bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of forskolin on the spontaneous maturation and cyclic AMP content of hamster oocyte‐cumulus complexes
Authors: Racowsky Catherine
Published: June 2005

Forskolin, a reversible stimulator of the catalytic subunit of adenylate cyclase, has been used to determine: (1) whether an increase in hamster cumulus cell cyclic adenosine monophosphate (cAMP) results in an elevation of intraoocyte cAMP and an accompanying increase in the maintenance of meiotic arrest (%GV where GV is germinal vesicle) when heterologous coupling is maintained, (2) whether the hamster oolemma possesses the catalytic subunit of adenylate cyclase in an amount adequate to stimulate sufficient cAMP synthesis to maintain arrest, and 3) whether release from meiotic arrest is accompanied by a decrease in the content of intraoocyte cAMP. Intracellular cAMP was determined by RIA, functional metabolic coupling was assessed by determination of the fraction of radiolabeled uridine marker transferred from the cumulus mass to the oocyte, and meiotic stage was determined cytogenetically.

While the %GV of both cumulus‐enclosed (intact) and cumulus‐free (denuded) oocytes was dose‐dependent upon forskolin, that of intact oocytes was much more sensitive to the drug (intact: ID50 3.4 μM; denuded: ID50 65.0 μM, where ID50 is the dose of forskolin that inhibits the maturation of 50% of cultured oocytes). Forskolin stimulated a significant, dose‐dependent increase in the amount of cAMP within the cumulus mass [(r) = 0.789, P < 0.001)], the intact oocyte [(r) = 0.715, P < 0.001], and the denuded oocyte [(r) = 0.673, P < 0.01)]. The cAMP content of intact oocytes was significantly greater than that of denuded oocytes above 6.25 μM forskolin (25 μM forskolin: 9.28 ± 1.01 vs. 3.98 ± 0.15 fmol cAMP, intact and denuded oocytes, respectively; P < 0.001, paired t test). A highly significant positive correlation was established between the amount of cAMP in groups of cumulus masses and that in the corresponding enclosed oocytes [(r) = 0.635, P < 0.001]. The enhanced sensitivity of meiotic arrest in intact, as compared to denuded, oocytes was due to the presence of adherent cumulus cells but was not attributable to a significant increase in the cAMP content of intact oocytes (at 6.25 μM forskolin; %GV intact = 73.0 ± 10.7, denuded = 20.3 ± 7.4; fmol cAMP intact = 5.02 ± 1.50; denuded = 4.63 ± 0.81). The arresting action of forskolin on intact oocytes was transient and fully reversible, but release from arrest was not accompanied by a decrease in either intraoocyte cAMP or heterologous metabolic coupling. These data show that (1) the hamster oocyte can synthesize cAMP (2) when heterologous metabolic coupling is maintained cumulus cell cAMP may be transferred to the hamster oocyte, and (3) that release from forskolin‐maintained meiotic arrest is not correlated with a decline in intraoocyte cAMP or in heterologous coupling. The findings indicate that forskolin stimulates hamster cumulus cells to produce a “factor,” which may not be cAMP, to maintain meiotic arrest.
Oxygen consumption of mouse sperm and its relationship to capacitation
Authors: Boell E. J.
Published: June 2005

The oxygen consumption of spermatozoa from the caudae epididymides of the mouse was measured in various media and in the presence or absence of substrates and inhibitory agents in order to investigate the relationship between oxidative metabolism and capacitation.

When washed sperm were placed in a medium in which capacitation occurs, respiration increased abruptly, due to the availability of oxidizable substrates, and remained at a high, constant level throughout the period of measurement. There was no temporal change in rate during the time when capacitation was occurring, nor was the rate after capacitation had occurred higher than it was before.

Capacitation does not occur in a medium in which polyvinyl alcohol is substituted for bovine serum albumin or to which ethyl alcohol is added. Prevention of capacitation by these means had no effect on the rate of oxygen consumption.

The results support the conclusion that the increased respiration of sperm in a capacitating medium is due to the presence of oxidizable substrates and, as such, is an accompaniment of the process of capacitation rather than a factor in bringing it about.
Evidence for the presence and specificity of an unidentified plasma cofactor increasing haemocyanin oxygen affinity in two natantid crustaceans
Authors: Morris S. , Bridges C. R. , Grieshaber M. K.
Published: June 2005

Investigation of haemocyanin oxygen affinity in two species of Palaemon has demonstrated the presence of an unidentified factor (s); (U.F.), in the plasma, that increases oxygen affinity. Plasma exchange experiments have further demonstrated that this factor is not species‐specific and that the magnitude of the effect is dependent on the particular haemocyanin molecule. It has not been possible to demonstrate conclusively that the effect of this factor(s) can be reduced by dilution of the plasma. The variability in the extent of this cofactor effect, throughout the Crustacea, may be explained by variable sensitivity of haemocyanin to U.F.
Blood viscosity in arctic fishes
Authors: Graham Mark S. , Fletcher Garth L. , Haedrich Richard L.
Published: June 2005

The blood viscosity of arctic char, Salvelinus alpinus, and shorthorn sculpin, Myoxocephalus scorpius, from the arctic (74° 42′N) was measured with a cone‐plate viscometer. Blood viscosity of the two arctic species was considerably lower, less shear rate dependent, and less temperature dependent than the blood of winter flounder (Pseudopleuronectes americanus) from more temperate waters. The rheological properties of the arctic fish blood would minimize blood flow resistance and thus be advantageous at the low temperatures (0°C) characterizing their environment.
Isolation of enamelinlike proteins from blue shark (Prionace glauca) enameloid
Authors: Graham Edward Earl
Published: June 2005

