Induction of interleukin-2 receptor by tumor necrosis factor α on cultured ovarian tumor-associated lymphocytes

Summary We have recently reported that autologous tumor-specific cytotoxic T lymphocyte (CTL) lines and clones can be developed from lymphocytes infiltrating ovarian malignant ascites (TAL). In this study, we investigated the biological effects of tumor necrosis factor (TNF) in the induction, expansion, long-term proliferation and lytic function of CD8⁺ TAL. TNF up-regulated the IL-2 receptor (IL-2R) chain (Tac antigen) on the surface of CD3⁺ CD8⁺ CD4^– TAL, enhanced the proliferation of autologous tumor-specific CTL, and potentiated their lytic function in long-term cultures. Furthermore, in the induction and expansion phase of CD8⁺ TAL, the presence of TNF was associated with a selective increase in CD8⁺ IL-2R⁺ (Tac⁺) cells, and subsequent decrease in CD4⁺ IL-2R⁺ (Tac⁺) cells. These results suggest that the observed facilitation of the outgrowth of CD8⁺ cells in TAL cultures may be due, at least in part, to the up-regulation of IL-2R, and indicate the usefulness of TNF in the analysis of signalling in autologous tumor-reactive CTL.     

Characterization of cpsF and its product CMP-N-acetylneuraminic acid synthetase, a group B streptococcal enzyme that can function in K1 capsular polysaccharide biosynthesis in Escherichia coli

Group B Streptococcus (GBS) is the foremost cause of neonatal sepsis and meningitis in the United States. A major virulence factor for GBS is its capsular polysaccharide, a high molecular weight polymer of branched oligosaccharide subunits. N -acetylneuraminic acid (Neu5Ac or sialic acid), at the end of the polysaccharide side chains, is critical to the virulence function of the capsular polysaccharide. Neu5Ac must be activated by CMP-Neu5Ac synthetase before it is incorporated into the polymer. We showed previously that a transposon mutant of a serotype III GBS strain which had no detectable capsular Neu5Ac was deficient in CMP-Neu5Ac-synthetase activity (Wessels et al ., 1992). In this paper, we report the identification and characterization of cpsF , a gene interrupted by transposon insertion in the previously described Neu5Ac-deficient mutant. The predicted amino acid sequence of the cpsF gene product shares 57% similarity and 37% identity with CMP-Neu5Ac synthetase encoded by the Escherichia coli K1 gene, neuA . The enzymatic function of the protein encoded by cpsF was established by cloning the gene in E. coli under the control of the T7 polymerase/promoter. Lysates of E. coli in which the cpsF gene product was expressed, catalysed the condensation of CTP with Neu5Ac to form CMP-Neu5Ac. In addition, when a CMP-Neu5Ac synthetase-deficient mutant of E. coli K1 was transformed with cpsF , K1 antigen expression was restored. We conclude that cpsF encodes CMP-Neu5Ac synthetase in type III GBS, and that the GBS enzyme can function in the capsule-synthesis of a heterologous bacterial species.     

Decrease in tolerance to fenvalerate, in resistantHelicoverpa armigera after pupal diapause

Pyrethroid resistant and susceptible adults ofHelicoverpa armigera (Lepidoptera: Noctuidae) were screened for tolerance to pyrethroids after 6 wk or 12 wk pupal diapuse. Resistant larvae and F₂ larvae from a cross between resistant and susceptible parents (two replicates), were reared under conditions to induce pupal diapause. After eclosion, adults were tested in glass vials coated with the pyrethroid fenvalerate, at a dose (DD) that is known to discriminate between susceptible and heterozygous resistant individuals. In all diapause experiments, the frequency of resistance was lower in the test groups that had experienced diapause compared with the non-diapausing control group. The underlying cause of the decline is not certain but selective mortality of resistant versus susceptible individuals could not account for all the difference in two of the three experiments — tolerance to the pyrethroid, fenvalerate, is most likely to have declined either as a consequence of diapause or from the extended time of development associated with diapause. These results indicate that monitoring programs could underestimate pyrethroid resistance frequencies when usingH. armigera adults emerging from diapause.     

