LAP2ß transmits force to upregulate genes via chromatin domain stretching but not compression.

There is increasing evidence that force impacts almost every aspect of cells and tissues in physiology and disease including gene regulation. However, the molecular pathway of force transmission from the nuclear lamina to the chromatin remain largely elusive. Here we employ two different approaches of a local stress on cell apical surface via an RGD (Arg-Gly-Asp)-coated magnetic bead and whole cell deformation at cell basal surface via uniaxial or biaxial deformation of a fibronectin-coated flexible polydimethylsiloxane substrate. We find that nuclear protein LAP2ß mediates force transmission from the nuclear lamina to the chromatin. Knocking down LAP2ß increases spontaneous movements of the chromatin by reducing tethering of the chromatin and substantially inhibits the magnetic bead-stress or the substrate-deformation induced chromatin domain stretching and the ensuing dihydrofolate reductase (DHFR) gene upregulation. Analysis of DHFR gene-containing chromatin domain alignments along or perpendicular to the direction of the stretching/compressing reveals that the chromatin domain must be stretched and not compressed in order for the gene to be rapidly upregulated. Together these results suggest that external-load induced rapid transcription upregulation originates from chromatin domain stretching but not compressing and depends on the molecular force transmission pathway of LAP2ß. STATEMENT OF SIGNIFICANCE: How force regulates gene expression has been elusive. Here we show that the orientation of the chromatin domain relative to the stress direction is crucial in determining if the chromatin domain will be stretched or compressed in response to a cell surface loading. We also show that nuclear protein Lap2b is a critical molecule that mediates force transmission from the nuclear laminar to the chromatin to regulate gene transcription. This study reveals the molecular force transmission pathway for force-induced gene regulation.

Fatty acyl-CoA reductase influences wax biosynthesis in the cotton mealybug, Phenacoccus solenopsis Tinsley.

Mealybugs are highly aggressive to a diversity of plants. The waxy layer covering the outermost part of the integument is an important protective defense of these pests. However, the molecular mechanisms underlying wax biosynthesis in mealybugs remain largely unknown. Here, we analyzed multi-omics data on wax biosynthesis by the cotton mealybug, Phenacoccus solenopsis Tinsley, and found that a fatty acyl-CoA reductase (PsFAR) gene, which was highly expressed in the fat bodies of female mealybugs, contributed to wax biosynthesis by regulating the production of the dominant chemical components of wax, cuticular hydrocarbons (CHCs). RNA interference (RNAi) against PsFAR by dsRNA microinjection and allowing mealybugs to feed on transgenic tobacco expressing target dsRNA resulted in a reduction of CHC contents in the waxy layer, and an increase in mealybug mortality under desiccation and deltamethrin treatments. In conclusion, PsFAR plays crucial roles in the wax biosynthesis of mealybugs, thereby contributing to their adaptation to water loss and insecticide stress.

The Roles of DNA Methyltransferases 1 (DNMT1) in Regulating Sexual Dimorphism in the Cotton Mealybug, Phenacoccus solenopsis.

The cotton mealybug, Phenacoccus solenopsis, is an invasive pest that can cause massive damage to many host plants of agricultural importance. P. solenopsis is highly polyphagous, and shows extreme sexual dimorphism between males and females. The functions of DNA methyltransferase (DNMT) enzymes in the cotton mealybug have not been well studied. Here, we carried out an investigation of DNMTs in cotton mealybug to study their roles in sexual dimorphism. We found that the cotton mealybug has two copies of PsDnmt1, but Dnmt3 is absent. We then amplified the full-length cDNAs of PsDnmt1A (2,225 bp) and PsDnmt1B (2,862 bp) using rapid amplification cDNA ends (RACE). Quantitative reverse transcriptase PCR shows that both PsDnmt1A and PsDnmt1B are highly expressed in adult males, while the expression of PsDnmt1B is 30-fold higher in gravid females than in virgin females. We knocked down PsDnmt1A and PsDnmt1B with small interfering RNAs (siRNAs), and both genes were successfully down-regulated after 24 h or 72 h in adult females and pupa (t-test, p < 0.05). Down-regulating the expression of these two DNMT genes led to offspring lethality and abnormal body color in adult females. Furthermore, the silencing of PsDnmt1B induced abnormal wing development in emerged adult males. Our results provide evidence that PsDnmt1 plays a crucial role in regulating sexual dimorphism in the cotton mealybug.