A sequential dissociative extraction scheme was used to extract proteins from developing Blue Shark enameloid. The first extraction solution (4 M guanidine HCl) solubilized the polypeptides, mainly collagenous, not closely associated with the hydroxyapatite. The next extraction solution (4 M guanidine HCl, 0.5 M ethylenediaminetetraacedic acid (EDTA)) solubilized the proteins more closely associated with the tooth mineral component. After extraction, the proteins were separated and isolated with gel electrophoresis. Protein molecular weights were determined and selected proteins were isolated for amino acid composition analysis. The two proteins isolated were tested for mammalian enamel protein antigenic determinants by a “Dot” immunobinding assay. The isolated proteins were enamelinlike by extraction criteria and amino acid composition. Further, the two proteins share antigenic determinants with mammalian enamel proteins.
Photoperiodic regulation of thyroid responsiveness to TSH in Fundulus heteroclitus
Authors: Grau E. Gordon , Brown Christopher L. , Stetson Milton H.
Published: June 2005

Treatment of the killifish, Fundulus heteroclitus, with ovine thyrotropin (oTSH) produced elevations in serum thyroxin (T4) that varied seasonally with a strong inverse correlation to environmental photoperiod (P < 0.001). At 20°C, oTSH (0.2 IU) increased serum T4 to levels ranging from 1.5 μg/100 ml in midsummer to 7.5 μg/100 ml in midwinter despite relatively stable resting levels throughout the two years of study. Similar rates of clearance of T4 in summer and winter suggest that an alteration in thyroid response to oTSH accounts for this change. The serum T4 response to oTSH is both photoperiod‐ and temperature‐dependent. In laboratory studies, fish exposed to a short artificial photoperiod (LD 8:16) for one month responded to oTSH with T4 levels about twice as high as those in fish exposed to long days (LD 14:10). On the other hand the T4 response to oTSH was sharply reduced at 5°C from that seen at 20°C. This suggests that, in nature, seasonal changes in photoperiod and temperature have opposite effects on thyroidal responsiveness to TSH. Overall, the annual variation in the T4 response to oTSH appears to be driven by photoperiod, inasmuch as the alterations preceded major temperature changes in the wild and can be shown to occur at constant temperature in captivity. Photoperiodic induction of changes in thyroid sensitivity may aid in the maintenance of basal T4 levels under changing thermal conditions.
Surface of the rooster spermatozoon changes in passing through the Wolffian duct
Authors: Esponda P. , Bedford J. M.
Published: June 2005

Fluid secreted by the rooster Wolffian duct contains several proteins separable on polyacrylamide gel electrophoresis (PAGE) and isoelectricfocusing (IEF) gels. Antibodies against these fluid components were obtained by immunizing rabbits, and the IgG fraction was then purified. As judged by indirect immunofluorescence, purified IgG against rooster duct fluid did not bind to any testicular spermatozoa. However, it bound distinctly to the whole surface of spermatozoa from the initial (epididymal) region and more intensely to all spermatozoa from the mid‐ and terminal regions of the Wolffian duct of the rooster, though not at all to mature duck or pigeon spermatozoa. Thus, in the rooster, as in therian mammals, the surface of the spermatozoon clearly acquires specific components secreted by the Wolffian duct. It should not be assumed that such surface change in rooster spermatozoa is entirely comparable, in a functional sense, to that undergone by mammalian spermatozoa, in which this seems directly related to fertilizing ability. Unlike those of mammals, rooster spermatozoa do not seem to require capacitation, and some spermatozoa in the testis already are competent to fertilize. Components acquired in the Wolffian duct by the rooster spermatozoon may bear on other aspects, perhaps sperm transport and/or survival in the female.
Stimulating male sexual behavior with repetitive pulses of GnRH in female green iguanas, Iguana iguana
Authors: Phillips John A. , Alexander N. , Karesh William B. , Millar R. , Lasley B. L.
Published: June 2005

Adult female green iguanas (Iguana iguana) were treated with repetitive pulses of chicken gonadotropin (d‐Arg6 chicken II) releasing hormone (GnRH) delivered by interperitoneal osmotic pumps. Total estrogen levels in serum decreased from 37.3 ± 18.0 pg/ml to 5.4 ± 4.6 pg/ml 9 days after the pump was implanted. Estrogen levels returned to pre‐implant levels 5 days after the end of the treatment period. The behavior of male iguanas, housed with the treated females, was influenced while the pumps were functioning. The frequency of assertive displays between males increased threefold after 7 days of GnRH treatment. Males actively interposed themselves between “their” female and other males during the same period.
Exogenous catecholamines do not affect osmoregulatory parameters in the intact eel
Authors: Epple August , Kahn Harry A.
Published: June 2005

Injections of physiological (2 μg/kg) and supraphysiological (8 μg/kg) doses of dopamine, norepinephrine, and epinephrine via a cardiac cannula into freshwater‐adapted eels were not followed by changes in serum osmolality, sodium, and chloride. Likewise, injections of 8 μg/kg of epinephrine had no impact on these parameters in seawater‐adapted eels. These results suggest that circulating catecholamines do not have a major effect on the overall balance of osmoregulatory serum components in the intact eel.
Adrenergic responses of the cardiovascular system of the eel, Anguilla australis, in vivo
Authors: Hipkins Scott F.
Published: June 2005

