MULTIPLE ALLELES AT THE INCOMPATIBILITY LOCUS IN THE MYXOMYCETE DIDYMIUM IRIDIS

Collins , O'Neil Ray . (Queens Coll., New York City.) Multiple alleles at the incompatibility locus in the Myxomycete Didymium iridis. Amer. Jour. Bot. 50(5): 477–480. 1963.—Working with 2 isolates of Didymium iridis, from Honduras and Panama, respectively, it was shown that each isolate possesses a pair of incompatibility factors. On the basis of results from inter-isolate crosses, one pair was designated A¹ A² and the other A³ A⁴ to indicate that these factors actually constitute a series of multiple alleles at a single locus.     

GENETICS OF SOMATIC CELL FUSION IN TWO ISOLATES OF DIDYMIUM IRIDIS

Analysis of progeny from a cross between a Honduran clone and a Panamanian clone of Didymium iridis has revealed existence of five new plasmodial fusion loci in the Panamanian isolate. These are in addition to six which were previously known.     

FURTHER STUDIES IN MULTIPLE ALLELOMORPH HETEROTHALLISM IN THE MYXOMYCETE DIDYMIUM IRIDIS

Analysis of an isolate of Didymium iridis from Costa Rica indicates that it possesses a pair of incompatibility factors. These factors have been shown to be allelic with those of a Honduras and a Panama isolate. Data presented in this paper show that, among them, the 3 isolates possess 6 incompatibility alleles at 1 locus.     

CONTROL OF PLASMODIAL FUSION IN A PANAMANIAN ISOLATE OF DIDYMIUM IRIDIS

Plasmodial fusion in a Panamanian isolate (Pan. 1) of Didymium iridis is controlled by at least six fusion loci. Only plasmodia with identical phenotypes for these six loci are capable of fusion. No evidence was obtained in this study to indicate that any one fusion locus more strongly affects the fusion process than any of the other loci. Control of plasmodial fusion in the Pan. 1 strain of D. iridis is similar to that found earlier for a Honduran strain (Hon. 1).     

GENETICAL AND CYTOLOGICAL EVIDENCE FOR CHROMOSOMAL ELIMINATION IN A TRUE SLIME MOLD,DIDYMIUM IRIDIS

In crosses involving a polyploid myxamoebal clone. CR 2-25*, F₁ plasmodia and myxamoebae display a variety of unexpected ploidy levels as indicated by nuclear DNA measurements. Genetic analyses of the F₁ generations reveal either complete elimination of certain genetic markers or greatly skewed segregation ratios. On the basis of these two kinds of evidence, it is assumed that chromosome elimination occurs at some stage (or stages) following karyogamy between parental nuclei. The possible significance of polyploidy in relation to myxomycete speciation and evolution is discussed.     

NUCLEAR DNA CONTENT OF MYXAMOEBAE AND PLASMODIA IN SIX NON-HETEROTHALLIC ISOLATES OF A MYXOMYCETE,DIDYMIUM IRIDIS

The nuclear DNA content of six non-heterothallic isolates of the myxomycete Didymium iridis was measured by combining the Feulgen reaction with absorption microspectrophotometry. This allowed us to distinguish between homothallic (sexual) and apogamic (non-sexual) isolates. Four of the isolates studied, Panamanian 4 and 5, California 1, and Missouri 1 are homothallic. Moreover, the average DNA content of the myxamoebal and plasmodial nuclei (0.32 and 0.61 respectively) does not differ significantly from the calculated haploid and diploid values for heterothallic isolates of D. iridis (0.34 and 0.63). Hence, it is concluded that in each of these isolates the myxamoebae are haploid and the plasmodia diploid. In two of the isolates investigated, Georgia 1 and Hawaii 1, the DNA content of the myxamoebal and plasmodial nuclei did not differ significantly. Therefore, in both of these isolates the plasmodia appear to develop apogamically. In addition the mean DNA values recorded for the Ha-1 isolate suggest that it is aneuploid.     

QUANTITATIVE MICROSPECTROPHOTOMETRY OF NUCLEAR DNA IN SELFING STRAINS OF THE MYXOMYCETE DIDYMIUM IRIDIS

Genetic and cytochemical investigations of the origin, development, nuclear activity, and ploidy level of Plasmodia obtained from selfed clones S-2 and B₁P-33 of the heterothallic myxomycete, Didymium iridis, are presented. To demonstrate that selfing did not result from contamination of the clones, or mutations at the mating-type locus, crosses were made between F₁ clones and clones of known mating types. The data were inconsistent with these two possibilities. DNA was quantified by Feulgen-DNA microspectrophotometry. All cellular phases studied (logarithmic amoebae, swarmers, and encysted amoebae) appear to be haploid, with the nuclear DNA being in the replicated (2C) state. The plasmodia are in all cases diploid; however, the data indicate that the selfed Plasmodia are in an extended G₁ condition. The nuclear DNA content of these is therefore 2C, whereas that of the cross Plasmodium is 4C. Sporangial nuclei exhibit DNA in diploid replicated (4C) category.     

