23 Matching Annotations
  1. Sep 2020
    1. For table 2, how do they know their nonenucleated controls aren't just using their normal nucleus? Actually, I think that's probably what they're expecting because they're working much better and that makes more sense for a control.

    2. I was hoping they'd double check their fancy new karyoplast fusion technique with some good old microinjection

    3. The idea that later stage nuclei are more fragile or at least more difficult to extract is something Gurdon 1962 talks about

    4. Their method for testing the cause of the failure of transplanted nuclei from more developed cells was clever. Was it the nucleus, or was it the cytoplasm?

    5. At table 1, this is what Sean was talking about. Why not use equal numbers of each donor?

    6. So can two cell nuclei not progress past blastocyst? It sounds like there was some big issue like each cell no longer contains Weismann's nuclear determinants past the 2 cell stage. This worked in frogs, so what's different in mice?

    1. These results show that a nucleus can promote the formation of a differen-tiated intestine cell and at the same time contain the genetic informationnecessary for the formation of all other types of differentiated somatic cell ina normal feeding tadpole. It is concluded that the differentiation of a cell cannotbe dependent upon the incapacity of its nucleus to give rise to other types ofdifferentiated cell

      Wahoo this is what I've been looking for

    2. enucleatedrecipient eggs

      They're enucleated now but they didn't enucleate in the 1958 experiment?

    3. The third possibilityis that the genetic information provided by a nucleus is entirely dependent onits cytoplasmic environment at any one time; in this case a nucleus would neverundergo any stable changes having a qualitative effect on its function.

      I think this is it more or less. Hormones and other signals are what tell the nucleus which genes to express

    4. nucleartransplantation experiments seem to be consistent with the view that stablechanges restricting the developmental capacity of nuclei are not essential forcellular differentiation to take place

      Yea so this is saying the nucleus and DNA doesn't have to change for a cell to differentiate

    5. hese experiments therefore show that a nucleus can be re-sponsible for the formation of an intestinal epithelium cell and at the same timepossess the capacity to form other kinds of differentiated cells

      So I think they're saying that all cells (at least all epithelial cells) have the DNA to differentiate into any type of cell, they had just happened to become epithelial cells. I don't think they mean that only 7% or whatever of them contain the right genetic material

    6. It has been clearly shown that about 7 per cent, of the total number oftransplanted intestine nuclei have the genetic information required to formnormal feeding tadpoles.

      So do the others not have that genetic material? Or do they just not express the right genetic material for some reason?

    7. Thus, if a transplanted nucleus supports the development ofa feeding tadpole, this is regarded as showing that it possessed the genetic in-formation required for this when it was present in the donor cell, and did notacquire this information only after transplantation.

      this is the big thing I'm taking out of this paper, but maybe that's just because this is what I'm looking for

    8. The effect ofmaking serial transfers is to transplant the mitotic products of a nucleus intoseveral different recipient eggs, so that at least some of these are of good qualityand therefore demonstrate the real developmental capacity of the originalsomatic nucleus

      It would be helpful to see percent of viable unsubstituted, fertilized eggs to see how that percent compares. If the rate were similar to percent of viable substituted eggs, that would support the idea that its a crappy egg's fault.

    9. Thus thepresence of a feeding tadpole among any of the transplant-embryos derivedfrom a nucleus shows that the nucleus had the genetic information requiredfor this before transplantation, even though the first-transfer embryo as wellas most of the serial-transfer embryos may have been abnormal

      This is what I've been waiting for

    10. Second, the abnormality of the first-transfer embryo might be due to some non-genetic cause such as poor egg quality

      I'd guess this way. I was wondering if issues that prevented a nucleus from growing well in its first implantation but a nucleus from that failed embryo could result in a successful transfer could include something like poor egg quality or failure of the nucleus to get comfortable in the cell somehow

    11. in all 31 cases some of the serial-transfer embryos differentiated morenormally than the first-transfer embryo from whose nuclei they were derived

      Ok this makes more sense. I guess I just didn't understand what they were trying to say last paragraph

    12. partial blastulae in which an appreciable part of the surface area isuncleaved, never develop beyond the late blastula or very early gastrula stage.

      So on the serial transfer of a nucleus, it can't develop any further than it got on its first implantation? I don't follow that- I thought there was a technical difficulty with transferring the nucleus--but if it's done properly there shouldn't be any issues?

    13. Some experiments have been carried out in order to determinethe significance of these abnormalities and, in particular, whether the abnor-malities are due to a limited developmental capacity of the transplanted nucleior to other factors such as variation in technique

      I was wondering about this!

    14. 10 normal feeding tadpoles have been obtained from the trans-plantation of intestinal epithelium cell nuclei

      It worked! I had a hunch it would

    15. all those which developed beyond the blastula stage containedmarked nuclei, thus proving that they were derived from the transplanted nucleusand not from the egg nucleu

      We've talked about this; how do we know the nucleus in the cell is actually the transplanted one and not the natural one

    16. The donor cells used for these experiments were intestinal epithelium cellsof feeding tadpoles. This is the final stage of differentiation of many of theendoderm cells whose nuclei have already been studied by means of nucleartransplantation experiments in Xenopus

      So, If Gurdon is able to get the epithelium nuclei into an egg and it grows, it will show that it is not the DNA that changes, just how it's expressed

    17. whether the differentiation of cellsdepends upon a stable restriction of the genetic information contained in theirnuclei.

      I think it does--that's why DNA in cells are the same and yet all cells are clearly not the same