Ecophysiology of egg rejection in hosts of avian brood parasites:new insights and perspectives

Egg rejection is the most effective and widespread defense used by host species to counteract the extreme fitness costs frequently imposed by obligate avian brood parasites.Yet,the proximate mechanisms underlying between-and within-individual variation in host responses remain poorly explored.Emerging evidence suggests that egg rejection is dependent on individual physiological states,and draws attention to the role of hormones as mediators of flexible antiparasitic responses.In this perspective article,I outline recent advances in our understanding of the proximate factors that mediate egg rejection.I also point out some areas where knowledge remains still lacking,especially those related to the development and maintenance of effective cognitive functions,the potential role of oxidative stress,immunological state,and developmental stressors.I propose new hypotheses that stimulate future research on behavioral host responses toward brood parasitism.

Feather content of porphyrins in Eurasian eagle owl(Bubo bubo)fledglings depends on body condition and breeding site quality

Porphyrins are pigments produced in most animal cells during the synthesis of heme,but their importance for external coloration is unclear.Owls(Order Strigiformes)are among the few animals that accumulate porphyrins in the integument,where it could serve as a means of signaling.Here we hypothesized that the porphyrin content of feathers may depend on body condition and breeding site quality in Eurasian eagle owl(Bubo bubo)fledglings and,thus,constitute amplifiers of the quality of the area where they are born.Using high-performance liquid chromatography,we found 2 porphyrins(protoporphyrin IX and coproporphyrin III)in the body feathers of 19 eagle owl fledglings from 7 breeding territories.Coproporphyrin III,but not protoporphyrin IX feather concentration,was positively associated with the body mass of fledglings and with the quality of the breeding sites where they were reared with respect to food quality and availability.As coproporphyrin III is produced under oxidative stress,we suggest that good breeding sites may lead to fledglings in good condition.This,in turn,may make fledglings induce a certain level of free radical and coproporphyrin III production to signal to conspecifics their site-mediated capacity to cope with oxidative stress.This is the first time that porphyrin content in the integument has been found to be related to individual quality,opening a new scenario for studying evolution of animal coloration.

Rice tissue-specific promoters and conditiondependent promoters for effective translational application

Rice （Oryza sativa） is one of the most important staple food crops for more than half of the world＇s population. The demand is increasing for food security because of population growth and environmental challenges triggered by climate changes. This scenario has led to more interest in developing crops with greater productivity and sustainability. The process of genetic transformation, a major tool for crop improvement, utilizes promoters as one of its key elements. Those promoters are generally divided into three types： constitutive, spatiotemporal, and condition-dependent. Tran- scriptional control of a constitutive promoter often leads to reduced plant growth, due to a negative effect of accumu- lated molecules during cellular functions or energy consump- tion. To maximize the effect of a transgene on transgenic plants, it is better to use condition-dependent or tissue- specific promoters. However, until now, those types have not been as widely applied in crop biotechnology. In this review, we introduce and discuss four groups of tissue-specific promoters （5o promoters in total） and six groups of condition-dependent promoters （27 promoters）. These pro- moters can be utilized to fine-tune desirable agronomic traits and develop crops with tolerance to various stresses, enhanced nutritional value, and advanced productivity.

Complex courtship success and plasticity environments displays facilitate in signaling across male reproductive variable

Effective signal transmission is essential for communication. In environments where signal transmission is highly variable, signalers may utilize complex signals, which incorporate multiple components and modalities, to maintain effective communication. Male Rabidosa rabida wolf spiders produce complex courtship signals, consisting of both visual and seismic components. We test the hypothesis that the complex signaling of R. rabida contributes to male reproductive success in variable signaling environments. We first examine the condition-dependence of foreleg ornamentation （a presumed visual signal） and seismic signal components and find that both may provide potentially redundant information on foraging history. Next, we assessed reproductive success across manipulated signaling environments that varied in the effectiveness of visual and/or seismic signal transmission. In environments where only one signal could be successfully transmitted （e.g., visual or seismic）, pairs were still able to successfully copulate. Additionally, we found that males altered their courtship display depending on the current signaling environment. Specifically, males reduced their use of a visual display component in signaling environments where visual signal transmission was ablated. Incorporating signals in multiple modalities not only enables R. rabida males to maintain copulation success across variable signaling environments, but it also enables males to adjust their composite courtship display to current signaling conditions .