Formation of cartilage by non-chondrogenic cell types

Freshly excised embryonic rat skeletal muscle has been shown to form hyaline cartilage when organ cultured upon demineralized rat bone (bone matrix). Since skeletal muscle is composed of fibrous connective tissue (C.T.) as well as muscle cells, the cartilage could arise from either of these sources. The object of this study was to determine whether cartilage arose from fibrous connective tissue or muscle cells, or both, and whether the ability to form cartilage is limited to tissues derived from somatic mesoderm. Control experiments demonstrated that 19-day embryonic rat skeletal muscle formed cartilage when organ cultured on bone matrix after dissociation and cultivation in vitro, and that 11-day embryonic chick muscle also formed cartilage, although less reproducibly (3 out of 10 cases). Fibroblasts and skeletal muscle were cloned from similar suspensions of dissociated muscle in order to test these purified cell types. Dermis, vascular tissue, and tendons were mechanically removed prior to dissociation in order to eliminate fibroblasts from contaminant sources. Cloned fibroblasts, derived from rat skeletal muscle, formed cartilage in three out of three cases. It was not possible to clone sufficient rat skeletal muscle to place an aggregate onto bone matrix. An aggregate of several hundred chick skeletal muscle clones formed cartilage on bone matrix. The freshly excised C.T. capsules of embryonic chick thyroid and lung were tested for the ability to form cartilage as nonskeletal C.T. derivatives. The epithelial rudiments of thyroid and lung were also tested as endodermal derivatives. Chick cornea was similarly tested as an ectodermal derivative. Of these tissues, only the C.T. capsules formed cartilage. The results demonstrate that various C.T. cell types may alter their phenotype well after that stage at which their differentiation is thought to be stabilized, and that the ability to differentiate as cartilage may be common to all C.T. cells. The option of differentiating along a certain variety of pathways may depend more upon local conditions than on a predetermined pattern.     

漆酶同工酶基因在斑玉蕈生长发育过程中的表达分析

为了探明漆酶在斑玉蕈生长发育过程中的功能,对斑玉蕈转录测序预测的13个漆酶基因序列进行分析、鉴定和构建分子系统发育树;检测了不同生长发育时期漆酶的活性和漆酶基因表达水平。研究结果显示：13个基因片段中有10个是漆酶基因。不同的漆酶同工酶之间进化关系存在明显差异,大多数漆酶与木腐菌（金针菇Flammulina filiformis和侧耳属Pleurotus）进化关系较近。对斑玉蕈不同生长发育时期的酶活检测结果显示,从斑玉蕈的菌丝恢复期到钉头期,漆酶活性逐渐升高,而在子实体形成后期酶活逐渐降低。对培养40d、60d和80d的菌丝样品以及不同生长发育时期的样品进RT-qPCR检测,结果显示在菌丝营养生长时期,大多数漆酶基因在第40-60天表达量持续增加1-3倍,而在第60-80天时表达量出现降低的情况。而在生殖生长时期,大多数漆酶基因在转色期或者原基期相对表达量达到最大值,并在子实体期出现降低,这与漆酶活性的检测具有一致性。lcc3、lcc7、lcc8和lcc9在斑玉蕈生殖生长过程中相对表达量出现了10-100倍的上调。这说明从菌丝培养到菌丝扭结形成子实体和子实体发育的过程中,不同的漆酶可能发挥着不同的作用,表达量较高的漆酶基因可能对基质降解和子实体形成起主要作用。     

Elucidating the Role of a Tetrafluoroborate‐Based Ionic Liquid at the n‐Type Oxide/Perovskite Interface

Halide perovskites are currently one of the most heavily researched emerging photovoltaic materials. Despite achieving remarkable power conversion efficiencies, perovskite solar cells have not yet achieved their full potential, with the interfaces between the perovskite and the charge‐selective layers being where most recombination losses occur. In this study, a fluorinated ionic liquid (IL) is employed to modify the perovskite/SnO₂ interface. Using Kelvin probe and photoelectron spectroscopy measurements, it is shown that depositing the perovskite onto an IL‐treated substrate results in the crystallization of a perovskite film which has a more n‐type character, evidenced by a decrease of the work function and a shift of the Fermi level toward the conduction band. Photoluminescence spectroscopy and time‐resolved microwave conductivity are used to investigate the optoelectronic properties of the perovskite grown on neat and IL‐modified surfaces and it is found that the modified substrate yields a perovskite film which exhibits an order of magnitude lower trap density than the control. When incorporated into solar cells, this interface modification results in a reduction in the current–voltage hysteresis and an improvement in device performance, with the best performing devices achieving steady‐state PCEs exceeding 20%.     

