DNA levels in somatic and germ line cells of a freshwater crustacean, Mesocyclops edax

1995 ◽  
Vol 53 ◽  
pp. 924-925
Author(s):  
E. M. Rasch ◽  
G.A. Wyngaard
Keyword(s):  
Acetic Acid ◽  
Somatic Cell ◽  
Nuclear Dna ◽  
Germ Line ◽  
Internal Reference ◽  
Chromatin Diminution ◽  
Internal Reference Standard ◽  
Freshwater Crustacean ◽  
Mesocyclops Edax ◽  
Chromosome Regions

Chromatin diminution--the fragmentation and elimination of chromosome Regions--provides an unusual opportunity to study genomic reorganization during development. Some species of copepods regularly excise and discard large amounts of nuclear DNA from presumptive somatic cell lines during early cleavage stages . To study this phenomenon in M. edax we determined DNA-Feulgen levels for more than 5,600 individual nuclei from squash preparations of 30 female and 25 male adults collected from lakes in Nova Scotia, Virginia and Florida. Fixation in 3:1 methanol/acetic acid was followed by squashing individual specimens in 45% acetic acid, freezing each slide in liquid N2 and thawing in absolute ethanol before air drying. Each series of slides was stained with the feulgen reaction for DNA and measured with a Vickers M86 scanning and integrating microdensitometer at 560 nm, using chicken RBC nuclei as an internal reference standard of 2.5 pg DNA per cell. This allowed us to ask several questions: are there differences in genome size (1) among specimens from different collecting localities, (2) between females and males at any single locality, and (3) between cells of germ line and somatic cell lineages?

Analysis of DNA Levels During Gonomery in Early Cleavage Divisions of the Freshwater Copepod Mesocyclops Edax

1997 ◽  
Vol 3 (S2) ◽  
pp. 191-192 ◽  
Author(s):  
E.M. Rasch ◽  
G.A. Wyngaard
Keyword(s):  
Acetic Acid ◽  
Early Cleavage ◽  
Chromatin Diminution ◽  
Cleavage Division ◽  
Relative Contribution ◽  
Male Genome ◽  
Egg Carrying ◽  
Mesocyclops Edax ◽  
Chromosome Regions ◽  
Absolute Etoh

Gonomery, the separate grouping of maternal and paternal chromosomes during the first few mitoses following fertilization (Fig. 1) and chromatin diminution, the fragmentation and elimination of whole chromosome regions during specific stages of early cleavage in all primordial cells of the soma, occur in several species of copepods, ascarid nematodes, ciliated protozoa, Japanese hagfish 9 and a few other invertebrates. Because of the marked loss of DNA from all presumptive somatic cells by selective chromatin diminution during the 4th cleavage division in M. edax, it was of interest to determine DNA levels in chromosomes during gonomery in anaphases preceding diminution (Fig. 1). It was also important to estimate the DNA content of sperm as an index of the relative contribution by the male genome at fertilization in this species.Mature males and egg-carrying females were fixed in 3:1 methanol/acetic acid for 3-5 mins, swollen in 45% acetic acid for 2-3 mins, squashed, frozen in liquid N2 for coverslip removal, thawed in 2 changes of absolute ETOH and air dried.

DNA–Feulgen cytophotometric determination of genome size for the freshwater-invading copepod Eurytemora affinis

Genome ◽  
2004 ◽  
Vol 47 (3) ◽  
pp. 559-564 ◽  
Author(s):  
Ellen M Rasch ◽  
Carol Eunmi Lee ◽  
Grace A Wyngaard
Keyword(s):  
Somatic Cell ◽  
Genome Size ◽  
Dna Content ◽  
Nuclear Dna ◽  
Growth Characteristic ◽  
Nuclear Dna Content ◽  
Cell Nuclei ◽  
Chromatin Diminution ◽  
Eurytemora Affinis ◽  
Genomic Studies

Variation in nuclear DNA content within some eukaryotic species is well documented, but causes and consequences of such variation remain unclear. Here we report genome size of an estuarine and salt-marsh calanoid copepod, Eurytemora affinis, which has recently invaded inland freshwater habitats independently and repeatedly in North America, Europe, and Asia. Adults and embryos of E. affinis from the St. Lawrence River drainage were examined for somatic cell DNA content and the presence or absence of embryonic chromatin diminution, using Feulgen–DNA cytophotometry to determine a diploid or 2C genome size of 0.6–0.7 pg DNA/cell. The majority of somatic cell nuclei, however, have twice this DNA content (1.3 pg/nucleus) in all of the adults examined and possibly represent a population of cells arrested at the G2 stage of the cell cycle or associated with some degree of endopolyploidy. Both suggestions contradict assumptions that DNA replication does not occur in adult tissues during the determinate growth characteristic of copepods. Absence of germ cell nuclei with markedly elevated DNA values, commonly found for species of cyclopoid copepods that show chromatin diminution, indicates that E. affinis lacks this trait. The small genome size and presumed absence of chromatin diminution increase the potential utility of E. affinis as a model for genomic studies on mechanisms of adaptation during freshwater invasions.Key words: copepod, genome size, DNA–Feulgen, calanoid, Eurytemora.

