向日葵染色体Giemsa C-分带研究

采用HKG (HCI-KOH-Giemsa)法对内葵杂3号三交种染色体进行了C-分带研究和分析.结果表明:每条染色体至少都有一条C-分带,染色体组共有62务C-分带,以中间带和着丝点带为主,中间带主要分布在染色体短臂上;C-分带强弱差异明显,其中46条强带,16条弱带.Giemsa C-分带带型公式为:2n =2x =34 =8I++3T++5I+I+T++4C +2CI+4CI+ +3CI+ +I+T++CT++2CT+.每条染色体都显示出显著的带纹特征,因此,利用Giemsa C-分带方法可以将向日葵的每条染色体区分开.     

Giemsa Poststaining of Sections Stained for Acetyl-Cholinesterase Improves Sensitivity and Contrast

During investigations into the cholinergic innervation of blood vessels in skeletal muscle, it was found that poststaining of sections with Giemsa's stain (Gurr, R66) after incubation to reveal acetylcholinesterase activity as copper ferrocyanide (El-Badawi and Schenk 1967) not only produced nuclear and cytoplasmic counter-staining, but also resulted in intensification of the reaction, resulting in deep blue-black nerve endings (Fig. 1). Areas previously distinguishable only by phase contrast were easily recognizable after Giemsa staining. The method described was originally used on 10 μm cryostat sections, pre- or postfixed in formolcalcium and stained in the reaction mixture described by El-Badawi and Schenk (1967) for 30-60 minutes. After rinsing in distilled water (5 min), sections were stained in Giemsa's stain (3 min), washed well in distilled water, rapidly dehydrated, cleared and mounted.     

Giemsa Banding in Chromosomes of Douglas Fir Seedlings and Plantlets

Douglas fir plantlets have been produced by tissue culture.Karyotypes of seedlings and plantlets were prepared from roottip squash preparations using standard histological procedures.Adiploidchromosome number of 26 was common to both. The relative lengths of seedling and plantlet chromosomes werefound to be similar. The frequency of occurrences of secondaryconstrictions was found to be high in chromosomes three andten. Giemsa staining was successfully used to distinguish uniquechromosomal banding patterns in seedlings and plantlets. Pseradotsuga menziesii, Douglas fir, chromosomes, giemsa staining     

The Number of Chromosomes in SCHIZOSACCHAROMYCES POMBE: Light Microscopy of Stained Preparations

Chromosomes have been counted with the light microscope in fixed and stained preparations of Schizosaccharomyces pombe. The least ambiguous images were seen in zygotes fixed at meta-, ana- and telophase of meiosis II. They suggest that the haploid number of chromosomes in S. pombe is three.     

A Method to Visualize Harlequin Stained Chromosomes without Interference by Autoradiographic Grains

If autoradiograms of tritium labeled harlequin chromosomes are stained with the fluorescent dye acridine orange, it is possible to see clearly a fluorescent image of the chromosomes without the silver grains obscuring the image. If fluorescent and bright field microscopy are alternated, the chromosomes and the autoradiogram can be studied repeatedly without having to resort to the study of sequential photographs. The technique is particularly useful for the study of heavily labeled chromosomes.     

Elimination of Material that Obscures Stained Chromosomes in Squashes of Vicia faba Root Tips

A procedure for elimination of cytoplasmic debris from Vicia faba root tip cells is: (1) a root tip previously fixed in 3:1 absolute alcohol-acetic acid and stained by the Feulgen method is placed on a slide and squashed in a small drop of water, (2) a cover slip is applied and the cells are flattened with a hand-operated lever device supplying 35 pounds pressure onto a 22 × 22 mm cover glass, (3) the slide is quick-frozen, the cover slip is removed, and the slide is dropped immediately into water, (4) the slide is cleared through an alcohol-xylene dehydration series and permanently mounted. The significant result of this procedure is the consistent presence of clear, flat cells showing excellent definition of chromosomes.     

