摘要:

AbstractEight mating type complementary strains ofE. raikoviwere mixed two by two in all the possible combinations. In addition to heterotypic pairs, homotypic pairs of both mixed strains were usually found. Each strain was then suspended with the cell‐free fluid obtained from any other complementary strain. Most strains appeared capable of both producing an active cell‐free fluid and responding to a heterotypic cell‐free fluid by pairing. The induced pairs were usually able to complete conjugation, to survive, and to yield viable offspring. The results indicate that mating inducing factors (gamones) are normally released into the extracellular environment by theE. raikovi

ISSN:0022-104X    

DOI:10.1002/jez.1402260102

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn order to characterize differences in mating types inEuplotes vannus, two cell populations of complementary mating types were mixed and exposed to a pattern of irritation (switching schedule of agitation and rest). Cells costimulate each other, as is seen from courtship behavior during still intervals, but do not pair. Prolonged periods of treatment cause distinctly reduced cell interactions. After 72 hr they have ceased completely: Overstimulated cells have lost their ability to conjugate. However, with fresh cells of mating types, which are different from both constituents of the mixture, overstimulated cells mate normally as judged by time course, cycloheximide‐sensitivity, and concanavalin A (ConA) binding. Conjugation competence thus is selectively lost only for that mating type which has been the partner in the perturbated mixture. The required classification of pairs with regard to mating‐type combinations were confirmed by several identification procedures using amicronucleates and doublets. The observed phenomena during the mating‐type‐specific loss of conjugation ability are consistent with the concept that this is due to a physiological disappearance of a specific mating substance, which might correspond to the receptor side of the extended gamone‐receptor hypothesis of Miy

ISSN:0022-104X    

DOI:10.1002/jez.1402260103

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

年代:1983

数据来源: WILEY

摘要:

AbstractDaytime and nighttime rates of oxygen consumption (VO2) were determined for young freshwater prawns during progressive hypoxia. During daytime hypoxia VO2fell slightly, then was maintained at 0.200 ml O2/gm/h to 40 mm Hg partial pressure of oxygen. Below 40 mm Hg VO2fell markedly. At night VO2averaged 0.310 ml O2/gm/h before falling at a critical pressure (Pcr) of 65 mm Hg. Sets of prawns were exposed to progressive hypoxia both day and night at rates simulating conditions during the closed respirometry studies. Prawns were sacrificed at different PO2s and analyzed for whole body lactate concentrations. Concentrations of 0.153 mg lactate/gm body weight were unchanged until the respective Pcrwas reached during either day or night. Below Pcrlactate concentrations increased at a constant rate regardless of the severity of hypoxia. Combined aerobic metabolism and anaerobic glycolysis did not increase as a result of progressive hypoxia, indicating a small energy requirement for oxyregulation. Anaerobic energy production via glycolysis during hypoxia proceeded at only 1–3% of the regulated aerobic metabolism. This is much less than in other crustaceans, underscoring the importance of well‐aerated environments both inMachrobrachium rosenbergii'snatural habitat and under aquaculture conditi

ISSN:0022-104X    

DOI:10.1002/jez.1402260104

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

年代:1983

数据来源: WILEY

摘要:

AbstractRabbit antibody to chicken liver mitochondrial glutamine synthetase was purified by immunoaffinity chromatography for analysis of the immunological relatedness of vertebrate glutamine synthetases. The antibody cross‐reacted with enzymes from representitives of all five vertebrate classes, indicating a high degree of evolutionary conservatism in the structure of the enzymes. A unique aspect of the immunological similarity of these enzymes is that it exists between cytosolic and mitochondrial enzymes which are, in general, immunologically distinct. The antibody did not cross‐react with two insect glutamine synthetases. Compositional difference indices, calculated from the amino acid compositions of glutamine synthetases from several species, gave a mean estimate of over 80% sequence homology for the vertebrate enzymes. The avian mitochondrial enzyme gave a mean 78% homology with the mammalian cytosolic enz

ISSN:0022-104X    

DOI:10.1002/jez.1402260105

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

年代:1983

数据来源: WILEY

摘要:

AbstractBranchial and cutaneous O2uptake as well as branchial ventilatory stroke volume and frequency were measured by twin‐chamber respirometry in conscious unoperated eels (Anguilla australis) at 20°C. The branchial ventilatory pattern comprised alternating periods of apnea and eupnea, together constituting a “Standard Breathing Cycle” (SBC = 1 apneic period plus the ensuing period of eupnea). SBC time in 17 eels averaged 15.5 min of which only 23% was devoted to eupnea. Reduction of the PO2of inspired water from 155 to 80 torr significantly increased the proportion of time devoted to eupnea to 49% of SBC time without significantly changing SBC time. Absolute cutaneous O2uptake (5.8 ml O2·h−1·kg−1) was largely independent of the frequency or occurrence of eupnea, with the relative contribution of the skin to total O2uptake averaging 47%. The histological appearance of the skin inA. australisis very similar to that described inA. anguilla: eel skin is only poorly vascularized. It was concluded that the skin may contribute to O2requirements other than its own, and that this adaptation is a consequence of the unusual intermittent pattern of gill

ISSN:0022-104X    

DOI:10.1002/jez.1402260106

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

年代:1983

数据来源: WILEY

摘要:

AbstractSubstrate oxidation was measured in the gills of blue crabs,Callinectes sapidus, acclimated to different salinities. The oxidation rates for glucose and the four major amino acids of hemolymph were about twice as great in the gills from crabs acclimated to 17%0seawater relative to the gills from crabs acclimated to full‐strength, 35%0seawater. Alanine oxidation contributed about 36% to the total CO2released from amino acid oxidation. Alanine was also deaminated and released into the medium as α‐keto acids. Both alanine oxidation and α‐keto acid formation were concentration dependent and did not appear to reach saturation within physiological concentrations. However, the rates of amino acid oxidation were not sufficient to explain the efflux of NH4+in excise

ISSN:0022-104X    

DOI:10.1002/jez.1402260107

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe regulation of sperm transport through the Wolffian duct of male amphibians is poorly understood. These experiments were conducted using rough‐skinned newts (Taricha granulosa) to determine if Wolffian ducts are capable of contracting in vitro and, if so, to characterize the contractile responses to acetylcholine (ACh), norepinephrine (NE), and neurohypophysial hormones. Dose‐response curves for NE and ACh, which were prepared by measuring isometric contractions, are similar to those reported for mammalian vas deferens. For NE, the minimum effective dose and ED50were found to be 1 × 10−5M and 4.17 × 10−5M, respectively. For ACh, the minimum effective dose was 3.2 × 10−8M and the ED50was 1.37 × 10−5M. Alpha‐adrenorecep‐tors appear to mediate the contractile responses to NE because phentolamine (10−5M) blocked or attenuated the response to NE (10−6M, 10−5M or 10−4M). Beta‐adrenoreceptors appear to mediate relaxation because dichloroisoproterenol (10−5M) enhanced the response to 10−5M NE. The contractile response to three neurohypophysial hormones were also investigated. Arginine vasotocin was more effective in eliciting contractions than oxytocin. The effect of lysine vasopressin was intermediate between arginine vasotocin and oxytocin. These experiments demonstrate that amphibian (Taricha) Wolffian ducts contract in vitro in response to neurotransmitters and neurohypophysial hormones. The contractile response to neurotransmitters occurs in a dose‐dependent manner; the response to neurotransmitters and neurohypop

ISSN:0022-104X    

DOI:10.1002/jez.1402260108

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe dorsal and ventral myogenic regions were isolated from the right and left wings of donor chick embryos. After removal of the ectoderm, the myogenic regions were grafted into the dorsal myogenic region of the right wing of host embryos in normal or reversed proximal‐distal orientation. All grafts were made so that the surface of the graft originally in contact with ectoderm was dorsal. It was expected that myogenic regions grafted into the myogenic region would participate in the normal formation of the host wing. However, after 7 days of further development many of the host wings had developed abnormal cartilages. To investigate the interactions between the tissue of the host and the tissue of the graft and the source of the tissue giving rise to ectopic cartilages, the donor embryos were labeled with tritiated thymidine. The location and shape of the graft were recorded at the time of the operation. The host wings and adjacent body wall were fixed 1, 3, and 4 days after the operation, sectioned, and prepared as autoradiographs. The location of the grafted cells in the host wing was determined by reconstructing the host wing and adjacent body wall. Serial sections and the reconstructions were examined to discover the correlates of abnormal cartilage formation. The following observations were made: 1) Grafts from the dorsal region of the right and left wing in normal orientation participated in the formation of the groove at the base of the wing ventral to the nineteenth somite that produces the extensor surface of the elbow. Grafts from the ventral region of the right and left wing in normal orientation, and all grafts in reversed orientation, did not participate in the formation of the groove. 2) Grafts in normal orientation increased in length on the axis of the humerus and did not increase in width. Grafts in reversed orientation increased in both length and width. Increase in width caused the graft to extend into the proximo‐caudal corner of the wing. 3) Wings with grafts from the dorsal regions of the right and left wings in normal orientation were not clearly abnormal 4 days after the operation. When the groove ventral to the nineteenth somite did not form normally, ectopic cartilage differentiated where the groove should have been from grafted cells of the myogenic region. Increase in width of the graft into the proximo‐caudal corner of the wing produced an increased mass of graft cells ventral to the nineteenth somite and an increased amount of ectopic cart