Heart output, arterial pressures, and heart rate were measured directly in conscious unrestrained eels (Anguilla australis) and responses to intra‐arterial injection of adrenaline monitored. Adrenaline increased systemic vascular resistance, heart output, and cardiac stroke volume in all animals. In some cases small transient decreases in stroke volume and hence heart output were seen at the peak of the pressor response: These probably reflect a passive decrease in systolic emptying due to increased afterload on the heart. In most cases, adrenaline produced tachycardia; but two animals showed consistent and profound reflex bradycardia, which was accompanied by a concomitant increase in stroke volume such that heart output was maintained or increased slightly. The interaction of changes in heart output and systemic vascular resistance produced complex and variable changes in arterial pressure. There was no consistent pattern of changes in branchial vascular resistance. Atropine treatment in vivo revealed vagal cardio‐inhibitory tone in some animals and always blocked the reflex bradycardia seen during adrenaline induced hypertension. In some animals, adrenaline injection after atropine pretreatment led to the establishment of cyclic changes in arterial pressure with a period of about 1 min (Mayer waves).
Effects of pH on in vitro ovulation of goldfish (Carassius auratus) oocytes
Authors: Goetz Frederick W. , Nagahama Yoshitaka
Published: June 2005

The in vitro effects of pH on goldfish (Carassius auratus) ovulation were investigated. Final oocyte maturation and follicular detachment were induced in vivo in gravid goldfish by HCG injections and elevated holding temperatures. Females were biopsied to determine the time of germinal vesicle breakdown and when oocytes should be removed for in vitro incubations. Prior to ovulation, the ovaries were removed, dissected and mature intrafollicular oocytes were incubated in media of varying pH (7.3–8.9). There was a significant increase in ovulation as the pH of the incubation increased and this ovulation could be blocked by indomethacin. Indomethacin did not inhibit the actual mechanism of oocyte expulsion since exogenous PGF2α induced ovulation in indomethacin blocked incubates. Increased pH did not increase the ovulatory response observed with exogenous PGF2α. The combined results suggest that an increase in incubation pH stimulates prostaglandin synthesis that, in turn, stimulates ovulation.
A possible effect of the Na+ concentration in oviductal fluid on amino acid uptake by cleavage‐stage mouse embryos
Authors: van Winkle Lon J. , Campione Allan L. , Kester Samara E.
Published: June 2005

Two‐ and four‐cell mouse embryos exhibited both Na+‐dependent and Na+‐independent components of zwitterionic α‐amino acid transport, which we tentatively ascribe to the A and L amino acid transport systems, respectively. Uptake of taurine was virtually all Na+‐dependent and is probably via the β system. Na+‐independent L‐lysine uptake by two‐cell embryos may have been via system y+. The small amount of lysine transport which was Na+‐dependent (30% of the total) could not be attributed to any well known transport system and may have been due to the early ontogenetic expression of a newly described transport system which predominates in preimplantation blastocysts. We conclude that the rate of Na+‐dependent amino acid transport in two‐cell mouse embryos could be significantly affected in situ by changes in the [Na+] which are known to occur in oviductal fluid.
The 3, 4‐didehydroretinal chromophore of goldfish porphyropsin
Authors: Tsin Andrew T. C. , Santos Frank R.
Published: June 2005

The isomeric configuration of the 3,4‐didehydroretinal chromophore of goldfish porphyropsin was determined by high performance liquid chromatography (HPLC) and by the regeneration of this visual pigment with authentic isomers of 3,4‐didehydroretinal. A nonisomerizing, quantitative method using hydroxylamine and methylene chloride was employed to extract the 3,4‐didehyroretinal chromophore from the rod outer segment membrane (containing the porphyropsin). When this extracted chromophore was injected into the HPLC, only a single major peak was observed and this peak coeluted with the authentic 11‐cis 3,4‐didehydroretinyl oxime. This suggests that the chromophore of goldfish porphyropsin is 11‐cis 3,4‐didehydroretinal. When the bleached rod outer segments (containing the opsin) were incubated with different 3,4‐didehydroretinal isomers (13‐cis, 11‐cis, 9‐cis, and all‐trans), only the 11‐cis isomer resulted in the degeneration of porphyropsin. This also suggests that the porphyropsin chromophore exists in the 11‐cis configuration.
Surface contractile activity associated with isolated asters in cylindrical sand dollar eggs
Authors: Rappaport R. , Rappaport Barbara N.
Published: June 2005

The purpose of this investigation was to explore the capacity of isolated asters of the mitotic apparatus of elicit contractile activity in adjacent cell surface. When a fertilized Echinarachnius parma egg with an intact mitotic apparatus was confined in an 82‐μm‐i.d. silicone rubber capillary, the furrow developed at the midpoint between the asters. The mitotic apparatus could be broken by inserting and ejecting the egg from the capillary. The asters of a broken mitotic apparatus were usually abnormally far apart. When asters were as far as 68 μm apart, furrowing occurred; when the intervening distance was greater, there was no furrowing. When the asters were too far apart to establish a furrow between them, constrictions appeared adjacent to one of the asters. The constrictions could shift or could cut through the asters that appeared to elicit them. Cylindrical cells in 0.015 M ethyl urethane formed furrows when the mitotic apparatus was intact but formed neither furrows nor astral constrictions when the asters were far apart. Astral constrictions did not form in the presence of an active furrow. They were frequently temporary and they appeared to be slower and less acute than normal furrows. Single asters remaining after half of the amphiaster was removed had the same effect as widely separated asters. The form of the constriction was related to the position of the aster in the cylinder. When the aster was centered, the constriction resembled a furrow; but when it was near one of the poles, the adjacent surface pulled away from the capillary wall and the radius of curvature at the pole decreased. When initially distant asters were pushed together, a furrow formed between them. These results contribute to a better understanding of the interaction between the mitotic apparatus and the egg surface and the formation of the cleavage mechanism.
Inhibition of nuclear maturation in fully grown porcine and mouse oocytes after their fusion with growing porcine oocytes
Authors: Fulka J. , Motlík J. , Fulka J. , Crozet Nicole
Published: June 2005

