Liver microbiome of Peromyscus leucopus, a key reservoir host species for emerging infectious diseases in North America

Microbiome studies generally focus on the gut microbiome, which is composed of a large proportion of commensal bacteria. Here we propose a first analysis of the liver microbiome using next generation sequencing as a tool to detect potentially pathogenic strains. We used Peromyscus leucopus, the main reservoir host species of Lyme disease in eastern North America, as a model and sequenced V5-V6 regions of the 16S gene from 18 populations in southern Quebec (Canada). The Lactobacillus genus was found to dominate the liver microbiome. We also detected a large proportion of individuals infected by Bartonella vinsonii arupensis, a human pathogenic bacteria responsible for endocarditis, as well as Borrelia burgdorferi, the pathogen responsible for Lyme disease in North America. We then compared the microbiomes among two P. leucopus genetic clusters occurring on either side of the St. Lawrence River, and did not detect any effect of the host genotype on their liver microbiome assemblage. Finally, we report, for the first time, the presence of B. burgdorferi in a small mammal host from the northern side of the St. Lawrence River, in support of models that have predicted the northern spread of Lyme disease in Canada.

Discovery of CX-5461, the First Direct and Selective Inhibitor of RNA Polymerase I, for Cancer Therapeutics

Accelerated proliferation of solid tumor and hematologic cancer cells is linked to accelerated transcription of rDNA by the RNA polymerase I (Pol I) enzyme to produce elevated levels of rRNA (rRNA). Indeed, upregulation of Pol I, frequently caused by mutational alterations among tumor suppressors and oncogenes, is required for maintenance of the cancer phenotype and forms the basis for seeking selective inhibitors of Pol I as anticancer therapeutics. 2-(4-Methyl-[1,4]diazepan-1-yl)-5-oxo-5H-7-thia-1,11b-diaza-benzo[c]fluorene-6-carboxylic acid (5-methyl-pyrazin-2-ylmethyl)-amide (CX-5461, 7c) has been identified as the first potent, selective, and orally bioavailable inhibitor of RNA Pol I transcription with in vivo activity in tumor growth efficacy models. The preclinical data support the development of CX-5461 as an anticancer drug with potential for activity in several types of cancer.

Discovery of CX-6258. A Potent, Selective, and Orally Efficacious pan-Pim Kinases Inhibitor

Structure-activity relationship analysis in a series of 3-(5-((2-oxoindolin-3-ylidene)methyl)furan-2-yl)amides identified compound 13, a pan-Pim kinases inhibitor with excellent biochemical potency and kinase selectivity. Compound 13 exhibited in vitro synergy with chemotherapeutics and robust in vivo efficacy in two Pim kinases driven tumor models.

Discovery and SAR of 5-(3-chlorophenylamino)benzo[c][2,6]naphthyridine-8-carboxylic acid (CX-4945), the first clinical stage inhibitor of protein kinase CK2 for the treatment of cancer

Herein we chronicle the discovery of CX-4945 (25n), a first-in-class, orally bioavailable ATP-competitive inhibitor of protein kinase CK2 in clinical trials for cancer. CK2 has long been considered a prime cancer drug target because of the roles of deregulated and overexpressed CK2 in cancer-promoting prosurvival and antiapoptotic pathways. These biological properties as well as the suitability of CK2's small ATP binding site for the design of selective inhibitors, led us to fashion novel therapeutic agents for cancer. The optimization leading to 25n (K(i) = 0.38 nM) was guided by molecular modeling, suggesting a strong binding of 25n resulting from a combination of hydrophobic interactions, an ionic bridge with Lys68, and hydrogen bonding with the hinge region. 25n was found to be highly selective, orally bioavailable across species (20-51%) and efficacious in xenograft models. The discovery of 25n will allow the therapeutic targeting of CK2 in humans for the first time.

