bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cholinesterase in the Cnidarians Velella velella (Hydrozoa: Syphonophora) and Actinia equina (Anthozoa: Actiniaria): A comparative study
Authors: Talesa Vincenzo , Principato Giovanni B. , Mangiabene Carla , Giovannini Elvio , Norton Scott J. , Rosi Gabriella 
Published: June 2005

AbstractSoluble cholinesterases were purified from the cnidarians, Velella velella (Hydrozoa), and Actinia equina (Anthozoa), using 100,000g supernatants of total homogenates by affinity chromatography on a procainamide‐containing gel. An overall purification of 2,340‐ and 1,970‐fold, respectively, was achieved with an about 10% final yield. Both purified enzymes (relative molecular mass: 300 kDa, V. velella; 330 kDa, A. equina) seem to be tetrameric proteins consisting of four apparently identical or quite similar monomers. According to the values of kinetic constants, kcat and kcat/Km values, both enzymes are acetylcholinesterases. However, on the basis of kinetic and inhibition studies, the cholinesterase from A. equina shows a poor substrate affinity and an approximately 20‐fold lower catalytic efficiency in comparison with the enzyme from V. velella. These findings suggest in the former a less specific and relatively unspecialized conformation of the active site. Such different features are likely due to particular adaptive patterns of cnidarians, also involving their nervous system. © 1992 Wiley‐Liss, Inc.
Homeobox DNA polymorphisms (RFLPs) in subterranean mammals of the Spalax ehrenbergi superspecies in Israel: Patterns, correlates, and evolutionary significance
Authors: Nevo Eviatar , Ben‐Shlomo Rachel , Beiles Avigdor , Hart Charles P. , Ruddle Frank H. 
Published: June 2005

AbstractHomeobox DNA polymorphisms (restriction fragment length polymorphisms, RFLPs) were first found in 13 individuals, and then in 121 subterranean mole rats of the Spalax ehrenbergi superspecies in Israel. Spalacidae are adapted morphologically to life underground apparently since Oligocene times, 30 million years ago. The superspecies S. ehrenbergi comprises four chromosomal species (2n = 52, 54, 58, and 60) displaying active speciation and dynamic adaptive radiation into four climatic regimes. A Hox‐1.1 and ‐1.5 polymorphism was found with EcoRI, where three of four individuals of the species 2n = 60 were lacking the diagnostic locus‐specific band present in all other nine individuals tested in the first stage. Next we found monomorphism in 121 animals in Hox‐2.1 digested with five six‐base recognition endonucleases (EcoRI, HindIII, BstEII, KpnI, BamHI, and one four‐base enzyme, TaqI). However, we found in the same 121 animals from 13 populations of the four species in Hox‐3.1 species‐specific TaqI polymorphism in two populations of 2n = 54, and HindIII polymorphism in five populations, three of 2n = 54 and two of 2n = 58. The homeobox polymorphisms found display significant correlations with the burrow microclimates of mole rats. Furthermore, they are significantly correlated primarily with diverse morphological variables, and secondarily with protein (allozyme) and DNA polymorphisms, but very little with physiological and behavioral variables. We suggest that in subterranean mole rats, the variation in microclimatic factors, particularly in more unpredictable xeric regions, may maintain genetic polymorphisms by diversifying selection in the developmental control homeobox genes Hox‐1.1, ‐1.5, and Hox‐3.1, affecting regulatory morphogenetic processes in evolution. By contrast, the Hox‐2.1 monomorphism suggests strong purifying selection for conservation across the superspecies over long periods of evolutionary times. © 1992 Wiley‐Liss, Inc.
Rapid proliferation of historecognition alleles in populations of a colonial ascidian
Authors: Yund Philip O. , Feldgarden Michael 
Published: June 2005

