DNA hybridization evidence for the principal lineages of hummingbirds (Aves:Trochilidae)

The spectacular evolutionary radiation of hummingbirds (Trochilidae) has served as a model system for many biological studies. To begin to provide a historical context for these investigations, we generated a complete matrix of DNA hybridization distances among 26 hummingbirds and an outgroup swift (Chaetura pelagica) to determine the principal hummingbird lineages. FITCH topologies estimated from symmetrized delta TmH-C values and subjected to various validation methods (bootstrapping, weighted jackknifing, branch length significance) indicated a fundamental split between hermit (Eutoxeres aquila, Threnetes ruckeri; Phaethornithinae) and nonhermit (Trochilinae) hummingbirds, and provided strong support for six principal nonhermit clades with the following branching order: (1) a predominantly lowland group comprising caribs (Eulampis holosericeus) and relatives (Androdon aequatorialis and Heliothryx barroti) with violet-ears (Colibri coruscans) and relatives (Doryfera ludovicae); (2) an Andean-associated clade of highly polytypic taxa (Eriocnemis, Heliodoxa, and Coeligena); (3) a second endemic Andean clade (Oreotrochilus chimborazo, Aglaiocercus coelestis, and Lesbia victoriae) paired with thorntails (Popelairia conversii); (4) emeralds and relatives (Chlorostilbon mellisugus, Amazilia tzacatl, Thalurania colombica, Orthorhyncus cristatus and Campylopterus villaviscensio); (5) mountain-gems (Lampornis clemenciae and Eugenes fulgens); and (6) tiny bee-like forms (Archilochus colubris, Myrtis fanny, Acestrura mulsant, and Philodice mitchellii). Corresponding analyses on a matrix of unsymmetrized delta values gave similar support for these relationships except that the branching order of the two Andean clades (2, 3 above) was unresolved. In general, subsidiary relationships were consistent and well supported by both matrices, sometimes revealing surprising associations between forms that differ dramatically in plumage and bill morphology. Our results also reveal some basic aspects of hummingbird ecologic and morphologic evolution. For example, most of the diverse endemic Andean assemblage apparently comprises two genetically divergent clades, whereas the majority of North American hummingbirds belong a single third clade. Genetic distances separating some morphologically distinct genera (Oreotrochilus, Aglaiocercus, Lesbia; Myrtis, Acestrura, Philodice) were no greater than among congeneric (Coeligena) species, indicating that, in hummingbirds, morphological divergence does not necessarily reflect level of genetic divergence.      

Isolation and characterization of lectins specific for mannose/fucose/N-acetylglucosamine from rat peritoneal macrophages

Rat peritoneal macrophages were shown to have two distinct mannose/fucose/N-acetylglucosamine-specific lectins. The major lectin of 180 kDa, which is similar in size to the mannose receptor first isolated from alveolar macrophages (Wileman, T.E., Lennartz, M.R., & Stahl, P.D. (1986) Proc. Natl. Acad. Sci. U.S. 83, 2501-2505), was shown to occur as a dimer under nondenaturing conditions. The 29 and 32 kDa lectins were identified as members of the liver mannan-binding protein family on the basis of their immunochemical crossreactivity, collagenase sensitivity, and molecular sizes (Oka, S., Ikeda, K., Kawasaki, T., & Yamashina, I. (1988) Arch. Biochem. Biophys. 260, 257-266). Despite the similarity in the sugar binding specificity, these two types of lectin were clearly differentiated with regard to the binding to IgM molecules. The 29 and 32 kDa lectins bound to IgM most likely through high-mannose type oligosaccharides on IgM, whereas the 180 kDa lectin did not.     

The sensitivity of Afromontane tarns in the Maloti-Drakensberg region of South Africa and Lesotho to acidic deposition

Despite their remoteness from sources of atmospheric pollutant emissions, the Afromontane tarns in the Maloti-Drakensberg region are perfect candidates to study the negative effects of acidifying atmospheric pollution, because mountain lakes are widely recognised as sentinel ecosystems, unimpacted by direct human disturbance within their catchments. Thirty-four tarns were sampled in the Maloti-Drakensberg region and most were found to be extremely sensitive to acidic deposition, as indicated by their low acid neutralising capacity. There are very few studies of freshwater critical loads for any region within South Africa. The steady-state water chemistry model (SSWC) was adapted and used to determine critical loads, whereas exceedance was estimated relative to modelled regional deposition data, in order to understand the risk of harmful effects to aquatic ecosystems. Seventy-six percent of sampled sites across the Maloti-Drakensberg would exceed critical loads even at the lowest modelled deposition levels, but there are no current measured deposition data for the region. The sensitivity of the Maloti-Drakensberg tarns needs to be considered in future policy formulation regarding acceptable levels of acidifying atmospheric pollution from South Africa’s energy sector and indicates the need for assessing aquatic ecosystem impacts in other regions of South Africa.     

A myotrophic protein from chick embryo extract: Its purification,identity to transferrin,and indispensability for avian myogenesis

Chick embyro extract (EE) has been widely employed as a growth-promoting supplement in avian myogenic cell cultures. We have purified a myotrophic substance from EE with ammonium sulfate precipitation, CM-Sephadex and DEAE-cellulose chromatography. Salt gradient elution from DEAE-cellulose columns yielded three active peaks with a protein of 80K daltons. The proteins have different isoelectric points of 6.1, 5.9, and 5.7, respectively. They promoted chick myoblasts to proliferate and myotubes to grow when added in the place of EE to a basal culture medium (BCM) composed of Eagle's minimal essential medium and horse serum. Their myotrophic activities were the same and reversibly lost by removal of protein-bound Fe. They were identified as transferrin (Tf) species of differing numbers of sialic acid residues, on the basis of physicochemical and immunological analyses. Tf in EE consisted of species of fewer sialic acid residues than adult serum Tf. Indispensability of Fe-bound Tf for EE to exert myotrophic activity was demonstrated by experiments to remove Tf by immunoprecipitation and to remove Fe from Tf in EE. Either treatment led to a complete loss of the myotrophic activity, which was restored by supplementation of Fe-bound Tf or Fe³⁺. Comparison of myotrophic activity of EE with that of Tf indicated the presence of other factors in EE which promote myogenic cell growth synergistically with Tf. From the results and on the basis of the class-specific function of Tf on the cells, we discuss the relation of Tf to nerve-derived myotrophic proteins and other factors in EE.     

