摘要:

AbstractConjugation between cells of mating type IV and V inEuplotes patellasyngen 2 was studied with respect to mating inducing factors (gamones) and their effects on pair formation. Type IV cells excreted into the medium gamone(s) of type IV which induced selfing pairs in and enhanced the gamone's excretion by cells of type V. The same effects on type IV cells were induced by cells and gamone(s) of type V. The number of homotypic pairs (IV‐IV, V‐V) increased with an increase in the level of Ca2+in the medium. However, heterotypic pairs (IV‐V) were constantly formed even in the absence of Ca2+, and their formation was not influenced by the level of Ca2+. When cells of two types were mixed, heterotypic pairs were predominantly produced, although cells were capable of forming pairs between homotypic types. These results revealed that pair formation between heterotypic cells was different from that between homotypic cells in the requirement of Ca2+, and that the specificity of pair formation between heterotypic cells was more predominant than that of homotypic

ISSN:0022-104X    

DOI:10.1002/jez.1402330202

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe properties of the haemolymph ofPalaemon elegansfor oxygen and carbon dioxide transport were studied with respect to the considerable fluctuation in the environmental conditions normally experienced by this prawn in intertidal rock pools. The haemolymph was found to have a high oxygen affinity (P50= 3.6 Torr, 15°C, pH 8.0) and a large oxygen carrying capacity (1.17 mmol.L−1), as well as a marked Bohr shift (φ = ‐ 1.7). Under some conditions, the affinity appeared to be independent of temperature as did the n50value (n50= 2.8). Experiments in which the pH of the haemolymph was varied using fixed acid together with two different CO2tensions demonstrated a specific CO2effect on O2affinity, which did not affect the Bohr factor. The nonbicarbonate buffer value of the haemolymph was found to be high (16.02 mmol.L−1.pH unit−1). The in vivo postbranchial haemolymph pH at 15°C was 7.89 with a calculated Pco2of 1.26 Torr. A large functional Haldane coefficient was observed (1.25), which was only moderately temperature dependent. The haemolymph exhibited an extremely high capacitance for CO2at low Pco2values (βCO2= 8.4 mmol.L−1.Torr−1). Some functional implications of linkage between the large Bohr and Haldane effects are discussed in light of pr

ISSN:0022-104X    

DOI:10.1002/jez.1402330203

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe phase‐response curve (PRC) for the circadian rhythm in the flight activity of a cave‐dwelling bat,Hipposideros speoris, constructed with 0.063‐msec light flashes, reported here is thefirstof its kind for any circadian system and isunlikeany other phase‐response curves constructed for other nocturnal animals. The phase responding with maximal advances (90°) and the phase responding with maximal delays (0°) of this PRC were exposed to light flashes of systematically varying durations from 0.083 to 3.33‐msec. For 0° phase, the flashes of 0.063‐3.33 msec effected delay phase shifts of comparable magnitude. For 90° phase, the flashes of 0.063‐1.0 msec effected advance phase shifts, whereas 3.33‐msec flashes effected unmistakable delay phase shifts with advancing transients. Phase shifts evoked with such light flashes are further compared with phase shifts evoked with pulses of longer durations (15 min to 2.

ISSN:0022-104X    

DOI:10.1002/jez.1402330204

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

年代:1985

数据来源: WILEY

摘要:

AbstractThis study is presented to compare two methods of evaluating changes in muscle function after amputation of the left leg at the knee. Rats were fed a 50%Lathyrus odoratusdiet, which causes exostoses to develop at sites of attachment of certain muscles. The rats were on the experiment for 3, 6, or 9 weeks. Muscles of rats killed at 6 weeks were weighed to determine whether atrophy or hypertrophy had occurred. Sizes of exostoses were evaluated subjectively at each time period. The left adductor longus and quadratus femoris muscles underwent considerable atrophy and their exostoses were smaller than on the right side. The left iliopsoas increased in weight and had the larger exostosis. However, the left pectineus increased in weight but had the smaller exostosis. It is concluded that changes in muscle weights and changes in sizes of exostoses both reflect changes in muscle function, but because the two methods respond by different mechanisms, the results do not always agree.

