Search results for "Vitellogenesis"
showing 10 items of 16 documents
Effects of two acanthocephalan parasites on the fecundity and pairing status of female Gammarus pulex (Crustacea: Amphipoda)
2002
Acanthocephalan parasites are known to alter the reproductive biology and physiology of their hosts in various ways. In this study we investigated the influence of two acanthocephalan parasites, Pomphorhynchus laevis and Polymorphus minutus, on the fecundity and pairing success of female Gammarus pulex. The results show that P. laevis and P. minutus affect female intermediate host reproduction in different ways. Females infected with P. minutus were totally castrated, whereas those infected with P. laevis only showed reduced fecundity. The oocytes of P. laevis-infected females showed a similar structure to those of uninfected females, although infected females had a higher proportion of ooc…
Can phthalates move into the eggs of the loggerhead sea turtle Caretta caretta? The case of the nests on the Linosa Island in the Mediterranean Sea
2021
During the monitoring of Caretta caretta nests on the island of Linosa, 30 unhatched eggs from four nests were collected to study the presence of phthalates in their three components (shell, yolk, and albumen). Four phthalates, namely diethyl (DEP), dibutyl (DBP), di-(2-ethylhexyl) (DEHP), and dioctyl (DOTP) phthalic acid esters (PAE), which are widely used as additives in plastics, were detected in all egg components. The most frequently found phthalate was DBP, followed by DEHP in eggshell and yolk. Dimethyl- (DMP) and butylbenzyl-phthalate (BBP) were below the limits of detection for all samples. The high total phthalate recorded in the yolk suggests that contamination could arise by vit…
Annelid Coelomic Fluid Proteins
2020
The coelomic cavity is part of the main body plan of annelids. This fluid filled space takes up a considerable volume of the body and serves as an important site of exchange of both metabolites and proteins. In addition to low molecular substances such as amino acids and glucose and lactate, the coelomic fluid contains different proteins that can arise through release from adjacent tissues (intestine) or from secretion by coelomic cells. In this chapter, we will review the current knowledge about the proteins in the annelid coelomic fluid. Given the number of more than 20,000 extant annelid species, existing studies are confined to a relatively few species. Most studies on the oligochaetes …
Imidazole derivative KK-42 reduces ecdysteroid titers and interferes with reproductive processes in adult females of Tenebrio molitor
2004
0048-3575 doi: DOI: 10.1016/j.pestbp.2004.07.004; KK-42, an imidazole derivative considered as potent inhibitor of ecdysteroid biosynthesis, was tested on adult females of Tenebrio molitor. The compound was applied topically (0.1, 1, 5, and 10 μg/insect) on 0- or 2-day-old adult females or added to the culture medium (1 and 10 μM) of ovaries. To test the effect of KK-42 on the reproduction capacity, ovaries were explanted from 2- and 4-day-old females corresponding, respectively, to follicles at the beginning and the end of vitellogenesis. KK-42 treatment reduced the fecundity and the longevity of females, and in addition, it delayed oviposition and affected growth and development of oocyte…
Vitellogenin polypeptide levels in one susceptible and one cadmium-resistant strain of Oncopeltus fasciatus (Heteroptera: Lygaeidae), and its role in…
2005
The heavy metal Cd has recently been shown to have endocrine disrupting activity in different vertebrate species. In the insect Oncopeltus fasciatus, Cd exposure delays ovarian maturation and inhibits vitellogenesis, probably through a reduction in vitellogenin (Vg) polypeptide synthesis. An O. fasciatus strain was selected in the laboratory for Cd resistance with gradually increasing Cd concentrations for 50 generations. Cd-selected (OCdR) insects were 2.7-2.3 times more resistant to chronic exposure to Cd than susceptible (OS) insects. OCdR females showed increased (up to 90%) Vg polypeptide levels in hemolymph. Vg polypeptide synthesis was equally decreased in OCdR and OS females after a…
No evidence of androgenic hormone from the testes of the glowworm, Lampyris noctiluca.
2005
The widely accepted concept, stating that insects have no true sex hormones, and that primary as well as secondary sex characteristics are controlled by the genetic inventory of each single cell, is challenged by the report of Naisse, J. [1966a. Controle endocrinien de la differenciation sexuelle chez l'Insecte Lampyris noctiluca (Coleoptere Malacoderme Lampyride). I. Role androgene des testicules, Arch. Biol. Liege, 77, 139-201] on the discovery of an androgenic hormone in the glowworm, Lampyris noctiluca. This case is of special interest, since it may point to an ancestral mode of sex differentiation in arthropods, considering that androgenic hormones have been discovered and characterize…
Vitellogenin from female and estradiol-stimulated male river lampreys (Lampetra fluviatilis L.)
2001
The influence of estradiol-17β (E2) on vitellogenesis is well documented for a number of oviparous craniates. We have examined the role that estradiol-17β plays in the induction and regulation of vitellogenin synthesis in the maturing European river lamprey, Lampetra fluviatilis. In both females and males the estradiol-17β concentrations in the plasma reached comparable maximum values in March, only a few weeks before spawning. Throughout the spawning run, the vitellogenin titer in the blood of females remains rather constant while the ovary volume increases. In contrast, we never found circulating VTG in untreated male lampreys. The synthesis and secretion of the yolk precursor molecule ca…
Regulation of vitellogenesis in Nereis virens (Annelida: Polychaeta): effect of estradiol-17beta on eleocytes.
2005
Abstract In the marine polychaete Nereis virens , the yolk protein precursor vitellogenin (Vg) is synthesized in specialized coelomic cells (eleocytes) during oogenesis. This process was visualized by immunohistochemistry using antibodies raised against the yolk protein. Transversal sections from male and female worms confirmed that eleocytes from females but not from males produce Vg. In order to investigate the hormonal regulation of Vg synthesis, eleocytes were incubated in vitro with estradiol-17β (E 2 ) at a concentration of 1 μg/l for up to three days. A strong increase in Vg secretion was detected by ELISA in culture media of treated eleocytes from vitellogenic females. In contrast, …
Reproductive, biochemical, physiological, and population responses in perch (Perca fluviatilisL.) and roach (Rutilus rutilusL.) downstream of two ele…
2001
Perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) populations in a state of late vitellogenesis were studied downstream of two pulp and paper mills and at upstream references in southern Lake Saimaa, Finland. The mills used elemental chlorine-free bleaching and activated sludge effluent treatment technologies. The exposure of fish to pulp mill effluents, as measured by concentrations of chlorophenolics in the bile and liver ethoxyresorufin-O-deethylase (EROD) activity, was low and almost similar to the references. Nevertheless, bile resin acid concentrations in exposed perch and roach (260-320 micrograms/ml) and bile beta-sitosterol concentrations in exposed roach (1.5-3.5 microgr…
Effect of temperature on the duration of sensitive period and on the number of photoperiodic cycles required for the induction of reproductive diapau…
2013
Abstract Correct timing of the induction of photoperiodic reproductive diapause has been found to play an important role in the life cycle of several northern insect species. However, even when the environmental conditions are favourable for diapause, the switch to diapause can only take place when the females are in a proper developmental and physiological stage, referred to as the sensitive period (SP) for diapause. We have previously shown that in a northern fly species, Drosophila montana, the developmental pathway of the ovaries (direct maturation vs. diapause) is determined by photoperiodic cues that the females receive after eclosion. Here, we have studied the effects of temperature …