Showing papers in "The Biological Bulletin in 1972"

Chemotactic and growth responses of marine bacteria to algal extracellular products

Abstract: 1. The possibility that planktonic algae possess a "phycosphere," a zone surrounding them created by the production of extracellular products which may serve as bacterial nutrients, is examined.2. Bacterial growth in algal cultures to which no additional organic material is added is greatest only as the cultures age and algal cell lysis becomes obvious.3. Marine bacterial isolates are chemotactic to filtrates from algal cultures, but the response is significant only to filtrates from old cultures, again where cell lysis is evident.4. Specific compounds known to occur as algal extracellular products attract bacteria, but the threshold concentrations for attraction are unexpectedly high when compared with the generally very low concentrations of organic compounds in natural sea water.5. The validity of the phycosphere concept and its potential importance to marine microorganisms is discussed.

Induction and termination of pupal diapause in sarcophaga (diptera: sarcophagidae)

Abstract: 1. In temperate regions species of Sarcophaga overwinter in pupal diapause. The environmental control of diapause is investigated in Sarcophaga argyrostoma, S. crassipalpis, and three strains of S. bullata. Environmental cues of daylength and temperature, water content of the larval medium, and the sex of the animal determine the induction of diapause. Termination of diapause is temperature dependent.2. Daylength is of primary importance for induction. Diapause is completely averted when adult mothers and larvae are maintained under a long daily photophase or continuous light at 25° C. Short-day exposure of the adults and larvae at 25° induces a high incidence of diapause. However, if short-day is received by only the larvae, diapause is absent, and adult short-day without subsequent larval short-day produces a low diapause incidence. The maximum diapause response is observed when adults are maintained under a short daily photophase at 25°, and larvae are reared at a short daily photophase at 17°.3. Criti...

The inorganic composition of molluscan extrapallial fluid

Abstract: The inorganic composition of the extrapallial fluids of Mercenaria mercenaria, Mytilus edulis and Crassostrea virginica was significantly different from sea water. Calcium was the principal ion bound in the extrapallial fluids. This binding was accomplished by a non-dialyzable component that appeared to be a glycoprotein.

Suspension feeding by marine invertebrate larvae: clearance of particles by ciliated bands of a rotifer, pluteus, and trochophore

Abstract: 1. High speed cinefilms of a serpulid trochophore, a bdelloid rotifer, and an echinopluteus show two ways cilia remove particles from suspensions.2. In the pluteus a particle passing through the band of cilia triggers a localized change of beat which appears to be a reversal and which retains the particle on the upstream side of the band of cilia. Retention of particles by an induced local reversal of beat implies that the stimulus occurs during the forward effective stroke of a cilium and that the reversed effective stroke of this cilium or its neighbors begins before the forward stroke is completed. For this system, clearance and transport of particles, rejection of particles, and swimming can be accomplished by a single band of cilia.3. In the bdelloid rotifer, and probably in the serpulid trochophore, the opposed action of parallel preoral and postoral bands of cilia apparently causes the longer preoral cilia to push particles relative to the water during the latter part of the effective stroke. This ...

Loss of limbs as a stimulus to ecdysis in brachyura (true crabs)

Abstract: 1. Loss of 6 to 8 pereiopods or chelipeds triggers precocious molts in a number of marine crabs including the green crab, Carcinus maenas, the blue crab, Callinectes sapidus, and the fiddler crabs, Uca pugnax and U. pugilator, but not in the spider crab, Libinia emarginata. Mortality rates are negligible compared to those of animals induced to molt by eyestalk removal.2. Precocious molts call be elicited in the land crab, Gecarcinus lateralis, by the loss of 5 to 8 appendages (pereiopods and chelipeds) but the loss of all 10 appendages inhibits molting. Loss of a cheliped which in Gecarcinus may have a mass ten times greater than a pereiopod is no more effective than loss of a walking leg.3. The size of the regenerates formed in Gecarcinus is reduced by one-third from normal size when front 1 to 6 pereiopods are lost, and by one-half when 8 limbs are regenerated.4. When one or more partially regenerated limbs is removed before a certain critical time in the premolt period (Stage D0?) the animal re-regener...

