Control of l-amino acid oxidase in Neurospora crassa by different regulatory circuits

l-Amino acid oxidase is synthesized in Neurospora crassa in response to three different physiological stimuli: (i) starvation in phosphate buffer, (ii) mating, and (iii) nitrogen derepression in the presence of amino acids. During starvation in phosphate buffer, or after mating, l-amino acid oxidase synthesis occurred in parallel with that of tyrosinase. Exogenous sulfate repressed the formation of the two enzymes in starved cultures, but not in mated cultures. Sulfate repression was relieved by protein synthesis inhibitors, suggesting that the effect of sulfate required the synthesis of a metabolically unstable protein repressor. With amino acids as the sole nitrogen source only l-amino acid oxidase was produced. Under these conditions enzyme synthesis was repressed by ammonium and was insensitive to sulfate. Biochemical evidence suggested that the l-amino acid oxidase formed under the three different conditions was the same protein. Therefore, the expression of l-amino acid oxidase appeared to be under the control of least two regulatory circuits. One, also controlling tyrosinase, seems to respond to developmental signals related to sexual morphogenesis. The other, controlling other enzymes of the nitrogen catabolic system, is used by the organism to obtain nitrogen from alternative sources such as proteins and amino acids.     

Subcellular localization and glycoprotein nature of the invertase from the fission yeast Schizosaccharomyces pombe

The subcellular localization of the enzyme invertase in Schizosaccharomyces pombe cells, both repressed and derepressed for synthesis of the enzyme, was studied. Most of the invertase was found to be located outside the plasma membrane and only a small percentage was found to be associated to membranes. A substantial portion of the external enzyme remained firmly bound to cell-wall material.All of the invertase recovered in soluble form from cellular extracts reacted with concanavalin A and with the lectin from Bandeiraea simplicifolia seeds, indicating the presence in the enzyme of a carbohydrate moiety which probably contains terminal mannosyl (or structurally related) and galactosyl residues.The possibility of the presence of two different forms of invertase in S. pombe was considered. An intracellular, soluble form of invertase, devoid of carbohydrate, similar to the small invertase of the budding yeast Saccharomyces cerevisiae, was not found in S. pombe. However, the Michaelis constant for sucrose of the enzyme present in repressed cells was smaller than that of the invertase synthesized under derepressing conditions, although this difference could also be the result of a different pattern of glycosylation of the invertase synthesized under different growth conditions.     

Gibberella fujikuroi mutants obtained with UV radiation and N-methyl-N'-nitro-N-nitrosoguanidine

N-methyl-N'-nitro-N-nitrosoguanidine (nitrosoguanidine) and to a lesser extent UV radiation are very mutagenic for Gibberella microconidia. The recommended nitrosoguanidine doses lead to much higher frequencies of mutants than are found in other microorganisms. The frequency of mutants among the survivors increases linearly with the nitrosoguanidine dose (molar concentration X time); the absolute number of viable mutants in a given population reaches a maximum for a dose of ca. 0.7 M X s. The microconidia are uninucleate. The onset of germination brings about increased lethality of nitrosoguanidine, but it does not modify the action of UV radiation. Mycelia are more resistant than spores to both agents. Visible illumination effectively prevents lethality when given immediately after UV radiation. Auxotrophs and color mutants are very easily obtained. Pink adenine auxotrophs and several classes of color mutants are affected in the biosynthesis of the carotenoid pigment, neurosporaxanthin.     

Characterization of Neurospora crassa cyclic AMP phosphodiesterase activated by calmodulin.

Activation of cyclic AMP phosphodiesterase I by brain or Neurospora calmodulin was studied. The stimulation required micromolar concentrations of Ca2+, and it was observed at cyclic AMP concentrations between 0.1 and 500 microM. Activation was blocked by EDTA and some neuroleptic drugs such as chlorpromazine and fluphenazine. These drugs inhibit the elongation of N. crassa wild-type aerial hyphae. These results reinforce the evidence towards the recognition of Ca2+-calmodulin as one of the systems controlling cyclic nucleotide concentrations in Neurospora.     

Ka'apor ritual hunting

Several investigators cite population control, frequent settlement relocation, trekking, expansion of diet breadth, and food taboos as strategic responses to game depletion by indigenous populations living in interfluvial zones of lowland South America. The Ka'apor Indians of the interfluvial forest of northern Maranhão, Brazil, employ other means of optimizing hunting efficiency, partly based on ritual. Menstruating women, pubescent girls, and parents of newborns can consume meat only of the tortoise (Gochelone denticulata), the first prey species to be hunted out of an area. Tortoise capture requires, on average, one full day of hunting. This means that the full potential of hunting pressure does not materialize near the settlement. Meat productivity is unusually high even near old settlements. I argue that ritual tortoise hunting helps to regulate environmental utilization, to maintain a sustained yield of meat protein, and to expand the catchment area gradually.     