Global population structure of the stable fly (Stomoxys calcitrans) inferred by mitochondrial and nuclear sequence data

Stomoxys calcitrans (Diptera: Muscidae: Stomoxyini), a synanthropic fly with a worldwide distribution, is recognized to have an important medical and veterinary impact. We conducted a phylogeographic analysis based on several populations from five major zoogeographic regions of the world in order to analyse population genetic structure of S. calcitrans and to trace its global dispersion. Results from mitochondrial (COI, Cyt-b and ND1-16S) and nuclear (ITS2) DNA show a substantial differentiation of Oriental populations (first lineage) from the Afrotropical, Palearctic, Nearctic, Neotropical and Oceanian populations (second lineage). The divergence time analyses suggest the separation between the two lineages approximately in mid-Pleistocene. Oriental populations are isolated and would not have participated in the colonization of other regions, unlike the Afrotropical one which seems to be the source of S. calcitrans dispersion towards other regions. Demographic analyses indicate that Oriental, Afrotropical and Palearctic regions have undergone a population expansion during late Pleistocene-early Holocene. The expansion time of this cosmopolitan species could have been influenced by continental human expansions and by animal domestication.

Abstract A246: Discovery of selective small molecule Pan-Pim kinase inhibitors with potent oral efficacy in murine xenograft models

The PIM family of serine/threonine kinases are pro-proliferative kinases activated by multiple cytokines and growth factor signaling. The Pim kinases are unusual in that they are regulated primarily by transcription and not by membrane recruitment or phosphorylation like other serine/threonine kinases. Activated cytokine receptors recruit JAKs to induce STAT-dependent transcription of the Pim genes. They are proto-oncogenes and have been implicated in the process of lymphomagenesis and malignant transformation. Pim overexpression has been reported in diffuse B cell lymphoma, chronic lymphocytic leukemia, FLT3-mediated acute myelogenous leukemia and prostate cancer. Pim-2 is over expressed in leukemias and lymphomas, whereas Pim-3 overexpression has been observed in melanoma, pancreatic and gastric tumors. The recent reports of elevated levels of Pim-1 expression in human prostate tumor biopsies implicate the Pim family of protein kinases in the progression of human prostate tumors. Further, in transgenic animal models, Pim-1 expression has been shown to be elevated in prostate tumors that are caused by overexpression of the c-myc oncogene. Recent evidence reveals the overlapping and compensatory nature of Pim-1 and Pim-2 phosphorylation and highlights the importance of inhibiting all isoforms. The emerging role of the PIM kinase family in hematological malignancies and solid tumors and the druggable nature of their ATP binding pocket make them attractive targets for anticancer drug development.

Utilizing a highly distinct molecular scaffold, CX-6258 was developed as a selective and potent small molecule pan-PIM kinase inhibitor. CX-6258 inhibits Pims 1, 2 and 3 with IC50 values in the low nanomolar range and high selectivity as evidenced in a screening panel of over 100 kinases. CX-6258 demonstrates potent in vitro antiproliferative activity, particularly in leukemia derived cell lines expressing the FLT3-ITD. Moreover, CX-6258 inhibits the phosphorylation of BAD and 4EBP1, known substrates for PIMs 1, 2 and 3. When delivered orally, this pan-Pim inhibitor is well tolerated and demonstrates potent antitumor activity in murine xenograft models of PIM driven cancer. Using CX-6258 as our “path finder” molecule, we have created four additional unique chemical scaffolds as pan-Pim inhibitors, and certain molecules from these scaffolds can inhibit Pims 1, 2 and 3 in the picomolar range while exhibiting no inhibitory activity of the Flt3 protein kinase. The in vivo and in vitro profiles of these chemically diverse series are indicative of an effective and potent anti-cancer mechanism mediated through the selective inhibition of PIM kinase activity. Together, these findings exemplify that we have created multiple proprietary chemical series of pan-Pim inhibitors exhibiting picomolar potency and discerning selectivity.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A246.

Contribution of collagen stable isotope biogeochemistry to the paleobiology of extinct endemic vertebrates from Tenerife (Canary Islands, Spain)

The paleodiet and paleoenvironmental context of two extinct species from Tenerife island, one giant rat Canariomys bravoi and one giant lizard Gallotia goliath, have been investigated using carbon and nitrogen isotopic compositions of fossil bone collagen. Preliminary to this study, a calibration of the isotopic variations of bone collagen from modern Rat Rattus rattus, Rabbit Oryctolagus cuniculus and Lizard Gallotia galotti relative to environmental conditions on Tenerife Islands has been attempted. No clear relationship could be found between collagen delta13C and delta15N values and aridity; the only relevant factors seem to be seashore proximity for rat, and the relative amount of C3 and CAM plants. It seems that anthropic activities have interfered with the expected relationships between collagen isotopic compositions and environmental conditions. Most fossil specimens yielded well preserved collagen. The isotopic composition of giant rat and giant lizard collagen suggest a purely C3 environment, possibly more humid than today on Tenerife. Large ranges of nitrogen isotopic compositions, especially within giant rats, may be due to local environmental conditions. Further work is needed in order to provide more valuable paleobiological information in order to better understand the role of environmental factors in the evolution and extinction of insular endemic species on Tenerife.

