bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphogenetic effect of rotated skin cuffs on tail regeneration in Plethodon cinereus
Authors: Dinsmore Charles E.
Published: June 2005

As an epimorphic system, the urodele tail has much in common with the urodele limb, relative to tissue components. In an effort to elucidate potentially similar functions of the skin during regeneration, two procedures which have been shown to be highly disruptive of limb morphogenesis were performed on the tail. In the first, cuffs of tail skin were rotated 180° about the long axis of tails in Plethodon cinereus. Subsequent amputation through the rotated cuffs produced regenerates at a normal rate which were also normal in both internal architecture and skin gland distribution.

In a second series, cuffs of tail skin were rotated 90° about the dorso‐ventral axis of the tail, such that the dorsal red stripe encircled the tail. Upon amputation through the middle of the cuff, the stump skin presented an excusively dorsal surface which, nevertheless, had no effect upon the morphogenetic success of the regenerate.

These data therefore indicate that a tissue, such as skin, may be inconsistent in its morphogenetic influence among epimorphic fields within the same organism. It is not clear whether these results reflect differences in field behavior or in absolute tissue potential determined by the field of origin. A tissue hierarchy of morphogenetic influence within and among epimorphic fields is suggested as a preliminary framework within which to coordinate such information.
The anovulatory hamster: A comparison of the effects of short photoperiod and daily melatonin injections on the induction and termination of ovarian acyclicity
Authors: Stetson Milton H. , Hamilton Brian
Published: June 2005

Cyclic female hamsters were rendered anovulatory by daily subcutaneous melatonin injections (25 μg/0.1 ml oil) in 29 days or by transfer to a short light cycle, LD 6:18 (lights 1000‐1600 hrs) in 33 days. Estrous cyclicity was reinitiated in these animals in 44 or 45 days following cessation of melatonin injections or transfer to long light cycles (LD 14:10, lights 0600‐2000 hrs), respectively. Exposure of both groups to LD 6:18 after reinitiation of estrous cyclicity caused a second cessation of ovulation in 75 (melatonin group) or 61 (short light cycle group) days. Thus, although both treatments disrupted estrous cyclicity for nearly 6 weeks, this was not sufficient to induce photorefractoriness (failure to respond to short light cycles with continued estrous cyclicity). Rather, every animal responded to LD 6:18 and ceased ovulating. Melatonin‐induced anovulatory hamsters showed daily gonadotropin release patterns identical to those reported in hamsters in other anovulatory states (lactating, prepubertal, and photoinduced anovulatory hamsters); that is, peak LH and FSH release at 1700 hrs daily.
Control mechanisms of amino acid‐mediated cell volume regulation in salinity‐stressed molluscs
Authors: Pierce Sidney K. , Amende Lynn M.
Published: June 2005

The mechanisms of cell volume regulation in molluscs have been examined in detail in only a few species. While generalizations must be made with some caution until additional species have been tested, the following mechanism has emerged. When stressed with a decreased external salinity the cells of osmoconforming bivalves swell for a period of time and then recover toward the original cell volume. The volume recovery is effected by an efflux of intracellular free amino acids which act as osmotic solute. While the drop in external osmolality initiates the efflux, the duration of the efflux (restoration of normal amino acid permeability) relies on the activity of a Ca2+ – Mg2+ requiring ATPase. In addition, cell volume regulation and the amino acid efflux are accompanied by an alteration in the number of membrane associated particles per unit of membrane area. While the relationship between the ATPase activity, membrane associated particles and amino acid permeability is not yet clear, there is good evidence that the mechanism of cell volume control resides with the cell membrane in these animals.
Water compartmentalisation in insects
Authors: Machin John
Published: June 2005

Tenebrionid beetle larvae survive prolonged dehydration as well as rapid water vapor intake without exchanging solutes with their environments. Tissue water is partially regulated at the expense of the hemolymph. This presumably optimum sharing of water is brought about by the mobilization of osmotically active solutes in hydrated animals and by their storage and osmotic inactivation in dehydrated specimens. The principal solutes involved are amino acids, trehalose, sodium, and chloride.

Between moults the rectal complex generates extremely high osmotic pressures (6.7 Osm.kg−1 in Tenebrio) for the purposes of fecal dehydration and water vapor absorption. Rectal osmotic pressures run down to hemolymph levels (about 0.6 Osm.kg−1) at the onset of moulting. Tubule and rectal epithelial cells show remarkably little change in volume over this osmotic range. Volume regulation probably protects the cells from bursting and increases the efficiency of osmotic coupling between rectal lumen and the tubules during water transport. The possibility of using ions from the gut to bring about regulation in epithelial cells is discussed.
Intracranial joint movements in the Agamid lizard Amphibolurus barbatus
Authors: Throckmorton Gaylord S. , Clarke Lewis K.
Published: June 2005

Movement at the quadrate‐articular, quadrate‐squamosal, frontoparietal, and basipterygoid joints of the lizard Amphibolurus barbatus were measured from biplanar cinefluorographs taken at 60 fps while the animals were feeding on crickets. Resolution of the cinefluorographs was enhanced by placing tantulum pins into the lizard's skull at selected sites. The X, Y, and Z coordinates of the pins in each film frame were recorded using a computer assisted digitizing tablet. A computer program then calculated for each frame the angular position of the skeletal elements of each of the four joints.

