Effect of somatostatin on beta-endorphin release in rat experimental chronic inflammation.

The aim of the present study was to investigate the effect of somatostatin administration in arthritic rats. Inflammation was induced by daily interplantar injection of 100 microl of Freund's complete adjuvant into the left hind paw of the rat. Arthritis developed 20 days following the first injection and was stable in the inoculate paw. Arthritic rats were treated interplantarly with somatostatin (5 or 10 microg) or with indomethacin (100 microg) daily for 14 days. Inflammatory response was studied at 12 h, 7 and 14 days following drug administration. The effect of somatostatin was determined by local (into popliteal lymph nodes) and systemic production of beta-endorphin. Our results showed that somatostatin treatment significantly increased beta-endorphin levels in the blood and lymphocytes from popliteal lymph nodes. Greater efficiency was seen when 5 microg instead of 10 microg of somatostatin was used. A significant decrease of absolute leukocytosis was observed at the 14th day following somatostatin administration. Moreover, a significant reduction of plasmatic beta-globulins at 12 h and the 7th day and of plasmatic alpha2-globulins at the 14th day was observed after the beginning of somatostatin treatment.     

Recherches sur l'hérédité de la dilution et du blanchiment du pelage dans le genre cavia

Sans résuméTravail exécuté grâce à une subvention de la DonationGeorges etAntoine Claraz, instituta et curataJohannis Schinz professoris auspiciis Série zoologie n^o 66     

Comparison of the Vertical Distribution of Nematodes from Two Contrasting Abyssal Sites in the Northeast Atlantic Subject to Different Seasonal Inputs of Phytodetritus

The vertical distribution of nematodes in the sediments of three cores from the phytodetritus-influenced Porcupine Abyssal Plain station is compared with three cores from the Madeira Abyssal Plain station in the DEEPSEAS programme. Nematode vertical distributions are compared with sediment organic chemistry data sampled at the same time from the same sites. The results support the two hypotheses erected by Thiel (1983) that the penetration of meiofauna into deep-sea sediments might be correlated with the input of organic matter and that a greater biological activity of larger organisms would increase the penetration of nematodes into the sediment through increase downward transport of food material.     

Ultrastructure and Comparative Morphology of Mouth-part Sensilla in Ground Beetle Larvae (Insecta, Coleoptera, Carabidae)

Labial and maxillary palps in 22 species of ground beetle larvae revealed the presence of four different types of sensilla: sensilla digitiformia, sensilla campaniformia, sensilla basiconica and sensilla chaetica. Using transmission electron microscopy techniques, the role of most of them was defined: sensilla campaniformia and sensilla chaetica are mechanoreceptors; while sensilla basiconica are chemoreceptors. Sensilla digitiformia can be both mechanoreceptors and chemoreceptors, though hygroreception may also be postulated on the basis of their abundance on the mouthparts of some hygrophilous species that depend on damp or wet patchy biotopes/seasons. The number and location of the sensory structures has been found to vary among the investigated taxa. The differences are related to the larval behavioural types, and are an adaptive response to different lifestyles, feeding habits and use of space.     

Human granulocyte surface molecules identified by murine monoclonal antibodies

We have investigated the nature of the antigens recognized by four classes of mouse anti-human monoclonal antibodies that characteristically reacted with neutrophilic granulocytes and their precursor cells, but not with monocytes or other normal hemopoietic cells. The antigenic targets of the majority (9/12) of the independently isolated monoclonal antibodies were present on two surface glycoproteins (Mr 145,000 and 105,000) and glycolipids. This antigen(s) was also detected on granulocyte precursor cells, including the bone marrow granulocyte/monocyte progenitor cells (CFU-GM). The same antigen(s) detected by these monoclonal antibodies was also present in non-hemopoietic cell lines (colon carcinoma and neuroblastoma). Three other antigens, defined by monoclonal antibodies AHN-8, L12.2, and L13.1 and present on granulocytes and their mid-late precursor cells, could not be identified as proteins but were detected in a protein-free glycolipid extract of these cells. The diversity of the antigens was confirmed by cross-competition experiments and by the identification of their different patterns of reactivity with cell lines and bone marrow cells.     

