摘要:

AbstractMale redheaded buntings (Emberiza bruniceps) were subjected to continuous darkness (DD) or short days (8L/16D) after photo‐stimulation (15L/9D) for either 15 or 30 days. Two groups of birds (four each), after photo‐stimulation for 30 days, were continued on a regimen of 15L/9D. Another two groups (of four each) of photo‐sensitive birds were also subjected to DD or 8L/16D; they served as controls. The effect of transfer to DD or 8L/16D on the size of testes was found not be dependent upon the size attained at the time of transfer. The rate of testicular regression was nearly the same under both the treatments, i.e., in those birds transferred either to DD or to 8L/16D. The birds that were maintained on 15L/9D maintained enlarged testes; this excluded the possibility of the onset of photo‐refractoriness during the treatment period. On the other hand, testes were not photo‐stimulated in the photo‐sensitive birds subjected to DD or 8L/16D. These results are consistent with the Bünning‐Pittendrigh avian external coincidence model, but could be explained alternatively by a relatively simple internal coincidence model. Nevertheless, the application of the law of parsimony suggests the acceptance of the hypothesis of the external coi

ISSN:0022-104X    

DOI:10.1002/jez.1402210202

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe structure of the body‐wall muscle of the ascidian,Halocynthia roretzi, was investigated by electron and light microscopy. Thin (about 8 nm in diameter), (18–20 nm in diameter), and 10‐nm filaments were seen in this muscle cell. These filaments, however, did not have the regular arrangement of a striated or oblique structure. We also found by three‐dimensional reconstruction that this muscle cell is multinucleated. Based on these observations, we report that the body‐wall muscle of the ascidian,Halocynthia roretzi, is smooth and multi

ISSN:0022-104X    

DOI:10.1002/jez.1402210203

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe primary purpose of this study was to identify the muscles active during flight and determine their temporal relationships in the flight‐cycle, thereby laying the foundations for further investigations of the neural control of flight in the cockroach. The wing‐beat frequency of tethered roaches and the frequency of the flight‐cycle in restrained animals was similar, varying between 23 and 30 beats/second. Intracellular recordings of metathoracic and metacoxal muscle were made simultaneously with electromyograms from the elevators of the wing. Muscles 155, 157, 161, 162, 163, 177A, and 174‐6 were active near the onset of elevator activity; muscles 153, 154, 164, 165, 167, 169, and 177C were active approximately 180° out of phase with the elevators. Muscles 177A and 177C, bifunctional in nature, act as antagonists during flight and as synergists to extend the femur. Since the femur is held flexed during flight, the activity of the femoral flexors, 181A‐C and 182C, was determined during flight. 181A and B showed a bimodal phase distribution while 181C and 182C was almost continuously active during flight. Therefore, the flight‐motor‐program reciprocally drives the elevators and depressors and can continuously drive the motor‐neuronal pool operating the femoral flexor. This continuous drive fixes the femur and permits 177A and 177C to act on

ISSN:0022-104X    

DOI:10.1002/jez.1402210204

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

年代:1982

数据来源: WILEY

摘要:

AbstractThrough direct observations onAmbystoma mexicanumit is found that the pulmonary artery contracts during stimulation of the vagus nerve and during acetylcholine treatment. In addition, contraction of the artery is a response to lung deflation and also occurs when the vagus fibers from the lung wall are sectioned; lung inflation and atropine treatment produce dilatation of the artery. Hypercapnia and noradrenaline had no effect on pulmonary vasomotor tone. The constrictor is located between the ductus Botalli and the lung, where histological examination showed a concentrically arranged layer of smooth muscle cells. It is suggested that the vagus nerve contains afferent fibers from stretch receptors in the lung wall inhibiting the vasomotor tone in the pulmonary artery. It is further suggested that the pulmonary vasoconstrictor inA. mexicanumis homologous to the vasoconstrictor previously found in a similar location in anurans and reptiles.

ISSN:0022-104X    

DOI:10.1002/jez.1402210205

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

年代:1982

数据来源: WILEY

摘要:

AbstractRainbow trout (Salmo gairdneri), acclimated to 5°C or 20°C, were reacclimated to water of the opposite temperature. The time course of alterations in fatty acid composition of microsomes from gills and liver was monitored over a 28‐day period. Two to six days were required for maximum changes in fatty acid levels with acclimation to 20°C, whereas 10—17 days were required in the opposite direction. Fatty acids from gill microsomes had lower U/S (ratio of unsaturates to saturates) and UI (unsaturation index) and a shorter average chain length than liver microsomes; these differences were preserved with acclimation. In both tissues the U/S, UI, and chain length increased with cold adaptation and decreased with warm adaptation. In gill microsomes, changes in UI and U/S were due primarily to altered levels of saturated fatty acids and 20:4 (n‐6) and 20:5 (n‐3). The latter two acids, products of the Δ5 desaturation step in PUFA biosynthesis, also contributed to the changes in unsaturation indexes were initially mediated by large but transient changes in levels of saturates and monoenes, whereas changes in polyunsaturated fatty acids of the n‐6 and n‐3 families were delayed 3—6 days. Thus, changes in fatty acid composition that accompany acclimation to a different temperature can be resolved into those metabolic reactions (e.g., Δ5 desaturation) that are of major importance and, in the liver, into temporally more than one mechanism (e.g., altering monoenes and PUFA a