The effect of copper (ii) on survival, respiration, and heart rate in the common blue mussel, mytilus edulis

Abstract: 1. The effects of Cu(II) on survival heart rate, and respiration in M. edulis have been determined. 2. Free Cu(II) is toxic to M. edulis causing respiratory and cardio-vascular depression and a toxicity threshold of 0.2 mg/l has been demonstrated. 3. Live animals can detoxify solutions of limited Cu(II) content. 4. Heat-killed homogenates are also effective in detoxifying solutions of limited Cu(II) content.

A hierarchy of histo-incompatibility in hydractinia echinata

Abstract: 1. Hydractinia represents a simple system in which to study induction, cellular-recognition mechanisms, and hyperplastic growth.2. Among various strains isolated from nature, there is a tissue incompatibility upon contact which results in the production of hyperplastic stolons (overgrowth) in one or both colonies of any binary combination of strains. The induction of hyperplasia probably involves surface-bound molecules produced by the ectoderm.3. A hierarchy of hyperplastic potential was established in two groups of ten strains each. A correlation between colonial morphology and rank in the hierarchy was noted.4. Consistency of morphology and intermediate forms of incompatibility between related strains (i.e., parent-offspring, half-sibs) suggests genetic control of histo-incompatibility and hyperplastic growth.

Studies on the development of the sea urchin Strongylocentrotus droebachiensis. I. Ecology and normal development.

Abstract: 1 Methods for obtaining viable gametes and embryos of the arctic-boreal sea urchin Strongylocentrotus droebachiensis are presented and practical suggestions are made regarding the suitability of this material for embryological use2 The useful breeding season extends from early January to mid-April for animals obtained from shallow subtidal regions of Cape Cod Bay or beginning roughly a month later for animals collected from the Gulf of Maine The "season" can be extended by at least two months by holding the ripe animals at 4° C3 The time course for the first division and for development to the four-armed echinopluteus are given for various temperatures Development time follows an inverse log relationship with temperature over the range of -1° C to 9° C4 The susceptibility of the eggs and embryos to temperatures in excess of 10° C and of the hatched blastulae to bacterial action are discussed in regard to laboratory experimentation and the natural distribution of the organism

Osmoregulation in three molluscs: acanthochitona discrepans (brown), glycymeris glycymeris (l.) and mytilus edulis (l.).

Abstract: The molluscs Glycymeris glycymeris, Mytilus edulis and Acanthochitona discrepans can be acclimated from sea water to salinities down to 25% sea water. During this acclimatization, these molluscs do not show any extracellular anisosmotic regulatory power except for potassium, the blood level of which is regulated at the concentration it has in the blood of sea water aclimated animals.During rapid acclimatization to diluted media, a transistory hyperosmotic state can be recorded in both blood and perivisceral fluid of the two bivalves species (Glycymeris glycymeris, and Mytilus edulis) but not in the blood of the polyplacophora Acanthochitona discrepans. This hyperosmotic state, which can last for about 96 hours in both bivalves when placed suddenly in diluted media, is due to the ability of those molluscs to isolate themselves from the external medium by closing their valves tightly. This "shell-closing" mechanism may help the animals in withstanding a sudden osmotic stress but it cannot contribute to the ...

Juvenile hormone in relation to the larval-pupal transformation of the cecropia silkworm.

