Exotic meson decay to omegapi0pi-.

A partial-wave analysis of the mesons from the reaction pi(-)p --> pi(+)pi(-)pi(-)pi(0)pi(0)p has been performed. The data show b(1)pi decay of the spin-exotic states pi(1)(1600) and pi(1)(2000). Three isovector 2(-+) states were seen in the omegarho(-) decay channel. In addition to the well known pi(2)(1670), signals were also observed for pi(2)(1880) and pi(2)(1970).

Observation of exotic meson production in the reaction pi- p --> eta'pi- p at 18 GeV/c.

An amplitude analysis of an exclusive sample of 5765 events from the reaction pi- p-->eta'pi- p at 18 GeV/c is described. The eta'pi- production is dominated by natural parity exchange and by three partial waves: those with J(PC) = 1(-+), 2(++), and 4(++). A mass-dependent analysis of the partial-wave amplitudes indicates the production of the a2(1320) meson as well as the a4(2040) meson, observed for the first time decaying to eta'pi-. The dominant, exotic (non- qq) 1(-+) partial wave is shown to be resonant with a mass of 1.597+/-0.010(+0.045)(-0.010) GeV/c2 and a width of 0.340+/-0.040+/-0.050 GeV/c2. This exotic state, the pi1(1600), is produced with a t dependence which is different from that of the a2(1320) meson, indicating differences between the production mechanisms for the two states.

The use of flash photolysis for a high-resolution temporal and spatial analysis of bacterial chemotactic behaviour: CheZ is not always necessary for chemotaxis.

The purpose of this work was to develop a high-resolution analysis of behaviour as an assay of the physiological consequences of mutations in the che genes and also to examine the role of CheZ in chemotaxis. Recent advances in flash photolysis have made it possible to expose cells to an unstable chemical gradient created by a square-wave increase in attractant concentration. The response of individual cells can be tracked in the order of milliseconds using real-time motion analysis. The tumble frequency of wild-type Escherichia coli exposed to photoreleased aspartate falls very quickly to smooth-swimming levels, and the swimming speed of these cells rises. As a consequence of these behavioural changes, there is an increase in the number of bacteria present in the centre of the flashed area, that is the bacteria's response to the transient gradient generated by flash photolysis was to swim into the centre of the flash area. This allowed the rapid quantitative measurement of chemotaxis. Deletion of various che genes resulted in predictable changes in chemotactic behaviour. cheZ null mutants are non-chemotactic when measured by classical techniques but demonstrate a definite chemotactic response to photoreleased attractant.

A motion tracking system for simultaneous recording of rapid locomotion and neural activity from an insect.

We have adapted techniques for studying the locomotion of tethered insects to analysis of rapid directional movements such as escape behavior. We describe here a computer-based motion tracking system that allows an animal to turn and run as rapidly as it does under free-ranging conditions, and that samples fast enough to accurately reconstruct the movements. Furthermore, we have designed chronic electrodes that allow for simultaneous extracellular recording of the activity of interneurons related to behavior. We used this system to record the escape response of tethered cockroaches, Periplaneta americana, and compared the data with those obtained from high-speed videographic analysis of the same animals under free-ranging conditions. In the motion tracking system, animals were normally responsive to sensory input, and expressed directional escape turning responses. This system allows details of an entire escape response (initial turn and subsequent running) to be quantified. These behavioral details can now be correlated with the discharge of key interneurons on a trial-by-trial basis.

Differential origin and control mechanisms in small and large bovine luteal cells.

Studies of the calcium requirement and the relationship of intracellular calcium to progesterone synthesis in highly purified preparations of bovine luteal cells reveal a remarkably close relationship between intracellular calcium levels and steroidogenesis. The differential responses of the two cell types, summarized in Table 2, are beginning to reveal how the two cell types may co-operate to produce both luteotrophic and luteolytic responses at different stages of the oestrous cycle and early pregnancy. The luteotrophic mechanisms in the small cells are fairly clear; in addition to the luteotrophic effects of LH and cAMP, activation of protein kinase C leads to increased progesterone synthesis. Accordingly, PGF-2 alpha and several other prostanoids are luteotrophic in these cells. PGF-2 alpha stimulates phospholipase C activity in the small cells but does not reduce LH-stimulated cAMP or progesterone accumulation (Davis et al., 1989). This acute stimulus of protein kinase C activation to progesterone production in bovine small luteal cells is rapidly desensitized, although its stimulus to prostanoid production continues for at least 24 h. Large cells respond to LH, but only at relatively high levels. In addition, we have no good evidence for a role for protein kinase C in the control of progesterone synthesis in the large bovine luteal cells from mid-cycle corpora lutea. Phorbol esters have no effect on steroidogenesis and it is not yet established that protein kinase C provides the same high affinity receptor for phorbol esters that is found in the small cells. Experiments with inhibitors of protein kinase C, such as staurosporine, in large cells have been inconclusive. Evidence for several species suggests that both cell types co-operate, in ways not yet fully understood, to bring about maximal progesterone production at mid-cycle. Some evidence suggests that they may also co-operate to bring about luteolysis. The concept that PGF-2 alpha initiates luteolysis by inhibiting LH stimulated progesterone production in the large cells must be revised in light of the relative insensitivity of these cells to LH and the fact that they probably constitutively express the cholesterol side-chain cleavage enzymes (P-450scc) that represent the rate-limiting step in progesterone production. Oonk et al. (1989) have reported that, once P-450scc mRNA is induced in rat granulosa cells by the LH surge, it is constitutively maintained by the luteinized cells in the absence of gonadotrophins and is no longer regulated by cAMP.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential effects of calcium on progesterone production in small and large bovine luteal cells.

