Chromosomes Research Papers - Academia.edu (original) (raw)

A thorough understanding of the mechanisms of R-, C-and G-banding will come only from studies of the binding of Giemsa dyes to isolated and characterized preparations of heterochromatin and euchromatin. Since such studies require an exact... more

A thorough understanding of the mechanisms of R-, C-and G-banding will come only from studies of the binding of Giemsa dyes to isolated and characterized preparations of heterochromatin and euchromatin. Since such studies require an exact knowledge of the optical characteristics of Giemsa, the spectral adsorption curves and extinction coefficients of Giemsa and its component dyes at various concentrations in the presence and absence of DNA were determined. — Although Giemsa is a complex mixture of thiazin dyes plus eosin; methylene blue, and azure A, B or C alone gave good banding. Thionin, with no methyl groups, gave poor or no banding. Eosin was not a necessary component for banding. — The most striking characteristic of the thiazin dyes is that they are strongly metachromatic, i.e., their adsorption spectra and extinction coefficients change as the concentration of the dye increases or as they bind to positively charged compounds (chromotropes). These changes, especially for methylene blue, are described in detail and allow a distinction between concentration dependent binding to DNA by intercalation and binding by side stacking.

Advances in molecular genetics have opened opportunities to enhance strategies for genetic improvement of pigs by directly selecting on genes or chromosomal regions that harbor genes that affect traits of interest. In this paper, we... more

Advances in molecular genetics have opened opportunities to enhance strategies for genetic improvement of pigs by directly selecting on genes or chromosomal regions that harbor genes that affect traits of interest. In this paper, we review molecular technologies that have become available, the current state of the use of gene- or marker tests in pig breeding programs, and future prospects.

Isolated Chinese hamster metaphase chromosomes were resuspended in 4 M ammonium acetate and spread on a surface of distilled water or 0.15 to 0.5 M ammonium acetate. The DNA was released in the form of a regular series of rosettes... more

Isolated Chinese hamster metaphase chromosomes were resuspended in 4 M ammonium acetate and spread on a surface of distilled water or 0.15 to 0.5 M ammonium acetate. The DNA was released in the form of a regular series of rosettes connected by interrossette DNA. The mean length of the rosette DNA was 14 μm, similar to the mean length of 10 μm for chromomere DNA of Drosophila polytene chromosomes. The mean interrosette DNA was 4.2 μm. SDS gel electrophoresis of the chromosomal nonhistone proteins showed them to be very similar to nuclear nonhistone proteins except for the presence of more actin and tubulin. Nuclear matrix proteins were present in the chromosomes and may play a role in forming the rosettes. Evidence that the rosette pattern is artifactual versus the possibility that it represents a real organizational substructure of the chromosomes is reviewed.

Plant pathogen resistance is mediated by a large repertoire of resistance (R) genes, which are often clustered in the genome and show a high degree of genetic variation. Here, we show that anArabidopsis thaliana R-gene cluster is also... more

Plant pathogen resistance is mediated by a large repertoire of resistance (R) genes, which are often clustered in the genome and show a high degree of genetic variation. Here, we show that anArabidopsis thaliana R-gene cluster is also subject to epigenetic variation. We describe a heritable but metastable epigenetic variant bal that overexpresses the R-like geneAt4g16890 from a gene cluster on Chromosome 4. The balvariant and Arabidopsis transgenics overexpressing theAt4g16890 gene are dwarfed and constitutively activate the salicylic acid (SA)-dependent defense response pathway. Overexpression of a related R-like gene also occurs in the ssi1(suppressor of SA insensitivity1) background, suggesting that ssi1 is mechanistically related to bal.

Staining of chromosome preparations of Chinese hamster-human hybrid cells and mouse-chimpanzee hybrids with alkaline Giemsa has yielded color differentiation of the interspecific chromosomes. Bicolor chromosomes, indicating apparent... more

Staining of chromosome preparations of Chinese hamster-human hybrid cells and mouse-chimpanzee hybrids with alkaline Giemsa has yielded color differentiation of the interspecific chromosomes. Bicolor chromosomes, indicating apparent translocations also are observed for each of these hybrids. The specific color differences observed provide a rapid means of recognizing and aiding in the identification of the interspecific chromosomes and apparent translocations in these somatic cell hybrids.

Coffee pulp is produced in large quantities, and its disposal can pollute the environment. However, the nutritional value and antioxidant content of coffee pulp make it a good option for animal feed. Therefore, the objective of this study... more

Coffee pulp is produced in large quantities, and its disposal can pollute the environment. However, the nutritional value and antioxidant content of coffee pulp make it a good option for animal feed. Therefore, the objective of this study was to determine the chemical composition, the phenolic compounds and the antioxidant capacity of coffee pulp using fresh (FCP), ensiled (ECP), and ensiled and sun-dried (EDCP) coffee pulp. The study design was completely randomized with three treatments (n=4). Dry matter (DM), crude protein (CP), ash, acid detergent fiber (ADF), neutral detergent fiber (NDF), lignin, phenolic compounds and antioxidant capacity were determined. Data were analyzed by analysis of variance, and means were compared with the Tukey test. The percentage of CP, NDF and ADF was higher in ECP and EDCP than in FCP. There were no changes in lignin content. Ensiling and sun drying did not decrease (P>0.05) caffeine or tannins. No differences were found in caffeic acid (2.031...