Abstract: 1. Pupae retaining larval integumentary structures were formed after topical applications of Cecropia juvenile hormone or a mixture of juvenile hormone analogues to fifth instar Cecropia larvae prior to the initiation of spinning. Even daily applications of high doses did not result in a supernumerary larval molt.2. The integument was most sensitive to juvenile hormone (JH) two to four days prior to spinning.3. During the period of cocoon spinning, both the larval integument and viscera were insensitive to exogenous JH.4. During the prepupal period, the integument remained insensitive but the larval-pupal transformation of the viscera was retarded by topical application of JH.5. Juvenile hormone applied during the prepupal period prevented the normal "shutting-off" of the prothoracicotropic activity of the brain prior to pupal ecdysis. Consequently, the pupae did not diapause but initiated adult development within 5 days. The subsequent adults were normal externally but retained pupal or pupal-adult visce...

Studies on the development of the sea urchin strongylocentrotus droebachiensis. ii. regulation of mitotic spindle equilibrium by environmental temperature

Abstract: 1. The assembly and function of the mitotic apparatus in first division eggs of the sea urchin Strongylocentrotus droebachiensis were studied at 0° C and at 8° C by polarization microscopy in vivo and after isolation in hexylene glycol at controlled pH.2. No differences in the amounts of total tubulin synthesized over comparable periods of the cell cycle were observed.3. Mitotic apparatuses from a cell grown at 0° C are anastral, while those grown at 8° C are amphiastral.4. At a 0° C growth temperature only about one-half of the spindle fiber monomer is available for polymerization as at 8° C, indicating a natural variation in pool size.5. The amount of spindle monomer made available to the usable pool is specified only by the temperature (during early prophase, with temperature prehistory having no effect.6. The temperature coefficient for this apparent activation differs markedly from that of the mitotic process as a whole.7. The amount of tubulin obtained from an isolated mitotic apparatus, as determin...

Development and juvenile growth of the sea anemone, Tealia crassicornis.

Abstract: 1. Tealia crassicornis in the Friday Harbor Laboratories was observed to spawn from April to June. The eggs measure 500-700 µ in diameter, and bear surface spines 25 µ in length.2. The cleavage is superficial, resulting in small cells on the animal pole and large cells on the vegetal pole.3. Endoderm appears to be formed by multipolar ingression while the central yolk mass remains uncleaved and the formation of the gastrovascular cavity is achieved by absorption of yolk material.4. The settlement of planula larvae can be facilitated by adding the tubes of the polychaete worms, Phyllochaetopterus or Sabellaria to the culture dishes.5. A chronology of development is presented and the histogenesis of larval tissue is described.6. The young anemones have grown to a size of 4 cm in diameter with 60 to 70 tentacles within 18 months when fed in the laboratory.7. Young anemones can withstand starvation for at least 9 months. There is no growth when starved.

Evaporative water loss by tardigrades under controlled relative humidities

Abstract: The effects of relative humidity on the survival of desiccation by the tardigrade, Macrobiotus areolatus, were investigated. The most survivals were obtained when the animals were dried at relative humidities greater than 70% at 20° C. At these high humidities the animals form tuns, while at lower humidities they become flattened or crumpled. Anesthetized animals do not form tuns at any humidity.The rate of evaporative water loss from tuns in air was investigated by recording weight loss from animals kept at known relative humidities. Tuns formed by active animals lose water during the early stages of dehydration at a rate approximately 0.3 times the rate of anesthetized animals. Anesthetized animals equilibrate with the surrounding air within one hour, while tuns require more than 100 hours to equilibrate. At the end of 100 hours, the water content of tuns at 80% RH is 10-25%. During dehydration the permeability coefficient of tuns decreases a hundredfold (from 2.0-5.0 x 10-4 cm hr-11 atm-1 to 1.6-6.0 x ...

