Changes in the free amino acid pattern of haemolymph of the common indian scorpionPalamnaeus bengalensis during moulting

Summary Haemolymph ofPalamnaeus bengalensis contains normally 12 and during moulting up to 15 free amino acids, being in maximal number at the end of ecdysis. Aminoacidaemia is most pronounced during the pharate stage. Tyrosine appeared for tanning of the cuticle. Taurine and methionine were not present.Acknowledgment. The author is thankful to Dr.S. C. Shrivastava for valuable guidance and State C.S.I.R. (U.P.) for funds.     

Influence of castration and testosterone replacement on hypothalamic tyrosine hydroxylase activity in the rat

Summary Hypothalamic tyrosine hydroxylase (TH) activity of castrate rats is modulated by testosterone propionate (TP) in vivo. Kinetic studies revealed that bothV _max andK _m were virtually unaltered for substrate tyrosine in the presence of an excess of DMPH₄ cofactor. TP replacement to castrate rats increased theK _m for added DMPH₄ cofactor, whileV _max decreased. These results suggest that TP decreases TH activity of castrate rats by inhibiting the enzymereduced pteridine cofactor complex.     

Influence of castration and testosterone replacement on hypothalamic tyrosine hydroxylase activity in the rat.

Hypothalamic tyrosine hydroxylase (TH) activity of castrate rats is modulated by testosterone propionate (TP) in vivo. Kinetic studies revealed that both Vmax and Km were virtually unaltered for substrate tyrosine in the presence of an excess of DMPH4 cofactor. TP replacement to castrate rats increased the Km for added DMPH4 cofactor, while Vmax decreased. These results suggest that TP decreases TH activity of castrate rats by inhibiting the enzyme-reduced pteridine cofactor complex.     

Hypothalamic tyrosine hydroxylase activity, plasma gonadotropin and prolactin levels after aminooxyacetic acid in ovariectomized rats

Plasma concentrations of gonadotropin, prolactin and hypothalamic tyrosine hydroxylase (TH) activity were measured in ovariectomized rats treated with aminooxyacetic acid (AOAA), a drug which elevates brain GABA levels. Hypothalamic TH activity was significantly increased with a significant decrease in prolactin (Prl) release. Plasma levels of gonadotropins were not modified by AOAA. These results support an inhibitory action of GABA on Prl release possibly mediated through hypothalamic dopamine.     

A sensitive and inexpensive high-performance liquid chromatographic assay for tyrosine hydroxylase

We describe a highly sensitive assay method for tyrosine hydroxylase (TH) using high-performance liquid chromatography with amperometric determination. This assay method could be applicable to any tissues with low enzyme activity, such as rat cerebellum. We also describe the kinetic properties of TH in rat cerebral cortex.     

A sensitive and inexpensive high-performance liquid chromatographic assay for tyrosine hydroxylase

Summary We describe a highly sensitive assay method for tyrosine hydroxylase (TH) using high-performance liquid chromatography with amperometric determination. This assay method could be applicable to any tissues with low enzyme activity, such as rat cerebellum. We also describe the kinetic properties of TH in rat cerebral cortex.     

Hypothalamic tyrosine hydroxylase activity,plasma gonadotropin and prolactin levels after aminooxyacetic acid in ovariectomized rats

Summary Plasma concentrations of gonadotropin, prolactin and hypothalamic tyrosine hydroxylase (TH) activity were measured in ovariectomized rats treated with aminooxyacetic acid (AOAA), a drug which elevates brain GABA levels. Hypothalamic TH activity was significantly increased with a significant decrease in prolactin (Prl) release. Plasma levels of gonadotropins were not modified by AOAA. These results support an inhibitory action of GABA on Prl release possibly mediated through hypothalamic dopamine.Supported by grants from Indian Council of Medical Research (ICMR), New Delhi. RIA kits for the estimation of LH, FSH and Prl were kindly supplied by Dr A.F. Parlow, NIAMDD-NIH, Bethesda, Maryland, USA. GNB is a UGC research fellow.     

