摘要:

AbstractElectron microscopic observations suggest that venom from isolated nematocysts of the stinging tentacles of the Portuguese man‐of‐war, Physalia physalis, causes histamine release via a rapid, short‐duration exocytosis of granules and a slower, long‐duration lysis of mast cells. Fine structural changes in mast cells are concurrent with histamine release and are independent of the presence of leukocytes. Vesiculation of the plasma membrane and release of granules nearest the cell surface occur within 10 sec after exposure to 100 μg venom/105cells. Released granules and granules retained in plasma membrane inaginations are fibrous and less electron opaque than more centrally located granules. Complex channels to the external medium continue to form, and within 1 min, characteristics of both degranulation and cytolysis are well advanced. Mitochondria are swollen or disrupted. Microridges are absent. Intracellular granules are significantly fewer in venom‐treated mast cells, but are more widely separated than in controls. This suggests that degranulation occurs at early stages but is halted as cytolysi

ISSN:0022-104X    

DOI:10.1002/jez.1402310102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe effects of ion substitutions on the Cl−secretion rate and tissue conductance of isolated short‐circuited opercular epithelia from sea‐water‐adaptedFundulus heteroclituswere investigated. Serosal Na+substitution had the same effect on the Cl−secretion rate that serosal Cl−substitution had on the active component of the Cl−efflux. This similarity indicated a 1:1 Na‐Cl requirement for active Cl−secretion across this epithelium, which supports the proposal of a coupled NaCl uptake mechanism at the serosal membrane of Cl−secretory epithelia. Mucosal Na+and Cl−substitutions appeared to inhibit completely the active Cl−secretory flux. The reductions in the tissue conductance with mucosal ion substitutions suggested that this effect can be attributed to a blocking of the apical membrane Cl−conductance. These mucosal ion effects suggested a possible direct regulatory influence of the external salinity on the Cl−secretion rate and tissue conductance, which provide alternative explanations for observations with

ISSN:0022-104X    

DOI:10.1002/jez.1402310103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractZymogen‐activating factors in the mouse were investigated by two‐dimensional electrophoresis. Mouse pancreatic zymogens—trypsinogen‐I group (Try G‐I group), trypsinogen‐II (Try G‐II), and chymotrypsinogen (Chy G)—were purified using DEAE‐cellulose column chromatography. Analysis by two‐dimensional electrophoresis, using the purified zymogens as substrates, revealed enterokinase isozymes and chymotrypsinogen‐activating factors in both the intestinal extract and luminal fluid. Mouse enterokinase was separated into at least two bands in the first‐dimensional gel, each able to activate both trypsinogens Try G‐I group and Try G‐II. Chymotrypsinogen‐activating factors were separated into several bands in the first‐dimensional gel. Some activating factors showed mobilities similar to those of mouse enterokinase isozymes. Moreover, other activating factors that can activate chymotrypsinogen were present only in the more anodal area of the first‐dimensional gel. These findings indicate that at least two enterokinases and several chymotrypsinogen‐activating factors play an important role in the proc

ISSN:0022-104X    

DOI:10.1002/jez.1402310104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe objective of this study was to locate nerves arising from the CNS that have a cardioregulatory function in the tarantula,Eurypelma marxiSimon. Ramifications of the paired abdominal nerve VIIIb merge with the cardiac ganglion within the first heart segment. Electrical stimulation of the branches of nerve VIIIb that connect with the cardiac ganglion produce changes in heartbeat rate and amplitude. Nerve cutting experiments indicate that no other cardioregulatory nerves are present.Both increases and decreases in heart activity can be produced upon electrical stimulation of nerve VIIIb on each side of the heart. Only one action potential associated with the response of each type could be recorded in each member of the nerve pair. Therefore, we conclude that there are two inhibitory and two acceleratory neurons that arise in the central nervous system to modulate heartbeat activity.The inhibitory effect becomes maximal at a stimulation frequency of 20–30 Hz and the accelerator effect at 30–40 Hz. The aftereffect of acceleratory nerve activity exceeds that of inhibitory nerve activity. When the inhibitor and accelerator are activated simultaneously, the inhibitor dominates.The regulatory nerves interact with neurons in the cardiac ganglion. During inhibition, the number of externally recorded spikes in each ganglionic burst is decreased. The rate and magnitude of the heartbeat are decreased concomitantly. Stimulation of the accelerator enhances electrical activity in the cardiac ganglion at the same time that the heartbeat rate and amplitude are increa

ISSN:0022-104X    

DOI:10.1002/jez.1402310105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractCells were isolated from the liver of the skate and the uptake of β‐alanine followed using [14C]‐β‐alanine. The isolated hepatocytes showed good viability, were found to accumulate β‐alanine from the incubation medium, and did so in a manner indicating a transport system involving a saturable carrier. The data for the rate of β‐alanine uptake suggest that this may be a rate‐limiting step in the oxidation of the amino acid by the liver. Experiments indicated that the transport system could distinguish β‐alanine from certain structurally similar molecules (L‐alanine and taurine, but not γ‐amino butyrate). Cells isolated from fish adapted to a diluted environment (50% seawater) showed no significant change in the uptake rate. However, evidence indicates that, over the range of β‐alanine concentrations occurring in the fish, the uptake rate would be acutely sensitive to small changes in the concentration in the blood, thus forming a self‐regulating system for

