Instability of the anteroposterior axis in spontaneous double abdomen (sda), a genetic variant of Chironomus samoensis (Diptera, Chironomidae)

Development ◽  
1987 ◽  
Vol 101 (3) ◽  
pp. 591-603 ◽  
Author(s):  
K.L. Kuhn ◽  
J. Percy ◽  
M. Laurel ◽  
K. Kalthoff
Keyword(s):  
Genetic Variant ◽  
Laboratory Strain ◽  
Posterior Pole ◽  
Mirror Image ◽  
Anterior Pole ◽  
Spontaneous Formation ◽  
Pole Cells ◽  
Anterior Segments ◽  
Egg Polarity

We have isolated a laboratory strain of Chironomus samoensis in which determination of the anteroposterior egg polarity is disturbed. Most conspicuous is the spontaneous formation of ‘double abdomen’ embryos where head and thorax are replaced by a mirror image of the abdomen. Such double abdomens are found in about half of the egg clusters in this strain, which we call the spontaneous double abdomen (sda) strain as opposed to the normal (N) strain. Also observed in the sda strain, although less frequently, are ‘double cephalon’ embryos showing a mirror-image duplication of cephalic segments in the absence of thorax and abdomen. Moreover, embryos from the sda strain tend to form cells at the anterior pole resembling the pole cells at the posterior pole. Reciprocal crossings between the sda and the N strain indicate that the sda trait is inherited maternally. Spontaneous double abdomen formation is correlated with signs of disturbed egg architecture, including extruded yolk and detached cells. Double cephalons can also be generated by centrifuging embryos from the N strain, whereas centrifugation of sda embryos produces mostly double abdomens. Double abdomen formation can be induced experimentally by anterior u.v. irradiation of embryos from either strain. The sda trait and u.v. irradiation act in a synergistic fashion. The data suggest that the sda trait may be caused by one or more genomic mutations interfering indirectly with the activity of anterior determinants, i.e. cytoplasmic RNP particles necessary for the development of anterior segments. The sda defects may be ascribed to alterations in cytoskeletal components involved in anchoring anterior determinants and segregating them into anterior blastoderm cells.

Mutations in the Drosophila gene bullwinkle cause the formation of abnormal eggshell structures and bicaudal embryos

Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 3023-3033 ◽  
Author(s):  
K.R. Rittenhouse ◽  
C.A. Berg
Keyword(s):  
Cell Migration ◽  
Cell Fate ◽  
Germ Line ◽  
Follicle Cell ◽  
Posterior Pole ◽  
Mirror Image ◽  
Follicle Cells ◽  
Anterior Pole ◽  
Posterior Group ◽  
General Transport

Subcellular localization of gene products and cell migration are both critical for pattern formation during development. The bullwinkle gene is required in Drosophila for disparate aspects of these processes. In females mutant at the bullwinkle locus, the follicle cells that synthesize the dorsal eggshell filaments do not migrate properly, creating short, broad structures. Mosaic analyses demonstrate that wild-type BULLWINKLE function is required in the germ line for these migrations. Since the mRNA for gurken, the putative ligand that signals dorsal follicle cell fate, is correctly localized in bullwinkle mutants, we conclude that our bullwinkle alleles do not affect the dorsoventral polarity of the oocyte and thus must be affecting the follicle cell migrations in some other way. In addition, the embryos that develop from bullwinkle mothers are bicaudal. A KINESIN:beta-GALACTOSIDASE fusion protein is correctly localized to the posterior pole of bullwinkle oocytes during stage 9. Thus, the microtubule structure of the oocyte and general transport along it do not appear to be disrupted prior to cytoplasmic streaming. Unlike other bicaudal mutants, oskar mRNA is localized correctly to the posterior pole of the oocyte at stage 10. By early embryogenesis, however, some oskar mRNA is mislocalized to the anterior pole. Consistent with the mislocalization of oskar mRNA, a fraction of the VASA protein and nanos mRNA are also mislocalized to the anterior pole of bullwinkle embryos. Mislocalization of nanos mRNA to the anterior is dependent on functional VASA protein. Although the mirror-image segmentation defects appear to result from the action of the posterior group genes, germ cells are not formed at the anterior pole. The bicaudal phenotype is also germ-line dependent for bullwinkle. We suspect that BULLWINKLE interacts with the cytoskeleton and extracellular matrix and is necessary for gene product localization and cell migration during oogenesis after stage 10a.

