bluuebunny/crossref_metadata_2025 huggingface dataset:
Chloride shift in fish blood
Authors: Cameron James N.
Published: June 2005

When the physically dissolved CO2 is suddenly increased or decreased in whole blood of red snapper at 24° C, or rainbow trout at 14° C, the plasma Cl− falls or rises with a time constant of 0.35 or 0.40 sec, respectively. The reaction is completely blocked by the carbonic anhydrase inhibitor, acetazolamide. This “chloride shift” provides a rapid dehydration pathway for excretion of the CO2 bound as HCO3. These results would seem to contradict the theory that fish RBC's are impermeable to HCO.
Nerve trophic effects: An in vitro assay for factors involved in regulation of protein synthesis in regenerating amphibian limbs
Authors: Choo Alfred F. , Logan David M. , Rathbone Michel P.
Published: June 2005

We have developed a rapid sensitive test for factors that mimic the trophic effects of nerves by maintaining normal rates of protein synthesis in denervated forelimb blastemata of adult newts (Notophthalmus viridescens). Rates of protein synthesis in secondary blastemata are similar. However, after they are denervated and explanted into organ culture the rates of protein synthesis first increase and later fall below control values. Similar changes occur after denervation in vivo. The alterations in the rates of protein synthesis are prevented by adding to the culture medium aqueous extracts from brains of adult newts or chicken embryos. The active material is either a peptide or a protein.
Detrimental effect of visible light on meiosis of mammalian eggs in vitro
Authors: Hirao Y. , Yanagimachi R.
Published: June 2005

Short wavelength visible light (<470–480 nm) emmitted from ordinary light sources is detrimental to unfertilized hamster eggs in that prolonged exposure to the light disturbs the completion of normal meiosis after the eggs are penetrated by spermatozoa. The fluorescent light commonly used in modern laboratories is more harmful than the light from incandescent lamps. In experiments involving the handling of eggs in vitro, minimal exposure to the light or the use of appropriate filters (e.g., red cellophane sheets) is recommended.
Homopolar grafting in Blepharisma japonicum
Authors: Kumazawa H.
Published: June 2005

Results of homoplastic grafting in Blepharisma japonicum v. intermedium are described. The parabiotic homopolar fusion complex of two cells either simply splits into two singlets, or undergoes cell division. In the latter case the division results either in two doublets or in two singlets (proters) and a doublet (opisthe). If one or two of the systems of feeding organelles are removed after parabiotic homopolar fusion of two cells, the fusion complex does not split, but undergoes division. If an almost complete set of feeding organelles is lacking, the division of the graft complex usually results either in a singlet proter and a doublet opisthe or in two doublets. If two complete sets of feeding organelles have been excised from the graft complex, division occurs after the regeneration of the missing organelles, most frequently resulting in two doublets. The same operation on the graft complex with two primordium sites placed very close to each other may result in the regeneration of one normal and one reversed peristome, the latter being to the right of the former. The doublet biotypes derived from the graft complexes with or without further experimental changes usually reproduced true to type. The asymmetric doublet with two peristomes less than 180° apart tends to resorb the left peristome, that is, one with a larger left‐hand somatic area than the other. The asymmetric doublet may also form a third peristome on the right side of the original left peristome. The third peristome is usually of reversed asymmetry. That the appearance of the third primordium site might be due to the presence of the original line of fusion of two components of the doublet, and that the tendency of the original primordium sites to reestablish themselves might give rise to the third one, when the original ones fail to be kept away from one another, are discussed.
The influence of temperature adaptation on the composition of the neutral lipid fraction of rainbow trout (Salmo gairdneri) liver
Authors: Hazel Jeffrey R.
Published: June 2005

Rainbow trout (Salmo gairdneri) acclimated to 20°C possessed significantly greater quantities of total neutral lipid, triglyceride, and free fatty acids, and smaller quantities of hydrocarbons in their livers than 5°C‐acclimated animals. Regardless of acclimation temperature the relative abundance of the various neutral lipid classes was triglyceride > cholesterol ester > free cholesterol > diglyceride > free fatty acid > wax ester and hydrocarbon. Two patterns of compositional change were observed in response to alterations in environmental temperature. Depot lipids (triglyceride and wax ester) became more unsaturated at lower ambient temperatures due primarily to moderate increases in the content of monoenes, and larger increases in the content of both dienes and polyunsaturates. Increased unsaturation of the triglyceride fraction was mediated primarily by an accumulation of unsaturates belonging to the linoleic and linolenic acid families, whereas oleate‐ and linoleate‐derived fatty acids accumulated in the wax ester fraction. The remaining neutral lipid fractions (free fatty acids, diglycerides, and cholesterol esters) all experienced a decline in the content of unsaturated fatty acids at reduced temperatures due primarily to a loss of monoenes from each fraction and a loss of dienes from the diglyceride and cholesterol ester fractions; unsaturated fatty acids belonging to the oleate family were preferentially lost from these neutral lipids upon cold acclimation. These results suggest that in response to a reduction in environmental temperature, a reorganization of lipid metabolism occurs which in volves a selective uptake of predominantly linolenate‐derived unsaturated fatty acids into phospholipids and linoleate‐derived unsaturated fatty acids into depot lipids, resulting in a free fatty acid fraction enriched in saturated fatty acids.
Dissociation and separation of Xenopus laevis spermatogenic cells
Authors: Risley Michael S. , Eckhardt Ronald A.
Published: June 2005

