Further observations on the distribution of cytoplasmic substances among the cleavage cells in Lymnaea stagnalis

Development ◽  
1974 ◽  
Vol 31 (1) ◽  
pp. 37-59
Author(s):  
Chr. P. Raven
Keyword(s):  
Lymnaea Stagnalis ◽  
Special Kind ◽  
Central Position ◽  
Animal Cells ◽  
Interphase Nuclei ◽  
Cell Stage ◽  
Animal Pole ◽  
Vegetative Part ◽  
Composite Granules

The period of development from the 4th cleavage to the 24-cell stage was studied. Both during 4th and 5th cleavage a wave of mitosis passes over the egg from the vegetative to the animal pole. At 5th cleavage it does not spread over the cells of the first quartet, however, and cell division stops for 3 h at the 24-cell stage. Nucleoli are now formed in the interphase nuclei, and many of them are extruded whole into the cytoplasm. After 5th cleavage the cleavage cavity is gradually reduced and finally disappears altogether. All cells then extend towards the centre of the egg. In this process one of the macromeres (3D) finally becomes preponderant, gets a central position and applies itself against the inner side of the animal cells. This is preceded by a period of seemingly haphazard variation in macromere positions. Lipid globules and mitochondria accumulate in the central parts of the first quartet cells. The special cytoplasm (SCA-plasm) found in the most vegetative part of the macromeres at the 8-cell stage is distributed among the cells at the next cleavages. Part of it passes into the 2nd micromeres, another part into the 3rd micromeres, while the rest remains concentrated in the vegetative part of the macromeres around the vegetative cross-furrow. At this place coarse dark composite granules, of a special kind and very rich in RNA, become visible at the 16-cell stage. At the 24-cell stage they begin to move inwards along the cell walls, and finally condense into the compact RNA-rich ‘ectosomes’ at the central ends of the macromeres. The significance of the SCA-plasm and of the ‘ectosomes’ for the determination of dorsoventrality in Lymnaea is discussed.

Contribution of maternal factors and cellular interaction to determination of archenteron in the starfish embryo

Development ◽  
1994 ◽  
Vol 120 (9) ◽  
pp. 2619-2628 ◽  
Author(s):  
R. Kuraishi ◽  
L. Osanai
Keyword(s):  
Alkaline Phosphatase ◽  
Normal Development ◽  
Early Stage ◽  
Posterior Part ◽  
Immature Oocyte ◽  
Cellular Interaction ◽  
Cell Stage ◽  
Cytoplasmic Factor ◽  
Animal Pole

Contribution of maternal cytoplasmic factors and cellular interaction to determination of archenteron in a starfish embryo was analyzed by (1) examining temporal and positional pattern of expression of an endoderm-specific enzyme, alkaline phosphatase, (2) deleting the vegetal polar fragment from an immature oocyte and (3) changing the orientation of a blastomere within an early stage embryo. The archenteron (and the differentiated digestive tract) of Asterina pectinifera was divided into three areas based on the time of start of alkaline phosphatase expression. At 27 hours after 1-methyladenine treatment, the whole archenteron except the anterior end started to express alkaline phosphatase. The anterior negative area differentiated into mesodermal tissues such as mesenchyme cells and anterior coelomic pouches (anterior mesodermal area). The alkaline-phosphatase-positive area 1 gave rise to the esophagus and the anterior end of the stomach. Alkaline-phosphatase-positive area 2, which was gradually added to the posterior end of the archenteron after 30 hours, became alkaline-phosphatase- positive and formed the middle-to-posterior part of the stomach and the intestine. When the vegetal oocyte fragment, the volume of which was more than 8% of that of the whole oocyte, was removed from the immature oocyte, archenteron formation was strongly suppressed. However, when the volume deleted was less than 6%, most of the larvae started archenteron formation before the intact controls reached the mesenchyme-migration stage (30 hours). Although cells in the alkaline-phosphatase-positive area 2 are added to the posterior end of the archenteron after 30 hours in normal development (R. Kuraishi and K. Osanai (1992) Biol. Bull. Mar. Biol. Lab., Woods Hole 183, 258–268), few larvae started gastrulation after 30 hours. Estimation of the movement of the oocyte cortex during the early development suggested that the area that inherits the cortex of the 7% area coincides with the combined area of anterior mesodermal area and alkaline-phosphatase-positive area 1. When one of the blastomeres was rotated 180° around the axis of apicobasal polarity at the 2-cell stage to make its vegetal pole face the animal pole of the other blastomere, two archentera formed at the separated vegetal poles. Intracellular injection of tracers showed that cells derived from the animal blastomere, which gives rise to the ectoderm in normal development, stayed in the outer layer until 30 hours; a proportion of them then entered the archenteron gradually. The involuted animal cells expressed alkaline phosphatase and were incorporated into the middle-to-posterior part of the stomach and the intestine. These results suggest that anterior mesodermal area and alkaline-phosphatase-positive area 1 are determined by cytoplasmic factor(s) that had already been localized in their presumptive areas. In contrast, alkaline-phosphatase-positive area 2 becomes the endoderm by homoiogenetic induction from the neighboring area on the vegetal side, namely alkaline-phosphatase-positive area 1.

