Showing papers in "The Biological Bulletin in 1967"
TL;DR: Experiments involving colony fusion, subsequent vascular budding, and the analysis of color patterns in resultant systems suggest that cells of the simple vessel walls govern the morphology of the regenerated zooids.
Abstract: 1. Properties of Botryllus schlosseri which give it outstanding promise for studies in developmental genetics are reviewed.2. Laboratory culture procedures, in vitro fertilization, and a method for raising embryos in vitro are described. Controlled successions of complete life cycles can now be achieved in any laboratory.3. Experiments involving colony fusion, subsequent vascular budding, and the analysis of color patterns in resultant systems suggest that cells of the simple vessel walls govern the morphology of the regenerated zooids.4. Results of some preliminary genetic crosses are reported.
166 citations
TL;DR: It is concluded that reef corals are among the most productive organisms known and that, in Florida corals, the boring green algae contribute very little indeed to this productivity.
Abstract: Oxygen exchange is reported for 14 species of Florida reef corals in the dark and at different light intensities. Oxygen tension was monitored with a recording polarographic electrode. Results are given as grams of carbon fixed per square meter of coral surface per day, and compensation light intensities were given for each species. Maximum ratios of photosynthesis to respiration varied from 1.9 to 5.8. Boring, filamentous green algae living in the skeleton of Dichocoenia stokesii were not observed to change their rate of oxygen consumption from dark conditions up to 5000 footcandles of light. It is concluded that reef corals are among the most productive organisms known and that, in Florida corals, the boring green algae contribute very little indeed to this productivity. Some data are given on the light impinging on Florida reefs and the light penetrating coral skeleton. Reasons for believing boring green algae are of minor importance are given in the discussion.
149 citations
TL;DR: The relationship between active uptake and external concentrations at low concentrations resembles that found in fresh-water crustaceans.
Abstract: Measurements have been made of the rates of influx and efflux of sodium ions in sea water, 40% sea water and fresh water in the killifish, Fundulus heteroclitus. Measurements have also been made of the rates of efflux of chloride and bromide ions in the same media. The rate of drinking has been measured using inulinlabeled sea water. In sea water the sodium influx averages 20 mM Na/kg./hr., of which more than half enters by diffusion, the rest by drinking. In fresh water the rate of influx is about 0.6 mM Na/kg./hr., practically all of which takes place by active transport. Adaptation to fresh water is accompanied by a great reduction in permeability to sodium and chloride ions. This fall in permeability takes place within a few minutes of transfer to fresh water but the increase of permeability on return to sea water takes many hours. The relationship between active uptake and external concentrations at low concentrations resembles that found in fresh-water crustaceans.
126 citations
TL;DR: The vertical-migration rhythm will persist in the laboratory in constant illumination, constant temperature, and away from the influence of the tide for as long as eleven days, during which time the cells remain in approximate synchrony with the feral cells in nature.
Abstract: 1. The diatom, Hantzschia virgata, appears on the surface sands of Barnstable Harbor, Mass., during daytime low tides. Surface accumulations of this organism reach such concentrations that the sand takes on a golden-brown color. As the tide returns the cells re-burrow into the sand.2. The cells can be prevented from emerging onto the surface sands at low tide by artificially darkening the area with an opaque covering just as the tide recedes. Cells already on the surface can be made to re-burrow by similarly placing them in darkness.3. The vertical-migration rhythm will persist in the laboratory in constant illumination, constant temperature, and away from the influence of the tide for as long as eleven days. During this time the cells remain in approximate synchrony with the feral cells in nature.4. In nature, when the times of low tide approach sunset, the cells rephase their rhythm to the early morning hours of daylight. Cells collected during late afternoon low tides and returned to L:D or L:L in the ...
123 citations
TL;DR: The methods involved repeated CsCl-buoyant density centrifugations, digestion of interfering polysaccharide, and monitoring of the procedures with added radioactively labeled DNA, and final determinations were made on material characterized by several criteria as highly purified.
