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Annual Review of Entomology 1992
Review
Topics: Animals; Egg Proteins; Endocytosis; Insecta; Oocytes; Receptors, Cell Surface; Vitellogenesis; Vitellogenins
PubMed: 1311540
DOI: 10.1146/annurev.en.37.010192.001245 -
Insect Biochemistry and Molecular... Nov 2018Juvenile hormone (JH) is known to promote cell polyploidization for insect vitellogenesis and egg production, but the underlying mechanisms remain poorly understood....
Juvenile hormone (JH) is known to promote cell polyploidization for insect vitellogenesis and egg production, but the underlying mechanisms remain poorly understood. Using the migratory locust Locusta migratoria as a model system, we report here that the expression of cyclin-dependent kinase 6 (Cdk6) and adenovirus E2 factor-1 (E2f1), the core mediators in cell cycle progression is regulated by JH and its receptor Methoprene-tolerant (Met). JH acts through its receptor complex comprised of Met and Taiman to directly activate the transcription of Cdk6 and E2f1. Depletion of Cdk6 or E2f1 results in significantly decreased ploidy, precocious mitotic entry and increased cell numbers in the fat body, accompanied by substantial reduction of Vitellogenin gene expression, blocked ovarian growth and arrested oocyte maturation. These findings indicate a crucial role of Cdk6 and E2f1 in JH-regulated polyploidization and vitellogenesis as well as a novel regulatory machinery for endocycling in insects.
Topics: Animals; Cyclin-Dependent Kinase 6; E2F1 Transcription Factor; Fat Body; Female; Grasshoppers; Insect Proteins; Juvenile Hormones; Polyploidy; Transcription, Genetic; Vitellogenesis
PubMed: 30205150
DOI: 10.1016/j.ibmb.2018.09.002 -
Bulletin of Entomological Research Apr 2017Insulin-like peptides (ILPs) act through a conserved insulin signaling pathway and play crucial roles in insect metabolism, growth, reproduction, and aging. Application...
Insulin-like peptides (ILPs) act through a conserved insulin signaling pathway and play crucial roles in insect metabolism, growth, reproduction, and aging. Application of bovine insulin is able to increase vitellogenin (Vg) mRNA and protein levels in female insects. Here, we first show that injection of bovine insulin into previtellogenic Chrysopa septempunctata female adults promoted ovarian growth, increased Vg protein abundance, elevated reproductive performance, and enhanced protease activity. These data suggested that ILPs play crucial roles in reproductive regulation of the green lacewing, C. septempunctata.
Topics: Animals; Cattle; Female; Insect Proteins; Insecta; Insulin; Oviposition; Peptide Hydrolases; Peptides; Pest Control, Biological; Vitellogenesis; Vitellogenins
PubMed: 27573159
DOI: 10.1017/S0007485316000742 -
Veterinary Parasitology Nov 2021Rhipicephalus microplus is an important cattle tick, and resistant strains to synthetic compounds have been widespread. The combined effects of different essential oil...
Effects of acaricidal essential oils from Lippia sidoides and Lippia gracilis and their main components on vitellogenesis in Rhipicephalus microplus (Canestrini, 1888) (Acari: Ixodidae).
Rhipicephalus microplus is an important cattle tick, and resistant strains to synthetic compounds have been widespread. The combined effects of different essential oil compounds enhance biological activity and reduce selection for the development of target organism resistance. Essential oils of two different genotypes of each of Lippia sidoides and Lippia gracilis and their main components, the isomers thymol and carvacrol, have acted as acaricides against R. microplus. Little is known about the effects of the essential oils of L. sidoides and L. gracilis and thymol and carvacrol on the morphophysiology of R. microplus ovaries. This study aimed to identify the morphological changes in the ovaries of R. microplus females treated with essential oils from two different genotypes of each of L. sidoides (102 and 103) and L. gracilis (106 and 201) and the terpenes thymol and carvacrol through histological techniques. The LC and LC of essential oils and thymol and carvacrol were used for Adult Immersion Test (AIT) with groups of five fully engorged females of R. microplus. A negative control (DMSO 3% solution) was performed. Seven days after the AIT, the ticks were dissected to collect ovaries and their histologic analysis. Only the group treated with the essential oil of L. gracilis genotype 106 at the LC had no change compared with the control. The other groups showed the following changes in oocytes I to V: vacuolation, chorion deformation, disorganization of yolk granules, and irregularities at the cell periphery, causing incomplete process of vitellogenesis. Thus, the essential oils tested in this study may be potent products for the control of cattle ticks and thereby preventing further life cycles.
Topics: Acaricides; Animals; Ixodidae; Larva; Lippia; Oils, Volatile; Plant Oils; Rhipicephalus; Vitellogenesis
PubMed: 34583144
DOI: 10.1016/j.vetpar.2021.109584 -
Memorias Do Instituto Oswaldo Cruz 1987Insect vitellogenesis involves coordinated activities of the fat body and oocytes. We have studied these activities at the cellular level in the mosquito. During each...
