Development of the germ cells and reproductive primordia in male and female embryos of Rhodnius prolixus Stål (Hemiptera: Reduviidae)

Newly deposited eggs of Rhodnius prolixus lack a visible pole plasm and require 14 days to develop at 27 °C and 70% RH. The first germ cells originate at 9% of embryogenesis by asynchronous mitosis of blastodermal cells behind the germ Anlage at the posterior pole of the egg. From 9 to 17%, these proliferate to a mean of 270 cells and, from 13 to 18%, migrate forward over the dorsal surface of the mesoderm and lodge in abdominal segments 3–7. Between 22 and 30%, they shift laterally and segregate into three or four paired clumps between segments 3 and 4, 4 and 5, 5 and 6, and, sometimes, 6 and 7 and, from 30 to 37%, gradually assemble into a continuous longitudinal mass on either side of segments 3–6, where they begin to associate with mesodermal cells. Between 37 and 46%, these collect between (males) and around the germ cells to form the rudiments of the terminal filaments (females), inner and outer gonadal sheaths, interstitial cells (males), and primary exit ducts. Dorsally situated sheath cells then invaginate ventrally into each gonadal rudiment, partitioning it into seven compartments, each containing a mean of 15 oogonia or 16 spermatogonia. These seem to fuse into a rosette, at least in females, but do not begin to divide again until after hatch. Excluded germ cells lodge within the rudiments of one or both exit ducts. The evolutionary and functional aspects of our findings are addressed and new observations are presented on the mechanism of anatrepsis.

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Memoirs: The Early Embryonic Development of Rhodnius Prolixus (Hemiptera, Heteroptera)

Journal of Cell Science ◽

10.1242/jcs.s2-78.309.71 ◽

1935 ◽

Vol s2-78 (309) ◽

pp. 71-90

Author(s):

HELEN MELLANBY

Keyword(s):

Relative Humidity ◽

Embryonic Development ◽

Early Development ◽

Constant Temperature ◽

Germ Cells ◽

Rhodnius Prolixus ◽

Posterior Pole ◽

Early Embryonic Development ◽

Temperature And Humidity ◽

Cent Relative Humidity

1. Eggs of Rhodnius prolixus were incubated at constant temperature and humidity (21° C. and 90 per cent, relative humidity). Eighty-five per cent, was the lowest record of the controls hatched successfully under these conditions. 2. The processes of maturation and fertilization were not studied. 3. Cleavage begins 12-13 hours after incubation. At 25 hours there are 32 nuclei. Yolk-cells are derived from cleavage nuclei, and they multiply by mitosis up to 50 hours. Blastoderm formation is complete after 55-60 hours of incubation. 4. The ventral embryonic rudiment is similar to that of many other insects. As soon as it is formed, germ-cells are budded off at the posterior pole of the egg. 5. The first stage in blastokinesis is fully described. 6. The formation of the mesoderm is by invagination and overgrowth. 7. The endoderm arises from two proliferating areas situated anteriorly and posteriorly. 8. Numerous cells are given off into the yolk during the early development of the embryo. There they disintegrate.

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Protein components of ribonucleoprotein granules from Drosophila germ cells oligomerize and show distinct spatial organization during germline development

Scientific Reports ◽

10.1038/s41598-019-55747-x ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 5

Author(s):

Hieu D. L. Vo ◽

Wahiduzzaman ◽

Samuel J. Tindell ◽

Jimiao Zheng ◽

Ming Gao ◽

...

Keyword(s):

Germ Cells ◽

Spatial Organization ◽

Super Resolution ◽

Posterior Pole ◽

Germline Development ◽

Functional Aspects ◽

Polar Granules ◽

Germ Granules ◽

Protein Components ◽

Multiple Domains

AbstractThe assembly of large RNA-protein granules occurs in germ cells of many animals and these germ granules have provided a paradigm to study structure-functional aspects of similar structures in different cells. Germ granules in Drosophila oocyte’s posterior pole (polar granules) are composed of RNA, in the form of homotypic clusters, and proteins required for germline development. In the granules, Piwi protein Aubergine binds to a scaffold protein Tudor, which contains 11 Tudor domains. Using a super-resolution microscopy, we show that surprisingly, Aubergine and Tudor form distinct clusters within the same polar granules in early Drosophila embryos. These clusters partially overlap and, after germ cells form, they transition into spherical granules with the structural organization unexpected from these interacting proteins: Aubergine shell around the Tudor core. Consistent with the formation of distinct clusters, we show that Aubergine forms homo-oligomers and using all purified Tudor domains, we demonstrate that multiple domains, distributed along the entire Tudor structure, interact with Aubergine. Our data suggest that in polar granules, Aubergine and Tudor are assembled into distinct phases, partially mixed at their “interaction hubs”, and that association of distinct protein clusters may be an evolutionarily conserved mechanism for the assembly of germ granules.

