Body‐mass‐dependent trade‐off between immune response and uropygial gland size in house sparrows Passer domesticus

Parasites greatly impact host fitness. The immune system is fundamental to combat endoparasites, and survival increases with greater investment in immunity. Some ectoparasites, by contrast, are reportedly combated by the use of the uropygial gland, an organ exclusive to birds, which secretes an oily substance (preen oil) that is spread on plumage. However, both mounting an immune response against a parasite and producing uropygial gland secretion depend on the same resources, a situation which may induce trade‐offs between the two antiparasitic functions. In this study, I experimentally test whether immune response is traded off against uropygial gland size in the house sparrow Passer domesticus. In the experiment, a group of sparrows were injected with an antigen (lipopolysaccharide, LPS), which stimulates the immune system, while the other group received a sham injection. The uropygial gland of LPS‐treated birds decreased significantly more than that of the control birds after treatment. Nevertheless, the effect of the treatment was limited to house sparrows with low body mass, suggesting that heavy house sparrows were able to produce an immune response while maintaining a relatively large uropygial gland. Given that uropygial gland size is strongly related to production of preen oil, these results suggest that preen oil production declines in birds in poor body condition when resources are preferentially diverted to other demanding functions, such as the immune system. Considering that the uropygial gland is involved in several fitness‐related processes in birds, the trade‐off between immune response and uropygial gland size may have important consequences for bird life histories.     

Competing Lipid-Protein and Protein-Protein Interactions Determine Clustering and Gating Patterns in the Potassium Channel from Streptomyces lividans (KcsA)

There is increasing evidence to support the notion that membrane proteins, instead of being isolated components floating in a fluid lipid environment, can be assembled into supramolecular complexes that take part in a variety of cooperative cellular functions. The interplay between lipid-protein and protein-protein interactions is expected to be a determinant factor in the assembly and dynamics of such membrane complexes. Here we report on a role of anionic phospholipids in determining the extent of clustering of KcsA, a model potassium channel. Assembly/disassembly of channel clusters occurs, at least partly, as a consequence of competing lipid-protein and protein-protein interactions at nonannular lipid binding sites on the channel surface and brings about profound changes in the gating properties of the channel. Our results suggest that these latter effects of anionic lipids are mediated via the Trp⁶⁷–Glu⁷¹–Asp⁸⁰ inactivation triad within the channel structure and its bearing on the selectivity filter.     

Nonsteroidal 2,3-dihydroquinoline glucocorticoid receptor agonists with reduced PEPCK activation

Continuing studies based on dihydroquinoline glucocorticoid receptor agonists lead to the discovery of a series of C4-oxime analogs. Representative compounds exhibited potent transrepression activity with minimal transactivation of phosphoenolpyruvate caboxykinase (PEPCK), a key protein in the gluconeogenesis pathway. These compounds represent promising leads in identifying GR agonists with high anti-inflammatory activity and attenuated potential for glucose elevation.     

Selenium accumulation in plants--phytotechnological applications and ecological implications

Selenium (Se) is an essential trace element for many organisms including humans, yet toxic at higher levels. Both Se deficiency and toxicity are problems worldwide. Since plants readily accumulate and volatilize Se, they may be used both as a source of dietary Se and for removing excess Se from the environment. Plant species differ in their capacity to metabolize and accumulate Se, from non-Se accumulators (< 100 mg Se/kg DW), to Se-accumulators (100-1000 mg Se/kg DW) to Se hyperaccumulators (> 1,000 mg Se/kg DW). Here we review plant mechanisms of Se metabolism in these various plant types. We also summarize results from genetic engineering that have led to enhanced plant Se accumulation, volatilization, and/or tolerance, including field studies. Before using Se-accumulating plants at a large scale we need to evaluate the ecological implications. Research so far indicates that plant Se accumulation significantly affects the plant's ecological interactions below and above ground. Selenium canprotect plants from fungal pathogens and from a variety of invertebrate and vertebrate herbivores, due to both deterrence and toxicity. However, specialist (Se-tolerant herbivores), detritivores and endophytes appear to utilize Se hyperaccumulator plants as a resource. These findings are relevant for managing phytoremediation of Se and similar elements.     