AbstractPrevious work on the distribution of historecognition alleles in botrylloid ascidians has revealed extensive polymorphism at this locus, but has yielded little information on the distribution of alleles among populations and the rate of allele proliferation within populations. We first present preliminary data on the genetics of historecognition in Botrylloides diegense, a West Coast native that was introduced to the East Coast in 1972. We then compare the distribution of alleles in 2 populations of different size in a Maine estuary. Finally, we compare the alleles in those 2 populations to the alleles in a population at Woods Hole, the site of the original introduction. Our results indicate that a small, peripheral population contains fewer alleles than a large population and suggest that alleles have proliferated rapidly since this species was introduced to the East Coast. The rapid proliferation of alleles reported here provides additional support for the hypothesis that historecognition systems are subject to frequency dependent selection in natural populations. © 1992 Wiley‐Liss, Inc.
Micromanipulation of cleaved embryos cultured in protein‐free medium: A mouse model for assisted hatching
Authors: Alikani Mina , Cohen Jacques 
Published: June 2005

AbstractA mouse model for studying anomalies of human embryonic hatching following micromanipulation is proposed. Initiation and completion of mouse blastocyst hatching was severely impaired (34/292; 12% and 28/292; 10%, respectively) with protein deprivation, resembling the situation in human in vitro fertilization. Hatching ability was restored when an artificial gap was introduced in the zona pellucida by micromanipulation at the cleaved embryo stage. This enabled 77% (285/371) and 36% (134/371) of the embryos to initiate and complete hatching in protein‐free medium. No differences were found in overall cell counts between the two groups of embryos. Transfer of micromanipulated blastocysts to pseudopregnant females resulted in development of healthy fetuses. © 1992 Wiley‐Liss, Inc.
Differential processing of the two prolactins of the tilapia (Oreochromis mossambicus) in relation to environmental salinity
Authors: Borski Russell J. , Hansen Mette U. , Nishioka Richard S. , Grau E. Gordon 
Published: June 2005

AbstractProlactin (PRL) is thought to play a significant role in the freshwater (FW) adaptation of euryhaline teleost fishes, including the tilapia, Orechromis mossambicus. Two PRLs (tPRL188 and tPRL177) have been characterized in the anteriormost portion of the tilapia pituitary, the rostral pars distalis (RPD; Specker et al., '85a,b; Yamaguchi et al., '88). Our studies were undertaken to determine whether the in vivo RPD content of tPRL188 and tPRL177 varied with environmental salinity. To this end, tilapia were reared from the period of yolk‐sac absortion for 7 months or acclimated for 21 and 35 days in FW or seawater (SW). In a parallel study, we also examined whether the release of the 2 tilapia PRLs from the RPD of FW or SW tilapia might be differentially sensitive to changes in medium osmotic pressure during 18–20 hr incubations. In agreement with earlier work, we found that the smaller tPRL177 molecule was present in greater quantities in the RPD of FW tilapia compared to the content in RPD of SW fish. For the first time, we show here that the content of tPRL188, like that of tPRL177, is also significantly greater in the RPD of FW fish compared to the quantity in RPD of SW tilapia. Nevertheless, the relative content or ratio of the 2 PRLs in the pituitary was dependent on rearing salinity. Thus, the relative content or ratio of the larger tilapia PRL to smaller PRL (tPRL188/tPRL177) in the RPD of FW tilapia was significantly higher (1.5:1) than that seen in SW fish (0.75:1). This ratio was not altered after 18–20 hr in vitro incubations in hyposmotic or hyperosomtic medium, suggesting that the shift in ratios did not result from differential release by osmotic pressure. During 18–20 hr incubation in either hyposmotic or hyperosmotic medium, the RPD of FW tilapia released more of both forms of PRL than did the RPD of SW fish. Consistent with previous studies, reductions in medium osmotic pressure within the physiological range of the tilapia stimulated the release of botg tPRL188 and tPRL177 from RPD of FW fish over levels observed during exposure to hyperosmotic medium. We report here, for the first time, that the reduction of medium osmotic pressure also stimulates the release of both tPRL188 and tPRL177 from RPD of SW fish. Throughout the experiments we did not observe differences between the release of tPRL188 and tPRL177 under our incubation conditions. The transfer of FW‐reared fish to SW and vice versa for 49 days altered the ratio of the 2 PRLs (tPRL188/tPRL177) to that observed in the RPD of SW‐reared and FW‐reared fish, respectively. Overall, our studies indicate that the processing of the 2 PRLs may be differentially sensitive to environmental salinity. © 1992 Wiley‐Liss, Inc.
Changes in brain gonadotropin‐releasing hormone, plasma estradiol 17‐β, and progesterone during the final reproductive cycle of the female sea lamprey, Petromyzon marinus
Authors: Bolduc Thomas G. , Sower Stacia A. 
Published: June 2005