Evolutionary history of the most speciose mammals: molecular phylogeny of muroid rodents

Phylogenetic relationships between 32 species of rodents representing 14 subfamilies of Muridae and four subfamilies of Dipodidae were studied using sequences of the nuclear protein-coding genes Lecithin Cholesterol Acyl Transferase (LCAT) and von Willebrand Factor (vWF). An examination of some evolutionary properties of each data matrix indicates that the two genes are rather complementary, with lower rates of nonsynonymous substitutions for LCAT. Both markers exhibit a wide range of GC3 percentages (55%-89%), with several taxa above 70% GC3 for vWF, which indicates that those exonic regions might belong to the richest class of isochores. The primary sequence data apparently harbor few saturations, except for transitions on third codon positions for vWF, as indicated by comparisons of observed and expected pairwise values of substitutions. Phylogenetic trees based on 1,962 nucleotidic sites from the two genes indicate that the 14 Muridae subfamilies are organized into five major lineages. An early isolation leads to the clade uniting the fossorial Spalacinae and semifossorial Rhizomyinae with a strong robustness. The second lineage includes a series of African taxa representing nesomyines, dendromurines, cricetomyines, and the sole living member of mystromyines. The third one comprises only the mouselike hamster CALOMYSCUS: The fourth clade represents the cricetines, myospalacines, sigmodontines, and arvicolines, whereas the fifth one comprises four "traditional" subfamilies (Gerbillinae, Murinae, Otomyinae, and Acomyinae). Within these groups, we confirm the monophyly of almost all studied subfamilies, namely, Spalacinae, Rhizomyinae, Nesomyinae, Cricetomyinae, Arvicolinae, Sigmodontinae, Cricetinae, Gerbillinae, Acomyinae, and Murinae. Finally, we present evidence that the sister group of Acomyinae is Gerbillinae, and we confirm a nested position of Myospalacinae within Cricetinae and Otomyinae within Murinae. From a biogeographical point of view, the five main lineages spread and radiated from Asia with different degrees of success: the first three groups are now represented by a limited number of species and genera localized in some regions, whereas the last two groups radiated in a large variety of species and genera dispersed all over the world.

The bushlike radiation of muroid rodents is exemplified by the molecular phylogeny of the LCAT nuclear gene

Phylogenetic relationships among 40 extant species of rodents, with an emphasis on the taxonomic sampling of Muridae and Dipodidae, were studied using sequences of the nuclear protein-coding gene LCAT (lecithin cholesterol acyl transferase). Analysis of 804 bp from the exonic regions of LCAT confirmed many traditional groupings in and around Muridae. A strong support was found for the families Muridae (represented by 29 species) and Dipodidae (5 species). Compared with Sciuridae, Gliridae, and Caviomorpha, the Dipodidae family appeared the closest relative of Muridae, confirming the suprafamilial Myodonta concept. Within the speciose family Muridae, the first branching leads to the fossorial Spalacinae and semifossorial Rhyzomyinae. The remaining components of Muridae appear as a polytomy from which are issued Sigmodontinae, Calomyscinae, Arvicolinae, Cricetinae, Mystromyinae, Nesomyinae, and some Dendromurinae (Steatomys and Dendromus). This phylogeny is interpreted as the result of a bushlike radiation at the end of the early Miocene, leading to emergence of most living subfamilies. The separation between three additional taxa, Murinae, Gerbillinae, and "Acomyinae" (which comprises the genera Acomys, Deomys, Uranomys, and Lophuromys), has occurred more recently from a common ancestor issued from the main basal radiation. As previously shown by other molecular studies, the vlei rats, Otomyinae, are nested within Old World Murinae. In the same way, the zokors, Myospalacinae, appear strongly nested within the hamsters, Cricetinae. Finally, we propose a sister group relationship between Malagasy Nesomyinae and south African Mystromyinae.