Abstract: 1. Values of 8.26 ± 0.30 pg. (9.5 χ haploid amount) for Lytechinus pictus and 3.30 ± 0.25 pg. (4.3 χ haploid amount) for Strongylocentrotus purpuratus have been obtained for the DNA content per egg of these sea urchins. The methods involved repeated CsCl-buoyant density centrifugations, digestion of interfering polysaccharide, and monitoring of the procedures with added radioactively labeled DNA. The final determinations were made on material characterized by several criteria as highly purified.2. Mitochondrial (M) and yolk (Y) fractions of differentially centrifuged homogenates of L. pictus eggs contain the bulk of the cytoplasmic DNA. It is uncertain to what extent the smaller variable amount (11.5 to 26.5%) found in the supernatant may be derived from breakdown of M- and Y-particles.3. For distribution between M- and Y-fractions the best present value is considered to be about 3:1. Since yolk spherules are approximately one-third as numerous as mitochondria, the amount of DNA is estimated to be the sam...
120 citations
TL;DR: Two series of experiments were undertaken to identify a possible environmental factor able to cause a deviation to the male phenotype during sex differentiation, on the working hypothesis that low male incidence in clones composed otherwise of hermaphrodites indicated a lability in the sex-determining mechanism through which the genotype normally produces the herMaphrodite phenotype.
Abstract: 1. Rivulus marmoratus is the only known hermaphroditic fish species naturally self-fertilizing. Tissue grafts between wild-caught fish and their uniparental laboratory descendants give the autograft reaction, indicating propagation by selfing in the wild also. Only hermaphrodites have been found in the wild locally, although selfing through more than 10 uniparental laboratory generations yielded a few primary male gonochorists, under 5% in contrast to over 95% that were hermaphrodites. Females seem to be non-existent.2. Two series of experiments were undertaken to identify a possible environmental factor able to cause a deviation to the male phenotype during sex differentiation, on the working hypothesis that low male incidence in clones composed otherwise of hermaphrodites indicated a lability in the sex-determining mechanism through which the genotype normally produces the hermaphrodite phenotype.3. Individuals of two clones, each in its own jar throughout life, were exposed to the eight combinations of...
112 citations
TL;DR: The action spectrum for spawning suggests cytochrome c as a chromophore in Ciona intestinalis, and the animals spawn when returned to the dark after a short illumination period, provided they have received enough energy.
Abstract: 1. The spawning of Ciona intestinalis with respect to light was studied, using both white light and monochromatic light.2. A one-hour dark-adaption period followed by exposure to light resulted in spawning by 66.6% of the 884 animals tested.3. Spawning occurs an average of 27.3 minutes after the onset of illumination.4. Illumination need not be continuous until spawning occurs; the animals spawn when returned to the dark after a short illumination period, provided they have received enough energy.5. The action spectrum for spawning suggests cytochrome c as a chromophore.
97 citations
TL;DR: There was a 46% inhibition in the growth rate of larvae between the optimum temperature and the minimum temperature at which development is completed, and a large proportion of these embryos survived and developed normally through metamorphosis when placed at room temperature.
Abstract: 1. Development of the embryos of Nassarius obsoletus within egg capsules is regulated by sea-water temperature. An increase in the time required between spawning and the emergence of veliger larvae is slight between 28° and 20° C., about 0.25 day for each degree decrease in temperature. Between 20° and 16.5° C., the corresponding increase was 2 days per degree decrease in temperature. At 11.5° C., development was not completed and larvae did not emerge from their egg capsules after nine weeks. However, a large proportion of these embryos survived and developed normally through metamorphosis when placed at room temperature. 2. The growth rate of planktonic veliger larvae of N. obsoletus was greatest at approximately 25° C. The lowest temperature at which the development to metamorphosis was completed was at 16° to 17° C. There was a 46% inhibition in the growth rate of larvae between the optimum temperature and the minimum temperature at which development is completed. 3. The larval life of N. obsoletus veligers may be divided into two stages. The first of these, the "developmental period," is one during which rapid growth and morphological development occur. This is followed by the "delay period" characterized by a gradual decrease in growth rate. Reduced temperature may influence the rate of growth and consequently the length of the "developmental period." The termination of the "developmental period" comes with the "creeping-swimming stage." The duration of the "delay period" may be quite variable and is determined by the availability of a favorable sediment for settlement.
