Localization of P elements, copy number regulation, and cytotype determination in Drosophila melanogaster

Seventeen highly-inbred lines of Drosophila melanogaster extracted from an M' strain (in the P/M system of hybrid dysgenesis) were studied for their cytotype and the number and chromosomal location of complete and defective P elements. While most lines were of M cytotype, three presented a P cytotype (the condition that represses P-element activity) and one was intermediate between M and P. All lines were found to possess KP elements and only eight to bear full-sized P elements. Only the lines with full-sized P elements showed detectable changes in their P-insertion pattern over generations; their rates of gain and of loss of P-element sites were equal to 0.12 and 0.09 per genome, per generation, respectively. There was no correlation between these two rates within lines, suggesting independent transpositions and excisions in the inbred genomes. The results of both Southern blot analysis and in situ hybridization of probes made from left and right sides of the P element strongly suggested the presence of a putative complete P element in region 1A of the X chromosome in the three lines with a P cytotype; the absence of P copy in this 1A region in lines with an M cytotype, favours the hypothesis that the P element inserted in 1A could play a major role in the P-cytotype determination. Insertion of a defective 2 kb P element was also observed in region 93F in 9 of the 13 M lines. The regulation of the P-element copy number in our lines appeared not to be associated with the ratio of full-length and defective P elements.     

Interaction between the min locus and ftsZ.

In Escherichia coli, distinct but similar minicell phenotypes resulting from mutation at the minB locus and increased expression of ftsZ suggested a possible interaction between these genes. A four- to fivefold increase in FtsZ resulting from increased gene dosage was found to suppress the lethality of minCD expressed from the lac promoter. Since increased MinCD did not affect the level of FtsZ, this suggested that MinCD may antagonize FtsZ to inhibit its cell division activity. This possibility was supported by the finding that alleles of ftsZ isolated as resistant to the cell division inhibitor SulA were also resistant to MinCD. Among the ftsZ(Rsa) alleles, two appeared to be completely resistant to MinCD as demonstrated by the lack of an effect of MinCD on cell length and a minicell phenotype observed in the absence of a significant increase in FtsZ. It was shown that SulA inhibits cell division independently of MinCD.     

Outgrowth promoting factor for the inner cell mass of the mouse blastocyst

When cultured individually, isolated inner cell masses (ICMs) of the mouse blastocyst form an outer layer of endoderm and remain in suspension as spherical structures for several days. Conditioned media from certain teratocarcinoma- and blastocyst-derived cell lines contain one or more outgrowth promoting factors (OPF) which facilitate attachment and outgrowth of ICMs, in some cases prior to endoderm formation. OPF adheres to culture dishes and presumably promotes ICM cell outgrowth by alteration of the substratum. Analyses indicate that the active material is a nondialyzable protein which is stable to freezing and thawing, a wide range of pH, and extended incubation at 37°C. However, inactivation takes place at 60°C for 20 min. Although these properties of OPF are in some ways similar to those of various proteins which have been implicated in cell adhesion and spreading, differences between OPF and most of these other proteins are evident. The detection of OPF activity in conditioned medium from primary cultures of embryonic and some extraembryonic cell types suggests that the factor is biologically significant, perhaps, for example, in the spreading of parietal endoderm cells along the surface of the trophoblast layer.     

Environmental footprints of British Columbia wood pellets from a simplified life cycle analysis

Purpose  

Environmental footprints of wood pellets produced in British Columbia (BC) of Canada are to be estimated based on industry surveys and published emission factor data.     

Isoliquiritigenin ameliorates caerulein‐induced chronic pancreatitis by inhibiting the activation of PSCs and pancreatic infiltration of macrophages

Chronic pancreatitis (CP) is characterized by persistent inflammation of the pancreas that results in progressive loss of the endocrine and exocrine compartment owing to atrophy and/or replacement with fibrotic tissue. Currently, the clinical therapeutic scheme of CP is mainly symptomatic treatment including pancreatic enzyme replacement, glycaemic control and nutritional support therapy, lacking of specific therapeutic drugs for prevention and suppression of inflammation and fibrosis aggravating in CP. Here, we investigated the effect of isoliquiritigenin (ILG), a chalcone‐type dietary compound derived from licorice, on pancreatic fibrosis and inflammation in a model of caerulein‐induced murine CP, and the results indicated that ILG notably alleviated pancreatic fibrosis and infiltration of macrophages. Further in vitro studies in human pancreatic stellate cells (hPSCs) showed that ILG exerted significant inhibition on the proliferation and activation of hPSCs, which may be due to negative regulation of the ERK1/2 and JNK1/2 activities. Moreover, ILG significantly restrained the M1 polarization of macrophages (RAW 264.7) via attenuation of the NF‐κB signalling pathway, whereas the M2 polarization was hardly affected. These findings indicated that ILG might be a potential anti‐inflammatory and anti‐fibrotic therapeutic agent for CP.     

