Mating trials validate the use of DNA barcoding to reveal cryptic speciation of a marine bryozoan taxon

Despite increasing threats to the marine environment, only a fraction of the biodiversity of the oceans has been described, owing in part to the widespread occurrence of cryptic species. DNA-based barcoding through screening of an orthologous reference gene has been proposed as a powerful tool to uncover biological diversity in the face of dwindling taxonomic expertise and the limitations of traditional species identification. Although DNA barcoding should be particularly useful in the sea, given the prevalence of marine cryptic species, the link between taxa identified through DNA barcodes and reproductively isolated taxa (biological species) has rarely been explicitly tested. Here, we use an integrated framework comparing breeding compatibility, morphology and mitochondrial (cytochrome c oxidase 1) and nuclear (elongation factor-1-alpha) DNA sequence variation among globally distributed samples of the cosmopolitan marine bryozoan Celleporella hyalina (L.). Our results reveal that C. hyalina comprises numerous deep, mostly allopatric, genetic lineages that are reproductively isolated, yet share very similar morphology, indicating rampant cryptic speciation. The close correspondence between genetic lineages and reproductively isolated taxa in the context of minimal morphological change suggests that DNA barcoding will play a leading role in uncovering the hidden biodiversity of the oceans and that the sole use of morphologically based taxonomy would grossly underestimate the number of marine species.     

A primitive ornithischian dinosaur from the Late Triassic of South Africa, and the early evolution and diversification of Ornithischia

Although the group played an important role in the evolution of Late Mesozoic terrestrial ecosystems, the early evolutionary history of the ornithischian dinosaurs remains poorly understood. Here, we report on a new primitive ornithischian, Eocursor parvus gen. et sp. nov., from the Late Triassic (?Norian) Lower Elliot Formation of South Africa. Eocursor is known from a single specimen comprising substantial cranial and postcranial material and represents the most complete Triassic member of Ornithischia, providing the earliest evidence for the acquisition of many key ornithischian postcranial characters, including an opisthopubic pelvis. A new phylogenetic analysis positions this taxon near the base of Ornithischia, as the sister taxon to the important and diverse clade Genasauria. The problematic clade Heterodontosauridae is also positioned basal to Genasauria, suggesting that an enlarged grasping manus may represent a plesiomorphic ornithischian condition. This analysis provides additional phylogenetic support for limited ornithischian diversity during the Late Triassic, and suggests that several major ornithischian clades may have originated later than generally believed. There are few morphological differences between Late Triassic and Early Jurassic ornithischians, supporting previous suggestions that the Early Jurassic ornithischian radiation may simply represent the filling of vacant ecological space following Late Triassic terrestrial extinctions.     

Valvulogenesis: the moving target

Valvulogenesis is an extremely complex process by which a fragile gelatinous matrix is populated and remodelled during embryonic development into thin fibrous leaflets capable of maintaining unidirectional flow over a lifetime. This process occurs during exposure to constantly changing haemodynamic forces, with a success rate of approximately 99%. Defective valvulogenesis results in impaired cardiac function and lifelong complications. This review integrates what is known about the roles of genetics and mechanics in the development of valves and how changes in either result in impaired morphogenesis. It is hoped that appropriate developmental cues and phenotypic endpoints could help engineers and clinicians in their efforts to regenerate living valve alternatives.     

Stable expression of human growth hormone over 50 generations in transgenic insect larvae

Developments in insect transgenesis using transposons combined with available mass rearing technology for insects such as the Medfly, Ceratitis capitata, provide opportunity for the production of protein for industrial, agricultural and healthcare purposes on a very large scale. In this study, we report the germ-line transformation and expression of a cDNA encoding human growth hormone (hGH) in transgenic Drosophila using the Minos transposon. Production and secretion of a bioactive hGH into the haemolymph of transgenic larvae was demonstrated by immunoblot analysis, ELISA and a proliferation bioassay. Stable expression of hGH was observed over 50 generations. The results indicate that mass reared transgenic diptera with a rapid period of larval growth could provide cost effective production systems for the manufacture of therapeutic and other high value proteins.     

The JNK signal transduction pathway

The c-Jun NH(2)-terminal kinases (JNKs) are an evolutionarily conserved sub-group of mitogen-activated protein (MAP) kinases. Recent studies have improved our understanding of the physiological function of the JNK pathway. Roles of novel molecules that participate in the JNK pathway have been defined and new insight into the role of JNK in survival signaling, cell death, cancer and diabetes has been achieved.     

Linking bioprospecting with sustainable development and conservation: the Panama case

The limited international resources for economic aid and conservation can only mitigate poverty and losses of biodiversity. Hence, developing nations must establish the capacity to resolve their problems. Additionally, policy-makers and donors need to obtain scientific input on issues such as global change and ecosystem services. We propose that for nations rich in biodiversity, ecosystem services derived from bioprospecting, or drug discovery, could contribute to economic development. In the case where unstudied samples are shipped abroad for research, the chances of obtaining royalties are infinitesimally small. Therefore developing nations will only realize benefits from bioprospecting through in-country research on their own biodiversity. Policy-makers and donors have failed to appreciate the value of this approach. In order to provide an example of the inherent links between conservation and sustainable economic development, we initiated a drug discovery effort in Panama that emphasizes local benefit. As much of the drug discovery process as possible is conducted in Panamanian laboratories, providing jobs dependent on intact biodiversity and enhancing local research and training. In short, research, plus the spin-offs from research, provide immediate and long-lasting benefits to Panama. The connection between conservation and development has been highlighted in publicity about the project in Panama’s urban media. This provides a constructive alternative to the perception the among the urban populace that economic development inevitably competes with conservation. In summary, our program uses biodiversity to promote human health as well as to support research capacity, economic development and conservation within Panama. The program provides an example of the widely recognized but little developed concept of bioprospecting research as an ecosystem service.     

