Reconciliation and third‐party affiliation in carrion crows

Conflicts are costly because they can damage social relationships. To buffer conflicts, various species use post‐conflict behaviour, such as reconciliation or third‐party affiliation. Both behaviours have predominantly been studied in non‐human primates. However, recently, studies revealed post‐conflict behaviour in other mammalian and some bird species (e.g., corvids). While third‐party affiliation has been reported in several corvid species, reconciliation has only rarely been observed. The social structure of the studied groups has been postulated as a reason for the absence of reconciliation. Here, we investigated whether post‐conflict behaviours in corvids indeed mirror the relationship structure. We studied the behaviour of a newly established group of juvenile carrion crows (Corvus corone corone), where pair bonds had not yet been established. We applied a combination of observations and food monopolisation experiments to quantify the use of post‐conflict behaviours. Provisioning food in one or two pieces induced different patterns of aggression during feeding and differently affected the affiliation patterns after feeding. Specifically, victims of severe aggression affiliated with third parties after conflicts in the two‐piece condition, while aggressors affiliated with victims of mild aggression in the one‐piece condition. We thus provide the first evidence that a corvid species, crows, flexibly engage in both third‐party affiliation and reconciliation.     

Addressing high excitation conditions in time-resolved X-ray diffraction experiments and issues of biological relevance

One of the most important fundamental questions connecting chemistry to biology is how chemistry scales in complexity up to biological systems where there are innumerable possible pathways and competing processes. With the development of ultrabright electron and x-ray sources, it has been possible to literally light up atomic motions to directly observe the reduction in dimensionality in the barrier crossing region to a few key reaction modes. How do these chemical processes further couple to the surrounding protein or macromolecular assembly to drive biological functions? Optical methods to trigger photoactive biological processes are needed to probe this issue on the relevant timescales. However, the excitation conditions have been in the highly nonlinear regime, which questions the biological relevance of the observed structural dynamics.     

Differential modulation of murine host immune response by salivary gland extracts from the mosquitoes Aedes aegypti and Culex quinquefasciatus

Mosquitoes (Diptera: Culicidae) are major vectors of numerous infectious agents. Compounds in mosquito saliva not only facilitate blood-feeding, but may also have an impact upon the immune system of vertebrate hosts. Consequently, the exposure to mosquito saliva may influence pathogen transmission, establishment and disease development. Using two medically important vector mosquitoes, Aedes aegypti (L.) and Culex quinquefasciatus Say, we examined the effects of mosquito saliva on immune cells of host mice. After antigen-specific or non-specific stimulation, murine splenocyte proliferation and production of both Th1 and Th2 cytokines were significantly reduced in the presence of salivary gland extract (SGE) from Ae. aegypti, but not SGE from Cx. quinquefasciatus. T cell populations were highly susceptible to this suppression, showing increased mortality and reduced division rates - judged by flow cytometric analyses. Evidently these two culicine mosquitoes differ in their host immunomodulatory activities.     

Metabolic and functional diversity of saponins,biosynthetic intermediates and semi-synthetic derivatives

Abstract

Saponins are widely distributed plant natural products with vast structural and functional diversity. They are typically composed of a hydrophobic aglycone, which is extensively decorated with functional groups prior to the addition of hydrophilic sugar moieties, to result in surface-active amphipathic compounds. The saponins are broadly classified as triterpenoids, steroids or steroidal glycoalkaloids, based on the aglycone structure from which they are derived. The saponins and their biosynthetic intermediates display a variety of biological activities of interest to the pharmaceutical, cosmetic and food sectors. Although their relevance in industrial applications has long been recognized, their role in plants is underexplored. Recent research on modulating native pathway flux in saponin biosynthesis has demonstrated the roles of saponins and their biosynthetic intermediates in plant growth and development. Here, we review the literature on the effects of these molecules on plant physiology, which collectively implicate them in plant primary processes. The industrial uses and potential of saponins are discussed with respect to structure and activity, highlighting the undoubted value of these molecules as therapeutics.     

DNA sequence analyses of the ribosomal spacer regions in theTriticeae

Two regions of the ribosomal DNA (rDNA) were sequenced from a range of species from the tribeTriticeae. One region, the central spacer, was found to be more divergent in sequence than the other, the 18 S-spacer junction. Both regions contained sequences 20–30 bp long which were more highly conserved than the remainder of the region and their possible significance in rDNA expression is discussed. Phenetic relationships based on the sequence data were generally consistent with the relationships based on other criteria. Species possessing the S, E, J₁J₂, D, and B genomes clustered together, with the H genome species being the most distinct of those examined. The R, P, and V genome species occupy an intermediate position in the overall pattern of relationships. Some relationships differed in detail from those established by other parameters, for example the position of the N genome species, and explanations for discrepancies of this type are discussed.     

