bluuebunny/crossref_metadata_2025_split huggingface dataset:
Survival and reproduction of the desert pupfish (Cyprinodon n. nevadensis) after acclimation to acid water
Authors: Gerking Shelby D. , Lee Raymond M. 
Published: June 2005

AbstractThe tolerance of desert pupfish, Cyprinodon n. nevadensis to acid water was tested by exposing a group of fish for 14 weeks to alkaline water resembling their natural habitat (pH 8.3) and another to sublethal acidity (pH 6.3). The difference in mean times to loss of equilibrium at pH 4.2 (sublethal = 19.2 ± 2.93 hours; control = 17.9 ± 5.37 hours) was not statistically significant, indicating a failure to acclimate to the sublethal acidity.A reciprocal transfer experiment was performed with a sublethal (pH 6.3) and a control group (pH 8.3) to learn whether reproductive performance would compensate for acid stress. Reproductive performance was measured by egg production (eggs gm−1 day−1) and frequency of egg laying. In the first portion of the experiment the two groups were acclimated to their respective conditions for 3 weeks prior to a 3‐week measure of reproductive performance. The two groups were then reversed and tested again for 5 weeks. Reproductive performance of a control group was monitored for the 11‐week experimental period. No adaptation of the reproductive function occurred, since the transferred controls and acclimated sublethals were not statistically distinguishable. The sublethal group did not recover its reproductive capacity after transfer to the control level, suggesting either that permanent damage to some portion of the oogenesis process might have been suffered as a result of the acid exposure, or that the recovery was delayed beyond the 5‐week duration of this portion of the experiment.
The hare and the tortoise: Metabolic strategies in cardiac and skeletal muscles of the skink and the chameleon
Authors: Guppy M. , Davison W. 
Published: June 2005

AbstractTwo lizards ‐ a skink capable of fast short dashes, and a chameleon, incapable of fast movement ‐ have been studied to determine the degree of metabolic diversity that exists in this group of reptiles. Oxygen uptake measurements, skeletal muscle histochemistry, and enzyme and metabolite levels in cardiac and skeletal muscles reveal that the skink has a higher metabolic potential, both aerobic and anaerobic, than the chameleon. The difference, however, is not as large as is indicated by the behaviors of the two lizards. Levels of citrate synthase and B‐hydroxybutaryl CoA dehydrogenase in the hearts of both the lizards are high and indicate mammalian‐level metabolic capabilities.
Evidence that ectoderm influences the differentiation of muscle in the limb of the embryonic chick
Authors: Searls Robert L. , Smith Allen A. 
Published: June 2005

AbstractIntact limb buds from stage 19 to 21 embryos differentiate to contain both cartilage and muscle in culture. If the limb ectoderm is removed, the limb mesoderm cells differentiate as cartilage and connective tissue but not as muscle. Intact limb buds from stage 19 embryos differentiate both cartilage and muscle when grafted to the chorioallantoic membrane, but differentiate only cartilage and connective tissue if the ectoderm is removed. The significance of limb ectoderm to muscle differentiation can be observed as late as stage 24. Both the prospective cartilage region and the prospective soft tissue region from the limb of a stage 24 embryo differentiate cartilage and muscle in the presence of limb ectoderm, but differentiate little, if any, muscle in the absence of limb ectoderm. The results indicate that the dorsal and ventral ectoderm have some influence on muscle differentiation.
Biochemical and immunohistochemical localization of alpha and beta keratin in avian scutate scales
Authors: O'Guin W. Michael , Knapp Loren W. , Sawyer Roger H. 
Published: June 2005

AbstractWe have determined the distribution of alpha and beta keratins in avian scutate scales using SDS‐PAGE and indirect immunofluorescence with non‐cross‐reacting rabbit antisera prepared to both alpha and beta keratins. Contrary to previous studies, we find that alpha keratin is definitely present in the epidermis of the outer scale surface as well as that of the inner surface and hinge region of the scale. In fact, all six alpha keratin polypeptides found in the whole scale epidermis are also present in epidermis taken exclusively from the outer scale surface. Three of these polypeptides demonstrate a specific enrichment in the epidermis of the outer scale surface when compared to the polypeptides of the entire scale epidermis. Immunofluorescence studies specifically localize the alpha keratins of the outer scale epidermis in the Stratum Basale and Stratum Intermedium, but the beta keratins are restricted to the Stratum Intermedium and Stratum Intermedium and Stratum Corneum.
Effect of polyamines on fertilization of mouse ova in vitro
Authors: Stanger J. D. , Quinn P. 
Published: June 2005