Methods have been developed for the dissociation and fractionation of spermatogenic cells of the South African clawed frog, Xenopus laevis. Testis cells were dissociated with collagenase to obtain cell suspensions (1.2 × 10 8 cells/testis) highly enriched for spermatogenic cells (99.5%). The only testicular somatic cells present in the suspensions in significant numbers were Sertoli cells with mature spermatids embedded in their cytoplasm. Spermatogenic cells prepared by this method exhibited consistently high viabilities (98.7%) as measured by their ability to exclude Trypan blue dye. Subsequent to the dissociation procedure, spermatogenic cells were separated into fractions, each of which was highly enriched for a specific developmental stage, by unit gravity sedimentation and isopycnic centrifugation in Metrizamide gradients. The entire dissociation and fractionation procedure required approximately nine hours to complete and was used to separate as many as 5 × 109 cells with no apparent cytotoxic effects.
Macrocyst formation in the cellular slime mold Dictyostelium mucoroides: Involvement of light and volatile morphogenetic substance(s)
Authors: Filosa Michael F.
Published: June 2005

In the dark, cultures of Dictyostelium mucoroides produce macrocysts while in the light fruiting bodies are formed. However, dark cultures will form fruiting bodies if grown over activated charcoal indicating that some gas or volatile substance is involved. Light cultures will form macrocysts when grown over CO2 absorbents (eg. KOH). If light cultures are grown over both KOH and activated charcoal only fruiting bodies are formed. A light‐mediated reaction involving CO2 assimilation may prevent the synthesis or utilization of the volatile substance needed for macrocyst formation.
HCO3‐stimulated CL efflux in the Gulf toadfish acclimated to sea water
Authors: Kormanik Gregg A. , Evans David H.
Published: June 2005

Unidirectional efflux of Cl was examined in the Gulf toadfish, Opsanus beta, in artificial seawater solutions with modified concentrations of Cl and HCO3. Removal of Cl and HCO3 reduced Cl efflux. Addition of HCO3 at typical seawater concentrations stimulated Cl efflux, independent of changes in the transepithelial potential. This active, HCO3‐stimulated Cl efflux is saturable, with a Km of 2.4 mM, typical of the concentration of HCO3 found in sea water, and independent of external pH. Active extrusion of Cl offsets the net diffusional and oral gain of Cl faced by O. beta in sea water.
Regenerative responses in larval axolotl limbs with skin grafts over the amputation surface
Authors: Tassava Roy A. , Garling David J.
Published: June 2005

Complete flaps of whole skin over the amputation surface of larval axolotl limbs did not prevent dedifferentiation, DNA synthesis, and mitosis. However, even by two weeks, insufficient cell division had occurred for blastema formation. In about 50% of the cases, small areas of wound epidermis formed over the amputated tip of the radius or ulna. At two weeks after amputation, mitotic figures and dedifferentiated cells which incorporated H3‐thymidine were predominantly located in the vicinity of the small area of wound epidermis. Although delayed in relation to controls, these limbs regenerated.

The results are consistent with the view that the wound epidermis is necessary to maintain dedifferentiated cells in the cell cycle.
Solute compatibility with enzyme function and structure: Rationales for the selection of osmotic agents and end‐products of anaerobic metabolism in marine invertebrates
Authors: Bowlus R. David , Somero George N.
Published: June 2005

The major nitrogenous osmolytes present in the cells of marine invertebrates, notably the free amino acids glycine, alanine and proline, and trimethylamine oxide and betaine, are highly compatible with proper enzyme function and structure. These nitrogenous osmolytes display either nonperturbing or, in some cases, favorable effects on enzyme‐substrate and enzymecofactor complex formation, catalytic velocity and protein structural stability. In contrast, inorganic salts (KCl and NaCl) and certain of the free amino acids which play only a minor osmotic role, e.g., arginine and lysine, have galy perturbing effects on one more of these enzymic parameters. The compatible nitrogenous solutes therefore are suitable for use at high (several tenth molar) contcetrations and at widely varying consentrations in osmo conferming species.

Certain nitrogenous solutes, especially trimethyline oxide, betaine and glutamate, offset some of the perturbing effects of inorganic ions on enzyme fuction. The selective accumulatin of osmolytes thus unvolves not only the concentration of non‐perturbing solutes, but also a balanced accumulation of solutes with opposing effects on enzumes.

The selection of end‐products of anaerobic metabolism also appears to be based, in part, on considerations of solute compatibility with enzyme fuction. Octopine is a non‐perturbing solute, whereas arginine, which is condensed with pyruvate to form octopine, is very strongly perturbing. Succinate has marked stabilizing effects on protein structure.

