Heterospecific competitors and seasonality can affect host physiology and behavior: key factors in disease transmission

Treatment of acute pharyngitis in rats with season tea decoctions from traditional Chinese medicine through a synergistic and subtle regulation of ARNTL and BHLHE40

ETHNOPHARMACOLOGICAL RELEVANCE

While the seasonal variations in the human immune function and many infectious diseases are well-known, to develop therapeutic strategies regarding such seasonality is quite challenging. However, some traditional medical practices have already taken the seasonality into account, such as the "Season Tea" (ST) decoctions investigated in the present study.

AIM OF THE STUDY

We present a study of the ST decoctions from traditional Chinese medicine, which include four formulae designed for the four seasons, aiming to investigate their pharmacological commonality and distinction.

MATERIALS AND METHODS

A rat model of acute pharyngitis was utilized for the pharmacological study, and the effects of the ST decoctions were evaluated through histology, biomedical assays, microarray analysis, real-time quantitative PCR and Western blot.

RESULTS

The experimental data show that all of the four ST formulae display good pharmaceutical effects on acute pharyngitis, and circadian rhythm appears to be a significant pathway for investigating their pharmacological commonality and distinction. Specifically, while all of the four ST decoctions can regulate the circadian-rhythm-related genes ARNTL and BHLHE40, the regulation is along different directions with the modification of the supplements and the substrates in each ST formula.

CONCLUSION

These results indicate the correlation between the acute pharyngitis and circadian rhythm, and illustrate the possibility of synergistically and subtly regulating ARNTL and BHLHE40, which is significant for relevant drug development.

Activity patterns and interactions of rodents in an assemblage composed by native species and the introduced black rat: implications for pathogen transmission

Background

The degree of temporal overlap between sympatric wild hosts species and their behavioral interactions can be highly relevant to the transmission of pathogens. However, this topic has been scantly addressed. Furthermore, temporal overlap and interactions within an assemblage of wild rodents composed of native and introduced species have been rarely discussed worldwide. We assessed the nocturnal activity patterns and interactions between rodent taxa of an assemblage consisting of native species (Oligoryzomys longicaudatus, Abrothrix hirta, and Abrothrix olivaceus) and the introduced black rat (Rattus rattus) in a temperate forest from southern Chile. All rodent species in this study are known hosts for various zoonotic pathogens.

Results

We found a high nocturnal temporal overlap within the rodent assemblage. However, pairwise comparisons of temporal activity patterns indicated significant differences among all taxa. Rattus rattus showed aggressive behaviors against all native rodents more frequently than against their conspecifics. As for native rodents, agonistic behaviors were the most common interactions between individuals of the same taxon and between individuals of different taxa (O. longicaudatus vs Abrothrix spp.).

Conclusions

Our findings reveal several interactions among rodent taxa that may have implications for pathogens such as hantaviruses, Leptospira spp., and vector-borne pathogens. Furthermore, their transmission may be facilitated by the temporal overlap observed between rodent taxa.

Expanding the frame around social dynamics and glucocorticoids: From hierarchies within the nest to competitive interactions among species

The effect of the social environment on individual state or condition has largely focused on glucocorticoid levels (GCs). As metabolic hormones whose production can be influenced by nutritional, physical, or psychosocial stressors, GCs are a valuable (though singular) measure that may reflect the degree of "stress" experienced by an individual. Most work to date has focused on how social rank influences GCs in group-living species or how predation risk influences GCs in prey. This work has been revealing, but a more comprehensive assessment of the social environment is needed to fully understand how different features of the social environment influence GCs in both group living and non-group living species and across life history stages. Just as there can be intense within-group competition among adult conspecifics, it bears appreciating there can also be competition among siblings from the same brood, among adult conspecifics that do not live in groups, or among heterospecifics. In these situations, dominance hierarchies typically emerge, albeit, do dominants or subordinate individuals or species have higher GCs? We examine the degree of support for hypotheses derived from group-living species about whether differential GCs between dominants and subordinates reflect the "stress of subordination" or "costs of dominance" in these other social contexts. By doing so, we aim to test the generality of these two hypotheses and propose new research directions to broaden the lens that focuses on social hierarchies and GCs.

Physiological links with behavior and fitness: The acute adrenocortical response predicts trappability but not survival in male and female deermice

The "Cort-Fitness" hypothesis predicts a negative relationship between baseline glucocorticoids (GCs) and fitness, although evidence for this hypothesis remains mixed. Such ambiguity could partially exist because blood GCs, typically used in field studies, can fluctuate too rapidly to measure accurately, while the relationship between GCs and trappability is often neglected. Here, by addressing these factors, we examined relationships between GC measures and survival of North American deermice (Peromyscus maniculatus; hereafter deermice) as a model system. To do this, we used more stable GC measures, including the integrated measures of baseline and stress response fecal corticosterone metabolites (FCMs), and downstream measures of neutrophil/lymphocyte ratio (N/L ratio), and body condition score (BCS), to characterize their relationships with survival and trappability. Over two years, deermice were live-trapped monthly, evaluated for BCS, and sampled for feces and blood. Stress response FCMs were evaluated only at first capture. Mark-recapture models, with GC measures as predictors of either survival or trappability, were compared to identify top models. We found that stress response FCMs negatively predicted trappability, and weaker evidence that BCS positively predicted survival. Although the latter provides some support for the "Cort-Fitness" hypothesis, there was no support when using integrated measures. Instead, our findings suggest that deermice with a lower adrenocortical response (i.e. stress response FCMs) were more likely to be captured. Therefore, GC-trappability relationships must be investigated in field studies to avoid linking the wrong GC profile to fitness, and physiological measures other than blood GCs may be useful for detecting GC-fitness patterns.