Evaluation of strain competitiveness in Rhizobium leguminosarum bv phaseoli using a nod + fix− natural mutant

Competition from native soil rhizobia is likely to be an important factor limiting Phaseolus vulgaris L. inoculant response in Latin America. We used UMR 1116, a nod ⁺ fix^– natural mutant of Rhizobium leguminosarum bv phaseoli strain CC511, as a reference strain to study competition for nodulation sites in this species. When P. vulgaris cv Carioca was planted in soils containing different proportions of UMR 1116 and the effective and competitive strain UMR 1899, UMR 1116 occupied more than 50% of the nodules at all inoculant ratios tested, though increasing the proportion of UMR 1899 in the inoculant did enhance the number and percentage of effective nodules and plant dry weight. Sixty two strains of bean rhizobia were tested in competition with UMR 1116. An inoculant ratio of 1:1 was used, with all strains applied to the soil rather than to seeds. Strains varied in the number and percentage of effective nodules produced in competition with UMR 1116, and in plant dry weight, and there was a strong correlation between variation in each of these traits and plant N accumulation. Seven of the strains (UMR 1073, 1084, 1102, 1125, 1165, 1378 and 1384) were identified as both superior in competitive ability and active in N₂ fixation. Site of placement of the inoculant and ambient temperature influenced strain response.Journal paper 16736, Agricultural Experiment Station, University of Minnesota, St. Paul, MN 55108, USA     

Susceptibility of autologous target cells to lysis by lymphokine-activated effectors from interferon-α-treated chronic myelogenous leukaemia patients

Summary Chronic myelogenous leukemia (CML) patients in chronic phase display compromised lymphokine-activated killer (LAK) cell induction, which is partly restored after therapy with interferon . However, the relative resistance of the leukemic cells from these patients to autologous or allogeneic LAK lysis is not affected by this treatment. In an attempt to render CML cells more susceptible to lysis or cytostasis, they were precultured in serum-free medium with or without recombinant growth factors. In eight patients studied, interleukin-3 (IL-3) significantly enhanced the spontaneous short-term (6-day) proliferation of CML cells, with retention of ability to form colonies in methylcellulose. Culture in either medium alone or IL-3 led to a significant enrichment of CD14⁺ and CD33⁺ cells but to a reduction in CD34⁺ cells. In contrast, culture of the same cells in IL-2 (to generate autologous LAK activity) resulted in a loss of CD14⁺ and CD33⁺ as well as CD34⁺ cells but in a significant increase in CD3⁺ and CD56⁺ cells. Despite similarities in their phenotypes, IL-3 cultured cells but not those cultured in medium alone acquired susceptibility to lysis by the IL-2-cultured autologous LAK cells. These results may have significance for the design of novel combination immunotherapy in CML.This work was supported in part by the Deutsche Forschungsgemeinschaft (SFB 120)     

The role of carrier ATPases and neuromediators in neurological disorders

Physiological and biochemical processes which take place in the nervous system at stroke and neurotrauma are reviewed, and the experience of using low doses of steroid derivatives with piridamole in the treatment of central nervous system (CNS) disorders is summarized. ATPases (including Na,K-ATPase) are reported to play an important role in CNS functioning, the correlation between Na,K-ATPase activity and the extent of CNS injury is revealed. The use of NMR-spectroscopy method for investigation of brain and spinal cord condition in vivo is suggested.     

Blood flow changes following 137Cs irradiation in a rat glioma model

Blood flow changes in response to 20 Gy 137Cs whole brain irradiation were measured with quantitative autoradiography of [14C]iodoantipyrine (IAP) in intracerebral grafts of the 36B-10 rat glioma, the brain around tumor (BAT), the contralateral corpus callosum, and the contralateral cerebral cortex. Irradiations were delivered on Day 14 post-transplantation, and measurements of flow (F) were performed with IAP on Day 15 or Day 16. Mean values of F were determined in individual tumors and in treatment groups. In 15- and 16-day-old unirradiated control tumors, the group mean F was 0.31 ml.g-1.min-1. In both 15- and 16-day-old tumor groups irradiated on Day 14 (Day 1 and 2 postirradiation tumors) the mean F for each day's group was 0.52 ml.g-1.min-1, 68% higher than the control (P less than 0.01). Flow in the BAT and the contralateral corpus callosum similarly was increased at these times (P less than 0.01). Flow in the contralateral cerebral cortex was 1.1, 1.5, and 1.3 ml.g-1.min-1 in the control, 1 day postirradiated, and 2 day postirradiated groups, respectively, but these increases were not significantly different from the control. These data indicate that flow increases in the intracerebral gliomas as well as in normal brain regions during the 2 days following 20 Gy irradiation. Changes such as these following radiotherapy may have important effects on the bioavailability of chemotherapeutic drugs.     

