Djhsp60 Is Required for Planarian Regeneration and Homeostasis.

HSP60, a well-known mitochondrial chaperone, is essential for mitochondrial homeostasis. HSP60 deficiency causes dysfunction of the mitochondria and is lethal to animal survival. Here, we used freshwater planarian as a model system to investigate and uncover the roles of HSP60 in tissue regeneration and homeostasis. HSP60 protein is present in all types of cells in planarians, but it is relatively rich in stem cells and head neural cells. Knockdown of HSP60 by RNAi causes head regression and the loss of regenerating abilities, which is related to decrease in mitotic cells and inhibition of stem cell-related genes. RNAi-HSP60 disrupts the structure of the mitochondria and inhibits the mitochondrial-related genes, which mainly occur in intestinal tissues. RNAi-HSP60 also damages the integrity of intestinal tissues and downregulates intestine-expressed genes. More interestingly, RNAi-HSP60 upregulates the expression of the cathepsin L-like gene, which may be the reason for head regression and necrotic-like cell death. Taking these points together, we propose a model illustrating the relationship between neoblasts and intestinal cells, and also highlight the essential role of the intestinal system in planarian regeneration and tissue homeostasis.

[Functional analysis of autophagy-related gene Atg6 in planarian central nervous system regeneration].

Autophagy-related gene 6 (Atg6) plays an essential role in autophagy, and loss of its function impairs neurogenesis. Planarian is a good model for the study of the central nervous system (CNS) regeneration. It can regenerate a new head de novo in 1 week following decapitation. Therefore, functional analysis of Atg6 in planarian CNS regeneration is very important for understanding of autophagy in the regulation of neurogenesis. In this work, we reported the molecular characteristics of Atg6 in Dugesia japonica (DjAtg6) for the first time and examined its function by RNAi. The full-length cDNA of DjAtg6 is 1366 bp encoding 423 amino acids. The deduced amino sequence of DjAtg6 contains the coil-coil domain and ß-α-repeated autophagy-specific domain shared by ATG6/Beclin 1 family. Following amputation before and after the pharynx, DjAtg6 transcripts increased and were mainly distributed in the newly regenerated brain structure. RNAi-DjAtg6 delayed planarian head regeneration with a small size of brain, and decreased the expression levels of neural-related genes. In addition, our results revealed that RNAi-DjAtg6 did not affect the stem cell proliferation, but down-regulated the cell migration-related genes mmp1 and mmp2. Furthermore, RNAi-mmp1 and RNAi-mmp2 delayed planarian head regeneration. Therefore, our results suggest that DjAtg6 is important for planarian CNS regeneration. The abnormal CNS regeneration caused by RNAi-DjAtg6 may be related to cell migration, but the detailed mechanism needs to be further investigated.

Effects of inorganic electrolyte anions on enrichment of Cu(II) ions with aminated Fe3O4/graphene oxide: Cu(II) speciation prediction and surface charge measurement.

The present work evaluated the effects of six inorganic electrolyte anions on Cu(II) removal using aminated Fe3O4/graphene oxide (AMGO) in single- and multi-ion systems. A 2(6-2) fractional factorial design (FFD) was employed for assessing the effects of multiple anions on the adsorption process. The results indicated that the Cu(II) adsorption was strongly dependent on pH and could be significantly affected by inorganic electrolyte anions due to the changes in Cu(II) speciation and surface charge of AMGO. In the single-ion systems, the presence of monovalent anions (Cl(-), ClO4(-), and NO3(-)) slightly increased the Cu(II) adsorption onto AMGO at low pH, while the Cu(II) adsorption was largely enhanced by the presence of SO4(2-), CO3(2-), and HPO4(2-). Based on the estimates of major effects and interactions from FFD, the factorial effects of the six selected species on Cu(II) adsorption in multi-ion system were in the following sequence: HPO4(2-)>CO3(2-)>Cl(-)>SO4(2-)>NO3(-)=ClO4(-), and the combined factors of AD (Cl(-)×SO4(2-)) and EF (Cl(-)×SO4(2-)) had significant effects on Cu(II) removal.

Effects of background electrolytes and ionic strength on enrichment of Cd(II) ions with magnetic graphene oxide-supported sulfanilic acid.

To elucidate the influence mechanisms of background electrolytes and ionic strength on Cd(II) removal, the adsorption of Cd(II) onto magnetic graphene oxide-supported sulfanilic acid (MGO-SA) in aqueous solutions containing different types and concentrations of background electrolytes was studied. The results indicate that Cd(II) adsorption was strongly dependent on pH and could be strongly affected by background electrolytes and ionic strength. The Cd(II) removal was decreased with the presence of background electrolyte cations (Na(+), K(+), Ca(2+), Mg(2+), Mn(2+), Zn(2+), and Ni(2+)), and the divalent cations exerted more obvious influences on the Cd(II) uptake than the monovalent cations at pH 6. Both Cl(-) and NO3(-) had negative effects on Cd(II) adsorption because they can form water-soluble metal-anion complexes with Cd(II) ions. The presence of 0.01molL(-1) Na3PO4 reduced the removal percentage of Cd(II) at pH<5 but extremely enhanced the Cd(II) removal when the pH>5. The Cd(II) adsorption was sensitive to changes in the concentration of NaCl, NaNO3, NaClO4, and Na3PO4. Besides, the adsorption isotherm of Cd(II) onto MGO-SA could be well described by the Freundlich model and was also influenced by the type of background electrolyte ions and the ionic strength.