We studied the effects of calcium (Ca2+) ions in progesterone (P) production by separated small and large luteal cells. Corpora lutea were collected from 31 heifers between days 10 and 12 of the estrous cycle. Purified small and large cells were obtained by unit gravity sedimentation and flow cytometry. P accumulation in cells plus media was determined after incubating 1 x 10(5) small and 5 x 10(3) large cells for 2 and 4 h respectively. Removal of Ca2+ from the medium did not influence basal P production in the small cells (P greater than 0.05). However, stimulation of P by luteinizing hormone (LH), prostaglandin E2 (PGE2), 8-bromo-cyclic 3',5' adenosine monophosphate (8-Br-cAMP) and prostaglandin F2 alpha (PGF2 alpha) was impaired (P less than 0.05) by low Ca2+ concentrations. LH and PGE2-stimulated cAMP production was not altered by low extracellular Ca2+ concentrations, and PGF2 alpha had no effect on cAMP. In contrast, basal as well as LH and forskolin-stimulated P production were attenuated (P less than 0.05) in Ca2(+)-deficient medium in the large cells. However, P production stimulated by 8-Br-cAMP was not altered in Ca2(+)-deficient medium. Steroidogenesis in large cells was also dependent on intracellular Ca2+, since 8-N, N-diethylamineocytyl-3,4,5-trimethoxybenzoate (TMB-8), an inhibitor of intracellular Ca2+ release and/or action, suppressed (P less than 0.05) basal, LH and 8-Br-cAMP stimulated P. In contrast, basal P in small cells was not altered by TMB-8; whereas LH-stimulated P was reduced 2-fold (P less than 0.05). The calcium ionophore, A23187, inhibited LH-stimulated P in small cells and both basal and agonist-stimulated P in large cells. These studies show that basal P production in small cells does not require Ca2+ ions, while hormone-stimulated P production in small cells and both basal and hormone-stimulated P in large cells do require Ca2+. The inhibitory effect of Ca2+ ion removal was exerted prior to the generation of cAMP in the large cells, but distal to cAMP generation in hormone-stimulated small cells. The calmodulin/protein kinase C antagonist, W-7, also inhibited both basal and hormone-stimulated P production in both small and large luteal cells, indicating that P production in luteal cells also involves Ca2(+)-calmodulin/protein kinase C-dependent mechanisms.

Phorbol ester receptors in bovine luteal cells: relationship to protein kinase C.

We investigated the binding kinetics of the tumor-promoting phorbol ester, phorbol-12,13-dibutyrate (PBt2) to dispersed total bovine luteal cells, purified small luteal cells, and purified luteal protein kinase C (PKC). Saturation analysis and competitive displacement techniques were used. Binding of [3H]PBt2 to total luteal cell preparations resulted in two distinct affinities. The high affinity component was characterized by a Kd of 4.5 +/- 1.5 nM. Analysis of [3H]PBt2 binding to total cells using competitive displacement demonstrated that the low affinity binding was specific and displaceable but dependent on concentrations of [3H]PBt2 far above the Kd for the high affinity binding. In contrast to the total cell preparations, only high affinity binding was observed in intact purified small luteal cells (Kd = 0.96 +/- 0.04 nM). Partial purification of luteal cytosolic PKC by DEAE-Sephadex chromatography resulted in co-elution of PKC enzyme activity and the [3H]PBt2 binding activity. Under conditions of saturating calcium (0.1 mM) and phosphatidylserine (PS) (100 micrograms/tube) concentrations, binding to the partially purified PKC preparation was found to be of a single high affinity and exhibited a Kd (1.3 +/- 0.2 nM) similar to the high affinity binding observed in intact cells. These results suggest that the primary phorbol ester receptor in luteal cells is PKC. However, a low affinity, high capacity [3H]PBt2 binding site also exists within the corpus luteum, either in the large cells or in the accessory cell fraction which consists mainly of endothelial cells.

Escape responses following elimination of the giant interneuron pathway in the cockroach, Periplaneta americana.

The entire set of giant interneurons (GIs) in the nerve cord of the cockroach, Periplaneta americana, was ablated using either electrolytic or surgical techniques. All animals with these lesions were capable of turning and running away from standard wind puffs. However, all animals responded much less frequently to standard wind stimuli following lesion, and the latency of their responses was significantly increased. These results are discussed in terms of a GI role in extremely short latency escape responses, and the idea that non-GI pathways, perhaps associated with head sensory structures, need to be considered in the normal control of escape in the cockroach.