The results from 29 chewing cycles show that in Amphibolurus: 1) During the opening and closing phases of most chewing cycles quadrate movement is negatively correlated with movement at the mandibular joint. Thus, as the jaws open, the quadrate rotates anteriorly tending to reduce gape and protracting the lower jaw. 2) Movement of the quadrate is independent of movement at the other intracranial joints. 3) The amount of movement at the frontoparietal joint is inconsistent with Frazzetta's ('62) model of lizard cranial kinesis. 4) In many chewing cycles, the fleshy tongue holds the prey against the upper jaws as the lower jaw is depressed. 5) During the stationary phase the quadrate tends to rotate anteriorly.

These results suggest that in Amphibolurus quadrate movement serves two functions: 1) food transport during the opening and closing phases as suggested by Robinson ('66), and 2) during the stationary phase the movement serves to increase mechanical advantage of the pterygoideus muscle as suggested by Smith ('80).
Tyrosinase subcellular distribution and kinetic parameters in wild type and c‐locus mutant C57BL/6J mice
Authors: Townsend Dewayne , Witkop Carl J. , Mattson Judith
Published: June 2005

The distribution and kinetic parameters of tyrosinase (EC 1.14.–18.1) from anagen hair follicles of the C57BL/6J mouse and several c‐locus mutants were investigated. The results showed that c‐locus mutations not only influenced the total tyrosinase activity, but the subcellular distribution as well. The kinetic parameters of tyrosinase were not influenced by the pigment mutations, suggesting that the mutations were not influencing the structure of the enzyme.
Chondrogenesis in the mutant nanomelia. Changes in the fine structure and proteoglycan synthesis in high density limb bud cell cultures
Authors: Sawyer Linwood M. , Goetinck Paul F.
Published: June 2005

High density limb bud micromass cultures, derived from individual four‐day embryos, were established in order to examine chondrogenesis in normal and nanomelic embryos. One‐ and three‐day cultures revealed no morphological differences between the two genotypes. At six days in culture, the scalloping of the cell surface observed in normal chondrocytes is not extensive in the mutant, and the extracellular matrix granules are greatly reduced in number. Differences in sulfated proteoglycan (PGS) synthesis were first detected at three days in culture when the mutant failed to synthesize cartilage‐specific PGS. The study, therefore, indicates that the mutant gene is not expressed in prechondrogenic cells.
The metamorphosis of the humeral disc of Drosophila melanogaster
Authors: Pedelty Joey , Arking Robert
Published: June 2005

The metamorphosis of the Drosophila humeral (dorsal prothoracic) disc was examined using histological procedures as well as both in vivo and in vitro culture techniques. The histological analysis was done at four developmental stages: late third instar larvae, early pre‐pupae, late pre‐pupae, and early pupae. In the late third instar larva, the disc forms a cylinder around the tracheal tubule just posterior to the anterior spiracles and consists of an outer layer of imaginal cells and an inner layer of larval cells. Evagination of the disc begins in the early prepupal stage and consists of a marked medial and posterior migration of the imaginal cells along each of the lateral tracheal trunks. By the late prepupal stage the disc has come into contact with the evaginating wing disc and has formed two structures, an anterior tubular structure which will form the second thoracic spiracle (SpTh2) and a posterior multilayered spherical structure which will form the single layered humeral callus of the adult. By the early pupal stage the humeral callus has become integrated with the rest of the thorax and the SpTh2 is contiguous with the developing adult tracheal system. In vitro cultures also showed a marked posterior migration of the imaginal cells along the tracheal trunk during the first 20–24 hours of culture which corresponds to the normal evagination period of cultured wing and leg discs. No resulting apolysis or differentiation of the cultured humeral discs was observed. Only a low level of differentiation was obtained following the in vivo culture of humeral discs. In both culture experiments, normal levels of differentiation were exhibited by the control (ventral prothoracic) discs. A hypothesis involving the possible requirement of humeral disc‐wing disc contact as a prerequisite for differentiation is presented.
Collagenase solutions induce in vitro ovulation in lobsters (Homarus americanus)
Authors: Talbot Prudence
Published: June 2005

The effect of several hydrolytic enzymes on ovulation of lobster (Homarus americanus) oocytes was studied in vitro using strips of ovarian tissue. Only ovaries which were judged by candling and microscopic examination to be close to natural ovulation were used. Ovaries were removed and cut into small, flat strips (1 cm2) and placed in either seawater (SW) or SW containing an enzyme. The number of oocytes ovulated from these strips was determined periodically over a 3–6‐hour period. Of the enzymes tested, only crude collagenase treatment produced ovulation. Highly purified collagenase was tested subsequently and found effective. Moreover, when cysteine, a collagenase inhibitor, was added to crude collagenase preparations, ovulation did not occur. These results (1) show that mature lobster ovaries will undergo in vitro ovulation in SW solutions containing collagenase, and (2) are the first demonstration that a hydrolytic enzyme may be directly involved in invertebrate ovulation. It is suggested that collagenase disrupts the thick basement membrane surrounding each follicle, thus initiating follicular rupture and subsequent extrusion of the oocyte. This technique provides a useful method for in vitro studies of lobster ovulation.
Effects of 18 weeks of daily melatonin injection on reproduction and temperature regulation in the mouse, Peromyscus leucopus
Authors: Heath Harley W. , Lynch G. Robert
Published: June 2005

