Germ Line — Soma Differentiation
W. Hennig
2013. g. jūn. · Results and Problems in Cell Differentiation 13. grāmata · Springer Science & Business Media
E-grāmata
196
Lappuses
reportAtsauksmes un vērtējumi nav pārbaudīti. Uzzināt vairāk
Par šo e-grāmatu
One of the oldest problems in developmental biology is the differentiation between germ line and somatic cells. The continuity of germ line cells between subsequent generations of multicellular organisms was first suggested by Owen, and later elaborated by A. Weismann to his famous germ line theory. His additional assumption that cellular differentiation was based on a differential representation of the genetic material in somatic cells was soon disproved. In some, apparently exceptional, cases, however, such differences in the genetic material between germ line and somatic cells were discovered. The best-known example is the nematod Ascaris. Boveri discovered and studied the fundamental differences in the karyotypes of germ line and soma of Parascaris equorum. Later, similar situations were found in some other organisms. However, in particular the work ofSpemann demonstrated that cellular differentiation in general is not accompanied by fundamental changes of the genetic material. Subsequently, the relatively few examples of germ line-soma differences achieved by chromatin elimination processes have been considered as a curiosity. Experimental studies have been essentially restricted to Ascaris species and to the pioneering cytological studies of chromatin elimination by S. Beermann. Despite the large proportions of the genome involved in chromatin elimina tion, our knowledge of this process is still very restricted. In particular the biological meaning of this differentiation process is entirely obscure. In this context one must, however, consider that also for the majority of DNA sequences in eukaryotic genomes the biological relevance is unclear.
Novērtējiet šo e-grāmatu
Izsakiet savu viedokli!
Informācija lasīšanai
Viedtālruņi un planšetdatori
Instalējiet lietotni Google Play grāmatas Android ierīcēm un iPad planšetdatoriem/iPhone tālruņiem. Lietotne tiks automātiski sinhronizēta ar jūsu kontu un ļaus lasīt saturu tiešsaistē vai bezsaistē neatkarīgi no jūsu atrašanās vietas.
Klēpjdatori un galddatori
Varat klausīties pakalpojumā Google Play iegādātās audiogrāmatas, izmantojot datora tīmekļa pārlūkprogrammu.
E-lasītāji un citas ierīces
Lai lasītu grāmatas tādās elektroniskās tintes ierīcēs kā Kobo e-lasītāji, nepieciešams lejupielādēt failu un pārsūtīt to uz savu ierīci. Izpildiet palīdzības centrā sniegtos detalizētos norādījumus, lai pārsūtītu failus uz atbalstītiem e-lasītājiem.
