Wilhelm Roux Archiv Fur Entwicklungsmechanik Der Organismen最新文献

One of the most important biochemical aspects of regeneration, in the early stages, after amputation, is the increase in acid hydrolase activities. During regeneration, 24h after amputation of the anterior part of the body of the polychaeteOwenia fusiformis, we have observed the following events: 1. The increase of³H-Uridine incorporation in microsomal and nuclear fractions. 2. After one hour's labelling the major part of the radioactivity is localized on polysomal structures. 3. By use of specific drugs (cycloheximide and actinomycin D at various concentrations) we have attempted demonstrating the relation between the activation of synthesis of RNAs (probably mRNA) and the new synthesis of acid hydrolase molecules.

In a foreign protein medium (LTS), naked prospective diapause-germs have a tendency to develop into fully segmented germ bands (stage of dormancy): however, deposition of chorion, serosa or yolk will stimulate themvia the medium to pass through organogenesis without delay (non-dormancy =Nd). The question remained if a germ from a non-diapausing egg would stimulate the uninterrupted development of such a test-germ (Tk). Using 2 different or 2 to 3 equal germs as well asTk alone (control) in hanging drops, experimental evidence was obtained permitting conclusions not only as to the competence and sensitivity of the embryonic reaction system, but also as to factors of the extraembryonicNd-action systems in eggs with and without predetermined diapause regulatory mechanism. 1. Control explants (1 prospective diapause-Tk inLYS) have aNd-level of 10% (= average ofNd-rates in operative stages). This difference from former controls (0%Nd) can be explained by the longer operative procedure in the cups when several test-germs were used. Seven minutes after opening an egg one can reckon on aNd-stimulationvia LYS medium from egg-residues in the operation cup. While transfering the test-germs, yolk-derived substances related to theNd-stimulation can be brought into the hanging drop. The difference betweenNd-controls and the results ofNd-stimulation have to be statistically significant. 2. In experiments with two different germs in LYS-droplets no influence of a non-diapause germ (polyvoltine) on a prospective diapause germ (univoltine) could be noted. Accordingly, the naturally prospectiveNd-germs, have a tendency to develop to dormant germs only, as do the 2Tk and 1Tk controls. In combination with artificially prospectiveNd-germs (univoltine, HCl-treated) no stimulation of the test germ occcurs; nor after explantation with an older germ-band or a young embryo. 3. Combination with two prospective diapause germs of equal age in a drop, having the same minor contamination ofNd-factors in the operation-cup, will result in a threefold increase of theNd-level as compared to the 1Tk-controls. The competence of the embryonic reaction system ranges from a coatlike germ-anlage to a germ with thoracic segmentation. In the dish-like germ-anlage at diapause onsetin ovo maximalNd-rate (70%) is foundin vitro, i.e. highest sensibility towardsNd-stimulatory factors. Also at this operative stage, bothTk of a drop, most frequently developed beyond the dormancy stage. 4. Experiments with three prospective diapause germs of equal age in a drop, having the same minor contamination ofNd-factors in the operation-cup, show a sevenfold increase of theNd-level as compared to controls, showing an almost similar stage-range in competence and stage-specificity in sensibility. The increase of theNd-stimulation rate in relation with the number of test germs in the drop corresponds to a morphogenetic crowding-effect, the influence of the test germs on each other being called "interfere

In the egg ofPimpla turionellae L., three density gradients are produced by different methods of centrifugation. In spinning, the egg is rotated about its own long axis, so that the lightest egg material is collected in a central column (radial stratification). Flinging parallel to the long axis has been carried out at a short distance from the rotational axis (rotation axis situated immediately adjacent to a long edge of the egg) as well as further from the rotational axis (at a distance of 4.5 cm). A transversal stratification is thereby produced, in which the lightest and the heaviest material are collected at opposite long edges of the egg. The same stratification results from all three methods. From centripetal outward toward centrifugal, a lipid zone, a light yolk zone, a cytoplasm zone poor in yolk granules (basophilic cytoplasmic network), a dense yolk zone and a glycogen zone are formed. The sharpness of separation between the zones in eggs centrifuged during maturation divisions is better than that in eggs spun or flung during cleavage or pre-blastoderm formation. Either development ceases soon after the experiment has taken place or the centrifuged eggs develop into larvae. Half of the eggs flung at short distance or spun about the rotational axis with 10000-12000g are able to develop into embryos. Eggs handled by both of these methods show identical development at increasing accelerations. Eggs flung at greater distance already cease their development after a treatment at 10000g. Malformations or incomplete embryos do not occur in any group of experiments. These findings allow postulation of a system of factors sensitive to accelerations higher than 10000g, which is arranged cylindrically within the egg and which is not connected in any way to the shiftable, light microscopic fractions. This postulated system of factors could have a dynamic function and thereby be an essential component of the primary organization pattern in the egg ofPimpla.Only eggs forming polar caps at opposite ends of the egg within 1.5-2 hours after the experiment will develop into embryos. The polar caps are formed independently of each other. Following too great a stress on the end of the egg oblique to the rotational axis, ooplasm contraction fails to take place. Ooplasmic redistribution has been pursued in life and in section pictures in eggs continuing to and failing to develop. Redistribution combined with a regulated removal of zones is evidently connected with the energid migration. The content of the lipid plasm zone disappears to some extent during redistribution. The posterior part possesses the highest capacity for development in nonviable eggs. It is sometimes able to form a blastoderm independently of the anterior region. A blastoderm is formed only if the posterior part includes the region between 25 and 35% of the egg.

