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At least 307 records · Page 17Linked to original sources
PubMed1983

Ultrastructure of the sinus gland and lateral cephalic nerve plexus in the isopod Ligia oceanica (Crustacea Oniscoidea).

Isopod crustaceans have two distinct cephalic neurohemal organs: the sinus gland (SG) and lateral cephalic nerve plexus (LCNP). The present study of Ligia oceanica was designed to ascertain the ultrastructure, during the moulting cycle, of the terminals constituting the SG and LCNP, both of which store and release neurosecretory material, and to trace these terminals to their probable origin in neurosecretory perikarya. The SG was observed to contain four types of terminals (I, II, III, and IV) assigned, on the basis of the appearance of their neurosecretory granules, to four types of neurosecretory cells in the protocerebrum (beta 1, beta 2, B1, and Bu). When the same morphological criteria were applied to the LCNP, two types of terminals were found--III' and IV'. Type III' was thought to originate in the Bp plexus cells and in the B2 cells of the suboesophageal ganglion. The origins of Type IV' terminals were believed to be the Bu and Bm cells of this ganglion. Release from both the GS and LCNP occurred by exocytosis. The discussion attempts to relate the ultrastructural variations observed in the SG and LCNP with existing data on the neuroendocrine regulation of the moult. Such regulation involves the two antagonistic hormones (moult-inhibiting and moult-accelerating) which determine the circulating ecdysteroid level. It is also suggested that the plexus cells are the site of synthesis of a factor controlling the release of the exuviation factor.

Animals↗
PubMed1983

[Masculinization of prepubertal and pubertal females of Sphaeroma serratum Fabr., (Crustacea Isopoda Flabellifera) by implantation of an androgenic gland of pubertal male].

In Sphaeroma serratum, the differentiation of the male external sexual characteristics, as a result of an androgenic gland implant, proceeds more easily in females in vitellogenesis than in immature females. On the contrary, the transformation of the gonads is quicker and more obvious in immature females than in mature ones. This transformation which leads, in all cases, to an inversion of the ovary to a functional testicle able to produce spermatozoa, always occurs without any differentiation of an androgenic gland, contrary to what can be observed with Oniscoïds. The details of the external sexual differentiation of the grafted females can be related to the functioning of a protocerebral neurosecretory center having, as in males, an androinhibitory effect on the androgenic gland implant; the activity of this center, which seems to correspond to the center secreting VIH, would be particularly high with immature females and would become very low--or nonexistent--in females in vitellogenesis.

Androgens↗
PubMed1986

Identification of nonecdysteroid steroids in hemolymph of both male and female Astacus leptodactylus (Crustacea) by gas chromatography-mass spectrometry.

The O-pentafluorobenzyloxime (OPFB)-heptafluorobutyrylester (HFB) derivatives of hemolymph steroid extracts from both male and female Astacus leptodactylus were subjected to negative ion chemical ionization and capillary gas chromatography-mass spectrometry (NCI/GC-MS). Five nonecdysteroid steroids, namely pregnenolone, 17 alpha-hydroxypregnenolone, testosterone, cholesterol, and 6 beta-hydroxyprogesterone were identified. With selected ion monitoring (SIM), indications were found for the presence of four more steroids: androstenedione, 5 alpha-dihydrotestosterone, 11-ketotestosterone, and 11 beta-hydroxytestosterone. The presence of 6 beta-hydroxyprogesterone could only be demonstrated in the female hemolymph. With the technique used, dehydroepiandrosterone, progesterone, 17 alpha-hydroxyprogesterone, and estrogens could not be detected in male or female hemolymph extracts.

17-alpha-Hydroxypregnenolone↗
PubMed1987

Ecdysteroid titers during the molt cycle of Orchestia cavimana (Crustacea, Amphipoda).

Ecdysteroids were analyzed during a molt cycle in adult males of the crustacean Orchestia cavimana; levels were determined in the hemolymph and in whole bodies, using radioimmunoassay. Results show a single and sharp peak at the end of D1 stage, reaching 810 pg eq/microliter in the hemolymph (a 230-fold increase compared to the middle of intermolt). From B stage to the beginning of D1, levels are very low but increase regularly and significantly. The amplitude and the temporal position of the peak are discussed in detail, in relation to the precision of the staging (17 different stages can be easily made in Orchestia) and to the cuticle cycle (the hormonal peak occurs ca. 10 hr before the beginning of cuticle synthesis at D2). Preliminary experiments, using monoclonal antibodies during the period of low ecdysteroid titers or high-performance liquid chromatography followed by polyclonal RIA during the peak period, suggest that the immunoreactive hormone in O. cavimana behaves like 20-hydroxyecdysone. However, other minor compounds have been detected (some unknown, others migrating like ecdysone and ponasterone A in HPLC).

Animals↗
PubMed1989

Hemolymph ecdysteroids and molt cycle in males and females of Siriella armata M-Edw. (Crustacea: Mysidacea): possible control by the MI-ME X-organ of the eyestalk.

