bluuebunny/crossref_metadata_2025_split huggingface dataset:
Free amino acids and cell volume regulation in the elasmobranch, Raja erinacea
Authors: Goldstein Leon 
Published: June 2005

AbstractFree amino acids comprise a significant fraction of the total intracellular osmolality in skate tissues. The high amino acid concentrations are maintained by active, Na+‐dependent transport systems in the cell membranes. Following transfer to a hypo‐osmotic environment (dilute seawater) cellular concentrations of free amino acids are reduced mainly as a result of increased rates of outflux but decreased rate of influx can also play a role. Metabolism (oxidation and synthesis) does not appear to play a direct role in the modulation of free amino acid concentrations in skeletal muscle cells and erythrocytes. However, continued release of free amino acids from these cells during hypo‐osmotic stress is dependent on the ability of liver and kidney to either oxidize (β‐alanine, sarcosine) or excrete (taurine) amino acids at accelerated rates. A scheme for the overall modulation of cellular free amino acids in skate tissues by a combination of membrane transport, metabolism, and excretion is presented.
Circadian rhythm of nonpineal extraretinal photosensitivity in a teleost fish, the lake chub, Couesius plumbeus
Authors: Kavaliers Martin 
Published: June 2005

AbstractLake chub, Couesius plumbeus, displayed a diurnal rhythm of nonpineal extraretinal photosensitivity under laboratory light‐dark cycles. There was a bimodal pattern in the threshold intensity (energy fluence rate) for iniating extraretinally mediated photoresponses. Significantly greater intensitites were required in the scotophase than in the photophase of a 12‐hour‐light:12‐hour‐dark cycle. Maximal sensitivity was at the light‐dark and dark‐light transitions. Under constant darkness this pattern continued as a free‐running circadian rhythm of nonpineal extraretinal photosensitivity. The pineal organ, which is directly photosensitive and involved in the control of circadian rhythms in teleost fishes, is not essential for either the generation or expression of this circadian rhythm.
Extraocular photoentrainment of the circadian locomotor rhythm of the garden slug Limax
Authors: Beiswanger Christine M. , Sokolove Phillip G. , Prior David J. 
Published: June 2005

AbstractGarden slugs (Limax maximus and Limax flavus) exhibit a circadian locomotor rhythm which persists in constant darkness or light and in constant temperature with a period of approximately 24 hours, entrains to lightdark cycles (LD 12:12 or LD 16:8), and can be phase shifted by changes in the LD cycle. Results of experiments comparing the locomotor activity of blinded slugs and unoperated control animals indicate that the eyes are not necessary for either maintenance of rhythmicity or for LD entrainment. In DD, locomotor activity of blinded and control animals is robust, and the active period in a freerun projects back to the dark phase of the previous light‐dark cycle. Blinded animals remain entrainable to white‐light LD cycles and are able to follow a 6 or 12 hour phase shift. However, eyeless animals do not entrain to LD cycles of wavelengths greater than about 600 nm, whereas intact animals entrain without difficulty. In additon, there is an approximately 2‐hour increase in the phase angle difference of blinded animals compared to either sham or unoperated controls. These observations suggest that the eyes provide photic input to the slug circadian system, even though they are not essential components of the circadian oscillator that controls locomotor activity.
Wound healing in the imaginal discs of Drosophila II. Transmission electron microscopy of normal and healing wing discs
Authors: Reinhardt Christoph A. , Bryant Peter J. 
Published: June 2005