par-4, a gene required for cytoplasmic localization and determination of specific cell types in Caenorhabditis elegans embryogenesis.

Genetics ◽  
1992 ◽  
Vol 130 (4) ◽  
pp. 771-790 ◽  
Author(s):  
D G Morton ◽  
J M Roos ◽  
K J Kemphues
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Types ◽  
Intestinal Cells ◽  
Specific Cell ◽  
Cytoplasmic Localization ◽  
Loss Of Function ◽  
Embryo Viability ◽  
Cell Stage ◽  
Maternal Genome

Abstract Specification of some cell fates in the early Caenorhabditis elegans embryo is mediated by cytoplasmic localization under control of the maternal genome. Using nine newly isolated mutations, and two existing mutations, we have analyzed the role of the maternally expressed gene par-4 in cytoplasmic localization. We recovered seven new par-4 alleles in screens for maternal effect lethal mutations that result in failure to differentiate intestinal cells. Two additional par-4 mutations were identified in noncomplementation screens using strains with a high frequency of transposon mobility. All 11 mutations cause defects early in development of embryos produced by homozygous mutant mothers. Analysis with a deficiency in the region indicates that it33 is a strong loss-of-function mutation. par-4(it33) terminal stage embryos contain many cells, but show no morphogenesis, and are lacking intestinal cells. Temperature shifts with the it57ts allele suggest that the critical period for both intestinal differentiation and embryo viability begins during oogenesis, about 1.5 hr before fertilization, and ends before the four-cell stage. We propose that the primary function of the par-4 gene is to act as part of a maternally encoded system for cytoplasmic localization in the first cell cycle, with par-4 playing a particularly important role in the determination of intestine. Analysis of a par-4; par-2 double mutant suggests that par-4 and par-2 gene products interact in this system.

The Effect of a Temperature Gradient on the Early Development of the Frog

1928 ◽  
Vol 5 (4) ◽  
pp. 309-336
Author(s):  
I. L. DEAN ◽  
M. E. SHAW ◽  
M. A. TAZELAAR
Keyword(s):  
Cell Size ◽  
Small Cells ◽  
Tail Bud ◽  
Animal Cells ◽  
Differential Growth ◽  
Experimental Conditions ◽  
Animal Pole ◽  
Stage Of Development ◽  
Permanent Effect ◽  
Two Sides

