A mutant strain of Chymomyza costata (Diptera: Drosophilidae) insensitive to diapause-inducing action of photoperiod

ABSTRACT. From a Japanese population of Chymomyza costata which has been known to have a photoperiodic larval diapause, we selected a mutant strain which did not respond to photoperiod. However, about 70% of the individuals of this strain entered diapause at 11^oC irrespective of photoperiod, and about the same percentage of those of the photoperiod-sensitive strain also did so in continuous illumination at 11^oC. This indicates that low temperature induces diapause independently of photoperiod. On the other hand, a temperature drop from 18 or 25^oC to 15^oC and chilling at 4^oC did not induce diapause.     

Investigation of the efficacy of paclitaxel on some miRNAs profiles in breast cancer stem cells

Understanding of the functions of microRNAs in breast cancer and breast cancer stem cells have been a hope for the development of new molecular targeted therapies. Here, it is aimed to investigate the differences in the expression levels of let-7a, miR-10b, miR-21, miR-125b, miR-145, miR-155, miR-200c, miR-221, miR-222 and miR-335, which associated with gene and proteins in MCF-7 (parental) and MCF-7s (Mammosphere/stem cell-enriched population/CD44+/CD24-cells) cells treated with paclitaxel. MCF-7s were obtained from parental MCF-7 cells. Cytotoxic activity of paclitaxel was determined by ATP assay. Total RNA isolation and cDNA conversion were performed from the samples. Changes in expression levels of miRNAs were examined by RT-qPCR. Identified target genes and proteins of miRNAs were analyzed with RT-qPCR and western blot analysis, respectively. miR-125b was significantly expressed (2.0946-fold; p = 0.021) in MCF-7s cells compared to control after treatment with paclitaxel. Downregulation of SMO, STAT3, NANOG, OCT4, SOX2, ERBB2 and ERBB3 and upregulation of TP53 genes were significant after 48 h treatment in MCF-7s cells. Protein expressions of SOX2, OCT4, SMAD4, SOX2 and OCT4 also decreased. Paclitaxel induces miR-125b expression in MCF-7s cells. Upregulation of miR-125b may be used as a biomarker for the prediction of response to paclitaxel treatment in breast cancer.     

Distinguishing bacterial pathogens of potato using a genome-wide microarray approach

A set of 9676 probes was designed for the most harmful bacterial pathogens of potato and tested in a microarray format. Gene‐specific probes could be designed for all genes of Pectobacterium atrosepticum, c. 50% of the genes of Streptomyces scabies and c. 30% of the genes of Clavibacter michiganensis ssp. sepedonicus utilizing the whole‐genome sequence information available. For Streptomyces turgidiscabies, 226 probes were designed according to the sequences of a pathogenicity island containing important virulence genes. In addition, probes were designed for the virulence‐associated nip (necrosis‐inducing protein) genes of P. atrosepticum, P. carotovorum and Dickeya dadantii and for the intergenic spacer (IGS) sequences of the 16S–23S rRNA gene region. Ralstonia solanacearum was not included in the study, because it is a quarantine organism and is not presently found in Finland, but a few probes were also designed for this species. The probes contained on average 40 target‐specific nucleotides and were synthesized on the array in situ, organized as eight sub‐arrays with an identical set of probes which could be used for hybridization with different samples. All bacteria were readily distinguished using a single channel system for signal detection. Nearly all of the c. 1000 probes designed for C. michiganensis ssp. sepedonicus, c. 50% and 40% of the c. 4000 probes designed for the genes of S. scabies and P. atrosepticum, respectively, and over 100 probes for S. turgidiscabies showed significant signals only with the respective species. P. atrosepticum, P. carotovorum and Dickeya strains were all detected with 110 common probes. By contrast, the strains of these species were found to differ in their signal profiles. Probes targeting the IGS region and nip genes could be used to place strains of Dickeya to two groups, which correlated with differences in virulence. Taken together, the approach of using a custom‐designed, genome‐wide microarray provided a robust means for distinguishing the bacterial pathogens of potato.     

