Inhibition of a nutrient-dependent pinocytosis in dictyostelium discoideum by the amino acid analogue hadacidin

In the present study we examine the effects of the drug hadacidin (N-formyl-N- hydroxyglycine) on pinocytosis in the eukaryotic microorganism dictyostelium discoideum. At concentrations of up to approximately 8 mg/ml, hadacidin inhibited the rate of pinocytosis of fluorescein isothiocyanate (FITC) dextran in cells in growth medium in a concentration-dependent manner but had no effect on cells in starvation medium. Because hadacidin also inhibits cellular proliferation at this concentration, the relationship between growth rate and pinocytosis was studied further using another drug, cerulenin, to produce growth-arrest. These experiments showed no changes in the rate pinocytosis even after complete cessation of cellular proliferation. Other studies showed that the transfer of cells from growth to starvation medium reduced the rate of pinocytosis by approximately 50 percent. A reduction of similar magnitude occurred if cells were transferred from growth to starvation medium containing hadacidin. Also, no additional reduction in pinocytosis occurred when cells that had been treated with hadacidin were transferred to starvation medium containing hadacidin. These cells were able to take up [(14)C]hadacidin in the starvation medium. In contrast to the results with hadacidin-treated cells, cells in a cerulenin-induced state of growth-arrest when transferred to starvation medium exhibited the same 50 percent reduction in pinocytosis observed in cells not previously exposed to either drug. Cells treated with azide, in either growth or starvation medium, exhibited an immediate inhibition of all pinocytotic activity. After the transfer of log-phase cells to starvation medium supplemented with glucose, the reduction in rate was only approximately 10-15 percent. In contrast, a 50 percent reduction was observed after supplementation of starvation medium with sucrose, KCl, or concanavalin A. Maintaining the cells in growth medium containing hadacidin for as long as 16 h had no effect on the rate at which cells aggregated. These results are consistent with the conclusion that D. discoideum exhibits two types of pinocytotic activity: one that is nutrient dependent and the other independent of nutrients. This latter activity persists in starvation medium and is unaffected by hadacidin, whereas the nutrient-dependent activity is present in growth medium and is inhibited by hadacidin.     

Extracts of black and brown rice powders improve hepatic lipid accumulation via the activation of PPARα in obese and diabetic model mice

Rice powder extract (RPE) from black and brown rice (Oryza sativa L. indica) improves hepatic lipid accumulation in obese and diabetic model mice via peroxisomal fatty acid oxidation. RPE showed PPARα agonistic activity which did not differ between black and brown RPE despite a higher anthocyanin content in black RPE.     

Phylogeography of the socially polymorphic sweat bee Halictus rubicundus (Hymenoptera: Halictidae)

The evolution of sociality in insects holds a central place in evolutionary theory. By examining the phylogenetic patterns of solitary and social behavior and how they correlate with ecological variables, we may identify factors important in the evolution of sociality. In this study, we investigated historical and biogeographical patterns of sociality in a socially polymorphic bee species (one that demonstrates both social and solitary nesting behavior). This unique system allows for a more powerful examination of evolutionary transitions in sociality than interspecific studies of obligately social and solitary species. We conducted a phylogenetic analysis among populations of the halictine bee Halictus rubicundus and then identified relationships among mitochondrial DNA sequence data, sociality, environmental conditions at the nesting site, and geographic location of populations of this species. Within North America, populations of H. rubicundus expressing social and solitary behavior belong to different genetic lineages. Sociality is also correlated with at least one environmental variable used in this study. Taken together, the results support the predictions for genetic control of sociality, but they are still consistent with social behavior at some level being determined by the environmental conditions at the nesting site.     

Selective release of microRNA species from normal and malignant mammary epithelial cells

MicroRNAs (miRNAs) in body fluids are candidate diagnostics for a variety of conditions and diseases, including breast cancer. One premise for using extracellular miRNAs to diagnose disease is the notion that the abundance of the miRNAs in body fluids reflects their abundance in the abnormal cells causing the disease. As a result, the search for such diagnostics in body fluids has focused on miRNAs that are abundant in the cells of origin. Here we report that released miRNAs do not necessarily reflect the abundance of miRNA in the cell of origin. We find that release of miRNAs from cells into blood, milk and ductal fluids is selective and that the selection of released miRNAs may correlate with malignancy. In particular, the bulk of miR-451 and miR-1246 produced by malignant mammary epithelial cells was released, but the majority of these miRNAs produced by non-malignant mammary epithelial cells was retained. Our findings suggest the existence of a cellular selection mechanism for miRNA release and indicate that the extracellular and cellular miRNA profiles differ. This selective release of miRNAs is an important consideration for the identification of circulating miRNAs as biomarkers of disease.     

