Why animals lie: how dishonesty and belief can coexist in a signaling system

We develop and apply a simple model for animal communication in which signalers can use a nontrivial frequency of deception without causing listeners to completely lose belief. This common feature of animal communication has been difficult to explain as a stable adaptive outcome of the options and payoffs intrinsic to signaling interactions. Our theory is based on two realistic assumptions. (1) Signals are "overheard" by several listeners or listener types with different payoffs. The signaler may then benefit from using incomplete honesty to elicit different responses from different listener types, such as attracting potential mates while simultaneously deterring competitors. (2) Signaler and listener strategies change dynamically in response to current payoffs for different behaviors. The dynamic equations can be interpreted as describing learning and behavior change by individuals or evolution across generations. We explain how our dynamic model differs from other solution concepts from classical and evolutionary game theory and how it relates to general models for frequency-dependent phenotype dynamics. We illustrate the theory with several applications where deceptive signaling occurs readily in our framework, including bluffing competitors for potential mates or territories. We suggest future theoretical directions to make the models more general and propose some possible experimental tests.     

Crucial role of position 40 for interactions of CCK-58 revealed by sequence of cat CCK-58

Evidence suggests that amino terminal extensions of CCK-8 affect the carboxyl terminal bioactive region of CCK. Cat CCK-58 was purified by low pressure reverse phase and ion-exchange chromatography steps and several reverse phase HPLC steps. The purified peptide and its tryptic fragments were characterized by mass spectral analysis and microsequence analysis. The structure of cat CCK-58 is: AVQKVDGEPRAHLGALLARYIQQARKAPSGRMSVIKNLQSLDPSHRISDRDY(SO3) MGWMDF-amide. Cat and dog CCK-58 are identical except for position 40 which is serine in cat and asparagine in dog. Radioimmunoassay detected cat CCK-58 about 1/10th as well as dog CCK-58, indicating a marked effect on C-terminal immunoreactivity. Cat CCK-58 with a serine at position 40, the same residue found in pig, mouse, cow and rabbit CCK-58, can be used as a unique bioprobe for defining how amino terminal amino acids influence the structure and bioactivity of the carboxyl terminal region of CCK.     

Gender differences in UV-induced inflammation and immunosuppression in mice reveal male unresponsiveness to UVA radiation

Immunosuppression attributed mainly to the UVB (290-320 nm) waveband is a prerequisite for skin cancer development in mice and humans. The contribution of UVA (320-400 nm) is controversial, but in mice UVA irradiation has been found to antagonise immunosuppression by UVB. In other studies of photoimmune regulation, protection mediated via oestrogen receptor-β signalling was identified as a normal endogenous defence in mice, and was shown to depend on UVA irradiation. A gender bias in photoimmune responsiveness was thus suggested, and is tested in this study by comparing the UV-induced inflammatory and immune responses in male and female hairless mice. We report that male mice, which show greater skin thickness than females, developed a less intense but slower resolving sunburn inflammatory oedema, correlated with reduced epidermal expression of pro-inflammatory IL-6 than females following solar simulated UV (SSUV, 290-400 nm) exposure. On the other hand, the contact hypersensitivity reaction (CHS) was more severely suppressed by SSUV in males, correlated with increased epidermal expression of immunosuppressive IL-10. Exposure to the UVB waveband alone, or to cis-urocanic acid, suppressed CHS equally in males and females. However, whereas UVA irradiation induced immunoprotection against either UVB or cis-urocanic acid in females, this protection was significantly reduced or abrogated in males. The results indicate that males are compromised by a relative unresponsiveness to the photoimmune protective effects of UVA, alone or as a component of SSUV. This could explain the known gender bias in skin cancer development in both mice and humans.     

Fine-scale genetic population structure of southern pine beetle (Coleoptera: Curculionidae) in Mississippi forests

The southern pine beetle, Dendroctonus frontalis Zimmerman, is the most destructive insect pest of pine forests in the southeastern United States, Mexico, and Central America. Southern pine beetle aggressively attacks pine trees, and when in epidemic stages, they are capable of killing even the most healthy pine trees in a short period of time. Despite the amount of destruction caused by the southern pine beetle and the amount of monetary loss faced by the timber industry and recreation, the population genetics of this species has been limited to comparisons among distant geographic locations. This study investigates the fine-scale genetic population structure of the southern pine beetle in Mississippi. Very little genetic differentiation was observed among samples. Bayesian assignment testing failed to detect multiple groups within all samples; estimates of genetic differentiation and genetic distance were very low in magnitude; and a Mantel test did not reveal a significant relationship between genetic distance and geographic distance. These results suggest that management of the southern pine beetle needs to consider the potential movements of individuals within and among national forests and should be focused on a large scale, at least as big as continuously forested areas and possibly even multiple forests. These results further suggest that removal of beetle-infested trees is important.     

An Adaptable Staining Schedule for Plant Tissues

A general schedule for staining meristematic, maturing, and mature plant tissues is described. Treatment with a dilute aqueous solution of Delafield's hematoxylin is followed with staining in 0.1% safranin in 60% alcohol. Destaining of safranin may be partly accomplished in alcohol and completed by counterstaining with dilute fast green FCF in a xylene and alcohol mixture. Various modifications and adaptations are briefly discussed.