Peptidoglycan maturation enzymes affect flagellar functionality in bacteria

The flagellar machinery is a highly complex organelle composed of a free rotating flagellum and a fixed stator that converts energy into movement. The assembly of the flagella and the stator requires interactions with the peptidoglycan layer through which the organelle has to pass for externalization. Lytic transglycosylases are peptidoglycan degrading enzymes that cleave the sugar backbone of peptidoglycan layer. We show that an endogenous lytic transglycosylase is required for full motility of Helicobacter pylori and colonization of the gastric mucosa. Deficiency of motility resulted from a paralysed phenotype implying an altered ability to generate flagellar rotation. Similarly, another Gram‐negative pathogen Salmonella typhimurium and the Gram‐positive pathogen Listeria monocytogenes required the activity of lytic transglycosylases, Slt or MltC, and a glucosaminidase (Auto), respectively, for full motility. Furthermore, we show that in absence of the appropriate lytic transglycosylase, the flagellar motor protein MotB from H. pylori does not localize properly to the bacterial pole. We present a new model involving the maturation of the surrounding peptidoglycan for the proper anchoring and functionality of the flagellar motor.     

The avoidance of self-interference in the endemic daffodil Narcissus cyclamineus (Amaryllidaceae)

Hermaphrodite flowers usually possess floral traits to avoid the negative effects derived from inbreeding depression and/or self-interference between pollen export and reception, both acting as the main selective pressures on those floral traits. The avoidance of self-interference is widely accepted as the primary force promoting the separation between sexes within the flowers in time (dichogamy) and/or space (herkogamy) for self-incompatible species, which are already protected from the negative effects of inbreeding depression by the incompatibility system. Different degrees of incompatibility, herkogamy, and dichogamy have been reported for the genus Narcissus. However, the only mechanism for the separation of sexes reported up to date for Narcissus cyclamineus is herkogamy, while the presence of dichogamy and the type of incompatibility in this species remain uncertain. In this study, we analyze the patterns of sexual reproduction in N. cyclamineus to ascertain whether there is any selective pressure favouring sexual segregation or its maintenance and their mechanisms. N. cyclamineus is self-incompatible and dichogamy can be rejected for this species. Even though the species is self-incompatible, when cross-pollination is preceded by self-pollination the number of ovules available for legitimate crosses is diminished (ovule discounting). Pollinators are scarce during the flowering period, resulting in pollen limitation. It is suggested that both the scarcity of pollinators and ovule discounting may be acting synergically to promote herkogamy or its maintenance in this species.     

Egg hatching response to a range of air humidities for six species of predatory mites

The efficiency of biological control agents is often affected by local conditions such as low relative humidity (r.h.). This is especially true for mites of the family Phytoseiidae, and particularly for their egg stage. A key issue in biological control is thus to assess the drought tolerance of phytoseiid species that are (or that will be) commercialized. In this study, we evaluated the egg hatching response to a humidity range for six species of Phytoseiidae, by assessing the relative air humidity and vapour pressure deficit (VPD) at which 50% of the eggs hatch: r.h.₅₀ and VPD₅₀. Typhlodromus athiasae Porath & Swirskii and Phytoseiulus longipes Evans (Argentinean strain) were the most drought‐tolerant, with a r.h.₅₀ of 43% (VPD₅₀ = 18.2 hPa) and 43% (18.1 hPa), respectively. The most drought‐sensitive species were Amblyseius swirskii (Athias‐Henriot) (63%, 11.4 hPa), Phytoseiulus macropilis (Banks) (69%, 9.8 hPa), and Phytoseiulus persimilis Athias‐Henriot (70%, 9.4 hPa). Neoseiulus idaeus Denmark & Muma and P. longipes (Chilean strain) showed intermediate responses with 49% (16.1 hPa) and 50% (15.9 hPa), respectively. These results were similar to what had been obtained for the same species by other authors. However, unexpected inter‐ and intraspecific differences uncorrelated to climatic conditions of the area of origin were observed. The possibility to localize species and/or populations that could be efficient as biological control agents under dry conditions is discussed.