We conclude that the composition of the intracellular fluids of marine invertebrates reflects selection for osmolytes and end‐products whose net effects create a cellular microen vironment which is conducive to otimal enzyme fuction and structure. The accumulation of compatible solutes may preclude the necessity for widespread changes in protein structure in adapting to concentrated or highly variable osmotic environments.
Intermediate filaments connect Z‐discs in adult chicken muscle
Authors: Price Maureen , Sanger Joseph W.
Published: June 2005

When adult chicken skeletal myofibrils are treated with a myosin‐extracting solution, the Z‐discs with attached actin filaments retain their linear connections with one another in the extracted myofibril. The sarcomere length increases in the extracted myofibrils from a control length of 2.5 μm up to 6 μm. In a sarcomer, eight to fifty 10 nm filaments can be seen in parallel array in the H‐zone. The 10nm‐wide filaments do not bind heavy meromyosin and are two to four μm in length. These intermediate filaments are postulated to be an integral part of the sarcomere, connecting Z‐bands along the length of the myofibril.
Periodic breathing in the crocodile, Crocodylus niloticus: Consequences for the gas exchange ratio and control of breathing
Authors: Glass M. L. , Johansen K.
Published: June 2005

The ventilatory pattern in the Nile crocodile consists of episodes of breathing, interrupted by periods of breath‐holdin, the latter occupying 80% of total time during normal breathing at 25°C.

End‐tidal gas composition varied with the periodic breathing but Po2 was always high (Po2<110 torr) and Pco2 low (Pco2<25 torr). The alveolar gas exchange ratio, RE, was very low during the non‐ventilatory periods (RE ≃ 0.5), but increased markedly during ventilation.

Breathing of hypoxic and hypercapnic gases caused a pronounced decrease in the duration of breath‐holds. Hypercapnia decreased breathing frequency during ventilatory periods, but increased tidal volume.

The results are discussed in relation to the practice of prolonged breath‐holding associated with diving in crocodiles.
DNA reassociation kinetics in diploid and phylogenetically tetraploid cyprinidae
Authors: Mauro Maria Luisa , Micheli Gioacchino
Published: June 2005

Four diploid and three phylogenetically tetraploid Cyprinidae (Ostariophysi) have been characterized as for nuclear DNA content, modal chromosome number and DNA reassociation kinetics (hydroxyapatite chromatography).

Among the diploid species nuclear DNA content (10−12 g DNA/2C) was 1.62 for Tinca tinca, 1.87 for Scardinius erythrophthalmus, 2.53 for Leuciscus cephalus and 2.75 for Alburnus alburnus, while the phylogenetically tetraploid species Carassius auratus, Barbus barbus and Cyprinus carpio attained 3.40,3.66 and 3.80 respectively. Modal chromosome number was 2n = 48–50 for diploid individuals and 2n = 100–104 for phylogenetically tetraploid ones. In all the species 5–8% of the genome is represented by highly repetitive and foldback DNA. In DNA reassociation kinetics of phylogenetically tetraploid Cyprinidae a distinct plateau separates an intermediate reassociating sequence fraction (about 22% of the genome; with average repetition frequencies between 1,000 and 1,400) from a slow reassociating one (unique DNA; about 72% of the genome). These two genome fractions are not clearly distinguishable from each other in Cot curves of the diploid Cyprinidae, where a similar plateau is not evident.

Since simple ploidy changes are not expected to affect DNA reassociation kinetics we suggest a different evolution in the genome organization of the two ploidy groups. Some possible hypotheses are discussed.
Dependence of oral development and cleavage on cell size in the ciliate Stentor
Authors: de Terra Noël
Published: June 2005

In Stentor, the two main cytoplasmic events of cell division are development of the oral primordium that gives rise to the oral apparatus of the posterior daughter cell and cleavage. The present work examines directly the dependence of these two events on the size of the cell body. Cell body size was reduced by various amounts with a microneedle during early stages of cell division and the effects on oral development and cleavage observed. The oral primordium was always resorbed and cleavage never occurred when the cell body was reduced to one quarter of its original size at Stage 3 of cell division; appropriate controls showed that this result was not caused by operation injury. Progressively smaller reductions in cell size yielded correspondingly lower percentages of inhibited cells. These data suggest that the mechanisms underlying the dependence of oral development and cleavage on cell size do not involve accumulation of regulator substances up to a critical concentration during interphase. The fact that oral development can be reversed by reducing cell body size supports the hypothesis that oral development and cell division are initiated when the oral apparatus becomes disproportionately small in relation to cell body size as a result of interphase growth. The size‐dependence of cleavage is probably best understood as a mechanism for regulating cell size in Stentor.
Effect of seasonal variation on immune system of the lizard, Scincus scincus
Authors: Hussein M. F. , Badir N. , El Ridi R. , El Deeb S.
Published: June 2005

In winter, the lizard, Scincus scincus, fails to form humoral antibodies to parenterally introduced rat erythrocytes. The response is slow and feeble in spring whereas, it is quick and vigorous in summer and autumn. In winter, the thymus of Scincus is involuted, white pulp of spleen highly depleted while, gut‐associated lymphoid tissue is rather developed. By the beginning of spring, lymphoid organs start to regenerate. By the end of spring through midfall, the thymus presents a rich lymphoepithelial organization; splenic lymphoid aggregates are so developed that they become confluent and gut aggregates increase in number and size. The data suggest that, the kinetics and magnitude of the lizard's humoral response to foreign erythrocytes, correlate with the state of lymphoid tissue development which, in turn, is affected by seasonal variations.
Fatty acid and sterol synthesis by hepatocytes of thermally acclimated rainbow trout (Salmo gairdneri)
Authors: Hazel Jeffrey R. , Sellner Peggy A.
Published: June 2005