B-group vitamin production by lactic acid bacteria--current knowledge and potential applications

Although most vitamins are present in a variety of foods, human vitamin deficiencies still occur in many countries, mainly because of malnutrition not only as a result of insufficient food intake but also because of unbalanced diets. Even though most lactic acid bacteria (LAB) are auxotrophic for several vitamins, it is now known that certain strains have the capability to synthesize water-soluble vitamins such as those included in the B-group (folates, riboflavin and vitamin B(12) amongst others). This review article will show the current knowledge of vitamin biosynthesis by LAB and show how the proper selection of starter cultures and probiotic strains could be useful in preventing clinical and subclinical vitamin deficiencies. Here, several examples will be presented where vitamin-producing LAB led to the elaboration of novel fermented foods with increased and bioavailable vitamins. In addition, the use of genetic engineering strategies to increase vitamin production or to create novel vitamin-producing strains will also be discussed. This review will show that the use of vitamin-producing LAB could be a cost-effective alternative to current vitamin fortification programmes and be useful in the elaboration of novel vitamin-enriched products.     

Combined methods to detect pollution effects on shell shape and structure in Neogastropods

Tributyltin (TBT) has been widely used as antifouling in marine environments, producing imposex in gastropod females (i.e. neoformation of a vas deferens and/or a penis) and shell malformations in bivalves. However, effects of TBT and other pollutants from high marine traffic zones on the shell of gastropods have been little explored. Shell shape in volutids Odontocymbiola magellanica from a harbor polluted site (P) has been compared with that of animals from a non-polluted location (NP) using 3D geometric morphometrics. Also, the microstructure and density of shells from both populations were analyzed. Prior studies made in the same area (Golfo Nuevo, Patagonia, Argentina) based on traditional multivariate morphometrics showed some differences in size but was unable to detect differences in shell shape among O. magellanica from P and NP areas. Departing from 3D geometric morphometrics, scanning electron microscopy (SEM) and computed tomography (CT) techniques, we have registered the presence of patent differences on shell shape and structure in animals from polluted (P) and non-polluted (NP) areas. In 100% of shells from the NP area we register three calcium carbonate layers (prismatic, cross lamellar and amorphous) and higher densities, while in 50% of the shells collected at the P area the external layer (amorphous) was lacking. Furthermore, a body weight loss of around 30% and a shell weight loss of 20% were registered in animals from the P area. Our combined results suggest that the coordinated use of 3D geometrics morphometrics, CT scan and SEM could be of great utility in order to detect the effect of environmental variables on Neogastropods shell shape and structure.     

Behavioural and physiological stress responses to handling in wild guanacos

Both ethology and physiology can provide insights about stress conditions in wild animals during handling. Lama guanicoe (guanaco) is the major large herbivore inhabiting arid zones in Argentina. Since 2005, the Payún Matrú Cooperative, a business established and run by native people, has captured and handled guanacos for shearing at Payunia Reserve, Mendoza Province, Argentina, to market the species’ fibre for clothing and other products. The aim of our study was to evaluate the behavioural and physiological stress responses to handling of wild guanacos during these shearing activities. We evaluated stress conditions in guanacos by monitoring the frequency of agonistic behaviour in the holding corrals, following capture, the rate of vocalisation and agonistic behaviour during handling, and by estimating cortisol levels in handled animals. Crowding increased agonistic behaviour; this appeared to be related to dominance conflicts between males in the corrals. Time of corralling increased rate of agonistic behaviour and vocalisations during handling. The rate of behavioural stress responses was negatively related to cortisol levels in males; which may be due to animal fatigue or because behavioural stress responses may help mitigate physiological stress responses. Incorporating our results into animal welfare practices could help reduce stress conditions in wild guanacos. Our results suggest that both behavioural and physiological responses are important measures of stress in handled animals, and that behavioural stress responses cannot be used as a simple surrogate for glucocorticoid levels.     

ROCK inhibitor Y-27632 suppresses dissociation-induced apoptosis of murine prostate stem/progenitor cells and increases their cloning efficiency

Activation of the RhoA/ROCK signaling pathway has been shown to contribute to dissociation-induced apoptosis of embryonic and neural stem cells. We previously demonstrated that approximately 1 out of 40 Lin(-)Sca-1(+)CD49f(high) (LSC) prostate basal epithelial cells possess the capacities of stem cells for self-renewal and multi-lineage differentiation. We show here that treating LSC cells with the ROCK kinase inhibitor Y-27632 increases their cloning efficiency by 8 fold in an in vitro prostate colony assay. Y-27632 treatment allows prostate colony cells to replate efficiently, which does not occur otherwise. Y-27632 also increases the cloning efficiency of prostate stem cells in a prostate sphere assay and a dissociated prostate cell regeneration assay. The increased cloning efficiency is due to the suppression of the dissociation-induced, RhoA/ROCK activation-mediated apoptosis of prostate stem cells. Dissociation of prostate epithelial cells from extracellular matrix increases PTEN activity and attenuates AKT activity. Y-27632 treatment alone is sufficient to suppress cell dissociation-induced activation of PTEN activity. However, this does not contribute to the increased cloning efficiency, because Y-27632 treatment increases the sphere-forming unit of wild type and Pten null prostate cells to a similar extent. Finally, knocking down expression of both ROCK kinases slightly increases the replating efficiency of prostate colony cells, corroborating that they play a major role in the Y-27632 mediated increase in cloning efficiency. Our study implies that the numbers of prostate cells with stem/progenitor activity may be underestimated based on currently employed assays, supports that dissociation-induced apoptosis is a common feature of embryonic and somatic stem cells with an epithelial phenotype, and highlights the significance of environmental cues for the maintenance of stem cells.     

