Antiphonal call timing in marmosets is behaviorally significant: interactive playback experiments

Studies of primate vocal communication systems have generally focused on vocalizations and the information they convey to conspecifics. But the vocalizations are not the only sources of information. Aspects of each species vocal behaviors are likely to be communicatively rich as well. During vocal interactions, for example, the latency delay between the calls could communicate an important message to the signal receiver, such as an interest and willingness to socialize. Here we employed novel, interactive playback software to address this issue in the antiphonal calling behavior of common marmosets. In these experiments, we parametrically varied the latency delay of antiphonal call stimuli and measured its effects on subjects’ resultant vocal behavior. Results showed that marmosets produced successively fewer antiphonal call responses during test conditions with increasing latency delays. Moreover, although subjects produced significantly more antiphonal than spontaneous calls in conditions with antiphonal call timing delays up to 9 s, a longer delay resulted in a significant decline in calling. These data suggest that antiphonal call timing is a salient cue for maintaining antiphonal calling interactions and may be used by marmosets to determine whether a subsequent call is produced in response to or independently of their own.     

Comparative <Emphasis Type="Italic">in vivo</Emphasis> infection models yield insights on early host immune response to Campylobacter in chickens

Salmonella typhimurium and Campylobacter jejuni pose significant risks to human health and poultry are a major vector for infection. Comparative in vivo infection models were performed to compare the avian host immune response to both bacterial species. Forty-five commercial broiler chickens were orally challenged with either C. jejuni or S. typhimurium whilst 60 similar control birds were mock challenged in parallel. Birds were sacrificed at 0, 6, 20 and 48 h post-infection and cloacal swabs, blood and tissue samples taken. Peripheral blood leukocytes were isolated for flow cytometric analyses and RNA was extracted for gene expression profiling. Colonisation patterns were markedly different between the two bacterial species, with systemic colonisation of Campylobacter outside the gastrointestinal tract. Salmonella infection induced significant changes in circulating heterophil and monocyte/macrophage populations, whilst Campylobacter infection had no effect on the heterophil numbers but caused a significant early increase in circulating monocytes/macrophages. Toll-like receptor 1 (TLR1) gene expression was decreased, and avian β-defensin (AvBD) gene expression (AvBD3, AvBD10 and AvBD12) was significantly increased in response to Salmonella infection (P < 0.05). In contrast, Campylobacter infection induced increased TLR21 gene expression but significantly reduced expression of seven antimicrobial peptide (AMP) genes (AvBD3, AvBD4, AvBD8, AvBD13, AvBD14, CTHL2 and CTHL3; P < 0.05). Considered together, microbiological, cellular and gene expression profiles indicate that the innate immune system responds differently to Salmonella and to Campylobacter infection. Furthermore, reduction in the expression of AMPs may play a role in the persistence of high level colonisation of the host by Campylobacter. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Evolutionary Divergence in Brain Size between Migratory and Resident Birds

Despite important recent progress in our understanding of brain evolution, controversy remains regarding the evolutionary forces that have driven its enormous diversification in size. Here, we report that in passerine birds, migratory species tend to have brains that are substantially smaller (relative to body size) than those of resident species, confirming and generalizing previous studies. Phylogenetic reconstructions based on Bayesian Markov chain methods suggest an evolutionary scenario in which some large brained tropical passerines that invaded more seasonal regions evolved migratory behavior and migration itself selected for smaller brain size. Selection for smaller brains in migratory birds may arise from the energetic and developmental costs associated with a highly mobile life cycle, a possibility that is supported by a path analysis. Nevertheless, an important fraction (over 68%) of the correlation between brain mass and migratory distance comes from a direct effect of migration on brain size, perhaps reflecting costs associated with cognitive functions that have become less necessary in migratory species. Overall, our results highlight the importance of retrospective analyses in identifying selective pressures that have shaped brain evolution, and indicate that when it comes to the brain, larger is not always better.     

