Assignment of RAS proto-oncogenes in Chinese hamsters: implications for mammalian gene linkage conservation and neoplasia

HRAS and KRAS are the cellular homologs of the oncogenic transforming genes found in the Harvey strain of murine sarcoma virus and the Kirsten murine sarcoma virus, respectively. Phyla as diverse as insects, birds, and mammals possess distinct HRAS and KRAS sequences, suggesting that these genes are essential to metazoa. In this report, we used a clone panel of Chinese hamster X mouse C11D somatic cell hybrids segregating hamster chromosomes to map those genes. Southern filter hybridization analyses of the hybrids revealed that hamster HRAS and KRAS gene sequences are on chromosomes 3 and 8, respectively. These gene assignments are consistent with the conservation of autosomal gene linkage groups observed among hamsters, humans, and mice and may provide insight into specific chromosomal alterations that have been observed during the spontaneous neoplastic transformation of Chinese hamster fibroblasts in vitro.     

Type I interferon is required for T helper (Th) 2 induction by dendritic cells

Type 2 inflammation is a defining feature of infection with parasitic worms (helminths), as well as being responsible for widespread suffering in allergies. However, the precise mechanisms involved in T helper (Th) 2 polarization by dendritic cells (DCs) are currently unclear. We have identified a previously unrecognized role for type I IFN (IFN‐I) in enabling this process. An IFN‐I signature was evident in DCs responding to the helminth Schistosoma mansoni or the allergen house dust mite (HDM). Further, IFN‐I signaling was required for optimal DC phenotypic activation in response to helminth antigen (Ag), and efficient migration to, and localization with, T cells in the draining lymph node (dLN). Importantly, DCs generated from Ifnar1^?/? mice were incapable of initiating Th2 responses in vivo. These data demonstrate for the first time that the influence of IFN‐I is not limited to antiviral or bacterial settings but also has a central role to play in DC initiation of Th2 responses.     

Biodiversity effects of the predation gauntlet

The ubiquity of trophic downgrading has led to interest in the consequences of mesopredator release on prey communities and ecosystems. This issue is of particular concern for reef-fish communities, where predation is a key process driving ecological and evolutionary dynamics. Here, we synthesize existing experiments that have isolated the effects of mesopredators to quantify the role of predation in driving changes in the abundance and biodiversity of recently settled reef fishes. On average, predators reduced prey abundance through generalist foraging behavior, which, through a statistical sampling artifact, caused a reduction in alpha diversity and an increase in beta diversity. Thus, the synthesized experiments provide evidence that predation reduces overall abundance within prey communities, but—after accounting for sampling effects—does not cause disproportionate effects on biodiversity.

     

Genetic abnormalities in a pre and post-chemotherapy hepatoblastoma

Comparative genomic hybridization (CGH) analysis was performed on both a pre- and post-chemotherapy hepatoblastoma from a 24-month-old female patient. The diagnostic sample obtained from a tru-cut biopsy was a mixed epithelial-mesenchymal tumor with both fetal and embryonal patterns present. In contrast, the post-chemotherapy tumor exhibited a prominent anaplastic large cell population focally reminiscent of pleomorphic hepatocellular carcinoma (HCC). CGH analysis indicated that there were similarities as well as differences in the gains and losses of genetic material in each tumor. The diagnostic sample had gains of chromosome 1q, 2, 2(q31q33), 7, 8q, 12(q15q22), 17q and 20 material, while the post-chemotherapy tumor had gains of 1q, 2, 7, 8q, 10, 17q and 20 material. In addition, the pre- and post-chemotherapy samples may have incurred loss of chromosome 17p material. The main differences between the two samples involved localized gain of 2(q31q33) and 12(q15q22) in the pre-chemotherapy sample, and gain of chromosome 10 material in the post-chemotherapy tumor. The patient subsequently developed metastatic nodules in her lungs, the histology of which was identical in pattern to the diagnostic pattern, and appeared to have localized gain of 2(q31q33) and 12(q15q22). These results are consistent with published results that gain of chromosome 8q and 20 are associated with an unfavorable prognosis.     

Molecular and crystal structure of an intercalation complex: Proflavine–cytidylyl-(3′,5′)-guanosine

The high-resolution crystal and molecular structure of a 3:2 complex of proflavine and cytidylyl-(3′,5′)-guanosine is described. The complex exhibits more than one mode of dye binding to the dinucleoside phosphate. One proflavine cation is symmetrically intercalated between the base pairs. The other proflavine cations and ones related by symmetry stack above and below the base pairs and also hydrogen bond externally to the duplex. The conformation of the CpG is most similar to A-RNA with all C(3′)-endo sugar puckering. To allow the base pairs to stretch from the normal 3.4-Å separation to a 6.8-Å separation, the torsion angles ? and χ of the guanosine are increased by about 60° from the values found in RNA. The crystal structure itself contains disordered sulfate anions and is highly solvated, with all but one water molecule involved in a continuous water–sulfate channel.     