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Barentsz is essential for the posterior localization of oskar mRNA and colocalizes with it to the posterior pole

The Journal of Cell Biology ◽

10.1083/jcb.200105056 ◽

2001 ◽

Vol 154 (3) ◽

pp. 511-524 ◽

Cited By ~ 88

Author(s):

Fredericus J.M. van Eeden ◽

Isabel M. Palacios ◽

Mark Petronczki ◽

Matthew J.D. Weston ◽

Daniel St Johnston

Keyword(s):

Germ Cells ◽

Translational Control ◽

Mrna Localization ◽

Posterior Pole ◽

Rna Transport ◽

Specific Component ◽

Microtubule Cytoskeleton ◽

Transport Complex ◽

Pole Plasm ◽

Null Mutants

The localization of Oskar at the posterior pole of the Drosophila oocyte induces the assembly of the pole plasm and therefore defines where the abdomen and germ cells form in the embryo. This localization is achieved by the targeting of oskar mRNA to the posterior and the localized activation of its translation. oskar mRNA seems likely to be actively transported along microtubules, since its localization requires both an intact microtubule cytoskeleton and the plus end–directed motor kinesin I, but nothing is known about how the RNA is coupled to the motor. Here, we describe barentsz, a novel gene required for the localization of oskar mRNA. In contrast to all other mutations that disrupt this process, barentsz-null mutants completely block the posterior localization of oskar mRNA without affecting bicoid and gurken mRNA localization, the organization of the microtubules, or subsequent steps in pole plasm assembly. Surprisingly, most mutant embryos still form an abdomen, indicating that oskar mRNA localization is partially redundant with the translational control. Barentsz protein colocalizes to the posterior with oskar mRNA, and this localization is oskar mRNA dependent. Thus, Barentsz is essential for the posterior localization of oskar mRNA and behaves as a specific component of the oskar RNA transport complex.

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Memoirs: The Embryonic Development of Trichogramma evanescens, Westw., Monembryonic Egg Parasite of Donacia Simplex, Fab

Journal of Cell Science ◽

10.1242/jcs.s2-62.246.149 ◽

1917 ◽

Vol s2-62 (246) ◽

pp. 149-187

Author(s):

J. BRONTÉ GATENBY

Keyword(s):

Germ Cells ◽

Nuclear Division ◽

Single Case ◽

Dorsal Surface ◽

Posterior Pole ◽

The Body ◽

Egg Mass ◽

Trichogramma Evanescens ◽

Polar Bodies ◽

Blastoderm Stage

(1) Trichogramma evanescens lays its eggs on the egg mass of a beetle, Donacia simplex, a single parasite emerging from one host's egg. (2) The ovum has a large germ cell determinant at its posterior pole, and in segmentation the determinant is divided among the large cells at the posterior pole, which are the germ cells. (3) In the single case found there were two polar bodies. (4) The blastula is fairly normal except for the curious arrangement of the chromatin in the somatic nuclei. (5) Many nucleoli are cast out into the centre of the egg, where they collect till from twenty-five to fifty are present; the mass is then extruded on the periphery of the egg. (6) As the blastoderm grows it broadens without lengthening up to the stage where the germ layers begin to form. (7) About thirty-five nuclei sink inwards from the dorsal surface of the embryo to form endoderm. (8) From the blastoderm stage to that of the gastrula no nuclear division appears to take place. (9) Shortly after the formation of the endoderm amitosis may be found, and from this onwards the number of nuclei increases. (10) The mesoderm seems to be formed from peripheral nuclei, which sink in sporadically; no somites can be made out, nor does any segmental method of formation of the mesoderm occur. (11) The nervous system, stomodæum, and probably proctodæum, are normally formed. (12) The germ cells lie in a pocket formed be several somatic cells, which embrace them. (13) Ordinary mouth parts, tracheæ, heart, and œsophageal valve are wanting; the head has two horn-like mandibular processes, which may assist in scooping forwards the food. (14) The larva does not feed on the food little by little, defecating as it eats; instead, it begins by swallowing all the yolk at once, so that its body becomes enormously distended and stretched. (15) Metameric external segmentation is absent, the body and head being continuous and sac-like.

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METHODS OF QUANTITATIVE EVALUATION OF THE MEIOTIC PATHOLOGY OF MALE AND FEMALE GERM CELLS

CLINICAL AND EXPERIMENTAL MORPHOLOGY ◽

10.31088/2226-5988-2018-26-2-4-12 ◽

2018 ◽

Vol 26 (2) ◽

pp. 4-12

Author(s):

L.F. Kurilo ◽

Keyword(s):

Quantitative Evaluation ◽

Germ Cells ◽

Male And Female

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Reproductive Isolation and Morphogenetic Evolution in Drosophila Analyzed by Breakage of Ethological Barriers

Genetics ◽

10.1093/genetics/147.1.231 ◽

1997 ◽

Vol 147 (1) ◽

pp. 231-242 ◽

Cited By ~ 1

Author(s):

Lucas Sánchez ◽

Pedro Santamaria

Keyword(s):

Reproductive Isolation ◽

Germ Cells ◽

Morphological Analysis ◽

Seminal Fluid ◽

Germ Line ◽

Regulatory Gene ◽

Motile Sperm ◽

Male And Female ◽

Drosophila Yakuba

Abstract This article reports the breaking of ethological barriers through the constitution of soma-germ line chimeras between species of the melanogaster subgroup of Drosophila, which are ethologically isolated. Female Drosophila yakuba and D. teissieri germ cells in a D. melanogaster ovary produced functional oocytes that, when fertilized by D. melanogaster sperm, gave rise to sterile yakuba-melanogaster andteissieri-melanogaster male and female hybrids. However, the erecta-melanogaster and orena-melanogaster hybrids were lethal, since female D. erecta and D. orena germ cells in a D. melanogaster ovary failed to form oocytes with the capacity to develop normally. This failure appears to be caused by an altered interaction between the melanogaster soma and the erecta and orena germ lines. Germ cells of D. teissieri and D. orena in a D. melanogaster testis produced motile sperm that was not stored in D. melanogaster females. This might be due to incompatibility between the teissieri and orena sperm and the melanogaster seminal fluid. A morphological analysis of the terminalia of yakuba-melanogaster and teissieri-melanogaster hybrids was performed. The effect on the terminalia of teissieri-melanogaster hybrids of a mutation in doublesex, a regulatory gene that controls the development of the terminalia, was also investigated.

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