AbstractAfter a 1‐hour preincubation of epididymal mouse spermatozoa at a concentration of 2 × 106/ml in 0.23 mM spermine, the proportion of F1 (C57BL × CBA) mouse ova fertilized after 1 and 2 hours was significantly greater than with untreated spermatozoa. Spermine also significantly increased the proportion of ova fertilized at the sub optimal sperm concentration of 2 × 105/ml. The stimulatory effect was lost when the protein source in the fertilization medium was changed from human serum albumin V (HSA) to HSA crystalline. This provides indirect evidence that albumin is directly involved in the capacitation process and that the crystalline is more potent than the fraction V preparation. At equimolar concentrations, spermidine was partially and putrescine was totally inhibitory to fertilization. Mechanisms whereby spermine may affect metabolic activity or sperm‐zona binding are discussed. It is suggested spermine may also be present in ovulatory fluid and therefore could potentially be involved in fertilization in vivo.
Transmission and scanning electron microscopic studies of the human sperm chromatin decondensed by micrococcal nuclease and salt
Authors: Sobhon Prasert , Chutatape Chutima , Chalermisarachai Panpaka , Vongpayabal Pandung , Tanphaichitr Nongnuj 
Published: June 2005

AbstractThe human sperm chromatin was gently decondensed by treating the sperm heads sequentially with micrococcal nuclease and 2 M NaCl. All histones, about 10% of DNA, and a small amount of degraded protamines were released into the soluble fraction, leaving mainly nucleoprotamines in the pellet fraction. Transmission and scanning electron microscopic studies revealed that the nucleoprotamine pellet consisted of chromatin cords of two dimensions, viz., 330‐ to 420‐Å and 650‐ to 1200‐Å thick cords laced together by very fine strands of 60‐ to 80‐Å fibers; both types of cords appeared knobby and had zig‐zag patterns throughout their length. It appeared that these cords were derived from two types of sperm heads of approximately equal population; one type contained chiefly the thick cords and the other chiefly the thin cords. Further treatment of the pelletnuclease‐NaCl with urea and mercaptoethanol resulted in the dissociation of the thick into the thin cords and unravelling of the thin cords into smaller sized fibers; whereas the treatment of the pelletnuclease‐NaCl with DNAase I resulted in the disappearance of the 60‐ to 80‐Å fibers, and the remaining cords were chiefly of thick type together with the sperm head exoskeletons. From these results the packing order of the chromatin in human sperm was proposed.
Isolation of an Arbacia sperm fertilization antigen
Authors: Eckberg William R. , Metz Charles B. 
Published: June 2005

AbstractAntisperm antibody fragments (IFab) block sea urchin fertilization by inhibiting the acrosome reaction and consequently sperm‐egg attachment. We describe here a 68,000 dalton MW glycoprotein which neutralizes the fertilization‐inhibiting action of IFab. This glycoprotein is a minor component in SDS‐polyacrylamide gels of sperm membranes, but is greatly enriched in lithium diio‐dosalicylate extracts of the membranes. Final purification of the antigen was accomplished by elution from preparative SDS‐polyacrylamide gels. This glycoprotein is evidently the sea urchin sperm receptor which interacts with the egg jelly coat and acts as a “trigger” for the acrosome reaction.
Studies of phospholipase A2 related to the hamster sperm acrosome reaction
Authors: Llanos Miguel N. , Lui Chung W. , Meizel Stanley 
Published: June 2005

AbstractThis report describes studies of innate and exogenous phospholipase A2 related to the acrosome reaction of golden hamster cauda epididymal sperm in vitro. Two acrosome reaction‐inducing systems were used: a nonsyn‐chronous system with epinephrine, and a synchronous system with the protonionophore FCCP. After a high percentage of sperm had undergone AR (in both systems) an increased phosphatidylcholine hydrolyzing activity was found in incubation media supernatants after partial purification by Affi‐Gel Blue chromatography. A preliminary characterization demonstrates that the activity was stimulated by Ca2+, detectable at pH 7.4‐‐7.8, but not at pH 4.5, and inhibited by p‐bromophenacyl bromide and mepacrine. Thus, it appears that a phospholipase A2 was released as a result of the acrosome reaction. BSA purified by TCA precipitation and ethanol resolubilization (TCA‐BSA), utilized in both types of incubations did not contain associated phospholipase A2 activity, but did contain an associated phosphatidylcholine hydrolyzing activity. The nonphospholipase A2 activity was removed by further purification of the TCA‐BSA by Affi‐Gel Blue chromatography, but the resulting highly purified TCA‐BSA was still able to induce capacitation and acrosome reactions in hamster sperm at the same level as prior to column chromatography. Incubations of the sperm in the presence of a partially purified bee venom phospholipase A2 did not stimulate hamster sperm AR over control values in the presence of epinephrine, but did so in the absence of epinephrine (probably by mimicking the action of the innate sperm head phospholipase A2). These results provide further support to earlier studies from this laboratory suggesting the involvement of a sperm head phospholipase A2 as an important factor in the mammalian sperm acrosome reaction.
Avian feather morphogenesis: Fibronectin‐containing anchor filaments
Authors: Haake Anne Reeves , Sawyer Roger H. 
Published: June 2005

AbstractDuring feather morphogenesis anchor filaments, continuous with the basement membrane, extend deep into the dermis. We find that these anchor filaments give intense fluorescence with antifibronectin (FN) antibody, using indirect immunofluorescence and immunoelectron microscopic techniques. These filaments are abundant in the dermis of the developing feather germ, yet are not present in the dermis beneath the epidermis of the elevated feather primordia. We suggest that these FN‐containing anchor filaments function in establishing the epidermal placodes of feathers and/or the organization of the feather dermis.
Analysis of the Drosophila female sterile mutant, tiny, by means of pole cell transplantation
Authors: Dimario Patrick J. , Hennen Sally 
Published: June 2005

AbstractOogenesis in Drosophila females homozygous for the female sterile mutation, ty, is characterized by morphological abnormalities in both the somatically derived follicle cells and the germ line derived nurse cells and oocyte. In order to identify the target cells of the mutation, reciprocal pole cell transfers were carried out between ty and ty+ embryos. The resulting mosaic ovaries contained host and donor germ line cells derived from the pole cells but only host follicle cells. Our results show that ty is a germ line mutation. The ty follicle cells in cooperation with normal nurse cells and oocyte lead to the production of normal flies. Consequently, the follicle cell abnormalities in ty egg chambers result from the expression of the mutation in the nurse cells, oocyte, or both.
Effect of gonadotropins and prostaglandin on cumulus mucification in cultures of intact follicles
Authors: Phillips David M. , Dekel Nava 
Published: June 2005

AbstractFollicles of 28 day‐old prgnant mare serum gonadotropin (PMSG)‐primed rats, were cultured for up to 24 hours in the presence or absence of ovine gonadotropins, highly purified rat gonadotropins, dibutyryl cyclic AMP (dbcAMP), methylisobutylxanthine (MIX), choleratoxin (CT), or prostaglandin E2 (PGE2). The morphology of the cumulus‐oocyte complexes isolated from these follicles was subsequently examined with the light microscope. Cumulus mucification was studied under the different culture conditions using scanning electron microscopy (SEM) and the hyaluronidase sensitivity test. The features of the cumulus‐oocyte complexes in the control cultures did not change throughout the incubation period, while complexes from follicles incubated with LH, FSH, dbcAMP, MIX, CT, or PGE2 changed their appearance and accumulated extracellular mucoid material. Treatment of these cumuli with hyaluronidase resulted in lysis of the extracellular mucus and dispersal of the cumulus masses. The results of this study agree with our earlier observation that the maturation of the cumulus‐oophorus, which occurs in vivo following the LH surge, can be induced in vitro by either gonadotropins or cAMP. Prostaglandin E2 did not affect cumulus cells, unless incubated enclosed by their follicles. This suggests that this hormone may influence the cumulus cells indirectly, probably via other components.
Effect of hyaluronidase treatment on the distribution of cranial neural crest cells in the chick embryo
Authors: Anderson Cheryl B. , Meier Stephen 
Published: June 2005