Glycosaminoglycans as regulators of stem cell differentiation

ES (embryonic stem) cell differentiation is dependent on the presence of HS (heparan sulfate). We have demonstrated that, during differentiation, the evolution of specific cell lineages is associated with particular patterns of GAG (glycosaminoglycan) expression. For example, different HS epitopes are synthesized during neural or mesodermal lineage formation. Cell lines mutant for various components of the HS biosynthetic pathway are selectively impaired in their differentiation, with lineage-specific effects observed for some lines. We have also observed that the addition of soluble GAG saccharides to cells, with or without cell-surface HS, can influence the pace and outcome of differentiation, again highlighting specific pattern requirements for particular lineages. We are combining this work with ongoing studies into the design of artificial cell environments where we have optimized three-dimensional scaffolds, generated by electrospinning or by the formation of hydrogels, for the culture of ES cells. By permeating these scaffolds with defined GAG oligosaccharides, we intend to control the mechanical environment of the cells (via the scaffold architecture) as well as their biological signalling environment (using the oligosaccharides). We predict that this will allow us to control ES cell pluripotency and differentiation in a three-dimensional setting, allowing the generation of differentiated cell types for use in drug discovery/testing or in therapeutics.     

New magnetic resonance contrast agents as biochemical reporters

Magnetic resonance imaging is a noninvasive, volume rendering diagnostic technique that uses lanthanide complexes to enhance proton relaxation. Magnetic resonance imaging is not limited by light scattering as optical microscopic techniques are, and allows imaging of whole animals. Clinical contrast agents are nonspecific and report solely on anatomy, whereas contrast agents that can be activated can be tailored to report on the physiological status or metabolic activity of biological systems. These new classes of magnetic resonance contrast agents represent a substantial leap in the type of information that can be derived from imaging experiments, and are the focus of this review.     

Plasma and erythrocyte membrane long chain polyunsaturated fatty acids in endogenous depression

Patients suffering from endogenous depression had significantly greater proportions of long chain polyunsaturated fatty acids (LCP), docosahexaenoic acid (22:6ω3) and eicosapentaenoic acid (20:5ω3), and a reduced proportion of linoleic acid (18:2ω6) in their plasma choline phosphoglycerides (CPG) compared with age-sex-matched healthy controls. Patients suffering from reactive depression or from other psychiatric disorders did not differ significantly from matched controls. Changes in the fatty acid composition of the major erythrocyte membrane phospholipids were in the same direction but were less marked. The importance and possible reasons for the elevated LCP in endogenous depression are discussed.     

Relation of fetal and infant growth to plasma fibrinogen and factor VII concentrations in adult life.

OBJECTIVE--To determine whether reduced fetal and infant growth are associated with higher plasma fibrinogen and factor VII concentrations in adult life. DESIGN--Follow up study of men born during 1920-30 whose weights at birth and at 1 year had been recorded by health visitors, and men born during 1935-43 whose size at birth had been measured in detail. SETTING--Hertfordshire and Preston, England. SUBJECTS--591 men born in east Hertfordshire who still lived there and 148 men born in Preston who still lived in or close to the city. MAIN OUTCOME MEASURES--Plasma fibrinogen and factor VII concentrations. RESULTS--Among men in Hertfordshire mean plasma fibrinogen and factor VII concentrations fell with increasing weight at 1 year (from 3.21 g/l in men of less than or equal to 18 lb to 2.93 g/l in men greater than or equal to 27 lb and from 122% of standard to 103%; p less than 0.001, p less than 0.005 respectively). The trends were independent of cigarette smoking, alcohol consumption, body mass index, and social class. Neither plasma fibrinogen nor factor VII concentration was related to birth weight. In men in Preston, however, fibrinogen concentration fell progressively as the ratio of placental weight to birth weight decreased (p = 0.01). CONCLUSIONS--Reduced growth in fetal life and infancy is strongly related to high plasma concentrations of the haemostatic factors fibrinogen and factor VII. This may be a persisting response to impaired liver development during a critical early period.