Control of progesterone production in small and large bovine luteal cells separated by flow cytometry.

Corpora lutea were collected from Holstein heifers on Days 10 and 12 of the oestrous cycle and the cells were dispersed with collagenase. The dispersed cells were separated into preparations of highly purified (90-99%) small (less than 20 microns) and large (greater than 25 microns) luteal cells by unit gravity sedimentation and fluorescence-activated cell sorting. Net progesterone accumulation by 1 x 10(5) small cells and 1 x 10(3) large cells during 2 and 4 h incubations, respectively, were measured after additions of LH, PGF-2 alpha, and phorbol esters, alone and in combination. Progesterone synthesis was increased (P less than 0.05) by phorbol dibutyrate (PBt2) or PGF-2 alpha (P less than 0.05) in small, but not in large, luteal cells (10.1 +/- 3.0 and 18.1 +/- 5.0 ng/10(5) cells for 0 and 50 nM-PBt2, and 19.9 +/- 3.2 and 44.2 +/- 9.3 ng/10(5) cells for 0 and 1 microgram PGF-2 alpha/ml). The previously reported stimulatory effects of PKC activation and PGF-2 alpha addition to total dispersed cell preparations are therefore entirely attributable to the small, theca-derived cells. Small cells responded to low levels of LH (9.1 +/- 1.1, 69.0 +/- 5.4 and 154.7 +/- 41.4 ng/10(5) cells for 0, 1 and 5 ng LH/ml, respectively, P less than 0.05), while large cells responded only to high levels of LH (1635 +/- 318, 2662 +/- 459 and 3386 +/- 335 pg/10(3) cells for 0, 100 and 1000 ng LH/ml, respectively, P less than 0.05). PGF-2 alpha inhibited LH-, 8-Br-cAMP- and forskolin-stimulated progesterone synthesis in the large cells (3052 +/- 380, 3498 +/- 418, 3202 +/- 391 pg/10(3) cells for 1 microgram LH/ml, and 0.5 mM-8-Br-cAMP, and 1 microM-forskolin respectively and 1750 +/- 487, 2255 +/- 468, 2165 +/- 442 pg/10(3) cells for PGF-2 alpha + LH, PGF-2 alpha + 8-Br-cAMP and PGF-2 alpha + forskolin, respectively), indicating that the inhibitory effect of PGF-2 alpha on progesterone synthesis in large cells occurs at a site distal to cAMP generation. These results suggest that the large cells are the targets of the luteolytic effects of PGF-2 alpha, while the small cells are responsible for the previously reported luteotrophic effect of PGF-2 alpha in vitro.

Control of steroidogenesis in small and large bovine luteal cells.

Evidence was cited to show that: (1) prostacyclin (PGI2) plays a luteotrophic role in the bovine corpus luteum and that products of the lipoxygenase pathway of arachidonic acid metabolism, especially 5-hydroxyeicosatetraenoic acid play luteolytic roles; (2) oxytocin of luteal cell origin plays a role in development, and possibly in regression, of the bovine corpus luteum; and (3) luteal cells arise from two sources; the characteristic small luteal cells at all stages of the oestrous cycle and pregnancy are of theca cell origin; the large cells are of granulosa cell origin early in the cycle, but a population of theca-derived large cells appears later in the cycle. Results of in vitro studies with total dispersed cells and essentially pure preparations of large and small luteal cells indicate that: (1) the recently described Ca2+-polyphosphoinositol-protein kinase C second messenger system is involved in progesterone synthesis in the bovine corpus luteum; (2) activation of protein kinase C is stimulatory to progesterone synthesis in the small luteal cells; (3) activation of protein kinase C has no effect on progesterone synthesis in the large luteal cells; and (4) protein kinase C exerts its luteotrophic effect in total cell preparations, in part at least, by stimulating the production of prostacyclin. The protein kinase C system may cause down regulation of LH receptors in the large cells.

Hammond memorial lecture. New concepts of the control of corpus luteum function.

Five new concepts concerning the control of corpus luteum function in the cow have been developed in recent years. Prostacyclin (PGI-2) plays a luteotrophic role. Conversely, products of the lipoxygenase pathway of arachidonic acid metabolism, particularly 5 hydroxyeicosatetraenoic acid (5-HETE), play luteolytic roles. Luteal cells arise from two sources. The small luteal cells are all of theca cell origin; the large cells found early in the cycle (Days 2-6) are mainly of granulosa cell origin. However, a population of large cells found after Day 10 of the cycle are of theca cell origin. Oxytocin of luteal cell origin plays a role in development of the corpus luteum and possibly in its regression. The recently described Ca2+-polyphosphoinositol-protein kinase C second messenger system, as well as the LH-cAMP system, is involved in control of progesterone synthesis in the bovine corpus luteum. Progesterone synthesis in the small theca-derived luteal cells is primarily controlled by the cAMP system. However, elevated intracellular calcium diminishes cAMP-mediated progesterone synthesis in these cells. These findings modify our current concepts of the mechanisms of control of progesterone secretion by the corpus luteum and suggest several new lines of research.