Molecular phylogenetics ofCochlearia (Brassicaceae) and allied genera based on nuclear ribosomal ITS DNA sequence analysis contradict traditional concepts of their evolutionary relationship

The systematics and phylogeny of the genusCochlearia and allied genera are unsettled. There are no clearly defined genera and subtribal structures to determine subtribeCochleariinae in respect to subtribeThlaspidinae. The use of morphological data, such as fruit form or embryo characters have resulted in contradictory taxonomic concepts in the past due to their homoplastic nature. We investigated all sections of genusCochlearia recognised in the most common concepts, as well as some genera such asIonopsidium, Bivonaea, Pastorea andThlaspi s. l. pro parte. Previous studies based on molecular data and morphological studies have shown close relationships between taxa from subtribeCochleariinae andThlaspidinae. The Internal Transcribed Spacer regions of the nuclear encoded ribosomal DNA operon and the plastidictrnL intron were sequenced from a number of genera. A molecular phylogeny was derived and compared to traditional classification systems. These data grouped sections ofCochlearia outside theCochlearial Ionopsidium core group and integrated them either closely to genusNoccaea in subtribeThlaspidinae (sect.Pseudosempervivum) or positioned them outside both theCochlearia core group and theThlaspi s. l. clade (sect.Hilliella). The molecular data indicate that subtribal arrangements in tribeLepidieae are artificial and do not reflect evolutionary history. The genusCochlearia is represented by sectionsCochlearia andGlaucocochlearia and the genusIonopsidium should be integrated intoCochlearia.     

Habitat relationships of forest birds on Tutuila Island, American Samoa

Aim Our knowledge of landbirds on tropical Pacific islands is often comprised of brief, one-time surveys. We know little of species’ habitat preferences, and this information is critical for understanding the resource requirements or population status of native species and the impacts of human activity on island birds. Location Tutuila Island, American Samoa. Methods The spatial patterns in forest birds were investigated. This island harbours large tracts of native forest, a variety of disturbed and non-native forests, and some relatively healthy bird populations. The distribution of birds was correlated with forest types using habitat data collected at fifty-seven sites and avian census data collected monthly for 1–4 years at these sites. Results Differences in location and in vegetation structure and composition between native and non-native habitats are important influences on the distribution of birds on Tutuila. Among native species, for example, the purple-capped fruit-dove (Ptilinopus porphyraceus Temminck) is dependent upon native habitat, the Samoan starling (Aplonis atrifusca Peale) occurs in all habitats, and the cardinal honeyeater (Myzomela cardinalis Gmelin) is more abundant in low elevation, non-native habitat. Conclusions This research reinforces the importance of quantitative assessment of habitat relationships in the study and conservation of Pacific birds.     

对应关系形成的一般分子机制

对应关系形成的分子机制的阐明对于在理论上深入了解对应关系本质和生命系统运行机制,在应用方面帮助人工利用、干预或构建对应关系具有重要意义．分子生物学的快速发展为对应关系的分子机制进行更深入和全面的认识提供了条件．本文在综合比较各种生物大分子基础上,提出系统性的多单体生物大分子模型理论,试图揭示对应关系形成的一般分子机制．该模型理论认为多单体生物大分子具有种类的高多样性,对应关系对多单体生物大分子高效完成各种生物学功能具有必要性,同时,多单体生物大分子的结构和性质也为对应关系的形成提供了可能性．对应关系的形成过程是一个相对独立的可分为3个阶段的复杂过程．在多单体生物大分子结构和性质基础上,从与配体间的识别机制、作用机制及亲和性三方面揭示了对应关系的形成机制．对多单体生物大分子产生对应关系的必然性、形成的分子机制的复杂性及在理论和应用方面的重要价值也进行了讨论．     

Taxonomic relationships in East AsianVicia species with unijugate leaves based on random amplified polymorphic DNA markers

Random amplified polymorphic DNA(RAPD) markers were investigated to clarify the taxonomic positions ofVicia linearifolia andV. bifolia, and to assess the genomic diversity among the 9 populations ofV. unijuga, each of which represents a geographical variation or infraspecific taxa in southern Korea. These species are characterized by unijugate leaves in East Asia and have been controversial as to infra-or interspecific classification. The polymorphic markers among the populations examined were observed for fifteen decamer primers. The degree of band sharing was used to calculate genetic similarity between populations, and a phenogram using UPGMA cluster analysis was generated based on the Dice similarity coefficient. The taxa studied were divided into two main groups and the populations ofV. unijuga were all grouped together in the phenogram. The genetic similarities ofV. unijuga were very high among the populations and did not show distinctions between the infraspecific taxa, although the populations of Mt. Odae and adjacent areas in eastern Korea were different from others of the species.V. linearifolia fell within the range of the genomic variation among the populations ofV. unijuga, whileV. bifolia was grouped withV. venosa var.cuspidata having multijugate leaves rather thanV. unijuga. The result from studying RAPD markers suggested thatV. linearifolia should be integrated intoV. unijuga and that species with unijugate leaves ofV. bifolia andV. unijuga are polyphyletic.