Mice injected daily with 50 μg of melatonin, 12 hr after lights on, for 18 weeks, underwent gonadal regression after 4–7 weeks and reproductive recrudescence after 15 weeks. Most treated animals molted to a winter pelt after 9–11 weeks of injections, and 2 of the 10 mice experienced bouts of daily torpor after 14 weeks.
Deoxycorticosterone‐induced precocious hatching of teleost embryos
Authors: Cloud J. G.
Published: June 2005

Embryos of the teleost (Oryzias latipes) incubated at 22–23°C in medium containing deoxycorticosterone (DOC) at a concentration of 1μg/ml hatched in 11.7 days; embryos incubated under identical conditions in rearing medium alone or in rearing medium plus the steroid vehicle hatched in 22.3 and 22.2 days, respectively. The rate of development of embryos incubated with DOC was not different from that of control. Addition of DOC to the rearing medium at either 0, 4, or 8 days after fertilization resulted in a reduction of hatching time relative to the control group, but there was no significant difference in the time of hatching between these DOC‐treated groups. Increasing the rate of embryogenesis by increasing incubation temperature to 28°C resulted in a decrease in hatching time in both DOC‐treated and control embryos. The time required for hatching decreased in a dose‐dependent manner as the concentration of DOC in the incubation media increased from 0 to 1 μg/ml. Since hatching of teleost embryos is dependent upon enzymatic solubilization of the chorion, these data suggest that exogenous deoxycorticosteron induces the precocious release of hatching enzymes from the teleostean larvae.
Histochemical study of the amphibian digestive tract during normal and thyroxine‐induced metamorphosis. II. Acid phosphatase
Authors: Kaltenbach Jane C. , Wang Claire H. K. , Lipson Marcia J.
Published: June 2005

This histochemical study comprises a comprehensive overview of acid phosphatase distribution along the entire length of the digestive tract from esophagus through large intestine of growing and metamorphosing larvae and mature frogs of a single anuran species, Rana pipiens. The main site of enzyme localization throughout the length of the tube is the supranuclear area of the mucosal epithelium. However, activity of the enzyme varies markedly, not only in different locations (e.g., weak in the esophagus, strong in the small intestine), but also in different stages of larval development. During limb bud—early metamorphic stages (I—XX), activity is localized only in epithelial cells (supranuclear zone and scattered basal foci) and in glands of the stomach. Activity in these sites increases when remodeling of the digestive tract begins in the latter stages of this period. By mid‐metamorphosis (XXI—XXII), shortening of the tract has become maximal, and acid phosphatase‐positive epithelial cells have degenerated and sloughed into the lumen. In contrast, enzyme activity appears (albeit transitorily) in a new location, namely, in connective tissue thickening along the length of the tract. A similar histochemical picture can be induced precociously by thyroxine treatment. By the end of metamorphosis (XXIII—XXV), activity again appears in mucosal epithelium, but in newly differentiated adult‐type cells as well as in gastric and initially‐forming esophageal glands (the only two types of multicellular glands in the digestive tract). In adult frogs, activity remains in these sites and in scattered points (probably phagocytes) in the connective tissue; however, activity is generally weaker than in early‐stage larvae.
Developmental changes in acid proteases of the avian proventriculus
Authors: Yasugi Sadao , Mizuno Takeo
Published: June 2005

Developmental changes in acid proteases in the chicken and quail proventriculus were studied. During embryonic stages, the specific acid protease activity of both species showed a peak a few days before hatching and decreased towards the end of the incubation period. The electrophoretic patterns of acid proteases changed considerably at these stages. Within 24 hr after hatching, the activity increased about 30 times that of embryonic stages. Concomitant with this rapid increase, was a shift of electrophoretic patterns to the adult type. This shift occurred even in nonfed, hatched fowls. Electrophoretic patterns and immunochemical studies with the purified chicken and quail pepsinogens revealed that the embryonic and adult proventriculi of both species have stage‐specific and species‐specific pepsinogens.
Anaerobic metabolism in freely diving painted turtles (Chrysemys picta)
Authors: Gatten Robert E.
Published: June 2005

The degree to which painted turtles (Chrysemys picta) rely on anaerobic metabolism during unrestrained, voluntary dives was estimated by measuring the total body lactate content of turtles in the lab and in outdoor pools in summer and in winter. Experiments with forcibly submerged animals were carried out for comparative purposes. Summer turtles diving voluntarily in an aquarium at 25°C during a 5‐day experiment did not accumulate lactate (x̄ = 20 mg%). When turtles in water at 25°C were threatened and prodded but not restrained or forcibly immersed, their total body lactate content increased fourfold in 60 min. Animals forcibly submerged for 2 days at 25°C exhibited total body lactate levels up to 300 mg%. Summer turtles diving undisturbed in outdoor pools had lactate levels which were low (x̄ = 10 mg%) and which were correlated with water temperature, but not with time of day, intensity of activity in the hour prior to sampling, or the time interval since the last breath. Winter turtles forcibly submerged in an aquarium at 5°C did not exhibit a total body lactate level of 300 mg% until 2 weeks had elapsed. Winter animals diving undisturbed in an outdoor tank had lactate levels (up to 558 mg%) unrelated to time of day, water temperature (x̄ = 3.7°C), or ice thickness, but highly correlated with the duration of their hibernation (up to 67 days). These results are consistent with the hypothesis that painted turtles in nature rely on anaerobiosis when forced by a predator to remain submerged and during hibernation but not during routine diving at moderate temperatures.
The mechanism of blood flow redistribution within the carotid labyrinth of the toad, Bufo marinus
Authors: Smith D. G. , Rogers D. C. , Chamley‐Campbell J. , Campbell G. R.
Published: June 2005

