scholarly journals G banding in two species of grasshopper and its relationship to C, N, and fluorescence banding techniques

Genome ◽  
1991 ◽  
Vol 34 (4) ◽  
pp. 638-643 ◽  
Author(s):  
J. P. M. Camacho ◽  
J. Cabrero ◽  
E. Viseras ◽  
M. D. Lopez-Leon ◽  
J. Navas-Castillo ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Dna Sequences ◽  
Locusta Migratoria ◽  
Nucleolus Organizer ◽  
Banding Technique ◽  
Eyprepocnemis Plorans ◽  
Grasshopper Species ◽  
Nucleolus Organizer Regions ◽  
Dapi Banding ◽  
Regular Patterns

A G banding technique combining trypsin and hot saline treatments was used to analyze the chromosomes of two grasshopper species, Eyprepocnemis plorans and Locusta migratoria, both of which contain both standard and supernumerary heterochromatin. Although this technique does not produce G bands like those in mammalian chromosomes, it serves to characterize heterochromatic regions whose nature has been inferred from other banding techniques (C, N, CMA, and DAPI banding). The light regions revealed by G banding contain GC-rich DNA sequences, the more prominent of which coincide with nucleolus organizer regions (NORs). Furthermore, the proximal heterochromatin in E. plorans was heterogeneous, and the standard and supernumerary heterochromatin showed conspicuous differences in organization. Supernumerary heterochromatin is an exception to the regular patterns shown by the standard heterochromatin. The findings are related to the mechanism of action of these banding techniques.Key words: banding techniques, grasshoppers, Eyprepocnemis plorans, Locusta migratoria.

The nucleolus organizer regions (Nor loci) of hexaploid wheat cultivars

1992 ◽  
Vol 43 (5) ◽  
pp. 889 ◽  
Author(s):  
CE May ◽  
R Appels
Keyword(s):  
Dna Sequences ◽  
Intergenic Spacer ◽  
Wheat Breeding ◽  
Nucleolus Organizer ◽  
Rrna Genes ◽  
F1 Hybrids ◽  
Dna Fragments ◽  
Wheat Cultivars ◽  
Nucleolus Organizer Regions ◽  
Spacer Dna

We have used the techniques of molecular genetics to analyse the nucleolus organizer regions (Nor loci) of a broad range of Australian, Chinese, and other hexaploid wheats (Triticum aestivum L. em Thell.). Genomic DNA was extracted from the leaves of 260 wheat cultivars, 94 different F1 hybrids, and from more than 800 F2 plants. Samples of the DNA were digested with the restriction enzyme TaqI and electrophoretically separated in agarose gels. The DNA fragments were then transferred to DNA filters by Southern blotting and assayed with the probe pTa250.4. This probe specifically detects the intergenic spacer DNA sequences which alternate with the ribosomal-RNA (rRNA) genes in highly repeated tandem arrays within the Nor loci. Analyses of the spacer DNA restriction fragments present in P, F1 and F2 plants show that allelic variants of the Nor loci can be distinguished by the existence of different lengths of spacer DNA fragments, different combinations of different length fragments, or differing amounts of the same length fragments. Eight alleles of the Nor-B1 locus on chromosome 1B (Nor-Bla to Nor-B1h) and 20 variants of the Nor-B2 locus on chromosome 6B (Nor-B2a to Nor-B2t) have been identified. The DNA fragments present in the different alleles are expressed in a co-dominant fashion to give phenotypic F2 ratios of 1 : 2 : 1 and 1 : 2 : 1 : 2 : 4 : 2 : 1 : 2 : 1, indicating segregation at one or two loci, respectively. With two exceptions, individual alleles segregated in a 1 : 1 ratio. On the basis of the presence of different combinations of Nor-B1 and Nor-B2 alleles, the wheat cultivars investigated were divided into 53 phenotypic groups. These groups clearly reflect the germplasm used in wheat breeding programs in different countries. Hybrid wheats could also be recognized and plants with new combinations of alleles were produced.

scholarly journals Karyotype description and evidence of multiple sex chromosome system X1X1X2X2/X1X2Y in Potamotrygon aff. motoro and P. falkneri (Chondrichthyes: Potamotrygonidae) in the upper Paraná River basin, Brazil

2011 ◽  
Vol 9 (1) ◽  
pp. 201-208 ◽  
Author(s):  
Vanessa Paes da Cruz ◽  
Cristiane Kioko Shimabukuro-Dias ◽  
Claudio Oliveira ◽  
Fausto Foresti
Keyword(s):  
Sex Chromosome ◽  
Chromosomal Rearrangements ◽  
Chromosomal Evolution ◽  
Nucleolus Organizer ◽  
Banding Technique ◽  
Nucleolus Organizer Regions ◽  
Sex Chromosome System ◽  
Upper Paraná River ◽  
Upper Paraná River Basin ◽  
Almost All

Cytogenetic analysis of Potamotrygon aff. motoro and P. falkneri indicated the occurrence of an X1X1X2X2/X1X2 Y multiple sex chromosome system in both species, with 2n = 66 chromosomes for females and 2n = 65 chromosomes for males. The nucleolus organizer regions (NORs) identified using Ag-NOR technique showed that both species have multiple Ag-NORs (5 to 7 chromosomes stained). C-banding technique indicated the presence of heterochromatic blocks in the centromeric regions of almost all chromosomes in both species. Through this study there was evidence of heterogeneity in the karyotypes, which suggests that chromosomal rearrangements such as inversions and/or translocations occurred during the chromosomal evolution in two species of this genus.