Adaptations to environmental oxygen levels in infaunal and epifaunal sea anemones

Abstract: Numerous investigators have shown correhatioius between various physiological properties of aquatic organisms amidthe chuaracteristic levels of oxygemuin which the aninuals are foumud. Older studies omusurvival timuueumuder how oxygen coiuditions gemuerally imudicate that, withimu closely related groups, burrowimug species are more resistamut to oxygen deprivatiomu thamu epifaunal forms (Packard, 1905). Sinuilarly, animals living imufast-moving streanus are less resistant than those living in rela fively unnuixed pond wafer (Fox, Simmonds and Washbourn, 1935 ; Bovbjerg, 1952 ; Walshue, 1948) . Walshe ( 1948) also showed that, among the chuirononuid larvae, resistance to oxygen lack is better correlated with ecological distributiomu than with phyhogeny. Nunierous studies support the very plausible notion that animals fronu low oxygen environments have a lower rate of oxygen comusumptionthuan their counter parts from high oxygen environments when compared at the sanue oxygen concen frations. Examples are two species of Balanus (Prasada Rao and Ganapati, 1968) epifaunal and infaunal tropical echinoids (Lewis, 1968) ; oxygen minimunu layer nuysids (Childress, 1971) ; stream and pomud insect larvae (Fox, Simmonds and Washbourn, 1935) , crustaceans (Fox and Simmonds, 1933) and leeches ( Manmu, 1956) ; and maldanid polychaetes (Mangum, 1963, 1964a). Perhaps the muuost elusive physiological correlate of emuvironnuemutal oxygen level is the degree to which oxygen consunuptiomu rate is maintained constant over a range of ambient oxygen concentratiomus. It is clear that in mamuyaquatic inverte brafes respiratory regulation withimua species is not entirely constant. It varies with temperature (Thomas, 1954 ; Wiens and Armitage, 1961) , weight (HeIff, 1928) , molt cycle (Thompson and Pritchard, 1969) and previous activity levels (Nimura and Inoue, 1969). Relatively few investigators have examined the metabolic response of aquatic animals to wide ranges of oxygen concentration following periods of oxygen de privation. Instead, most investigations have cluaracterized the respomuse to anoxia omily at oxygen concemutratiomus at or muear air saturation. Prosser, Barr, Pinc amid Lauer (1957) luave sluowmu that golduishurespond to chronic exposure to low oxygemu cotuditiomus by a reduction of standard nuefabohism amida shuiftof critical p02 to lower oxygen partial pressures, accompamuiedby increased hemoglobin concentrations and red blood cell counts. After oxygemulack, oxygemuconsumiuptiomi rates iii tlue mwl snail NOSSOY1ZIS Ol)SOlet,lS imicrease ( Kushimus and Niangunu, 1971 ) , but the response

Studies on the naturally occurring hemagglutinin in the coelomic fluid of an ascidian

Abstract: The occurrence of a natural hemagglutinin in the coelomic fluid of solitary ascidians, Styela plicata and Halocynthia hilgendorfi is reported. The hemagglutinin aggregated some mammalian erythrocytes and was absorbed by them. The hemagglutinins of the two ascidian species are specifically distinct.The hemagglutinin of Styela plicata is a large molecule which is very heat stable, resistant to trypsin digestion, but is destroyed by periodate. These data suggest that the hemagglutinin is polysaccharide or mucopolysaccharide.The hemagglutinin has no apparent opsonic effect, but it seems to play a role in the adherence of cell-to-cell and cell-to-glass surface.

Some factors controlling reproduction in the spider crab, libinia emarginata

Abstract: While oogenesis in crustaceans has frequently been studied, detailed knowledge of the anatomy, histology and hormonal controls involved in reproduction in female brachyurans have been limited (see Ryan, 1967; Adiyodi and Adiyodi, 1970 for review) . The structure and function of the reproductive system in the crab Portunus during the molting and reproductive cycles of the preadult and two adult instars has been examined recently (Ryan, 1967) . Although a definite relation ship exists between the molting and reproductive cycles in crustacean females, little is known regarding this relationship between molting and sexual maturation among the members of the family Majidae to which Libinia belongs. For instance, Maja is reported to undergo a final or terminal molt (Drach, 1939) . Whether this occurs in all Oxyrhyncha is not known. This study was undertaken to investigate the relationship between molting and sexual maturation and to determine what if any hormonal controls may be operating in ovarian development in the female spider crab, Libinia emarginata.

