油松毛虫雌蛾对油松松针两种手性化合物的触角电位反应

采用触角电位技术测定了油松毛虫雌蛾触角对油松挥发物的两对手性单萜的剂量反应,并在饱和剂量下测定了α-蒎烯、β-蒎烯手性化合物及其消旋体的触角电位值。剂量反应测试表明,油松毛虫雌蛾对(-)-α-蒎烯的饱和剂量为1 600 μL,对(+)-α-蒎烯、(+)-β-蒎烯、(-)-β-蒎烯的饱和剂量为800 μL。α-蒎烯右旋异构体的反应值高于(-)-α-蒎烯的反应值,说明(+)-α-蒎烯能够更有效的与感受器中的分子受体结合;β-蒎烯则相反,(-)-β-蒎烯的EAG反应值高于(+)-β-蒎烯,说明β-蒎烯的右旋异构体不能有效的与多数感受器中的分子受体结合。在饱和剂量下的测定结果表明油松毛虫雌蛾对α-蒎烯和β-蒎烯消旋体的反应均与对其手性异构体反应相当,说明油松毛虫雌蛾用同一个感受细胞来接受α-蒎烯的两个对映异构体,同样β-蒎烯的两个对映异构体也是被同一个受体细胞来接受。结果提示,手性化合物的比例可能在油松毛虫寄主识别中有重要作用。     

Ontogeny of hydrocarbon profiles in the ant Aphaenogaster senilis and effects of social isolation

In ants, cuticular hydrocarbons are used for nestmate recognition; they are stored in the postpharyngeal gland and shared among the individuals. Newly emerged ants have a very small quantity of hydrocarbons. We studied the ontogeny of the hydrocarbon profile in Aphaenogaster senilis. The total quantities of both cuticular and postpharyngeal gland (PPG) hydrocarbons increased with age from 0 to 20 days after emergence and then stabilised. These quantities are correlated with the development of the ovary. Under individual social isolation, cuticular hydrocarbons increased as normal, but the total quantity of PPG hydrocarbons never increased from the initial low level. This effect of social isolation on the PPG hydrocarbon level indicates the importance of hydrocarbon transfer between nestmates through the PPG and lends support to the gestalt model of nestmate recognition. To cite this article: K. Ichinose, A. Lenoir, C. R. Biologies 332 (2009).     

Genetics, behaviour and chemical recognition of the invading ant Pheidole megacephala

Introduced species often become ecologically dominant, displacing native species and posing a serious threat to ecosystem function and global biodiversity. Ants are among the most widespread and damaging alien species; introductions are often accompanied by population-level behavioural and genetic changes contributing to their success. We investigated the genetic structure, chemical profile and nestmate recognition in introduced populations of the invasive big-headed ant, Pheidole megacephala, in Australia. Behavioural analyses show that workers are not aggressive towards conspecifics from different nests, even at large geographical scales (up to 3000 km) and between populations encompassing a wide range of environmental conditions. By contrast, interactions with workers of other species invariably result in agonistic behaviours. Genetic analyses reveal that populations have low genetic diversity. No genetic differentiation occurs among nests of the same population; differentiation between populations, though significant, remains weak. Chemical analyses indicate that cuticular lipids are similar between colonies of a population, and that differentiation between populations is low. Altogether, these results indicate that the big-headed ant P. megacephala forms a large unicolonial population across northern/eastern Australia.     

A chemical signal of offspring quality affects maternal care in a social insect

Begging signals of offspring are condition-dependent cues that are usually predicted to display information about the short-term need (i.e. hunger) to which parents respond by allocating more food. However, recent models and experiments have revealed that parents, depending on the species and context, may respond to signals of quality (i.e. offspring reproductive value) rather than need. Despite the critical importance of this distinction for life history and conflict resolution theory, there is still limited knowledge of alternative functions of offspring signals. In this study, we investigated the communication between offspring and caring females of the common earwig, Forficula auricularia, hypothesizing that offspring chemical cues display information about nutritional condition to which females respond in terms of maternal food provisioning. Consistent with the prediction for a signal of quality we found that mothers exposed to chemical cues from well-fed nymphs foraged significantly more and allocated food to more nymphs compared with females exposed to solvent (control) or chemical cues from poorly fed nymphs. Chemical analysis revealed significant differences in the relative quantities of specific cuticular hydrocarbon compounds between treatments. To our knowledge, this study demonstrates for the first time that an offspring chemical signal reflects nutritional quality and influences maternal care.     

Behavioral and Chemical Correlates of Long-Term Queen Adoption in the Facultative Polygynous Ant Ectatomma tuberculatum

In ants, queen adoption is a common way of achieving secondary polygyny but the mechanisms involved are little known. Here we studied the process of long-term adoptions of alien queens in the facultative polygynous ant Ectatomma tuberculatum. In eight out of 10 successful adoption experiments, all the introduced queens showed similar behavior and fecundity as the resident queens even after 2 months, indicating complete integration into the colony. Chemical analysis revealed that the cuticular hydrocarbon profiles of resident and introduced queens were clearly distinct from those of workers and that they did not change after adoption. We propose that queen-specific cuticular hydrocarbon profile may represent a reliable signal of queen’s fertility and discuss about the evolution of high level of queen acceptance in E. tuberculatum.     

