STUDIES ON THE BIOSYNTHESIS OF COLLAGEN : I. THE GROWTH OF FOWL OSTEOBLASTS AND THE FORMATION OF COLLAGEN IN TISSUE CULTURE

1. A tissue culture method was devised in which suspensions of osteoblasts, obtained directly from frontal bones of fowl embryos, were grown in a fluid, fibrin-free medium. 2. Maximum growth of the tissue, as measured by dry weight, with the formation of collagen protein, based on the estimation of hydroxyproline, was obtained in periods of up to 6 days. 3. Appreciable amounts of protein-bound hydroxyproline were formed during the first 24 hour growth period, but electron microscopy of portions of the same cultures failed to demonstrate the presence of any typical collagen fibrils. 4. The subsequent formation of many characteristic collagen fibrils was not associated with a significant rise in the mean hydroxyproline content of the tissue. 5. The cytoplasmic granules of the osteoblasts stained intensely with the P.A.S. technique when the collagen fibrils were being formed. 6. It is suggested that collagen-forming cells synthesise and secrete a hydroxyproline-rich precursor of protein or large peptide nature, which subsequently becomes directly transformed into typical collagen fibrils.     

COLLAGEN BIOSYNTHESIS : TISSUE CULTURE EXPERIMENTS TO ASCERTAIN THE ROLE OF ASCORBIC ACID IN COLLAGEN FORMATION

Quantitative studies of collagen formation by chick embryonic lung tissue grown in media deficient in, or completely lacking, ascorbic acid have been carried out. Cell growth and collagen formation in such cultures can proceed almost normally in media lacking ascorbic acid. Ascorbic acid in combination with whole embryo extract, dialyzed media, or synthetic mixture number 703 was found to have no appreciable effect on cell growth or total collagen formation. This is in marked contrast to the almost total failure of collagen formation in scorbutic animals and suggests that for slow collagen biosynthesis as distinct from more prolific collagen-producing systems, ascorbic acid plays an indirect role.     

湖北贝母组织培养研究 Ⅰ.湖北贝母的愈伤组织培养与形态发生

本文报道了湖北贝母在不同生长时期、不同外植体来源、不同激素浓度与组合,以及培养方法和温度对愈伤组织诱导与形态发生的影响。     

禿杉组织培养研究

本文详细报道了从秃杉(Taiwania flousiana Gaussen)离体胚诱导不定芽、不定根及从无菌苗茎端培养再生植株的过程。诱导不定芽要求较低的蔗糖浓度(以3％最好);同时BA是必须的,在附加0.1—3 mg/1 BA的White培养基上,从离体胚的子叶或胚轴上诱导了不定芽的发生(以1 mg/1最好);NAA与BA结合使用,对不定芽诱导无促进作用;适当提高光照有利于不定芽的诱导。在诱导不定芽的同时,在子叶表面还观察到有许多无结构的“不定突起”。不定芽起源于子叶表皮下1—2层细胞。IBA对诱导离体胚上产生不定根效果较好。在有或无生长素的培养基上,从生长1月龄的无菌苗茎端培养获得了不定根的产生,在加有细胞分裂索的培养基上,从无菌苗上产生了腋芽。     

槐树组织细胞培养的研究

系统研究了槐树叶片、子叶及花药的培养方法和植株再生,获得了大量的试管苗,建立了槐树二倍体和单倍体植株快速繁殖的培养程序。实验表明在MS附加高浓度比值BA／IBA或2,4-D的培养基中可诱导各种外植体在短期内产生大量的不定芽和试管苗,但同时,又诱导产生了许多超度含水态苗。在培养过程中,BA浓度先高后低,既可获得大量的试管苗,又相对降低了超度含水态苗的比率,是槐树快速繁殖程序中的重要一环。组织学观察显示,槐树子叶切块培养中形成的胚状体来自于子叶的表皮及叶肉细胞,通过单细胞起源和多细胞出芽两种方式产生。     

鹤望兰组织培养与工厂化快繁程序的研究

将材料接种于诱导愈伤组织手芽的培养基上,培养２个月后,胚芽外植体下出现白色颗粒状的愈伤组织,４个月后愈伤组织上出现小芽丛。将小芽丛转入不加植物激素的ＭＳ培养基上,芽的生长加快,２个月左右可长成３－６ｃｍ高的丛小植株。将小植株切下,插入根培养基中,一般３５ｄ左右基部突出很小的白色根尖。     

