F prostaglandins function as potent olfactory stimulants that comprise the postovulatory female sex pheromone in goldfish

This study establishes that ovulated female goldfish release F type prostaglandins (PGFs) to the water where they stimulate male spawning behavior and comprise the goldfish postovulatory pheromone. We first demonstrated that ovulated and prostaglandin-injected female goldfish release immunoreactive PGFs to the water. Next, using electro-olfactogram recording (EOG), we determined that waterborne prostaglandins function as potent olfactory stimulants for mature male goldfish. Prostaglandin F2 alpha (PGF2 alpha) and its metabolite 15-keto-prostaglandin F2 alpha (15K-PGF2 alpha) were the most potent prostaglandins; the former had a detection threshold of 10(-10) M and the latter a detection threshold of 10(-12) M. Studies of prostaglandin-injected fish indicated that PGF metabolites are an important component of the pheromone. Cross-adaptation experiments using the EOG demonstrated that goldfish have separate olfactory receptor sites for PGF2 alpha and 15K-PGF2 alpha that are independent from those that detect other olfactory stimulants. Finally, we established that male goldfish exposed to low concentrations of waterborne PGFs exhibit reproductive behaviors similar to those elicited by exposure to the odor of ovulated fish. Together with our recent discovery that a steroidal maturational hormone functions as a preovulatory "priming" pheromone for goldfish, these findings suggest that hormones and their metabolites may commonly serve as reproductive pheromones in fish.     

Identification and characterization of a suppressor T cell hybridoma specifically inducible by L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT)

In vitro activation of naive spleen cells from C57BL/10 mice with GAT and the monoclonal GAT-TsF1, 372B3.5, followed by fusion with BW5147 resulted in generation of a hybridoma that fails to produce GAT-TsF constitutively, but upon reexposure to GAT and 372B3.5 is induced to secrete GAT-TsF2. The induction is GAT specific and requires de novo RNA, protein synthesis, and DNA synthesis. Although both GAT and 372B3.5 are required for induction, they may be added sequentially, provided the GAT is added first. The GAT-TsF produced by the induced cell is antigen specific and composed of two polypeptide chains: one capable of binding antigen, the other bearing determinants encoded by the I-J region of the MHC. The utility of this inducible GAT-TsF2 cell line for molecular biology and other studies is discussed.     

Techniques for studying the execution of foreign queens by temporal subcastes in fire ants (Solenopsis invicta)

Using monogynous and polygynous colonies of the fire ant, Solenopsis invicta Buren, we developed methodology to determine which behavioural subcaste of workers was responsible for executing unfamiliar queens that were introduced to them. Separation of subcastes and introduction of queens to each of these separately was partly effective, but more accurate results were obtained by removing workers that were in the act of executing queens, marking them individually, and returning them to the colony. Their subsequent behaviour was then recorded to determine whether they behaved like nurses, reserves, or foragers. The results showed that foragers are dominant in execution behaviour and that all morphological subcastes (minors, medias, and majors) are involved. This methodology may be applied to other social insect species.

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Résumé A l'aide de colonies monogynes de S. invicta Buren, nous avons testé la sensibilité de deux méthodes: Premièrement, nous avons isolé les trois sous-castes temporelles des ouvrières (nurses, réserves et fourrageuses) auxquelles nous avons introduit des reines étrangères. Nous avons trouvé que les fourrageuses étaient le groupe le plus agressif, exécutant un pourcentage élevé des reines qui leur étaient présentées. Le degré de physogastrie de la reine étrangère, sa colonie d'origine et la présence de couvain n'avaient pas d'effet visible sur sa destinée. La sensibilité de cette méthode était limitée par la difficulté d'une séparation complète des souscastes temporelles.Deuxièmement, nous avons capturé des ouvrières exécutant activement des reines étrangères, après marquage nous les avons remises dans leur colonie pour observations ultérieures. Nous avons remarqué que leur localisation dans le nid et leur comportement correspondaient aux séquences trouvées pour les fourrageuses bien plus qu'à celles des ouvrières réserves ou nurses. Cette méthode est plus sensible. Des mesures de la largeur de la capsule céphalique de ces ouvrières ont montré qu'aucune des sous-caste morphologiques (mineurs, moyennes et majeurs) étaient dominantes dans le comportement d'exécution. Nos résultats indiquent que la sensibilité des ouvrières à certaines phéromones de la reine et odeur de la colonie augmente avec leur âge.