NESTMATE RELATEDNESS IN A COMMUNAL BEE,PERDITA TEXANA (HYMENOPTERA: ANDRENIDAE), BASED ON DNA FINGERPRINTING

Perdita texana is a facultatively communal bee species with up to 28 females per nest. We used multilocus DNA fingerprinting to test the hypothesis that nestmates are more closely related to each other than are nonnestmates. The mean band sharing proportion among pairwise nestmate comparisons did not differ significantly from the mean among nonnestmate comparisons [P = 0.787 (df = 484)]. Although mean band sharing proportions did not differ among nestmates and nonnestmates, some nestmates show very high band sharing proportions (in excess of the upper 95% confidence limit for the nonnestmate mean). These individuals almost certainly are related, probably as half-sib sisters, however, they comprise a very small percentage of the nestmate populations. Our results indicate that kin selection is unlikely to play an important role in the evolution and maintenance of communal nesting. Communal societies most likely arise because of the mutualistic benefits of cooperative nesting, including accelerated nest founding and improved nest defense.     

Rapid repeated cloning of mutant lac repressor genes

We have developed a procedure to efficiently recover lac repressor mutations (lacI-) from F'lac onto a single-stranded M13 phage vector. The recovery is based on homologous recombination between F'lac and an M13lac vector. This vector, mRS81, carries the entire Escherichia coli lacI gene as well as the adjacent alpha-complementation region of the lacZ gene, inserted in the AvaI site of the M13 ori region. It also carries a single point mutation in lacZ- alpha which abolishes its alpha-complementing ability. Recovery of lacI- genes from F is based on the conversion of this lacI+Z- alpha phage to lacI-Z+ alpha by recombination with F'lacI-Z+. This double exchange restores its alpha-complementing ability in the absence of any inducer of the lac operon. Detection requires a lacI- alpha-complementation host, which was also constructed in this study. The procedure was developed to obtain rapid nucleotide sequence information on large collections of lacI mutants for the purpose of studying mutational mechanisms and specificities.     

Evidence for a free-living life stage of the blue crab parasitic dinoflagelate, Hematodinium sp.

Hematodinium sp. is a parasitic dinoflagellate reported to cause disease and death in a variety of crustacean species including the blue crab (Callinectes sapidus). However, because of difficulties in the culture of Hematodinium sp. associated with blue crabs, little is known about its life cycle or mode of transmission. Here, we report the first detection of this organism outside of a metazoan host and provide evidence that this life stage can act as an infective agent. Observations of dinospores in crab hemolymph samples suggest that dinospores may be responsible for waterborne disease transmission. Additionally, we developed and validated a quantitative Real Time PCR assay for the detection of Hematodinium sp. inside and outside of a host organism that will be useful for future investigations of Hematodinium biology and Hematodinium sp.-infection etiology. Based on the observations of a free-living form of Hematodinium sp. and the association of this parasite with a widespread epizootic in blue crab populations, we propose that Hematodinium sp. be considered a Harmful Algal Bloom species.     

Lessons from assembling UCEs: A comparison of common methods and the case of Clavinomia (Halictidae)

Sequence data assembly is a foundational step in high-throughput sequencing, with untold consequences for downstream analyses. Despite this, few studies have interrogated the many methods for assembling phylogenomic UCE data for their comparative efficacy, or for how outputs may be impacted. We study this by comparing the most commonly used assembly methods for UCEs in the under-studied bee lineage Nomiinae and a representative sampling of relatives. Data for 63 UCE-only and 75 mixed taxa were assembled with five methods, including ABySS, HybPiper, SPAdes, Trinity and Velvet, and then benchmarked for their relative performance in terms of locus capture parameters and phylogenetic reconstruction. Unexpectedly, Trinity and Velvet trailed the other methods in terms of locus capture and DNA matrix density, whereas SPAdes performed favourably in most assessed metrics. In comparison with SPAdes, the guided-assembly approach HybPiper generally recovered the highest quality loci but in lower numbers. Based on our results, we formally move Clavinomia to Dieunomiini and render Epinomia once more a subgenus of Dieunomia. We strongly advise that future studies more closely examine the influence of assembly approach on their results, or, minimally, use better-performing assembly methods such as SPAdes or HybPiper. In this way, we can move forward with phylogenomic studies in a more standardized, comparable manner.