97 citations
TL;DR: The brain hormone extracted from brains of Bombyx mori was purified by use of heating, ammonium sulfate precipitation, Sephadex gel-filtration, and DEAE-cellulose chromatography, and the most purified preparation was active when injected into brainless pupae of Samia cynthia ricini.
Abstract: 1. The brain hormone extracted from brains of Bombyx mori was purified by use of heating, ammonium sulfate precipitation, Sephadex gel-filtration, and DEAE-cellulose chromatography. On the basis of protein measurement, about 8000-fold purification was achieved. The most purified preparation was active by 0.002 µg. protein when injected into brainless pupae of Samia cynthia ricini.2. The brain hormone manifested highly heterogeneous molecular forms which were revealed by Sephadex gel-filtration and by DEAE-cellulose chromatography. The molecular weights of the major components were estimated by Sephadex gelfiltration as ranging from 9000 to 31,000.
83 citations
TL;DR: 1. When female Aedes aegypti were given a daily opportunity to take a blood meal over a 9-day period, the number of mated females feeding on days 3, 6, and 9 was significantly less than thenumber of virgins feeding.
Abstract: 1. When female Aedes aegypti were given a daily opportunity to take a blood meal over a 9-day period, the number of mated females feeding on days 3, 6, and 9 was significantly less than the number of virgins feeding. This low period of feeding coincides with the terminal phases of the first, second, and third gonotrophic cycles, respectively.2. The "mated" feeding pattern could be established in a virgin female by the implantation of a male accessory gland. Copulation without semen transfer or the implantation of a testis was ineffective in inducing the pattern of biting.3. Functional ovaries in the female receiving the accessory gland implant are required in order for the implant to exert its effect. Implantation of a normal ovary plus an accessory gland into females lacking ovaries produced the mated biting pattern.4. The material from the male accessory gland also controls oviposition behavior by female mosquitoes. Mated females lay their eggs readily on completion of oogenesis. Virgins mature an equal...
79 citations
TL;DR: Urinary output of water exceeds the diffusional net (osmotic) input of water as calculated, and this mechanism, here demonstrated for the first time in crustaceans, is suggested as being of adaptive significance.
Abstract: 1. The osmotic performance of the small cancroid crab Rhithropanopeus harrisi (Brachyura) has been surveyed in order to assess the mechanisms mainly responsible for its success in colonizing waters of low salinity.2. This crab shows hyper-regulation of chloride and osmotic pressure in media up to about 60-70% sea water, and a slight tendency to hypo-regulate in higher salinities.3. Like other crabs, Rh. harrisi maintains a relatively high blood concentration and produces a blood-isotonic urine.4. Urine production, estimated by an indirect method, approximates 24% of the body weight per day in low salinities, implying a high rate of water turnover.5. Approximately ⅓ of the total salt loss is via the urine.6. Inward permeability to water, as judged by D2O influx rate, is decreased at lower salinities. This mechanism, here demonstrated for the first time in crustaceans, is suggested as being of adaptive significance.7. Urinary output of water exceeds the diffusional net (osmotic) input of water as calculated...
TL;DR: The data indicate that female A. aegypti in nature may normally gels during mating and that loss of semen following second mating may result from a defect in this process.
Abstract: 1. The effectiveness of mating of female Aedes aegypti that had previously been mated was compared to that of virgin females. Non-virgin females mated less readily than virgin females and copulation was of somewhat shorter duration. Genital union was firm, and insemination occurred in both virgin and non-virgin females, yet semen was generally not retained in the copulatory bursa of females that had previously been mated. This effect was most evident when one or two days had elapsed between matings. Multiple insemination, with utilization of sperm from both matings, however, was occasionally effective when less than 5 hours separated the first and second matings.2. Factors derived from the accessory glands of the male and, to a lesser extent, the testes appeared to induce this loss of semen.3. It was suggested that semen normally gels during mating and that loss of semen following second mating may result from a defect in this process.4. These data indicate that female A. aegypti in nature may normally ut...
TL;DR: In this article, a study was made of the compounds in shrimp extracts which induce the proboscis search reaction in Nassarius obsoletus and the results showed that the compounds were as follows: alanine, asparagine, aspartic acid, betaine, glutamic acid, glycine, histidine, homarine, inosine, isoleucine and leucine.
