Wilhelm Roux Archiv Fur Entwicklungsmechanik Der Organismen最新文献

In order to specify the role of skin and internal tissues in limb regeneration, we have replaced stump skin by skin from one side or from two opposite sides of the limb or from the flank. 1. After transplantation of limb skin, from one side regenerates are partially abesnt, normal, or multiple. Experimental variations were 90‡ rotation of the proximo-distal axis of the skin, proximo-distal heterogeneity in the grafted skin and the introduction of a unique quality (e.g. dorsal quality) in the grafted skin at the level of amputation. After a critical analysis only the third variations helps towards an explanation of the results. 2. After transplantation of limb skin from two opposite sides of the limb regenerates are normal or multiple. 3. After transplantation of back skin regeneration are normal or absent. To explain the results obtained after limb skin transplantation we make the following two suggestions: a) The development of principal or supernumerary morphogenetic centers requires contact between the tissues of the two opposite sides. The tissues may be of the same character (skin or internal tissue) or may be different (skin and internal tissue). b) Antero-posterior and dorso-ventral gradients are present in both skin and internal tissues. Either one or the other type of tissue can direct the pattern of morphogenesis and give rise to asymmetry of the regenerate. When only one of them has a predominant morphogenetic influence, regenerates may be either normal or partially absent. When skin and internal tissues have equivalent morphogenetic influences, a contact between skin from one side and internal tissues from the opposite side would lead to the development of supernumerary formations.

The growth of the eye inAeshna cyanea has been studied by several experiments involving removal, regeneration and heterotopic grafts.The results show that the ommatidia do not develop from any stemcells that are permanent during the whole larval life. In fact the ommatidia grow by progressive recruitment of vertex epidermal cells on a level with a transitory zone (the eye budding zone) which progress through this epidermis.The eye budding zone regenerates only from the competent cells of the vertex in contact with differentiated ommatidia. Contact between ommatidia and epidermal cells from another area does not allow regeneration of the eye.The results are discussed and we propose an hypothesis explaining the larval eye's growth by means of these findings on its regeneration.

The purification of an actin-like protein from cricket egg yolk plasmodia by different selective extraction procedures, ammonium sulphate precipitation, ion exchange and immunoabsorption chromatography is described. Criteria of purity from analytical ultracentrifugation, SDS-disc electrophoresis, and immunoelectrophoresis are presented. Immunodiffusion analysis was used to control the success of the purification procedures.The molecular weight of the monomeric form is 60000±10%. Polymerization to pearl-chain aggregate structures occurs under different conditions in 0.1 M KCl in the presence of ATP. Vinblastine precipitation leads to similar structures. Possibly related structures and the possible rÔle of this protein in organizing movements in the plasmodial system are discussed.

If imaginal disks are transplanted into host flies that are kept on a protein-free sugar diet, their developmental processes come to a more or less reversibel standstill. This block is generally attributed to absence of cell divisions. Since cell division and DNA-synthesis are intimately coupled, we have used the polytene system of the salivary glands in order to study the question whether DNA-synthesis is possible in starved hosts.Nuclear DNA was determined with a modified Feulgen technique using the fluorescent dye BAO. Salivary glands of 72 hrs old male larvae were cultured in vivo and in vitro under various conditions (Fig. 2, Table 2, 3). In young starved hosts the nuclei can complete an already initiated S-phase, but further synthesis is blocked (Figs. 4, 5, 6). Older starved hosts are more effective in blocking DNA-synthesis. This block is largely reversible: in hosts that are transferred onto complete yeast food, the nuclei resume DNA-synthesis at a normal rate (Table 2, Kg. 5). Cytoplasmic differentiation as indicated by vacuolization of cultured gland cells has also been shown to be reversibly blocked in starved hosts (Fig. 7). Contrary to these findings starvation seemed to cause some irreversible alterations at the chromosomal level (Fig. 8).We suggest that in starved hosts protein synthesis is blocked and that this in turn will prevent initiation of new S-phases.

