A developmental analysis of periodic albinism in the amphibian Xenopus laevis

The periodic albino of Xenopus laevis displays a transitory presence of black melanin pigment in the embryo but looses this during tadpole development. This mutation, involving a recessive allele, affects melanogenesis in dermal melanophore pigment cells. It has been suggested that the mutation is intrinsic to the melanophore cell itself or, alternatively, reflects malfunction in the neuroendocrine system that regulates melanophore cell function. This latter system, involving pituitary melanotrope cells which produces α-melanophore stimulating hormone (α-MSH), is responsible for stimulating the production and dispersion of melanin pigment in dermal melanophores. The purpose of the present study was to determine to which degree the albinism is intrinsic to the melanophore or involves neuroendocrine malfunction. Experiments involved transplantation of presumptive melanophores from wild-type to albino embryos, and vice versa, immunocytochemical analysis of the albino neuroendocrine system and the creation of wild-type/albino parabiotic animals to determine if the neuroendocrine system of the albino can support melanotrope cell function. We show that the albino has a functional neuroendocrine system and conclude that the defect in the albino primarily affects the melanophore cell, possibly rendering it incapable of responding to α-MSH. It is also apparent from our results that in later stages of development the cellular environment of the melanotrope cell does become important to its development, but the nature of the critical cellular factors involved remains to be determined.     

Mikroglia und Pericyten als Transformationsformen der Blut-Monocyten mit erhaltener Proliferationsfähigkeit

Summary A report is made of the experimental investigations concerning the problems of the increase of microglia by proliferation only or by invasion of mononuclear blood cells. If an invasion could be demonstrated, we wanted to find out, whether monocytes or lymphocytes transform into microglia. Moreover the position of pericytes should be clarified.—An increase of migroclia experimentally could be made by stab-would, cold-lesion, and herpes simplex-encephalitis. The non-specific-esterases (-naphthyl-acetate-esterase, naphthol-AS-d-chloracetate-esterase) which were demonstrable in blood-monocytes of rabbits only and not in the cytoplasm of lymphocytes, was demonstrated in brain sections using a combined autoradiographical-enzyme histochemical technique.—After the transfusion into rabbits of mononuclear blood cells which were labelledin vivo by³H-thymidine orin vitro by³H-cytidine as well as by the technique of irradiated parabiosis in rats we can presume that a great number of microglia and pericytes in experimental brain damage in rabbits and rats derive from blood monocytes. Beside this heteroplastic increase of mesenchymal cells in the brain a (homoplastic) proliferation of the local microglia and pericytes was demonstrable.

Ein Teil der Ergebnisse wurde auf der Deutsch-Englischen Neuropathologentagung, Heidelberg 1971, vorgetragen.     

连体动物模型的应用

连体动物模型是通过外科手术的方式将两只动物连接起来,在伤口处发生血管再通而形成共享的循环系统,最终实现细胞和可溶性因子的交换。是一个研究循环因素影响组织器官功能的动物模型。利用异龄连体动物模型,可以观察到青年内环境影响老年小鼠的衰老表型,恢复某些衰老器官的功能;利用同龄连体模型,可以观察到相对健康的内环境对病理生理状态产生的影响。     

