Somatic cell mapping, polymorphism, and linkage analysis of bovine prolactin-related proteins and placental lactogen.

The bovine prolactin gene family includes novel members expressed in the fetal placenta that are distinct from placental lactogen. In this study, we investigated the genetic organization of four members of this gene family (PRP1, PRP3, PRP6, and PRP10) as well as placental lactogen (PL). Using a bovine-rodent hybrid somatic cell panel, all five genes were assigned to bovine chromosome 23, which contains prolactin and the major histocompatibility group (BOLA). Restriction fragment length polymorphisms were detected by all probes in breeding populations with the restriction enzyme MspI, whereas no polymorphisms were detected with BamHI. EcoRI, HindIII, TaqI, and PstI produced polymorphic fragments with some but not all of the probes tested. A PRP10 polymorphism, which is apparently the result of a insertion/deletion event, detected polymorphism frequency differences between Bos indicus and Bos taurus. No recombinational events were observed with these probes and prolactin using linkage analysis involving 91 American Holsteins. The bovine prolactin gene family was incorporated into a linkage group containing CYP21. Our studies demonstrate that members of the bovine prolactin gene family have a close physical association with each other, and all members demonstrate genetic variability in the breeding population.     

(+/-)2,3-Dihydroxypropyl dichloroacetate, an inhibitor of glycerol kinase

Of a range of glycerol analogues, (+/-)-2,3-dihydroxypropyl dichloroacetate (III) has been shown to be the most potent inhibitor of glycerol kinase in vitro. Inhibition is noncompetitive with a Ki value of 1.8 X 10(-3) M. The presence of ATP seems essential for effective inhibition of the enzyme, suggesting that the inhibitor is phosphorylated to a glycerol-3-phosphate analogue. In vivo III causes a decrease in the specific activity of liver glycerol kinase and produces a dose-dependent reduction in blood glucose levels. There is a reduction in the conversion of [U-14C] glycerol into glucose after administration of III to CBA/CA mice while gluconeogenesis from fructose is increased. This suggests that of the enzymes of gluconeogenesis only glycerol kinase is inhibited by III. This compound may be useful in reducing the lipid contribution to gluconeogenesis in advancing cancer.     

Mapping HSA10 homologous loci in cattle.

Loci homologous to those on human chromosome 10 (HSA10) map to five mouse chromosomes, MMU2, MMU7, MMU10, MMU14, and MMU19. In cattle, one unassigned syntenic group (U26) was previously defined by the HSA10/MMU19 isoenzyme marker glutamic-oxaloacetic transaminase 1 (GOT1). To evaluate the syntenic arrangement of other HSA10 loci in cattle, seven genes were physically mapped by segregation analysis in a bovine x hamster hybrid somatic cell panel. The genes mapped include: vimentin (VIM) on HSA10 and MMU2; interleukin 2 receptor (IL2R) on HSA10 and MMU?; ornithine aminotransferase (OAT) on HSA10 and MMU7; hexokinase 1 (HK1) on HSA10 and MMU10; retinol-binding protein 3 (RBP3) on HSA10 and MMU14; plasminogen activator, urokinase type (PLAU) on HSA10 and MMU14; and alpha-2-adrenergic receptor (ADRA2) on HSA10 and MMU19. VIM and IL2R mapped to U11; ADRA2 and OAT mapped to U26; and RBP3, PLAU, and HK1 mapped to U28.     

Quantitative PCR assays for mouse enteric flora reveal strain-dependent differences in composition that are influenced by the microenvironment

The mammalian gastrointestinal (GI) tract is inhabited by over a hundred species of symbiotic bacteria. Differences among individuals in the composition of the GI flora may contribute to variation in in vivo experimental analyses and disease susceptibility. To investigate potential interindividual differences in GI flora composition, we developed real-time quantitative PCR-based assays for the detection of the eight members of the Altered Schaedler Flora (ASF) as representative members of different bacterial niches within the mammalian GI tract. Quantitative and reproducible strain-specific variations in the numbers of the ASF members were observed across 23 different barrier-housed inbred mouse strains, suggesting that the ASF assays can be used as sentinels for changes in GI flora composition. A significant cage effect was also detected. Isogenic mice that cohabited at weaning, whether from the same or different litters, showed little variation in ASF profiles. Conversely, litters split among different cages at weaning showed divergence in ASF profiles after three weeks. Individual ASF profiles, once established, were highly stable over time in the absence of environmental perturbation. Furthermore, cohabitation of different inbred strains maintained most of the interstrain variation in the GI flora, supporting a role of host genetics in determining GI flora composition.     

Meeting report for the 4th Annual Complex Trait Consortium Meeting: From QTLs to Systems Genetics

The fourth annual meeting of the Complex Trait Consortium (CTC) was held in Groningen, the Netherlands on June 26–29, 2005. This meeting, which set a new attendance record, followed three previous and highly successful meetings. The focus at this meeting was on continued resource development and the exiting new field of systems genetics, the integration and anchoring of multi-dimensional data-types to underlying genetic variation. A new aspect at the meeting was the three-minute, ‘come see my poster’ presentations that generated significant interaction at the poster sessions. If the 2005 meeting is an indicator of things to come, future meetings promise to offer even more exciting research efforts to integrate high-throughput biological measurements with genetic variation to unravel the mechanisms responsible for inter-individual variation.     

Efficacy of EGFR inhibition is modulated by model, sex, genetic background and diet: implications for preclinical cancer prevention and therapy trials

Molecule-targeted therapies are being widely developed and deployed, but they are frequently less effective in clinical trials than predicted based upon preclinical studies. Frequently, only a single model or genetic background is utilized using diets that are not relevant to that consumed by most cancer patients, which may contribute to the lack of predictability of many preclinical therapeutic studies. Inhibition of epidermal growth factor receptor (EGFR) in colorectal cancer was used to investigate potential causes for low predictive values of many preclinical studies. The efficacy of the small molecule EGFR inhibitor AG1478 was evaluated using two mouse models, Apc(Min/+) and azoxymethane (AOM), both sexes on three genetic backgrounds, C57BL/6J (B6) and A/J (A) inbred strains and AB6F1 hybrids, and two diets, standard chow (STD) or Western-style diet (WD). AG1478 has significant anti-tumor activity in the B6-Apc(Min/+) model with STD but only moderately on the WD and in the AOM model on an A background with a WD but not STD. On the F1 hybrid background AG1478 is effective in the Apc(Min/+) model with either STD or WD, but has only moderate efficacy in the AOM model with either diet. Sex differences were also observed. Unexpectedly, the level of liver EGFR phosphorylation inhibition by AG1478 was not positively correlated with inhibition of tumor growth in the AOM model. Model-dependent interactions between genetic background and diet can dramatically impact preclinical results, and indicate that low predictive values of preclinical studies can be attributed to study designs that do not account for the heterogeneous patient population or the diets they consume. Better-designed preclinical studies should lead to more accurate predictions of therapeutic response in the clinic.