Genetic influence on caste determination underlying the asexual queen succession system in a termite

The question of how reproductives and sterile workers differentiate within eusocial groups has long been a core issue in the study of social insects. Recent studies have shown that not only environmental factors but also genetic factors affect caste differentiation. In the termite Reticulitermes speratus, queens produce their replacements (neotenics) asexually but use normal sexual reproduction to produce other colony members. Here, we demonstrate a genetic influence on caste determination underlying the asexual queen succession system in this termite species. Thelytoky in termites is accomplished by automixis with terminal fusion, yielding almost completely homozygous offspring; thus, parthenogenetically and sexually produced offspring profoundly differ in heterozygosity. An analysis of the relationship between the reproductive dominance of female neotenics obtained from experimentally orphaned colonies and their genotypes at five microsatellite loci showed that homozygosity at two loci influenced the developmental priority and/or reproductive quality of neotenics. These results suggest the existence of a multi-locus system affecting the queen fecundity and explain why parthenogens have genetic priority to become neotenics in this termite species.     

Industrial waste management simulation game and its educational effect

The purposes of this study were to develop the Industrial Waste Game and to examine the validity of this game as a tool for environmental education. The aim of this game is to enable players to understand the social dilemma between individual interest of hazardous dumping and the social cost of purifying pollution, and to find a solution to the social dilemma by providing the monitoring and sanction system for illegal dumping or other efficient systems. The game was played by 213 undergraduate students who were divided into 40 groups of 5 to 6 people. One of 4 combinations of monitoring and penalty conditions was assigned to each group. The players were asked to answer questionnaires concerning their interests and understanding of the industrial waste issue before and after the game to evaluate educational effects. The results indicated that the players increased their awareness of industrial waste problems and came to understand that these problems were caused not by psychological factors such as immorality of the illegal dumper but mainly by social structural factors like the social dilemma. Through playing the game and participating in post-game discussion, players were able to obtain interesting experience and gain motivation to learn more.     

Waterproof and translucent wings at the same time: problems and solutions in butterflies

Although the colour of butterflies attracts the most attention, the waterproofing properties of their wings are also extremely interesting. Most butterfly wings are considered “super-hydrophobic” because the contact angle (CA) with a water drop exceeds 150°. Usually, butterfly wings are covered with strongly overlapping scales; however, in the case of transparent or translucent wings, scale cover is reduced; thus, the hydrophobicity could be affected. Here, we present a comparative analysis of wing hydrophobicity and its dependence on morphology for two species with translucent wings Parantica sita (Nymphalidae) and Parnassius glacialis (Papilionidae). These species have very different life histories: P. sita lives for up to 6 months as an adult and migrates over long distance, whereas P. glacialis lives for less than 1 month and does not migrate. We measured the water CA and analysed wing morphology with scanning electron microscopy and atomic force microscopy. P. sita has super-hydrophobic wing surfaces, with CA > 160°, whereas P. glacialis did not (CA = 100–135°). Specialised scales were found on the translucent portions of P. sita wings. These scales were ovoid and much thinner than common scales, erect at about 30°, and leaving up to 80% of the wing surface uncovered. The underlying bare wing surface had a remarkable pattern of ridges and knobs. P. glacialis also had over 80% of the wing surface uncovered, but the scales were either setae-like or spade-like. The bare surface of the wing had an irregular wavy smooth pattern. We suggest a mode of action that allows this super-hydrophobic effect with an incompletely covered wing surface. The scales bend, but do not collapse, under the pressure of a water droplet, and the elastic recovery of the structure at the borders of the droplet allows a high apparent CA. Thus, P. sita can be translucent without losing its waterproof properties. This characteristic is likely necessary for the long life and migration of this species. This is the first study of some of the effects on the hydrophobicity of translucency through scales’ cover reduction in butterfly wings and on the morphology associated with improved waterproofing. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

泳动床技术处理高浓度废水特性研究

熊本大学自然科学研究院,熊本860-8555,日本     

Function of the major cheliped in male–male competition in the hermit crab <Emphasis Type="Italic">Pagurus nigrofascia</Emphasis>

Functions of the major cheliped in pagurid hermit crabs have been studied in fights for shells. The major cheliped often shows sexual size dimorphism, suggesting that sexual selection favors the development of the male major cheliped. The function of the major cheliped in male–male competition was examined in Pagurus nigrofascia collected from April to June 2009 on the intertidal rocky shore in southern Hokkaido, Japan (41°N, 140°E). Sexual size dimorphism of the major cheliped was observed, and precopulatory guarding males had larger major chelipeds than solitary ones. Guarding males used the major cheliped to deter intruders during competitive interactions. Males without a major cheliped were disadvantaged even if they were larger than opponents and had ownership. Cheliped size affected the outcomes of contests between similar sized males. This suggests that the male major cheliped in P. nigrofascia protects mates from competitors and, consequently, enhances male mating success. Sexual selection may favor the development of the major cheliped in male pagurids.     

