Adrien Girardie

Identification of an arginine vasopressin-like diuretic hormone from Locustamigratoria

We have identified two neuropeptides (F1 and F2) from suboesophageal and thoracic ganglia of Locusta migratoria, which we isolated earlier based on their immunological similarity to arginine vasopressin. The more abundant and hydrophilic factor, F1, has sequence Cys-Leu-Ile-Thr-Asn-Cys-Pro-Arg-Gly-NH2, but its biological role is unknown. The less abundant factor, F2, is an antiparallel dimer of F1, and functions as a diuretic hormone of this species. It appears to act through the intermediacy of cyclic AMP. The properties of the native neuropeptides were identical with those of samples synthesized from appropriately protected L-amino acids.

Anti-juvenile effect of neuroparsin A, a neuroprotein isolated from locust corpora cardiaca

Abstract Neuroparsin A, a sulfur-containing protein synthesized by the medial part of the brain of Locusta and transported to the corpora cardiaca (CC) via the nervi corporis cardiaci I (Girardie et al. , 1987), was satisfactorily isolated using electro-elution. A specific immune serum against electro-eluted neuroparsin A was generated. On serial histological sections of the brain treated with the immune serum, only the median neurosecretory cells [stained in blue following the double staining Victoria blue-paraldehyde fuchsin (Al type)] were revealed using peroxidase-antiperoxidase technique. Inactivation of neuroparsin A by antigen-antibody complex formation following injections of immune serum induced green pigmentation, intermediary forms and precocious sexual maturation. These symptoms also follow juvenile hormone (JH) injections. Injections of immune serum antineuroparsin A or the electro-eluted neuroparsin A produced opposite effects on oocyte growth but had no effect on the rate of JH biosynthesis evaluated by radiochemical assay. The neurohormone neuroparsin A could be the median humoral inhibiting factor of the JH system which was previously demonstrated (Girardie, 1966, 1967) in the central area of the pars intercerebralis.

Amino acid sequence of locust neuroparsins

Neuroparsins A and B were isolated from the nervous part of the corpus cardiaca of Locusta migratoria via a two‐step purification procedure. Both consist of two polypeptide chains linked by disulfide bridges. The N‐terminal sequence of both native neuroparsins was determined: the N‐terminal end of neuroparsin B was unique while that of neuroparsin A showed three different sequences. These sequences were that of neuroparsin B and two others having five and two extra N‐terminal residues. Neuroparsin B was found as a homodimer and the complete sequence of the monomer, determined from peptide fragments generated by treatment with cyanogen bromide and endoprotease Glu‐C, comprises 78 residues.

Lom OMP, a putative ecdysiotropic factor for the ovary in Locusta migratoria

The primary target of the gonadotropic neurohormone of Locusta migratoria (Lom OMP) was investigated in locust fifth instar larvae (last larval instar) and adult females by analysing the effect of Lom OMP and 20-hydroxyecdysone (20-HE) on the appearance of vitellogenin (Vg) in the haemolymph and on ovarian growth. Detection of Vg was carried out using 7.5% polyacrylamide gel electrophoresis of haemolymph while ovarian growth was estimated by measuring the mean length of basal oocytes. Injections of 20-HE had no effect in larvae but induced, in adults, a precocious occurrence of Vg and precocious ovarian maturation similar to injections of Lom OMP. Moreover, injections of 20-HE counterbalanced the endogenous Lom OMP inactivated by its immune serum. Finally, Lom OMP did not induce the appearance of Vg when it was injected in ovariectomized fifth instar larvae. These results demonstrate, in contrast to the prevailing concept, that ecdysone is a gonadotropic hormone in Locusta and strongly suggest that Lom OMP induces ovarian ecdysone production. The possibility that not only the ovary but also the fat body could be a target organ of Lom OMP is discussed.

Isolation, sequence determination, physical and physiological characterization of the neuroparsins and ovary maturing parsins of Schistocerca gregaria

Neurosecretory products immunologically related to either neuroparsin (NP) or ovary maturing parsin (OMP) of Locusta migratoria (Lom) were purified from the nervous corpora cardiaca of Schistocerca gregaria (Scg). The determination of both their molecular masses by mass spectrometry and their sequences by automated Edman degradation established that they are members of the NP and OMP families respectively. NP molecules of Schistocerca (Scg NPs) consisted of two major forms having about the same molecular masses as NPA and NPB of Locusta and 88% primary structure similarity. They had also the same antidiuretic activity. OMP molecules of Schistocerca (Scg OMPs) were composed in young adults of four isoforms: two long isoforms corresponding to Lom OMP, and differing by a tripeptide insertion (Pro-Ala-Ala) at position 21 and two short isoforms deprived of the 13-residue N-terminal peptide of Lom OMP and differing by the same tripeptide insertion. The PAA isoforms were observed in low amounts as compared to the other isoforms. In mature adults, only the two short isoforms were present. The complete sequence of PAA Scg OMP presents a large degree of sequence homology with Lom OMP (83%). The mixed Scg OMPs had the same biological effects as Lom OMPs. They induced precocious occurrence of both ecdysteroids and vitellogenin in the haemolymph and stimulated oöcyte growth.