Abstract: 1. A study was made of the compounds in shrimp extracts which induce the proboscis search reaction in Nassarius obsoletus.2. Compounds identified in shrimp extracts were as follows: alanine, asparagine, aspartic acid, betaine, glutamic acid, glycine, histidine, homarine, inosine, isoleucine, leucine, lactic acid, lysine, methionine, phenlyalanine, proline, serine, taurine, threonine, trimethylamine oxide, tryptophan, tyrosine, urea, and valine. Carnitine was tentatively identified. The amino acids and lactic acid were determined quantitatively; betaine was determined semi-quantitatively.3. Glycine (ca. 10-3 M) and lactate (ca. 5x 10-4 M) were the only compounds identified in the extracts which possessed marked stimulatory capacities when tested individually; betaine (ca. 10-3 M) was mildly stimulatory. However, quantitative analyses of these compounds in shrimp extracts showed that they were present in insufficient concentrations to account for the responses observed with the dilutions of extract which we...
TL;DR: periodic sampling of a Neapolitan population of the cidaroid sea urchin Stylocidaris affinis, revealed an annual reproductive cycle and conspicuous components of the yolk granules are protein and neutral mucopolysaccharide.
Abstract: 1. Periodic sampling of a Neapolitan population of the cidaroid sea urchin Stylocidaris affinis, revealed an annual reproductive cycle.2. In female urchins, primary oocyte growth begins only in September and continues for almost a year until maximum size is attained the following August.3. In the oocytes of this species, conspicuous components of the yolk granules are protein and neutral mucopolysaccharide. Acid mucopolysaccharides, probably destined to be cortical components of the ripe egg, are synthesized only as the primary oocytes are nearing their maximum size.4. After reaching their maximum size in August, the primary oocytes undergo maturation divisions (probably en masse) to become ripe eggs. The ripe eggs are apparently shed soon after being produced in August or September.5. In male urchins, spermatogonia give rise to spermatocytes, which accumulate in an ever-thickening layer in the testes during the winter, spring and summer. The spermatocytes seem blocked from differentiating into more advan...
TL;DR: It appears that growth of spines requires a very precise resorption as well as deposition of calcite, and the relationship between breakage, regeneration and internal spine morphology was established by producing sharp lines of color in the spines of young urchins and new cycles in the spine of larger animals, both as a result of regeneration.
Abstract: 1. Numbers of cycles in the spines of S. purpuratus were positively correlated with animal size.2. Examination of 500 spine sections in this study led to the hypothesis that cycles are the result of breakage and regeneration.3. The relationship between breakage, regeneration and internal spine morphology was established by producing sharp lines of color in the spines of young urchins and new cycles in the spines of larger animals, both as a result of regeneration.4. From observed morphology and experimental evidence, it appears that growth of spines requires a very precise resorption as well as deposition of calcite.
TL;DR: In two species the combined hydrolytic capacities of the gut flora are considered sufficient for it to play an important part in digestion of proteins, fats and carbohydrates; and in the other species there is evidence that it can participate to a lesser but still significant extent.
Abstract: 1 Histological, histochemical and bacteriological methods have been used to study digestion and the nature and source of digestive enzymes in nine species of leech2 The gastrodermis is not differentiated morphologically into secretory and absorptive structures and there is little difference in the structure of the crop or intestine3 Endopeptidases, which initiate proteolysis in most animals, lipases and amylases do not appear to be produced by the leech digestive system4 The possibility that the gut flora is concerned in digestion in compensation for the lack of endogenous enzymes, has been investigated using mass cultures of the microorganisms normally present in crop and intestine In two species the combined hydrolytic capacities of the gut flora are considered sufficient for it to play an important part in digestion of proteins, fats and carbohydrates; and in the other species there is evidence that it can participate to a lesser but still significant extent5 Exopeptidases, as typified by the
TL;DR: The mud snail, Nassarius obsoletus, was shown to be an excellent test animal for studies of chemoreception and a bioassay procedure was developed for studying the properties of substances which contribute to the response-inducing capacities of shrimp extracts.