High-Throughput Sequencing Analysis of Endophytic Bacteria Diversity in Fruits of White and Red Pitayas from Three Different Origins.

Pitaya contains various types of polyphenols, flavonoid and vitamins which are beneficial for health and it is among the most important commercial tropical fruits worldwide. Endophytic bacteria might be beneficial for plant growth and yield. However, bacterial diversity in pitaya is poorly characterized. In this study, fruits of white and red pitayas from three different origins (Thailand, Vietnam and China) were chosen for endophytic bacteria diversity investigation by using Illumina HiSeq second-generation high-throughput sequencing technology. Large number of endophytic bacteria were detected and 22 phyla, 56 classes, 81 orders, 122 families and 159 genera were identified. Endophytic bacteria diversity was uneven among pitaya fruits from different origins and bacteria structure was different between white pitaya group and red pitaya group. Phylum Bacteroidetes, classes Bacteroidia and Coriobacteriia, orders Bacteroidales and Coriobacteriales, families Prevotellaceae, Bacteroidaceae, Ruminococcaceae, Paraprevotellaceae, Rikenellaceae, Alcaligenaceae and Coriobacteriaceae, genera Prevotella, Bacteroides, Roseburia, Faecalibacterium and Sutterella were statistically significant different species (P < 0.05) between white and red pitayas. These findings might be useful for growth improvement, fruit preservation and processing of different pitaya species from different origins.

The complete genome sequence of Streptomyces autolyticus CGMCC 0516, the producer of geldanamycin, autolytimycin, reblastatin and elaiophylin.

Streptomyces autolyticus CGMCC 0516 produces the anti-tumor benzoquinone ansamycins geldanamycin, autolytimycin, and reblastatin and the 16-membered macrodiolide elaiophylin. Here, we report the complete genome sequence of S. autolyticus CGMCC 0516, which consists of a 10,029,028bp linear chromosome and seven circular plasmids. Fifty-seven putative biosynthetic gene clusters for secondary metabolites were found. The geldanamycin, autolytimycin, and reblastatin biosynthetic gene clusters were located on the left arm (2.06-2.15Mb) of the chromosome, and the elaiophylin gene cluster was located on the right arm (9.45-9.53Mb). Twenty-one putative gene clusters with high or moderate similarity to important antibiotic biosynthetic gene clusters were found, including the antitumor agents echoside, bafilomycin, hygrocin, and toxoflavin; the antibacterial/antifungal agents nigericin, skyllamycin, kanamycin, naphthomycin, eco-02301, and bottromycin A2; the immunosuppressants meridamycin and brasilicardin A; the anti-inflammatory agent cyclooctatin; and the acute iron poisoning medication desferrioxamine B. The genome sequence reported here will enable us to study the biosynthetic mechanism of these important antibiotics and will facilitate the discovery of novel secondary metabolites with potential applications to human health.

Effects of anthopleurin-Q on myocardial hypertrophy in rats and physiologic properties of isolated atria in guinea pigs.

AIM: To study effects of anthopleurin-Q (AP-Q) on myocardial hypertrophy in rats and isolated atria in guinea pigs. METHODS: Two myocardial hypertrophy models in rats were established, one introduced by levothyroxine, the other by stenosis of abdominal aorta. Cardiac myocytes morphometry and functional experiments were employed to investigate effects of AP-Q. RESULTS: Low dose of AP-Q (1 microg/kg/d, ip) reduced morphologic changes of myocardial hypertrophy in both rat models. While high dose of AP-Q (10 microg/kg/d, ip) did not, and caused mild hydropic degeneration in cardiomyocytes. High concentration of AP-Q (30 nmol/L) enhanced the contractility, raised automaticity, and prolonged the functional refractory period (FRP) in isolated left atria of guinea pigs; higher concentration (100 nmol/L) triggered arrhythmia in right atria; low concentration of AP-Q (1 nmol/L)did not affect any myocardial properties above. CONCLUSION: Low dose of AP-Q without inotropic effect can hinder the experimental myocardial hypertrophy in rats; high dose with positive inotropic effect may be responsible for its toxic reaction.