Incorporation of tritium from tritiated water into lipid fractions was measured in isolated hepatocytes from rainbow trout (Salmo gairdneri) acclimated to 5°C and 20°C. Hepatocytes from cold‐acclimated trout exhibited significantly higher rates of tritium incorporation into both fatty acid and sterol fractions at assay temperatures of 15°C and 20°C than did hepatocytes from warm‐acclimated trout. Tritium incorporation into the fatty acid fraction was nearly temperature independent in hepatocytes from warm‐acclimated trout (Q10 = 1.39) but markedly temperature dependent (Q10 = 2.63) in hepatocytes from cold‐acclimated trout; in contrast, rates of sterol synthesis were more temperature dependent in warm‐acclimated trout. At 5°C, fatty acid lipogenesis comprised a significantly greater percentage of the total tritium incorporation in hepatocytes from warm‐acclimated trout and the percentage of total lipogenesis attributable to fatty acids decreased significantly in warm‐acclimated trout as the assay temperature increased; the opposite trends were observed in cold‐acclimated trout.
Effect of activity of lateral cilia on transport of amino acids in gills of Mytilus californianus
Authors: Wright Stephen H.
Published: June 2005

The effect of 5‐hydroxytryptamine (5‐HT) on influx of 14C‐glycine in isolated gills of Mytilus was studied. 5‐HT was observed to induce metachronal activity of lateral cilia in in vitro preparations of gills of M. californianus and M. edulis. Active lateral cilia were capable of increasing perfusion of isolated gills of M. californianus, as demonstrated by a significant reduction in the t1/2 for washout of 14C‐inulin from gills treated with 5‐HT. Application of 5‐HT at a concentration of 10−5 M increased influx of 1 μM 14C‐glycine in isolated gills of M. californianus from control values of less than 0.1 μmoles/(g‐hr) to 0.5 μmoles/(g‐hr). Influx of 1μM glycine in gills from M. edulis treated with 5‐HT was more than 700% of control values. 5‐HT had no effect on uptake of glycine in intact, actively pumping M. californianus, indicating that 5‐HT's effect on transport in isolated gills is a result of activating lateral cilia rather than a direct effect on the transport process. The Michaelis constant for influx of glycine was reduced from a control value of 44 μM to 20 μM by treatment of gills from M. californianus with 5‐HT. These observations are consistent with the hypothesis that in vitro preparations of mussel gill have unstirred layers that introduce a significant bias into determinations of transport kinetics. Extrapolation of results obtained with isolated gills to intact animals is dubious.
Germinal vesicle configurations and patterns of polypeptide synthesis of porcine oocytes from antral follicles of different size, as related to their competency for spontaneous maturation
Authors: McGaughey Robert W. , Montgomery Deborah H. , Richter Joel D.
Published: June 2005

The cytogenetic configurations of germinal vesicle (gv) chromatin were analyzed for pools of porcine oocytes harvested from small (1.0–2.0 mm), medium (3.0–5.0 mm), and large (6.0–10.0 mm) antral follicles. Groups of oocytes from these follicular classes also were examined by high‐resolution, two‐dimensional, polyacrylamide gel electrophoresis to compare their patterns of polypeptide synthesis. The results show a high incidence of gross and cytogenetic degeneration among oocytes from small antral follicles as compared with those from medium or large follicles. Pools of oocytes could be separated, on the basis of gross morphology and integrity of adherent granulosa cells, into two classes: “Type A” which appeared normal, and “type B” which appeared to be atretic. Among selected “type A” oocytes a particular chromatin configuration, termed “fibrous” characterizes the gv of oocytes from small follicles; whereas a different configuration, termed “diffuse,” characterizes the gv of oocytes from large follicles. The patterns of polypeptide synthesis were markedly different for samples of “type A” oocytes of the three follicular classes; and the patterns for oocytes from medium and large follicles were more similar to each other than to patterns for oocytes from small follicles. The incidences of maturational development beyond the gv stage in vitro were similar for “type A” oocytes from the three follicular classes (i.e., 66% to 82% maturation); although “type B” oocytes underwent maturation beyond the gv at a significantly reduced incidence (i.e., 20% to 29% maturation). “Type A” oocytes from large follicles completed maturation in vitro (i.e., underwent the first meiotic division) at a significantly higher incidence (55%) than did oocytes from small (11% to 20%) or medium (16%) follicles. Our findings are consistent with the hypotheses that a high proportion of oocytes from small antral follicles are atretic, and that a developmental program controls the molecular and cytogenetic changes occurring in porcine oocytes during follicular growth. These changes appear to be highly correlated with the acquisition of competency to complete maturation in vitro, and possibly also are required for normal fertilization and embryogenesis.
Creatine kinase gene expression during the development of Brachydanio
Authors: Pontier Paul J. , Hart Nathan H.
Published: June 2005

The ontogeny of creatine kinase (CK) in Brachydanio rerio, B. albolineatus and hybrids formed by their reciprocal crosses was investigated using electrophoretic and spectrophotometric methods. Creatine kinase existed in three homodimeric isozymes in tissues of both species: an eye‐brain predominant CK‐B2 form, a skeletal muscle predominant CK‐A2 form, and a stomach specific CK‐C2 form. Zebra and pearl danio embryos exhibited identical progressions of CK isozymes through four days postfertilization. The CK‐B2 isozyme was continuously expressed and was the only CK form present from Stage 1 (fertilization) through Stage 20 (optic cup). The CK‐A2 isozyme initially appeared at Stage 21. Its expression correlated temporally with slow, irregular contractions of the trunk and early differentiation of the trunk somites into myoblasts. Spectrophotometric analysis of total CK showed a sharp decline in activity during the first 10 hours of development (i.e., until the end of gastrulation). Total CK activity remained low until the appearance of the CK‐A2 isozyme.