Distribution of tudor protein in the Drosophila embryo suggests separation of functions based on site of localization

Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 207-219 ◽  
Author(s):  
A. Bardsley ◽  
K. McDonald ◽  
R.E. Boswell
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Posterior Pole ◽  
Drosophila Embryo ◽  
Normal Functioning ◽  
Polar Granules ◽  
Pole Cells

Mutations in the tudor locus of Drosophila affect two distinct determinative processes in embryogenesis; segmentation of the abdomen and determination of the primordial germ cells. The distribution of tudor protein during embryogenesis, and the effect of various mutations on its distribution, suggest that tudor protein may carry out these functions separately, based on its location in the embryo. The protein is concentrated in the posterior pole cytoplasm (germ plasm), where it is found in polar granules and mitochondria. Throughout the rest of the embryo, tudor protein is associated with the cleavage nuclei. Mutations in all maternal genes known to be required for the normal functioning of the germ plasm eliminate the posterior localization of tudor protein, whereas mutations in genes required for the functioning of the abdominal determinant disrupt the localization around nuclei. Analysis of embryos of different maternal genotypes indicates that the average number of pole cells formed is correlated with the amount of tudor protein that accumulates in the germ plasm. Our results suggest that tudor protein localized in the germ plasm is instrumental in germ cell determination, whereas nuclear-associated tudor protein is involved in determination of segmental pattern in the abdomen.

Anterior determinants in embryos of Chironomus samoensis: characterization by rescue bioassay

Development ◽  
1988 ◽  
Vol 104 (1) ◽  
pp. 61-75 ◽  
Author(s):  
A. Elbetieha ◽  
K. Kalthoff
Keyword(s):  
Xenopus Oocytes ◽  
Normal Development ◽  
Posterior Pole ◽  
Mirror Image ◽  
Maximum Efficiency ◽  
Phylogenetic Distance ◽  
Anterior Pole ◽  
Polyadenylated Rna ◽  
Pyrimidine Bases ◽  
Blastoderm Stage

Embryos of Chironomus samoensis are programmed, by anterior u.v. irradiation, to form the abnormal body pattern ‘double abdomen’. Most double abdomen embryos show a mirror-image duplication of abdominal segments in the absence of cephalic or thoracic segments. Such embryos can be ‘rescued’, i.e. restored to normal development, by microinjection of cytoplasm or RNA from unirradiated donor embryos. Most of the rescued embryos look completely normal and many of them hatch spontaneously. The rescuing activity decreases from the anterior to the posterior pole in the donor cytoplasm and must be delivered near the anterior pole of the recipient for maximum efficiency. Rescuing activity is present in total RNA extracted from whole, unirradiated embryos. Upon fractionation, the activity is associated with poly(A)+ RNA, with LiCl precipitate depleted of RNA smaller than 250 nucleotides (nt) and with a sucrose gradient fraction depleted of RNA larger than 500 nt. Corresponding fractions of RNA from Xenopus oocytes have no rescuing activity. The activity of Chironomus RNA is sensitive to u.v. irradiation with low fluence affecting less than 2% of the pyrimidine bases. Rescuing activity is present in cytoplasm until the blastoderm stage but disappears earlier from poly(A)+ RNA. Rescuing activity is also present, and localized, in cytoplasm of embryos from two related dipterans, Smittia sp. and Drosophila melanogaster, although the extent of rescue observed in Chironomus decreases with the phylogenetic distance between donor and recipient. The results of these and previous experiments indicate that dipteran embryos contain localized RNP particles acting as anterior determinants. In Chironomus, the activity of these particles seems to depend on the integrity of polyadenylated RNA of about 250 to 500 nt length.

The development of the egg of Didymuria cuilescens (Phasmatodea : Phasmatidae : Podacanthinae) - embryology and determination of the stage at which first diapause occurs

1970 ◽  
Vol 18 (2) ◽  
pp. 155 ◽  
Author(s):  
GO Bedford
Keyword(s):  
Instar Nymph ◽  
Posterior Pole ◽  
Anterior Pole ◽  
Warm Temperature ◽  
Continue Development ◽  
First Instar

Development of the egg of D. violescens commences as nuclei multiply and congregate at the posterior pole (stage 1A). A germ disk then forms which elongates and becomes segmented as it turns anticlockwise on the surface of the yolk. Anatrepsis is completed when the tail end of the embryo reaches almost halfway to the anterior pole on the micropylar side of the egg. Katatrepsis commences as the embryo moves head-first around the posterior pole and continues to differentiate. The process is completed when the head of the pharate first-instar nymph comes to rest beneath the operculum at the anterior pole of the egg. Eggs kept at a constant warm temperature enter first diapause when there are numerous nuclei at the posterior pole (stage 1A of embryology), and if held under these conditions for a prolonged period they may emerge from diapause irregularly and continue development. In the field eggs develop continuously but slowly, suggesting that diapause and embryogenesis may proceed together at temperatures favourable to both.

