bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface properties of the zona pellucida
Authors: Phillips David M. , Shalgi Ruth M.
Published: June 2005

Structural and sperm binding properties of the hamster zona pellucida (ZP) were investigated using the scanning electron microscope (SEM). The internal and external surfaces of the ZP were found to be morphologically dissimilar. The external surface displayed a fenestrated lattice‐like appearance, whereas the internal surface showed a regular rough appearance. In order to investigate the physiological characteristics of the ZP, zonae were incubated with in vitro capacitated spermatozoa for five minutes and subsequently prepared for SEM examination. Numerous non‐acrosome‐reacted spermatozoa and dissociated acrosomes were observed associated with the external surface of the ZP. Spermatozoa or acrosomes were, however, not observed associated with the internal surface of the zona. Acrosome‐reacted spermatozoa did not adhere to the ZP. It was concluded that the external and internal surfaces of the zona are morphologically and physiologically dissimilar.
A study of morphology of Caenorhabditis elegans: A mutant of Caenorhabditis elegans with dumpy and temperature‐sensitive roller phenotype
Authors: Hosono Ryuji
Published: June 2005

The wild‐type nematode Caenorhabditis elegans has an elongated and spindle‐shaped body, whereas the dumpy mutant has a shorter body with approximately the same diameter. Although the wild‐type nematode moves forward by producing sinusoidal waves along the body, the roller mutant moves by rotating the body left or right around its long‐body axis. A temperature‐sensitive morphological mutant which develops into an adult with dumpy phenotype, at 15°, but with roller phenotype at 25°, in addition to dumpy phenotype, was isolated. The dumpy phenotype appeared at the first larval stage and was complete at the fourth larval stage; the roller behavior was also expressed at the fourth larval stage. The heterozygous offspring (F1), produced by crossing the mutant hermaphrodite with wild‐type males, were rollers in both hermaphrodites and males. Therefore, the dumpy character is autosomal recessive, and the roller character is dominant in heterozygote but cold‐sensitive in homozygote. The dumpy mutation was mapped as allele of dpy‐10 gene of linkage group II (LG II). The F2 progeny, produced by self‐fertilization of the F1 roller hermaphrodite, segregated to wild, dumpy, and roller animals in a ratio of 1:1:2. An attempt to isolate from the F2 generation the roller mutant which produced no dumpy progeny was entirely unsuccessful. Therefore, the dumpy and the roller phenotypes are produced by closely linked mutations or perhaps by a single mutation.
Histochemistry of lobster claw‐closer muscles during development
Authors: Ogonowski M. M. , Lang F. , Govind C. K.
Published: June 2005

Based on histochemical detection of the specific activities of myofibrillar ATPase in fast and slow mucle, the fiber composition of the paired claw‐closer muscles in the lobster Homarus americanus was examined during development. The cutter muscle of juvenile lobsters, 1 year (13th stage) and older, has a majority of darkly staining, fast fibers and a minority of lightly staining, slow fibers which are restricted to the ventral area. The crusher muscle, on the other hand, stained lightly over its entire area, showing that it is composed only of slow fibers. In the 3rd larval stage the paired muscles are similar, each having a central band of intense‐staining, fast fibers sandwiched by light‐staining, slow fibers. From the 4th stage onwards, the differentiation to the dimorphic condition occurs with gradual expansion, in the cutter claw of the dark‐staining, fast fibers, and in the crusher claw of light‐staining, slow fibers. The cutter closer muscle is differentiated completely and consistently by the 9th–10th stage, whereas the crusher differentiated more slowly between the 13th–22nd stages. During this process the transformation of slow muscle to fast in the cutter claw may be via an intermediate type.
Studies on the mechanism of neurulation in the chick: Microfilament‐mediated changes in cell shape during uplifting of neural folds
Authors: Nagele Robert G. , Lee Hsin‐Yi
Published: June 2005

The organization and properties of microfilaments of developing chick neuroepithelial cells were investigated in an attempt to elucidate the structural basis for the observed changes in cell shape during uplifting of neural folds. Microfilaments in the apical regions of cells are more organized than those along the lateral and basal cell margins and are associated with developing junctions. At the level of the zonula occludens, microfilaments are arranged into a loose meshwork extending just below the luminal surface. At the level of the zonula adherens, microfilaments are organized into several discrete bundles rather than as a single circumferential bundle. The opposite ends of these bundles appear to make contact with the plasma membrane at specialized areas of the junction. Microfilaments in the peripheral cytoplasm of the neck and basal regions form a continuous but sparse meshwork. All of these microfilaments bind heavy meromyosin. The implications of the present findings to the observed changes in cell shape during uplifting of neural folds in the chick is discussed.
Polyamines and diamines in regenerating tissues of the Japanese newt, Triturus (Cynops) pyrrhogaster
Authors: Matsuzaki Shigeru , Inoue Sakae
Published: June 2005

Newt forelimb and tail regenerates of various stages were analyzed for their contents of diamines and polyamines, including putrescine, spermidine, spermine, sym‐homospermidine, and cadaverine. All the regenerates were particularly rich in putrescine and spermidine among the amines tested. The putrescine level in forelimb regenerates continued to increase during the bud formation period to reach a maximum at 45 days after amputation (“palette stage” to “medium digit stage”) and then decreased. In tail regenerates, putrescine level doubled within 14 days, reached a peak at 26 days, and then decreased gradually. The spermidine level in forelimb regenerates increased gradually for 45 days after amputation and decreased thereafter, while that in tail regenerates reached a peak at 26 days and remained nearly constant thereafter. The spermine and sym‐homospermidine concentration changed little throughout the experiment. Cadaverine levels were lower in the regenerates of the male newt than in intact tissues.
Production of androgenetic diploid axolotls by suppression of first cleavage
Authors: Gillespie Laura L. , Armstrong John B.
Published: June 2005

Androgenetic diploid axolotls were produced by a combination of ultraviolet inactivation of the egg pronucleus and pressure suppression of the first cleavage division. Although survival was low, this technique will prove to be useful for producing completely homozygous animals in one step.
Isolation of hatching gland cells from the teleost, Oryzias latipes, by centrifugation through percoll
Authors: Yoshizaki Norio , Sackers Rudolf J. , Schoots André F. M. , Denucé J. M.
Published: June 2005

Hatching gland cells (HGCs) of the teleost, Oryzias latipes, have been isolated. The optimum condition is mechanical dissociation of the buccal tissues in Ca‐free saline containing 15% bovine serum albumin (BSA). The cell suspension is fractionated by centrifugation through 30–33.3% Percoll TM containing 5% BSA. The isolated HGCs are washed in 5% BSA. BSA in the latter two solutions can be omitted when a swing‐out rotor is used. The recovery of total and viable HGCs was about 74% and 45%, respectively. The purity was 75–85%. Cellular integrity was shown by pseudopodial movements of the cultured cells.
Effects of growth hormone and thyroxine on pituitary and testicular function in two types of hereditary dwarf mice
Authors: Doherty P. C. , Bartke A. , Dalterio S. , Shuster L. , Roberson C.
Published: June 2005

Hereditary dwarf mice are growht hormone (GH)‐ and prolactin (PRL)‐deficient and hypothyroid. Administration of PRL, GH, or thyroxine (T4) can induce fertility inmale dwarf mice. The mechanism of action of PRL appears to involve stimulation of FSH release, increased ability of the testes to bind LH, and increased production of testosterone (T) and spermatozoa. To obtain some information on the action of GH and T4 on the pituitary‐testicular axis in these animals, we have examined spermaogenesis, plasma hormone levels, and testicular T production in vitro in Snell (dw) and Ames (df) dwarf mice treated with GH or T4. Treatment with T4 (2μg/day for 2 weeks; 1μg/day for 4 weeks or 4–6μg 3 ×/wk for 6 weeks) or with GH (125 μg/day for 2 weeks; or 38–150 μg/day for 4 weeks) increased body weight, stimulated spermatogenesis, and increased the weight of the testes and seminal vesicles. Treatment with T4 had no significant effects on plasma hormone levels, while treatment with GH for 2 weeks increased plasma levels of LH, FSH, and T in Ames but not in Snell dwarf mice. The ability of the testes to produce T in vitro in the presence of hCG was not affected by in vivo treatment with GH or T4 in either df or dw dwarf mice. These results indicate that the stimulatory effect of T4 and GH on testicular function of dwarf mice does not involve increased responsiveness to gonadotropins or major chages in gonadotropin release. Comparison of the present results with those obtained earlier with PRL indicates that the ability of PRL to induce fertility in dwarf mice may be a specific action of this hormone on the pituitary‐testicular axis, rather that a result of its inherent somatotropic activity.
DNA synthesis and mitosis in adult newt limbs following amputation and insertion into the body cavity
Authors: Loyd Robert M. , Tassava Roy A.
Published: June 2005

Experiments were designed to investigate the roles of injury, nerves, and wound epidermis in regeneration. By immediate insertion of amputated limbs into the body cavity, the wound epidermis was prevented from forming. Through 3 weeks post amputation, these inserted limbs showed lower 3H‐thymidine labeling indices and mitotic indices than control normally regenerating limbs. No blastema formed and regeneration did not occur. When denervation preceded insertion, some labeling with 3H‐thymidine was seen but essentially no mitoses were observed. When insertion of innervated limbs was delayed for 48 hr to allow the wound epidermis to form, regeneration occurred in a normal fashion. These results emphasize the importance of injury, nerves, and wound epidermis in controlling cell cycle events during regeneration.
Frequency of supernumerary limbs following blastemal rotations in the newt
Authors: Stock Gregory B. , Krasner Gary N. , Holder Nigel , Bryant Susan V.
Published: June 2005

An examination has been made of the supernumerary limbs produced as a result of tissue interaction following ipsilateral rotation of blastemas at the stage of early digits. The frequency of supernumerary limb formation peaks sharply at angles of rotation near 180°, where tissues from widely separated circumferential locations are opposed. This behavior is compatible with predictions of the polar coordinate model with positional values clustered in the anteriorventral quadrant of the circumference (French et al., '76; Bryant and Iten, '76).
Cytochemical localization of acid phosphatase in ocelli of the seastar Patiria miniata during recycling of photoreceptoral membranes
Authors: Brandenburger Jean L. , Eakin Richard M.
Published: June 2005

The amount and distribution of the lysosomal enzyme acid phosphatase in ocelli of seastars (Patiria miniata) in a 24‐hour light‐dark cycle were studied by a standard cytochemical technique. The enzyme was found in the Golgi apparatus, GERL, and primary and secondary lysosomes of sensory and pigmented supportive cells. We conclude that photoreceptoral membrane of the sensory microvilli is resorbed inthe day by incorporation into pinocytotic vesicles and saccules and degraded in the late day and at night in the secondary lysosomes. Photoreceptoral membrane of microvilli abscised into the ocellar cavity in the day is probably recycled by phagocytosis and digestion in secondary lysosomes of the supportive cells, and perhaps to a lesser extent in the corneal cells. We speculate that recaptured molecules, including photopigment, are returned, in some unknown way, to the distal ends of the sensory cells where the receptoral microvilli are regenerated in the dark. Pinocytotic vesicles may provide stored membrane.
Neural tube closure defects following in vitro exposure of mouse embryos to xylocaine
Authors: O'shea K. S. , Kaufman M. H.
Published: June 2005

Early somite mouse embryos were exposed in vitro to xylocaine (Lignocaine hydrochloride) to examine its effect on neural tube closure. When embryos were exposed to 2.4 × 10−4 mg/ml xylocaine for the entire 36‐hour culture period, cephalic neural tube closure did not take place. When examined by SEM, the neuroepithelial cells of these embryos were incompletely elevated, and depressions in their lateral surfaces were often observed. TEM observations on the neuroepithelium of similar embryos indicated that the microtubules and apical microfilament bundles were absent.

The role of calcium in the maintenance of neuroepithelial cell asymmetry and in the production of these defects is considered.
Genome exclusion in gametogenesis by an interspecific Rana hybrid: Evidence from electrophoresis of individual oocytes
Authors: Uzzell Thomas , Hotz Hansjürg , Berger Leszek
Published: June 2005

The diploid hybridogenetic frog Rana esculenta, an interspecific hybrid of R. ridibunda and R. lessonae, usually transmits its ridibunda genome to progeny: the lessonae genome is lost before gametogenesis is completed. Samples of ovary reveal only ridibunda alleles when examined electrophoretically. Cytological and genetic evidence suggests that the lessonae genome is excluded premeiotically. Since recombination between the parental genomes occurs at a low frequency, such recombination should be detectable by examination of the alleles expressed in individual enlarged oocytes.

Examination of electrophoretic markers for four loci from 860 individual oocytes (100 each from eight females, ten each from six females) revealed no evidence of either heterozygosity or recombination, although the eight females for which 100 oocytes were examined were somatically heterozygous 29 times for these loci, so that there were 2,900 possibilities for detecting heterozygosity or recombination in the oocytes.

These data abundantly confirm the inactivity of the lessonae genome during vitellogenesis in Rana esculenta. They are consistent with a premeiotic exclusion of the lessonae genome, but do not require it. The lessonae genome may be present although inactive, which may permit occasional crossing over between the lessonae and ridibunda genomes. The exclusion of the lessonae genome possibly is a consequence of its inactivity. Exclusion of the non‐ridibunda genome seems to be under control of loci located in the ridibunda genome. A regulatory endoduplication of the ridibunda genome may be necessary before an orderly meiosis can occur.
Male fertility in a female‐sterile mutant of Drosophila melanogaster
Authors: Trippa G. , Loverre A. , Cicchetti R.
Published: June 2005

The fertility and the fecundity of males homozygous for the recessive female‐sterile factor fs(2)TLM have been investigated. Both for standard mating and for observed mating procedures, there was a more than 35% male sterility. Moreover, in a total fecundity experiment the fertile males (about 70%) were effectively fertile for a shorter time than the control males, and the mean progeny per male was about a third that of the controls.

It can thus be concluded that the penetrance of the fs(2)TLM factor is different in the two sexes, being complete in the females and incomplete (0.35) in the males. Furthermore, in the males it shows two different degrees of expressivity: complete sterility and fecundity lowered by about 70%.

It is suggested that the resultant sterility of these males is a consequence not merely of altered processes causing testicular abnormalities, but also of independent events directly affecting spermatogenesis.
Mitotic activity in the pseudoapical ridge of the trout pelvic fin bud, Salmo gairdneri
Authors: Geraudie Jacqueline
Published: June 2005

A radioautographic study of the pseudoapical epidermal ridge, after tritiated thymidine labelling, shows that basal cells do not incorporate this precursor to DNA synthesis. The results conform with the low mitotic activity of this structure after vinblastine treatment, and point to a special metabolism of these cells, probably associated with their involvement in actinotrichial development.
Ribonucleoside metabolism by mouse oocytes: Metabolic cooperativity between the fully grown oocyte and cumulus cells
Authors: Heller David T. , Schultz Richard M.
Published: June 2005

Ribonucleoside uptake and metabolism were studied in mouse oocytes arrested at dictyate and metaphase II, with or without attached cumulus cells. Uptake of uridine and guanosine decreased after meiotic maturation, whereas that of adenosine and cytidine remained unaltered. Dictyate oocytes free of cumulus cells (denuded) phosphorylated all of the radiolabeled ribonucleosides. Little radiolabeled ribonucleoside‐5′‐triphosphate was found. This is in contrast to the early mouse embryo, which rapidly converts ribonucleosides to the 5′‐triphosphate (Daentl and Epstein, '71; Clegg and Piko, '77). Following meiotic maturation, the major metabolite present when metaphase II oocytes were cultured with cytidine or uridine was the ribonucleoside, whereas the 5′‐monophosphate was still the major species for oocytes cultured with guanosine or adenosine.

Ribonucleoside uptake was increased and the distribution of phosphorylated metabolites was different for cumulus‐enclosed dictyate oocytes compared to their denuded counterparts. This increase in uptake and alteration in metabolite distribution was not observed for cumulus‐enclosed metaphase II oocytes. These results are discussed in terms of gap junction‐mediated metabolic cooperativity between the cumulus cells and the fully grown oocyte and the possible role this type of cell‐to‐cell interaction may serve during oocyte growth.
Erythrocyte metabolism: Kinetic and electrophoretic analyses of pig red cell hexokinase
Authors: Dixon Earl , Wilson B. A.
Published: June 2005

The mature erythrocyte of the pig has been observed to possess the slowest metabolic rate of any mammalian cell type. Previous studies in this laboratory suggested that the hexokinase isolated from these cells was inhibited by glucose in concentrations in excess of 0.2 mM. In the present study, the enzyme was isolated by utilizing DEAE‐Sephadex A‐50, ammonium sulfate precipitation, DEAE‐cellulose (DE‐52), and Sephadex G‐100 gel‐filtration. Studies on the hexokinase isolated from the pig mature erythrocyte by the above procedures revealed two distinct isozymes of hexokinase that do not behave kinetically and electropho retically as those previously found in other mammalian red blood cells. The isozyme isolated from the erythrocyte of the young adult pig (less than six months of age) migrated at a slower electrophoretic rate than the one isolated from the adult pig (more than six months of age). Coupled with the observed difference in electrophoretic mobilities were changes in the apparent Km̂, values as well as Vmax as a function of substrate concentration. In spite of the changes observed in relation to glucose, the apparent Km̂ for Mg‐ATP−2 was not altered during development. Diphosphoglycerate (DPG) was observed to be a “linear‐mixed” inhibitor of both isozymes with respect to Mg‐ATP−2. An experiment designed to determine the type of inhibition by DPG on the type I isozyme isolated from the horse erythrocyte revealed competitive inhibition with the Mg‐ATP−2 site. Free Mg activated both isozymes in low concentrations (< 2.5 mM) but inhibited the enzymatic activity as the concentration was elevated. The data suggest that both the young adult and the adult pig erythrocyte possess two distinct type III isozymes of hexokinase.
Wing buds with three ZPAs
Authors: Iten Laurie E. , Murphy Douglas J. , Javois Lorette C.
Published: June 2005

It has been hypothesized that a diffusible morphogen emanates from the ZPA of the embryonic chick limb and that cells can have their presumptive fate respecified to form more posterior structures when exposed to a higher concentration of morphogen. Attempts to raise the concentration of morphogen by grafting two additional ZPAs into a host wing bud failed. Instead, the greater the positional disparity between the donor and host tissue at the graft sites, the greater the number of extra structures that formed.
Mechanics of tail resorption in triiodothyronine‐induced metamorphosing tadpoles
Authors: Dmytrenko George M. , Kirby Gerald S.
Published: June 2005

The mechanics of tail resorption in triiodothyronine (T3) induced metamorphosing Rana catesbeiana tadpoles was investigated. Premetamorphic (Taylor and Kollros stages 7–11) tadpoles'tails were permanently marked off into three segments with silk suture loops anchored in metameric musculature of the tail. A dose of 3 × 10−10 moles T3/gram of body weight was administered intraperitoneally. Tail length measurements were made daily for 6 days after injection. Significant reductions were observed in total tail length as well as concurrent reductions in proximal, middle and distal tail segment lengths. These data indicate that resorptive activity is not confined to the distal tail tip, but that tissue resorption occurs simultaneously along the entire tail length. The rate of shortening is greatest in the distal segment and least in the proximal segment. Key words: Tail resorption, Metamorphosing, Triiodothyronine, Tadpole.
The cellular origin of the zona pellucida antigen in the human and hamster
Authors: Bousquet D. , Léveillé M. C. , Roberts K. D. , Chapdelaine A. , Bleau G.
Published: June 2005

The origin of the zona pellucida in follicles at different stages of maturation was studied in the hamster and human by indirect immunofluorescence microscopy using a specific anti‐hamster zona pellucida serum. The earliest detection of the zona pellucida material occurred in the ooplasm of oocytes in primordial follicles. In primary follicles, the fluorescence was localized at the periphery of the oocyte. In secondary and in mature follicles a deposition of fluorescent material was visualized on the inner and outer regions of the zona pellucida. Follicular cells, other than the oocyte, failed to exhibit a fluorescent reaction with the antizona pellucida serum. It is concluded that the oocyte is an important source of the antigenic material of the zona pellucida of hamster and human ova.
Adaptation and tolerance of invertebrate nervous systems to osmotic stress
Authors: Prior David J. , Pierce Sidney K.
Published: June 2005

Both the osmotic and ionic concentration changes accompanying a salinity alteration might be expected to have profound effects on neuronal physiology, especially in euryhaline animals. We have examined the effects of salinity change and followed the subsequent adaptation to that change by an invertebrate neuron. The spontaneous activity of the follower cell of the cardiac ganglion of Limulus polyphemus is altered during salinity stress. The membrane potential is depolarized, the burst frequency is altered and the impulse pattern within each burst is disrupted following hypoosmotic stress. With time in the reduced salinity, adaptation occurs and both the membrane potential and the burst pattern return to control levels. Further, all these changes are due to osmotic variation with no detectable ionic component. Coincident with the adaptation of the electrical characteristics of these follower cells is an efflux of intracellular free amino acids which in turn, presumably, is regulating cell volume. Thus, this temporal correlation suggests that the electrical adaptation is dependent upon the cell volume regulatory mechanisms of the neurons.
Adaptation of nitrogen metabolism to hyperosmotic environment in Amphibia
Authors: Balinsky John B.
Published: June 2005

A large number of species of Amphibia, both Anura and Urodela, are capable of tolerating a moderately saline environment. Rana cancrivora, Bufo viridis, and Xenopus laevis are among the most euryhaline frogs so far studied. Rana cancrivora can tolerate undiluted seawater. In a saline environment, Amphibia show raised plasma sodium and chloride and raised intracellular potassium and chloride. In the adults, plasma and tissue urea are elevated, especially in the more euryhaline species. Free amino acids contribute negligibly to plasma osmolarity, but are very important in intracellular fluids. By these various means, the osmotic pressure of body fluids is always maintained at a higher level than that of the surroundings. Larval Amphibia, however, do not make urea; Rana cancrivora tadpoles can live in saltwater, but maintain the osmolarity of their body fluids below that of their surroundings.

Adaptive responses to hyperosmolar environment include decreased skin sodium transport, greatly reduced urine flow, and release of posterior pituitary hormones. After the initial response, the release of these hormones declines, and urine flow increases. Accumulation of urea occurs slowly, but this substance plays an increasingly important role as adaptation proceeds. Accumulation is due initially to urea retention, and possibly to greater synthesis due to a high concentration of precursors of the urea cycle. In later stages of adaptation, increased urea synthesis is due to elevated levels of urea cycle enzymes, especially those that appear to have been rate‐limiting. Liver glutamate dehydrogenase is also elevated. In animals subjected to pure osmotic stress, in solutions not containing sodium, responses are similar to, but not identical with, those caused by a medium containing sodium chloride.
Cell volume regulation in crustaceans: Relationship between mechanisms for controlling the osmolality of extracellular and intracellular fluids
Authors: Gilles R. , Péqueux A.
Published: June 2005

The control of cell volume in tissues of crustaceans acclimating to salinity changes cannot be ascribed to a single mechanism; it results rather from different processes acting both at the cell level and at the blood level. The mechanisms at work at the cell level are discussed and some possible relations between them and those acting at the blood level are considered. The amino acids leaking out of the cells during cell volume readjustment, following application of hypoosmotic conditions, can be stored in the form of blood proteins. Increased deamination and oxidation of amino acids also occur under such conditions, the products of this increased catabolic activity being used in the gills as counterions for NaCl active uptake.
Hormone‐induced ovulation in Ambystoma tigrinum: Influence of prolactin and thyroxine
Authors: Norris David O. , Duvall David
Published: June 2005

Treatment of hypophysectomized or intact neotenic tiger salamander larvae (Ambystoma tigrinum) with ovine prolactin (PRL) increased sensitivity of the ovary to the ovulation‐inducing hormones, human chorionic gonadotropin and luteinizing hormone (LH). Effects of pretreatment in vivo with PRL or thyroxine (T4) on the responsiveness of ovarian fragments in vitro to ovulation‐inducing agents, LH, or progesterone (PROG) in the presence or absence of PRL were observed. In November (prior to normal spawning occurring from January through May) in vivo and in vitro treatment with PRL increased the number of oocytes producing polar bodies and the number of eggs ovulated in vitro. In April addition of PRL in vitro increased polar body formation and ovulations in response to LH or PROG, but in vivo pretreatment with PRL had no effect. Pretreatment in vivo with T4 blocked the in vitro enhancement observed with PRL. Thus, endogenous PRL may play a role in the development of ovarian sensitivity to ovulatory hormones at the level of the oocyte, and T4 may inhibit this action.
Synaptic mechanisms that generate network oscillations in the absence of discrete postsynaptic potentials
Authors: Anderson William W. , Barker David L.
Published: June 2005

Synaptic mechanisms were examined in the pyloric network of the lobster stomatogastric ganglion which generate network oscillations in the absence of discrete postsynaptic potentials (PSPs). In normal saline, the unstimulated pyloric network underwent weak bursting in only a few cells. Stimulation of the input nerve, or bath application of the input neurotransmitter dopamine, produced similar vigorous bursting in many pyloric neurons. In saline‐containing tetrodotoxin (TTX) plus dopamine, action potentials and corresponding discrete PSPs were blocked, but the underlying slow wave oscillations in network neurons continued. No oscillations occurred in TTX‐saline without dopamine. The generation of these nonspiking network oscillations can be explained by the interaction between two synaptic mechanisms which do not produce discrete PSPs: neurotransmitter activation of bursting pacemaker oscillations in a single network neuron, and graded inhibition between network neurons.
Uptake and binding of prostaglandins in a marine bivalve, Modiolus demissus
Authors: Freas William , Grollman Sigmund
Published: June 2005

The existence of specific PGA2 binding sites was demonstrated in the 12,000 × g supernatant fraction of homogenized gill tissue from Modiolus demissus (Geukensia demissus). The binding of prostaglandins at these sites was pH‐dependent, time‐dependent, and reversible. The binding was more specific for prostaglandin A2 (PGA2) than prostaglandin E2 (PGE2) or prostaglandin F2α (PGF2α). Binding was enhanced by calcium and magnesium. For calcium the binding kinetics exhibited a Km of 7 mM; for magnesium the Km was 15 mM. The amount of PGA2 bound/mg protein at saturating cation concentration was determined to be 0.20 pmoles/mg for both calcium and magnesium. A dissociation constant (Kd) of 9.8 × 10−5 M was calculated by Scatchard plot analysis for the PGA2 binding site. Binding was inhibited by 20 mM Cu+ +, 10−3 M ATP and 10−3 M GTP. These low‐affinity binding sites may perform an important role in the physiological action of prostaglandins in marine bivalves.
Survival of mouse embryos after freezing and thawing in the presence of erythritol
Authors: Miyamoto Hajime , Ishibashi Takehiko
Published: June 2005

Eight‐cell mouse embryos were frozen by using erythritol as the cryoprotective agent. The samples were cooled slowly (1°C/min) to temperatures between − 15 and − 75°C before direct transfer into liquid nitrogen (− 196°C). The most effective concentration of erythritol for freezing of embryos was 0.6 M, and the optimal exposure time of embryos to 0.6 M erythritol at 0°C prior to freezing appeared to be 60 min under the conditions used. The embryos in erythritol survived slow thawing (∼20°C/min), only when cooled slowly to temperatures between − 30 and − 60°C before transfer into liquid nitrogen, and survived rapid thawing (∼500°C/min), only after transfer from − 25 to − 40°C. The highest survival rates of slowly thawed embryos were obtained after transfer to − 196°C from − 35 (63%) and − 40°C (64%), and the highest survival rates of rapidly thawed embryos were obtained after transfer from − 30°C (54%). Mouse embryos that survived freezing and thawing with erythritol as the cryoprotective agent were capable of developing to full‐term fetuses.
Light and time correlated migration of invasive hemocytes in the crayfish compound eye
Authors: Waterman Talbot H. , Piekos W. Barry
Published: June 2005

The number and radial distribution of hemocytes discovered periodically invading the retinas of crayfish compound eyes (Figs. 1–3) were measured under a variety of light and dark adaptation programs (Fig. 4, Table 1). Overall the density of these cells in the eye was significantly less in light than in darkness (Figs. 5–8, Table 2). The corresponding hemocyte ebb and flow occurred in intercellular spaces between retinulas, not in blood vessels which are absent from decapod crustacean eyes everywhere distal to the basement membrane.

Hemocytes under all conditions were most dense just below the basement membrane. Within the retina their occurrence ranged from maximum at the basement membrane to minimum or zero near the distal tip of the rhabdom, beyond which they rarely occurred (Figs. 5, 6, Table 3). The effectiveness of light in reducing hemocyte concentrations was maximal distally and minimal proximally and hence had a gradient inverse that for cell density (Fig. 8).

Bilateral experiments with one eye covered and the other exposed showed that light could independently and unilaterally induce hemocyte emigration from the retina (Fig. 5). But in time‐of‐day experiments hemocyte movements occurring before the programmed cyclic diurnal illumination changes proved that endogenous control mechanisms must also participate (Fig. 7). Such experiments also showed the fewest retinal hemocytes (≈︁0) at 18:00 hours, when the rate of rhabdom synthesis should be near maximum.

So far no direct phagocytic uptake of identifiable photoreceptor membrane has been found in crayfish retinal hemocytes. Nevertheless these cells were seen to make junctionlike contacts with retinular cells and appeared to be actively ingesting interstitial detritus in the retina at levels coincident with the radial extent of the rhabdoms (Figs. 1–3). Previously phagocytic wandering cells were known to participate in photoreceptor membrane turnover in teleost eyes and in reptile pineal organs although fixed retinal pigment epithelial cells are normally involved in this function in birds and mammals.
Possible involvement of macrophages in embryo–maternal relationships during ovum implantation in the rat
Authors: Tachi C. , Tachi Sumie , Knyszynski Ahuva , Lindner H. R.
Published: June 2005

Distribution of phagocytic cells in the rat endometrium during the estrous cycle and early gestation was examined by histological, electron microscopic, and histochemical techniques. The results show that numerous macrophages emerge around the nidus shortly after the onset of ovum implantation. Such macrophages, however, were not present within the decidua, suggesting that this tissue may be a protective barrier against the migration of phagocytic cells towards the implants. Approximately 48 hours after the onset of implantation, the number of endometrial macrophages decreased dramatically.
Isolation of epithelial cells from the corpus epididymidis and analysis for glycerylphosphorylcholine, sialic acid, and protein
Authors: Hoffmann David S. , Killian Gary J.
Published: June 2005

Enzymatically dispersed cells from the rat corpus epididymidis were separated by unit gravity sedimentation and centrifugal elutriation. Based on differential cell counts, principal cells isolated by centrifugal elutriation were 55% pure, while basal cells and fibroblasts were 88% and 61% pure, respectively. Compared to unit gravity separation, purity was an average of 7% higher in principal and basal cell fractions obtained by elutriation. Viability was>87% by either method, but yields following elutriation averaged 23% higher for basal cells, 78% higher for principal cells, and 290% for fibroblasts than corresponding yields following unit gravity separation. Analyses for epididymal secretory products indicated that cellular content (μutmoles/109 cells) of glycerylphosphorylcholine (GPC), sialic acid, and protein was greater in principal cells than other cell types (p<.05). When expressed on the basis of cellular volume, concentraions of GPC and protein also were significantly greater in basal and principal cells than fibroblasts (p<.05). Caput sperm contained significantly more GPC than either corpus or cauda sperm (p<.005). Protein concentrations in caput and corpus sperm were similar, but concentrations were lower in cauda sperm (p<.005). Levels of sialic acid did not vary among sperm from different epididymal regions. It was concluded that principal cells from the corpus epididymidis contain major quantities of three epididymal secretory products and that regional differences in the function of the epithelium are present.
Alteration of annulate lamellae in the in vitro progesterone‐treated, full‐grown Rana pipiens oocyte
Authors: Kessel Richard G. , Subtelny Stephen
Published: June 2005

In full‐grown but immature Rana pipiens ovarian oocytes, stacks of annulate lamellae are preferentially localized in the ooplasm between the germinal vesicle and the animal pole. Furthermore, the largest stacks of these porous cytomembranes tend to be localized deeper in the ooplasm in proximity to the germinal vesicle, while smaller, but variable‐sized stacks of annulate lamellae are found closer to the oolemma of the animal pole. Manually defolliculated, full‐grown oocytes were cultured in progesterone for periods of 1, 3, 5, 6, 9, 12, 16, 18, and 22 hours at 18°C. Annulate lamellae were observed in the animal pole ooplasm after 1, 3, 5, 6, and 9 hours of in vitro culture in progesterone at 18°C. In contrast, annulate lamellae were not observed in fully grown oocytes cultured in the progesterone for 12, 16, 18, or 22 hours at 18°C. Rather, many localized areas in the animal pole ooplasm were observed that contained large numbers of closely packed vesicles of different size. The largest clusters of vesicles were present in the ooplasm near the germinal vesicle. Progressing toward the oolemma of the animal pole, the vesicular clusters appeared to become smaller in area. These clusters of vesicles were not observed in either untreated control oocytes at 3–22 hours of culture, or in those treated with progesterone for 1, 3, 5, 6, or 9 hours. The results suggest that after the appropriate maturation‐inducing treatment with progesterone, annulate lamellae lose their integrity, probably by a process of vesiculation. This represents one of the first morphological changes which occurs during the induction of meiotic maturation. The alteration of annulate lamellae observed in the progesterone‐treated oocytes occurs prior to complete germinal vesicle breakdown, for under the experimental conditions described, the germinal vesicle nuclear envelope did not completely break down until between 18 and 22 hours of culture in progesterone.
Hyperphagia and the control of ingestion in the female mosquito, Culiseta inornata (Williston) (Diptera: Culicidae)
Authors: Owen William B. , McClain Elizabeth
Published: June 2005

Hyperphagia resulted in all females of Culiseta inornata that were fed 1 M sucrose after the ventral nerve cord was severely damaged or severed in either abdominal segment I, II, or III. Hyperphagia also occurred in 42% of females fed successive higher concentrations of sucrose ranging from 0.25–2.0 M. The conclusions are: (1) Signals from receptors in the anterior abdominal segments limit the intake of sugary liquids; (2) this type of receptor is absent from the ventral diverticulum; and (3) excitatory input from oral receptors may dominate inhibitory input from abdominal stretch receptors.
Developmental properties of induced buds from a nonbudding mutant of Hydra viridis
Authors: Novak Patricia L. , Lenhoff Howard M.
Published: June 2005

The apical portions of the nonbudding mutant of Hydra viridis were induced to bud by grafting to them basal portions of wild type hydra of the same species. The induced buds had unusual developmental and morphogenetic properties that frequently showed characteristics of both wild type and mutant animals. The rate and extent of bud induction varied depending upon the body region of the wild type tissue grafted to mutant tissue. The gastric region induced the most buds at the highest rate. Induced buds containing cells from both the wild type and the nonbudding mutant were referred to as “heterocytes”. Wild type heterocytes were more like the mutant. Mutant heterocytes had regeneration properties characteristic of both the wild type and mutant animals depending upon how long they had been fed. The initial budding rates of the wild type heterocytes varied, but eventually all wild type heterocytes transformed into animals of mutant phenotype. These observations suggest that complex interactions are taking place in the heterocytes composed of cells derived from both the wild type and the nonbudding mutant.
Photo‐thermoperiodic effects on fat stores in the green anole, Anolis carolinensis
Authors: Ferrell Blaine R. , Meier Albert H.
Published: June 2005

A circadian rhythm of thermosensitivity is set by a photoperiodic schedule (LD 12:60) in lizards at 20°C so that the coincidence of 6‐hour thermoperiods (30° C) with a thermosensitive phase is stimulatory for fattening. The thermosensitive phase reoccurs every 24 hours. Thermoperiodism involves circadian mechanisms similar to those which have been described for photo‐periodism.
Effects of pinealectomy and melatonin on the photoperiodic gonadal response of the male lizard Anolis carolinensis
Authors: Underwood Herbert
Published: June 2005

The effects of pinealectomy and exogenous melatonin treatment on the photoperiodic testicular response in the lizard Anolis carolinensis were examined at two times of year. In the summer (July–August) neither pinealectomy nor melatonin affected the photoperiodic response. In the fall (September–October) pinealectomy had a progonadal effect in lizards maintained on either LD 8:16 or LD 14:10 photoperiods. Melatonin blocked the gonadal development in response to pinealectomy on LD 8:16 but melatonin did not inhibit the acceleration in testicular development caused by pinealectomy on LD 14:10. However, melatonin did inhibit testicular development in intact (nonpinealectomized) anoles exposed to LD 14:10.

These results show that pinealectomy can modify testicular function in Anolis, that the effects of pinealectomy are seasonal, and that melatonin may be a reproductively active factor involved.
Immunohistochemical localization of phosphoglycerate kinase isozymes in mouse testes
Authors: Vandeberg John L. , Lee Chi‐Yu , Goldberg Erwin
Published: June 2005

We have used specific antibodies against mouse phosphoglycerate kinase (PGK) isozymes in an immunohistochemical technique to determine which cells in testicular cross sections contain PGK‐A and which contain PGK‐B. Phosphoglycerate kinase‐A is highly concentrated in interstitial cells and is weakly expressed in Sertoli cells and throughout the germinal epithelium. Phosphoglycerate kinase‐B is highly concentrated in spermatids and spermatozoa, but it is not detectable in stage 8 spermatids or earlier gametogenic stages, or in somatic cells of the testis. These results confirm that PGK‐B is a sperm‐specific isozyme in mice.
Loss of pH sensitivity of amino acid incorporation during early development of the horseshoe crab, Limulus polyphemus L
Authors: Bannon G. A. , Shen S. S. , Brown G. G.
Published: June 2005

Embryos of the primitive arthropod, Limulus polyphemus L., exhibit a 5–50‐fold increase in amino acid incorporation approximately 6–8 hours after fertilization, which is not concomitant with cytoplasmic alkalization. Lowering of intracellular pH before this increase occurs will prevent the initiation of amino acid incorporation. However, lowering the internal pH after the increase has occurred does not inhibit the incorporation rate. These results suggest that amino acid incorporation in Limulus embryos is a pH‐sensitive event before the increase occurs, but becomes pH insensitive after the increase in incorporation rate has been initiated.
Linkage disequilibrium between the T/t complex and Pgk‐2 in wild mice
Authors: Rudolph Natalie S. , Vandeberg John L.
Published: June 2005

Linkage disequilibrium between the T/t complex and Pgk‐2 – two loci flanking the murine major histocompatibility complex on chromosome 17‐ has been found in a population of wild mice. By subjecting 78 wild males to progeny testing, we extracted 15 recessive t haplotypes of the T/t complex and assigned 12 of them to the tw5 complementation group. We also determined the allelic phase of T/t, Pgk‐2, and Ce‐2 on both chromosomes from each wild male. The allele Pgk‐2c was always associated with a t haplotype, although the converse was not true.
Haemolymph gas transport, acid‐base regulation, and anaerobic metabolism during exercise in the land crab (Cardisoma carnifex)
Authors: Wood Chris M. , Randall D. J.
Published: June 2005

Haemolymph gases, acid‐base status, and metabolite levels were studied in Cardisoma carnifex at rest and after 10 minutes of mild (0.2 body lengths/second) or severe (exhausting, 0.5 BL/second) exercise. O2 transport is very similar to that in aquatic crabs. At rest, arterial haemocyanin saturation is ≃ 87%, venous saturation is ≃ 45%, and tissue utilization is ≃57%. During exercise, Ṁ rises 2–3‐fold. Ps fall so that O2 transport is shifted onto the steep part of the dissociation curve, venous saturation decreases markedly while arterial saturation remains high, and cardiac output rises. These adjustments raise the P gradient at the respiratory surface, tap the haemolymph O2 store, and maintain or increase the a–v O2 difference so that utilization reaches ≃82%. Postexercise acidosis augments these effects via the Bohr shift. Resting P's are low (≃15 torr) for an air‐breather, and Pa changes minimally despite 2.5–5‐fold evaluations in Ṁ. All haemolymph gas levels return to normal within 0.5–1.0 hours. Postexercise acidosis is largely metabolic, and smaller than in aquatic crabs. Lactate anions and protons enter the haemolymph in equivalent amounts and totally account for the metabolic acidosis. Elevated NH3 and pyruvic acid levels have negligible influence. During recovery, the metabolic acid load is reduced faster than the lactate load, resulting in alkalosis, possibly because of CaCO3 mobilization from the carapace. Exercise metabolism appears largely anaerobic, but changes in haemolymph lactate levels do not correlate with the O2 debt. However, the “excess lactate” concept which compensates for pyruvate elevation gives a good index of the debt. All changes are more marked after severe than after mild exercise, but the patterns are similar.
Localization of protein absorption during transport of food in the intestine of the grasscarp, Ctenopharyngodon idella (Val.)
Authors: Stroband H. W. J. , van der Veen F. H.
Published: June 2005

The uptake of protein and amino acids in the intestine of young (18 months old) and adult grasscarp has been studied with the inert marker (Cr2O3) method. The absorption of protein takes place in the anterior 40–50% of the gut.

The second intestinal segment (± 25% of gut length) has the ability to absorb macromolecules of protein. Ferritin (mol wt 400,000) was found in pinocytotic vesicles in enterocytes of this second segment. On the basis of morphological and histochemical evidence, it has previously been suggested that the pinocytotic uptake of whole protein molecules might be related to the lack of peptic digestion in stomachless fishes. A major quantitative function in protein absorption, however, cannot be attributed to the second gut segment, and proteins appear to be digested adequately in these stomachless animals. The function of this part of the gut and the role of the stomach in protein digestion in other vertebrates remain to be explained.

The absorption of individual amino acids in the intestine of the grasscarp suggests that essential amino acids are preferentially absorbed. The rapid disappearance of lysine and arginine from the chyme points to a tryptic breakdown of proteins.