Trail‐sharing among tropical ants: interspecific use of trail pheromones?

1. Trail‐sharing between different ant species is rare and restricted to a small number of species pairs. Its underlying mechanisms are largely unknown. For trail‐sharing to occur, two factors are required: (i) one or both species must recognise the other species or its pheromone trails and (ii) both species must tolerate each other to a certain extent to allow joint use of the trail. A species that follows another's trails can efficiently exploit the other's information on food sources contained in the pheromone trails. Hence, food competition and thus aggressive interactions between a species following another's trail and the species being followed, seem likely. 2. In the present study, we investigated interspecific trail following and interspecific aggression in trail sharing associations (i) among Polyrhachis ypsilon, Camponotus saundersi, and Dolichoderus cuspidatus, and (ii) among Camponotus rufifemur and Crematogaster modiglianii. We tested whether trail‐sharing species follow each other's pheromone trails, and whether the ants tolerated or attacked their trail‐sharing partners. In both associations, we confronted workers with pheromone trails of their associated species, and, for the former association, measured interspecific aggression among the trail‐sharing species. 3. In our assays, D. cuspidatus and C. rufifemur regularly followed heterospecific pheromone trails of P. ypsilon and C. modiglianii, respectively. However, only few workers of the remaining species followed heterospecific pheromone trails. Thus, shared trails of P. ypsilon and C. saundersi cannot be explained by interspecific trail‐following. 4. Interspecific aggression among P. ypsilon, C. saundersi, and D. cuspidatus was strongly asymmetric, C. saundersi being submissive to the other two. All three species differentiated between heterospecific workers from the same or another site, suggesting habituation to the respective trail‐sharing partners. We therefore hypothesise that differential tolerance by dominant ant species may be mediated by selective habituation towards submissive species and this way determines the assembly of trail‐sharing associations.     

Cryobanking of viable biomaterials: implementation of new strategies for conservation purposes

Cryobanking, the freezing of biological specimens to maintain their integrity for a variety of anticipated and unanticipated uses, offers unique opportunities to advance the basic knowledge of biological systems and their evolution. Notably, cryobanking provides a crucial opportunity to support conservation efforts for endangered species. Historically, cryobanking has been developed mostly in response to human economic and medical needs — these needs must now be extended to biodiversity conservation. Reproduction technologies utilizing cryobanked gametes, embryos and somatic cells are already vital components of endangered species recovery efforts. Advances in modern biological research (e.g. stem cell research, genomics and proteomics) are already drawing heavily on cryobanked specimens, and future needs are anticipated to be immense. The challenges of developing and applying cryobanking for a broader diversity of species were addressed at an international conference held at Trier University (Germany) in June 2008. However, the magnitude of the potential benefits of cryobanking stood in stark contrast to the lack of substantial resources available for this area of strategic interest for biological science — and society at large. The meeting at Trier established a foundation for a strong global incentive to cryobank threatened species. The establishment of an Amphibian Ark cryobanking programme offers the first opportunity for global cooperation to achieve the cryobanking of the threatened species from an entire vertebrate class.     

An ultrastructural immunocytochemical localization of hyalin in the sea urchin egg

The fertilized sea urchin egg is invested by the hyaline layer, a thick extracellular coat which is necessary for normal development. On the basis of ultrastructural studies and the fact that hyalin is released during the time of the cortical reaction, it has been generally accepted that hyalin is derived from the cortical granules. However, this has never been proven definitely, and recently, it has been reported that hyalin is a membrane and/or cell surface protein. To determine where hyalin is stored, we carried out an ultrastructural immunocytochemical localization of hyalin in the unfertilized egg. Hyalin purified from isolated hyaline layers was used to immunize rabbits. Antisera so obtained were shown to be hyalin specific following absorption with a combination of sea urchin proteins. Immunocytochemical localizations were carried out on sections of Epon-embedded material using protein A-coated gold particles as an antibody marker. Our results demonstrate that, prior to fertilization, hyalin is stored in the homogeneous component of the cortical granule in Strongylocentrotus droebachiensis and Strongylocentrotus purpuratus. Labeling of small cortical vesicles in both unfertilized and fertilized eggs, suggests that these vesicles may contain a secondary reservoir of hyalin.     

Influence of teeth, alveoli, and periodontal ligaments on torsional rigidity in human mandibles.

