Evolution and taxonomy of the wild species of the genus Ovis (Mammalia,Artiodactyla, Bovidae)

New insights for the systematic and evolution of the wild sheep are provided by molecular phylogenies inferred from Maximum parsimony, Bayesian, Maximum likelihood, and Neighbor-Joining methods. The phylogeny of the wild sheep was based on cytochrome b sequences of 290 samples representative of most of the sub-species described in the genus Ovis. The result was confirmed by a combined tree based on cytochrome b and nuclear sequences for 79 Ovis samples representative of the robust clades established with mitochondrial data. Urial and mouflon, which are either considered as a single or two separate species, form two monophyletic groups (O. orientalis and O. vignei). Their hybrids appear in one or the other group, independently from their geographic origin. The European mouflon O. musimon is clearly in the O. orientalis clade. The others species, O. dalli, O. canadensis, O. nivicola, and O. ammon are monophyletic. The results support an Asiatic origin of the genus Ovis, followed by a migration to North America through North-Eastern Asia and the Bering Strait and a diversification of the genus in Eurasia less than 3 million years ago. Our results show that the evolution of the genus Ovis is a striking example of successive speciation events occurring along the migration routes propagating from the ancestral area.     

Expression, purification, and characterization of cysteine-free mouse P-glycoprotein

Cysteine-free mouse MDR3 P-glycoprotein (Pgp) was constructed by mutagenesis of the nine natural Cys to Ala. The Cys-free protein was expressed in Pichia pastoris and purified. Yield, purity, ATPase activity, K(m)(MgATP), and stimulation of ATPase by verapamil, were similar to wild-type mouse Ppg. Mouse Cys-free Pgp was superior in yield and stability to Cys-free human MDR1 Pgp. Mutants Y1040A and Y1040C were constructed in mouse Cys-free Pgp background. Both showed extremely low ATPase activity, strongly-impaired vanadate-trapping of ADP, and reduced photolabeling by 8-azido-ATP. The results are consistent with the conclusion that Tyr-1040 is located in the MgATP-binding site in NBD2 and is required for correct binding and/or orientation of bound MgATP substrate in Pgp as previously suggested by X-ray structures of other ABC transporters and by sequencing of photolabeled Pgp. The results also support our previous conclusion that both catalytic sites must be intact for normal function in Pgp.     

In vitro selection of resistant/tolerant mutants lines of Citrus jambhiri Lush. using crude culture filtrate of Phytophthora parasitica and their randomly amplified polymorphic DNA analysis

This study deals with in vitro‐induced mutagenesis and selection of Phytophthora tolerant lines of Citrus jambhiri and their regeneration. For in vitro‐induced mutagenesis, cotyledons were treated with ethyl methane sulfonate (EMS) 100, 200 and 300 mm for different time durations viz. 1, 3, 6 and 9 hr. Callus cultures were established from EMS treated cotyledon explants on MS medium supplemented with 2.0 mg/L of 2,4‐D and 500 mg/L of malt extract. Calli derived from cotyledon were challenged in vitro on selective MS medium containing 5%–100% of culture filtrate (CF) of the Phytophthora parasitica. Selected mutagen‐treated calli showed resistance in vitro on media containing CF. Calli treated with 100 mm EMS for 6‐hr duration showed tolerance (24%) up to 75% CF after 4th selection cycle. While, calli treated with 200 mm for 6‐hr duration showed maximum tolerance (76%) up to 75% CF. Resistant calli were then transferred to MS regeneration medium for shoot bud regeneration. A dose‐dependent decrease in the regeneration capacity of the selected calli was observed with the increasing concentration of the CF. In randomly amplified polymorphic DNA analysis, plantlets showed different banding pattern in comparison with the control plant, which confirms the presence of variations at genetic level.     