X-irradiation suppresses the morphogenetic power of limb tissues. Transplantation of non-irradiated tissues onto an irradiated limb allows, one to study the influence of the grafts qualities (viz. dorsal, ventral, anterior and posterior qualities) and the influence of the orientation of these grafts both on the degree of development and on the orientation of the regenerates. Either limb tissues or flank tissues were grafted. Either four or two or one quality were represented in the limb tissue grafts, while various orientations and locations were imposed upon them. 1. When four qualities (dorsal, ventral, anterior and posterior) were present in the grafts, regeneration was generally normal and complete. When two qualities (dorsal and ventral) were present the rate of normal or subnormal regeneration was 66%, with differentiation of all skeletal parts of the regnerarates. When only one quality (dorsal or ventral) was present regenerates were deficient or absent, and differentiation of carpus and zeugopod bones was never observed. At least two opposite qualities are necessary to allow regenerates to develop. 2. When we graft skin cuffs on irradiated limbs, the proximo-distal development of the regenerates depends only upon the proximo-distal level of the non-irradiated limb from which the graft was taken. 3. The orientation of regenerates is like that of the grafts. 4. 90‡ rotation of the skin has no influence on regeneration.

An implication of Crick's (1970, 1971) "source-sink" model of diffusion gradients is that the addition of sources along the length of a gradient would cause it to bulge away from linearity in the direction of the source. The activity of the budding region ofHydra viridis as a source of the diffusible inhibitors of head and of foot regeneration is investigated in this light, by placing multiple series of budding regions along the length of the inhibitory gradients of head and of foot regeneration previously described (Shostak, 1972, 1973).Samples of 30-50 animals were used to determine the frequencies of head and of foot regeneration at each graft border formed by grafting 2 to 5 gastric-plus budding regions in tandem, the distal one having a terminal apical head, and the proximal one part of a host animal having terminal basal peduncle and foot. These frequencies were compared to the corresponding frequencies at appropriate distances along the lengths of the inhibitory gradients, as computed from the linear equations for these gradients based on earlier work. The curves for the regeneration of heads and feet for animals with three or fewer additional budding regions deviate in the direction of greater inhibition, but do not differ significantly from the gradients on animals having only grafted gastric regions. The curves for animals with four additional budding regions, however, bulge out toward greater inhibition, and differ with statistical significance from the linear inhibitory gradients at the fourth graft border.The results show, therefore, that the budding region is a source of both the inhibitors of head and of foot regeneration also produced by the head and foot, respectively. The suggestion arises that the diffusible inhibitors produced by the morphogenetically active regions ofHydra have no effect on the normal homeostatic processes and budding occurring in these regions, but normally prevent regeneration that might otherwise occur during cellular turnover.

The location of the immature eye-antennal discs ofDrosophila melanogaster in embryos and young larvae was established by means of transplantation experiments. The developmental capacities of these immature discs was then investigated by implanting them into larvae which were ready to metamorphose, thus bypassing large portions of embryonic and larval development. Imaginal eye-antennal discs of embryos and first instar larvae are unable to synthesize eye pigments or secrete cuticle. The discs acquire the first detectable competence in the middle of the second instar, 32-36 hours after hatching, when the eye region of the disc becomes competent to synthesize ommochrome pigments and the rest of the disc becomes competent to secrete a thin untanned, transparent cuticle. Competence to synthesize pteridine pigments becomes evident later, 36-42 hours after hatching. The competence to produce specific bristle and hair patterns is acquired still later, 42-56 hours after hatching. Different regions of the eye-antennal disc acquire competence at different times and the acquisition of competence seems to occur in a proximo-distal sequence within both eye and antennal regions of the disc. In the eye region of the disc, the competence to produce proximal structures such as facets appears before the competence to produce ocelli. Similarly, in the antennal region of the disc, the competence to produce the first antennal segment appears before the competence to produce the third antennal segment or arista. Also, the acquisition of competence to produce a specific cuticular pattern occurs four to six hours earlier in the eye region of the disc than in the antennal region. It was also found that the temporal sequence in which differentiation events actually occur during adult development is similar to the temporal sequence in which specific competences are acquired by the growing immature eye-antennal discs.