Intraspecific nestmate recognition in two parabiotic ant species: acquired recognition cues and low inter-colony discrimination

Parabiotic ants—ants that share their nest with another ant species—need to tolerate not only conspecific nestmates, but also nestmates of a foreign species. The parabiotic ants Camponotus rufifemur and Crematogaster modiglianii display high interspecific tolerance, which exceeds their respective partner colony and extends to alien colonies of the partner species. The tolerance appears to be related to unusual cuticular substances in both species. Both species possess hydrocarbons of unusually high chain lengths. In addition, Cr. modiglianii carries high quantities of hereto unknown compounds on its cuticle. These unusual features of the cuticular profiles may affect nestmate recognition within both respective species as well. In the present study, we therefore examined inter-colony discrimination within the two parabiotic species in relation to chemical differentiation. Cr. modiglianii was highly aggressive against workers from alien conspecific colonies in experimental confrontations. In spite of high inter-colony variation in the unknown compounds, however, Cr. modiglianii failed to differentiate between intracolonial and allocolonial unknown compounds. Instead, the cuticular hydrocarbons functioned as recognition cues despite low variation across colonies. Moreover, inter-colony aggression within Cr. modiglianii was significantly influenced by the presence of two methylbranched alkenes acquired from its Ca. rufifemur partner. Ca. rufifemur occurs in two varieties (‘red’ and ‘black’) with almost no overlap in their cuticular hydrocarbons. Workers of this species showed low aggression against conspecifics from foreign colonies of the same variety, but attacked workers from the respective other variety. The low inter-colony discrimination within a variety may be related to low chemical differentiation between the colonies. Ca. rufifemur majors elicited significantly more inter-colony aggression than medium-sized workers. This may be explained by the density of recognition cues: majors carried significantly higher quantities of cuticular hydrocarbons per body surface.     

Specificity of Lipid Composition in Two Botryococcus Strains,the Producers of Liquid Hydrocarbons

The structure of liquid hydrocarbons and fatty acids produced by the green alga Botryococcus was identified. Two representatives of this alga, Botryococcus braunii Kütz, strain IPPAS H-252, introduced into culture earlier and an organism isolated for the first time from the Shira Lake, were used for this identification. Fatty acid composition of B. braunii, strain H-252, lipids was characterized by a high content of trienoic acids of C16–C18 series. The hydrocarbon composition of this strain was represented by straight-chain and branched-chain C14–C28 components; long-chain linear aliphatic C20–C27 hydrocarbons (54.4%) and 2,6,10,14-tetramethylhexadecane (20.5%) predominated among them. The strain H-252 differed in its fatty acid and hydrocarbon composition from the strains described earlier as Botryococcus braunii. The fatty acid composition of the Botryococcus isolate was represented mainly by C12–C32 saturated and monoenoic acids. The hydrocarbons formed by this isolate were represented by dienoic and trienoic components. C29 (48.9–56.3%) and C31 (11.1–16.3%) hydrocarbons predominated among the C23–C31 dienoic hydrocarbons, and C27, C29, and C31 trienoic hydrocarbons comprised 2.5–2.6% of total hydrocarbons. This type of hydrocarbons and the lipid fatty acid composition were characteristic for the race A of B. braunii.     

Association between the CYP1A1 T3801C polymorphism and risk of cancer: Evidence from 268 case–control studies

T3801C is a common polymorphism in CYP1A1, showing differences in its biological functions. Case–control studies have been performed to elucidate the role of T3801C in cancer, although the results are conflicting and heterogeneous. Hence, we performed a meta-analysis to investigate the association between cancer susceptibility and T3801C (55,963 cases and 76,631 controls from 268 studies) polymorphism in different inheritance models. We used odds ratios with 95% confidence intervals to assess the strength of the association. Overall, significantly increased cancer risk was observed in any genetic model (dominant model: odds ratio [OR] = 1.14, 95% confidence interval [CI] = 1.09–1.19; recessive model: OR = 1.23, 95% CI = 1.12–1.34; CC vs. TT: OR = 1.31, 95% CI = 1.19–1.45; TC vs. TT: OR = 1.12, 95% CI = 1.07–1.18; additive model: OR = 1.14, 95% CI = 1.09–1.19) when all eligible studies were pooled into the meta-analysis. In further stratified and sensitivity analyses, the elevated risk remained for subgroups of cervical cancer, head and neck cancer, hepatocellular cancer, leukemia, lung cancer, prostate cancer and breast cancer. In addition, significantly decreased colorectal cancer risk was also observed. In summary, this meta-analysis suggests that the participation of CYP1A1 T3801C is a genetic susceptibility for some cancer types. Moreover, our work also points out the importance of new studies for T3801C association in some cancer types, such as gallbladder cancer, Asians of acute myeloid leukemia, and thyroid cancer, where at least some of the covariates responsible for heterogeneity could be controlled, to obtain a more conclusive understanding about the function of the CYP1A1 T3801C polymorphism in cancer development.     

Chemical deception among ant social parasites

Deception is widespread throughout the animal kingdom and various deceptive strategies are exemplified by social parasites. These are species of ants, bees and wasps that have evolved to invade, survive and reproduce within a host colony of another social species. This is achieved principally by chemical deception that tricks the host workers into treating the invading parasite as their own kin. Achieving levels of acceptance into typically hostile host colonies requires an amazing level of decep- tion as social insects have evolved complex species- and colony-specific recognition systems. This allows the detection of for- eigners, both hetero- and con-specific. Therefore, social parasitic ants not only have to overcome the unique species recognition profiles that each ant species produces, but also the subtle variations in theses profiles which generate the colony-specific profiles We present data on the level of chemical similarity between social parasites and their hosts in four different systems and then discuss these data in the wider context with previous studies, especially in respect to using multivariate statistical methods when looking for differences in these systems.