1. Temperature gradients were passed through the developing frog's egg and embryos. These gradients were applied either (a) apico-basally, when they were either (i) adjuvant, or (ii) antagonistic to the egg's own main gradient; or (b) transversely to the egg's main axis--lateral gradients. 2. (a) By this means considerable modification of segmentation and of cell size was induced, and was especially marked in the mid-blastula. Adjuvant gradients accentuated the normal differences in cell size between the animal and vegetative poles. Antagonistic gradients produced a double gradient in cell size, the smallest cells being in the region of the equator, and animal cells, in extreme cases, larger than yolk cells. (b) Several cases of the non-formation or obliteration of the blastocoel were obtained by all methods of treatment. (c) Too high temperature with adjuvant gradient produced inhibition at the animal pole, the large retarded cells being very sharply marked off from the surrounding small cells. (d) Lateral gradients produced a great difference in cell size on the two sides of the eggy and, as in the cases of "inhibition," a sharp line of demarcation may appear between the large cells of the cooled side and the small cells of the heated side. (e) When two sets of exactly similar eggs were treated simultaneously in opposite ways, then those subjected to the adjuvant gradient were always, at the close of the experiment, at a more advanced stage of development than those subjected to an antagonistic gradient. Because of this the yolk cells of the "adjuvant" eggs were smaller than those of the "antagonistic" eggs, although the former were cooled and the latter heated. (f) There seems to be a slight permanent effect of the gradient applied during segmentation. Eggs treated with antagonistic gradient tend to develop into microcephalous tadpoles and vice versa. 3. (a) Antagonistic gradients during gastrulation cause a reduction of the gastrular angle. (For definition see Bellamy (1919).) (b) Antagonistic gradient causes the eggs to gastrulate sooner than adjuvant eggs under exactly similar experimental conditions. (c) In the neurula stage the differential effect of the gradient is seen in the inhibition of the head and dorsal region in those subjected to antagonistic gradient, and inhibition of tail and ventral region in those subjected to adjuvant gradient. (d) Whether this alteration of relative sizes of head and tail regions is maintained in later development has not yet been ascertained. (e) Eggs exposed to lateral gradients in all stages of gastrulation showed marked asymmetries, some of which were apparently regulated later, while others persisted till the death of the tadpole. 4. Side-to-side treatment in the tail bud stage caused the development of marked asymmetry as the result of differential growth of the two sides. As in the case of 3 (e) some tadpoles appeared to regulate back to normal, whereas others remained markedly asymmetrical till death.

The role of fibroblast growth factor in early Xenopus development

Development ◽  
1989 ◽  
Vol 107 (Supplement) ◽  
pp. 141-148 ◽  
Author(s):  
J. M. W. Slack ◽  
B. G. Darlington ◽  
L. L. Gillespie ◽  
S. F. Godsave ◽  
H. V. Isaacs ◽  
...  
Keyword(s):  
Marginal Zone ◽  
Specific Activity ◽  
Progressive Increase ◽  
Defined Medium ◽  
Relative Molecular Mass ◽  
Heparin Binding ◽  
Cell Stage ◽  
Animal Pole