Chromatin diminution in the copepod Mesocyclops edax: diminution of tandemly repeated DNA families from somatic cells

Genome ◽  
2006 ◽  
Vol 49 (6) ◽  
pp. 657-665 ◽  
Author(s):  
Guy Drouin
Keyword(s):  
Dna Sequences ◽  
Germ Line ◽  
Somatic Cells ◽  
Repeated Sequences ◽  
Cyclopoid Copepod ◽  
Embryonic Cells ◽  
Repeated Dna ◽  
Chromatin Diminution ◽  
Mesocyclops Edax ◽  
Tandemly Repeated Dna

Chromatin diminution, i.e., the loss of selected chromosomal regions during the differentiation of early embryonic cells into somatic cells, has been described in taxa as varied as ciliates, copepods, insects, nematodes, and hagfish. The nature of the eliminated DNA has been extensively studied in ciliate, nematode, and hagfish species. However, the small size of copepods, which makes it difficult to obtain enough DNA from early embryonic cells for cloning and sequencing, has limited such studies. Here, to identify the sequences eliminated from the somatic cells of a copepod species that undergoes chromatin diminution, we randomly amplified DNA fragments from germ line and somatic line cells of Mesocyclops edax, a freshwater cyclopoid copepod. Of 47 randomly amplified germ line clones, 45 (96%) contained short, tandemly repeated sequences composed of either 2 bp CA-repeats, 8 bp CAAATAGA-repeats, or 9 bp CAAATTAAA-repeats. In contrast, of 83 randomly amplified somatic line clones, only 47 (57%) contained such short, tandemly repeated sequences. As previously observed in some nematode species, our results therefore show that there is partial elimination of chromosomal regions containing (CAAATAGA and CAAATTAAA) repeated sequences during the chromatin diminution observed in the somatic cells of M. edax. We speculate that chromatin diminution might have evolved repeatedly by recruitment of RNAi-related mechanisms to eliminate nonfunctional tandemly repeated DNA sequences from the somatic genome of some species.Key words: chromatin diminution, Mesocyclops edax, copepod, satellite DNA, hetorochromatin.

scholarly journals Ploidy level determination of Hedera (Araliaceae) with an emphasis on discussable species (Hedera hibernica)

Caryologia ◽  
2021 ◽  
Vol 74 (1) ◽  
pp. 109-116
Author(s):  
Fahimeh Fallah ◽  
Farrokh Ghahremaninejad
Keyword(s):  
Flow Cytometry ◽  
Genome Size ◽  
Nuclear Dna ◽  
Petroselinum Crispum ◽  
New Taxon ◽  
Internal Reference ◽  
Ploidy Levels ◽  
Internal Reference Standard ◽  
Significant Difference

Genome size is a helpful tool for circumscribing taxa at diverse taxonomic degrees (mostly species) and resolving intricate low-level taxonomies. The correct genome size in Hedera (Araliaceae) has long been discussed, and the ploidy levels of some taxa are still unclear. Twelve accessions of Hedera were measured via flow cytometry. Flow cytometry is a relatively rapid, inexpensive, and credible tool. Fresh leaves of Hedera samples and internal reference standard parsley (Petroselinum crispum) were stained with propidium iodide (PI). Flow cytometry measurements showed that for the accessions of 2CV (3.09 - 6.40 pg), the lowest amount of nuclear DNA was 3.09 pg for Hedera crebrescens (So), while the highest amount was 6.40 pg for H. hibernica “Hamilton,” representing a statistically significant difference. According to this study, the new taxon (H. crebrescens) is a diploid, though this taxon was previously considered H. hibernica (tetraploid).

Genome size in cyclopoid copepods (Copepoda: Cyclopoida): chromatin diminution as a hypothesized mechanism of evolutionary constraint

2021 ◽  
Vol 41 (3) ◽  
Author(s):  
Emilly Schutt ◽  
Maria Hołyńska ◽  
Grace A Wyngaard
Keyword(s):  
Genome Size ◽  
Life Histories ◽  
Nuclear Dna ◽  
Cell Lineage ◽  
Fundamental Property ◽  
Nuclear Dna Content ◽  
Evolutionary Constraint ◽  
Chromatin Diminution ◽  
Somatic Genome ◽  
Copepoda Cyclopoida