Achieving Balanced Crystallization Kinetics of Donor and Acceptor by Sequential‐Blade Coated Double Bulk Heterojunction Organic Solar Cells

Sequential deposition has great potential to achieve high performance in organic solar cells due to the resulting well‐controlled vertical phase separation. In this work, double bulk heterojunction organic solar cells are fabricated by sequential‐blade cast in ambient conditions. Probed by the in situ grazing incidence X‐ray diffraction and in situ UV–vis absorption measurements, the seq‐blade system exhibits a different tendency from each of the binary films during the film formation process. Due to the extensive aggregation of FOIC, the binary PBDB‐T:FOIC film displays a strong and large phase separation, resulting in low current density (J_sc) and unsatisfactory power conversion efficiency. In the seq‐blade cast system, the bottom layer PBDB‐T:IT‐M produces many crystal nuclei for the top layer PBDB‐T:FOIC, so the PBDB‐T molecules are able to crystallize easily and quickly. Balanced crystallization kinetics between polymer and small molecule and an ideal percolation network in the film are observed. In addition, the balanced crystallization kinetics are favorable toward realizing lower recombination loss through charge transport processes.     

Aging shifts mitochondrial dynamics toward fission to promote germline stem cell loss

Changes in mitochondrial dynamics (fusion and fission) are known to occur during stem cell differentiation; however, the role of this phenomenon in tissue aging remains unclear. Here, we report that mitochondrial dynamics are shifted toward fission during aging of Drosophila ovarian germline stem cells (GSCs), and this shift contributes to aging‐related GSC loss. We found that as GSCs age, mitochondrial fragmentation and expression of the mitochondrial fission regulator, Dynamin‐related protein (Drp1), are both increased, while mitochondrial membrane potential is reduced. Moreover, preventing mitochondrial fusion in GSCs results in highly fragmented depolarized mitochondria, decreased BMP stemness signaling, impaired fatty acid metabolism, and GSC loss. Conversely, forcing mitochondrial elongation promotes GSC attachment to the niche. Importantly, maintenance of aging GSCs can be enhanced by suppressing Drp1 expression to prevent mitochondrial fission or treating with rapamycin, which is known to promote autophagy via TOR inhibition. Overall, our results show that mitochondrial dynamics are altered during physiological aging, affecting stem cell homeostasis via coordinated changes in stemness signaling, niche contact, and cellular metabolism. Such effects may also be highly relevant to other stem cell types and aging‐induced tissue degeneration.     

Flexible chromosome painting based on multiplex PCR of oligonucleotides and its application for comparative chromosome analyses in Cucumis

Chromosome painting is a powerful technique for chromosome and genome studies. We developed a flexible chromosome painting technique based on multiplex PCR of a synthetic oligonucleotide (oligo) library in cucumber (Cucumis sativus L., 2n = 14). Each oligo in the library was associated with a universal as well as nested specific primers for amplification, which allow the generation of different probes from the same oligo library. We were also able to generate double‐stranded labelled oligos, which produced much stronger signals than single‐stranded labelled oligos, by amplification using fluorophore‐conjugated primer pairs. Oligos covering cucumber chromosome 1 (Chr1) and chromosome 4 (Chr4) consisting of eight segments were synthesized in one library. Different oligo probes generated from the library painted the corresponding chromosomes/segments unambiguously, especially on pachytene chromosomes. This technique was then applied to study the homoeologous relationships among cucumber, C. hystrix and C. melo chromosomes based on cross‐species chromosome painting using Chr4 probes. We demonstrated that the probe was feasible to detect interspecies chromosome homoeologous relationships and chromosomal rearrangement events. Based on its advantages and great convenience, we anticipate that this flexible oligo‐painting technique has great potential for the studies of the structure, organization, and evolution of chromosomes in any species with a sequenced genome.