Polar granules are organelles unique to the germ plasm of some insects and amphibians and are thought to be involved in germ cell formation. These granules inMiastor are similar to those inDrosophila andAmphibia both in their structure and in their continuous presence in the germ line cells throughout the life cycle of the organism. They are formed during oogenesis as dense masses of amorphous material at the posterior tip of the oocyte. During the maturation and cleavage divisions of the embryo, the polar granules fragment into small granules and ribosomes become associated with their periphery. After their inclusion in the pole cell and the two pole cell divisions, the polar granules reaggregate into large granules and these subsequently become associated with the nuclear envelope as dense bodies. During the remainder of the life cycle ofMiastor until the inception of oogenesis, dense bodies are associated with the nuclear envelope of the primordial germ cells. During oogenesis the nuclear envelope of the oocyte lacks the dense bodies, but the nurse nuclei have copious amounts. The relationships between the dense bodies of the nuclear envelope of the nurse chamber and polar granules is discussed.

The present paper deals with studies of the activity and the isoenzyme patterns of LDH during the development ofXenopus laevis, Triturus alpestris andvulgaris andAmbystoma mexicanum. Activity measurements have been performed with the optical test method using pyruvate as substrate and the isoenzymes have been separated by vertical starch gel electrophoresis. a) Substrate optima for enzyme extracts from embryonic stages 1-38 are identical in the three speciesTriturus alpestris, Ambystoma mexicanum andXenopus laevis and lie in the range of 1.2-1.4 mM pyruvate. b) Uncleaved eggs ofXenopus andTriturus alpestris contain almost the same activities of LDH/embryo, whereas the eggs ofAmbystoma show values twice as high. The activity per embryo is fairly constant between stage 1 and 26 in all species tested. Only a slight rise takes place during gastrulation and neurulation, but a second increase becomes pronounced after the embryos have reached stage 30. c) The activity of LDH, LDH per mg soluble protein in embryonic extracts rises during gastrulation and neurulation inTriturus alpestris, Ambystoma mexicanum andXenopus laevis compared to the uncleaved egg. After having fallen to a minimum at stage 26, it rises again inTriturus alpestris andXenopus embryos and approaches a limiting value after stage 40. InAmbystoma however the LDH activity mg soluble protein decreases after stage 26 and approaches the same limiting value as inTriturus alpestris andXenopus, so that the marked difference in activity values between uncleaved eggs ofAmbystoma on the one hand andTriturus alpestris andXenopus on the other hand diminishes considerably after stage 40. d) During early embryonic development the isoenzyme pattern of LDH is rather constant in all four species tested and is species-specific. With the onset of organogenesis, especially when the myotomes begin to function (stage 26), basic isoenzymes, which are dominant in adult skeletal muscle and other adult organs, appear for the first time inXenopus, Triturus alpestris andT. vulgaris. Neither quantitative nor qualitative changes are detectable in the isoenzyme pattern ofAmbystoma during development until stage 40; the general pattern of adult tissues exists here already in the egg.

1. The regulating capacity and the state of determination of the regions of the wing joint on the imaginal disk in the last two larval stages are examined. 2. After dissection of a part from the wing imaginal disk on the second and fourth day of the last larval stage, regeneration is initiated, but not completed because the remaining time period before the prepupal stage begins is too short. From tests made on the second day of the final larval stage some of the implanted medially halved wing disks will form symmetrically duplicated parts. 3. On the fifth day of the last larval period regeneration did not appear in all cases. The regulating capacity disappears after the fifth day. The period of determination may lay between the fifth and the sixth day of the last larval stage. 4. After extirpation of a medially halved wing disk during the penultimate stage, the remaining half wing-Anlage, apart from the joint elements, even the wing lamina will be partly or completely regenerated. 5. The parts of the imaginal disks, implanted in the abdomen, duplicate themselves in many cases but were not able to regenerate a complete wing joint. Such double formations appeared often, but not always symmetrically. Even the tegula can be doubled. 6. When regeneration has begun, if at all present, a delay in further development does not occur to the same extent inLymantria as inEphestia.