Effect of X-537A on the phosphorylated protein in sarcoplasmic reticulum vesicles

Summary The effect of the antibiotic X-537A on the phosphorylated ATPase (EP) was investigated. The results show that X-537A depresses the level of EP which is dependent on the Ca²⁺ gradient, while the Ca²⁺-independent EP is not affected. Acknowledgments. This work was supported by grants from the Instituto de Alta Cultura of the Portuguese Ministry of Education (No. CB/2) and the Calouste Gulbenkian Foundation.     

新疆少数民族中学"体育与健康"课程教学现状的调查与研究

本对新疆南、北疆、东疆地区和乌鲁木齐市的101所民族中学进行实地的调查研究，通过对各民族中学体育教学中大纲、教材、场地器材、汉语授课、男女生分班情况、教师培训、教学计划以及对课程改革的认识等方面的分析．进一步了解新疆各地区民族中学学校体育状况，特别是“体育与健康”课程实施后，各地区民族中学学校体育教学现状以及所面临的问题，旨在加快新疆少数民族中学的体育教学改革和《体育与健康》课程教学研究。为新疆教育主管部门制定实施“体育与健康”课程教学提供决策依据。     

A structural change in the kinesin motor protein that drives motility

Kinesin motors power many motile processes by converting ATP energy into unidirectional motion along microtubules. The force-generating and enzymatic properties of conventional kinesin have been extensively studied; however, the structural basis of movement is unknown. Here we have detected and visualized a large conformational change of an approximately 15-amino-acid region (the neck linker) in kinesin using electron paramagnetic resonance, fluorescence resonance energy transfer, pre-steady state kinetics and cryo-electron microscopy. This region becomes immobilized and extended towards the microtubule 'plus' end when kinesin binds microtubules and ATP, and reverts to a more mobile conformation when gamma-phosphate is released after nucleotide hydrolysis. This conformational change explains both the direction of kinesin motion and processive movement by the kinesin dimer.     

Urocortin-deficient mice show hearing impairment and increased anxiety-like behavior

Urocortin is a member of the corticotropin-releasing hormone peptide family and is found in many discrete brain regions. The distinct expression pattern of urocortin suggests that it influences such behaviors as feeding, anxiety and auditory processing. To better define the physiological roles of urocortin, we have generated mice carrying a null mutation of the urocortin gene. Urocortin-deficient mice have normal basal feeding behavior and stress responses, but show heightened anxiety-like behaviors in the elevated plus maze and open-field tests. In addition, hearing is impaired in the mutant mice at the level of the inner ear, suggesting that urocortin is involved in the normal development of cochlear sensory-cell function. These results provide the first example of a function for any peptidergic system in hearing.     

Invasion of big sagebrush ( Artemisia tridentata ) by white fir ( Abies concolor ) on the southeastern slopes of the Warner Mountains, California

White fir ( Abies concolor ) appears to be invading vegetation dominated by big sagebrush ( Artemisia tridentata ) on the southeastern slopes of the Warner Mountains of extreme northeastern California. The time of initial tree establishment within the shrubs was determined by increment borings. Possible causes of the invasion involving specific climatic conditions, fire history, and grazing use of the area during years of the establishment were explored. Heavy grazing by domestic livestock, particularly sheep, appears responsible for altering the sagebrush - grass vegetation and allowing tree invasion.     

Inhibin beta in central neural pathways involved in the control of oxytocin secretion

Inhibin (I) a gonadal hormone glycoprotein which suppresses follicle-stimulating hormone (FSH) secretion from the anterior pituitary, is a heterodimer consisting of an alpha subunit and one of two distinct beta subunits. S1 nuclease analysis has revealed that RNAs encoding all three subunits (alpha, beta A and beta B) are expressed in rat brain. We report here on the localization, and a potential function, of inhibin beta in the rat brain. A cell group centred in the nucleus of the solitary tract (NTS), a major recipient of visceral sensory information, was stained immunohistochemically with antisera against synthetic fragments of I beta, but not I alpha. The distribution of I beta-stained fibres is consistent with known NTS projections, and includes a prominent projection to oxytocinergic aspects of the magnocellular neurosecretory system.     

Presence of calcium ions as a requisite for the in vitro stimulation of TSH-release by hypothalamic TRF

Résumé L'incubation in vitro de fragments d'hypophyse (rat) dans le liquide de Krebs-Ringer sans calcium (Ca⁺⁺) inhibe l'action du facteur hypothalamique TRF (TSH-releasing factor) qui normalement stimule la sécrétion de l'hormone thyréotrope (TSH). La ré-introduction de l'ion Ca⁺⁺ (2.54 mM) rétablit la réponse (sécrétion de TSH) au facteur TRF.

---

---

Supported by USPHS research grants Nos. AM 08290.04, HD 02577.01, training grant No. GM 956.04; also No. FR 00254 to Common Research Computer Facility, Texas Medical Center. We are pleased to acknowledge the excellent assistance of Mrs.Nancy Pace in the assays involved here.     

Importance of FSH-releasing protein and inhibin in erythrodifferentiation

Inhibin is a hypophysiotropic hormone which selectively suppresses the secretion of pituitary follicle-stimulating hormone. It has been isolated from gonadal fluids and characterized as a protein heterodimer consisting of an alpha subunit and one of two beta subunits (beta A or beta B). FSH-releasing protein (FRP), also named activin, is a dimer consisting of two inhibin beta-chains. A factor from conditioned medium of a leukaemia cell line has been isolated which can induce mouse Friend cells to become benzidine-positive, and which shares a similar N-terminal sequence with porcine FRP. In this report, we find that FRP and inhibin modulate both the induction of haemoglobin accumulation in a human erythroleukaemic cell line, K562, and the proliferation of erythroid progenitor cells in human bone marrow culture. These two proteins could constitute a novel humoral regulatory control of erythropoiesis which would involve two types of related protein dimers with functionally opposite effects.