ISSN:0022-104X    

DOI:10.1002/jez.1402210206

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

年代:1982

数据来源: WILEY

摘要:

AbstractXenopus laeviswas adapted stepwise to 600 m osmolar sodium chloride. After adaptation, the level of argininosuccinate lyase was raised 9‐fold, carbamoylphosphate synthetase 6‐fold, and ornithine carbamoyltransferase and arginase 3‐fold. Liver glutamate dehydrogenase was also raised 5‐fold; kidney glutamate dehydrogenase was unchanged. InBufo viridissimilarly adapted, there was a 5‐fold increase in argininosuccinate lyase. WhenXenopus laeviswas adapted to 600 m osmolar sucrose, there was only an increase in argininosuccinate lyase, and that was only 2.4‐fold. This indicates that the increases in urea cycle enzymes are at least in part responses to sodium chloride rather than just to osm

ISSN:0022-104X    

DOI:10.1002/jez.1402210207

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

年代:1982

数据来源: WILEY

摘要:

AbstractLysine‐vasopressin and oxytocin were tested on the normally neotenous adult Mexican axolotl,Ambystoma mexicanum, to determine their influence on metamorphosis. The salamanders were divided into four groups, and daily injections of saline, lysine‐vasopressin, oxytocin, and TSH were made over a 28‐day test period. Tail height, gill length, and body weight were measured as indicators of metamorphic change. Additionally, thyroid uptake of131I was determined.The results showed that the vasopressin and oxytocin groups had a significant (P<0.01) loss in tail height and body weight compared to controls, but showed no gill rachis resorption or131I uptake. These results suggest that the effects of vasopressin and oxytocin were not mediated by TSH and thyroxine, but rather may be caused by an antagonism of prol

ISSN:0022-104X    

DOI:10.1002/jez.1402210208

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

年代:1982

数据来源: WILEY

摘要:

AbstractHemocyanin is present in the megalops and young juvenile stages of the Dungeness crabCancer magister. The hemocyanin of these early developmental stages resembles that of the adult in molecular weight, appearance in the electron microscope, and copper content. The six subunits of megalops and early juvenile hemocyanins are similar in molecular weight to those of the adult (Mr= 67,000–82,000); however, the larval 25S hemocyanins and the adult 25S hemocyanin each contain one unique subunit. The five other 25S hemocyanin subunits are present in different relative amounts in the youngs crabs than in the adult. The subunit composition of adult 16S hemocyanin includes only five of the six adult 25S subunits. The 16S hemocyanin fractions of the megalops and juvenile crabs are different from adult 16S as well as adult, juvenile, and megalops 25S hemocyanins. This is the first ontogenic structural change in crustacean hemocyanins that has been documente

ISSN:0022-104X    

DOI:10.1002/jez.1402210209

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

年代:1982

数据来源: WILEY

摘要:

AbstractA 1‐cm‐diameter hole was punched through rabbits' ears. The surface potentials during wound healing of regenerating (normal) and partially and nonregenerating (decartilaged) ears were measured. The time sequence of these surface potentials were similar to those reported to occur in regenerating amphibians forelimbs. A small positive potential was observed for about 1 week, and this was followed by a larger negative potential of up to 20 mV, with different durations. The duration of the positive potential was about the same as which was observed in amphibians. The duration and the amplitude of the negative potential were greatest for completely regenerating ears with overgrowth, smaller for partially regenerating ears, and smallest for the nonregenerating ears. The surface potential was localized. If a nipple‐shaped outgrowth developed after the hole was closed, the surface potential was observed only on this outgrowth; immediately outside it, the potential was normal. We concluded that the negative bioelectric activity accompanies growth, and while growth continues, negative bioelectric potential cont

ISSN:0022-104X    

DOI:10.1002/jez.1402210210

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

年代:1982

数据来源: WILEY

摘要:

AbstractMorphometric analysis and thymidine autoradiography were used to test the hypothesis that differential growth in the form of proliferative asymmetry is a major contributor to formation of lateral body folds in somatopleure. Chick embryos provided an opportunity to study both spatial and temporal differentials within an individual stage of development. Ectoderm and mesoderm were studied as separated tissues. Thymidine labeling index ranged from 34% to 49% in ectoderm and 43% to 66% in mesoderm and was assumed to reflect rate of proliferation in populations with a 100% proliferation index. Density of cell ranged from ten to 13 cells/1,000 μm2in ectoderm and ten to 15 cells/1,000 μm2in mesoderm, with a mean density of 12 cells/1,000 μm2. Cellular proliferation was important in folding, because ectoderm showed highest frequencies of labeling and highest cell density in folding levels. Correlation of proliferative differentials with morphogenesis suggests that proliferation is the form of growth contributing to formation of lateral body folds in 20‐somite chick emb

ISSN:0022-104X    

DOI:10.1002/jez.1402210211

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

年代:1982

数据来源: WILEY