Embryos of reciprocal crosses between B. rerio and B. albolineatus displayed similar patterns of expression of both CK‐B2 and CK‐A2 isozymes. The paternal Ck‐B locus was first expressed in hybrid embryos at 48 hours postfertilization in the form of the CK‐BABR heterodimer. The paternal CK‐B2 homodimer was detected in embryos at 55 hours postfertilization. The parental alleles of the Ck‐B locus were synchronously expressed. The pattern of CK‐A2 expression in hybrids followed a pattern similar to that in intraspecific crosses.

Experiments with actinomycin D and cycloheximide supported our previous studies which indicate that nuclear genes of multilocus isozyme systems in Brachydanio are activated during gastrulation. Results of exposing B. rerio embryos to actinomycin D showed that transcription of template RNA coding for the CK‐A2 isozyme occurred during an 8‐hour interval beginning at mid‐gastrulation or about 12 to 20 hours prior to Stage 21. The initial translation of the CK‐A2 template RNA began 15 hours following transcription or five hours prior to the detection of the first enzyme molecules.
Interspecific heterokaryons between oocytes and blastomeres of the mouse and the bank vole
Authors: Bałakier H.
Published: June 2005

Interspecific hybrid cells were produced using Sendai‐virus‐mediated fusion of interphase blastomeres from 2‐cell embryos with ovulated oocytes of the mouse and bank vole. Under the influence of the cytoplasm of' oocytes (arrested in metaphase II) premature chromosome condensation occurs in the nuclei of blastomeres, thus implying that the cytoplasmic factor which induces chromosome condensation is not species specific, at least not between these two species.
A comparison between oocyte growth in coculture with granulosa cells and oocytes with granulosa cell‐oocyte junctional contact maintained in vitro
Authors: Eppig John J.
Published: June 2005

Evidence is presented that strongly supports the hypothesis that the junctional association between oocytes and granulosa cells must be maintained to promote oocyte growth and development in vitro and that the coculture of oocytes with granulosa cells is not a sufficient condition for oocyte development. Furthermore, it is shown that incorporation of uridine and leucine by oocytes into TCA‐insoluble material is significantly greater in granulosa cell‐enclosed oocytes than in cocultured oocytes.
Pigment synthesis in the Himalayan mouse
Authors: Kidson Susan , Fabian Barry
Published: June 2005

The effect of temperature on pigment synthesis in adult and juvenile Himalayan mice was investigated. Since pigment synthesis only occurs in actively growing hair, adult mice were plucked to induce hair growth. The extent of darkening of the hair was recorded by photography against a reference scale. The presence of pigment granules in hair follicles was investigated histologically. Housing adult and juvenile mice at 15° C results in the synthesis of pigment in growing hair follicles whereas housing at 30° C results in the absence of pigment granules in the growing hair follicles.
Acclimation to successive short term salinity changes by the bivalve Modiolus demissus. I. Changes in hemolymph osmotic concentration, hemolymph ion concentration and tissue water content
Authors: Strange Kevin B. , Crowe John H.
Published: June 2005

The response of Modiolus demissus to successive short term osmotic stress, such as may be experienced on a daily basis during normal tidal fluctuations, was investigated. Results indicate that if M. demissus uses valve closure as a means of avoiding temporary salinity change, the period of time during which it does so must be very short. Animals were found to be essentially in osmotic equilibrium with their environments within three hours of exposure to new salinity regimes.
Fertilization of hamster eggs in vitro at sperm:Egg ratios close to unity
Authors: Bavister B. D.
Published: June 2005

Hamster epididymal spermatozoa were washed and preincu‐bated at extremely low sperm concentrations (100/ml or less) in a culture medium containing naturally‐occurring sperm motility‐stimulating substances. These substances were partially purified “sperm motility factor” (SMF) derived from hamster adrenal glands and catecholamines (epinephrine or isoprotere‐nol). After preincubation for three hours, a small number (5 or less) of washed, cumulus‐free hamster eggs was added to each sperm suspension. Many of these eggs were undergoing fertilization when examined two to three hours later. Fertilization was accomplished in vitro at sperm:egg ratios approaching 1:1, a situation comparable to that believed to exist in vivo. It appears that this demonstration will considerably enhance the potential of in vitro fertilization studies for providing useful information on mammalian gamete interactions.
Nuclear requirement for post‐maturational cortical differentiation of amphibian oocytes: Effects of cycloheximide
Authors: Schuetz Allen W. , Samson Douglas
Published: June 2005

Cycloheximide induced a complex series of alterations in the cortical cytoplasm of amphibian (Rana pipiens) oocytes undergoing steroid induced nuclear and cytoplasmic maturation in vitro. The morphological changes were described and the role of nuclear‐cytoplasmic interactions in the induction of these changes was investigated in intact, enucleated and enucleated‐reinjected oocytes. Three stages of cortical changes were ascertained on the basis of: localized alterations at the animal pole, redistribution of pigment and localized contractility (furrow formation) primarily along the animal:vegetal pole axis. The extent and type of cortical alterations varied depending upon the time at which oocytes were examined following hormonal stimulation and cycloheximide treatment. Cycloheximide did not produce cortical alterations in non‐hormone treated oocytes nor in steroid treated oocytes until after germinal vesicle breakdown. Nuclear and cytoplasmic maturation and the appearance of cortical alterations were all inhibited when cycloheximide was added to oocytes at the time of steroid treatment. Cycloheximide induction of cortical alterations occurred only after the inhibitor was no longer effective in preventing germinal vesicle breakdown.

Enucleated oocytes underwent cytoplasmic maturation in response to the steroid but exhibited no cortical alterations following the delayed addition of cycloheximide. Simultaneous administration of cycloheximide and steroid to enucleated oocytes inhibited cytoplasmic maturation and all observable cortical alterations. Reinjection of nuclear material into enucleated oocytes restored the ability of cycloheximide to induce cortical alterations following steroid induction of cytoplasmic maturation. Without steroid treatment, such reinjected oocytes did not exhibit cortical changes in response to cycloheximide. The data demonstrate that the nucleus is required for and contains a factor(s) which controls the cycloheximide response and post‐maturation differentiation of the oocyte. The maturational changes in the cortical cytoplasm appear to be dependent on the intermixing of the germinal vesicle nucleoplasm materials with mature cytoplasm following germinal vesicle breakdown. The results further suggest that the cortical effects of cycloheximide are dependent upon the initiation of protein synthesis during this period of oocyte development. The significance of these observations and experimental studies are discussed in relation to current understanding of the molecular mechanisms controlling meiosis induction and the composition of the germinal vesicle.
Initial stages of sperm penetration into the egg of Fundulus heteroclitus
Authors: Brummett Anna Ruth , Dumont James N.
Published: June 2005

Very little information is available about the morphological details of sperm‐egg fusion in teleosts. The acrosomeless teleost sperm gains access to the egg cytoplasm through a small opening (the micropyle) in the egg envelope (the chorion). Identification of the micropyle, therefore, permits one to localize the sperm entry site and to use the electron microscope to study the details of sperm‐egg fusion under normal monospermic conditions. In this study freshly stripped eggs of Fundulus heteroclitus were inseminated with sperm of the same species and exposed to fixative at intervals varying from 1 second to 15 minutes after insemination. The scanning electron microscope was used to observe morphological aspects of the initial stages of fertilization.
Neural regulation of cholinesterase in newt skeletal muscle. II. The effects of denervation and of culture in vitro
Authors: Rathbone Michel P. , Vickers John D. , Ganagarajah Mailvaganam , Brown Judy A. , Logan David M.
Published: June 2005

The effect of denervation in vivo on the acetylcholinesterase (AChE) of newt (Notophthalrnw uiridescens) triceps muscle was compared with the effect of culturing explanted muscles in organ culture. Two weeks after denervation, the AChE activity of triceps muscles falls to approximately 60% of that in innervated muscles. The initial rate of loss of AChE is more rapid during summer than during winter, but no seasonal differences were observed in the specific activity of AChE in innervated muscles or in muscles two weeks after denervation. Changes in AChE activity when the triceps muscles were maintained in organ culture were similar in rate and in extent to those that occurred after denervation in vivo.

The effect of denervation in vivo and culturing upon the individual AChE species separated by velocity sedimentation was also determined. Denervation and organ culture both resulted in a marked and rapid loss of two forms of AChE with sedimentation coefficients of 16.5S and 12.8S on sucrose density gradients. The former is associated with the motor endplates and the latter with the musculotendinous junctions. The activity of another form of AChE, with a sedimentation coefficient of 9.8S, transiently increased after denervation, but after one week returned to the initial level. The activity of a major form of AChE, with a sedimentation coefficient of 5,5S, remained constant after denervation, but that of the slowest sedimenting form (3.7S) declined slightly after one week. Similar alterations in the activities of these forms were observed in cultured muscles. Co‐culture of the muscles with dorsal root (sensory) ganglia from newts prevented both the loss of total AChE activity and the alterations in molecular forms of AChE in the muscles. This innervation‐like effect of the ganglia is apparently mediated by a diffusible factor(s) since ganglia separated from the muscles by a Millipore filter (0.22 μm pore size) also prevented alterations in AChE activity and molecular forms in the cultured muscles.