Novel mutant green fluorescent protein protease substrates reveal the activation of specific caspases during apoptosis

BACKGROUND

The caspase-mediated proteolysis of many cellular proteins is a critical event during programmed cell death or apoptosis. It is important to determine which caspases are activated in mammalian cells, and where and when activation occurs, upon receipt of specific death stimuli. Such information would be useful in the design of strategies to regulate the activation of caspases during apoptosis.

RESULTS

We developed two novel fluorescent substrates that were specifically cleaved by caspase-1 or caspase-3. For in vitro studies, four-amino-acid recognition sequences, YVAD for caspase-1 and DEVD for caspase-3, were introduced between blue fluorescent protein (BFP) and green fluorescent protein (GFP), expressed in bacteria and purified. For in vivo studies, YVAD and DEVD were introduced between cyan fluorescent protein and yellow fluorescent protein, and expression was monitored in live mammalian cells. The proximity between fluorophores was determined using fluorescence resonance energy transfer. Purified substrates were cleaved following exposure to purified caspase-1 and caspase-3. In Cos-7 cells, caspase-1 and caspase-3 substrates were cleaved upon induction of apoptosis with staurosporine, a protein-kinase inhibitor, whereas caspase-3 but not caspase-1 substrate was cleaved upon treatment of cells with the DNA-damaging agent mitomycin c.

CONCLUSIONS

These substrates allow the spatial activation of specific members of the caspase family to be deciphered during the initiation and execution phase of programmed cell death, and allow activation of specific caspases to be monitored both in vivo and in vitro. This technology is also likely to be useful for high-throughput screening of reagents that modulate caspase activity.

[Recent history of the brown bear in the Maghreb]

Bones of the brown bear (Ursus arctos, mammalia, Carnivora) found in a cave of the Akouker massif (Djurdjura, Algeria) have been dated according to the 14C method as belonging to the historical times (420-600 A.D.). The bone and teeth measurements correspond to a small-sized animal, the smallest ever found in the Maghreb. A review of fossil bears in the Quaternary faunas of North Africa clearly shows that the area of distribution, which was initially wide, shrank at the end of the Upper Pleistocene. The bears had temporarily taken to mountainous areas difficult to access. The bone remains discovered up to now prove that the brown bear was represented by individuals or populations showing a large diversity of size.

Molecular evidence that the spiny mouse (Acomys) is more closely related to gerbils (Gerbillinae) than to true mice (Murinae)

Spiny mice of the genus Acomys traditionally have been classified as members of the Murinae, a subfamily of rodents that also includes rats and mice with which spiny mice share a complex set of morphological characters, including a unique molar pattern. The origin and evolution of this molar pattern, documented by many fossils from Southern Asia, support the hypothesis of the monophyly of Acomys and all other Murinae. This view has been challenged by immunological studies that have suggested that Acomys is as distantly related to mice (Mus) as are other subfamilies (e.g., hamsters: Cricetinae) of the muroid rodents. We present molecular evidence derived from DNA.DNA hybridization data that indicate that the spiny mouse Acomys and two African genera of Murinae, Uranomys and Lophuromys, constitute a monophyletic clade, a view that was recently suggested on the basis of dental characters. However, our DNA.DNA hybridization data also indicate that the spiny mice (Acomys) are more closely related to gerbils (Gerbillinae) than to the true mice and rats (Murinae) with which they have been classified. Because Acomys and the brush-furred mice Uranomys and Lophuromys share no derived morphological characters with the Gerbillinae, their murine morphology must have evolved by convergence, including the molar pattern previously considered to support the monophyly of the Murinae.

[Bridge grafting between the ascending and lower thoracic aorta using the right side approach (author's transl)]

We describe a method aimed at reconstituting the thoracic aorta by means of a graft located on the right side of the heart. The method is original in that the graft is entirely intra-thoracic and not thoraco-abdominal, as in previously reported similar operations, its advantages are demonstrated by reference to one case where it was used for the treatment of a relapsed congenital atresia of the aortic arch.