The mechanism of flow redistribution in the carotid labyrinth of the toad, Bufo marinus, was investigated by exposing saline‐perfused labyrinths and cultured explants of cells from the pars capillaris or p. cavernosa to various vasoactive compounds. In addition, the presence of smooth muscle myosin and tropomyosin was demonstrated by immunofluorescence histochemistry. Explants from the p. capillaris were found to be unresponsive to all agonists tested, whereas those from the p. cavernosa were contracted by each of angiotensin, adrenaline, and acetylcholine. The same agonists always reduced the proportion of total perfusion leaving the labyrinth via the external carotid artery while simultaneously raising the overall resistance to flow through the organ. It is concluded that flow through the external carotid artery is controlled by smooth muscle cells encircling it at its base or by others surrounding the radicles to the ring vessel: Flow through the p. capillaris to the internal carotid is not controlled by β‐cells or their processes. Internal carotid flow may be controlled actively by constriction of the internal carotid itself, or passively as a consequence of altered pressure gradients within the labyrinth during constriction of the external carotid artery.
Cephalic flexure formation in the chick embryo
Authors: Goodrum Gail R. , Jacobson Antone G.
Published: June 2005

The cephalic flexure, found in all vertebrate brains, is a ventrally directed bend through the mesencephalon, and a ventral bulging and elongation of the prosencephalon. Most sources say the cephalic flexure is caused by differential growth. We have measured the changing angle of flexure through time and find that flexure occurs between chick embryo stages 10 to 15. We measured, during these stages, the lengths, thicknesses, and volumes of the floor and roof of the mesencephalon and of the prosencephalon. As expected, during flexure the mesencephalic roof elongates much more than the floor. Both roof and floor increase in thickness, and mesencephalic roof volume increases twice as much as floor volume. However, prosencephalon, which does not bend, also has differential growth between roof and floor, but the growth is taken up in complex changes of shape other than flexure. There are sufficient numbers of mitoses in the brain to account for the observed tissue growth, assuming accompanying cell enlargement. We deleted brain parts adjacent to the mesencephalon before flexure and the mesencephalon bent, so migration of cells from or to these adjacent parts to contribute to the differential growth of the mesencephalon is unlikely. We reduced cerebrospinal fluid pressure during flexure by explanting heads to the chorioallantoic membrane, or into New cultures. The mesencephalon of explanted heads bends, but the prosencephalon fails to elongate. We conclude that differential growth may be necessary for mesencephalic flexure in the chick embryo, but other factors that decide the disposition of the products of growth in space must determine the shape.
Accumulation of DNA, RNA, and protein by cultured rat embryos following maternal administration of a teratogenic dose of trypan blue
Authors: Fisher D. L.
Published: June 2005

The effect of trypan blue on the rates of DNA, RNA, and protein accumulation in rat embryos was investigated using a system of whole embryo culture. Embryos were isolated on the 10th gestational day (sperm day = Day 0) either 4 or 24 hr after maternal injection. The cultivation period was for 24 or 42 hr. The rate of DNA and RNA accumulation in the embryo following either a 4‐ or 24‐hr previous maternal treatment was significantly decreased at both 24 and 42 hr of cultivation. Protein values were significantly reduced after a 4‐hr maternal exposure, but only slightly reduced after a 24‐hr maternal exposure. No significant differences in DNA, RNA, or protein content were observed at the beginning of cultivation, following either a 4‐ or 24‐hr previous maternal treatment. The percentage of embryos establishing a visceral yolk sac circulation was greatly reduced, and this supports the conclusion that trypan blue interferes with yolk sac function. The most obvious teratogenic insults include failure of neuropore closure, retention of a dorsiflexed position, and cranial edema.
Detection of modifications in the tail of capacitated guinea pig sperm using lectins
Authors: Talbot P. , Chacon R.
Published: June 2005

The surfaces of uncapacitated, capacitated, and trypsinized guinea pig sperm have been compared using 10 lectins. A previously described assay was used to assess the degree and pattern of agglutination induced by each lectin. Our method of evaluating the agglutination pattern was significantly improved by observing assay plates with an inverted phase contrast microscope at 200 or 320 × magnification rather than with a dissecting microscope. Following in vitro capacitation or trypsinization, the agglutinability of sperm by SBA, DBA, and WGA increased, and the agglutination pattern induced by SBA, DBA, WGA, and RCA120 changed to a predominantly reticular form. These changes did not occur when sperm were incubated in Ham's F‐10, a control medium which does not support capacitation. Since binding of these lectins is inhibited by N‐acetyl‐D‐galactosamine (SBA, DBA), D‐galactose (SBA, RCA120, DBA), or N‐acetyl‐D‐glucosamine (WGA), we conclude that surface receptors containing these residues are affected by capacitation. By examining assay plates with an inverted phase contrast microscope, we were able to show that the change in the agglutination pattern for all four lectins was due to an increase in agglutinability of the principal piece of the flagellum. It is suggested that the modification of the principal piece detected by this lectin assay may be important in the development of activated motility. Results further show that capacitation and trypsin treatment affect the sperm surface in a similar manner, and are thus consistent with the idea that a trypsin‐like enzyme may modify the sperm during capacitation.
Inhibition of mouse blastocyst attachment and outgrowth by protease inhibitors
Authors: Kubo Harumi , Spindle Akiko , Pedersen Roger A.
Published: June 2005