Female mate preference for a costly ornament in male guppies

Female mate preference for dorsal fin length in male guppies (Poecilia reticulata) was investigated. In a dichotomous choice experiment using live males, females preferred males with longer dorsal fins to those with shorter dorsal fins. When the dorsal fin lengths of the two males were reversed by surgical manipulation, the females reversed their preference. To further examine this preference behaviour, a second dichotomous choice experiment was conducted using digitally modified male images that differed only in dorsal fin lengths. In this next experiment, females preferred male images with a longer dorsal fin than those with a shorter dorsal fin. In order to clarify the cost of possessing a long dorsal fin for males, the effect of dorsal fin length on swimming performance of males was also examined with a flow chamber. Male swimming performance was enhanced by surgically shortening the dorsal fin. The result of this study suggests that the long dorsal fin of male guppies is a costly handicap that may have evolved due to female mate choice.     

Depositional records of plutonium and (137)Cs released from Nagasaki atomic bomb in sediment of Nishiyama reservoir at Nagasaki

In a sediment core of Nishiyama reservoir at Nagasaki city, depth profiles of (240)Pu/(239)Pu isotopic ratio, (239+240)Pu and (137)Cs activities were determined. Sediments containing plutonium and (137)Cs, which were deposited immediately after a detonation of Nagasaki atomic bomb, were identified in the core. Observed below the sediments were macroscopic charcoals, providing evidence for initial deposit of the fallout of the Nagasaki atomic bomb. This is the first entire depositional records of plutonium and (137)Cs released from the Nagasaki atomic bomb together with those from atmospheric nuclear tests.     

Mechanical behavior of inert waste landfills under seismic condition

Journal of Material Cycles and Waste Management - Mechanical properties and slope stability of inert waste landfills under seismic condition were studied with three different approaches: in-situ...     

Ultraweak photon emission from herbivory-injured maize plants

Following perception of herbivory or infection, plants exhibit a wide range of inducible responses. In this study, we found ultraweak photon emissions from maize leaves damaged by Helicoverpa armigera (Noctuidae). Interestingly, mechanically damaged maize leaves treated with caterpillar regurgitants emitted the same intensity and pattern of photon emissions as those from maize leaves damaged by caterpillars. Furthermore, two-dimensional imaging of the leaf section treated with the oral secretions clearly shows that photon emissions were observed specifically at the lip of the wound exposed to the secretions. These results suggest that the direct interaction between maize leaf cells and chemicals contained in caterpillar regurgitants triggers these photon emissions.     

Microscopic synchrotron X-ray analysis of mercury waste in simulated landfill experiments

Mercury enters into the environment or waste streams because it is present as an impurity in natural minerals. Mercury must be appropriately managed as an hazardous waste. In this study, a waste layer of artificial mercury sulfide mixed with incinerator ash and sewage sludge compost in a simulated landfill experiment for 5 years was analyzed using microscopic synchrotron X-ray to obtain basic knowledge of mercury behavior in a landfill. Mapping by synchrotron X-ray revealed the distribution of mercury-containing particles in the waste layer. In most cases, the movement of mercury sulfide was not considered significant even within a microscopic range; however, water flows could enhance the movement of mercury sulfide particles. When disposing of mercury sulfide, “concentrated placement” or solidification, rather than mixing with other wastes, was more effective at preventing mercury leaching in lysimeters. The chemical form of mercury sulfide in each lysimeter was confirmed by X-ray absorption fine structure (XAFS) analysis, which showed that most of the mercury was present as metacinnabar and had not undergone any changes, indicating that it was extremely stable. The microscopic synchrotron X-ray analysis proved very useful for studying the behavior of mercury waste in a simulated landfill experiment.