Studies on the development of the sea urchin strongylocentrotus droebachiensis. iii. embryonic synthesis of ciliary proteins

Abstract: 1. Cilia were isolated from sea urchin blastula pulse-labeled with 14C-leucine at various time points prior to and during ciliogenesis, the structural components fractionated by SDS-acrylamide gel electrophoresis, and the relative amount of labeled protein determined by autoradiography of gel slices.2. The two components of the ciliary ATPase dynein are synthesized differentially. The higher molecular weight enzymatic component pre-exists before fertilization; only the lower molecular weight component is synthesized after fertilization and it is made at a constant rate.3. A number of components with medium and low molecular weights are also synthesized uniformly throughout development. Of these, tubulin alone shows a marked increase in synthesis during late ciliogenesis. This protein is synthesized in three to four-fold excess over that needed for one generation of cilia. All of the others, including dynein, show no significant decrease in specific activity upon regeneration from previously labeled and de...

Early life-history of melampus and the significance of semilunar synchrony

Abstract: 1. The salt-marsh pulmonate snail, Melampus bidentatus, is placed in the Ellobiidae which family encompasses the most primitive of living Pulmonata and is regarded as not far removed from the ancestral stem-group of both modern land snails and freshwater pulmonates. Inhabiting the higher levels of salt marshes. Melampus is "amphibious": although an air-breather with a gill-less vascularized mantle-cavity functioning as a lung, if retains an archetypic pattern of reproduction with small eggs and a free-swimming veliger larva. 2. Field and laboratory studies over several years (based on natural populations at Little Sippewisset, Cape Cod, Massachusetts) have shown that egg-laying, hatching, and larval settlement are each confined to cycles of about four days in phase with the spring high tides. Adaptively such semilunar synchronies ensure that these processes occur only during the 2.3% to 4% of each month when the Melampus habitat in the upper 12% of the intertidal zone is bathed by seawater. 3. The annual reproductive period extends from late May or early June through early July. with either three or four cycles of egg-laying occurring at two-week intervals in phase with the tides of new and of full moon. Synchrony of egg-laying (and of the patterned aggregation and copulation which precede it) is obligate. Stocks of Melampus brought into the laboratory in spring will maintain the same semilunar rhythm of reproductive behavior during the summer period. 4. Eggs are small (about 109 ng organic carbon) and are laid in gelatinous egg-masses averaging 850 eggs. Mean numerical fecundity is 33,150 eggs per snail per year. For most freshwater pulmonates fecundity would lie in the range 8-800 eggs per snail per year. At 18° C, development to a well-differentiated and active veliger within the egg-shell takes 11 days. 5. Hatching shows semilunar synchrony in the field: enormous numbers of newly hatched veligers can be collected on the flood of appropriate spring tides. A series of experiments with laboratory-laid egg-masses showed that eclosion normally occurs in response to a sequence of about 4 tidal floodings in under 50 hours. Hatching can occur from egg-masses from 10 to 24 days after laying. Being facultative, the process allows better survival and overlap of cohorts but also reestablishes the synchronization with spring tides. 6. Veligers feed actively and grow from shell length 127 µ to 280 µ during their time in the plankton, deduced to be 14 ±2 days. The bulk of the settlement is into the exact vertical zone occupied by adult Melampus. 7. A period as a crawling, radula-feeding postlarva (after loss of velar lobes and operculum) is followed by an abrupt metamorphosis of the mantle and shell. Postmetamorphic spat grow rapidly. In terms of organic carbon or ash-free dry weight, growth extends through two orders of magnitude during veliger and early spat life, through more than three during the first eleven weeks, and six in the entire 3-4year life-span. In contrast, similar biomass growth measures in freshwater pulmonates involve only two to three orders in their life-span. 8. In Melampus, the shells of late veligers and of post-larvae show sinistral coiling, and those of metamorphosed spat and of adults dextral coiling. There is a metamorphosis of mantle and shell alone; throughout development, larval and spat stages, the internal organs are in their adult dextral arrangement. Such a metamorphosis from a hyperstrophic shell condition to an orthostrophic one is known to occur in the ectocommensal opisthobranch family Pyramidellidae and in certain other snails with planktonic larvae. The present study provides the first description of the succession of shell stages and metamorphosis for any pulmonate. 9. In conclusion, the small eggs, the mantle-shell metamorphosis, and the semilunar synchrony are discussed in their evolutionary setting. "Primitive" reproduction with small eggs, as retained in Melampus, confers advantages in dispersal and genetic potential. Evolution of larger eggs, as in the freshwater pulmonates, may have involved selection pressures to reduce the temporal extent of immature growth in seasonally variable environments. Mantle-shell changes in Melampus, including the metamorphosis, can be interpreted simply in terms of the changing needs for protective containment at different stages in the life-cycle. Semilunar synchrony of reproductive and of larval stages has evolved in response to the concursion of specialized aerial respiration and the primitive pattern of spawning large numbers of small eggs. The combination of both obligate and facultative processes in producing these synchronies is thought to be significant in relation to the long evolutionary history which can be hypothesized for these semilunar rhythms.