These results demonstrate that the response of AChE to the absence or presence of nervous tissue, apparently mediated by a neurotrophic factor, is identical to that observed in vivo, at least in the case of the characteristics examined.
Failure of human spermatozoa to penetrate zona free mouse and rat ova in vitro
Authors: Quinn P.
Published: June 2005

When incubated for 8 to 26 hours with zona‐free mouse or rat ova, human spermatozoa failed to attach to or penetrate any of the ova. The ova were capable of being fertilized since both intra‐ and inter‐species penetration of spermatozoa and formation of pronuclei occurred between rat and mouse gametes. When mouse spermatozoa were incubated for three to eight hours with rat ova, a high proportion of the ova were penetrated, formation of pronuclei occurred and in 9 out of 36 ova incubated for 40 hours after insemination, regular cleavage and formation of morphologically normal 2‐cell embryos occurred. Human spermatozoa retained their morphological integrity and motility only when the culture medium contained purified bovine serum albumin (3 mg/ml) or human serum (5% v/v) and not when unpurified BSA from several different commercial sources was used as a protein source. In this latter medium, the ova of both rats and mice degenerated after 8‐hour incubation in the presence of human spermatozoa but not when human spermatozoa were absent or in the presence of either rat or mouse spermatozoa. Electron microscopy indicated that the human spermatozoa incubated for eight hours in medium containing purified BSA had undergone an acrosome reaction. These spermatozoa also attached to and penetrated human oocytes which had been matured in vitro.
Short period interspersion pattern in the genome of a teleostean fish
Authors: Serra Virginia , Mandarino Rosina
Published: June 2005

Sequence interspersion in the genome of Salmo trutta has been investigated by means of reassociation kinetics of DNA fragments of 0.5 and 2.5 Kb double‐stranded fragment lengths. Preliminary results indicate that only 34% of the trout genome presents a short period interspersion pattern, the remainder seems to be composed of unique and repeated sequences longer than 2.5 Kb.
Salt and water balance in the oligohaline clam, Rangia cuneata II. Accumulation of intracellular free amino acids during high salinity adaptation
Authors: Henry Raymond P. , Mangum Charlotte P. , Webb Kenneth L.
Published: June 2005

During adaptation to an increase in ambient salinity (2–20 ppt) the estuarine clam Rangia cuneata enlarges the pool of free amino acids in adductor muscle fibers by more than five‐fold (>300 μM/gm dry wt). The process can occur under anaerobic conditions, but oxygen is critical to survival during high salinity adjustment. It is suggested that the pool may be enlarged by de novo synthesis, via a modified form of glycolysis perhaps involving the direct amination of pyruvate to form alanineutilizing free ammonia.
Ovarian development in an opportunistic breeder, the Zebra Finch Poephila guttata castanotis
Authors: Sossinka Roland
Published: June 2005

In opportunistic breeding species living in unpredictable environments, gonadal development and activation should be quite different from that in periodically breeding species, which live in an environment with highly predictable changes. In Australian Zebra Finch females, bred in laboratories, the development during ontogeny was investigated. Body growth, ovarian weight, and the diameter of the largest follicle were recorded in birds 10 days to some years of age. A linear follicle growth pattern from 10 to 100 days is followed by a resting phase, during which the follicles remain in a medium‐developed resting state. As soon as favorable conditions occur, a rapid logarithmic growth and yolk deposition starts, leading to ovulation within one to two, weeks. Egg laying sometimes occurs as early as day 90. The ovary as a whole reaches a medium‐developed resting state much later, but remains in this state even during long nonbreeding intervals.

Compared with photoperiodically breeding species, for example Zonotrichia leucophrys gambelii, the Zebra Finch has the disadvantage of permanently keeping its gonads activated. Because of the lack of proximate factors, the Zebra Finch has to respond to the appearance of the ultimate factors as quickly as possible. Activation of fully regressed ovaries would take too much time, but starting from a medium‐developed resting state allows ovulation in less than two weeks. In addition, no detectable refractory period reduces the capacity to respond. In the young this causes precocity.

These peculiarities have been selected for by the sporadic and erratic rainfalls, which cause the unpredictability of breeding periods in several parts of Australia.
Effect of hydrostatic pressure on morphogenesis in nerve‐free hydra
Authors: Wanek Nancy , Marcum Beverly A. , Lee Hsueh‐Tze , Chow Margaret , Campbell Richard D.
Published: June 2005

Tissue stretching was controlled in hydra which lack nerves by preventing the accumulation of osmotic fluid within the gastrocoelic cavity. Hydra lacking nerves (epithelial hydra) became highly distended and swollen during the course of regular daily culturing conditions. Animals that were kept deflated for several days lost some of the abnormal morphology characteristic of epithelial hydra. The hypostome became conical and the upper portion of the body column became constricted. These new, more normal characters persisted for two days after deflation was discontinued. After long term deflation, the mesolamella was thick and regions of peristaltic annulations were altered. Furthermore, animals failed to bud at normal rates or elongate when pressure, in the gastric cavity was continually low. Thus, hydrostatic pressure, arising from gastrocoelic fluid, affects the long term histological and morphogenetic organization of hydra tissue.
Development of Drosophila imaginal discs in vitro: Effects of ecdysone concentration and insulin
Authors: Martin Presley , Shearn Allen
Published: June 2005

A detailed scoring system was used to determine the effects of a variety of factors on the evagination and differentiation of Drosophila imaginal discs cultured in vitro. In modified Schneider's Drosophila medium, β‐ecdysone induced development at concentrations approximately 100x lower than α‐ecdysone. The metamorphosis of imaginal discs consists of two processes, evagination and differentiation, which were found to be differentially sensitive to hormone concentration. Optimal differentiation occurred at relatively low β‐ecdysone concentrations (30 ng/ml), while complete evagination required higher levels (500 ng/ml). Even at the optimal hormone concentration for differentiation, not all discs differentiated completely, and each region of the eye, antenna, wing, and leg exhibited a characteristic frequency of differentiation. In addition, a strong negative correlation between the extent of evagination and the quality of differentiation was observed. Bovine insulin stimulated β‐ecdysone induced evagination, but at the same time it inhibited differentiation.
Partial blastema formation after amputation in adult mice
Authors: Neufeld Daniel A.
Published: June 2005