Effects of protease inhibitors on development of mouse blastocysts and fibrinolytic activity of trophoblast were examined by growing embryos on monolayers of decidual cells in the presence of inhibitors. Nitrophenol‐p‐guanidino benzoate (NPGB) was the most effective inhibitor; 10−4 M NPGB inhibited attachment and trophoblast outgrowth by 24% and 66%, respectively, and inhibited the fibrinolytic activity of trophoblast by 86%. The effects of NPGB were reversible, as demonstrated by the embryos' ability to attach and resume normal development when transferred to NPGB‐free medium. Soybean trypsin inhibitor and ϵ‐aminocaproic acid were less effective than NPGB in inhibiting blastocyst development. When 10−4 M NPGB and 350 μg/ml of soybean trypsin inhibitor were added together, blastocyst development and fibrinolytic activity were inhibited more severely than when either inhibitor was added alone. We suggest that at least two types of proteolytic activities in mouse blastocysts are involved in implantation, attachment requiring trypsin‐like activity, and trophoblast outgrowth requiring both plasminogen activator and trypsin‐like activity.
Lens of the hydromedusan Cladonema studied by SDS gel electrophoresis and immunofluorescent technique
Authors: Weber Christian
Published: June 2005

The lens of the medusa Cladonema radiatum contains protein components. Three different protein fractions were found in SDS‐polyacrylamide gels. Each sample used for electrophoresis contained extracts of 60 ocelli of Cladonema. Direct comparisons show correspondence between the electrophoretic mobilities of the three fractions and bands of amphibian and bovine lens proteins and antigen‐antibody reaction of bovine lens antibodies to Cladonema lens crystallins.
Epidermal cell migration during attempted closure of skin wounds in the adult newt: Observations based on cytochalasin treatment and scanning electron microscopy
Authors: Donaldson Donald J. , Dunlap Mary K.
Published: June 2005

Epidermal closure of skin wounds on newt limb explants was inhibited to equal degrees by cytochalasins B,D and dihydiocytochalasin B (H2CB). The cytochalasin solvent, dimethylsulfoxide (DMSO), had no effect on migration at the low concentration present in the cytochalasin and control solutions. However, a 5% DMSO solution completely blocked mobility. Wounds on limb explants and limbs in situ responded similarly to cytochalasin treatment. Inhibition of migration by H2CB was reversible even when protein synthesis was reduced by 73%. Scanning electron microscopy of wound epithelium migrating on nucleopore filters revealed extensive lamellipodia on marginal cells and the first row of submarginal cells. Cytochalasin treatment produced plications in the upper surface and free edge of the normally smooth lamellipodia. This disturbance of the free edge revealed focal adhesions with the substratum. The fact that migration was inhibited by CD and H2CB (two cytochalasins with an affinity for contractile proteins but without some of the side effects of CB) leads us to conclude that epidermal cells utilize actin or actin‐like proteins during wound closure. These results increase the likelihood that tissue cells of all types, whether in vitro or in vivo, share a common biochemical basis for cell movement.
Shunts in the gill filament in tadpoles of Rana temporaria and Bufo bufo (amphibia, anura)
Authors: De Saint‐Aubain Marie Louise
Published: June 2005

Vascular shunts in the gill filament have been discovered in larvae of Rana temporaria and Bufo bufo by means of Indian ink and latex injections. These shunts offer a nonrespiratory flow path to the dorsal aorta. They are morphologically different from the shunts seen in urodeles. Contractility of the shunts is indicated and influence on gill blood flow proposed.
1‐Methyladenine induced stimulation of protein phosphorylation and Na+ pump does not require the presence of the nucleus
Authors: Doree M.
Published: June 2005

1‐Methyladenine, which induces meiosis reinitiation in starfish oocytes, stimulates 32P incorporation into proteins and activates the ouabain‐sensitive Rb+ influx in anucleated fragments obtained from full‐grown Marthasterias glacialis oocytes. This shows that hormone‐induced stimulation of protein phosphorylation and Na+ pump does not require the presence of the nucleus. Stimulation of protein phosphorylation is, however, delayed and reduced with respect to intact oocytes.
The role of oxygen and light in guiding “photoaccumulation” in the Paramecium bursaria‐Chlorella symbiosis
Authors: Cronkite Donald , van den Brink Sue
Published: June 2005