Anterior Movement of the Crystalline Lens in the Process of Accommodation in Children

2007 ◽  
Vol 17 (4) ◽  
pp. 515-520 ◽  
Author(s):  
B.J. Kaluzny
Keyword(s):  
Refractive Error ◽  
Axial Length ◽  
Crystalline Lens ◽  
Posterior Pole ◽  
Anterior Pole ◽  
Forward Movement ◽  
Ophthalmic Examination ◽  
Lens Thickness ◽  
Lens Position ◽  
Refractive Status

Purpose To investigate changes of crystalline lens position during accommodation in children with emmetropia, myopia, and hyperopia. Methods A total of 188 children (372 eyes) from 4 to 19 years old (mean age 11.3±4.43) with cycloplegic refractive error within a range +9.00 D to −9.00 D were enrolled. After a general ophthalmic examination, ultrasound biometry was performed, with the eye at a maximal accommodative effort. Cycloplegia was induced by triple installation of 1% tropicamide drops and 30 minutes later the biometric examination was repeated. Results In emmetropic eyes in the process of accommodation, the anterior pole of the crystalline lens moved forward by 0.144±0.14 mm (p ≤ 0.001); the position of the posterior pole did not change. In myopic eyes, the anterior pole moved forward by 0.071±0.13 mm (p≤0.001) and the posterior pole moved backward by 0.039±0.10 mm (p=0.003). In hyperopic eyes, the whole lens translocated anteriorly: anterior pole moved forward by 0.242±0.16 mm (p≤ 0.001) and posterior pole moved forward by 0.036±0.09 mm (p≤0.001). Differences among emmetropia, myopia, and hyperopia were statistically significant. Forward movement of the posterior pole correlated with a low axial length of the eye, and also with plus refractive error and with a smaller accommodative increase of lens thickness. Conclusions In children, accommodative changes of the crystalline lens position depend on refractive status.

scholarly journals Identification of a component of Drosophila polar granules

Development ◽  
1988 ◽  
Vol 103 (4) ◽  
pp. 625-640 ◽  
Author(s):  
B. Hay ◽  
L. Ackerman ◽  
S. Barbel ◽  
L.Y. Jan ◽  
Y.N. Jan
Keyword(s):  
Germ Line ◽  
Posterior Pole ◽  
Nuclear Bodies ◽  
Maternal Origin ◽  
Pole Cell ◽  
Polar Granules ◽  
Early Embryos ◽  
Biochemical Studies ◽  
Males And Females ◽  
Pole Cells

Information necessary for the formation of pole cells, precursors of the germ line, is provided maternally and localized to the posterior pole of the Drosophila egg. The maternal origin and posterior localization of polar granules suggest that they may be associated with pole cell determinants. We have generated an antibody (Mab46F11) against polar granules. In oocytes and early embryos, the Mab46F11 antigen is sharply localized to the posterior embryonic pole. In pole cells, it becomes associated with nuclear bodies within, and nuage around, the nucleus. Immunoreactivity remains associated with cells of the germ line throughout the life cycle of both males and females. This antibody recognizes a 72–74 × 10(3) Mr protein and is useful both as a pole lineage marker and in biochemical studies of polar granules.

scholarly journals An 1 H NMR determination of the three-dimensional structures of mirror-image forms of a Leu-5 variant of the trypsin inhibitor from Ecballium elaterium (EETI-II)

1994 ◽  
Vol 3 (2) ◽  
pp. 291-302 ◽  
Author(s):  
Katherine J. Nielsen ◽  
Dianne Alewood ◽  
John Andrews ◽  
Stephen B.H. Kent ◽  
David J. Craik
Keyword(s):  
Trypsin Inhibitor ◽  
Three Dimensional ◽  
Mirror Image ◽  
H Nmr

Mirror-Image Discrimination: A Purely Perceptual Measurement with Phi Motion

1974 ◽  
Vol 38 (3) ◽  
pp. 823-829 ◽  
Author(s):  
Thomas S. Ball
Keyword(s):  
Measurement Procedure ◽  
Mirror Image ◽  
Unique Contribution ◽  
Perceptual Constancy ◽  
Discrimination Ability ◽  
Conventional Tests

Mirror-image forms were used as phi stimuli in a measurement procedure rendered automatically and compellingly meaningful through the unique contribution of perceptual constancy to the determination of the threshold for phi. Because phi responses are based on unlearned behavior, the pretraining required on conventional tests is eliminated, and a purer measurement of discrimination ability is attained. Using the phi technique, it was found that a group of 12 5-yr.-olds could discriminate like-oriented from mirror-image stimuli as well as did 12 adults.

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