Porcine ovarian oocytes, isolated from follicles of 5 mm in diameter (large oocytes), were fused either together or with oocytes isolated from follicles of 0.5 mm in diameter (small oocytes). In giant cells composed of two large oocytes (control) germinal vesicle breakdown (GVBD) occurred and two metaphase I chromosome sets (M I) were observed 24 to 30 h after fusion. By contrast, in giant cells composed of one large and one small porcine oocyte, both germinal vesicles (GVs) remained well conserved after 24–30 h of culture. An identical situation was observed after fusion and cultivation of small porcine and large mouse oocytes isolated from preovulatory follicles. The results demonstrate the presence of inhibiting activity in the ooplasm of small porcine oocytes that prevents nuclear maturation of large porcine and mouse oocytes fused to them. This maturation inhibiting activity can be overcome by preincubating large porcine oocytes for more than 14 h before fusion with small oocytes. During preincubation the ooplasm produces sufficient amount of maturation promoting factor (MPF) to overcome the inhibiting activity present in small porcine oocytes thus inducing GVBD and chromatin condensation both in small and large oocytes.
Inhibition of 45Ca2+ uptake in the eggs and embryos of the sea urchin, Anthocidaris crassispina, by several calcium antagonists, anion transport inhibitor, and chloride transport inhibitors
Authors: Fujino Yukio , Mitsunaga Keiko , Fujiwara Akiko , Yasumasu Ikuo
Published: June 2005

The rate of45Ca2+ uptake was close to zero in unfertilized eggs. It rapidly increased after fertilization and then decreased within 1 hr. The rate remained low between 1 and 12 hr after fertilization (until shortly after hatching). Thereafter, the rate gradually increased during developmental period between 15 (the mesenchyme blastula stage) and 30 hr after fertilization (the prism stage). It then decreased 40 hr after fertilization (the pluteus stage). In embryos assayed 30 and 40 hr after fertilization, about 70 and 40 percent, respectively, of 45Ca2+ was found in the spicules. During the whole period of early development, 45Ca2+ uptake was inhibited by diltiazem and verapamil (calcium antagonists), ruthenium red (known to inhibit45Ca2+ uptake in mitochondia and also Ca2+ ‐ATPase in plasma membrane), and 4,4′‐diisothiocyano‐2,2′‐disulfonic acid stilbene (an anion transport inhibitor). Ethacrynic acid and furosemide (chloride transport inhibitors), inhibited 45Ca2+ uptake between 24 and 40 hr after fertilization. These results suggest that 45Ca2+ is transported through a Ca2+ channel and/or a Ca2+ ‐pump and that electrosilent transport of Ca2+ is achieved by anion transport.
Long‐term adaptation to low salinities in the euryhaline shrimp Crangon franciscorum (Stimpson)
Authors: Shaner Stephen W. , Crowe John H. , Knight Allen W.
Published: June 2005

The euryhaline shrimp Crangon franciscorum is a hyper‐hypoosmotic regulator, its hemolymph being iso‐osmotic with the medium near 27‰ salinity. Shrimp collected from low salinity environments are physiologically very distinct from those collected from high salinity environments. Individuals from low salinity habitats exhibit better survival, a lower water content and apparent permeability to water, and a decreased rate of sodium loss in low salinities when compared to shrimp from high salinity habitats. These differences persist after several days of adaptation to low salinity, however after acclimation to a low salinity for a longer time (5–6 weeks in this study), these differences disappear.
Purification and characterization of an N‐acetyl‐β‐D‐glucosaminidase from cortical granules of Xenopus laevis eggs
Authors: Prody Gerry A. , Greve L. Carl , Hedrick Jerry L.
Published: June 2005

The enzyme N‐acetyl‐β‐D‐glucosaminidase was purified from the cortical granules of Xenopus laevis eggs using affinity chromatography, gel filtration, and density gradient centrifugation. The enzyme had a molecular weight of 37,000–40,000 as determined by polyacrylamide gel electrophoresis and density gradient centrifugation, had a Km for p‐nitrophenyl‐β‐D‐N‐acetyl‐glucosaminide of 0.66 mM and a Ki for glucosamine of 4.3 mM. The kinetic properties of the cortical granule enzyme were similar to the enzyme isolated from jack bean. Treatment of unfertilized eggs with the enzyme isolated from cortical granules or jack bean rendered eggs unfertilizable. Loss of fertilizability was proportional to the product of time and enzyme concentration, consistent with an enzymatic mechanism being responsible for the loss of fertilizability. The amount of enzyme present in the perivitelline space was approximately the same as that which reduced fertilizability by 50% in one hour. We suggest that the action of cortical granule N‐acetyl‐β‐D‐glucosaminidase on egg integuments may function as a block to polyspermy at fertilization.
Control of panting in the desert iguana: Roles for peripheral temperatures and the effect of dehydration
Authors: Dupré R. Keith , Crawford Eugene C.
Published: June 2005

