Étude quantitative du parasitisme réalisé parTrichomalopsis peregrina dans les nids d'hiver d'Euproctis chrysorrhoea en chenaie

Les interactions h?te-parasito?de ont été abordées dans le cas du systèmeTrichomalopsis peregrina G. (Pteromalidae) et son h?te grégaireEuproctis chrysorrhoea L. (Lymantriidae), au cours de la phase diapausante des chenilles dans les nids d'hiver tissés par ce ravageur. Un échantillon de 1 432 nids d'hiver a été récolté dans 8 peuplements de chênes dans la région toulousaine durant l'hiver 1988. Le volume du nid a été utilisé comme estimateur du nombre de chenillesh?tes dans les nids et la réponse du parasito?de a été comparée à celle prévue par la théorie de la stratégie optimale de recherche. Les principaux résultats sont les suivants:

Alternative Pathways of Glucose Utilization in Brain; Changes in the Pattern of Glucose Utilization in Brain Resulting from Treatment of Rats with 6-Aminonicotinamide

The effect of 6-aminonicotinamide (6AN) treatment on the activities of alternative pathways of glucose metabolism in 20-day-old rat brain was evaluated by measurements of yields of 14CO2 from glucose labeled with 14C on carbons 1, 2, 3 + 4, or 6 and uniformly labeled glucose, and from the incorporation of 14C from specifically labeled glucose into lipids by brain slices from cerebral hemispheres and cerebellum. At the highest dose of 6AN used (35 mg/kg body weight) there was a significant decrease in the 14CO2 yields via the pentose phosphate pathway, the glycolytic route, tricarboxylic acid (TCA) cycle, and via the glutamate-gamma-aminobutyric acid pathway. Giving a graded series of doses (20-35 mg 6AN/kg body weight) revealed a hierarchy of responses in which the pentose phosphate pathway, lactate, glyceride-glycerol, and fatty acid formation were most sensitive, followed, in sequence, by the pyruvate dehydrogenase reaction, the glutamate-gamma-aminobutyrate route and, finally, the TCA cycle. The nature of the blocks in the various pathways was examined by the use of metabolite profiles.     

EGb761 Blocks MPP+-Induced Lipid Peroxidation in Mouse Corpus Striatum

EGb761 has been suggested to be an antioxidant and free radical scavenger. Excess generation of free radicals, leading to lipid peroxidation (LP), has been proposed to play a role in the damage to striatal neurons induced by 1-methyl-4-phenylpyridinium (MPP⁺). We investigated the effects of EGb761 pretreatment on MPP⁺ neurotoxicity. C-57 black mice were pretreated with EGb761 for 17 days at different doses (0.63, 1.25, 2.5, 5 or 10 mg/kg) followed by administration of MPP⁺, (0.18, 0.36 or 0.72 mg/kg). LP was analyzed in corpus striatum at 30 min, 1 h, 2 h and 24 h after MPP⁺ administration. Striatal dopamine content was analyzed by HPLC at the highest EGb761 dose at 2 h and 24 h after MPP⁺ administration. MPP⁺-induced LP was blocked (100%) by EGb761 (10 mg/kg). Pretreatment with EGb761 partially prevented (32%) the dopamine-depleting effect of MPP⁺ at 24 h. These results suggest that supplements of EGb761 may be effective at preventing MPP⁺-induced oxidative stress.     

Indigenous Knowledge of Rock Kangaroo Ecology in Western Arnhem Land, Australia

Indigenous peoples of western Arnhem Land, central northern Australia, have detailed knowledge of the rock kangaroos of the region, species that are little known to science. Information about the ecology of the species is required for their conservation and management. Ethnoecological studies can assist senior indigenous people with transfer of knowledge and can give respect and meaningful employment to those involved. We used semidirected interviews in the regional vernacular, Bininj Kunwok, to record indigenous knowledge of the ecology of the four rock kangaroo species (Petrogale brachyotis, P. concinna, Macropus bernardus and M. robustus). Discussions focussed on habitat preferences, diet, activity patterns, reproduction, predation, and hunting practices. The ethnoecological knowledge of the rock kangaroo species was extensive, and both complemented and extended that reported in the scientific literature. In contrast to scientific understanding of taxonomy and ecology, consultants recognized the rock kangaroos as a natural group. They also described subtle differences in the species’ comparative ecology. The methodology used proved highly successful and we recommend recording indigenous knowledge of the ecology of fauna species in the local vernacular wherever possible. This study is one of the most comprehensive ethnozoological studies of a group of species undertaken in Australia.

