The Rhodnius testis: hormonal effects on germ cell division

1975 ◽  
Vol 53 (11) ◽  
pp. 1682-1689 ◽  
Author(s):  
J. B. Dumser ◽  
K. G. Davey
Keyword(s):  
Cell Division ◽  
Germ Cell ◽  
Juvenile Hormone ◽  
Mitotic Index ◽  
Methyl Ether ◽  
Meiotic Prophase ◽  
Hormone Production ◽  
Natural Induction ◽  
Juvenile Hormone Mimic ◽  
Metaphase Accumulation

The spermatogonial cells of the Rhodnius testis exhibit a basal level of division activity in the absence of morphogenetic hormones. Ecdysone, naturally induced by feeding or injected in physiological doses, approximately doubles the mitotic index as measured by colchicine-metaphase accumulation. Juvenile hormone production in the molting larvae or application of juvenile hormone mimic farnesyl methyl ether abolishes the ecdysone-stimulated increase in mitotic index, but has no effect on the basal level. Similar results are obtained in fed and unfed decapitates, and in surgically manipulated insects. In contrast, natural induction of ecdysone secretion is shown to be ineffective in altering the duration of the meiotic prophase.

Hormonal control of ovarian development and metamorphosis in Malacosoma pluviale

1969 ◽  
Vol 47 (5) ◽  
pp. 917-920 ◽  
Author(s):  
T. S. Sahota
Keyword(s):  
Juvenile Hormone ◽  
Adult Development ◽  
Methyl Ether ◽  
Topical Application ◽  
Ovarian Development ◽  
Hormonal Control ◽  
Juvenile Hormone Mimic

Simplified preparations, such as isolated abdomens, were used to study the effect of farnesyl methyl ether (a juvenile hormone mimic) and ecdysone on ovarian development and adult development in Malacosoma pluviale. Untreated isolated abdomens showed very limited ovarian development and failed to form imaginal cuticle, thus indicating a lack of adult development. Topical application of farnesyl methyl ether to the isolated abdomens blocked the ovarian development completely and no adult development ensued either. Both adult development and ovarian development of the isolated abdomens were stimulated by ecdysone injections. Thus, adult development and ovarian development in M. pluviale seem to be closely related.

The Rhodnius testis: hormones, differentiation of the germ cells, and duration of the molting cycle

1975 ◽  
Vol 53 (11) ◽  
pp. 1673-1681 ◽  
Author(s):  
J. B. Dumser ◽  
K. G. Davey
Keyword(s):  
Cell Division ◽  
Germ Cell ◽  
Juvenile Hormone ◽  
Germ Cells ◽  
Fourth Instar ◽  
Fourth Stage ◽  
Molting Cycle ◽  
Male Germ Cells ◽  
Germ Cell Development ◽  
Species Specific

Allatectomy of third- and fourth-stage Rhodnius larvae results in the production of precocious adults at the succeeding molt. When the allatectomy is performed on fourth-instar larvae, the testes of which contain spermatocysts of approximately 26 cells, spermatozoa are evident in the testis of the resulting precocious adult. If the allatectomy is performed on third-instar larvae, the testes of which contain spermatocysts of approximately 24 cells, the precocious adult never shows germ cell development beyond the early spermatocyte (28) stage, in spite of extensive metamorphosis of mesodermal and ectodermal structures. These results support the view that differentiation of the male germ cells in insects is inflexibly tied to a species-specific division sequence, and thus not directly manipulable by morphogenetic hormones. Evidence is also presented that the presence or absence of juvenile hormone influences the duration of the molt and hence the available time for germ cell division within each instar.

scholarly journals Automated and customizable quantitative image analysis of whole Caenorhabditis elegans germlines

Genetics ◽  
2021 ◽  
Author(s):  
Erik Toraason ◽  
Victoria L Adler ◽  
Nicole A Kurhanewicz ◽  
Acadia DiNardo ◽  
Adam M Saunders ◽  
...  
Keyword(s):  
Image Analysis ◽  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Meiotic Prophase ◽  
Quantitative Image Analysis ◽  
Dna Breaks ◽  
C Elegans ◽  
Quantitative Image ◽  
Cytological Features ◽  
Single Nucleus