Groups of Paramecium bursaria, containing the symbiotic alga Chlorella, aggregate in a “light trap” – a spot of light in a dark field. Cell populations conform to the shape of the light trap because (1) individual cells in the light either move slowly or not at all; and (2) individuals also, upon leaving the spot of light, undergo a short avoiding reaction – a step‐down response – changing the direction of their forward movement back toward the light. Upon removing the light source, cells become more motile and disperse from the area of the light trap. A similar result is produced in the light by the addition of 10−6 molar 3‐(3,4‐dichloropheny1)‐1,1‐dimethyl urea, (DCMU), which completely inhibits the photosynthetic evolution of O2 by Chlorella‐bearing P. bursaria. However, in the presence of DCMU the step‐down response is not affected. We conclude that P. bursaria accumulates in light through two mechanisms: an “aeroreceptor” senses changes in concentrations of O2 and a “photoreceptor” senses decrease in light intensity. Additionally, methods of quantifying photobehavior have been developed and have been used to show that blue light is a more effective inducer of step‐down photobehavior than is red light. Further studies are underway to examine the roles of ions and of the symbiont in mediating the response of P. bursaria to light.
Improved visualization of apical vesicles in chloride cells of fish gills using an osmium quick‐fix technique
Authors: Bradley Timothy J.
Published: June 2005

Quick‐fixation with buffered osmium is a well established technique for fixing rapid forms of cell motility, e.g., metachronal ciliary beat. One proposed mechanism of salt transport in the gills of saltwater fish is a vesicular shuttle in the apical tubulovesicular system of gill chloride cells. We decided to use the osmium quick‐fix technique to see if rapid fixation causes modification of observed gill ultrastructure. Gill chloride cells from two species of fish, Fundulus heteroclitus and Poecilia reticulata, were examined ultrastructurally under two conditions of fixation: (1) Conventional fixation in glutaraldehyde followed by osmium or (2) quick‐fixation for 20 seconds in osmium tetroxide buffered with Na cacodylate followed by conventional fixation. Following osmium quick‐fixation, the ultrastructure of the apical tubulovesicular system is substantially different, such that more vesicles are seen in the cortical region and membrane fusion events between vesicles and the apical membrane are much more prevalent. The appearance of other portions of the chloride cell, e.g., mitochondria, tubular reticulum, cell junctions, was identical under the two conditions of fixation. These results suggest that a rapid vesicular shuttle is present in the chloride cell apex. A model indicating how such a shuttle might be instrumental in transepithelial ion transport is presented and evaluated. We currently lack sufficient information to accept or reject any of the current models of ion transport. It is anticipated that the osmium quick‐fix technique will serve as a useful tool in further studies of the morphology, movements, and function of apical vesicles in fish chloride cells.
Induction of budding in a nonbudding mutant of Hydra viridis as a result of grafts using wild type tissue with varying compositions of interstitial and nerve cells
Authors: Novak Patricia L. , Lenhoff Howard M.
Published: June 2005

In order to determine if the interstitial cell or its derivative nerve cells play a role in inducing buds, experiments were conducted in which grafts using wild type tissue of varying cell compositions were made with the nonbudding mutant. Wild type specimens of H. viridis lacking i‐cells but possessing nerve cells as well as lacking both i‐cells and nerve cells were prepared using various combinations of hydroxyurea and colchicine. Wild type tissue lacking i‐cells but possessing nerve cells stimulated the mutant tissue to bud. Wild type tissue without i‐cells and nerve cells, however, was unable to induce budding. Chimeric hydra consisting of epithelial cells from wild type hydra and i‐cell lineages from the mutant reproduced asexually by budding as do wild type epithelial animals repopulated with wild type i‐cells. Chimeric hydra, however, were unable to induce budding when grafted back to the mutant. From the results of these experiments dealing with properties and induction of budding, we propose that nerve cells can influence adjacent epithelial tissues to form buds.
Development of swimming behavior in sea urchin embryos. II
Authors: Maruyama Y. K.
Published: June 2005

The previous study has revealed that sea urchin prehatching embryos exhibited either clockwise or counterclockwise spin on the animal—vegetal axis, whereas the hatched embryos showed only counterclockwise spin. This behavioral change at hatching was analyzed in the present study by testing the “mechanical interaction hypothesis” proposed in the previous paper. Observations of the spinning behavior have been made of (1) embryos without the fertilization membrane (denudation experiment), (2) those embedded in fibrin gel at the prehatching or free‐swimming stages (maintenance or induction experiments), and (3) those liberated into seawater after the embedding (liberation experiment). The results have provided evidence to support the hypothesis that the duality of the spinning behavior in the prehatching embryos is due to a mechanical or hydrodynamic interaction between the cilia and the inner surface of the fertilization membrane, independent of the developmental stage of the embryo proper. Thus it is concluded that the change in the spinning behavior of embryos after hatching is brought about solely by their release from the fertilization membrane.
Fine structure of the micropylar apparatus of the chum salmon egg, with a discussion of the mechanism for blocking polyspermy
Authors: Kobayashi Wataru , Yamamoto Tadashi S.
Published: June 2005

The micropylar apparatus of the eggs of the chum salmon, Oncorhynchus keta, was examined by scanning and transmission electron microscopy. The apparatus consists of a funnel‐shaped vestibule, from the bottom of which extends the micropylar canal, about 5 μm, in diameter. The canal traverses the entire zona pellucida interna of the egg envelope, about 30 μm in thickness. At its inner end, the diameter of the micropylar canal is the same as the width of the sperm head, about 2 μm. The lower portion of the canal is occupied by a conspicuous outgrowth of the ooplasmic surface, 3–10 μm in length.