The amputation surface of toes of adult mice was treated by repeated skin removal and exposure to a saturated solution of NaCl. Histological examination of treated appendages revealed the presence of wound epithelium, numerous irregularly oriented subepithelial cells, many of which were mitotically active as indicated by [3H] thymidine uptake, and a remodeled viable bone adjacent to subepithelial cells. Thus, tissues at the amputation site of mammals can resemble comparable tissues of newt limb stumps at an early stage of regeneration. Complete blastema formation was not achieved, however.
Chicken fetal antigen expression on the definitive erythroid maturation series in the bone marrow of the adult chicken
Authors: Nelson Carrie H. , Patel Nipam H. , Sanders Bob G.
Published: June 2005

Chicken fetal antigen (CFA) describes a membrane developmental antigen system present on embryonic and fetal erythroid cells that is present during development, but is absent on erythrocytes of mature chickens. In this study, CFA was detected by indirect immunofluorescence and correlated with six stages of morphological maturation of erythroid cells. All cells in the erythroid series through the late polychromatic erythrocyte (reticulocyte) stage were found to posses CFA. Fluorescent intensity and staining patterns of the definitive erythroid series demonstrated CFA concentration increase and distribution pattern change throughout erythroid maturation.
Molecular correlates of morphological differentiation: Avian scutes and scales
Authors: Brush Alan H. , Wyld Jean A.
Published: June 2005

The scute reticulate scales of birds differ morphologically. We present evidence that the differences extend to the level of molecular content and organization. From the molecular evidence it appears that the scute was derived from the crocodilian scale and that the reticulate scale, like the feather, may be a structure unique to birds.
The relation of mitotic index, cell density, and growth to pattern regulation in regenerating Ambystoma maculatum forelimbs
Authors: Stocum David L.
Published: June 2005

Mitotic index and cell density were determined for all stages of larval Ambystoma maculatum upper arm and wrist regeneration up to the notch. Intrinsic growth rates and proportions of skeletal segments of upper arm and wrist regenerates were determined for stages of regeneration from notch to 25 days post‐amputation. Mitotic index was always higher in the blastema of the regenerate than in the dedifferentiating tissue proximal to it. Mitotic activity along the proximal‐distal axis of the blastema proper was relatively uniform until the onset of redifferentiation, when it declined in a distal to proximal direction in the proximal half of the blastema. Cell density tended to parallel mitotic index in both wrist and upper arm regenerates. There was no evidence that apical growth of the blastema is controlled by an inverse relationship between cell density (contact inhibition) and mitotic index. The relationship between the intrinsic growth rates of the regenerating skeletal segments were such that the proportions of the segments remained unchanged throughout their redifferentiation in upper arm regenerates, but were shifted slightly in wrist regenerates. These findings are discussed in relation to the progress zone model of limb development (Summerbell et al., '73).
The follicular envelope of ascidian eggs: A site of messenger RNA and protein synthesis during early embryogenesis
Authors: Jeffery William R.
Published: June 2005

Spawned ascidian eggs are surrounded by an extra‐embryonic envelope that consists of test cells and follicle cells and remains closely associated with the developing embryo until the time of larval hatching. The purpose of the present study was to determine whether this envelope is involved in macromolecular synthesis during early embryogenesis. Autoradiographic detection of radioactive uridine and leucine incorporation into the egg envelope of Ciona intestinalis and Styela plicata showed that this structure was active in RNA and protein synthesis between fertilization and the sixteen‐cell stage. In both ascidian species the components of the envelope active in macromolecular synthesis were the follicle cells. As shown by in situ hybridization with an [3H]‐poly (U) probe, the follicle cells but not the test cells contained substantial accumulations of poly(A)‐containing RNA during embryogenesis. Approximately 90% of the RNA synthesized in the follicle cells was poly(A)‐containing RNA. Both follicle cells and test cells, however, participated in macromolecular synthesis during oogenesis. The follicle cells of unfertilized Ciona eggs primarily synthesized a 42,000 molecular weight polypeptide which may be coded for by a major 16S putative mRNA species. It is concluded that the follicle cells are active in RNA and protein synthesis during early ascidian development. The production of a major polypeptide species suggests an active physiological role for these cells during embryogenesis.
Effect of thyrotropin‐releasing hormone on 22Na uptake by the pond snail Helisoma carabaceum
Authors: Grimm‐Jørgensen Y.
Published: June 2005

The effect of thyrotropin‐releasing hormone, added to the external environment, on in vivo Na+ uptake by Helisoma carabaceum was assessed. It was found that 10−5M TRH significantly decreased unidirectional sodium flux. The Na+ concentration in the tissues and hemolymph was not affected by the hormone. Histidyl‐proline‐diketopiperazine, a TRH‐metabolite, had no effects on Na+ uptake in vivo.