Although it is generally held that panting is a physiological mechanism for the regulation of brain temperature during heat stress, a number of studies have pointed to the importance of peripheral input for the initiation of the panting response in a variety of animals. By presenting ambient heat loads of 47°, 54°, 58°, and 65°C, and measuring skin, ear and core temperatures of the desert iguana, Dipsosaurus dorsalis, at the onset of panting, we found that the skin temperature at panting onset was independent of ambient heat load. This suggests that skin (peripheral) temperature is the body temperature on which the central thermoregulatory center cues to initiate thermal panting. Peripheral temperature control of panting was retained when the plasma osmolality of the desert iguana was increased by 100 mOsm/kg H2O to simulate dehydration. Dehydration to 80% initial body weight (IBW) resulted in a progressive increase in panting threshold (skin) from 42°C for untreated lizards to 42.5°C at 90% IBW to 43.3°C at 80% IBW. Injection of 80% IBW lizards with a volume of 10 mM NaCl equivalent to weight loss resulted in a decrease in panting threshold to 40.8°C. Injection with 1% body weight 3000 mM NaCl produced a dramatic increase in panting threshold to 45.9°C. These data suggest that the desert iguana responds to dehydration by elevating panting threshold, thus promoting water conservation. These data also suggest that changes in plasma osmolality may be involved in the “setting” of panting threshold.
The role of K+ and Cl− conductances in chloride secretion by the opercular epithelium
Authors: Degnan Kevin J.
Published: June 2005

The opercular epithelium of the teleost Fundulus heteroclitus, when mounted in a lucite chamber under short‐circuited conditions, secretes Cl− at a rate equivalent to the short‐circuit current (Isc). The transepithelial Na+ movements are passive and proceed by a paracellular pathway. The addition of 2 × 10−3 M Ba2+ to the serosal bathing solution inhibited the Isc 76.8% with no effect on the transepithelial conductance (Gt). The addition of 5 × 10−4 M Cu2+ to the mucosal bathing solution inhibited the Isc 79.6% and reduced the Gt 35.6%. These inhibitory effects of Ba2+ and Cu2+ on the Isc were initiated within 1 minute after exposure with maximum effects occurring within 20 and 30 minutes, respectively. Simultaneous 36Cl− and 22Na+ unidirectional fluxes were performed on paired epithelia from the same fish. Serosal Ba2+ and mucosal Cu2+ inhibited the Cl− secretory flux 30.2 and 58.9%, respectively. The resulting net Cl− flux after inhibition was not significantly different from the mean measured Isc. Neither ion had significant effects on the Cl− influx (mucosa to serosa) or the unidirectional Na fluxes. These results indicated that the effects of both Ba2+ and Cu2+ were most likely exclusive to the transcellular Cl− pathway. Ba2+ is proposed to inhibit Cl− secretion by blocking the basolateral K+ channels, depolarizing the cell, and reducing the electrochemical driving force for Cl− across the apical membrane. Cu2+ is proposed to inhibit Cl− secretion by blocking the apical membrane Cl− channels. The results are in keeping with the proposed mechanism for Cl− secretion by indicating that the Cl− exit step across the apical membrane occurs via Cl− conductive channels and is driven passively by a favorable electrical gradient.
Cell allocation in half‐ and quadruple‐sized preimplantation mouse embryos
Authors: Rands Gillian F.
Published: June 2005

The size of preimplantation mouse embryos was experimentally manipulated in order to examine the consequences for the allocation of cells to the two primary tissues, trophectoderm and inner cell mass (ICM). Half embryos were produced by the mechanical lysis of one cell at the two‐cell stage and quadruple embryos by the aggregation of four whole eight‐cell embryos. Such procedures are shown not only to alter the absolute number of cells that are assigned to the trophectoderm and ICM, but also to disturb significantly the proportions of these two tissues in the blastocyst. The proportion of trophectoderm is directly related to the surface area of the morula, as is predicted by a purely epigenetic scheme for cell allocation.
The behaviour of insect plasmatocytes in vitro: Changes in morphology during settling, spreading, and locomotion
Authors: Davies D. H. , Preston T. M.
Published: June 2005

The settling, spreading and locomotory behaviour of the plasmatocytes from three lepidopteran species (Ephestia kuehniella, Pieris brassicae and Aglais urticae) on a glass substratum in vitro has been examined using light and scanning electron microscopy. Immediately upon withdrawal from the haemocoel plasmatocytes are ovoid (E. kuehniella) or spindle‐shaped. These cells are usually seen to undergo a series of three distinct morphological changes in response to cell‐substratum contact. 1) The initial stable attachment, beneath the nuclear region, is followed by a rapid rounding‐up with a concomitant initiation of surface ruffling and filopod production. 2) Cell‐substratum contact is consolidated by an increase in area and the establishment of additional contacts at suitable (cell‐free) sites around the periphery by filopodia. 3) Spreading proceeds with the production of lamellae which expand within the interfilopodial space.

The shape of fully spread plasmatocytes is variable but only locomoting cells are clearly polarized. Locomotion is triggered during spreading in response to cell‐cell contact; colliding partners then polarise and exhibit brief evasive translocations over a short distance. It has also been shown that plasmatocytes translocate over the surface of glass implants during the early stages of encapsulation in vivo.
Sexual differences and steroid‐induced changes in metabolic activity in toadfish sonic muscle
Authors: Pennypacker Keith R. , Fine Michael L. , Mills Richard R.
Published: June 2005

