Assessment of Rival Males through the Use of Multiple Sensory Cues in the Fruitfly Drosophila pseudoobscura

Environments vary stochastically, and animals need to behave in ways that best fit the conditions in which they find themselves. The social environment is particularly variable, and responding appropriately to it can be vital for an animal’s success. However, cues of social environment are not always reliable, and animals may need to balance accuracy against the risk of failing to respond if local conditions or interfering signals prevent them detecting a cue. Recent work has shown that many male Drosophila fruit flies respond to the presence of rival males, and that these responses increase their success in acquiring mates and fathering offspring. In Drosophila melanogaster males detect rivals using auditory, tactile and olfactory cues. However, males fail to respond to rivals if any two of these senses are not functioning: a single cue is not enough to produce a response. Here we examined cue use in the detection of rival males in a distantly related Drosophila species, D. pseudoobscura, where auditory, olfactory, tactile and visual cues were manipulated to assess the importance of each sensory cue singly and in combination. In contrast to D. melanogaster, male D. pseudoobscura require intact olfactory and tactile cues to respond to rivals. Visual cues were not important for detecting rival D. pseudoobscura, while results on auditory cues appeared puzzling. This difference in cue use in two species in the same genus suggests that cue use is evolutionarily labile, and may evolve in response to ecological or life history differences between species.     

Regulation and Methylation of Tumor Suppressor MiR-124 by Androgen Receptor in Prostate Cancer Cells

Prostate cancer (PCa) is the most frequently diagnosed cancer for men in the developed world. Androgen receptor signaling pathway plays an important role in prostate cancer progression. Recent studies show that microRNA miR-124 exerts a tumor suppressive function in prostate cancer. However, the relationship between AR and miR-124 is unclear. In the present study, we found a negative feedback loop between AR and miR-124 expression. On one hand, miR-124 was a positively regulated target gene of the AR, on the other hand, overexpression of miR-124 inhibited the expression of AR. In addition, we found that miR-124-2 and miR-124-3 promoters were hypermethylated in AR-negative PCa cells. Furthermore, overexpression of miR-124 inhibited proliferation rates and invasiveness capacity of PCa cells in vitro, and suppressed xenograft tumor growth in vivo. Taken together, our results support a negative feedback loop between AR and miR-124 expression. Methylation of miR-124-2 and miR-124-3 may serve as a biomarker for AR-negative PCa cells, and overexpression of miR-124 might be of potential therapeutic value for the treatment of PCa.     

Detecting Minimal Hepatic Encephalopathy in an Endemic Country for Hepatitis B: The Role of Psychometrics and Serum IL-6

Background & Aims

It remains unknown what the prevalence of minimal hepatic encephalopathy is in Taiwan, a highly endemic country for chronic viral hepatitis infection. It is also unclear whether abnormal serum cytokine levels can be indicative of the presence of minimal hepatic encephalopathy. We aimed to standardize the tests of psychometric hepatic encephalopathy score and predictive value of proinflammatory cytokines in minimal hepatic encephalopathy in Taiwan.

Methods

180 healthy subjects and 94 cirrhotic patients without a history of overt hepatic encephalopathy from a tertiary center were invited to participate in this cross-sectional study. Blood sampling for determination of serum levels of interleukin 6 and 18 and tumor necrosis factor-α was performed. Based on the normogram of psychometric hepatic encephalopathy score from healthy volunteers, patients with minimal hepatic encephalopathy were identified from the cirrhotic patients using the criterion of a psychometric hepatic encephalopathy score less than −4.

Results

In the healthy subjects, age and education were predictors of subtests of psychometric hepatic encephalopathy score. Minimal hepatic encephalopathy was identified in 27 (29%) cirrhotic patients. Serum interleukin 6 level (OR = 6.50, 95% CI = 1.64–25.76, P = 0.008) was predictive of the presence of minimal hepatic encephalopathy after multivariate analysis.

Conclusions

The psychometric hepatic encephalopathy score can be a useful tool for detecting patients with minimal hepatic encephalopathy in Taiwan and around one third of cirrhotic outpatients fulfill this diagnosis. A high serum interleukin 6 level is predictive of the presence of minimal hepatic encephalopathy.     

