodied
instruction following in a setting where an agent can actively ask questions
about the task. To address this task, we propose DialMAT. DialMAT introduces
Moment-based Adversarial Training, which incorporates adversarial perturbations
into the latent space of language, image, and action. Additionally, it
introduces a crossmodal parallel feature extraction mechanism that applies
foundation models to both language and image. We evaluated our model using a
dataset constructed from the DialFRED dataset and demonstrated superior
performance compared to the baseline method in terms of success rate and path
weighted success rate. The model secured the top position in the DialFRED
Challenge, which took place at the CVPR 2023 Embodied AI workshop.Comment: Accepted for presentation at Fourth Annual Embodied AI Workshop at
CVP
Ontogeny and Individual Variation in the Adrenocortical Response of Zebra Finch ( Taeniopygia guttata ) Nestlings
Abstract Numerous studies indicate interspecies variation in the ontogeny of the adrenocortical response in birds; however, little is known about the extent of interindividual variation in avian young. Toward this end, we examined the ontogeny and interindividual variation in the adrenocortical response in zebra finch (Taeniopygia guttata) nestlings. We measured baseline and stressâinduced total (bound and free) corticosterone, corticosteroid binding globulin capacity, and resulting estimated free corticosterone levels in nestlings of four different ages (days 5, 10, 16, and 21). In addition, we investigated the potential correlates of interindividual variation (brood size and mass). Nestlings at days 5 and 10 postâhatching showed no significant increase in total or free corticosterone levels in response to a standardized handling stress, whereas an adultâlike stress response was seen by day 16 postâhatching. There was large interindividual (fivefold) variation in both baseline and stressâinduced corticos..
Relationship between severity of obsessive-compulsive symptoms and schizotypy in obsessive-compulsive disorder
Characterization of Epstein-Barr virus (EBV)-infected cells in EBV-associated hemophagocytic lymphohistiocytosis in two patients with X-linked lymphoproliferative syndrome type 1 and type 2
- âŠ