Backbone 1H, 13C,and 15N assignments of yeast Ump1, an intrinsically disordered protein that functions as a proteasome assembly chaperone

Eukaryotic proteasome assembly is a highly organized process mediated by several proteasome-specific chaperones, which interact with proteasome assembly intermediates. In yeast, Ump1 and Pba1-4 have been identified as assembly chaperones that are dedicated to the formation of the proteasome 20S catalytic core complex. The crystal structures of Pba chaperones have been reported previously, but no detailed information has been provided for the structure of Ump1. Thus, to better understand the mechanisms underlying Ump1-mediated proteasome assembly, we characterized the conformation of Ump1 in solution using NMR. Backbone chemical shift data indicated that Ump1 is an intrinsically unstructured protein and largely devoid of secondary structural elements.     

An ethical issue in biodiversity science: The monitoring of penguins with flipper bands

Individual marking is essential to study the life-history traits of animals and to track them in all kinds of ecological, behavioural or physiological studies. Unlike other birds, penguins cannot be banded on their legs due to their leg joint anatomy and a band is instead fixed around a flipper. However, there is now detailed evidence that flipper-banding has a detrimental impact on individuals. It can severely injure flipper tissues, and the drag effect of their flipper bands results in a higher energy expenditure when birds are moving through the water. It also results in lower efficiency in foraging, since they require longer foraging trips, as well as in lower survival and lower breeding success. Moreover, due to the uncertainty of the rate of band loss, flipper bands induce a scientific bias. These problems, which obviously have serious ethical implications, can be avoided with alternative methods such as radiofrequency identification techniques.     

Sex differences in body composition of wintering Mallards (Anas platyrhynchos): possible implications for survival and reproductive performance

Capsule Wintering female Mallards have a higher fat load than males which may compensate for their lower body size and ultimately improve their fitness.

Aims To investigate whether sex-related differences in biological processes in winter are associated with differences in body nutrient storage and flight capabilities and, if so, the possible implications for survival and reproductive performance.

Methods We analysed the body composition and the flight parameters of 35 male and 35 female Mallards wintering in western Europe on the Rhine river.

Results Males were 15% heavier and 18% larger than females, but the latter carried 27% more fat per unit body mass. Relative to body lipid mass, body protein mass was 11% lower for females. Wing loading was 7% lower in females and power loading was similar in both sexes.

Conclusions High lipid mass gives females survival capabilities to food shortage similar to males. This helps sustain them through their prebasic moult and breeding success. Heavier muscles in males compensate for their higher wing loading and thus improve pairing success. Wintering and reproductive strategies in Mallard seem to be closely linked through body reserves.     

The mouse KRAB zinc-finger protein CHATO is required in embryonic-derived tissues to control yolk sac and placenta morphogenesis

Yolk sac and placenta are required to sustain embryonic development in mammals, yet our understanding of the genes and processes that control morphogenesis of these extraembryonic tissues is still limited. The chato mutation disrupts ZFP568, a Krüppel-Associated-Box (KRAB) domain Zinc finger protein, and causes a unique set of extraembryonic malformations, including ruffling of the yolk sac membrane, defective extraembryonic mesoderm morphogenesis and vasculogenesis, failure to close the ectoplacental cavity, and incomplete placental development. Phenotypic analysis of chato embryos indicated that ZFP568 does not control proliferation or differentiation of extraembryonic lineages but rather regulates the morphogenetic events that shape extraembryonic tissues. Analysis of chimeric embryos showed that Zfp568 function is required in embryonic-derived lineages, including the extraembryonic mesoderm. Depleting Zfp568 affects the ability of extraembryonic mesoderm cells to migrate. However, explanted Zfp568 mutant cells could migrate properly when plated on appropriate extracellular matrix conditions. We show that expression of Fibronectin and Indian Hedgehog are reduced in chato mutant yolk sacs. These data suggest that ZFP568 controls the production of secreted factors required to promote morphogenesis of extraembryonic tissues. Our results support previously undescribed roles of the extraembryonic mesoderm in yolk sac morphogenesis and in the closure of the ectoplacental cavity and identify a novel role of ZFP568 in the development of extraembryonic tissues.     

Exogenous corticosterone and nest abandonment: A study in a long-lived bird, the Adélie penguin

Breeding individuals enter an emergency life-history stage when their body reserves reach a minimum threshold. Consequently, they redirect current activity toward survival, leading to egg abandonment in birds. Corticosterone (CORT) is known to promote this stage. How and to what extent CORT triggers egg abandonment when breeding is associated with prolonged fasting, however, requires further investigation.We manipulated free-living male Adélie penguins with CORT-pellets before their laying period. We then examined their behavioral response with respect to nest abandonment in parallel with their prolactin levels (regulating parental care), and the subsequent effects of treatment on breeding success in relieved birds.Exogenous CORT triggered nest abandonment in 60% of the treated penguins ~ 14 days after treatment and induced a concomitant decline in prolactin levels. Interestingly, prolactin levels in treated penguins that did not abandon their nest were higher at the point of implantation and also after being relieved by females, when compared with abandoning penguins. Among successful birds, the treatment did not affect the number of chicks, nor the brood mass.Our results show the involvement of CORT in the decision-making process regarding egg abandonment in Adélie penguins when incubation is associated with a natural long fast. However, we suggest that CORT alone is not sufficient to trigger nest abandonment but that 1) prolactin levels need to reach a low threshold value, and 2) a rise in proteolysis (i.e. utilization of protein as main energy substrate) seems also to be required.     