The first contact of the ooplasmic surface with a fertilizing spermatozoon occurs at the apex of the outgrowth in the micropylar canal. The surface of the outgrowth undergoes changes immediately after penetration by a fertilizing spermatozoon that prevent supernumerary spermatozoa from penetrating the ooplasm. As the formation of the perivitelline space takes place, the outgrowth withdraws from the micropylar canal. Supernumerary spermatozoa, however, cannot enter the perivitelline space and are eliminated from the canal lumen. In addition, the micropylar canal decreases in diameter at the region near its inner end and forms a mechanical barrier to the passage of supernumerary spermatozoa.
Only acrosome‐reacted spermatozoa can bind to and penetrate zona pellucida: A study using the guinea pig
Authors: Huang T. T. F. , Fleming A. D. , Yanagimachi R.
Published: June 2005

We have examined the behavior of guinea pig spermatozoa towards the guinea pig zona pellucida in vitro. Experiments were designed to determine whether the state of capacitation or the acrosome reaction determined the ability of the spermatozoa to attach to the zona. Freshly collected cauda epididymal spermatozoa are acrosome‐intact (AI) and, by definition, uncapacitated. These cells could not attach (at least persistently) to the zona. We then sampled spermatozoa from a progressively capacitating population at various time intervals. At no point did AI spermatozoa from such samples have the ability to attach to the zona. On the other hand, acrosome‐reacted (AR) spermatozoa that appeared in increasing number during this capacitation period rapidly and firmly adhered to the zona. Adhesion by AR spermatozoa prepared in several ways culminated in successful zona penetration and fertilization of the ovum. The data provide unequivocal evidence that AR guinea pig spermatozoa attach to zonae and fertilize the ova. We find no evidence that AI spermatozoa firmly attach or bind to the zona, regardless of their state of capacitation.
Formation of the block to polyspermy in ascidian eggs: Time course, ion requirements, and role of the accessory cells
Authors: Lambert Charles C. , Lambert Gretchen
Published: June 2005

The eggs of Ascidia nigra become incapable of fertilization by a second sperm about 21 seconds after fertilization by the initial sperm. Removal of the follicle cells slows the rate and lowers the percentage of fertilization but has no influence on the block to polyspermy. Similar numbers of sperm are found in the perivitelline spaces of polyspermic and monospermic eggs subjected to high sperm concentrations, suggesting that the block to polyspermy is at the egg surface. Like other polyspermy blocks in marine invertebrates, that of ascidians requires Na+ for formation.
Electrophoretic protein patterns in fast and slow muscles of the lobster, Homarus americanus
Authors: Meiss Dennis E. , Lyerla Timothy A. , Cain Scott , Costello Walter J.
Published: June 2005

The protein arrays of the claw and abdominal muscles of the lobster Homarus americanus were examined by sodium dodecyl sulfatepolyacrylamide gel electrophoresis. The gel protein patterns revealed consistent differences in several major bands that could be correlated with the physiological properties of the muscle. Fast‐type muscle, independent of innervation, showed a common protein pattern distinct from the slow muscles, which had a common pattern of their own. These results suggest that functional properties of crustacean muscle fibers are expressed in their protein composition.
Transport‐related ATPases as probes of tissue function in three terrestrial crabs of Palau
Authors: Towle David W.
Published: June 2005

Distribution and properties of Na+ + K+‐dependent ATPase and Cl−/HCO‐activated ATPase were used as probes of tissue function in relation to salt and water regulation in three terrestrial crabs, Cardisoma carnifex, Gecarcoidea lalandii, and Birgus latro. Of the three predominant tissues in the branchial chamber, gill consistently exhibited highest specific activity of both enzymes, indicating that terrestrial crabs may use ion regulation by the gills as an important mechanism of salt and water balance. Branchial epithelium lining the cavity does not appear to be important in regulation of monovalent ions, although it is highly specialized in B. latro as a respiratory organ. Pericardial sac also lacks the biochemical machinery for active salt and water uptake. Antennal gland of all three species showed high activity of Na+ + K+‐ATPase, perhaps facilitating water retention by that organ. Na+ + K+‐ATPase activity of intestine showed wide species‐related variation, and was enhanced in B. latro exposed to freshwater. The gill of B. latro maintained constant high activity of the Na+ + K+‐ATPase, irrespective of environmental conditions.
Production of chimeras in the deer mouse Peromyscus maniculatus bairdi
Authors: Klein Maryrose S. , Markert Clement L.
Published: June 2005

The production of intraspecific chimeras in the deer mouse, Peromyscus maniculatus, was undertaken to make mammals of another genus useful for studies of reproductive biology, developmental genetics, and embryonic development. Peromyscus was generally amenable to the same experimental procedures and techniques employed in producing Mus musculus chimeras. We found that Peromyscus embryos could be successfully manipulated and cultred in vitro. Fertilized eggs and 2‐cell embryos continue cleavage when cultured in vitro and form morulae and blastocysts. Almost all the 4‐ and 8‐cell embryos that were aggregated remained together and developed, after 1 day of culture in vitro, to form chimeric morulae and blastocysts. However, certain changes had to be made in the chimera‐making procedure employed for M. musculus to accomodate some of the differences in reproductive physiology and behavior of Peromyscus. The methods for the preparation of donor females and of foster mothers had to be modified in order to obtain embryos on the scheduled day of the experiment, and to obtain pseudopregnant foster mothers. With these revised precedures, three P. m. bairdi chimeras were produced. Two are healthy fertile males displaying chimerism in the fur. The other chimera was delivered dead at 17 days of gestation, after its foster mother died. Chimerism was detected in the retinal epithelium of the eye by the presence of black pigmented patches contributed by the wild‐type genotype, and unpigmented patches, contributed by the blonde mutant genotype. By developing the procedures enabling the production of the first chimeras in this genus, we have demonstrated that Peromyscus is a suitable animal for exacting technical manipulations in the laboratory.
The molt cycle of the crab, Cancer antennarius: Computer‐aided staging
Authors: Spaziani Eugene , Ostedgaard Lynda S. , Vensel William H. , Hegmann Joseph P.
Published: June 2005