COMPARATIVE MEASUREMENTS OF NUCLEAR DNA IN A HETEROTHALLIC AND A SELF-FERTILE ISOLATE OF THE MYXOMYCETE,DIDYMIUM IRIDIS

Comparative measurements were made of the nuclear Feulgen-DNA content of a heterothallic and a self-fertile isolate of the myxomycete Didymium iridis. Plasmodial nuclei of both isolates contain the diploid amount of DNA. The replicated diploid (4C) values for the heterothallic and the self-fertile isolates are 5.66 and 5.95, respectively. Myxamoebae, however, are quite dissimilar in their nuclear DNA content. Those of the heterothallic isolates, Honduran 1–2 (A¹) and Panamanian 2–4 (A⁷), have mean values of 3.81 and 3.69, whereas myxamoebae of the self-fertile Philippine-1 isolate were found to have a mean value of 6.07. Myxamoebae of the Ph-1 isolate are, therefore, at the same ploidy level as the Ph-1 Plasmodium. Mean DNA values for Ph-1 sporangial nuclei were in category 4C. Measurement of the DNA content of mitotic metaphases in sporangia at T = 6 hr confirmed that the mean DNA content of both Ph-1 myxamoebae and plasmodial nuclei is equivalent to 4C. It is concluded that nuclear phase alternance is lacking in the Ph-1 isolate and that the Plasmodium of this isolate develops by apogamy.     

CYTOPHOTOMETRIC MEASUREMENT OF NUCLEAR DNA IN SEVEN HETEROTHALLIC ISOLATES OF DIDYMIUM IRIDIS,A MYXOMYCETE

Absorption cytophotometry was used to measure nuclear Feulgen-DNA content of myxamoebae and Plasmodia in seven heterothallic isolates of Didymium iridis. Measurements of myxamoebal nuclei from clones of four isolates (Hon 1, Pan 1, Pan 2, and CR 5) gave a mean DNA value of 0.34, whereas the nuclei of Plasmodia which develop from each of the four intraisolate crosses had a mean value of 0.63. These values correspond to the 2C haploid level in myxamoebae and the 4C diploid level in Plasmodia. DNA values in two additional isolates (Pan 3 and CR 2) are much higher than the mean for the other five. Accordingly, it is proposed that these may be polyploid. The question of polyploidy in D. iridis and in other myxomycetes is evaluated. The seventh isolate, Ky 1, is taxonomically very close to D. nigripes and was not included in calculations of mean values for D. iridis.     

HETEROTHALLISM AND HOMOTHALLISM: A STUDY OF 27 ISOLATES OF DIDYMIUM IRIDIS,A TRUE SLIME MOLD

Single pore studies of 27 isolates of Didymium iridis from several geographical locations revealed that 11 are heterothallic, displaying a one-locus, multiple allelic mating system. Collectively, 9 of the 11 possess a total of 12 mating types in one multiple allelic series. Each of the remaining two isolates has a pair of mating types which are either incompatible with the 12 or they have not yet been tested against them. Sixteen isolates proved to be homothallic.     

多巴胺能神经元的体外培养及其纯度鉴定

目的通过建立体外培养的多巴胺能神经元模型,应用于帕金森病(PD)的病因和发病机制等基础研究.方法用孕14d的胎鼠中脑嘴侧被盖部组织进行分散细胞原代培养,并用酪氨酸羟化酶(TH)免疫组化染色法鉴定其纯度.结果本实验可观察细胞历时20～30d的生长过程,并观察到细胞生长的第7～11d是细胞生长最旺盛的时期,最适宜加入处理因素观察细胞变化.培养10d的神经细胞进行TH免疫组化染色,可见胞浆被染成棕黄色的细胞遍布视野,阳性率达90%.结论体外培养的神经细胞可保持结构和功能上的某些特点,提供了体内生长过程在体外重现的可能,可广泛应用于PD病因和发病机制的研究.     