Evidence for the participation of disulfide and sulfhydril groups in the specific binding of [3H]prazosin in cerebral cortex

The tritiated ₁ antagonist prazosin [³H]PRZ binds specifically and with high affinity to postsynaptic adrenoceptors in membrane preparations from cerebral cortex. Since adrenoceptors are of protein nature, it was of interest of investigate the possible role of disulfide (—SS—) and sulfhydril (—SH) groups in the binding of [³H]PRZ. Pretreatment of the membranes with the disulfide and sulfhydryl reactivesdl0Dithiothreitol,l-Dithiothreitol, Dithioerythritol or 5,5-Dithiobis-(2-nitrobenzoic acid) (DTNB), alone or in combination with the alkylating agent N-Methylmaleimide (NMM), decreased specific [³HPRZ binding, with minor changes in the non-specific counts. Saturation experiments revealed that all these reagents reduced the affinity of the binding site for [³H]PRZ, as judged by theK _d 25°C, but only the alkylating agent NMM and the oxydizing reagent DTNB produced in addition to the increase inK _d, a decrease of the maximum binding capacity (B _max). The present results provide evidence for a participation of—SS—and/or—SH groups in the recognition site of the ₁-adrenoceptor of cerebral cortex.     

Molecular cloning of cDNA coding for human preprourokinase

A cDNA library was constructed in pBR322 from 18S to 20S mRNA that was extracted from human kidney cells, fractionated on oligo(dT)-cellulose column and sucrose-density gradient, and confirmed for urokinase production in Xenopus laevis oocytes. The Escherichia coli RR1 transformants were hybridized to synthetic oligonucleotide probe prepared according to the known amino acid sequence, Glu 73 to Glu 77 of human urinary urokinase chain B. The entire cloned cDNA covers a 2250-bp region, wherein the 1293-bp sequence codes for preprourokinase consisting of 431 amino acids, with the first 20 residues being a signal peptide. The 5'-untranslated region is at least 80 bp long and the 3'-untranslated region is longer than 850 bp.     

Biofeedback control of migraine headaches: A comparison of two approaches

In order to assess the relative effectiveness of finger warming and temporal blood volume pulse reduction biofeedback in the treatment of migraine, 22 female migraine patients were assigned to one of three experimental conditions: temporal artery constriction feedback, finger temperature feedback, or waiting list. Biofeedback training consisted of 12 sessions over a 6-week period. All patients completed 5 weeks of daily self-monitoring of headache activity (frequency, duration, and intensity) and medication before and after treatment. Treatment credibility was assessed at the end of Sessions 1, 6, and 12. Results showed that temporal constriction and finger temperature biofeedback were equally effective in controlling migraine headaches and produced greater benefits than the waiting list condition. Power analyses indicated that very large sample sizes would have been required to detect any significant differences between the two treatment groups. No significant relationships were found between levels of therapeutic gains and levels of thermal or blood volume pulse self-regulation skills. Likewise, treatment outcome was not found to be related to treatment credibility. Further analyses revealed that changes in headache activity and medication were associated with changes in vasomotor variability. Because blood volume pulse variability was not significantly affected by biofeedback training, questions about its role in the therapeutic mechanism are raised.This research was supported in part by grants from the Quebec Ministry of Education and the Quebec Ministery of Social Affairs to the first author, and an award from the Medical Research Council of Canada to the second author. The authors are indebted to Drs. Frank Andrasik, Howard Barbaree, Edward Blanchard, Martin Ford, and Patrick McGrath, as well as to two anonymous reviewers, for their helpful comments on an earlier draft of this paper.     

Floristic groups and plant communities of southeastern Santa Fe,Argentina

This paper is a survey of the vegetation of the southeastern departments in the Province of Santa Fe (Argentina). The vegetation was analyzed following Braun-Blanquet's approach modified by Mueller-Dombois & Ellenberg (1974). The most relevant species of the region were placed in 25 groups according to their requirements or general behaviour. Most of the communities are herbaceous, and apart from the woody and some other miscellaneous ones they were grouped into three ecologically and floristically defined sets. The first set, the Stipa grasslands and related communities, which are characterized by the more or less abundant presence of Stipa hyalina, Stipa neesiana and Stipa papposa, comprises five different communities. The second, the halophilous communities, comprises five communities, the two Spartina ssp. grasslands, the halophilous prairies of Distichlis spicata, the short sedge Scirpus americanus communities and the ‘pela-dales’. The third, the hygrophilous communities, comprises nine communities which are not so well defined as the ones in the other sets. Besides, two further communities have been included, the Paspalum quadrifarium and the Melica macra tall grasslands.