Regional survey of gene frequencies in the mud snail nassarius obsoletus

Abstract: Six gene loci were characterized by polyacrylamide gel electrophoresis of 5 protein systems in the mud snail, Nassarius obsoletus. Snail populations collected at 11 sites along an Atlantic coast tr...

Chemoreception in the migratory sea turtle, chelonia mydas

Abstract: 1. The ability of the green turtle (Chelonia mydas) to detect various chemical substances dissolved in water has been investigated using operant conditioning techniques. The turtles pressed underwater keys to obtain food reinforcement in the presence of a chemical stimulus.2. The turtles were capable of underwater chemoreception of β-phenethylalcohol, iso-pentyl acetate, triethylamine and cinnamaldehyde at approximate concentrations of 5 x 10-6 M or 5 x 10-5 M, but not of L-serine or glycine at an approximate concentration of 10-4 M.3. Stimulus generalization occurred when turtles were shifted from one test chemical to another.4. Intranasal injection of 0.35 M zinc sulfate solution interrupted olfaction for periods of from 1 to 5 days. Treatment with 0.35 M saline or magnesium sulfate had no effect on the performance of the chemical discrimination. It was concluded on the basis of these experiments that chemoreception in Chelonia is largely or entirely mediated by olfaction rather than by taste.5. The adv...

Accumulation of free fatty acids from sea water by marine invertebrates

Abstract: 1. It has been established that representative marine annelids can accumulate and metabolize dissolved free fatty acids.2. Net uptake of fatty acid from dilute solution by the polychaete Stauronereis rudolphi was confirmed by the loss of total higher fatty acids from the medium.3. Uptake takes place across the body wall by a mediated transport system having kinetic properties analagous to those of enzyme-catalyzed reactions, including saturation at high substrate concentrations and competitive inhibition.4. At concentrations above 5µmoles/l, palmitic and oleic acids are taken up at anomalously high rates probably due to the formation of micelles or molecular aggregates.5. Dissolved free fatty acids occurring in Los Angeles Harbor sea water were extracted and analyzed by thin-layer and gas chromatography.6. Although the Ks's of higher fatty acid transport are low, allowing efficient uptake from low concentrations, the levels of free fatty acids found in the natural environment are probably too low for upta...