GENETIC CONTROL OF MITOCHONDRIAL THYMIDINE KINASE IN HUMAN-MOUSE AND MONKEY-MOUSE SOMATIC CELL HYBRIDS

Distinctive thymidine (dT) kinase molecular forms are present in mouse, human, and monkey mitochondria. Disk polyacrylamide gel electrophoresis (disk PAGE) analyses have shown that the mitochondrial-specific dT kinases differ from cytosol dT kinases in relative electrophoretic mobilities (Rm). Furthermore, the mouse mitochondrial dT kinase differs in Rm value from primate mitochondrial dT kinases. The mouse and primate cytosol dT kinases can also be distinguished. Disk PAGE analyses have been carried out on the cytosol and mitochondrial dT kinases of human-mouse (WIL-8) and monkey-mouse (mK·CV^III) somatic cell hybrids in order to learn whether the mitochondria of the hybrid cells contained murine mitochondrial-specific, primate mitochondrial-specific, or both dT kinases. WIL-8 cells were derived from cytosol dT kinase-negative, mitochondrial dT kinase-positive mouse fibro blasts and from cytosol dT kinase-positive, mitochondrial dT kinase-positive human embryonic lung cells; they contained mostly mouse chromosomes and a few human chromosomes, including the determinant for human cytosol dT kinase. The mK·CV^III cells were derived from cytosol dT kinase-negative, mitochondrial dT kinase-positive mouse kidney cells and from cytosol dT kinase-positive, mitochondrial dT kinase-positive monkey kidney cells; they contained mostly mouse chromosomes and a few monkey chromosomes, including the determinant for monkey cytosol dT kinase. Disk PAGE analyses demonstrated that the mitochondria of human-mouse and monkey-mouse somatic cell hybrids contained the mouse-specific mitochondrial dT kinase but not the human- or monkey-specific mitochondrial dT kinase. These findings suggest that primate cytosol and mitochondrial thymidine kinase genes are coded on different chromosomes.     

防风悬浮培养中的体细胞胚发生

将防风（Ｓａｐｏｓｈｎｉｋｏｖｉａ ｄｉｖａｒｉｃａｔａ （Ｔｕｒｃｚ．） Ｓｃｈｉｓｃｈｋ．）试管苗幼根接种在含０．５ ｍ ｇ／Ｌ ２,４－Ｄ 的ＭＳ培养基上诱导出愈伤组织,继而在含１０％ 椰子乳和０．５ ｍ ｇ／Ｌ ２,４－Ｄ的ＭＳ液体培养基中振荡分散建立了细胞悬浮物。至胚性细胞团产生后转至无激素培养基中形成体细胞胚。观察了从单细胞直到球形胚发生的显微及超微结构的变化。在胚性细胞团阶段细胞内出现周质内质网,它的出现可能与细胞团向原胚过渡时的特殊代谢相联系。从单细胞至原胚各阶段细胞内均含有圆球体,到原胚时数量大增,而且其中央电子致密的基质变小变浅,周边部分扩大并更加透明,暗示圆球体在胚胎发生早期起着贮藏蛋白或脂蛋白的作用,后来消耗于原胚的建成而衍生为脂滴。球形胚阶段,在很多细胞的液泡中出现团块状的液泡蛋白。此外还观察到,悬浮培养时单细胞的聚集能促进体细胞胚的发生     

INTERSPECIFIC INCOMPATIBILITY IN GOSSYPIUM. II. LIGHT AND ELECTRON MICROSCOPE STUDIES OF CELL NECROSIS AND TUMORIGENESIS IN HYBRIDS OF G. KLOTZSCHIANUM

Many Gossypium interspecific hybrids that involve G. klotzschianum result in either embryo or seedling lethals. Histologically, lethal symptoms are characterized by necrotic cells and tumors that appear 10–15 days after fertilization in the embryo lethals and at the first true-leaf stage in the seedling lethals. Ultrastructural studies of cell necrosis in seedling lethals show that the first subcellular abnormality is the degeneration of the inner membrane and cristae of the mitochondria. Mitochondrial degeneration is essentially complete before other organelles show evidence of structural aberrations.     

人肾小球系膜细胞葡萄糖转运蛋白的研究

本文采用了RT-PCR,细胞免疫荧光染色及流式细胞仪分析技术证实人肾小球系膜细胞有GLUT1(glucose transportorl)mRNA和蛋白质的表达。用2-Deoxy[~3H]-D-Glucose摄入法与根皮素抑制实验肯定了系膜细胞上GLUT1的功能及其在系膜细胞葡萄糖摄入中的作用。本项研究为进一步研究系膜细胞GLUT1在糖尿病肾病发病机理中的作用奠定了基础。