1alpha,25-Dihydroxyvitamin D3-induced down-regulation of the checkpoint proteins, Chk1 and Claspin, is mediated by the pocket proteins p107 and p130

A previous cDNA microarray analysis in murine MC3T3-E1 osteoblasts revealed a cluster of genes involved in cell cycle progression that was significantly down-regulated after a single treatment with 1alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] [L. Verlinden, G. Eelen, I. Beullens, M. Van Camp, P. Van Hummelen, K. Engelen, R. Van Hellemont, K. Marchal, B. De Moor, F. Foijer, H. Te Riele, M. Beullens, M. Bollen, C. Mathieu, R. Bouillon, A. Verstuyf, Characterization of the condensin component Cnap1 and protein kinase Melk as novel E2F target genes down-regulated by 1,25-dihydroxyvitamin D3, J. Biol. Chem. 280 (45) (2005) 37319-37330]. Among those genes were the DNA replication and DNA damage checkpoint proteins, Chk1 and Claspin, of which the human homologues were recently shown to be E2F-responsive. Quantitative real-time PCR experiments in 1,25(OH)(2)D(3)-treated MC3T3-E1 cells confirmed the down-regulation observed in the microarray experiment. Moreover, Chk1 and Claspin promoter activities were also reduced after incubation with 1,25(OH)(2)D(3), and this reduction was mediated through the E2F recognition motifs within their promoters because mutation of these motifs almost completely abolished the repressive effect of 1,25(OH)(2)D(3). The antiproliferative effect of 1,25(OH)(2)D(3) as well as its potential to down-regulate the expression of Chk1 and Claspin depended on the pocket proteins p107 and p130 because 1,25(OH)(2)D(3) lost its antiproliferative action and failed to repress these E2F-target genes in p107(-/-);p130(-/-)-cells, but not in pRb(-/-)-cells.     

Abiotic influences on embryo growth: statoliths as experimental tools in the squid early life history

Statolith size and growth was used to determine the influence of abiotic factors on the growth of Loligo vulgaris and Sepioteuthis australis embryos. Recently spawned egg masses collected from the field were incubated in the laboratory under different levels of light intensity, photoperiod, or short periods of low salinity (30‰). Double tetracycline staining was used to follow statolith growth. In L. vulgaris constant light conditions produced significantly slower growth in the embryonic statoliths and embryos held at summer photoperiod had slower statolith growth than those held at winter photoperiods. However once they hatched out there was no evidence that photoperiod affected statolith growth. After hatching, in all photoperiods statolith growth rates decreased in comparison with late embryonic rates. In S. australis embryos, differences between the high and medium light intensities for summer and intermediate photoperiods were found, suggesting that under summer incubation temperature, longer daylengths at medium light intensity favoured higher statolith growth for this species. In comparison to controls, slower statolith growth in S. australis embryos due to low salinity only occurred when exposed for 72 h. Comparison with previous studies indicates that temperature seems to be the main abiotic factor influencing statolith growth during early stages, however, interactions among all abiotic factors needs to be determined as well as the unknown influence of other isolated factors, e.g., oxygen concentration within the egg mass.     

Synthesis of cryptolepine analogues as potential bioreducible anticancer agents

A series of 10 novel nitro-analogues of cryptolepine (1) has been synthesised and these compounds were evaluated for their in-vitro cytotoxic properties as well as their potential for reductive activation by the cytosolic reductase enzymes NQO1 and NQO2. Molecular modelling studies suggest that cryptolepine is able to fit into the active site of NQO2 and thus raising the possibility that nitro-analogues of 1 could act as bioreductive prodrugs and be selectively reduced by NQO1 and NQO2 to more toxic species in cancer cells in which these enzymes are over-expressed. Analogues were screened against the RT112 cell line (high in NQO2), in the presence and absence of the essential cofactor dihydronicotinamide riboside (NRH), whereby all analogues were shown to be cytotoxic (IC50<2microM) in the absence of NRH. With the addition of NRH, one analogue, 2-fluoro-7,9-dinitrocryptolepine (7), exhibited a 2.4-fold increase in cytotoxic activity. Several nitro-derivatives were also evaluated as substrates for purified human NQO1 and analogues that were found to be substrates were subsequently tested against the H460 (high NQO1) and BE (low NQO1) cell lines to detect in-vitro activation by NQO1. The analogue 8-chloro-9-nitrocryptolepine (9) was found to be the best substrate for NQO1 but it was not more toxic to H460 than to BE cells. Fluorescence laser confocal microscopy of 1 and several analogues showed that in contrast to 1 the analogues were not localised into the nucleus suggesting that their cytotoxic mode(s) of action are different. This study has identified novel substrates for both NQO1 and NQO2 and further work on nitrocryptolepine derivatives as a lead towards novel anticancer agents would be worthwhile.     

Metabolic stress signaling mediated by mixed-lineage kinases

Saturated free fatty acid (FFA) is a major source of metabolic stress that activates the c-Jun NH(2)-terminal kinase (JNK). This FFA-stimulated JNK pathway is relevant to hallmarks of metabolic syndrome, including insulin resistance. Here we used gene ablation studies in mice to demonstrate a central role for mixed-lineage protein kinases (MLK) in this signaling pathway. Saturated FFA causes protein kinase C (PKC)-dependent activation of MLK3 that subsequently causes increased JNK activity by a mechanism that requires the MAP kinase kinases MKK4 and MKK7. Loss of PKC, MLK3, MKK4, or MKK7 expression prevents FFA-stimulated JNK activation. Together, these data establish a signaling pathway that mediates effects of metabolic stress on insulin resistance.