Effects of HCN, phenolic acids and related compounds in Sorghum bicolor on the feeding behaviour of the planthopper Peregrinus maidis

The feeding behaviour of the planthopper Peregrinus maidis was looked at in relation to the cyanide and phenolic compounds found in sorghum. Tests were carried out using both plant material and artificial media. HCN was found to be deterrent in long-term feeding tests with artificial media but it is unlikely to affect feeding when present in the plant. Mixtures of phenolic acids and their esters reduced feeding on artificial media when presented to the insects at concentrations similar to those occurring in young plants. Phenolic acid concentration was correlated with enhanced production of salivary sheath material in both plants and artificial media. In plants high concentrations of phenolic acids were correlated with a reduction in the ability of P. maidis to locate the phloem tissues.

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Résumé Les effets de l'HCN, des acides phénoliques et des composés voisins du Sorgho sur le comportement alimentaire de Peregrinus maidis, ont étré examinés en utilisant la plante ou un régime artificiel. HCN testé dans un régime artificiel est répulsif à des concentrations voisines de celles trouvées dans des plantes de 10 cm de haut. Des tests ultérieurs sur les effects de HCN sur le comportement de pigûre, montrent qu'il est plus toxique que répulsif. Les acides phénoliques et les esters èlevent l'activité perforatrice mais diminuent la prise de nourriture sur régime artificiel. De fortes teneurs en acides phénoliques dans les tissus de la plante sont aussi associées à des piqûres plus longues, à une plus grande ramification des piqûres et à une diminution correspondante de l'aptitude de P. maidis à découvrir le phloeme.

     

Effects of fetal intravenous glucose challenge in normal and growth retarded fetuses

Fetal intravenous glucose challenge test (0.75 g/kg of estimated fetal weight) was performed at 26-33 weeks gestation in 9 patients undergoing fetal blood sampling (FBS) by ultrasound guided needling from the umbilical vein. The indication for FBS was rapid karyotyping for fetal malformations in 5 (control group) and severe intrauterine growth retardation in the remaining 4 (IUGR group). Fetal blood samples were taken before the glucose infusion and after 1, 3, 5, 10 and 15 min; glucose and insulin were assayed on each occasion and acid-base balance at 0 and 5 min. Basal fetal pO2, pH, glucose and insulin were lower in the IUGR group than in controls. Following the glucose challenge, fetal glucose levels were similar in the two groups, but in the IUGR group the latter part of the glucose curve was characterized by a slower and delayed return to basal levels. In control fetuses the insulin response following the glucose challenge peaked at 3 min while in IUGR no change in insulin concentration was detected. Fetal pO2 did not change in either group; the median change in fetal pH was significantly different between the two groups (controls: +0.01; IUGR: -0.04; P less than 0.05) and there was a significant correlation between basal pO2 and the change in fetal pH (r = 0.79) (P less than 0.02). These results support the concept of a low energy state in IUGR. Fetal glucose supplementation in IUGR is unlikely to be of benefit and may even exacerbate underlying acidosis.     

Comparing temporal patterns in body condition of ringed seals living within their core geographic range with those living at the edge

Ecological theory suggests that demographic responses by populations to environmental change vary depending on whether individuals inhabit central or peripheral regions within the species’ geographic range. Here, we tested this prediction by comparing a population of ringed seals Pusa hispida located at high latitudes as part of their core range (core) with a population located at the southern extremity of their range (peripheral). First, we compared the two regions’ environmental trends in timing of sea-ice breakup and freeze-up, open-water duration and the North Atlantic Oscillation (NAO). We found that the core region shifted to progressively warmer conditions in the early 1990s; whereas, in the peripheral region, the warming trend shifted in 1999 to one with no warming trend but high inter-annual variability. Next, we examined how body condition, inferred from blubber depth, responded to temporal changes in sea-ice and climatic variables – variables that have been shown to influence ringed seal demography. Core seals displayed minimal seasonal changes in body condition; whereas peripheral seals displayed a 20–60% amplitude seasonal change in body condition with a phase shift to earlier initiation of fat accumulation and loss. Finally, we tested for interannual differences and found that both core and peripheral seals responded similarly with decreased body condition following more positive NAO. Environmental variables influenced body condition in opposite directions between the two regions with core seals declining in body condition with later spring breakup and shorter open-water duration, whereas peripheral seals showed opposite relationships. Seals living at the core likely benefit from an evolved match between adaptation and environmental variation resulting in dampened seasonal and interannual fluctuations in body condition. Knowledge of how different populations respond to environmental change depending on geographic location within a species range can assist in anticipating population specific responses to climate warming.