     

Cell-mediated immune responses to Chlamydia trachomatis in mothers and infants

Cell-mediated immunity to Chlamydia trachomatis was studied in pregnant women with chlamydial infection of the cervix, in infants born vaginally to these women, and in infants presenting with chlamydial conjunctivitis. Uninfected pregnant women and their infants were studied as controls. McCoy cell cultures were used to isolate C. trachomatis from clinical specimens. Cell-mediated immunity was measured by lymphocyte proliferative responses in vitro to stimulation by chlamydial antigens. Chlamydial IgG antibody in serum specimens was detected by a microenzyme-linked immunosorbent assay technique. The mean lymphocyte proliferative responses to chlamydial antigens were greater in infected women than in uninfected women both during pregnancy and in the postpartum period. Lymphocyte responsiveness in infected pregnant women, however, was less than in postpartum women. Despite failure to detect chlamydial infection in exposed infants, lymphocyte proliferative responses were greater in umbilical cord blood and later in peripheral blood samples from neonates born to infected mothers than in infants born to uninfected mothers. These responses were also greater in infants with chlamydial conjunctivitis than in infants of uninfected mothers. These data suggest that cellular immune responses to chlamydial antigens are increased in infected mothers and infants and that infants may acquire chlamydial cell-mediated immunity transplacentally.     

1α,25-dihydroxyvitamin D3 rapidly alters phospholipid metabolism in the nuclea envelope of osteoblasts

1α,25-Dihydroxyvitamin D₃ (1α, 25-(OH)₂D₃) has been shown to increase cytosolic calcium and inositol trophosphate levels in rat osteosarcoma cells (ROS 17/2.8) and to increase nuclear calcium in these cells. To determine the mechanism(s) of 1α, (OH)₂D₃-induced changes in the calcium, the effect of the hormone on phospholipid metabolism in isolated osteoblast nuclei wa assessed. 1α,25 (OH)₂D₃, 20 nM, increased inositol triphosphate levels in the nuclei after 5 min of treatment. The biologically inactive epimer, 1β,25-(OH)₂D₃, had no significant effect on inositol triphosphate levels. ATP, 1 mM, also increased inositol triphosphate levels in the isolated nuclei after 5 min. 1α,25-(OH)₂D₃, 20 nM, increased calcium in the isolated nuclei in the presence but not in the absence of extranuclear calcium with 5 min. Nuclear calcium was also increased within 5 min by ATP, 1 mM, and inositol triphosphate, 1 mM. The effects of ATP on nuclear calcium was not additive with 1α, 25-(OH)₂D₃, suggesting that these two agents increase nuclear calcium in these osteoblast-like cells by similar mechanisms. In summary, 1α,25-(OH)₂D₃ amd ATP rapidly increase inositol triphosphate levels in isolated from ROS 17/2.8 cells. The hormone, the nucleotide, and the inositol phospholipid nuclear calcium. Thus, the 1α,25-(OH)₂D₃ and ATP effects of nuclear calcium may be mediated by changes in phospholipid metabolism in the nuclei of these osteoblastlike cells. © Wiley-Liss, Inc.     

Biophysical studies of infectious pancreatic necrosis virus.

The molecular weight of infectious pancreatic necrosis virus (IPNV) has been determined by analytical ultracentrifugation and dynamic light scattering. The sedimentation coefficient of the virus was found to be 435S. The average value for molecular weight is (55 +/- 7) x 106. The virus genome consists of two segments of double-stranded RNA (molecular weights, 2.5 x 106 and 2.3 x 106), which represents 8.7% of the virion mass. The capsid protein moiety of IPNV consists of four species of polypeptides, as determined by polyacrylamide gel electrophoresis. The number of molecules of each polypeptide in the virion has been determined. There are 22 molecules of the internal polypeptide alpha (molecular weight, 90,000), 544 molecules of the outer capsid polypeptide beta (molecular weight, 57,000), and 550 and 122 molecules, respectively, of the internal polypeptides gamma1 (molecular weight, 29,000) and gamma2 (molecular weight, 27,000). IPNV top component contains only the beta polypeptide species, and its molecular weight is estimated to be 31 x 106. The hydrodynamic diameter and electron microscopic diameter (calculated by catalase crystal-calibrated electron microscopy) of IPNV was compared with those of reovirus and encephalomyocarditis virus. Due to the swelling of the outer capsid, reovirus particles were found to be much larger when hydrated (96-nm diameter) than when dehydrated (76-nm diameter), having a large water content content and low average density. In contrast, IPNV particles are more rigid, having nearly the same average diameter under hydrous (64 nm) as under anhydrous conditions (59.3 nm). Encephalomyocarditis virus has a very low water content and does not shrink at all when prepared for electron microscopy.     

