Physicochemical measurements of Japonica rice cultivars in Heilongjiang Province

We here characterized 27 japonica rice cultivars grown in Heilongjiang province and evaluated the relationship among their iodine absorption curve, physical properties, and ratio of 13 kDa prolamin. We developed the novel estimation formulae for ratio of 13 kDa prolamin and overall hardness (H2) with the use of A_λmax and λmax.     

Deficiency in the Lipid Exporter ABCA1 Impairs Retrograde Sterol Movement and Disrupts Sterol Sensing at the Endoplasmic Reticulum

Cellular cholesterol homeostasis involves sterol sensing at the endoplasmic reticulum (ER) and sterol export from the plasma membrane (PM). Sterol sensing at the ER requires efficient sterol delivery from the PM; however, the macromolecules that facilitate retrograde sterol transport at the PM have not been identified. ATP-binding cassette transporter A1 (ABCA1) mediates cholesterol and phospholipid export to apolipoprotein A-I for the assembly of high density lipoprotein (HDL). Mutations in ABCA1 cause Tangier disease, a familial HDL deficiency. Several lines of clinical and experimental evidence suggest a second function of ABCA1 in cellular cholesterol homeostasis in addition to mediating cholesterol efflux. Here, we report the unexpected finding that ABCA1 also plays a key role in facilitating retrograde sterol transport from the PM to the ER for sterol sensing. Deficiency in ABCA1 delays sterol esterification at the ER and activates the SREBP-2 cleavage pathway. The intrinsic ATPase activity in ABCA1 is required to facilitate retrograde sterol transport. ABCA1 deficiency causes alternation of PM composition and hampers a clathrin-independent endocytic activity that is required for ER sterol sensing. Our finding identifies ABCA1 as a key macromolecule facilitating bidirectional sterol movement at the PM and shows that ABCA1 controls retrograde sterol transport by modulating a certain clathrin-independent endocytic process.     

SSEA-1 marks regionally restricted immature subpopulations of embryonic retinal progenitor cells that are regulated by the Wnt signaling pathway

Identification and expansion of retinal progenitor cells are critical issues from both scientific and clinical aspects. Here, we identified SSEA-1 (CD15) as a novel surface antigen that can be used to define immature retinal progenitor cells. SSEA-1-expressing retinal cells were found in the peripheral region of the early embryonic mouse retina, and then their number dramatically disappeared along with retinal development. FACS analysis showed that the cells strongly positive for SSEA-1 co-expressed Ki67 proliferation antigen in all the developmental stages examined. The SSEA-1-expressing cells formed larger colonies than the non-expressing ones in retinal re-aggregation cultures. Moreover, late onset of rhodopsin expression was observed in SSEA-1-positive progenitor cells, supporting the idea that these cells have an intrinsically immature character. Differential expression of Wnt signal-related genes between SSEA-1-positive and -negative subpopulations of retina cells was revealed, and the expression of constitutively active forms of Wnt signaling molecules resulted in a greater number of SSEA-1-positive cells. In light of all of the data taken together, we propose SSEA-1 to be a surface marker to define a regionally restricted immature subset of progenitor cells of mouse neural retina, with SSEA-1 expression by them positively regulated by Wnt signals.     

Characterization and transfection properties of lipoplexes stabilized with novel exchangeable polyethylene glycol-lipid conjugates

The positive charge of cationic-lipid/DNA complexes (lipoplexes) renders them highly susceptible to interactions with the biological milieu, leading to aggregation and destabilization, and rapid clearance from the blood circulation. In this study we synthesized and characterized a set of novel amphiphiles, based on N-methyl-4-alkylpyridinium chlorides (SAINTs), to which a PEG moiety is coupled. Plasmids were fully protected in lipoplexes prepared from cationic SAINT-2 lipid and stabilized with SAINT-PEGs. Our results demonstrate that SAINT-PEG stabilization is transient, and permits DNA to be released from these lipoplexes. The rate of SAINT-PEG transfer from lipoplexes to acceptor liposomes was determined by the nature of the lipid anchor. Increased hydrophobicity, by lengthening the alkyl chain, resulted in a decrease of the rate of DNA release from the lipoplexes. Chain unsaturation had the opposite effect. Similarly, the in vitro transfection potency of lipoplexes containing PEG-SAINT derivatives was sensitive to the length and (un)saturation of the alkyl chain. However, the internalization of SAINT-PEG stabilized lipoplexes is determined by their charge, rather than by the concentration of the polymer conjugate. Lipoplexes targeted to cell-surface epithelial glycoprotein 2, by means of a covalently coupled monoclonal antibody, were specifically internalized by cells expressing this antigen.