Conversion of 4-aminobutyraldehyde to γ-aminobutyric acid in striatum treated with semicarbazide and kainic acid

4-Aminobutyraldehyde (ABAL) has been shown to cross the blood-brain barrier and to be converted rapidly to -aminobutyric acid (GABA) in various regions of the brain. In this paper, the formation of GABA from ABAL was studied with striatum that had suffered a lesion to GABA synthesis via glutamic acid decarboxylase (GAD). The GABA formation from ABAL was invariably observed in striatum in which GAD was severely inhibited by semicarbazide or kainic acid. Thus, this is another pathway for GABA formation.     

Analysis of powder and single crystal electron paramagnetic resonance spectra of deoxy myoglobins containing cobalt (II) proto-and mesoporphyrins IX at various microwave frequencies

Artificial myoglobins (Mbs) substituted for protoheme with Co(II) proto-and mesoporphyrins IX (proto-and meso-CoMbs, respectively) were prepared. The principal values and eigenvectors of g tensors and the hyperfine coupling tensors of the paramagnetic Co(II) centers of their deoxy forms have been determined by single crystal EPR spectroscopy at 77 K in order to elucidate orientation and electronic structure of the prosthetic group in myoglobin. The orientation of the porphyrin plane of deoxy meso-CoMb were found to be identical to that of deoxy proto-CoMb. However, the in-plane hyperfine coupling constants of deoxy meso-CoMb were more anisotropic and larger than those of deoxy proto-CoMb, suggesting an increase in the electron spin density on the Co(II) ion upon the exchange of protoporphyrin IX with mesoprophyrin IX. Powder EPR spectra of these CoMbs, which were measured at S- and L-band microwave frequencies, exhibited well resolved 59Co hyperfine splittings and can be clearly interpreted by the use of the EPR parameters obtained from single crystal EPR measurements.     

Fresh-water planarias and a marine planaria are relatively dissimilar in the 5S rRNA sequences.

The nucleotide sequences from fresh-water Dugesia japonica and marine Planocera reticulata have been determined. The similarity between these two species is only 69%. The Planocera sequence reveals nearly 80% similarity (72-81%) to the sequences of multicellular animals, while the Dugesia sequences are considerably different from them (66-73%).     

Some properties of salivary amylases of Adelphocoris suturalis (Miridae), Dolycoris baccarum (Pentatomidae), and several other heteropteran species

Some properties of salivary amylases of the adults of Adelphocoris suturalis Jakovlev and Dolycoris baccarum L. were studied in vitro and compared with those of several other heteropteran species. The reducing sugar produced by the action of the salivary amylase of D. baccarum increased in proportion to substrate concentration while the concentration was relatively low (below 0.67% in its final concentration). Its increase stopped at the concentrations from 0.67 to 2.0%, and then it increased again constantly but slowly. The optimum temperature for the action of the enzyme was found to be about 50° (in A. suturalis) and about 40° (in D. baccarum), and the optimal pH was 3.5–4.0 in A. suturalis and 6.0 in D. baccarum. The salivary amylase activity of D. baccarum was scarcely affected by NaCl, KNO₃, and other compounds, while the salivary amylase of A. suturalis was strongly activated by NaCl and moderately by KNO₃. It seems highly probable that taxonomically related heteropterous insects might well be grouped with respect to the degree of activation of the salivary amylase by Cl- or NO₃-.

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Zusammenfassung Einige Eigenschaften der Speichelamylase von Adelphocoris suturalis und Dolycoris baccarum wurden im Reagenzglas studiert und mit denen anderer Heteropterenarten verglichen. Die durch die Wirkung der Speichelamylase von D. baccarum produzierten Stärkehydrolysate vermehrten sich im Verhältnis zur Substratkonzentration bei einer verhältnismäßig niedrigen Konzentration (weniger als 0,67% in der Schlußkonzentration). Diese Vermehrung wurde bei einer Konzentration von etwa 0,67 bis 2,0 unterbrochen, um sich dann wieder stetig, aber langsamer fortzusetzen. Die optimale Temperatur für die Wirkung des Fermentes lag für A. suturalis bei etwa 50° und für D. baccarum bei etwa 40°. Die optimale Wasserstoff-Ionenkonzentration betrug für A. suturalis pH 3,5–4,0 und für D. baccarum pH 6,0. Die Aktivität der Speichelamylase von D. baccarum wurde durch NaCl, KNO₃ und andere Verbindungen kaum beeinflußt, während die Speichelamylase von A. suturalis durch NaCl stark und durch KNO₃ schwach aktiviert wurde. Es wird vermutet, daß, hinsichtlich des Aktivierungsgrades der Speichelamylase durch Cl- und NO₃-, systematisch nahe verwandte Heteropterenarten der gleichen Gruppe angehören.

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Contribution No. 28 from the Laboratory of Entomology, Obihiro Zootechnical University.     

Pituitary regulation of preovulatory estrogen secretion in the rat

The factors stimulating estrogen secretion in the preovulatory phase and an attempt to explain the mechanism of termination of estrogen secretion are discussed. Female Wistar rats, hypophysectomized at 1 p.m. in proestrus, were injected with rat pituitary extracts. Ovarian venous blood was collected and the estrogen activity of the plasma was measured. The estrogen secretion was minimized within 3 hours after hypophysectomy. The rat pituitary extract caused an 11-fold increase of estrogen concentration in the ovarian venous blood within 1 hour. Either LH or FSH alone was able to restore the estrogen secretion: LH took 1 hour to reach maximal response, FSH 2 hours. In the 1-hour test, the minimal effective dose for LH appeared to be less than .25 mcg per rat, for FSH, 2.5 mcg per rat. The total ability of the two preparations to produce estrogen appeared to be the same. 10 I.U. of prolactin slightly stimulated estrogen secretion, but 20 mU of ACTH was quite negative. These results demonstrate the pituitary gonadotropin dependency of estrogen secretion from the ovary having ripened follicles. It also showed that the ovary, after completion of ovulatory surge of LH, abolished its reactivity to the pituitary extract containing sufficient amount of substances in promoting estrogen secretion. Either LH or FSH was able to terminate estrogen secretion even at minute doses as small as 10 mcg. This shows that both FSH and LH provide a dual effect on ovarian estrogen secretion at the preovulatory stage, promotion and suppression. Promotion is an acute and direct action of hormones on steroidogenesis and suppression probably a delayed and indirect action of ovulation-inducing hormone, the release of which initiates the differentiation of estrogen-forming cells towards ovulation unfavorable to estrogen synthesis.