Mitochondrial polymorphism shapes intrapopulation behavioural variation in wild Drosophila

Intrapopulation variation in behaviour, including activity, boldness and aggressiveness, is becoming more widely recognized and is hypothesized to substantially affect ecological and evolutionary dynamics. Although previous studies used candidate-gene approaches and genome-wide association analyses to identify genes correlated with variations in activity and aggressiveness, behavioural variation may not be fully captured in the nuclear genome, as it does not account for mitochondrial genomes. Mitochondrial genes encode products that are key regulators of the cellular energy-producing pathways in metabolic processes and are thought to play a significant role in life-history and reproductive traits. In this study, we considered many isofemale lines of Drosophila immigrans established from two wild populations to investigate whether intrapopulation variation in the mitochondrial genome affected activity level within this species. We identified two major haplogroups in these populations, and activity levels in both larvae and adults differed significantly between the two haplogroups. This result indicated that intrapopulation variation in activity level may be partially controlled by mitochondrial genes, along with the interaction between nuclear and mitochondrial genes and the age of individual organisms.     

Heterologous expression and characterization of processing ��-glucosidase I from Aspergillus brasiliensis ATCC 9642

A gene for processing α-glucosidase I from a filamentous fungus, Aspergillus brasiliensis (formerly called Aspergillus niger) ATCC 9642 was cloned and fused to a glutathione S-transferase tag. The active construct with the highest production level was a truncation mutant deleting the first 16 residues of the hydrophobic N-terminal domain. This fusion enzyme hydrolyzed pyridylaminated (PA-) oligosaccharides Glc(3)Man(9)GlcNAc(2)-PA and Glc(3)Man(4)-PA and the products were identified as Glc(2)Man(9)GlcNAc(2)-PA and Glc(2)Man(4)-PA, respectively. Saturation curves were obtained for both Glc(3)Man(9)GlcNAc(2)-PA and Glc(3)Man(4)-PA, and the K (m) values for both substrates were estimated in the micromolar range. When 1 μM Glc(3)Man(4)-PA was used as a substrate, the inhibitors kojibiose and 1-deoxynojirimycin had similar effects on the enzyme; at 20 μM concentration, both inhibitors reduced activity by 50%.     

Tumor‐suppressive roles of ΔNp63β‐miR‐205 axis in epithelial–mesenchymal transition of oral squamous cell carcinoma via targeting ZEB1 and ZEB2

We previously revealed that epithelial‐to‐mesenchymal transition (EMT) was mediated by ΔNp63β, a splicing variant of ΔNp63, in oral squamous cell carcinoma (OSCC). Recent studies have highlighted the involvement of microRNA (miRNA) in EMT of cancer cells, though the mechanism remains unclear. To identify miRNAs responsible for ΔNp63β‐mediated EMT, miRNA microarray analyses were performed by ΔNp63β‐overexpression in OSCC cells; SQUU‐B, which lacks ΔNp63 expression and displays EMT phenotypes. miRNAs microarray analyses revealed miR‐205 was the most up‐regulated following ΔNp63β‐overexpression. In OSCC cells, miR‐205 expression was positively associated with ΔNp63 and negatively with zinc‐finger E‐box binding homeobox (ZEB) 1 and ZEB2, potential targets of miR‐205. miR‐205 overexpression by miR‐205 mimic transfection into SQUU‐B cells led to decreasing ZEB1, ZEB2, and mesenchymal markers, increasing epithelial markers, and reducing cell motilities, suggesting inhibition of EMT phenotype. Interestingly, the results opposite to this phenomenon were obtained by transfection of miR‐205 inhibitor into OSCC cells, which express ΔNp63 and miR‐205. Furthermore, target protector analyses revealed direct regulation by miR‐205 of ZEB1 and ZEB2 expression. These results showed tumor‐suppressive roles of ΔNp63β and miR‐205 by inhibiting EMT thorough modulating ZEB1 and ZEB2 expression in OSCC.     

Surface plasmon resonance characterization of specific binding of polyglutamine aggregation inhibitors to the expanded polyglutamine stretch

Proteins with an abnormally expanded polyglutamine (polyQ) stretch are prone to change their conformations, leading to their aggregation, and cause inherited neurodegenerative diseases called the polyQ diseases. Although screening for polyQ aggregation inhibitors has been extensively performed, many common false-positive hits have been identified so far. In this study, we employed surface plasmon resonance (SPR) to characterize the binding specificities and affinities of polyQ aggregation inhibitors to the expanded polyQ stretch. SPR successfully detected specific binding of polyQ binding peptide 1 (QBP1) to the expanded polyQ stretch (K_d = 5.7 μM), and non-specific binding of Congo red to polyQ proteins independent of their polyQ-length. Binding affinities of polyQ aggregation inhibitors to the expanded polyQ stretch were correlated with their inhibitory effects on polyQ aggregation. We therefore conclude that SPR is a useful technique for screening for specific polyQ aggregation inhibitors as promising therapeutic candidates for the currently untreatable polyQ diseases.     

Diurnal changes and frequency dependence in male mating preference for female morphs in the damselfly Ischnura senegalensis (Rambur) (Odonata: Coenagrionidae)

Ischnura senegalensis females exhibit color dimorphism, consisting of an andromorph and a gynomorph, which might be maintained under a frequency-dependent process of mating harassment by mate-searching males. Males change their mating preference for female morph depending on prior copulation experience. Binary choice experiments between two female morphs were carried out in four local populations in the early morning (07.00–09.00 hours) and the afternoon (12.00–14.00 hours), times which mark the onset and the end of diurnal mating activity, respectively. According to the line census along the water's edge, the proportion of andromorphs in the female population varied from 21 to 67% throughout the survey period for four local populations. Males showed non-biased preference for female morphs in the early morning in each local population, while they chose the common morph in the afternoon. Male mating preference for female morphs was positively correlated to the proportion of female morphs in the population. If the selective mating attacks on the common female morphs inhibit their foraging and/or oviposition behavior, frequency-dependent male mating attacks might provide a selective force for maintaining the female color dimorphism in I. senegalensis .     

The relative importance of substrate conditions as microhabitat determinants of a riverine benthic goby, Rhinogobius sp. OR (orange form) in runs

We examined the microhabitat determinants of the benthic goby Rhinogobius sp. OR (orange form) in runs by measuring fish density, and substrate and hydraulic variables at four sites in the middle and lower reaches of the Ado River, Japan. One of the four sites was located below a bridge pier in the lower reach and had coarser substrate than was typical there. This contributed to the elimination of the correlation between substrate condition and hydraulic variables by providing anomalous combinations of substrate and hydraulic variables. Using principal component analysis, the variables were divided into substrate and hydraulic components. A multiple regression analysis revealed that substrate variables explained more of the variance in fish density than hydraulic variables. We concluded that the density of this goby is determined by substrate conditions in runs, where the current velocity is lower and the stone shelter is scarcer than in riffles. The importance of substrate conditions, which can be easily masked by current velocity in natural settings, should not be neglected.