AbstractThe normal elements of the cell surface and the cytoskeleton of imaginal wing disc cells in third‐instar larvae of Drosophila melanogaster are described. This serves as a background for understanding the process of wound healing after experimentally cutting the two disc epithelia (columnar epithelium and peripodial membrane).The cells of both epithelial layers display microvilli at the apical surface, and there is a microvillar ridge at the periphery of each cell. The lateral cell surfaces display zonulae adhaerens, gap junctions, and septate junctions in characteristic patterns. A terminal web of 60–70‐Å microfilaments is located in the apical cell periphery, extends into the microvillar ridge, and is connected with the zonula adhaerens and probably also with the underlying belt of microtubules.Immediately after an incision is made in a normal disc, the two wound edges move apart to form a gape of about 45°. This fast wounding reaction is reversibly inhibited by treatment with cytochalasin B (0.5 μg/ml), suggesting that the wounding reaction is achieved by actinlike microfilaments. Initial wound closure results in an apposition of the columnar epithelium and the peripodial membrane (heterotypic contacts). Close (10–20 nm) heterotypic membrane contacts are found beginning at 12 hours after wounding, but cell junctions are not observed at such contact sites.Within 24 hours after wounding, the first focal cell membrane contacts are made between cells of corresponding epithelial types across the wound (homotypic contacts), at which time the heterotypic contacts are broken. At the time of epithelial healing, the wound surfaces shorten (“wound contraction”), and this is associated with cell‐shape changes within the epithelial cells along the wound. Within 48 hours after wounding, homotypic cell junctions and nonjunctional membrane contacts are fully reestablished, and wound healing is completed.We propose that the homotypic contacts between cells of the columnar epithelium are involved in the intercellular interactions controlling pattern regulation in the imaginal wing disc.
The hatching enzyme of Fundulus heteroclitus
Authors: DiMichele Leonard , Taylor Malcolm H. , Singleton Rivers 
Published: June 2005

AbstractThe chorionase (hatching enzyme) of Fundulus heteroclitus digests the chorion by producing water soluble peptide fragments. The chorion may be labeled with 14C‐iodoacetamide so that the soluble products of digestion are also labeled. We used this labeled substrate as the basis for a quantitative assay for chorionase. Chorionase was found to be quite stable at temperatures below 30°C and had a Q10 of 2.2 between 15 and 30°C. The pH optimum for enzymatic activity was between pH 8.0 and pH 8.5, and an ionic strength optimum was found between 0.1M and 0.2M. The enzyme was inhibited at ionic strengths similar to those found in sea water. Chorionase was also inhibited by divalent cations, EDTA, and PMSF. These results suggest that divalent cations are necessary for activity even though they are inhibitory at concentrations above 10mM.
Inhibition of in vitro fertilization of mouse eggs: 3‐quinuclidinyl benzilate specifically blocks penetration of zonae pellucidae by mouse spermatozoa
Authors: Florman Harvey M. , Storey Bayard T. 
Published: June 2005

AbstractThe fertilization in vitro of mouse eggs with intact zonae pellucidae by mouse cauda epididymal spermatozoa was inhibited in a concentration‐dependent fashion by 3‐quinuclidinyl benzilate (QNB), normally used as a specific antagonist for the muscarinic class of cholinergic receptors. Inhibition was observed with both cumulus‐intact and cumulus‐free preparations. QNB at 50 μM inhibited fertilization of cumulus‐free eggs by greater than 90% but had no effect on the fertilization of zona‐free eggs. At this concentration, QNB had no adverse effect on sperm motility, nor did it prevent binding of spermatozoa to the zona pellucida. The inhibitory effects of QNB were fully reversible. QNB is therefore a useful specific inhibitor of zona penetration. Spermatozoa in the in vitro fertilization medium bound QNB with a concentration dependence which matched that of the inhibition of fertilization. This binding was saturable and corresponded to 700 pmole/107 cells with KD = 10 μM. The in vitro fertilization medium contains 2% (w/v) bovine serum albumin (BSA) which also binds QNB according to the mass action law. The large amount of QNB bound to sperm in this medium appears to be QNB binding to BSA adsorbed on the sperm cell surface: these spermatozoa bind QNB specifically in the absence of BSA with a saturable capacity of only 70 fmole/107 cells with KD = 5 nM. Calculation of the distribution of QNB between BSA binding sites and sperm surface binding sites in the in vitro fertilization medium indicates that the specific sperm sites become saturated with the same concentration dependence as inhibition of fertilization. However, the dissociation rate of QNB from sperm in both the presence and absence of BSA is too rapid to permit confirmation of these sites as the locus of the inhibitory effect; this locus remains to be clarified.
The fertilization performance in vivo of rabbit spermatozoa capacitated in vitro
Authors: Viriyapanich P. , Bedford J. M. 
Published: June 2005