AbstractChanges in ovarian morphology, brain gonadotropin‐releasing hormone (GnRH), plasma estradiol, and progesterone were examined during the 1988 and 1989 spawning migrations of the adult female sea lamprey, Petromyzon marinus. There were significant increases through time in brain GnRH (1989) and plasma estradiol (1988 and 1989), with progesterone levels fluctuating (1988 and 1989) during the freshwater phase of the spawning migrations. In 1989, brain GnRH and plasma estradiol levels gradually increased through time until just prior to spawning when levels decreased. During 1988, there were no significant changes in GnRH, which may reflect lower temperatures in that year. These data provide new information on brain GnRH during final maturational processes in the female sea lamprey. © 1992 Wiley‐Liss, Inc.
Limb amputation and heat shock induce changes in protein expression in the newt, Notophthalmus viridescens
Authors: Tam Ying K. , Vethamany‐Globus Swani , Globus Morton 
Published: June 2005

AbstractTraditional limb regeneration studies have been focused on events transpiring during or subsequent to the 24–48 hour wound healing stage. In this study, amputation‐induced changes in limb protein expression were identified during the first few hours following amputation of the limb. These changes included the elevated expression of several amputation‐induced proteins (AIPs). Exposure of newts to a temperature of 37°C also resulted in teh enhanced synthesis of several heat shock proteins (HSPs) in similar molecular weight ranges. However, the amputation and heat shock responses differed in terms of the relative levels of induction of the various protein size classes. Furthermore, amputation resulted in the induction of an array of proteins that differed from those induced by heat shock. Unlike HSPs, AIPs were found to be synthesized exclusively in the forelimb tissue and were not seen in brain, liver, hindlimb, or tail tissues of forelimb‐amputated animals. However, AIP synthesis was not localized to limb tissue adjacent to the amputation site but rather was found at similar levels throughout the entire forelimb area. Moreover, in unilaterally amputated animals AIPs were found in both the amputated limb and the unamputated, contralateral limb. In addition to induced proteins, amputation also resulted in the suppression of several protein species. The latter occurred rapidly following amputation and was localized within the forelimb tissue immediately adjacent to the amputation site but not in proximal limb tissue. © 1992 Wiley‐Liss, Inc.
A comparison of tritiated vitellogenins prepared by in vivo and in vitro techniques for studies of ovarian uptake in fish
Authors: Nagler James J. , Idler David R. , So Ying P. 
Published: June 2005

AbstractThis study provides a comparison between serum vitellogenins (VGs), which have been radiolabelled with tritium (3H) using two different labelling methods, for ovarian uptake studies in fish. Purified VGs from winter flounder (Pseudopleuronectes americanus) and rainbow trout (Oncorhynchus mykiss) were radiolabelled in vitro following reaction with [3H]succinimidyl propionate which resulted in stable high specific activity [3H]propionyl‐VGs. Radiolabelled VGs were also prepared in vivo by injecting female winter flounder and rainbow trout with estradiol‐17β and [3H] amino acids intraperitoneally, and subsequently harvesting the serum and isolating the [3H]VGs. In winter flounder the ovarian uptake after a single intravenous injection of either [3H]propionyl‐VG or [3H]VG into female fish was determined after two weeks. Winter flounde VGs, radiolabelled either in vitro or in vivo, were similarly taken up by the ovary during early and mid phases of the annual vitellogenic cycle. It was demonstrated that both [3H]propionyl‐VG and [3H]VG were processed into a 280,000 relative molecular mass protein (i.e. lipovitellin). The small size of the vitellogenic winter flounder ovarian follicle precludes their use for in vitro culture, therefore an experiment was performed using rainbow trout ovarian follicles. Rainbow trout [3H]propionyl‐VG and [3H]VG were similarly incorporated by defolliculated ovarian follicles after 2, 6, and 12 hours of in vitro culture. © 1992 Wiley‐Liss, Inc.
Photoentrainment of the circadian rhythm in the electroretinogram of the crayfish and its dependence on the sinus gland
Authors: Moreno‐Sáenz Enrique , Fuentes‐Pardo Beatriz , Hernández‐Falcón Jesús 
Published: June 2005