Abstract: 1. The mud snail, Nassarius obsoletus, was shown to be an excellent test animal for studies of chemoreception. This snail responds to substances diffusing from dead animals by giving a series of extensions of the proboscis. With this response as the criterion, a bioassay procedure was developed for studying the properties of substances which contribute to the response-inducing capacities of shrimp extracts. N. obsoletus can be used in studies in which it is desirable to compare in a quantitative manner the response-inducing capacities of closely related solutions.2. The principal response-inducing compounds in shrimp extracts were heat stable, more soluble in polar than in non-polar solvents, non-volatile, of low molecular weight, alkali-stable, partially acid-labile, and resistant to oxidation.3. Separations of shrimp extracts on ion exchange columns revealed that the principal response-inducers were amphoteric and/or weakly basic compounds which were augmented by some acidic and/or neutral compound (s)....
TL;DR: The effects of decreasing ambient temperature varied considerably among species and abrupt lowering of ambient temperature tended to induce arousal in M. lucifugus and M. sodalis, whereas these species responded similarly to L. borealis when exposed to gradually decreasing temperature.
Abstract: 1. Responses to upward and downward changes in ambient temperature from 5° C. were studied in dormant bats of the species E. fuscus, P. subflavus, M. sodalis, M. lucifugus and L. borealis. Rectal temperatures and heart rates were recorded.2. Except for L. borealis which did not arouse until ambient temperature reached about 20° C., all species responded by arousal from dormancy when the temperature was increased to 15° C.3. The effects of decreasing ambient temperature varied considerably among species. E. fuscus invariably aroused from dormancy. L. borealis never aroused but showed a thermoregulatory response by increasing its metabolism to compensate for the increase in heat loss. The responses of the other species depended upon the abruptness of the temperature change. Abrupt lowering of ambient temperature tended to induce arousal in M. lucifugus and M. sodalis, whereas these species responded similarly to L. borealis when exposed to gradually decreasing temperature. P. subflavus usually aroused in re...
TL;DR: The data indicate that PcfO2 represents a useful index of the level of VO2, which may be used by the animals in natural environments using SCUBA-diving technique and in samples obtained from urchins in their natural habitat showed large variations.
Abstract: 1. Oxygen uptake (VO2) by sea urchins has been measured and correlated with partial pressures of oxygen in the ambient water (PiO2) and in coelomic fluid (PcfO2). PcfO2 was also analyzed in samples obtained from animals in natural environments using SCUBA-diving technique. In addition, changes in PcfO2 were recorded during prolonged air exposure of the animals.2. The three species investigated, Strongylocentrotus purpuratus, S. franciscanus and S. droebachiensis, showed steady levels of VO2 until PiO2 had dropped to 60-70 mm. Hg. At lower PiO2 the oxygen uptake decreased corresponding to the rate of decline of PiO2.3. Changes in PcfO2 at decreasing PiO2 closely paralleled the changes in VO2, except for a common initial compensatory increase in PcfO2. The data indicate that PcfO2 represents a useful index of the level of VO2.4. PcfO2 in samples obtained from urchins in their natural habitat showed large variations. Means by which the relationship between PcfO2 and VO2 may actively be used by the animals in...
TL;DR: It is proposed that this mode of feeding has been retained throughout lugworm evolution because the observed feeding behavior should have been successful throughout the range of lugworm habitats, and because of the importance of larval settlement and survival.
Abstract: 1. A comparison of the habitats of two sympatric lugworms shows that Abarenicola pacifica lives in a muddier and more poorly sorted sediment than does A. claparedi vagabunda.2. Both species, like Arenicola marina, are capable of suspension feeding, feed predominantly on surface rather than deep sediment, and integrate feeding and defecation into their irrigation cycle.3. Respiration and sediment turnover rates indicate that Abarenicola claparedi vagabunda is more active than A. pacifica. Both species seem to need little (3-5%) of the organic carbon ingested.4. Transplantation experiments suggest that physical factors rather than availability of food may limit A. pacifica to muddier sediment and that the distribution of A. claparedi vagabunda may be a result of larval settlement and survival.5. It is proposed that this mode of feeding has been retained throughout lugworm evolution because the observed feeding behavior should have been successful throughout the range of lugworm habitats, and because of the ...
