Ammonia attracts the haematophagous bug Triatoma infestans : behavioural and neurophysiological data on nymphs

1) Nymphs of the haematophagous bug Triatoma infestans (Heteroptera: Reduviidae) are attracted to volatiles from their own faeces on a servosphere. 2) Biological substrates attractive to triatomines release NH₃: wetted triatomine faecal papers release NH₃ at 256 ppb NH₃ from a 60-g source and stale rabbit urine at 394 ppb from 200 ml. Ammonia released from aqueous NH₃ also attracts bugs at doses of 3 ppb and 17 ppb on the servosphere. 3) Bugs typically show negative anemotaxis in a stimulus-free air-stream on the servosphere. At onset of stimulation with ammonia from either biological substrates or aqueous NH₃ the bugs stop, move their antennae, turn and walk upwind, i.e. odour-mediated anemotaxis. 4) At lower NH₃ doses a latency in attraction is recorded, but this latency disappears when the relative humidity of the stimulus delivery air-stream is dropped from 90 to 35%. 5) Electrophysiological recordings from single olfactory sensilla on antennae of Triatoma nymphs reveal two different types of NH₃-excited receptors, both within grooved-peg sensilla. The responses of one of these receptor cells to NH₃ has been studied in detail and shows that the action potential discharge rate is dose-dependent over the range 2–200 ppb. 6) The amplitudes of electroantennograms recorded from Triatoma nymphs to NH₃ are dose dependent over the range 5–550 ppb. Accepted: 16 January 1997     

A Bcl-2-related gene is activated in avian cells transformed by the Rous sarcoma virus.

The oncoprotein p60v-src encoded by the Rous sarcoma virus (RSV) genome is the prototype of non-receptor tyrosine kinases. More than 50 targets of p60v-src have been described to date. However, the precise mechanisms of RSV transformation remain to be elucidated. Here, we present the study of a new v-src-activated gene, NR-13, which encodes a protein identified as a new member of the Bcl-2 family. This protein is localized in the membrane with a pattern already observed with Bcl-2. In quail embryos, this gene is mainly expressed in neural and muscular tissues. Its expression is dramatically down-regulated after embryonic day 7 (E7) in the optic tectum. To evaluate a possible role for NR-13 in the control of apoptotic processes in this particular brain area, in situ hybridization and DNA ladder fractionation studies were performed to correlate NR-13 expression with typical situations of apoptosis during brain development. Our results support the idea that RSV could activate anti-apoptotic functions of the host cell resulting in an increase of their lifespan, which could be particularly relevant to tumour formation.     

Effect of naloxone and beta-casomorphin on the hypothalamic-pituitary-luteinizing hormone axis in vitro.

The effect of naloxone and beta-casomorphin on luteinizing hormone (LH) release from pituitary cell aggregates, obtained by three-dimensional culture, with or without mediobasal hypothalamic fragments was studied in vitro. Short-term naloxone perifusion at a concentration of 10(-5)M did not modify either basal or LHRH-stimulated LH release from the pituitary cell aggregates. In contrast, a 12-min naloxone perifusion at the same concentration caused an increase in LH release in the mediobasal hypothalamic-pituitary cell aggregate axis. This increase was rapid (12-16 min after time pulse), marked [up to 10 times (p less than 0.004) the initial base line], short (return to the base line secretion 32-40 min after the beginning of the time pulse) and dose-dependent, with a rise greater than 1000% at a concentration of 10(-4) (p less than 0.006). The same effect was observed when a second pulse was applied 48 min after the first one. LH release induced by naloxone was antagonized 56 +/- 2% (p less than 0.03) by beta-casomorphin (an exogenous opiate) at a concentration of 10(-5) M. beta-casomorphin alone did not modify LH basal secretion, but inhibited 25.1 +/- 2.4% (p less than 0.008) LH release enhanced by LHRH. These results indicate that naloxone, an opiate antagonist, markedly increases LH release via a mu-type opioid receptor mechanism at the hypothalamic level only, during short-term exposure.     

Les prélèvements testiculaires dans les azoospermies sécrétoires: le point de vue du Biologiste de la Reproduction sur la lecture du prélèvement

The prognosis of severe male sterility (nonobstructive azoospermia) has considerably improved over recent years with the introduction of ICSI. The human reproduction biologist actively collaborates with the surgeon in the search for and extraction of sperm from testicular tissue (TESE). The presence of the biologist during surgery is mandatory to guide exploration and to avoid an excessive number of biopsies. Sperm extraction is performed in the laboratory by mechanical extraction with fine forceps. Enzymatic extraction with collagenase IV can be used in cases of nonobstructive azoospermia to optimize tissue dispersion and to improve retrieval of mature cells. The use of only one fraction (50%) of Pure Sperm (JC Diffusion, Lyon France) limits the loss of spermatozoa. to optimize the results in cases of akinesia, it may be useful to induce sperm motility by pentoxifylline or perform in vitro culture for three days. Sperm cryopreservation is compulsory in the case of nonobstructive azoospermia. This allows programming of TESE for a different time from that of ICSI. All results obtained with cryopreserved testicular sperm, in recent years, are encouraging. It is also recommended to freeze several small fractions of sperm in order to limit the number of surgical procedures on the testicle. This article presents the results of our experience in 36 cases of nonobstructive azoospermia. Extraction was negative in 13 cases (36%), similar to the rate reported in the literature.     

Premiere decouverte en Europe Sud-occidentale de Praeovibos priscus (Mammalia,Artiodactyla, Ovibovinae) dans le gisement pleistocene moyen ante-risseien de la Caune de l'Arago (Tautavel,Pyrenees-Orientales,France)

Teeth, cranial and postcranial skeletton of Praeovibos were sampled from the sediments of the Caune de l'AragoCave. This material is enough to recognize the anatomical relationships between Praeovibos and Ovibos. Praeovibos is discovered for the first time in France and in South Western Europe also. The problem of the correlation of the whole European Middle Pleistocene is approached from a different point of view.