Temporal storage of kynurenine and 3-OH-kynurenine in the fat body of metamorphosingEphestia kühniella

Summary During the pharate pupal stage a massive accumulation of kynurenine and 3-OH-kynurenine is observed in the fat body ofEphestia kühniella. By injection it can be demonstrated that this organ is capable of sequestering at least 3-OH-kynurenine, the dominating tryptophan metabolite inEphestia. It is suggested that the fat body reduces a possibly harmfull excess of tryptophan metabolites at the beginning of metamorphosis. These sequestered metabolites provide a precursor depot for ommochrome synthesis in later development.     

Cyclic AMP during development and ageing of the insectCeratitis capitata

Summary Cyclic AMP was determined during the development of the dipteraCeratitis capitata. The concentration of the nucleotide reaches a peak at apolysis with a sharp decline in the pharate adult stage. A gradual increase takes place through the longevity of adult stage reaching a maximum plateau at the end of life.We are indebted to Prof.A. M. Municio for advice and encouragement and Mr.V. G. Corces for technical assistance.     

Biological activity of flucycloxuron,a novel benzoylphenylurea derivative,onTenebrio molitor: comparison with diflubenzuron and triflumuron

Flucycloxuron, a novel benzoylphenylurea (BPU) derivative, exhibited insecticidal activity when injected into newly ecdysed pupae ofTenebrio molitor. Mortality occurs because of defective adult ecdysis. Treatment caused a reduction in both cuticle thickness and incorporation of¹⁴C-labelled precursor into chitin, although it had no significant effect on the protein synthesis. The potencies of other BPU compounds as inhibitors of chitin biosynthesis have been examined and results showed that diflubenzuron was less effective than either flucycloxuron or triflumuron.     

Effets de la réserpine sur le développement d'Oedipoda coerulescens L. (Acridien,Orthoptère)

Summary Inhibitory effects of reserpine on ecdysis and chromatic adaptation inOedipoda appear to be linked with changes observed in both neural and neuro-endocrine regulating systems.     

Placing the activity rhythm in Araneus cornutus]

Araneus cornutus spiderling activities recorded from hatching to scattering show a particular distribution of the general motor activity over a 24-hour period. More motor activity is first observed during the light sequence, while at a nocturnal activity distribution appears after the 2nd nymphean ecdysis.     

Xanthindehydrogenase in Organen vonDrosophila melanogaster

Summary High activity of the enzyme, xanthindehydrogenase, was detected in larval fat-body of wild typeDrosophila melanogaster. The Malpighian tubules of both larvae and adults exhibit activity, too, though rather little. No activity was detected in larval testes, while probably insignificant traces were found in adult testes. The results are discussed with regard to non-autonomy of mutants deficient in the enzyme.

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Ausgeführt mit Unterstützung des Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung.     

Correlation between serum dopamine-β-hydroxylase activity and dopamine-β-hydroxylase and tyrosine hydroxylase activities in central and peripheral adrenergic neurons and adrenal glands

Summary Serum dopamine--hydroxylase activity in spontaneously hypertensive rats and Wistar-Kyoto rats had a positive correlation with dopamine--hydroxylase and tyrosine hydroxylase activities in mesenteric vessels, vas deferens, and adrenal glands at 14–16 weeks of age, a negative correlation with dopamine--hydroxylase activity in locus coeruleus at 3 weeks and 14–16 weeks of age, and a positive correlation with tyrosine hydroxylase activity only at 3 weeks of age, but not at 14–16 weeks of age.     

Identification of tyrosine-phosphorylated proteins of the mitochondrial oxidative phosphorylation machinery

The role of some serine/threonine kinases in the regulation of mitochondrial physiology is now well established, but little is known about mitochondrial tyrosine kinases. We showed that tyrosine phosphorylation of rat brain mitochondrial proteins was increased by in vitro addition of ATP and H₂O₂, and also during in situ ATP production at state 3, and maximal reactive oxygen species production. The Src kinase inhibitor PP2 decreased tyrosine phosphorylation and respiratory rates at state 3. We found that the 39-kDa subunit of complex I was tyrosine phosphorylated, and we identified putative tyrosine-phosphorylated subunits for the other complexes. We also have strong evidence that the FoF1-ATP synthase α chain is probably tyrosine-phosphorylated, but demonstrated that the β chain is not. The tyrosine phosphatase PTP 1B was found in brain but not in muscle, heart or liver mitochondria. Our results suggest that tyrosine kinases and phosphatases are involved in the regulation of oxidative phosphorylation.Received 7 January 2005; received after revision 19 April 2005; accepted 22 April 2005     