TL;DR: The marine flagellate Platymonas subcordiformis rapidly takes up amino acids at concentrations likely to be found in nature, providing further support for a normal role of heterotrophy in phytoplankters.
Abstract: The marine flagellate Platymonas subcordiformis rapidly takes up amino acids at concentrations likely to be found in nature. The relation between velocity of uptake and substrate concentration was determined, and the apparent maximum uptake velocity estimated. Accumulated C14 amino acids were assimilated into alcohol-insoluble compounds and entered oxidative pathways as shown by detection of evolved C14O2. The contribution of the uptake mechanism at an ambient glycine concentration of 1.0 µmole/l. to nitrogen requirement of the cell was found to be roughly 10% for optimal laboratory growth conditions. In nature, where growth conditions are probably less favorable, the contribution would be considerably greater. This provides further support for a normal role of heterotrophy in phytoplankters.
TL;DR: Large quantities of the supplied amino acids were found to have been taken up and retained by the epidermal cells in almost all regions of the body, and especially in those parts most in contact with the external medium.
Abstract: 1. Specimens of Asterias forbesi, Henricia sanguinolenta. and Echinaster spinulosus were exposed up to 24 hours to sea water media containing C14-labeled amino acids. The distribution of the labeled compounds after periods of 1 hour to 21 days was determined by means of stripping-film autoradiographs of histological sections of the specimens.2. The results from all three species were very similar. Large quantities of the supplied amino acids were found to have been taken up and retained by the epidermal cells in almost all regions of the body, and especially in those parts most in contact with the external medium. Variations in uptake between the different types of cells making up the epidermal layer appeared to be only minor and relative.3. The amino acids were found not to have penetrated through the madreporite channels or through the buccal opening. If fluid entered these regions, the amino acids were presumably completely removed by the adjacent superficial cells, which always demonstrated large amou...
TL;DR: It is concluded that nutrition in starfish is probably a dual process involving both a continuous epidermal absorption of dissolved exogenous materials for the benefit primarily of the superficial tissues, and intermittent oral feeding to satisfy the more general needs of the entire organism and especially of the internal organs.
Abstract: 1. Small specimens of A. forbesi and H. sanguinolenta were exposed to dissolved C14-amino acids and glucose. The subsequent distribution of these materials was then determined in the following five regions of the body: disk (including the gonads), oral body wall of the rays, aboral body wall of the rays, stomach, and digestive glands. 2. In all cases, large proportions of the labeled nutrients were taken up into the external tissues. The largest amount was usually absorbed into the oral body wall, which probably possesses a proportionately greater ventilated surface area than the other regions. 3. Over a period of 20 days there was little indication of movement of the externally absorbed nutrients into the internal organs. In this period, very little loss of amino acid radioactivity was noted. The amino acids became progressively less soluable in alcohol, suggesting that they were incorporated into the structural proteins of the organism. 4. Glucose radioactivity declined progressively over the 20-day period. As observed in Asterias, this decline occurred almost exclusively in the portion of absorbed glucose that remained alcohol-soluble. This fraction was possibly used as an energy source while the insoluble fraction became incorporated into more inert elements. 5. A number of the specimens of Henricia appeared to pump up and absorb the glucose medium into their digestive organs. This was interpreted as a form of feeding behavior possibly initiated by the relatively high concentration of glucose used. The much less concentrated amino acid medium failed to initiate such a reaction. 6. It is concluded that nutrition in starfish is probably a dual process involving both a continuous epidermal absorption of dissolved exogenous materials for the benefit primarily of the superficial tissues, and intermittent oral feeding to satisfy the more general needs of the entire organism and especially of the internal organs.
TL;DR: Evidence is presented which demonstrates a relationship between the neurosecretory cells of the Pars intercerebralis and the circadian rhythm, and the suggestion is made that the pars interceebralis acts as a rhythmic suppressor of general locomotory activity resulting in rhythmic locomotORY behavior.