Obesity QTLs on Mouse Chromosomes 2 and 17

The inheritance of obesity has been analyzed in an intercross between the mouse strains AKR/J and C57L/J. Two novel obesity quantitative trait loci (QTLs) have been identified using the strategy of selective DNA pooling. One QTL affecting adiposity,Obq3,was mapped to a 39-cM segment near the middle of Chromosome 2, with a peak lod score (5.1) just distal to theD2Mit15locus. The AKR/JObq3allele confers increased adiposity in a nearly additive manner, and males are more affected than females. A second obesity QTL (Obq4) maps to the centromeric end of Chromosome 17, with a lod score peak of 4.6 atD17Mit143.The obesity-conferring allele is contributed by C57L/J and acts in a recessive or an additive manner.Obq4also has more influence in males and affects the inguinal fat depot differentially.Obq3andObq4account for 7.0 and 6.1% of the phenotypic variance in adiposity (gender-merged data), respectively. The possible relationships between these QTLs and previously described obesity QTLs and candidate genes are discussed. The large number of different obesity QTLs that have been described in mice and the relatively small effects contributed by individual loci suggest considerable genetic complexity.     

Improved Techniques Using Giemsa Stained Glycol Methacrylate Tissue Sections to Quantitate Basophils and Other Leukocytes in Inflammatory Skin Lesions

Improved techniques were developed for processing inflammatory skin lesions in glycol methacrylate (JB-4, Polysciences, Inc.) and for quantitating their leukocyte infiltrates by light microscopy: (1) fixation of entire pelts from rabbits, guinea pigs, rats and mice bearing multiple lesions eliminated artifacts due to biopsy and produced uniformly oriented skin sections; (2) adding dimethylsulfoxide and hydrogen peroxide to the Karnovsky-type fixative increased the rate and effectiveness of fixation; (3) the presence of glycerol in the infiltrating methacrylate and the polymerized plastic block improved the sectionability of skin and other tissues; (4) coating slides with JB-4 Solution A prevented detachment of specimens; (5) Giemsa staining at a carefully selected pH provided optimal differentiation of leukocytes from the several species examined, including man. These techniques, which allowed an accurate histologic assessment of inflammatory skin lesions, were especially valuable for quantitating basophils.     

The Relationship of Slide Maturity and Trypsin Exposure Time in the Differential Giemsa Banding of Chromosomes

Difficulty has been reported in attaining consistent chromosome banding using trypsin-Giemsa techniques. When trypsin concentration, incubation temperature, and the duration of staining are held constant, a logarithmic relationship has been found to exist between the length of time since a slide was made and the length of trypsin treatment necessary to produce optimal banding when it is stained. Under the conditions specified in this report, ten seconds digestion was optimal for ten-day-old slides. This time approximately doubled for each additional eight days that slides were allowed to age. From a plot of the experimental results, treatment times appropriate for slides of any age from 10 to 60 days were obtained. Use of these times produced satisfactory banding in 85% of mitoses.     

Recombination Suppression by Heterozygous Robertsonian Chromosomes in the Mouse

Robertsonian chromosomes are metacentric chromosomes formed by the joining of two telocentric chromosomes at their centromere ends. Many Robertsonian chromosomes of the mouse suppress genetic recombination near the centromere when heterozygous. We have analyzed genetic recombination and meiotic pairing in mice heterozygous for Robertsonian chromosomes and genetic markers to determine (1) the reason for this recombination suppression and (2) whether there are any consistent rules to predict which Robertsonian chromosomes will suppress recombination. Meiotic pairing was analyzed using synaptonemal complex preparations. Our data provide evidence that the underlying mechanism of recombination suppression is mechanical interference in meiotic pairing between Robertsonian chromosomes and their telocentric partners. The fact that recombination suppression is specific to individual Robertsonian chromosomes suggests that the pairing delay is caused by minor structural differences between the Robertsonian chromosomes and their telocentric homologs and that these differences arise during Robertsonian formation. Further understanding of this pairing delay is important for mouse mapping studies. In 10 mouse chromosomes (3, 4, 5, 6, 8, 9, 10, 11, 15 and 19) the distances from the centromeres to first markers may still be underestimated because they have been determined using only Robertsonian chromosomes. Our control linkage studies using C-band (heterochromatin) markers for the centromeric region provide improved estimates for the centromere-to-first-locus distance in mouse chromosomes 1, 2 and 16.