Virus Aggregation as the Cause of the Non-neutralizable Persistent Fraction

The non-neutralizable or persistent fraction of virus populations has been found to be caused by aggregated virus. Detailed investigation was performed with the prototype strain of echovirus type 4 (Pesascek), as this virus is notorious for its large non-neutralizable fraction. When Pesascek virus was clarified by low-speed centrifugation, homologous antiserum hardly neutralized the virus. However, when the virus was filtered through membranes having a porosity only twice the diameter of the virus, monodispersed virus was obtained which was efficiently neutralized. Serum titers were up to 1,000 times higher if the neutralization test was carried out with monodispersed virus. Virus in non-neutralizable aggregates was found to constitute 30% of the infective units of unfiltered Pesascek virus but only 0.1% of the antigenically related DuToit strain. This explains why DuToit strain has been a more satisfactory indicator strain for detecting type 4 antibodies, regardless of the echo 4 strain used for inducing the antibodies. Clarified suspensions and ultrafiltrates of viruses belonging to the picorna-, reo-, myxo-, adeno-, herpes-, and poxvirus groups were studied. Clarified suspensions yielded persistent fractions of 0.005% for poliovirus, of 0.1% for reovirus, of 0.6% for influenza virus, of <0.001% for adenovirus, of 0.06% for herpesvirus, and of 10 to 30% for vaccinia virus. In all cases the persistent fractions were removed by membrane filters which had a pore diameter no larger than twice that of the virus under test, and the high concentration of virus in each ultrafiltrate was completely neutralized by antiserum.     

Electronic recording of mosquito activity

Spontaneous locomotor activity of mosquitoes (Aedes aegypti) was tested over twenty-four hour periods using an electronic recording device which gave a permanent time graph of activity. Single mosquitoes were placed on a wire grid with alternate strands connected to the positive and negative poles of an electric circuit. Each time the mosquito moved, the electric current changed and the event was recorded by a pen-writer. The number of peaks per time interval gave the index of activity. Variables which may affect activity include age, physiological state, sex and strain. A distinct activity cycle was evident in both virgin and mated females but not in males; peak activity came in the early evening and activity was lowest in the early afternoon.

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Zusammenfassung Die spontane lokomotorische Aktivität von Mücken (Aedes aegypti) wurde über 24stündige Perioden mit Hilfe einer elektronischen Registriereinrichtung untersucht, die eine ununterbrochene Zeitschreibung der Aktivität ergab. Einzelne Mücken wurden auf einen Gürtel feiner Drähte gesetzt, deren Stränge abwechselnd zu den positiven und negativen Polen eines elektrischen Stromkreises führten. Jedesmal wenn sich die Mücke bewegte, änderte sich der elektrische Stromfluß; dieses Ereignis wurde von einer Schreibfeder aufgezeichnet. Die Anzahl der Ausschläge pro Zeiteinheit ergab den Aktivitätsindex. Variable, welche die Aktivität beeinflussen, umfassen Alter, physiologischen Zustand, Geschlecht und Abstammung. Bei jungfräulichen wie bei begatteten Weibchen war ein bestimmter Aktivitätszyklus erkennbar, jedoch nicht bei Männchen; der Aktivitätsgipfel lag in den frühen Abendstunden und die Aktivität war am zeitigen Nachmittag am geringsten.

     

Expression of members of the Saccharomyces cerevisiae hsp70 multigene family

The hsp70 multigene family of Saccharomyces cerevisiae is a complex multigene family, composed of members exhibiting complex patterns of regulation. Expression of some members is induced after a heat shock, whereas expression of others is repressed. Some members of the family are expressed during exponential growth. One gene, SSA3, shows an unusual pattern of expression during approach to stationary phase. While most RNAs decrease in abundance, SSA3 RNA levels dramatically increase. The constitutive expression of SSA3 in cells lacking adenylate cyclase activity suggests that cAMP modulates SSA3 expression.     

Stress and relapse of breast cancer.

To elucidate the association between stressful life events and the development of cancer the influence of life stress on relapse in operable breast cancer was examined in matched pairs of women in a case-control study. Adverse life events and difficulties occurring during the postoperative disease free interval were recorded in 50 women who had developed their first recurrence of operable breast cancer and during equivalent follow up times in 50 women with operable breast cancer in remission. The cases and controls were matched for the main physical and pathological factors known to be prognostic in breast cancer and sociodemographic variables that influence the frequency of life events and difficulties. Severely threatening life events and difficulties were significantly associated with the first recurrence of breast cancer. The relative risk of relapse associated with severe life events was 5.67 (95% confidence interval 1.57 to 37.20), and the relative risk associated with severe difficulties was 4.75 (1.58 to 19.20). Life events and difficulties not rated as severe were not related to relapse. Experiencing a non-severe life event was associated with a relative risk of 2.0 (0.62 to 7.47), and experiencing a non-severe difficulty was associated with a relative risk of 1.13 (0.38 to 3.35). These results suggest a prognostic association between severe life stressors and recurrence of breast cancer, but a larger prospective study is needed for confirmation.     