scholarly journals Chromosome Banding in Amphibia. XXXIII. Demonstration of 5-Methylcytosine-Rich Heterochromatin in Anura

2016 ◽  
Vol 148 (1) ◽  
pp. 35-43
Author(s):  
Michael Schmid ◽  
Claus Steinlein
Keyword(s):  
Dna Sequences ◽  
Nucleolus Organizer ◽  
Major Influence ◽  
Banding Patterns ◽  
Nucleolus Organizer Regions ◽  
Experimental Parameters ◽  
Species Specific ◽  
Antibody Labeling ◽  
Chromosome Regions

An experimental approach using monoclonal anti-5-methylcytosine (5-MeC) antibodies and indirect immunofluorescence was elaborated for detecting 5-MeC-rich chromosome regions in anuran chromosomes. This technique was applied to mitotic metaphases of 6 neotropical frog species belonging to 6 genera and 4 families. The hypermethylation patterns were compared with a variety of banding patterns obtained by conventional banding techniques. The hypermethylated DNA sequences are species-specific and located exclusively in constitutive heterochromatin. They are found in centromeric, pericentromeric, telomeric, and interstitial positions of the chromosomes and adjacent to nucleolus organizer regions. 5-MeC-rich DNA sequences can be embedded both in AT- and GC-rich repetitive DNA. The experimental parameters that have major influence on the reproducibility and quality of the anti-5-MeC antibody labeling are discussed.

scholarly journals Response recovery in the locust auditory pathway

2016 ◽  
Vol 115 (1) ◽  
pp. 510-519
Author(s):  
Sarah Wirtssohn ◽  
Bernhard Ronacher
Keyword(s):  
Temporal Resolution ◽  
Auditory Processing ◽  
Locusta Migratoria ◽  
Nonlinear Effects ◽  
Auditory Pathway ◽  
Relevant Information ◽  
Spike Timing ◽  
Waveform Analysis ◽  
Grasshopper Species ◽  
Response Recovery

Temporal resolution and the time courses of recovery from acute adaptation of neurons in the auditory pathway of the grasshopper Locusta migratoria were investigated with a response recovery paradigm. We stimulated with a series of single click and click pair stimuli while performing intracellular recordings from neurons at three processing stages: receptors and first and second order interneurons. The response to the second click was expressed relative to the single click response. This allowed the uncovering of the basic temporal resolution in these neurons. The effect of adaptation increased with processing layer. While neurons in the auditory periphery displayed a steady response recovery after a short initial adaptation, many interneurons showed nonlinear effects: most prominent a long-lasting suppression of the response to the second click in a pair, as well as a gain in response if a click was preceded by a click a few milliseconds before. Our results reveal a distributed temporal filtering of input at an early auditory processing stage. This set of specified filters is very likely homologous across grasshopper species and thus forms the neurophysiological basis for extracting relevant information from a variety of different temporal signals. Interestingly, in terms of spike timing precision neurons at all three processing layers recovered very fast, within 20 ms. Spike waveform analysis of several neuron types did not sufficiently explain the response recovery profiles implemented in these neurons, indicating that temporal resolution in neurons located at several processing layers of the auditory pathway is not necessarily limited by the spike duration and refractory period.

Polymorphism of interphase nucleolus organizer regions in imported pigs and their offspring

2014 ◽  
Vol 40 (3) ◽  
pp. 211-213
Author(s):  
S. K. Buteeva ◽  
M. L. Kochneva ◽  
K. V. Zhuchaev ◽  
S. V. Papshev
Keyword(s):  
Nucleolus Organizer ◽  
Nucleolus Organizer Regions

Age-related influence of piracetam on mitotic index and number of silver-stained nucleolus organizer regions

1992 ◽  
Vol 14 (2) ◽  
pp. 213-220 ◽  
Author(s):  
Walter Vormittag ◽  
Christian Ensinger ◽  
Leo Lesnjakovic ◽  
Scheiber Viktor
Keyword(s):  
Mitotic Index ◽  
Nucleolus Organizer ◽  
Nucleolus Organizer Regions ◽  
Age Related

Molecular characterization of SerH3, a Tetrahymena thermophila gene encoding a temperature-regulated surface antigen

1990 ◽  
Vol 10 (11) ◽  
pp. 6091-6096
Author(s):  
M M Tondravi ◽  
R L Willis ◽  
H D Love ◽  
G A Bannon
Keyword(s):  
Surface Antigen ◽  
Dna Sequences ◽  
Tetrahymena Thermophila ◽  
Transcription Unit ◽  
Genomic Fragment ◽  
Gene Encoding ◽  
Tryptophan Residues ◽  
Functional Copy ◽  
Regular Patterns

The DNA sequences of a cDNA clone and the macronuclear genomic fragment corresponding to the functional copy of the SerH3 surface antigen gene of Tetrahymena thermophila were determined. Primer extension and nuclease protection assays show that the SerH3 transcription unit is 1,425 nucleotides long and contains no introns. The predicted polypeptide encoded by the SerH3 gene has a molecular mass of 44,415 daltons; one-third of its 439 residues are either cysteine, serine, or threonine. The central half of the polypeptide consists of three homologous domains in tandem array; within these domains, the cysteine, proline, and tryptophan residues occur in highly regular patterns.

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