Identification of Variants in Primary and Recurrent Glioblastoma Using a Cancer-Specific Gene Panel and Whole Exome Sequencing

Glioblastoma (GBM) is an aggressive, malignant brain tumor typically resulting in death of the patient within one year following diagnosis; and those who survive beyond this point usually present with tumor recurrence within two years (5-year survival is 5%). The genetic heterogeneity of GBM has made the molecular characterization of these tumors an area of great interest and has led to identification of molecular subtypes in GBM. The availability of sequencing platforms that are both fast and economical can further the adoption of tumor sequencing in the clinical environment, potentially leading to identification of clinically actionable genetic targets. In this pilot study, comprised of triplet samples of normal blood, primary tumor, and recurrent tumor samples from three patients; we compared the ability of Illumina whole exome sequencing (ExomeSeq) and the Ion AmpliSeq Comprehensive Cancer Panel (CCP) to identify somatic variants in patient-paired primary and recurrent tumor samples. Thirteen genes were found to harbor variants, the majority of which were exclusive to the ExomeSeq data. Surprisingly, only two variants were identified by both platforms and they were located within the PTCH1 and NF1 genes. Although preliminary in nature, this work highlights major differences in variant identification in data generated from the two platforms. Additional studies with larger samples sizes are needed to further explore the differences between these technologies and to enhance our understanding of the clinical utility of panel based platforms in genomic profiling of brain tumors.     

Tumor metastasis to bone

Establishment of skeletal metastasis involves bidirectional interactions between the tumor cell and the cellular elements in the bone microenvironment. A better understanding of the pathophysiology of bone metastasis will be critical in developing the means to prevent bone metastasis or inhibit its progression. The receptor activator of nuclear factor-kappaB (RANK)/RANK ligand pathway has emerged as the key pathway regulating osteolysis in skeletal metastasis. A number of candidate factors, including the Wnt (wingless int) proteins, endothelin-1, and bone morphogenetic proteins, have been implicated in the establishment of osteoblastic metastasis. The complex nature of tumor-bone microenvironment interactions and the presence of multiple pathways that lead to bone metastasis suggests that simultaneous targeting of these pathways in the metastatic cascade are required for effective treatment. This review discusses current understanding of the pathophysiologic mechanisms that underlie the establishment of bone metastasis and potential molecular therapeutic strategies for prevention and treatment of bone metastasis.     

Positive effects of testosterone and immunochallenge on energy allocation to reproductive organs

A number of studies have suggested the incompatibility of simultaneous increases in immune and reproductive functions. Other research has indicated that immune responses may be modulated depending on the relative benefits of increased survival and prospects for current and future reproduction. We tested the hypothesis that energy allocation to reproductive and other organ systems is not affected by testosterone level and energy expenditure on immune functions. Adult male white-footed mice (Peromyscus leucopus) with or without elevated testosterone levels and with or without immunochallenges were tested. Testosterone treatment was associated with reduced humoral immune response indicating immunosuppressive effects, reduced masses of gastrointestinal organs, reduced corticosterone level, increased kidney and seminal vesicle masses, and increased hematocrit. Immunochallenge was associated with increased resting metabolic rate and testes and seminal vesicle masses. Reproductive organ masses were greatest in immunochallenged mice with exogenous testosterone. Simultaneous increases in energy allocation to immune and reproductive structures may be an adaptive response that would enhance survival and current prospects for reproduction.     

The nature of gene action in a Nicotiana rustica cross revealed by the recombinant inbred and second-cycle hybrid analysis

 A unique set of data recorded on 60 randomly extracted single-seed-descent (F_∞) lines of a highly heterotic cross between two varieties of Nicotiana rustica and their 870 reciprocally produced pairwise crosses, the second-cycle hybrids (SCH), are analysed to investigate the true nature of genetical control in the cross and the results are compared with those in earlier publications. The analysis revealed that epistasis, genotype-by-micro-environmental interaction, maternal effects and linkage are significant for several characters and the additive and non-additive components of variation take large values for all of the traits. Epistasis is predominantly duplicate and not complementary. Dominance is high but partial, all estimates of dominance ratio lying between 0.5 and 0.9. Dominance is predominantly unidirectional for leaf length, leaf width and final height, while for the remaining traits, some genes show ambidirectional dominance, although the incidence of unidirectional dominance is much higher throughout. The direction of dominance is predominantly for the increased score, except for flowering time where alleles conferring earliness are up to five times more frequently dominant. The present study has also confirmed that the F₂ and SCH_i distributions are very similar and that the former can be used to predict the transgression in the latter with confidence. The reduced range of the SCH _i families compared to the recombinant inbreds, further indicated that heterosis among many of the SCH_i is due to gene dispersion and there is little evidence for the presence of over-dominance. Received: 8 July 1996 / Accepted: 8 November 1996