Effects of lithium chloride on embryos ofOphryotrocha labronica LaGreca and BacciEmanuelsson, Hadar
doi: 10.1007/BF00582001pmid: 28304681
Cleavage embryos of the polychaeteOphryotrocha labronica were exposed to LiCl solutions of various strength for up to 4 days. High concentrations strongly inhibited development and led to endodermal protrusion, whereas moderate concentrations permitted development of larvae, although with characteristic disturbances as a consequence. Ultrastructural analyses of embryos exposed to moderate concentrations demonstrated manifest changes already during the first 24 hours, viz. of lipid droplets and yolk granules, the latter being ruptured and the contents dispersed to an extent far surpassing that at normal development. The premature widespread splitting of yolk granules by LiCl was confirmed by quantitative measurements on embryos which during oogenesis had their yolk granule DNA selectively labelled with3H-thymidine.
Die humorale Kontrolle der Hodenentwicklung vonEphestia kühniella in der MetamorphoseNowock, Joachim
doi: 10.1007/BF00582002pmid: 28304682
1.
The testes ofEphestia kühniella go through two morphogenetic processes during metamorphosis: fusion of both organs in the prepupa (stage A3) and torsion in the early pupal phase (day 1–5; 23° C).
2.
By ligating behind the thorax the critical periods of these processes have been determined: for fusion the transition to prepupal phase, for torsion the second half (A3–A4) of this developmental stage.
3.
The humoral conditions during prepupal phase do not enable testis to make an autonomous torsion. This process is connected to a pupal milieu.
4.
When testes from donors, which have not yet passed the critical periods of fusion and torsion, are directly transplanted into pupae differentiation will only occur, if they are exposed to the influence of secretions of endocrine organs during this stage. The effectiveness of the morphogenetic factors decreases with aging of this stage and is no more detectable towards its end.
5.
Testes of various ages show different responsiveness to an effective humoral milieu: the younger the grafts the later they respond. Investigations with progressively younger larvae, however, did not yield a threshold of competence until the 3. instar (younger larvae withdrew from operation because of their small size).
6.
On the base of these results a conception of the control of testis differentiation during metamorphosis is traced. It is suggested that beside the stimulus of prothoracic gland hormone during the prepupal stage a second, pupal factor is necessary for torsion.
Kennzeichnung und Verhalten lysosomaler Enzyme im Schwanzgewebe von Xenopus-Larven in Beziehung zur InvolutionPerriard, Jean
doi: 10.1007/BF00582003pmid: 28304683
1.
The distribution of lysosomal enzymes obtained by density gradient centrifugation of cell-free extracts of Xenopus tail tissue was compared during growth and involution. The particles containing lysosomal enzymes were also characterized by means of electron microscopy.
2.
Cytochromeoxidase is recovered to more than 90% in bound form (mitochondria), whereas lysosomal enzymes are characterized by a high proportion of soluble activity (up to 67%). The particle-bound activity ofβ-glucuronidase, cathepsin, and acid RNase show two peaks after centrifugation, in contrast to the activity of acid phosphatase, which is distributed over the whole gradient. During tail involution an increasing proportion of soluble activity is observed, especially for cathepsin and acid RNase.
3.
Electronmicroscopical examination reveals a rather heterogeneous composition of the particle populations obtained by density gradient centrifugation. In fractions with highest activity of lysosomal enzymes various types of electron dense granules are found, thus precluding characterization of a specific lysosomal structure.
4.
The distribution of enzymes after induction of tail involution with thyroxine was almost similar to the results obtained from spontaneously metamorphosing animals. Since actinomycin D inhibits the increase in lysosomal enzymes and tissue involution it is concluded that the synthesis of soluble acid hydrolases is a prerequisite of hormonal induced tissue involution.
Position of targets and period of competence for UV-induction of the malformation “Double Abdomen” in the egg ofSmittia spec. (Diptera, Chironomidae)Kalthoff, Klaus
doi: 10.1007/BF00582004pmid: 28304684
1.
UV irradiation of anterior pole regions of eggs ofSmittia results in the formation of “double abdomens”. The frequency of this malformation has been recorded as a function of developmental stage, size and position of irradiated area, and UV dose.
2.
The efficiency of irradiation decreases with increasing longitudinal extent of the irradiated anterior area.
3.
Within the anterior fourth of the egg, irradiation of peripheral regions is more effective than irradiation of central regions.
4.
The varying efficiency of irradiation is thought to represent a corresponding distribution in the concentration of effective targets or the morphogenetic efficiency of the targets in the irradiated state. Alternative interpretations are discussed.
5.
There is a multiplicity of targets distributed symmetrically to the longitudinal egg axis.
6.
The effective targets have been proved to be localized in the ooplasm of eggs aged less than 1 h. There is evidence to show that the targets are confined to the ooplasm during all stages studied.
7.
The targets are probably stored during oogenesis.
8.
The irradiated targets affect the body segment pattern far beyond the irradiated area.
9.
Possible relations between the targets for UV-induction of double abdomens and factors that are involved in the formation of the normal body segment pattern are discussed.