A novel role in cytokinesis reveals a housekeeping function for the unfolded protein response

The unfolded protein response (UPR) pathway helps cells cope with endoplasmic reticulum (ER) stress by activating genes that increase the ER's functional capabilities. We have identified a novel role for the UPR pathway in facilitating budding yeast cytokinesis. Although other cell cycle events are unaffected by conditions that disrupt ER function, cytokinesis is sensitive to these conditions. Moreover, efficient cytokinesis requires the UPR pathway even during unstressed growth conditions. UPR-deficient cells are defective in cytokinesis, and cytokinesis mutants activate the UPR. The UPR likely achieves its role in cytokinesis by sensing small changes in ER load and making according changes in ER capacity. We propose that cytokinesis is one of many cellular events that require a subtle increase in ER function and that the UPR pathway has a previously uncharacterized housekeeping role in maintaining ER plasticity during normal cell growth.     

A novel PIP2 binding of epsilonPKC and its contribution to the neurite induction ability

Protein kinase C-epsilon (epsilonPKC) induces neurite outgrowth in neuroblastoma cells but molecular mechanism of the epsilonPKC-induced neurite outgrowth is not fully understood. Therefore, we investigated the ability of phosphatidylinositol 4,5-bisphosphate (PIP(2)) binding of epsilonPKC and its correlation with the neurite extension. We found that full length epsilonPKC bound to PIP(2) in a 12-omicron-tetradecanoylphorbol-13-acetate dependent manner, while the regulatory domain of epsilonPKC (epsilonRD) bound to PIP(2) without any stimulation. To identify the PIP(2) binding region, we made mutants lacking several regions from epsilonRD, and examined their PIP(2) binding activity. The mutants lacking variable region 1 (V1) bound to PIP(2) stronger than intact epsilonRD, while the mutants lacking pseudo-substrate or common region 1 (C1) lost the binding. The PIP(2) binding ability of the V3-deleted mutant was weakened. Those PIP(2) bindings of epsilonPKC, epsilonRD and the mutants well correlated to their neurite induction ability. In addition, a chimera of pleckstrin homology domain of phospholipase Cdelta and the V3 region of epsilonPKC revealed that PIP(2) binding domain and the V3 region are sufficient for the neurite induction, and a first 16 amino acids in the V3 region was important for neurite extension. In conclusion, epsilonPKC directly binds to PIP(2) mainly through pseudo-substrate and common region 1, contributing to the neurite induction activity.     

Body temperature changes induced by huddling in breeding male emperor penguins

Huddling is the key energy-saving mechanism for emperor penguins to endure their 4-mo incubation fast during the Antarctic winter, but the underlying physiological mechanisms of this energy saving have remained elusive. The question is whether their deep body (core) temperature may drop in association with energy sparing, taking into account that successful egg incubation requires a temperature of about 36 degrees C and that ambient temperatures of up to 37.5 degrees C may be reached within tight huddles. Using data loggers implanted into five unrestrained breeding males, we present here the first data on body temperature changes throughout the breeding cycle of emperor penguins, with particular emphasis on huddling bouts. During the pairing period, core temperature decreased progressively from 37.5 +/- 0.4 degrees C to 36.5 +/- 0.3 degrees C, associated with a significant temperature drop of 0.5 +/- 0.3 degrees C during huddling. In case of egg loss, body temperature continued to decrease to 35.5 +/- 0.4 degrees C, with a further 0.9 degrees C decrease during huddling. By contrast, a constant core temperature of 36.9 +/- 0.2 degrees C was maintained during successful incubation, even during huddling, suggesting a trade-off between the demands for successful egg incubation and energy saving. However, such a limited drop in body temperature cannot explain the observed energy savings of breeding emperor penguins. Furthermore, we never observed any signs of hyperthermia in huddling birds that were exposed to ambient temperatures as high as above 35 degrees C. We suggest that the energy savings of huddling birds is due to a metabolic depression, the extent of which depends on a reduction of body surface areas exposed to cold.     

Vultures of the seas: hyperacidic stomachs in wandering albatrosses as an adaptation to dispersed food resources, including fishery wastes

Animals are primarily limited by their capacity to acquire food, yet digestive performance also conditions energy acquisition, and ultimately fitness. Optimal foraging theory predicts that organisms feeding on patchy resources should maximize their food loads within each patch, and should digest these loads quickly to minimize travelling costs between food patches. We tested the prediction of high digestive performance in wandering albatrosses, which can ingest prey of up to 3 kg, and feed on highly dispersed food resources across the southern ocean. GPS-tracking of 40 wandering albatrosses from the Crozet archipelago during the incubation phase confirmed foraging movements of between 475-4705 km, which give birds access to a variety of prey, including fishery wastes. Moreover, using miniaturized, autonomous data recorders placed in the stomach of three birds, we performed the first-ever measurements of gastric pH and temperature in procellariformes. These revealed surprisingly low pH levels (average 1.50±0.13), markedly lower than in other seabirds, and comparable to those of vultures feeding on carrion. Such low stomach pH gives wandering albatrosses a strategic advantage since it allows them a rapid chemical breakdown of ingested food and therefore a rapid digestion. This is useful for feeding on patchy, natural prey, but also on fishery wastes, which might be an important additional food resource for wandering albatrosses.