甜茶组织培养研究

甜茶的茎段和实生苗培养在MS基本培养基中,研究植物激素对器官形成的影响,试验结果表明BA0.5-2.0毫克/升明显促进芽的形成和增殖;而对照(基本培养基)无形成芽。细胞分裂素对芽的起动是必需的。BA0.5-2.0毫克/升和GA_s1.0毫克/升配合使用,对茎段形成芽和增殖反而减少,但形成的苗较高和幼叶生长良好。通过继代培养,可繁殖大量小苗,它揭示出同一块外植体生长出许多小植株的可能,将无根苗转入含有IBA0.25-0.50毫克/升的1/2MS培养基中,能诱导生根,发展完整植株。试管苗移植土壤中,获得成功,幼苗生长良好。     

STUDIES ON THE INTRACELLULAR DIGESTIVE PROCESS IN MAMMALIAN TISSUE CULTURE CELLS

DNA-protein coacervates containing colloidal gold particles were readily phagocytized by strain L fibroblasts. During the subsequent digestion process, the gold particles served as markers which permitted the demonstration of the evolution of digestive vacuoles to multivesicular bodies and finally to dense bodies. Acid phosphatase and esterolytic activity was present in these structures. The hydrolytic enzymes were apparently brought to the phagocytotic vacuoles in small vesicles originating in the Golgi region. These vesicles entered the vacuoles prior to the digestion of the coacervates and the appearance of positive cytochemical reactions. The cytoplasmic dense bodies frequently merged with the phagocytotic vacuoles. This was demonstrated by prelabeling the dense bodies with colloidal iron prior to phagocytosis of the coacervates. In addition, evidence is presented for the interrelationship of the phagocytotic and autophagic pathways.     

小麦幼穗的组织培养及愈伤组织的分化研究

对普通小麦“津丰-55”的幼穗进行了组织培养,并跟踪研究了培养基中生长素、细胞分裂素、蔗糖、Ag~+以及一些维生素等附加成分对愈伤组织的生长、根苗分化的影响。对愈伤组织再生植株的途径也进行了研究。     

AN ATTEMPT TO INHIBIT THE MULTIPLICATION OF TOBACCO MOSAIC VIRUS IN TISSUE CULTURE BY ITS ANTISERUM

Extracts from tobacco tissue cultures infected with tobacco mosaic virus grown in medium containing antiserum to the virus had only one-half to one-sixteenth as much virus as extracts from tissues grown in medium without the antiserum. When tissues grown with antiserum were thoroughly washed before they were extracted, the extracts contained as much virus as extracts of tissues grown without antiserum. The antiserum did not affect virus multiplication, but antibodies in the tissues may have precipitated virus either in the cells or when the tissues were macerated.     

THE BIOSYNTHESIS OF CHOLESTEROL AND OTHER STEROLS BY BRAIN TISSUE

Abstract— The distribution of [¹⁴C]labelled material into subcellular fractions of 30-day-old rat brain was studied as a function of time, following intracerebral injection of [2-¹⁴C] mevalonic acid. As in the adult and 15-day-old brain, the microsomal fraction was indicated as the site of sterol synthesis. Unlike the 15-day-old animal, the myelin fraction from the 30-day-old rat was the predominately labelled fraction at 2 weeks after injection of the animal. Significant amounts of [¹⁴C]cholesterol were not present until about 4 h after injection. In order to ascertain whether different populations of cholesterol were being labelled, depending on the age of the animal injected, we compared the labelling of myelin and non-myelin components in animals injected at 15 or at 30 days of age, and sacrificed, respectively, from 14 to 29 days or from 1 to 28 days after injection. Our results indicated that there was an apparent shift of labelled sterol from non-myelin to myelin fractions at about 37–44 days of age.     

