MULTIPLE GENE SITES FOR 5S AND 18 + 28S RNA ON CHROMOSOMES OF <i>GLYPTOTENDIPES BARBIPES</i> (STAEGER)

Wen, Wu-Nan; León, Pedro; Hague, Donald R.

doi:10.1083/jcb.62.1.132

Cited by 32 publications

(10 citation statements)

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“…cold ethanol, after adding magnesium acetate to 1 mM. The precipitated material was resuspended in 3% potassium acetate pH 5.2 and reprecipitated with ethanol (Wen et al, 1974). U.v.…”

Section: Methodsmentioning

confidence: 99%

“…Carbon-coated Collodion-covered grids were used; preparations were rotary-shadowed at a 7 ° angle with platinum/palladium 80 : 20. Acrylamide gel electrophoresis of the nucleic acids was according to procedures already described (Wen et al, 1974), except that 0.8% agarose was used to stabilize the gels and staining was done with 0.04% methylene blue (Peacock & Dingman, 1968). Escherichia coli ribosomal RNA (Sigma) mol.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Some Physicochemical Properties of Maize Rayado Fino Virus

León¹,

Gámez²

1981

Journal of General Virology

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67 SUMMARYMaize rayado fino virus (RFV) was purified from infected maize (Zea mays) leaves. The virus had two components: empty shells and complete virus particles with sedimentation coefficients of 54S and 120S respectively, and buoyant densities of 1.28 and 1.46 g/ml in CsC1 and 1.24 and 1.37 g/ml in Cs2SO4. Virus particles were stable from pH 7 to pH 4 but not at pH 3. Isoelectric focusing of purified empty capsids revealed a single band in the pH range of 6 to 6.2. RFV contained 33 to 36% of single-stranded (ss)RNA of mol. wt. approx. 2 × 106. Dissociated coat protein migrated in acrylamide gel electrophoresis as a main band with an average mol. wt. of 2.1 x 104. RFV shares several biological and physicochemical properties with oat blue dwarf virus. These viruses appear to represent a new group of small RNA viruses, transmitted propagatively by their cicadellid vectors.

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“…cold ethanol, after adding magnesium acetate to 1 mM. The precipitated material was resuspended in 3% potassium acetate pH 5.2 and reprecipitated with ethanol (Wen et al, 1974). U.v.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Some Physicochemical Properties of Maize Rayado Fino Virus

León¹,

Gámez²

1981

Journal of General Virology

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“…Bridges went on to point out that the occurrence of homologies (in the sense of morphologically similar regions) at different sites along the same chromosome can be viewed as a "-demonstration that certain sections of normal chromosomes have actually been built up in blocks through such repeats-". But later several in situ hybridization studies indicated that ectopic pairing commonly involved the multiple sites of reiterated loci (Wen et al 1974, Pardue et al 1970, Henderson et al 1973. Zhimulev et al (2003) have compared the morphological characteristics of IH with other types of silenced chromatin such as pericentromeric heterochromatin and regions subject to position ef-fect variegation.…”

Section: Discussionmentioning

confidence: 99%

Intercalary Heterochromatin in the Pupal Foot Pad Polytene Chromosomes of Flesh Fly Parasarcophaga ruficornis Fab. (Sarcophagidae: Diptera)

Agrawal¹,

Tewari

2007

CYTOLOGIA

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Summary Polytene complement of Parasarcophaga ruficornis (Sarcophagidae: Diptera) has been analysed to provide data on intercalary heterochromatin (IH). The location of weak points and ectopic contacts has been attributed to the presence of IH in the polytene complement.The spontaneously occurring weak points appear to be distributed on all the 5 polytene chromosomes. The telomeric end of right arm of chromosome II often turns back to form an ectopic contact with the region 5B/C of the same chromosome, thus, resulting in the formation of a loop.Key words Intercalary heterochromatin, Polytene chromosomes, Ectopic contacts, Weak points.The term Intercalary Heterochromatin (IH) was introduced by Kaufmann (1939) in his studies on polytene chromosomes of Drosophila melanogaster. Since then numerous reports on the distribution of break and weak points on polytene chromosomes in Drosophila spp. have established that breaks occur much more frequently in IH than in other chromosome regions (see review Ananiev et al. 1978, Mukhina et al. 1981, Zhimulev et al. 1982, Bolshakov et al. 1985, Zhimulev 1998. Zhimulev et al. (1982) distinguished several types of weak points on polytene chromosomes of D. melanogaster viz. i) constrictions i.e. local attenuations of material between bands, ii) breaks, iii) semibreaks i.e., cracks along the bands forming V shape and iv) shifts i.e. the broken parts moved relative to each other. Moshkin et al. (2001) while examining the different aspects of IH in the region 89E1-4, the locus of the Bithorax complex, in salivary gland polytene chromosomes of Drosophila melanogaster described a similar variety of morphologies.Besides this, an infrequent non-homologus association between different chromosome arms in the salivary gland chromosomes of D. melanogaster has been reported by several workers (Bridges 1935, Kaufmann 1939, 1944, 1946, Kaufmann et al. 1947, 1948, and, referred to as "ectopic pairing" by Slizynski (1945) and Kaufmann and Iddles (1963). Many of the ectopically paired regions behave as 'weak points' and appear as constrictions (Prokofieva-Belgovaskaja 1941, Kaufmann and Iddles 1963, Zhimulev 1998. Thus, ectopic pairing is not at random and the sites that pair ectopically correlate well with the sites that are frequently the weak points. It is established that the identification of IH regions is well manifested by 2 criteria i) the presence of breaks or weak points and ii) ectopic pairing.In the present communication the occurrence of intercalary heterochromatin expressed as weak points and ectopic contacts in the pupal foot pad polytene complement of Parasarcophaga ruficornis has been analysed.

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“…Recently Cohen (1976) supported the view of Kaufmann et al, (1948) who suggested that non-homologous pairing (ectopic pairing) may be due to the association of repeated gene sequences, but not necessarily highly repeated by recording it between two different 5S sites in the genome of D. funebris. Wen et al (1974) reported the clearly labelled interchromosomal connection between two of the nucleolar organisers in the polytene chromosome of Glyptotendipes barbipes. A similar observation has also been made by Henderson et al (1973) for human chromosomes carrying the nucleolus organisers.…”

Section: Discussionmentioning

confidence: 99%