Since the male oyster toadfish (Opsanus tau) is more active in sound production than the female, we hypothesized that sonic muscles of the male are biochemically specialized to perform more work. In order to categorize the muscle biochemically and test for sexual differences, we measured the activity of two anaerobic enzymes, 3‐phosphoglyceraldehyde dehydrogenase (3PG) and lactic dehydrogenase (LDH), and two aerobic enzymes, malate dehydrogenase (MDH) and glutamic oxaloacetic transaminase (GOT). Males exhibited greater 3PG and GOT activity than females (p < 0.05). Both MDH and LDH showed little activity in either sex. High 3PG and low LDH levels indicate a substained level of glycolysis, with pyruvate shuttled into aerobic metabolism, and high GOT activity indicates a high level of aerobic metabolism. From this and other data, we conclude that toadfish sonic muscle can be classified as fast‐twitch oxidative glycolytic or fast‐twitch fatigue resistant. The endocrine basis for these sexual differences was examined by implanting steroid pellets into ovariectomized females. Testosterone induced a doubling of 3PG activity (p < 0.02), and dihydrotestosterone induced an eight‐fold increase (p < 0.0005) in GOT concentration over controls. The steroids had no effect on LDH and MDH activities. Hormones, therefore, trigger one of the fundamental sexual differences underlying toadfish communication, namely a difference in metabolism, providing the male with the capacity for increased sound production.
Glutamate catabolism in mitochondria from Mya arenaria mantle: Effects of pH on the role of glutamate dehydrogenase
Authors: Moyes Christopher D. , Moon Thomas W. , Ballantyne James S.
Published: June 2005

The role of glutamate dehydrogenase (GDH) in amino acid catabolism of the mantle of Mya arenaria was examined using coupled mitochondria and in vitro enzyme activity measurements. The maximal activities of mitochondrial glutamate‐oxaloacetate transaminase (GOT) and glutamate‐pyruvate transaminase (GPT) are fourfold and twofold greater, respectively, than GDH (deaminating). Based on pH profiles, the relative activities of these enzymes in vivo may be highly dependent on mitochondrial pH. Addition of ADP resulted in a 15‐fold activation of GDH (deaminating) and a shift in the pH optimum from 8.1 to 8.6. The in vitro activity of GDH was sufficient to account for all NADH produced in intact mitochondria oxidizing glutamate. In intact mitochondria at pH 7.4 and 8.2, addition of the aminotransferase inhibitor aminooxyacetic acid (AOA) had no effect on the state 3 rate of glutamate oxidation. However, at pH 6.7 in situ GDH (deaminating) activity was insufficient to maintain the rate of glutamate oxidation in the absence of transaminase activity. Glutamate oxidation between pH 6.4 and 8.0 is limited by the electron transport system. At pH 8.3, transport of glutamate into the mitochondria may be rate limiting. Mitochondria oxidizing glutamate in state 4 in the presence of phosphate or in state 2 in the absence of phosphate demonstrated increased oxygen consumption in response to the uncoupler carbonyl m‐chlo‐rophenyl‐hydrazone (CCCP). These studies suggest that in spite of low activities compared to vertebrates, GDH activities could be physiologically significant in amino acid metabolism of Mya arenaria mantle.
Pattern‐deficient forelimb regeneration in adult bullfrogs
Authors: Tomlinson Bruce L. , Tomlinson Donna E. , Tassava Roy A.
Published: June 2005

This study was designed to test the ability of adult bullfrogs (Rana catesbeiana) to regenerate forelimbs, both with and without various experimental treatments. Distal humerus‐level forelimb amputations provided with additional deviated (sciatic) nerve and/or repeated soft‐tissue injury exhibited considerable outgrowth. However, control sham‐operated forelimbs also produced regenerates with comparable frequency, size, and morphological complexity. The lengths of the regenerates ranged from 0.4 to 2.6 cm, representing an outgrowth of 10–65% of the portion removed by the distal humerus amputation plane; some regenerates exhibited an external morphology indicative of digitlike structures. Some outgrowths were flexible but only one was capable of independent movement. Victoria Blue staining of whole regenerates revealed a variety of internal cartilage elements. Staining showed a single solid mass of cartilage in some regenerates while others had several individual and variably shaped cartilages projecting distally. Histological analysis also revealed the presence of connective tissue, striated muscle, and abundant nerve fibers in addition to the individual cartilage elements. We have tentatively termed these responses pattern‐deficient regeneration.
The early lethality of autosomal monosomy in the mouse
Authors: Magnuson Terry , Debrot Sylvain , Dimpfl Joan , Zweig Adam , Zamora Teodosia , Epstein Charles J.
Published: June 2005

Using male mice doubly heterozygous for pairs of Robertsonian translocation chromosomes that have one arm in common, mouse embryos monosomic for 11 of the 19 autosomes have been generated. All of these monosomies result in death prior to or during the implantation period, with only rare survivors being detected 6 days after fertilization. For some of the monosomies the onset of lethality can be detected during the third or fourth day of development, but others do not begin to die until sometime after the late blastocyst stage on day 4. Retardation of development, as revealed by decreased cell numbers, is often detectable prior to or after the onset of the lethal period. The period during which death occurs may spread over several days and does not coincide with any of the developmental landmarks of the pre‐ or peri‐implantation period. Genetic factors that may affect the rate of cellular proliferation or other aspects of embryonic development appear to play an important role in determining exactly when individual monosomies result in death. The universal early lethality of the autosomal monosomies leads to the conclusion that a large number of loci scattered over all of the autosomes are involved in processes that are so concentration dependent that a 50% reduction is sufficient to produce very serious consequences.
Stimulation of 17α,20β‐dihydroxy‐4‐pregnen‐3‐one production in the granulosa cells of amago salmon, Oncorhynchus rhodurus, by cyclic nucleotides
Authors: Nagahama Yoshitaka , Kagawa Hirohiko , Adachi Shinji , Young Graham
Published: June 2005