AbstractThe cranial paraxial mesoblast is patterned into segmental units termed somitomeres. Recently we demonstrated the morphological relationship between the migratory pathways of cranial neural crest cells and the patterned primary mesenchyme of chick embryos (Anderson and Meier, '81). Since extracellular matrix, particularly hyaluronate, is also distributed in cranial crest pathways, embryos were given sub‐blastodisc injections of hyaluronidase just prior to neural tube fusion and neural crest migration to remove matrix. Histological sections of enzyme‐treated embryos showed that Alcian blue staining of hyaluronate was significantly reduced. Surface ectoderm appeared collapsed on the subjacent mesoderm as well. Examination of embryos with the scanning electron microscope (SEM) revealed that paraxial mesoderm remained segmentally patterned even though it appeared more condensed because of a reduction in intercellular space between mesenchymal cells. In enzyme‐treated embryos, the rostral crest cells spread over the dorsal surfaces of the first four somitomeres, as they would do normally. This distribution of neural crest cells occurs even when enzyme treatment interferes with neural tube fusion at that level. We conclude that 1) neural tube fusion is not a prerequisite for the timely release of cranial crest in the chick embryo and 2) that much of the organized hyaluronate‐rich matrix that lies in the path of cranial crest is not essential for crest emigration or patterned distribution.
Sperm penetration into rat ova fertilized in vivo
Authors: Phillips David M. , Shalgi Ruth 
Published: June 2005

AbstractThe mechanics of sperm entry into the oocyte were examined in rat ova fertilized in vivo. With the scanning electron microscope we observe that the spermatozoon is first associated with the oocyte by the region of the convex surface of the sperm head which is immediately anterior to the postacrosomal region. At this early stage the anterior tip of the sperm head is directed away from the oocyte surface. The spermatozoon subsequently appears to rotate so that it comes to lie on its “side.” The membrane over the sperm head becomes free of microvilli and a large incorporation cone is subsequently formed. It is concluded that in the rat initial fusion of sperm and egg probably occurs between the oolemma and the sperm plasmalemma over the equatorial segment of the acrosome at the convex surface of the sperm head which is just anterior to the postacrosomal region.
Regulation of melatonin in the retinae of guinea pigs: Effect of environmental lighting
Authors: Pang S. F. , Yu H. S. , Tang P. L. 
Published: June 2005

AbstractWe studied the effect of environmental lighting on the level of melatonin in the retinae of guinea pigs. Male pigmented guinea pigs were adapted to 12‐hour light: 12‐hour dark (with lights on at 0600 hours) for 2 weeks. In experiment 1, two groups of animals were decapitated at 1600 and 0400 hours. Melatonin was extracted from retinae and quantified by radioimmunoassay. A diurnal rhythm of retinal melatonin level per pair of retinae was demonstrated. In experiment 2, one group was subjected to an extended dark period (lights remained off after 0600 hours) while the control group remained on the normal photoperiod on the day of sacrifice. Both groups were killed at 1200 hours. The retinal melatonin level in the group under extended dark period was significantly higher (P < 0.05) than that of the control. In experiment 3, one group was exposed to an extended light period (lights remained on after 1800 hours) and the control group remained on the normal lighting schedule. Both groups were killed at 2400 hours. The retinal melatonin level in the group exposed to an extended light period was significantly lower (P < 0.05) than that of the control. Thus, darkness induces an increase while light causes a decrease in retinal melatonin level.
The “ventral organ” of Jasus paulensis (Crustacea, Decapoda)
Authors: Vranckx R. , Durliat M. 
Published: June 2005

AbstractA “ventral organ” mainly made up of lipoprotein cells is observed in Jasus paulensis and all the Decapoda we have been studying. It is extensive during the early premolt stages because of the development of both number and size of cells. Sometimes, the presence of smaller finely granular cells is noted, chiefly in early premolt stages. Crystals are visible from stage D1′ to stage D2 in extracellular spaces between the “adipocyte type cells.” They are postulated to be calcium deposits. The “organ” contains many lipids; most of them are phospholipids (phosphatidyl‐choline, phosphatidyl‐ethanolamine) but a few are neutral fats. This “organ” seems to be only a preferential site for the accumulation of adipose tissues. The functions of this ventral tissue as well as those of the cyclic adipose tissue are discussed in relation to the storage of materials, synthesis of lipoproteins, and general metabolism in Crustacea.
Wavelike propagation of stretching and shrinkage in the surface of the newt's egg before the first cleavage
Authors: Sawai Tsuyoshi 
Published: June 2005