STIMULATION OF COLLAGEN SYNTHESIS IN RAT CARDIAC FIBROBLASTS BY EXPOSURE TO HYPOXIC CULTURE CONDITIONS AND SUPPRESSION OF THE EFFECT BY NATRIURETIC PEPTIDES

Synthesis of type I and type III collagens by rat cardiac fibroblasts was stimulated when the cells were cultured under 95% N₂/5% CO₂for one hour followed by incubation under normoxic conditions for 24 hours. The stimulative effect was attenutated by the presence of atrial natriuretic peptide (ANP, 10⁻⁶m) or brain natriuretic peptide (BNP, 10⁻⁶m) in the culture medium. Northern blot analysis indicated that α1(I) and α1(III) collagen mRNA levels were also increased by hypoxia, and decreased with the addition of ANP or BNP in a dose-dependent manner. These results indicate interaction between intracellular signals of a physical stimulus (hypoxic stress) and those of a chemical one (ANP or BNP) and demonstrate that both signals regulate collagen synthesis by cardiac fibroblasts at the levels of the mRNAs. The results also suggest that natriuretic peptides produced by cardiomyocytesin vivomay function as paracrine factors that play a role in the prevention of cardiac fibrosis in ischaemic heart diseases.     

罗汉果茎段离体培养研究

罗汉果茎段培养在MS基本培养基中,研究植物激素对器官形成的影响,试验结果表明细胞分裂素BA促进芽的形成和增殖;而KT则有利于根的形成,却抑制芽的增殖,BA和IBA配合使用,对茎段形成芽有增效作用。通过继代培养,能繁殖大量绿苗,这揭示出同一块离体茎组织培养出许多小植株的可能,将嫩梢转入含有NAA0.2毫克/升的1/2MS培养基中,能诱导生根,形成完整小植株,试管苗成功地移栽田间,并已开始开花结果,     

槐树子叶组织培养中的形态发生研究

槐树子叶在MS附加0.1～5 mg/L BA 和0.1—5 mg/L 2,4-D的培养丛上培养两周,获得了灰色疏松型及白、绿色紧密型两种类型的愈伤组织。后者经培养产生不定芽并再生植株。子叶切块在MS 附加0.1～8 mg/L 2,4-D等培养基上培养3周,在切口处形成愈伤组织的同时,由其表面直接分化产生胚状体。组织学观察表明,胚状体来源于子叶的表皮及叶肉细胞,胚状体产生通过单细胞起源及多细胞出芽两种方式发生。胚状体发育依次通过球形胚、心形胚、鱼雷形胚和子叶胚等阶段形成再生植株,其发育过程与合子胚相似。     

STUDIES ON THE ORIGIN OF PYRIMIDINES FOR BIOSYNTHESIS OF NEURAL RNA IN THE RAT

Uridine was far superior to orotic acid in labelling the RNA in incubated slices of rat brain. On the other hand, uridine and orotic acid were equally effective in labelling the RNA of hepatic or renal slices In rats in vivo, uridine, but not orotic acid, labelled brain RNA, and the cerebellar RNA contained the most label. In contrast, both uridine and orotic acid labelled hepatic RNA. Only when surgical intervention prevented peripheral metabolism of orotic acid, thereby raising its concentration in the plasma, did neural tissue utilize this precursor for limited biosynthesis of RNA. However, among the tissues studied, the preference for uridine over orotic acid for RNA synthesis was unique to neural tissue.     

珊瑚豆果实成熟过程中叶绿体转化为杂色体的研究

珊瑚豆 (Solanum pseudo- capsicum var.diflorum (Vell.) Bitter)果实成熟过程中 ,果实颜色的变化和叶绿素含量降低及类胡萝卜素含量增长相符合。对果实中叶绿体转化为杂色体进行了电镜观察。早期绿色果实的特点是叶绿体具典型的基粒 -基粒间类囊体结构。在黄绿色果实时期叶绿体类囊体系统解体 ,代之以少数非叶绿素的单个类囊体和积累大的嗜锇的质体小球。质体转变为所谓的原质体。这表明叶绿体在果实成熟中的脱分化过程。当果实达到黄色阶段 ,这些质体所含的质体小球开始从中央形成质体小管的结构。最初质体小球中央变为半透明 ,认为是质体累积胡萝卜素的开始。随着质体小球的延长 ,小管从小球中伸出。这些小管围以电子致密的膜 ,中央是半透明的轴心。与此同时 ,在质体基质中出现一系列发育不同阶段的小泡 ,似乎是形成新的质体小球的过程。在成熟的橙色和橙红色果实中的杂色体中只包含无数小管和小的质体小球。质体小管在数量和长度上增长 ,充满成熟的杂色体。无数质体小球分布在小管之间的空间中。成熟杂色体从脱分化的原质体的重建是真正的再分化过程。可以作出结论 ,珊瑚豆果实叶绿体转化为杂色体实质上是一个脱分化和再分化过程