The effects of partially purified chum salmon gonadotropin (SGA), forskolin, dibutyryl cAMP and cGMP, and the phosphodiesterase inhibitors theophylline and 3‐isobutyl‐1‐methyl‐xanthine (IBMX) on the production of 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (maturation‐inducing steroid in amago salmon, 17α,20β‐diOHprog) by amago salmon, Oncorhynchus rhodurus, granulosa layers in vitro were examined. All test agents, with the exception of dibutyryl cGMP, significantly stimulated the production of 17α,20β‐diOHprog when granulosa layers were incubated in the presence of 17α‐hydroxyprogesterone, but not in its absence; 1 μg/ml SGA, 1, 10, and 100 μM forskolin, 1 mM dibutyryl cAMP, 1 mM theophylline, and 1 mM IBMX stimulated production to levels about 2–17 times those of the untreated controls. These results indicate that gonadotropin directly acts on amago salmon granulosa cells to stimulate 17α,20β‐diOHprog production, possibly by enhancing the activity of 20β‐hydroxysteroid dehydrogenase, the enzyme involved in the conversion of 17α‐hydroxyprogesterone to 17α,20β‐diOHprog, via an adenylate cyclase‐cAMP‐dependent mechanism.
Effects of sustained swimming on rainbow trout muscle structure, blood oxygen transport, and lactate dehydrogenase isozymes: Evidence for increased aerobic capacity of white muscle
Authors: Davie Peter S. , Wells Rufus M. G. , Tetens Vilhelm
Published: June 2005

Groups of rainbow trout (Salmo gairdneri, Richardson) were continuously swum at 20 cm s−1 (1.0 body lengths s−1) for 0, 3, 30, and 200 days. No significant changes in fish condition factor, combined red and white muscle mass, muscle fibre size or fibre size distribution were observed. After 200 days of swimming there was a significant 2.2 fold increase in red muscle mass.

Number of capillaries per red muscle fibre increased significantly in each group by a maximum of 27% after 200 days exercise. Number of capillaries per white muscle fibre increased significantly by 95% after 200 days exercise. Blood lactate, haemoglobin (Hb) concentration haematocrit, erythrocyte adenosine triphosphate, and whole blood oxygen affinity P50 were unchanged by swimming. After 30 and 200 days swimming there was a shift in expression of white muscle lactate dehydrogenase (LDH) isozymes from LDH‐A to LDH‐B. Within the duplicated LDH‐B isozyme complex, there was a shift in expression from LDH‐B to LDH‐B′ subunits. These results suggest that sustained swimming at 1−1 bl s−1 increased the aerobic capacity of red and particularly white (fast) muscle of rainbow trout but did not alter the gas transport characteristics of the blood.
Metamorphosis of the American eel, Anguilla rostrata LeSeur: I. Changes in metabolism of skeletal muscle
Authors: Egginton Stuart
Published: June 2005

Unequivocal demarcation between immature, nonmigratory yellow eels and migratory silver eels of greater sexual maturity is possible by measuring eye diameter and retial capillary length, which undergo a 1.5‐ and 2.3‐fold increase during metamorphosis, respectively. Anatomical arrangement of trunk musculature is similar in the two groups except for an increased depth of slow muscle in silver eel. Histochemical analysis reveals a progressive increase in numbers of “displaced” fast fibres within slow muscle of the lateral line triangle in maturing eels, although these are unlikely to affect recruitment pattern of muscle fibre types. Previous studies have suggested greater involvement of fast muscle in locomotion of migratory eels. In contrast, estimates of enzyme activity in fast muscle suggest an inadequate aerobic capacity to fuel sustained activity. Myoglobin content is extremely low, around 0.4 nM g wet wt−1. Prolonged anaerobic metabolism is also discounted as a migratory strategy. Increased energy provision for migration is apparently derived from increased capacity for both aerobic carbohydrate metabolism and mitochondrial fatty acid oxidation within slow muscle of silver eels. Activity of hexokinase (HK) shows a 1.6‐fold increase (to 0.51 μM g wet wt−1) and carnitine palmitoyltransferase (CPT) a 3.1‐fold increase (to 0.22 μM g wet wt−1 min−1), suggesting a maximal flux through these pathways of 18 and 14 ATP equivalents, respectively. However, the fatty acyl transferase system of skeletal muscle mitochondria displays up to threefold greater activity with palmitoleoyl CoA (C16:1) as substrate than with the usual palmitoyl CoA (C16:0). Slow muscle of silver eel is therefore capable of deriving aerobic energy from free fatty acids and carbohydrate in the ratio 2.3:1. Differences in aerobic enzyme activities are not paralleled by myoglobin content of slow muscle, being 15 and 16 nM g wet wt−1 for yellow and silver eel, respectively. Structural reorganization of muscle fibres during metamorphosis, however, results in a twofold elevation of cytoplasmic myoglobin concentration in silver eel. It would appear that dramatic differences in metabolic capacity between life history stages of eel is required to overcome locomotory inefficiency of yellow eels and to “preadapt” silver eels for migratory activity. This increased locomotory capacity may be amplified by a subsequent training response.
Development of the eye‐antenna imaginal disc and morphogenesis of the adult head in Drosophila melanogaster
Authors: Haynie John L. , Bryant Peter J.
Published: June 2005