异时连体共生对小鼠椎旁肌肉衰老退变的影响

目的 :通过异时连体共生(heterochronic parabiosis,HP)模型检测年轻小鼠血液循环环境对年老小鼠脊柱椎旁肌肉的影响。方法:选择4月龄的年轻小鼠及18月龄年老雌性小鼠,通过手术建立年轻和年老小鼠同时(isochronic parabiosis,IP)、异时连体共生模型。连体8周后将小鼠分成同时连体年轻小鼠组(youngisochronic,YI),异时连体年轻小鼠组(young heterochronic,YH);同时连体年老小鼠(old isochronic,OI)和异时连体年老小鼠组(old heterochronic,OH)4组,解剖并提取椎旁肌肉。通过流式细胞仪吸光度检测各组椎旁肌肉糖胺聚糖(glycosaminoglycans,GAG)及各组DNA的含量,提取肌肉组织蛋白行蛋白印痕(Western blot)检测衰老基因P53、P21、P16及自噬基因LC3、金属蛋白酶MMP13基因的表达。取脊柱椎旁肌肉组织进行组织免疫荧光(immunofluorescence,IF)检测Aggrecan、P16及炎症因子IL8的表达差异性。结果:GAG定量分析显示YI、YH、OH、OI各组分别为2.91±0.17、2.01±0.21、2.23±0.36、1.18±0.09,其中YI与YH、OH与OI组之间有统计学差异(P0.05);通过IF检测Aggrecan表达呈下降趋势,YI、YH、OH、OI各组分别为717.25±64.44、611.59±28.45、683.04±17.95、570.34±31.81,其中OH与OI组间有统计学差异(P0.05),YI与YH组间无统计学意义(P0.05);LI8基因表达YI、YH、OH、OI各组分别为494.20±28.35、561.62±44.72、602.35±45.57、726.36±58.40;P16基因表达YI、YH、OH、OI各组分别为701.30±27.21、695.92±31.06、754.82±25.78、815.54±24.70,有上升趋势但YI与YH、OH与OI组间无明显差异(P0.05)。Western blot检测自噬基因LC3Ⅱ/Ⅰ蛋白表达呈下降趋势YI、YH、OH、OI各组分别为0.39±0.09、0.29±0.05、0.26±0.04、0.16±0.01;衰老基因P21蛋白表达YI、YH、OH、OI各组分别为1.09±0.23、1.32±0.12、1.54±0.03、1.86±0.06;金属蛋白酶MMP13蛋白表达YI、YH、OH、OI组分别为0.59±0.11、0.68±0.13、0.88±0.15、1.11±0.18。在LC3Ⅱ/Ⅰ、P21、MMP13表达中,YI与YH组间无明显差异性(P0.05),OH与OI组间有统计学差异(P0.05)。结论:全身血液循环可以影响椎旁肌肉退变,年轻血液环境可以延缓年老小鼠脊柱椎旁肌肉衰老退变。     

联体共生诱导大鼠心脏移植免疫耐受的实验研究

目的　通过联体共生模型 ,建立供、受者嵌合体 ,探讨嵌合体与免疫耐受的关系。方法　纯系雄性DA(RT1a)大鼠为供者 ,Lewis(RT11)大鼠为受者 ,随机分成 3组 ,每组供、受者各 15只。Ⅰ组 (未处理组 ) :仅行DA到Lewis大鼠的腹部心脏移植 ,手术前后不作任何处理。Ⅱ组 (环磷酰胺组 ) :DA到Lewis大鼠的心脏移植前后分别经腹腔注射环磷酰胺 80mg/kg。Ⅲ组 (联体组 ) :0d :供、受者大鼠腹腔注射环磷酰胺 80mg/kg ;第6d :供、受者联体 ;第 16d :联体大鼠腹腔注射环磷酰胺80mg/kg ;第2 1d :分开联体 ,行DA到Lewis大鼠的心脏移植。观察各组移植心存活时间 ,供心病理学改变 ,供、受者间的混合淋巴细胞反应 (MLR)。结果　Ⅲ组形成了稳定的供、受者嵌合体 ,供心平均存活时间为 :(76 .33± 10 .71)d ,较Ⅰ组 (7.17± 1.17)d、Ⅱ组 (8.5 0± 1.87)d显著延长 ,差异有显著性 (P <0 .0 1) ;Ⅲ组的供心仅见少量炎性细胞浸润 ;供、受者间MLR较正常对照组显著降低 ,差异有显著性 (P <0 .0 1)。结论　联体共生可形成稳定的外周和中枢嵌合体 ,嵌合体在同种心脏移植的免疫耐受中起重要作用。     

Successful treatment of murine autoimmune cholangitis by parabiosis: Implications for hematopoietic therapy

There is a significant unmet need in the treatment of primary biliary cirrhosis (PBC) despite significant data on the effector pathways that lead to biliary duct damage. We focused attention on a murine model of PBC, the dominant negative transforming growth factor β receptor II (Tg) mice. To further define the pathways that lead to biliary pathology in these mice, we developed Tg mice deleted of CD4 cells (CD4^−/−Tg).Interestingly, these mice developed more severe cholangitis than control Tg mice. These mice, which lack CD4 cells, manifested increased levels of IFN-γ produced by effector CD8 cells. It appears that increased cholangitis is due to the absence of CD4 Treg cells. Based on these data, we parabiosed CD4^−/−Tg mice with established disease at 8–9 weeks of age with C57BL/6 control mice. Such parabiotic “twins” had a significant reduction in autoimmune cholangitis, even though they had established pathology at the time of surgery. We prepared mixed bone marrow chimera mice constructed from CD4^−/−Tg and CD8^−/− mice and not only was cholangitis improved, but a decrease in terminally differentiated CD8⁺ T effector cells in the presence of wild type CD4 cells was noted. In conclusion, “correcting” the CD4 T cell subset, even in the presence of pathogenic CD8 T cells, is effective in treating autoimmune cholangitis.     