ISSN:0022-104X    

DOI:10.1002/jez.1402310106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractIndividual cells of theCaenorhabditis eleganssecretory‐excretory system were ablated by laser microbeam in various larval stages. Effects on growth, molting, osmoregulation, fertility, longevity, and dauer larva formation were tested. Single‐cell ablations did not prevent subsequent molting, but ablation of the pore cell or the duct cell resulted in the absence of the normal cuticular lining of the excretory duct following a molt. When the pore cell, duct cell, or excretory cell was ablated, the animals filled with fluid within 12–24 hr and died within a few days, producing very few progeny. Ablation of the excretory gland cell, on the other hand, had no obvious developmental or behavioral effects. Excretory activity was monitored in dauer larvae by observing pulsation of the excretory duct in conditions of differing osmolarity. The rate of pulsation was quite variable over time in conditions of low osmotic strength, but averaged five‐ to six‐fold higher than that observed in buffered saline. These observations, combined with the effects of laser ablation, lead to the conclusion that one function of the excretory system is osmor

ISSN:0022-104X    

DOI:10.1002/jez.1402310107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractDeterminations of nucleoside triphosphates (NTP) were made on rainbow trout erythrocytes segregated into age classes following velocity sedimentation at unit gravity. The NTP content of young cells was lower than that of mature cells, whereas it was significantly higher in the oldest cell population. Thin‐layer chromatography of erythrocyte cell extracts showed that both ATP and GTP were present and that the former dominated in all age groups. Potassium cyanide was significantly more effective than iodoacetate in lowering NTP levels in the cells of the young age class whereas in the oldest cells the reverse was tru

ISSN:0022-104X    

DOI:10.1002/jez.1402310108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThis work provides data demonstrating a stimulatory effect of insulin on macromolecular events occurring in cultured regeneration blastemata and demonstrates a synergistic interdependence between nerves and insulin in newt limb regeneration. The current experiments provide evidence for the following: (1) Insulin is paramount for expression of the mitogenic effect of nerves on cultured blastemata. (2) Insulin stimulates the incorporation of (3H)uridine into the acid‐insoluble fraction of blastemal homogenates, but it does not alter the turnover rate of incorporated labeled uridine. (3) Insulin also stimulates the incorporation of35SO4and (3H)leucine into both chondroitinase‐sensitive and chondroitinase‐resistant blastemal proteoglycans. (4) Insulin increases the uptake of radiolabeled precursors by the blastemata, namely, (3H)leucine, (3H)uridine,35SO4, (3H)α‐aminoisobutyrate, and (3H)2‐deoxy‐D‐glucose. The importance of insulin in the regulation of newt limb regeneratio

ISSN:0022-104X    

DOI:10.1002/jez.1402310109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractNuclei were isolated from sea urchin (Hemicentrotus pulcherrimus) embryos during early stages of development, and the rates of histone acetylation and deacetylation were examined. Histone acetylation was measured in the presence of 6 mM sodium n‐butyrate, a potent inhibitor of deacetylase, and in the absence of the inhibitor. The deacetylation activity was estimated from the difference between the rates with and without the inhibitor. The activities of the acetylation and the deacetylation, and the ratio of deacetylation to acetylation were unchanged during the stages between early blastula and gastrula. Autoradiographic analysis of acetylated histones showed that all of the internal histones of the nucleosomes were acetylated and that no apparent difference was found in the pattern of the acetylated fractions during the stages compare

ISSN:0022-104X    

DOI:10.1002/jez.1402310110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractIn spherical cells with a central mitotic apparatus, the centers of the asters are closer to the poles than to the equator. This circumstance is basic to several hypothetical explanations of the way in which the mitotic apparatus establishes the division mechanism. This investigation was designed to determine whether that geometrical relationship is necessary for division.Fertilized, mechanically denuded sand dollar eggs were inserted into glass loops, which reduced the diameter in the constriction plane from the normal 142 to 78–80 μm and partly constricted the cell into equal parts. The mitotic apparatus straddled the constriction, and its length was not significantly changed. The manipulation increased the distance from the astral centers to the poles and decreased the distance from the astral centers to the equator to a degree that reversed the normal distance relations. These cells divided normally.Ethyl urethane (0.06 M) reduces the size of the mitotic apparatus and blocks cleavage in spherical cells. When treated cells are confined in 80‐μm i.d. capillaries, they divide. Treated cells also divide when they are constricted by an 80‐μm i.d. glass loop if the mitotic apparatus straddles the constriction. An equal degree of constriction in the subfurrow and subpolar areas did not reverse the effect of urethane.The results demonstrate that cleavage does not depend on the normal distance relation between the mitotic apparatus and the poles, and that the urethane effect can be remedied only by reducing the distance between the mitotic apparatus and the equatorial surface. Both findings are inconsistent with the polar stimulation hy

ISSN:0022-104X    

DOI:10.1002/jez.1402310111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY