bluuebunny/crossref_metadata_2025 huggingface dataset:
Calcium transport in crayfish gastrolith disc: Morphology of gastrolith disc and ultrahistochemical demonstration of calcium
Authors: Ueno Masaki
Published: June 2005

After induction of premolt conditions in crayfish by injection of the molting hormone (β‐ecdysone), gastrolith disc tissue was examined electron‐microscopically. The following four types of epithelial cells were morphologically distinguished, synchronized with the stage of gastrolith growth. Type 1 cells, containing abundant mitochondria with microtubules extending from apical to basal side, are abundant during the intermolt period. Type 2 cells, highly vacuolated and containing hypertrophied mitochondria, are involuting and abundant during the period of gastrolith formation. Type 3 cells, having fine microvilli at the apical portion, begin to appear at the large gastrolith period. Type 4 cells, containing many irregular vesicles at the apical portion with mitochondria present in basal infoldings, are seen when the gastrolith formation is completed.

These observations led to the assumption that the four types of cells represent the whole life cycle of an epithelial cell, starting from type 3 through type 4, type 1, and ending at type 2 involuting cells.

From ultrahistochemical demonstration of calcium, the presence of calcium was nearly restricted to the hypertrophied mitochondria of type 2 cells, which eventually slough off to the gastric lumen.

These findings suggest a unique calcium transport system: The hypertrophied mitochondria accumulate a large amount of calcium and supply calcium to the gastrolith.
Penetration of zona‐free hamster eggs in vitro by goat spermatozoa preincubated in the reproductive tract isolated from a maturing gilt
Authors: Kim C. I. , Niwa K. , Imai H. , Iritani A.
Published: June 2005

When goat spermatozoa were preincubated for 5‐5.5 hr in the isolated uterus and oviduct from a maturing gilt, they developed the ability to penetrate zona‐free hamster eggs in vitro. Overall penetration rates were 17% and 0%, respectively, 1 hr after insemination, and these increased to 59% and 54% 2 hr later. The penetration rates were not improved by incubation longer than 2 hr after insemination up to 5 hr. Goat spermatozoa preincubated for 5 hr in a m‐KRB solution with or without goat serum penetrated zona‐free hamster eggs with difficulty. The results suggest that a functional change in the ability of goat spermatozoa to penetrate zona‐free hamster eggs may occur in the reproductive tract of different species.
Relationship between gill Na+,K+‐activated ATPase activity and osmotic stress in the plecopteran nymph, Paragnetina media
Authors: Kapoor N. N.
Published: June 2005

A relationship between osmotic stress and gill Na+,K+‐activated ATPase was observed in plecopteran nymphs acclimated to diluted creek water and a hypertonic medium. An increase of 84% in diluted creek water is presumably related to an active uptake of sodium ions from the hypotonic medium. Whereas a 21% decrease in the enzyme activity may be related to the morphological changes in the specialized cells in the gills. The Na+, K+‐activated ATPase activity was also compared with the Malpighian tubules and the rectum. The highest ATPase activity of 32.6 ± 2 μmoles Pi mg protein−1 30 min−1 was observed in the Malpighian tubules. The activity in the gills (19 ± 1.2 μmoles Pi mg−1 30 min−1) was slightly lower than the rectum. Since the ATPase activity in the gills is quite high, the gills can be considered to play an active role in hyperosmotic regulation in plecopteran nymphs.
Ultrastructure of primary mesenchyme cell ingression in the sea urchin Lytechinus pictus
Authors: Katow Hideki , Solursh Michael
Published: June 2005

The ultrastructural changes associated with primary mesenchyme cell formation in the sea urchin Lytechinus pictus were studied by transmission (TEM) and scanning electron microscopy (SEM). Early during ingression, one can recognize about 30 presumptive primary mesenchyme cells, which form a ring around eight central cells, located at the apex of the vegetal pole. The first steps involve the loss of the basal lamina in the vegetal plate region and the loss of cilia from the 30 presumptive primary mesenchyme cells. These cells then elongate into bottle‐shaped cells which have a bulbous, appendage‐free basal end that protrudes into the blastocoel, and a thin neck region that forms numerous apical cell processes. Longitudinally oriented microtubules are observed in the peripheral cytoplasm in the neck region of the bottle‐shaped cells and in the adjacent cytoplasm of closely adherent neighboring non‐mesenchymal blastomeres. After the disappearance of apical junctions, the neck regions of the bottle‐shaped cells shorten, resulting in the transposition of the cells into the blastocoel as rounded primary mesenchyme. Mesenchyme cell displacement results in the temporary formation of fenestrae in the blastular wall, which are filled in by apical cell processes that extend from neighboring blastomeres. These morphological changes have several features in common with other examples of cells which exit from epithelia and are consistent with a morphological sequence involving the relaxation of the basal cytoplasm of the presumptive primary mesenchyme cells, followed by their active elongation and lateral compression by adjacent cells.
Regeneration in larvae and juveniles of the mud crab, Rhithropanopeus harrisii
Authors: McConaugha John R. , Costlow John D.
Published: June 2005

Both the megalopa and juvenile stages of the mud crab Rhithropanopeus harrisii were shown to have regenerative abilities following limb autotomy. The number of individual crabs initiating regeneration was directly dependent on the number of limbs autotomized and the stage of the molt cycle when autotomy occurred. The number of individuals undergoing regeneration and the proportion of the molt cycle when regeneration could be induced increased in later stages. Regeneration was associated with a significant delay in the molt cycle, while non‐regenerating individuals displayed a trend toward an accelerated molt cycle. The duration of the delay was independent of the number of limbs lost. It is hypothesized that this delay is due to an inhibition of ecdysone synthesis. This results in resetting the molt cycle to the intermolt or premolt stage.
The internal clock of reaggregating embryonic sea urchin cells
Authors: Spiegel Evelyn , Spiegel Melvin
Published: June 2005

The presence of micromere “a clock” during early cleavage in sea urchin embryos has been shown by several investigators. The suggestion that an internal clock may be operative in later developmental stages up to the pluteus is presented in this study.

The development of reaggregating Arbacia cells was followed from dissociation at the 16‐cell stage to pluteus formation, using scanning electron microscopy. After 7 hr of development, the reaggregates were dissociated a second time and were again able to develop into plutei. The morphological development of both reaggregations appears to be identical. In addition, embryos of both reaggregations developed at the same rate as control embryos. Differences in the cells of the first and second dissociations as compared to controls are described, as is the ability of reaggregating cells to catch up to controls during early development. Possible reasons for their ability to make up for lost time are discussed, including non‐randomness of cell behavior, lack of dedifferentiation and the presence of an internal clock.
Regulation of expression of the ribosomal RNA cistrons in Ilyanassa embryos: Nucleolus‐like bodies and nucleologenesis
Authors: Naus Christian G. , Kidder Gerald M.
Published: June 2005

In embryos of the gastropod, Ilyanassa obsoleta, ribosomal RNA (rRNA) synthesis first becomes detectable using sucrose gradients at the end of cleavage (by 24 hours post trefoil at 19°C; the trefoil stage is characterized by maximal extension of the third polar lobe, in association with first cleavage). The nuclei of early embryos, however, contain several prominent nucleolus‐like bodies (NLBs) from the 2‐cell stage onward. Investigation of these NLBs ultra‐structurally and cytochemically has led to a model for nucleologenesis and the regulation of expression of the rRNA cistrons during cleavage. Throughout the cleavage period, NLBs consist of homogeneous, spherical accumulations of 5–8 nm diameter fibrils. By 18 hours post trefoil, they have become extensively associated with chromatin. By 22 hours post trefoil there are definitive, chromatin associated nucleoli which have a distinct, 15–25 nm granular component surrounding and intermingling with a matrix of 5–8 nm fibrils. This period marks the beginning of a reduction in the number of NLBs per nucleus, until most post‐gastrula nuclei contain only one or two definitive nucleoli. Both NLBs and nucleoli stained selectively with bismuth, which Locke and Huie ('77) consider to be specific for basic proteins within the nucleolus. In contrast, a silver staining technique (Bloom and Goodpasture, '76) selective for active nucleolus organizers stained nucleoli of post‐gastrula embryos but not NLBs of mid‐cleavage embryos. Electron microscope autoradiography showed the incorporation of 3H‐uridine into NLBs beginning in late cleavage, just prior to the appearance of a granular nucleolar component. The agranular NLBs present in cleavage nuclei appear, therefore, to be precursors of the fibrillar matrix of the nucleoli which eventually replace them. This transition is coincident with the activation of rRNA gene expression as NLBs associate with chromatin towards the end of cleavage.
The effect of the substrate on tadpole tailfin epidermal cells in vitro
Authors: Udoh Paul , Derby Albert
Published: June 2005

The behavior of epidermal cells was studied by employing two in vitro systems in which reepithelialization occurs: the single explant system and the fused system. Single explants (4–5 mm2) are prepared from the tailfins of R. catesbeiana tadpoles and cultured in Hank's balanced salt solution at 22°C. The fused system is prepared by placing single tailfin pieces on either side of a tailfin piece that was stripped of its epidermis. These tissues are placed onto a Millipore filter and cultured in Hank's at 22°C. In these experiments one can study the effect of the substrate, core vs a collagenous basement membrane, on the behavior of epidermal cells during reepithelialization.

The results of these experiments demonstrate that there are differences in the behavior of epidermal cells in these two systems. In the fused system wound closure is associated with the occurrence of “contact inhibition,” the cessation of further cell migration, and the presence of an epidermal layer that exhibits a normal cytoarchitecture in the wound area. However, in the single explant system, wound closure occurs but an overaccumulation of epidermal cells in the wound area, “capping,” is observed.
Prevention of in vitro fertilization of canine oocytes by anti‐ovary antisera: A potential approach to fertility control in the bitch
Authors: Mahi Cherrie A. , Yanagimachi Ryuzo
Published: June 2005

Antisera raised against canine ovaries were found to induce light scattering of the surface of the egg zona pellucida even when diluted 10,000 times, and to delay digestion of the zona by pronase.
The development of the posterior musculature of the embryonic chick wing
Authors: Searls Robert L.
Published: June 2005

It has been proposed that movements of cells at the base of the developing wing cause the wing to rotate (Yander and Searls, '80a,b). It was suggested that rotation of the wing caused the dorsal muscle mass of the wing bud to become the posterior musculature of the proximal part of the wing. Rotation of the wing was investigated by grafting dorsal myogenic tissue from a wing labeled with tritiated thymidine into the dorsal myogenic region of an unlabeled wing in its original orientation. Grafts were made both with and without their original ectoderm. The location and shape of the graft was recorded at the time of the operation. After a period of growth and morphogenesis, the host wing and adjacent body wall were fixed, sectioned, and prepared as autoradiographs. The location of the grafted cells was determined by reconstructing the host wing and adjacent body wall. It was found that the graft increased in length on the axis of the humerus and did not increase rapidly on any other axis. During stage 25, a deep groove began to form ventral to somite 19 because of ventral and cranial movement of the lateral body wall proximal to the base of the wing. The distal border of this groove was recognized as the posterior margin of the proximal wing. If the graft extended to the base of the wing, the graft participated in the formation of this groove. Grafted cells on the distal border of the groove were on the posterior surface of the wing at the level of the humerus.
In the absence of protein, estradiol suppresses meiosis of porcine oocytes in vitro
Authors: Racowsky Catherine , McGaughey Robert W.
Published: June 2005

The effect of estradiol on the spontaneous maturation of porcine oocytes was investigated. Cumulus‐enclosed (intact) and cumulus‐free (denuded) oocytes were cultured in the presence of estradiol‐17β (0 to 10μg/ml) in a chemically defined bicarbonate‐buffered medium that contained either dextran or BSA, or in a complex Hepes‐buffered medium that was supplemented with serum. After 24 hr, chromatin spreads were prepared and meiotic maturation was scored. The biochemical integrities of the cumulus cells were assessed by determination of the estradiol and progesterone content of spent media after culture of intact oocytes in the presence of 0.5 × 10−6 M testosterone and 10 μg/ml follicle‐stimulating hormone.

Estradiol did not significantly affect the onset of maturation of either intact or denuded oocytes that were cultured in medium containing either BSA or serum. In serum‐supplemented medium, however, the progression of maturation beyond metaphase I was significantly affected by the steroid in a dose‐dependent manner. The steroid significantly inhibited the release from meiotic arrest of both types of oocyte cultured in medium supplemented with dextran. Supplementation of all media with testosterone and FSH significantly stimulated the synthesis of estradiol by the cumulus cells, compared with that of control groups. The synthesis of progesterone, however, was significantly stimulated by testosterone and FSH only in the BSA and serum‐supplemented media. It is concluded that exogenous estradiol has the capacity to arrest meiosis in vitro but that this capacity can only be expressed if no exogenous protein(s) is present. In the absence of exogenous protein, progesterone synthesis by the adherent cumulus cells is minimal.
Diurnal rhythms in developing ducts of the mouse mammary gland
Authors: Berger J. J. , Daniel C. W.
Published: June 2005

DNA synthesis (LI) and mitotic activity (MI) were studied at different times of the day in the developing mammary gland end bud of the postnatal mouse. Both LI and MI displayed a clear diurnal variation. Animals studied at the middle of the 12‐hr dark cycle showed a LI 2.1–2.6 times that of the tissue from the middle of the 12‐hr light cycle. Intermediate values were obtained in tissue sampled midway between these extremes. Mitotic activity was studied 4 hr after the peak and trough of LI and exhibited a corresponding variation. These diurnal variations may be related to cyclic changes in secretion of pituitary hormones or other peptide growth factors, but variation between individual end buds in the same animal is more likely a result of morphogenetic interactions at the tissue level.
Actomyosin components of the asymmetric claw closer muscles of californian snapping shrimp
Authors: Leferovich John M. , Stephens Philip J.
Published: June 2005

The dimorphic claws of the Californian snapping shrimp, Alpheus californiensis, contain an opener and a closer muscle. The closer muscle in the smaller pincer claw is composed of fibers with short and intermediate sarcomere lengths, whereas the closer muscle in the larger snapper claw is composed of fibers with long sarcomeres. Electrophoretic analysis of actomyosin extracts from the closer muscle in each claw revealed some common components. However, the snapper contains two additional components with molecular weights of 25 and 100 daltons.
Polar plasm and pole cell formation in an insect egg developing with or without follicular epithelium: An ultrastructural study
Authors: Junquera Pablo
Published: June 2005

After X‐ray irradiation, it is possible to obtain follicles and eggs of the gall midge Heteropeza pygmaea lacking the follicular epithelium. These “naked” eggs are able to develop up to the blastoderm stage but remain spherical instead of assuming an elongated shape. Polar plasm and pole cell formation have been studied at the ultrastructural level to investigate the role of the follicular epithelium and of the egg shape in the establishment of egg polarity and in the differentiation of germ line cells. It is shown that the normal egg shape and the follicular epithelium are not needed for the establishment of the anterior‐posterior polarity, as it is manifested by the polar plasm. Moreover, the polar plasm appears at that part of the naked eggs that is at the opposite side of the nurse chamber. Naked eggs are also able to form pole cells in a sequence of events, which strongly resembles that of pole cell formation in normal eggs. These events are described and discussed; they include the changes in the morphology of the polar granules and their association with other organelles during development, the shifting of the polar plasm towards an approaching cleavage nucleus, the cleavage of the first pole cell, and the appearance of pole cell‐specific nuclear lamellae.
Occurrence and function of prairie rattlesnake mouth gaping in a non‐feeding context
Authors: Graves Brent M. , Duvall David
Published: June 2005

Mouth gaping by rattlesnakes has been observed primarily during feeding sequences and interpreted as functioning to stretch the jaw in preparation for swallowing prey. However, exposure of prairie rattlesnakes to conspecific sociochemical signals elicited increased mouth‐gaping actions, and the latter were sequentially followed by tongue flicks at significant levels. Mouth gaping may function to facilitate vomeronasal olfaction independent of jaw‐stretching effects.
Monoclonal antibody against mouse sperm blocks a specific event in the fertilization process
Authors: Saling P. M. , Raines L. M. , O'rand M. G.
Published: June 2005

Hybridoma cell lines were produced by PEG (polyethylene glycol)‐induced fusion of myeloma cells (NS‐1/X63 Ag 8) with dispersed spleen cells from a Balb/c male mouse immunized syngeneically with homogenized Balb/c testis. Indirect immunefluorescence on mature (cauda epididymal) mouse sperm was employed as the primary screening assay. This procedure allowed the immediate identification of hybridomas which produce monoclonal antibodies of interest with respect to the fertilization process. One hybridoma cell line, M29, secretes an antibody of the IgM class that localizes to the equatorial segment of the mouse sperm head. This antibody is not species specific, but is restricted to the homologous functional area, the equatorial segment, in all other sperm examined (hamster, rabbit, human). When tested for a possible effect on the fertilization process, ascites fluid containing M29 antibody was very effective in blocking the fertilization of mouse gametes in vitro. The same inhibiting activity was observed regardless of whether the M29‐treated sperm first encountered the cumulus cell layer, the zona pellucida, or the egg plasma membrane. A large number of M29‐treated sperm were capable of penetrating zonae pellucidae when this layer was present. It appears, therefore, that M29 monoclonal antibody prevents fertilization specifically at the level of interaction between the sperm and egg plasma membranes; the other prefertilization events (hyperactivated motility, zona binding, acrosome reaction, zona penetration) seem little affected. Using the M29 antibody and related probes that are specific for particular biological events, it should be possible to map, in molecular terms, the functional domains of the sperm cell's membrane.
Comparison of the fertilizing ability of human spermatozoa preincubated in calcium‐ and strontium‐containing media
Authors: Mortimer D.
Published: June 2005

Human spermatozoa freed from seminal plasma using a discontinuous Percoll gradient procedure were incubated overnight in modified Tyrode's media containing either CaCl2 (CA medium) or with SrCl2 instead of CaCl2 (SR medium). The following morning these spermatozoa were washed by centrifugation, resuspended in fresh CA medium and incubated for either 2 or 3 h with zona‐free hamster eggs to test their fertilizing ability. Penetration rates were higher after 3 h of sperm‐egg contact than after 2 h, and the spermatozoa preincubated in SR medium penetrated significantly more hamster oocytes than those preincubated in CA medium.
The fine structure of germ plasm in eight‐cell embryos developing from normal and inverted eggs of Xenopus laevis
Authors: Jurand A. , Dixon K. E.
Published: June 2005

When X. laevis eggs developed with their animal‐vegetal axis oriented normally, the mitochondria of the germ plasm in eight‐cell embryos were frequently found to adhere to each other forming branching chains, and also the aggregates of germinal granules were physically associated with adjacent mitochondria. In embryos of the same stage developing from eggs inverted by 180°, these two components were arranged more loosely, so that the whole region of the germ plasm was less compact in appearance. In these embryos, the average number of intermitochondrial adhesions was reduced to approximately one‐third of that in the controls, while the average distance from the edge of an aggregate of germinal granules to the nearest mitochondrion was almost three times the control value. The morphology of the aggregates of germinal granules was also altered: they were much less compact, often with a large central space, and the individual granular components appeared as rings organised into chains. Absence of these associations between the two main constituents of the germ plasm in inverted eggs may correlate with the reduced numbers of primordial germ cells that enter the genital ridges, i.e., the function of the germ plasm as a determinant of primordial germ cells may depend on these associations.
Stimulation of cellular proliferation and differentiation in the intact and regenerating planarian Dugesia(G) tigrina by the neuropeptide substance P
Authors: Saló Emili , Baguñà Jaume
Published: June 2005

The neuropeptide substance P (SP) is shown to be a potent mitogen for intact and regenerating planarians. At nanomolar concentrations, SP markedly enhances cellular proliferation causing an increase in the mitotic index and in the number of blastema cells. Moreover, albeit to a lower extent, SP enhances cellular differentiation as shown by the increases in eye and pharynx length in regenerating organisms. On the basis of these observations, we hypothesize that SP may be one of the postulated growth factors necessary for the stimulation of proliferation, and to a lesser extent differentiation of cells in intact and regenerating planarians.
Contractile responses to temperature in the locomotory musculature of striped bass Morone saxatilis
Authors: Moerland Timothy S. , Sidell Bruce D.
Published: June 2005

The effects of temperature on contractile function of isolated, chemically skinned red (slow oxidative) and white (fast glycolytic) fibers of skeletal muscle from thermally acclimated striped bass (Morone saxatilis) were determined. Acclimation to 10° or 25°C has no significant effect on maximum isometric tension (Po) or maximum unloaded contraction velocity (Vo) of fibers of either muscle type. Sensitivity to acute changes in temperature is markedly greater for slow‐twitch fibers than for white, fast‐twitch fibers. Q10 (15–5°C) of Vo is 1.58 and 2.27 and R10 (15–5°C; analogous to Q10, but for parameters that are not rate functions) of Po is 1.57 and 2.17 for fibers from white and red muscle, respectively. R10 of maximum attainable power output is 1.29 for white and 4.50 for red fibers. Power for low speed, sustained swimming is derived exclusively from red muscle in striped bass, permitting comparisons between swimming performance and contractile capacity to be drawn. For maximum sustainable swimming speed at 15°C, calculated contraction velocity of a red muscle fiber corresponds to the maximum power output of a single fiber of red muscle at 15°C. Thermal sensitivity of red muscle power output predicts that maximum sustained swimming speed of striped bass will be severely impaired at cold temperatures. However, cold acclimation induces a proliferation of the red muscle mass that may ameliorate the thermal sensitivity of red muscle contractile function.
Intrinsic control of regenerative loss in Xenopus laevis limbs
Authors: Muneoka Ken , Holler‐Dinsmore Gregory , Bryant Susan V.
Published: June 2005

The regenerative capability of Xenopus laevis hindlimbs was studied at different developmental stages. Three types of surgical deletion of the autopod were performed: simple amputations, 3‐digit wedge‐shaped deletions and 1‐digit wedge‐shaped deletions. The frequency of regenerative response and the digital patterns of the regenerates were analyzed. Regenerative capacity declines with developmental stage for all three types of deletions. For simple amputations this decline occurs in an orderly manner with the failure of anterior digits to regenerate at progressively later stages. A comparison between 1‐digit and 3‐digit deletions shows that for all stages of development, 3‐digit deletions regenerate better than one‐digit deletions. These data indicate that the amount of tissue removed is directly related to whether a regenerative response is observed. At any given stage, larger deletions are more likely to regenerate than smaller ones. These results are discussed with regard to the mechanisms by which growth during regeneration is controlled.
Effects of exogenous ecdysteroid titer on endogenous ecdysteroid production in vitro by testes of the tobacco budworm, Heliothis virescens
Authors: Loeb M. J. , Brandt E. P. , Woods C. W.
Published: June 2005

Testes or the isolated sheaths of testes from late‐last‐instar larvae of the tobacco budworm, Heliothis virescens, spontaneously secreted ecdysteroids in vitro. Exogenous 20‐hydroxyecdysone, incubated with the testes or isolated testis sheaths, functioned in a local positive feedback system to increase production of the several ecdysteroids typical of H. virescens testes. The increase in ecdysteroid production by testis tissue was dependent on discrete ranges in exogenous ecdysteroid titer. Activation ratios of 2–5 resulted from exogenous 20‐hydroxyecdysone titers of 0.5 to 15 pg/μl, while activation ratios of 10–30 resulted from exogenous titers of 15–100 pg/μl of 20‐hydroxyecdysone. Activation ratios approached 200 with exogenous titers of 100–1,000 pg/μl of 20‐hydroxyecdysone.
Mitotic behavior and pseudopodial activity of cells in the embryo of Oryzias latipes during blastula and gastrula stages
Authors: Kageyama T.
Published: June 2005

A simple and rapid method for mechanically isolating cells from fixed embryos of Oryzias latipes was developed, in order to study the mitotic and pseudopodial activities of the cells during early development. Most of the sister cells retain cytoplasmic connections with each other until the prophase of the next mitosis, during the synchronous cleavage stage. The cells of the enveloping layer (EVL), an embryonic epithelium, never extrude pseudopodia. The appearance and the increase and decrease of six types of pseudopodial activity in deep cells during the blastula and gastrula stages are described, and an antagonism between the mitotic and the pseudopodial activities in deep cells has been documented in a quantitative manner. A noteworthy finding in the present study is the occurrence of an elongated intercellular cytoplasmic bridge, which connects members of pairs of postmitotic deep cells from the midblastula stage until the late gastrula stage. The intercellular bridge has been found for the first time in the Oryzias embryo as a result of the newly developed method for the isolation of cells.
Oocyte activation in the marine shrimp, Sicyonia ingentis
Authors: Pillai Muralidharan C. , Clark Wallis H.
Published: June 2005

The resumption of meiotic maturation and formation of the hatching envelope in the ova of the marine shrimp, Sicyonia ingentis were triggered by exposure to seawater. Fertilized and unfertilized ova underwent the same sequence of events; however, a slightly longer time was required for the completion of meiotic maturation and hatching envelope formation in unfertilized ova. The hatching envelopes formed in both cases were structually identical. Activation of unfertilized ova, but not fertilized ova, depended on external Ca++. If unfertilized ova that formed neither polar bodies nor a hatching envelope in Ca++‐free seawater were transferred to normal seawater, activation resumed. External Mg++ was necessary for both fertilized and unfertilized ova to undergo activation.
Coexpression of distinct eye‐ and liver‐specific LDH isozymes in cichlid fish
Authors: Holt Robert W. , Leibel Wayne S.
Published: June 2005

In a recent electrophoretic survey of lactate dehydrogenase (LDH) in neotropical cichlid fishes (Perciformes, Cichlidae) we have discovered several species in which a cathodal liver‐specific isozyme is expressed along with the highly‐anodal eye‐specific isozyme (LDH‐C4) typically encountered in perciform fishes. We believe this fourth, liver‐specific LDH isozyme to be real and not artifactual since homogenization of fresh liver from one of these species, the Basketmouth cichlid (Acaronia nassa), in either of two nondenaturing detergents or in the presence of the protease inhibitor phenylmethylsulfonylfluoride affects neither the presence nor mobility of this cathodal band. Moreover, it continues to be expressed in the captively bred F1 of these same wild fish.

The discovery of several fish species, like the Basketmouth, in which biochemically distinct eye‐ and liver‐specific LDH isozymes are coexpressed, is discussed in light of the currently accepted hypothesis that these two isozymes are encoded by a single locus (LDH‐C) which has undergone divergent tissue expression in several other major teleost groups. Preliminary characterization of the liver‐specific isozyme relative to the eye‐specific LDH‐C4 in the Basketmouth cichlid with respect to thermolability and NADH‐induced binding to oxamate‐sepharose columns suggests that the eye‐ and liver‐specific LDH isozymes are biochemically quite distinct in this fish and that they are probably encoded by two distinct loci.
Water balance responses of the hylid frog Litoria aurea
Authors: Cree Alison
Published: June 2005

Cutaneous and antidiuretic water balance responses of the hylid frog Litoria aurea to dehydration and exogenous arginine vasotocin (AVT) were examined. Both dehydration and AVT caused an increase in the rate of water uptake through ventral skin. Dehydration (in one of two experiments) and AVT also caused a reduction in the rate of bladder urine accumulation. During rehydration, rates of water uptake through ventral skin were seven times higher than through the average body surface of immersed frogs. Treatment of normally hydrated frogs with AVT in vivo caused increased cutaneous water uptake and a reduction in glomerular filtration rate; together these produced water retention equivalent to 27% above original body weight. Pelvic skin had a higher resting rate of osmotic water flow (OWF) in vitro than did pectoral or dorsal skin and was the only region to show increased OWF in response to AVT. The cutaneous hydroosmotic response of L. aurea to AVT is unusually large for a semiaquatic frog, and this may reflect the basking habits of this species or its position within the Hylidae.
Differential effects of testosterone and dibutyryl cyclic AMP on the meiotic maturation of mouse oocytes in vitro
Authors: Ecay Tom W. , Powers R. Douglas
Published: June 2005

Fully grown, meiotically immature mouse oocytes were isolated and cultured under varying conditions with the aim of determining a) whether the inhibitory effects of testosterone on oocyte meiotic maturation require the synthesis of new oocyte proteins and b) if the meiosis‐inhibiting effects of testosterone and dibutyryl cyclic AMP (dbcAMP) are distinct and can be differentiated. We found that the inclusion of puromycin in culture medium containing testosterone has no effect on the meiosis‐inhibiting potency of testosterone or upon the reversibility of testosterone effects. We conclude that testosterone inhibits oocyte meiosis by a mechanism that is independent of protein synthesis. We also found that oocytes exposed to testosterone recover more rapidly, as evidenced by the timing of germinal vesicle breakdown (GVBD) following placement in a control medium, than do oocytes exposed to dbcAMP. Through further investigation of this phenomenon we have determined the sequence of testosterone and dbcAMP effects relative to the time course of GVBD. A testosterone‐sensitive event occurs 20 min prior to GVBD, while the dbcAMP‐sensitive event precedes GVBD by 41 min. The nature of this difference may involve the differential interaction of testosterone and dbcAMP with a set of puromycin‐sensitive proteins that are required for GVBD. When oocytes were initially cultured in medium containing both puromycin and either testosterone or dbcAMP and then moved to medium containing puromycin alone the incidence of GVBD was reduced relative to oocytes never exposed to puromycin. This observation suggests that mouse oocytes contain proteins that are required for GVBD and that experience a high turnover rate. The degree of reduction in GVBD was a function of the length of puromycin exposure and was significantly greater in dbcAMP‐ than in testosterone‐exposed oocytes. If oocytes were initially cultured in medium containing puromycin and dbcAMP, the rate of GVBD upon removal of dbcAMP was initially slow but increased with time. This observation is consistent with the hypothesis that dbcAMP inhibits oocytes at a point prior to the functioning of the puromycin‐sensitive proteins. However, if oocytes were cultured in medium containing puromycin and testosterone the rate of GVBD following testosterone removal was not significantly reduced relative to oocytes that were not exposed to puromycin. This observation suggests that testosterone acts to inhibit meiosis at a site beyond the function of the puromycin‐sensitive proteins or that testosterone causes a reduction in the turnover rate of these proteins. We conclude that the effects of testosterone and dbcAMP on the mouse oocytes are distinct and distinguishable and further that testosterone will be a useful tool in dissecting the molecular mechanisms controlling mouse oocyte meiotic maturation.
An in situ measurement of sperm dispersal in a colonial marine hydroid
Authors: Yund Philip O.
Published: June 2005

Because gamete dispersal in the water column is an essential feature of sexual reproduction in most sessile invertebrates, an analysis of gamete dispersal patterns in the field is vital to an understanding of gene flow in these organisms. This paper presents the results of an in situ measurement of sperm dispersal in the colonial hydroid Hydractinia echinata conducted in calm water. The environmental cue mediating gamete release (exposure to light) was manipulated to temporally isolate experimental animals from the natural population. As assayed by the development of eggs collected at various distances from a male colony, the fertilization rate was very high within 3 m but dropped off rapidly with no fertilization observed beyond 7 m. The short sperm dispersal distances reported here, combined with a general trend toward larval dispersal distances on a similar spatial scale, suggest that gene flow in colonial invertebrates occurs on a relatively small spatial scale.
Humoral response of the snail Biomphalaria glabrata to trematode infection: Observations on a circulating hemagglutinin
Authors: Couch Lee , Hertel Lynn A. , Loker Eric S.
Published: June 2005

The hemolymph of invertebrates often contains molecules that agglutinate vertebrate erythrocytes and that may function as humoral mediators of “non‐self” recognition. The objectives of this study were to 1) determine if exposure of M line or 10‐R2 strain Biomphalaria glabrata snails to infection with the trematodes Echinostoma paraensei and Schistosoma mansoni could increase agglutinating activity in snail hemolymph, and 2) identify particular hemolymph molecules with such activity. In some host‐parasite combinations, such as juvenile M line snails and E. paraensei, infection provoked significant elevations in titer from as early as 2 days post‐infection (dpi) through 15 dpi. In other combinations, as with 10‐R2 snails and E. paraensei or S. mansoni, host responses were comparatively modest, yet still measurable. In general, E. paraensei and S. mansoni elicited different responses from the same host strain, and M line and 10‐R2 snails responded differently to the same parasite. Further study of the response of juvenile M line snails to E. paraensei indicated that hemolymph agglutinating activity could be inhibited by several monosaccharides (including L‐fucose) and by EDTA and EGTA. An affinity column containing L‐fucose agarose beads was used to purify molecules with agglutinating activity from the hemolymph of such snails. The fraction eluted from the column by 0.2 M L‐fucose was shown by SDS‐PAGE to contain a broad band of 80–120 kD and, less consistently, a 200 kD band. Following extensive dialysis to remove L‐fucose, this fraction had agglutinating activity. As a previous study has shown that the hemolymph of E. paraensei–infected snails contains significantly increased quantities of 80–120 kD polypeptides, it is concluded that polypeptides in this size range are responsible, at least in part, for the increased hemolymph agglutination activity in such snails.
Effect of noradrenaline on the methaemoglobin concentration of rainbow trout red cells
Authors: Paajaste Marita , Nikinmaa Mikko
Published: June 2005

We studied the effect of noradrenaline on the methaemoglobin (metHb) concentration in rainbow trout red cells. The erythrocytes were incubated in physiological medium with or without noradrenaline and the percentage of metHb of total Hb content was measured. Noradrenaline lowered the metHb content significantly as compared to controls. To study if the effect of noradrenaline was caused by adrenergic intracellular alkalinization, cells were treated with noradrenaline + carbonic anhydrase or noradrenaline + acetazolamide. Carbonic anhydrase inhibits the adrenergic increase in intracellular pH, but did not reduce the effect of noradrenaline on the metHb concentration. Acetazolamide accentuates the increase in intracellular pH. However, there was no difference in the methaemoglobin content of noradrenaline‐incubated and noradrenaline + acetazolamide‐incubated cells. These results show that the effect of noradrenaline on the methaemoglobin content is independent from the adrenergic increase in intracellular pH. However, amil‐oride treatment inhibited the effect of noradrenaline on the methaemoglobin content, suggesting that the protein mediating sodium/proton exchange may also be involved in controlling cellular methaemoglobin levels.
Sodium orthovanadate induces in vitro ovulation and ovarian prostaglandin synthesis in brook trout (Salvelinus fontinalis)
Authors: Hsu Sheau‐Yu , Goetz Frederick William
Published: June 2005

The in vitro effects of sodium orthovanadate (Na3VO4), a G‐protein activator, on ovulation and prostaglandin (PG) synthesis were investigated in the brook trout (Salvelinus fontinalis) ovary. PGE and PGF levels in incubation medium of either extrafollicular (EF) tissue or follicles were measured by specific radioimmunoassays (RIA). PGE levels in follicle incubates were increased by Na3VO4 at both pre‐germinal vesicle breakdown (preGVBD) and preovulatory (preOV) stages. However, an increase of PGF levels in follicle incubates was observed only in preGVBD follicles in the presence of Na3VO4. The preOV follicles spontaneously released more PGF than preGVBD follicles and the level was not affected by Na3VO4 treatment. In contrast, in incubates of EF tissue, Na3VO4 induced dosage‐dependent increases in PGE and PGF at either stage. The Na3VO4‐stimulated increase of PGE in preOV follicle incubates was significantly reduced by the translational inhibitor, cycloheximide (5 μM), but not by the transcriptional inhibitor, actinomycin (5 μM). PGF levels in preOV follicle incubates were also significantly reduced by cycloheximide and actinomycin in controls, but not in the presence of 0.1 mM Na3VO4. The results suggest that protein synthesis was required for Na3VO4 to increase accumulation of PGE, and in maintaining control PGF levels in preOV follicles. In addition, since PGF levels in preOV follicles were not reduced by either inhibitor in the presence of Na3VO4, a Na3VO4‐stimulated increase of PGF levels was unmasked that apparently acts through a non‐translational pathway. In vitro ovulation was also significantly increased by 0.1 mM Na3VO4. However, the Na3VO4‐induced ovulation was not inhibited by either actinomycin or cycloheximide. The data imply that the mechanism(s) by which Na3VO4 induces ovulation are distinct from that for stimulating PG accumulation. When preOV follicles were incubated with 10 μM forskolin, no stimulatory effect on ovulation, or on PGE and PGF levels was observed. The data strongly indicate that the effects of Na3VO4 on ovulation and ovarian PG levels were not mediated by an increase in cAMP.
Monoamines and neuropeptides as transmitters in the sedentary polychaete Sabellastarte magnifica: Actions on the longitudinal muscle of the body wall
Authors: Díaz‐Miranda Lucy , de Motta Gladys Escalona , García‐Arrarás José E.
Published: June 2005

Pharmacological studies on the body wall musculature of the sedentary polychaete Sabellastarte magnifica show a potential neurotransmitter role for monoamines and neuropeptides in this organism. All catecholamines induced contraction of longitudinal muscle strips, while serotonin and the neuropeptides FMRFamide and substance P caused a relaxation of both resting and active muscle. In addition, we demonstrate catecholaminergic and serotonergic pathways in the nervous system of this sabellid, using immunohistochemistry and catecholamine‐induced fluorescence. The presence of neuropeptide‐containing fibers in the nervous system of this polychaete has been previously reported. Together these results suggest that catecholamines act as excitatory transmitters on the longitudinal muscle cells of the body wall of S. magnifica, while serotonin and FMRFamide, and possible substance P, are inhibitory transmitters. The possibility of coexistence of serotonin and FMRFamide within the same neuronal cell bodies and fibers of this polychaete is also explored. © 1992 Wiley‐Liss, Inc.
Interactive effects of high stocking density and triiodothyronine‐administration on aspects of the in vivo intermediary metabolism and in vitro hepatic response to catecholamine and pancreatic hormone stimulation in brook charr, Salvelinus fontinalis
Authors: Scott‐Thomas D. A. F. , Ballantyne J. S. , Leatherland J. F.
Published: June 2005

Brook charr (Salvelinus fontinalis) were maintained at one of two stocking densities (SD) (30 or 120 kg/m3) and fed either a control or a T3‐supplemented (20 mg/kg) diet for 30 days in order to investigate possible interactive effects of SD and T3‐administration on growth, feeding rate, food conversion efficiency, and hepatic and dark muscle enzyme activity. In addition, liver slices were incubated in vitro for 6 h with epinephrin, norepinephrin, isoproterenol, propranolol, insulin, glucagon, or somatostatin to evaluate possible SD‐T3 interactive effects on hepatic responses to hormonal stimulation. Maintaining the fish at high SD appeared to increase the clearance rate of T3 from the T3‐supplemented group. There was no clear evidence of SD‐T3 interactive effects on growth rate, feeding rate, or food conversion efficiency, although T3‐administration decreased food conversion efficiency, and high SD decreased growth and feeding rates. Of the hepatic enzymes studied, HOAD, malic enzyme, G6PDH, CS, PFK, HK, and GDH activities all showed changes suggestive of interactive SD‐T3 effects. Although hepatic FBPase was stimulated by both high SD and T3‐administration, there was no evidence of interactive SD‐T3 effects. Dark muscle HOAD, CS, and PFK also showed SD‐T3‐related responses; dark muscle malic enzyme, G6PDH, HK, and GDH were unaffected by either altered SD or T3‐administration.

Prior treatment of the fish with T3 and high SD had significant effects on free fatty acid (ffa) release to the medium and on hepatic lipid content, but had no effect on the responses to the various endocrine agents used. Glucose release from liver slices of fish stocked at high density (both T3‐supplemented and controls) was higher than that of the fish stocked at low density; with the exception of insulin and glucagon, glucose release was similar in all pre‐treatment groups. The insulin‐ and glucagon‐stimulated changes in glucose release seen in the fish fed non‐supplemented diets were not found in the two groups of fish fed the T3‐supplemented diets. High SD and/or T3‐administration induced significant lowering of hepatic glycogen content, but there was no effect of pre‐treatment on the response to any of the endocrine agents used. The data show a marked effect of SD on energy partitioning processes in brook charr and the animal's ability to respond to T3‐stimulation, but provided no evidence of such effects on the liver response to the various agents used. © 1992 Wiley‐Liss, Inc.
Intrinsic pigment cell stimulating activity in the skin of the leopard frog, Rana pipiens
Authors: Mangano Francesco T. , Fukuzawa Toshihiko , Johnson Warren C. , Bagnara Joseph T.
Published: June 2005

Consistent with the concept that specific pigment patterns of amphibians might result from the highly localized distribution of stimulators and inhibitors of pigment cell expression in the skin, the spot pattern of the leopard frog, Rana pipiens, was examined through the use of the Xenopus neural tube explant assay system (Fukuzawa and Ide, 1988). Media conditioned with pieces of skin from dorsal black spotted areas promoted melanization of neural crest cells at a significantly higher level than did media conditioned with dorsal interspot skin in the absence of extra tyrosine. All conditioned media contained exceedingly low concentrations of tyrosine. With the addition of supplemental tyrosine, the melanization capacity of conditioned media from the interspot areas was elevated to that of the spotted skin. Control media conditioned with ventral frog skin inhibited melanization, as usual, because of the presumed presence of melanization inhibiting factor (MIF). It is considered that dorsal skin contains a melanization stimulating factor (MSF) which is present in significantly higher levels in spotted skin than in interspot areas and that expression of the particular pigmentary pattern of this leopard frog is regulated by the relative distribution of MIF, MSF, and possibly other intrinsic substances present in the skin. © 1992 Wiley‐Liss, Inc.