Germ Line — Soma Differentiation
W. Hennig
2013-ж. июн. · Results and Problems in Cell Differentiation 13-китеп · Springer Science & Business Media
Электрондук китеп
196
Барактар
reportРейтинг жана сын-пикирлер текшерилген жок Кеңири маалымат
Учкай маалымат
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.
Бул электрондук китепти баалаңыз
Оюңуз менен бөлүшүп коюңуз.
Окуу маалыматы
Смартфондор жана планшеттер
Android жана iPad/iPhone үчүн Google Play Китептер колдонмосун орнотуңуз. Ал автоматтык түрдө аккаунтуңуз менен шайкештелип, кайда болбоңуз, онлайнда же оффлайнда окуу мүмкүнчүлүгүн берет.
Ноутбуктар жана компьютерлер
Google Play'ден сатылып алынган аудиокитептерди компьютериңиздин веб браузеринен уга аласыз.
eReaders жана башка түзмөктөр
Kobo eReaders сыяктуу электрондук сыя түзмөктөрүнөн окуу үчүн, файлды жүктөп алып, аны түзмөгүңүзгө өткөрүшүңүз керек. Файлдарды колдоого алынган eReaders'ке өткөрүү үчүн Жардам борборунун нускамаларын аткарыңыз.