The influence of plant growth regulators on the growth of the embryonic axes of red- and far-red-treated lettuce seeds

The influence of several plant growth regulators on the growth of the embryonic axes from red- and far-red-(R- and FR-)treated lettuce (Lactuca sativa L., cv. Grand Rapids) seeds was examined; as shown previously, the water potential of the axes from R-treated seeds has been lowered by 3.5–5.6 bars compared to that in axes from FR-treated ones. Kinetin and abscisic acid (ABA), when included in the incubation medium, reduced the elongation of the axes whereas fusicoccin stimulated it; however, these effects were the same in axes of both R- and FR-treated seeds. In contrast, elongation of axes from FR-treated seeds was stimulated by gibberellic acid (GA₃, but elongation of axes from R-treated ones was not affected by this hormone. This latter result indicates that gibberellins may be involved in the phytochrome-mediated growth responses in lettuce axes.When the root caps of the embryos were removed prior to light treatment, R was still able to induce a water-potential decrease in the embryonic axes, indicating that at least a portion of the active Pfr resides in the axis and not the root cap.Abbreviations ABA abscisic acid - FR far red light - GA₃ gibberellic acid - PEG polyethylene glycol - Pfr far-red-absorbing form of phytochrome - R red light     

Two-stage culture for producing berberine by cell suspension and shoot cultures of <Emphasis Type="Italic">Berberis buxifolia</Emphasis> Lam

In vitro cultures of Berberis buxifolia were established using thidiazuron (4.5, 23 and 45 mM) or picloram (4 and 40 mM) as plant growth regulators for sustaining growth. For producing berberine, a two-stage culture was performed. In the first step, thidiazuron or picloram were used for biomass production followed by the production stage where benzylaminopurine (4.4 mM) was added as a plant growth regulator. Berberine yields (102 mg g⁻¹ DW) and in vitro shoot cultures (200 mg g⁻¹ DW) were significantly lower than those of whole plants in the field (416 mg g⁻¹ DW). The highest productivity (0.18 mg 1⁻¹ day⁻¹) was attained using picloram (either 4 on 40 mM) in the first stage for producing biomass.     

Ii-Key/HER-2/<Emphasis Type="Italic">neu</Emphasis> MHC class-II antigenic epitope vaccine peptide for breast cancer

Purpose Cytotoxic T lymphocytes (CTL)- and T-helper cell-specific, and major histocompatibility complex (MHC) class-I and class-II peptides, respectively, of the HER-2/neu protein, induce immune responses in patients. A major challenge in developing cancer peptide vaccines is breaking tolerance to tumor-associated antigens which are functionally self-proteins. An adequate CD4+ T-helper response is required for effective and lasting responses.Methods Stimulating anti-cancer CD4+ T cell responses by MHC class-II epitope peptides has been limited by their weak potency, at least compared with tight-binding MHC class-I epitope peptides. Previously, a potent T-cell response to a MHC class-II epitope was engineered by coupling the N-terminus of the pigeon cytochrome C [PGCC(95–104)] MHC class-II epitope to the C-terminus of an immunoregulatory segment of the Ii protein (hIi77–81, the Ii-Key peptide) through a polymethylene spacer.Results In vitro presentation of the MHC class-II epitope to a T hybridoma was enhanced greatly (>250 times). Now, an Ii-Key/HER-2/neu (777–789) MHC class-II epitope hybrid peptide stimulated lymphocytes from both a healthy donor and a patient with metastatic breast carcinoma. The in vitro primary stimulation with the hybrid peptide strongly activated IFN- release, whereas the epitope-only peptide was weakly active. In fact, the hybrid stimulated IFN- release as well as the wild-type peptide when augmented with IL-12; however, the hybrid was comparable to free peptide in stimulating IL-4 release. This pattern is consistent with preferential activation along a non-tolerogenic Th1 pathway.Conclusion Such Ii-Key/MHC class-II epitope hybrid peptides have both diagnostic and therapeutic applications.     

Non-invasive quantification of peripheral arterial volume distensibility and its non-linear relationship with arterial pressure

Arterial wall function is associated with different physiological and clinical factors. Changes in arterial pressure cause major changes in the arterial wall. This study presents a simple non-invasive method to quantify arterial volume distensibility changes with different arterial pressures.The electrocardiogram, finger and ear photoplethysmogram were recorded from 15 subjects with the right arm at five different positions (90°, 45°, 0°, ?45° and ?90° referred to the horizontal level). Arm pulse propagation time was determined by subtracting ear pulse transit time from finger pulse transit time, and was used to obtain arterial volume distensibility. The mean arterial blood pressure with the arm at the horizontal level was acquired, and changes with position were calculated using the hydrostatic principle that blood pressure in the arm is linearly related to its vertical distance from the horizontal level.The mean arm pulse propagation times for the five different positions were 88, 72, 57, 54 and 52 ms, with the corresponding mean arterial volume distensibility of 0.234%, 0.158%, 0.099%, 0.088% and 0.083% per mmHg. For all consecutive changes in arm position, arm pulse propagation time and arterial volume distensibility, were significantly different (all probability P<0.05). The slopes of arm pulse propagation time and arterial volume distensibility against arterial pressure decreased significantly between each consecutive arm position from 90° to ?45° (all P<0.01), indicating significant non-linearity.The experimental results fitted the physiological exponential model and Langewouters’ arctangent model well, and were also comparable to published data with arterial volume distensibility approximately tripling for transmural pressure changes from 101 to 58 mmHg.In conclusion, the inverse and non-linear relationship between arterial volume distensibility and arterial pressure has been quantified using a simple arm positioning procedure, with the greatest effect at low pressures. This work is an important step in developing a simple non-invasive technique for assessing peripheral arterial volume distensibility.     

Simultaneous selection of mutants in gluconeogenesis and nucleoside catabolism in Salmonella typhimurium

Penicillin selection in minimal thymidine medium, used to select mutants in deoxynucleoside catabolism, also yields a high percentage (37%) of mutants in fructose diphosphatase. The expression of the deo regulon is retarded in the mutants defective in the gluconeogenic pathway.