ISSN:0022-104X    

DOI:10.1002/jez.1402330205

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

年代:1985

数据来源: WILEY

摘要:

AbstractMale mud fiddler crabs (Uca pugnax) were shown to hyperosmoregulate in 10% and 50% seawater (SW) and to hypoosmoregulate in 150% and 200% SW. Crabs fully immersed in the media did not osmoregulate as well as those that were free to enter or leave the medium at will (“natural” environment). Gill sodium‐plus‐potassium ATPase (Na,K‐ATPase) enzyme specific activity was characterized in crude homogenates. After acclimation (21 days) in 10% SW, all six gill pairs in immersed crabs showed significantly higher enzyme specific activity (ESA) than 100% SW controls; crabs in 50% SW had significantly higher ESA in gills 3 through 6. With one exception, a decrease, acclimation to 150% or 200% SW did not significantly change gill ESA in immersed crabs. In all media, gills 5 and 6 had approximately 75% of the total ESA in the crabs' gills. Crabs in the “natural” environment showed a similar pattern of changes in gill ESA. Thus, changes in gill ESA appear to be important only in hyperosmotic regulation and in active sodium uptake by the gills from dilute media. The time‐course of changes in crude homogenate ESA in gills 5 and 6, after transfer of 100% SW crabs to 10% SW, was relatively rapid (significantly increased after 1 day) and correlated well with changes in hemolymph osmolality. Three different microsomal preparations from gills 5 and 6 did not show significantly increased ESA until between 3 and 7 days after transfer. Therefore, gill Na,K‐ATPase activity may be altered both by rapid modulation of existing enzyme and by longer term synthe

ISSN:0022-104X    

DOI:10.1002/jez.1402330206

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

年代:1985

数据来源: WILEY

摘要:

AbstractPeroxidase activity was examined cytochemically in the mucosal epithelium along the length of the digestive tract from the esophagus through the large intestine during the development of the bullfrog,Rana catesbeiana. In the tadpole of this species, cells with peroxidase activity were found abundantly in the esophagus, stomach, and large intestine; and the types of such cells differed according to the region: ciliated cells and mucous cells in the esophagus; ciliated cells in the stomach; and brush cells, absorptive cells, and goblet cells in the large intestine, respectively. After metamorphosis, however, peroxidase activity was observed exclusively in absorptive cells and goblet cells in the large intestine. Peroxidase activity was commonly demonstrated in apical vesicles or granules, to some degree in rough endoplasmic reticulum, and in some elements of the Golgi apparatus. Furthermore, reaction product was also found in mucus covering the luminal surface of such epithelial cells. These findings indicate that peroxidase‐positive cells, which may have the ability to synthesize peroxidase as a secretory product, were distributed mainly in three regions of the digestive tract in tadpoles (esophagus, stomach, and large intestine), but were centered in one specific region, the large intestine, after metamorphosis. Concomitantly, the variety of types of peroxidase‐positive cells decreased during metamorphosis. Our results indicate that some of the peroxidase in the digestive tract may have a secretory origin and may play a role in the defense against microorgani

ISSN:0022-104X    

DOI:10.1002/jez.1402330207

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

年代:1985

数据来源: WILEY

摘要:

AbstractFragments of iris ring, spleen, kidney, tail, tail blastema, tentacle, tentacle blastema, and spinal cord were implanted between the outer and the inner cornea in normal eyes ofXenopus laevistadpoles at stage 50 (according to Nieuwkoop and Faber, '56).Results show that tail blastema, tentacle blastema, and spinal cord can induce varying degrees of lens‐forming transformations in the outer cornea, while the iris ring, spleen, kidney, tail, and tentacle do not produce any significant response from the cornea, thus demonstrating that the lens‐inducing capacity is not widely distributed in the larval tissues ofXenopus.The causes of the different degrees of lens‐inducing capacity in the various larval tissues are disc