Identification of the collagen-binding domain of vitronectin using monoclonal antibodies

Vitronectin is a 75 kilodalton (kDa) cell-adhesive glycoprotein found in animal blood and connective tissue, also termed serum spreading factor, S-protein, and epibolin. It promotes attachment and spreading of animal cells on tissue culture dishes, and it also binds to collagen. We established four mouse hybridoma lines producing monoclonal antibodies (M1, M2, M4 and M5) to human vitronectin. By immunoblotting, both epitopes recognized by M4 and M5 were suggested to exist in the amino terminal 5 kDa portion of vitronectin, and both M1 and M2 bound to the adjacent 35 kDa portion. Cell spreading on vitronectin-coated dishes was inhibited by M4 = M5 greater than M1, but not by M2. Collagen binding to vitronectin was inhibited by M2 greater than M4 = M5, but not by M1. These results indicate that the collagen-binding site is located near the cell-binding site in the amino terminal half of vitronectin. Independent inhibition of vitronectin binding to the cell and to collagen by these monoclonal antibodies will provide a potential tool to dissect the structure and function of vitronectin.     

Differences in the carbon tetrachloride-induced damage to components of the smooth and rough endoplasmic reticulum from rat liver

There is a higher activity of ethyl morphine N-demethylase (EM-ase) and cytochrome P-450 (P-450) reductase as well as higher P-450 content in the smooth endoplasmic reticulum (SER) than in the rough endoplasmic reticulum (RER). The extent of the irreversible binding of the¹⁴C from¹⁴CCl₄ to lipids and proteins, as well as the CCl₄-induced destruction of P-450 is more intense in SER than in RER while the opposite was found for glucose 6-phosphatase (G6P-ase) destruction. CCl₄-induced lipid peroxidation is as intense in SER as is in RER.¹⁴C from¹⁴CCl₄ gets irreversibly bound to ribosomal proteins.     

Adipose-derived stromal cells inhibit prostate cancer cell proliferation inducing apoptosis

Mesenchymal stem cells (MSCs) have generated a great deal of interest in the field of regenerative medicine. Adipose-derived stromal cells (AdSCs) are known to exhibit extensive proliferation potential and can undergo multilineage differentiation, sharing similar characteristics to bone marrow-derived MSCs. However, as the effect of AdSCs on tumor growth has not been studied sufficiently, we assessed the degree to which AdSCs affect the proliferation of prostate cancer (PCa) cell. Human AdSCs exerted an inhibitory effect on the proliferation of androgen-responsive (LNCaP) and androgen-nonresponsive (PC3) human PCa cells, while normal human dermal fibroblasts (NHDFs) did not, and in fact promoted PCa cell proliferation to a degree. Moreover, AdSCs induced apoptosis of LNCaP cells and PC3 cells, activating the caspase3/7 signaling pathway. cDNA microarray analysis suggested that AdSC-induced apoptosis in both LNCaP and PC3 cells was related to the TGF-β signaling pathway. Consistent with our in vitro observations, local transplantation of AdSCs delayed the growth of tumors derived from both LNCaP- and PC3-xenografts in immunodeficient mice. This is the first preclinical study to have directly demonstrated that AdSC-induced PCa cell apoptosis may occur via the TGF-β signaling pathway, irrespective of androgen-responsiveness. Since autologous AdSCs can be easily isolated from adipose tissue without any ethical concerns, we suggest that therapy with these cells could be a novel approach for patients with PCa.     

Genomic characterisation of the effector complement of the potato cyst nematode Globodera pallida

Background

The potato cyst nematode Globodera pallida has biotrophic interactions with its host. The nematode induces a feeding structure – the syncytium – which it keeps alive for the duration of the life cycle and on which it depends for all nutrients required to develop to the adult stage. Interactions of G. pallida with the host are mediated by effectors, which are produced in two sets of gland cells. These effectors suppress host defences, facilitate migration and induce the formation of the syncytium.

Results

The recent completion of the G. pallida genome sequence has allowed us to identify the effector complement from this species. We identify 128 orthologues of effectors from other nematodes as well as 117 novel effector candidates. We have used in situ hybridisation to confirm gland cell expression of a subset of these effectors, demonstrating the validity of our effector identification approach. We have examined the expression profiles of all effector candidates using RNAseq; this analysis shows that the majority of effectors fall into one of three clusters of sequences showing conserved expression characteristics (invasive stage nematode only, parasitic stage only or invasive stage and adult male only). We demonstrate that further diversity in the effector pool is generated by alternative splicing. In addition, we show that effectors target a diverse range of structures in plant cells, including the peroxisome. This is the first identification of effectors from any plant pathogen that target this structure.

Conclusion

This is the first genome scale search for effectors, combined to a life-cycle expression analysis, for any plant-parasitic nematode. We show that, like other phylogenetically unrelated plant pathogens, plant parasitic nematodes deploy hundreds of effectors in order to parasitise plants, with different effectors required for different phases of the infection process.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-923) contains supplementary material, which is available to authorized users.