Multiple origin of metallicolous populations of the pseudometallophyte Arabidopsis halleri (Brassicaceae) in central Europe: the cpDNA testimony

The population structure of the pseudo-metallophyte herb, Arabidopsis halleri, was studied using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) on chloroplast DNA (cpDNA). The history of metallicolous (M) populations showing increased zinc tolerance was investigated. Eight primer-enzyme combinations out of 72 tested were applied to a total of 625 individuals from 28 widespread populations, 14 of them being M. Eleven distinct chlorotypes were found: five were common to nonmetallicolous (NM) and M populations, whereas six were only observed in one edaphic type (five in NM and one in M). No difference in chlorotype diversity between edaphic types was detected. Computed on the basis of chlorotype frequencies, the level of population differentiation was high but remained the same when taking into account levels of molecular divergence between chlorotypes. Isolation by distance was largely responsible for population differentiation. Geographically isolated groups of M populations were more genetically related to their closest NM populations than to each other. Our results suggest that M populations have been founded separately from distinct NM populations without suffering founding events and that the evolution towards increased tolerance observed in the distinct M population groups occurred independently.     

BAFF inhibition: a new class of drugs for the treatment of autoimmunity

BAFF (BLyS) and APRIL are TNF-like cytokines that support survival and differentiation of B cells. Recent studies have discovered a role for BAFF in augmenting both innate and adaptive immune responses as well as in collaborating with other inflammatory cytokines to promote the activation and differentiation of effector immune cells. BAFF is an important pathogenic factor in lupus mouse models and BAFF inhibition successfully delays disease onset in these mice, although the responsiveness to BAFF inhibition varies among different strains. These results have led to the development of inhibitors targeting BAFF and APRIL in humans. An anti-BAFF antibody has shown significant but modest efficacy in two Phase III clinical trials for moderately active SLE and other inhibitors are being developed or at early stages of clinical testing.     

Secreted PCSK9 downregulates low density lipoprotein receptor through receptor-mediated endocytosis

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protease that regulates low density lipoprotein receptor (LDLR) protein levels. The mechanisms of this action, however, remain to be defined. We show here that recombinant human PCSK9 expressed in HEK293 cells was readily secreted into the medium, with the prosegment associated with the C-terminal domain. Secreted PCSK9 mediated cell surface LDLR degradation in a concentration- and time-dependent manner when added to HEK293 cells. Accordingly, cellular LDL uptake was significantly reduced as well. When infused directly into C57B6 mice, purified human PCSK9 substantially reduced hepatic LDLR protein levels and resulted in increased plasma LDL cholesterol. When added to culture medium, fluorescently labeled PCSK9 was endocytosed and displayed endosomal-lysosomal intracellular localization in HepG2 cells, as was demonstrated by colocalization with DiI-LDL. PCSK9 endocytosis was mediated by LDLR as LDLR deficiency (hepatocytes from LDLR null mice), or RNA interference-mediated knockdown of LDLR markedly reduced PCSK9 endocytosis. In addition, RNA interference knockdown of the autosomal recessive hypercholesterolemia (ARH) gene product also significantly reduced PCSK9 endocytosis. Biochemical analysis revealed that the LDLR extracellular domain interacted directly with secreted PCSK9; thus, overexpression of the LDLR extracellular domain was able to attenuate the reduction of cell surface LDLR levels by secreted PCSK9. Together, these results reveal that secreted PCSK9 retains biological activity, is able to bind directly to the LDLR extracellular domain, and undergoes LDLR-ARH-mediated endocytosis, leading to accelerated intracellular degradation of the LDLR.     

Kinetics of the interactions between yeast elongation factors 1A and 1Balpha, guanine nucleotides, and aminoacyl-tRNA

The interactions of elongation factor 1A (eEF1A) from Saccharomyces cerevisiae with elongation factor 1Balpha (eEF1Balpha), guanine nucleotides, and aminoacyl-tRNA were studied kinetically by fluorescence stopped-flow. eEF1A has similar affinities for GDP and GTP, 0.4 and 1.1 microm, respectively. Dissociation of nucleotides from eEF1A in the absence of the guanine nucleotide exchange factor is slow (about 0.1 s(-1)) and is accelerated by eEF1Balpha by 320-fold and 250-fold for GDP and GTP, respectively. The rate constant of eEF1Balpha binding to eEF1A (10(7)-10(8) M (-1) s(-1)) is independent of guanine nucleotides. At the concentrations of nucleotides and factors prevailing in the cell, the overall exchange rate is expected to be in the range of 6 s(-1), which is compatible with the rate of protein synthesis in the cell. eEF1A.GTP binds Phe-tRNA(Phe) with a K(d) of 3 nm, whereas eEF1A.GDP shows no significant binding, indicating that eEF1A has similar tRNA binding properties as its prokaryotic homolog, EF-Tu.     