Correct patterning of the primitive streak requires the anterior visceral endoderm

Anterior-posterior axis specification in the mouse requires signalling from a specialised extra-embryonic tissue called the anterior visceral endoderm (AVE). AVE precursors are induced at the distal tip of the embryo and move to the prospective anterior. Embryological and genetic analysis has demonstrated that the AVE is required for anterior patterning and for correctly positioning the site of primitive streak formation by inhibiting Nodal activity. We have carried out a genetic ablation of the Hex-expressing cells of the AVE (Hex-AVE) by knocking the Diphtheria toxin subunit A into the Hex locus in an inducible manner. Using this model we have identified that, in addition to its requirement in the anterior of the embryo, the Hex-AVE sub-population has a novel role between 5.5 and 6.5dpc in patterning the primitive streak. Embryos lacking the Hex-AVE display delayed initiation of primitive streak formation and miss-patterning of the anterior primitive streak. We demonstrate that in the absence of the Hex-AVE the restriction of Bmp2 expression to the proximal visceral endoderm is also defective and expression of Wnt3 and Nodal is not correctly restricted to the posterior epiblast. These results, coupled with the observation that reducing Nodal signalling in Hex-AVE ablated embryos increases the frequency of phenotypes observed, suggests that these primitive streak patterning defects are due to defective Nodal signalling. Together, our experiments demonstrate that the AVE is not only required for anterior patterning, but also that specific sub-populations of this tissue are required to pattern the posterior of the embryo.     

Novel pathway of adipogenesis through cross-talk between adipose tissue macrophages, adipose stem cells and adipocytes: evidence of cell plasticity

Introduction

Previous studies highlight a complex relationship between lineage and phenotype for adipose tissue macrophages (ATMs), adipose stem cells (ASCs), and adipocytes, suggesting a high degree of plasticity of these cells. In the present study, using a novel co-culture system, we further characterized the interaction between ATMs, ASCs and adipocytes.

Research Design and Methods

Human adipocytes and the stromal vascular fraction containing ATMs and ASCs were isolated from human adipose tissue and co-cultured for 24 hours. FACS was used to characterize ATMs and ASCs before and after co-culture. Preadipocytes generated after co-culture were characterized by immunostaining for DLK (preadipocytes), CD14 and CD68 (ATMs), CD34 (ASCs), and Nile Red staining for lipid drops. qRT-PCR was used to quantify adipogenic markers such as C/EBPα and PPARγ. A novel fluorescent nanobead lineage tracing method was utilized before co-culture where fluorescent nanobeads were internalized by CD68 (+) ATMs.

Results

Co-culture of adipocytes with ATMs and ASCs increased the formation of new preadipocytes, thereby increasing lipid accumulation and C/EBPα and PPARγ gene expression. Preadipocytes originating after co-culture were positive for markers of preadipocytes, ATMs and ASCs. Moreover, fluorescent nanobeads were internalized by ATMs before co-culture and the new preadipocytes formed after co-culture also contained fluorescent nanobeads, suggesting that new preadipocytes originated in part from ATMs. The formation of CD34(+)/CD68(+)/DLK (+) cell spheres supported the interaction of ATMs, ASCs and preadipocytes.

Conclusions

Cross-talk between adipocytes, ATMs and ASCs promotes preadipocyte formation. The regulation of this novel adipogenic pathway involves differentiation of ATMs to preadipocytes. The presence of CD34(+)/CD68(+)/DLK(+) cells grouped in spheres suggest that paracrine interactions between these cell types plays an important role in the generation and proliferation of new preadipocytes. This phenomenon may reflect the in vivo plasticity of adipose tissue in which ATMs play an additional role during inflammation and other disease states. Understanding this novel pathway could influence adipogenesis, leading to new treatments for obesity, inflammation, and type 2 diabetes.