Survey of general practitioners' attitudes to AIDS in the North West Thames and East Anglian regions

As the numbers of people suffering from human immunodeficiency virus infection and the acquired immune deficiency syndrome (AIDS) increase, so will the contribution to care required from general practice. A postal questionnaire survey was therefore carried out among general practitioners in the North West Thames and East Anglian regions to determine their attitudes to AIDS and the issues it raises for them. One hundred and thirty seven questionnaires were returned (response rate 57%) and four factors underlying the doctors'' attitudes identified; these concerned disease control, general practitioner care, patient support, and perception of seriousness. There were wide divergencies of attitude among the general practitioners, younger doctors being more in line with specialist thinking on AIDS than older colleagues, and evidence of important gaps between policies advocated by AIDS specialists and bodies of opinion in general practice.Attitudes to AIDS in general practice may partly be a function of personal experience; further study is required.     

Anti-adenovirus type 5 cytotoxic T lymphocytes: immunodominant epitopes are encoded by the E1A gene.

Virus specific, major histocompatibility complex-restricted, cytotoxic T lymphocytes (CTL) generated in Fischer strain rats infected with human adenovirus type 5 (Ad5) were found to recognize antigenic determinants encoded within the Ad5 early region 1A (E1A) gene. Preliminary mapping studies suggest that the E1A CTL epitopes are encoded within the regions between bp 625 to 810 and 916 to 974 in the first exon of this gene. These epitope-coding regions occur within subregions of E1A that are conserved functionally, and to some extent structurally (approximately 50% sequence homology), among adenoviruses of different groups. Nevertheless, Ad5-specific CTL lysed only targets infected with adenoviruses of the same group (group C; e.g., Ad2) and not targets infected with adenoviruses of different groups (groups A, B, and E). These results suggest that virus-specific CTL may limit adenoviral dissemination by destroying virus-infected cells at an early stage in the viral replicative cycle, during E1A gene expression. Expression of other adenovirus genes does not appear to be required to target infected cells for elimination by CTL.     

Complete Amino Acid Sequence of a Polypeptide from Zea mays Similar to the Pathogenesis-Related-1 Family

A polypeptide serologically related to the tobacco pathogenesis-related-1 family of proteins has been purified from the root tissue of maize (Zea mays L.), and the complete amino acid sequence has been determined. The mature protein has a calculated molecular weight of 14,970 and isoelectric point of 4.2. The maize protein shows 66 to 68% amino acid identity with the tobacco pathogenesis-related-1 family and 55% identity with the tomato p14 protein.     

Ecological correlates of small mammal community structure in the semi-arid Karoo, South Africa

The understanding of the determinants of small mammal community structure in arid and semiarid ecosystems is of importance, both in the light of the role that small mammals play, and the impact of livestock grazing on the flora of these systems. In a study aimed at identifying these determinants, small mammal assemblages and environmental features were quantified at six localities (a gradient of floristic structure, with constant annual rainfall) across the southern Karoo, South Africa. Stepwise variable regression indicated that small mammal diversity was correlated with plant and rock cover, as well as plant cover and horizontal foliage diversity at intermediate heights (40–60 cm). Initially, small mammal diversity increased with increasing plant cover, but decreased at cover levels greater than 30%. This relationship is similar to that found in other desert systems, although the peak in diversity found here is at higher levels of plant cover than found previously. I suggest that this higher peak may be owing to the lack of reliance on granivory by these animals, which are relatively omnivorous. This model may therefore explain the conflicting reports on the impact of livestock grazing on desert small mammals, with small mammal diversity decreasing with grazing below the peak, and increasing with grazing above the peak.