Analyses of the secretomes of Erwinia amylovora and selected hrp mutants reveal novel type III secreted proteins and an effect of HrpJ on extracellular harpin levels

Erwinia amylovora is a plant pathogenic enterobacterium that causes fire blight disease of apple, pear and other rosaceous plants. A type III (T3) secretion system, encoded by clustered, chromosomal hrp genes (hypersensitive response and pathogenicity), is essential for infection, but only a few proteins are known that are secreted through this pathway (the T3 'secretome'). We developed an efficient protocol for purification and concentration of extracellular proteins and used it to characterize the T3 secretome of E. amylovora Ea273 by comparing preparations from the wild-type strain with those from mutants defective in hrp secretion, regulation, or in genes encoding putative T3-secreted proteins. Proteins were resolved by gel electrophoresis and identified using mass spectrometry and a draft sequence of the E. amylovora genome. Twelve T3-secreted proteins were identified, including homologues of known effector and helper proteins, and HrpJ, a homologue of YopN of Yersinia pestis . Several previously uncharacterized T3-secreted proteins were designated as Eops for Erwinia outer proteins. Analysis of the secretome of a non-polar hrpJ mutant demonstrated that HrpJ is required for accumulation of wild-type levels of secreted harpins. HrpJ was found to be essential for pathogenesis, and to play a major role in elicitation of the hypersensitive reaction in tobacco.     

Common anastomosis and internal transcribed spacer RFLP groupings in binucleate Rhizoctonia isolates representing root endophytes of Pinus sylvestris, Ceratorhiza spp. from orchid mycorrhizas and a phytopathogenic anastomosis group

Binucleate Rhizoctonia endophytes from the roots of nursery-grown Pinus sylvestris (Scots pine) seedlings and the orchid Goodyera repens from Scots pine forests were characterized on the basis of morphological characters, anastomosis group membership and PCR-assisted ribosomal DNA fingerprinting. Common hyphal and colony morphological traits displayed by the Finnish binucleate Rhizoctonia isolates and a range of Canadian orchid root endophytes enabled them to be placed in the anamorphic genus Ceratorhiza . Five main anastomosis groups were identified and included groups that contained different combinations of Scots pine, G. repens and Canadian Ceratorhiza spp. isolates. Two Scots pine root endophytes anastomosed with a phytopathogenic Japanese tester isolate, confirming their membership of anastomosis group I, which is known to include the teleomorphic species Ceratobasidium cornigerum . Hierarchical cluster analysis of RFLPs in the internal transcribed spacer of ribosomal DNA enabled the division of isolates into one of five RFLP groups. The RFLP and anastomosis groupings were closely correlated; isolates within each of four RFLP groups, which shared 100% RFLP identity, anastomosed in the cross-pairing anastomosis group tests. However, all represented different vegetatively compatible populations (clones) because the diagnostic killing reaction, a cellular vegetative incompatibility response, was identified at hyphal fusion junctions. These findings indicate a high degree of intraspecific variation within Ceratobasidium cornigerum , which includes isolates able to enter into either mutualistic or pathogenic root association with susceptible host plants. The common anastomosis group/RFLP groupings identified also strongly support the hypothesis that conifer tree roots can act as large inoculum reservoirs for these orchid endophytes, allowing the development of inter-plant connections, via commonly shared hyphal linkages, in boreal forest ecosystems.     

Modulation of respiratory metabolism in response to nutrient changes along a soil chronosequence

Laboratory studies indicate that plant respiratory efficiency may decrease in response to low nutrient availability due to increased partitioning of electrons to the energy‐wasteful alternative oxidase (AOX); however, field confirmation of this hypothesis is lacking. We therefore investigated plant respiratory changes associated with succession and retrogression in soils aged from 10 to 120 000 years along the Franz Josef soil chronosequence, New Zealand. Respiration rates and electron partitioning were determined based on oxygen isotopic fractionation. Leaf structural traits, foliar nutrient status, carbohydrates and species composition were measured as explanatory variables. Although soil nutrient levels and species composition varied by site along the chronosequence, foliar respiration across all sites and species corresponded strongly with leaf nitrogen concentration (r² = 0.8). In contrast, electron partitioning declined with increasing nitrogen/phosphorus (r² = 0.23) and AOX activity correlated with phosphorus (r² = 0.64). Independently, total respiration was further associated with foliar Cu, possibly linked to its effect on AOX. Independent control of AOX and cytochrome pathway activities is also discussed. These responses of plant terminal respiratory oxidases – and therefore respiratory carbon efficiency – to multiple nutrient deficiencies demonstrate that modulation of respiratory metabolism may play an important role in plant responses to nutrient gradients.     