We investigated the influence of teeth, periodontal ligaments, and alveoli on the structural integrity of human mandibles loaded in torsion. Surface bone strain was recorded from the mandibular corpus below the first molar on each of four specimens. These specimens were loaded by an external force that caused primarily torsion about the long axis of the corpus, and bone strain was recorded under the following conditions: 1) all supporting structures intact, 2) all supporting structures intact and the M1 loaded by a simulated bite force, 3) M1 removed and 4) alveolar bone of the M1 removed. For comparative purposes, experiments were also designed to investigate the effects of intermittent holes on the torsional rigidity of a baboon femur. This permitted comparison of the mechanical behavior of the mandibles with that of a more homogeneous bony member. These experiments suggest that the presence of teeth within alveoli has a measurable role in the maintenance of torsional rigidity. The condition of the periodontal ligament also appears to influence these stress-bearing capabilities. Moreover, the alveolar bone supporting the teeth also provides structural support for countering torsional loads. For the specific case of corpus twisting, the mandible does not behave as a member with open or closed sections as predicted by theoretical models. The observed magnitudes of bone strain, however, conform more closely to the predictions generated by a closed-section model.     

拐芹根化学成分研究Ⅱ

从伞型科当归属植物拐芹(Angelica polymorpha Maxim)的根及根茎中又分得4个结晶性化合物。经物理常数测定、光谱分析,分别鉴定为欧前胡素Ⅰ,异氧化前胡内酯Ⅱ,Pabulenol Ⅲ,Phellopterin Ⅳ。     

In vivo bone strain in the mandible of Galago crassicaudatus.

Single element foil strain gages were bonded to mandibular cortical bone in eight specimens of Galago crassicaudatus. The gage was bonded below the Pm4 or M2 adjacent to the lower border of the mandible. The bonded strain gage was connected to form one arm of a Wheatstone bridge. Following recovery from the general anesthetic, the restrained Galago bit either a piece of wood, a food object, or a bite force transducer. During these biting episodes, mandibular bone strain deformed the strain gage and the resulting change in electrical resistance of the gage caused voltage changes across the Wheatstone bridge. These changes, directly proportional to the amount of bone strain along the gage site, were recovered by a strip chart recorder. Bone strain was measured on both the working and balancing sides of the jaws. Maximum values of bone strain and bite force were 435 microstrain (compression) and 8.2 kilograms respectively. During bending of the mandible, the correlation between bone strain (tension or compression) and bite force ranged from -0.893 (tension) to 0.997 (compression). The experiments reported here demonstrate that only a small percentage of the Galago bite force is due to balancing side muscle force during isometric unilateral molar biting. In addition, these experiments demonstrate that the Galago mandible is bent in a predictable manner during biting. The amount of apparent mandibular bone strain is dependent on (1) the magnitude of the bite force and (2) the position of the bite point.     

Assessment of DNA damage and its modulation by dietary and genetic factors in smokers using the Comet assay: a biomarker model

Methods are needed to assess exposure to genotoxins in humans and to improve understanding of dietary cancer prevention. The Comet assay was used to detect smoking-related exposures and dietary modulations in target tissues. Buccal scrapings, blood and faeces were collected from 38 healthy male volunteers (smokers and non-smokers) during a dietary intervention study with bread supplemented with prebiotics±antioxidants. GSTM1-genotype was determined with PCR. Buccal and peripheral lymphocytes were analysed for DNA damage using the Comet assay. Genotoxicity of faecal water (FW) was assayed in human colon HT29 clone 19A cells. 'Tail intensity' (TI) was used as a quantitative indicator of DNA damage in the Comet assay. Intervention with bread reduced DNA damage in lymphocytes of smokers (8.3±1.7% TI versus 10.2±4.1% TI, n=19), but not of non-smokers (8.6±2.8% TI versus 8.3±2.7% TI, n=15). Faecal water genotoxicity was reduced only in non-smokers (9.4±2.9% TI versus 18.9±13.1% TI, n=15) but not in smokers (15.5±10.7% TI versus 20.4±14.1% TI, n=13). The Comet assay was efficient in the detection of both smoking-related exposure (buccal cells) and efficacy of dietary intervention (faecal samples). Smokers and non-smokers profited differently from the intervention with prebiotic bread±antioxidants. Stratification of data by genotype enhanced specificity/sensitivity of the intervention effects and contributed important information on the role of susceptibility.