AbstractSinus gland participation on the phase relationship between the circadian rhythms of the response to light (electroretinogram, ERG) of the visual photoreceptors in the crayfish was studied. Chronic ERG recordings were simultaneously obtained from both eyestalks in intact and sinus‐gland‐deprived animals during free‐running conditions and during the application of external periodic signals that consisted of 12 hr of light and 12 hr of darkness, or 12 hr of darkness and 12 hr of light, light regimens. It was found that the sinus glands are indispensable for preservation of the main characteristics of the circadian rhythm in the ERG and for the maintenance of a tight phase relationship between the rhythms of both eyes under free‐running conditions and during the application of the 2 kinds of light regimen. It is concluded that the sinus glands play a determining role in the processes that confer an internal temporal order on crayfish. © 1992 Wiley‐Liss, Inc.
Genetic and experimental studies on a new pigment mutant in Xenopus laevis
Authors: Droin Anne 
Published: June 2005

AbstractWhite lethal (wl) is a recessive mutation affecting the differentiation of the three types of chromatophores in Xenopus laevis and eventually leading to the death of the mutants around stage 50. Melanophores appear at st. 33 but differentiate abnormally, remaining pale grey, and do not proliferate after st. 41. The rare xanthophores present contain only a few differentiated pterinosomes, and the iridophores consist of noniridescent white dots. When the albino gene (ap) is combined with wl, melanophores do not differentiate. Reciprocal heterotopic and orthotopic trunk neural crest grafts have shown that the defect is intrinsic to the neural crest cells but is not due, in the case of melanophores, to a tyrosinase deficiency as revealed by the dopa reaction. The mode of action of the gene, the abnormal pattern, and lethality are discussed. © 1992 Wiley‐Liss, Inc.
Protein kinase C modulators influence meiosis kinetics but not fertilizability of mouse oocytes
Authors: Lefèvre Brigitte , Pesty Arlette , Koziak Katarzyna , Testart Jacques 
Published: June 2005

AbstractThe role of protein kinase C (PKC) in the successive steps of mouse oocyte meiotic process was investigated. We have used either OAG, an analog of diacylglycerol, or mezerein, a nonphorbol ester diterpene, less tumor promoting than phorbol esters, as PKC activators, and staurosporine as PKC inhibitor. Cumulus‐free oocytes were cultured in minimum essential medium with each of these PKC modulators and maturation stages were screened every two hours until the end of the process. Both PKC activators prevented GVBD at each tested dose for 4 hr (OAG) and 8 hr (mezerein), and decreased the frequencies of PB oocytes. The inhibitory effects of both activators were dose dependent and reversible. The addition of OAG to the culture medium after GVBD occurence (i.e., after 4 hrs) did not affect PB extrusion whereas similar addition of mezerein significantly decreased the frequency of PB oocytes. Inhibition of PKC by staurosporine accelerated GVBD and increased the frequency of PB extrusion. When staurosporine was added after GVBD, PB extrusion occurred earlier but PB oocyte frequency was not increased. Fertilizability was not affected when oocyte maturation occurred in the presence of any of these substances despite the delay in maturation process. These results clearly indicate that the PKC pathway in involved in mouse oocyte meiotic process: activation of the enzyme would arrest meiotic process whereas its inhibition would participate in meiosis induction. © 1992 Wiley‐Liss, Inc.
Culture of postimplantation rat embryos in rabbit serum for the identification of the growth factor in fractionated rat serum
Authors: Usami Makoto , Nakaura Shinsuke , Kawashima Kunio , Tanaka Satoru , Takanaka Akira 
Published: June 2005