ISSN:0022-104X    

DOI:10.1002/jez.1402260109

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn some species of amphibians, the regenerative response to limb amputation is not uniform. For example, regenerative ability varies from one individual to another within the speciesXenopus laevis, Ambystoma maculatum, andAmphiuma tridactylum. In many species, limb regenerative ability declines with increasing age. The objective of this investigation was to determine if this variation in regenerative ability can be explained by variation in the quantity of innervation. In each of the above‐named species, limbs were amputated and allowed to regenerate. The quantity of innervation (percentage of cross‐sectional area of amputated surface occupied by nerves) was measured in the amputated part of the limb as close as possible to the amputation surface. The presence, rate, or extent of limb regeneration in that specific limb was then compared to the quantity of innervation at the amputation surface. The results indicated that there was no correlation between innervation and the rate or extent of regeneration inXenopus laevisorAmbystoma maculatum. On the other hand, inAmphiuma tridactylum, those limbs that regenerated were the ones that had the highest levels of innervation. InAmbystoma maculatum, the quantity of innervation was measured at five different stages, from early larvae to mature adult. The results showed that the quantity of innervation was highest during the larval period, reaching a maximum at the late larval stage before declining greatly to the adult level. It appears that the decline in regenerative ability in the adult cannot be attributed solely to a reduction in innervation to below the threshold le

ISSN:0022-104X    

DOI:10.1002/jez.1402260110

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

年代:1983

数据来源: WILEY

摘要:

AbstractChick embryo mesoderm cells at various stages of differentiation were cultured in three‐dimensional matrices of hydrated collagen. The tissues used were: stage 5 mesoderm from regions adjacent to the primitive streak; stage 12 mesoderm, comprising somitic, unsegmented (segmental plate) and lateral plate mesoderm; and stage 18 sclerotome. Explants were examined by phase contrast microscopy, including time‐lapse, and scanning and transmission electron microscopy. The cells showed an increased ability to adhere to, and move in, the collagen gel with advancing stage. Of the stage 12 tissues, the unsegmented mesoderm was initially the slowest to grow out of the explant. Sclerotome cells showed by far the greatest ability to move within the gel. Where the collagen fibrils were randomly oriented, the cell morphology was polypodial and advancing lamellipodia showed clear undulations at their leading edges. A distinction was drawn between these undulations and the classical major ruffles which are seen in two‐dimensional culture to uplift and pass back along the cell surface. The latter were not seen in the collagen matrix and were presumably suppressed by the three‐dimensional culture configuration while the leading edge undulations were not. Ultrastructural examination showed that the cells possessed patches of amorphous material on their surface, which was sometimes interposed between the plasma membrane and collagen fibrils. Addition of hyaluronie acid (2 mg/ml) had an effect only the segmented mesoderm, where outgrowth was enhanced. Although the addition of plasma fibronectin (50 μg/ml) to the cultures did not affect any of the tissues, the removal of this substance, by antifibronectin antiserum or by the use of fibronectin depleted serum, inhibited outgrowth in most cases. The only tissue not reproducibly inhibited in this way was sclerotome. Alignment of the collagen fibres by the explants was observed, accompanied by an elongation of the outgrowing cells which, in bipolar form, preferentially moved up and down the aligned tracts. Scanning electron microscopy suggested that cell processes attached to, and presumably exerted tension on, bundles of fibrils thereby pulling them into line. Cell‐to‐cell contact was not accompanied by contact paralysis as judged by time‐lap

ISSN:0022-104X    

DOI:10.1002/jez.1402260111

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

年代:1983

数据来源: WILEY