Gilbert Martin

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.

The hyperglycemic neuropeptide of the terrestrial isopod, Porcellio dilatatus. I. Isolation and characterization

From isolated sinus glands of Porcellio dilatatus, a hyperglycemic neuropeptide (CHH) was purified by means of a single, two-step purification procedure which consisted of gel chromatography on Sephadex G-50, followed by high-performance liquid chromatography. The 5800- to 6100-Da peptide contains 50-52 amino acids residues. The amino acid composition is (Pro, Ile)1; His1-2; (Thr, Ser, Gly, Met, Tyr)2; (Val, Phe, Lys)3; (Ala, 1/2Cys, Leu, Arg)4; Glx5; Asx7; Trp, n.d. The amino acid composition differs from that of two decapod CHHs analyzed thus far. The N-terminus is blocked. The neuropeptide exhibits little or no interspecific hyperglycemic effect in the brachyuran, Uca pugilator, and its cross-reactivity and potency in the RIA for Carcinus-CHH is very low.

Immunochemical and immunocytochemical studies of the crustacean vitellogenesis-inhibiting hormone (VIH).

Immunochemical investigations, using dot immunobinding assay (DIA) and enzyme-linked immunosorbent assay (ELISA), and immunocytochemical studies reveal the following new information about crustacean vitellogenesis-inhibiting hormone (VIH): (1) The structure of VIH is sufficiently different from that of the other sinus gland neuropeptides to allow a selective recognition of VIH by polyclonal antibodies. (2) From immunochemical criteria, VIH does not seem strictly species specific. The antisera raised against VIH of Homarus americanus cross-react with sinus gland extracts of Palaemonetes varians, Palaemon serratus, Macrobrachium rosenbergii, Carcinus maenas, and Porcellio dilatatus. (3) In the sinus gland of H. americanus, VIH immunoreactivity is localized mainly in electron-dense granules of medium size (110-185 nm in diameter) while, in P. dilatatus, the labeling is mostly on the largest granules (200-270 nm in diameter).

Characterization and transcriptional analysis of two gene clusters for type IV secretion machinery in Wolbachia of Armadillidium vulgare

Wolbachia are maternally inherited alpha-proteobacteria that induce feminization of genetic males in most terrestrial crustacean isopods. Two clusters of vir genes for a type IV secretion machinery have been identified at two separate loci and characterized for the first time in a feminizing Wolbachia. Furthermore, we demonstrated that these operons are transcriptionally active in ovaries and in all other tissues tested, suggesting that T4SS has a significant role in Wolbachia biology. These observations and the identification of homologous vir genes in Wolbachia strains infecting insects or nematodes show that vir genes are conserved among Wolbachia strains whatever the phenotype induced by the bacteria.

Localization of crustacean hyperglycemic and vitellogenesis-inhibiting hormones in separate cell types in the protocerebrum of the woodlouse Armadillidium vulgare (Crustacea, Isopoda).

We gave an accurate immunolocalization of CHH (crustacean hyperglycemic hormone) and VIH (vitellogenesis-inhibiting hormone) in the brain and the sinus gland of the woodlouse Armadillidium vulgare. The two immune sera have been respectively raised against HPLC-purified CHH and against a small peptide derived from the N-terminus of VIH. By immunocytochemistry, we showed that CHH and VIH were synthesized in different perikarya and stored in different axon endings of the sinus gland. As in other crustacean species studied to date, CHH was located in the axon endings filled with the biggest granules. Immunoblotting confirmed that VIH was stored in the sinus glands of both the female and the male. These clear localizations of CHH- and VIH-antigens do not preclude that only one peptide is released from a given type of SG endings and do not rule out that each peptide can be involved in the control of different physiological processes.

A somatostatin-like antigen in the nervous system of an isopod Porcellio dilatatus brandt

Abstract Immunohistological investigations were performed with an antiserum to protein-linked somatostatin (SRIF) in the CNS of a crustacean Porcellio dilatatus . Discretely located perikarya and fibers containing a SRIF-like substance are completely negative with usual staining. The functional role of this SRIF-like substance is still unknown.

Protein profiling of hemocytes from the terrestrial crustacean Armadillidium vulgare

To establish and maintain a successful infection, microbial pathogens have evolved various strategies to infect the host in the face of a functional immune system. In this context, the alpha-proteobacteria Wolbachia capacities to infect new host species have been greatly evidenced. Indeed, in terrestrial isopods, experimentally transferred Wolbachia invade all host tissues, including immune cells such as hemocytes. To investigate mechanisms that have to be avoided by bacteria to maintain themselves in hemocytes, we characterized the hemocyte proteome of Armadillidium vulgare by a 2D gel electrophoresis approach. Fifty-six proteins were identified and classified into functional groups (stress and immunity, glucose metabolisms, cytoskeleton, others). We focused on immune response and cytoskeleton proteins often exploited by bacteria to invade their host. From the microsequences obtained by mass spectrometry, PCR primers were designed to amplify seven partial cDNAs encoding masquerade, alpha2-macroglobulin, transglutaminase, MnSOD, calreticulin, cyclophilin, and vinculin, confirming their expression in hemocytes.

La reproduction saisonniére chez les isopodes terrestres: Contrôle photopériodique et neurohumoral

Summary Seasonal reproduction in terrestrial Isopods is regulated by a neurohormone (VIH) synthesized in neurosecretory cells located in the protocerebrum median part. VIH restrains vitellogenin synthesis by the fat body. This inhibitory system is driven by the photoperiodic variations. Long days introduce a decrease in synthesis and—or—VIH release, allowing the oocytes to carry out the last vitellogenic phase. Other signals (mating, eggs in brood-pouch) tune the activity of the inhibitory system. Various aspects of photoperiodic and neurohormonal controls of reproduction are discussed: geographical variability and genetic determinism of the photoperiodic response; chemical nature, specificity and VIH mode of action; male physiology and VE synthesis, modalities of VIH synthesis and release.

INTRACEREBRAL OCELLI IN THE GIANT ANTARCTIC SLATER GLYPTONOTUS ANTARCTICUS(ISOPODA: VALVIFERA)

ABSTRACT Details on the location and ultrastructural organization of 2 intracerebral ocellar regions in the giant Antarctic slater Glyptonotus antarcticus are given. Each ocellar region measures approximately 120 x 45 μm and consists of 2 overlapping ocellar subunits inserted under the neurilemma in the median part of the protocerebrum. One subunit comprises 2 retinula cells; the second 3. Small rhabdoms, made up of typical microvilli, are formed by both subunits. Lipid droplets, but no screening pigment granules, were present in all 5 retinula cells together with a host of intracellular organelles characteristic of membrane-turnover processes. It is concluded that direct photostimulation of the intracerebral ocelli is likely and that functionally they could be analogous to the pineal organ of lower vertebrates. Evidence is presented that, at least anatomically, the intracerebral ocelli are independent from other sensory complexes in the head of G. antarcticus, such as the compound eyes, the organ of Bellonci, and the sensory pores.

Note On Some Anatomical Features (Neurosecretory Organs and Median Ocelli) of Paramphisopus Palustris (Glauert, 1924) (Isopoda, Phreatoicidae)

Previous studies of the endocrine organs and frontomedial ocelli of the Isopoda revealed that structural differences exist in the hitherto observed suborders. The Phreatoicidea, the oldest known suborder, are studied for the first time. A Bellonci organ was not discovered. The sinus gland has a globular form, it seems to be linked with the lateral cephalic nerve plexus. Similar sinus glands are known from the Oniscidea. The median ocelli are reduced to the number of 3, while other Isopoda may have 2 to maximally 5 ocelli.