Insect vitellogenesis involves coordinated activities of the fat body and oocytes. We have studied these activities at the cellular level in the mosquito. During each vitellogenic cycle, the fat body undergoes three successive stages: 1) proliferation of biosynthetic organelles, 2) vitellogenin synthesis, 3) termination of vitellogenin synthesis and degradation of biosynthetic organelles by lysosomes. Analysis with monoclonal antibodies and radiolabelling demonstrated that the mosquito yolk protein consists of two subunits (200-kDa and 65-kDa). Both subunits are glycosylated, their carbohydrate moieties are composed of high-mannose oligosaccharides. The yolk protein subunits are derived from a single 220 kDa precursor detected by an in vitro translation. Oocytes become competent to internalize proteins as a result of juvenile hormone-mediated biogenesis of endocytotic organelles. The yolk protein is then accumulated by receptor-mediated endocytosis. A pathway of the yold protein and factors determining its routing in the oocyte have been studied.
Topics: Animals; Culicidae; Vitellogenesis; Vitellogenins
PubMed: 2908129
DOI: 10.1590/s0074-02761987000700019 -
Effects of methoprene, nonylphenol, and estrone on the vitellogenesis of the mysid Neomysis integer.General and Comparative Endocrinology Jun 2006The induction of the female-specific protein, vitellogenin, in male fish is a well-established endpoint to assess exposure to estrogen-like chemicals. The use of... (Comparative Study)
Comparative Study
The induction of the female-specific protein, vitellogenin, in male fish is a well-established endpoint to assess exposure to estrogen-like chemicals. The use of vitellogenesis as a biomarker for xenobiotic exposure in egg-laying invertebrates, however, is still relatively unexplored. Recently, we developed a quantitative enzyme-linked immunosorbent assay (ELISA) for vitellin in Neomysis integer (Crustacea: Mysidacea) to study mysid vitellogenesis and its potential disruption by xenobiotics. In this study, gravid mysids were exposed to methoprene, nonylphenol, and estrone for 96 h. All methoprene-exposed (0.01, 1, and 100 microg/L) animals had lower vitellin levels compared to the control animals, though this effect was not statistically significant. Exposure to nonylphenol resulted in significantly induced vitellin levels in the lowest exposure concentration (0.01 microg/L), whereas no effects were observed at higher concentrations. Estrone significantly decreased vitellin levels at the highest test concentration (1 microg/L). These results indicate that mysid vitellogenesis can be disrupted following chemical exposure. Difficulties in the interpretation of the observed chemical-specific and concentration-specific responses in this study highlight the need for a better understanding of hormone regulation of crustacean vitellogenesis.
Topics: Animals; Crustacea; Endocrine Disruptors; Estrone; Female; Methoprene; Phenols; Vitellogenesis
PubMed: 16466727
DOI: 10.1016/j.ygcen.2005.12.021 -
General and Comparative Endocrinology Nov 2006In fish, vitellogenin is an important nutritional precursor protein produced solely in the liver and released into the blood where it binds calcium. In the gilthead sea...
In fish, vitellogenin is an important nutritional precursor protein produced solely in the liver and released into the blood where it binds calcium. In the gilthead sea bream (Sparus auratus) 17beta-Estradiol (E2) plays an important role in the synthesis of vitellogenin, but also the pituitary hormones prolactin (PRL) and growth hormone (GH) can stimulate vitellogenin induction in fish. Considering the emerging involvement of PTHrP in fish calcium metabolism and the importance of calcium regulation in reproduction, we investigated the possible role of PTHrP in vitellogenesis. E2-naïve and E2-primed sea bream hepatocytes were used in an in vitro primary hepatocyte culture and stimulated with a recombinant sea bream PTHrP (sbPTHrP) to establish the contribution of sbPTHrP alone or in combination with E2 to the regulation of hepatic vitellogenin synthesis. Hepatocytes stimulated solely with sbPTHrP were not affected in their vitellogenesis. However, in hepatocytes stimulated with E2 in combination with sbPTHrP a higher vitellogenin production was seen than with E2 alone. It is concluded that sbPTHrP has a potentiating effect on estradiol stimulation of vitellogenin production by sea bream hepatocytes. The sea bream provides a unique model where vitellogenesis regulation can be studied on E2-naïve liver cells, both in vivo and in vitro.
Topics: Animals; Calcium; Cells, Cultured; Drug Implants; Drug Synergism; Estradiol; Female; Hepatocytes; Male; Parathyroid Hormone-Related Protein; Recombinant Proteins; Sea Bream; Vitellogenesis; Vitellogenins
PubMed: 16839552
DOI: 10.1016/j.ygcen.2006.05.016 -
Aquatic Toxicology (Amsterdam,... May 2012Some environmental compounds are known to have anti-oestrogenic activity and their modes of action (MoA) are believed to include competitive inhibition of 17β-estradiol...