Dimensions and ultrastructure of toadfish gills

Abstract: 1. This analysis of the measurement from the gills of about 60 toadfish using log/log transformation has shown that the gill area and its constituent parts increases with body weight as follows:Total area (mm2) = 560.7 W0.79 Total filament length(mm) = 302.1 W0.485 Secondary lamellae/mm on one side of filament = 15.99 W-0.075 Average bilateral area of a secondary lamella (mm2) = 0.06 W0.3722. A comparison with the corresponding data for other fish, particularly tunas, shows differences in the values of these relationships and confirms the general conclusion that the gills of more sluggish fish have a smaller number of larger secondary lamellae and relatively wider spaces through which the water flows.3. An electron microscope study of the toadfish secondary lamella has shown the same basic structure as in other teleost fish but the collagen layer of the basement membrane is especially thick. Also noticeable are distinct lymphoid spaces between the two epithelial layers and the presence of stages in the de...

Ovarian development in habrobracon juglandis (ashmead) (hymenoptera: braconidae). i. the origin and differentiation of the oocytenurse cell complex.

Abstract: Normal oogenesis in the adult wasp, Habrobracon juglandis, is described. Accounts are given of: (1) the mitotic behavior of oogonia and cystocytes: (2) the production of synaptonemal complexes by pro-oocytes in the germarium; (3) the formation of an egg chamber and its movement through the vitellarium; (4) the ultrastructural details of the transfer of cytoplasmic organelles to the oocyte by the nurse cells; and (5) the production of accessory muclei and protein yolk spheres in the ooplasm. Comparisons are drawn between Habrobracon and other insects with respect to: (1) the cystocyte divisions, the origin of ring canals, and the control of pro-oocyte differentiation; (2) the possible symbiotic relationships of bacteria which reside in ovarian tissue; (3) the proposed functions performed by accessory nuclei and protein yolk spheres; and (4) the synthesis of rRNA by the nurse cells.

On the endogenous control of tide-associated displacements of pink shrimp, Penaeus duorarum Burkenroad

Abstract: 1. Swimming of both postlarval and juvenile pink shrimp was recorded in current chambers in the laboratory for three days following collection from nature.2. In the apparent absence of environmental cues the animals maintained various forms of phase relationship with the tidal and diurnal cycles.3. Postlarvae manifested a pattern of swimming, markedly in phase with the semi-diurnal tide cycle. Upstream swimming took place during flood tides and downstream swimming during ebb tides. No circadian periodicity was found and the confining of their activity in nature to night-time is considered a direct response to prevailing light intensity.4. The patterns of swimming evidenced by juveniles differ depending, apparently, on some as yet undetermined aspect of the tide cycle to which they are exposed prior to collection. Individuals collected at times of new and full moon when ebb tides occur early in the evening, exhibit a different pattern of swimming from those of individuals collected at times of quarter moon...

Injury induced molting in galleria mellonella larvae

Abstract: 1. Injury to less than 1-day-old last instar larvae of Galleria induced an additional larval molt.2. 4 and 6-day-old larvae on injury delay their succeeding pupal molt.3. Injury induction of an additional molt as well as the delay of molting appear to be mediated via the brain.4. Brains from injured early last instar larvae, unlike those of the uninjured larvae, appear to possess prothoracotropic and allatotropic activities.5. During an injury induced molt the epidermal cells do not engage in DNA synthesis to the same extent as in the normal larval molts.6. The relevance of these results in the analysis of control of molting and DNA synthesis is discussed.

The life cycle of peachia quinquecapitata, an anemone parasitic on medusae during its larval development

Abstract: 1. Peachia quinquecapitata kept in sea water tanks at the Friday Harbor Laboratories were induced to spawn. The egg is 120 µ in diameter and is covered with spines 20 µ in length.2. Cleavage leads to a hollow blastula which becomes ciliated. As the cilia appear the spines become shorter and disappear.3. Gastrulation is by invagination. The planula stage is reached when the gastrula develops an apical tuft of long cilia.4. A swimming planula can be ingested by the medusa Phialidium gregarium. After ingestion the larva begins to grow and differentiate. Planulae which did not get ingested would not develop in the laboratory.5. The larvae remained endoparasitic for an average of 11 days and probably were feeding on material in the gatrovascular cavity of the host medusa.6. After 11 days the larvae became ectoparasitic and fed on the gonads of the host medusa. After an average of 31 days of ectoparasitism anemones had acquired their adult characteristics and dropped off the host medusa to become free-living.7....