‘Random‐flight’ dispersal in tropical fruit‐feeding butterflies? High mobility,long lifespans and no home ranges

1. Tropical fruit‐feeding Nymphalidae butterflies are widely used in research, monitoring, and conservation projects, but to date a key aspect of their behaviour – dispersal – remains poorly understood. They have anecdotally been described as ‘relatively sedentary’ based on movement vectors from mark‐recapture studies, but this may be inaccurate because plot‐based studies in small sampling areas often underrepresent long‐distance movements. 2. Based on data from a peat‐swamp forest in Borneo, it was found that these butterflies may be much more mobile than previously thought, as they frequently moved distances of 1–2 km between sampling plots. Median daily movements were approximately 200–250 m, and over lifespans of one or more months these movements may sum to total life‐time dispersals of several kilometres. 3. Recapture rates for long‐distance movements between sampling plots were between 28.2% and 41.6% of the re‐encounter rates that would be predicted by a random‐walk approximation/Brownian motion (without accounting for survival rates), supporting the hypothesis that it is a suitable model of dispersal in this group, although further research is needed to confirm this. 4. There was no evidence that butterflies occupied permanent home ranges, and it is suggested that a permanent home range or territorial behaviour would be maladaptive in this group. Pseudo‐replication caused by ‘trap‐happy’ behaviour was not found to be widespread, and some recommendations are provided regarding the treatment of recapture data in trap‐based studies. 5. These findings substantially increase the spatial parameters for future research and conservation projects in this group and are also applicable to theoretical modelling studies. An abstract for this article in Bahasa Indonesia is included in the online supporting information File S1.     

Interactions of elevated carbon dioxide and temperature with aphid feeding on transgenic oilseed rape: Are Bacillus thuringiensis (Bt) plants more susceptible to nontarget herbivores in future climate?

Climate change factors such as elevated carbon dioxide (CO₂) and temperature typically affect carbon (C) and nitrogen (N) dynamics of crop plants and the performance of insect herbivores. Insect‐resistant transgenic plants invest some nutrients to the production of specific toxic proteins [i.e. endotoxins from Bacillus thuringiensis (Bt)], which could alter the C–N balance of these plants, especially under changed abiotic conditions. Aphids are nonsusceptible to Lepidoptera‐targeted Bt Cry1Ac toxin and they typically show response to abiotic conditions, and here we sought to discover whether they might perform differently on compositionally changed Bt oilseed rape. Bt oilseed rape had increased N content in the leaves coupled with reduced total C compared with its nontransgenic counterpart, but in general the C : N responses of both plant types to elevated CO₂ and temperature were similar. Elevated CO₂ decreased N content and increased C : N ratio of both plant types. Elevated temperature increased C and N contents, total chlorophyll and carotenoid concentrations under ambient CO₂, but decreased these under elevated CO₂. In addition, soluble sugars were increased and starch decreased by elevated temperature under ambient but not under elevated CO₂, whereas photosynthesis was decreased in plants grown under elevated temperature in both CO₂ levels. Myzus persicae, a generalist aphid species, responded directly to elevated temperature with reduced developmental time and decreased adult and progeny weights, whereas the development of the Brassica specialist Brevicoryne brassicae was less affected. Feeding by M. persicae resulted in an increase in the N content of oilseed rape leaves under ambient CO₂, indicating the potential of herbivore feeding itself to cause allocation changes. The aphids performed equally well on both plant types despite the differences between C–N ratios of Bt and non‐Bt oilseed rape, revealing the absence of plant composition‐related effects on these pests under elevated CO₂, elevated temperature or combined elevated CO₂ and temperature conditions.