Patterns of variation in chromosomes, mitochondrial DNA and allozymes were assessed for two parthenogenetic (Lepidodactylus lugubris and Hemidactylus garnotii) and one sexual (H. frenatus) species of house gecko that have colonized remote... more

Patterns of variation in chromosomes, mitochondrial DNA and allozymes were assessed for two parthenogenetic (Lepidodactylus lugubris and Hemidactylus garnotii) and one sexual (H. frenatus) species of house gecko that have colonized remote Pacific Ocean islands. The aims were to test the assumed recency of colonization and to provide information on the amount and distribution of genetic variation. Lepidodactylus lugubris was found to have diploid and triploid clones, high heterozygosity and moderate diversity for allozymes, and only two common types of mtDNA. The common clones distinguished by genetic analysis were geographically widespread. Together the genetic data suggest multiple origins of L. lugubris, with multiple recent invasions of the Pacific Ocean islands. Hemidactylus garnotii had low genetic diversity for chromosomes, mtDNA and allozymes. In contrast, its sexual congener, H. frenalus, had unusually high levels of mtDNA diversity, with some widespread variants. The low level of mtDNA diversity in the parthogenetic species provides strong support for the assumption that these are recent colonists of Pacific Islands.

Microsatellite or simple sequence repeat (SSR) markers have wide applicability for genetic analysis in crop plant improvement strategies. The objectives of this project were to isolate, characterize, and map a comprehensive set of SSR... more

Microsatellite or simple sequence repeat (SSR) markers have wide applicability for genetic analysis in crop plant improvement strategies. The objectives of this project were to isolate, characterize, and map a comprehensive set of SSR markers for maize (Zea mays L.). We developed 1051 novel SSR markers for maize from microsatellite-enriched libraries and by identification of microsatellite-containing sequences in public and private databases. Three mapping populations were used to derive map positions for 978 of these markers. The main mapping population was the intermated B73 × Mo17 (IBM) population. In mapping this intermated recombinant inbred line population, we have contributed to development of a new high-resolution map resource for maize. The primer sequences, original sequence sources, data on polymorphisms across 11 inbred lines, and map positions have been integrated with information on other public SSR markers and released through MaizeDB at URL:www.agron.missouri.edu. The maize research community now has the most detailed and comprehensive SSR marker set of any plant species.

Many aspects of the mitotic cycle can take place independently in syncytial Drosophila embryos. Embryos from females homozygous for the mutation gnu undergo rounds of DNA synthesis without nuclear division to produce giant nuclei, and at... more

Many aspects of the mitotic cycle can take place independently in syncytial Drosophila embryos. Embryos from females homozygous for the mutation gnu undergo rounds of DNA synthesis without nuclear division to produce giant nuclei, and at the same time show many cycles of centrosome replication (Freeman et al. 1986). S phase can be inhibited in wild-type Drosophila embryos by injecting aphidicolin, in which case not only do centrosomes replicate, but chromosomes continue to condense and decondense, the nuclear envelope undergoes cycles of breakdown and reformation, and cycles of budding activity continue at the cortex of the embryo (Raff and Glover, 1988). If aphidicolin is injected when nuclei are in the interior of the embryo, centrosomes dissociate from the nuclei and can migrate to the cortex. Pole cells without nuclei then form around those centrosomes that reach the posterior pole (Raff and Glover, 1989); the centrosomes presumably must interact with polar granules, the materna...

The manual system of preparing time table in colleges with large number of students is very time consuming and usually ends up with various classes clashing either at same room or with same teachers having more than one class at a time.... more

The manual system of preparing time table in colleges with large number of students is very time consuming and usually ends up with various classes clashing either at same room or with same teachers having more than one class at a time. These are just due to common human errors which are very difficult to prevent in processes such as these. To overcome these problems people usually taking the previous year's timetable and modifying it but still it is a tedious job to in cooperate changes. To overcome all these problems we propose to make an automated Application. The Application will take various inputs like details of students, subjects and class rooms and teachers available, depending upon these inputs it will generate a possible time table, making optimal utilization of all resources in a way that will best suit any of constraints or college rules. List of subjects may include electives as well as core subjects. The case is similar to schools and other educational institutions. So our aim is to develop a general purpose which can efficiently generate optimal solutions.

