In vivo analysis of a new lacZ retrovirus vector suitable for cell lineage marking in avian and other species

To obtain a replication-defective retrovirus vector well suited for cell lineage marking in early avian embryos, we have constructed and tested a derivative of the avian spleen necrosis virus (SNV) carrying the marker gene lacZ. Consistently high titers of this virus, designated CXL, were produced from retroviral packaging cells with no evidence of contaminating helper virus even after 12 months of continuous culture. CXL expresses lacZ strongly and stably in avian cells and has a host range that extends to other avian and some mammalian species. We show that CXL has the potential to mark a wide variety of chick embryo cell types by infection in ovo. The high titers obtainable with this virus can provide a significant advantage over alternative lacZ vectors, especially in lineage marking of early stage embryos. As an example of this, we show that CXL can be used to mark cells of the precardiac mesoderm in stage 4-5 chick embryos.     

Identification of nuclear factor IV/Ku autoantigen in a human 2D-gel protein database. Modification of the large subunit depends on cellular proliferation

Nuclear Factor IV (NFIV) is a heterodimeric DNA-binding protein from HeLa cells, recognizing molecular ends and is identical to the autoantigenic target Ku. We have identified the two NFIV/Ku subunits, by comigration, in the 2D-gel database of transformed human amnion cell (AMA) proteins. We observed that the large subunit of NFIV/Ku consists of at least 3 charge variants that correspond to SSP IEFs 5705 (81.2 kDa, pI 5.74), 6707 (81.2 kDa, pI 5.67) and 6706 (81.9 kDa, pI 5.60) in the AMA catalogue. The relative amounts of the 2 major variants (IEFs 5705 and 6707) was dependent on the state of cell proliferation. Inhibition of DNA-synthesis by hydroxyurea also changed the relative levels of the variants, whereas aphidicolin or a thymidine block had no effect. These results suggest a possible role for NFIV/Ku in DNA replication.     

The introduction ofMimorista pulchellalis [Lepidoptera: Pyraustidae] into South Africa for the biological control of jointed cactus,Opuntia aurantiaca. 2. Field evaluation

The mothMimorista pulchellalis was monitored over 2 years after liberation in a jointed cactus (Opuntia aurantiaca) infestation in South Africa. Moth and cactus densities were estimated using a system of randomly-assigned quadrats and the impact of the moth on the cactus population quantified. Moths appeared adapted to survive on the etiolated form of jointed cactus plants, killing approximately 1% of the increment in small plants annually. Large plants were also attacked but damage was negligible. The moths occurred in low numbers throughout the study period and generally went through 3 generations in a year.

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Résumé La pyraleMimorista pulchellalis a été surveillée durant les deux années qui suivirent sa libération dans une infestation de figuier de Barbarie en Afrique du Sud. Les densités de pyrale et de cactus ont été estimées en utilisant un système de quadrats distribués au hasard et l'impact de la pyrale sur la population de cactus a été quantifiée. Les pyrales semblaient adaptées à survivre sur la forme étiolée des plants de cactus tuant approximativement 1% de l'accroissement annuel des petits plants. Les gros plants étaient aussi attaqués, mais les dégats étaient négligeables. La pyrale existait en faibles nombres durant toute la période d'étude et elle présentait généralement 3 générations par an.

     

Isolation of nitrogen deregulated mutants of erythromycin biosynthesis

Summary Ammonium represses erythromycin synthesis bySaccharopolyspora erythraea and insensitive mutants to this effect were isolated. Six mutants were selected and one of them produces 50% more antibiotic than the wild type in 100 mM NH₄Cl as nitrogen source. Glutamine synthetase and alanine dehydrogenase levels in the mutants were determined and no differences with wild type strain were observed.     

Dynamics of functional reciprocal connections between cerebral motor cortex neurons under stimulation in cats

Activity was recorded from neurons belonging to the representation of the forelimb in the motor cortex (sulcus cruciatus, L 7–9 mm) using multiple multi-channel/barrel electrodes during acute experiments on cats. Cross-correlation analysis of impulse trains was adopted to investigate dynamics of interneuronal connections during passive flexion and electrical stimulation of the limb contralateral to the recording site. It was found that neither passive bending nor electrical stimulation of the limb leads to a significant increase in the total number of direct relationships between cortical neurons. At the same time, passive flexion does produce a considerable decrease in the number of instances of both inputs operating in neighboring neurons (50–100 µm apart) and an increase in cells located further (between 100 and 400 µm) apart. Some increase in the number of direct inhibitory interactions between neighboring neurons was observed during electrical stimulation.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Nentskii Institute of Experimental Biology, Warsaw, Poland. Center of Experimental and Clinical Medicine, Warsaw, Poland. Translated from Neirofiziologiya, Vol. 23, No. 1, pp. 73–80, January–February, 1991.