ISSN:0022-104X    

DOI:10.1002/jez.1402330208

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

年代:1985

数据来源: WILEY

摘要:

AbstractThird‐stage larvae of the swine parasitic roundworm,Ascaris suum, were grown in stationary multiwell cultures in the presence of synthetic steroid hormones or the HPLC fractions of a steroid extract of adult female reproductive tracts to determine the subsequent effect of these compounds on length of 4th‐stage larvae. Log doses of ecdysone, 20‐hydroxyecdysone, progesterone, and makisterone standards, from 50 pg/ml to 500 ng/ml, were incubated with larvae for 1 day in RPMI‐1640 supplemented with cholesterol. Length measurements were made on 4th‐stage larvae after an additional 6 days of incubation. All compounds and extracts had a dose‐dependent enhancement on length of these larvae; the partially purified extracts were more potent than their synthetic analogs. All standards and extracts except makisterone showed reduced or no response at higher dose levels. In contrast, makisterone continued to have maximal effect from 500 pg/ml to 500 ng/ml. Short exposure period to the steroid and low concentration were critical to demonstrate enhanced growth in this homologo

ISSN:0022-104X    

DOI:10.1002/jez.1402330209

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe effects of pinealectomy and exogenous melatonin treatment on the reproductive system of male anoles were examined at several different times of year. In September pinealectomy of anoles exposed to either a stimulatory LD 14:10 light cycle or a nonstimulatory LD 10:14 light cycle induced significant testicular growth and development over that observed in sham‐operated anoles. At a nonphotosensitive time of year (December) pinealectomy also had a significant progonadal effect but no effect of pinealectomy was seen in February‐March. Daily melatonin injections given either in the morning or afternoon (or both) failed to block gonadal growtheither (1) in sham‐operated or pinealectomized anoles exposed to LD 14:10 in the fall or (2) in pinealectomized lizards exposed to LD 10:14 in the fall. Continuous melatonin administration via subcutaneous silastic implants blocked the progonadal effects of pinealectomy in the winter (December).The results show that (1) pinealectomy can have significant progonadal effects; (2) these effects are seasonal but can encompass phases of the annual testicular cycle which are either photoperiod‐dependent or temperature‐dependent; and (3) melatonin may be a reproductively active factor

ISSN:0022-104X    

DOI:10.1002/jez.1402330210

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

年代:1985

数据来源: WILEY

摘要:

Abstract17β‐Hydroxysteroid dehydrogenase (17β‐HSD) catalyzes the interconversion of estradiol‐17β (E2) and estrone (E1). The present study is designed to investigate the following: (1) the developmental stage of hamster embryos at which 17β‐HSD activity first becomes detectable, and (2) the E1→ E2and E2→ E1conversion rate in the preimplantation hamster embryo. Embryos obtained from superovulated hamsters on days 1–4 were cultured in medium containing 107 ng [3H]E1or – E2/ml and the respective conversion product, [3H]E2or – E1, was isolated and assayed. The results show that (1) E1→ E2conversion was active in all embryos at the rate of 0.57, 0.66, 0.54 and 0.48 fmol/embryo/hr for day 1 (one‐cell), 2 (two‐cell), 3 (eight‐cell) and 4 (blastocyst), respectively, and (2) E2→ E1conversion was not detectable in hamster embryos. In long‐term blastocyst culture, E2→ E1conversion becomes detectable at 25 hours and increases sharply from 25 to 47 hours. These results suggest that (1) 17β‐HSD may function mainly to convert E1into E2in preimplantation hamster embryos and (2) E2→ E1conversion may become a

ISSN:0022-104X    

DOI:10.1002/jez.1402330211

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

年代:1985

数据来源: WILEY