AbstractSmall carbon particles were attached to the surface of uncleaved fertilized eggs of the newt, Cynops pyrrhogaster, to analyze movement of the egg surface. Distances between pairs of particles were measured on still pictures photographed at intervals of 5 minutes. Measurements were made parallel to the cleavage furrow and perpendicular to it. The surface of the animal pole region began stretching about 40 minutes before the first cleavage, and then shrank about 20 minutes later. The phases of surface‐stretching and ‐shrinkage propagated from the animal pole toward the equatorial region. The shrinking region was observed in the photographs as a narrow circular zone of more concentrated pigment which was probably the second surface contraction wave found by Hara ('71).
Structural cell number and regeneration in Chlorohydra viridissima
Authors: Shostak Stanley 
Published: June 2005

AbstractRepresentative Chlorohydra viridissima were cut so that head‐end pieces had different structural cell numbers and tentacle numbers. Structural cell number was calculated from cell counts on macerated preparations. The number of tentacles regenerating on these pieces changed significantly as a function of the structural cell number, but not the tentacle number on the original pieces. The interaction term for the original tentacle number and structural cell number on tentacle regeneration was also significant. Foot regeneration on the head‐end pieces was a function of the length of pieces and mutually exclusive with the formation of tentaclelike basal spikes and the repolarization of pieces whereby an original tentacle became a basal structure. The number of tentacles regenerating on the basal stump peaked at one‐quarter the length of the gastric region in violation of expectations based on gradient models of morphogenesis. Structural cell number appears to be a major morphogenic determinant in regenerating Hydra.
The peripheral generation of action potentials in excitatory motor neurons of a crab
Authors: Lazarus Robert E. , Stephens Philip J. , Mindrebo Norman 
Published: June 2005

AbstractThe effects of temperature on the firing patterns of the excitatory motor supply to the bender muscle were examined in autotomized walking limbs of the crab Pachygrapsus crassipes. A brief electrical shock applied to the limb nerve evoked an action potential in one or both of the excitor axons and an excitatory junctional potential (ejp) in the bender muscle fibers. However, at high temperatures a single shock to one of the excitor axons (E2) resulted in a short train of nerve spikes and a concomitant burst of ejps. Extracellular recordings made from two sites along the E2 axon demonstrated that the additional action potentials are generated peripherally. Furthermore, myogram recordings from bender muscles in untethered animals indicate that peripheral generation of spikes does take place in intact crabs exposed to high temperatures.The peripheral generation of action potentials exhibited a critical temperature threshold which could be altered by acclimation and by low levels of ethanol in the saline bathing the autotomized limb preparation. This phenomenon may, therefore, be closely associated with membrane fluidity.
Sperm interaction with the zona‐free hamster egg
Authors: Binor Zvi , Sokoloski Joseph E. , Wolf Don P. 
Published: June 2005

AbstractThe interaction of sperm with the zona‐free hamster egg was studied. Hamster sperm were capacitated in Tyrodes media, containing 50% heat‐inactivated serum and used to inseminate zona‐free eggs in BWW containing 10% serum. Capacitated sperm began fusing with eggs within the first hour of insemination and by 3 h penetration had ceased as indicated by the absence of further changes in the mean number of sperm incorporated per egg. Penetration by capacitated hamster sperm was linearly related to the log of the motile sperm concentration at concentrations above 104 cells/ml. The viability of sperm and eggs in culture was limited in these studies to approximately 3–5 h. The existence of a block to unlimited sperm penetration of the zona‐free egg was sought in reinsemination experiments. A relatively low sperm concentration was used to initiate egg responses, followed, at timed intervals, by reinsemination with a high challenge concentration of sperm. Subsequent polyspermy levels reflected the presence or absence of the egg's block to polyspermy response. In order to circumvent the problems arising from the rapid aging of hamster sperm in culture, mouse sperm were employed, a convenience afforded by the lack of species specificity in this egg. Reinseminated eggs incorporated additional sperm during the challenge; therefore, the hamster egg is not capable of preventing unlimited sperm penetration. The implications of these findings to the use of the zona‐free hamster egg test in fertility evaluation is discussed.