AbstractThe growth factor for postimplantation rat embryos was investigated on the basis of the serum species‐specificity in supporting embryonic development in culture. We used rabbit serum as a basal medium for the culture of head‐fold stage rat embryos, and examined the effects of various fractions of rat serum on their development. In rabbit serum alone, rat embryos developed poorly. With the rat serum ultrafiltrate of molecular weight (MW) < 300,000, embryonic development improved, but not with the ultrafiltrate of MW < 100,000. With dialyzed rat serum or the globulin fraction of rat serum, embryonic development improved, but the albumin fraction had no effect. It was concluded from these results that some macromolecular growth factor for cultured postimplantation rat embryos was present in the globulin fraction of rat serum. The molecular weight of this growth factor was estimated to be between 65,000 and 300,000. Rabbit serum was considered to be suitable as a medium for the identification of this growth factor. © 1992 Wiley‐Liss, Inc.
The ionophore‐induced acrosome reaction differs structurally from the spontaneous acrosome reaction
Authors: Watson P. F. , Plummer J. M. , Jones P. S. 
Published: June 2005

AbstractThe ultrastructure of the spontaneous acrosome reaction in ram spermatozoa has been compared with that induced by the ionophore, A23187. The spontaneous event was dependent on incubation for 4 h, on the temperature, and on dilution. Apart from the more rapid occurrence of the ionophore‐induced event, the mean diameter and distribution of vesicle size was also different. The ionophore‐induced vesicles were larger, more irregular, and heterogeneous in size compared with those occuring in the spontaneous acrosome reaction (average diameter 84 nm vs. 60 nm in the spontaneous acrosome reaction). These observations are interpreted in relation to capacitation. © 1992 Wiley‐Liss, Inc.
Secretion of prostaglandin F2α and E2 in vitro by the uterus of the American alligator (Alligator mississippiensis)
Authors: Dubois Daniel H. , Guillette Louis J. 
Published: June 2005

AbstractThis study determined whether uterine tissue of alligators produce prostaglandins F2α (PGF) and E2 (PGE) and examined the relationship between secretion of prostaglandins and reproductive stage. Uterine tissue from alligators (n = 8) was incubated in the presence of arachidonic acid (AA), banamine (B), arginine vasotocin (AVT), AA + AVT or incubation medium alone. Aliquots of the culture medium were collected at 0, 30, 60, and 90 min and at 24 h of culture. Secretion of PGF was not detected from uterine tissue collected from gravid alligators, whereas non‐gravid and post‐oviposition alligators secreted appreciable amounts of PGF. The addition of AA to uterine tissue from non‐gravid alligators increased secretion of PGF (P < 0.05), whereas AVT had no effect. Addition of AA or AVT decreased secretion of PGF and PGE by uterine tissue from post‐oviposition alligators (P < 0.05). Secretion of PGF and PGE by uterine tissue was greater from post‐oviposition than from non‐gravid and gravid alligators. Secretion of PGE from uterine tissue of non‐gravid alligators was not altered by AA or AVT. However, secretion of PGE from uterine tissue from gravid alligators increased in the presence of AVT and decreased when incubated with AA + AVT. Arachidonic acid alone did not significantly alter secretion of PGE in this group. This study demonstrated that uteri of alligators secrete PGF and PGE and production is related to reproductive status. © 1992 Wiley‐Liss, Inc.
Assembly and disassembly of axonal microtubules of the toad Xenopus laevis under the effect of temperature
Authors: Alvarez Jaime , Fadić Ricardo 
Published: June 2005

AbstractIn toads Xenopus laevis living at 11° (winter), the microtubular density of 4‐μm myelinated axons of lumbosacral nerves was assessed with the electron microscope. In controls, the density was 11.2 microtubules/μm2. In nerves incubated at 0°, microtubules decreased following a simple exponential curve with a half time of 4.7 min (k = 0.149 min−1); residual microtubules were 4.5%. After rewarming, the full complement of microtubules reappeared within 60 min. In steady state, the microtubular density exhibited a linear relationship with temperature (range: 0–22°;slope 0.94 microtubules/μm2 per degree; r, 0.96). After heating the nerve by 11° above the physiological temperature, microtubules increased by 83%, whereby the pool of unpolymerized tubulin was at least 2.7 mg/ml of axoplasm. A seasonal variation of the microtubular density was observed which accorded with the environmental temperature. The macroscopic kinetics of microtubule disassembly in the axoplasm is similar to that reported for purified tubulin but that of assembly is slower. Microtubules of peripheral axons of Xenopus are cold‐labile and vary during the annual cycle. © 1992 Wiley‐Liss, Inc.