The nurse chamber inMiastor is a syncytium containing a variable number of nuclei. Many workers have claimed that all the nurse nuclei were derived from somatic cells. However, since one of these nuclei is larger than the remaining nuclei, other workers have thought that this nucleus was germinal in origin. Our ultrastructural studies of the nurse chamber-oocyte complex demonstrate the presence of an intercellular bridge between the nurse chamber and the oocyte. Furthermore, the large nurse nucleus contains lamellae characteristic only of the germ line. Both findings indicate that one of the nurse nuclei is the sister to the oocyte.

When first leg imaginai discs from early third instar larvae are forced to differentiate immediately by transplantation into larval hosts ready to pupate, they fail to differentiate all the adult leg structures. Even though the variability among these incomplete differentiations is wide, we were able to draw the following conclusions. Even if only little differentiations, limited to a few hairs and bristles, were observed, the structures were always identifiable as the most proximal and the most distal structures of the leg. In those cases where differentiation was more complete the tarsal segments were never completely separated; in extreme cases all five segments were fused. The segments more proximal than the tarsus were always separated when differentiation occurred, but not all the structures within the segments were formed. The absence of a particular structure in an incompletely differentiated segment seems to occur in a random way and is not dependent on its location within the disc.

Various fragments of the wing disc from third instar larvae ofZaprionus vittiger were implanted into mature host larvae. From the differentiated structures observed in the metamorphosed transplants, a fate map (anlage plan) was constructed which includes the primordia for the thoracic colored stripes and the anlagen for several thoracic bristle organs. Our present data forZ. vittiger andDrosophila melangaster are in accord with the fate map reported earlier forD. melanogaster, with the only exception that the medio-lateral orientation of the primordia in the wing disc is reversed.

1. Anterior and posterior halves of 6 hour-old embryos were transplanted with or without their central egg yolk filling into the abdomens of adult females. 2. It was found that the yolk has no formative or nutritive influence on the differentiation which proceeds normally in the adult milieu.

The modalities of determination and differentiation of sexual dimorphism of Nereids (Annelida Polychaeta) were investigated inNereis pelagica L. andPerinereis cultrifera G. with experiments involving decerebration, castration (by X irradiation), grafts or injection of genital products.The sexual somatic characters of the parapodial cirri (swelling and crenellations) always develop according to the genetic sex, whatever the genital state of the Nereis and the nature of the intervention. Therefore the determination of the sexual somatic characters of the parapodial cirri appear to be determined in a very precocious and stable way (at least 3 months before the genital differentiation).The pygidial papillae, a male sexual character in normal conditions, can be formed by very young females in which heteronereidation is realized prematurely by decerebration, and by females of any age in which heteronereid transformations are realized in a male environment (e.g. by injection of genital products, or grafting onto a male). Therefore the pygidial papillae may be determined precociously in either sex; however their differentiation is normally inhibited in females in the course of genital maturation.

In ring/rod-X-chromosome heterozygotes the ring-X-chromosome is frequently lost in the early cleavage mitoses. The resulting gynandromorphs are mosaics with female XX- and male XO-areas. The phenotypes of the recessive alleles on the rod-X-chromosome are expressed in the XO-areas.The genemaroonlike (mal) on the X-chromosome influences the activity of the enzyme aldehyde oxidase. This fact was used to test the cell autonomy of aldehyde oxidase activity by histochemical methods in gynandromorphs of the genotypesR(1)2,In(1)w ^vC /y w mal andR(1)2,In(1)w ^vC /y w sn ³ lz ^50e mal. The results show that in the cells of the imaginal Malpighian tubules the phenotypes ofwhite (w) andmaroonlike (mal) always occur together; XX-cells are pigmented and show aldehyde oxidase activity, whereas colorless XO-cells have no such enzyme activity (Figs. 1 and 2). This cell autonomy of aldehyde oxidase activity most likely applies also to the imaginal gut and the inner genitalia.The distribution of XX- and XO-areas in the Malpighian tubules, the gut and the inner genitalia was examined in 355 gynandromorphs. Approximately half of the gynanders have Malpighian tubules with an XX/XO-mosaic (Table 1, 2 and 3). A large fraction of the mosaic tubules (62%; Table 4) shows a pattern of alternating small cell clusters of different genotypes. It is supposed that this pattern develops during the formation of the tubes, especially during their elongation. The number of primitive Malpighian cells is estimated to be about 140.72% of the gynanders have mosaic guts (Table 1 and 5). The border between tissues of different genotypes is found very frequently in the posterior third of the anterior midgut (Fig. 3) and may correspond to the border between the tissues which develop from the anterior and posterior midgut rudiments. The estimates of the numbers of primitive cells for the gut structures are 2-3, as far as the crop, the cardia and the rectal valve are concerned, whereas a number of several hundred is estimated for the anterior as well as for the posterior midgut.Mosaics were also found in the inner genitalia consisting of combinations of male and female structures. In 16 gynandromorphs the paragonia or the ductus ejaculatorius were mosaic (Fig. 4); i.e. in male structures with XO-genotype areas with aldehyde oxidase activity were found. Nothing is known about the origin of these XX-cells, but the possibility must be considered that in gynandromorphs cells of female genotype can participate in the development of male genital structures.

In previous papers we have reported that wing disks ofGalleria mellonella complete tracheole migration and evagination when they are cultured in a chemically defined medium containing alpha-ecdysone. The presence of larval fat body in the culture medium greatly improved the response of the disks. We have isolated this fat body factor from culture medium. It is dialyzable, heat stable (100° C, 5 min), and insensitive to pronase digestion. The fat body factor, recovered from thin layer plates, stimulated evagination in the absence of alpha-ecdysone. Furthermore, radiochromatography studies with tritiated alpha-ecdysone and spectral analysis of the factor indicated that it was neither a metabolite of alpha-ecdysone nor an ecdysone-like molecule.