Abstract Arranged in a spatial-temporal gradient for germ cell development, the adult germline of Caenorhabditis elegans is an excellent system for understanding the generation, differentiation, function, and maintenance of germ cells. Imaging whole C. elegans germlines along the distal-proximal axis enables powerful cytological analyses of germ cell nuclei as they progress from the pre-meiotic tip through all the stages of meiotic prophase I. To enable high-content image analysis of whole C. elegans gonads, we developed a custom algorithm and pipelines to function with image processing software that enables: (1) quantification of cytological features at single nucleus resolution from immunofluorescence images; and (2) assessment of these individual nuclei based on their position within the germline. We show the capability of our quantitative image analysis approach by analyzing multiple cytological features of meiotic nuclei in whole C. elegans germlines. First, we quantify double-strand DNA breaks (DSBs) per nucleus by analyzing DNA-associated foci of the recombinase RAD-51 at single-nucleus resolution in the context of whole germline progression. Second, we quantify the DSBs that are licensed for crossover repair by analyzing foci of MSH-5 and COSA-1 when they associate with the synaptonemal complex during meiotic prophase progression. Finally, we quantify P-granule composition across the whole germline by analyzing the colocalization of PGL-1 and ZNFX-1 foci. Our image analysis pipeline is an adaptable and useful method for researchers spanning multiple fields using the C. elegans germline as a model system.

scholarly journals The effect of a juvenile hormone mimic, methoprene, against mosquito larvae

1975 ◽  
Vol 26 (2-3) ◽  
pp. 105-111 ◽  
Author(s):  
Kazuo BUEI ◽  
Sumiyo ITO ◽  
Takashi YAMADA ◽  
Shinichi GAMO ◽  
Masaaki KATO
Keyword(s):  
Juvenile Hormone ◽  
Mosquito Larvae ◽  
Juvenile Hormone Mimic

scholarly journals The Dynamics of Cell Division in Some Local Potato Varieties Cultivated in Vitro on Micropropagation Medium

2012 ◽  
Vol 45 (3) ◽  
pp. 71-78
Author(s):  
Iustina Brînduşa Ciobanu ◽  
Dana Constantinovici ◽  
L. Creţu
Keyword(s):  
Solanum Tuberosum ◽  
Cell Division ◽  
Mitotic Index ◽  
Accumulation Rate ◽  
Solanum Tuberosum L ◽  
In Vitro Cultures ◽  
Local Varieties ◽  
Skoog Medium ◽  
Murashige Skoog

Abstract This study was performed to reveal the changes in cell division, as a result of the prolonged period of subculture on micropropagation medium, of five local varieties of Solanum tuberosum L. maintained on in vitro collection at Suceava Genebank, Romania. For this purpose it was used the Murashige-Skoog medium (MS- 1962) with addition of 40 g/l sucrose, and 6 mg/l daminozide. The effect of prolonged period of subculture up to two and 12 months was expressed as mitotic index and frequency of cells with abnormal division. Mitotic index ranged from 20.1 to 22.1% after 12 days, between 15.5 - 17.7% after two months and between 17.7 - 19.2% after 12 months of subculture. The results obtained showed that the frequency of aberrant cells increased with the preservation time on the in vitro cultures and their accumulation rate depended on the genotype. Were identified interphases with micronuclei, metaphases with retarded chromosomes, ana-telophases with chromosomal bridges, retarded chromosomes and chromosomal fragments, but their percentage was low in all the genotypes.

The fusome organizes the microtubule network during oocyte differentiation in Drosophila

Development ◽  
2000 ◽  
Vol 127 (19) ◽  
pp. 4253-4264 ◽  
Author(s):  
N.C. Grieder ◽  
M. de Cuevas ◽  
A.C. Spradling
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Meiotic Prophase ◽  
Crucial Role ◽  
Skeletal Structure ◽  
Network Organization ◽  
Microtubule Network ◽  
Complex Process ◽  
Gamma Tubulin ◽  
Oocyte Differentiation

Differentiation of the Drosophila oocyte takes place in a cyst of 16 interconnected germ cells and is dependent on a network of microtubules that becomes polarized as differentiation progresses (polarization). We have investigated how the microtubule network polarizes using a GFP-tubulin construct that allows germ-cell microtubules to be visualized with greater sensitivity than in previous studies. Unexpectedly, microtubules are seen to associate with the fusome, an asymmetric germline-specific organelle, which elaborates as cysts form and undergoes complex changes during cyst polarization. This fusome-microtubule association occurs periodically during late interphases of cyst divisions and then continuously in 16-cell cysts that have entered meiotic prophase. As meiotic cysts move through the germarium, microtubule minus ends progressively focus towards the center of the fusome, as visualized using a NOD-lacZ marker. During this same period, discrete foci rich in gamma tubulin that very probably correspond to migrating cystocyte centrosomes also associate with the fusome, first on the fusome arms and then in its center, subsequently moving into the differentiating oocyte. The fusome is required for this complex process, because microtubule network organization and polarization are disrupted in hts(1) mutant cysts, which lack fusomes. Our results suggest that the fusome, a specialized membrane-skeletal structure, which arises in early germ cells, plays a crucial role in polarizing 16-cell cysts, at least in part by interacting with microtubules and centrosomes.

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