Tyrosine phosphorylation of cytoplasmic proteins in proliferating, differentiating, apoptotic HL-60 cells and blood neutrophils

Two-dimensional electrophoretic analysis was used to assess quantitative and qualitative changes in the expression and tyrosine phosphorylation of cytoplasmic proteins of proliferating, differentiating HL-60 cells and mature human blood neutrophils. The total tyrosine phosphorylation level of cytoplasmic proteins appeared approximately constant during the pre-commitment period, i.e., 6-24 h after induction of differentiation by 700 nM all-trans retinoic acid. At the time of granulocytic phenotype formation (48-120 h), the total level of tyrosine phosphorylation of cytoplasmic proteins increased significantly. Tyrosine phosphorylation of cytoplasmic proteins in matured blood neutrophils was significantly lower than that of cytoplasmic proteins of HL-60 cells differentiated for 96 h with retinoic acid. Immunoblotting with anti-Erk2 and anti-phosphotyrosine monoclonal IgG2bk antibodies showed that Erk2 was expressed and tyrosine-phosphorylated at different levels in HL-60 proliferating cells and in cells at all stages of differentiation. Our data showed that tyrosine phosphorylation of cytoplasmic proteins in differentiating HL-60 cells changes dramatically during the period of phenotype formation and is accompanied by increasing activity of Erk2. An increasing number of apoptotic cells appeared in the differentiating HL-60 cell population during the granulocyte maturation stage (48-120 h of differentiation). The appearance at this time of differentiation of a new set of tyrosine-phosphorylated cytoplasmic proteins (also distinctive for apoptotic HL-60 cells mediated by etoposide) together with an increasing number of apoptotic cells in the differentiating population strongly suggests that these proteins are associated with the apoptotic process.     

Increase in the hypothalamic tyrosine hydroxylase activity after lesion of the catecholaminergic neurons of the rat pontine tegmentum]

Hypothalamic tyrosine hydroxylase activity is increased 6 and 18 h after bilateral lesioning of the Locus Coerulues, in the Rat. An adrenocortical hypertrophy was observed previously, under the same experimental conditions. The neurochemical and neuroendocrinological implications of theses results are discussed.     

Methemoglobin in hypoxic rats

Methemoglobin levels have been found to vary with altitude and to shift the hemoglobin-oxygen dissociation curve. In this study, hematocrits and methemoglobin levels were monitored in rats exposed to hypoxia (420 torr absolute) for various intervals. Hematocrits gradually increased throughout the period of hypoxia, while methemoglobin levels rose by 12 h, peaked at 24 h and returned to control level by day 6. These data, in the context of other work, suggest that increased methemoglobin is important in acclimation to hypoxia.     

Effects of injections of ecdysterone on the molt and regeneration in the crab Carcinus maenas (L.)]

Two successives injections of 10 microng/g of ecdysterone induce precocious ecdysis in 66% of Crabs. This induction of precocious ecdysis is always accompanied by an inhibiting effect on regeneration: tiny abnormal regenerates or none are obtained. A majority of recipients of ecdysterone underwent successful ecdysis. Experimental results are discussed; a morphological and cytological study of ecdysterone effects on regeneration is announced.     

Invertase activity in the midgut ofSarcophaga ruficornis andMusca domestica (diptera: Insecta)

Summary The pH for the optimum activity of the midgut invertase was 5.5 in the adults ofS. ruficornis, 6.0 in its larvae and adults ofM. domestica and 6.5 in the larvae of the latter fly. The optimum temperature was 50°C. Enzyme activity was retarded by the addition of glucose and fructose.