Ultrastructural autoradiographic localization of serotonin in the pituitary of a teleost fish,Poecilia latipinna

Summary Light- and electron-microscopic autoradiographic studies of pituitaries of the molly Poecilia latipinna, after their incubation with tritiated serotonin, revealed the presence of labelled cells in the proximal pars distalis, together with cell processes or nerve fibres throughout all regions of the gland except the prolactin cell zone. The serotonincon-centrating cells and most of the fibres contained small dense-cored vesicles, but some labelled fibres contained larger granules similar in ultrastructure to those of vasotocinergic fibres.This work was supported by a SERC studentship to DJG and SERC grant GR/6379-06 to Professor J.N. Ball     

Calcium currents in embryonic and neonatal mammalian skeletal muscle

The whole-cell patch-clamp technique was used to study the properties of inward ionic currents found in primary cultures of rat and mouse skeletal myotubes and in freshly dissociated fibers of the flexor digitorum brevis muscle of rats. In each of these cell types, test depolarizations from the holding potential (-80 or -90 mV) elicited three distinct inward currents: a sodium current (INa) and two calcium currents. INa was the dominant inward current: under physiological conditions, the maximum inward INa was estimated to be at least 30-fold larger than either of the calcium currents. The two calcium currents have been termed Ifast and Islow, corresponding to their relative rates of activation. Ifast was activated by test depolarizations to around -40 mV and above, peaked in 10-20 ms, and decayed to baseline in 50-100 ms. Islow was activated by depolarizations to approximately 0 mV and above, peaked in 50-150 ms, and decayed little during a 200-ms test pulse. Ifast was inactivated by brief, moderate depolarizations; for a 1-s change in holding potential, half-inactivation occurred at -55 to -45 mV and complete inactivation occurred at -40 to -30 mV. Similar changes in holding potential had no effect on Islow. Islow was, however, inactivated by brief, strong depolarizations (e.g., 0 mV for 2 s) or maintained, moderate depolarizations (e.g., -40 mV for 60 s). Substitution of barium for calcium had little effect on the magnitude or time course of either Ifast or Islow. The same substitution shifted the activation curve for Islow approximately 10 mV in the hyperpolarizing direction without affecting the activation of Ifast. At low concentrations (50 microM), cadmium preferentially blocked Islow compared with Ifast, while at high concentrations (1 mM), it blocked both Ifast and Islow completely. The dihydropyridine calcium channel antagonist (+)-PN 200-110 (1 microM) caused a nearly complete block of Islow without affecting Ifast. At a holding potential of -80 mV, the half-maximal blocking concentration (K0.5) for the block of Islow by (+)-PN 200-110 was 182 nM. At depolarized holding potentials that inactivated Islow by 35-65%, K0.5 decreased to 5.5 nM.     

Control of endometrial oxytocin receptor and uterine response to oxytocin by progesterone and oestradiol in the ewe

The effects of administration of progesterone and oestradiol on ovine endometrial oxytocin receptor concentrations and plasma concentrations of 13,14-dihydro-15-keto prostaglandin F-2 alpha (PGFM) after oxytocin treatment were determined in ovariectomized ewes. Ewes received progestagen pre-treatment, progesterone and/or oestradiol in 11 different treatment schedules. Progestagen pre-treatment decreased oxytocin receptor concentrations in endometrium from ewes treated subsequently with either progesterone for 5 days or progesterone for 5 days plus oestradiol on Days 4 and 5 of progesterone treatment. Oestradiol increased endometrial oxytocin receptor concentrations when administered on Days 4 and 5 of 5 days progesterone treatment. Progestagen pre-treatment followed by progesterone treatment for 12 days caused a large increase in oxytocin receptors and no further increase occurred when ewes were given oestradiol on Days 11 and 12, or when progesterone was withdrawn on Days 11 and 12, or these two treatments were combined. Oxytocin administration caused an increase in plasma PGFM concentrations in ewes which did not receive progestagen pre-treatment, and subsequently received progesterone treatment for 5 days and oestradiol treatment on Days 4 and 5 of progesterone treatment. Similarly treated ewes which received progestagen pre-treatment did not respond to oxytocin. Oxytocin administration also increased plasma PGFM concentrations in ewes which received progestagen pre-treatment followed by progesterone treatment for 12 days, progesterone treatment for 12 days plus oestradiol on Day 11 and 12 of progesterone treatment, progesterone withdrawal on Day 11 and 12, or progesterone withdrawal and oestradiol treatment combined. The results indicate that (1) progesterone pre-treatment affects oxytocin receptor concentrations in the endometrium and uterine responsiveness to oxytocin and (2) progesterone treatment alone for 12 days after a treatment which mimics a previous luteal phase and oestrus is sufficient to induce oxytocin receptors and increase oxytocin-induced PGF release. These results emphasize the importance of progesterone and provide information which can be used to form an hypothesis for control of luteolysis and oestrous cycle length in the ewe.     

Meconium ileus equivalent in adults with cystic fibrosis of pancreas: a report of six cases.

Eleven episodes of "meconium ileus equivalent" have been seen in six adults with cystic fibrosis of the pancreas. Three patients were initially treated surgically; one died and the other two developed serious postoperative chest infections. Six episodes were successfully treated medically with acetylcysteine orally and by enema, nasogastric suction, and intravenous fluids. Operation should be avoided if possible, and maintenance treatment with acetylcysteine may be necessary to prevent relapse.     