Some environmental compounds are known to have anti-oestrogenic activity and their modes of action (MoA) are believed to include competitive inhibition of 17β-estradiol (E2) binding to the oestrogen receptor (ER) or interference with ER-dependent processes. The presence of multiple compounds having the same MoA may cause concern, as exposure to multiple compounds at concentrations below their threshold for effect can interact with cellular targets to cause effects in combination. The combined effect of mixtures can be assessed using prediction models such as concentration addition (CA) and independent action (IA). The objective of the present study was to determine if the CA and IA prediction models could accurately characterise the combined effects of mixtures of ER antagonists in rainbow trout (Oncorhynchus mykiss) hepatocytes using the ER-mediated production of the oestrogenic biomarker vitellogenin (Vtg) as a screening assay. Model anti-oestrogens (4-hydroxytamoxifen and ZM 189.154) and environmentally relevant compounds (PCBs and PAHs) were tested to ensure inclusion of compounds from different chemical classes and with different MoAs. All eleven tested compounds had the ability to reduce the in vitro E2-induced production of Vtg in a concentration-dependent manner. The potency of the tested compounds differed by four orders of magnitude based on the concentrations for 50% inhibition (IC(50)). The observed order of potency was 2,3,7,8-tetrachlorodibenzo-p-dioxin>4-hydroxytamoxifen>3,3',4,4',5-pentachlorobiphenyl>benzo(k)fluoranthene>3,3',4,4'-tetrachlorobiphenyl>β-naphthoflavone>ZM 189.154>indeno[1,2,3-cd]pyrene>benzo(b)fluoranthene>benzo(a)pyrene>benzo(a)anthracene. The CA and IA models were able to predict the combined effects of mixtures of ER antagonists with similar MoA. The mixtures of certain ER-antagonists with different and/or complex MoA caused deviations from both the CA and the IA model by causing higher anti-oestrogenic activity than predicted from the potency of the compounds alone. The rationale for these deviations warrants additional studies to assess the potential impacts on the health of organisms.
Topics: Animals; Cells, Cultured; Estrogen Antagonists; Hepatocytes; High-Throughput Screening Assays; Models, Biological; Oncorhynchus mykiss; Vitellogenesis; Water Pollutants, Chemical
PubMed: 22366424
DOI: 10.1016/j.aquatox.2012.01.023 -
Reproductive Biology and Endocrinology... Mar 2010When European silver eels (Anguilla anguilla) venture into the Atlantic Ocean for their 6,000 km semelparous spawning run to the Sargasso Sea, they are still in a... (Comparative Study)
Comparative Study
BACKGROUND
When European silver eels (Anguilla anguilla) venture into the Atlantic Ocean for their 6,000 km semelparous spawning run to the Sargasso Sea, they are still in a prepubertal stage. Further sexual development appears to be blocked by dopaminergic inhibition of hypothalamus and pituitary activity. Recently, we found that swimming for several weeks in freshwater stimulated the incorporation of fat droplets in the oocytes. So, it was hypothesized that long term swimming in seawater would release the inhibition further and would also stimulate the production of vitellogenin by the liver.
METHODS
For this study a swim-flume was constructed to allow simulated migration of migratory female silver eels for 3 months (1,420 km) in natural seawater at 20 degrees C. Primers were designed for polymerase chain reactions to measure the mRNA expression of estrogen receptor 1 (esr1), vitellogenin1 (vtg1) and vitellogenin2 (vtg2) genes in the liver of European female silver eels.
RESULTS
In comparison to resting eels, swimming eels showed a diminished expression of esr1, vtg1 and vtg2 in the liver. They also had lower plasma calcium (Ca; indicative of vitellogenin) levels in their blood. This showed that vitellogenesis is more strongly suppressed in swimming than in resting eels. However, when eels were subsequently stimulated by 3 weekly carp pituitary extract injections, the expression of the same genes and plasma levels of Ca strongly increased in both groups to similar levels, thus equalizing the initial differences between resting and swimming.
CONCLUSIONS
It is concluded that vitellogenesis remains suppressed during resting and even more during swimming. The fact that swimming stimulates fat deposition in the oocytes but suppresses vitellogenesis indicates that these events are separated in nature and occur sequentially. Swimming-suppressed vitellogenesis may imply that in nature eels undergo vitellogenesis and final maturation near or at the spawning grounds.
Topics: Animal Migration; Animals; Calcium; Down-Regulation; Eels; Estrogen Receptor alpha; Female; Gene Expression Regulation; Liver; Rest; Seawater; Swimming; Vitellogenesis; Vitellogenins
PubMed: 20302623
DOI: 10.1186/1477-7827-8-27 -
Developmental Biology (New York, N.Y. :... 1988
Review
Topics: Animals; DNA-Binding Proteins; Female; Gene Expression Regulation; Hormones; Male; Multigene Family; Receptors, Estrogen; Transcription, Genetic; Up-Regulation; Vitellogenesis; Vitellogenins; Xenopus
PubMed: 3077977
DOI: 10.1007/978-1-4615-6817-9_9