A Review on Additives for Halide Perovskite Solar Cells

Additives are widely adopted for efficient, stable, and hysteresis‐free perovskite solar cells and play an important role in various breakthroughs of perovskite solar cells (PSCs). Herein the various additives adopted for PSCs are reviewed and their functioning mechanism and influence on device performance is described. The main roles of additives, modulating morphology of perovskite films, stabilizing phase of formamidinium (FA) and cesium (Cs)‐based perovskites, adjusting energy level alignment in PSCs, suppressing nonradiative recombination in perovskites, eliminating hysteresis, enhancing operational stability of PSCs, are summarized.     

PPARγ与c/EBPα基因在苏太猪不同组织中的表达水平探究

为探究PPARγ与c/EBPα基因在苏太猪不同组织中的表达与脂肪沉积的关系,本实验以10月龄苏太猪为研究对象,运用实时荧光定量PCR (q RT-PCR)技术检测PPARγ与c/EBPα基因mRNA在苏太猪心、肝、脾、肺、肾、胃、背最长肌和皮下脂肪8个组织中的表达水平。结果表明,PPARγ与c/EBPα基因在苏太猪的8个组织中均有不同程度的表达,其中,PPARγ基因在苏太猪脾脏组织中的表达量最高,皮下脂肪中的表达水平仅次于脾;以背最长肌中PPARγ基因的相对表达量作对比,背最长肌与脾、肺和皮下脂肪的相对表达差异极显著(p<0.01),其余为差异不显著(p>0.05),表达量高低顺序为脾>皮下脂肪>肺>心>胃>肾>肝>背最长肌;c/EBPα基因在苏太猪的皮下脂肪的表达量最高,以背最长肌中c/EBPα基因的相对表达量作对比,在肝、脾、皮下脂肪组织中表达差异极显著(p<0.01),肺的相对表达差异显著(p<0.05),其余组织中差异不显著(p>0.05),表达量的高低顺序为皮下脂肪>肝>脾>肺>肾>心>胃>背最长肌。两基因在各组织中表达趋势趋于一致。试验结果表明PPARγ和c/EBPα基因可能对猪脂肪沉积有重要影响。     

Medical physics graduate education in Mexico and its relation to the advances in radiation oncology

AimTo evaluate the state of graduate education in medical physics and progress in radiation oncology (RO) equipment in Mexico since 2000, when conferring degrees from two master’s-degree programs in Medical Physics began.BackgroundMedical physics is a Health Profession and there are international recommendations for education, training, and certification. Both programs follow these education guidelines. The most common clinical occupation of graduates is in RO services. Techniques in Mexican RO include traditional and high-precision procedures.MethodsAcademic and occupational information about the programs and their graduates were obtained from official websites. Graduates were invited to respond to a survey that requested information about their present job. We obtained data on RO equipment and human resources from public databases and estimated staffing requirements of medical physicists (MPs).ResultsMedical physics programs have graduated a total of 225 MPs. Half of them work in a clinical environment and, of these, about 90 work in RO services. MPs with M.Sc. degrees constitute 36% of the current MP workforce in RO, estimated to be 250 individuals. Survey responses pointed out the main merits and limitations of the programs. The number of MPs in RO has increased fivefold and the number of linacs sixfold in 15 years. The present number of MPs is insufficient, according to published guidelines.ConclusionAll MPs in RO services with advanced modalities must be trained following international recommendations for graduate education and post-graduation clinical training. Education and health institutions must find incentives to create more graduate programs and clinical residencies.