AbstractAlthough mammalian spermatozoa can be capacitated in vitro appropriately for the accomplishment of fertilization in vitro, it has not been established whether such spermatozoa can fertilize immediately in the Fallopian tube nor whether their fertilizing ability is comparable to that of spermatozoa capacitated in vivo. Rabbit spermatozoa treated here in a way reported to capacitate them for fertilization in vitro (20 min in high ionic strength medium (HIS) of 380 mOsm/kg at 37°C) could not penetrate eggs in the Fallopian tube unless allowed a considerable time for further capacitation in the female tract. Thus, while it may initiate the events of capacitation, HIS treatment clearly does not complete the process. Spermatozoa cultured for 12 h under another set of defined conditions (BSA‐free medium +20% serum under oil equilibrated with 5% CO2 + 8% O2 at 37°C) did fertilize eggs in 7 of 14 trials, however, when inseminated 12–15 h post‐hCG. Therefore capacitation that allows fertilization in vivo soon after insemination can be achieved in at least some spermatozoa, largely and perhaps entirely in the absence of factors from the female tract. Nonetheless, the performance of the 12h in vitro spermatozoa (29% of 131 eggs fertilized: 0.3 perivitelline spermatozoa/egg) compared poorly with that of 10 times fewer uterine spermatozoa in the contralateral oviduct (81% of 43 eggs fertilized: 15 perivitelline spermatozoa/egg). Moreover, in a final series, 12 h in vitro capacitated spermatozoa failed to compete directly for ova if inseminated together with many fewer labeled uterine spermatozoa, even though they fertilized significant numbers when inseminated alone into the contralateral oviduct.Current in vivo and in vitro fertilization systems for the assay of rabbit sperm capacitation are not entirely comparable because the penetrable life of rabbit ova is short in the Fallopian tube but prolonged in culture. Since fully capacitated spermatozoa begin to penetrate eggs almost immediately, assay of the capacitation status of spermatozoa of the rabbit or indeed of other species might best be evaluated within about 3 hours of gamete mixing. Such a limitation on the time allowed for sperm‐egg interaction in capacitation assays would minimize the possibility for completion of capacitation by factors present in the fertilization assay system.
Inhibition of two homeotic mutants of Drosophila by 5‐bromodeoxyuridine and fluorouracil
Authors: Ibars George C. , Selick Harold E. , Kauffman Stuart A. 
Published: June 2005

AbstractNasobemia (Ns) and spineless‐aristapedia (ssa40a) are dominant and recessive homeotic mutants of Drosophila which convert parts of the antenna to leg structures. Exposure of Ns and ssa40a larvae to half‐lethal concentrations of 5‐bromodeoxyuridine (BUdR) and flourouracil (FU) together or separately during the presumptive time of gene action suppresses the expressivity and penetrance of the mutants.
Experimental analysis of the lens‐forming competence of the cornea, iris, and retina in Xenopus laevis tadpoles
Authors: Bosco Luigi , Filoni Sergio , Paglioni Silvana 
Published: June 2005

AbstractThe present research was carried out using Xenopus laevis tadpoles at stage 50–51 to ascertain whether eye territories other than the outer cornea and the pericorneal epidermis have lens‐forming competence, particularly the iris and/or retina. Five experiments were performed: simple lentectomy; removal of lens, outer cornea, and pericorneal integument; removal of lens, outer cornea, and pericorneal integument, and simultaneous incision of retina; removal of lens, outer cornea and pericorneal integument, and simultaneous incision of dorsal iris; removal of lens and simultaneous lesion of iris and retina. Results show that when lentectomy is performed without damaging any territories other than the outer and inner cornea, lens regeneration is always from the outer cornea, and the iris and retina do not exhibit any lens‐forming competence. The iris and retina show no clear‐cut lens‐forming competence even after they have been stimulated by comparatively extensive lesions.
Aberrant spermiogenesis in X‐linked male‐sterile mutants of Drosophila melanogaster
Authors: Dybas Linda K. , Tyl Barbara T. , Geer Billy W. 
Published: June 2005

AbstractMales expressing mutations of fertility genes situated in sections 19 and 20 of the X‐chromosome of D. melanogaster were examined to identify the genetic lesions. ms(1)16, located in 20B‐C, affected pre‐meiotic events and caused ultrastructural abnormalities of the axoneme and of the major mitochondrial derivative during spermiogenesis. ms(1)1, situated in 19F1–20A1–2 to 20A1–2–20B, influenced the stability of the axoneme. ms(1)14, located in 19E8–19F1 to 20A1–2, and ms(1)7, found in 19E6–8 to 19E8–19F1, did not effect detectable ultrastructural abnormalities in developing gametes. ms(1)4, located in 18F to 19C3–19E1, resulted in abnormal development of tbe paracrystalline body and elongation of the major mitochondrial derivative. The nature of the genetic defects makes it unlikely that these proximal genes act as components of a single regulatory unit.
Vision tuned to species bioluminescence emission in firefly Photinus pyralis
Authors: Lall Abner B. 
Published: June 2005