In early amphibian development, the mesoderm is formed around the equator of the blastula in response to an inductive signal from the endoderm. A screen of candidate substances showed that a small group of heparin-binding growth factors (HBGFs) were active as mesoderm-inducing agents in vitro. The factors aFGF, bFGF, kFGF and ECDGF all show similar potency and can produce inductions at concentrations above about 100 pM. The product of the murine int-2 gene is also active, but with a lower specific activity. Above the induction threshold there is a progressive increase of muscle formation with dose. Single blastula ectoderm cells can be induced and will differentiate in a defined medium to form mesodermal tissues. All inner blastula cells are competent to respond to the factors but outer cells, bearing oocyte-derived membrane, are not. Inducing activity can be extracted from Xenopus blastulae and binds to heparin like the previously described HBGFs. Antibody neutralization and Western blotting experiments identify this activity as bFGF. The amounts present are small but would be sufficient to evoke inductions in vivo. It is not yet known whether the bFGF is localized to the endoderm, although it is known that inducing activity secreted by endodermal cells can be neutralized by heparin. The competence of ectoderm to respond to HBGFs rises from about the 128-cell stage and falls again by the onset of gastrulation. This change is paralleled by a rise and fall of binding of 125I-aFGF. Chemical cross-linking reveals that this binding is attributable to a receptor of relative molecular mass about 130 × 103. The receptor is present both in the marginal zone, which responds to the signal in vivo, and in the animal pole region, which is not induced in vivo but which will respond to HBGFs in vitro. In the embryo, the induction in the vicinity of the dorsal meridian is much more potent than that around the remainder of the marginal zone circumference. Dorsal inductions contain notochord and will dorsalize ventral mesoderm with which they are later placed in contact. This effect might be due to a local high bFGF concentration or, more likely, to the secretion in the dorsal region of an additional, synergistic factor. It is known that TGF-β-1 and -2 can greatly increase the effect of low doses of bFGF, although it has not yet been demonstrated that they are present in the embryo. Lithium salts have a dorsalizing effect on whole embryos or on explants from the ventral marginal zone, and also show potent synergism when applied together with HBGFs.

Most of centrin in animal cells is not centrosome-associated and centrosomal centrin is confined to the distal lumen of centrioles

1996 ◽  
Vol 109 (13) ◽  
pp. 3089-3102 ◽  
Author(s):  
A. Paoletti ◽  
M. Moudjou ◽  
M. Paintrand ◽  
J.L. Salisbury ◽  
M. Bornens
Keyword(s):  
Calcium Binding ◽  
Complex Structure ◽  
Specific Pattern ◽  
Dominant Negative ◽  
Cell Fractionation ◽  
Animal Cells ◽  
Negative Effects ◽  
Cell Stage ◽  
Centriole Duplication ◽  
Ef Hand

Centrin is a member of the calcium-binding EF-hand protein superfamily present in centrosomes of widely divergent species. Investigating the cellular distribution of human centrin by both immunofluorescence and cell fractionation, we report that centrin is biochemically complex in human cells, displaying as much as ten isoforms in 2-D electrophoresis. This suggests that centrin may be subject to multiple regulations. Strikingly, more than 90% of centrin is not associated with the centrosome fraction. The centrosome-associated centrin, however, displays a specific pattern in 2-D electrophoresis and is concentrated within the distal lumen of the centrioles, where a complex structure has been previously described. This precise localization allows the resolution of centrioles at the optical level throughout the cell cycle and provides a valuable tool for monitoring centriole duplication. To get insights on centrin function, we performed injection experiments of recombinant heterologous centrin in two-cell stage frog embryos in an attempt to produce dominant negative effects. We report that green algae and human centrin delay cleavage and promote the formation of abnormal blastomeres in which the distribution of microtubule asters and of nuclei is dramatically impaired. This suggests that centrin could be involved in the centrosome reproduction cycle, in the coordination of cytoplasmic and nuclear division or in cytokinesis.

Activité génétique au cours de l'embryogenèse de l'Oligochète Eisenia fœtida (autoradiographie à l'uracile-3H et traitement à l'actinomycine D)

Development ◽  
1976 ◽  
Vol 35 (2) ◽  
pp. 403-424
Author(s):  
Par J. Devriès
Keyword(s):  
Ribonucleic Acid ◽  
Actinomycin D ◽  
Acid Synthesis ◽  
Eisenia Foetida ◽  
Messenger Rnas ◽  
Blastula Stage ◽  
Stages Of Development ◽  
Interphase Nuclei ◽  
Nuclear Membranes

Embryos of Eisenia fœtida (Spiralia) have been cultivated with [3H]uracil precursor of RNA at different stages of development from egg to gastrula. The results show that ribonucleic acid synthesis detected by autoradiography begins precociously. During segmentation messenger RNAs are produced by interphase nuclei and liberated in cytoplasm cyclically at mitosis. After the blastula stage rRNAs (nucleoli), which can migrate through the nuclear membranes, predominate. The blastomeres, which contain polar plasm and also mesoderm, already known for its controlling part in embryogenesis after gastrulation, are the seats of the increasingly important ribonucleic acid synthesis. These genetic transcriptions, which are inhibited by actinomycin D, are implicated in the determination of the blastomeres and postblastular differentiation. Only the messages required for the segmentation divisions pre-exist in the undivided egg.