Vitamin D? Supplementation in Batswana Children and Adults with HIV: A Pilot Double Blind Randomized Controlled Trial

ObjectivesSince vitamin D insufficiency is common worldwide in people with HIV, we explored safety and efficacy of high dose cholecalciferol (D₃) in Botswana, and evaluated potential modifiers of serum 25 hydroxy vitamin D change (Δ25D).DesignProspective randomized double-blind 12-week pilot trial of subjects ages 5.0–50.9 years.MethodsSixty subjects randomized within five age groups to either 4000 or 7000IU per day of D₃ and evaluated for vitamin D, parathyroid hormone, HIV, safety and growth status. Efficacy was defined as serum 25 hydroxy vitamin D (25D) ≥32ng/mL, and safety as no simultaneous elevation of serum calcium and 25D. Also assessed were HIV plasma viral RNA viral load (VL), CD4%, anti-retroviral therapy (ART) regime, and height-adjusted (HAZ), weight-adjusted (WAZ) and Body Mass Index (BMIZ) Z scores.ResultsSubjects were 50% male, age (mean±SD) 19.5±11.8 years, CD4% 31.8±10.4, with baseline VL log₁₀ range of <1.4 to 3.8 and VL detectable (>1.4) in 22%. From baseline to 12 weeks, 25D increased from 36±9ng/ml to 56±18ng/ml (p<0.0001) and 68% and 90% had 25D ≥32ng/ml, respectively (p = 0.02). Δ25D was similar by dose. No subjects had simultaneously increased serum calcium and 25D. WAZ and BMIZ improved by 12 weeks (p<0.04). HAZ and CD4% increased and VL decreased in the 7000IU/d group (p<0.04). Younger (5–13y) and older (30–50y) subjects had greater Δ25D than those 14–29y (26±17 and 28±12 vs. 11±11ng/ml, respectively, p≤0.001). Δ25D was higher with efavirenz or nevirapine compared to protease inhibitor based treatment (22±12, 27±17, vs. 13±10, respectively, p≤0.03).ConclusionsIn a pilot study in Botswana, 12-week high dose D₃ supplementation was safe and improved vitamin D, growth and HIV status; age and ART regimen were significant effect modifiers.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT02189902","term_id":"NCT02189902"}}NCT02189902     

Origin and functional significance of large-scale chromosomal imbalances in neuroblastoma

Neuroblastoma is characterized by numerous recurrent large-scale chromosomal imbalances and gene amplifications which are associated with poor clinical outcome. The most common include MYCN amplification, loss of 1p, 3p and 11q, and gain of 17q genomic regions. Two of these abnormalities, MYCN amplification and loss of 11q, define different genetic subtypes of the disease with vastly different global gene expression profiles. The progress towards the identification of the genes and genetic pathways that have been affected by these abnormalities is reviewed and high resolution mapping of the chromosomal breakpoint regions using oligonucleotide array CGH (oaCGH) is discussed. oaCGH analysis is proving useful for both defining minimal regions of overlap of imbalances, as well as providing information on the molecular mechanisms that generate the chromosomal imbalances. These high resolution analyses have also permitted the detection of micro-deletions in the tumors that further assist in identifying genes important for neuroblastoma pathogenesis.     

Intercalation Model for DNA-Cross Linking in a 1-Nitro-9-aminoacridine Derivative,an Analog of the Antitumor Agent “Ledakrin” (Nitracrine)

Abstract

Ledakrin (nitracrine), C-283, is a 1-nitro-9-aminoacridine derivative that is used in Poland as an antitumor agent. In order to investigate the basis of the activity of this compound the structure of another analog, [9-(3-dimethyl-l-methylpropylimino)-l-nitro-9, 10-dihydroacridine], C-829, that has similar activity, was determined by X-ray crystallographic techniques and was compared with that of ledakrin, already reported in the literature. In both molecules the proximity of the 1-nitro to the substituted 9-aminoacridine group causes extensive distortions. These compounds are believed to act, after metabolic “activation”, by cross-linking DNA. Such cross-linking does not occur in the absence of the 1-nitro group or if the nitro group is moved to the 2-, 3- or 4-position. Computer-assisted model-building has been used to test possible intercalative models. It has shown that functional groups on C-829 or C-283 are, when the acridine portion of the molecule is intercalated as in a proflavine dinucleoside phosphate complex, in positions suitable for DNA cross-linking by activated 1-nitro- 9-aminoacridine derivatives.     

Energy allocation in juveniles of a warm-temperate reef fish

During the first year of life, organisms are faced with competing demands for energy between growth and storage. Most research on energy allocation in young fishes has focused on cold-temperate species which are subjected to strong seasonal fluctuations in productivity, while few studies have considered those at lower latitudes where seasonality is less pronounced. Gag (Mycteroperca microlepis) of the northeastern Gulf of Mexico settle in coastal seagrass beds in the spring as juveniles and emigrate to offshore reefs in the fall. Upon settlement, these young fish grow at remarkably fast rates, but their growth slows considerably before emigration. Slowed growth can be explained by one of three hypotheses: (1) size-specific emigration times; (2) reduced feeding efficiency associated with declines in primary and secondary productivity; or (3) energetic shifts in allocation from growth to storage. Gag emigrate essentially as a cohort, so slowed growth does not result from differential emigration patterns based on fish size. They also emigrate before seasonal declines in primary and secondary productivity; thus, food remains abundant and feeding efficiency constant. The more plausible hypothesis is that there is an energetic shift from growth to storage. The liver serves as the primary site of lipid storage and the hepatosomatic index of juvenile gag increases coincident with reduced growth. The overall effect of increased energy stores is presumably for use during offshore migration and/or for overwinter survival.