Abstract: 1. Ablation of the region of the pars intercerebralis of the cockroach brain induced arrhythmicity of locomotory activity in the animal. Evidence is presented which demonstrates a relationship between the neurosecretory cells of the pars intercerebralis and the circadian rhythm.a. Surgical removal of the pars intercerebralis, including the lateral and medial neurosecretory cells, results in arrhythmicity and an increased level of activity.b. In a large number of cases where normal activity and rhythms regenerated post-operatively, neurosecretory cells could be demonstrated histologically to be present and presumably functioning.2. The suggestion is made that the pars intercerebralis acts as a rhythmic suppressor of general locomotory activity resulting in rhythmic locomotory behavior.3. In animals where rhythms "regenerate" several weeks post-operatively, the speculation was made that biological regenerative processes, such as regeneration of several nerve tracts of a few remaining neurosecretory cells, i...
TL;DR: The inhibition by galactose, and other actively transported sugars, is effected during or after absorption of the sugar and is not a competition for a common site at the external interface.
Abstract: 1. The uptake of cycloleucine (l-aminocyclopentane-1-carboxylic acid) by dogfish intestinal tissue is inhibited by galactose in 10-minute incubations but not in 2-minute incubations.2. Preincubation of the tissue in galactose inhibits subsequent uptake of cycloleucine in 2-minute incubations without sugar. Addition of phlorizin to the preincubation with galactose abolishes inhibition. The inhibition by galactose, and other actively transported sugars, is effected during or after absorption of the sugar and is not a competition for a common site at the external interface. Leucine on the other hand, competitively inhibits cycloleucine uptake in 2-minute incubations.3. The inhibitory effects of galactose are dependent on time of preincubation and concentration of the sugar.4. In 2,4-dinitrophenol-inhibited tissues, the previous absorption of galactose inhibits the subsequent uptake of cycloleucine.5. Both galactose uptake and cycloleucine uptake are sodium-dependent. However while potassium antagonizes sodiu...
TL;DR: It is suggested that during the spinning of a cocoon plasmatocytoids transform into both immature and mature adipohemocytes, that when the larvae are densely cocooned mature adipOhemocytes are largely formed by the maturation of immature adipoemocytes, and that in pharate pupae new mature adipiocytes are derived from both immature adipehemocytes and plasmatictoids.
Abstract: 1. The hemocytes of Galleria mellonella (Linnaeus) larvae were identified and differentially counted in unfixed hemolymph with phase microscopy. The numbers of hemocytes per microliter of hemolymph were obtained from both unfixed and heat-fixed larvae. Hemolymph volumes were determined by the amaranth red method. These studies were made to determine what changes in the hematology occur as the last stage larvae pass through distinctive phases in transforming into pupae. 2. In differential counts, plasmatocytoids decrease, immature adipohemocytes suddenly appear, and mature adipohemocytes steadily increase. Spherule cells, oenocytoids and dividing hemocytes decrease as Galleria larvae develop into pupae. 3. The numbers of hemocytes per microliter of hemolymph increase as Galleria larvae proceed towards the pupal stage in both unfixed and heat-fixed animals. Counts were always significantly higher in heat-fixed than in unfixed larvae. 4. The hemolymph volume is the same in both unfixed and heat-fixed larvae. The hemolymph volume declines from about 34% (56.7 microliters) in precocoonspinning larvae to less than 16.4% (19 microliters) in newly formed pupae. 5. It is estimated from the various data presented that an average of 1,456,000 hemocytes remain in circulation within the hemocoele of unfixed larvae from the fifteenth through the twentieth days of life, and that with pupation more than one-half of these cells fall out of circulation. 6. In three out of 5 cases it was possible to correlate decreases in the plasmatocytoid population with increases in adipohemocytes. It is suggested that during the spinning of a cocoon plasmatocytoids transform into both immature and mature adipohemocytes, that when the larvae are densely cocooned mature adipohemocytes are largely formed by the maturation of immature adipohemocytes, and that in pharate pupae new mature adipohemocytes are derived from both immature adipohemocytes and plasmatocytoids. 7. The hemocyte picture of Galleria is compared to that of Prodenia and Bombyx. In all three of these Lepidoptera the plasmatocytoids decrease and the hemocytes with many polysaccharide and/or lipid or other types of inclusions increase prior to pupation. Galleria differs from the other two species in that their hemocytes with lipid or other inclusions do not appear until about the sixteenth or seventeenth days of larval life, do not divide, and in many cases are derived from circulating plasmatocytes.
