Approach to women with a previous child with a genetic disorder
Minakshi Rohilla in Recurrent Pregnancy Loss and Adverse Natal Outcomes, 2020
This test identifies common trisomies 13, 18, 21, and X/Y and nine other common microdeletion syndromes. A bacterial artificial chromosome is a sequence of DNA that has been incorporated into a bacterium to allow a large amount of the sequence of interest to be manufactured. Bacterial artificial chromosomes derived from each chromosomal region of interest are then immobilized on a bead, which then has three fluorochromes attached for quantifying the reaction. The sample DNA is then added and analyzed. It uses two probes per chromosome arm and three for each acrocentric chromosome and has been shown to be an accurate method of identifying trisomies [6]. As culture failure is not an issue, this test can be used on products of conception. Terminal duplication and deletion have a lower overall pickup rate and may not be suitable for this analysis.
Cytogenetics
Wojciech Gorczyca in Atlas of Differential Diagnosis in Neoplastic Hematopathology, 2014
A karyotype is a set of chromosomes from one cell. There are 46 chromosomes occurring in 23 pairs (Figure 6.1). Chromosomes are distinct bodies found in the nucleus of cells, best visible in the phase of the cell cycle called metaphase. Chromosomes are composed of protein and DNA, and hold the genetic information in the form of linear sequences of four bases (A, T, C, and G). The DNA sequence for a single trait is called a gene. Each chromosome contains a few thousand genes, which range in size from a few thousand bases up to 2 million bases. The first 22 pairs are labeled longest to shortest. The last pair are called the sex chromosomes, which are labeled X or Y. Females have two X chromosomes (XX), and males have an X and a Y chromosome (XY). Each chromosome has a short or p (petit) arm and long or q (next letter in the alphabet) arm, which are separated by a region known as the centromere. The centromere is a condensed part of chromosome that binds together two sister chromatids and constitutes the attachment site for spindle fiber during cell division. Types of chromosomes are presented in Figure 6.2. Each chromosome arm is further defined by numbering the bands (light and dark bands visible under the microscope after staining with various dyes); the higher the number, the further the area is from the centromere. The band width and the order of bands are specific for each chromosome and allow their identification.
Genetics and exercise: an introduction
Adam P. Sharples, James P. Morton, Henning Wackerhage in Molecular Exercise Physiology, 2022
Chromosomes have two arms and a central constriction which is termed the centromere. The short arm of a chromosome is denoted as p and the long arm as q. Each arm of the chromosome is subdivided into regions numbered consecutively from the centromere to the telomere which is the tip of each chromosome arm. Each band (i.e. the dark and light stripes of a chromosome seen in Figure 3.5) within a given region is identified by a number. With this nomenclature, it is possible to specify any chromosomal region by its “cytological address”. For example, chromosome 1 is composed of about 249 million (mega, M) DNA base pairs (Figure 3.6). 1p22 refers to chromosome 1, p arm, region 2, band 2. Since the sequence of the DNA bases of the entire human genome is now available, it is possible to specify a physical position on a given human chromosome in terms of the exact base number in a sequence ranging from one to millions. For instance, there are 4,300 genes encoded on chromosome 1. The gene KIF1B which encodes kinesin family member 1B codes for a motor protein that transports vesicles within cells. It is located on 1p36.22 and extends from 10.21 to 10.38 M bases of DNA.
Efflux in Gram-negative bacteria: what are the latest opportunities for drug discovery?
Published in Expert Opinion on Drug Discovery, 2023
Teresa Gil-Gil, Pablo Laborda, Luz Edith Ochoa-Sánchez, José Luis Martínez, Sara Hernando-Amado
As previously mentioned, RND efflux pumps are composed by three proteins (Figure 1): an inner membrane protein, an outer membrane protein, and a periplasmic protein [65,66]. The large majority of them are housekeeping determinants encoded in the bacterial chromosome and present in all (or most) strains of a given bacterial species. Although less frequently described, RND efflux pumps might also be found encoded in plasmids, therefore contributing to plasmid-mediated acquired resistance. For instance, OqxAB is a RND efflux pump, likely originated in the chromosome of Klebsiella pneumoniae [67], and encoded in plasmids carried by E. coli, Salmonella spp, Enterobacter aerogenes, Enterobacter cloacae, or Serratia marcescens, which presents a broad substrate specificity including nalidixic acid, chloramphenicol, olaquindox, benzalkonium chloride, fluoroquinolones, nitrofurantoin, sodium dodecyl sulfate, and trimethoprim [67–75].
Improving protein glycan coupling technology (PGCT) for glycoconjugate vaccine production
Published in Expert Review of Vaccines, 2020
Jennifer Mhairi Dow, Marta Mauri, Timothy Alexander Scott, Brendan William Wren
An important consideration when using PGCT is the cloning of a genetic construct capable of expressing the components needed to produce the target glycan in the bacterial host. Ideally, the genes required will be found in the native bacterial chromosome as a single locus, which can be faithfully cloned into a suitable plasmid backbone for expression. Continued efforts into understanding the basic biology of glycosylation systems have also led to the development of synthetic operons with optimal enzymes for each stage of glycan expression, expanding the potential of using PGCT with glycans from organisms where the biosynthetic enzymes are not found in a single cluster [70]. This process is a dedicated glycoengineering technique in its own right, termed Glycan Expression Technology (GET) [71,72].
An overview on cyanobacterial blooms and toxins production: their occurrence and influencing factors
Published in Toxin Reviews, 2022
Isaac Yaw Massey, Muwaffak Al osman, Fei Yang
The ancient cyanobacteria organisms, noticeable in rocks dating from the first thousand million years of the earth’s history and belong to the kingdom monera (Prokaryota), division eubacteria and class cyanobacteria (Ressom et al.1994, Omidi et al.2018), are a type of photosynthetic bacteria that live in water surface. As cyanobacteria colonies occur in shallow water, they appear in the fossil record in sedimentary rocks deposited in shallow seas and lakes. Cyanobacteria colonies identified as stromatolites emerge in rocks as fossilized mushroom shapes and sheets. Falconer (2005) reported that the Gunflint chert was one of the best stromatolite formations known in Lake Erie. It is of interest cyanobacteria was shown to possess a single circular chromosome completely sequenced in several species, plasmids and small circular strands of DNA (Schwabe 1988, Kaneko et al.1996). Whitton and Potts (2000) found that the chlorophyll-a and pigment phycocyanin observed in cyanobacteria photosynthetic membranes were responsible for the characteristic blue-green color of the many species. Pigments such as carotenoids and phycoerythrin which give a strong red color to some species may also be present (Bryant 1994).
Related Knowledge Centers
- Cell Division
- DNA
- DNA Condensation
- Eukaryote
- Genome
- Histone
- S Phase
- Chaperone
- Transcriptional Regulation
- Metaphase