The presence of gigartinine in a New Zealand Gracilaria species

Gigartinine, 5-(3-amidinoureido)-2-aminovaleric acid, serves as achemotaxonomic marker to distinguish two species of Gracilaria withvery similar morphologies. Gigartinine was identified by ¹³C-NMRspectroscopy and amino acid analysis of a cold-water extract from Gracilaria sp. nov., collected from a sheltered harbour localityat Blockhouse Bay, Auckland, New Zealand. Levels of this amino acid,naturally ca. 5% by dry weight of seaweed, were able to be depleted andthen restored during a nitrogen pulsing experiment. In contrast, native andpulsed samples of Gracilaria chilensis from Point Arthur, Wellingtonshowed no extractable gigartinine. Although these two species are unableto be distinguished in the field by morphological characteristics, they canbe separated by the presence or absence of gigartinine.     

A radiation hybrid map of 18 growth factor, growth factor receptor, hormone receptor, or neurotransmitter receptor genes on the distal region of the long arm of chromosome 5.

The distal portion of the long arm of human chromosome 5 contains an impressive number of genes encoding growth factors, growth factor receptors, and hormone/neurotransmitter receptors. The order of and relative distance between 18 of these genes was determined by radiation hybrid mapping. There is only a single gap in a contiguous radiation map from 5q22-5q35. For this set of radiation hybrids, one map unit (centiray) corresponds to 20-50 kb of DNA. Close physical proximity for several pairs of loci was predicted by the map. Two sets of these were found to be contained in single YAC clones. The physical map produced by radiation hybrid mapping should prove useful in efforts to identify four disease genes that have been assigned to distal 5q by linkage studies.     

Interactions of Na+ with haemoglobin-organic phosphate complexes

Longitudinal and transverse relaxation times were measured in aqueous solutions containing haemoglobin and 2,3-bisphosphoglycerate and in dilute lysates of human erythrocytes. Analysis of the data in terms of calculated excess relaxation rates shows that Na+ interacts with the protein-organic phosphate complex. The comparable magnitude of the effect in the model system and in dilute lysate suggests that intracellular Na+ binds to the haemoglobin-bisphosphate complex. Results obtained with adenosine triphosphate and D-glucose indicate that there is also interaction between Na+ and haemoglobin complexes of these molecules.     

Antinociceptive action of intrathecal neurotensin in mice

Neurotensin has been demonstrated to be analgesic in rodents. This study used intrathecal injection of neurotensin in unanesthetized mice to evaluate the effect of the peptide at the spinal level on unconditioned behavior. Intrathecal administration of neurotensin produced dose-related inhibition of locomotor activity and of the response elicited by subcutaneous hypertonic saline. The effects of the peptide in the tail flick assay were variable and it produced no inhibition of the behavioral response to intrathecal substance P. The results indicate that neurotensin antinociception at the spinal level does not result from locomotor impairment, may be somewhat selective for chemically induced pain, and may be mediated by a presynaptic action on primary afferent fibers.