AbstractThe ERG spectral sensitivity of the dorsal sector of the compound eye in firefly Photinus pyralis possesses two maxima, one in the violet and the second in the yellow region of the spectrum, with a marked attenuation of sensitivity in the green resulting in a narrow yellow sensitivity identical in shape to the species bioluminescence emission spectrum. Since the spectral sensitivity curves of the lamina response obtained from eyes devoid of cornea and distal screening sleeve were similar to the ERG spectral sensitivity curves obtained form intact eyes, the distal screening pigment and the cornea cannot be implicated in causing the attenuation of sensitivity in the green.
Implanted cerebral ganglia produce supernumerary eyes and tentacles in host snails
Authors: Moffett Stacia , Austin Daniel R. 
Published: June 2005

AbstractIn the pulmonate snail Melampus bidentatus, cerebral ganglia from adult donors implanted into the hemocoel of adult host snails form connections with the host nervous system and periphery. In addition, approximately 50% of the implanted ganglia develop an eye on the surface of the ganglion, and approximately 25% of the host snails develop a supernumerary tentacle above the site where the implanted ganglion lies. The morphology of these sensory structures was examined by light and electron microscopy. Comparison of implant eyes with adult control eyes and regenerated eyes indicates that the same elements are present (cornea, lens, microvillar layer, pigment layer and cell layer), although implant eyes at four months and regenerated eyes at two months do not have pigment and microvillar layers as thick as the controls. The receptor cell structure is similar in all cases. The surface of the supernumerary tentacles is not as convoluted as that of control tentacles, but sensory cells and a neural link to the implant ganglion are present. An eye is often produced in the skin at the base of the supernumerary tentacle.
Drugs that block smooth muscle contraction inhibit in vivo ovulation in hamsters
Authors: Martin Gary G. , Talbot Prudence 
Published: June 2005

AbstractWe have demonstrated previously that smooth muscle cells (SMC) in the base of hamster follicles contract minutes before ovulation. The contraction of these cells correlates well in time with the development of a constriction in the base of the follicle. The purpose of this study was to determine whether contraction of SMC (1) produces this constriction and (2) is necessary for ovulation. We treated preovulatory hamster ovaries with six classes of drugs (lanthanides, calcium antagonists, local anesthetics, prostaglandins, cAMP modulators, and cytochalasin B) known to inhibit SMC contraction in other tissues. Drugs were injected into the experimental bursal cavity of a hamster 3 hours before ovulation; the contralateral ovary received no treatment and served as a control. Three hours after ovulation, the number of ruptured follicles on experimental and control ovaries were compared by light and electron microscopy. All the smooth muscle (SM) inhibitors, except those that affect cAMP levels and cytochalasin B, prevented (1) contraction of follicular SM, (2) constriction of the base of the follicle, and (3) ovulation. These results support the idea that contraction of follicular SMC constricts the follicle and is required for ovulation. The results further show that follicular SMC are activated by an influx of extracellular calcium and that prostaglandin F2α may be involved in promoting this contraction.
Ejection of algae in the green hydra symbiosis
Authors: McAuley P. J. 
Published: June 2005

AbstractGreen hydra appears to regulate strictly the symbiotic algae within its digestive cells. Numbers of algae in the Frome and Jubilee strains were not affected by either sulphate enrichment of the medium or starvation, although numbers of algae fell when photosynthesis was inhibited by darkness and /or DCMU, due to cessation of algal growth. Treatment with glycerol or the antibiotic trimethoprim caused ejection of algae; trimethoprim, but not glycerol, also inhibited algal growth. Glycerol and trimethoprim caused an increase in numbers of algae at the apical ends of digestive cells, and appearance of cohesive algal pellets in treated hydras' coelenterons and in the culture dish; in control hydra and those treated with darkness or DCMU, fewer algae were at the apexes of digestive cells, and no algal pellets were produced. It was concluded that ejection of algae is not the normal regulatory mechanism in the green hydra symbiosis, although the fact that certain treatments may cause algal ejection should be taken into account when algal proliferation is measured in green hydra.
Developmental expression of glucose and triose phosphate isomerase genes in teleost fishes (Brachydanio)
Authors: Pontier Paul J. , Hart Nathan H. 
Published: June 2005

