MicroRNA 224 Regulates Ion Transporter Expression in Ameloblasts To Coordinate Enamel Mineralization

Enamel mineralization is accompanied by the release of protons into the extracellular matrix, which is buffered to regulate the pH value in the local microenvironment. The present study aimed to investigate the role of microRNA 224 (miR-224) as a regulator of SLC4A4 and CFTR, encoding the key buffering ion transporters, in modulating enamel mineralization. miR-224 was significantly downregulated as ameloblasts differentiated, in parallel with upregulation of SLC4A4 and CFTR. Overexpression of miR-224 downregulated SLC4A4 and CFTR expression in cultured human epithelial cells. A microRNA luciferase assay confirmed the specific binding of miR-224 to the 3′ untranslated regions (UTRs) of SLC4A4 and CFTR mRNAs, thereby inhibiting protein translation. miR-224 agomir injection in mouse neonatal incisors resulted in normal enamel length and thickness, but with disturbed organization of the prism structure and deficient crystal growth. Moreover, the enamel Ca/P ratio and microhardness were markedly reduced after miR-224 agomir administration. These results demonstrate that miR-224 plays a pivotal role in fine tuning enamel mineralization by modulating SLC4A4 and CFTR to maintain pH homeostasis and support enamel mineralization.     

QTLs associated with chlorimuron ethyl sensitivity in soybean: Effects on seed yield and related traits

 Soybean, Glycine max (L.) Merr., genotypes are known to differ in chlorimuron ethyl sensitivity (CS). Earlier we have reported two putatively independent marker loci linked to two quantitative trait loci (QTLs) controlling CS in a soybean population derived from a cross of PI97100 (sensitive to chlorimuron ethyl) and ‘Coker 237’ (tolerant to chlorimuron ethyl). The objective of the present study was to quantify the association of the two marker loci with seed yield and related traits in this soybean population following application of chlorimuron ethyl. Phenotypic data were collected for 111 F₂-derived lines of the cross grown in replicated plots at Athens, G.A., in 1994 and 1995, and at Blackville, S.C., in 1995. The two CS marker loci explained as much as 50% of the genetic variation in seed yield and seed number m^-2, but had no association with seed weight, plant height, lodging, seed protein, and seed oil. There were no epistatic interactions between the two marker loci for any of the traits. The marker locus (cr168-1 on USDA linkage group E) linked to the major CS QTL explained between 13 and 23% of the variation in seed yield. The Coker 237 allele at this locus was associated with decreased CS and increased seed yield. The marker locus (Blt015-2 on an unknown linkage group) linked to the minor CS QTL accounted for a maximum of 11% of the variation in seed yield. The Coker 237 allele at this locus was associated with an increase in CS and a decrease in seed yield. The association of the two marker loci with seed number m^-2 strongly resembled their association with seed yield. Seed yield had a strong positive correlation (r=0.74 – 0.94) with seed number m^-2, and the effect of chlorimuron ethyl on seed yield was due mainly to its effect on seed number m^-2 rather than seed weight. Received: 6 August 1996 / Accepted: 28 February 1997     

肝癌细胞与胶原蛋白Ⅰ裱衬表面粘附特性

本文以正常胎肝细胞的原代培养及肝癌细胞的传代培养为基础,应用微管吸吮技术在单个细胞水平上研究肝实质细胞癌细胞在胶原蛋白Ⅰ裱衬表面的粘附力学特性。实验将正常原代肝细胞与肝癌细胞进行对照,阐明肝癌细胞与胶原蛋白Ⅰ裱衬表面粘附行为的时间与浓度依赖性,结果表明肝癌细胞与胶原蛋白Ⅰ裱衬表面具有更强的粘附力。这一研究对肝癌转移的定量研究有方法学的参考意义。     

Imaging of Scleral Collagen Deformation Using Combined Confocal Raman Microspectroscopy and Polarized Light Microscopy Techniques

This work presents an optospectroscopic characterization technique for soft tissue microstructure using site-matched confocal Raman microspectroscopy and polarized light microscopy. Using the technique, the microstructure of soft tissue samples is directly observed by polarized light microscopy during loading while spatially correlated spectroscopic information is extracted from the same plane, verifying the orientation and arrangement of the collagen fibers. Results show the response and orientation of the collagen fiber arrangement in its native state as well as during tensile and compressive loadings in a porcine sclera model. An example is also given showing how the data can be used with a finite element program to estimate the strain in individual collagen fibers. The measurements demonstrate features that indicate microstructural reorganization and damage of the sclera’s collagen fiber arrangement under loading. The site-matched confocal Raman microspectroscopic characterization of the tissue provides a qualitative measure to relate the change in fibrillar arrangement with possible chemical damage to the collagen microstructure. Tests and analyses presented here can potentially be used to determine the stress-strain behavior, and fiber reorganization of the collagen microstructure in soft tissue during viscoelastic response.     

Growth and physiology of a yeast cultivated in batch and continuous culture systems

Inoculum size has been found to affect significantly the maximum attainable specific growth rate during batch cultivation ofCandida utilis. Lower inoculum size resulted in an increased growth rate and relatively longer lag. The culture is found to be most active in the beginning of the exponential phase as regards its RNA synthesis rate. Batch data were used for predicting the conditions of the yeast population in single-stage continuous culture system. Predicted and the experimental values showed a reasonable agreement. In single-stage chemostat the physiology of the yeast was studied on the basis RNA, DNA and protein synthesis rates at various growth rates. The results indicate that the productivity of cells and the rate of synthesis of macromolecules is highest at the dilution rate values of 0.33 to 0.35 hr⁻¹. In order to attain so-called unrestricted conditions of growth a pluristage pluristream continuous system was employed. It is assumed that under such conditions the specific growth rate and the synthetic activity of yeasts may reach its maximum on a given medium. The results presented do not show such conditions of growth under the experimental conditions employed (D ₁=0.35 hr⁻¹ andD ₂=0.2 to 1.7 hr⁻¹) withCandida utilis cultivated on beet molasses medium. Second stage of a two-stage two-stream continuous system is constantly fed with the cells from the foregoing stage; this category of cells on entering the new conditions of the second stage is expected to show some adaptation period. Experiments are reported to this effect.