The biological half life and distribution of 125Iodide and radioiodinated protein in the imported fire ant, Solenopsis invicta

The radioisotope ¹²⁵Iodide, a gamma emittor, was used in two different forms, as ¹²⁵I mixed with egg yolk and as ¹²⁵I covalently attached to egg albumin and mixed with egg yolk, to study food flow in the imported fire ant, Solenopsis invicta Buren. The biological half life of ¹²⁵I-albumin in egg yolk powder was determined to be 96 hr in isolated workers, 108 hr in individuals held with small groups of unlabelled workers, and 1,008 hr in workers held in colonies exposed to labelled food for 48 hr. In contrast, the biological half life of free ¹²⁵I mixed with egg yolk powder was 22 hr, 20 hr, and 40 hr, respectively.The internal distribution of radioactivity was checked after 24,48, and 380 hr. There was a significant difference in distribution of ¹²⁵I in ants fed either free ¹²⁵I or ¹²⁵I-albumin. Most of the free ¹²⁵I was rapidly excreted. A high percentage of ¹²⁵I-albumin was assimilated, apparently through protein digestion pathways with eventual storage in or below the cuticle. There was no evidence of gland involvement in food flow to either larvae or queens with the radio-iodinated protein.

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Résumé L'utilisation de l'iode radio-actif (¹²⁵I) a permis d'étudier le cheminement de la nourriture chez Solenopsis invicta Buren (Myrmicinée). Deux formes différentes de l'isotope ont été étudiées. L'iode 125 a été fixé d'une manière covalente à la tyrosine dans l'albumine des oeufs en utilisant la méthode chloramine T pour ioder les protéines. L'albumine marquée a été mangée ensuite à du jaune d'oeuf en poudre.La seconde forme contenait de l'iode 125 mélangé au jaune d'oeuf en poudre en absence de tout catalyseur, ce qui empêche la fixation chimique. La demi-vie biologique (T_biol) des deux formes a été déterminée chez des ouvrières isolées, chez des individus gardés avec de petits groupes d'ouvrières non-marquées, et chez des ouvrières gardées dans des colonies exposées à la nourriture radio-active pendant 48 h. La demi-vie biologique de l'albumine marquée était de 96 h, 108 h, et 1.008 h. En contraste, la demi-vie de l'iode 125 était de 22 h, 20 h, et 40 h. L'effet de groupe créé par des échanges répétés de nourriture entre les individus était négligeable avec la nourriture protéique. L'échange répété de nourriture entre les larves et les ouvrières a beaucoup augmenté la demi-vie de l'albumine marquée à I 125. Cet effet n'était pas aussi clair avec l'iode 125 par suite de son élimination rapide.La distribution de la radio-activité a été examinée chez des ouvrières au bout de 24, 48 et 380 h après les avoir nourries avec de l'albumine marquée à I 125 et de l'iode 125. Il y avait une différence considérable de distribution, avec un haut pourcentage d'albumine assimilé, sans doute par les voies de digestion de protéines. Le radio-isotope a été ensuite conservé sous forme d'iode 125 ou d'iodotyrosine, dans (ou sous) la cuticule de l'ensemble du corps. Les fourmis ont rapidement excrété l'iode 125 libre avec 5% de la radioactivité résiduelle après 380 h, peut-être fixée aux protéines cellulaires, et ensuite transportée vers la cuticule. Les différences considérables entre les demi-vies biologiques et la distribution interne de la radioactivité chez les fourmis nourries avec de l'iode 125 ou à l'albumine marquée à I 125, soulignent le danger de croire que le cheminement de la nourriture peut être définitivement étudié en utilisant des radio-isotopes qui ne sont pas fixés chimiquement à la substance étudiée.

     

Isolation of an aggregation inhibitory factor from non-adhesive mouse teratoma cells

An aggregation inhibitory factor (AIF) has been extracted from mouse ascites teratoma cells (that do not aggregate in culture) that retards adhesion of cultured teratoma cells of the same cell line (that do aggregate). Preliminary characterization of AIF on polyacrylamide gels suggests that AIF is a protein composed of four subunits. Extraction of AIF from ascites teratoma cells was accomplished without significant loss of viability by a technique involving the application of an electric field to large numbers of whole cells suspended in a hypertonic electrode buffer. In tests of adhesion, AIF consistently and immediately inhibited aggregation of cultured teratoma cells after 5, 10, 15, and 30 min of incubation. Furthermore, a reduced concentration of AIF resulted in a corresponding decrease in inhibition, suggesting a concentration-dependent action. AIF may help explain how cultured teratoma cells adhere, whereas ascites teratoma cells of the same subline do not adhere.