Hemolymph ecdysteroids were quantified by radioimmunoassay (RIA) at successive stages of the molt cycle in the mysid Siriella armata. Profiles showed a single peak during premolt, at stage D1 for males, and D2 for reproducing females who displayed ecdysteroid levels 10 times higher than males. Titers were also measured for individuals which had been molt inhibited by early electrocauterization of the eyestalk MI-ME X-organ. In the case of total inhibition of molt preparation, the ecdysteroid peak was suppressed. It was displaced toward the end of the cycle when only ecdysis was inhibited. Ecdysone and 20-hydroxyecdysone were characterized in the hemolymph of both sexes using high-pressure liquid chromatography followed by RIA. High-polarity products, abundant in the female hemolymph, were resolved into 20-hydroxyecdysone and ecdysone by enzymatic hydrolysis and thin-layer chromatography. The quantitative and qualitative variations of ecdysteroid in the different situations (male or female, normal or inhibited cycles) are presented in relation to apolysis, epidermic activity, ecdysis, and secondary vitellogenesis in females, emphasizing the importance not only of ecdysteroids, but also of the MI-ME X-organ in monitoring molt and blood preparation in mysids.

Animals↗
PubMed1990

Purification and characterization of androgenic hormone from the terrestrial isopod Armadillidium vulgare Latr. (Crustacea, Oniscidea).

Androgenic hormone (AH) was purified from hypertrophied androgenic glands of intersexed Armadillidium vulgare (genetic males feminized by symbiotic endocellular bacteria). Two isohormones labeled AH1 and AH2 with similar molecular weights in the range 17,000-18,000 were isolated. Amino acid analysis showed the absence of cysteine in these two forms. A polyclonal antiserum was raised which recognized AH1 and AH2. The physiological significance of this polymorphism is still not known.

Amino Acids↗
PubMed1990

Vitellogenin synthesis in andrectomized males of the terrestrial isopod, Armadillidium vulgare (malacostracan Crustacea).

When adult females of Armadillidium vulgare were ovariectomized, the fat body continued to synthesize vitellogenin. On the other hand, females transplanted with androgenic glands decreased the synthetic activity for vitellogenin in their fat body. In order to elucidate effect of the androgenic hormone for vitellogenin synthesis, the occurrence of vitellogenin was studied with andrectomized males. Vitellogenin was estimated, using rocket immunoelectrophoresis. Vitellogenin synthesis in the fat body was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and fluorography. After andrectomy, males ceased elongation of the endopods (copulatory organs) and then vitellogenin was present in their hemolymph. Their vitellogenin titer continued to rise until it reached approximately three times higher than that of normal females. The accumulation level of vitellogenin was comparable with that of ovariectomized females. However, the activity of vitellogenin synthesis was at a low level in the fat body culture of andrectomized males, similar to ovariectomized females. These results indicate that andrectomized males are capable of vitellogenin synthesis, so one of the effects of the androgenic hormone is to inhibit vitellogenin synthesis. In A. vulgare, ovarian factors may not be involved in the induction of vitellogenin synthesis.

Animals↗
PubMed1991

Ovarian control of oostegite formation in the terrestrial isopod, Armadillidium vulgare (Malacostraca, Crustacea).

The correlation between oostegite formation and ovarian maturation was investigated in the isopod Armadillidium vulgare. Females whose ovaries had been removed and males whose androgenic glands had been removed were used in these experiments. Ovariectomy of puberal females did not stop oostegite formation. Whether oostegites develop in puberal females whose ovaries have been removed depends upon the degree of maturation of the ovaries at the time of removal. On the other hand, ovariectomized juvenile females and andrectomized juvenile males were unable to form oostegites when they attained puberty. An extract of vitellogenic ovaries induced oostegite formation in ovariectomized females and andrectomized males, but not in intact males. The ability of ovarian extracts to induce oostegite formation was dose-dependent. The nature of this ovarian factor that induces oostegite formation in A. vulgare remains to be elucidated.

Animals↗
PubMed1991

Sex-reversal of male Armadillidium vulgare (Isopoda, Malacostraca, Crustacea) following andrectomy and partial gonadectomy.

Evidence is presented for the first time for the complete sex-reversal of genetic males of the terrestrial isopod Armadillidium vulgare into functional females following partial gonadectomy. Fifth-instar males were used. The anterior half of their rudimentary reproductive organs along with the attached androgenic glands were removed. Six months later these animals formed oostegites and laid eggs, and when bred with normal males, produced only male offspring. These results show that in the absence of the androgenic gland, female sex characteristics differentiate and oogenesis occurs in genetic males.

Animals↗
PubMed1978

Modified pore canals in the cuticle of Gammarus (Crustacea : Amphipoda); a study by scanning and transmission electron microscopy.

A novel type of pore canal is described from the cuticle of three species of Gammarus. Each canal passes from the epidermis vertically through the endocuticle and exocuticle, and in the most distal layers of the latter is slightly expanded. Before entering the epicuticle the canal narrows, forming a neck the base of which is encircled by an electron-dense collar. Several tubular structures arise from the collar and pass distally into the reticular innermost regions of the epicuticle. Within the neck and just below its opening at the cuticle surface, a rod-like structure is inserted; this protrudes a short distance from the pore. Each pore canal is connected to many necks; the openings of the latter are aligned in rows over the surface, the openings and rows being about 0.15 and 1.0 micron apart, respectively. Changes in the pore and canal contents are visible and their significance is discussed.

Animals↗