The distribution of actin in cultured ovarian granulosa cells

Ovarian granulosa cells grown on glass coverslips were split by a "sandwich" technique. Using this technique we describe a complex filamentous network in the cytoplasm of cultured granulosa cells that was composed of a branching and anastomosing lattice of filaments 20-40 nm in diameter. Since filament identification is impossible on the basis of size, split cells were decorated with S-1 fragments of rabbit skeletal muscle myosin. It was readily apparent that the major constituent of the filamentous lattice was actin. Actin was organized in large bundles in which individual filaments were longitudinally aligned. Actin was also observed organized in a loose network throughout the remainder of the cytoplasm. Actin appeared to be intimately associated with organelle and plasma membranes. Coated pits were also a site of actin-filament interaction. Filament polarity was generally away from the membrane with which filaments were associated.     

Serum pancreatic lipase activity in cystic fibrosis.

Patients with cystic fibrosis have been found to have abnormal serum concentrations of immunoreactive trypsin and abnormal activities of pancreatic isoamylase. A study was undertaken to discover whether activity of pancreatic lipase is also altered in cystic fibrosis. Serum from 23 patients with cystic fibrosis was assayed for immunoreactive trypsin and pancreatic lipase. Median serum pancreatic lipase activity was significantly lower in patients with cystic fibrosis than in controls, as was immunoreactive trypsin concentration (p less than 0.0001). Some patients had supranormal lipase concentrations but these were not always associated with absence of malabsorption. Serum pancreatic lipase activity is considerably changed in cystic fibrosis.     

Breeding bird communities on Scottish farms

The Common Birds Census, begun by the British Trust for Ornithology has now been monitoring bird population levels on a nationwide basis since 1962. Separate indices were constructed for Scotland and the rest of Great Britain for 12 of the commonest species. Of the species examined blue tit (Parus caeruleus), wren (Troglodytes troglodytes), song thrush (Turdus philomelos), lapwing (Vanellus vanellus), chaffinch (Fringilla coelebs) and skylark (Alauda arvensis) have increased since 1963 and show very similar population trends to the rest of Great Britain. Whitethroat (Sylvia communis), willow warbler (Phylloscopus trochilus) and swallow (Hirundo rustica) have all declined nationally, the decline in the swallow appears to have begun earlier in Scotland. The blackbird (Turdus merula) and dunnock (Prunella modularis) showed similar upward trends until 1972 when the Scottish population started to decline; a much more noticeable decline in the Scottish robin (Erithacus rubecula) population began in 1966. The total density of territory-holding males has not increased but the biomass has and this is due to more, bigger birds but fewer passerines. The species diversity measured by the Shannon Wiener index (H.) has improved a little since 1971 and it is concluded that during the study period the farmland plots censused in Scotland have on average not shown evidence of deterioration as habitats for territory-holding birds.     

Molecular cloning of four novel murine ribonuclease genes: unusual expansion within the ribonuclease A gene family.

We have characterized four novel murine ribonuclease genes that, together with the murine eosinophil-associated ribonucleases 1 and 2, form a distinct and unusual cluster within the RNase A gene superfamily. Three of these genes (mR-3, mR-4, mR-5) include complete open reading frames, encoding ribonucleases with eight cysteines and appropriately spaced histidines (His11 and His124) and lysine (Lys35) that are characteristic of this enlarging protein family; the fourth sequence encodes a non-functional pseudogene (mR-6P). Although the amino acid sequence similarities among these murine ribonucleases varies from 60 to 94%, they form a unique cluster, as each sequence is found to be more closely related to another of this group than to either murine angiogenin or to murine pancreatic ribonuclease. Interestingly, the relationship between the six genes in this 'mR cluster' and the defined lineages of the RNase A gene family could not be determined by amino acid sequence homology, suggesting the possibility that there are one or more additional ribonuclease lineages that have yet to be defined. Although the nature of the evolutionary constraints promoting this unusual expansion and diversification remain unclear, the implications with respect to function are intriguing.     

Influence of peripheral targets on the expression of calcitonin gene-related peptide immunoreactivity in rat cranial motoneurones

Calcitonin gene-related peptide-like immunoreactivity (CGRP-ir) is displayed by motoneurons that innervate striated muscle but is absent from preganglionic parasympathetic motoneurons. One hypothesis to explain this is that CGRP gene expression in motoneurons is, in part, dependent on influences from the innervated organ. To test this hypothesis, we cross-anastomosed the right hypoglossal and cervical vagal nerves of rats so that the vagal motoneurons grew to innervate the musculature of the tongue. Following a recovery period of 17 to 52 weeks, the distribution of CGRP-ir in the dorsal motor vagal nucleus was determined in both cross-anastomosed animals and self-anastomosed control animals. Successful reinnervation of the tongue musculature by vagal motoneurons was demonstrated by showing that electrical stimulation of the central vagus/peripheral hypoglossal nerve produced a twitch of the tongue muscles. Motoneurones of the dorsal motor vagal nucleus, which now innervated the tongue were found to express CGRP-ir, which was evident from the double labeling of neurons with both horseradish peroxidase and CGRP-ir. Motoneurones of the dorsal motor vagal nucleus contralateral to the cross-anastomosis remained CGRP negative. Similarly, motoneurons of the dorsal motor vagal nucleus in control animals where the vagus nerve was self-anastomosed remained CGRP negative, showing that an induction of CGRP expression is not a result of nerve section itself. We suggest that a signal from the striated muscle transported retrogradely via the motor axon regulates expression of CGRP-ir in motoneurons. © 1995 John Wiley & Sons, Inc.