TL;DR: The observed sensitivity to amino acids and to potassium ions is thought to enable the animal to recognize living prey after it has been pierced by the setae present on the cirri.
Abstract: 1. Feeding responses were elicited when solutions of amino acids and of organic and inorganic cations were applied to the cirri and mouth parts of Lepas and other barnacles. Proteins, peptides, sugars, neutral organic molecules, and anions were without effect.2. Of the common amino acids, Lepas anatifera was most responsive to L-glutamic acid and L-proline. It was very sensitive also to betaine and taurine.3. The order of sensitivity to amino acids and to other zwitterionic substances did not correlate with any obvious physical or chemical property.4. Inorganic and organic cations had to be applied at higher concentrations than many amino acids to produce a response and probably acted on different receptors. The potassium ion had the greatest effect of those tested.5. The observed sensitivity to amino acids and to potassium ions is thought to enable the animal to recognize living prey after it has been pierced by the setae present on the cirri.
TL;DR: The supraesophageal ganglion of a mature animal secretes less hormone than that of an immature animal, though it still induces a significant amount of regeneration when implanted into an immature, decerebrate host.
Abstract: Normal and regenerative growth are partially separated from maturation, since during the later stages of maturation, growth does not occur. A mature animal almost invariably regenerates a pygidium but rarely regenerates segmental rudiments. The supraesophageal ganglion of a mature animal secretes less hormone than that of an immature animal, though it still induces a significant amount of regeneration when implanted into an immature, decerebrate host. The rate of secretion of such a ganglion is as great during the first five days after implantation into the host as it is subsequently. A single ganglion from an immature donor (in which it is known to be actively secreting) induces no regeneration when implanted into a mature host. Immature grafts, from which posterior segments have been removed, engage in virtually no segment regeneration when stitched into mature hosts. However, implantation of three ganglia removed from immature donors into each graft results in the formation of a significant but very sm...
TL;DR: Both maxima of the diurnal time course of oxygen evolution as well as the free-running rhythm were expressed at a moderate (250 ft.) and at a high (1000 ft.-c.) light intensity, indicating an unusually loose coupling of the light and dark reactions.
Abstract: 1. Oxygen exchange by Acetabularia crenulata in various light regimes was monitored continuously for as long as 10 days by means of a rate-measuring graphite oxygen electrode.2. The time course for photosynthesis in 8-hour light periods is bimodal, and consists of an initial burst of oxygen production followed by a depression and a subsequent slow rise to a (usually) higher maximum in the latter part of the period. The two maxima show differential sensitivity to the deleterious effects of long-term exposure to the environment of the oxygen electrode.3. The light curve for photosynthesis departs from linearity at the comparatively low intensity of 200 ft.-c. but does not reach saturation below 1300 ft.-c., indicating an unusually loose coupling of the light and dark reactions.4. Both maxima of the diurnal time course of oxygen evolution as well as the free-running rhythm were expressed at a moderate (250 ft.-c.) and at a high (1000 ft.-c.) light intensity. A free-running rhythm was also found at 45 ft.-c. ...
TL;DR: The apparently simplest interpretation of the results of the experiments suggests that there must be separate, although perhaps not completely independent, control schemes for synthesis and release of pituitary gonadotropin.
Abstract: The characteristics of the gonadal photoperiodic responses in the White-crowned Sparrow, Zonotrichia leucophrys gambelii, have been examined by the use of cyclic photoperiodic regimes consisting of a day with a long photoperiod followed by n days with short, non-stimulatory daily photoperiod, n with the range 0-5; responses measured were the rates of gonadal growth and the concentration of pituitary gonadotropin. The gonadotropic effect of a single 20-hour photoperiod extends through at least seven days with short (8-hour) non-stimulatory photoperiods. The apparently simplest interpretation of the results of the experiments suggests that there must be separate, although perhaps not completely independent, control schemes for synthesis and release of pituitary gonadotropin.