Fortnightly molting and reproductive cycles in the sand-beach isopod, excirolana chiltoni

Abstract: 1. The isopod, Excirolana chiltoni is found buried in the sand in a narrow zonal band on the high intertidal beach during low tide and emerges only during high tide to swim and forage in the wave wash. The position of the zonal band during low tides bears a consultant relationship to the level of the water line during the preceding high tide. Because of this relationship the isopod zone moves up and down the beach on a fortnightly schedule which corresponds to the semi-monthly variation in tide amplitudes (the spring-neap cycle).2. Excirolana chiltoni stores considerable quantities of mineral prior to ecdysis in localized concretions of the integument (dermoliths).3. Molting takes place in two steps. First the posterior portion of the isopod including the abdomen and last 3 thoracic segments is cast which is followed by the casting of the anterior portion of the animal. Isopods which are in the process of molting can be easily recognized since the newly exposed posterior exoskeleton is fully expanded befo...

Effects of ecdysterone on the deposition of cockroach cuticle in vitro

Abstract: Quantitative studies were made of the stimulation of cuticular deposition in cockroach leg regenerates in vitro by the molting hormone ecdysterone. Preliminary experiments showed that the hormone remained active and that the tissues remained sensitive in vitro for as long as 30 days. Large doses given one week apart resulted in the production of multiple cuticles, but small doses given at shorter intervals gave a single, cumulative response. Time-dosage studies showed that the concentration of the hormone and the length of exposure make roughly equal contributions to the effect of the dose.

Isolation, partial purification and characterization of a peptide which stimulates the hindgut of the cockroach, leucophaea maderae (fabr.)

Abstract: 1. Ethanol extracts of hindguts from L. maderae contained a material that stimulated the myogenic activity of the isolated organ. Ion-exchange chromatography of the ethanol extracts resulted in a 2000-fold purification of the active residue, and thin-layer chromatography demonstrated that the activity was associated with a single ninhydrin-positive spot.2. The biological activity of the extracted substance was not affected by incubation for 3 hours with chymotrypsin. However, pronase completely destroyed the activity within 30 minutes, which suggests that the active material is a peptide. Gel filtration experiments indicated that the molecular weight is in the 400-600 range.3. The peptide was isolated from extracts of terminal ganglia, proctodaeal nerves, and heads of the cockroach but not from the foregut. Interestingly, the myogenic activity of this organ was not affected by exposure to extracts from the hindgut. The peptide was found in the two cockroaches, L. maderae and P. americana, and the grasshop...

Innervation of the lateral cilia in the mussel. mytilus edulis l.

Abstract: With the use of standard dissection, electron microscopic and histochemical fluorescence techniques branchial nerve fibers have been traced from the visceral ganglion to the ciliated epithelium of the gill in the mussel, Mytilus edulis. Hitherto underscribed nerve fibers have been shown to lie adjacent to gill filaments and to penetrate the fibrous basal lamina under the gill epithelium. Nerve fibers have been observed subjacent to postlateral. ciliated lateral and frontal cells. Homologous lateral ciliated cells have been demonstrated to be connected by septate junctions.The localization of 5-HT in the branchial nerve within the gill epithelium has been studied by means of histochemical fluorescence. Severing the branchial nerve or intramuscular injections of reserpine depleted the 5-HT in the gill. Intramuscular injections of nialamide resulted in an increase of specific fluorscence.