Assessment of algorithms for high throughput detection of genomic copy number variation in oligonucleotide microarray data

Background

Genomic deletions and duplications are important in the pathogenesis of diseases, such as cancer and mental retardation, and have recently been shown to occur frequently in unaffected individuals as polymorphisms. Affymetrix GeneChip whole genome sampling analysis (WGSA) combined with 100 K single nucleotide polymorphism (SNP) genotyping arrays is one of several microarray-based approaches that are now being used to detect such structural genomic changes. The popularity of this technology and its associated open source data format have resulted in the development of an increasing number of software packages for the analysis of copy number changes using these SNP arrays.

Results

We evaluated four publicly available software packages for high throughput copy number analysis using synthetic and empirical 100 K SNP array data sets, the latter obtained from 107 mental retardation (MR) patients and their unaffected parents and siblings. We evaluated the software with regards to overall suitability for high-throughput 100 K SNP array data analysis, as well as effectiveness of normalization, scaling with various reference sets and feature extraction, as well as true and false positive rates of genomic copy number variant (CNV) detection.

Conclusion

We observed considerable variation among the numbers and types of candidate CNVs detected by different analysis approaches, and found that multiple programs were needed to find all real aberrations in our test set. The frequency of false positive deletions was substantial, but could be greatly reduced by using the SNP genotype information to confirm loss of heterozygosity.     

The heme transfer from the soluble HasA hemophore to its membrane-bound receptor HasR is driven by protein-protein interaction from a high to a lower affinity binding site

HasA is an extracellular heme binding protein, and HasR is an outer membrane receptor protein from Serratia marcescens. They are the initial partners of a heme internalization system allowing S. marcescens to scavenge heme at very low concentrations due to the very high affinity of HasA for heme (Ka = 5,3 x 10(10) m(-1)). Heme is then transferred to HasR, which has a lower affinity for heme. The mechanism of the heme transfer between HasA and HasR is largely unknown. HasR has been overexpressed and purified in holo and apo forms. It binds one heme molecule with a Ka of 5 x 10(6) m(-1) and shows the characteristic absorbance spectrum of a low spin heme iron. Both holoHasA and apoHasA bind tightly to apoHasR in a 1:1 stoichiometry. In this study we show that heme transfer occurs in vitro in the purified HasA.HasR complex, demonstrating that heme transfer is energy- and TonB complex-independent and driven by a protein-protein interaction. We also show that heme binding to HasR involves two conserved histidine residues.     

Apoptotic effects of over-expressed estrogen receptor-beta on LoVo colon cancer cell is mediated by p53 signalings in a ligand-dependent manner

Epidemiologic studies reported that the prevalence of hereditary non-polyposis colon cancer (HNPCC) in male is about 1.5-fold higher than that in female. Decreases in circulatory estradiol (E2) have been reported to downregulate the expression of E2 receptor (ER) and significantly increase the risk of colorectal cancer. Patients that received E2 replacement therapy were found to have a reduction in the incidence of colon adenoma and carcinoma. Furthermore, significant decreases in the expression of ER have been found in colorectal cancer specimens. These data strongly suggest the protective roles of E2 and ER against colorectal cancer. However, the mechanisms remain unexplored. LoVo cells were transient transfected to overexpress ER-beta, DNA fragmentation and caspase activity assay were performed to evaluate apoptotic effects. Western blotting was used to evaluate protein levels, and luciferase activity assay to measure the TNF-alpha promoter activity. Our data clearly demonstrated that E2 and ER-beta alone could upregulate p21 and p27 proteins, which further activate caspase-8 and caspase-9 to induce apoptosis in LoVo cell, and the ER-beta. effects were enhanced by E2. However, overexpressed ER-beta did not influence the expression and promoter activity of TNF-alpha. In addition, E2 and overexpressed ER-beta downregulated the beta-catenin proteins which cause the downregulation of its target genes, cyclin D1 and Rb, to inhibit the cell cycle and cell proliferation. The results indicate that overexpressed ER-beta may induce LoVo cell apoptosis and anti-proliferation by increasing p53 signaling in a ligand-dependent manner, and without hTNF-alpha involvement. Efforts aiming at enhancing ER-beta expression and/or activity may prove to be an attractive alternative therapy against colorectal cancer.