Static pressure is an alternative method to chemical pressure for tuning the crystal structure, bonds, and physical properties of materials, and is a significant technique for the synthesis of novel materials and fundamental research. In this letter, we report the crystallization and phase transformation of p-xylene under high pressure. Our optical micrographic observations and the appearance of lattice modes in the Raman and infrared (IR) spectra indicated that p-xylene crystallizes at similar to 0.1 GPa. The X-ray diffraction (XRD) pattern at 0.84 GPa suggests that the crystallized p-xylene had a monoclinic phase with the Cc(9) space group. The sharp shrinkage of the lattice at similar to 13 GPa and the solid state of the decompressed sample we observed suggests a new crystalline phase of p-xylene. The in situ XRD showed that the new crystalline phase was still a monoclinic structure but with a different space group of C2(5), indicating that a phase transition occurred during further compression. The mass spectrometry experiment confirmed phase transition polymerization, with mainly trimer and tetramer polymers. Our findings suggest an easy and efficient method for crystallizing and polymerizing p-xylene under high pressure.

Zebrafish Liver-enriched gene 1a (Leg1a) and Leg1b are liver-produced serum proteins encoded by two adjacently linked homologous genes leg1a and leg1b, respectively. We previously showed that maternal-zygotic (MZ) leg1a null mutant developed a small liver at 3.5 days post-fertilization (dpf) during winter-time or under UV-treatment and displayed an abnormal stature at its adulthood. It is puzzling why Leg1b, which shares 89.3% identity with Leg1a and co-expressed with Leg1a, cannot fully compensate for the loss-of-function of Leg1a in the leg1a(zju1) MZ mutant. Here we report that Leg1a and Leg1b share eight cysteine residues but differ in amino acid residue 358, which is a serine in Leg1a but cysteine (C-358) in Leg1b. We find that Leg1b forms an intermolecular disulfide bond through C-358. Mutating C-358 to Methionine (M-358) does not affect Leg1b secretion whereas mutating other conserved cysteine residues do. We propose that the intermolecular disulfide bond in Leg1b might establish a rigid structure that makes it functionally different from Leg1a under certain oxidative conditions. (c) 2021 Published by Elsevier Inc.

Platyhelminthes are excellent models for the study of stem cell biology, regeneration and the regulation of scale and proportion. In addition, parasitic forms infect millions of people worldwide. Therefore, it is puzzling that they remain relatively unexplored at the molecular level. We present the characterization of similar to3000 non-redundant cDNAs from a clonal line of the planarian Schmidtea mediterranea. The obtained cDNA sequences, homology comparisons and high-throughput whole-mount in situ hybridization data form part of the S. mediterranea database (SmedDb; http://planaria.neuro.utah.edu). Sixty-nine percent of the cDNAs analyzed share similarities with sequences deposited in GenBank and dbEST. The remaining gene transcripts failed to match sequences in other organisms, even though a large number of these (similar to80%) contained putative open reading frames. Taken together, the molecular resources presented in this study, along with the ability of abrogating gene expression in planarians using RNA interference technology, pave the way for a systematic study of the remarkable biological properties displayed by Platyhelminthes.