High-frequency somatic embryogenesis, nuclear DNA estimation of milkweed species (Asclepias latifolia, A. speciosa, and A. subverticillata), and genome size stability of regenerants

Ribbon worms (phylum Nemertea) are among several animal groups that have been overlooked in past studies of genome-size diversity. Here, we report genome-size estimates for eight species of nemerteans, including representatives of the major lineages in the phylum. Genome sizes in these species ranged more than fivefold, and there was some indication of a positive relationship with body size. Somatic endopolyploidy also appears to be common in these animals. Importantly, this study demonstrates that both of the most common methods of genome-size estimation (flow cytometry and Feulgen image analysis densitometry) can be used to assess genome size in ribbon worms, thereby facilitating additional efforts to investigate patterns of variability in nuclear DNA content in this phylum.

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High frequency plant regeneration in Indian Siris via cyclic somatic embryogenesis with biochemical, histological and SEM investigations

Industrial Crops and Products ◽

10.1016/j.indcrop.2015.07.060 ◽

2015 ◽

Vol 76 ◽

pp. 623-637 ◽

Cited By ~ 16

Author(s):

Taiba Saeed ◽

Anwar Shahzad

Keyword(s):

Somatic Embryogenesis ◽

Plant Regeneration ◽

High Frequency

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

Journal of Crustacean Biology ◽

10.1093/jcbiol/ruab043 ◽

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.

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