Abstract Genome size is a fundamental property of organisms that impacts their molecular evolution and life histories. The hypothesis that somatic genome sizes in copepods in the order Cyclopoida are small and evolutionary constrained relative to those in the order Calanoida was proposed 15 years ago. Since then, the number of estimates has almost doubled and the taxon sampling has broadened. Here we add 14 new estimates from eight genera of freshwater cyclopoids that vary from 0.2 to 6.6 pg of DNA per nucleus in the soma; all except one are 2.0 pg DNA per nucleus or smaller. This new sample adds to the pattern of genome size in copepods and is remarkably similar to the distribution on which the original hypothesis was based, as well as those of subsequently published estimates. Embryonic chromatin diminution, during which large portions of DNA are excised from the presomatic cell lineage, is reported in Paracyclops affinis (G.O. Sars, 1863). This diminution results in a somatic genome that is one half the size of the germline genome. When the sizes of the germline genomes carried in presomatic cells of cyclopoid species that possess chromatin diminution are considered, the prediminuted germline genome sizes of cyclopoid embryos overlap with the distribution of calanoid somatic genome sizes, supporting the hypothesis that chromatin diminution has functioned as a mechanism to constrain somatic nuclear DNA content in cyclopoid copepods. Geographically based variation in genome size among populations is also reviewed.

scholarly journals Determination of Organosulfides from Onion Oil

Foods ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 884 ◽  
Author(s):  
Maranda S. Cantrell ◽  
Jared T. Seale ◽  
Sergio A. Arispe ◽  
Owen M. McDougal
Keyword(s):  
Diethyl Ether ◽  
Steam Distillation ◽  
Extraction Efficiency ◽  
Agricultural Products ◽  
Gas Chromatography Mass Spectrometry ◽  
Diallyl Disulfide ◽  
Reference Standard ◽  
Internal Reference ◽  
Internal Reference Standard

Qualitative and semi-quantitative analysis of organosulfides extracted from oil obtained by steam distillation of yellow onions was performed by gas chromatography-mass spectrometry (GC-MS). The extraction efficiency of organosulfides from onion oil was evaluated across four solvents: dichloromethane; diethyl ether; n-pentane; and hexanes. Analysis of solvent extracted organosulfides by GC-MS provided qualitative results that support the use of dichloromethane over other solvents based on identification of 27 organosulfides from the dichloromethane extract as compared to 10 from diethyl ether; 19 from n-pentane; and 17 from hexanes. Semi-quantitative evaluation of organosulfides present in the dichloromethane extract was performed using diallyl disulfide as the internal reference standard. Three organosulfides were detected in the extract at ≥5 mg/kg; 18 organosulfides between 3–5 mg/kg; and six organosulfides at <3 mg/kg. The E/Z isomers of 1-propenyl propyl trisulfide were among the most prevalent components extracted from the onion oil across all solvents; and 3,6-diethyl-1,2,4,5-tetrathiane was among the most abundant organosulfides in all solvents except hexanes. The method described here for the extraction of organosulfides from steam distilled onion oil surveys common solvents to arrive at a qualitative and semi-quantitative method of analysis for agricultural products involving onions; onion oil; and secondary metabolites of Allium spp.

scholarly journals Can random mutation explain phenotypic variability?

2018 ◽  
Author(s):  
Víctor Alejandro Zapata Trejo
Keyword(s):  
Gene Expression ◽  
Somatic Cell ◽  
Germ Line ◽  
Phenotypic Variability ◽  
Random Mutation ◽  
Differentiated Cells ◽  
Undifferentiated Cells ◽  
Joint Evolution

The epigenome regulates the gene expression of all differentiated cells and indicates which specific genes must be transcribed. It is argued that the expression factors that act on specific genes of the somatic cell involved in a behavior also act on the transcription of the same genes in the most undifferentiated cells of the germ line. It is proposed how a probabilistic view of the random mutation can explain the evolution of the phenotypes and integrate all the evidence pointing to a joint evolution with the environment.

scholarly journals Can random mutation explain the phenotypic variability?

2018 ◽  
Author(s):  
Víctor Alejandro Zapata Trejo
Keyword(s):  
Gene Expression ◽  
Somatic Cell ◽  
Germ Line ◽  
Phenotypic Variability ◽  
Random Mutation ◽  
Differentiated Cells ◽  
Undifferentiated Cells

The epigenome regulates the gene expression of all differentiated cells and indicates which specific genes must be transcribed. It is argued that the expression factors that act on specific genes of the somatic cell involved in a behavior also act on the transcription of the same genes in the most undifferentiated cells of the germ line. It is proposed how a probabilistic view of the random mutation can explain the evolution of the phenotypes and integrate all the evidence pointing to a conjunct evolution with the environment.

The genetics of inherited cancers

2010 ◽  
pp. 358-371
Author(s):  
Rosalind A. Eeles
Keyword(s):  
Somatic Cell ◽  
Cancer Cell ◽  
Germ Line ◽  
Cancer Predisposition ◽  
Cellular Growth ◽  
Germ Line Mutation ◽  
Cancer Predisposition Gene

All cancer can be termed ‘genetic’ as cancer is caused by somatic cell mutations (alterations in the DNA code), which result in abnormal cellular growth and/or proliferation. Most of these mutations are sporadic (only occurring in the cancer cell), but some are due to the inheritance of a germ-line mutation in a cancer predisposition gene....

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