Effects of parabiosis of obese with diabetes and normal mice

Summary Parabiosis of obese (ob/ob) with diabetes (db ^2J/db^2J) mice caused the obese partner to become hypoglycemic, to lose weight and to die of starvation, while no abnormal changes were observed in the diabetes partner. The striking similarity of this response to that observed in normal mice in parabiosis with diabetes mice suggests that obese mice are like normal mice in having normal satiety centers sensitive to the satiety factor produced by the diabetes partner. In contrast, parabiosis of obese with normal mice is a fully viable combination suggesting that the obese partner does not produce sufficient satiety factor to turn off the normal partner's eating drive. However, obese mice in parabiosis with normal mice gain weight less rapidly and eat less than obese mice in parabiosis with obese mice. These observations suggest that some humoral factor is provided by the normal partner that regulates food consumption in the obese partner. To explain the identical obese-hyperglycemic syndromes produced by these two unrelated and separate genes when on identical genetic backgrounds, it is postulated that the obese mouse is unable to produce sufficient satiety factor to regulate its food consumption, whereas the diabetes mouse produces satiety factor, but cannot respond to it because of a defective satiety center.Supported in part by NIH Research Grant AM 14461 from the National Institute of Arthritis, Metabolism, and Digestive Diseases and by an allocation from the South Waite Foundation.The Jackson Laboratory is fully accredited by the American Association for Accreditation of Laboratory Animal Care.     

The use of parabiosis for investigating the mechanism of transplantation tolerance in bone marrow chimeras induced by total lymphoid irradiation

The mechanism of transplantation tolerance in total lymphoid irradiation (TLI)-induced semiallogeneic bone marrow chimeras without clinical evidence of graftversus-host disease (GVHD) was investigated using the technique of surgical parabiosis. When held in parabiosis with normal BALB/c mice, BALB/c (BALB/cxC57BL/6) F1 (BALBF1) chimeras survived 7–9 days, significantly (P<0.001) shorter than the 12–19 day survival of normal F1 hybrids kept in parabiosis with normal BALB, and in contrast to indefinite (>200 days) survival of syngeneic BALB parabiotic partners. When C57 skin grafts were placed on BALB mice held in parabiosis with BALBF1 chimeras, C57 skin grafts survived 50–60 days, in contrast to 10–14 days in normal BALB recipients (P<0.001). Lethal GVHD, induced in sublethally irradiated F1 recipients by 10⁷ BALB spleen cells, could not be delayed or prevented by cotransfer of 10⁷ to 30x10⁷ tolerant BALB spleen cells obtained from stable BALBF1 chimeras. GVHD reactivity of BALB spleen cells isolated from BALBF1 chimeras tolerant of C57 could not be recovered by depletion of Lyt 2 cytotoxic suppressor cells. Taken together, in the absence of suppressive capacity by suppressor cells, these data support functional clonal deletion as the primary mechanism responsible for the maintenance of unresponsiveness to host alloantigens in TLI-induced semiallogeneic chimeras, since no protection against induction of GVHD could be documented in vivo. The transfer of relative unresponsiveness to the host's alloantigens to the normal BALB partner of BALB/BALBF1 parabiotic pairs following sparation is also compatible with the latter conclusion, although transfer of suppressor cells capable of blocking rejection but not GVHD against the same alloantigens cannot yet be formally excluded.     

Low level of mixing of partner cells seen in extrathymic T cells in the liver and intestine of parabiotic mice: its biological implication

c-kit⁺ stem cells have recently been found in the liver and intestine of adult mice. We examined whether such stem cells give rise to extrathymic T cells in these organs in situ. To this end, we used parabiotic B6.Ly5.1 and B6.Ly5.2 mice, i.e. mice sharing the circulation. The origin of lymphocytes was identified by anti-Ly5.1 and anti-Ly5.2 monoclonal antibodies in conjunction with immunofluorescence assays. Lymphocytes in the blood, spleen, lymphnodes and liver had become a half-and-half mixture of Ly5.1⁺ and Ly5.2⁺ cells in both individuals by day 14. However, this level of mixing decreased in extrathymic T cells in the liver ( i.e. NK T cells) and intestine by day 14 and thereafter. The same was observed in T cells of the thymus. The data from immunohistochemical staining supported the results of immunofluorescence assays for suspension cells. The present results raise the possibility that extrathymic T cells in the liver and intestine may arise from their own pre-existing precursor cells, possibly from their own stem cells. Another important finding was that the composition pattern of lymphocyte subsets in one individual was quite similar to that in its partner at various sites. This result was interpreted to mean that only selected partner cells migrate to specific sites in the other partner individual.