Some stages of the molting cycle are not readily discernible in large crustaceans, if classical staging methods are employed. Alternative methods were explored. A statistical classification procedure used in numerical taxonomy, multiple discriminant analysis, was applied to 26 variables measured in crabs (Cancer antennarius) of known stages. Variables were tested systematically for discriminant capacity singly, in pairs, and in linear combinations. A set of 12 variables was found that discriminates stages accurately and efficiently. The variables are physical in character, highly accessible, and easily measured; the required data can be collected routinely before, during, or after an experiment. The method can be applied to staging other species.
Macromolecular synthesis during oral regeneration in the Ciliate Condylostoma magnum: Effects of different inhibitors (II). Protein synthesis and microtubule assembly
Authors: Bohatier Jacques
Published: June 2005

Macromolecular syntheses essential to the regeneration of a new oral apparatus in the Ciliate Condylostoma magnum were studied by use of specific chemical metabolic inhibitors. In the present paper we have tried to elucidate the question of protein synthesis required for cytodifferentiation and the problem of microtubule assembly. Postperistomial fragments were exposed to cycloheximide and colchicine, immediately, or at various times after cutting. Protargol‐impreg‐nated cells were observed with a light microscope to control the cytological effects of inhibitors. Continuous exposure to high concentrations of cycloheximide (250 μg/ml) or colchicine (700 μg/ml) completely inhibits oral regeneration. Once oral regeneration is initiated, results differ depending on the time when the drugs are added. Applications during the course of morphogenesis suggest that the different steps of oral regeneration, (1) kinetosome proliferation, (2) adoral, and (3) paroral ciliature differentiation and stabilization, (4) invagination of feeding organelles, (5) formation of food vacuoles, (6) elongation and renodulation of the macronucleus are all dependent upon protein synthesis and are colchicine sensitive. On the other hand we can show that stabilization of new oral ciliature occurs when the typical pattern is restored (transverse kinetosome rows on the left side of the oral area, longitudinal rows on the right side). Then, we can define in Condylostoma, two “stabilization points”, one for adoral ciliature and later another for paroral ciliature. This stepwise stabilization is temporally correlated with the times at which these two structures acquire their definitive organization.
Cyclic AMP concentrations during distal regeneration in Hydra oligactis
Authors: Hill Susan K. , Lesh‐Laurie Georgia E.
Published: June 2005

Removal of the highly innervated hypostome and tentacle regions of Hydra initiates physiological changes that result in selective cellular differentiation and regeneration. Evidence has been presented previously that neural products direct this selective cell differentiation, although the mechanism(s) by which this occurs is not known.

This investigation has demonstrated a predictable pattern of cyclic AMP activity following subhypostomal amputation. This pattern of activity demonstrates two major peaks during the first 42 hours of regeneration. This first peak occurs at approximately 12–20 hours of regeneration, at a time when macromolecular synthesis studies showed unremarkable activity. The second activity period occurs in close association with significant increases in DNA and RNA synthesis.
Activation of amino acid accumulation in delayed implantation mouse blastocysts
Authors: van Winkle Lon J.
Published: June 2005

Delayed implantation blastocysts remained in a diapausing‐like state when incubated in Na+‐depleted (55 mM) medium. Accumulation of radioactive amino acids remained low when embryos were in low Na+ medium, but increased in the manner characteristic of these embryos when placed in high (124 mM) Na+ medium. Differentiation of blastocysts was apparently arrested in medium containing only 55 mM Na+ since no progress toward formation of trophoblastic outgrowths was made in this medium even when it contained all other compounds required for this process. Low Na+ may prevent uptake of amino acids, such as lysine, essential to outgrowth formation. Accumulation of lysine was Na+‐dependent in blastocysts even though this amino acid is not transported via a Na+‐symport system in most cell types. Glucose deprivation did not affect the increase in the capacity of delayed implantation blastocysts to take up amino acids when incubated in high Na+ medium, and glucose accumulation was not Na+‐dependent. The capacity of delayed implantation blastocysts to take up amino acids was inversely related to the time before these embryos began forming outgrowths in vitro. The latter process occurred more rapidly if diapausing blastocysts had been stimulated in utero by injecting overiectomized mice with progesterone and estrogen. However, these hormones slowed outgrowth formation slightly when present in the culture medium in vitro.
Arylsulphatase activity in seminal plasma from fowl semen
Authors: Droba Maria , Droba Bogusław
Published: June 2005

Arylsulphatase from seminal plasma of fowl was characterized with a crude enzyme preparation using nitrocatechol sulphate as the substrate. Arylsulphatase activity was considerable and showed a shift of pH optimum dependent on the incubation time and on the presence of sulphate and chloride ions. The electrophoretic pattern of enzymic activity showed three separate bands. It is concluded that both arylsulphatases A and B may be present in seminal plasma.