Controle humoral de l'equilibre hydrique chez Locusta migratoria migratorioides

Abstract The electrocoagulation of the median neurosecretory cells of the pars intercerebralis in Locusta migratoria migratorioides induces the swelling of the abdomen which is due to the increase of the total water content (increase of haemolymph volume). In vitro experiments have been done to investigate the influence of aqueous extracts of pars intercerebralis, of corpora cardiaca, of suboesophageal ganglions, and of abdominal nervous chains on the Malpighian tubules and the rectum. The extracts of the pars intercerebralis favour both the excretion by the Malpighian tubules and the reabsorption by the rectum; this proves that the pars intercerebralis produces a diuretic hormone acting on the Malpighian tubules and an antidiuretic hormone acting on the rectum. The Malpighian tubules in the presence of extracts of pars intercerebralis obtained from hydrated animals excrete more than extracts from dehydrated animals. Rectal reabsorption is higher with extracts from dehydrated animals than with extracts from normal or hydrated animals. The extracts of corpora cardiaca show a strong antidiuretic action on the Malpighian tubules and on the rectum. This action is strongest with extracts from hydrated animals. The antidiuretic effect of the corpora cardiaca on the Malpighian tubules might be due to a specific factor of these glands. Extracts of the suboesophageal ganglions and the abdominal nervous chains have a weak antidiuretic effect on the Malpighian tubules and on the rectum. Extracts of muscles modify neither the speed of excretion of the Malpighian tubules nor the rate of rectal reabsorption.

Activity of disconnected corpora allata in Locusta migratoria: Juvenile hormone biosynthesis in vitro and physiological effects in vivo

Abstract Severance of nervi corporis allati I (NCA I) in day-1 adult female Locusta migratoria resulted in a significant decrease and a loss of the characteristic pattern of juvenile hormone biosynthesis by the corpora allata as determined by radiochemical assay. This decrease in the rate of juvenile hormone biosynthesis was not reflected in basal oocyte growth. The lengths of the oocytes were the same in NCA-transectioned and in the sham-operated females. The effect of severance of both NCA I and NCA II on juvenile hormone biosynthesis and ovarian maturation was similar to the effect of NCA I severance only. Rate of juvenile hormone biosynthesis by corpora allata of fourth-instar larvae exhibited a maximum of activity in the middle of the stadium. The severance of NCA I early in the stadium resulted in a very low rate of juvenile hormone biosynthesis and a disappearance of this peak. In NCA I-transectioned larvae, the duration of the stadium was significantly increased although larvae moulted into normal fifth instar.

Enhancement of juvenile hormone biosynthesis in locusts following electrostimulation of cerebral neurosecretory cells

Abstract Electrostimulation of the medial neurosecretory cells of day-1 adult female Locusta migratoria resulted in a significant enhancement of juvenile hormone biosynthesis by the corpora allata within 2–3 days of the operation, as determined by a radiochemical assay for juvenile hormone biosynthesis. This elevation in the rate of juvenile hormone biosynthesis was also reflected in basal oocyte length, with the oocytes of stimulated animals significantly larger than the sham-operated animals. Radio-frequency cautery of the cerebral axonal tracts of the medial neurosecretory cells prevented this enhancement in juvenile hormone biosynthesis and in basal oocyte growth in both stimulated and sham-operated animals. Stimulation of the lateral neurosecretory cells resulted in a slight elevation in rates of juvenile hormone biosynthesis 2 days after the operation. However, after cautery of the medial cell tracts, a significant elevation in juvenile hormone biosynthesis was observed 1 and 2 days after stimulation. Basal oocyte length in stimulated animals differed significantly from sham-operated animals only on day 6. Cautery of the medial cell tracts again attenuated oocyte growth. Our results suggest that the medial neurosecretory cells are the source of an allatotropin that can be released by electrostimulation. This substance appears to operate directly on the corpus allatum, causing a change in the juvenile hormone biosynthetic machinery.

Production sites of the three neurosecretory proteins characterized in the corpora cardiaca of the migratory locust

The sites of production of three cysteine and/or cystine-rich neurosecretory proteins (a monomer, a dimer and a trimer) partially characterized by us previously (Girardie et al., 1985) were determined by slab gel autoradiography using both intact locusts and locusts in which the corpora cardiaca (CC) were disconnected from the brain before injection of [35S]cysteine. The dimer is synthesized by the glandular cells of the CC and we propose the name cardiacin for this protein. The trimer is synthesized by the protocerebral median neurosecretory cells (A1 and/or A2 types) and we propose the name neuroparsin A for this molecule. The monomer, which appears only in nervous CC results from a transformation of neuroparsin A and we thus propose the name neuroparsin B. The mechanism of this transformation, which also occurs in vitro with the isolated oligomer is, as yet, unknown but neuroparsin B could be a releasable form of neuroparsin A.

Action de la pars intercerebralis sur le developpement de Locusta migratoria L.

Abstract The destruction of the pars intercerebralis in the last two larval stages (IV and V) of the gregarious phase of Locusta migratoria by X-rays or cauterization alters the normal development of this insect. Moulting is stopped or delayed as after the removal of the ventral glands. Animals which moult have their metamorphosis, pigmentation, and development of the oocytes similar to animals which have been implanted with active corpora allata: the fifth moult results in metathetelic animals, or imperfect adults, or normal adults, and most animals are green. The other animals remain dark or become pale. The destruction of the pars intercerebralis can also completely prevent the growth of the terminal oocytes in the ovaries. The operated locusts contain in the sixth stage extremely large volumes of blood which greatly distend the abdomen. From all this it can be concluded that the pars intercerebralis in Locusta migratoria exerts control over the activity of the ventral glands and the corpora allata. The pars intercerebralis without the intermediacy of the corpora allata acts also on the chromatic adaptation, on oocyte development, and on metabolism.