We have studied the organization and development of the eyeantenna imaginal disc of Drosophila melanogaster. We examined the pattern of gynandromorph mosaicism and determined the “sturt distances” between 42 different structures of the head, antenna, and maxillary palpus. A morphogenetic map based on these sturt distances resembles more closely in size and shape that of a single thoracic segment than that of two or more adjacent segments, suggesting that the eye‐antenna disc is derived from a single embryonic body segment. We examined the morphology of the eye‐antenna discs in situ in late third‐instar larvae in serial cross sections. The two discs are connected medially by a thin cellular membrane that probably serves to join the two discs during evagination and morphogenesis of the adult head. A fate map of the imaginal disc was established by cutting the mature disc into fragments and transplanting the fragments into host larvae for metamorphosis. The peripodial layer of the eye‐antenna disc is thickened in several regions, and our data suggest that these thickened areas represent primordia of adult head structures. A comparison of the location of precursors in the imaginal disc with those of the differentiated structures of the adult head revealed the nature of the morphogenetic movements that must occur during evagination and differentiation.
The defender role of the precocious larvae ofCopidosomopsis tanytmemusCaltagirone (Encyrtidae, Hymenoptera)
Authors: Cruz Y. P.
Published: June 2005

A specialized larval morph, here called the precocious larvae, is present in broods of the polyembryonic encyrtid wasp,Copidosomopsis tanytmemusCaltagirone, an egg‐larval parasite of the Mediterranean flour moth,Anagasta kuehniella(Zeller). The precocious larvae are clonally derived from the same embryonic cells that produce the normal larvae. In contrast to their normal siblings, precocious larvae have well‐developed cranial structures and mouthparts, and are extremely motile. The most unusual feature of precocous larvae, however, is their failure to attain reproductive age; they invariably die in the host hemolymph as untransformed larvae. Competition experiments with the braconidPhanerotoma flavitestaceaFischer or one of the ichneumonidsVenturia canescens(Gravenhorst) andTrathalasp. showed that precocious larvae injured or killed these competitors in 74, 98, and 97%, respectively, of the observed cases of multiple parasitism.

Dissection of parasitized host larvae revealed that dead parasite larvae had different fates. Although injured and dead braconid and ichneumonid parasites were encapsulated by aggregations of host lamellocytes, precocious larvae remained unencapsulated, regardless of whether death occurred normally or, rarely, resulted from injury. It is hypothesized that successful avoidance of encapsulation by both precocious and normal larvae ofC. tanytmemusis due to either or both of the host‐produced cyst or the parasite‐produced trophic membrane.

The precocious larvae fulfill the requirements for the ultimate altruist predicted by kin‐selection theory. However, because they are genetically identical to the individuals whose survival they enhance, the precocious larvae paradoxically qualify as a completely selfish caste as well. It is thus pointed out that the biological role of the precocious larvae is most appropriately evaluated as that of defender.
Assimilation and deposition of wax esters in planktivorous seabirds
Authors: Roby Daniel D. , Place Allen R. , Ricklefs Robert E.
Published: June 2005

We have analyzed the lipid composition of meals fed to chicks and determined the ability of chicks to assimilate wax esters in four species of high latitude, plankton‐feeding seabirds: one alcid (Aethia pusilla; Alcidae: Charadriiformes) and three petrels (Pelecanoides urinatrix, P. georgicus, and Pachyptila desolata; Procellariiformes). Up to 63% of the estimated digestible energy in chick meals consists of wax esters. Using 14C‐labeled cetyl palmitate, we have shown that chicks of the four study species efficiently hydrolyze wax esters, with less than 1% of the ingested label excreted in most cases. Labeled fatty acids were assimilated and deposited primarily as triacylglycerols in storage fat depots. The one study species known to store lipids in the proventriculus retained much of the labeled wax ester unhydrolyzed in stomach oils. However, the capacity to store stomach oils was not a requisite for efficient assimilation of wax esters. This study provides the first direct evidence that seabirds have the inherent ability to digest and assimilate wax esters efficiently.
Variations in radiosensitivity during development of the frog Limnodynastes tasmaniensis
Authors: Panter H. C.
Published: June 2005

Twenty‐two stages of the life cycle of the laboratory‐reared frog Limnodynastes tasmaniensis, from the fertilised egg to the adult frog, have been subjected to acute irradiation from cobalt‐60 (60Co) gamma rays to determine the lethal dose (LD50) values. The period of observation was 40–160 days, depending on the stage irradiated. The most sensitive stage was the fertilised egg, with an LD50/40 of 0.6 Gy. Thereafter, radioresistance increased in an uneven pattern, with periods of relatively rapid increase alternating with periods of little change. The most resistant stages of the life cycle were medium to large tadpoles at limb bud and toe development stages (LD50/60 ∼ 25 Gy). At metamorphosis, resistance decreased significantly to an LD50/160 of 18.3 Gy, with a very similar result, 18.7 Gy, for young adult frogs. The latter figure, when compared with LD50 values for other frogs, is found to be in good agreement with other results obtained using gamma rays. Preliminary experiment on chronic caesium‐137 (137Cs) gamma irradiation are described.
Immunocompetence in Hydra: Epithelial cells recognize self‐nonself and react against it
Authors: Bosch Thomas C. G. , David Charles N.
Published: June 2005

The evolution of effective immunologic defense mechanisms in multicellular organisms involves the ability of host cells to distinguish betweeen “self” and “nonself” and to react appropriately to eliminate foreign tissue. By producing interspecies grafts we have obtained evidence that immunorecognition followed by incompatibility reactions occur in Hydra. Our results demonstrate that epithelial cells of Hydra recognize and phagocytose foreign hydra cells, indicating that they are the effector cells in the incompatibility reactions. This observation is consistent with the idea that immunocompetence appeared early in the evolution of multicellular organisms.