Characterization of a Nerve Growth Factor-Stimulated Protein Kinase in PC12 Cells Which Phosphorylates Microtubule-Associated Protein 2 and pp250

Treatment of PC12 cells with nerve growth factor (NGF) resulted in the rapid, but transient, activation of a protein kinase which specifically phosphorylated an endogenous 250-kDa cytoskeletal protein (pp250). We report that the microtubule-associated protein, MAP2, is an alternative substrate for the NGF-activated kinase. NGF treatment maximally activated the kinase within 5 min; however, the activity declined with longer exposure to NGF. The enzyme was localized predominantly in microsomal and soluble fractions and phosphorylated MAP2 on serine and threonine residues. The soluble enzyme was fractionated by DEAE chromatography and gel filtration and had an apparent Mr of 45,000. The enzyme was purified to near homogeneity by chromatofocussing and had a pI of 4.9. Kinetic analysis revealed that NGF treatment caused a sevenfold increase in Vmax for MAP2. The Km with respect to the MAP2 substrate was approximately 50 nM and was not altered by NGF treatment. A novel feature of the NGF-stimulated enzyme was its sharp dependence on Mn2+ concentration. The active enzyme is likely to be phosphorylated, because inclusion of phosphatase inhibitors was required for recovery of optimal activity and the activity was lost on treatment of the enzyme with alkaline phosphatase. Histones, tubulin, casein, bovine serum albumin, and the ribosomal subunit protein S-6 were not phosphorylated by this enzyme. The NGF-stimulated kinase was distinct from A kinase, C kinase, or other NGF-stimulated kinases. The rapid and transient activation of the protein kinase upon NGF treatment suggests that the enzyme may play a role in signal transduction in PC12 cells.     

Labelling oligonucleotides to high specific activity (I).

The normal procedure for labelling oligonucleotides radioactively is the use of polynucleotide kinase and gamma 32P-ATP. However, this has the disadvantage of only introducing one labelled base per molecule of the oligonucleotide. In this paper we describe an approach based on primer/template combinations using conventional fill-in conditions followed by the release of the labelled sequence by digestion with uracil-DNA glycosylase.     

Effect of oxygen pressure on synthesis and export of nitrogenous solutes by nodules of cowpea

Nodules of cowpea plants (Vigna unguiculata (L.) Walp. cv. Vita 3 :Bradyrhizobium CB756) cultured for periods of 23 d with their root systems maintained in atmospheres containing a range of partial pressures of O₂ (pO₂; 1–80%, v/v, in N₂) formed and exported ureides (allantoin and allantoic acid) as the major products of fixation at all pO₂ tested. In sub-ambient pO₂ (1 and 2.5%) nodules contained specific activities of uricase (urate: O₂ oxidoreductase; EC 1.7.3.3) and allantoinase (allantoin hydrolyase; EC 3.5.2.5) as much as sevenfold higher than in those from air. On a cell basis, uninfected cells in nodules from 1% O₂ contained around five times the level of uricase. Except for NAD: glutamate synthase (EC 1.4.1.14), which was reduced in sub-ambient O₂, the activities of other enzymes of ureide synthesis were relatively unaffected by pO₂. Short-term effects of pO₂ on assimilation of fixed nitrogen were measured in nodules of air-grown plants exposed to subambient pO₂ (1, 2.5 or 5%, v/v in N₂) and¹⁵N₂. Despite a fall in total¹⁵N₂ fixation, ureide synthesis and export was maintained at a high level except in 1% O₂ where formation was halved. The data indicate that in addition to the structural and diffusional adaptations of cowpea nodules which allow the balance between O₂ supply and demand to be maintained over a wide range of pO₂, nodules also show evidence of biochemical adaptations which maintain and enhance normal pathways for the assimilation of fixed nitrogen. This work was supported by a grant from the Australian Research Council (to C.A.A.) and an Australian Development Assistance Bureau postgraduate fellowship (to F.D.D.).     

Morphological and structural adaptation of nodules of cowpea to functioning under sub- and supra-ambient oxygen pressure

Nodules of cowpea (Vigna unguiculata (L.) Walp. cv. Vita 3:Bradyrhizobium CB 756) from 28-d-old plants cultured for 23 d with their root systems maintained in O₂ levels from 1 to 80% (v/v, in N₂) in the external gas phase showed a range of structural changes which have been interpreted in relation to an over- or under-supply of O₂. A response to the partial pressure of O₂ in the gas phase (pO₂) was noted with respect to nodule size, lenticel development, the relative distributions of cortical and infected central tissue, the differentiation of cortex, especially the inner cortex, the frequency and size of infected and uninfected interstitial cells, the volume of extracellular spaces both in cortex and infected tissue, and in the frequency of bacteroids. As a consequence of these changes the surface area of inner cortex relative to the nitrogenase-containing units of fixing tissue (infected cells or bacteroids) was increased by as much as 20-fold. Effectiveness of bacteroid functioning increased from 0.10 ± 0.02 · 10^-9 μmol acetylene reduced per bacteroid in air-grown nodules to 0.9 ± 0.16 · 10^-9 (same units) per bacteroid in those cultured in 1% O₂. This work was supported by a grant from the Australian Research Council (to C.A.A.) and an Australian International Development Assistance Bureau postgraduate fellowship (to F.D.D.). The authors wish to thank Dr. W.F.C. Blumer for his considerable help with morphometric analysis, Dr. J. Kuo for guidance in the use of histological techniques, and to Dr. J.S. Pate for the suggestion that lenticel development might be quantified by surface staining of nodules.     

Chromosomal band assignments of the genes encoding human FKBP12 and FKBP13.

Human FKBP12 and FKBP13 are encoded by distinct genes designated FKBP1 and FKBP2, respectively. Human FKBP1 was previously characterized. The characterization of human FKBP2 is described. FKBP2 is three kb in length and contains six exons. Fluorescence in situ hybridization of FKBP1 and FKBP2 genomic probes to metaphase chromosomes localized FKBP1 to human chromosome 20 band p13 and FKBP2 to human chromosome 11 band q13.1-q13.3.