Preferential chromosome association at metaphase I has been analyzed and compared in autotetraploid cells obtained by colchicine treatment of hybrid diploid rye plants with different degrees of chromosomal divergence between homologs. The... more

Preferential chromosome association at metaphase I has been analyzed and compared in autotetraploid cells obtained by colchicine treatment of hybrid diploid rye plants with different degrees of chromosomal divergence between homologs. The tendency to identical over homologous, but not identical, pairing preferences detected when homologous partners are contributed by less related parental lines indicates that chromosome differentiation may play an important role on preferential pairing behavior of polyploids. However, associations between more similar (identical) partners are not always favored, thus suggesting that additional factors must be considered. Other hypotheses for explaining pairing preferences in competitive situations are discussed. No clear relationship has been found between multivalent frequencies at metaphase I and chromosome differentiation between homologs or preferential pairing behavior. Therefore evolutionary divergences among related genomes should be carefull...

Embryogenic cell suspension (ECS) cultures were established from hypocotyl segments-derived embryogenic calli of Egyptian cumin ( Cuminum cyminum L. cv. 'Balady'), the sole popular commercial variety of cumin in Egypt. After culture for... more

Embryogenic cell suspension (ECS) cultures were established from hypocotyl segments-derived embryogenic calli of Egyptian cumin
(
Cuminum cyminum
L. cv. 'Balady'), the sole popular commercial variety of cumin in Egypt. After culture for 2-4 months on B5 solid
callus induction medium supplemented with 0.88 mg/l 2,4-dichlor
ophenoxyacetic acid (2,4-D) plus 0.86 mg/l kinetin (Kin), merist
ematic
globules and yellow, friable ECS were induced from the explants of seedling hypocotyls. ECS were initiated from these embryogen
ic calli
in the same liquid B5 callus induction medium. After selection of small aggregates and single cell cultures at 15-day intervals
for 2
months, homogeneous and yellow ECSs, composed of single cells, small cell aggregates were established. Based upon the growth
dynamic of ECS, the entire old medium was replaced weekly by an equal volume of fresh medium. Plating of ECS (1-12 months old)
on 3
different solid B5 media (B5
Z
,
B5
K
and B5
ZK
) resulted in the induction and development of approximately six, two and six compact,
organized calli/ml of ECS, respectively. Variation in callus induction ability was influenced by the time elapsed after subcult
ures and the
medium used. Plated cells responded best 5 days after subculture; 11 calli/ml ECS were obtained while 8.2 shoots/ml ECS regener
ated on
B5
ZK
medium containing 0.065 mg/l Zeatin + 0.021 mg/l Kin. A total of 230 plants were obtained, ~75% of which were survived under
ex-vitro
conditions, flowered and produced normal seeds. Chromosome number of suspension cells ranged from 12-28 chromosomes, and
the majority of cells (51%) had a normal (14) chromosome number,
which was also observed in 63% of tested root tip cells of reg
enerated
plants

This book presents a comprehensive introduction to the principles of human cytogenetics and provides examples of their applications, especially those that are important in diagnostic and preventive medicine. The authors have each worked... more

This book presents a comprehensive introduction to the principles of human
cytogenetics and provides examples of their applications, especially those
that are important in diagnostic and preventive medicine. The authors have each
worked in human cytogenetics for more than 40 years and have witnessed firsthand
the enormous strides made in the field during this time . The many advances
made since the third edition of this book reflect the rapidly growing application
of molecular biological techniques and concepts by human cytogeneticists.
Insertion of transposable elements, genomic imprinting, and expansion of trinucleotide
repeats are only a few of the important cytogenetic mechanisms that
have been discovered and shown to playa role in producing disease phenotypes.
Molecular cytogenetic methods have taken center stage in cancer studies with
the demonstration that cancers arise by chromosomal mechanisms such as gene
amplification, oncogene activation by chromosome rearrangement, ectopic
recombination leading to loss of heterozygosity, and multiple mechanisms
leading to genome destabilization.
We present a comprehensive and relatively brief overview of the principles of
cytogenetics, including the important new disease mechanisms previously men tioned.
Examples are chosen that illustrate these principles and their application,
thus preparing the reader to understand the new developments that constantly
appear in the laboratory, the clinic , and the current literature of this very active
field. At many points in the book, important unsolved problems in cytogenetics
are mentioned with suggestions of how a solution might be sought, which acts
as a stimulus to the reader to come up with his or her own suggestions . The
book should be particularly useful for physicians who want to keep up with new
developments in this field and students interested in a career in medical genetics
or genetic counseling. It could easily serve as a text for a one-semester college
or graduate-level course in human cytogenetics, or, with some supplementation,
a course in general cytogenetics.
In this edition , the text has been extensively reorganized and almost completely
rewritten to incorporate essential insights from cell and molecular genetics,
along with other advances in cytogenetics, and to present them in a
systematic way. Examples have been chosen that not only emphasize the underlying
principles but also illustrate the growing clinical importance of molecular
cytogenetics. Most of the tables and the majority of the figures are new, and virtually
all are based on studies of human chromosomes. We are grateful to the
colleagues and copyright holders who have generously permitted the use of their
published and unpublished figures and tables .
vi
Detroit, Michigan
Madison, Wisconsin
Orlando J Miller
Eeva Therman