Construction of an improved baculovirus insecticide containing an insect-specific toxin gene

Baculoviruses provide alternatives to chemicals for controlling insect pests and can be applied by spraying. Baculoviruses have a limited host range, but work relatively slowly. They are dissolved in the midgut of insect larvae to release infectious virions which enter gut epithelial cells and begin to replicate. Replication in other organs causes extensive tissue damage and eventually death. This process can take 4-5 days, but in the field may last for more than a week, allowing the larvae to feed for longer and thereby damaging the host plant. Baculovirus expression vectors expressing foreign genes, such as those for insect-specific toxins, hormones or enzymes, might alleviate this problem. We have now constructed a recombinant baculovirus derived from Autographa californica nuclear polyhedrosis virus containing an insect-specific neurotoxin from the venom of the North African (Algerian) scorpion, Androctonus australis Hector. The neurotoxin acts by causing specific modifications to the Na+ conductance of neurons, producing a presynaptic excitatory effect leading to paralysis and death; it has no effect in mice. Expression of the neurotoxin by the virus causes a reduction in the time required to kill the host insect.     

Linkage of Mls genes to endogenous mammary tumour viruses of inbred mice.

T cells that recognize self antigen are clonally deleted in the thymus--a maturation process that occurs in the context of histocompatibility molecules and the T-cell receptor. The minor lymphocyte stimulation antigens (Mls) effect these deletions through interactions with the V beta portion of the T-cell receptor, thus mimicking bacterial 'superantigens'. Intrigued by the fact that each known Mls gene maps to the same chromosomal region as an endogenous mouse mammary tumour virus (Mtv), we reevaluated the linkage relationships between the two gene families. Here we report perfect concordance in inbred and recombinant inbred mice between the presence of four Mtv proviruses with the expression of Mls gene products. These data suggest a general model in which mammary tumour virus gene products themselves are the ligands that shape a considerable portion of the immunological repertoire of common laboratory mice.     

Secretion and mechanism of action of the hole-forming toxin aerolysin

Aeromonas hydrophila exports aerolysin as a protoxin which is activated by proteolysis after release. Aerolysin binds to the eucaryotic cell receptor glycophorin and oligomerizes, forming holes in the membrane. Important regions of the molecule have been identified by site-directed mutagenesis, and channel formation has been studied in planar lipid bilayers.     

Electromyographic responses elicited by cutaneous and mixed nerve stimulation in human tibialis anterior muscle

The rectified and averaged myoelectrical responses of the anterior tibial muscle to stimulation of the posterior tibial, peroneal and sural nerves at the ankle were recorded during a weak isometric contraction in man. The stimulation of the posterior tibial nerve elicited two excitatory phases (short and long latency excitations) at 40 ms and 78 ms latencies, respectively, separated by a phase of reduced activity. With peroneal and sural nerve stimulation such triphasic responses were less consistent; only a monophasic inhibitory response occurred in some recordings. These results indicate that well-identifiable responses with distinct latencies can be obtained in human leg muscle with cutaneous and mixed nerve stimulation distal to the muscle.     

A study on the pharmacokinetics in mouse of adenine-9-beta-D-arabinofuranoside 5-monophosphate conjugated with lactosaminated albumin

In plasma of mice injected with adenine-9-beta-D-arabinofuranoside monophosphate (ara-AMP) coupled to human lactosaminated serum albumin (L-HSA) some of the ara-AMP molecules are enzymatically released, whereas others remain linked to L-HSA. Evidence has been obtained that ara-AMP is not deaminated when it is conjugated to L-HSA, in contrast to the free drug which is rapidly metabolized to its hypoxanthine derivative.     

Presence of specific binding sites for [3H]sarcophytol-A in cultured human skin fibroblasts

The presence of specific binding sites for [3H]sarcophytol-A in human skin fibroblasts was examined using biochemical and morphological methods. The displacement studies clearly revealed that high (KD = 31.0 nM) and low (KD = 6.05 microM) affinity sites were present in the intact cells. Moreover, autoradiographic studies using light microscopy revealed that the specific binding sites may exist in both the cytoplasm and the nuclei.