Xmsx-1 modifies mesodermal tissue pattern along dorsoventral axis in Xenopus laevis embryo

Development ◽  
1997 ◽  
Vol 124 (13) ◽  
pp. 2553-2560 ◽  
Author(s):  
R. Maeda ◽  
A. Kobayashi ◽  
R. Sekine ◽  
J.J. Lin ◽  
H. Kung ◽  
...  
Keyword(s):  
Target Gene ◽  
Marginal Zone ◽  
Dominant Negative ◽  
Gastrula Stage ◽  
Cell Stage ◽  
Animal Pole ◽  
Alpha Globin ◽  
Molecular Marker Analysis ◽  
Alpha Actin ◽  
Stage Stage

This study analyzes the expression and the function of Xenopus msx-1 (Xmsx-1) in embryos, in relation to the ventralizing activity of bone morphogenetic protein-4 (BMP-4). Expression of Xmsx-1 was increased in UV-treated ventralized embryos and decreased in LiCl-treated dorsalized embryos at the neurula stage (stage 14). Whole-mount in situ hybridization analysis showed that Xmsx-1 is expressed in marginal zone and animal pole areas, laterally and ventrally, but not dorsally, at mid-gastrula (stage 11) and late-gastrula (stage 13) stages. Injection of BMP-4 RNA, but not activin RNA, induced Xmsx-1 expression in the dorsal marginal zone at the early gastrula stage (stage 10+), and introduction of a dominant negative form of BMP-4 receptor RNA suppressed Xmsx-1 expression in animal cap and ventral marginal zone explants at stage 14. Thus, Xmsx-1 is a target gene specifically regulated by BMP-4 signaling. Embryos injected with Xmsx-1 RNA in dorsal blastomeres at the 4-cell stage exhibited a ventralized phenotype, with microcephaly and swollen abdomen. Histological observation and immunostaining revealed that these embryos had a large block of muscle tissue in the dorsal mesodermal area instead of notochord. On the basis of molecular marker analysis, however, the injection of Xmsx-1 RNA did not induce the expression of alpha-globin, nor reduce cardiac alpha-actin in dorsal marginal zone explants. Furthermore, a significant amount of alpha-actin was induced and alpha-globin was turned off in the ventral marginal zone explants injected with Xmsx-1. These results indicated that Xmsx-1 is a target gene of BMP-4 signaling, but possesses a distinct activity on dorsal-ventral patterning of mesodermal tissues.

Sound influence on spa park perception in feelings of visitors

2017 ◽  
Author(s):  
Małgorzata Sztubecka ◽  
Maria Mrówczyńska ◽  
Anna Bazan-Krzywoszańska ◽  
Marta Skiba
Keyword(s):  
Human Perception ◽  
Special Kind ◽  
Sound Level ◽  
Health Resort ◽  
Measurement Results ◽  
Noise Measurements ◽  
Permissible Levels ◽  
The One ◽  
The Impact

Noise can have many harmful effects on the recipients, however people exposed to noise on a long-term and regular basis can get used to it, even if the permissible levels are exceeded. In cities, green areas and park systems are provided to create a climate for rest and relaxation. Spa parks are a special kind of such park systems, which – in addition to the above-mentioned features – support therapies offered by spa facilities located there. On the one hand, patients and visitors appreciate various social and entertainment events held there, but – on the other – a multitude of sounds associated with them may reduce the comfort of their stay. The aim of this paper is to analyse the relationship between the results of noise measurements and the human perception of noise within the impact zone. The examined area is a spa park in the health resort district of Inowrocław, where seasonal measurements (taken in summer and winter) provided a basis for the determination of the connection between the measured values of equivalent sound level and the noise level perceived by surveyed people. A statistical analysis was performed to take into account the correlation between the obtained measurement results and the human perception of noise. It shows some differences in the perception of heard sounds. The results allow an evaluation of the soundscape of the analysed area.