AbstractThe ontogeny of glucosephosphate isomerase (GPI; E.C. 5.3.1.9) and triosephosphate isomerase (TPI; E.C. 5.3.1.1) isozymes in Brachydanio rerio, (zebra danio), B. albolineatus (pearl danio) and hybrids formed by their reciprocal crosses were examined by electrophoretic and spectrophotometric methods. The two species showed virtually identical adult, tissue‐specific distributions and developmental progressions for both GPI and TPI isozymes. The Gpi‐A and Tpi‐B loci were expressed in all tissues studied. The Gpi‐B locus was predominantly expressed in skeletal muscle and the Tpi‐A locus in eye, brain and ovary. The GPI‐A2, TPI‐A2, TPI‐AB and TPI‐B2 isozymes were continuously expressed from fertilization through 5 days postfertilization. The GPI‐B2 isozyme initially appeared at 35 hours postfertilization, temporally correlating with the early differentiation of trunk somite myoblasts. Spectrophotometric analysis of total GPI showed fluctuations in activity through 48 hours, followed by a steady increase through 4 days postfertilization. Total TPI showed increased activity by the end of gastrulation and a sharp rise in activity beginning at 25 hours postfertilization.Embryos of reciprocal hybrids between B. rerio and B. albolineatus showed that isozymes derived from the activation of the paternal Tpi‐B, Gpi‐A and Tpi‐A alleles were initially detected at 20, 25, and 48 hours following fertilization, respectively. The maternal and paternal isozymes of the Gpi‐B locus were synchronously expressed at 35 hours postfertilization. The pattern of GPI‐B2 expression in hybrids followed a pattern similar to that in intraspecific crosses.Exposure of B. rerio embryos to pulses of actinomycin D at various stages prior to 35 hours postfertilization showed that messenger RNA encoding the GPI‐B2 isozyme was first transcribed over a 14‐hour interval initiated during mid‐gastrulation. Translation of the GPI‐B2 message occurred during a 13‐hour period immediately preceding the embryonic expression of the GPI‐B2 isozyme. Our studies with Brachydanio indicate that several gene loci are activated at gastrulation and transcribe messenger RNA molecules coding for histospecific isozymes associated with later stages of organogenesis.
Magnetic field detection in sockeye salmon
Authors: Quinn Thomas P. , Merrill Ronald T. , Brannon Ernest L. 
Published: June 2005

AbstractPrevious research has indicated that lake‐migrating sockeye salmon fry have compass directional preferences, cued in part by magnetic fields. This paper reports the results of experiments designed to compare the magnetosensory system of salmon with those of other organisms. Unlike birds, the fry did not reverse their compass orientation 180° when the magnetic field's vertical component was inverted, but rather displayed northerly (31°) orientation similar to that of fry in two different control conditions (325° and 22°). These results agreed with the 349° bearing displayed in 1979.Magnetized material (implicated as possible transducers in the magnetosensory systems of bacteria, honeybees, and homing pigeons) was not found (<2 × 10−7 e.m.u.) in 26 out of 30 fry examined. The material in the other 4 was probably environmental contamination, and not part of a sensory system. The mechanism of magnetic detection in salmon remains unknown, but consideration of the evolution and life history of the fish provides some clues as to the possible nature of the mechanism.
Inhibition of the hamster sperm acrosome reaction by transmethylation inhibitors
Authors: Meizel Stanley 
Published: June 2005

AbstractTwo inhibitors of somatic cell transmethylation, homocysteine thiolactone (Hcy) and 3–deazadenosine (3–DZA), inhibited the acrosome reactions of hamster sperm in vitro. Hcy (250 μM) or 3–DZA (200 μM) inhibited acrosome reactions by approximately 30% after 4 hours of incubation with washed sperm in a capacitating medium containing epinephrine, taurine, and bovine serum albumin. Inhibition by 3–DZA decreased by 5 hours, but inhibition by Hcy did not. Incubation of sperm with the combination of both inhibitors inhibited acrosome reactions by nearly 60% at 4 hours, and did not appreciably decrease with time up to 5 hours. These results are the first to demonstrate that such inhibitors can interfere with the acrosome reaction and taken together with the effects of Hcy and 3 – DZA on somatic cells, suggest that sperm protein and/or phospholipid transmethylation is/are involved in capacitation and/or the acrosome reaction.