Myoadenylate deaminase (adenosine monophosphate deaminase--AMPDA) was recently shown to be deficient in a group of patients by use of a histochemical and biochemical method based on the elaboration of ammonia by this enzyme as it deaminates 5' AMP. We have confirmed the utility of this histochemical method and the existence of persons deficient in AMPDA through the use of an unrelated assay technique. The lack of enzyme activity is not associated with any inhibitory activity in the muscles of patients with this disorder. The clinical diversity of these patients suggests that this lack may represent a normal variant or a subclinical state rather than an actual disease. The occurrence of AMPDA deficiency in both sexes points to possible autosomal inheritance.

AMP Deaminase↗

PubMedDate not supplied

The determination of biogenic amines in four strains of the fruit fly Drosophila melanogaster.

A range of biogenic amines were measured in the heads from four strains of Drosophila melanogaster. Quantitation was carried out using gas chromatography-negative ion chemical ionization mass spectrometry (GC-NICIMS) with stable isotope dilution. The principal amines detected in the heads were dopamine, noradrenaline and 5 HT with small amounts of p- and m-tyramine; p-octopamine could not be detected in samples of 25 heads with a limit of detection of 10 pg per sample. In addition to conventional neurotransmitters or putative neurotransmitters the amines 5- and 6-hydroxydopamine were detected in the heads in substantial amounts.

Animals↗

PubMedDate not supplied

Basic studies on heterobifunctional biotin-PEG conjugates with a 3-(4-pyridyldithio)propionyl marker on the second terminus.

Heterobifunctional poly(ethylene glycol) (PEG) derivatives with a biotin terminus have been synthesized and characterized with respect to avidin binding. Unambiguous measurement of biotinyl and pyridyldithiopropionyl end groups was established by selecting suitable assays and introducing necessary modifications. Functional studies on the binding of biotin-PEG conjugates to avidin tetramers revealed much similarity to known biotin-spacer-peptide conjugates with 7-27 atom spacers: dissociation kinetics of the initially formed 4:1 complexes were multiexponential, the complex with 2 ligands per avidin dissociating rather slowly with half-times of approximately 2 days at 25 degrees C. The observed stability of 3:1 and 2:1 complexes with avidin is particularly significant since it allows exploitation of the additional advantages of PEG spacers, i.e. reduced steric strain in biotin-avidin-biotin bridges, reduced nonspecific adsorption of biotinylated probes and markers, and, especially, uncomparable fluorescence intensities of biotin-PEG-fluorophore conjugates as is demonstrated in the accompanying study (second of three papers in this issue).

Avidin↗

PubMedDate not supplied

Biotin-fluorophore conjugates with poly(ethylene glycol) spacers retain intense fluorescence after binding to avidin and streptavidin.

Conventional biotin-fluorophore conjugates with approximately 14 atom spacers lose most of their fluorescence when binding to avidin or streptavidin, as is demonstrated in the present study. This explains the unusual fact that only biotinylated marker enzymes, but not fluorescent biotins, are regularly used in bioanalytic assays. Novel biotin-spacer-fluorophore conjugates are presented that retain intense fluorescence when binding to avidin or streptavidin. Preservation of fluorescence depends upon the use of poly(ethylene glycol) (PEG) spacers, which are shown not to interfere with biotin function. The observed absence of nonspecific interactions may also be attributed to the PEG chain. These novel fluorescent biotins are expected to be excellent new tools in fluorescence microscopy and related techniques.

Avidin↗

PubMedDate not supplied

Biotin-pyrene conjugates with poly(ethylene glycol) spacers are convenient fluorescent probes for avidin and streptavidin.

Conventional biotin-fluorophore conjugates with approximately 14 atom spacers are strongly quenched when bound to avidin or streptavidin, whereas fluorescence becomes insensitive to receptor binding if typical fluorophores are linked to biotin via poly(ethylene glycol) (PEG) chains (Gruber et al., see the second of three papers in this issue). In the present study the antagonism between PEG-PEG repulsion and fluorophore interaction was examined more closely, using biotin-PEG-pyrene conjugates as model compounds. The antagonistic tendencies between hydrophilic PEG chains and hydrophobic pyrene labels were about balanced in the PEG1900 derivative since quenching was approximately 50% in 4:1 complexes with avidin or streptavidin. In contrast, strong quenching and concomitant excimer fluorescence was seen with the biotin-PEG800-pyrene conjugate, providing for a new fluorescence assay to accurately measure avidin and streptavidin concentrations at > or = 40 and > or = 10 nM, respectively. Association/ dissociation kinetics were analyzed from pyrene fluorescence changes, and dissociation constants were deduced. About 3-fold affinities were observed for streptavidin as compared to avidin, and little influence of PEG chain length was seen. All affinities were increased by a factor of approximately 3 when biotin-PEG-tetramethylrhodamine conjugates were used. The observed effect of fluorophore variation upon biotin binding is unexpectedly small; thus, the kinetic/thermodynamic data appear to be representative for biotin-PEG conjugates in general.

Avidin↗

PubMedDate not supplied

Intuition: the new-era trump card.

Welcome to the new era--one largely defined by rapid change and unprecedented access to information. If you are worried about keeping up, you are not alone. But take heart, many corporations are rapidly adapting to this chaotic new environment by using one of the oldest, most powerful tools in our history--intuition.

Administrative Personnel↗

PubMedDate not supplied

Metamorphosis of the mushroom bodies; large-scale rearrangements of the neural substrates for associative learning and memory in Drosophila.

Paired brain centers known as mushroom bodies are key features of the circuitry for insect associative learning, especially when evoked by olfactory cues. Mushroom bodies have an embryonic origin, and unlike most other brain structures they exhibit developmental continuity, being prominent components of both the larval and the adult CNS. Here, we use cell-type-specific markers, provided by the P[GAL4] enhancer trap system, to follow specific subsets of mushroom body intrinsic and extrinsic neurons from the larval to the adult stage. We find marked structural differences between the larval and adult mushroom bodies, arising as the consequence of large-scale reorganization during metamorphosis. Extensive, though incomplete, degradation of the larval structure is followed by establishment of adult specific alpha and beta lobes. Kenyon cells of embryonic origin, by contrast, were found to project selectively to the adult gamma lobe. We propose that the gamma lobe stores information of relevance to both developmental stages, whereas the alpha and beta lobes have uniquely adult roles.

Animals↗

PubMedDate not supplied