NUTRITION OF ANIMAL CELLS IN TISSUE CULTURE: VIII. DESOXYRIBONUCLEIC ACID PHOSPHORUS AS A MEASURE OF CELL MULTIPLICATION IN REPLICATE CULTURES

1954 ◽  
Vol 32 (1) ◽  
pp. 319-326
Author(s):  
George M. Healy ◽  
Dorothy C. Fisher ◽  
Raymond C. Parker
Keyword(s):  
Horse Serum ◽  
Cell Multiplication ◽  
Desoxyribonucleic Acid ◽  
Present Communication ◽  
Animal Cells ◽  
Defined Media ◽  
Chick Embryo Extract ◽  
Material Good ◽  
Cell Strains

A chemical method of estimating the size of cell populations in replicate cultures has been devised for use with certain cell strains from the mouse and rat. The method is based upon the determination of desoxyribonucleic acid phosphorus (DNAP). Although the method may be used as an alternative to the procedure of counting isolated, stained nuclei in a hemocytometer, it actually supplements such measurements and provides useful information on the DNA-content per cell. The method consists of a modified Schmidt and Thannhauser separation of ribonucleic acid (RNA) and desoxyribonucleic acid (DNA) followed by the spectrophotometric estimation of the orthophosphate. The present communication describes the procedures in detail and reports recoveries of RNAP and DNAP from mixtures of highly polymerized nucleic acids and various types of biological material. Good correlation was found between nuclear counts and DNAP values in natural media (containing horse serum and chick embryo extract) and in synthetic (chemically-defined) media. Finally, the efficiency of the dispensing apparatus most frequently employed in preparing replicate cultures from continuously stirred, washed cell suspensions has been determined by measuring the DNAP content of serially dispensed samples.

Specification of endoderm and mesoderm in the sea urchin

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S41-S41 ◽  
Author(s):  
David R. McClay
Keyword(s):  
Sea Urchin ◽  
Wnt Pathway ◽  
Special Significance ◽  
Nuclear Entry ◽  
Cell Stage ◽  
Animal Pole ◽  
Secondary Axis ◽  
Sea Urchin Embryo ◽  
Vegetal Pole

It has long been recognized that micromeres have special significance in early specification events in the sea urchin embryo. Micromeres have the ability to induce a secondary axis if transferred to the animal pole at the 16-cell stage of sea urchin embryos (Hörstadius, 1939). Without micromeres an isolated animal hemisphere develops into an ectodermal ball called a dauer blastula. Addition of micromeres to an animal half rescues a normal pluteus larva, including endoderm (Hörstadius, 1939). Despite these well-known experiments, however, neither the molecular basis of that induction nor the endogenous inductive role of micromeres in development was known. In recent experiments we learned that if one eliminates micromeres from the vegetal pole at the 16-cell stage the resulting embryo makes no secondary mesenchyme. Earlier it had been found that β-catenin is crucial for specification events that lead to mesoderm and endoderm (Wikra-manayake et al., 1998; Emily-Fenouil et al., 1998; Logan et al., 1999). We noticed that at the 16-cell stage β-catenin enters the nuclei of micromeres, then enters the nuclei of macromeres at the 32-cell stage (Logan et al., 1999). Since nuclear entry of β-catenin is known to be important for its signalling function in the Wnt pathway, we asked whether β-catenin functions in the micromere induction pathway.

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